RU2492253C1 - Method of producing nickel from sulfide ore stock - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: proposed method comprises leaching by chloride solution at feed of oxygen and chlorine. Then, copper is precipitated from said solution to obtain copper sulfide cake and said solution of cleaned of iron, zinc and cobalt. after cleaning nickel is electrically extracted from the solution while effluent is processed to recover chlorine and alkali. Note here that leaching is performed in two steps with solution backflow. Note here that only oxygen is fed to said first step while only chlorine is fed to said second step.

EFFECT: ruled out losses of nonferrous metals, lower costs.

5 cl, 5 tbl, 7 ex

Description

The invention relates to the field of non-ferrous metals, in particular, nickel from sulfide ores by oxidative leaching, followed by purification of the leach solution and electroextraction.

A known method for producing nickel and a concentrate of precious metals from copper-nickel matte (application for invention of the Russian Federation No. 2009138072), according to which the sulfide material is copper-nickel matte is leached with a chloride solution when chlorine is fed, copper is precipitated from the leach solution, the solution is purified from iron, zinc, copper and cobalt and nickel is obtained by electroextraction from a purified solution. The method is applicable only to sulfide raw materials with a low iron content, which determines the possibility of extracting it from the solution by standard methods, since the deep extraction of iron into the solution is implemented at the leaching stage.

A known method of dissolving sulfide raw materials based on Nickel, cobalt and iron (US Patent No. 4384940) with a chlorine feed, according to which non-ferrous metals are extracted from Feinstein in the sequence of leaching processes with the supply of oxygen under pressure and the subsequent leaching of the obtained residue with the supply of chlorine. The use of the method without the use of an external catalyst is limited to raw materials with a high content of the sum of non-ferrous metals, since the reagentless conversion to iron cake (III), formed at the leaching stage with the supply of chlorine, is possible only during the processes of reduction of iron (III) to iron (II) at interaction with non-ferrous metal sulfides, the oxidation of iron (II) to iron (III) by oxygen with the consumption of acid and hydrolysis of iron (III). In addition, for the oxidation of iron from a solution with a high concentration in this method, oxygen is supplied to the reaction zone under pressure, which complicates and increases the cost of the hardware design of the process.

A known method of processing nickel-containing raw materials by chloride leaching (WO No. 2007/039665), according to which the sulfide ore concentrate is dissolved in a two-stage process, with the solution of the second leaching stage containing copper (II) being supplied to the first stage, together with the concentrate. As a result of the interaction of copper (II) with sulfides of the concentrate, nickel and iron pass into solution, and copper precipitates in the form of CU2S. The leaching residue of the first stage is transferred to the second stage, and reagents — oxygen (air) and hydrochloric acid or chlorine — that transfer Cu ₂ S from the solid phase to the solution in the form of copper (II) chloride, are supplied. Cu (II) oxidizes sulfides of nickel and iron, converting nickel and iron into solution and reducing to Cu (I), and is again regenerated by the oxidizing agent supplied to the second stage. The iron transferred to the solution is hydrolyzed and passes into the leach residue in the form of hematite. The solution from the first leaching stage is cleaned of iron with lime with the return of the precipitate to the second leaching stage, nickel hydroxide or metallic nickel is obtained from the filtrate, magnesium hydroxide is precipitated and chlorine, hydrogen and alkali are produced by electrolysis, and hydrochloric acid is synthesized from chlorine and hydrogen. Alkali and hydrochloric acid (in the embodiment, chlorine is used instead of oxygen and hydrochloric acid) are used in the second leaching stage, and hydrogen in the embodiment is used to produce metallic nickel.

The disadvantage of this method is its applicability only to ore raw materials with a low copper content, since the scheme does not imply deep extraction of copper from the concentrate, and leaching with oxygen at atmospheric pressure does not allow copper to be effectively extracted from sulfide minerals. The method is applicable to sulfide raw materials of limited mineral composition. In an example implementation of the method indicated easily leachable pentlandite. Minerals such as pyrrhotite and chalcopyrite are leached at potentials that cannot be achieved with oxygen leaching. The use of chlorine as an oxidizing agent will increase the extraction of nickel and copper in the solution, but thereby eliminate the separation of nickel and copper stated in the description of the method at the leaching stage.

