RU2062800C1 - Method for processing of waste melt of chlorinators of titanium production - Google Patents

Abstract

FIELD: processing of wastes of chlorination of ilmenite concentrates. SUBSTANCE: melt of chlorinators of titanium production is poured in water. Into thus prepared solution sodium sulfate is added, its quantity being 7-12 kg/m³ as calculated for sulfate ion. Thus obtained pulp is cooled to 25-35 C, after cooling solution is additionally used for production of pulp having density 1.20-1.28 g/cm³. Then barium chloride is added into pulp (its quantity being 7-12 kg/m³) and mixing within 0.5-1.0 h is carried out. The process is followed by adding 0.2-0.5 % solution of polyacryl amide, its quantity being 0.05-0.10 m³/m³ of pulp. Thus prepared pulp is allowed to stand within 2-4 h. Clarified solution is used for extraction of valuable components. Clarifying degree is about 70 %. EFFECT: improves efficiency of the method. 3 tbl

Description

 The present invention relates to the field of non-ferrous metallurgy and can be used in the complex processing, utilization and neutralization of waste from the production of titanium tetrachloride.

 According to the existing technology, a significant amount of chloride waste is produced annually containing iron, chromium, manganese, thorium, scandium, niobium, tantalum, titanium, zirconium, aluminum, sodium, potassium, magnesium, etc.

 Currently, there are several dozens of ways to process, neutralize and utilize the spent melt of titanium chlorinators with the extraction of valuable components and obtaining marketable products. However, there are still no industrially developed reliable and simple ways of preparing waste for further processing.

 The known / I / method, which consists in draining the spent melt into a mixture of water and a cooled working solution in a water removal bath, separating the coarse fraction of the insoluble residue in the classifier, draining the undiluted solution into a buffer tank equipped with an impeller mixer and a heat exchanger, from which the solution flows by gravity into the water removal bath or for processing.

The disadvantage of this technology is the low rate of clarification, for 10 hours the degree of clarification is 70%
Of the known analogues, the closest to the claimed method in terms of features is the known method / 2 / for obtaining concentrated solutions (pulps) of the spent melt of titanium chlorinators (prototype).

 The prototype method is as follows.

 The spent melt from the chlorinator is discharged into the hydrodetachment bath, and water or a circulating solution (pulp) is simultaneously supplied there. The resulting pulp flows by gravity into a sump, where a large fraction of insoluble sediment settles, the clarified pulp is pumped into the collection tank, where it is cooled by the water supplied to the collection jacket. After cooling, the solution (pulp) is pumped back into the hydraulic removal bath. To prevent sedimentation of particles of water-insoluble residue and clogging of valves, as well as to prevent popping and emissions, nitrogen is supplied to the hydraulic removal bath and collection tank. To accelerate clarification, the pulp is additionally treated with a 0.2% solution of polyacrylamide (PAA) in an amount of 5-10% of the volume of the pulp.

The main disadvantage of this method (prototype) is the preparation of solutions containing suspended solids up to 60-80 g / dm ³ , which complicates the subsequent processing of solutions.

 The claimed technical solution is aimed at solving the problem of reducing the content of thorium and the fine fraction of the insoluble residue.

This problem is solved by the proposed method for processing the spent melt of titanium chlorination plants, the essence of which is expressed by the following set of essential features: solid sodium sulfate in the amount of 7-12 g / dm ³ by sulfate ion is introduced into the pulp after discharge, then the pulp is cooled to 25-35 ^o C and again sent to hydraulic erosion. The operation of hydraulic washing is repeated (circulating) 4-6 times until the pulp density reaches 1.20-1.28 g / cm ³ . After that, barium chloride is introduced into the pulp in an amount of 7-12 g / dm ³ , stirred for 0.5-1.0 hours and clarification is carried out by supplying a 0.1-0.5% solution of polyacrylamide in an amount of 0.05-0, 10 m ³ / m ³ . Moreover, in the process of pulp circulation, sodium sulfate gradually dissolves in the chloride solution, then, in the process of barium sulfate precipitation, thorium compounds and the finely dispersed fraction of insoluble residue co-precipitate. The clarified solution is directed to the extraction of valuable components to obtain marketable products.

