高砷河道尾砂还原焙烧脱砷研究

Experiment Research on Removal of Arsenic in the High Arsenic Tailings by the Reducing Roast Method

【目的】对河道尾砂富集分离形成的高砷尾砂进行脱砷处理,使之达到高炉冶炼的要求。【方法】在前期氧化焙烧脱砷研究的基础上,分别采用煤基还原焙烧工艺和气基还原焙烧工艺对含砷量为0.47%的河道尾砂氧化焙烧渣进行脱砷试验。考察焙烧温度、时间、还原气氛CO/(CO+CO_2)和空气流速等主要影响因子对脱砷效果的影响。【结果】气基还原焙烧的脱砷效果优于煤基还原焙烧。气基还原焙烧的适宜条件:焙烧温度900℃、焙烧时间约30min、CO/(CO+CO_2)浓度20%、气体流量0.5m3/h;在适宜的气基还原焙烧条件下,焙烧尾砂中砷的含量可降至0.058%,脱砷率达87.66%。【结论】经气基还原焙烧工艺得到的河道尾砂还原焙烧渣能满足高炉炼铁的要求。

【Objective】After river sand separation,the high arsenic tailings were formed,of which arsenic removal treatment was performed to meet the requirements for iron making.【Methods】Based on the preliminary study of arsenic removal by oxidizing roast,both the coal-based and the atmosphere reduction roasting processes were used to remove the arsenic in the river tailings' oxidizing roasting slag,of which the high arsenic content was up to 0.47%.The impact of major factors on the arsenic removal efficiency were investigated,including calcination temperature and time,reducing atmosphere and air flow.【Results】The results showed that the atmosphere reductive roasting process exhibited higher efficiency in arsenic removal from the oxidi-zing roasting slag than the coal-based reduction roasting process.The optimum conditions of atmosphere reductive roasting process were further ascertained.The best calcination temperature was 900℃ and the roasting time was about30 min.Meanwhile,the suitable concentration of CO/(CO+CO_2)was 20% and the gas flow was0.5 m^3/h.Under above demonstrated appropriate conditions of reduction roasting,the arseniccontent of oxidizing roasting slag could be reduced to 0.058%,and the corresponding arsenic removal efficiency reached to 87.66%.【Conclusion】The reduction roasting slag obtained by atmosphere reductive roasting treatment can completely meet the requirements of blast furnace smelting on raw material.