The second important disadvantage of this method is the need for a significant consumption of hydrochloric acid for the implementation of deep metal extraction during leaching with oxygen. Given the fact that the acid consumption during the oxidation of copper (1) by oxygen only compensates for the formation of acid during the hydrolysis of iron (III), the added acid can only be neutralized by the basic magnesium compounds in the concentrate, and, therefore, the method is implemented only if they are sufficient content and activity. The lack of effective neutralization of free acid prevents the hydrolysis of iron (III) and determines the need for organizing the process of cleaning the leach solution from iron at its high concentration. In the variant of using chlorine as an oxidizing agent, the processes occurring with the consumption of acid - with the exception of neutralization with basic magnesium compounds - are absent, which also prevents the hydrolysis of iron (III). With a high content of sulfide iron in the starting material, the iron cleaning unit becomes very bulky, requires a significant consumption of reagents, areas of filtering equipment and is characterized by a high turnover of iron-containing cake.

The closest technical solution is a method for processing sulfide nickel ore or concentrates, including oxidative leaching with oxygen or air at atmospheric pressure in a solution of sodium chloride and hydrochloric acid (WO No. 2007/039663). Copper (II) -containing solution obtained by treating chlorine with the leach recycle solution, or directly chlorine, is also fed to leaching. Copper is removed from the cycle by precipitation with alkali in the form of copper hydroxide (1). In addition, the scheme provides for the return of copper (II) from the leach solution in the form of hydroxychloride. The disadvantage of this method is the possibility of its implementation only with a significant amount of neutralizer (rock-forming compounds of magnesium and other base metals) in the ore concentrate - sufficient to neutralize the supplied hydrochloric acid and part equivalent to the amount of chlorine leached for leaching - iron hydrolysis acid. If there is a lack of a converter in the concentrate, a significant amount of iron from the solution should be removed in a separate redistribution.

The objective of the present invention is to reduce material costs, operating costs and losses in the production of electrolyte nickel due to the oxidative leaching of non-ferrous metals from poor in their content of sulfide ore raw materials without introducing external acid into the leaching process.

The technical result is achieved by the fact that in the proposed method for producing nickel from ore sulfide raw materials, which includes leaching with a chloride solution when oxygen and chlorine are supplied with a control of the consumption of chlorine by the value of the redox potential, precipitation of copper from the solution to obtain copper sulfide cake, and cleaning the solution of iron , zinc and cobalt and nickel electroextraction, according to the invention, leaching is carried out in two stages with a countercurrent solution, while only oxygen is supplied to the first stage and the second only chlorine.

In this case, the supply of chlorine is controlled by the value of the redox potential, which is kept within 450-700 mV.

Leaching with oxygen is carried out for 5-30 hours.

In addition, non-ferrous metals and magnesium are precipitated from the washing water of the leach residue with the supply of chlorine, the precipitate is filtered off and returned to the leaching cycle, and the filtrate is returned to the washing.

In this case, non-ferrous metals and magnesium are precipitated with lime.

The sequence of redistribution of the technological scheme for the production of electrolyte nickel according to the claimed method is presented in figure 1.

At the leaching stage with the supply of oxygen, oxidation of iron sulfides, the conversion of iron (II) to iron (III), and hydrolysis are realized. Copper ions act as mediators of oxidation. The oxidized form of copper ions is generated by the acid-consuming reaction:

$$\text{2CuCl + 0}{\text{5O}}_{\text{2}}{\text{+ 2HCl = CuCl}}_{\text{2}}{\text{+ H}}_{\text{2}}\text{O}\left(\text{one}\right)$$

Further, copper (II) ions oxidize sulfides containing iron by the reactions:

$$2F{e}_{\left(\mathrm{one}-x\right)}S+\mathrm{four}\left(\mathrm{one}-x\right)CuC{l}_2=2\left(\mathrm{one}-x\right)FeC{l}_2+\mathrm{four}\left(\mathrm{one}-x\right)CuCl+2S\left(2\right)$$

$$CuFe{S}_2+3CuC{l}_2=\mathrm{four}CuCl+FeC{l}_2+2S\left(3\right)$$

$$2{\left(Ni,Fe\right)}_9{S}_8+36CuC{l}_2=9NiC{l}_2+9FeC{l}_2+36CuCl+16S\left(\mathrm{four}\right)$$

