RU2299254C1 - Method of vanadium extraction out of the highly concentrated lime slag - Google Patents

Abstract

FIELD: non-ferrous metallurgy; methods of extraction of vanadium out of the highly concentrated lime slag.

SUBSTANCE: the invention is pertaining to the field of non-ferrous metallurgy, in particular, to vanadium metallurgy, namely to the method of extraction of vanadium out of the highly concentrated lime slag providing for the wet milling of the highly concentrated lime slag with production of the pulp, treatment of the slag pulp with the sulfuric acid and its oxidizing burning, the sulfuric-acidic leaching of the burning product with the subsequent settling of vanadium from solution by hydrolysis. The technical result of the invention is the increased output of the extracted vanadium as the commercial product, and also improvement of the production process indices at reprocessing of the highly concentrated lime slag. For gaining the technical result the milled slag pulp is treated with the concentrated sulfuric acid taken in the amount of 30-35 % to the mass of the slag. The oxidizing burning is conducted at the temperature of 700-950°C. The product of the burning is subjected to leaching in the weak-acid solution of the sulfuric acid and conduct vanadium settling from the produced solution.

EFFECT: the invention ensures the increased output of the extracted vanadium as the commercial product, the improved production process indices at reprocessing of the highly concentrated lime slag.

1 tbl, 8 ex

Description

The invention relates to the metallurgy of rare metals and can be used in the technology of extracting vanadium from vanadium-containing raw materials and primarily from high-lime slag from purging or converting vanadium cast iron to steel by a monoprocess.

High-lime slag contains 35-50% CaO and 7-15% V ₂ O ₅ . The high calcium content makes it difficult to process this type of slag by existing methods.

There is a method of extracting vanadium from highly lime slag of steelmaking (in%: 5.7 V ₂ O ₅ , 47.0 CaO, 2.5 MgO, 11.0 SiO ₂ , 3.2 P ₂ O ₅ , 4.1 MnO, 15.1 Fe _total , 1.2 Al ₂ O ₃ ), including oxidative calcination with a pyrite concentrate in an atmosphere rich in SO ₂ and O ₂ [Wilkomiraky IAE, Luraschi A., Reghessa A. Method for extracting vanadium from steel slag. - Extraction metallurgy '85. The Institution of Mining and Metallurgy. London 1985, p.531-549 (Expressinformation: Production of rare metals and semiconductor materials. Foreign experience. - M.: TSNIITSVETMET of Economics and Information, Giredmet, 1986. Issue 19, p.1-2)]. Through vanadium recovery from slag is about 80%. The process is multi-stage and very lengthy, it is associated with large material flows both at the stage of firing and at the stage of hydrometallurgical redistribution, and the need to clean large volumes of firing gases from SO ₂ , etc.

A known method of processing high-calcium vanadium-containing materials [UK Patent No. 1474152, C22B 34/22; 16/20, publ. 05/18/1977], according to which the slag after grinding is treated with hydrochloric acid with complete conversion of calcium to a solution, the solution is separated from the residue by filtration, and then the vanadium is recovered from the residue by treating it with a NaOH solution in the presence of gaseous chlorine or other oxidizing agents. The disadvantages of the method are: a low degree of extraction of vanadium from slags, low quality of vanadium pentoxide, the use of environmentally hazardous reagents, especially chlorine, the formation of calcium chloride solutions in a large volume of calcium chloride solutions requiring further disposal, and poor pulp filtration after hydrochloric acid treatment due to the release of free silicic acid during the decomposition of calcium silicates.

In another known method of processing high-calcium vanadium-containing materials [RF Patent No. 2147620. C22B 34/22, 3/06, C01G 31/02, publ. 04/20/2000 Bull. No. 11] initially slag (7-13% V ₂ O ₅ , 30-40% CaO, 7-12% SiO ₂ , 14-25% Fe _total , 4-6% MnO, 3-7% MgO, etc. .) is treated with sulfuric acid with a flow rate of 0.5-0.9 of the stoichiometrically necessary for the formation of calcium salts and a carbonate-containing reagent is introduced into the solution with a flow rate of 0.01-0.3 of the mass of the original slag. Then the pulp is filtered and the residue after washing is subjected to oxidative calcination at 800-900 ° C for 1.5-2.5 hours. The cinder was leached with sulfuric acid at pH 2-3 at 60-70 ° C for 1-2 hours, the vanadate solution was separated from the residue by filtration and isolated from the solution of vanadium pentoxide. The disadvantages of this method are the low vanadium recovery, high acid consumption and the need for additional operations to neutralize excess acid.

