Upgradation of bauxite by molecular hydrogen and hydrogen plasma

An approach was developed to upgrade the bauxite ore by molecular hydrogen and hydrogen plasma. A gibbsite-type bauxite sample was obtained from National Aluminium Company（NALCO）, Odisha, India. The obtained sample was crushed and sieved（to 100 μm） prior to the chemical analysis and grain-size distribution study. The bauxite sample was calcined in the temperature range from 500 to 700°C for different time intervals to optimize the conditions for maximum moisture removal. This process was followed by the reduction of the calcined ore by molecular hydrogen and hydrogen plasma. Extraction of alumina from the reduced ore was carried out via acid leaching in chloride media for 2 h at 60°C. X-ray diffraction, scanning electron microscopy, thermogravimetry in conjunction with differential scanning calorimetry, and Fourier transform infrared spectroscopy were used to determine the physicochemical characteristics of the material before and after extraction. Alumina extracted from the reduced ore at the optimum calcination temperature of 700°C and the optimum calcination time of 4 h is found to be 90% pure.

离析焙烧从转炉渣中回收铜

离析焙烧富集工艺,比加筛分或浮选,看来是从渣和氧化矿中提取铜的一种可选择性的途径。本研究使用含2—4％铜的转炉渣,铜以金属形式直接回收。该法包括渣的预焙烧和在碳素物、碱金属或碱土金属氯化物存在下的离析焙烧,最后筛分回收离析的金属。研究了焙烧时间、温度。