CA1161649A - Method for recovering residual matter accumulated in the production and machining of steel and apparatus for dispensing metal chips - Google Patents
Method for recovering residual matter accumulated in the production and machining of steel and apparatus for dispensing metal chipsInfo
- Publication number
- CA1161649A CA1161649A CA000376237A CA376237A CA1161649A CA 1161649 A CA1161649 A CA 1161649A CA 000376237 A CA000376237 A CA 000376237A CA 376237 A CA376237 A CA 376237A CA 1161649 A CA1161649 A CA 1161649A
- Authority
- CA
- Canada
- Prior art keywords
- chips
- cylinder
- dust
- mixture
- dispensing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65G—TRANSPORT OR STORAGE DEVICES, e.g. CONVEYORS FOR LOADING OR TIPPING, SHOP CONVEYOR SYSTEMS OR PNEUMATIC TUBE CONVEYORS
- B65G65/00—Loading or unloading
- B65G65/30—Methods or devices for filling or emptying bunkers, hoppers, tanks, or like containers, of interest apart from their use in particular chemical or physical processes or their application in particular machines, e.g. not covered by a single other subclass
- B65G65/34—Emptying devices
- B65G65/40—Devices for emptying otherwise than from the top
- B65G65/48—Devices for emptying otherwise than from the top using other rotating means, e.g. rotating pressure sluices in pneumatic systems
- B65G65/4881—Devices for emptying otherwise than from the top using other rotating means, e.g. rotating pressure sluices in pneumatic systems rotating about a substantially horizontal axis
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B30—PRESSES
- B30B—PRESSES IN GENERAL
- B30B15/00—Details of, or accessories for, presses; Auxiliary measures in connection with pressing
- B30B15/30—Feeding material to presses
- B30B15/302—Feeding material in particulate or plastic state to moulding presses
- B30B15/308—Feeding material in particulate or plastic state to moulding presses in a continuous manner, e.g. for roller presses, screw extrusion presses
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65G—TRANSPORT OR STORAGE DEVICES, e.g. CONVEYORS FOR LOADING OR TIPPING, SHOP CONVEYOR SYSTEMS OR PNEUMATIC TUBE CONVEYORS
- B65G47/00—Article or material-handling devices associated with conveyors; Methods employing such devices
- B65G47/02—Devices for feeding articles or materials to conveyors
- B65G47/16—Devices for feeding articles or materials to conveyors for feeding materials in bulk
- B65G47/18—Arrangements or applications of hoppers or chutes
- B65G47/19—Arrangements or applications of hoppers or chutes having means for controlling material flow, e.g. to prevent overloading
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Processing Of Solid Wastes (AREA)
- Manufacture And Refinement Of Metals (AREA)
- Crushing And Grinding (AREA)
- Filling Or Emptying Of Bunkers, Hoppers, And Tanks (AREA)
Abstract
Abstract of the Disclosure A method of recovering dust and other particulate matter having a high metal content and resulting from production or machining of steel is accomplished by wetting the matter to hydrate free lime in the dust, mixing the dust with metal chips having a certain length and with a suitable binder to form the mixture into briquettes. An apparatus for dispensing comminuted metal chips has a hopper for receiving the chips with an open bottom covered by a toothed periphery of a cylinder the teeth of which intermesh with the teeth of a stationary or rotative comb for dispensing comminuted metal chips. A weighing conveyor below the cylinder receives and carries away the dispensed chips and by using the weight reading from the conveyor, the dispensing cylinder can be controlled so that the conveyor delivers a chip feed at a measured rate.
Description
6'~
The invention relates to a method for recovering residual matter which accumulates in the production and machining of steel. The matter recovered is in the form of metal-containing dust and chips and is Eormed into briquettes by the addition oE a binder. The invention further relates to an apparatus for dispensing comminuted metal chips which are for instance useful for :Eorming bri-quettes w~th~dust.
The subject oE reco~ering residual matter has been treated for a long time but is of increasing imp~r~ance in recent tlmes in connection with develop-ing shortages of raw materials and the difficulties of finding suitable deposi-tion sites. Since the residual matter has a high metal content consisting of iron and expensive alloying elements, such as chromium and nickel, its reuse for saving more expensive raw materials is of interest. To this must be added that transport and disposal of residual matter, which is usually in the form of fine dust, presents some problems with respect to pollution of the environment.
Thus numerous proposals have been made for reprocessing residual matter w~th the goal of re-using it in the production of steel.
~rom German patent publication AS 23 ~1 742, for instance, a method is known, according to which spherical briquettes are made from four components, namely, sludge, a coarse component with a grain size ~ 100 ~m, a fine component 2Q with a grain size ~ 100 ~m and a binder. These components are mlxed and pressed, but prior to pressing the mixture must be heated, to a temperature at which the binder becomes liquid. It is a disadvantage oE this known method that the con-tent of the fines component with a grain size of less than 100 ~m, which is very difiicult to process, is limited to a maximum of 25%, because dust in this size spectrum constitutes by far the largest part of the waste products accumulated.
In addition, a continu~usly operating platform conveyor oven is required to heat the mixture so as to liquify the binder. S~nce, according to the known method, -- 1 -- ~
~, ~L6~64~
sludge is an absolutely essential componen~ of the mixture, it is not immediately clear how residual matt0r which accumulates only in tlle dry sta~e can be pro-cessed for recovery.
