Simbiose industrial: SPL do alumínio primário ao coprocessamento na indústria cimenteira

• Autor(a) principal: ORSINE, Alberto Rossine Antunes
• Data de Publicação: 2015
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UNIFACS
• Texto Completo: http://teste.tede.unifacs.br:8080/tede/handle/tede/435
• topic: Spent Pot Lining (SPL); Impactos ambientais; Simbiose Industrial; Engenharias

Spent Pot Lining (SPL) is a solid waste produced by the aluminium industry during the manufacture of aluminium metal in electrolytic cells. After years of operation, the cathode liner materials deteriorate and affect the cell´s performance and need to be replaced. The waste cathode lining consists of a carbon part and a refractory part. SPL contains water-soluble fluorides and small amounts of leachable cyanides. Due to the high fluoride and cyanide content SPL was listed as hazardous waste by the US Environmental Protection Agency in the year 1988. In Brazil, according to the Brazilian Standards NBR 10004, the SPL is listed as a hazardous waste (K088) content of cyanide. SPL is indicated as the major environmental problem in the aluminium industry. The lining during operation of the cells, is subject to strong reducing conditions and fails by a variety of mechanisms depending on how the cell was projected, constructed, designed and operated. Based on current production levels, it is estimated that a significant amount of SPL (more than 50 %) is still stored in buildings lined or unlined sites, waiting for treatment. SPL can be used by cement industry. There are advantages to the cement process as SPL has a reasonable calorific value and fluorides reduce the kiln temperature. The technological requirements of this industry make it particularly well suited to the use of fuels made from waste. Such fuels must be characterized by a suitable amount of chemical energy, which depends on the nature of the components and on the organic matter content. This work presents a case study of environmental impact on the area in which SPL was landfilled for about 18 years. During this period of time the fluoride and cyanide concentrations were measured on a weekly basis. It was observed that the fluoride and cyanide concentrations were increasing and exceeding the allowed limits. A study was conducted to assess the extent of the impact. It was found that the landfill was not working properly. As a first action for remediation it was determined a complete removal of the landfill and its transportion to the cement industry for use in full. In respect to this case it was observed that the proper management of SPL is characterized as industrial symbiosis process, since is generated by the aluminum industry and co-processing by Portland cement, where carbon content works as a source of secondary energy and the other components (oxides of aluminum, iron, calcium, silicon) and fluorides as secondary raw materials, minimizing environmental liabilities and preserving natural resources.