US2410021A - Flotation process - Google Patents

Description

Patented Oct. 29, 1946 FLO'IATION PROCESS Fred D. De Vaney, Hibbing, Minn, assignor to Erie Mining Company, Hibbing, Minn., a corporation of Mlnnesot No Drawing. Application April 26, 1944, Serial No. 532,867

Claims.

This invention relates to specific improvements in the froth flotative beneficiation of silicious iron ores, and is specifically concerned with a mode of accelerating the rate of flotative separation of silicious gangue from such ores using higher molecular weight aliphatic amine compounds as cationic collectors.

It heretofore has been suggested that silicious iron ores might be beneficiated by froth-floating the silicious gangue particles from the iron mineral particles of a pulp of the ore by the use of a higher molecular weight aliphatic amine compound, having from 10 to 18 carbon atoms in the aliphatic radical, as collector in conjunction with a suitable frother. According to the suggested technique the pulp circuit was to be maintained distinctly alkaline; preferably, also, the flotation was to be effected in the presence of a selectivityimproving agent such as acid-treated starch.

the ore pulp a relatively small amount of an alkali metal sulfide (specifically, sodium sulfide), the rate of flotation of the silicious gangue particles can be very materially increased, with no decrease in the selectivity and with a small but appreciable saving in the amount of amine collector required. As equivalent of sodium sulfide there may be used potassium sulfide or calcium sulfide or barium sulfide or a polysulfide of sodium, potassium, calcium or barium.

It has been found that the alkali ,metal or alkaline earth metal sulfide or polysulfide functions most effectively when the pulp circuit is maintained acid (i. e., less than pH 7) rather than alkaline.

The influence of progressive additions of sodium sulfide, while maintaining a constant pH, may be seen from the data of the following table:

TABLE 1 Effect of sodium sulfide on amine flotation oi Mesabi washing plant tailings t r nt. Assay}, P t so um percen ercen sulfide, Product total g g lbs/ton iron n Iron Silica Silicious froth. 82. 41 8. 95 41. 01 Concentrate.--.- 17. 59 60. 24 8.15 58. 99 min 25 sec.

Total. 100.00 17. 97 100. 00 Silicious froth. 82. 86 8 85 41. 36 o 2 Concentrate... 17. i4 60. 61 8.02 58. 64 min Total... 100.00 17. 72 100. 00 Silicious froth. 82. 48 8. 63 39. 92 Concentrate".-. 17.52 61. 21 7.17 60.08 3 min" 25 sec Total. 100.00 i7. 84 100.00 Silicious froth.-. 83. 06 9. 61 44. 42 m8 Concentrate..- 10. 34 61. 54 6. 55. 58 3 min,

Total. 100. 00 18. 10 100. 00 Silicious froth. 84. 50 9. 98 47. 54 Concentrate... 15. 50 59. 75 9 34 52. 46 2 mm" 35 Total. 100. 00 17. mo. 00

Norm-In each test 500 gm. of washing plant tailing were treated without additional crushing and without desliming in a 500 gram Denver Sub A flotation cell. The pulp in each case was maintained at an acidity of pH 5.2. The flotation reagents used in each test were Identical and consisted of 0.4 lbJton of AM Coco," i. e., a canonically-acting collector consisting of the hydrochlorides. acetates or other watersoluble forms of mixed primary aliphatic amines corres nding in aliphatic chain length to fatty acids of coconut oil, made by Armour & ompan and .104 lb./ton of methyl amyl alcohol which were added in small increments. hen sodium sulfide was used this reagent was conditioned with the pulp for 5 minutes prior to flotation.

It has now been found that if with the usual higher molecular weight aliphatic amine collector aforesaid and suitable frother there be added to The infiuence of varying the acidity of the pulp circuit, while maintaining constant the amount of sodium sulfide (and all other variables) at arbitrary levels, may be seen from the data of the following table:

' TABLE 2 increased rate of flotation means that a flotation Efl'ect of varying pH of pulp on amine flotation of Mesabi washing plant tailinas Assay percent pH of PM at Percent f'ggf Total flotation pulp wt. time Iron Silica Siliclcus froth 80. 90 7. 99 B6. 64 a o Concentrate... 19. 10 58. 72 9. 79 63. 46 3 mm. a) m.