The same applies to the method known from German patent publication AS 25 31 ~57, in which the sludge component must first be dehydrated down to a water content of 2 to 15% by weight before the binder and the dust component areadmixed. This latter method requires heating the briquettes to 35~C to remove th~ residual moisture and is, therefore, relatively elaborate and expensive.
According to German patent publication AS 24 27 619, finely divided wastes which contain carbon and at least 5% iron, are mixed with a bituminous binder, the mixture is formed into briquettes, and the briquettes are treated for 30 to 90 m~nutes with an oxygen-containing gas at 170 to 320C. This heat treat-ment, however, is expensive and is to be applled only: ~a) to waste accumulatingin the production of iron and steel in powder or dust form, i.e., blast-furnace flue dust, converter dust, rolling scale~ coke dust and flux; or (b~ to scrap from foundries and machine shops, namely, lathe and drill press chips. Mixtures ; of fine with coarse grain fractions are not provided in this method. If chips are used, their dimensions should not exceed 6 mm; if necessary, they are to be comminuted, which means additional costs.
2Q It is an object of the invention to provide a method of processing metal-containing dust and metal chips, as the residual matter obtained in the largest quantities in the production and machining of steel, in a simple and cost-effective manner.
The in~ention is based on the disco~ery that the metal-containing dust preci~itated in filters contains, among other things, free lime, which upon ex-tended storage of the briquettes formed from the dust, causes the briquettes to decay because they absorb moisture. It has also been found that in pressing L6~
briquettes of metal-containing dust and metal chips, certain mixing ratios must be obs-erved in order to facilitate pressing.
The invention provides in a method for recovering residual matter of the type accumula~ed as metal-containing dust and chips in the production and machining of steel, forming the residual ma~ter into briquettes, and adding binder, the steps comprising: adjusting the moisture content of the metal-containing residual matter to contain approximately 2 to 8% by weight of water to hydrate free lime contained in the dust; or treating the mixture with a cor-responding amount of steam, mixing the dust with metal chips in a ratio of ap-proximately 7~ : 20 to 30 : 60; and adding approximately 2 to 10% by weight of a binder, based on thc total amount of the mixture.
After hydration of the free lime contained in the dust, the danger of premature disintegration of the residual-matter briquettes is reduced.
According to one advantageous embodiment of the method according to the invention, the dus* is to be mixed with metal chips, the length of which is 7 to 30 mm and preferably, 7 to 15 mm in the ratio 70 : 20 to 30 : 60 and 2 to 10% by weight, and preferably 3 to 6% by weight, of a binder are added to the mixture. Contrary to the method known from German patent publication AS 23 61 742, supra, in which the dust content is to be limited to 25% maximum, 2a a h~gher dust content of 30 to 70% can be processed in the method according to the invent~on. This is uf great importance because o~ the relatively high mass content of dust as compared ko the contents of residual matter in other forms.
The increased amount of dust that can be processed into briquettes is based, in addition to the preceding hydration of the free lime~ on the fact that metal chips of a given length, which is not ~o be smaller than 7 mm and not larger then 30 mm, are to be used. ~etal chips with a length in this range form an ideal matrix in which the dust, provided with the binder, settles so that 4~
! the cohesion of the ~riquettes is assuredl if suitable 6inders are used. Such binders are bitumen or water glass> also without the use of water, which must always be present, besides the binder, in known methods in order to render the mixture of residual matter capable of being processed.
However, according to the invention, waker is added in an amount of 2 to 8% by weight, and preferablyJ 3 to 6% by weight so that the binder content can be reduced accordingly. It is of advantage ~o adjust the mixture to a residual moisture content corresponding to the water content in the hydration treatmen~.
Sludge accumulated in wet filters may also ~e used if it is converted into dry dust by drying and comminuting.
The method according to the invention is ad~antageously distinguished from the above-mentioned known methods in that durable briquettes made of the types of residual matter which are produced in the largest quantities, namely, dust and metal chips, can be produced in a relatively simple and cost-effective manner .
Th~ method according to the invention will now be expalined in greater detail with the aid of the following examples. While Examples 1 and 2 were car-ried out by the method according to the invention, a sample pressed from dust only was used for comparison in Example 3.
Example 1 Electric-~ilter dust from the production of stainless steel was moistened ln an intensive mixer to 6% water and then digested for a period of 3 days. During this time, the lime contained in the electric-filter dust was burned to calcium hydroxide.
After the digestion, 70 parts of electric-filter dust were mixed with 3~ parts chips~having a length in the range of 10 to 25 mm which had been pro-duced in grinding ingot slabs of stainless steel. The metal chips can also be mixed w~th the filt0r dust during the moistening with water. The mixture was adjusted to 6.3% moisture3 and 5% cellulose powder ~dry component of the sulfite waste~ was added.
Then, the mixture was fed, via a dosing and precompaction worm, to a cylinder briquetting press. With a circumferential cylinder velocity of 0.33 m/s, a set pressure of 28 kN/cm cylinder width and a briquette volume of the briquet-ting cylinders of lO cm3, briquettes with a specific gravity of 3.53 g/cm3 were produced.