In total with reaction (1), reactions (2) - (4) are written as:

$$2F{e}_{\left(\mathrm{one}-x\right)}S+\left(\mathrm{one}-x\right)O_2+\mathrm{four}\left(\mathrm{one}-x\right)HCl=2\left(\mathrm{one}-x\right)FeC{l}_2+2\left(\mathrm{one}-x\right)H_{2}O+2S\left(5\right)$$

$$CuFe{S}_2+O_2+\mathrm{four}HCl=CuC{l}_2+FeC{l}_2+2H_{2}O+2S\left(6\right)$$

$$2{\left(Ni,Fe\right)}_9{S}_8+9O_2+36HCl=9NiC{l}_2+9FeC{l}_2+16S+\mathrm{eighteen}{H}_{2}O\left(7\right)$$

Or, in relation to iron sulfide:

2FeS + O ₂ + 4HCl = 2FeCl ₂ + 2H ₂ O + 2S

Iron (II) is oxidized to iron (III) and is hydrolyzed by the reaction

$$FeC{l}_2+CuC{l}_2+2H_{2}O=FeOOH+CuCl+3HCl\left(8\right)$$

Or, in total with reaction (1):

$$\mathrm{four}FeC{l}_2+O_2+6H_{2}O=\mathrm{four}FeOOH+8HCl\left(9\right)$$

with the formation of acid hydrolysis.

The final reaction of the opening of iron sulfide is written by the equation:

$$\mathrm{four}FeS+3O_2+2H_{2}O=\mathrm{four}FeOOH+\mathrm{four}S\left(10\right)$$

and proceeds with zero acid balance.

Copper (II), coming from the leaching stage with the supply of chlorine, and copper (II), resulting from the oxidation of copper (1) by oxygen, is also involved in the transfer to the solution of non-ferrous metals - nickel, cobalt and copper - according to reactions (3) - (4) or similar leaching reactions containing nickel, cobalt and copper minerals that make up the ore.

Oxidation of copper (I) by oxygen according to reaction (1) with the subsequent participation of copper (II) ions in reactions of transfer to a solution of non-ferrous metals proceeds with the consumption of acid. With the consumption of acid, dissolution reactions of the main compounds (magnesium, aluminum, calcium) of the rock-forming phases also occur.

These processes neutralize the leach from the redistribution with the supply of chlorine, the acid-containing solution and the acid of hydrolysis of iron dissolved in this leach stage.

At the leach redistribution with the supply of chlorine, deep opening processes are not opened at the leaching stage with the supply of oxygen sulfide phases with the transfer of non-ferrous metals and iron to the solution according to the reactions:

$$F{e}_{\left(\mathrm{one}-x\right)}S+\left(\mathrm{one}-x\right)C{l}_2=\left(\mathrm{one}-x\right)FeC{l}_2+S\left(\mathrm{eleven}\right)$$

$$F{e}_{\left(\mathrm{one}-x\right)}S+\mathrm{1,5}\left(\mathrm{one}-x\right)C{l}_2=\left(\mathrm{one}-x\right)FeC{l}_3+S\left(12\right)$$

$$CuFe{S}_2+2C{l}_2=CuC{l}_2+FeC{l}_2+2S\left(13\right)$$

$$CuFe{S}_2+\mathrm{2,5}C{l}_2=CuC{l}_2+FeC{l}_3+2S\left(\mathrm{fourteen}\right)$$

$$2{\left(Ni,Fe\right)}_9{S}_8+\mathrm{eighteen}C{l}_2=9NiC{l}_2+9FeC{l}_2+16S\left(\mathrm{fifteen}\right)$$

$$2{\left(Ni,Fe\right)}_9{S}_8+27C{l}_2=9NiC{l}_2+9FeC{l}_2+16S,\left(16\right)$$

flowing also with the participation of mediators - copper ions.

