CA1225793A - High molecular weight water-soluble polymers and flocculation method using same - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A high molecular weight, water-soluble polymer, water-in-oil emulsions thereof and a flocculating process using same are disclosed. The polymer may be represented by the formula:

wherein A represents a repeating unit derived from a hydrophobic vinyl monomer having a water-solubility of less than about 5 weight %; R1 and R3 are each a hydrogen atom or a methyl group; R4 and R5 are each a hydrogen atom, a methyl group or an ethyl group; R2 represents a divalent hydrocarbon group having from 2 to 13 carbon atoms; X represents a monovalent cation; B
represents a repeating unit derived from an ethylenically-unsaturated carboxylic acid or a salt thereof; m is about 0.1-10 mole %, n is about 1-40 mole %, p is about 20-98.9 mole %, and q is about 0-40 mole % with the proviso that m + n + p + q = 100 mole % and r is a large positive integer.

D-13,858

Description

~2;~ 93~ D-13858-(:

TITLE OF THE INVENTION

HIGH MOLECULAR WEIGHT
WATER- SOLUBLE POLYMERS AND FLOCCULATION

-BACKGROUND OF THE INVENTION

Field of the Invention This invention relates to water-soluble acrylamide containing polymers and their use in, for example, flocculation of waste mineral processing streams.

Descripticn of the Prior Art In a number of mining industries such as copper, iron (taconite), ptash, phosphate, coal, etc., waste products from the ore processing present serious disposal problems.
For example, in the phosphate mining industry, processing leads ~o about one-third recoverable phosphate rock~, about one-third sand tailings and about one-third fines of generally less than 150 mesh particle size. Aqueous ~ 3 suspensions of these ultrafine solids, which are associated with the ore, and which result from the processin~, are referred to as ~slimes.U In the central area of t}le State of Fl-orida, where a large portion of the U.S. phosphate mining industry exists, the problem of ~isposal of these slimes has become a major problem. The slimes may be contained in ponds cr impounded areas surrounded by earthen dams and allowed to settle by gravity. However, this process takes a number of years.
lQ Alternatively, flocculants may be employed to concentrate the suspended solids.

Similarly, in the coal mining industry, large amounts of so-called ~blackwater~ are generated as a waste product of the coal cleaning plant operations. Such blackwater contains suspended coal fines and clays which desirably are removed prior to disposal or reuse o~ the water.

Mineral sli~es exhibit colloid-like properties that are believed to be largely responsible for their poor dewatering characteristics and generally comprise very fine colloid-like particles (e.g., clays) suspended in water which, in the case of phosphate slimes, are largely Montmorillonite and Attapulgite clays. Attapulgite and Montmorillonite clays together are known to comprise approximately one-third of a typical phosphate slime.
These clay materials are also well knoun for their colloid-like behavior when exposed to water~ They tend to absorb water or to associate with water and orm a ~uspended material which may be difficult to flocculate.

~ater-~oluble acrylamide polymers and copolymers are known as being useful for the flocoulation o~ such phosphate $1imes and blackwater ~u~pensions. ~or example, U. S. Patent No. 4,529,782 ~cribe6 ~ de-contain~
~f,'' .
~-13,858 :
.... . .

~L2257~3 polymers, having an intrinsic YiScosity of at least 15 dl/g, useful for flocc~lating phosphate slimes. ~he disclosed polymers may ~e terpolymers which may be represented by the following formula:

t H~ - C ~tC~2 - ~ ~CH2 - ~

NH2 0~
- R2~ d wherein R, Rl and R3 are independently hydroge~ or met~yl: R2 is an alkali metal ion, such as Na+ or K+ :
R4 is OR5, where R5 is an alkyl group having up to 5 carbon atoms, O O
Il 11 -O-C-R7, where R7 is eit~r methyl or ethyl, -C-O-R6, pnenyl, substituted phenyl, CN, or ~

and R6 is an alkyl group having up to 8 carbon atoms;
wherein a is from about 5 to about 90 mole percent, b is rom 5 to about g0 mole percent, c is from about 0.2 to about 20 mole percent, a~d d is an integer of from about 100,000 to about 500,000.

An example of such a terpDlymer is one derived ~rom a monomer mixture comprising about 54.3 mole percent acrylamide, about 4.6 mole ~ vinyl acetate and about 41.1 mole % sodium ~crylate.

Also disclo~ed in said ~x~e~d~ng U. S. Patent No. 4,529,782 are tetrapolymers obtained by the partial hydrolysis of ~he R~ group in the above ~ormul~.

,.
.~L~ D-13~858 ~;2S793 A process ~or flocculatin~
pho~phate slimes employing employing such polymers is dis-cioce-d in IJ.S. Patent No. 4,555,346- The disclosed process generally comprises MiXing a dilute aqueous solution of the polymer with the phosphate slimes under appropriate floc-forming conditions and allowing the suspended solids to settle from the slime to form an underflow of a more concentrated suspension of the clay solids and an essentially clear aqueous supernatant liquid.

Japanese Patent Publication No. 51-18913 describes a method of accelerating the aggregation/filtration of a fine mineral particle suspension using water-soluble terpolymers. These polymers are described as having a molecular weight above 1,000,000, preferably above 3,000,000, and comprise 5-50 weight % of a univalent salt of acrylic or methacrylic acid, 40-90 weight % of acrylamide, methacrylamide or methylol derivatives thereof, and 1-50 weight ~ of a weakly hyd~ophilic vinyl monomer. Table 1 therein describes a terpolymer prepared from 25 weight % sodium acrylate, 55 weight ~ acrylamide and 20 weight ~ vinyl ac2tate having a molecular weiyht of 1,500,000. GerMan Offenlegungsschrift No. 2,543,135 discloses similar polym~rs as flocculants.

Copolymers of about 75 weight 4 acrylamide and about 25 weight ~ sodium a~rylate are also known to be useful ~s flocculants in various aqueous ~ystems. U.S. Patent Nos.
3,790,476, 3,790,477, 3,479,282 and 3,479,284 disolose ~imilar ~crylamide/sodium acrylate copolymers and state tha~ they are useful as flocculants.

U.S. Patent ~o. ~,342,653 discloses a process for ~locculating ~ueous ~olid di~persions, ~uch as phosphate D-13,858 .
... ~,;~ .
i~ .' 1 1 ... .. . ,~ .. . . .. ... ..
. . .

~225793 slimes, with polymeric anionic flocculants comprising 40-99 mole % of repeating units derived from acrylamide, 1-35 mole % of repeating units derived from 2-acrylamido-2-methylpropane sulfonic acid (which is available from the Lubrizol Corporation under its product designation and here~te2 referred to as, ~AMPS"~ and 0-25 mole ~ of repeating units derived from acrylic acid.

U.S. Patent no. 3,692,673 discloses water-soluble sulfonate polymers said to be useful as flocculants for aqueous systems, especially in combination with inorganic co-flocculants. The polymers contain units of the formula:

R

C ", o NH
I

R - (S03M)x wherein ~1 is hydrogen or lower alkyl which may be substituted; R2 is a divalent or trivalent hydrocarbon or substituted hydrocarbon radical M is a hydrogen atom or one equivalent of a cation: and x is 1 or 2. The polymers may be obtained by polymerizing, either alone or in combination with other polymerizable vinyl monomers, a corresponding monomeric N-sulfohydrocarbon- subsSituted acrylamide (e.g. "A~IPSR or its alkali metal or ammonium 6alt). It is further disclosed that the most useful polymers are homopolymers of such monomers and copolymers thereof with 5-95 weight ~ of ~n acrylic monomer such as ~crylic or methacrylic ~cid or a salt or amide thereof (e.g., acrylamide). specific disclosed copolymers are 80 weight S sodium "AMPS/20 weight ~ ~odium ~crylate and 95 weight ~ sodium ~AMPS~/5 weight % ~crylamide.

Pi~ ~ D-13,858 ,. . ~

S~93 U.S. Patent No. 3,709,815 discloses copolymers of ~AMPS~
with acrylamide or acrylic acid as flocculants for aqueous systems. U~S. Patent No. 3,709,816 discloses flocculating alluvial deposits (e.g., silt) in water systems with "AMPS" or sodium ~AMPS~ water-soluble polymers, which may be "AMPS~ homopolymers or ~A~IPSn copolymers (containing at least 2 mole ~ "AMPS") with other comonomers, preferably acrylamide, acrylic acid, vinyl acetate, methyl acrylate or styrene. Other water-soluble monoethylenically unsaturated monomers which may be used include the alkali metal salts of acrylic and methacrylic acids, etc.

U.S. Patent ~lo. 3,975,496 discloses water-soluble copolymers useful as flocculants, especially in settling red mud obtained by the digestion of bauxite. The copolymers are, for example, acrylamide copolymers with either ~AMPS" or sodium acrylate wherein the acrylamide is partially methylolated.

Conversely, U.S. Patent Nos. 3,898,037 and 3,806,367 disclose acrylamido-sulfonic acid copolymers useful as dispersants or deflocculants for particles in aqueous systems. The copolymers (which have a molecular weight of 750 to 5,000,000) may comprise "AMPS" (or a salt thereof) copolymerized with a vinyl monomer, such as acrylic acid, esters thareof, acrylamide, vinyl acetate, etc.

Japanese Patent Publication No. 53-55488 discloses a flocculant comprising a water-soluble polymer containing about 90-99.8 mole ~ of an amide-type vinyl unit (e.~., acrylamide), about 0.1-5 mole % of a sulfonic group-containing vinyl unit (e.g., ~AMPS~ or its salt) and 0.1-5 ~ole % of a carboxyl group - containing vinyl unit (e.g., acrylic acid or its salt). The disclosed polymer is said to be useful for the sedimentation of used and waste water, for concentration, and for dehydration of various types of dirt.
D-13,858 ~Z;25793 Japanese Patent Publication No. 52-37580 discloses a method of aggregating solids suspendeZ in aqueous media employing an aggregating agent which comprises a copolymer which exhibits a strong tendency to form threads and which is obtained by polymerizing a mixture of 65-98 weight % of acrylamide and 2-35 weight % "AMPS~, where the total mono-mer concentration in the mixture is at least 15 weight ~.

