US1598858A - Apparatus for treating liquids with gases - Google Patents

Description

Sept. 7 1926. 1,598,858

W. E. GREENAWALT APPARATUS FOR TREATING LIQUIDS WITH GASES Filed April 2, 1923 3 Sheets-Sheet l 000 090 000 900. 08980 08080 0 0 (D 0 0 0 (52:. 0 0 0 0 0 0 0 0 O 0 o o 7 3 0 0 0 0 0000000 09 0 0 9 0 0 00 Q hfi 1a n) 1c d 1 12 12 12 12 FIG-1 L FIG 3 1 F1 c fjf f Sept. 7, 1926.

w. E; GREENAWALT APPARA'ms' FOR TREATING LIQUIDS WITH GASES Filed April 2, 19 23 3 Sheets-Sheet 2 .FIGS) FIG 10 LEE I Q) I ,1

I NVENTOR Sept. 7 1926. 1,598,858 I W. E. GREENAWALT APPARATUS FOR TREATING LIQUIDS WITH GASES Filed April 2, 1923 3 Sheets-Sheet 3 FIG 15 2 Han I NVENTOR pasta Sept. 7, 192

UNITED STATES WILLIAM E. enn mawnn'r, or nnnvnn, coLonA'no.

APPARATUS FOR TREATING LIQUIDS WITH GASES.

Application filed April 2,

The invention has as its object the efi'ective atomization, or fine subdivision, of gas.

in liquid. It finds efi'ective application in the flotation treatment of ores; in the pneumatic agitation of liquids and ore pulps; and the application of corrosive gases, such as sulphur dioxide or chlorine, to the, treatment of copper, gold, and silver ores.

The descript on of the invention will be more particularly directed to the flotation treatment of ores.

In the flotation treatment of ores, excellent results have been obtained by applyin "the air, or gas, to the ore pulp, through porous material in the lower portion of the tank containing the ore pulp. In doing this, certain difiiculties have arisen; among which may be mentioned the delicate nature of the porous material if it is made of woven fabric, the clogging of the pores ifv inorganic porous-material is used, and the settlingwof the sands on the porous material and consequent unequal distribution of the air in worn or clogged porous material.

To overcome these difiiculties, jets of air have been injected into the liquid and the impingement of the air against the liquid 'siibdivides the air and gives encouraging results," althou h these results are far from being as satis actory as theoretical conditions would indicate.

' I have found that if jets of air, or gas,

are mixed with the liquid, and the mixture is injected into the surrounding liquid in the tank, a very satisfactory atomization can be accomplished, especially if these jets of "as and liquid are directed against one anther, or arranged to inter-penetrate one.

another in the liquid in the tank. It has been found, b this. arrangement, that the injecting of t e gas, in this way, can be made, sufliciently energetic to prevent sands from settling, even in flat bottom tanks, and that the construction of the apparatus can be made in large units, which 'has an imr portant bearing in: the practical and eco-.

nomic operation. In the treatment of ores with acid solutions or with corrosive gases the ore pulp may betreat'ed and agitate by means or airor other tga's by making the gas difl'using members 0 some acid proof, or acid resistin material, such as antimonial lead, or ferrosi icon.

Theadvantage of getting a fine atomiza- I tion of the gas, without a porous material,

is evident.

1923. Serial No. 629.362.

The invention will now be described in detail, reference being made to the accompanying drawings, in which Fig. 1, represents a plan of the apparatus as applied to the flotation treatment or ores; Fig. 2 the corresponding longitudinal section; Fig. 3 the corresponding transverse section; Fig. 4: a longitudinal section'of the invention adapted to treat liquids with corrosive ases; Fig. 5 a detail in vertical section of t e, at-

omizer, injector, or gas impregnator, and

Fig. 6 the corresponding horizontal section on the line 66 of Fig. 5; Fig. 7 a detail vertical section of a modified form of atomizer, or injector, and Fig. 8 the correspond- 'i-ng horizontal section on the line 88 of n Fig. 7.; Fig. 9 a detail of the bottom of the tank similar to that shown in Fig. 3; Fig. 10 a cross section of a modification of the apparatus as applied to the flotation treatment of ores; Fig. 11 a detail in vertical sec-.

