US2317139A - Froth breaking - Google Patents

Froth breaking Download PDF

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US2317139A
US2317139A US285488A US28548839A US2317139A US 2317139 A US2317139 A US 2317139A US 285488 A US285488 A US 285488A US 28548839 A US28548839 A US 28548839A US 2317139 A US2317139 A US 2317139A
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froth
collecting agent
pulp
aqueous
reagent
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US285488A
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Frantz Philip Morhiser
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Colorado Fuel and Iron Corp
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Colorado Fuel and Iron Corp
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B03SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
    • B03DFLOTATION; DIFFERENTIAL SEDIMENTATION
    • B03D1/00Flotation
    • B03D1/08Subsequent treatment of concentrated product

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  • my invention contemplates breaking said froth by incorporating an aqueous lstarch emulsion therein. I have found, further, that the presence of an acid or base in the emulsion, so that the latter is not neutral and has a pH othe'i ⁇ than 7, aids greatly in froth breaking.
  • a froth comprising gas-filled bubbles coated with a collecting agent to which mineral particles are adhering by aeration of an aqueous mineralbearing pulp containing the collecting agent
  • the improvement which comprises incorporating in said froth an aqueous starch emulsion of high protein content and thereby destroying the froth.
  • a froth comprising gas-filled bubbles coated with a collecting agent to which mineral particles are adhering by aeration of an aqueous mineralbearing pulp containing the collecting agent
  • the improvement which comprises incorporating in said froth an aqueous starch emulsion having a protein content of at least on the weight of the starch.

