RU2701319C1 - Method for complex processing of aluminum-containing salt slag - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to a method for complex processing of aluminum-containing salt slag formed during production of secondary aluminum. Method involves preliminary crushing and washing from salts of slag containing aluminum oxide, then treatment of slag with sulfuric acid, separation of filtration of obtained solution from sand, sand is washed, and the purified solution is fed into the crystallizer and cooled, separating the aluminum sulphate crystals from the mother solution containing sulfuric acid, the aluminum sulphate crystals are washed with an organic solvent which, after regeneration, is used in subsequent washing operations, and mother solution, which contains sulfuric acid, is used in subsequent steps of slag treatment, and released during washing slag from salts of gases H₂, CH₄, C₂H₂ combustion and using combustion heat to evaporate salt solution and obtain crystals of NaCl and KCl salts, and NH₃ is used to produce ammonium sulphate, washed from salts slag is pre-purified from iron oxides on a magnetic separator, and mother solution is pre-purified from impurities of sulphates by-products.

EFFECT: separation of reagents into alumina-containing salt slag into components and enhancement of quality and quantity of finished products from aluminum-containing salt slag due to careful separation of raw materials into components at each stage of technological process.

1 cl, 1 dwg

Description

Technical field

The invention relates to a technology for processing aluminum-containing salt slags formed in the production of secondary aluminum.

State of the art

A known method of processing aluminum-containing slag by washing them with water, followed by drying the precipitate, grinding it to obtain powder, which is used in the preparation of concrete mix as a blowing agent (US patent No. 4119476, publ. (A) - 1978-10-10).

The reasons why it is impossible to achieve a technical result is the poor yield of products due to the residual gases in them.

A known method of processing waste from aluminum production, characterized in that the waste from aluminum production is treated with hydrochloric acid or its salt, which is used in the form of a 1-10% aqueous solution, followed by exposure at the temperature of the working room for the complete neutralization reaction (patent RU No. 2137852, publ. . September 20, 1999).

The reasons why it is impossible to achieve a technical result is that the aluminum-containing slag is not processed, but neutralized for subsequent disposal.

There is also known a method for processing aluminum slag, including grinding in a grinding drum, separating aluminum metal, after which the oxide and salt parts of the slag are separated. Next, the salt slag is ground in a drum mill with water and, after filtration, the brine is evaporated, and the slag is recycled to the mill. Grinding of salt slag is carried out according to a multi-stage scheme and after washing it, the slag is stored (DE patent No. 2825806 from 06/13/78, MKI C22B 7/04).

The reasons why the technical result cannot be achieved is that it is limited to the extraction of aluminum metal and NaCl and KCl salts from the slag.

The closest analogue taken as a prototype is a method of producing aluminum sulfate, including preliminary washing of slag containing aluminum oxide from salts, then treating it with sulfuric acid, separating the resulting solution by filtration from sand, characterized in that the sand is washed and the purified solution is fed after filtration into the crystallizer and cooled, aluminum sulfate crystals are separated from the mother liquor, which contains sulfuric acid, aluminum sulfate crystals are washed with an organic solvent, These aluminum sulfate crystals are dried and packaged in bags, after washing them from the remaining mixture of organic solvent, water and sulfuric acid, the organic solvent is separated by distillation at its boiling point, the liquefied organic solvent is used in subsequent washing operations, and the mother liquor, which contains sulfur acid, used in the subsequent stages of the processing of slag (RU patent No. 2315715, publ., January 27, 2008).

The reasons why it is impossible to achieve a technical result is that the use of aluminum-containing slag to obtain a single product - aluminum sulfate, without preliminary purification of the feedstock from iron and the circulating mother liquor from impurities of metal sulfates, which reduces the quality of the finished product.

Disclosure of the invention

The technical problem lies in the development of a method for separation into component reagents in aluminum-containing salt slag.

The technical result is aimed at improving the quality and quantity of finished products from aluminum-containing salt slag, through careful separation of raw materials into constituent components at each stage of the process.

