US2470150A - Froth flotation of oxide iron ore - Google Patents

Description

Patented mi 1 1 1m 1 morn nomnonor oxmsmon one 1 a Fred DlDe Vaney, l iibbing,Minnanssignorlto Erie Mining Company, Hibbing,.Minn.,- a cor- I P 9t esota it em, sto t le-art or new? lady-concerned-withithe pre-treatnientand conditioning of; such pulps when using fatty acids, fatty acids soaps,-ta l loel, talloelsoapsor resinates as anionicallyiactingjcollectors. 'f'

In essence,'f-the-proce ss' of the present invention comprise'sflthe following combination or procedural featuresl and,operative-stepsg The pulp is 'cleslimed and given-an acid'wash (1) to clean nparticlesljromaqueous'pulps.- thereoifteontaining also silicious gangue particles, The'proce'ss :ofthejpresent inventionis particu Nqn 'awins. 'ApplicationJanuai-y'z,1946,

SerialNo."638,707 P i 5 came. (01. 209-166) 'ferred up n the deslime'd acting collectors 'with the silicious oxidic iron pulps with which 'the present invention is concerned. Thus, I have found, in working withal-r kali resinate collector s, that if the pH of the circuit be dropped below 8.-2 through addition V thereto of an acid,the resinate collector tends to the surfaces of the dxidic iron particles whereby to enhance theirjfloatability and simultaneously (2) to remove ironslimes from the surface of the silicate minerals whereby to depress the float-- ability 0? the latter; To :eflectthe acid wash, the pulp is thoroughlyadmixed with a suitable acid, usually a-mineral'acid, in an amount equivalent tomore than 1 but not moreathan about 3 pounds'of concentrated sulphuric acid per ton of the pulp, dry-basis. The acid-washed pulp is then repulpedwith fresh water, and then thickened to a solids content of at least 65% and desirablybetween 65% and 80%. The pulp, at

high pulp density, is made mild y yet definitely alkaline by the incorporation thereinto of a suitable alkali, e. g., caustic soda orsoda ash, in an amount sufllcient to give the pulp a pH of from 8.0 to 8.5, e. g.,' about 8.2, depending to some extent upon the identity of the collector. Thereupon, the mildly alkaline pulp is conditioned with breakdown to tree resin and an alkali metal salt of, theadded acid (e. g., sodium'sulphate); in such case, the resin continues .to function as an amonically acting collector but in a manner much i less efieotive than the solubleres'inate- When efiective'compounds an emulsion of the selected anionically acting r agent,e. g., a materially alkaline and quite soluble sodium'resinate soap ora talloel soap, and a suitable oil, e. g., fuel oil. The so-conditioned pulp is ready to be diluted with water to 20-25% solids and subjected to; froth flotation in conventional manner.- I

In the cases o f,certain ores it is'advantageous to first deslimeand then acid wash. With other ores it issimpler to acid wash first and then deslime. Thesetwooperations are interchangeable and the choice; depends on the character of the ore, the type of mill water being used, the soluble salts encountered, etc.

I have found that the degree of alkalinity contors.

working with alkali metal soapsof talloel (which latter consists essentially of'fatty acids and resin acids in approximately equalamounts) much the same result attends lowering thepH of the pulp circuit as in-thecaseof. the soluble'resinates.

Thepetroleum hydrocarbon'sulphonates, such for example as the -well knownmahogany soaps, behave just oppositely they-arei'quites soluble in acidic solutions, but break down to fiotatively inalkaline. 1

The above experimentally derived facts pertain to the efiect of too low a pH value when. working with the above named anionically acting collecf I have found, on the other hand, that too great anflalkalinity of .the.pu lp circuit is equally as disadvantageous as too low a value. Thus, numerous experiments have established that as'the alkalinity is increased above, pH 8.5 l the grade of the resulting concentrate depreciates and at a pH of approximately 9.5 the separation tends to be reversedi. e., tends so to operate as j v to float the silicious particles in'preferencerto the oxidic iron particles.

