WO2007117169A1 - Method for processing oxidised nickel-cobalt ore - Google Patents

Abstract

The invention relates to methods for extracting nickel and cobalt from ores and can be used for processing oxidised nickel and cobalt ores. The inventive method makes it possible to reduce the iron content in a produced nickel-cobalt concentrate and to minimise nickel and cobalt losses with iron sediment. Said method for processing oxidised nickel-cobalt ore consists in mixing the ore with sulphuric acid using a granulating device, sulphating and annealing the thus obtained granules and in leaching nickel and cobalt from the annealed granules. The method also consists in neutralising the obtained metal sulphate-containing solution in such a way that pH ranging from 3.0 to 5-5 is attained, sorbing nickel and cobalt from the produced pulp on ionite and in processing the metal-saturated ionite for obtaining a nickel-cobalt concentrate.

Description

 Method for processing oxidized nickel-cobalt ore

FIELD OF TECHNOLOGY

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

BACKGROUND

There is a method of autoclave sulfuric acid leaching of nickel and cobalt from oxidized ores [Reznik ID,

Ermakov G.L., Schneerson, Y.M. Nickel. M .: Hayka and Technology LLC, 2001. T.2: Oxidized Nickel Ores, pp. 385-388].

According to this method, for example, at the Moa Bay plant, pulp containing 45% of ore is heated with hot steam in heating columns, and then leached in a chain of four vapor lift autoclaves. Processing is carried out at a temperature of 240-25O ⁰ C (pressure of about 4.0 MPa). Essential Sulfuric Acid

(98%) in an amount of about 240 kg / t ore is fed to 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.

There is also known a method for the extraction of nickel and cobalt from laterite ores - as a result of mixing them with sulfuric acid, heat treatment of the mixture and subsequent leaching of metals from the cinder [Zubruskuj N., Evapi DJI, Maskiw VN Refreptiul sulfatiopelpolitpolitpolitpolitpoltpoltpoltpoltpoltpoltpoltpoltpolta Of Metals. 1965. Mau. P.478-486]. According to this method, crushed ore to - 0.15 mm is pulped in water to obtain pulp with content of about 60% solid material. Then the pulp is mixed for 15 minutes with a predetermined amount of concentrated sulfuric acid. The resulting paste is dried at a temperature above HO ⁰ C, the dried paste is crushed to a particle size of 4.7-1.65 mm, calcined at a temperature of up to 700-750 ⁰ C, sulfates are leached from the calcine and precipitated from a solution of nickel and cobalt sulfides. Ore samples with a content of 1.20-2.27% nickel and 0.03-0.26% cobalt were tested. An extraction of 85% nickel and 90% cobalt was obtained. The disadvantages of the method are the difficulty of preparing a mixture of ore with sulfuric acid for calcination (pulp ore in water, drying an acid paste, crushing the dried paste with a significant yield of product of substandard size), two thermal operations (drying and calcination) and, accordingly, an increase in the number of equipment, relatively low extraction of Nickel from rich oxidized ores, use for the deposition of metals from solutions of leaching of toxic hydrogen sulfide.

Closest to the proposed method is the processing of oxidized nickel-cobalt ore, according to which the ore is granulated with sulfuric acid, soluble sulfates are transferred into solution, the obtained granules are sulfated at a temperature of 200-250 ⁰ C and then calcined at a temperature of 650-700 ⁰ C, from calcined the granules were leached with water nickel and cobalt (RF patent JY22245933, publ. 02/10/2005). The method provides a high degree of extraction of nickel and cobalt from oxidized ore into the solution, but does not provide for a high degree of extraction of nickel and cobalt in commercial products. SUMMARY OF THE INVENTION

The technical result of the proposed method is to ensure a high degree of extraction of Nickel and cobalt in commercial products. The technical result is achieved by the fact that according to the proposed method, the oxidized ore is dried, crushed and mixed in a granulator with sulfuric acid, the granules obtained are subsequently sulphated first and then calcined in a single stage in a counter-rotating tube furnace, nickel is leached from the calcined product with water and cobalt, after neutralization of the solution and precipitation of iron and aluminum, nickel and cobalt are sorbed on the ion exchanger and the metal-saturated ion exchanger is processed to produce nickel cobalt th concentrate. The solution is neutralized to a pH optimum for ion exchange in the range of 3.0-5.5 and sorbed nickel and cobalt from the resulting pulp.

EXAMPLE OF PREFERRED EMBODIMENTS OF THE INVENTION Example 1

Oxidized nickel ore with a nickel content of 0.70 and

1.25% was dried, crushed to a particle size of 100% -0.15 mm and mixed on a bowl granulator with sulfuric acid at a flow rate of 0.47-0.52 t / t ore. Successively, sulfatization and calcination operations were carried out by placing samples of the granulated mixture in a muffle furnace at room temperature and heating it to a predetermined value within 650-800 ⁰ C. The heat treatment time was 4.5 hours. Calcined product was leached with water for 1 hour at a temperature of 70 ⁰ C and T: W = 1: 1, the operation was repeated 3 times, after each solution was separated, after the last leaching, the granules were washed with water. The combined solution was analyzed. The data obtained are given in table 1.

As can be seen from Table l, for these processing parameters and maximum calcination temperatures of 700–750 ^° C, the same high nickel recovery in solution was achieved for the two samples tested. Example 2

Oxidized nickel ore with a content,%, 1.25 Ni; 0.44

Co; 17.9 Fe was mixed in a bowl granulator with sulfuric acid at a flow rate of 0.47 t / t ore. The obtained granules were processed in a tubular rotary kiln for 3.5 hours, and then leached with water at a ratio of T: W = 1: 1 three times for 1 hour, the solutions were combined and analyzed. The results of the experiments are shown in table 2.