 The sequence of operations in the process of hydraulic washing of the spent melt of titanium chlorinators (ORTX) is due to the following.

When OPTX is first drained, the melt dissolves at a water-melt ratio (10-7): 1 and the pulp is heated to 80-90 ^o C. At the same time, solutions with a density of 1.02-1.09 g / cm ³ diluted with metal chlorides are obtained. 4-6 times circulation provides pulp with a density of 1.20-1.28 g / cm ³ containing, g / dm ³ : 40-60 iron, 3-5 chromium, 6-10 manganese, 0.05-0.10 scandium, 0.1-0.3 zirconium, 0.01-0.03 thorium, 7-10 magnesium and calcium, and up to 200 g / dm ^{3 of} sodium and / or potassium chlorides. These pulps, which are chloride-saturated stock solutions with pH from 0.4 to 0.2, contain up to 60-80 g / dm ^{3 of the} solid phase (finely divided part of the insoluble residue TiD ₂ , Al ₂ O ₃ , C, SiD ₂ and other).

 Such a pulp, in principle, is convenient for its subsequent neutralization from toxic substances by neutralization, for example, with milk of lime, since in this case 4-5 times less (compared to the prototype known method) quantity of solutions is processed. However, for subsequent complex processing with the extraction and disposal of valuable components, the pulp is practically unsuitable and must be clarified, since the pulp does not settle and is not filtered through all the tested filter fabrics: polyvinyl chloride, cotton belting, polyester, lavsan, nylon, etc.

Research and pilot trials have shown that this problem can be solved by sequentially treating the pulp with sodium sulfate first (7-12 g / dm ³ SO $\genfrac{}{}{0ex}{}{\text{-2}}{\text{4}}$ ), then barium chloride (7-12 g / dm ³ BaCl ₂ ) and a 0.1-05% solution of polyacrylamide (0.05-0.1 m ³ / m ³ pulp). Under these conditions, for 2-4 hours, clarification by 70% occurs and the content of suspended solids in the clarified part is 0.1-0.5 g / dm ³ .

 With any other sequence of pulp processing, the main objective of the invention is to ensure the obtaining of metal-concentrated solutions with a low content of suspended solids, suitable for subsequent complex processing, is not achieved.

 In particular, it is necessary to pay attention to the fact that pulp is treated with solid sodium sulfate. This is due to the following: treatment with sodium sulfate in the form of a solution requires the additional installation of tank equipment for the preparation and dosage of solutions and the preparation of diluted solutions.

 The analysis of patent and scientific and technical documentation indicates that the sources of information have not found a description of the methods similar to the proposed and coinciding with the claimed technical solution for the totality of essential features.

 The analysis of the prior art in relation to the totality of all the essential features of the claimed technical solution shows that the proposed method meets the criterion of novelty.

 Verification of compliance of the claimed invention with the requirement of "inventive step" in relation to the totality of essential features indicates that the proposed method does not follow for experts explicitly from the prior art. In particular, the fact that the treatment of the solution with sodium sulfate after the first discharge of the melt with barium chloride after 4-6-fold circulation and then with a 0.2% PAA solution will obviously result in a technical result is reduced from the prior art. suspended particulate matter.

 The essence of the proposed method is as follows.

 The spent melt of titanium production chlorinators is poured into a bath filled with water. To prevent a rapid increase in the temperature of the solution, water (solution) is continuously supplied to the bath. To prevent the accumulation of solid residue in the bath and the oxidation of iron (II) to iron (III), nitrogen is continuously fed into it during the discharge of the melt through the barbators installed in the lower part of the bath.

