RU2363742C1 - Method for extraction of precious components out of coal ashes and slags - Google Patents

Abstract

FIELD: technological processes. ^ SUBSTANCE: invention is related to method for extraction of precious components out of coal ashes and slags. Method includes mixing of initial raw materials with reagent, mixture heating, water leaching and extraction of components out of solutions. Reagent used in mixing is ammonium fluoride, ammonium hydrodifluoride or their mixture. Mixture heating is done at temperature from 130C to 240C for hydrofluoridation. From heated fluoridated mass fluoride volatile compounds are extracted at temperature of 320-600C with their further desublimation on surface, temperature of which is 100-270C, and separation by pyrohydrolysis method by desublimate treatment with water vapors. Residue after hydrofluoridation and sublimation separation is exposed to water leaching. Insoluble residue after water leaching is exposed to sulfuric acid leaching, with further filtration separation of insoluble sulfates. Extraction of components from solutions of sulfuric acid and water leaching is realised by method of ammonium hydrolysis. ^ EFFECT: possibility to separate ash and slag into individual components. ^ 3 ex, 1 dwg

Description

The invention relates to the field of chemical technology of inorganic substances and can be used in cases where it is necessary to isolate one or more valuable components from coal slag or to carry out their complete separation.

A known method of processing slag based on the interaction of slag with a reducing agent. The solid charge, rolling along the walls of the furnace, is heated to a temperature of 1100-1200 ° C, while the reaction of reduction of zinc, lead and rare elements to metal proceeds. Metal vapors are sublimated and again oxidized in the space above the charge to an oxide that is carried away by gases into the dust collecting system [Lakernik MM, Mazurchuk EN, Petker S.Ya., Shabalina RI Processing of slag non-ferrous metallurgy. - M.: Metallurgy. 1977. - 159 p.]. The disadvantages of the method is the high energy intensity and environmental safety.

A known method involving the stepwise grinding of chromate production waste and separation of the crushed material by gravity methods to produce a chromium-containing concentrate, a magnesium-containing concentrate and a concentrate containing light metal compounds. The starting material is ground and sent to the first stage of gravity separation, during which a light fraction is obtained in the form of a concentrate of light metal compounds and a heavy fraction is in the form of chromium and magnesium-containing intermediate product, which is subjected to regrinding, followed by gravity separation into a chromium-containing concentrate and a magnesium-containing concentrate [patent No. 2117533]. The disadvantage of this method is the complexity of the hardware design of the separation process.

A known prototype method for the separation of valuable components from coal ash and slag, including mixing the feedstock with a reagent, heating the mixture, water leaching and separation of the components from solutions [patent No. 2170775]. The disadvantage of this method is the inability to separate all ash and slag components into separate fractions.

The present invention is to develop a method for the separation of ash and slag into individual components.

The problem is solved in that the pre-ground slag is mixed with ammonium fluoride, ammonium hydrodifluoride or a mixture thereof and heated to a temperature of 130 to 240 ° C and held for 1-5 hours, slag hydrofluorination occurs. Next, the fluoride mixture is heated to 320-600 ° C, volatile compounds are freeze-dried. Gaseous fluoride compounds are desublimated on a surface with a temperature of 20-270 ° C and separated by pyrohydrolysis, treating the desublimate with water vapor, as a result of subsequent heating to a temperature of 320-600 ° C, sublimation separation of fluoride compounds not subjected to pyrohydrolysis remains in solid form oxides of elements whose fluoride compounds have undergone pyrohydrolysis. Gaseous fluoride compounds are desublimated on a surface with a temperature of 20-310 ° C and treated with ammonia water, resulting in the formation of oxides, which are separated by filtration. The solution was evaporated to give ammonium fluoride.

The solid residue after hydrofluorination and sublimation separation of fluoride compounds is subjected to water leaching, as a result of which a series of fluorides passes into the solution. The solution is subjected to ammonia hydrolysis, while the hydrolysis is carried out by gradually increasing the pH of the solution to separate the precipitated hydroxides, ammonia remains in the solution, which are destroyed by boiling, followed by filtration. The solution was evaporated to give ammonium fluoride.

The solid residue after aqueous leaching of the fluoride mixture is subjected to sulfuric acid leaching, followed by aqueous leaching, as a result of which insoluble sulfates are precipitated in solid form. The solution is treated with ammonia water, while the hydrolysis is carried out by a gradual increase in the pH of the solution to separate the precipitated hydroxides, as a result of which hydroxides are released in solid form. The solution was evaporated to obtain soluble hydroxides and ammonium sulfate.

