Extraction of lithium from beta-spodumene using routes with simultaneous acquisition of zeolitic structures

• Autor(a) principal: Santos, Leonardo Leandro dos
• Data de Publicação: 2018
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UFRN
• Texto Completo: https://repositorio.ufrn.br/jspui/handle/123456789/26932
• topic: CNPQ::ENGENHARIAS::ENGENHARIA DE MATERIAIS E METALURGICA; Beta-spodumene; Lithium extraction; Li2CO3; High-throughput screening; Zeolites

The expected increase in demand for lithium salts raises a growing concern regarding this metal scarcity and environmental issues in the national industry of lithium extraction in tilled reserves. The methodologies applied in lithium extraction are associated with the use of sulfates, organic and actinide-based solvents that leads to the formation of sulfated silico-aluminum by-products and radioactive waste. Therefore, this study aimed to develop and to design environmentally efficient routes in order to extract lithium in salt form from beta-spodumene (β-LiAlSi2O6) and technologically feasible routes to simultaneously obtain zeolites as a by-product. A literature review describes techniques to extract lithium using sulfated additives with by-product recovery after the synthesis process, which indicates that this research is considered unprecedented for having obtained zeolitic crystalline structures formed in the lithium extraction route. In order to elaborate efficient and economically feasible extraction routes, a prior understanding of the attributes of molecular sieves was necessary, in particular, the zeolite types. Thus, the efficiency of lithium extraction using Na2CO3, NaOH e NaCl additives was evaluated through the measurement of atomic absorption in the supernatant, based on chemoselective ion exchange between Li+ from β-LiAlSi2O6 and Na+ from Na2CO3 and NaCl, resulting in up to 85% of extracted lithium. The addition of NaOH promoted the mineralization for the dissolution of β-LiAlSi2O6, enabling the recovery of Li and the availability of Si and Al for the nucleation and the development of zeolite structures. As a result, two routes were developed operating in the closed and continuous circuit (HTS: high-throughput screening). Each route consisted of different stages such as calcination, hydrothermal treatment, and the use of bicarbonate for the dissolution and precipitation of the associated lithium salt, besides the recovery of new materials like as by-products of cage (LTA and FAU) or channel (LTT, MOR, and MFI) zeolitic topology. At last, in order to validate the strategies used, the materials were categorized applying techniques such as XRD, XRF, TGA, ICP, N2 adsorption isotherms, SEM, TEM and FT-IR with adsorbed pyridine.