RU2319756C2 - Method used for extraction of lithium from the mixture of lithium concentrates - Google Patents

Abstract

FIELD: metallurgy industry; other industries; methods of reprocessing of the spodumene and lepidolite concentrates.

SUBSTANCE: invention is pertaining to metallurgy, in particular, to reprocessing of the spodumene and lepidolite concentrates. Method of extraction of lithium from the mixture of the lithium concentrates includes preparation of the charge from the spodumene and lepidolite concentrates, activating preparation of the charge and the water leaching. At that the charge is prepared from the mixture with the purpose to obtain the mass ratio of the spodumene and lepidolite concentrates in their mixture equal 2.5÷99.0. Activating preparation of the charge is conducted by means of mechanical activation with production of the X-ray-amorphous product of coarseness of less than 45 microns. Before the water leaching the X-ray-amorphous product is depulped in the water and added with the sulfuric acid for formation of the water-soluble lithium sulfate. The technical result of the invention is the high degree of extraction of lithium into the water solution without usage of fluxes.

EFFECT: invention ensures the high degree of extraction of lithium into the water solution without usage of fluxes.

1 tbl, 6 ex

Description

The invention relates to metallurgy, in particular to the processing of spodumene and lepidolite concentrates.

Sodumene (LiAl ₂ [Si ₂ O ₆ ]), lepidolite (KLi _1,5 Al _1,5 [Si ₃ AlO ₁₀ ] [F, OH] ₂ ) and amblygonite (LiAl [PO ₄ ] [F, OH] ₂ ) - one of the main industrial lithium minerals [1, pp. 12-18, 20, 28-31, 90]. In mining and processing industries, these minerals are extracted from ores into appropriate concentrates. Lithium concentrates are characterized by a low lithium content (not more than ~ 4% wt. [1, p. 92]). For this reason, the known methods for the extraction of lithium from these concentrates are technically difficult to implement and very expensive.

To extract lithium from its minerals, a large number of known methods can be used: sulfuric acid, sulfate, lime, and others [1, pp. 121-157; 2, pp. 226-272]. The bulk of the known methods for the extraction of lithium from lithium concentrates is designed to process only individual lithium minerals, which significantly narrows the raw material base of lithium industries. The number of known methods for co-processing lithium concentrates is currently limited.

A known method of extracting lithium from a mixture of spodumene and amblygonite concentrates, adopted as an analogue [2, p.243-249] and including: 1) mixing spodumene concentrate with limestone (in a mass ratio of 1: 3) and adding to the resulting mixture of amblygonite concentrate in an amount 10 ÷ 40% wt .; 2) the activating preparation of a mixture composed of concentrates and limestone by sintering it at a temperature of 800 ÷ 950 ° C, followed by grinding the custody; 3) water leaching of the activated mixture (ground cake).

Sintering a mixture of concentrates with alkaline earth flux - limestone, alkaline decomposition of spodumene and amblygonite is achieved and water-insoluble lithium aluminate (Li ₂ O · Al ₂ O ₃ ) and calcium silicate (2CaO · SiO ₂ ) are formed. However, due to the excess of limestone supplied to the stage of sintering with concentrates, during the leaching of the crushed cake, water-soluble lithium hydroxide and water-insoluble calcium aluminate are formed:

After separation of the pulp from the stage of leaching the crushed custard into a solution of lithium hydroxide and cake (precipitate of gross composition 2CaO · SiO ₂ + CaO-Al ₂ O ₃ ), water washing the cake from lithium hydroxide, the cake is dumped. The use in the analogue method of significant amounts of limestone at the stage of its blending with concentrates (115 ÷ 214% of the total mass of concentrates) leads to an extremely poor raw material charge (~ 1% wt. Lithium or less) in lithium content, which leads to high costs for the extraction of lithium from this charge, the formation of a large mass of dump cake (washing of which from lithium hydroxide is a difficult task), as a result of which significant amounts of lithium are lost with the cake, so that the extraction of lithium from a mixture of concentrates in solution is only 80 ÷ 90% wt.

The disadvantages of the analogue method of processing a mixture of spodumene and amblygonite concentrates are the low extraction of lithium from the mixture of concentrates into the solution, the need to use flux (limestone) in significant quantities, which leads to the formation of a large volume of a lithium-rich raw material charge and the high cost of extracting lithium from it, the formation of a large amount of dump cake, for the washing of which from lithium hydroxide and subsequent disposal in special expensive dump fields, I have high costs.