The dropplng strength of the briquettes produced was 3.5 m after leav-ing the press. After the briquettes were hardened at room temperature for 3 days, a cold compression strength of the briquettes of 115 daN/briquette was measured.
Example 2 In thls example, the ratio of the electric-filter dust to the grinding cH~ps was set to ~0 : 50. The other data may be seen from the following Table.
~s shown in the Table, it was possible to achieve a dropping strength of the ~riquettes of 4~0 m after leaving the press. The cold compression s~rength of the briquettes after hardening for 3 days was 175 daN/briquette.
Example 3 In this reference example, ~hich does not corre~pond to the invention, 2Q no metal chips were added to the filter dust. The other data may be found in the follo~ing Table.
The dropping strength of these briquettes after leaving the press was only Q.7 m. The cold compression strength after hardening for 3 days was 50 daN/~riquette.
The examples show that the binding-in of metal chips, with the effect af a reinforcement, leads to an unusually high dropping strength of the finished ; briquettes and to a very good cold compression strength of the hardened bri-quettes.
.6~6 ~
Table Process 5teps Example Moisten F.-filter dust to (%H20~ 6 6 6 Digestion time ~days) 3 3 3 Mixing; rat~o E-filter dust/chips (pts/pts) 70/30 50/50 100/0 Residual moistening of moisture to (% H20) 6.3 5.4 7.3 Binder addi~ion, cellulose powder (%) 5 3 7 Briquetting with cylinder pressure (kN/cm) 28 26 24 Briquette volume (cm3~ cylinder width 11 11 11 Quality of the brlquettes a) Dropping strength after leavlng press 3.5 4.0 0.7 Dropping helght (m) b~ Cold compression strength a~ter hardening 115 175 50 for 3 days (daN/brlquette) Specific gravity of the brlquettes (glcm ) 3.53 3.84 2.85 The inventlve method requires proportloning of the metallic dust and chips to form a mixture whlch with the addltlon o~ a blnder and processlng ls brlquetted. A measured feed of the chips for mixing with the dust is required.
The chips can intertangle to form accumulations which must be broken up for feed-lng.
It ls therefore another object of the inventlon to provlde a metal chip dispenslng app ratus sultable for application to the above kind of method but whic~ ma~ be used whenever metallic chips or the like must be fed or dis-pensed in comminuted form.
; The invention provides an apparatus for dispensing metal chips, com-pr~slng a hopper adapted to be loaded wlth the chips and ha~ing an open bottom, G~
a rotative dispensing cylinder having a peripllery e~tending across and covering said Bottom, a multiplici~y of interspaced teeth projecting radially from said periphery, and variable~speed means for rotating said cylinder.
The interspaced teeth may be pins, nails or the like, and ~he cylinder is preferably made oscillatory in the axial direction of this cylinder. Means are provided for combing chips from between the dispensing cylinder's teeth and comminuting ~he chips. Below the dispensing cylinder, means are provided for conveying away while preferably also weighing the chips falling from the cylinder.
The above combing means can comprise a stationary comb or preferably lQ compr~ses a rotative cylinder positioned parallel to the dispensing cylinder and having a periphery from which a multiplicity of interspaced teeth project radi-ally, and these teeth may also be in the form oE pins or nails. The relatlve lengths and positions o~ the first and second mentioned teeth are such as to cause the respective teeth to intermesh without interference when the two cylin-ders are rotated in opposite directions with the hopper oscillating.
Both rotative cylinders are provided with variable-speed means for rotating or driving them respectively in opposite directions and so that scrap pieces feeding from the hopper are fed do~nwardly between the two cylinders, the combing cylinder being driven the fastest to provide effective combing action.
2Q This positively frees any entanglement of scrap pieces and assures that the pieces fall substantially all separated from each other onto an underlying weighing conveyor which forms the previously mentioned means for weighing and carry~ing away the pieces.
Commercially available weighing conveyors provide a read-out which normally~continuously~multiply~weight by travel to give tonnage passing over the conveyor, and with the present invention this read-out can be used to control the variable speed means rotating the dispensing cylinder so that a constant and su~.stantially~unvaria~le weight of scrap pieces can be delivered by the conveyor ~elt to feed the process previously referred to. Control is made relatively easy by having both cylinders powered by hydraulic motors which by known cir-cuitry can be made to control the speed wi.th which the dispensing cylinder is driven in response to the read-out provided by the weighing conveyor. Prefer-ably the combing cylinder is of the smaller diameter while the dispensing cylin-der is of larger diameter as required to cover the hopper bottom, and the combing roller is driven preferably at rotative speeds substantially faster than those of the dispensing cylinder.
The tee~h projecting radially from the two cylinders should have a height and spacing relative to each other which are no longer than the lengths of the chips being dispens0d.
An example of the invention is illustrated by the accompanying drawings in wh~ch:
~igure 1 is a side elevation;
Figure 2 is an end elevation; and ~igure 3 schematically shows the two cylinders with their teeth as well as the intermeshing action of the teeth of the respective cylinders.