tion of the corresponding atomizer and low-' er portion of the tank; Fig. 12 a cross sectionin detail of the atomizer or injector; Fig. 13 a longitudinal section of a modified apparatus; Fig. 1 4.- a horizontal section of one end of Fig. 13; Fig. 15 a detail in vertical section showing the relation of the atomizers to the tank; Fig. 16 a modification of the invention, in vertical section, as applied to round tanks; and Fig. 17 is a vertical section of a modification of the invention as applied to a continuous flow of gas and liquid in which both the gas and liquid are under super-atmospheric ressure.

Referring to the drawings; 1 is a tank adapted to contain the liquid, or ore slud e,

to.be treated. The tank is preferably i.-

vided into sections 1, 1 1, and 1, by the vertical partitions 2, so that the liquid may fiow progressively throu h the tank from one section to the next, or any number of sections; for this purpose the partitions have communicating openings 2, which are intended 'to be large enough to maintain practically the same liquid level in all the sections composin the tank. The tank is provided with a liquid inlet 3, with a weir overflow, outlet 4, and with ,an underfiow' outlet 5 to take the heavier particles of insoluble "matter which cannot be rejected through the weir overflow outlet 4. The underflow outlet 5 has a regulating valve, by means of which a small ste'ady'stream can be made to flow through the underflow outlet to take care of the heavier particles of suspended matter, while the liquid and slimes overfiou over the weir, and this weir is made abundantly large so that any irregularity in the feed will notcause an apprefiiable change in the liquid level in the tan i In the bottom of the tank, in the respective compartments, are gas chambers .6, which are supplied with gas under pressure through the gas pipe 7, and the flow of gas into the respective gas chambers may-be regulated by the valves 10. The flow through the gas main 7 may be regulated by the valve 11. Communicating with each of the gas chambers 6 are atomizers, gas distributors, or injectors, 9, arranged and designed so that the gas in the gas chambers 6 is forced out through discharge passages, and in being forced out, acts as an injector, to suck some of the liquid in the tank into the interior of the atomizer, where the gas and liquid are mixed, and the mixture or gas and liquid is then ejected into the surrounding liquid in the tank. The gas ejected in this way is brought into a very fine state of subdivision, or atomization; much finer than is obtainable by merely'ejecting liquid, offers, it is believed, ideal conditions a stream of gas alone into the liquid.- The impetusof the liquid'mixed with the ejected gas carries the gas a comparatively long distance from the ejector, and by arrangeing-these 'ejectors so that the streams ofthe mixture of gas and liquid impinge, intersect, or penetrate one another, a fairly fine and uniform distribution of the gas may be made all over the bottom of the tank, and the finely divided gas, ascending through the for flotation, for impregnation, and for heating and cooling of the liquid, without the ,use of rotary mechanism.

The gas atomizers may be described in detail by referring to Figs. 5 and 6. The compressed gas from the submerged gas chamber 6, is forced through the .pipe 16- intothe gas discharge passages 17, and throughthe gas discharge passages 17 into the gas and .liquid'discharge passages 19. As the gas is injected from the discharge passage 17 into the discharge passage 19, it sucks liquid from the tank into the interior of the atomizer, through the ducts 18, working somewhat like an injector, and the mixture of gas and liquid is then ejected into the surrounding liquid in the tank, Any number of these atomizers may be screwed into the gas chamber in-the bottom .of the tank, and they are preferably arranged sothat radiating jets, orstreams, of gas and liquid, mix, impinge, and penetrate, so as to bring the gas in a fine state of subdivision, give a fairly uniform distribution of the gas, and prevent violent surging of the liquid. Violent surging off the liquid is detrimental to flotation.

treated the jets may be quite fine and quite.

