An environmentally benign and sustainable process for carbon recovery and efficient defluorination of spent carbon cathode

一种实现废阴极炭回收以及高效脱氟的环保可持续工艺

A systematic and green low-temperature sulfation roasting−water leaching strategy was put forward to achieve a very high fluorine removal rate of 97.82%for spent carbon cathode(SCC),which was believed as a hazardous solid waste.And the carbon could be recycled with a purity of 90.29 wt.%in the flaky microstructure.Thermodynamic analysis and the results of SEM,XRD and EDS indicate that most of the fluoride could convert into water-soluble sulfate at low temperature.And the highest fluorine removal rate could be obtained when<0.15 mm SCC particles were mixed with sulfuric acid at a liquid-to-solid ratio of 1:1,and then roasted at 300℃ for 0.5 h.The sulfate was removed to purify the carbon via water-leaching process.Avrami exponents and corresponding activation energy for the roasting and leaching process demonstrated that both processes are controlled by diffusion.

提出一种系统、绿色的低温硫酸化焙烧−水浸工艺,危险固体废弃物废阴极炭块的脱氟率可达97.82%,同时,片状回收炭纯度达90.29%(质量分数)。热力学分析和SEM、XRD及EDS结果表明,大部分的氟化物可以在较低的温度下转化为水溶性的硫酸盐。结果表明,将<0.15 mm的废阴极颗粒与浓硫酸以1:1的液固比混合,然后在300℃焙烧0.5 h可实现最佳的脱氟效果。进一步通过水浸去除硫酸盐实现炭的纯化。同时,焙烧和浸出过程的Avrami指数和相应的活化能表明这两个过程均受扩散控制。