DE2323130A1 - INTERPRETATION OF SULPHIDE CONCENTRATES - Google Patents

Description

23 812 n / wa

The International Nickel Company of Canada Ltd.
Copper Cliff / Ont., Canada

Leaching of sulphide concentrates

The present invention relates to a hydrometallurgical process and, more particularly, to an improved process for the recovery of non-ferrous metal values
Sulphide minerals by oxidation of an aqueous slurry of the sulphide mineral.

3Q98S1 / 1Q4?

As a general rule, the use of high temperatures will increase the kinetics of the leaching reaction and more commercially attractive leaching rates will be obtained. However, if the sulfide minerals are oxidized in an aqueous solution at temperatures above about 112 ° C, the melting point of sulfur, under conditions in which molten, elemental sulfur is formed, the further reaction is "cut off" by the released molten elemental sulfur "that the unreacted sulfides are wetted and coated. The sulfur-coated unreacted sulfides then stop reacting unless the sulfur coating is removed in some way. For example, it has been suggested to use vigorous agitation during leaching in order to destroy the sulfur coating on the unreacted sulfide surfaces. In order to completely avoid the disadvantages associated with a coating consisting of molten sulfur, it has also been proposed to leach out the sulfide minerals at temperatures below the melting point of sulfur. However, this is not a completely satisfactory solution because at temperatures below about 112 C there are some important things. " Senmineralulfide react only slowly and others do not react at all. Chalcopyrite is a good example of a sulfide mineral which is so unreactive that it cannot be leached ^{at industrially acceptable rates using conventional alkalis at temperatures below about 112 ° C. without prior thermal treatment.} For example, attempts have been made to process concentrates containing chalcopyrite and greater than about 10 % pyrrotine at temperatures

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to be treated above 112 ° C, with the oxidative dissolution the copper values associated with chalcopyrite are initially carried out at economically favorable speeds, however, when elemental sulfur is generated, it forms molten elemental sulfur coatings and "cuts off" the oxidation reactions.

It has now been found that sulphide minerals of light ferrous metal values in acidic aqueous solutions at temperatures above the melting point of sulfur can be oxidized while minimizing the coating effect of the released elemental sulfur.

Generally speaking, the invention provides an improved method of treating at least one mineral sulfide in a? aqueous) suspension at temperatures above the melting point of sulfur for oxidation at least of a part of the sulphidic sulfur is considered to be elemental sulfur. The improvement includes the addition of a surfactant to the aqueous suspension in small but effective amounts to minimize wetting and coating of the sulphide mineral by molten elemental sulfur, see above that the oxidation of the sulphide sulfur can continue.

An advantageous embodiment of the invention consists in the treatment of a sulfide mineral of at least one light-ferrous metal value, which is among cobalt, copper, lead, nickel and zinc is selected from sulfide minerals, with acidic aqueous solutions under oxidative conditions at temperatures above the melting point of sulfur in order to set elemental sulfur free and the non-ferrous

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dissolve metal values. A slurry of a finely divided sulfide mineral of non-ferrous metal value and an acidic aqueous solution containing a surface active reagent in a small but effective amount to minimize wetting and coating of the sulphide mineral by molten sulfur to a temperature above the melting point of sulfur for the oxidation of at least part of the sulphide sulfur heated to elemental sulfur and to dissolve the non-ferrous metal value.

Ores, ore concentrates, leachate or other metallurgical intermediates that contain at least one metal which is selected from the class consisting of cobalt, copper, iron, lead, nickel and zinc be treated by the method according to the invention. For economic reasons it is advantageous if that Ore or the ore concentrate contains at least one non-ferrous metal value derived from cobalt, copper, lead, Nickel or zinc existing group is selected. Examples of these sulfide minerals include, albeit the Invention is not limited to chalcopyrite, pentlandite, chalcocite, sphalerite, cubanite, galena, pyrrhotite, Violarite, Covellin, Digenite, Millerite, Bornite, Cobalt luster, Polydymite and iron monosulphide, which is produced by heating iron pyrite generated in non-oxidizing atmospheres to remove the unstable substances.