numerous, for, in that case there is no danger of the atomizers becoming clogged :or of sand settling in the ,bottom of the tank. If the-material to be treated is ore pulp, the jets of gas and liquid should be larger and stronger, at least strong enough to prevent any settling of sands.- The pressure under which the gas should be delivered vto the gas chamber will also depend largely on the material to be treated. For the sake of economy the gas should be delivered at the lowest pressure which will give the desired atomization and agitation. In Figs. 7 and 8 is shown a modification of the atomizer shown in Figs. 5 and 6. The gas is delivered into the interior of the atomizer through the pipe 20, and is ejected through a multiplicity of ducts, or discharge passages, 21 into the general channel formed by the upper and lower plates. This general channel is designated by 22. and 23. The stream of gas and liquid is ejected outwardly around the entire periphery of the atomizer. In this type of atomizer, as also in the other type, the gas may be introduced directly into the interior of each atomizer, through the pipe 20, and the fiow of gas to each atomizer may be under direct "control by a valve (not shown). The atomizer may rest directly on the bottom of the tank. This type of atomizer is preferred where violent agitation isrequired in the presence of corrosive gases or corrosive liquids, or for the agitation of ore pulp containing rather coarse 9 inlet pipe 7 connected with the gas chamber .6 through the top instead of through the bottom. Such an arrangement as shown nv 1 Fig. 9, will avoid any complications due to making connections t rough thetank. The gas chambers, as shown in Fig. 9, can be raised and lowered, with the atomizers attached, and thus repairs and inspections can easily b made. I

In Fig. 4, the gas upper portion of the tank and forced 1n the lower portion by means of the exhausters 30, and both the gas and the material being treated are flowed progressively'from one section to the next through the tank. The gas inlet is shownby 31 and the excess is exhaustedfronidahe gas outlet by 32. This type of apparatus can be constructed in very large units. A tank, for example, 15 feet wide, 20 feet deep, and, 100 feet long, would treat from 2400 tons to 4800 tons of ore per day of 24 hours, with the time of treatment of one and two hours respectively. This is made possible on the basis that a flat bottom tank can be used, and that settling of the ore particlescan be avoided by the means described, and

that the flow of ore pulp can be made progressively from the, tank inlet to the -tank outlets I Fig, 10 shows a modification of the invention, as applied to flotation, in which two atomizers are placed at the sides of the tank in opposite relation, so that thestreams of gas and liquid impinge, or intersect, or penetrate, one another, and so that the gas is projected from one side of the tank against the other side. Better results are usually obtained if a grating, or perforated member, is'placed above the gas streams in the lower portion of the tank. This'somewhat confines thesphere of action, with the result that the gas particles are more minutely subdivided, or atomized, and with the additional advantage that surging iseither avoided or greatly reduced. The grating is shown by 29, the atomizer by 24 and the gas supply pipe by 25.

A detail section of the lower portion of the tank is shown in Fig. '11. The gas is introduced under pressure into the injector, or atomizer, 24 through the gas supply pipe 25, and is ejected through the gas discharge pipe, or nozzle, 28, into the discharge passage 27. In doing this, some of the liquid of the tank is sucked into the atomizer through the ducts 2'6, and is ejected with the gas. The impetus given tothe stream of gas and liquid ejected from the atomizer, by the gas-pressure in,the ipe 25, carriesthe stream of gas and liquid to the other side of the tank, while at the same time small gas bubbles are diffused through the entire lower portion 'of the tank. The streams, impinging, or penetrating, one another, greatly assists in'thel diffusion of the indicates the gas discharge passage and 26' gas bubbles. Y

The atomizers'are intended to be fairly close together, on each side of,the tank, so as to give a uniform distribution of the gas horliizontally, in the lower portiono'f the tan i Fig. 12, shows a detail section through the atomizer on the line 1212 of Fig. 11. 28

the liquid inlet ducts.

In theflotation treatment of ores, it is vdesirable to have a somewhat quiet zone 12 (Figs. 3 and-10). This is formed by baflles 13 and the projections 14, so arranged that the .mineral froth may overflow into a launder, and the gangue particles and middling may descend into the main body of the tank through .the opening 15, to' be again and again ,acted upon by the ascending-atomized gas, until finally, the material will be eliminated from the tank either as mineral froth, through the overflow 12,01 through the gangue and liquid overflow 4, or underflow 5.