Partially sulfide and, possibly, elemental sulfur is also oxidized to sulfate according to reactions (13) - (14):

$$S+3C{l}_2+\mathrm{four}{H}_{2}O=H_{2}S{O}_{\mathrm{four}}+6HCl\left(17\right)$$

$$MeS+\mathrm{four}C{l}_2+\mathrm{four}{H}_{2}O=MeS{O}_{\mathrm{four}}+8HCl\left(\mathrm{eighteen}\right)$$

where Me is Ni, Co, Cu, Fe

The acid and acid of hydrolysis of iron (III) formed by reactions (17) - (18) are neutralized at the leaching stages with the supply of oxygen (mainly) and chlorine by the main compounds of magnesium, aluminum, calcium, which are part of the rock-forming minerals. Weak basic properties of rock-forming minerals determine the slowness of the acid neutralization process. Therefore, the duration of the leaching stage with the supply of oxygen, at which a low (less than 1 g / l) iron content in the leaching solution is realized, ranges from several hours to tens of hours.

Deep extraction of nickel, cobalt and copper from refractory minerals occurs at sufficiently high values of the redox potential (ORP) at the leaching stage with the supply of chlorine. High ORP values result in an increase in the yield of reactions (17) - (18) and, accordingly, the flow of acid with a leaching solution with the supply of chlorine to the leaching stage with oxygen supply. In addition, with a high ORP value, the proportion of copper (II) in the leach solution with a supply of chlorine increases, and, accordingly, the proportion of non-ferrous metals transferred to the solution at the stage of leaching with oxygen supply. Thus, leaching is largely realized at the stage of leaching with oxygen supply, and at the second stage, leaching with the supply of chlorine, the leaching cake with oxygen supply and the deep oxidation of copper (1) to copper (II) are provided.

In general, the overall process is as follows:

- the transfer of most of the iron from the sulfide form to hydrate with zero acid acid balance by oxidation with the supply of oxygen;

- the conversion of a smaller portion of iron from the sulfide form to the hydrate form — by oxidation with the supply of chlorine to form hydrolysis acid;

- the transfer of part of non-ferrous metals into solution with the consumption of acid in the oxidation process with oxygen supply;

- transfer of the remaining amount of non-ferrous metals to a solution with zero acid acid balance by oxidation with the supply of chlorine;

- the formation of acid during the oxidation of sulfide and elemental sulfur with the supply of chlorine;

- equivalent to the formation of acid neutralization by the main rock-forming minerals of ore raw materials.

The overall acid balance in processes 1-5 is positive, therefore it is the presence in the ore raw materials of a significant amount of the basic compounds of magnesium, aluminum, calcium that are part of the rock-forming minerals that provides a low acidity leach solution.

With a decrease in the ORP, the formation of acid at the leaching stage with the supply of chlorine decreases. Also, the formation of copper (II) ions at the leaching stage with the supply of chlorine and the corresponding formation of acid, which is not compensated by the acid-consuming reaction of the formation of copper (II) with oxygen, are reduced. The percentage of extraction of non-ferrous metals into the solution at the leaching stage with the supply of chlorine increases, but the total recovery decreases. The addition of external acid to any stage does not increase the extraction of non-ferrous metals into the solution from refractory minerals and only determines the increased transfer of magnesium, aluminum, and calcium from the compounds that make up the rock-forming minerals into the solution. A decrease in the ORP below 450 mV leads to a technologically unacceptable decrease in the extraction of non-ferrous metals into the solution.

With increasing ORP, acid formation increases, and with a certain high value of ORP, the resulting acid can no longer be neutralized by the main compounds of rock-forming minerals. Accordingly, a leach solution with oxygen supply will be characterized by high levels of acid and iron, which will lead to an increase in the consumption of reagents during its purification. In addition, with a deep opening of rock-forming minerals in the resulting solution, the contents of magnesium, aluminum and calcium will increase, which will adversely affect the performance of subsequent processes of solution cleaning and electroextraction of nickel. The maximum ORP value is limited by the level of 700 mV, above which the transition of chlorine to gases significantly increases.

Water after washing the leach residue with the supply of chlorine is partially attached to the filtrate and partially treated with a neutralizer, in particular, lime for the deposition of non-ferrous metals and magnesium. The precipitation pulp is filtered off, the precipitate returns to the leaching stage with a chlorine feed, partially neutralizing the acid formed at this stage, and the filtrate containing chloride and sodium sulfate is again used to wash the leach residue with a chlorine feed. This reduces the consumption of fresh water for flushing. Washed from non-ferrous metals, the leach residue is sent to the dump.