Table No. 1 immediately following shows the effect of varying the pH on theianionic flotation sota. I

l and acid-washed -pulpu'. prior 'to'conditioning with the aforesaid agents of rea im n e t the? ub e ento i- 1 tioning and. flotation-L -The above referred 'to'; mild alkalinity" is essential to' 'good fiotation results when usingthe above-named; anionically when the pulp circuit is made Table #L-Eflect of varying m on iron ore sion as collector my, Per Cent t pH Flota- Per Cent m Tm tion Pulp Produc Wt. r

Iron Silica Composite 100. 00 14. 94 100. 00

#197 8. 0 Ciiliceili:l'8te. 19. 09 61. 97 0. 66 83. 31 Midd1ing 5. 14 88 7. 11 Tailing 75. 77 1 79 9. 58

Composite. 100. 00 l4. 1!) 100. 00

#206 8 3 Concentrate. 20. 84 53. 57 i8. 94 79. 21 iddling 20. 71 6. 83 10.00 Tailing 58. 45 2. 60 10. 79

Composite 100. 00 14. 09 100. 8

#207 9 5 Concentrate 01. 13 14. 71 72. 45 61.96 Middling. 13. 2o 11. 27 10. 27

Talllngn 67 15. 69 27.

' Composite 100.00 14. 51 100. 00

Deslimed Head Sample. 14. 53

Tm comlitions.-Ore given acid wash using 3 lbs. msomon ore and deslimcd. Orc

regulped with fresh water. or

Conditioned at high solids with acid or caustic to give an It will be noticed that optimum results were poor that not enough concentrate was floated to secured at a pH of 8.0-test #197. With a lower pH, as in tests #209 and #213, while a good concentrate was produced the tailings undesirably increased in grade-apparently because the warrant having the products analyzed. At a. pH of 9.2 the selectivity was poor, as it was with the other two collectors in circuits as alkaline as pH 9.0.

Table #2.Eflect of varying pH on iron ore flotation using talloel-juel oil as collector A'ssay,Pcr Cent er Cent Test zg g Product Per Cent Total p wt. 1

Iron Silica mu 1. 71 No Analysis Composite 100.00

#204 8. 0 Concentrate 20. 77 60. 8. 86. 61 Middling. .5. 02 14. 79 5. i1 'lailing 74. 21 1. 62 8. 28

Composite 100. 00 14. 49 100. 00

Composite 100. 00 14. 34 100. 00

Dcslimcd Head Sample. 14. 53

as such, separately, and conditioned at high solids.

In each of above tests 2 lbs.

tallocl and 2 lbs. fuel oil per ton of dcslimcd ore usedas collector.

sodium resinate collector broke down to a resin under the acidic conditions maintained. It will be observed, on the other hand, that as the alkalinity is increased beyond pH 8.0 or 8.2-as in tests #206 and #207-the grade of concentrates drops off until at pH 9.5 the separation is reversed and more silica than iron is floated.

The beneficial efiects of using a mildly alkaline circuit are not limited'to the resinates but apply also to alkali metal soaps of talloel.

Table #2 shows the results using tallcel as a collector.

The conditions of test #204 sav optimum separation results.

It was found that alkali metal soap of talloel could be substituted for the talloel of the above experiments with comparable results.

In Table #3, following, are assembled data pertaining to the flotation oi oxidic iron from a deslimed, acid-washed and then alkalized pulp of an oxidized taconite ore material, using an aqueous emulsion of sodium resinate collector In an acid pulp the results were so 18 and fuel oil. I

Table #3 on flotation tests using oxidized Taconite, pool mine sodium resinate-fuel oil emulsion as collector Test conditions.-Sample of oxidized Taconite crushed and wet ground to 100 mesh. Deslimed. Conditioned with 3 lbs. H:S|/ton deslimed ore. Repigliped with fresh water. Conditioned at 75% solids with 0.3 lb. s mm hydroxide per ton feed and an emulsion made up of %sodium resinate, 10% fuel oil and 80% water. Amount of collector used was equivalent to 2 lbs. of resinate and 2 lbs. of fuel oil per ton of deslimed feed.

From a series of experiments I have found that best results follow holding the pH at from 8.0 to 9.0 at the point where the collector is added to the thickened pulp, the upper limit being carefully controlled to eliminate activation of the silica, while in the rougher cells the pH preferably is maintained at 7.8-8.5 and in the cleaner cells at 7.0-8.5. The data indicate that it is helpful to make the pulp nearly neutral during the cleaning step, as the silica particles then sink from the rougher froth better and a cleaner concentrate is secured.

An advantage of the present method is that by controlling the pH one can eflect an excellent separation by the use of relatively small amounts of resinates and talloel soaps, which are cheaper than sulfonates. By keeping the circuit alkaline one secures full use of the collector (resinate. or talloel soap) and requires only half as much as in an acid circuit. The flotation separation is carried on in alkaline circuit which is not corrosive to iron and steel equipment as an acid circuit would be.