Total. 100.00 17.68 100.00 silicious froth. 79. 8. 00 35. 39 v 7.1 Concentrate- 20. 34 5?. 16 12. 63 64. 61 5 mm.

Total. 100. 00 18. 00 100. 00 silicious froth- 7a 73 7. 61 33. 28 a Concentrate"-.. 21. 27 65. 69 14. 61 06. 72 5 mm" 45 m.

I Total- 100. 00 17. 76 100. 00

Test conditions same as given in Table 1, except 0.5# fused sodium sulfide used in all tests and alkalinity and acidity controlled by addition of either sulphuric acid or sodium carbonate.

By using in the pulp circuit both the sulfide and the acid-treated starch it is possible to maintain the high selectivity attributable to the use of the starch material while simultaneously achieving the high rate of feed made possible by use of the sulfide.

EXAMPLE The starting material was a washing plant tailing from the Danube mine, Minnesota, analyzing 16.66% Fe, mostly as hematite. The silicious gangue was mostly quartz. The material as obtained was essentially of a size through 48 mesh and was not further subdivided.

The starting material, without having been subjected to a desliming treatment, and in the form of an aqueous pulp of approximately solids, was added to a mechanically agitated flotation cell, and to it were added 0.5 lb./ton of acid-treated starch, /4 lb./ton of sulfuric acid monohydrate, and 0.8 lb.-/ton of sodiumlsulflde in the form of 60% fused flake. Afterthorough mixing of these ingredients with the pulp and conditioning for 3 minutes, froth flotation was induced by the addition of 0.25 lb./ton of 9AM (.looo collector and 0.05 lb./ton of B-23" frother, both of which agents were added, in small inmany flotation cells to handle the same tonnage alkali metal or alkaline earth metal sulfide or crements, during the agitation and aeration of Per cent Per cent Per cent Per cent Pmdm wt. Fe SlOl total iron silicious froth (tailing)--- 60. 24 5. 71 20. 2d lrotli (middling) 23. 62 13. 86 10. 63 Concentrate l6. 14 61. 66 7. 45 59. 72

It is to be noted that the time required for the over-all flotation (both roughing and cleaning) was 3 minutes and 15 seconds, whereas in the absence of the sodium sulfide the normal flotation time is from 5 to 6 minutes. This greatly polysulfide is used appears to be due to a selective fiocculating effect of the sulfide or polysulfide on the gangue particles. Whatever may be the correct explanation, it is an observable fact that, with use of the sulfide or polysulfide, flocculation of the gangue particles does take place, and this flocculation of the ga'ngue is definitely a very desirable condition for rapid flotation.

I have found that non-alkali inorganic sulfides such as ammonium sulfide and hydrogen sulfide not only do not serve to accelerate the rate of separating but positively are harmful in the flotation. A number of experiments with organic I compounds of sulfur, e. g., petroleum sulfonates,

sulfonic acids and a number of xanthates, have established that such compounds are not helpful for accelerating the rate of flotation.

It is tobe noted, in this connection, that the function of the alkali metal or alkaline earth metal sulfide or polysulfide is not that of a sulfidizing agent toward the mineral to befloated,

as obtains in the flotation of base metal ores,-e. g.,

oxidized copper and lead ores. where a sulfide actually forms a base metal sulfide "sheath or surface layer on the mineral particle. In the present process, no chemical combination between the silica and the sulfide or polysulfide of sodium, potassium, calcium or barium has been observed.

I claim: a

1. In the process of beneflciating silicious iron ore by cationically froth-floating the silicious gangue particles from the iron mineral particles of an aqueous pulp of such an ore by the use of a higher molecular weight aliphatic amine collector and a frother, the step of accelerating the rate of flotation of the silicious gangue particles which consists in incorporating a relatively very small amount of sodium .sulfide into the pulp prior to the froth flotation step.

