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Method for recycling aluminum electrolysis waste cathode carbon blocks

A technology for recycling waste cathode carbon blocks and aluminum, applied in chemical instruments and methods, aluminum fluoride, aluminum halide, etc., can solve the problems of difficult quality assurance, large amount of waste water, and difficult recycling of carbon materials, so as to solve equipment corrosion. , the effect of efficient use

Active Publication Date: 2020-05-19
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Patent CN 110127649A treats spent cathode carbon blocks by oxidative decyanation, sulfuration roasting and defluorination, and concentrated crystallization to obtain Glauber's salt, but this method needs to consume 5 to 7 times the mass of spent cathode carbon blocks in the process. Concentrated sulfuric acid and 2~ 3 times the amount of sodium hydroxide, and produce waste water of more than 15 times the quality of spent cathode carbon blocks; patent CN1320491A uses acid-base combined roasting to process waste cathode carbon blocks, but the resulting product contains fluorine in sodium sulfate, silicon in alumina, and fluoride Contains iron, so the quality is difficult to guarantee; the patents GB2056422A and US005955042A sulfurate and roast the waste cathode carbon blocks, and then perform high-temperature treatment. In the process, graphite carbon materials are used as fuels for low-value combustion, wasting resources
It can be seen that the existing sulfuration roasting process still has the problems of large amount of wastewater and difficulty in recycling carbonaceous materials

Method used

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  • Method for recycling aluminum electrolysis waste cathode carbon blocks

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0056] (1) The cathode carbon block is crushed and sieved to obtain carbon particles;

[0057] (2) Taking the Si element in the carbon particles and the S element in the sulfuric acid solution as the target, after adding the sulfuric acid solution, the Si and S molar ratio in the slurry A is 1:2.10, and the concentration of the sulfuric acid solution is 3mol / L, soaking The time is 5 hours, the temperature is 150°C, the pressure is 0.4MPa, and the gas generated during the process is absorbed with lye.

[0058] (3) Slurry B was evaporated and concentrated at a temperature of 120° C., and the obtained slurry C had a water mass percentage of 8%, and the generated steam was collected to obtain slurry C.

[0059] (4) With the element F in the slurry C and the sulfur element in the concentrated sulfuric acid and the slurry C as the target, after adding the concentrated sulfuric acid, the molar ratio of F and S in the slurry D is 1:1.0, and the concentration of the concentrated sulfur...

Embodiment 2

[0062] (1) Crushing and screening the waste cathode carbon blocks to obtain carbon particles;

[0063] (2) Taking the Si element in the carbon particles and the S element in the sulfuric acid solution as targets, after adding the sulfuric acid solution, the Si and S molar ratio in the slurry A is 1:2.15, and the concentration of the sulfuric acid solution is 2mol / L. The time is 3 hours, the temperature is 200°C, and the pressure is 1.6MPa. The gas generated during the process is absorbed with lye.

[0064] (3) Slurry B was evaporated and concentrated at a temperature of 160° C., and the obtained slurry C had a water mass percentage of 7%, and the generated steam was collected to obtain slurry C.

[0065] (4) The element F in the slurry C, the concentrated sulfuric acid, and the sulfur element in the slurry C are targeted. After adding the concentrated sulfuric acid, the molar ratio of F and S in the slurry D is 1:2.0, and the concentration of the concentrated sulfuric acid is ...

Embodiment 3

[0068] (1) Crushing and screening the waste cathode carbon blocks to obtain carbon particles;

[0069] (2) Taking the Si element in the carbon particles and the S element in the sulfuric acid solution as targets, after adding the sulfuric acid solution, the Si and S molar ratio in the slurry A is 1:2.20, and the concentration of the sulfuric acid solution is 1mol / L, soak The time is 1 hour, the temperature is 250°C, and the pressure is 4MPa. The gas generated during the process is absorbed with lye.

[0070] (3) Slurry B was evaporated and concentrated at a temperature of 180° C., and the obtained slurry C had a water mass percentage of 6%, and the generated steam was collected to obtain slurry C.

[0071] (4) The element F in the slurry C, the concentrated sulfuric acid, and the sulfur element in the slurry C are targeted. After adding the concentrated sulfuric acid, the molar ratio of F and S in the slurry D is 1:3.0, and the concentration of the concentrated sulfuric acid i...

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Abstract

The invention discloses a method for recovering aluminum electrolysis waste cathode carbon blocks, which comprises the following steps: (1) crushing and screening waste cathode carbon blocks to obtaincarbon particles; (2) mixing the carbon particles with a sulfuric acid solution to obtain slurry A, and then performing pressure leaching to obtain a slurry B; (3) evaporating and concentrating the slurry B until the mass percent of water is lower than 8% to obtain a slurry C; (4) adding concentrated sulfuric acid into the slurry C to obtain a slurry D, roasting at 150-300 DEG C for 0.5-10 hours,and roasting at 300-600 DEG C for 0.5-8 hours to obtain baked carbon; and (5) heating the baked carbon to 1200-3000 DEG C, and keeping the temperature for 0.5-20 hours to obtain the purified carbon.In the treatment process, high-temperature fluorine-containing flue gas and fluorine-containing wastewater are not generated, and fluorine, aluminum and carbon materials can be recycled, so that comprehensive recycling and cleaning treatment of the aluminum electrolysis waste cathode carbon blocks are realized.

Description

technical field [0001] The invention belongs to the technical field of comprehensive utilization of solid waste in the electrolytic aluminum industry, and in particular relates to the recovery of aluminum electrolytic waste cathode carbon block resources. Background technique [0002] The aluminum electrolysis cathode is deformed, bulged and broken due to the erosion, erosion and thermal stress of molten salt and aluminum liquid, thus producing waste cathode carbon blocks. Under normal circumstances, for every ton of electrolytic aluminum produced, about 10kg of waste cathode carbon blocks will be produced. In 2018, the global output of electrolytic aluminum was 64.34 million tons, and more than 600,000 tons of waste cathode carbon blocks were produced, which is a huge amount. Aluminum electrolysis waste cathode carbon block contains carbon, aluminum fluoride, sodium fluoride, calcium fluoride, cryolite, alumina, nepheline and cyanide and other substances. Among them, the c...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B32/05C01B32/205C01B32/215C01F7/50
CPCC01F7/50C01P2006/80C01B32/05C01B32/205C01B32/215
Inventor 赖延清田忠良龚培育杨凯
Owner CENT SOUTH UNIV
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