I claim:

1. Process of concentrating by anionic froth floatation the oxide iron of pulps of oxidic ironbearing ores and ore-like materials including taconites containing silicious gangue, which comprises treating the pulp with a mineral acid of a strength and in an amount sufllcient to clean the sulfaces of the pulp particles, desliming the pulp, treating the deslimed acid-treated pulp at a pulp density at least equivalent to 65% solids with an alkaline-acting alkali metal compound in an amount suflicient to raise the pH of the pulp to from 8.0 to 9.0, conditioning the alkalized pulp with a reagent charge consisting essentially of an aqueous dispersion of an anionically acting agent of the group consisting of alkali metal soaps of talloel and alkali metal resinates and an oily carrier, diluting the so-conditioned pulp with water, and subjecting the diluted conditioned pulp to froth flotation.

2. Process of concentrating by. anionic froth flotation the oxidic iron of pulpsuif oxidic ironbearing ores and ore-like materials includins taconites containing silicious gangue, which comprises treating the pulp with a mineral acid of a strength and in an amount equivalent to from 1 pound to 3 pounds of concentrated sulphuric acid per ton of the pulp solids and sumcient to clean the surfaces of the pulp particles, desliming the pulp and repulping in fresh water, treating the deslimed acid-treated pulp at a pulp density at least equivalent to 65% solids with an alkaline-acting metal compound in an amount sufllcient to raise the pH of the pulp to from reagent charge consisting essentially of an aqueous emulsion of an anionically acting agent of the group consisting of alkali metal soaps of talloel and alkali metal resinates and an oily carrier, diluting the so-conditioned pulp with water, and subjecting the diluted conditioned pulp to froth flotation.

3. Process of concentrating by anionic froth flotation the oxidic iron of pulps of oxidic ironbearing ores and ore-like materials including taconites containing silicious gangue, which comprises treating the pulp with a mineral acid of a strength and in an amount sufficient to clean the surfaces of the pulp particles, desliming the pulp, treating the deslimed acid-treated pulp at a pulp density at least equivalent to solids with an alkaline-acting alkali metal compound in an amount sufficient to raise the pH of the pulp to from 8.0 to 8.5, conditioning the alkalized pulp with a reagent charge consisting essentially of an aqueous emulsion of an anionically acting alkali metal resinate and an oily carrier, diluting the so-conditioned pulp with water, and subjecting the diluted conditioned pulp to froth flotation.

4. Process of concentrating by anionic froth flotation the oxidic iron of pulps of oxidic ironbearing ores and ore-like materials including taconites containing silicious gangue, which comprises treating the pulp with a mineral acid of a strength and in an amount suificient to clean the surfaces of the pulp particles,-desliming the pulp, treating the deslimed acid-treated pulp at a pulp density at least equivalent to 65% solids with an alkaline-acting alkali metal compound in an amount sufficient to raise the pH of the pulp to from 8.0 to 8.5, conditioning the alkalized pulp with a reagent charge consisting essentially of an aqueous emulsion of an anionically acting sodium resinate and an oily carrier, diluting the so-conditioned pulp with water, and subjecting the diluted conditioned pulp to froth flotation.

5. Process of concentrating by anionic froth flotation the oxidic iron of pulps of oxidic ironbearing ores and ore-like materials including taconites containing silicious gangue, which comprises treating the pulp with a mineral acid of a strength and in an amount sufllcient to clean the surfaces of the pulp particles. desliming the pulp, treating the deslimed acid-treated pulp at a pulp density at least equivalent to 65% solids with an alkaline-acting alkali metal compound in an amount sumcient to raise the pH of the pulp to from 8.0 to 9.0, conditioning the -alkalized pulp with a reagent charge consisting essentially of an aqueous emulsion of an anionically acting sodium soap of talloel and an oily carrier, diluting the so-conditioned pulp with water, and subjecting the diluted conditioned pulp to froth flotation.

' FRED D. Dn VANEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,305,502 Booth Dec. 5, 1942 2,885,054 Booth Sept. 18, 1945 2,410,876 Booth Oct. 29, 1946 2,410,377 Booth -1 Oct. 29, 1946 OTHER REFERENCES Milling Methods 1939, published by American Institute of Mining, J Metallurgical Engineers,