In the above drawings Figures 1 and 2 show the apparatus as having a supporting frame 1 in which the large diameter dosing or dispensing cylinder 2 is~journaled, the frame also journaling the horizontally offset combing cylinder 3, the two cylinders being parallel and laterally spaced and providing clearance for the teeth 4 of the dispensing cylinder 2 and the teeth 5 of the combing cylinder 3. The tee~h can be ormed by pins, nalls, rods Oe small diameter and the like, and their radial lengths and relative interspacing in the axial direc-tion of the cylinders 2 and 3 should provide interstices no larger or not much larger than the average lengths of the chips removed from the open bottom of the 6'~
hopper 6 by the dispens;ng cylind~er 2. ~s illustrated by the arrows in Figure 1, the dispensing cy~lin~er 2 and the combing cylinder 3 rotate in opposite directions so that a downward feed is o~tain0d via the space between the two rollers.
Above the dispensing roller 2 of relatively large diameter, the hopper 6 ~s mounted on the frame 1 so t~at the hopper's open bottom is covered coexten-sively ~y the periphery of the dispensing cylinder 2. The walls of the hopper 6 expand or flare downwardly via one or more angled flat sides so that the cross-sectional area of the hopper increases in a downward direction to its open bottom, contrary to the usual hopper design. This permits the scrap pieces to fall in the hopper more freely and with less compaction by the weight of superimposed scrap such as would occur with the usual hopper design. The frame 1 which is internally open to permit the scrap to fall from the cylinder 2, also mounts the weighing conveyor 7 previously mentioned.
This weighing conveyor is shown as powered by a hydraulic motor 8, the cy:linders 2 and 3 being respectively powered also by hydraulic motors 8a and 8b, all as shown by Figure 2. Hydraulic motors are variable speed motors and are easily speed-controlled by the rate of hydraulic input. With the weighing con-veyor 7 providing its conventional output signal, ~his can be used to control the speeds of all of the motors, but particularly the motor 8a which powers the cylinder 2.
In operation of the example illustrated by the drawings, the speed of the dispensing cylinder 2 was 2 rpm with a circumferential velocity of 3.77 m/min and the rotation speed of the combing cylinder 2 was 19 rpm, giving it a circum-~erential velocity of 12 m/min.
T~e downwardly increasing cross-sectional area of the hopper 6 is ef-fectiye in prevonting undue settling and compaction of the chips at the hopper's bottom. In addition, the hopper is made to be oscillatory in the axial direction ~6~
of the dispensing cylinder 2 as îndicated ~y the arrows in ~igure 2.
In operation, steel chips are charged into the open top of the hopper ~ so as to accur~ulate upwardly from its open bottom where the teeth 4 of the rotating dlspensing cyl~nder 2 pick of the chips more or less individually and carry them downward to the right as the apparatus is shown by Figure 1. Chips whlch may have become wedged between the teeth ~ of the dispensing cylinder are com~ed out by the teeth 5 of the combing roller 3 which rotates oppositely at a higner periphery velocity than that of the dispensing cylinder.
The chips then fall downwardly relatively free or co~pletel~ free from entanglement and onto the horizontal upper span of the weighing conveyor 7 which carries the chips to the left, again referring to the Pigure 1 view.
~ith the weighing conveyor 7 providing its usual output or signal which is dependent on the weight carried by the upper span of the conveyor, this output or signal can in known manner be used to control the speed of the hydraullc motors 8a and 8b. In this way the rotative and, therefore, feeding rate of the dispensing cylinder 2 can be varied as required so that the conveyor provides a constant feed of predetermined weight of chips as required by the method of the application.
Although the invention has been described hereinabove as particularly 2Q adapted for the feeding at a predetermined weight rate or dose of steel chips, its princip~es may be used ~or the dispensing of chips of other material.
_ 10 -
The invention relates to a method for recovering residual matter which accumulates in the production and machining of steel. The matter recovered is in the form of metal-containing dust and chips and is Eormed into briquettes by the addition oE a binder. The invention further relates to an apparatus for dispensing comminuted metal chips which are for instance useful for :Eorming bri-quettes w~th~dust.
The subject oE reco~ering residual matter has been treated for a long time but is of increasing imp~r~ance in recent tlmes in connection with develop-ing shortages of raw materials and the difficulties of finding suitable deposi-tion sites. Since the residual matter has a high metal content consisting of iron and expensive alloying elements, such as chromium and nickel, its reuse for saving more expensive raw materials is of interest. To this must be added that transport and disposal of residual matter, which is usually in the form of fine dust, presents some problems with respect to pollution of the environment.
Thus numerous proposals have been made for reprocessing residual matter w~th the goal of re-using it in the production of steel.
~rom German patent publication AS 23 ~1 742, for instance, a method is known, according to which spherical briquettes are made from four components, namely, sludge, a coarse component with a grain size ~ 100 ~m, a fine component 2Q with a grain size ~ 100 ~m and a binder. These components are mlxed and pressed, but prior to pressing the mixture must be heated, to a temperature at which the binder becomes liquid. It is a disadvantage oE this known method that the con-tent of the fines component with a grain size of less than 100 ~m, which is very difiicult to process, is limited to a maximum of 25%, because dust in this size spectrum constitutes by far the largest part of the waste products accumulated.
In addition, a continu~usly operating platform conveyor oven is required to heat the mixture so as to liquify the binder. S~nce, according to the known method, -- 1 -- ~
~, ~L6~64~
sludge is an absolutely essential componen~ of the mixture, it is not immediately clear how residual matt0r which accumulates only in tlle dry sta~e can be pro-cessed for recovery.
