A method of processing fluoride waste production of aluminum by electrolysis

 

(57) Abstract:

Use: waste treatment, production of aluminium to remove the aluminum part, alkali metals and fluorine almost completely, as well as to obtain a raw material containing alumina and a source of energy. The method is suitable for disposal as waste lining electrolysis baths and various sludges. The inventive fluorine-containing waste of the production of aluminum suspended in a solution of aluminum sulfate concentrations 40oC165 g/l, heated to 50oC100oC and stirred for 0.5oC4,0 h before until compounds of alkali metals and fluorine do not go into the liquid phase almost completely. Then lineseparator fraction (solid residue) is one of the known methods, for example by filtration, and washed with hot water. Glinotsementnyj balance and fluoride solution sent for recycling. table 1.

The invention relates to the field of non-ferrous metallurgy and can be used in the recycling of aluminum production to return to the production of compounds of aluminum, alkali metals and fluorine, and carbon. The method is suitable for utilization as Abtenau pot lining [1] consists in retrieving and returning to the cycle of valuable components, such as metal fluorides, alkali and carbon.

The process consists of several stages. Old lining is crushed to particle size of 100 μm, then leached with a solution of sodium hydroxide (14 g/l) before the formation of enriched aluminum fluoride of the alkaline solution and a solid residue containing carbon. For a more complete removal of fluoride carbon-containing residue is treated is heated to 105oC solution of Al2(SO4)3and H2SO4(the ratio of the last 0,75 1,0). The obtained acidic fluoride solution is separated from the carbon particles by filtration. Then the solution is processed in several stages with the release of AlF3and NaOH. The disadvantage of this method is that the process of leaching lead into two stages with the use of reagents as alkaline and acidic nature. This complex instrumentation process causes additional consumption of reagents increases the volume of the mother liquor and wash water, then subjected to recycling and disposal.

Closest to the invention to the technical essence and the achieved result is a method of processing a cryolite forsterei waste [2] formed by the capture and the I with stirring and heating in the range of 40 70oC for 0.5 to 3 hours. Then through the resulting solution is passed gaseous HF. Withstand atomic ratio F Al 3, apply a solution of aluminum sulfate with a concentration of 0.03 to 0.1 M

The main disadvantages of this method include the following. With such low concentrations of aluminum sulfate is impossible to achieve a high degree of extraction of alkali and in particular fluorine and thereby to solve the main task for the neutralization and full recycling. At lower concentrations (see table) to 30.3 g/l, which is approximately equal 0,09 M and thus corresponds to the upper concentration boundary (0.1 M) of the analogue output in the liquid phase decreases for fluorine to 82.5% and sodium oxide to 94.4% in Addition, getting used to the analog HF in turn accompanied by the formation of environmentally hazardous waste, perhaps, and thereby reducing the efficiency of the recycling method of fluorine-containing waste.

The technical result of the invention is the separation of waste aluminum cryolithology and operatsionalnoy faction. The first fraction technological solution suitable for further processing. And the second solid pluralising OST is as alumina or as a pigment in anti-corrosion coatings, or just as an environmentally friendly fuel, or in any other capacity. Thus, solved the technical problem of the invention: split waste aluminum into fractions suitable for full utilization of the most valuable components contained in them.

The technical result is achieved in that in the method of processing solid waste production of aluminum on cialisforyou and lineseparator fraction of fresh sludge, such as sludge wet gas cleaning system or the old sludge from sludge fields, suspended in a solution of aluminum sulfate concentration of 40 165 g/l, heated to 50 100oC and stirred for 0.5 to 4.0 hours up until compounds of alkali metals and fluorine do not go into the liquid phase almost completely. Then lineseparator fraction (solid residue) is one of the known methods, for example by filtration, and washed with hot water. Glinotsementnyj balance and fluoride solution sent for recycling.

