RU2245934C1 - Method for reprocessing of oxidized nickel-cobalt ore - Google Patents

Abstract

FIELD: reprocessing of oxidized ore by sulfating.

SUBSTANCE: claimed method includes raw treatment with sulfuric acid, transfer of soluble sulfates into solution and roasted product leaching. Batch is baked in gas medium obtained by oxidizing of elementary sulfur of sulfides with air oxygen. Then gases are recycled into sulfuric acid production. Sulfur oxides released during batch baking are utilized together with sulfur oxidation products charged in oven.

EFFECT: prevention of sulfur oxides losses; cobalt and nickel recovery with high yield; reduced fuel consumption.

1 tbl, 3 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 by sulfatization.

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 the significant consumption of acid, a wide range of fluctuations in the extraction of nickel from various ore samples, as well as the inability to utilize excess acid.

The technical result of the proposed solution is to achieve a high degree of extraction of nickel and cobalt from oxidized nickel-cobalt ore and to prevent the loss of sulfur oxides during its processing.

The technical result is achieved by the fact that according to the proposed method, the oxidized nickel-cobalt ore is granulated with sulfuric acid and the granules are calcined in the atmosphere of gases obtained during the oxidation of elemental sulfur or sulfides with atmospheric oxygen, after which these gases, together with sulfur oxides released during the calcination of the granules, are sent to production sulfuric acid, used in the head of the process, and granules - for leaching with water.

Example 1 (prototype)

Sulfuric acid (in terms of 100%) was added to the aqueous pulp of oxidized nickel-cobalt ore (with a content,%, 1.25 Ni; 0.44 Co; 17.9 Fe) with a ratio of T: W = 1: 3 (in terms of 100%) 0.92 t / t ore. Preliminary calculations showed that in order to convert to sulfates the metals contained in the ore (Ni, Co, Fe, Mg, etc.) in terms of the stoichiometric ratio, it is necessary to expend 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

The oxidized nickel-cobalt ore (Example 1) was granulated with sulfuric acid at a flow rate of 0.47 t / t of ore. The granules were calcined in a tubular rotary kiln at a temperature of flue gases of 750 ° C for 3.0 hours. After calcination, the granules were leached with water at a ratio of T: W = 1: 3 for 3 hours. The solution is recovered,%: 91.3 Ni; 95.0 Co; 25.8 Fe

The exhaust gases resulting from the decomposition during calcination of iron (III) sulfate, formed during the interaction of sulfuric acid with iron oxide, and evaporation from granules of free sulfuric acid contained up to 0.16% (vol.) Sulfur oxides.

Thus, the heat treatment of the granular product leads to a sharp increase in the extraction of Nickel and cobalt during leaching of the cinder. However, sulfur oxides passing into the gas phase cannot practically be disposed of because of their low concentration, but they must be neutralized.

Example 3

The oxidized ore (Example 1) was granulated with sulfuric acid at a flow rate of 0.49 t / t ore. The granules were placed in an oven and calcined at temperatures of 650-700 ° C for 3.0 hours in a gas atmosphere containing 10% sulfur dioxide obtained by burning elemental sulfur (650 ° C) or iron sulfide (700 ° C). Sulfur oxides released during the calcination of granules are combined with the dioxide supplied to the furnace and used to produce sulfuric acid.

After calcination, the granules were leached with water at a ratio of T: W = 1: 3 for 3 hours. The results obtained by leaching metals are shown in table 1. From a comparison of the results given in examples 2-3, it is seen that the presence of sulfur dioxide in the gas atmosphere leads to a slight increase in the extraction of nickel in the solution.

Table 1
The results of the calcination of granules in an atmosphere of SO ₂ Temperature ° C Recovery in solution,% Ni With Fe 650 91.4 95.5 27.0 700 93.2 95.0 24.8

Thermotechnical calculations showed that the heat released during the oxidation of air by the amount of sulfur, which is ultimately used to produce the sulfuric acid needed in the granulation process, is enough to carry out the process of calcining the granules. This allows you to replace expensive hydrocarbon fuels.

The technical efficiency of the proposed method for processing oxidized nickel-cobalt ore is that as a result of applying the process of granulation of ore with sulfuric acid and calcining the granules in the atmosphere of gases obtained by burning sulfur or sulfides:

- the heat of the above gases is effectively used, which eliminates the burning of carbon fuel,

- the amount of equipment used in the technology is reduced (instead of the furnaces and gas purification systems specially mounted for the calcining furnace, a sulfur or sulfide burning furnace and gas treatment of a sulfuric acid plant are used),

- gaseous decomposition products of iron sulfate are utilized.

SOURCES OF INFORMATION

1. Reznik I.D., Ermakov G.P., Shneerson Y.M. Nickel. M .: Nauka i Tekhnologii LLC, 2001. Vol. 2: Oxidized nickel ores.

2. Pat. U.S. 6379637, IPC ⁷ C 22 B 23/00. Direct atmospheric leaching of highly-serpentinized saprolitic nickel laterite ores with sulphuric acid. / Curlook Walter, Curlook W. // Publ. 04/30/02, NPK 423 / 150.4.

Claims (1)

A method of processing nickel-cobalt oxidized 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, the granules are calcined in an atmosphere of gases obtained from the oxidation of elemental sulfur or sulfides with atmospheric oxygen, then the gases are liberated with calcining the granules with sulfur oxides is sent to the production of sulfuric acid, and the granules are leached with water.