Processing of quartz lumps rejected by silicon industry to obtain a rawmaterial for silica glass

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)This work aimed at analyzing quartz lumps rejected from a major metallurgical grade silicon producer and at studying the effect of several processing techniques over its purification. The final objective was to enable the use of these lumps as a raw material for silica glass production. Chemical analyses using ICP-MS technique were conducted to understand the nature of the chemical impurities in the rejected lumps, aiming to identify rather if the impurity was inside or outside the quartz lattice. The processing procedures were divided in two steps, the first consisting of only a physical treatment and the second one consisting of a chemical treatment. The physical treatment consisted of washing, milling (and separating the material by its particle size) and magnetic separation. This treatment reduced most of the impurities present in quartz, purifying over 90% of the Fe contamination and over 60% of the Al contaminations, but it was incapable of producing a powder with similar chemistry to commercial raw materials. The chemical treatment was conducted using two different acid mixtures (dilute HC1 and dilute HC1 + HF). Interesting results were obtained using the HF containing mixtures. These mixtures were able to produce a powder with commercial purity (with Al impurities lower than 50 ppm). This treatment was also able to reduce lattice impurities. (C) 2015 Elsevier B.V. All rights reserved.This work aimed at analyzing quartz lumps rejected from a major metallurgical grade silicon producer and at studying the effect of several processing techniques over its purification. The final objective was to enable the use of these lumps as a raw mater1356570CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)sem informaçãosem informaçãosem informaçãoAuthors would like to acknowledge Capes, CNPq and FAPESP for individual financing. They would also like to acknowledge the company Beneficiamento de Minérios Rio Claro Ltda. (BMRC Mineral Technology) for the technical support and fundin