The resulting pulp is continuously drained through a sump, where a large fraction of the insoluble residue settles and is collected in a collection tank. After discharge, sodium sulfate is introduced into the pulp in an amount of 7-12 g / dm ³ by sulfate ion, mixed with nitrogen to dissolve sodium sulfate and prevent sedimentation at the bottom of the tank and cool the pulp to 25-35 ^o With water supplied to the jacket of the collection tank .

The cooled pulp is again fed into the hydro-removal bath for the next discharge of the melt. This operation is repeated (i.e., the pulp is circulated in the hydraulic removal bath-sump-tank-collector system) 4-6 times until a density of 1.20-1.28 g / cm ^{3 is} reached. Then, barium chloride is introduced into the pulp, preferably in solid form (in order to dilute the solution) in an amount of 7-12 g / dm ³ , stirred with nitrogen for 0.5-1.0 hours, cooled to 25-35 ^o C, clarification lead by feeding a 0.1-0.5% solution of polyacrylamide in an amount of 0.05-0.1 m ³ / m ³ pulp, followed by settling for 2-4 hours. A clarified solution containing, g / dm ³ : Fe 52- 60; Cr 3.9-4.2; Mn 9-10; Sc 0.06-0.07; suspended solids 0.1-0.5, drained and sent for complex processing with the extraction of iron, chromium, manganese, scandium in the form of marketable products.

 Information confirming the possibility of carrying out the invention is given in the examples.

Example 1.1 By a known method
The spent melt of titanium production chlorinators through the overflow unit is periodically discharged into a hydraulic removal bath filled with water over the upper overflow. When the melt enters the water, it cools and dissolves, accompanied by intense evaporation and boiling of water at the contact point. To prevent a rapid increase in the temperature of the solution, water is fed continuously into the hydro-removal bath at a speed of 25-35 nm ³ / h, maintaining the temperature of the solution at 80-90 ^o С. The resulting salt solution along the upper overflow is also continuously drained through the sump into the collection tank. The coarse fraction from the sump is auger discharged into the boxes and transported to the dump. The ratio of water to melt is approximately 7-10: 1. In this case, solutions are formed with a density of 1.07-1.10 g / cm ³ . The concentration of metals is 20-25 g / DM ³ .

 To prevent the sedimentation of suspended and insoluble particles and the accumulation of solid sediment in the bath, compressed air is continuously supplied into it during the discharge of the melt through barbators installed in the lower part of the bath.

With 4-6-fold circulation, solutions (pulps) are formed with a density of 1.20-1.25 g / cm ³ . After processing with a 0.2% PAA solution and holding for 4 hours, the mass concentration was, g / dm ³ : Fe (III) 3.5; Fe (II) 3.7; Th 0.05; Cr 3.7; Mn 8.2; Sc 0.04; suspended solids 52. The processing of such pulp is difficult, because leads to contamination of the resulting products with water-insoluble particles.

Example 1.2 According to the proposed method
The spent melt of titanium production chlorinators is discharged and the water removal bath is filled. The resulting salt solution along the upper overflow is continuously drained through the sump and pumped into the collection tank. At the end of the discharge, sodium sulfate is loaded in a solution having a temperature of 80-90 ^{° C.} in an amount of 10 g / dm ³ by sulfate ion. After cooling the solution to 25-35 ^o With it is again used to drain the melt. After 4-5 cycles, pulps with a density of 1.23-1.25 g / cm ^{3 are formed} . After 5-fold circulation, the pulp is treated with barium chloride in an amount of 10 kg / m ³ and stirred for 0.5-1.0 hours. Then, the pulp is treated with polyacrylamide and settled. In the table. 1 shows the results of tests on the effect of the amount of polyacrylamide and sludge time.

As can be seen from the data in Table 1, a clarification degree of 60-65% is achieved in 4 hours depending on the amount of 0.2% PAA solution introduced (0.05-0.020 m ³ / m ³ pulp). Further sedimentation of the pulp (up to 24 hours) leads to a slight increase in the degree of clarification of the pulp (up to 72%). It is economically feasible to limit 2-4 hours of sludge. Studies have shown that the concentration of PAA in the range of 0.1-0.5% has virtually no effect on the degree of clarification.