The technological sequence of operations is shown in the drawing.

Example 1

A portion of ash and slag weighing 20 g, containing 65.9% (13.18 g) SiO ₂ , 21% (4.2 g) Al ₂ O ₃ , 3% (0.6 g) K ₂ O, 4% (0, 8 g) CaO, 0.8% (0.16 g) TiO ₂ , 0.2% (0.04 g) MnO ₂ , 5% (1 g) Fe ₂ O ₃ , 0.1% (0.02 g) CuO is mixed with 115 g of ammonium hydrodifluoride. The mixture is transferred to a corundum crucible and kept in a shaft furnace at a temperature of 200 ° C for 2 hours. The profiled mass is heated to 400 ° C, volatile compounds of silicon and titanium are sublimated, which are captured and desublimated. Desublimate is treated with water vapor and reheated to 400 ° C, a volatile silicon compound that has not undergone pyrohydrolysis is sublimated, and titanium dioxide remains in solid form. The volatile silicon compound is captured and desublimated, the desublimate is dissolved in 50 ml of water and treated with 50 ml of ammonia water; the resulting slurry is transferred to a filter and the solid residue, which is silicon dioxide, is separated. The mass of titanium dioxide obtained was 0.12 g and silicon dioxide 13.08 g.

The solid residue after hydrofluorination is dissolved in 70 ml of water, the resulting slurry is transferred to a filter and the solid residue is separated.

The solid residue is treated with 8 g of sulfuric acid, boiled for 20 minutes and dissolved in 50 ml of water. The solid residue represented by calcium sulfate is filtered off. 50 ml of ammonia water are poured into the solution, and aluminum hydroxide which is precipitated in solid form is filtered off, which is calcined to oxide. The solution was evaporated to obtain solid potassium hydroxide and ammonium sulfate. The mass of the obtained alumina was 4.11 g, calcium sulfate 1.92 g.

Ammonia water is poured into the solution obtained after dissolving solid fluorides containing iron, manganese and copper fluorides, bringing the pH to 1-3, and iron hydroxide precipitated in solid form is separated by filtration, bringing the pH of the solution above 8, precipitated in solid form is filtered manganese hydroxide. Copper ammonia remains in the solution, it is heated to 100 ° C and copper hydroxide precipitated in solid form is separated. Hydroxides are calcined to form oxides. The mass of the obtained iron oxides was 0.92 g, manganese - 0.02 g, copper - 0.01 g.

Example 2

It differs from Example 1 in that 148 g of ammonium fluoride was used as the opening reagent. The mass of the obtained SiO ₂ was 13.09 g, Al ₂ O ₃ - 4.16 g, CaSO ₄ - 1.91 g, TiO ₂ - 0.11 g, MnO ₂ - 0.03 g, Fe ₂ O ₃ - 0.96 g, CuO - 0.01 g.

Example 3

It differs from Example 1 in that a 130 g mixture of ammonium fluoride and ammonium hydrodifluoride was used as the opening reagent. The mass of the obtained SiO ₂ was 13.15 g, Al ₂ O ₃ - 4.12 g, CaSO ₄ - 1.92 g, TiO ₂ - 0.14 g, MnO ₂ - 0.04 g, Fe ₂ O ₃ - 0.95 g, CuO - 0.02 g.

Claims (1)

The method of separation of valuable components from coal ash and slag, including mixing the feedstock with a reagent, heating the mixture, water leaching and separation of components from solutions, characterized in that ammonium fluoride, ammonium hydrofluoride or a mixture thereof is used as a reagent, the mixture is heated at a temperature from 130 to 240 ° C for hydrofluorination, from the heated fluorinated mass, sublimation separation of fluoride volatile compounds is carried out at a temperature of 320-600 ° C, followed by their desublimation on top water, the temperature of which is 100-270 ° C, and separation by pyrohydrolysis by treating desublimate with water vapor, the residue after hydrofluorination and sublimation separation is subjected to water leaching, the insoluble residue after water leaching is subjected to sulfuric acid leaching, followed by filtration separation of insoluble sulfates, the separation of components from acid solutions and water leaching are carried out by ammonia hydrolysis.

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