US 2399845 A
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Description (OCR text may contain errors)
May 7, 1946. c. F. ALLEN Erm. 2,399,845
TREATMENT OF ORES CONTAINING CBALT AND NICKEL Filed Feb. 6, 1945 Dafa/'essen 2 F? Tail/'fly INVENTORS v CHHAM "5 F. 4 EN,
/V M. KIA/TPO,
ATTO R N EY Patented May 7,
NIKEL v charles F. Auen, Stamford, and Dan M. xenon,
Noroton, Conn., assignors to American Cyanamid-Company, New York, N. Y., a corporation of Maine vApplication February 6, 1945, Serial No. 576,450
present invention and subjected to a selective 4 Claims.
The present invention relates to the beneficiavtion of cobalt-nickel ores. More particularly, the
invention relates to an improved method of beneficlating cobalt and nickel sulilde ores by froth flotation using selective depressants for the pyrlte and/or marcasite gangue which is frequently found in intimate association therewith.
Low-grade sulfide ores of cobalt and nickel,
particularly thse containing linnaeite and the complex cobalt-nickel sulilde, siegenite, are frequently found to contain other. sulilde minerals such as chalcopyrite and galena in a gangue of pyrite, marcasite, calcite and quartz. Commonly, the nickel-cobalt content of these ores is low, often being as little as 0.5 to 2% or less, of thev nickel and cobalt sulildes. To be commercially useful as a source of the metals, a concentrate containing at least 5% of cobalt in the combined cobaltnickel product is desirable. The problem, therefore, involves two factors, the removal of gangue and the reduction of the iron content.
Beneilciation by ordinary concentrating methods dependent upon surface conditions, such as froth flotation, is extremely 4diillcult. Not only is there an intimate association lof the minerals, but the commonly-found pyrite and marcasite gangue, and the cobalt and nickel mineralsv are similarly affected by surface-conditioning reagents. In general, they exhibit similar reactions toward standard promoters, depressants, dispersants and the like. Consequently, an effective concentration of the nickel andV cobalt minerals has been diilicult, if not impractical, to obtain. Nevertheless, because these ores represent a principal proportion of the available domestic source of both nickel andcobalt, the importance of a practicable method of concentrating the cobalt-nickel content is quite apparent.
It is, therefore, the principal object of the present invention to develop a selective process of concentration by froth. notation whereby the cobalt and nickel values may be effectively separated from the pyrite and marcasite gangue. It is also an object of this invention to develop a vprocess which enables the production of a concentrate which when sintered, will be sufficiently high in cobalt-nickel and sulcientlylow in iron to be commercially acceptable.
In general, the first step in accomplishing the principal objects of the present invention is to remove a copper-lead concentrate as these mlnerals are present in appreciable amounts. The residue, or alternatively a bulk cobalt-nickel-iron concentrate obtained therefrom by flotation, is conditioned with the novel depressants of the flotation of the cobalt-nickel sulides to produce a concentrate ,richer in cobalt and nickel, and
having the iron content minimized.
Surprisingly, it has been found that the alkali ferricy-anides and/or ferrocyanides in combination witha suitable oxidizing agent act as selective depressants for pyrite and marcasite under operating conditions. The selective action of this reagent combination is most striking when it is considered that the principal gangue constituents are iron sulfide minerals which ordinarily exhibit substantially the same flotation characteristics as do the cobalt and nickel minerals, and that the materials being used as depressants include alkali-iron complexes. Further, alkali cyanides which have been commonly used as reagents in lead-copper flotation do not produce any noticeablebeneilt when used in the cobalt-nickel concentration. I i
The practice of the present invention may be readily understood by reference to the accompanying drawing which diagrammatically illustrates the steps in Aone preferred method of `carrying out the process. v
In general, the process of the present invention has the distinct advantage of being easily carried out. namely the lead-copper float, several considerations have been found to be important in connection with the desired object of keeping the cobalt-nickel minerals out of the copper-lead concentrate.. Preferably, the circuit should be alkaline. According to the present invention, a
PH of about 9 to 10 has been found'to be practically suitable, although this may be varied have been found to be perfectly acceptable. Lime. being more economical and, when used in optimum amount, apparently having some specific enable. Otherwise, the lead-copper flotation is not particularly unusual.
Excellent results have been obtained in this partici' the process using as flotation reagents either the commercially available xanthate-type promoters or those of the dithiopnosphate type such, for example, as the 4ammonium salt of dcresyl dithiophosphoric acidand the sodium salt of di-sec. butyl dithiophosphoric acid in conjunction with a suitable alkali or alkaline-earth metal.
However, in the first stage of the process,
beneilcialeffect on the minerals, is perhaps prefl sired. They may be added as required in ac- Commercial black calcium cyanide is quito satisfactory so the more expensive alkali cyanides are not necessary. Also, the addition of a small amount of calcium sulte has also been found to be helpful as an aid to selectivity in some cases.