Closest to the claimed technical essence and the achieved result is a sulfuric acid method for extracting vanadium from the converter high-lime slag monoprocess (prototype) [RF Patent No. 2160786. A method of extracting vanadium from highly calcareous slag. / Lyakishev N.P., Reznichenko V.A., Sadikhov G.B. et al. / C22B 34/22, 7/04. Publ. 12/20/2000 Bull. No. 35], including wet slag grinding, pulp treatment (neutralization) with sulfuric acid to pH 8-9.5, followed by filtration, oxidative slag burning at a temperature of 875-1075 ° C for 1 hour, leaching of the calcined product with diluted sulfuric acid ( H ₂ SO ₄ : H ₂ O = 1: 1 ÷ 3) at a pH of 2.5-3.0 and a temperature of 25-50 ° C, followed by precipitation of vanadium from solution (in the form of V ₂ O ₅ - a commercial product) by hydrolysis . Although in this method, in comparison with other analogues, some technological parameters of the process are significantly improved, the through extraction of vanadium from slag into a marketable product is relatively low and does not exceed 80%.

The objective of the proposed invention is to increase the extraction of vanadium in commercial products, as well as improving other basic technological parameters of the method as a whole. The solution to this problem lies in the fact that in the known method of extracting vanadium from highly calcareous slag, taken as a prototype, including wet grinding of highly calcareous slag, processing the crushed slag with sulfuric acid and its oxidative calcination, sulfuric acid leaching of the calcination product, followed by precipitation of vanadium from the hydrolysis solution in accordance with the claimed method, the pulp of crushed slag before firing is treated with concentrated sulfuric acid, dosed in an amount of 30-35% of ma slag sss, oxidative firing of sulfated slag directly without any additional operations are carried out in the temperature range of 700-950 ° C, preferably at 800-900 ° C.

The essence of the proposed method lies in the fact that the processing of pulp of crushed highly calcined slag before oxidative roasting with concentrated sulfuric acid, along with a decrease in the chemical activity of CaO in the slag, makes it possible to destroy the structure of the vanadium-containing slag phase (vanadium-containing calcium titanate with perovskite structure) that is difficult to open during roasting. Due to this, when firing, the oxidation of vanadium is complete with the formation of calcium vanadates readily soluble in weakly acidic solutions; as a result, when the calcined product is leached, the degree of vanadium recovery reaches 90%, i.e. in comparison with the prototype increases by 10-15%. The technological characteristics of the vanadate solution in comparison with the prototype are significantly improved and the filtration rate of leached pulps increases sharply (in the prototype 110-140 ml / min) and reaches ≥400 ml / min. In addition, during sulfatization due to the release of free gel-like oxides of silicon and vanadium, the slag is pelletized to produce bulk material. Therefore, the filtering operation of the treated slag pulp used in the prototype before firing is excluded.

In the proposed method, the optimal firing temperature of sulfated slag is in the range of 700-950 ° C. At higher temperatures, slag sintering occurs, and at temperatures of 700 ° C and lower the process proceeds very slowly. In both cases, the degree of extraction of vanadium is significantly reduced. The most acceptable temperature for burning sulphated highly calcined slag is in the region of 800-900 ° C, in which, along with the achievement of favorable conditions for the technological process, a sufficiently high degree of slag opening and vanadium recovery are ensured during subsequent leaching of the calcined product.

The development of the proposed method for the extraction of vanadium was carried out on the same representative sample of industrial highly lime slag, which was used in the prototype,%: 7.83 V ₂ O ₅ , 36.2 CaO, 9.4 SiO ₂ , 3.6 MnO, 24.6 Fe _total 3.8 TiO ₂ , 1.4 Al ₂ O ₃ , 0.57 P ₂ O ₅ . The material composition of the slag is mainly represented by calcium-containing phases: tricalcium silicate - Ca ₃ SiO ₅ , dicalcium vanadium silicate - Ca ₂ (V, Si) O ₄ , vanadium-containing titanate - Ca ₃ (Ti, V) ₂ O ₇ , and calcium aluminoferrite - Ca ₄ Al ₂ Fe ₂ O ₁₀ . More than 90% of the vanadium contained in the slag is distributed between the first three phases.

The main indicators achieved during the processing of highly lime slag by the proposed method are shown in the table.

The following examples on this slag illustrate the possibilities of the proposed method (these examples in the table are shown in bold; the index 1-6 in the experience number means, respectively, the number of the example).

