废镍镉电池的真空蒸馏回收技术

Ni-Cd battery recycling technology using high-temperature vacuum distillation

废镍镉电池是城市生活垃圾中重金属的主要来源之一,所以必须在进入焚烧炉以前分离出来并妥善处理。利用自行设计的真空辅助回收装置,对废镍镉电池的真空高温分解及镉的挥发冷凝的基本规律进行了研究。实验结果表明:利用真空蒸馏可以实现镍镉电池中镉与其它金属的有效分离,并得到纯度大于99%的金属镉;在真空高温条件下,镍镉电池中的主要可挥发物质为水、有机物和镉;系统真空度为67mPa时,镉的有效蒸馏温度区间为573～1173K;压强为10Pa,在773～1173K之间,温度升高时镉在蒸馏剩余物中含量显著降低;蒸馏温度为1173K,在80～20Pa之间降低压强,蒸馏剩余物中镉含量呈降低趋势;当系统温度为1173K,压强为10Pa,蒸馏时间大于3h后,剩余物中镉的含量小于0.2%。

 The wide use of municipal solid waste incinerators has increased concern over heavy metal pollution. Spent NiCd batteries, the main source of the heavy metal cadmium, should be removed and handled properly before the municipal solid waste is put into the incinerator. An experimental recovery system was designed to develop a process for disassembling and recovering selected materials from NiCd batteries using high temperature vacuum distillation of the NiCd batteries because of the distinct difference between cadmium and other metals. The results showed that the heavy metal cadmium could be effectively separated by vacuum distillation to produce high purity cadmium (>99%). Water, organic substances and cadmium became vapor at high temperature in the vacuum system. The cadmium boiling point of was about 750 K at a heating rate of 2.5 K/min at 67 mPa. The distillation temperature should be at the range of 773 K to 1 173 K. At 10 Pa and a distillation temperature of 1 173 K, the cadmium content in the residue was less than 0.2% after distillation for 3 h. 