If the atomizers are tobe positioned fairly close to one another, the arrangement 7 sands settle, it is-not probable that the sand can obstruct the gas outlet so that no gas will flow when the gas pressure is turned on, and once the gas begins to flow, all ob,- structing sands in the liquid discharge passages are quickly removed.

, 'In the flotation treatment of ores, it is desirable to have the communicating passages between the various compartments fairly low in the tank, as shown in Figs. 2 and 3. This serves two useful purposes: the sands are more easily advanced from one compartment to the next; and a mineral particle, once floated, will have to descend against the ascending atomized gas in order to escape. In this way the entirely'barren I gangue is quickly worked through the ap paratus, .while the mineral particles which are not readily floated, are also not readily eliminated, and can be given a thorough treatment.

Referring to Fig. ,13; the tank is made with offsets corresponding with the vertical partitions 2 which divides the tank into sections, and a series of atomizers projected through these offsets in the bottom of the tank. Thestream of gas and liquid ejected from the atomizers sweep thebottom of the tank, so' that the heavier gangue matter is readily moved toward the outlet and eliminated. The mineral is floated toward the surface,.and before any particle of mineral, once floated. can escape, it will have to descend against the ascending atomized gas. The baffles 35 are intended to confine and distribute the gas in the lower region of the tank so as to prevent surging at the surface, and also to move the heavier particles of gangue through the tank. Fig. 14 shows the correspondinghorizontal section of one end of the tank, showing the series of atom izers arran ed so as to give a horizontal distribution of the gas in thelower portion of the tank. The arrangement of the atomizers is shown in detail in Fig. 15; It is preferred'to attach the outside member, or casting 3D to the tank, as shown. This casting 30' is made so that a pipe, or nozzle 5 may be inserted into it from the outs1 e. V

Fig. 16 shows the applicationof'thein-v vention to around tank. The atomize'rs 30" are arranged about the periphery of the tank, in the lower portion, and preferably very close to the bottom. The intersecting jets of gas and liquid give a good distribution and atomization of the gas. The lower arms 39, rotated by the shaft 38, work the heavier sands toward the outlet 41. The

upper arms 40, skim the mineral froth from the top of the liquid. The liquid level is maintained by the weir overflow 4. 3 It will ordinarily be desirable to have a number of these tanks in series for effective flotation. I

In the modification shown in Fig. 17, the gas is applied under pressure to a continuous flow of liquid under pressure through the apparatus. This modification is particularly effective in the oxidation or reduction of salts of the variable valent elements in solution. F orekample, the reducing action of sulphur .dioxide in the reduction of ferric salts in copper leach 'solutionsis not very rapid at ordinary temperatures and atmospheric pressure. When, however, the pressure is increased the reduction of the ferric salts is very rapid and complete. and at elevated temperatures, even the copper may be precipitated from sulphate solutions as theelemental metal. The application of a gas to a liquid, under pressure, is well known, but the application of the. 40 gas, where both the' gas and liquid are under pressure and flowing in'continuous streams, and in which the gas, in finely subdivided particles is forced up through the liquid under a gas pressure at the top, appears to present newpossibilities.

Referring to the modification shown in Fig. 17, represents a tank adapted to contain the liquid and to confine a gas under pressure above the liquid as 50' This tank may bemade of steel for noncorrosive liquids, and of steel' lined with lead for corrosive liquids. 62 is a tower adapted to contain liquid, and the height of the liquid will be determined by the pressure ofgasdesired. 53 shows a gas generator, and the-gas may be supposedto be sulphur dioxide. The gas is exhausted from the generator 53 through the' pipe 57 by means of the ekhauster-blower 54, and 60 forced through the pipe 58, through the injectors 60 and into the liquid in the lower portion of the ,tank. The valve 59 is supposed to be closed. The injectors may be similar to those shown in Fig. '15. The gas, ascending through the liquid against super- 61 into the lower shown by 51.