As a result of this treatment, a solution was obtained containing, g / dm ³ : Fe 53.4; Cr 3.99; Mn 8.94; Sc 0.066; Zr 0.12; Th 0.031.

 Comparative tests (in a pilot plant) showed the possibility of using these solutions for their complex processing, in particular, for the extraction and utilization of compounds of iron, chromium, manganese and scandium (according to previously developed technologies). It was found that the performance of the installation in the case of dilute solutions drops by 8-10 times, while the loss of metals increases, the energy consumption disproportionately increases, etc. In addition, there are known difficulties with obtaining clarified solutions (sedimentation, filtering of pulp, etc.).

Example 2
Same as in example 1.2. However, the circulation was 2 times, a solution was obtained with a density of 1.15 g / cm ³ containing, g / dm ³ : Fe 30; Cr 2.7; Mn 5.3; Sc 0.037; Zr 0.06; Th 0.021.

 The feasibility study showed that the complex processing of such solutions is unprofitable. Table 2 shows the composition of the solutions, depending on the number of plums.

 Thus, the upper limit is due to safety considerations, and the lower limit is due to the profitability (technical and economic indicators) of the process.

 Examples 3-6 show the test results in which either the sequence of actions is changed, or the process parameters differ from the optimal ones.

Example 3
The same as in example 1 according to the proposed method, only sodium sulfate was introduced after 6 discharge, then barium chloride, while the degree of clarification of the pulp decreases and is 35-40% instead of 70%. In addition, the additional effect of cleaning the solution from thorium compounds also decreases . The thorium concentration decreases only from 0.034 to 0.019 g / dm ³ .

Example 4
The same as in example 1 according to the proposed method, only first introduced barium chloride, and at the end of the circulation of sodium sulfate. In this case, practically unremovable and poorly filtered pulps were also obtained, as in the case of untreated pulp.

Example 5
The same as in example 1 according to the proposed method, only the solution after pouring the melt was not cooled in the collection tank with water to a temperature of 25-35 ^o C, and immediately filed for circulation, in this case, boiling of the solution, its discharge, which leads to emergency situations in the workshop.

Example 6
In the table. Figure 3 shows the results of pulp clarification depending on the amount of sodium sulfate and barium chloride added. The consumption of polyacrylamide in all cases was 0.1 m ³ / m ³ .

As can be seen from the above data, with the introduction of an ion sulfate and barium chloride of less than 7 g / dm ³ , complete clarification of the solutions is not achieved. At a flow rate of more than 12 g / dm ^{3, the} degree of clarification does not increase, only the consumption of reagents increases.

 Thus, the resulting solutions are suitable for further processing, for example, to extract scandium compounds or pigment synthesis.

 The proposed method of melt hydraulic washing allows to increase the degree of concentration of metals, increase the productivity of the process and improve working conditions. In addition, the proposed method also solves the environmental problem of the disposal of waste from highly toxic substances to produce marketable products.

 In addition to the social effect, the proposed method gives a significant economic effect due to the sale of commercial products of scandium oxide, iron oxide shell pigments, chromium compounds, iron-manganese, manganese concentrates, etc., as well as paints based on them. TTT1 TTT2 TTT3

Claims (1)

A method of processing the spent melt of titanium production chlorinators, including pouring the melt into water, cooling the chloride pulp, circulating it, clarifying it with polyacrylamide, and then processing the clarified solution with the extraction of valuable components, characterized in that 7- sodium sulfate is introduced into the pulp after discharge 12 g / dm ³ at sulfate ion, cooling is carried out to 25-35 ° C, the resultant pulp was used to drain the circulating melt to a density of 1.2 1.28 g / cm ^3, and before it is introduced into the clarification chlorides barium in an amount of 7-12 g / dm ^3, 0,5 stirred 1.0 hours and lighting supply lead 0.1 0.5 polyacrylamide solution in an amount of 0.05-0.1 m ³ slurry followed by settling 2 to 4 hours.

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