The same applies to the method known from German patent publication AS 25 31 ~57, in which the sludge component must first be dehydrated down to a water content of 2 to 15% by weight before the binder and the dust component areadmixed. This latter method requires heating the briquettes to 35~C to remove th~ residual moisture and is, therefore, relatively elaborate and expensive.
According to German patent publication AS 24 27 619, finely divided wastes which contain carbon and at least 5% iron, are mixed with a bituminous binder, the mixture is formed into briquettes, and the briquettes are treated for 30 to 90 m~nutes with an oxygen-containing gas at 170 to 320C. This heat treat-ment, however, is expensive and is to be applled only: ~a) to waste accumulatingin the production of iron and steel in powder or dust form, i.e., blast-furnace flue dust, converter dust, rolling scale~ coke dust and flux; or (b~ to scrap from foundries and machine shops, namely, lathe and drill press chips. Mixtures ; of fine with coarse grain fractions are not provided in this method. If chips are used, their dimensions should not exceed 6 mm; if necessary, they are to be comminuted, which means additional costs.
2Q It is an object of the invention to provide a method of processing metal-containing dust and metal chips, as the residual matter obtained in the largest quantities in the production and machining of steel, in a simple and cost-effective manner.
The in~ention is based on the disco~ery that the metal-containing dust preci~itated in filters contains, among other things, free lime, which upon ex-tended storage of the briquettes formed from the dust, causes the briquettes to decay because they absorb moisture. It has also been found that in pressing L6~
briquettes of metal-containing dust and metal chips, certain mixing ratios must be obs-erved in order to facilitate pressing.
The invention provides in a method for recovering residual matter of the type accumula~ed as metal-containing dust and chips in the production and machining of steel, forming the residual ma~ter into briquettes, and adding binder, the steps comprising: adjusting the moisture content of the metal-containing residual matter to contain approximately 2 to 8% by weight of water to hydrate free lime contained in the dust; or treating the mixture with a cor-responding amount of steam, mixing the dust with metal chips in a ratio of ap-proximately 7~ : 20 to 30 : 60; and adding approximately 2 to 10% by weight of a binder, based on thc total amount of the mixture.
After hydration of the free lime contained in the dust, the danger of premature disintegration of the residual-matter briquettes is reduced.
According to one advantageous embodiment of the method according to the invention, the dus* is to be mixed with metal chips, the length of which is 7 to 30 mm and preferably, 7 to 15 mm in the ratio 70 : 20 to 30 : 60 and 2 to 10% by weight, and preferably 3 to 6% by weight, of a binder are added to the mixture. Contrary to the method known from German patent publication AS 23 61 742, supra, in which the dust content is to be limited to 25% maximum, 2a a h~gher dust content of 30 to 70% can be processed in the method according to the invent~on. This is uf great importance because o~ the relatively high mass content of dust as compared ko the contents of residual matter in other forms.
The increased amount of dust that can be processed into briquettes is based, in addition to the preceding hydration of the free lime~ on the fact that metal chips of a given length, which is not ~o be smaller than 7 mm and not larger then 30 mm, are to be used. ~etal chips with a length in this range form an ideal matrix in which the dust, provided with the binder, settles so that 4~
! the cohesion of the ~riquettes is assuredl if suitable 6inders are used. Such binders are bitumen or water glass> also without the use of water, which must always be present, besides the binder, in known methods in order to render the mixture of residual matter capable of being processed.
However, according to the invention, waker is added in an amount of 2 to 8% by weight, and preferablyJ 3 to 6% by weight so that the binder content can be reduced accordingly. It is of advantage ~o adjust the mixture to a residual moisture content corresponding to the water content in the hydration treatmen~.
Sludge accumulated in wet filters may also ~e used if it is converted into dry dust by drying and comminuting.
The method according to the invention is ad~antageously distinguished from the above-mentioned known methods in that durable briquettes made of the types of residual matter which are produced in the largest quantities, namely, dust and metal chips, can be produced in a relatively simple and cost-effective manner .
Th~ method according to the invention will now be expalined in greater detail with the aid of the following examples. While Examples 1 and 2 were car-ried out by the method according to the invention, a sample pressed from dust only was used for comparison in Example 3.
Example 1 Electric-~ilter dust from the production of stainless steel was moistened ln an intensive mixer to 6% water and then digested for a period of 3 days. During this time, the lime contained in the electric-filter dust was burned to calcium hydroxide.
After the digestion, 70 parts of electric-filter dust were mixed with 3~ parts chips~having a length in the range of 10 to 25 mm which had been pro-duced in grinding ingot slabs of stainless steel. The metal chips can also be mixed w~th the filt0r dust during the moistening with water. The mixture was adjusted to 6.3% moisture3 and 5% cellulose powder ~dry component of the sulfite waste~ was added.
Then, the mixture was fed, via a dosing and precompaction worm, to a cylinder briquetting press. With a circumferential cylinder velocity of 0.33 m/s, a set pressure of 28 kN/cm cylinder width and a briquette volume of the briquet-ting cylinders of lO cm3, briquettes with a specific gravity of 3.53 g/cm3 were produced.