The closest set of features to the proposed method is a method for extracting lithium from a mixture of lepidolite and spodumene concentrates [2, pp. 243-249], adopted as a prototype and including: 1) mixing spodumene concentrate with limestone (in a mass ratio of 1: 3) and adding to the resulting mixture of lepidolite concentrate in an amount of 10 g 40% wt .; 2) activating preparation of a mixture composed of concentrates and limestone by sintering it at a temperature of 900-950 ° C followed by grinding of cake; 3) water leaching of the activated mixture (ground cake).

As a result of sintering a mixture of concentrates with alkaline earth flux - limestone, alkaline decomposition of lepidolite and spodumene occurs and water-insoluble lithium aluminate and calcium silicate are formed. However, due to the excess of limestone supplied to the stage of sintering with concentrates, during the leaching of the crushed cake, water-soluble lithium hydroxide and water-insoluble calcium aluminate are formed [see reaction equation (1)]. After separation of the pulp from the stage of leaching the ground cake to a solution of lithium hydroxide and Al-, Ca-, silicon-containing cake, water washing the cake from an alkaline solution, the cake is dumped into a dump. The use in the prototype method of significant amounts of limestone at the stage of its blending with concentrates (115 ÷ 214% of the total mass of concentrates) leads to an extremely poor raw material charge (~ 1% wt. Lithium and less) in lithium content, which leads to high costs the extraction of lithium from this charge, the formation of a large mass of dump cake (washing of which from lithium hydroxide is a difficult task), as a result of which significant amounts of lithium are lost with the cake, so that the extraction of lithium from a mixture of concentrates in solution is it is only 80 ÷ 84% wt.

The disadvantages of the prototype method of processing a mixture of lepidolite and spodumene concentrates are the low extraction of lithium from the mixture of concentrates into the solution, the need to use flux (limestone) in significant quantities, which leads to a large amount of raw material charge poor in lithium content and the high cost of lithium extraction from it, formation a large amount of dump cake, the washing of which from lithium hydroxide and subsequent disposal in special expensive dump fields requires high rats.

The problem to which the invention is directed is to develop a method for the joint processing of lepidolite and spodumene concentrates, providing high lithium extraction from a mixture of these concentrates into a solution without using flux, while reducing the mass of the initial charge and the cost of extracting lithium from it, with small volumes of dump cake, low costs for washing cake from a lithium-containing solution and disposal of cake in special dump fields.

The essence of the proposed method for the extraction of lithium from a mixture of lithium concentrates is that, in contrast to the known method for the extraction of lithium from a mixture of lithium concentrates, including the preparation of a mixture from lepidolite and spodumene concentrates, activating the preparation of a mixture, water leaching of an activated mixture, according to the claimed invention, preparation of a mixture perform from a mixture of concentrates based on obtaining a mass ratio of lepidolite and spodumene concentrates in their mixture equal to 2.5 ÷ 99.0, Activate batch preparation is carried out by mechanical activation to obtain X-ray amorphous product size less than 45 microns, prior to aqueous leaching raspulpovyvayut x-ray amorphous product in water and added sulfuric acid to form a water-soluble lithium sulfate.

The solution of this problem and the achievement of the corresponding technical results is ensured by the fact that in the known method of extracting lithium from a mixture of lepidolite and spodumene concentrates, including the charge of the mixture with flux, activating the preparation of the concentrate and flux mixture and water leaching of the activated mixture, according to the claimed invention, the preparation of the charge is performed mixtures of lepidolite and spodumene concentrates without the use of flux based on the calculation of the mass ratio of lepidolite of the second and spodumene concentrates in their mixture equal to 2.5–99.0, the activating preparation of the charge is carried out by mechanically activating it to obtain an X-ray amorphous product with a particle size of less than 45 μm, before the water leaching, the X-ray amorphous product is pulped in water and sulfuric acid is added to form water-soluble lithium sulfate . As a result of grinding the mixture of lepidolite and spodumene concentrates, the crystal lattices are destroyed and the specific surface of lepidolite and spodumene increase, i.e. mechanical activation of these minerals, which increases their chemical activity and provides the possibility of deep opening of lithium minerals activated in this way with sulfuric acid leaching of a mechanically activated concentrate mixture with sulfuric acid to form water-soluble lithium sulfate and insoluble silica. Since the inventive method does not use flux, the total mass of the raw material charge is significantly less compared to the mass of the raw material charge compiled by the prototype method, which reduces the cost of processing raw materials with lithium extracted into the solution, the weight of the dump cake, the cost of washing the cake from lithium-containing solution and the cost of burying cake in special dump fields.

