RU2334800C1 - Method of extraction of vanadium out of after burning waste of sulphuric black oil - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention refers to non-ferrous metallurgy and can be used for extraction of vanadium out of ashes which is waste produced by burning of sulphuric vanadium containing black oil in heat engines of heat and hydropower stations. The method consists in the following: source ashes are mixed with sodium carbonate and water at a weight ratio of 100:(10-60):(30-50), then produced mixture is held at temperature of 100-150°C, preferably 115-120°C, during 2 hours. Vanadium is leached out of produced self-diffusing cake with water at temperature of 95-100° and a ratio of liquid: solid = (1.5-3):1.

EFFECT: avoiding of generating harmful gas exhausts at extraction of vanadium and implementation of available equipment.

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Description

The invention relates to the field of non-ferrous metallurgy and can be used to extract vanadium from waste generated during the combustion of sulfur vanadium-containing fuel oil in heat plants of a thermal power plant and state district power station.

Currently, due to the lack of rational processing technology, waste is accumulated in the settling tanks of thermal power plants, creating a danger to the environment. Waste is a slimy material with a V ₂ O ₅ content of 0.8 to 20%, consisting mainly of oxides of iron, calcium, silicon and unburned soot residues of organic matter.

There is a method of processing the ash residues of a thermal power plant in a charge with other vanadium-containing materials to produce vanadium sinter and pellets, which are further used in steel industry for steel alloying (ed. St. USSR No. 918322, IPC S22B 34/22, publ. 1982). The method is intended for use of vanadium in the steel industry.

At the same time, for other applications of vanadium, it is of most interest to obtain it in the form of vanadium pentoxide. To extract vanadium in the form of vanadium pentoxide from various solutions, precipitation of solutions of poorly soluble ammonium vanadate with its subsequent decomposition is used or precipitation from a solution of hydrated vanadium pentoxide V ₂ O ₅ × H ₂ O at a solution pH of 1.5-2 followed by dewatering of the precipitate (Chemistry and technology of rare and scattered elements. Edited by Bolshakov. Vol. 3, M., 1976, p. 320).

A known method of converting vanadium from ash to solution by treating the ash with a solution of hydrogen peroxide at room or low temperature (Japanese application No. 49-32404, IPC C22B 55/00, publ. 1974). Vanadium in the form of pentoxide is precipitated from the solution after heating and oxidation.

The disadvantage of this method is the use of an expensive and easily decomposing reagent.

A known method of processing fly ash containing vanadium, a concentrated solution of sodium hydroxide, which selectively dissolves vanadium from the ash obtained by processing bitumen shale (French patent No. 2187878, IPC C10C 3/00, publ. 1974).

This method uses a rather expensive reagent, in addition, when vanadium is leached from the ash formed after burning fuel oil at a thermal power plant, a low vanadium extraction should be expected in the solution, since calcium and iron vanadates from the thermal power plant ash do not decompose when caustic leached out.

According to the interaction chemistry and the technical essence, the closest to the proposed method is the processing method used to extract vanadium from various products, which consists in sintering vanadium raw materials with soda ash (sodium carbonate) at a temperature of 600-800 ° C in an oxidizing atmosphere, followed by leaching of vanadium from sintering with water (US patent No. 3929460, IPC C22B 7/04, 34/22, publ. 1975).

A method for extracting vanadium from vanadium-containing slag, similar in composition to vanadium-containing ash, is described. This method is used for the selective extraction of vanadium from various products. Depending on the consumption of soda in the solution, up to 90% of vanadium can be recovered. To implement this method requires a roasting rotary tube furnace lined with refractories, and a system for the disposal and disposal of the resulting gas medium.

The need for special high-temperature equipment and additional measures for dust and gas collection make it difficult to implement the method in the conditions of each individual CHP.

There is also a method of extracting vanadium from vanadium-containing raw materials, which use TPP ash and, after mixing them with limestone, are additionally treated with water at T: W 1: 1.5: 10, at a temperature of 30-80 ° C for 10-30 minutes (patent RF №2080403, IPC С22В 34/22, publ. 1997).

The task of creating the present invention is to develop an environmentally friendly, accessible for implementation under normal conditions, the method of extracting vanadium from ash, which is a waste product from burning sulfur fuel oil using sodium carbonate (soda ash).

The problem is solved in the proposed method, the essence of which is that to extract vanadium from ash, which is a waste product of burning sulfur fuel oil, heat treatment of the mixture of the initial ash with sodium carbonate and subsequent leaching of vanadium from the obtained cake, while the original ash is mixed with sodium carbonate and water, taken in a weight ratio of 100: (10-60) :( 30-50), heat treatment of the resulting mixture is carried out at a temperature of 100-150 ° C for 2 hours, and leaching of vanadium is carried out with water at a temperature of 95- 100 ° C and the ratio W: T = (1.5-3): 1.

Under the conditions of the proposed ash heat treatment, the gas phase consists mainly of water vapor, which can be easily condensed.

No additional measures are required to clean the gas mixture.