The dropplng strength of the briquettes produced was 3.5 m after leav-ing the press. After the briquettes were hardened at room temperature for 3 days, a cold compression strength of the briquettes of 115 daN/briquette was measured.
Example 2 In thls example, the ratio of the electric-filter dust to the grinding cH~ps was set to ~0 : 50. The other data may be seen from the following Table.
~s shown in the Table, it was possible to achieve a dropping strength of the ~riquettes of 4~0 m after leaving the press. The cold compression s~rength of the briquettes after hardening for 3 days was 175 daN/briquette.
Example 3 In this reference example, ~hich does not corre~pond to the invention, 2Q no metal chips were added to the filter dust. The other data may be found in the follo~ing Table.
The dropping strength of these briquettes after leaving the press was only Q.7 m. The cold compression strength after hardening for 3 days was 50 daN/~riquette.
The examples show that the binding-in of metal chips, with the effect af a reinforcement, leads to an unusually high dropping strength of the finished ; briquettes and to a very good cold compression strength of the hardened bri-quettes.
.6~6 ~
Table Process 5teps Example Moisten F.-filter dust to (%H20~ 6 6 6 Digestion time ~days) 3 3 3 Mixing; rat~o E-filter dust/chips (pts/pts) 70/30 50/50 100/0 Residual moistening of moisture to (% H20) 6.3 5.4 7.3 Binder addi~ion, cellulose powder (%) 5 3 7 Briquetting with cylinder pressure (kN/cm) 28 26 24 Briquette volume (cm3~ cylinder width 11 11 11 Quality of the brlquettes a) Dropping strength after leavlng press 3.5 4.0 0.7 Dropping helght (m) b~ Cold compression strength a~ter hardening 115 175 50 for 3 days (daN/brlquette) Specific gravity of the brlquettes (glcm ) 3.53 3.84 2.85 The inventlve method requires proportloning of the metallic dust and chips to form a mixture whlch with the addltlon o~ a blnder and processlng ls brlquetted. A measured feed of the chips for mixing with the dust is required.
The chips can intertangle to form accumulations which must be broken up for feed-lng.
It ls therefore another object of the inventlon to provlde a metal chip dispenslng app ratus sultable for application to the above kind of method but whic~ ma~ be used whenever metallic chips or the like must be fed or dis-pensed in comminuted form.
; The invention provides an apparatus for dispensing metal chips, com-pr~slng a hopper adapted to be loaded wlth the chips and ha~ing an open bottom, G~
a rotative dispensing cylinder having a peripllery e~tending across and covering said Bottom, a multiplici~y of interspaced teeth projecting radially from said periphery, and variable~speed means for rotating said cylinder.
The interspaced teeth may be pins, nails or the like, and ~he cylinder is preferably made oscillatory in the axial direction of this cylinder. Means are provided for combing chips from between the dispensing cylinder's teeth and comminuting ~he chips. Below the dispensing cylinder, means are provided for conveying away while preferably also weighing the chips falling from the cylinder.
The above combing means can comprise a stationary comb or preferably lQ compr~ses a rotative cylinder positioned parallel to the dispensing cylinder and having a periphery from which a multiplicity of interspaced teeth project radi-ally, and these teeth may also be in the form oE pins or nails. The relatlve lengths and positions o~ the first and second mentioned teeth are such as to cause the respective teeth to intermesh without interference when the two cylin-ders are rotated in opposite directions with the hopper oscillating.
Both rotative cylinders are provided with variable-speed means for rotating or driving them respectively in opposite directions and so that scrap pieces feeding from the hopper are fed do~nwardly between the two cylinders, the combing cylinder being driven the fastest to provide effective combing action.
2Q This positively frees any entanglement of scrap pieces and assures that the pieces fall substantially all separated from each other onto an underlying weighing conveyor which forms the previously mentioned means for weighing and carry~ing away the pieces.
Commercially available weighing conveyors provide a read-out which normally~continuously~multiply~weight by travel to give tonnage passing over the conveyor, and with the present invention this read-out can be used to control the variable speed means rotating the dispensing cylinder so that a constant and su~.stantially~unvaria~le weight of scrap pieces can be delivered by the conveyor ~elt to feed the process previously referred to. Control is made relatively easy by having both cylinders powered by hydraulic motors which by known cir-cuitry can be made to control the speed wi.th which the dispensing cylinder is driven in response to the read-out provided by the weighing conveyor. Prefer-ably the combing cylinder is of the smaller diameter while the dispensing cylin-der is of larger diameter as required to cover the hopper bottom, and the combing roller is driven preferably at rotative speeds substantially faster than those of the dispensing cylinder.
The tee~h projecting radially from the two cylinders should have a height and spacing relative to each other which are no longer than the lengths of the chips being dispens0d.
An example of the invention is illustrated by the accompanying drawings in wh~ch:
~igure 1 is a side elevation;
Figure 2 is an end elevation; and ~igure 3 schematically shows the two cylinders with their teeth as well as the intermeshing action of the teeth of the respective cylinders.