It is not necessary that the ore, the ore concentrate or the metallurgical intermediate in any way other than preliminary crushing or grinding is pretreated to increase the surface area of the material to facilitate the leaching reaction. In

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In most cases, milling to 100 % less than 149 microns (100 % minus 100 mesh Tyler Screen Size 1 ~ TSSJ7) is beneficial in obtaining economically favorable leach rates. It is even more beneficial to mill the ore, ore concentrate, or other metallurgical intermediates to at least 90 % less than 44 microns (minus 325 mesh TSS) to obtain commercially favorable reaction rates and minimize material handling difficulties. The best results in terms of non-ferrous metal value dissolution, sulfide-sulfur conversion, reaction rates, and apparatus application are obtained when the ore or ore concentrate is milled to a particle size of about 100 % less than 44 microns.

After crushing or grinding, if necessary, the ore, ore concentrate or other metallurgical intermediate product is mixed with water or an acidic aqueous alkali solution. A wide range of pulp densities, for example from about 2 wt % solids to about 50 wt% solids, can be used. However, it is preferred to employ pulp densities between about 5 wt % and 50 wt% solids to minimize material handling inconveniences and to make effective use of the process equipment and to produce more concentrated solutions of nonferrous metals.

Any leaching process can be used which removes the sulfide sulfur found in the non-ferrous metal sulfide minerals occurs, oxidizes to elemental sulfur and dissolves the non-ferrous metal value. For example, can Solutions of at least one iron (III) salt, which from the selected from the group consisting of sulfate, chloride and nitrate

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is to oxidize the sulphide sulfur of spruce-iron metal sulphide minerals to elemental sulfur with dissolution of the non-ferrous metal value, whereby the used lye solutions are regenerated by known chemical or electrolytic processes. Of course, other polyvalent metal salts such as chromium and manganese salts can also be used. In In another embodiment, the sulfide mineral can be used to dissolve the metal value and to oxidize the sulfide Sulfur can be oxidized to elemental sulfur by passing gaseous chlorine through an aqueous slurry of the sulfide mineral conducts. The leaching is particularly advantageously carried out by an aqueous Slurry of the sulfide mineral is oxidized with a free oxygen-containing gas.

In an advantageous embodiment of the process, an aqueous slurry of the finely divided sulfide mineral is introduced into an autoclave made of a suitable acid-resistant material and equipped with agitators for the slurry . The slurry is heated to a temperature above about 112 ° C. under a partial pressure of oxygen of at least about 3 atmospheres to oxidize the sulfide sulfur to elemental sulfur and dissolve the metal value. Advantageously, the slurry to a temperature between about 120 ⁰ C and 250 ° C is heated under an oxygen partial pressure between about 10 atmospheres and 30 atmospheres. At temperatures between about 120 ^° C. and 170 ^° C. and under partial pressures of oxygen between about 10 atmospheres and 30 atmospheres, the oxidation reaction takes place at industrially desirable rates without the need for undesired heavy equipment. At temperatures that are considerably above L90 ° C

309851/1047

elemental sulfur is not produced, the sulphide sulfur is oxidized to sulphate sulfur, which when recovered the dissolved metal values must be neutralized from the solution.

The elemental sulfur released is ^{melted at temperatures above 112 °} C. and tends to wet and coat the sulfide minerals. As more and more elemental sulfur is released, the wetting and coating effects of the molten sulfur and the oxidation reaction compete. When sufficient molten elemental sulfur has been released to wet and coat the sulphide minerals, the oxidation reactions are stopped. In order to avoid the termination of the oxidation reactions, a surfactant reagent in a small but effective amount is added to the aqueous slurry to moderate the wetting and coating reaction of the sulphide minerals by molten elemental sulfur. Although the invention is not limited thereto, it is believed that the surfactant reagents act to retard the wetting of the unreacted sulfide minerals by the molten sulfur. Desirably, the surfactants are water-miscible organic compounds that are liquid at the leach temperatures. An exemplary list of the surface-active reagents which can be used includes, although the invention is not limited thereto, mixtures of water-soluble aliphatic amines, polyalkylene glycol esters, polyoxyethylene lauryl ethers and sulfonated aromatic substances.

