RU2160319C1 - Method of reworking intermediate products of copper-and-nickel industry - Google Patents

Abstract

FIELD: non-ferrous metallurgy; reworking intermediate products containing precious metals; metallized and sulfide materials formed in the course of production of non-ferrous metals from copper and-nickel ores. SUBSTANCE: proposed method includes oxidizing sulfuric acid leaching under pressure at heating and aeration of solution, solubilizing nickel, cobalt and copper and bringing metals of platinum group to insoluble residue, reworking insoluble residue by liquid phase sulfatization followed by obtaining concentrate of precious metals; oxidizing sulfuric acid leaching is effected at pressure of 0.8 to 1.6 Mpa in solution containing ion Cu⁺²2-40 g/l 2 to 40 g/l; iron, nickel, cobalt and copper are solubilized and resulting pH of solution is maintained at level not higher than 1.0. Aeration is effected by means of oxygen-containing gas in the amount of 1,4-4,0 nm³ of oxygen per cu.m of solution. EFFECT: increased extraction of non-ferrous and platinum metals; low cost of process. 2 cl, 3 ex

Description

 The invention relates to non-ferrous metallurgy, in particular to the processing of intermediate products of technology containing precious metals, and can be used in relation to metallized and sulfide materials formed in the production of non-ferrous metals from copper-nickel ores.

 A known method (Novikova EI Non-ferrous metallurgy, bull. TsNIItsvetmet, M., N 3, 1975, S. 34-35) processing of copper-Nickel middlings released by magnetic separation during separation of copper-Nickel matte, including sulphating melting, allocation secondary industrial product, casting anodes from it and their electrolytic processing to produce sludges rich in platinoids.

 A known method (Autosvid. N 383752 USSR, class C 22 B 23/02, 1971) for processing copper-nickel intermediate product, including magnetic fraction of Feinsteins, including sulphidizing melting into secondary Feinstein, flotation separation of Feinstein into nickel and copper concentrates extraction of platinum metals from them.

 The disadvantages of the known pyrometallurgical methods for processing industrial products of copper-nickel production are high operating costs, multi-process flows, the formation of significant volumes of circulating products with a concentration of platinum metals in them.

The known method (Patent N 2144091 RF, IPC C 22 B 3/08, C 22 B 15:00; 23: 00, 1999) hydrometallurgical processing of industrial products of copper-nickel production, including atmospheric, two-stage oxidative leaching with sulfuric acid containing Cu ⁺² ion , a solution during heating and aeration, transferring to a sulfate solution of nickel, cobalt, iron and copper, obtaining a dissolution residue containing platinum group metals.

 The disadvantage of this method of atmospheric sulfuric acid leaching of products is the low content of precious metals in the insoluble residue.

 The closest in technical essence to the proposed method is the hydrometallurgical method (Gutin V.A. Isolation and processing of the magnetic fraction of Feinstein - one of the ways to increase the extraction of precious metals. Non-ferrous metals, N 12, 1988, p. 28-29) processing of copper-nickel by-product of enrichment methods during Feinstein separation, including autoclave sulfuric acid oxidative leaching of coarse-grained by-product, conversion of nickel, copper and cobalt into sulfate solution, and iron and platinum metals into insoluble the remainder. At the same time, the final pH of the solution is 1.4-3.5. Further leaching of iron from the residue is carried out in a sulfuric acid solution in the presence of a reducing agent - sulfur dioxide - and platinum metals are isolated into an insoluble residue.

 The disadvantages of the known method of autoclave processing of industrial products are high technological energy consumption, a significant yield of insoluble residue, the need for additional operations to extract iron from the residue of dissolution.

 Our proposed method solves the following technical problem: increasing the extraction of non-ferrous, including platinum metals, reducing processing costs, reducing the yield of insoluble residue and increasing the content of precious metals in the residue.

 In copper-nickel production, industrial products enriched in the content of precious metals are obtained by isolating the metallized phase from Feinstein and nickel concentrate, as well as by atmospheric leaching of the metallized phase (alloy) in sulfate solutions.

 Metallized alloy is isolated by enrichment methods and hydrodynamic classification. The most common names for these products are the Feinstein magnetic fraction (MFF) and the nickel concentrate magnetic fraction (MFN).

 According to the grain composition, MFF is a coarse-grained material (grain size more than 0.3 mm), contains up to 15% copper. The product should be subjected to atmospheric sulfuric acid leaching when heated with aeration of the solution. In the process of chemical dissolution, natural grinding of the material to a particle size of less than 0.3 mm should occur.

 MFN is a finely dispersed material (grain size less than 0.3 mm), contains up to 10% copper and can be supplied both to atmospheric leaching and to dissolution in autoclave-type apparatuses.

