报废动力电池镍钴锰酸锂三元正极材料高温氢还原−湿法冶金联用回收有价金属

通过高温氢还原和湿法冶金联用的方法回收报废动力电池镍钴锰酸锂三元正极材料中的镍、钴、锰以及锂金属,并对其回收机理及工艺进行研究。结果表明:报废三元正极材料经过高温氢气还原后,在层状镍钴锰酸锂结构中的锂迁移到表面,变成LiOH、LiOH∙H2O和少量的Li2CO3;镍钴锰由之前的Co^2+、Ni^3+和Mn^4+分别还原成了Co0、Ni0和MnO,其在还原水洗后物料的表面相分别为Ni(OH)2和Co(OH)2及MnO;还原后的LiOH、LiOH∙H2O和少量的Li2CO3经过水浸、酸洗、沉淀后,可得纯度为99.5%的Li2CO3,实现了锂与镍、钴、锰的分离;还原后的镍、钴和MnO经过硫酸酸浸后,镍、钴和锰浸出率分别为96.88%、97.23%和99.78%。浸出后溶液经氧化沉淀及萃取分离,锰沉淀分离率为98.46%,萃取分离后氯化钴和氯化镍溶液杂质含量低于10 mg/L。

铁中硅元素对铝/铁复合板界面金属间化合物生长的影响

使用SEM,EBSD研究(480~640)℃1h退火后,铁中添加不同的硅含量(u(Si)=0.82%,1.48%,3.26%)对铝/铁复合板界面金属间化合物生长的影响。结果表明:(480~640)℃1 h退火后,未添加硅的铝/铁复合板在界面处均生成连续金属间化合物,随着退火温度升高,金属间化合物厚度增大,当退火温度超过620℃时,界面金属间化合物形貌由较为平直转变为舌状突起;640℃1 h退火后,界面金属间化合物厚度随铁中硅元素含量的增加呈指数型减小,未添加硅的铝/铁复合板界面金属间化合物厚度在35 μm以上,而铁中添加ω(Si)=3.26%的铝/铁复合板界面金属间化合物厚度为20 um左右;铝/铁复合板界面金属间化合物主要为Fe_(2)Al_(5),少量的Fe_(4)Al_(13)分布在靠近铝侧和分散在Fe_(2)Al_(5)中;铁中添加ω(Si)=1.48%时,界面金属间化合物同样包括Fe_(2)Al_(5)及少量的Fe4Al13,其分布与不加硅的铝/铁复合板的类似,只是其界面还生成了含硅的Fe_(3)Al_(2)Si_(3)和FeAl_(2)Si相,他们弥散分布于靠近铁侧的Fe_(2)Al_(5)中。

Discussion of Environmental Problem and Study of Environmental Impact on Steel Industry in China

The environmental conditions in steel industry were discussed in detail.It was also pointed out that it was necessary to reduce the quantity of waste generated and discharged by improving the raw material,energy structure and consumption rate,and reinforcing the waste control and management.At the same time,the relevant mathematical models of environmental impact were set up on the basis of raw material consumption,energy consumption and waste generation and discharge in different technical routes of steelmaking.The result showed that the production route of DR-iron clearly has more environmental advantages over that of BF-hot metal.