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The surfactant reagent is added to the aqueous slurry of the sulfide mineral in a small but effective amount added to ensure that the leaching liquid removes the molten sulfur on the mineral sulfide surface will replace. Although the sulfide mineral itself, the ore or the ore concentrate and the extent the grinding affect the amount of surface-active reagent used, the surface-active reagent Stock generally of the slurry in amounts between about 0.23 kg / t "(0.5 lb / t) of the sulfide mineral slurry and 4.54 kg / t of the sulphide mineral added. Advantageously The surfactant will be present in amounts between about 0.45 kg / t (1 lb / t) solids in the sludge and 2.27 kg / t (5 lbs / t) of pesticides in the sludge Maximize the effects of the surfactant while minimizing its consumption.

In an advantageous embodiment of the invention, a sulfidic ore or ore concentrate, which pyrrhotite and at least one sulfide mineral of a low-grade iron metal value, are used. which is selected from the class consisting of nickel or copper, contained, treated by aqueous oxidation at temperatures above the melting point of sulfur to obtain the elemental sulfur, easily separable iron oxide and a mother liquor in which a predominant part of the non-ferrous metal value is dissolved. The sulphide minerals of nickel include pentlandite, violarite, and mi11erite, while the copper minerals chalcocite, covelline, digigenite, chalcopyrite * cubanite and bornite, all of which occur with pyrrhotite. The ore or ore concentrate is mixed with water to produce advantageously a slurry or sludge containing between about 5 wt.% And 30 wt.% Solids,

309851/1047

taking a surface active reagent in a small however, an amount effective to minimize wetting and coating of the pyrrhotite and non-ferrous metal sulfide value is added to the pulp by molten elemental sulfur. The surfactant preferably represents at least one element selected from mixtures of water-soluble aliphatic amines, Polyalkylene glycol esters, polyoxyethylene lauryl ethers and sulfonated aromatic substances and the pulp - advantageously in amounts between about 0.45 kg / t (1 lb / t) sulphide mineral and 2.27 kg / t (5 lbs / t) sulphide mineral is added. The slurry is placed in an autoclave and transferred to a Temperature between about 12p C and 160 ° C under an oxygen partial pressure of at least about j5 atmospheres, advantageously between about 10 atmospheres and 30 atmospheres Atmospheres for the oxidation of at least part of the sulphidic sulfur to elemental sulfur and to Dissolution of the non-ferrous metal value heated. While The oxidation treatment is used to promote the oxidation reactions and to ensure that the pulp is used freshly exposed sulfide surfaces are brought into contact with the surface-active agent, stirred vigorously. if the oxidation reactions have essentially ended, the slurry is subjected to controlled agitation to produce solidified Chilled sulfur pelettos. The sulfur pellets and the iron oxide can come from the mother liquor and from each other separated, while the dissolved nickel and copper values can be obtained from the mother liquor.

An advantageous embodiment of the invention in treatment an ore or ore concentrate, which pyrrhotite, pentlandite urü

309851/1047 - 10 -

Chalcopyrite contains, is that the aqueous oxidation to oxidize substantially all of the sulfide sulfur that occurs with the pyrrhotite and pentlandite and only minor amounts of the sulfide sulfur that occurs with the chabopyrite to produce a. Performs sludge of elemental sulfur, iron oxide and unreacted Chalcopyri.t in a mother liquor containing nickel. After the liquid-pesticide separation, the elemental sulfur and chalcopyrite can be separated from the iron oxide and then from each other so that the chalcopyri can be treated to recover the copper. The mother liquor containing nickel can be treated to selectively precipitate any dissolved copper and then to recover nickel. In practicing this embodiment, an ore or ore concentrate which contains pyrrhotite, pentlandite and chalcopyrite and is advantageously ground to a particle size of at least about 100 % less than 44 microns (100 % minus 325 mesh TSS) is mixed with water, For example, to produce a slurry containing between about 5 wt.% and 30 wt. % pesticides. A surfactant reagent is added to the slurry in small but effective amounts to minimize wetting and coating of the pyrrhotite and pentlandite by molten elemental sulfur to ensure that substantially all of the sulfide sulfur of the pyrrhotite and pentlandite is oxidized. For example, at least one surface-active agent consisting of mixtures of water-soluble aliphatic amines, polyalkylene glycol esters, polyoxyethylene lauryl ether and sulfonated

