RU2245933C1 - Method for reprocessing of oxidized nickel-cobalt ore - Google Patents

Abstract

FIELD: cobalt and nickel recovery from ores.

SUBSTANCE: claimed method includes ore granulation with sulfuric acid at stoichiometric ratio. Granules are baked at 650-700⁰C for 2.5-3.0 h up to soluble iron content of 1.0-3.0 % followed by leaching with water. Before baking granules are sulfated at 200-250⁰C for 1 h.

EFFECT: high yield metal recovery; decreased sulfuric acid consumption; granulated sulfated product without decomposition during leaching with water.

3 cl, 3 tbl, 4 ex

Description

The invention relates to methods for the extraction of nickel and cobalt from ores and can be used in the processing of oxidized nickel and cobalt ores.

A known method of autoclave sulfuric acid leaching of oxidized ores [1]. According to this method, for example, at the Moa Bay plant, ore pulp containing 45% solid is heated with hot steam in the heating columns, and then leached in a chain of four steam lift autoclaves. Processing is carried out at a temperature of 240-250 ° C (pressure of about 4.0 MPa). The required sulfuric acid (98%) in an amount of about 240 kg / t of ore is fed into the first autoclave. Mixing in autoclaves is carried out with direct steam. Leaching time is 1-2 hours, while about 95% of nickel and cobalt passes into the solution. The disadvantages of the process are the high cost of equipment for autoclave leaching, the complexity of the operation of autoclaves.

Closest to the proposed technical solution is a method for the extraction of nickel and cobalt by leaching with sulfuric acid at atmospheric pressure of nickel lateritic ores with a high content of serpentine [2]. According to this method, at atmospheric pressure, nickel and cobalt are leached from finely ground ore pulped in water (ore content 15-33%) with sulfuric acid at a temperature of 80-100 ° C. The consumption of sulfuric acid is 80-100% by weight of dry ore. Duration of leaching is 1 hour. Seven ore samples with a content of 1.92-3.34% nickel and 0.02-0.18% cobalt were tested. Extraction into solution ranged for nickel in the range of 71-96%, for cobalt - 95-97%. Excess acid is neutralized with limestone to partially release iron. The disadvantages of the method are a significant excess consumption of acid, a wide range of fluctuations in the extraction of Nickel from various samples of ores and, in addition, the difficulty of separating finely ground leached ore from the stock solution.

The technical result of the proposed technical solution is to achieve a high degree of extraction of nickel and cobalt from oxidized ore, reduce the consumption of sulfuric acid and obtain a granular sulfated product that is not destroyed when it is leached with water.

The technical result is achieved by the fact that according to the proposed method, the oxidized ore is granulated with concentrated sulfuric acid, used in an amount stoichiometrically necessary for the reaction with metal oxides interacting with the acid contained in the ore, and the obtained granules are calcined in a tubular rotary kiln at a temperature of 650-750 ° C within 2.5-3.0 hours for the decomposition of the main part of iron (III) sulfate to a residual iron content in - granules (in the form of sulfate) of 1.0-3.9%. The sulfur oxides released in this process additionally sulfate the nickel and cobalt oxides. To increase the extraction of Nickel and cobalt before calcining, it is advisable to carry out the sulfatization of granules at a temperature of 200-250 ° C for 1 hour.

Nickel and cobalt are leached from calcined granules with a soluble iron content of 1.0-3.9% in amounts of up to 92-96 and 93-95%, respectively, and granule destruction does not occur, which greatly facilitates the separation of the solution from the solid leached residue.

Example 1 (prototype)

Sulfuric acid (in terms of 100%) in the amount of 0 was introduced into the aqueous pulp of the oxidized concentrate (with a content,%, 1.25 Ni; 0.44 Co; 17.9 Fe) with a ratio of T: W = 1: 3 , 92 t / t ore. Preliminary calculations showed that in order to convert to sulfates the metals contained in the ore (Ni, Co, Fe, Mg, etc.) by the stoichiometric ratio, it is necessary to spend 0.5-0.55 t / t of ore. Thus, the real acid consumption was 1.67-1.84 times higher than the stoichiometrically necessary.

Leaching was carried out at a temperature of 90 ° C for 1 hour. The solution is recovered,%, 37.9 Ni; 19.1 Co; 21.0 Fe.

Example 2

Oxidized nickel ore (example 1) was granulated with sulfuric acid at a flow rate of the last 0.49-0.59 t / t of ore. The granules were placed in a tubular rotary kiln heated to a temperature of 650 ° C and calcined for 3.5 hours. After calcination, the granules were leached with water at a ratio of T: W = 1: 3 for 3 hours. The experimental results are shown in table 1.