The filtrate from the leaching stage with oxygen supply, containing in addition to nickel and cobalt copper in a significant concentration, a small amount of iron, as well as zinc, magnesium and other basic metals, is sent for purification. The first of the treatment operations is copper purification using nickel powder of metallurgical production, or another dispersed metallized intermediate of nickel production and ground elemental sulfur. The deposition of copper in cake is realized by the reactions:

$$2C{u}^{2+}+Ni=2C{u}^{+}+N{i}^{2+}\left(19\right)$$

$$2C{u}^{+}+2S+Ni=2CuS+N{i}^{2+}\left(\mathrm{twenty}\right)$$

Copper cake is filtered, washed and sent to copper production.

Before electroextraction of nickel, the solution obtained after deposition of copper in copper sulfide cake is subjected to extraction. purification from iron and zinc; and hydrolytic purification from cobalt.

A part of the solution purified from copper, iron and zinc is removed from the cycle to the redistribution of nickel carbonate, which is necessary for hydrolytic purification of the electrolyte from cobalt. Magnesium hydroxide is precipitated from the carbonate redistribution with alkali, the filtrate is evaporated, sodium sulfate is crystallized from the evaporated solution, and the mother liquor containing sodium chloride is subjected to electrolysis to obtain chlorine and alkali solution used in the technology.

The following examples describe embodiments of the invention.

Example 1

Oxygen leaching (KB) was subjected to the ore concentrate of the composition indicated in Table 1, ground to a fraction of 71 μm.

Table 1 Ni With Cu Fe S Mg the weight. % 8.53 0.28 3.56 35.8 23.8 5.41

265 g of the concentrate was pulp in 1 l of solution from the second stage of leaching (leaching with a supply of chlorine (CV)) at a temperature of 80 ° C. Oxygen was supplied to the pulp through a distributor at a rate of 2.0 L / min. The experiment lasted 10 hours, after which the pulp was filtered. The oxygen leaching residue was filtered and leached with chlorine for 3 hours in a synthetic solution of the calculated composition at a boiling point while maintaining an ORP value of 620 mV. The yield of leach residue with oxygen supply amounted to 109.7% by weight of the ore concentrate, the yield of leach residue with chlorine feed was 92.6% of the mass of the leach residue with oxygen supply. The compositions of sediments and solutions and the values of the extracts of the components of the concentrate are shown in table 2.

table 2 Compositions Ni With Cu Fe Mg S

$$S{O}_{\mathrm{four}}^{2-}$$

Cl ^- Ref. solution on KB g / dm ³ 63.6 1.3 19.9 5,4 11.1 20,4 141 RR KB g / dm ³ 79.7 1.8 21.9 1,0 12.0 20.8 141 remainder KB % 2.22 0.09 2,55 34.1 4.6 21.6 Extraction in solution on KB % 72 66 21,4 5.9 0.2 Sludge recovery on KB % 81.3 Ref. RR on HV g / dm ³ 83,2 1.9 25.8 3.8 13.1 23.9 165 HV g / dm ³ 89.4 2.1 32.9 8.9 15,2 29.5 207 balance XB % 0.21 0.01 0.28 35.1 4.3 22.7 Extraction in a solution on HV % 91.3 88.7 89.7 4.8 14.7 2,8 Total recovery in solution % 97.5 96.1 91.9 0.42 19.8 3.0

Example 2

In the experiment of example 2, performed under conditions similar to the experience of example 1, the duration of the leaching stage with the supply of oxygen was increased to 30 hours. The output of the leach residue with oxygen supply amounted to 109.3% by weight of the ore concentrate, the yield of leach residue with the supply of chlorine was 92.3% of the mass of the leach residue with oxygen supply. The compositions of sediments and solutions and the values of the extracts of the components of the concentrate are shown in table 3.

Table 3 Compositions Ni With Cu Fe Mg S

$$S{O}_{\mathrm{four}}^{2-}$$

Cl ^- Ref. solution on KB g / dm ³ 63.8 1.3 20.1 5,6 12,2 21.5 146 KV g / dm ³ 80.3 1.8 22.1 0,0 14.3 21.8 147 remainder KB % 2, P 0.09 2.60 34.7 4.2 21.7 Extraction in solution on KB % 73 66 20,2 14.6 0.2 Sludge recovery on KB % 99.9 Ref. RR on HV g / dm ³ 83.6 1.9 26.1 3.3 15,2 25,2 171 r-rHV g / dm ³ 89.7 2.2 33.3 9.3 17.0 31,2 216 balance XB % 0.17 0.01 0.27 35.5 4.0 22.8 Extraction in a solution on HV % 92.7 89.1 90.3 5,6 13.3 3.0 Total recovery in solution % 98.0 96.3 92.3 0.008 26.0 3.2

The increase in the duration of the leaching stage with the supply of oxygen led to a greater completeness of hydrolysis of iron and to obtain a solution with a very low content. The neutralization of the hydrolysis acid with the main magnesium compounds contained in the concentrate led to a greater extraction of magnesium into the solution.