Japanese Patent Publication No. 54-61285 discloses a method for preparing a polymeric aggregating agent wherein the wet polymer is heated at a temperature above the copolymerization temperature and then dehydrated and dried. The polymer is a copolymer containing 55-98 weight % of acrylamide and 2-45 weight % "AMPS" (or its salt) and optionally, up to 20 weight % of a thir~ copolymerizable monomer (e.g., sodium acrylate).

British Patent No. 1,437,281 discloses high molecular weight, water-soluble acrylamide polymers useful as flocculating agents for, e.g., mineral processing slimes.
The polymer comprises a~ least 50 weight % of acrylamide, 0-50 weight % of acrylic acid or its alkali metal salt and up to 5 weight % of other ethylenically unsaturated monor,~ers such as ~AMPS~ or its alkali metal salts.

British Patent No. 1,401,353 discloses the use of ~AMPSn -containing polymers as retention and drainage aids in paper manufacturing. The polymer contains at least 2.5 mole % ~AMPS" (or its salt) and 0-97.5 mole % o~ a comonomer such as acrylamide or sodium acrylate and, optionally, up to 20 mole % of other water-soluble comonomers and up to 10 mole % of water-insoluble comonomers.

U.S. Patent No. 4,024,040 discloses a radiation process for preparing water-soluble, high molecular weight D-13,858 ~2;~ 93 acrylamide polymers useful as flocculating agents. The polymer is prepared from an acrylamide-type monomer, or mixtures thereof, which monomer may be acrylamide, an alkali metal acrylate, 2-acrylamido-2-methylpropane-sulfonic acid ("AMPSn) or its salt, etc. No specific ~AMPSn - containing polymers are disclosed.

~est German Published (Non-Prosecuted) Application No.
1,442,408 discloses a flocculating a~ent comprising a copolymer of acrylamide and l to 10 ~ of compounds of the formula Il .
CH2 = C - C N - (C~12)n -Y
l l Rl R2 wherein Rl is hydrogen or methyl, ~2 is hydrogen or Cl 4 alkyl, Y is SO3X or O-SO3X, X is a monovalent cation such an alkali metal, and n is a whole number such as 2 or 3.
It has now been found that improved flocculation efficiency is obtained in aqueous systems such as phosphate slimes and coal blackwater when the water-soluble acrylamide polymers of the present invention are used as flocculants.
SUMMARY OF THF INVENTION

Broadly stated, the present invention comprises water-soluble acrylamide-containing polymers , water-in-oil emulsions of such polymers and the use of such polymers in flocculating aqueous solid suspensions such as phosphate slimes and blackwater derived from coal washing. The polymers of the invention may be represented by the D-13,858 ~Z257g3 following formula:
~m ~C~2 ~ C ~ f C~2 c~----~B~--C=O C=O

. R~ N \ _ r wherein A represents a repeating unit derived ~rom a hydrophobic vinyl monomer having a water-solubility of less than about 5 weight ~; Rl and R3 are each a hydrogen atom or a methyl group; R4 and R5 are each a hydrogen atom, a r.lethyl group or an ethyl group; R2 represents a divalent hydrocarbon group having from 2 to 13 carbon atoms; X represents a monovalent cation; B
represents a repeating unit derived from an ethylenically-unsaturated carboxylic acid or a salt thereof; m is about 0.1 - 10 mole %, n is about 1-40 mole %, p is about 2G-98.9 mole ~, and q is about 0-40 mole %, with the proviso that m + n + p + q = 100 mole %; and r is a large positive integer. Alternatively, the polymer may be defined as that resulting from the polymerization of a water-in-oil monomer emulsion containing r,lonomers corresponding~to the repeating units in the above formula in amounts of about 0.1-20 mole ~ of monomer ~A", about 1-40 mole ~ of the S03X-containing monomer, about 20-98.9 mole % of monomer CH2 = C - C - N - Rs and about 0-40 mole % of monomer "Bn, all based on the total moles of mGnomer in the emulsion.

D-13,858 "

~257~3~
-- 10 ~

The present invention also resides in a process for flocculatin~ an a~ueous solid suspension which comprises mixing the suspension with the above-identified polymer under appropriate floc-forming conditions and allowing the suspended solids to settle to form an underflow of a more concentrated suspension of the solids and an essentially clear aqueous supernatant liquid.

BRIEF DESCRIPTION OF THE DRAWINGS
Figures 1-3 sho~l the flocculation efficiency of terpolymers of the invention and three other polymers in three different phosphate slimes.

Figure ~ shows the flocculation efficiency of ~1) a sodium "A~IPSn/acrylamide/vinyl acetate terpolymer, (2) a sodium "AMPSn/acrylamide copolymer prepared by the dual-initiator process and (3) a prior art sodium "AMPS~/acrylamide copolymer, in a phosphate ~lime.
Figure 5 shows the flocculation efficiency, in a phosphate slime, of a sodium "AMPSn/acrylamide/vinyl acetate terpolymer and a sodium ~AMPSn/acrylamide copolymer prepared by the dual-initiator process.
Figure 6 compares the flocculation efficiency, in a phosphate slime, of three sodium "AMPSn/acrylamide~
vinyl acetate terpolymers (having differen~ vinyl acetate contents and a sodium "AMPSn/acrylamide copolymer prepared by the dual-initiator process.

Figure 7 shows the effect of the content of vinyl acetate, in various polymers, on flocculation efficiency.

D-13,858 ~25t793 DESCRIPTION OF THE PREFERRED EMBODIMENTS

As is apparent from the foregoing summary, the polymers of the present invention may be terpolymers (when q is zero) or tetrapolymers. Both types of polymers are useful in flocculating aqueous solid suspensions and the selection of which type, and of the particular monomers in each polymer, will vary depending upon, for example, the specific suspension being flocculated, economic considerations te.g., the cost of particular monomers), the desired rate of settling, and the desired degree of solids compaction, etc. These and other considerations will be fully discussed below so as to enable those skilled in the art to practice the present invention.
Vue to the fact that the polymers of the invention are often of very high molecular weight, it may be difficult to determine the precise content of the hydrophobic monomer unit "A~ in the polymer althoush there generally is no such difficulty in ascertaining the content, in the polymer, of the other monomer units. However, based on the known reactivity of a given hydropho~ic monomer "A~, the reactivities of the other monomers, the amount of all monomers present in the monomer emulsion to be polymerized and the polymerization conditions, the order of magnitude of the content of the hydrophobic monomer unit ~A~ in the resulting polyrner may be determined. For example, for a pre~erred terpolymer of the invention derived by polymeri-zing a water-in-oil monomer emulsion containing 8-12 mole % of sodium ~AMPS" monomer, 87-91 mole % of acrylamide monomer and about 1 mole % of vinyl acetate monomer, it is expected that the resulting polymer would contain a minimum of about 0.2-0.25 mole %, and probably close to that level, of total vinyl acetate (including unhydrolyzed and hydrolyzed vinyl acetate moieties). Therefore, the polymers of the invention may be described either in terms of the D-13,858 monomer content of the water-in-oil monomer emulsion polymerized to form such polymer, or in terms of the repeating unit contents of the polymer.

The polymers of the invention may be random or block copolymers although it is expected that they have both sections of random copolymer structure as well as other sections of block structure. It is not the purpose to limit the`present invention to any particular type of structure.

The terpolymers of the present invention may be represented by the following formula:

~ ~t- ~ C~2 - C ~ , ~ C~2 ~ C - -C=O C=O
~3 R4 ~ R5 r wherein:
(1) ~' represents a repeating unit derived from a hydrophobic vinyl monomer having a water-solubility of less than about S weight percent, such as those monomeric repeating units represented by the formula:

O O
Il 11 wherein R6 is -H or -CH3: R7 is - C - 0 - R8, - O - C - Rg, a halogen atom (e.g., chlorine), - 0 - Rlo or ~ Rll, D-13,85B

~5~793 where R8 is an alkyl group having from 1 to 12 carbon atoms, preferably 1 to 4 carbon atoms, most preferably a butyl group, R9 is an alkyl ~roup having from 1 to 4 carbon atoms, preferably a methyl group, Rlo is an alkyl group having from 1 to 6 carbon atoms, preferably from 2 to 4 car~on atoms, Rll is a hydrogen atom, a methyl group or an ethyl group, preferably a hydrogen atom or a methyl group. Examples of pre~erred hydrophobic vinyl monomers include vinyl acetate, styrene, alpha-methyl styrene, ethyl acrylate, methyl acrylate, ethyl methacrylate, methyl methacrylate, butyl acrylate, isobutyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, vinyl propionate, vinyl butyrate, propyl vinyl ether, butyl vinyl ether, methyl vinyl ether, ethyl vinyl ether, isobutyl vinyl ether, vinyl chloride, and vinylidene chloride.

(2) Rl and R3 are each a hydrogen ator,l or a ~ethyl group although it is preferred that both Rl and R3 are hydrogen atoms;

(3) R2 is a divaler.t hydrocarbon group having from 2 to 13 carbon atoms, such as alkylene yroups having from 2 to 8 carbon atoms, cycloalkylene groups having from 6 to 8 car~on atoms, phenylene, and the like. Preferred divalent hydrocarbon groups include -C(CH3)2-CH2-, -CH2CH2-, -~n2~n2~n2 , ~n2~n2~n2 2 ~ , CH CH2 , ~

and ~ C - . The most preferred R2 grouping I

is -C(CH3)2-CH2- which forms sodium ~lPS~ when Rl =
hydrogen and X is sodium;

D-13,858

(4) X is a monovalent cation such as a hydrogen atom, an ammonium group, an al~ali metal atom (e.g., Na or K), or an organoammonium group of the formula 15 16)( 17)NH+ where R15, R16 and R17 are each a hydrogen atom, an alkyl group having from 1 to 3 carbon atomsJ or a hydroxyalkyl group having from 1 to 3 carbon atoms, and the like. The pre~erred cation is a sodium atom.

