Method for preparing porous carbon material from aluminum electrolysis waste cathode carbon

Abstract

The invention discloses a method for preparing a porous carbon material from aluminum electrolysis waste cathode carbon, wherein aluminum electrolysis waste cathode carbon is used as a raw material, and the purposes of fluorine fixation and etching are mainly realized through auxiliary treatment and reactant reaction, so that easy-to-separate porous carbon is obtained. According to the invention,soluble fluorine ions in waste cathode carbon are cured by utilizing calcium ions or magnesium ions in a calcium agent or a magnesium agent, oxygen ions and hydroxyl ions in the calcium agent or the magnesium agent are combined with sodium ions, potassium ions and lithium ions to form oxides and hydroxides with high etching property, so that in-situ hole etching is realized; water vapor generatedby auxiliary treatment or high-temperature decomposition of the calcium agent and the magnesium agent can react with insoluble aluminum fluoride and cryolite to generate hydrogen fluoride and aluminumoxide, so that the content of insoluble fluoride in the carbon is reduced; and air in auxiliary treatment can improve the etching property of a carbon skeleton, increase the wettability of a carbon interface and improve the separability of impurities, so that the content of the impurities in the carbon material is reduced.

Description

Technical field [0001] The invention relates to a method for resource utilization of aluminum electrolysis waste cathode carbon, in particular to a method for preparing porous carbon materials from aluminum electrolysis waste cathode carbon. Background technique [0002] my country's electrolytic aluminum is developing rapidly. By the end of December 2019, the electrolytic aluminum production capacity reached 35.04 million tons. However, due to the effects of thermal shock, chemical erosion, mechanical erosion, sodium and electrolyte penetration, etc., the aluminum electrolytic cell is damaged after 4 to 7 years of use and needs to be overhauled. With the increase in the output of electrolytic aluminum, the waste cathode carbon produced by the overhaul has also increased rapidly. Among them, only the Chinese electrolytic aluminum industry produces 250,000 tons of waste cathodes each year. In recent years, more than 4 million tons of waste cathodes have been accumulated. Suitable...

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Problems solved by technology

However, this method has large investment, high energy consumption, high processing cost, and secondary pollution.

[0006] (3) Ultra-high temperature separation method: the "AUMSET" process developed by Alcoa Company, but it has large investment, high energy consumption and high cost

However, this method has the following problems: first, toxic dust and gas containing cyanide are produced during the crushing and screening process of electrolytic aluminum waste cathode carbon; High energy consumption, strict equipment requirements and high cost; third, the flue gas needs to be purified after secondary combustion, which requires high investment and is prone to secondary pollution; fourth, after calcination at 2000-2600 °C, the resulting carbon still contains A large amount of fluoride (such as calcium fluoride with a boiling point as high as 2497°C or higher), making it difficult to reuse carbon materials

[0007] (4) Combustion separation method: Although aluminum electrolysis waste cathode carbon has a calorific value higher than that of coal, generally as high as 4000-5500kcal / kg, but its ignition point is high, it needs to be incinerated in a special incinerator and a fluidized bed, so the combustion method exists The process is cumbersome, the combustion time is long, the energy consumption is large, and the fluoride is difficult to effectively recover, and the secondary pollution is serious

The identification results of the Shandong Aluminum Plant's "Recycling and Utilization of Waste Cathode Carbon Blocks from Aluminum Electrolyzers" organized by China Nonferrous Metals Industry Corporation on November 16, 1988 have not yet been able to replace coal with cathode carbon.

The reasons are as follows: 1. The addition of cathode carbon reduces the coal-fired grinding efficiency; 2. The low-activity graphite carbon seriously reduces the overall combustion performance of coal powder, which affects the working conditions of the kiln system; 3. The lining of the kiln Severe corrosion greatly reduces its service life

[0008] (5) Safe landfill method: The environmental pollution problem of aluminum electrolysis waste cathode carbon has not been effectively solved, resulting in the vast majority of aluminum electrolysis waste cathode carbon still being discarded. If safe landfill is adopted, it can be resolved within a certain period of time Its environmental protection problem, but the method of landfilling and stockpiling electrolytic aluminum solid waste will cause great harm to the environment. Even if it is completely innocuous landfill of hazardous solid waste, it will still produce continuous pollution and cause a lot of pollution. waste of resources

[0011] In the face of prominent environmental problems in the electrolytic aluminum industry, the harmless treatment of electrolytic aluminum hazardous solid waste cannot meet the needs of social, ecological and environmental development