Example 3

In the experiment of example 3, performed under conditions similar to the experience of example 1, leaching with a supply of chlorine was performed at an ORP of 450 mV. The yield of leach residue with oxygen supply was 110.8% by weight of the ore concentrate, the yield of leach residue with chlorine feed was 94.2% of the weight of the leach residue with oxygen supply. The compositions of sediments and solutions and the values of the extracts of the components of the concentrate are shown in table 4.

Table 4 Compositions Ni With Si Fe Mg S

$$S{O}_{\mathrm{four}}^{2-}$$

Cl ^- Ref. solution on KB g / dm ³ 63.7 1.3 13.8 2,8 3.6 16.1 by RR KB g / dm ³ 77.5 1.7 14.3 0.8 3,7 16.1 110 remainder KB % 2.90 0.11 3.0 33.0 4.9 21.5 Extraction in solution on KB % 62 55 5.2 0.5 0,0 Sludge recovery on KB % 72.1 Ref. RR on HV g / dm ³ 81.9 1.9 17.3 2.1 4.0 18.3 128 HV g / dm ³ 89.8 2.2 22.8 4.6 4,5 22.3 161 balance XB % 0.36 0.02 1.34 34.2 5,0 22.4 Extraction in a solution on HV % 88.3 85,4 58.6 2,4 3.3 2.0 Total recovery in solution % 95.6 93.5 60.8 0.33 3.8 2.0

The decrease in the leaching ORP with the supply of chlorine somewhat reduces the extraction of nickel and cobalt and, significantly, copper into the solution, which limits the application of the method in the mode of soft leaching with low copper content raw materials.

Example 4

In the experiment of example 4, performed under conditions similar to the experience of example 1, leaching with a supply of chlorine was performed at an ORP value of 700 mV. The yield of leach residue with oxygen supply was 105.6% by weight of the ore concentrate, the yield of leach residue with chlorine feed was 92.0% of the weight of the leach residue with oxygen supply. The compositions of sediments and solutions and the values of the extracts of the components of the concentrate are shown in table 5.

Table 5 Compositions Ni With Si Fe Mg S SO ₄ ^2- Cl ^- Ref. solution on KB g / dm ³ 62.9 1.3 19.3 10.1 23,4 43.0 181 RR KB g / dm ³ 82.7 1.9 23.0 1,2 30.3 45,2 181 remainder KB % 1.20 0.06 2.1 37.0 2.7 22.3 Extraction in solution on KB % 85 77 38.9 47.3 1.10 Sludge recovery on KB % 88.1 Ref. RR on HV g / dm ³ 84.6 2.0 26.3 6.8 31,0 50.8 213 HV g / dm ³ 88.1 2.1 32,0 16.7 32,3 60.7 269 balance XB % 0.05 0.00 0.20 36.7 2,5 23.0 Extraction in a solution on HV % 95.8 93.6 91 8.8 15,2 4.90 Total recovery in solution % 99,4 98.6 94.5 0.50 55.3 5.95

An increase in the leaching ORP with the supply of chlorine increases the extraction of nickel, cobalt, and copper into the solution. However, this increases the oxidation of sulfide sulfur of the concentrate to sulfide with equivalent formation of acid and the consumption of basic magnesium compounds to neutralize it.

Reducing the duration of the leaching stage with an oxygen supply below 5 hours leads to a significant increase in the iron content in the filtrate and an increase in the cost of subsequent cleaning of the solution. An increase in the duration of this stage is impractical, since deep extraction of iron into the precipitate is already achieved in 20-30 hours. Since ore concentrates are characterized by a significant zinc content, purification of the solution involves a liquid extraction step, in which pre-oxidized iron is also extracted from the solution together with zinc. The presence of extraction redistribution allows you to limit the depth of deposition of iron from the solution at the leaching stage with an oxygen supply of ~ 1 g / dm ³ , correspondingly reducing the stage duration to 10-20 hours.