(5) R4 and R5 are each a hydrogen atom, a methyl group or an ethyl group although it is preferred that both R4 and R5 are hydrogen atoms;

(6) m i5 about 0.1 - 10 mole ~, pre~erably about 0.2-5 mole %;

(7) n is about 1-40 mole %, preferably about 5-20 mole ~;

(8) p is about 50-98.~ mole %, preferably about 75-95 mole ~;

(9) m ~ n + p = 100 mole %; and

(10) r is a large positive integer, such as from about 1,000 to about 200,000. Generally, it is preferred that the polymer be a high molecular ~eight, linear polymer since both characteristics tend to favor improved flocculation. Due to the high reactivities of the monomers represented by the n and p moieties in the above formulaJ especially sodium ~AMPS~ and acrylamide, the formation of very high molecular weight, linear polymers may be readily accomplished. The molecular weight of the terpolymer (as well as the tetrapolymer) of the invention is generally greater than about 500,000 and preferably is greater than about 1,000~000.

D-13,858 ~L~2~i7gl3 Some of the acetoxy or alkoxy groups of R7 (i~e., the o - O - C - Rg, or - O - Rlo groups, respectively) may be hydrolyzed, resulting in a tetrapolymer which may be represented by the formula:
~ CH2--C t ~CH2 c ~ ~H2 C t ~CH2 c--t~
R7 m-z OH z C=O n C=O p NH R4R5 r _ R2 where~n Rl ~ R2 l R3 ~ R4 ~ R5~ R6~ 7~ , n , p and r are as defined above, and z is from about 0.1 to less than about 10 mole ~ and wherein (m' - z') + z' ~ n' + p' = 100 r,lole ~.

Alternatively, instead of defining the terpolymer repeating units as in (6) - (8) above, the terpolymer (and its hydrolyzed derivative) may be defined as that resulting from the polymerization of a water-in-oil monomer emulsion containing from about 0.1-20 mole %, preferably 0.2-10 mole ~ of Jnonomer A', about 1-40 mole %~
preferably about 5-20 mole ~, of the S03X-containing monomer, and about 50-98.9 mole ~, R3 l~ R4 preferably about 75-95 mole %, of monomer CH2 ~ C - C - N - Rs, all ba~ed on the total moles of monomer in the emuleion.

D-13,858 . ~, ..

. ~ ,, ~2;~5793 Examples of suitable S03X-containing monomers are "AMPS"
sodium "AMPSn, and the like~ The most preferred monomer is sodium "AMPS~.
. R3 R4 Examples of suitable monomers of the formula CH2 = C - C - N - R~
are acrylamide, methacrylamide, dimethylacrylamide, and the like. The most preferred monomer of this type is acrylamide.

The most preferred terpolymer is that resulting from the polymerization of a water-in-oil monomer emulsion containing about 8-12 mole % of sodium "A~IPS" monomer, about 87-91 mole % of acrylamide monomer and about 1-5 mole % of vinyl acetate monomer. Such terpolymers are especially useful in flocculating phosphate slimes.

The tetrapolymers of the present invention may be represented by the following formula:
A'-~ ~C32 - C ~ 3 L NH R ~ R5 ~rn _ I

' l' R2l R3, R4 and R5 have the same meaning as defined above with respect to the terpolymer of the invention; wherein m , n , and r have the same meaning as m , n and r , respectively, defined above with respect to the terpolymer of the invention; and wherein D-13,858 ~ ~5~3 ~ 17 -(1) p is ~bout 20-98.9 mole ~, preferably abo~t 40-86.9 mole ~;
. .
(2) q is greater than 0 and up to 40 mole ~, preferably about 10-30 mole %;

(3) B represents a repeating unit derived from an ethylenically-unsaturated monomer containing a carboxylic acid group such as acrylic acid, methacrylic acid, maleic acid, and the like and salts thereof with alkali metals (e.g., sodium, potassium, etc.) , ammonia (i.e., ammonium salts) and organic amines ~e.g., amines represented by the tR12)(R13)tR14)N- wherein R12, R13 and R14 are each a hydrogen atom, an alkyl ~roup having from 1 to 3 carbon ato~s, or a hydroxyalkyl group having from 1 to 3 carbon atoms such as trimethylamine, triethanolamine, etc.). Examples of suitable monomers include acrylic acid, methacrylic acid, maleic acid, sodium acrylate, ammonium acrylate, tri~ethylammonium acrylate, and the like. The preferred B monomer is sodium acrylate.

Some of the alkoxy or acetoxy groups of the hydrophobic monomer A' may be hydrolyzed, resulting in~a pentapolymer which may be represented by the formula: ~
~ } ~ I t { I t R7 m-z OH z C~O n C-O p NH ,N r _ i' R2 ~ a a where~n Rl~ R2~ R3~ R4~ R5~ R6~ 7~
and r are as defined ~bove, and z is from ~bout 0.1 to less than ~bout 10 ~ole ~;
~, ; D-13,858 . . . ... .... . . . .

~2~ 3 Alternatively, instead of defining the tetrapolymer repeatin~ units as above, the tetrapolymer (and its hydrolyzed derivative~ may be defined as that resulting from the polymerization of a water-in-oil monomer emulsion containing about 0.1-20 mole %~ preferably 0.2-lO mole 4 of monomer A', about 1-40 mole %, preferably abut 5-20 mole ~, of the So3X-containing monomer, about 20-98.9 mole %, preferably about 40-86.9 1 ll I
mole %, of monorner CH2 = C - C - N - R5, and greater than 0 to abo~t 40 mole %, preferably about 10-30 mole ~, of monomer ~B~, all based on the total moles of ~onomer in the er,lulsion.
The most preferred tetra~olymer of the invention is that resulting from the polymerization of a water-in-oil monomer emulsion containing about 6-lO mole % of sodium ~AMPSR monomer, about 50-70 mole % of acrylamide monomer, about l-5 mole ~ of vinyl acetate monomer and about 20-40 mole ~ of sodium acrylate monomer. Such t~trapolymers are especially useful in the flocculation of coal fines (e.g., blackwater).

The amounts of the sulfonic acid/sulfonate monomer and the oarboxylic acid/carboxylate monomer may be varied depending upon a number of factors. For example, an ~AMPS~ monomer is relatively more expensive than the carboxylic acid/carboxylate monomerO since the presence 3~ of both a strongly acidic group ~i.e., the sul~onic acid/sulfonate group) and a weak acid (i.e., the carboxylic acid/~arboxylate group) ~ay provide a ~locculant which ls more versatile for a broader range of applicatlo~s, the relative amounts may be tailored for particul~r ~ppli~a~ions ~nd therefore the tetrapolymers may provide both improved performance and better economy.

, y ~ D-13,85~
.~

3L225~7~3 }g The polymers of the present invention may be prepared using conventional techniques known to those skilled in the art, ~or example by standard water-in-oil emulsion polymerization processes. Such processes generally comprise emulsifying one or more water-soluble monomers in an oil phase and polymerizing the monomers in the resulting emulsion. It is preferred that the polymers of the invention be prepared as a w~ter-in-oil emulsion in order to provide linear, high molecular weight polymers which may nevertheless be recovered as solutions containing high polymer concentrations. Ordinarily, such polyrlers may best be prepared by water-in-oil emulsion polymerization processes, such as the process disclosed in U S. Patent No. 4,485,209.

The monorners polymerized to form the polymers of the present invention are either commercially available or may be prepared by processes known to those skilled in the art. For example, the So3X-containing monomers may be made by processes disclosed in U.S. Patent No. 3,506,707, the disclosure of which is hereby expressly incorporated herein by reference.

The water-in-oil emulsion polymerization process described in U- S. Patent N- 4,485,209 . which may be used to prepare the polymers of the present invention, comprises the steps of:

(a) co~bining: (i) an aqueous ~hase con~prising an ~queous solution containing at least one water-soluble monomer (i.e.~ the S03X-containing ~onomer, monomer D-13,858 7 ' ' "~'.). ' . . . . - ' .

t~3

11 1 CH2 = C - C - N - R5 and monomer "B"~, and (ii) an oil phase comprising a mixture of a hydrophobic liquid, a hydrophobic monomer (i.e., monomer A or A') and an oil-soluble surfactant;

(b) homogenizing the resulting mixture from (a) to form a water-in-oil emulsion followed by deoxygenating the emulsion;

(c) polymerizing the homogenized water-in-oil emulsion by adding thereto a deoxygenated initiator solution and heating the resulting mixture in a reactor under polymerization conditions so as to form a polymer water-in-oil emulsion; and (d) recovering a polymer water-in-oil emulsion.

A water-soluble surfactant may be added to the recovered water-in-oil emulsion to invert the emulsion on contact with water.

In the first step of the process, an aqueous solution containing one or more water-soluble monomers is combined with a mixture containing a hydrophobic liquid, a hydrophobic monomer and an oil-soluble surfactant. This combination of materials is homogenized to form a water-in~oil emulsion.
The ayueous solution contains a mixture of water-soluble monomers represented by the formulas D-13,858 Rl o H2C = C ~ C - ~IH - ~2 - SO3X, R3 o 1 ll ~ R4 H2C = C C - N ~5 and, optionally, B, where Rl, R2, R3, R4, R5 X and B are as defined hereinabove. The acids ~i.e., monomer ~B~ and the SO3X -oontaining monomer) may first be reacted with a suitable base~
preferably with an equivalent amount of base, such as sodium hydroxide, so that the resulting solution has a pH
of from about 5.0 tc about 10.0, preferably from a~out 6.5 to about 8.5, depending on the type and amount of base esnployed. The resulting solution may then be co~bined with another water-soluble monomer, such as acrylamide, and then with water to form the aqueous solution used in step (a).

The mixture which is combi~ed with the aqueous solution containing the water-soluble monomers contains a hydro-phobic liquid, a hydrophobic monomer (i.e., monomer A or A' as defined above) and an oil-soluble surfactant.

The particular hydrophobic liquid is not critical.
Examples of suitable hydrophobic liquids for use herein include benzene, xylene, toluene, mineral oils, kerosenest petroleum, ~ixtures thereof, and the like. A preferred hydrophobic liquid is an aliphatic hydrocarbon ~vailable from the Exxon Chemical Co. under the tradename Isopar M.
The particular surfactant is not critical. Exa~ples of ~uitable ~urfactants are those of the oil-soluble type having a Hydrophile-Lipophile Bal~nce (MLB) value of from ~bout 1 to about 10, preerably ~rom about 2 to abou~ 6.
~hese ~urfactants ~re normally re~erred to as the water-in-oil type. The~e ~uitable ~urfactants lnc:Lude D-13~858 - it~
~' ~ `'' i , ... .. ~ ............ . . .

fatty acid esters, such as sorbitan monolaurate, sorbitan monostearâte, sorbitan monooleate (such as that available from I.C.I. under its tradename Spa ~80), sorbitan trioleate, etc.; mono- and diglycerides, such as mono and diglycerides obtained from the glycerolysis of edible fats, polyoxyethylenated fa~ty acid esters, such as polyoxyethylenated ~4) sorbitan monostearate;
polyoxyethylenated linear alcohols, such as Tergitol 15-S-3 and Tergito ~25-L-3 (both supplied by Union Carbide Corp.); polyoxyethylene sorbitol esters, such as polyoxyethylene sorbitol bees~-ax derivative;
polyoxyethylenated alcohols such as polyoxyethylenated (2) cetyl ether, and the like.