The technical result is achieved by the fact that the method of complex processing of aluminum-containing salt slag, including pre-crushing and washing from the salts of slag containing aluminum oxide, then processing the slag with sulfuric acid, filtering the resulting solution from sand, sand is washed, and the purified solution is fed into the crystallizer and cooled , aluminum sulfate crystals are separated from the mother liquor, which contains sulfuric acid, aluminum sulfate crystals are washed with an organic solvent, which after regeneration used in the subsequent washing operations, as stock solution, which includes sulfuric acid, was used in the subsequent stages the slag processing, and the gases produced during flushing of slag from salts H _2, CH _4, C ₂ H ₂ is burned and use the combustion heat to evaporation of the saline solution and obtaining crystals of NaCl and KCl salts, and NH _{3 is} used to produce ammonium sulfate, the slag washed from salts is preliminarily purified from iron oxides on a magnetic separator, and the mother liquor is preliminarily purified from impurities th sulphates of by-products.

Description of drawings

The implementation of the method is shown schematically in FIG. 1, where:

1. ball mill;

2. slag washing reactor;

3. the capacity of the solution of NH ₃ ;

4. burner;

5. filter for separating slag and a solution of salts of NaCl, KCl;

6. crystallizer of salts of NaCl, KCl;

7. centrifuge;

8. magnetic separator;

9. sulfonation reactor;

10. pulp filter;

11. sand washing filter;

12. a drying drum;

13. an aluminum sulfate crystallizer;

14. KSA filter;

15. KSA washing filter;

16. evaporator;

17. capacitor;

18. evaporator;

19. filter Me;

20. reactor for the production of ammonium sulfate;

21. a metal hydroxide filter;

22. an ammonium sulfate crystallizer;

23. ammonium sulfate filter;

24. A drum for drying ammonium sulfate.

The implementation of the invention

The method includes pre-washing the slag containing alumina from salts (NaCl and KCl) with the formation of a saturated 30% solution. The released gases (NH3, C2H2, CH4, H2) are separated in an aqueous medium to form an ammonia solution and a gas mixture consisting of hydrogen, methane and acetylene. A mixture of gases (H2, CH4, C2H2) is used as an energy carrier to obtain crystals of NaCl and KCl from solution. The ammonia solution is used in the process to obtain mineral fertilizers.

The slag washed from salts is purified from iron oxides, treated with sulfuric acid, and the resulting solution is separated by filtration from sand. The sand is washed, and the purified solution after filtration is fed into the crystallizer and cooled. Crystals of aluminum sulfate are separated from the mother liquor, which includes sulfuric acid and sulfates of metal impurities. The crystals of aluminum sulfate are washed with an organic solvent, dried and packaged in bags. After washing them, the organic solvent is separated by distillation from the remaining mixture of the organic solvent and the mother liquor. The liquefied organic solvent is used in subsequent washing operations. The mother liquor after filtering the crystals of aluminum sulfate and the mother liquor after distillation of the organic solvent are collected and sent for regeneration. During regeneration, the mother liquor is evaporated to a sulfuric acid content of 76%. At a concentration of sulfuric acid, crystals of sulfates of by-products (Mg, Fe, etc.) are formed. Crystals of metal sulfates are filtered off, and the purified mother liquor is used in the subsequent stages of processing the slag.

The filtered crystals of by-product sulfates are dissolved in ammonia water to form ammonium sulfate and metal hydroxides. Metal hydroxides are filtered off and dried. A solution of ammonium sulfate is evaporated to form crystals. Ammonium sulfate crystals are filtered off, dried and bagged.

When processing salt slags, a mixture of NaCl and KCl salts is obtained, which are a flux for smelting secondary aluminum; aluminum sulfate, which is used as a coagulant in the treatment of domestic, industrial, and wastewater; ammonium sulfate, used as a mineral fertilizer, as well as sand consisting of silicon oxide, aluminum, magnesium, iron and other metals and their hydroxides, which is a safe building material, iron oxides that are used to produce pigments.