A decrease in the ORP value at the leaching stage with a chlorine supply below 450 mV results in a significant decrease in the extraction of nickel and cobalt into the solution. An increase in the ORP level in excess of 700 mV leads to a breakthrough of chlorine in the gases and, in addition, it sharply increases the oxidation of sulfide sulfur to sulfate with the formation of a significant amount of acid, which can no longer be neutralized by the basic magnesium compounds contained in the concentrate.

Example 5

In a series of cyclic experiments of Example 5, carried out under conditions similar to that of Example 1, by adding lime taken with a 50% excess to stoichiometry, the acid was neutralized and nickel, cobalt, copper, iron and magnesium were precipitated from the leaching residue leaching water with the supply of chlorine . The pulp was filtered off, the precipitate was transferred to the next leach cycle with a supply of chlorine, 30% of the filtrate was taken to prepare a starting leach solution with oxygen supply, and 70% with the addition of an equal selected volume of fresh water was used to wash the cake of the next leach with chlorine feed. After 5 cycles of dissolution, the composition of the industrial product and, accordingly, the moisture in the dump cake, stabilized at, g / dm ³ : Ca - 3.0; Cl ^- - 5.1; SO ₄ ^2- - 0.5; Mg - 0.3.

Example 6

In 1 l of a leaching solution with oxygen supply, an experiment performed analogously to example 1, with stirring, 14 g (0.92 g / g of copper in solution) of nickel powder of tube furnaces and 9 g (0.60 g / g of copper in solution) were ground sulfur. The duration of the experiment is 60 minutes. At the end of the copper cleaning, the pulp was filtered. The yield of copper cake was 117% of the total mass of solid reagents, the content in cake,%: Ni - 4.6, Cu - 57.1, S total - 33.4, S elementary - 4.6. The residual copper content in the purified solution is 0.05 g / dm. In addition, the solution contained, g / dm ³ : iron - 1.5, cobalt - 1.8, zinc - 0.21 and lead - 0.009. The solution was cleaned of zinc and iron after preliminary oxidation of iron with chlorine was performed by extraction with trioctylamine, from cobalt and lead with chlorine and nickel carbonate with the conversion of cobalt to cobalt cake. The purified solution contained, g / dm ³ : nickel - 70, copper - 0.003, iron - 0.0008, cobalt - 0.010, zinc - 0.00038, lead - 0.00015 and by the content of impurities provided the possibility of electroextraction of high-quality nickel.

Example 7

Of 2 l containing 12 g / dm ³ purified from copper, zinc and iron solution obtained in an experiment similar to that of example 6, 58.0 g of magnesium hydroxide precipitated with sodium hydroxide solution. The resulting solution containing 60 g / dm ³ SO ₄ ^2- , 62 g / dm ³ Cl ^- , 71 g / dm ³ Na ⁺ , pH 9.0, was neutralized with sulfuric acid and evaporated 2.5 times. Sodium sulfate crystallized from one stripped off solution. From a mother liquor containing 230 g / dm sodium chloride, an alkali solution with a concentration of 400 g / dm ³ and chlorine was obtained by electrolysis in a membrane electrolyzer.

Claims (5)

1. A method of producing nickel from ore sulfide raw materials, including leaching with a chloride solution when oxygen and chlorine are supplied, precipitation of copper from the solution to obtain copper sulfide cake, purification of the solution from iron, zinc and cobalt, electroextraction of nickel and processing of waste with the recovery of chlorine and alkali, characterized in that the leaching is carried out in two stages with a countercurrent in solution, while only oxygen is supplied to the first stage, and only chlorine to the second. 2. The method according to claim 1, characterized in that the supply of chlorine is controlled by the magnitude of the redox potential, kept within 450-700 mV. 3. The method according to claim 1, characterized in that the oxygen leaching is carried out for 5-30 hours 4. The method according to claim 1, characterized in that the leach residue with the supply of chlorine is washed and non-ferrous metals and magnesium are precipitated from the washings, the precipitate is filtered off and returned to the leaching cycle, and the filtrate is returned to washing. 5. The method according to claim 4, characterized in that the non-ferrous metals and magnesium are precipitated with lime.

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