The invention consists in that the use of the method of solution of aluminum sulfate in a certain range of concentration makes effective one-step separation of solid waste at cialisforyou and lineseparator INIA, heat and mix up until a solid residue, glinosempromstroy fraction is released from the fluorides of alkali metals and aluminum almost completely. The formation of a new phase, aqueous solution, which goes cryolithology fraction of solid waste is becoming possible due to the fact that the conditions for the formation and dissolution in the aqueous environment of chemical compounds: persulfate aluminum, sulfates of alkali metals, etc. It is evidenced by the data shown in the table.

Implement the method as follows. A portion of the dried (optional) slurry and a certain amount of a solution of aluminum sulfate load with stirring in a reactor and heated for 0.5 to 4.0 hours at a temperature of 50 100oC. the thus Treated sludge is separated and washed with hot water.

Was composed of a representative batch of sludge from sludge fields one of the largest factories in the industry. Dry part dried at 105oC sludge contained, by weight. Al2O38,4; F 12,3; Na2O 9,9; K2O 0,32; CaO 0,77% MgO 0,49% Fe2O31,2; SiO22,0; others mainly carbon. The results of the experiments presented in the table.

An example implementation is>water was loaded into the reactor and stirred for 4 h at t 98oC. Then the suspension was filtered, the solid residue was washed on the filter 250 cm3hot water and dried at 105oC. the Solid residue contained, mass. Al2O37,4; Na2O 0,47; F OF 0.26. The degree of extraction of sodium oxide 97% of fluoride 98%

Data presented in table confirm the high efficiency of the proposed method of solid waste processing aluminum cialisforyou and lineseparator fractions: liquid phase sodium oxide and fluorine reaches 98%

Thus, the proposed method allows the use of current waste production and return to the process with sludge fields, vast amounts of alkalis, fluorine, alumina and carbon, and the environment free from toxic pollutants.

A method of processing fluoride waste production of aluminium by electrolysis, comprising leaching them with a solution of aluminum sulfate at elevated temperature and separating the liquid and solid phases, characterized in that the solution of aluminum sulfate take with a concentration of 40 165 g/l and the leaching is carried out at 50 to 100oC.

 

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FIELD: nonferrous metallurgy; processing of sodium sulfate solutions.

SUBSTANCE: the invention is pertaining to the field of nonferrous metallurgy, in particular, to processing of sodium sulfate solutions, which are released into a slime storage after a gas cleaning treatment electrolysis of bodies by production of aluminum. The method of processing of sodium sulfate solutions produced after the gas purification of the electrolysis bodies at production of aluminum provides for the gases purification from sulfuric oxides and fluorides by their sprinkling with a sodium sulfate solution in the washers, extraction from the solution after the gas purification of the fundamental quantity of sodium fluoride in the form of cryolite. The sodium sulfate solution purified from cryolite is in addition purified from sodium fluoride by its treatment at the temperature of 95-105°С within 1.5-2.0 hours with a lime milk injected into the sodium sulfate solution at the rate of stoichiometric binding of fluorine contained in the solution in CaF2. The sodium sulfate solution purified from fluorine is further subjected to a concentrating evaporation till achieving the density of a product solution of 1.37±0.02 g/l and extract a sodium sulfate from it into the sediment a in the form of berkeyit salt by introduction in the product solution of a carbonate soda till achieving the concentration of the titratabic alkali in the mother liquor of 215-230 g/l Na2Ot and the density of the solution in the suspension up to 1.35±0.02 g/l at stirring of the suspension at temperature of 95-100°С within 30-40 minutes. The invention ensures a more complete extraction of sodium sulfate from the product sodium sulfate solution in the form of berkeyit salt purified from sodium fluoride.

EFFECT: the invention ensures a more complete extraction of sodium sulfate from the product sodium sulfate solution in the form of berkeyit salt purified from sodium fluoride.

FIELD: mining industry.

SUBSTANCE: method comprises charging cryolite in rinsing water, washing it at stirring, and dehydration of washed product. Washing is continued until content of sodium sulfate achieves 45-65% that in initial cryolite, which requires time from 5 to 60 min at rinsing water temperature 25 to 70°C and water-to-cryolite weight ratio (3-10):1.

EFFECT: reduced mechanical loss of cryolite due to lesser degree of particle grinding at maximum possible degree of sodium sulfate removal.