The method is carried out on conventional equipment using lepidolite and spodumene concentrates with lithium content of 2, 29 and 3.28%, respectively. For the implementation of the proposed method prepare mixtures consisting of lepidolite and spodumene concentrates with different mass ratios of concentrates. The prepared mixture is ground in a planetary mill to obtain an X-ray amorphous product with a particle size of 45 microns. Mechanically activated mixtures are pulped in water at a ratio of T: W = 1: 0.8. In the resulting pulp add 93% sulfuric acid at the rate of 0.6 ÷ 0.8 ml per 1 g of mechanically activated mixture. The sulfates formed are leached with water at T: W = 1: 5 (according to a mechanically activated mixture), at a temperature of 95 ° C for 2 ± 1 h. The resulting sulfate pulp is filtered, the filtered cake is subjected to 2-fold filter-repulpation washing with water acidified with sulfuric acid to pH 3.0 ÷ 3.5, at T: W = 1: (5 ÷ 6) (mechanically activated mixture) and a temperature of 70 ° C for 15 minutes. The residual lithium content in the cake determines the completeness of the extraction of lithium from the concentrate into the solution.

The table shows the results of the implementation of the method according to the claimed invention and for comparison, according to the prototype method (symbols used in table 1: LC - lepidolite concentrate, SC - spodumene concentrate).

From the data presented in the table, it follows that when implementing the proposed method (examples 2-5), the extraction of lithium is 86 ÷ 99% wt. In these examples, mixtures of lepidolite and spodumene concentrates are calculated on the basis of obtaining the mass ratio of concentrates in these mixtures equal to 2.5–99.0, and limestone is not used in the process of activation of mixtures. A decrease in the mass ratio of lepidolite and spodumene concentrates in their mixtures below 2.5 (to 1.3; Example 1, table) leads to a decrease in lithium extraction into solution to 82% wt.

Comparative indicators of the process of extracting lithium from mixtures of lithium concentrates according to the claimed method and the prototype method Example No. Implementation Method The mass ratio of SC / LC in their mixture Add CaCO ₃ to the mixture of concentrates,% wt. The mass of the mixture (the amount of Li in it), g The mass of the mechanically activated mixture (cake), g Weight of dump cake, g The amount of Li in dump cake, g Extraction of Li in solution (cake),% wt. one
2
3
four
5
6
7
8 The inventive method
Way-
prototype 1.0 / 1.3
1,0 / 2,5
1.0 / 6.0
1.0 / 10.0
1.0 / 99.0
1.0 / 120.0
1.0 / 1.6
1.0 / 0.4 0
0
0
0
0
0
115
214 36.7 (1)
38.9 (1)
41.1 (1)
42.0 (1)
43.5 (1)
44.1 (1)
80.3 (1)
104.7 (1) 36.7
38.9
41.1
42.0
43.5
44.1
(65.1)
(80.5) 25.7
26.8
26.7
27.7
27.1
27.8
48.3
70.5 0.18
0.14
0,07
0.04
0.01
0.01
0.16
0.20 82.0
86.0
93.0
96.0
99.0
99.0
84.0
80.0

An increase in the mass ratio of lepidolite and spodumene concentrates in their mixtures above 99 (up to 120; Example 6, table) does not affect the completeness of lithium extraction into the solution.

For comparison with the claimed invention, the table presents the results of the extraction of lithium from mixtures of lepidolite and spodumene concentrates according to the prototype method (examples 7 and 8), in which the extraction of lithium in solution is only 80 ÷ 84% wt.

Thus, the inventive method allows you to effectively extract lithium from a mixture of lithium concentrates. Compared with the prototype method, the inventive method provides (table):

1) increase the extraction of lithium in solution from 80 ÷ 84 to 86-99% wt .: 2) the exclusion of the use of flux - limestone; 3) an almost twofold reduction in the mass of the initial raw material charge with a corresponding reduction in the costs of its processing with the extraction of lithium into solution; 4) an almost twofold decrease in the mass of the dump cake with a corresponding reduction in the cost of washing the cake from the lithium-containing solution and the disposal of cake in special dump fields.

Information sources

1. Ostroushko Yu.I., Buchihin P.I., Alekseeva V.V. et al. Lithium, its chemistry and technology. - M .: Atomizdat, 1960 .-- 200 p.

2. Plyushchev V.E., Stepin B.D. Chemistry and technology of compounds of lithium, rubidium and cesium. - M .: Chemistry, 1970 .-- 408 p.

Claims (1)

A method of extracting lithium from a mixture of lithium concentrates, including the preparation of a mixture of lepidolite and spodumene concentrates, activating the preparation of a mixture and water leaching, characterized in that the preparation of a mixture is performed from a mixture based on the calculation of the mass ratio of lepidolite and spodumene concentrates in their mixture equal to 2.5 ÷ 99.0, activating the preparation of the mixture is carried out by mechanical activation to obtain an X-ray amorphous product with a particle size of less than 45 microns, before water leaching, the X-ray amorphous odukt raspulpovyvayut in water and added sulfuric acid to form a water-soluble lithium sulfate.