The mixture of the aqueous phase and oil phase resulting from step (a) is homogenized to form a water-in oil emulsion. Homogenization takes place by subjecting the mixture to high shear mixing techniques which are generally well-kno~n in the art. These include the use of homosenizers, hlgh speed mixers and any other techniques for obtaining high shear mixin~. The homogenization is carried out at a temperature of from about,0 to about 30C, preferably about 15 to 25C. The homogenization may be carried out either continuously or in a batch process.
The emulsions so prepared have a rather narrow particle size distribution. The diameters of the majority of the particles range from about 0.2 to about 5 microns.

The resulting monomer water-in-oil emulsion comprises:

(a) from about 50 to about B0, preferably from about 60 to 78, weight percent, ~ased on the total weight of the emulsion, of an squeous phase containing the water-soluble monomers, wherein these monomers constitute ~rom about 20 to about 80, preferably from about 25 to about S0, weight percent of the aqueous phase:

D-13,B58 ~a2;~ii7~33 (b) from about lS to about 45, preferably from about 20 to about 40, weight percent, based on the total weight of the emulsion, of an oil phase comprising the hydrophobic liquid and hydrophobic monomer(s), wherein these monomers S constitute from about 0.1 to about 20, pre~erably from about 1 to 10, weight percent of the oil phase;

(c) from about 0.1 to about 5, preferably from about 1 to about 3, weight percent, based on the total weight of the emulsion, of the oil-soluble surfactant.

After forming the water-in-oil emulsion, either during or after addition to a reactor, it is generally deoxygenated by, for example, subjecting part or all of the emulsion to a vacuum of from about 50 to about 500, preferably from about 100 to about 200, mm of mercury under an inert gas atmosphere at a temperature of from about 0 to about 30C, either continuously or as a batch process.

A catalyst or initiator useful in polymerizing ethylenically unsaturated monomers is also added to the reactor. These catal~sts include azo-and peroxide-containing compounds known in the art and are added to the reactor either directly or in the form of a solution, i.e., the catalyst is dissolved in a sGlvent, such as a hydrocarbon liquid, e.g., toluene. The catalyst solution contains from about 1 to about 10, preferably from about 3 to about 6, weight percent of the catalyst.

From about 1 to about 99, preferably from about 20 to about 60, weight percent of the catalyst solution is initially added to the reactor containing the water-in-oil emulsion. The remaining water-in-oil emulsion and cata-lyst solution are then continually fed into the reactor.

D-13,858 ~L2;;~ 93 The polymerization is carried out at a temperature of from about 30 to about 100C, preferably from about 40 to about 70C, mo$t preferably from about 45 to about 55C, for about 1 to about 10 hours, preferably from about 2 to about 6 hours. The reaction time depends on the size of the reactor and the polymerization conditions.

Alternatively, all of the reactants may be charged into a reactor and the polymerization conducted in a batch operation.

The polymerization is generally carried out at atmospheric pressure, although subatmospheric and superatmospheric pressures may be used. The polymerization is preferably carried out under an inert atmosphere, such as a helium, argon or nitrogen atmosphere.

The polymerization reaction generates considerable heat which must be removed. Generally, the heat is dissipated by normal cooling facilities.

The polymerization reaction rate may be controlled by the introduction of small quantities of air (atmospheric air and/or oxysen) into the reaction. The air May be introduced, i.e., sparged, either intermittently or continuously into the reactor to control the reaction temperature. ~hen a continuous air sparging is employed, the amount of oxygen in the reaction mediuM must be carefully controlled so as to achieve the desixed rate of polymerization. An oxygen content of from about 0.01 to about 1.0, preferably from about 0.02 to about O.S0, part per million is desirable. When the air is introduced intermittently, a flow rate of from about 0.01 to about 1.0, preferably from about 0.05 to about 0.5 cubic inches D-13,858 - 24a -per minute per pound of reactor charge is desirableO The duration of air injection may vary from a fraction of a second to a few seconds, and it may be repeated as many times as necessary until a desired rate of polymerization is achieved.

D-13,85~

~22~;~93 ; 25 -After the poly~erization is complete~ an antioxidant may be added to the reaction mass. ~ny organic antioxidant suitable for the inhibition of free radical reactions may be used. The antioxidant is ~enerally dissolved in a suitable solvent. The preferred antioxidants include substituted phenols (such as tha~ available from Shell Chemical Co. under its tradename Iono~ ~ thiobisPhenol ~such as is available from the Monsanto Chemical Co. under its tradename santonox-lM-R~, and hydroquinone derivatives, such as the monomethyl ether of hydroquinone. The suitable solvents include toluene, benzene, xylene, diethyl ether, methyl acetate, and the }ike. ~he antioxidant is present in the solution in amounts of from about 0.1 to about 10, preferably from about 1 to about 5, weight percent.

The antioxi~ant solution is added to the reaction mass in amounts of from about 0.05 to about 5 parts per hundred parts of polymer. Addition of the antioxidant may be commenced either at the end of the polymerization or after the reaction mixture has been cooled to ambient temperature.

The reaction mass is senerally cooled to about 25C and the polymer water-in-oil emulsion recovered.

The resulting polymer water-in-oil emulsion generally comprises:

(a) ~rom ~bcut 50 to about 80, preferably from about 60 to about 78, weight per~ent, based on the weight o~ the entire emulsion, of an aqueous phase which oontains therein from about 20 to about 80, preferably from about 25 to about 60, weiyht peroent of polymer, based on the total wei~ht of the ~gueous phase;

~ 13,858 , ~ .

~2~7~3 (b) from about 15 to about 50, prefera~ly Irom about 20 to about 40 weight percent, based on the weight of the entire emulsion, of a hydrophobic liquid and (c~ frGr,l about 0.1 to about 5, preferably from about 1 to about 3, weight percent, based on the total weight of the emulsion, of an oil-soluble surfactant.

If desired, the polymer may be recovered by, for example, coagulation in a large excess of a non-solvent for the polymer, such as isopropyl alcohol. The polymer may then be collected by filtration and subsequently dried.

After the polyMer water-in-oil emulsion is prepared, a water-soluble invertins surfactant may be added thereto.
The polymer in the water-in-oil emulsion containing an inverting surfactant can be inverted in the presence of water releasing the polymer into the water in a very short period of time. The surfactants which may be used include polyoxyethylene alkyl phenol; polyoxyethylene (10 mole) cetyl ether; polyoxyethylene alkyl-aryl ether; quaternary ammonium derivatives; potassium oleate; N-cetyl-N-ethyl morpholinium ethosulfate; sodium lauryl sulfate;
condensation produces of higher fatty alcohols with ethylene oxide such as the reaction product of oleyl alcohol with 10 ethylene oxide units; condensation products of alkylphenols and ethylene oxide such as the reaction products of isooctylphenol with 12 ethylene oxide units; condensation products of higher fatty acid amines with five, or more, ethylene oxide units; ethylene oxide condensation products of polyhydric alcohol partial higher fatty esters and their inner anhydrides (e.g., m~nnitol anhydride, called Mannitan, and sorbitol anhydride, called Sorbitan). The preferred surfactants are ethoxylated D-13,858 ~a 22~7~33 nonyl phenols, ethoxylated nonyl phenol formaldehyde resins, and the like.

The inverting surfactant is used in amounts of from about 0.1 to about 20, preferably from about 1 to about 10 parts b~ weight per one hundred E)arts by weight of the polyliler.

Although the foregoing process may be employed, the pre~erred mode of preparing the polymers (i.e., both ter-and tetra-polymers) of this invention is by a novel dual-initiator uater-in-oil emulsion polymerization process disclosed in ~dian Patent Application Serial No. 448 159-3 The so-called dual-initiator process disclosed in said application differs from the process descr~bed in said U. S. Patent No. 4,485 209 in that two initiators are employed; a first, highly reà~ctive, low temperature initiator to provide a shear-stable erllulsion, and a second, less reactive initiator to complete tbe polymerization at higher temperatures. The presence of a small amount of polymer formed in situ at low temperatures by the action of the first initiator provides a highly stable emulsion resistant to degeneration b~ subsequent shearing and heating during the course of poly~erization at higher temperatures. Fur~her, product uniformity i6 greatly improved and gel Sormation i8 minimized and the 2c improved emulsion stability permits greater flexibility in process design and a broader operating latitude.

D-13,858 .. . . .

` ~Z2S7~33 ~`) - 28 - .

The first, highly reactive initiator may be a free radioal initiator capable of initiatiny polymerization of the mono~ers at a temperature between about 0 and 45C, preferably between about 20 to 40C to provide a small amount o~ polymer. The specific amount of polymer thus produced will vary dependlng upon the monomers employed, the polymerization conditions, etc, and will be that amount necessary to provide a shear-stable emulsion.
Examples of suitable initiators are azo compounds such as 2, 2 - azobis (2,4-dimethyl-4-methoxy-valeronitrile) and peroxy compounds such as potassium pers~lfate, sodium bisulfite, etc.

The second, less reactive initiator may be a free radical initiator capable of initiating polyr.lerization of the monomers at a temperature between about 40 to 100C, pr~ferably between about 45 to 80C. Examples of suitable initiators are azo compounds such as 2,2 -azobis (2,4-dimethylvaleroni~rile) and peroxy compounds such as benzoyl peroxide.

