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Method for defluorinating and preparing cryolite by secondary aluminum ash acid method

A secondary aluminum lime acid and cryolite technology, applied in the preparation/separation of ammonia, chemical instruments and methods, aluminate/alumina/aluminum hydroxide purification, etc., can solve the problem of unsatisfactory large-scale production and complicated process , Low product value and other issues, to achieve harmless and high-value utilization, avoid environmental pollution, and achieve significant economic benefits

Active Publication Date: 2020-06-26
CENT SOUTH UNIV +2
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Due to the complex composition of secondary aluminum ash, it is easy to produce high-risk chemicals such as ammonia, hydrogen, methane, hydrogen fluoride, and cyanide after contact with water, causing fires; Causes necrosis of plant tissue, seriously endangers bone health of human body and livestock
The method is complex in process, high in energy consumption, low in product value, and uneconomical
Patent CN104495893A discloses a preparation method of cryolite. The solid residue containing calcium sulfate, sodium sulfate and aluminum sulfate produced by the decomposition of albite and the gas product containing silicon fluoride are used as raw materials to generate cryolite. Acid leaching and adding NaF to produce cryolite; however, the operation is complicated and the raw materials are expensive, so it is difficult to popularize on a large scale
Patent CN105502451A discloses a method for producing aluminum fluoride and co-producing high molecular ratio cryolite, but producing cryolite as a co-product has low production efficiency and cannot meet large-scale production

Method used

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  • Method for defluorinating and preparing cryolite by secondary aluminum ash acid method

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0033] The specific operation is as follows:

[0034] (1) Get 1kg secondary aluminum ash and sieve after ball milling, the yield on the sieve is 4.08%, the metal aluminum grade is 71.5%, and the recovery rate is 69.1%;

[0035] (2) Take 955g of secondary aluminum ash from which metal aluminum has been removed and add water to the reaction kettle at a liquid-solid ratio of 5:2, heat and stir at 100°C for leaching for 4 hours, and recover the overflowed ammonia gas with water to prepare ammonia water;

[0036] (3) After that, directly add an appropriate amount of concentrated hydrochloric acid to prepare 1mol / L hydrochloric acid, and carry out acid leaching and stirring leaching according to the liquid-solid ratio of 10:1, the leaching temperature is normal temperature, and the time is 1h;

[0037] (4) Carry out solid-liquid separation after acid leaching to obtain acid leaching slag and acid leaching liquid; the yield of acid leaching slag is 61%, which is alumina with a purity...

Embodiment 2

[0042] The specific operation is as follows:

[0043] (1) Get 1kg secondary aluminum ash and sieve after ball milling, the yield on the sieve is 3.53%, the metal aluminum grade is 79.86%, and the recovery rate is 66.23%;

[0044] (2) Take 960g of secondary aluminum ash from which metal aluminum has been removed and add water into the reaction kettle at a liquid-solid ratio of 5:2, heat and stir at 100°C for leaching for 6 hours, and recover the overflowing ammonia gas with water to prepare ammonia water;

[0045] (3) Afterwards, directly add an appropriate amount of concentrated hydrochloric acid to prepare 1.5mol / L hydrochloric acid, and carry out acid leaching and stirring leaching according to the liquid-solid ratio of 10:1, the leaching temperature is normal temperature, and the time is 1h;

[0046] (4) Carry out solid-liquid separation after acid leaching to obtain acid leaching slag and acid leaching liquid; the yield of acid leaching slag is 55.1%, which is alumina with...

Embodiment 3

[0051] The specific operation is as follows:

[0052] (1) Get 1kg secondary aluminum ashes and sieve after ball milling, the yield on the sieve is 4.4%, the metal aluminum grade is 68.2%, and the recovery rate is 70.1%;

[0053] (2) Take 950 g of secondary aluminum ash from which metal aluminum has been removed and add water to the reaction kettle at a liquid-solid ratio of 5:2, heat and stir at 100° C. for leaching for 4 hours, and recover the overflowed ammonia gas with water to prepare ammonia water;

[0054] (3) After that, directly add an appropriate amount of concentrated hydrochloric acid to equip it with 3mol / L hydrochloric acid, and carry out acid leaching and stirring leaching according to the liquid-solid ratio of 5:1, the leaching temperature is normal temperature, and the time is 1h;

[0055] (4) Carry out solid-liquid separation after acid leaching to obtain acid leaching slag and acid leaching solution; the yield of acid leaching slag is 54.4%, which is alumina ...

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Abstract

The invention provides a method for defluorinating and preparing cryolite by a secondary aluminum ash acid method. The method comprises the following steps: carrying out ball milling on secondary aluminum ash, and screening to remove metal aluminum; taking the aluminum ash from which the metal aluminum is removed, adding water, heating and leaching; adding acid into the slurry subjected to water leaching for acid leaching; carrying out solid-liquid separation on the slurry subjected to acid leaching to obtain an acid leaching solution and acid leaching residues; mixing the acid leaching solution with NaF, and adjusting the pH value of the mixed solution to be neutral; heating and stirring the solution of which the pH value is adjusted, and then carrying out solid-liquid separation to obtain a cryolite product and residual liquid; and drying the obtained cryolite product to obtain a finished product, and returning the obtained residual liquid to the ball milling process for cyclic utilization. According to the method, harmless utilization of the secondary aluminum ash is achieved, recyclable products such as cryolite and high-purity aluminum oxide are produced, resource circulationis achieved, economic benefits of enterprises are improved, and the method has important practical significance and practical value.

Description

technical field [0001] The invention relates to the field of recovery and utilization of waste resources in the aluminum industry, in particular to a method for defluorinating aluminum ash acid twice and preparing cryolite. Background technique [0002] Metal aluminum is the second largest metal used by humans. Since its production began in 1888, it has produced about 1 billion tons accumulatively, and its recycling rate is as high as 75%. However, in all aluminum melting processes such as primary aluminum electrolytic smelting, secondary aluminum melting and casting cycle, aluminum processing, etc., the molten metal aluminum is in contact with the air, the surface is oxidized, and semi-solid floating objects are formed on the molten body, which is in order to reduce aluminum. Various fluorine compounds added according to the melting point are mixed to form an unavoidable hazardous solid waste - aluminum ash. Aluminum ash is divided into primary aluminum ash and secondary a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F7/54C01F7/46C01C1/02
CPCC01C1/022C01C1/026C01F7/46C01F7/54C01P2006/80
Inventor 张国范邓传宏刘琨石晴李松春冯海港荀骆冰镇思远
Owner CENT SOUTH UNIV
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