摘要
在废旧电路板热解处理过程中,溴化阻燃剂分解产生大量溴化氢,为了减少溴化氢对热解设备和环境的危害,提出了碳酸钙吸附分离溴化氢的处理工艺,生成的溴化钙通过水的浸取、过滤、蒸发、浓缩等过程,获得了质量分数为52%,密度为1.7 g/mL的溴化钙水溶液。研究了热解温度、碳酸钙用量对溴化钙产率的影响规律及溴化钙的浸取工艺条件。热解吸附试验表明,碳酸钙与电路板的质量比为1.2～1.4,热解温度约为600 ℃时,溴化钙的产率最高可达86%;浸取试验表明,溴化钙的单次浸取率随浸取剂的浓度增大而降低,随温度升高而提高。溴的回收率主要取决于溴化钙的产率,通过选择合适的热解吸附条件,废旧电路板中溴的总回收率高于80%,所回收的溴化钙液体产品主要技术指标接近同类市售产品。
The paper has earried the investigations and experiments on the effects of pyrolysis temperature and weight ratio of calcium carbonate to WPCBs on the yield of calcium bromide along with our study of the processing conditions of extracting calcium bromide. As is known, most of the bromine to be recovered here present in bromi- nated flame retardant exist in the form of hydrogen bromide during the pyrolysis of waste printed circuit boards（WPCBs）, with the hydrogen bromide formed to cause severe equipment corrosion and environmen- tal pollution. Therefore, in order to reduce the damage caused by the hydrogen bromide, we have developed actually a new process of ad- sorbing and separating hydrogen bromide from calcium carbonate. Calcium bromide resulted in the given process can be extracted with water, and then 52% wt calcium bromide solution with density of 1.7 g/mL could be obtained through filtrating, evaporating and concen- trating of the calcium bromide extraction solution. The experimental results of pyrolysis and adsorption indicate that the maximum yield of CaBr2 was 86%, when the ealeium carbonate weight ratio to WPCBs remains between 1.2 to 1.4 with the pyrolysis temperature at about 600 ℃. In addition, the extracting experimental results also show that the single extraction rate of calcium bromide which tends to get reduced with the increase of the extraction agent content whereas in- creased with elevation of extraction temperature. Moreover, the calcium carbonate after being regenerated can be recycled to adsorb HBr. However, there remains a small amount of calcium bromide residue in the calcium carbonate that may not be likely to cause any loss of bromine duo to the recycling of calcium earhonate. Thus, the recov- ering rate of bromine mainly depends on the yield of calcium bro- mide, with the total recovering rate of bromine expected to get over 80% by the optimal pyrolysis and adsorbing conditions. The main specifications of calcium bromide solution prepared from our experi- ments with WPCBs are
出处
《安全与环境学报》
CAS
CSCD
北大核心
2010年第1期64-67,共4页
Journal of Safety and Environment
基金
广东省科技计划项目(2006A36703001)
关键词
环境工程学
溴化阻燃剂
溴化钙
废旧电路板
environmental engineering
brominated flame retardant
calcium bromide
waste printed circuit boards