In the dual-initiator Process twhich is more fullv described in Canadian Patent Application Serial No.
448,159-3), the first initiator may be added to the reactor containing the water in-oil emulsion and, after polymerization has been initiated at a low temperature (i.e., during the heating up of the ~ontents of the reactor3 ~nd a small amount of polymer is ~ormed in ~he emulsion, the second initiator ~ay be ~dded th~reto ~nd the polymerization continued ~nd completed At ~ higher tempersture. Alternzt~vely, both the firxt and second ~nitiators ~ay be present ~n the reactor ~r~m the be~inning of the polymeriz~tion. ghe preferred ~ner of ~dding th* initiators is ~equenti~l (i.e., the s~cond be$ng added ~fter a small ~mount o~ polymer ls for~ed~.
....
.~j ~,L. `'~
D-13,858 7g3 - -- 2g -- .

An effective method for heat removal, and one which is preferred, especially in conjunction with the dual-initiator process, involves the use of an external heat exchan~er connected to the reactor through a closed loop. The reaction mixture may be circulated through the heat exchanger by a pump during the course of polymerization. Due to the fact that the dual-initiator process provides a shear-stable water-in-oil emulsion, such an external heat exchanger may be employed. Under ordinary conditions, without the improvemerlt afforded by the dual-initiator process, under the shear field generated by a high flow capacity pump, the stability of a conventional monomer emulsion is so marginal that such an operation cannot be carried out with any reasonable degree of reliability. In fact, emulsion breakdown often takes place at the early stages of polymerization leading to the formation of either coarse emulsion particles or gelation. Any conventional heat appa~atus rnay be used to provide the external heat exchange loop. It is preferred to employ such an external heat exchanger so as to afford the maximum removal or dissipation of the heat generated during polymerization. The foregoing advantages should be obtained, however, regardless of the mechanical design of the reactor system employed.
Another embodiment of the present invention resides in the use of the polymers of the invention in flocculating aqueous solid suspensions. The types of aque~us solid suspensions that can be treated in accordance with the present invention include phosphate slimes, suspensions derived from coal processing operations (such as so-called blackwater) and other mineral processing (waste) streams derived from mining of copper, iron (taconite), potash, kaolin and other clays, bauxite, etc., and other industrial waste streams such as paper fines, and the like.

D-13,858 ~.~Z~ii7~3 The present invention is particularly useful in flocculating phosphate slimes and coal blackwater suspension~ employing the polymers of the present invention.

As described above, the polymers of the inventi~n are preferably prepared in the form of a water-in-oil emulsion which contains the polymer in concentrated form within the aqueous phase. For purposes of the present invention, the concentrated water-in-oil emulsion may be inverted to form a concentrated polymer solution which may thereafter be diluted with additional water. The resulting dilute solution may be added to the aqueous solid suspension being treated under appropriate floc-forming conditions, and thereafter allowing the suspended solids to settle from the suspension to thereby form an underflow of a more concentrated solid suspension and an essentially clear aqueous supernatant.

The concentrated aqueous solution formed from the polymer water-in-oil emulsion described above generally contains from about 0.01 to about 1.0, preferably from about 0.1 to about 0.5, weight percent of polymer, based on the total weight of the solution. This concentrated solution is then normally further diluted with additional water to provide a dilute solution containing from about 0.0005 to about 0.1, preferably from about 0.~02 to about 0.05, weight percent of polymer, based upon the total weight of the dilute solution.
The dilute solution is then mixed with the aqueous solid suspension at one or more addition points. The amount of polymer solution employed will vary depending upon a number of factors, such as the type of aqueous solid suspension being treated, the desired rate of settling, degree of compaction and overflow clarity desired as well - as the particular polymer employed, etc. It is also D-13,858 ~LZZ~i793 obviously desirable to employ the lowest amount of polymer dosage necessary to achieve a given settling rate, degree of compaction or overflow clarity, but it is often difficult to fix effective ranges of flocculant dosages (expressed either in terms of the weight of polymer per unit weight of aqueous solid suspension or the amount of polymer necessary to achieve a certain settling rate) for certain types of solid suspensions. As an example, the composition and properties of phosphate slimes obtained frcr,l the saMe r,lining location may differ substantially.
However, generally speaking, it is commercially desirable to obtain underflow solids for phosphate slir,~es on the order of about 12 to 20 weight ~ solids using conventional - equipment and therefore the polymer flocculant dosage may be adjusted to achieve said degree of compaction.
Alternatively, the polymeric flocculants of the present invention may be employed in amounts of from about 0.05 to about 2.0 pounds ~of active poly~er) per ton of suspended solids, although higher or lower dosages may be employed depending on the difficulty of flocculating a particular slime. Similarly, for coal processing waste suspensions, the polymeric flocculant may be employed in amounts of from about 0.001 to about 2.0 pounds (of active polymer) per ton of solid coal fines in suspension to obtain settling rates of about 5 to 10 inches/minute. Dosages for other systems May be easily fixed by those skilled in the art for a particular polymer.

As indiated above, the dilute solution of polymer is added to the aqueous solid suspension under appropriate floc-forMing conditions, which include the appropriate or desired flocculant dosage, the concentration of t~e dilute flocculant solution, the selection of acceptable or desired mixing energies to achieve desirably large-sized flocs and the appropriate contact between the flocculant solution and the aqueous solid suspension. Upon addition D-13,858 ~22~ 33 . of ~he dilute flocculant solution und~er appropriate floc-forming conditions, rapid separation of the suspended solids begins to occur, and with time, the suspended solids are floccula~ed and settled, thereby forming an underflow of a more concentrated solid suspension and an essentially clear supernatant~

The following examples are intended to illustrate the present invention, sometirnes by comparison wi~h prior art poly~ers, and are based upon and de~cribe work that was actually performed. It is not intended to limit the scope of the present invention to the embodiments described in the following examples; rather, it is the intention that the present invention be limited only by the scope of the claims appended hereto.

Example 1 An aqueous solution containing 79.1 grams of 2-acry}amido-2-methylpropane sulfonic acid ~-AMPS~) crystals and 92.85 grams of deionized water was neutralized with about 110.79 grams of a 40 weight ~ sodiu~l hydroxide solution to a pH
of about 6.25. The resulting sodium ~AMPSa so}ution was then mixed with 205.69 grams of a 50 wei~ht % aqueous solution of acrylamide, 0.03 ~ram of ethylenediamine tetracetic acid sodium salt, and 23.13 grams of deionized water. Separately, an oil phase was prepared by mixing 169.75 grams of an aliphatic hydrocarbon (available from the Exxon Chemical Co. under its tradename Isopar-M), 9.46 grams of sorbitan ~onooleate ~available from ~.C.I. under its tradename Spa~-80), and 10.64 ~rams of vinyl acetate.
The two phases were combined and homogenized in a Waring blender to yield a uniform water-in-oil emulsion having a Brookfield viscosity of 448 centipoises ~cps~Model HBT at 10 R~M at Z5 C). The monomer emulsion w~s transferred to -~ ~ onæ-liter Pyrex~ l~ss polymeriz~tion kettle ~quipped D 13,858 with a turbine agitator, a thermo~eter, a condenser, an addition funnel and a nitrogen (air~ inlet and outlet.
The reactor was deaerated by sparging with nitrogen at a rate o~ 40G ml/min for u period of about 45 minutes.
Thereafter, a solution of 0.195 gram of 2,2 -a~obis (2,4-dimethylvaleronitrile)(ava ~a~le from the DU Pont Company under its tradename VAZO-52) in 9.39 grams of toluene was prepared and a 20~ portion of the initiator solution was quickly introduced into the reactor. The polymerization was initiated by heating the kettle with an external water bath to about 52C. Once the exotherm took place, the remaining initiator solution was added into the reactor at a rate of 0.7 ml/10 min. and the polyrnerization temperature was l,laintained by a combination of external cooling and air injection. The latter is a technique to control the rate of palymeri2ation of the system by adjusting the dissolved oxygen levels in the mono~er emulsion usins alternative air and nitro~en s~argin~s.
The polymerization was completed in about 3 hours and a solution of 0.195 gram of thiobispherlol (available fr~
the Monsanto Chemical Co. unaer its traden~me Santonox-R) in 5 ~rams of toluene was introduced before discharging the product. The resultant product was a uniform water-in-oil emulsion which exl~ibited a Brookfield viscosity of 704 cps (Model ~BT at 10 RPM at 25C).

Example 2 A portion of the product prepared in Exar,lple 1, weighing 23 10 grams, was coagulated in 400 ml of isopropanol using a ~aring blender. The coagulated, granular polymer was ~ollected and drled in a vacuum oven ~t 55C. 8.07 grams of dry polymer were obtained indicating that ~he conversion W2S e~sentially quantitative.

D-13,858 , ~, . .

~L~2~7~3 Example 3 An 0.3 weight ~ polymer sol~tion was prepare~ by dissolYing the polymeric eMulsion obtained in Example 1 in water in the presence of a small amount of a polyoxyethyleneated linear alcohol (available f~ ~ Union Carbide Corporation under its tradename Tergit~l-NP 10~.
A very viscous solution was obtainedl and it exhibited a arookfield viscosity of 1,376 cps (Model HBT at 10 RPM at 25C) and a pH of 6.32.

Example 4 The intrinsic viscosity of the polymer prepared in Example 1 was measured in a one normal sodium chloride solution and was found to be 8.8 dl/g., indicating the product was of very hish l~olecular weight.

Example 5 The product prepared in Example 1 (having an I.V. of 8.8 dl/g) was evaluated as a flocculant for coal blackwater at a dosage of 0.1 pound of polymer per ton of suspended solids, in combination with 0.1 pound per ton of a cationic flocculant (available from Allied Colloids under its tradename Perco~-402) in a cylinder settling test.
Por comparison purposes, tbe combination of 0.1 pound per ton ~f a sodium acrylate (NaA~-containing anionic polymer flocculant having an I.V. of 9.5 dl/g (i.e., a 41.1 mole percent sodium acrylate/54.2 rlole percent acrylamide/4,7 ~ole percent ~inyl acetate terpolymer) and 0.1 pound per . on of Percol-402 w~s used as a control. The cylinder ~ettling test involved plac$ng a coal blackwa~er ~uspension in a cylinder, injecti~g the anionic polymer ~loccul~nt (i.e., the product prepared ln Example l or the ~odium ~cr~ate-conta$ning polymer) into the cylinde,r, f'''','!~ ~13,eS8 ; . . .

