Method for leaching and recycling fluorine in aluminum electrolysis cell waste cathode

An aluminum electrolytic cell waste and leaching technology, applied in the direction of calcium/strontium/barium fluoride, calcium/strontium/barium halide, etc., can solve the problems of difficult large-scale industrial application, low recovery rate of valuable components and high processing cost , to achieve the effect of no secondary pollution, mild conditions and easy availability of raw materials

Active Publication Date: 2019-05-10
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, most of the current inventions are aimed at condition optimization and auxiliary treatment technologies for the acid-base leaching process, such as ultrasonic-assisted leaching, pressure-assisted leaching, etc., but there are still problems such as high processing costs, complicated processes, and low recovery rates of valuable components. Large-scale industrial application

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  • Method for leaching and recycling fluorine in aluminum electrolysis cell waste cathode
  • Method for leaching and recycling fluorine in aluminum electrolysis cell waste cathode

Examples

Experimental program
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Effect test

Embodiment 1

[0040] Take 100g of waste cathode carbon blocks from an aluminum electrolytic cell in a domestic factory, and the measured main element contents are (wt.%): C32.91, O15.9, Na 13.92, F 12.63, Al 8.93, and the TCLP leaching toxicity analysis results are fluoride ions The concentration is 5236.57mg / L.

[0041] After collecting the waste cathodes of the aluminum electrolytic cells, they were crushed and mixed to collect spare granules. Among the spare granules, the particles with a particle diameter of less than 60 mesh accounted for 90% of the total mass of the granules. Add the spare particles into deionized water at a liquid-solid ratio of 5:1, stir with a stirrer at a speed of 300r / min for 30min at 30°C, and filter after leaching to obtain a primary filtrate and a primary filter residue.

[0042] Add the primary filter residue to a 0.3mol / L ferric nitrate solution at a liquid-solid ratio of 10:1, stir with a stirrer at a speed of 300r / min for 90min at 50°C, and filter after le...

Embodiment 2

[0046] Take 100g of waste cathode carbon blocks from an aluminum electrolytic cell in a domestic factory, and the measured main element contents are (wt.%): C 32.91, O 15.9, Na 13.92, F 12.63, Al 8.93, and the fluoride ion concentration of the TCLP leaching toxicity analysis results is 5236.57mg / L.

[0047] After collecting the waste cathodes of the aluminum electrolytic cell, they were broken and mixed to collect spare particles, and the particles with a particle size of less than 60 mesh in the spare particles accounted for 80% of the total particle mass. Add the spare granules into deionized water at a liquid-solid ratio of 10:1, stir with a stirrer at a speed of 300r / min for 60min at 40°C, and filter after leaching to obtain primary filtrate and primary filter residue.

[0048] Add the primary filter residue to the mixed solution of 0.5mol / L ferric nitrate and 0.8mol / L nitric acid according to the liquid-solid ratio of 20:1, stir with a stirrer at a speed of 300r / min for 6...

Embodiment 3

[0052] Take 100g of waste cathode carbon blocks from an aluminum electrolytic cell in a domestic factory, and the measured main element contents are (wt.%): C 32.91, O 15.9, Na 13.92, F 12.63, Al 8.93, and the fluoride ion concentration of the TCLP leaching toxicity analysis results is 5236.57mg / L.

[0053] After collecting the waste cathodes of the aluminum electrolytic cell, they are broken and mixed to collect the spare granules. Among the spare granules, the particles with a particle diameter of less than 60 mesh account for 100% of the total mass of the granules. Add the spare particles into deionized water at a liquid-solid ratio of 10:1, stir with a stirrer at a speed of 200r / min for 60min at 50°C, and filter after leaching to obtain a primary filtrate and a primary filter residue.

[0054] Add the primary filter residue to the mixed solution of 0.3mol / L ferric nitrate and 0.6mol / L nitric acid according to the liquid-solid ratio of 10:1, stir with a stirrer at a speed o...

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Abstract

The invention relates to a method for leaching and recycling fluorine in an aluminum electrolysis cell waste cathode, and belongs to the field of aluminum electrolysis solid waste source recycling. The method includes the steps: crushing and finely grinding aluminum electrolysis cell waste cathode carbon blocks, and leaching soluble fluoride in the carbon blocks by water solution; complexing filter residue after leaching by iron salt solution, and leaching insoluble fluoride in the filter residue; filtering mixture to obtain powdered carbon with low content of the fluoride; adding calcium saltor calcium-containing compound into primary filter liquor and secondary filter liquor to generate calcium fluoride, recycling fluorine sources, and returning tail liquid after filtering to corresponding working sections to be recycled. According to the method, the fluoride in the waste cathode can be efficiently separated, secondary pollution is omitted, the purity of the prepared calcium fluoride is higher than 65%, the calcium fluoride can be used for metallurgy industry, the content of carbon in the recycled carbon powder is higher than 80%, and follow-up utilization is facilitated. The method is short in process procedure, harmless treatment of the aluminum electrolysis cell waste cathode carbon blocks is achieved, and the fluorine has good industrial application prospects.

Description

technical field [0001] The invention relates to a method for leaching and recovering fluorine from waste cathodes of aluminum electrolytic cells, and belongs to the technical field of recycling and utilization of aluminum electrolytic solid waste resources. Background technique [0002] The electrolytic aluminum industry in my country has developed rapidly, and the output of primary aluminum has ranked first in the world for many years in a row. Studies have shown that about 30-50 kg of waste cathode carbon blocks are discharged for every 1 ton of electrolytic aluminum produced. With the substantial increase in aluminum production, the waste cathode carbon blocks produced each year are also increasing year by year. The waste cathode carbon block of aluminum electrolytic cell contains a lot of fluoride (NaF, Na 3 AlF 6 , CaF 2 etc.) and a small amount of cyanide have been included in my country's "National Hazardous Waste List" (waste code 321-023-48). As early as the 19...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01F11/22
Inventor 郭朝晖聂云飞郭鑫瑶彭驰肖细元
Owner CENT SOUTH UNIV
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