In the above drawings Figures 1 and 2 show the apparatus as having a supporting frame 1 in which the large diameter dosing or dispensing cylinder 2 is~journaled, the frame also journaling the horizontally offset combing cylinder 3, the two cylinders being parallel and laterally spaced and providing clearance for the teeth 4 of the dispensing cylinder 2 and the teeth 5 of the combing cylinder 3. The tee~h can be ormed by pins, nalls, rods Oe small diameter and the like, and their radial lengths and relative interspacing in the axial direc-tion of the cylinders 2 and 3 should provide interstices no larger or not much larger than the average lengths of the chips removed from the open bottom of the 6'~
hopper 6 by the dispens;ng cylind~er 2. ~s illustrated by the arrows in Figure 1, the dispensing cy~lin~er 2 and the combing cylinder 3 rotate in opposite directions so that a downward feed is o~tain0d via the space between the two rollers.
Above the dispensing roller 2 of relatively large diameter, the hopper 6 ~s mounted on the frame 1 so t~at the hopper's open bottom is covered coexten-sively ~y the periphery of the dispensing cylinder 2. The walls of the hopper 6 expand or flare downwardly via one or more angled flat sides so that the cross-sectional area of the hopper increases in a downward direction to its open bottom, contrary to the usual hopper design. This permits the scrap pieces to fall in the hopper more freely and with less compaction by the weight of superimposed scrap such as would occur with the usual hopper design. The frame 1 which is internally open to permit the scrap to fall from the cylinder 2, also mounts the weighing conveyor 7 previously mentioned.
This weighing conveyor is shown as powered by a hydraulic motor 8, the cy:linders 2 and 3 being respectively powered also by hydraulic motors 8a and 8b, all as shown by Figure 2. Hydraulic motors are variable speed motors and are easily speed-controlled by the rate of hydraulic input. With the weighing con-veyor 7 providing its conventional output signal, ~his can be used to control the speeds of all of the motors, but particularly the motor 8a which powers the cylinder 2.
In operation of the example illustrated by the drawings, the speed of the dispensing cylinder 2 was 2 rpm with a circumferential velocity of 3.77 m/min and the rotation speed of the combing cylinder 2 was 19 rpm, giving it a circum-~erential velocity of 12 m/min.
T~e downwardly increasing cross-sectional area of the hopper 6 is ef-fectiye in prevonting undue settling and compaction of the chips at the hopper's bottom. In addition, the hopper is made to be oscillatory in the axial direction ~6~
of the dispensing cylinder 2 as îndicated ~y the arrows in ~igure 2.
In operation, steel chips are charged into the open top of the hopper ~ so as to accur~ulate upwardly from its open bottom where the teeth 4 of the rotating dlspensing cyl~nder 2 pick of the chips more or less individually and carry them downward to the right as the apparatus is shown by Figure 1. Chips whlch may have become wedged between the teeth ~ of the dispensing cylinder are com~ed out by the teeth 5 of the combing roller 3 which rotates oppositely at a higner periphery velocity than that of the dispensing cylinder.
The chips then fall downwardly relatively free or co~pletel~ free from entanglement and onto the horizontal upper span of the weighing conveyor 7 which carries the chips to the left, again referring to the Pigure 1 view.
~ith the weighing conveyor 7 providing its usual output or signal which is dependent on the weight carried by the upper span of the conveyor, this output or signal can in known manner be used to control the speed of the hydraullc motors 8a and 8b. In this way the rotative and, therefore, feeding rate of the dispensing cylinder 2 can be varied as required so that the conveyor provides a constant feed of predetermined weight of chips as required by the method of the application.
Although the invention has been described hereinabove as particularly 2Q adapted for the feeding at a predetermined weight rate or dose of steel chips, its princip~es may be used ~or the dispensing of chips of other material.
_ 10 -
Claims (16)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a method for recovering residual matter of the type accumulated as metal-containing dust and chips in the production and machining of steel, form-ing the residual matter into briquettes, and adding binder, the steps comprising:
adjusting the moisture content of the metal-containing residual matter to contain approximately 2 to 8% by weight of water to hydrate free lime con-tained in the dust; or treating the mixture with a corresponding amount of steam, mixing the dust with metal chips in a ratio of approximately 70 : 20 to 30 : 60; and adding approximately 2 to 10% by weight of a binder, based on the total amount of the mixture.
adjusting the moisture content of the metal-containing residual matter to contain approximately 2 to 8% by weight of water to hydrate free lime con-tained in the dust; or treating the mixture with a corresponding amount of steam, mixing the dust with metal chips in a ratio of approximately 70 : 20 to 30 : 60; and adding approximately 2 to 10% by weight of a binder, based on the total amount of the mixture.
2. The method of claim 1 in which water is added in an amount of 3% to 6%
by weight to the dust.
by weight to the dust.
3. Method of claim 1 wherein the water content of the mixture is adjusted in the hydrating treatment to a residual moisture corresponding to the water content.
4. The method according to claim 1 comprising, in addition:
briquetting the mixture in a cylinder press at a cylinder pressure of 20 to 80 kN/cm of cylinder width, and hardening the briquettes by storage at room temperature for a period of about 1 to 2 days.
briquetting the mixture in a cylinder press at a cylinder pressure of 20 to 80 kN/cm of cylinder width, and hardening the briquettes by storage at room temperature for a period of about 1 to 2 days.
5. The method according to claim 1, 3 or 4 in which the dust component of the mixture is filter dust accumulated in the production of stainless steel.
