RU2202637C2 - Method to process oxidized nickel-cobalt ores - Google Patents

Abstract

FIELD: non- ferrous metallurgy. SUBSTANCE: method can find use in processing of nickel-cobalt ores and products of their beneficiation. Method includes reducing-magnetizing sintering of ore in atmosphere of live steam at temperature of 480-600 C with use of carbamide in the capacity of reducing agent or any other organic substance showing increased boiling temperature and containing no sulfur. Any known technology ( hydrometallurgy or electrostatic separation ) can be employed to recover nickel and cobalt from magnetic fraction. EFFECT: simplified technology, reduced energy consumption, improved ecological situation. 2 tbl

Description

 The invention relates to the field of non-ferrous metallurgy and can be used in the processing of oxidized nickel-cobalt ores and their products.

 All known oxidized nickel-cobalt ores are characterized by a complex, constantly changing composition. Nickel in them is either in the form of free oxide, or isomorphically replaces iron in laterite-type ores, or isomorphically replaces magnesium in ores of the silicate (non-nitron-serpentine) type. In both types of ores, cobalt is mainly confined to manganese compounds.

 There are many known methods for processing oxidized nickel-cobalt ores. All of them essentially boil down to finding the conditions and methods for the destruction of complex mineral formations, including nickel, with the transfer of the latter to a free phase state or elementary, or sulfide, or water-soluble.

 In practice, the most commonly used processing method is based on the sulfidation of nickel and cobalt with elemental sulfur (hydrosulfidation), pyrite or gypsum (pyrosulfidation).

 Oxidized nickel-cobalt ores of YuUNK, V-Ufaleysky NK (RF), plants of the USA, Canada, Sweden, etc. are processed using pyrosulfidation technology. , according to the hydrosulfidation technology, oxidized nickel-cobalt ores are processed by the plants of the company Shirit-Gordon and others. A number of plants use direct hydrometallurgical redistribution of ore subjected to reduction calcining. Usually, ammonia-carbonate or sulfuric acid leaching is used (plants of Cuba, N-Caledonia, etc.). Other enterprises (Canada, USA, etc.) prefer reduction smelting to ferronickel [1, 2, 3, 4].

 As a prototype of the proposed technical solution, the method of reductive sintering with the release of reduced iron, nickel, cobalt from the cooled sintered mass after grinding by magnetic separation [5] was adopted.

All known methods, including the prototype, have a number of serious drawbacks, the main of which are multi-stage separation processes, high energy and reagent intensity, recovery processes at high temperatures (significantly higher than 1000 ^o C), and sulfidation methods, especially pyrosulfidation contribute to environmental degradation in the area where enterprises operate.

 The objective of this technical solution was to find methods and reagents that allow to obtain in the sinter metals in an elementary state, and transfer iron oxide compounds into magnetite at temperatures significantly lower than the prototype.

In contrast to the prototype, the task is achieved by sintering the ore in an atmosphere of saturated steam at 430-620 ^o With the use of urea or other organic matter having a high boiling point and not containing sulfur as a reducing agent. The reducing agent is set in the charge at the stage of grinding ore. Grinding of ore is carried out in an alkaline medium pH 7.5-8.5, regulated by the task of a strong solution of caustic or soda ash. In this case, reactions occur, expressed for lateritic ores by equation 1 and silicate (serpentine) ores by equation 2.

9 (NiFe) O ₃ + 6CO (NH ₂ ) ₂ = 9Ni + 3Fe ₃ O ₄ + 3CO + 3CO ₂ + 12H ₂ O + 6N ₂ ; (1)
3 (NiOMgO) SiO ₂ + CO (NH ₂ ) ₂ = 3Ni + 3MgO + 3SiО ₂ + CO ₂ + 2H ₂ O + N ₂ ; (2)
Elemental nickel and cobalt are extracted from the cake by magnetic separation. Together with them, magnetite also passes into the magnetic fraction. Nickel and cobalt are extracted from the magnetic fraction by any of the known methods: by flotation, electrostatic separation or by hydrometallurgical method using various kinds of solvents, and the magnet remains mainly in an insoluble residue and can be used in the production of cast iron or steel.

