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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As_4O_6(g)等气态物质脱除。除尘灰中砷以固态As_2O_3(s)和As_2O_5(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As_4(g)挥发,在400℃以下析出单质砷。
In order to study the arsenic removal of iron ore sintering and dust removal, the effects of different partial pressure of oxygen, temperature and alkalinity on the arsenic removal rate, arsenic balance composition and final arsenic removal status of arsenic-bearing iron ore were studied by FactSage software. The thermodynamic study on deash arsenic removal was carried out. The sintering experiment was carried out with the sintering cup and verified by roasting and dust-removing test in multi-atmosphere. The XRD, SEM and EDS were used to analyze the ore phase. The results showed that the removal of arsenic products and arsenic removal rate and temperature, oxygen partial pressure and alkalinity are closely related. In the sintering process, the arsenic remained in the sinter is mainly solid arsenate, other arsenic will be As_4O_6 (g) and other gaseous substances removed. Ashing arsenic to solid As_2O_3 (s) and As_2O_5 (s) exist. Roasting dust in an air or anaerobic atmosphere can convert arsenic to arsenate. However, when using matching pulverized coal and anaerobic conditions, the dust is calcined at 600 ℃ or above to volatilize arsenic to As_4 (g) in the gaseous phase and to precipitate simple arsenic below 400 ° C.