atmospheric pressure and with its reducing power greatly increased, escapes at the top of the liquid into the gas space 51 until sufficient pressure has accumulated to force it through the column ofliquid in the tower 62. "The valve 59 being closed, the gas, under pressure, is forced through the pipe portion of the tower 62, and escapes through the liquid in the tower at a pressure corresponding to the height of the liquid, into the space 63 in the upper portion of the tower. From the tower the I gas may be'exhausted by the exhausterblower 67 and forced under pressure into another tank 70, and so on for as many tanks as desired, until the gas is sufiiciently consumed and'the liquid sufficiently treated. The liquid flows into the first tank through the inlet pipe 72, and from the first to the second-tank through the connecting pipe 73, and so on for. the entire series of tanks for as many tanks as desired. The liquid level may-be maintained in the tanks by any of the well known methods, such as a weir overflow in the last tank, or by closely regulating the inflowing and outflowing streams of liquid. To compensate for the differ-- ence in pressure which might arise due to variations in the speed of the exhausterblowers, or to compensate for the consumption of gas in the different tanks, valves 64 and 65 are placed at the top of the 'towers- 63: one of these valves is arranged to blow off excess gas, and the other is arranged to take in air or gas if the pressure falls be- 'low the amount desired. Manifestly, the

finely'sub-divided, or atomized gas, under these conditions, will have a greatly increased effect in oxidation, in reduction, heating, cooling, etc. It has been ascer tained by careful experiments, that very finely atomized gas, even under atmospheric pressure, is from four to five times as effective as gas simplybubbled in the liquid,

'or applied as in the well known Pachuca 1 tank, where the gas is simply introduced through an ordinary pipe and circulation ,induced through a large central tube within the tank.

I claim:

' 1. In apparatus for treating liquid with gas, a tank adapted to contain liquid, stationary oppositely positioned injectors in the lower portion of the tank adapted to. inject a mixture of gas and liquid from their interiors in substantially horizontal streamsinto the surrounding liquid-said injectors" having both their liquid inlets and their liquid outlets in communication with the tank, and means for supplying gas under pressure to said in'ectors.

2. In apparatus or treatingliquid with gas, a tank adapted to'contain liquid, a plurality of stationary hollow members submerged in the liquid in the lower portion'of the tank having outwardly directed liquid gas, a tank adapted to contain liquid, hollow stationary gas injectors in the lower portion of the tank adapted to receive liquid from the tank and to eject a mixture of gas and liquid from their interiors into the surrounding liquid in the tank, said injectors being arranged so that issuing streams of as and liquid from oppositely positioned inectors will penetrate one another, and means for supplying gas to said injectors.

4. In apparatus for treating liquid with gas, a tank adapted to contain liquid, a stationary injector within the tank submerged in the liquid, vertical liquid inlets communicating with the tank and with the interior of the injector and horizontal outlets communicating with the interior of the injector and with the tank, and means for supplying gas under pressure to the interior of the injector and ejecting it with liquid through the horizontal outlets into the surrounding liquid in the tank.

5. In apparatus for treating liquid with gasfa tank adaptedto contain liquid, a stationary injector within'the tank submerged in the liquid, a vertical liquid inlet communicating with the source of liquid supply and with the interior of the injector, a substantially horizontal liquid outlet communicating with the interior of the injector and with the tank, a gas supply pipe within the vertical liquid inlet adapted to deliver gas to the horizontal outlet, and means for supplying gas under pressure to said gas pipe.

6. In apparatus for treating liquid with gas, a tank adapted to contain liquid, a stationary injector within the tank submerged in the liquid, a liquid inlet communicating with the source of liquid supply and with the interior of the injector, a plurality of liquid outlets supplied with liquid through said inlet communicating with the interior of the injector and with the tank, and means i for introducing gas under pressure into the liqpid outlets of the injector. a In apparatus'for treating liquid with gas, a tank adapted to contain liquid, a stationary injector within the tank submerged in the liquid having a plurality of outwardly directed discharge passages communicating through a common center with the source of liquid supply, means for combining a stream of gas with a stream of liquid in the interior of the injector and ejecting the stream-of as and liquid into the surrounding liquid in the tank, and means for supplying gas under pressure to the interior of the injector.

WILLIAM E. GREEN-AWALT.

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