Method for recycling aluminum electrolysis waste cathode carbon blocks

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...

AI Technical Summary

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

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