Using a mixture of water with soda at given ratios allows you to create the effect of a concentrated solution in the ash layer with a relatively low consumption of soda. The contact of ash particles with a concentrated solution at temperatures of 100-150 ° C ensures the desorption of vanadium from soot particles and the intensive flow of mass transfer processes according to the schemes:

Ca (VO ₄ ) ₂ + Na ₂ CO ₃ → CaCO ₃ ↓ + 2NaVO ₄

Fe (VO ₄ ) ₂ + Na ₂ CO ₃ + 1 / 4O ₂ + 1 / 2H ₂ O → Fe (OH) CO ₃ ↓ + 2NaVO ₄ + CO ₂

The conversion of vanadium into a soluble form, and calcium and iron into sparingly soluble compounds.

The resulting friable cake is leached with water. To accumulate the concentration of vanadium in the solution, leaching is carried out in dense pulps, with a ratio of W: T = (1.5-3): 1 with a partial or full use of the resulting solutions to leach fresh portions of cake. The resulting solutions with a pH of 1.5-2 are heated to a boil. In this case, a precipitate of hydrated vanadium pentoxide is released from the solution. Decomposition of the initial ash with a soda solution at relatively low temperatures allows one to obtain a sufficiently pure vanadium pentoxide with an impurity content of less than 2%.

Due to the availability of the implementation of the method and environmental safety, it can be used directly in the conditions of each thermal power plant or state district power station in small plants of simple design.

The proposed method was developed on a laboratory and enlarged laboratory scale. The effectiveness of the method is illustrated by the examples and experimental results presented in the table.

Example 1 (by a well-known analogue - US patent No. 3929460).

A portion of the initial ash with a V ₂ O ₅ content of 11.3% is mixed with soda ash (sodium carbonate) in a weight ratio of 100: 20. The mixture is heated in a muffle furnace at a temperature of 800 ° C for 2 hours with air purging. After cooling, the cake is ground and leached with water at a temperature of 95 ° C for 1 hour at a ratio of W: T = 3: 1.

73.6% V ₂ O _{5 was} recovered in a solution with a V ₂ O ₅ content of 27.7 g / L. The yield of cake was 48.2%, the residual content of cake V ₂ O ₅ was 6.2%.

Example 2 (by the proposed method).

A portion of the initial ash with a V ₂ O ₅ content of 11.3% is mixed with sodium carbonate and water in a ratio of 100: 20: 50. The mixture is heated in an oven at a temperature of 120 ° C for 2 hours in contact with air. The resulting hot cake is leached with water at a temperature of 95 ° C for 1 hour at a ratio of W: T = 3: 1.

74.4% of V ₂ O _{5 was} recovered in a solution with a V ₂ O ₅ content of 28.0 g / l, cake yield 88.7%. Its content of V ₂ O _{5 is} 3.26%.

The above examples show that by analogy and the proposed method with the same consumption of soda, approximately the same extraction of vanadium in solution is achieved. The yield of cake by analogue is less due to the burning of soot particles contained in ash at 800 ° C. As a result, the content of V ₂ O ₅ in the cake is higher by analogy than by the proposed method.

The data shown in the table show that in the proposed method, with the consumption of soda 10-60% by weight of ash, an acceptable extraction of vanadium in the solution is ensured. Soda consumption of more than 60% does not provide an economically acceptable increase in vanadium recovery. Water consumption of 30-50% by weight of ash is optimal for dissolving the soda introduced into the mixture, and sufficient to maintain the mixture in a wet state during the heat treatment at 100-150 ° C.

Thus, the application of the proposed method allows you to translate vanadium into a solution with extraction, comparable and slightly higher than by analogy. The process is carried out at low temperatures, eliminating the formation of harmful gas emissions, and using available equipment.

Table The results of leaching vanadium from the ash of a thermal power plant after heat treatment of ash with sodium carbonate by analogy (US patent No. 3929460) and by the proposed method. Experience number Heat treatment conditions for the initial ash (per 100 g of ash) The leaching conditions of the obtained cake The nature of the solution after leaching Cake after leaching The recovery of V ₂ O ₅ in solution,% The consumption of Na ₂ CO ₃ ,% The consumption of N ₂ O,% t, ° C τ, hour Leaching solution W: T t, ° C τ, hour Volume, l per 100 g of ash with a promvod pH V ₂ O ₅ , g / l Exit, % V ₂ O ₅ ,% one By analogy H ₂ O, 3: 1 95 one 0.3 9.1 27.7 48,2 6.2 73.6 twenty - 800 2 2 According to the proposed method H ₂ O, 3: 1 95 one 0.3 8.9 26.5 91.0 3.67 70,4 10 fifty 120 2 3 twenty fifty 120 2 H ₂ O, 3: 1 95 one 0.3 9.3 28.0 88.7 3.26 74,4 four 40 fifty 120 2 H ₂ O, 3: 1 95 one 0.3 10.1 28.7 86.5 3.11 76,2 5 60 fifty 120 2 H ₂ O, 3: 1 95 one 0.3 10.8 30,0 83,2 2.77 79.6

Claims (1)

A method of extracting vanadium from ash, which is a waste product of burning sulfur fuel oil, comprising heat treatment of a mixture of the initial ash with sodium carbonate and subsequent leaching of vanadium with water from the obtained cake, characterized in that the initial ash is mixed with sodium carbonate and water, taken in a weight ratio of 100: (10 -60) :( 30-50), and the mixture is heat treated at a temperature of 100-150 ° C for 2 hours, and vanadium is leached with water at a temperature of 95-100 ° C and the ratio W: T = (1.5-3 ):one.