In this example, the best results for the extraction of nickel into the solution by leaching were obtained at a calcination temperature of 65O ⁰ C. A further increase in temperature (up to 700 ⁰ C) leads to a more complete decomposition of iron sulfate and, apparently, partial screening of nickel compounds. As a result, there is a slight decrease in nickel extraction, however, a decrease in the amount of iron passing into the solution during leaching of nickel and cobalt leads to granules more resistant to destruction during leaching of nickel and cobalt. Before sorption of nickel and cobalt from sulfuric acid solutions, the iron contained in the solution must be precipitated. To do this, you can neutralize the solution, for example, with limestone or calcium oxide. Experimental data show that the effectiveness of the indicated reagents has a significant difference (Table 3), which manifests itself in varying degrees of coprecipitation with nickel iron (5.3 and 9.4%, respectively) and aluminum (96.4 and 99.5%) .

With an increase in pH above 3.5, the amount of metals passing into the precipitate increases both due to their coprecipitation with iron and due to the achievement of the pH of intrinsic precipitation. For example, when iron is precipitated from the initial solution given in Table 3 by neutralizing it with calcium oxide to pH 5, the iron content in the solution decreases to 0.38; nickel - up to 1.38 (i.e. 18.8%); aluminum - up to 0.006 g / dm ³ .

The use of the process of sorption of these metals from the pulp allows minimizing the losses of nickel and cobalt with the iron precipitate, for which the pulp obtained after neutralization at constant pH and temperature is contacted with the ion exchanger in countercurrent mode. As ion exchangers, it is proposed to use pyridine hydroxyl ion exchangers, for example, HSV, or ion exchangers containing pyridinium nitrogen, for example, DO WEX XWS 4195 from DOW Chemical.

After sorption extraction of nickel and cobalt from the sulfate solution, the metal-saturated ion exchanger is washed with water and treated at 40-45 ^° C with an aqueous solution of a mineral acid (sulfuric, hydrochloric) with a concentration of not more than Zn. The obtained concentrated nickel-cobalt solutions are directed to the precipitation of carbonates or hydroxides.

Example 3 Sorption of Nickel and cobalt from neutralized pulp with pH = 5.0-5.5 was carried out with mechanical stirring, T: W = 1: 5, loading HSV in H ⁺ ZSO ₄ ^{2 "} in the form of 30% by volume of pulp. Obtained the results are given in table 4.

Thus, in the presence of ion exchanger recovery from pulp (liquid and solid phases) amounted to 97.6% nickel and 99.2% cobalt.

Similar results for the extraction of nickel and cobalt from neutralized pulp were obtained using ion exchanger.

UP TO WEX XWS 4195 from DOW Chemical. However, in this case, the process is carried out at a lower pH = 3.0-3.5, which reduces the consumption of the catalyst (CaCO ₃ ) by 10-12%.

The capacity of ion exchangers for nickel is, mg / g: HSV - 48.2; SUV XWS 4195 - 83.9.

The treatment of ion exchangers saturated with nickel and cobalt with aqueous solutions of mineral acids, for example sulfuric, allows the metals to be concentrated in the form of a sulfate solution suitable for producing carbonate concentrate in a known manner. The completeness of the desorption of nickel and cobalt and the degree of their concentration depend on the acid concentration and the process temperature. Example 4

A solution of sulfuric acid treated ion exchange resin saturated with Nickel and cobalt under the conditions specified in example 3. metal desorption was carried out under dynamic conditions, the volume of commodity desorbate was 1.7-2.0 volume to the volume of ion exchanger.

The highest degree of desorption (99%) was achieved with a concentration of sulfuric acid in a desorbing solution of 100-120 g / dm ³ and a temperature of 40-45 ⁰ C. The nickel concentration in the commodity desorbate was 8-10 g / dm ³ for HSV and 15-16 g / dm ³ for DO WEX

XWS 4195.

Carbonate concentrate precipitated from commercial desorbates

15% solution of soda ash at a temperature of 70-8O ⁰ C. The resulting concentrate was filtered, washed and dried. Based on the weight of the dry product, it contained,%: 38-45

Ni; 0.08-0.1 Co; 2.0-2.8 Fe; 1.0-1.1 Al; 0.4-0.5 Mg.

The technical efficiency of the proposed method for processing oxidized nickel ore is that as a result of using processes of mixing oxidized nickel ore with sulfuric acid in a granulator, solid-phase sulfatization of ore and calcining of granules, a good interaction of sulfuric acid and compounds of extracted valuable metals is ensured. Calcination of granules can drastically reduce the amount of iron passing into the solution during leaching. In turn, the sorption extraction of nickel and cobalt from pulps ensures the production of high-quality nickel-cobalt concentrate and minimizes the loss of these metals from the precipitation of iron hydroxide. Table 1 Effect of ore calcination temperature on metal recovery

Table 2 The results of the sequential leaching of granules

Таблица 3

Table 3

Precipitation of iron hydroxide pH of solutions after precipitation - 3.5-3.7

Table 4

исходная пульпа

source pulp

Claims

Claim 1. A method for processing oxidized nickel-cobalt ore, namely, that the ore is mixed with sulfuric acid using a granulator, the granules obtained are sulfated and calcined, and nickel and cobalt are leached out of calcined granules, characterized in that the solution containing metal sulfates obtained after leaching is they are neutralized to a pH in the range of 3.0-5.5, nickel and cobalt are adsorbed from the resulting pulp onto the ion exchange resin and the metal-saturated ion exchange resin is treated to obtain a nickel-cobalt concentrate.