US1364858A - Flotation of minerals - Google Patents

Description

UNITED STATES PATENT OFFICE.

CLEMENT L. PERKINS, 0F PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO METALS RECOVERY COMPANY, OF NEW YORK, N. Y., A CORPORATION OF MAINE.

FLOTATION OF MINERALS.

No Drawing.

To all whom it may concern:

Be it known that I, CLEMENT L. PERKINS, a citizen of the United States, residing at Pittsburgh, in the county of Allegheny, State of Pennsylvania, have invented certain new and useful Improvements in Flotation of Minerals; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to the concentration of'minerals, such as sulfid ores and the like, by flotation, and is based upon the discovery that improved results can be obtained by carrying out the flotation operation with the addition, to the ore or mineral pulp, of certain non-oleaginous solid or ganic compounds, which themselves have substantially no frothing properties, but which have valuable properties as selective or col.- lecting or mineral-modifyin agents for the mineral. Such agents, although substantially non-frothing, nevertheless so act upon the minerals that they very .materially assist in the recovery of the minerals when used in connection with a suitable frothing agent.

Among the agents which are of particular value as selective or collecting or mineralmodifying agents, and which are substantially non-frothing, are reduced compounds which are relatively easily oxidizable such as, for example, diazo-amino-benzene. It

may be that these compounds are adsorbed at the surface of the sulfid or mineral particles, and that they so modify the sulfid or mineral surfaces that these surfaces are less easily wet by water or made more readily susceptible to attachment by the air bubbles. In some cases the reduced compound is apparently further reduced by the action of the sulfid particles, so that the action may partake of both a chemical and physical nature. These agents also appear to be adsorbed to some extent by certain of the gangue particles, but in this case oxidation of the collecting agent apparently takes place at the surface of the gangue particles, so that the actual surface presented is an oxidizing or oxidized'surface, while in the case of the sulfid particles it appears to be a reduced surface. However, I do not desire to limit myself by any theoretical explana- Specification of Letters'Iatent.

Application filed July 13, 1920.

Patented Jan. 4, 1921.

Serial No. 395,997.

tion of the mechanism of the action of these collecting agents.

Although the collecting agents are substantially insoluble, and are commonly referred to as insoluble, nevertheless, they are soluble to a very small de ree, and it appears to be by reason of thls solubility that they are able to act upon the minerals and exert their marked selective and collecting properties.

These collecting agents are, as above noted, non-frothing, and it is, therefore, important to supplement their actionby an agent\ which will provide an appropriate amount of froth. The frothing agent, however, may be entirely inadequate to perform the flotation process by itself, inasmuch as its function appears to be simply to provide bubbles in suflicient quantity and of sulficient persistency to overflow into the launder of the flotation machine, thereby mechanically facilitating the removal of the mineral concentrate.

Among the collecting agents of the character above referred to, that is, which are substantially nonfrothing, are included certain of the aromatic thio-ureas, and many of the azo and diazo compounds. A collecting agent which I have found of particular value is diazo amino -benzene, C,H,:N:NNHC H The process in which such collecting or mineral-modifying agents are used is described and broadly claimed in my prior application Serial No. 312,247, filed July 21, 1919, while the more specific claims of said prior application relateto the process in which the selective or collecting agent, and

the frothing agent, are added in admixture, the one dissolved in the other. The claims of the present application relate to the two-step procedure in which the selective or collecting agent is first intimately incorporated with the mineral pulp, and the frothing agent subsequently added.

The collecting agent or agents can thus be incorporated with the ore or mineral pulp .1n any suitable manner which will lnsure their uniform incorporation and dissemination throughout the pulp. They may thus be incorporated with advantage by grinding in the tube mill or ball mill in which the ore itself is ground, and this is particularly advantageous. The action of such agent appears to be a selective modifying action upon the mineral surfaces rather than any action of importance upon the water itself, inasmuch as investigations indicate that the removal of the water from the ore pulp, after the collecting agent has been incorporated therewith, and the subsequent washing of the ore, does not deprive it of its improved flotation properties, and it can be again made into an ore pulp with fresh water and subjected to flotation. Investigations of this kind indicate that the collecting agents have a selective modifying effect upon the mineral surfaces and that any modifying effect upon the water is incidental.

After the collecting agent or mineralmodifying agent has been incorporated with the ore pulp, a suitable frothing agent is then added and intimately incorporated. The frothing agent may be added at any time subsequent to the incorporation of the collecting agent. It may thus be added in the launder leading to the flotation cell, or even in the cell itself.

The flotation operation can be carried out in the common forms of flotation apparatus, such as an ordinary Callow cell, or apparatus where the air is incorporated in the ore pulp by mechanical agitation.

It is of advantage in many cases to add to the ore pulp a small amount of alkali,-

which may be suflicient in amount to give to the ore pulp a distinct alkaline reaction, When alkalis are used, it is desirable to give them an appreciable time of contact with the ore pulp before subjecting the latter to flotation. When possible, it appears preferable to add the alkalis in the grinding mill, so that they will be present during the grind ing operation. The alkali may be caustic alkali, such as sodium hydrate, or an alkaline salt, such as sodium carbonate, or even lime or calcium oxid or hydrate can be used.

