Lu Xiong,Haisheng Hu,Meitang Liu,Lun Zhuang,Yunfei Li
Graphical The graphical summary shows the preparation of lithium carbonate from α -lithium pyroxene using an alkaline roasting process in a low-energy method. This new method achieves the full utilization of spodumene with lower energy consumption and demonstrates great potential for industrial applications. Extracting lithium from spodumene by sulfuric acid roasting is the largest commercialized way at present, which not only consumes a large amount of energy but also produces massive waste residue that will cause environmental problems. In this work, a new process for extracting lithium by directly decomposing α -spodumene through alkali calcination is designed. The reaction of α -spodumene with Na 2 CO 3 at 750 °C for 2 h can decompose it and form nepheline and lithium silicate/sodium silicate. The nepheline and soluble lithium silicate/sodium silicate are separated by water leaching, and 93.9 % of lithium can be leached under optimal conditions. In addition, the synthesis of nano-kaolinite is investigated with nitric acid solutions. Conversions of 98.7 % were obtained with 0.4 M nitric acid at 250 °C and an L/S ratio of 17.5 L/kg. The water leachate can precipitate Li 2 CO 3 with a purity of 99.0 % by CO 2 after desilicated by CaO. The final yields of Li 2 CO 3 and kaolinite relative to the Li and Si content of the starting minerals are 91.4 % and 48.5 %, respectively. This new method achieves the full utilization of spodumene with lower energy consumption and demonstrates great potential for industrial applications.
Spent carbon cathode is a hazardous solid waste generated from aluminum electrolysis industry, which can be used as a potential resource for the preparation of high-purity graphite. This study aims to propose a purification method combining activation roasting and hot pressing acid leaching on the basis of the traditional methods for the purification of waste cathode graphite. The results show that KOH activated roasting can not only purify the waste cathode, but also leave a large number of holes and cracks on the surface of the waste cathode to increase the specific surface area and porosity, thus destroying its structure to open up the internal channels, which is conducive to the subsequent injection of high-temperature and high-pressure in-depth removal of the internal impurities of the mineral by hot pressing acid leaching. Under the optimal process conditions, the removal rate of fluoride ions can reach 99.933%, and the removal rates of sodium (Na), aluminum (Al), calcium (Ca), and silicon (Si) can reach 99.32, 99.74, 99.36, and 97.61%, respectively, and the purity of regenerated high-purity graphite products reaches 99.914%. At the same time, the reaction mechanism of KOH activated roasting and hot pressing acid leaching was investigated and analyzed, and this study can provide a new way of thinking for the recycling of aluminum electrolysis waste cathode to prepare high purity graphite, which is not only a simple and low-cost process compared to the traditional purification methods, but also can be applied to the recycling of other waste graphite, which has the potential prospects for industrial applications.
危险品化学品经营许可证（带存储）