| 摘要 |
Spent potliner from aluminum reduction cells includes carbon, inorganic brick and refractory material, and fluoride, sulfur, and cyanide compounds, and is considered hazardous. It is treated by introducing it into a vessel, and exposing it to the heat of a plasma torch at a temperature of at least 1000 DEG C. As a result, carbon is gasified and converted to combustible carbon monoxide or hydrocarbons, or to carbon dioxide; inorganic material is melted form slag; fluoride compounds are melted, vaporized, or reduced to gaseous HF; cyanide compounds are destroyed; and all other materials, including sulfur compounds, are either melted or gasified. As a result, the spent potliner is rendered non-hazardous, and the quantity of remaining slag has both its solid volume and mass substantially reduced by a factor of at least 1.5:1 in mass and at least 3:1 in volume relative to the input spent potliner. The process allows gaseous fluoride compounds to be captured and thermal energy produced in the process to be extracted. The molten slag material produced within the vessel is removed from the vessel, and cooled to form a solid slag which is substantially free of cyanide compounds, resistive to leaching, and safe for disposal. The slag has commercial utility. Combustible carbon compounds can be captured and used. When carried out at an aluminum smelting site, adequate electrical power is readily available, and there is an in situ demand for recovered fluoride compounds, combustible gases, and extracted heat. |