2. In the process of benefic'iating silicious iron ore by cationically froth-floating the silicious gangue particles from the iron mineral particles of an aqueous pulp of such an ore by the use of a higher molecular weight aliphatic amine collector and a frother, the step of accelerating the rate of flotation of the silicious gangue particles improving agent, steps of accelerating the rate of flotation of the silicious gangue particles which consists in maintaining the pulp containing the aforesaid agents at a pH of less than 7 but not less than about 5 and incorporating into the acidic pulp, prior to the froth flotation step, a relatively very small amount of sodium sulfide.

4. In the process of beneficiating silicious iron are by cationically froth-floating the silicious gangue particles from the iron mineral particles of an aqueous pulp of such an ore by the use of a higher molecular weight aliphatic amine collector and a frother, the step of accelerating the rate of flotation of the silicious gangue particles which consists in incorporating a relatively very small amount of an alkali metal sulfide into the pulp prior to the froth flotation step.

5. In the process of beneficiating silicious iron ore by cationically froth-floating the silicious gangue Particles from the iron mineral particles of an aqueous pulp of such an ore by the use of a higher molecular weight aliphatic amine collector and a i'rother, the step of accelerating the rate of flotation of the silicious gangue particles which consists in incorporating a relatively very small amount of an alkali metal polysulfide into the pulp prior to the froth flotation step.

6'. In the process of beneficiating silicious iron ore by cationically: froth-floating the silicious '1. In the process of beneflciating silicious iron ore by cationically froth-floating the silicious gangue particles from the iron mineral particles of an aqueous pulp of such an ore by the use of a higher molecular weight aliphatic amine collector and 01' a frother, in a slightly acidic circuit, the step of selectively fiocculating the silicious -gangue particles which consists in incorporating into the pulp, prior to the flotation operation, a relatively small amount of a compound of the group consisting of the alkali metal sulfides, the alkaline earth metal sulfides, the alkali metal polysulfides and the alkaline earth metal polysulfldes.

8. The process of beneficiating a silicious oxidic iron ore, which comprises adding to an aqueous pulp of the ore a mineral acid in an amount sufllcient to give the pulp a pH of about 6.0, conditioning the pulp with from about 0.4 lb. to about 1.6 lbs/ton of a compound of the group consisting of alkali metal sulfides, alkaline earth metal sulfides, alkali metal polysulfldes and alkaline earth metal polysulfldes, and subjecting the acidified and conditioned pulp to froth flotation in the presence of a frother and of a higher molecular weight aliphatic amine collector, thereby rapidly raising a froth product rich in silicious gangue particles.

9. The process of beneflciating a silicious oxidic iron ore, which comprises adding to an aqueous pulp of the ore a mineral acid in an amount sufllcient to give the pulp a pH of about 6.0, conditioning the pulp with acid-treated starch and from about 0.4 lb. to about 1.6 lbs/ton of a compound of the group consisting of alkali metal sulfides, alkaline earth metal sulfides, alkali metal polysulfides and alkaline earth metal polysulfldes, and subjecting the acidified and conditioned pulp to froth flotation in the presence of a frother and of a higher molecular weight aliphatic amine collector, thereby rapidly raising a froth product rich in silicious gangue particles while depressing fine oxidic iron particles into the underflow product.

gangue particles "from the iron mineral particles of an aqueous pulp of such an ore by the'use of a higher molecular weight aliphatic amine col-:'

lector and 'a-frother, the stepof'accelerat'ing the rate of flotation of thelsilicious gangue particles which consists in incorporating a relatively very small amount of a compound of the group conslsting of the alkali metal sulfides, the alkaline earth metal sulfides, the alkali metal polysulfldes and the alkaline earth metal-polysulfides into the oulp prior to the froth flotation.

10. The process of 'beneflciating a silicious oxidic iron ore, which comprises adding to an aqueous pulp of the ore a mineral acid in anamount sufficient to give the pulp a pH of about 16.0, conditioning the pulp with from about 0.4 lb.

to about '1.6 lbs/ton of sodium sulfide, and subjecting the acidified and conditioned pulp to froth flotation in the presence of a frother and of a primary alkylamine having from 10 to 18 carbon atoms in the alkyl radical as collector, thereby rapidly raising a froth product rich in silicious gangue particles.

FRED D. DE VANEY.