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existing class of aromatic substances is selected, added to the slurry in amounts between approximately 0.45 kg / t ore and 2.27 kg / t ore. The slurry is introduced into an autoclave, to a temperature between about 120 ⁰ C and l60 ° C under an oxygen partial pressure of at least about 3 atmospheres, advantageously between about 10 atmospheres and 30 atmospheres, heated and violently for the oxidation of substantially all of the sulphide sulfur of the Pyrrhotite and pentlandite stirred to form elemental sulfur and sulphate sulfur. When substantially all of the pyrrhotite and pentlandite have been oxidized, the oxidation reactions are terminated before substantial amounts of the chalcopyrite are oxidized. This oxidation treatment results in a slurry of elemental sulfur, iron oxide, gangue and unreacted chalcopyrite in a sulphate mother solution containing nickel. After separation from the elemental sulfur, iron oxide and the mother liquor, the chalcopyrite can be treated to obtain the copper, while the nickel can be obtained from the mother liquor.

The invention is illustrated below in examples:

Example I.

Samples slurried a Pyrrhotinflotationskonzentrates which 0.5 $ copper, 1.3% nickel, 53% iron, 33% of total sulfur, and contained as a residue essentially gait was applied to 30 wt. $ Peststoffe with recirculation water and a surface active reagent. The surfactant reagent was a mixture of water soluble aliphatic, primary, secondary and tertiary amines

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which contained approximately 85 % primary amines with an average molecular weight of 265 and were added in varying amounts to all slurries with the exception of the slurries of runs 1 to 5 and 9, since the latter were run for comparison purposes. The slurries were placed in a titanium autoclave equipped with a powered propeller to vigorously mix the slurry and cooling coils to control the slurry temperature. The slurries were ^{heated to HO 0} C and oxygen was introduced into the autoclave to bring the pressure up to 21.1 atmospheres (300 psig) that is, an oxygen partial pressure of about 20 atmospheres. At the onset of the exothermic oxidation reactions, the temperatures of the slurries were allowed to rise to a predetermined temperature and then maintained at that temperature by dissipating the heat through cooling coils. The amount of surface agent added to the slurries, the reaction temperatures and times, and the results of the experiments are shown in Table I. A comparison of experiment 4 with experiment j5 and experiments 10 to 13 with experiment 9 confirms that the use of a surface-active agent increases the dissolution of nickel at all temperatures and that at 160 ° C. the conversion of sulphide sulfur into elemental sulfur and sulphate sulfur is more complete , even in experiment Ij5, which was only carried out for 0.5 hours when a surface-active agent is used. A comparison of test 12 with test 2 shows that the use of higher temperatures, which are generated autogenously, results in improved nickel dissolution in half the time.

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Table I.

Ver
search-
No. Tempe
rature
⁰ C Time,
Hours. additive
to upper
surfaces
active
Agent, Kon
kg / t
(lbs / t) Dissolved % Cu Sulfur conversion % IL 19th Total 1 110 1 0 Ni
Z. 12th 3 ° 19th 84 2 110 2.5 0 8o 25th 65 16 95 3 120 1 0 90 5 74 20th 93 4th 120 1 2.27 (5) 70 3- 77 18th 92 5 130 1 2.27 (5) 83 9 72 18th 93 6th 14O 0.5 2.27 (5) 86 5 75 20th 92 7th l40 1 1.36 (3) 79 22nd 74 20th 97 8th 140 1 2.27 (5) 90 11 77 21 95 9 160 1 0 90 16 75 20th 80 10 I6o 1 0.45 (1) 56 27 59 23 98 11 160 1 1.13 (2.5) 77 36 78 22nd 98 12th 160 1 2.27 (5) 86 27 75 21 99 13th 160 0.5 2.27 (5) 9h 18th 77 96 88 75

