Safe disposal and management of chromium bearing wastes are challenging tasks. Recycling of Cr and Fe metals and production of value-added products from these wastes not only reduce the environmental pollution but are also a compelling necessity. The existing techniques to reduce Cr +6 to relatively non-toxic Cr +3 compound/Cr metal either generate secondary waste, involve high cost or consume huge time. In this work, an attempt is made to reduce Fe and Cr metal oxides present in the chromium bearing waste by plasma assisted aluminothermic process. Chemical composition and leachability of chromium in the waste are analyzed. Aluminothermic reaction mixture is prepared with different weight ratios of waste to aluminium powder. Thermal stability of aluminothermic mixture and ignition temperature of the aluminothermic reaction are studied by TG and DSC analyses. Plasma assisted aluminothermic process is carried out in an argon environment at an atmospheric pressure. The products obtained from the waste are metallic mixture, slag and deposited/evaporated powder. Experiments are carried out at two different plasma powers and processing times. Slag and deposited powders do not contain Cr and Fe. The metallic fraction obtained contains Fe and Cr metals and AlFe 3 alloy. This process can be a suitable method to treat chromium bearing waste effectively without producing toxic products.

中文翻译：

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等离子辅助铝热还原含铬废料中的 Cr 和 Fe 氧化物

含铬废物的安全处置和管理是一项具有挑战性的任务。回收 Cr 和 Fe 金属并从这些废物中生产增值产品不仅可以减少环境污染，而且是一种迫在眉睫的必要性。将Cr +6 还原为相对无毒的Cr +3 化合物/Cr金属的现有技术要么产生二次废物，要么成本高，要么耗费大量时间。在这项工作中，尝试通过等离子体辅助铝热工艺减少含铬废物中存在的 Fe 和 Cr 金属氧化物。分析了废物中铬的化学成分和可浸出性。铝热反应混合物是用不同重量比的废料与铝粉制备的。通过TG和DSC分析研究了铝热混合物的热稳定性和铝热反应的点火温度。等离子辅助铝热工艺是在大气压的氩气环境中进行的。从废料中获得的产品是金属混合物、炉渣和沉积/蒸发的粉末。实验在两种不同的等离子体功率和处理时间下进行。炉渣和沉积粉末不含 Cr 和 Fe。获得的金属部分包含Fe和Cr金属以及AlFe 3 合金。该工艺是有效处理含铬废物而不产生有毒产品的合适方法。炉渣和沉积/蒸发的粉末。实验在两种不同的等离子体功率和处理时间下进行。炉渣和沉积粉末不含 Cr 和 Fe。获得的金属部分包含Fe和Cr金属以及AlFe 3 合金。该工艺是有效处理含铬废物而不产生有毒产品的合适方法。炉渣和沉积/蒸发的粉末。实验在两种不同的等离子体功率和处理时间下进行。炉渣和沉积粉末不含 Cr 和 Fe。获得的金属部分包含Fe和Cr金属以及AlFe 3 合金。该工艺是有效处理含铬废物而不产生有毒产品的合适方法。