Table 1
The effect of consumption of H ₂ SO ₄ on the quality of the calcined granules Consumption of H ₂ SO ₄ , Recovery in solution,% Contents sol. Fe in granules,% Bead behavior when leached t / t Ni With Fe 0.59 84.0 95.0 38.4 5,6 collapsed 0.56 88.8 95.5 27.0 4.1 partially destroyed. 0.49 88.8 89.4 25.8 3.9 not collapsed

Thus, the high residual content (more than 3.9% Fe) of soluble iron sulfates in the granular calcined product leads to the destruction of granules during metal leaching

Example 3

Oxidized nickel ore (example 1) was granulated with sulfuric acid at a flow rate of 0.35-0.51 t / t ore and subjected to heat treatment in a muffle furnace in the following mode: heating to 200 ° C (0.5 h) - sulfatization at heating from 200 to 250 ° C (1 h) - calcination of granules when heating from 250 to 700 ° C (3.5 h). The obtained granules were leached with water at a ratio of T: W = 1: 3 for 3 hours. The experimental results are shown in table 2

As can be seen from the table, the extraction of Nickel in the solution at the same flow rate of sulfuric acid as in example 2 (0.49 t / t), increased to 92.8-96.0%. This result can only be explained by the introduction of an additional sulfatization operation at 200-250 ° C for 1 hour.

table 2
The effect of consumption of H ₂ SO ₄ on the extraction of metals with the introduction of an intermediate operation of sulfatization Consumption of H ₂ SO ₄ , t / t Recovery in solution,% Ni With Fe 0.35 68.8 74,4 0.5 0.48 92.8 90.7 12,2 0.51 96.0 93.0 18.8

Example 4

Oxidized nickel ore (example 1) was granulated with sulfuric acid at a flow rate of the last 0.47 t / t of ore. The obtained granules were calcined in a tubular rotary kiln for 2.3-3.0 hours at temperatures from 600 to 750 ° C, and then leached with water at a ratio of T: W = 1: 3 for 3 hours. The results of the experiments are shown in table 3.

Table 3
The results of the calcination of granules in a tubular rotary kiln Temperature ° C Recovery in solution,% The content of Fe solution in granules,% Leaching granules Ni With Fe 600 86.4 95.2 27.4 4.1 partially collapsed 650 95.2 93.0 23.8 3.6 collapsed slightly 700 92.0 95.3 6.4 1,0 not collapsed 750 2.2 4.6 0.1 0.004 not collapsed

Mixing the granules during their calcination in a tubular rotary kiln contributes to a more complete (cf. Tables 2 and 3) and faster decomposition of iron sulfate. The best results for the extraction of Nickel in the solution during leaching were obtained at a calcination temperature of 650 ° C. A further increase in temperature (up to 700 ° C) leads to a more complete decomposition of iron sulfate and, apparently, a partial screening of nickel compounds. As a result, there is a slight decrease in nickel recovery. Thus, to obtain granules that are not destroyed during the leaching process and, at the same time, high extraction of nickel and cobalt into solution, the residual soluble iron content in calcined granules (in the form of sulfate) should be 1.0-3.9%.

As can be seen from the above examples, when using the proposed method, up to 92-96% of nickel, up to 93-95% of cobalt are extracted into the solution as a result of leaching with a relatively low (6.4-25.8%) iron recovery. The obtained calcined granules are not destroyed during the leaching of metals.

The technical efficiency of the proposed method for processing oxidized nickel ore is that as a result of the use of granulation processes of oxidized nickel ore with sulfuric acid, solid-phase sulfatization of ore and calcination of granules, a good interaction of sulfuric acid and compounds of extracted valuable metals is ensured. The consumption of sulfuric acid is reduced to the stoichiometrically necessary for the reaction with metal oxides interacting with the acid contained in the ore. Calcination of granules allows not only to drastically reduce the amount of iron passing into the solution during leaching, but also to obtain granules that are not destroyed (when the soluble iron content in them is in the range of 1.0-3.9%) in the process of leaching of metals, which greatly facilitates the subsequent separation of salable solution from leached ore.

To carry out these processes, simple construction and much cheaper and easier to use equipment than autoclaves are used.

SOURCES OF INFORMATION

1. Reznik I.D., Ermakov G.P., Shneerson Y.M. Nickel. M.: Science and Technology LLC, 2001. V.2: Oxidized Nickel Ores.

2. Pat. 6379637 USA, IPC ⁷ C 22 V 23/00. Direct atmospheric leaching of highly-serpentinized saprolitic nickel laterite ores with sulphuric acid. / Curlook Walter, Curlook W. // Publ. 04/30/2002, NPK 423 / 150.4.

Claims (3)

1. A method of processing oxidized nickel-cobalt ore, comprising treating the ore with sulfuric acid to transfer soluble sulfates to a solution, characterized in that the ore is granulated with sulfuric acid in the stoichiometrically necessary amount, the granules are calcined at a temperature of 650-700 ° C for 2.5-3 , 0 h, followed by leaching with water. 2. The method according to claim 1, characterized in that the granules are calcined to a soluble iron content in them in the range of 1.0-3.9%. 3. The method according to claim 1, characterized in that the granules are sulphated before calcination at a temperature of 200-250 ° C for 1 hour