 The main phase of the component of the magnetic fraction is a nickel-based metal alloy, the content of which varies between 50-70% by weight, the rest is copper, iron and cobalt sulfides, a small amount of silica and magnetite. The magnetic fraction contains a significant amount of platinum group metals, 10-14 times more than in Feinstein. The sulfur content in the magnetic fraction is 3-8%. The main phase component of the residue of atmospheric dissolution is a mixture of sulfides and an unopened metallized phase. The sulfur content in the residue is not less than 15%.

 The residue of atmospheric leaching of the metallized alloy is fine-grained (grain size less than 0.3 mm) and is enriched with platinum group metals to a content of 0.6-1.4%.

 The content of the platinum group metals in the initial Feinsteins and, accordingly, in the isolated MFF and MFN is significantly different and, in addition, depending on the composition of the Feinstein and its cooling rate, the phase structure of the Feinstein and the magnetic fraction changes, in which the ratio between the metal and sulfide components changes.

 The residue from the dissolution of the magnetic fraction during processing by atmospheric sulfuric acid leaching of different quality magnetic fractions contains a variable amount of platinum group metals. With an increased content of sulfides of the magnetic fraction, significant costs are required to refine the residue of dissolution by liquid-phase sulfatization.

A method is proposed that includes oxidative sulfuric acid leaching under pressure during heating and aeration of a solution, converting nickel, cobalt and copper into a solution, and platinum group metals into an insoluble residue, processing the insoluble residue by liquid phase sulfatization to obtain a precious metal concentrate, in which, unlike the known method sulfuric acid oxidative leach is carried out at a pressure of 0.8-1.6 MPa in a solution containing ion Cu ⁺² 2-40 g / l, the solution was transferred to iron, nickel, cobalt, m strand and the final pH of the solution is maintained not greater than 1.0. Aeration is carried out with oxygen-containing gas in an amount of 1.4-4.0 nm ³ oxygen per 1 m ^{3 of} solution.

 Leaching is carried out in autoclave plants. Sulfuric acid is necessary for the conversion of metals to sulfate, because the sulfide sulfur content in the initial intermediate product is not enough to convert all metals to the sulfate form and to create the optimal acidity of the medium. The leaching process proceeds most intensively if the acidity of the final solution is 8-10 g / l (pH less than 1.0). Decreasing the acidity of the solution (pH greater than 1.0) reduces the degree of extraction of non-ferrous metals into the solution and significantly iron, the filterability of the pulp deteriorates, the yield of cake increases, and its further processing is complicated. An increase in acidity of more than 10 g / l leads to an increase in the specific consumption of sulfuric acid.

Steam is used to heat the pulp. In the interaction of the intermediate with an acid solution, hydrogen sulfide may be released, which is suppressed when the Cu ^{+ 2} ion content in the initial solution is 2–40 g / l. In addition, Cu ⁺² serves as a catalyst for the dissolution of nickel, cobalt and iron. The content of Cu ⁺² ion less than 2 g / l does not provide absorption of the released hydrogen sulfide. When the content of Cu ^{+ 2} ion is more than 40 g / l, an increase in the process speed is not observed, but the solution is contaminated with copper, which further increases the load on the redistribution of the solution from copper.

 The most optimal pressure in the autoclave is in the range of 0.8-1.6 MPa. The decrease in total pressure below 0.8 MPa leads to an increase in the duration of leaching and the deterioration of the filterability of the final pulp; an increase in pressure of more than 1.6 MPa has virtually no effect on technological performance, but tightens requirements for the equipment of an autoclave plant.

 The process is as follows.

An intermediate product with a grain size of less than 0.3 mm is delivered to an autoclave unit and loaded into a receiving repulpator with mechanical stirring, a volume of 10 m ³ , into which a circulating, acidic, copper-containing solution is added. If it is necessary to increase the required acidity (180-280 g / l), the required amount of sulfuric acid is added, and to reduce the concentration, dilution with wash water from the existing workshop is provided. This level of acid concentration provides a fairly complete dissolution of the intermediate in the presence of a Cu ^{+ 2} ion and with intensive purging of the solution with an oxygen-containing gas. With a sulfuric acid content of more than 280 g / l, the extraction is reduced and the wear of the acid-resistant lining of the autoclave is increased.

As the starting material, the metallized phase of the nickel concentrate or the residue of atmospheric dissolution of MFF and MFN are used. Product loading is carried out in the amount calculated for a given volume of acid that is necessary to neutralize the acid to the required pH with the conversion of 95% nickel, cobalt, iron and ~ 50% copper into the solution. The average initial pulp with a solution content of 2-40 g / l Cu ⁺² and 180-280 g / l sulfuric acid is pumped to the head column of a string of autoclaves (12 columns in one string). There, continuously under pressure, steam is supplied to heat the pulp and an oxygen-containing gas in an amount of 1.4-4.0 nm ³ per 1 m ^{3 of a} solution for oxidizing and mixing the pulp. In the autoclave, pressure is maintained in the range of 0.8-1.6 MPa and a temperature of 120-160 ^o C. At higher temperatures, partial dissolution of platinum group metal satellites is observed. The leaching time under specified conditions is 0.6-1 hours and provides an insoluble residue enriched in platinum group metals.