It has been found moet practical to add these reagents during the grinding which is necessary to unlock the intimately associated variety of minerals in the ore. If, however, it is so desired, the grinding can be carried out and the reagents subsequently added 'in a separate conditioning step. Ii this is done, it is preferable that the conditioning be done at high solids but the operation may be carried out either in the flotation machine or in a separate mixer. Preferably, a part oi' the promoter is added during, grinding and the remainder conditioned with the pulp after transfer to the flotation machine. A frother is usually required during the lead-copper iiotation. The commercially available mixed cresylic acids frothers have been found to work well. Other types such as certain of the mixedl higher aliphatic alcohols, averaging about 7-8 carbon atoms, or pineoil may be used if so decordance with standard practice.
The procedure up to this point may be considered more or less as preparatory to the practice of the present invention which is found to potassium ferricyanide, sodium potassium ferricyanide and sodium or potassium ierrocyanide. The ferrocyanides are usually cheaper and if necessary considerably more of them can be used without raising the total reagent cost. They are also usually much more readily available. Therei'ore. the ferrocyanides are perhaps preferable.
A number of oxidizing agents are available for the purpose. Of those tried, the best results were obtained using alkali dichromates and/or permanganates. Either may be used if so desired. The optimum results, however, are obtained using a mixture of dichromate and permanganate with the ferroor fexricyanide. The eii'ectiveness of this depressant mixture is particularly surprising when it is considered that none of the materials when used individually produce concentrations of cobalt and nickel which are either as high in cobalt or nickel or as low in iron as can be obtained using the mixture. The invention will be more fully illustrated in commotion with the following example which is meant to be illustrative only and not by way of limitation. All parts are in pounds per ton of ore treated unless otherwise noted. In the following examples various reagents are represented by the following symbols:
A=Sodium, potassium ferricyanide B=Sodium ferrocyanide be highly critical in many respects. The flota- C=Klcno7 tion is not particularly critical as to the promoter D :mo l
used or as to the frother used. Commercial Example 1' xanthate promoters and higher aliphatic alcohol frothers were used in the development work A sample 0f 1W grade cobaltmkel Ore assay' ing about 0.6% Co and 0.8% Ni, was ground for but these may be replaced by equivalent reagents of similar properties when so desired.
The critical procedure is in the use of the selective depressant mixture which enables the production of good cobalt-nickel concentrates which are suiilciently low in iron to be commercially acceptable. As shown in the drawing, the tailings from the copper-lead rougher flotation circuit are conditioned with the chosen cobaltnickel promoter and then subjected to flotation flotation step in the notation cell for the production of a bulk cobalt-nickel-iron sulfide concentrate. A gangue tailing is obtained which may be discarded. The bulk rougher concentrate, or a cleaned concentrate if a cleaner stage is used, is then conditioned with the depressants and subjected to a selective cobalt-nickel notation which yields the desired 4concentrate. Either the bulk rougher or the 'selective cobalt-nickel flotation may be carried out in stages or in single operations in accordance with standard practice.l
So far as the depressant mixture is concerned, it is found that two constituents are required, the rst .being a suitable alkali ferroor ferricyanide and the second a suitable oxidizing 60 agent. A number of available alkali ferroand in the presence of'a frother added during the fteen minutes at about solids with a mixture of 1.0 part lime, 0.5 part calcium sulfite. 0.25 part commercial calcium cyanide and 0.04 part of a promoter comprising anammonia neutralized mixture of thiocarbanilid and dicresyli dithiophosphoric acid. After reduction to about 22% solids and conditioning for about one minute with 0.1 part of additional promoter, the pulp was floated for about four minutes to produce a vrougher Cu-Pb concentrate. This concentrate was given a three minute float with 0.03 part of an alcoholic type frother to produce thecleaner Cu-Pb concentrate. I
' Example 2 A sample ot tailings produced according to Example 1 was then broken up into-a series of test samples which were successively treated to a two minute conditioning at ilotation density with 0.1 part of axanthate promoter and floated for iive minutes with 0.03 part of an alcoholic frother. Thel resulting bulk concentrate from this treatment 'was then conditioned for about flve minutes with the iron minerals depressant being tested and floated for about two minutes to produce the final Co-Ni-concentrate. Illustrative depressants used and their metallurgical results ferricyanides are lavailable such as sodium or are shown in the following table:
Iron deptslsnt Assays-concentrate Rm; Tw m Percent Percent Percent l A 0 D l oo Ni Fo (72o lNi le v1.0 5.55 7.54 81.25 5&W, 59.@ 30.78
0.5 0.1 '5.1) 11.50 M ll '56.38 55.41 14.58
assaut We claim:
1. In concentrating suiiide minerals oi.' cobalt and nickel by i'roth flotation from an ore in which they are intimately associated with iron sulnde minerals, the improvement which comprises conditioning a pulp containing the cobaltfnickel sulides with a selective collector for the cobalt and nickel minerals and with a selective depressant mixture for the iron sulfide minerals, said depressant mixture comprising at least one compound selected from the group consisting of the alkali terricyanides and the alkali ierrocyanides and at least one oxidizing agent selected from the group consisting of the alkali permanganates and dichromates, vsubjecting the conditioned pulp t0 forth notation and collecting the resultant froth concentrate.
2. A process according to claim 1 in which the selective depressant mixture comprises at least one compound selected from the group consisting of the alkali feiricyanides and the alkali ferrocyanides together with an alkali permanganate.
3. A process according to claim 1 in which the selective depressant mixture comprises atleast one compound selected from the group consisting