~ 35 -inverting the cylinder 10 times, then injecting the cationic flocculant into the cylinderJ inverting the cylinder an additional 10 times and then observing the rate at which the solids are flocculated and settled. The results are given in the table below.
Flocculants Settling Hei~ht ~ Solids Content ~*
2 mlns S mins (wt . % ) Example ~ o~vmer + Percol'~0~ 77 16 29 NaA polym~
+ Percol 02 67 14 26 * The settling height is expressed as the location (expressed as a percentaye of the original total hei~ht of the suspension in the cylinder), after the indicated time, of the floccul~ted solids/supernatant liquid interface.

*~ The solids content of the compacted material was determined after 24 ho~rs and is expresse~ as weisht percent solids.
Example 6 The product prepared in Example 1, and other polymers for comparison, were evaluated as floc~ulants for a coal fines suspension in a cylinder settling test, conducted in the same ~anner as in Example 5. The results are shown in the ta~le below.
Settling Rate Percent Flocculants (inches Trans-Anionic (lb/to ~ /~in_) _ mission( Ex. 1 ~0.043 C4(1) (0.08) 13 75 ~ (0.02) ~ (0.04) 11 69 q ~0.01) (0.02) 6 63 Nalco~ 872(2) (0.04)Nalco 8B52(3) (0.08) 11 78 ~ (~.02) ~ (0.04) 8 77 35~ (0.01) ~ (0.02) 5 60 ~-13,~5~

.

~%2~;7~

~, Superfloc-208(4) (Q.04) Superfloc-355(5) (0.08) 9 83 (0.02) ~ (o,o~) 7 73 ( 0 . 01 ) a ( 0 . 02 ) 4 54 Percol-156(6) (0.04) Percol-402(7) (0.08) 8 77 (C.0~) ~ (0.04) 6 70 ~ (0.01) ~ (0.02) 4 55 Calgon M295(8) (0.04) Calgon M522D(9) (0.08) 9 76 (0.02) ~ (0.04) ~ ~0 (0.01) ~ ~0.02) 3 30 NaA/AM/VAc(10) (0.04) C4(1) (0.08) 13 76 (0.02) ~ (0.04) 12 73 n (O.01) ~ (0.02) 8 30 Note (1) - A cationic polymer ~locculant obtained from Rhone-Poulenc, France.

Note (2) - An anionic polyacrylamide flocculant available from the Nalco Chemical Company as Nalco 8872.

Note (3) - A polymeric cationic flocculant available from the Nalco Chemical Company as Nalc ~ 852.

Note (4) - An anionic acrylamide copolymer floccula ~ avail-able from the American Cyanamid Company as Superfloc 208.

Note lS) - A cationic polymer flocculaTMt available from the American Cyanamid Company as Superfloc 355.
- Note (6) - An anionic polymer flocculant available from Allied Colloids as Perco ~ 56.

Note (7) - An cationic poiymer ~locculant ~vailable from Allied Colloids as Perco ~402.

Note ~8) - An anionic polymer 1Occulant ~vailable from Calgon as Calgo ~ 295.

Note (9) - A cationic polymer flocculant available from Calgon ~ ~552D.

: ~-13,85~

i7~313 Note (10) - A terpolyme~ic flocculant comprising 41.1 mole - percent sodium acrylate, 54.2 mole percent acrylamide and 4.7 mole percent vinyl ~cetate.

~ote (11) - Percentage ~ransmission data is given as the percent transmission after 2 minutes.

Example 7 Example 1 was repeeted with the exception *hat the polymerization was car~ied out at 45C and the initiator used was 2,2 -azobis (2,4-dimethyl-4-methoxy-valeronitrile) (available from the DuTMont Company under its tradename VAZ0~ 3) inst~ad of VAZ0-52. A uniform, rnilky, water-in-oil emulsion was obtained. The conversion was essentially quantit~tive and the resultant product exhibited the following properties:
PO1YMer Emulsion Viscosity 752 cps (Model HBT at 10 RPM at 25C) 0.3~ Solution Viscosity 1,376 cps (Model HBT at 10 RPM at 25Cl Intrinsic Viscosity, dl/g. ~ 10.0 (in 1 N NaCl Solution) Exa~ple 8 Example 1 was repeated ~ith the exception that the 10.64 grams of vinyl ~cetate was replaced with the same amount of styrene. After polymerization, a milky, uniform, water-in-oil emulsion w~s obtained. The e~ulsion was ound to contain 31 wei~bt ~ polymer by the isopropanol coagulation test descri~ed in Example 2. ~n 0.3 weight S
aqueous solution of thi~ polymer exhibited ~ Brookfield vis~osity of 740 cps (~9odel ~Bl', 10 RPM at 25C).

' ~ D-13,858 .~ , .~ , :;
, - 3& -Example 9 .
Example 1 was repeated with the except:ion that the 10.64 gr~ms of vinyl acetate was replaced with the same amount of alpha-methyl styrene. After polymerization, a milky, uniform, water-in-oil emulsion was obtained. The emulsion was found to contain 28 weight ~ polymer by the isopropanol coagulation test described in Example 2. The polymer exhibited a~ intrinsic viscosity of 8D8 dl/g (deciliter/gram) in a 1 N NaCl solution. An 0.3 weight %
aqueous solution of this polymer exhibited a Brookfield viscosity of 1,380 cps (Model HB'T, 10 RP~ at 25C).

Example 10 A preparative method similar to that employed in Example 1, but usiny a unique dual-initiator sy~tem, was employed. An aqueous solution containing 138.13 grams of deionized w~ter and 57.2 grams of ~AMPS~ (Lubrizol Grade 2404) was neutralized with about 22.50 grams of a 50 weight ~ caustic solution to a pH of 7.5. The resultins sodium "AMPSW solution was then mixed with 283.87 grams of a 50 wei~ht % aqueous solution of acrylamide, and 0.245 gram of a pentasodium salt of diethylene triamine pentaacetic acid chelating a~ent (avail~ble from the Dow Chemical Co. under its tradename Versenex~-80) Separ~tely, anrMoil phase was prepared by mixing 169.75 grams of Isopar-M, 9.46 grams of Span-80, and 1.9 grams of ~ vinyl acetate. The two pha~es were then combined and homogenized in a ~aring blender to yield a uniform, milky, water-in-oil emulsion. The latter exhibited a Brookfield viscoslty o~ 1,288 cps ~Model ~BT, 10 RPM at 25C). The ~onomer emulsion was transgerred to a one liter Pyrex~ lass polymerization kettle similarly equipped as ~hat desoribed in Example 1. ~fter deaeration, an ~nl~Ator ~olution co~ t~ng of 0.012 ~ram of VAZC)-33 in D~13,858 ; ,~, .
~t ~ ~

. , .

3L;225t7g3 1.5 grams of toluene was introduced. The kettle - temperature was raised using an external water bath until the polymerization was initiated. Therea~ter, ~he polymerization temperature uas maintained at 50~C by external coolinq and the air injection technique described in Example 1. Simultaneously, a second initiator solution consisting of 0.1755 gram of VAZO 52 in 7.5 grams of toluene was fed into the reactor at a rate of about 1.5 ml per every 10 minutes. The polymerization was completed in about three hours and a solution consisting of 0.195 gram of Santonox~ in 5 grams of tol~ene was introduced. The reactor was cooled to room temperature and the product was discharged. The resultant water-in-oil emulsion possessed a Brookfield viscosity of 1,128 cps (Model HBT, 10 RPM at 25C). The polymer exhibited an intrinsic viscosity (in 1 ~ aCl solution) and a Brookfield solution viscosity tO.3 weight % polymer concentration measured with a HBT Model at 10 RPM at 25~C) of 10 dl/g and 1,28C cps, respectively.

Examples 11 - 29 Using the procedures described in Example 10, a variety of AMPS~-containing terpolymers of different compositions and intrinsic viscosities (molecular weights) were prepared. The forr,lulation variations and the characteristics of the finished products are compiled in the following Table I:

D-13,858 .J~'.!b f TABLE I

Terpolymer9 Composition 0.3% Solution _ _ (Mole %) _ ~AMPS~ Active Viscosity (cps) Type polymer I.V.4 Example VAc1 Na ~Ar~ps~2 AM3 Used (~) (dl/g) HBT5 LVT6 11 S.5 8.2 86.3 Lubrizol 28.9 11.0 900 3,050

12 i.0 12.3 86.7 2412 29.5 6.0 830 2,000

13 1.0 12.0 87.0 2404 29.5 7.0 5,240 36,700

14 1.0 12.3 86.7 2401 29.5 6.0 V. Low V. Low 1.0 12.0 87.0 2404 29.5 7.5 2,620 13,350 16 1.0 12.0 87.0 2404 25 8.7 1,920 8,200 17 1.0 23.0 87.0 2404 20 11.5 1 570 9,200 18 1.~ 12.0 87.~ 2404 29.5 15.0 2~370 12,000 19 1.0 12.0 87.0 2405 29.5 12.0 1,850 7,600 1.0 12.0 87.0 2405 25 13.5 1,3qO 9,900 21 1.0 12.0 B7.0 2404 20 15.0 1,440 10,800 22 2.7 11.8 85.5 2405 29.5 12.0 1,090 5,050 23 5.1 11.5 83.4 2405 29.5 11.7 1,000 5,200 24 1 14.4 84.6 2405 29.5 12.5 1,440 8,150 0.9 9.9 89.2 2405 29.5 12.0 1,150 5,300 26 0.9 7.8 91.3 2405 29.5 11.0 1,150 3,450 27 0.9 5.9 93.2 2405 29.5 9.0 1,150 2,950 28 1.0 12.0 87.0 2405 25 12.~ 1,470 8,900 t7) 29 1.0 12.0 87.0 2405 25 12.5 1,440 8,800 (8) (l) VAc = vinyl acetate (2) Na ~MPS~ = sodium ~AI~PS~
(3) AM = acrylamide (4) measured in l N NaCl solution (5) Brookfield viscometer Model HBT at lO RP~I and 25C
(6) Brookfield viscometer Model LVT at 0.6 RPM and 25C
(7) only l/2 of Versenex-80 charge used (8) twice Versenex-80 charqe used (9) expressed as the ~ole percentages of the respective momoners in the starting monomer emulsion ~-13,858 ~^i .