 After the process is completed at a pH of not more than 1.0, the leached pulp from the last column is sent to separators, where the pulp is separated from the vapor-gas mixture, and then filtered, after which the sulfate solution is used to produce cathode nickel or nickel salts. An insoluble residue containing platinum group metals is sent to the leaching stage II, which is carried out similarly to the first stage. The residue after stage II leaching is sent for processing by liquid phase sulfatization to obtain a precious metal concentrate.

 The method worked out in laboratory mode and tested on an industrial scale.

 Examples of the method.

 Example 1. In an industrial string of autoclaves, 1200 kg of a magnetic fraction of a nickel concentrate composition were processed,%: Ni - 69.91; Cu 10.24; Co - 2.086; Fe - 8.55; Pd 0.14; S - 8.52. The particle size of the intermediate: 8% - less than 0.3 mm, 92% - less than 0.2 mm.

Leaching conditions: pressure -1.3 MPa, temperature -140 ^o C, Cu ⁺² content in the solution for preparing the initial pulp - 17 g / l, sulfuric acid -220 g / l, leaching time - 0.8 hours. After filtration of the leached pulp, the remainder of the composition was obtained,%: N - 21.0; Cu-26.7; Co - 0.75; Fe - 4.8; Pd - 1.12, S - 34. Weight reduction by 8 times.

Extraction into solution,%: Ni - 96.3; Cu 67.4; Co 95.58; Fe - 93. The pH of the final solution is 1.0. The oxygen consumption in the air mixture for pulp aeration is 3.7 nm ³ per 1 m ^{3 of} solution.

Example 2. The magnetic fraction of Nickel concentrate in an amount of 5 kg, composition,%: N - 70.3; Cu, 10.41; Co - 1.98; Fe 8.18; S 8.87; Pd - 0.15, a similar fineness was processed in an experimental autoclave with a volume of 25 l under the following conditions: pressure - 0.9 MPa, temperature - 130 ^o C, the copper content in the solution for the preparation of concentrate pulp 20 g / l, leaching time 0.6 hours, the pH of the final solution is 0.9 units The purge air is enriched with oxygen up to 2.3 nm ³ per 1 m ^{3 of} solution. The obtained precipitate composition,%: Ni - 23; Cu 24.2; Co - 0.9; Fe - 4.5, S - 36. Extraction into solution,%: Ni - 95.3; Cu - 66.9; Co - 94; Fe - 92.4. Reducing the mass of material by 7 times. The palladium content in the residue is 1.05%.

Example 3. The residue from atmospheric leaching of the magnetic fraction of the nickel concentrate composition,%: Ni - 42.0; Cu - 13.5; Co - 1.8; Fe - 3.0; Pd 0.635; S - 38, in an amount of 200 g was processed in a laboratory autoclave with a volume of 1 l under conditions: pressure - 1.2 MPa, temperature - 130 ^o C, copper content in the initial solution - 27 g / l, sulfuric acid 190 g / l, duration leaching for 1 hour, the pH of the final solution is 0.9 units The oxygen consumption in the oxygen-containing mixture for aeration is 1.7 nm ³ per 1 m ^{3 of} solution. The remainder of the composition,%: Ni - 7.0; Cu - 13.0; Co - 0.45; Fe - 1.33; Pd - 1.4. Weight reduction - 2.2 times. The yield of the residue is 45.5%. Extraction into solution,%: Ni - 92.4; Cu 56.2; Co - 89: Fe - 79.8.

 Thus, the totality of the claimed features of the invention in comparison with the prototype allows to increase the extraction of non-ferrous metals in solution and platinum metals in the leach residue, to reduce the yield of insoluble residue from leaching and, accordingly, to reduce operating costs for processing the residue.

Claims (2)

1. A method of processing industrial products of copper-nickel production, including oxidative sulfuric acid leaching under pressure during heating and aeration of the solution, converting nickel, cobalt, copper into solution, and platinum group metals into an insoluble residue, processing the residue by liquid-phase sulfatization to precious metals concentrate, characterized in that oxidative sulfuric acid leaching is carried out at a pressure of 0.8 - 1.6 MPa in the presence of a Cu ⁺² 2 - 40 g / l ion, while iron, nickel, cobalt, copper are transferred into the solution, and the final pH of the solution is maintained no more than 1.0. 2. The method according to claim 1, characterized in that the aeration is carried out with an oxygen-containing gas in an amount of 1.4 - 4.0 nm ³ oxygen per 1 m ^{3 of} solution.