Description

P. MFRANTZ 2,3739
FROTH BREAKING iled July 20, 1939 I. 'i eff/alw Za Waffe ATTORNEYS Patented Apr. 20, v1943 ric FROTHBREAKING Philip Morliiser Frantz, Pueblo, Colo., assignor to The Colorado Fuel and Iron Corporation, Denver, Colo., a corporation of Colorado Application July 20, 1939, Seriali No. 285,488
14 Claims.
'Ihis invention relates to breaking froth and particularly mineral-bearing froths derived in ore dressing and the like.
In the concentration of minerals by froth flotation, a froth is formed which comprises gasfilled bubbles coated with a film of collecting agent with mineral particles adhering thereto. The froth usually is formed by aeration of an aqueous suspension or pulp of a mineral aggre'- gate in the presence of one or more otation agents which usually are of soapy or oleaginous character. The froth forms on top of the pulp and is removed therefrom by simple overflow or by skimming or sluicing. The froth usually contains considerable entrained water.
, The froth, once it is separated from the pulp, ordinarily is subjected to further treatment including a. de-watering or filtration operation. If the froth is very tenacious and resists destruction by agitation and the like, de-watering, ltration and other subsequent operations are conducted with difficulty. Thus, a persistent froth may result in an unsatisfactory lter cake.
'Ihe froth formed in the otation of fine coal and other non-metallic minerals is oftemmost tenacious and is de-watered or otherwise treated to reduce its bulk with great difficulty. As a result of my investigations, however, I have discovered that the incorporation of a starch emulsion into tenacious froths results in destruction of bubbles and in conditioning the froth so that even upon subsequent aeration the bubbles do not re-form to a substantial extent.,V I have found, further, that froths so treatedare much more amenable to filtration and the like,
Thus, in a process involving the formation of a froth comprising gas-filled bubbles coated with a collecting agent to which mineral particles adhere, my invention contemplates breaking said froth by incorporating an aqueous lstarch emulsion therein. I have found, further, that the presence of an acid or base in the emulsion, so that the latter is not neutral and has a pH othe'i` than 7, aids greatly in froth breaking.
The emulsion is made conveniently by boiling flour or other material of high starch content in c Water, and thereafter adding to the resulting pastean acid or base. Any suitable water-soluble base, such as alkali metal hydroxides, ammonium hydroxide, or calcium hydrate may be employed ployed. Thus, I have found that acetic acid, strong mineral acids, such as nitric acid, hydrochloric acid, and sulfuric acid, and organic acids, and acid-containing substances such as cresylic acid, creosote, tar acids and crude or refined phenols, may be used advantageously.
I have found further that a' starch of high I amount of flotation reagent present in the froth.
The reagent apparently reacts in some way with most oleaginous or soapy connecting agents to form new compounds which do not tend to maintain froth. In 4any case, as the amount of otation reagent in thefroth is increased, the amount of froth breaking reagent needed must also be increased, but an excess of froth breaking reagent over and abovethat necessary to accomplish adequate froth destruction does not result in improvement and represents a waste. 'I'he amount of froth breaking reagent necessary will vary somewhat depending upon the'nature of the flotation reagent employed. Generally speaking. however, the proportion of froth breaking reagent necessary is always less than the flotation reagent consumed, and, in fact, the amount of starch employed in froth breaking need not exceed r of the weight of the collecting agent consumed.
These and other aspects of my invention will be more thoroughly understood in the light of the following detailed description of presently preferred practices thereof, taken in conjunction with the accompanying single gure which is a flow sheet of a coal ilotation operation embodying the practice Iof my invention. n v
Referring now' to the ligure, it will be observed that an aqueous pulp I0 of fine coal mixed with gangue material and a large proportion of water (derived from customary coal washing operations) is passed to a Dorr thickener I I of conventional constructiom The coal and contaminating gangue materials tend to settle in the thickener and are removed as a thickened underflow I2. An aqueous overow I3 containing substantially no coal is derived from the thickener and sent to waste.
The coal-bearing underflow from the thickener is sent to a. coal flotation apparatusV I4 which may be any suitable froth flotation machine and is there agitated and aerated by' -oleaginous character, are also introduced into the flotation machine and a coal-.bearing froth i1 is formed in the conventional manner. The froth is removed from the flotation machine by sluicing or skimming and the tailings I8 pass out of the machine and are sent to waste.
VA great variety of oleaginous or soapy flota'- tion agents may be employed in the treatment of the coal. In one instance, the flotation reagent employed was a paraflin base crude oil diluted with kerosene to which had been added 10% by weight of creosote. Another suitable reagent comprises coal tar distillate having a gravity of about .825 to which is added 5% by Weight of tar acids. Such reagents may be employed ap propriately in the treatment of a coal-bearing pulp containing about 18% solids having the following screen analvsis:
- the pulp.
As indicated hereinbefore, a great variety 'of lli-sh Weight feighl latir@ weight Pcrcen! Per ccnl 11H-35. Y Y l0. 0 3. 42 3. 76
10U-H501.. 26.0 8.90 49.56 ,l50+200. l.. 20.2 6.85 56.41
boiling onepart =-of flour, preferably 'of high protein content, in 100 parts of water. To this boiling mixture, there is added one-half part of .Y
an acid or alkali (say acetic acid or sodium hydroxide) in a hot concentrated aqueous solution.
Very small proportions of such an emulsion are necessary for adequate froth destruction. Thus, I have found that with froth formed in the foregoing manner it is sufficient to employ about .13 lb. of flour and .065 lb. of ton of solids in the froth.
The ratio of starch to water and'caustic or acid employed is not critical. However,in general, it will be found that an emulsion made of one part of flour or starch, 100 parts of water and caustic 'per about one-half part of acid or alkali will -pro duce a verysatisfactory reagent and one which isV thin' enough toY be incorporated easily Ainto alkalies and acids may'be employed. I have found that the best reagents to employ with the starch or flour are, in the order of their eiliciency, caustic soda, acetic acid and crude creo- Y sote. v
it flows, usually with additional sluicing water. in a launder from the flotation machine. Good results may also be obtained by introducing a large batch of the froth into a tank into which the froth-breaking reagent is also introduced. the whole being agitatedpfor a short period of time, say ve minutes. Ordinarily,'however, it is better to break the froth in a continuous operationby passing it continuously through a small agitator I9 to which the froth-breaking reagent 20 in. appropriate proportion is continuously supplied.
As indicated hereinbefore, the higher the protein content of the starch within limits, the more effective is the froth-breaking reagent in which the starch is incorporated. Thus, I have found that bean fiour made byV comminution of navy beans and containing about 22% protein is approximately twice as effective in frothbreakingfas is a low-grade wheat flour containing about 12% protein, and in the practice of the invention, I prefer to employ a material containing at least 10% of protein on the weight of the starch.