.. ~ . . .. ,. , , ~ ... .. .. . ..

57~

ExamPle 30 The method of preparation of tetra-polymers containing both ~AMPS~ and acrylic acid, or their salts, is described in this example. An aq~eous solution containing 15.82 grams of ~AMPSn, 63.28 ~rams of acrylic acid and 138.13 grams of deionized water was neutralized with about 76.2 g~ams of a 50 weight ~ caustic solution to a final p~ of 7.48. The resulting Na ~AMPS~/Na acrylate solution was then mixed with 205.69 grams of an aqueous 5~ weight %
acrylamide solution and 0.194 gram of Versenex~80).
Separately, an oil phase was prepared by mixin~ 169.75 grams of Isopar-~, 9.46 ~rams of Span-80, and 10.64 grams of vinyl acetate. The two phases were then combined and homogenized in a ~laring blender to yield a uniform, mi}ky, uater-in oil emulsion. The latter exhibited a ~rookfield viscosity of 640 cps (Model HBT, 10 RPM at 25C). The monomer emulsion was then transferred to a one-liter Pyre~ glass polymerization kettle and was polymerized using the dual-initiator system in a manner similar to that described in Example 10. A uniform, ~ilky, water-in-oil emulsion containing a~out 30 weight % active polymer was obtained. The emulsio~ and a 0.3 weight aqueous solution of the polymer exhibited Brookfield viscosities of 1,048 and 2,496 cps, respectively. The polymer possessed an intrinsic viscosity of 16.0 dl/g (in 1 N NaCl solution)~

Example 31 3~
The polymer prepared in Example 30 was evaluated as a flocculant for the dewatering of a Florida phosphate 81ime. A t70 cylinder test was employed and the res~lts D-13,858 ~ .

are shown below:
- Dose Flocculant (lb/t_n~) t70 (sec) Example 30 polymer 1 lO.B
None - very long * lb of active polymer per ton of suspended solids~

The t70 cylinder test was conducted by pouring phosphate slime and diluted flocculant solution through a funnel into a breaker containing a rotating rake. The time t70 given in the above table is the time necessary for the flocculated solids/supernatant liquid interface to fall to 70 percent of the original heisht of the phosphate slime lS in the cylinder.

Example 32 The polymer prepare~ in Example 30 was evaluated as a flocculant for the treatment of coal-clay blackwater.
Tests were conducted by measuring both the settling rate and clarity of the supernatant liquid phase. Two terpolymers, one containing no sodium ~A~IPS~ and the other containiny no sodium acrylate, were used as controls:
Flocculant Cs~tl) CCL(2) Example 30 ~olymer 0.06 0.07 A terpolymer containing 0.14 0.24 no sodium acryl~te (3) A terpolymer oontaining 0.17 0.12 no ~odium ~AHPS~ (4) C~
(1 ) SR ~ polymer corlcentratiQn ( #~ton ) *o produce s~ ling rate of lD ~minute .

~ " , ,~,~ D-13,85~
~$~ ` `7 ' - 43 ~ ~S793 (2) CcL = polymer concentration ~#/ton) to produce supernat~nt clarity of 50%
(3) 8.2 mole ~ Na "AMPS"t 86.3 mole ~ acrylamide/
5.5 mole % vinyl acet~te (4) 54. 3 mole ~ acrylamide/ 41.1 mole % sodium ~crylate/4.6 mole ~ Yinyl acetate ExamPleS 33-3?
Using the preparative method described in Example 30, the following tetrapolymer emulsions (all having an active polymer content of 29.5 wei~ht %) were prepared by v~rying the monomer-feed compositions:

Tatrapolymer5 0.3S Solutlon Co~ on (Mble S) nAMPSn 2 Vlscoslty (cps) Ex~m- Na TVP~ I.V. 3 4 pl~VAc "AMPS" NaA1 AM Used (dl/~) H~T LVT
33 0.910 4.3 ~4.8 Lubrlzol 13.2 2,620 10,200 34 0.9 8 ~.3 82.8 2405 14.01,890 11,200 2 0 35 0.96.8 12.0 B0.3 240515.0 1,630 II,B00 36 5.38.3 23.8 62.6 240210.3 1,570 8,550 37 4.7 1.6 39.5 54.2 2402 8.9 2,750 26,550 (I) N~A = sodium acrylate (2) measured In I ~ NaCI solutlon at 25C
2 5 (3) 8rookfield viscometer Model HBT nt 10 RPM end 25~C
(4) ~rookfield viscometer Model LVT at 0.6 RPM and 25C
(5) Expressed ~s th~ mole percentages of the r0spectlve monomers In the startlng monomer ~mulslon E X a mP 1 e 3 8 A series o$ laboratory flocculation tests were performed on di$ferent Florida phosphQte slimes usin~
different polymer flocculants. These tests were performed using a 3.5 inch Enviro-Clear labor~tory ~hickener unit (manufactured by the Enviro-Clear Division of Amstar D-13,858 f~
,,, ;~,,~

J~2~ 3 Corporation, Somerville, Ne~ Jersey 08876). In each test, the raw Florida phosphate slime was metered, uith diluted polymer flocculant solution, through an in-line static mixer into the thickener unit, which separated the combined feed stream into a clear overflo~J liquid (i.e., supernatant) and a t~ ckened underflow. Previously-calibrated Masterflex pumps were used to meter the phosphate slime, the diluted polymer flocculant solution and also for the removal of the underflow stream.
Flocculant dosages (expressed as pounds of active polymer per ton of slimeJ were determined from the measured flow rates of diluted polymer flocculant solution (of a known concentration) and slime (both in cubic centimeters/
minute, cc/min) and the weight percent solids of the feed slime. Underflow solids (expressed as the weight ~ of solids in the underflow stream) were obtained a~ter 30 minutes running time by removing two underflow samples and drying them to a constant weig~lt under heat lamps. The data are reported as tweight %) underflow solids versus (l~s./ton) flocculant dose in Figures 1-7 of the drawings.

Figure 1 of the drawings compares the flocculatin~
efficiency of four different polymers (identified in Fig.
1 using the same numbers as below) on the same beige Florida phosphate slime:

~1) the terpolymer of Example 19;

(2) a prior art copolymer believed to contain 12 mole %
sodium ~AMPS~ and 88 mole % acrylamide;

(3) a 75 mole % acrylamide/ 25 mole ~ sodium acrylate copolymer (available from the Nalco Chemical company under its tradename Nalc~7873); and D-lJ,858 i7g;~

(4) a 54.2 mole % ~c~ylamide/4.7 mole % vinyl acetate/41.1 mole % sodium acrylate terpolymer (of the type described in U. S. Patent No.~4,529,782.
Based on ~igure 1, it is apparent that the terpolymer of the present invention is significantly more e~ficient, in this slime, than the other polymers tested, especially at dosages above about 0.1 lbs/ton.

Figures 2 and 3 show the results of similar comparisons, using the same polyme~s as in Fig. 1, on two different Florida gray phosphate slimes. Based on the data shown in Figs. 2 and 3, the polymer of the present invention is more efficient in th se slimes in comparison to the other polymers tested.

Figure 4 shows the fl~cculation efficiency, in a beige ~lorida phosphate slime, of:

(1) a 12.4 mole % sodium ~AMPSn/87.6 mole ~ acrylamide copolymer prepared by a dual-initiator pro~cess as in Example 10 (2) the terpolymer o~ Example i9; and (3) a prior art copol~ner believed to contain 12 mole %
sodium ~AMPS~ and 88 mDle g acrylamide.

Pigure 5 shows the fl~ulation efficiency, in a beige Florida phosphate sli~ believed to be low in Attapulgite clay/ of:

(1) a sodium ~AMPS~/a~rylamide/vinyl acetate terpolymer, prepared as in Xxample l;but ~rom ~ monomer emulsion 3s ~ containing 0.8 mole % vinyl acetate, 19.4 mole % sodium ~ AMPS~ and 79.8 mole ~ ~crylamide; and ~25793 (2) the same copolymer designated (1) in ~igure 4.

Figure 6 shows the flocculation efficiency, in a gray Florida phosphate slime, of:

(1) the same copolymer designated (1) in Fig. 4;

(2) the terpolymer of Example 19; and (3) and (4) terpolymers prepared as in Example 10, but starting from a monomer emulsion containing 2.7 mole % and 5.1 mole %" as in Examples 22 and 23 respectively, vinyl acetate rather than 1 mole ~ as in'Example 19 Figure 7 sho-~s the % underflow solids obtained as a function of the vinyl acetate contents of the same polymers as in Figure 6, for two different dosages, in a different, beige Florida phosphate slime. The data points on the two curves at 0, 1, 2.7 and 5.1 mole % vinyl acetate represent polymers designated (1), (2), ~3) and (4), respectively, in Figure 6, whereas the other two data points represent two dosages of the prior a~t copolymer desiqnated (3) in Fig. 4.

Based on the foregoing and the data shown in Figures 1-7, it will be appreciated that the polymers of the present invention, generally speaking, are improved flocculants in comparison to known polymeric flvcculants of the prior art.

D-13,858 .

Claims (29)

WHAT IS CLAIMED IS:

1. A high molecular weight, water-soluble polymer represented by the formula:

wherein A represents a repeating unit derived from a hydrophobic vinyl monomer having a water-solubility of less than about 5 weight %; R1 and R3 are each a hydrogen atom or a methyl group; R2 represents a divalent hydrocarbon group having from 2 to 13 carbon atoms; R4 and R5 are each a hydrogen atom, a methyl group or an ethyl group; X represents a monovalent cation;
B represents a repeating unit derived from an ethylenically-unsaturated carboxylic acid or its salt; m is about 0.1 - 10 mole %, n is about 1-40 mole %, p is about 20-98.9 mole %, and q is about 0-40 mole % with the proviso that m + n + p + q = 100 mole %; and r is a large positive integer.

