含砷铁矿石烧结及除尘灰焙烧脱砷热力学

 为了研究铁矿石烧结及除尘灰焙烧脱砷问题，运用FactSage软件研究了不同氧分压、温度及碱度对含砷铁矿石烧结脱砷率、砷平衡组成、脱砷最终形态的影响，并对除尘灰焙烧脱砷流程进行热力学研究。结合烧结杯进行烧结试验，并在多气氛下利用焙烧除尘灰试验进行验证，运用XRD、SEM及EDS对矿相进行分析。结果表明，脱砷产物及脱砷率与温度、氧分压及碱度密切相关。在烧结过程中，残留在烧结矿中的砷，主要是固态砷酸盐，其他砷会以As4O6（g）等气态物质脱除。除尘灰中砷以固态As2O3（s）和As2O5（s）存在。在空气或厌氧气氛下焙烧除尘灰，会使砷转变为砷酸盐。但采用配比煤粉及厌氧条件下，在600 ℃以上焙烧除尘灰，可使砷以气态As4（g）挥发，在400 ℃以下析出单质砷。

Thermodynamics of arsenic removal from arsenic-bearing iron ores with sintering process and dust ash by roasting

In order to study the arsenic removal by sintering of iron ore and roasting of dust ash,the effects of different oxygen partial pressures,temperatures and basicities on the equilibrium compositions,dearsenication rate about arsenic-bearing ores with sintering,and the final morphology of arsenic were investigated by FactSage thermodynamic analysis software,and thermodynamic study on the process of arsenic removal by roasting from dust ash was carried out. Sinter-ing test was carried out in combination with sintering cup,and the roasting experiment about dust ash in multi atmo-sphere was carried out to verify the thermodynamic analysis. The XRD,SEM and EDS were used to analyze the ore phases. The research results show that arsenic removal product and dearsenication rate are closely related to the tempera-ture,oxygen partial pressure and basicity. In the process of sintering,the residue of arsenic in the sinter mainly exists in the solid state arsenate,and the other arsenic is removed in gaseous As4O6(g).The arsenic in the dust ash exists in solid state As2O3(s)and As2O5(s). In the air or anaerobic atmosphere,arsenic transfers into arsenate as roasting of dust ash. However,roasting of dush ash with added coal above 600℃could cause the arsenic to be volatilizedasg as eous As4(g), and precipitated as arsenic below 400℃.