Example II

This example confirms that nickel sulfide flotation concentrates treated by the method according to the invention

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can be delt. The attempts of this example were carried out in a manner similar to Example I, with the exception, however, that water to form the sludge and Alternating addition grind sizes were used. Experiments 14, 15 and 23 were carried out according to known procedures Carried out for comparison purposes. The input samples, grinding, oxidation temperatures and times, the addition of surface agents (same as used in Example I) and the results are summarized in Table II. A comparison of experiment 16 with experiment 14 and experiment 17 test 15 confirms that the use of a surfactant implies the use of higher oxidation temperatures which higher Niekel resolutions in same times. Experiments 24 to 28 show in the same way when compared with experiments 23 and 24 that the use of a surface-active agent really allows higher nickel recovery than that, at which no surfactant is used at the same temperature. Experiments 21, 22 and 29 to 31 confirm that the resolution of the grind depends on the size of the grind is heavily dependent on the addition.

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309851/1047

Claims (1)

Claims Process for the treatment of at least one sulphide mineral in an aqueous suspension for oxidation from at least a portion of the sulphide sulfur to elemental sulfur at temperatures above the Melting point of sulfur, characterized in that one of the aqueous suspension a surfactant in a small but effective amount to minimize wetting and the coating of the sulphide mineral by molten elemental sulfur added so that the oxidation of the sulfide mineral can continue. Method according to claim 1, characterized in that the melted elemental Sulfur is formed by heating a slurry of sulfide mineral and an acidic aqueous solution and cobalt, copper, lead, nickel and zinc will be leached from the mineral. 3. The method according to any one of claims 1 or 2, characterized characterized in that the sulfide mineral is at least one non-ferrous metal sulfide and includes substantial amounts of pyrrhotite which are slurried with water and the sulfide minerals Sludge to a temperature above 112 ° C below - 18 309851/1047 - Io - an oxygen partial pressure of at least three atmospheres for the oxidation of the pyrrhetine to elemental Sulfur and to dissolve the light-ferrous metal values is heated. 4. The method according to claim 3> characterized in that the metal sulfides include pyrrhotite, pentlandite and pyrite and the aqueous suspension to 120 ⁰ C to 160 ° C to oxidize the sulfide sulfur of the pyrrhetine and pentlandite to elemental sulfur and sulfate sulfur, for oxidation and excretion of the iron oxide compounds to dissolve the nickel and to form a residue comprising unreacted chalcopyrite and the precipitated iron oxide compounds. 5. The method according to any one of claims 3 or 4, characterized in that the slurry is ^{heated to a temperature of 130 0} C to 170 ⁰ C under an oxygen partial pressure of 10 to 30 atmospheres. 6. The method according to any one of claims 1 to 5 * characterized in that about 100 % of the sulfide mineral has a particle size of less than 149 microns (about 100 ^ minus 100 mesh TSS). 7. A method according to any one of claims 1 to 6, characterized in that the suspension contains 2 to 50 wt.% Peststoffe. 8. The method according to claim 7, characterized in that the slurry contains 5 to 30 wt.% Peststoffe. 309851/1047 - 19 - 9. The method according to any one of claims 1 to δ, characterized in that the surface-active Agent at least one of mixtures of water-soluble aliphatic amines, polyalkylene glycol esters, Polyoxyethylene lauryl ethers and sulfonated aromatic substances. 10. The method according to any one of claims 1 to 9, characterized in that the surface-active agent is added to the aqueous suspension in amounts of 2.27 kg / t of pesticides in the suspension to 4.5 ² J-kg / t of solids in the suspension. 309851/1041