6. The method according to claim 1, 3 or 4 in which the chips are grinding chips produced in the grinding of ingot, ingot slabs blocks, plates and sheets of stainless steel.
7. The method according to claim 1, 3 or 4 in which the binder comprises cellulose powder, a molasses-lime mixture, soda or bitumen.
8. An apparatus for dispensing metal chips, comprising a hopper adapted to be loaded with the chips and having an open bottom, a rotative dispensing cylinder having a periphery extending across and covering said bottom, a multi-plicity of interspaced teeth projecting radially from said periphery, and variable-speed means for rotating said cylinder.
9. The apparatus of claim 8 in which said hopper has a cross-sectional area that increases downwardly to said open bottom.
10. The apparatus of claim 8 in which said hopper is oscillatory in the axial direction of said cylinder.
11. The apparatus of claim 8 having means for combing chips from between said teeth and comminuting said chips.
12. The apparatus of claim 11 in which said means comprises a rotative combing cylinder positioned parallel to said dispensing cylinder and having a periphery from which a multiplicity of interspaced teeth project radially, the relative lengths and positioning of the first-named and second-named teeth caus-ing the respective teeth to intermesh, and variable-speed means for rotating said combing cylinder so as to permit the latter to rotate at the same speed as or a different speed from the dispensing cylinder.
13. The apparatus of claim 12 having below said cylinders means for con-veying away while weighing chips falling from the cylinders.
14. The apparatus of claim 8, 9 or 10 in which said variable speed means comprise hydraulic rotary motors.
15. The apparatus of claim 11, 12 or 13 in which said variable speed means comprise hydraulic rotary motors.
16. The method according to claim 1 comprising, in addition:
briquetting the mixture in a cylinder press at a cylinder pressure of 30 to 40 kN/cm of cylinder width, and hardening the briquettes by storage at room temperature for a period of about 1 to 2 days.
briquetting the mixture in a cylinder press at a cylinder pressure of 30 to 40 kN/cm of cylinder width, and hardening the briquettes by storage at room temperature for a period of about 1 to 2 days.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3016194A DE3016194C2 (en) | 1980-04-26 | 1980-04-26 | Device for the dosed delivery of metallic chips |
| DEP3016194.5 | 1980-04-26 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1161649A true CA1161649A (en) | 1984-02-07 |
Family
ID=6101061
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000376237A Expired CA1161649A (en) | 1980-04-26 | 1981-04-24 | Method for recovering residual matter accumulated in the production and machining of steel and apparatus for dispensing metal chips |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS56166981A (en) |
| BR (1) | BR8102483A (en) |
| CA (1) | CA1161649A (en) |
| DE (1) | DE3016194C2 (en) |
| SU (1) | SU1292662A3 (en) |
| ZA (1) | ZA811740B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3232803C2 (en) * | 1982-09-03 | 1985-07-04 | O & K Orenstein & Koppel Ag, 1000 Berlin | Loading device for continuously conveyed, pourable to heavy-pourable bulk material |
| DE102007056330A1 (en) * | 2007-11-22 | 2009-05-28 | Egon Evertz Kg (Gmbh & Co.) | Method and device for producing binderless compacts from metal shavings and / or metal dusts |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AT177374B (en) * | 1948-04-30 | 1954-01-25 | Oswald F Dr Wyss | Storage container with device for even removal of chip and fiber materials u. like |
| DE926883C (en) * | 1953-08-15 | 1955-04-25 | Losenhausenwerk Duesseldorfer | Dosing scales with electrically controlled material feed |
| DE1786766U (en) * | 1958-12-22 | 1959-04-09 | Fredenhagen Kommanditgesellsch | DEVICE FOR DISCHARGING AND EVEN FEEDING UNEQUALIZED PIECES FROM A CONTAINER ON A FEORDER OR OTHER PICKUP. |
| DE1819780U (en) * | 1960-03-30 | 1960-10-13 | Parex Spezialmaschinen Horst G | BINNER DISCHARGE DEVICE FOR MATERIAL TENDING TO BRIDGE FORMATION. |
| DE2442189A1 (en) * | 1974-09-02 | 1976-03-11 | Guenther Prof Dipl In Heitmann | Material discharge roller with eccentric rods - has rod carrier eccentric inside rotary tube to vary protruding lengths |
| JPS54155237A (en) * | 1978-05-29 | 1979-12-07 | Nobuo Serizawa | Constant quantity feeder |
-
1980
- 1980-04-26 DE DE3016194A patent/DE3016194C2/en not_active Expired
-
1981
- 1981-03-16 ZA ZA00811740A patent/ZA811740B/en unknown
- 1981-04-17 JP JP5727281A patent/JPS56166981A/en active Pending
- 1981-04-21 SU SU813273764A patent/SU1292662A3/en active
- 1981-04-24 BR BR8102483A patent/BR8102483A/en unknown
- 1981-04-24 CA CA000376237A patent/CA1161649A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| SU1292662A3 (en) | 1987-02-23 |
| JPS56166981A (en) | 1981-12-22 |
| DE3016194C2 (en) | 1984-07-05 |
| BR8102483A (en) | 1982-01-05 |
| ZA811740B (en) | 1982-09-29 |
| DE3016194A1 (en) | 1981-11-05 |
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