The invention allows to effectively implement a universal, waste-free, environmentally friendly technology for the integrated processing of aluminum-containing slag.

Crushed slag, cleaned of lump aluminum and scrap iron, is crushed in a ball mill 1. For the occurrence of chemical reactions and to accelerate the grinding process, a small amount of water is supplied to a ball mill. The crushed slag enters the slag washing reactor 2. where the chemical reactions with the evolution of gases (NH3, H2. CH4, C2H2) are completed, the gases are passed through water in a tank 3 with the formation of an ammonia solution. Gases purified from ammonia (H2. CH4, C2H2) are burned on burner 4.

The slag after reactor 2 is separated on a filter for separating slag and a solution of salts of NaCl, KCl 5 from a saturated solution of salts of NaCl and KCl. In the crystallizer of NaCl, KCl 6 salts under the action of heat, excess moisture is removed from burner 4 to form NaCl and KCl crystals. The crystals of NaCl and KCl salts are separated in a centrifuge 7, and the saturated solution is returned to the crystallizer of NaCl salts, KCl 6.

Slag from the filter of separation of slag and water 5 is fed to a magnetic separator 8 to remove iron oxides. The purified slag is fed to a sulfonation reactor 9, which also serves sulfuric acid, reverse mother liquor (MR) and water. After the reaction, the pulp is poured onto the pulp filter 10, where sand is separated from the solution. The sand on the sand washing filter 11 is washed and dried in a drying drum 12. The washing water enters the sulfonation reactor 9. The solution from the pulp filter 10 enters the aluminum sulfate crystallizer 13. When the solution containing sulfuric acid is cooled, aluminum sulfate crystals precipitate. The crystals of aluminum sulfate (KSA) are separated from the mother liquor on the KSA 14 filter, washed on the KSA 15 washing filter with an organic solvent (ethyl alcohol) from the residues of the mother liquor, filtered and dried. The organic solvent with the mother liquor enters the evaporator 16, where it is separated from the mother liquor, condenses in the condenser 17 and is used in subsequent washing operations of aluminum sulfate crystals. The mother liquor from the KSA 14 filter and the evaporator 16 is collected in the evaporation apparatus 18. When the mother liquor is evaporated to a sulfuric acid concentration of 76%, the formed metal sulfate crystals (Mg, Fe, etc.) are separated on the Me 19 filter. The purified mother liquor is sent to the sulfonation reactor 9 for subsequent boiling of aluminum sulfate. Crystals of metal sulfates (Mg, Fe, etc.) are dissolved in ammonia water in an ammonium sulfate production reactor 20 to form ammonium sulfate and metal hydroxides. The metal hydroxides are separated on a metal hydroxide filter 21 and dried, and the ammonium sulfate solution is evaporated in an ammonium sulfate crystallizer 22 to form crystals, filtered on an ammonium sulfate filter 23 and, after drying in a drum for drying ammonium sulfate 24, is packed in bags.

Claims (1)

A method for the complex processing of aluminum-containing salt slags, including preliminary crushing and washing of slag containing aluminum oxide from salts, then treating the slag with sulfuric acid, filtering the resulting solution from sand, sand is washed, and the purified solution is fed to the crystallizer and cooled, aluminum sulfate crystals are separated from the mother liquor, which includes sulfuric acid, the crystals of aluminum sulfate are washed with an organic solvent, which after regeneration is used subsequently x washing operations, and the mother liquor, which includes sulfuric acid, is used in the subsequent stages of slag treatment, characterized in that the gases released during the washing of the slag from salts H ₂ , CH ₄ , C ₂ H _{2 are} burned and the heat of combustion is used for evaporation saline solution and obtaining crystals of salts NaCl and KCl, and NH ₃ are used to produce ammonium sulfate, the scrubbed salt slag has previously purified from iron oxides in a magnetic separator, and the mother liquor was purified by pre-sulphates incidental impurities metals.

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