Example 1. 200 g of crushed slag is subjected to sulfatization (treated with concentrated sulfuric acid) at a 25% consumption of H ₂ SO ₄ (monohydrate), then calcined in an atmosphere of air at a temperature of 900 ° C for 1 hour. The product of firing after cooling is leached under optimal conditions used in the prototype. After filtering the pulp and washing the precipitate (cake), the extraction of vanadium in the solution is 75.35%. Vanadium was precipitated from a solution by a known method — hydrolysis. The pH of the solution was adjusted to 1.7 by the addition of sulfuric acid, then the solution was heated to 100 ° C and kept at this temperature for 1 h. The precipitate was separated from the solution by filtration, washed with water and dried to obtain a commercial product - vanadium pentoxide.

Example 2. Carry out an experiment similar to that described in example 1, however, the acid consumption for sulfatization of the slag before firing is increased to 30%. In this case, the extraction of vanadium increases significantly and reaches 90.84%.

Example 3. In contrast to example 2, in this case, when sulfating the slag, sulfuric acid is taken in an amount of 35%. The recovery of vanadium from slag (90.75%) remains virtually unchanged.

Example 4. The processing of slag is carried out under the conditions of example 3 except that the oxidative firing is carried out at a temperature of 850 ° C. After leaching of the roasting product, the degree of vanadium recovery from the slag reaches 91.6%.

Example 5. The slag is subjected to processing in the conditions of example 3, however, the firing temperature is reduced to 800 ° C. In this case, the extraction of vanadium in the solution decreases to 83.13%.

Example 6. The processing of slag is carried out under the conditions of example 3, except that the sulfated slag is subjected to oxidative calcination at a temperature of 700 ° C. Despite the low firing temperature, the extraction of vanadium from slag into the solution is quite high and is at the level of 79.95%.

Example 7. The processing of slag is carried out under the conditions of example 3, however, in this case, the firing temperature is increased to 925 ° C. Vanadium recovery is relatively low at 84.63%.

Example 8. The experimental conditions are similar to those in example 3, however, the slag is fired at 950 ° C. The recovery of vanadium (78.72%) is almost at the level achieved with low-temperature firing under the conditions of example 6.

As can be seen from the above examples, the proposed method for processing highly calcined vanadium slag (from processing vanadium cast iron to steel by a monoprocess) allows, in comparison with the prototype, to increase the through extraction of vanadium from slag by an average of 5-15% (from 75-85 to 90%) . In addition, due to a significant decrease in the specific consumption of sulfuric acid for leaching of calcined slag with almost the same total consumption (50-55% of the mass of slag) in the prototype and the proposed method, there are no difficulties associated with an increase in the leaching temperature. At the same time, leached pulp filtration rates are significantly improved. Its speed increases to 400 ml / min and higher (in the prototype it is at the level of 140 ml / min).

Table
The results of experiments on the processing of high-slag according to the proposed method (weighed about 200 g) Experience number Consumption of H ₂ SO ₄ ,% by weight of slag t _crim , ° C τ-1 hour Leaching conditions T: W = 1: 3, τ-1 hour The recovery of vanadium,% H ₂ SO ₄ consumption,% by weight of slag t _high , ° C filtration rate, ml / min beg. Max. one fifteen 900 thirty 20,0 33.5 115.3 66.16 2 twenty 900 25 19.2 26.0 127.1 70.91 3 ¹ 25 900 twenty 18.0 24.2 142.6 75.35 four 25 925 twenty 18.5 29.0 144.5 69.03 5 25 950 twenty 17.5 27.0 140.9 66.85 6 ² thirty 900 22.6 21.5 36,2 401.6 90.84 7 ³ 35 900 19.3 21.0 32,2 410.8 90.75 8 40 900 19.2 23.5 33.5 420.1 89.67 9 45 900 15.1 24.0 32,5 397.5 90.91 10 35 600 23.9 24.0 33.5 110.8 26.11 11 ⁶ 35 700 21.5 19.5 31.5 245.2 79.95 12 ⁵ 35 800 21.7 19.0 30.5 316.4 83.13 13 ⁴ 35 850 22.1 18.7 32,0 415.1 91.61 fourteen 35 875 21.6 16.5 28,2 430.4 91.39 fifteen 35 900 21,2 21,2 31.5 420.3 90,42 16 ⁷ 35 925 20,4 18.2 28.0 409.8 84.63 17 ⁸ 35 950 19,4 21.5 32,0 380.2 78.72 eighteen 35 1000 16.3 20.1 30.3 286.5 56.36

Claims (1)

A method of extracting vanadium from highly lime slag, including wet slag grinding, treating slag pulp with sulfuric acid and its oxidative roasting, leaching the calcined product in a slightly acidic sulfuric acid solution, followed by precipitation of vanadium from the solution, characterized in that the pulverized pulverized slag is treated with concentrated sulfuric acid, taken in an amount of 30-35% by weight of the slag, oxidative calcination is carried out at a temperature of 700-950 ° C.