Recycling valuable metals from wastes by means of mechanochemical processing

采用机械化学法从各类废渣中回收稀有金属，开发了共磨加水浸回收稀有金属新工艺。通过与添加剂共磨含稀有金属的废料来刺激固相反应，以将目标金属的状态转变为易于回收的可行状态，例如水浸。根据目标元素的存在状态选择共研磨添加剂。2003年，通过机械刺激固相反应从二次电池正极材料中用聚氯乙烯研磨生成氯化物来回收钴是一项研究目标。由于氯化物在水中容易溶解，用水浸出地面样品回收金属。2004年，对使用钼、钒、钴和镍的硫化物的炼油工业的废催化剂进行了处理。在不加热的情况下，通过与CaO共磨来测试这些硫化物的氧化性能。人们已经发现，氧化这些硫化物是可能的。在用水浸出这些地面样品时，钼酸钙或钒酸钙的生成导致得率低。硫化物与MnO_2、碳酸钠共磨，生成易溶于水的钼酸钠和钒酸盐。对磨矿时间、添加摩尔比等实验参数进行了试验，确定了最佳实验条件，钼的回收率可达90%以上。水浸后，可用酸性溶液浸出钴、镍。采用碱液进一步浸出回收钒。目前正在与相关公司讨论实际应用的可能性，机械化处理有望为稀有金属的可持续供应做出贡献。

A new process composed of co-grinding and subsequent water leaching to recover rare metals from various types of waste has been developed by means of mechanochemical treatment. A solid state reaction is stimulated by co-grinding the rare-metal-containing waste with additives to transform the state of target metals into a feasible state for easy recovery, water leaching for example. Additive for co-grinding is chosen based on the existing state of target element.In 2003, a research target was put at the recovery of cobalt from cathode material of secondary battery by grinding with PVC to form chlorides through the mechanically stimulated solid state reaction. The metal is recovered by leaching the ground sample with water due to the easy dissolution of chlorides in water.In 2004, an effort is put on the treatment of waste catalysts from oil refinery industry where sulfides of molybdenum, vanadium, cobalt and nickel are used. Oxidization of these sulfides was tested by co-grinding them with CaO without heating. It has been found that it is possible to oxidize these sulfides. The formation of calcium molybdate or vanadate leads to the low yields when water leaching these ground sample.In 2005, manganese dioxide (MnO_2) was used as additive. Co-grinding sulfides with MnO_2 and sodium carbonate results in the formation of sodium molybdate and vanadate, which are easily dissolved in water. Several experimental parameters such as grinding time, adding molar ratio have been tested and the optimum experimental conditions have been determined to obtain recovering yield as high as 90% for molybdenum. After water leaching, leaching with acid solution can be applied to leach cobalt and nickel. Further leaching with alkali solution is applied to recover vanadium. The potential for practical application is under discussion with related company and contribution of the mechanochemical processing is expected to sustainable supply of rare metals.