(中南大學(xué) 資源加工與生物工程學(xué)院，長沙 410083)
摘 要: 對含砷鐵精礦球團(tuán)在中性、氧化和還原性氣氛以及預(yù)氧化-還原焙燒過程中砷的揮發(fā)行為進(jìn)行研究；并結(jié)合熱力學(xué)分析，揭示不同氣氛下砷揮發(fā)的機(jī)理。結(jié)果表明:含砷鐵精礦球團(tuán)在中性、弱還原性氣氛或經(jīng)預(yù)氧化-弱還原焙燒，均能實(shí)現(xiàn)砷的有效揮發(fā)。將含砷鐵精礦球團(tuán)在850 ℃、100% N2氣氛下焙燒10min，砷揮發(fā)率達(dá)到79.33%，砷含量由0.11%降低至0.023%；在950 ℃、5%H2、9.5%CO、85.5%CO2(體積分?jǐn)?shù))的弱還原氣氛下焙燒10 min，砷揮發(fā)率為82.47%，殘余砷含量僅為0.020%；球團(tuán)在空氣氣氛下經(jīng)750 ℃預(yù)氧化10 min后，再經(jīng)950 ℃、5%H2、9.5%CO、85.5%CO2條件下還原20 min后，砷的揮發(fā)率達(dá)到81.76%，殘余砷含量為0.021%。砷揮發(fā)機(jī)理的研究表明，砷在不同氣氛下能夠以As2(g)、As4(g)或As2O3(g)的形式揮發(fā)；但是氧化或還原氣氛過強(qiáng)將分別生成砷酸鐵和砷化鐵影響砷的脫除。
關(guān)鍵字: 砷；含砷鐵精礦；焙燒；氣氛；揮發(fā)
（School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China）
Abstract:Arsenic volatilization behavior of As-bearing iron concentrate pellet was studied in various atmospheres, such as neutral, oxidation, reduction and by preoxidation-weak reduction roasting. The results show that arsenic can be volatilized by roasting in the above mentioned atmosphere except oxidation atmosphere. The results show that arsenic volatilization ratio of 79.33% is obtained when roasted at 850 ℃ for 10 min in N2 atmosphere and the residual As content decreases from 0.11% to 0.023%. Under the conditions of 950 ℃ for 10 min in reduction atmosphere of 5% H2 and 10% CO/(CO+CO2), As volatilization ratio and residual As content are 82.47% and 0.020%, respectively. When the pellet was preoxidized at 750 ℃ for 10 min in air and subsequently reduced at 950 ℃ for 20 min with 5% H2 and 10% CO/(CO+CO2), As volatilization ratio of 81.75% is achieved and the residual As content decreases to 0.021% correspondingly. The volatilization mechanisms of arsenopyrite reveal that As is capable of being volatilized in the form of As2(g), As4(g) as well as As2O3(g). However, FeAsO4 and FeAs are likely generated at higher oxidation and reduction potential, respectively, which will inhibit the volatilization of As.
Key words: arsenic; arsenic-containing iron concentrate; roasting; atmosphere; volatilization