The use of the froth-breaking reagent in the treatment of flotation pulps` results inA a great improvement in ltration operations conducted upon the solids present in the froth. Thus, I have found that when the coal froth made as described hereinbefore is treated on a continuous filter withoutuse of the frotl'vbreaking reagent. a very soft wet cake is formed and the filtration rate is very slow. The resulting cake contains about 39% moisture. On the other hand, when .an identical froth is treated on identical apparatus after incorporation of the froth-breaker, I find that the broken froth filters approximately four times as fast and forms froths containing rock phosphates, fluorspar, or
other non-metallic minerals. However, the process of my invention is also applicable to the destruction of flotation froths of minerals of metal- 'lic' surface. such as those derived from the concentration of sulfide ores of copper, zinc. and the like. But the collecting agents employed in the notation of sumdes. and the like, seldom result in a tenacious froth.
I have found that, generally speaking, acid froths or froths derived from acid pulps break more easily than do froths derived from basic or neutral pulps. Likewise, alkaline froths or froths derived from alkaline Vpulps break more 6d easily .than do neutral pulp's. Consequently, for
most effective practice 'of my invention, the pulp from which the froth is derived should be maintained with a pH that is definitely off the neutrai point, i. e., above or below 7. and the frothbreaking reagent should be acid in the event that the pulp is acid and vice versa. However, the amount of froth-breaking reagent employed is ordinarily insufficient to bring about any substantial change in* the pH of .the froth.
As shown in the flow sheet, coal slurry 2| resultingfrom incorporation of the froth-breaking reagent in the froth is subjected to filtration `on a filter 22 such, for example, as an Oliver filter,
.a Dorrco filter, or an American leaf-type filter. Filter cake 23 from this operation is subjected: i
to drying in any suitable dryer 24 and the dried fine coal 25 is ready for market.
I claim:
1. In a process involving the formation of a froth comprising gas-filled bubbles coated with a collecting agent to which mineral particles are adhering by aeration of an aqueous mineralbearing pulp containing the collecting agent, the improvement which comprises incorporating in said froth an aqueous starch emulsion of high protein content and thereby destroying the froth.
2. In a process involving the formation of a froth comprising gas-filled bubbles coated with a collecting agent to which mineral particles are adhering by aeration of an aqueous mineralbearing pulp containing the collecting agent, the improvement which comprises incorporating in said froth an aqueous starch emulsion having a protein content of at least on the weight of the starch.
3. In a. process involving the formation of a froth comprising gas-filled bubbles coated with a collecting agent to which mineral particles are adhering by aeration of an aqueous mineralbearing pulp containing the collecting agent, the improvement which comprises incorporating in said froth an aqueous starch emulsion derived from bean flour.
4. In a process involving the formation of a froth comprising gas-filled bubbles coated with a collecting agent to which mineral particles are adhering by aeration of an aqueous mineral-f. bearing pulp containing the collecting agent, the improvement which comprises incorporating in said froth an aqueous starch emulsion derivedv from wheat flour containing at least 10% by weight of protein.
5. In a process involving the formation of a froth 'comprising gas-lled bubbles coated with a collecting agent to which mineral particles are adhering by aeration of an aqueous mineralbearing pulp containing the collecting agent, the improvement which comprises incorporating in the froth an alkaline aqueous starch emulsion.
v6. In a process involving the formation of a froth comprising gas-filled bubbles coated With a collecting agent to which mineral particles are adhering by aeration of an aqueous mineralbearing pulp containing the collecting agent, the improvement which comprises incorporating in said froth an acid aqueous starch emulsion.
7. In a process involving the formation of a froth comprising gas-lled bubbles coated with a collecting agent to which mineral particles are adhering by aeration of an aqueous mineral-- bearing'pulp containing the collecting agent, the improvement which comprises incorporating in said froth an aqueous starch emulsion containing alkali metal hydroxide.
8. In a process involving the aeration of an aqueous mineral-bearing pulp in the presence of a collecting agent to form a froth comprising air-filled bubbles coated with the collecting agent to which the mineral particles are adhering and the separation of said' froth from said pulpI the improvement which comprises subsequently subjecting said froth to the action of an aqueousstarch emulsion.
9. In a process involving the aeration of an aqueous mineral-bearing pulp in the presence of a collecting agent to form a froth comprising air-filled bubblesv coated with the collecting agent to which the mineral particles are adhering and the separation of said froth from said pulp, the improvement which comprises subsequently incorporating lin said froth an aqueous starch emulsion and thereafter subjecting the resultant product to filtration.
10. In a process involving the aeration of an aqueous mineral-bearing pulp in the presence of a collecting agent to form a froth comprising airfilled bubbles coated with the collecting agent to which the mineral particles are adhering and the separation of said froth from said pulp, the improvement which comprises maintaining a pH other than 7 in said pulp and incorporating in the froth after separation an aqueous starch emulsion.
11. In a process involving the aeration of an aqueous mineral-bearing pulp in the presence of a collecting agent to "form a froth comprising alrlled bubbles coated with a collecting agent to which the mineral particles are adhering and the separation of said froth from said pulp, the improvement which comprises subsequently adding an aqueous starch emulsion to said froth and subjecting the resultant mixture to agitation to distribute the emulsion therethrough.
12. In a process involving the-aeration of a mineral-'bearing pulp in the presence of an oleaginous collecting agent to form a froth comprising air-filled bubbles coated with the oleaginous agent to which mineral particles are adhering, the improvement which comprises treating the froth after separation thereof from the pulp with an aqueous starch emulsion having a pH other than 7.
13. In a vprocess involvingthe aeration of a 'mineral-bearing pulp in the presence of a collecting agent with resultant formation of a froth comprising gas-filledv bubbles coated with the collecting agent to which the mineral particles adhere, the improvement which comprises incorporating in the froth after separation from the pulp an aqueous starch emulsion, the weight of starch in the emulsion thus incorporated being substantially less than the weight of the collecting agent employed.
14. In a process involving the formation of a froth comprising gas-filled bubbles coated with a collecting agent to which mineral particles are adhering by aeration of an aqueous mineralbearing pulp containing the collecting agent, the improvement which comprises incorporating in said froth an aqueousv starch emulsion containing a strong mineral acid.
PHILIP MORHISER FRANTZ.
US285488A 1939-07-20 1939-07-20 Froth breaking Expired - Lifetime US2317139A (en)