4 tbl, 2 ex

FIELD: mining industry.

SUBSTANCE: invention relates to chemical and metallurgical processing of crude ore to produce technical-destination aluminum compounds, in particular cryolite (Na3AlF6). Cryolite is produced, in particular, from beryl concentrate. Charge consisting of beryl concentrate, soda ash, and limestone is melted and subjected to wet granulation, Granulate is ground and sulfatized with sulfuric acid. Sulfatized granulate is subjected to water leaching to extract aluminum and beryllium sulfates into solution. Resulting sulfate solution is neutralized with aqueous ammonia to jointly precipitate aluminum and beryllium hydroxides. Mixture of the two hydroxides is separated from mother liquor, dissolved in concentrated sodium hydroxide solution, and diluted in water to precipitate beryllium hydroxide, which is separated from sodium aluminate solution. Then, cryolite is precipitated via treatment with 40% hydrofluoric acid, used in amount 2.0-2.5 ml acid per 1 g sodium in solution, and with freshly precipitated aluminum hydroxide until weight ratio Na/Al = 2.5-3.0 is attained in cryolite pulp.

EFFECT: optimized process flowsheet.

1 tbl

FIELD: chemistry.

SUBSTANCE: cryolite is obtained by mixing aluminium oxide, sodium chloride and ammonium hydrodifluoride or fluoride in stoichiometric ratio, taken in excess of up to 20% of the stoichiometric ratio. The obtained mixture is heated at the first stage to 240°C and kept at this temperature until complete separation of ammonia gas and water, and at the second stage - to 400°C and kept until complete subliminal removal of ammonium chloride.

EFFECT: invention allows for obtaining cryolite and ammonium chloride at the same time.

2 ex

FIELD: metallurgy.

SUBSTANCE: proposed method washing off of regeneration cryolite pulp in condensate formed in heating of cryolite in pulping reactor. Duration of washing-off makes 30-60 minutes, temperature of condensate used for purifying if regeneration cryolite of sulfur compounds makes 50-80°C, volume ratio of used condensate to purifying pump makes (5÷8):1.

EFFECT: reduced costs, high quality.

4 cl, 1 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to production of inorganic coagulants based on iron and aluminium compounds. Aluminium metal is dissolved in aqueous solution of iron (II) chloride with concentration of iron ions 45-70 g/l, while stirring for 10-15 min. The precipitate is separated. Fe (II) is oxidised to Fe (III) using hydrogen peroxide at temperature 70-80°C for 1-2 hours.

EFFECT: method increases output of coagulant 2-3 times and also lowers content of aluminium and iron in water treated using the coagulant 2 and 3 times, respectively.

1 tbl, 5 ex

FIELD: metallurgy.

SUBSTANCE: solid fluorine-carbon-containing waste is treated with water solution of caustic alkali of concentration 25-35 g/dcm3 at temperature 60-90°C. Further, product is separated to deposit and solution with successive supply of solution into production of fluoric salts. Upon leaching deposit is treated with 1.0-1.5% water solution of organic acid at temperature 60-80°C and product is separated to deposit and solution. Solution is directed to production of fluoric salts, while carbonic deposit is directed to production of carbon containing products. Ratio L:S is preferably maintained as 10:1 at treatment of waste with solution of caustic alkali, while oxalic acid can be used as organic acid.

EFFECT: extraction of valuable components from waste.

3 cl, 1 tbl, 2 ex

FIELD: metallurgy.

SUBSTANCE: processing method for spent carbon-containing lining of aluminium electrolytic cell involves lining grinding, leaching with aqueous solution of sodium hydrate, separation of liquid and solid phases of the pulp, solution treatment with extraction of fluorine product. Grinding of spent carbon-containing lining is performed in water at pH = 6-8 and temperature up to 60 °C. Further, the pulp is processed with sodium hydrate solution at 80-100 °C for 4-10 hours at pH = 10-12. After phase separation, the solution is treated with an acid and/or salts.

EFFECT: obtainment of high-quality return fluorine-containing product.

5 cl, 1 tbl, 1 ex

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