The technology was developed at the oxidized nickel-cobalt ore of the Shalapskoye (Altai Territory) deposit. The ore sample averaged in proportion to the reserves had the composition,%:
SiO ₂ -37 S-0.01 Ni-1.00;
Al ₂ O ₃ -3.4 P ₂ O ₅ -0.2 Co-0.10;
MgO-6.7 Fe ₂ O ₃ -32 Cn-0.09;
CaO-1.2 FeO-0.39 Zn-0.94;
The research methodology was as follows. The ore was crushed to a particle size of 100% minus 0.25; 0.105; 0.075 mm. An appropriate ore sample was laden with one of the reducing agents dissolved in water to ensure a more complete contact. The mixture was placed in a porcelain tube, which was introduced into the tube furnace into a controlled temperature zone. During the heat treatment of the charge in the tube, a vapor-air medium was maintained by continuous injection of sharp steam into the tube. The material in the tube was mixed due to its continuous rotation at a speed of 5 rpm. After a predetermined time, the tube was removed from the furnace, cooled, and sintered out of it. The spec was disintegrated, and a magnetic fraction was released from it at a magnetic field of 3600 Oe.

 Nickel and cobalt were leached from the magnetic fraction with a solution of sulfuric acid at pH 1.5-2.5. The oxidizing potential of the solution was maintained in the range of 0.40-0.45 V by the sodium nitrite solution. Leaching was carried out in a flotation machine made of X18H9T steel. Nickel and cobalt were cemented from the solution with the Ira alloy. All products of the separation process were analyzed. The residual content in the solution of the sum of nickel and cobalt at the end of cementation was controlled, usually it did not exceed 1 mg / l, and was not taken into account when calculating the distribution.

 Example 1

 Initially, the influence of the size of the ore break and the boiling point was studied. At the same time, urea consumption was constant and amounted to 15 g per 1 kg of ore, i.e. 120% of the stoichiometric calculation for the reactions expressed by equations 1 and 2.

 The results of the experiments are presented in table 1.

 An analysis of the data in the table shows that the coarseness of the grinding, i.e. mechanical opening of recoverable ore components.

 Example 2

The effect of urea and additional dimethylformamide consumption was studied. Ore grinding 100% minus 0.1 mm, 1 kg sample, sintering temperature 540 ^o C.

 The results of the experiments are presented in table 2.

From the data of the table it follows that the consumption of urea should be at least 15 kg per 1 ton of ore, and the sintering time at 540 ^o With at least 30 minutes. Control experiments with dimethylformamide show that similar results can be obtained with a lower consumption of reducing agent. The use of dimethylformamide improves the recovery of cobalt.

Sources of information
1. V.I.Smirnov, A.A. Zeidler, I.F. Khudyakov, A.I. Tikhonov. Metallurgy of copper, nickel and cobalt, M .: Metallurgy, 1966 (39-129).

 2. NN Sevryukov, B. A. Kuzmin, E. V. Chelishchev. General metallurgy, M .: Metallurgy, 1976, 153-163; 176-178.

 3. Metallurgy of copper, nickel and cobalt. Sat international conference, editor A.A. Zeidler, M .: Metallurgy, 1965, 292-323.

 4. I.F. Khudyakov, A.I. Tikhonov, V.I. Deev, S.S. Naboychenko. Metallurgy of nickel and cobalt. - M.: Metallurgy, 1977, 196-200.

 5. L.I. Pimenov, V.I. Mikhailov. Processing of oxidized nickel ores. - M.: Metallurgy, 1972, 64-92.

 6. MLPolyakov, A.V. Filatov and others. "Method of hydrometallurgical processing of materials containing nickel, copper, iron, cobalt and sulfur." Copyright certificate 747141, 03/14/80.

Claims (1)

A method of processing oxidized nickel-cobalt ores, including reductive sintering and magnetic enrichment of the obtained cake with the conversion of nickel and cobalt into a magnetic fraction, characterized in that reductive sintering is carried out in a sharp steam medium at 480-600 ^o C using urea or another as a reducing agent organic matter with a high boiling point and not containing sulfur and nickel and cobalt are extracted from the magnetic fraction by the hydrometallurgical method or electrostatic separation s.

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