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2665004A (en) * 1949-04-11 1954-01-05 Albert W Zukosky Process for treating froth flotation concentrates
US2757797A (en) * 1953-03-27 1956-08-07 Monsanto Chemicals Water treatment
US2982635A (en) * 1958-12-30 1961-05-02 Texaco Inc Carbon separation process
US3039851A (en) * 1958-12-19 1962-06-19 Commercial Solvents Corp Recovery of carbon black
US3378500A (en) * 1964-11-16 1968-04-16 Sahlberg Carl Robert Process for breaking down foam
US4175035A (en) * 1978-02-27 1979-11-20 Bethlehem Steel Corporation Method for increasing fine coal filtration efficiency
US4244813A (en) * 1979-08-08 1981-01-13 Bethlehem Steel Corporation Method of increasing fine coal filtration efficiency
US4289609A (en) * 1978-05-02 1981-09-15 Uranium Recovery Corporation Process for removing solid organic materials and other impurities from wet-process phosphoric acid
US11279400B1 (en) 2018-01-02 2022-03-22 RBR Enterprise, LLC Adjustable wheel track axle with independent wheel angle control for an agricultural vehicle

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2665004A (en) * 1949-04-11 1954-01-05 Albert W Zukosky Process for treating froth flotation concentrates
US2757797A (en) * 1953-03-27 1956-08-07 Monsanto Chemicals Water treatment
US3039851A (en) * 1958-12-19 1962-06-19 Commercial Solvents Corp Recovery of carbon black
US2982635A (en) * 1958-12-30 1961-05-02 Texaco Inc Carbon separation process
US3378500A (en) * 1964-11-16 1968-04-16 Sahlberg Carl Robert Process for breaking down foam
US4175035A (en) * 1978-02-27 1979-11-20 Bethlehem Steel Corporation Method for increasing fine coal filtration efficiency
US4289609A (en) * 1978-05-02 1981-09-15 Uranium Recovery Corporation Process for removing solid organic materials and other impurities from wet-process phosphoric acid
US4244813A (en) * 1979-08-08 1981-01-13 Bethlehem Steel Corporation Method of increasing fine coal filtration efficiency
US11279400B1 (en) 2018-01-02 2022-03-22 RBR Enterprise, LLC Adjustable wheel track axle with independent wheel angle control for an agricultural vehicle

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