The amount of the collecting agent added may vary somewhat, and may be as little as one-fifth or one-fourth of a pound per ton of ore, (that is, calculated on the weight of the ore and not of the ore pulp). I have obtained good results with the use of as little as one-thirtieth of a pound per ton of ore. Larger amounts may, however, be used.

The invention will be further illustrated by the following specific examples of tests made upon a copper sulfid ore having a silicious gangue containing its flotable or sulfid copper in the form of a mixture of chalcocite and chalcopyrite, that is, socalled porphyry ores, such as those of the Utah (aopper Company. In general, treatment of the ore with alkalis, as above noted, gives improved results, the alkalis themselves apparently having a valuable effect upon the ores in improving the flotation thereof.

1. Dz'azo-amino-benaeae and terpineol.

500 parts by weight of Utah Copper Companys ore was ground in the pebble mill with 250 parts of water, sodium hydroxid equivalent to two pounds per ton of dry ore, and diazo-amino-benzene equivalent to onefifth pound per ton. The ground pulp was 7 2. Dz'aeo-amino-Lenzenc and terpineol.

The details of the test were thesame as those of No. 1, except that the proportion of diazo-amino-benzene was reduced to onethirtieth pound :per ton. The heads for test No. 2 contained1.38 per cent. copper, the concentrate produced contained about 17.3 per cent. copper, and the recovery was about 87.7 per cent.

3. Diazamninmbeneenc and pine oil.

The details of this test were the same as those of No. 1, except that steam-distilled pine oil was substituted for terpineol. The proportion of pine oil used was about onefourth pound per ton of dry ore. The heads for test No. 3 contained 1.39 per cent. copper, the concentrates produced contained about 17.9 per cent. copper, and the recovery was about 88.6 per cent.

The collecting agent can with advantage be used in addition to many of the usual oil mixtures which are commonly employed in flotation, with resulting improvements in the flotation operation. Flotation oils or oil mixtures which are good frothing agents, such as pine oil and other wood distillation oils, are of particular value, inasmuch as they supplement the action of the collecting agent, and are themselves supplemented in their ore floating properties by the collecting action ofthe collecting agent.

In the flotation of zinc-lead ores, it has been found of advantage to grind the collecting agent with the neutral ore pulp; and still better results have been obtained when copper sulfate and sulfuric acid were also used in the proportion of about one pound of each per ton of dry ore. A small amount of a suitable frothing agent, as above noted, should also be used.

It is characteristic of the invention that the froth obtained is readily broken up, while a relatively clean concentrate and high recovery can, nevertheless, be obtained. A part of the collecting agent, together with a part of the frothing agent, can sometimes be recovered so that they are available for use in the treatment of further amounts of ore; for example, by recovering the circuit water from the concentrates, or even that from the tailings, and returning the same to the process, with resulting economy in the amount to be added for subsequent operations. The amount of the collecting agent can, however, in many cases be reduced to such a small amount that it is feasible to practise the invention Without such recovery of the agents employed.

The addition of the flotation agents successively has the advantage that the grinding of the ore pulp and the preliminary incorporation of'the substantially non-frothing collecting agent can be effected withoutany objectionable froth formation, and the ore pulp can thusbe kept free from objectionable froth formation until the frothing tion of minerals by flotation, which com-' prises grinding the ore with the addition thereto of a small amount of a substantially non-frothing, non-oleaginous organic mineral collecting agent, subsequently adding a small amount of an agent having good frothing qualities, and subjecting the resulting mixture to a flotation operation; substantially as described.

3. The method of effecting the concentration of copper ores by flotation, which comprises intimately incorporating with the ore pulp a small amount of alkali and a small amount of a substantially non-frothing, nonoleaginous organic mineral collecting agent, subsequently adding an agent having good frothing qualities, and subjecting the resulting mixture to a flotation operation; substantially as described.

4:. The method of effecting the concentration of copper ores by flotation, which comprises grinding the ore in admixture with a small amount of alkali and a small amount of a substantially non-frothing, non-oleaginous organic mineral collecting agent, subsequently adding a small amount of an agent having good frothing properties, and subjecting the resulting mixture to a flotation operation; substantially as described.

The method of effecting the concentration of minerals by flotation, which comprises adding to the mineral pulp a small amount of diazoaminobenzene, subsequently adding an agent having good frothing properties, and subjecting the resulting mixture to a flotation operation; substantially as' described.

6. The method of effecting the concentration of minerals by flotation, which comprises grinding the ore with the addition thereto of a small amount of diazoaminobenzene, subsequently adding a small amount of an a ent having good frothing qualities, and su jecting the resulting mixture to a flotation operation; substantially as described.

7. The method of effecting the concentration of copper ores by flotation, which comprises intimately incorporating with the ore pulp a small amount of alkali and a small amount of. diazoaminobenzene, subsequently adding an agent having good frothing qualities, and subjecting the resulting mixture to a flotation operation; substantially as described.

8. The method of effecting the concentration of copper ores by flotation, which com prises grinding the ore in admixture with a small amount of alkali anda small amount of diazoaminobenzene, subsequently adding a small amount of an agent having good frothing properties, and subjecting the resulting mixture to a flotation operation; sub- 95 stantially as described.

In testimony whereof I afiix my si nature.

CLEMENT L. PERI INS.