2. The polymer of Claim 1 wherein r is from about 1,000 to about 200,000.

3. The polymer of Claim 1 wherein the polymer molecular weight is greater than 500,000.

4. The polymer of Claim 1 wherein the polymer molecular weight is greater than 1,000,000.

D-13,858

5. The polymer of Claim 1 wherein said polymer is a linear polymer.

6. The polymer of Claim 5 wherein A represents a monomeric repeating unit represented by the formula wherein R6 is a hydrogen atom or a methyl group; R7 is , a halogen atom, - O - R10 or wherein R8 is an alkyl group having from 1 to 12 carbon atoms; R9 is an alkyl group having from 1 to 4 carbon atoms; R10 is an alkyl group having from 1 to 6 carbon atoms; and R11 is a hydrogen atom, a methyl group or an ethyl group.

7. The polymer of Claim 5 wherein R2 is an alkylene group having from 2 to 8 carbon atoms.

8. The polymer of Claim 5 wherein B is selected from the group consisting of acrylic acid, methacrylic acid, and salts thereof with an alkali metal, ammonia, or an organic amine.

9. The polymer of Claim 5 which comprises a polymer resulting from the polymerization of a water-in-oil monomer emulsion containing about 6-10 mole % of sodium 2-acrylamido-2-methylpropane sulfonate monomer, about 50-70 mole % of acrylamide monomer, about 0.1 - 20 mole %
of vinyl acetate monomer and about 20-40 mole % of sodium acrylate monomer, all based on the total moles of monomer in the emulsion.

D-13,858

10. The polymer of Claim 6 wherein at least a portion of said monomeric repeating unit A is hydrolyzed to provide a polymer represented by the formula wherein R1, R2, R3, R4, R5, R6, R7, X, B, m, n, p, q and r are as defined in Claim 1 and z is from about 0.1 to less than about 10 mole % and wherein (m-z) +
z + n + p + q = 100 mole %;

11. A high molecular weight, water-soluble polymer resulting from the polymerization of a water-in-oil monomer emulsion containing about 0.1-20 mole % of a hydrophobic vinyl monomer having a water-solubility of less than about 5 wt. in the oil phase; about 1-40 mole % of a monomer represented by the formula wherein R1 represents a hydrogen atom or a methyl group, R2 represents a divalent hydrocarbon group having from 2 to 13 carbon atoms and X represents a monovalent cation;
about 20-98.5 mole % of a monomer represented by the formula wherein R3 represents a hydrogen atom or a methyl group, and R4 and R5 are each a hydrogen atom, a methyl group or an ethyl group;
and and from 0 up to about 40 mole % of an ethylenically-unsaturated carboxylic acid or its salt;
based on the total moles of monomer in said emulsion.

D-13,858

12. A high molecular weight, water-soluble polymer represented by the formula:

wherein A represents a repeating unit derived from a hydrophobic vinyl monomer having a water-solubility of less than about 5 weight %; R1 and R3 are each a hydrogen atom or a methyl group; R2 represents a divalent hydrocarbon group having from 2 to 13 carbon atoms; R4 and R5 are each a hydrogen atom, a methyl group or an ethyl group; X represents a monovalent cation;
m' is about 0.1-10 mole %, n' is about 1-40 mole % and p' is about 50-98.9 mole % with the proviso that m' +
n' + p' = 100 mole %; and r' is a large positive integer.

13. The polymer of Claim 12 wherein r' is from about 1,000 to about 200,000.

14. The polymer of Claim 12 wherein the polymer molecular weight is greater than 500,000.

15. The polymer of Claim 12 wherein the polymer molecular weight is greater than 1,000,000.

16. The polymer of Claim 12 wherein said polymer is a linear polymer.

D-13,858

17. The polymer of Claim 16 wherein A represents a monomeric repeating unit represented by the formula wherein R6 is a hydrogen atom or a methyl group; R7 is , a halogen atom, - O - R10 or , wherein R8 is an alkyl group having from 1 to 12 carbon atoms; R9 is an alkyl group having from 1 to 4 carbon atoms; R10 is an alkyl group having from 1 to 6 carbon atoms; and R11 is a hydrogen atom, a methyl group or an ethyl group.

18. The polymer of Claim 12 wherein R2 is an alkylene group having from 2 to 8 carbon atoms.

19. The polymer of Claim 12 which comprises a polymer resulting from the polymerization of a water-in-oil monomer emulsion containing about 8-12 mole % of sodium 2-acrylamido-2-methylpropane sulfonate monomer, about 87-91 mole % of acrylamide monomer and about 0.1-20 mole %
of vinyl acetate monomer.

D-13,858

20. The polymer of Claim 17 wherein at least a portion of said monomeric repeating unit A is hydrolyzed to provide a polymer represented by the formula:

wherein R1, R2, R3, R4, R5, R6, R7, X, m', n' , p' and r' are as defined in Claim 12 and z' is from about 0.1 to less than about 10 mole % and wherein (m'-z') + z' + n' + p' = 100 mole %.

21. A high molecular weight, water-soluble polymer resulting from the polymerization of a water-in-oil monomer emulsion containing about 0.1-20 mole % of a hydrophobic vinyl monomer having a water-solubility of less than about 5 wt.% in the oil phase; about 1-40 mole % of a monomer represented by the formula:

wherein R1 represents a hydrogen atom or a methyl group, R2 represents a divalent hydrocarbon group having from about 2 to 13 carbon atoms and X represents a monovalent cation; and about 50-98.9% mole % of a monomer represented by the formula wherein R3 represents a hydrogen atom or a methyl group, and R4 and R5 are each a hydrogen atom, a methyl group or an ethyl group;
based on the total moles of monomer in said emulsion.

D13,858

22. A process for flocculating an aqueous solid suspen-sion which comprises mixing a dilute aqueous solution of a high molecular weight, linear, water-soluble polymer with said suspension under appropriate floc-forming conditions and allowing the suspended solids to settle from said suspension to form an essentially clear aqueous super-natant, said polymer being represented by the formula wherein A represents a repeating unit derived from a hydrophobic vinyl monomer having a water-solubility of less than about 5 weight %; R1 and R3 are each a hydrogen atom or a methyl group; R2 represents a divalent hydrocarbon group having from 2 to 13 carbon atoms; R4 and R5 are each a hydrogen atom, a methyl group or an ethyl group; X represents a repeating monomer unit of a monovalent cation; B represents a repeating monomer unit derived from an ethylenically-unsaturated carboxylic acid or its salt; m is about 0.1 -10 mole %, n is about 1-40 mole %, p is about 20-98.9 mole %, and q is about 0-40 mole % with the proviso that m + n + p + q =
100 mole %; and r is a large positive integer.

D-13,858

23. The flocculating process of Claim 22 wherein said aqueous solid suspension comprises a coal blackwater suspension; wherein A represents a monomeric repeating unit represented by the formula wherein R6 is a hydrogen atom or a methyl group; R7 is , a halogen atom, - O - R10 or , wherein R8 is an alkyl group having from 1 to 12 carbon atoms; R9 is an alkyl group having from 1 to 4 carbon atoms; R10 is an alkyl group having from 1 to 6 carbon atoms; and R11 is a hydrogen atom, a methyl group or an ethyl group; wherein R2 is an alkylene group having from 2 to 8 carbon atoms; wherein q is greater than 0 and up to about 40 mole %; and wherein B
is a repeating monomer unit derived from a member selected from the group consisting of acrylic and methacrylic acids and salts thereof with an alkali metal, ammonia or an organic amine.

24. The flocculating process of Claim 23 wherein said polymer comprises a polymer resulting from the polymerization of a water-in-oil monomer emulsion containing about 6-10 mole % of sodium 2-acrylamido-2-methylpropane sulfonate monomer, about 50-70 mole % of acrylamide monomer, about 0.1-20 mole % of vinyl acetate monomer and about 20-40 mole % of sodium acrylate monomer, all based on the total moles of monomer in the emulsion.
D-13,858

25. A process for flocculating phosphate slimes which comprises mixing a dilute aqueous solution of a high molecular weight, linear, water-soluble polymer with said phosphate slimes under appropriate floc-forming conditions and allowing the suspended solids to settle from said slimes to form an essentially clear aqueous supernatant, said polymer being represented by the formula wherein A represents a repeating unit derived from a hydrophobic vinyl monomer having a water-solubility of less than about 5 weight %; R1 and R3 are each a hydrogen atom or a methyl group; R2 represents a divalent hydrocarbon group having from 2 to 13 carbon atoms; R4 and R5 are each a hydrogen atom, a methyl group or an ethyl group; X represents a monovalent cation;
m' is about 0.1 - 10 mole %, n' is about 1-40 mole %
and p' is about 50-98.9 mole % with the proviso that m' + n' + p' = 100 mole %; and r' is a large positive integer.

26. The flocculating process of Claim 25 wherein A
represents a monomeric repeating unit represented by the formula wherein R6 is a hydrogen atom or a methyl group; R7 is ,a halogen atom, - O - R10 or , wherein R8 is an alkyl group having from 1 to 12 carbon atoms; R9 is an alkyl group having from 1 to 4 carbon atoms; R10 is an alkyl group having from 1 to 6 carbon atoms; and R11 is a hydrogen atom, a methyl group or an ethyl group; and R2 is a alkylene group having from 2 to 8 carbon atoms.

27. The flocculating process of Claim 26 wherein said polymer comprises a polymer resulting from the polymeri-zation of a water-in-oil monomer emulsion containing about 8-12 mole % of sodium 2-acrylamido-2-methylpropane sulfonate monomer, about 87-91 mole % of acrylamide monomer and about 0.1-20 mole % of vinyl acetate monomer, all based on the total moles of monomer in the emulsion.

28. A polymer water-in-oil emulsion comprising (a) from about 50 to about 80 weight %, based on the weight of the emulsion, of an aqueous phase which contains therein from about 20 to about 80 weight %, based on the weight of said aqueous phase, of the polymer of Claim 1; (b) from about 15 to about 50 weisht %, based on the weight of the emulsion, of a hydrophobic liquid; and (c) from about 0.1 to about 5 weight %, based on the weight of the emulsion, of an oil-soluble surfactant.
D-13,858

29. A polymer water-in-oil emulsion comprising (a) from about 50 to about 80 weight %, based on the weight of the emulsion, of an aqueous phase which contains therein from about 20 to about 80 weight %, based on the weight of said aqueous phase; of the polymer of Claim 10; (b) from about 15 to about 50 weight %, based on the weight of the emulsion, of a hydrophobic liquid; and (c) from about 0.1 to about 5 weight %, based on the weight of the emulsion, of an oil-soluble surfactant.
.