Lixiviação de escórias de soldagem a arco submerso visando à recuperação dos óxidos de alumínio e titânio

• Ano de defesa: 2011
• Autor(a) principal: Raquel Annoni
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: meio ambiente; escórias de soldagem a arco submerso; lixiviação; Engenharia metalúrgica
• Link de acesso: http://hdl.handle.net/1843/BUOS-8MSGJY

Nowadays, more than 10 thousand tons of submerged arc welding slags are produced by year in Brazil. This solid waste, generally qualified as acid, neutral or basic according to the welding flux used on the welding process, can be classified as a waste class II, non-inert, according to the Brazilian environmental laws, and it is frequently disposed in landfills. Until this moment, there is no applicable recycling process for this type of waste, and as a palliative way, according to research found on the literature, it can be reused as part of the raw material necessary for producing new welding fluxes or as constituents of building materials. However, this reuse as raw materials for new welding fluxes is very difficult to carry out in a real production plant and more than that, it does not represent an expressive economic saving since the most expensive raw materials for the welding flux production are not present in the slag. Moreover, both landfill disposal and the slag inclusion into building materials imply in metallic value loses. This waste has considerable amount of aluminum and titanium as well as other metals, suggesting the evaluation of hydrometallurgical routes for its treatment. So, the present research work aimed (i) the chemical, mineralogical and morphological characterization of the slags, and (ii) slag leaching using different strategies, varying parameters like type and concentration of the leaching agent (acid and basic), fusion as pre-treatment with different reagents, temperature, sequential operation, addition of oxidizing and reductant agents and others. Evaluating the results it was found that acid submerged arc welding slags have approximately 14% of Al and 10% of Ti, while neutral ones have 12% of Al and 1% of Ti and they are possibly formed by simple oxides and also by other more complex phases, like spinels. The best aluminum extraction were achieved after 2h of leaching, H2SO4 6M solution, 80oC temperature, solid:liquid ratio 1:40g/mL, when 80% of the aluminum was recovered. The best titanium extraction was 31% and it was achieved after 2h of leaching, H2SO4 6M solution, 80oC temperature, solid:liquid ratio 1:40g/mL