熔融改质含磷钢渣碳热还原回收有价元素试验

 针对含磷转炉渣中磷、铁及锰等有价资源回收及有价元素回收后钢渣资源化利用的问题,通过理论计算、电阻炉试验、感应炉试验等研究手段,系统分析了熔融改质后的含磷钢渣碳热还原回收有价元素的热力学条件和影响规律。研究结果表明,还原温度为1 723 K、碱度为1.0~2.0时,低碱度有利于渣中铁、磷资源的回收;当炉渣碱度为1.0时,Fe₂O₃、P₂O₅、MnO还原率分别可达到99.50%、84.47%和3.26%,渣中铁元素和磷元素收得率分别为99.50%和68.69%;当碱度为1.5时,渣中Fe₂O₃、P₂O₅还原率分别为90.45%和63.73%,与碱度为1.0时相比还原率降低;当碱度为2.0时,渣铁未实现完全分离,渣中Fe₂O₃还原率为71.43%。在感应炉内对熔融改质工业渣碳热还原试验中,在碱度为1.0时,温度为1 723 K条件下,渣中铁元素收得率可以达到99%以上,磷收得率为47.18%;通过热力学分析可以发现,FeO、P₂O₅与MnO相比更容易被碳还原,在试验过程发现,FeO及P₂O₅先还原,反应20 min后渣中MnO开始被还原,整个还原过程中渣中MnO含量略有降低;碳热还原后渣中FeO质量分数仅为0.07%,渣中P₂O₅质量分数为0.93%,MnO质量分数为2.83%;利用FactSage对比改质渣还原前后物相组成可知,还原后渣中含铁物相(Ca₃Fe₂Si₃O₁₂)物相能得到有效控制,磷酸钙质量分数明显减少,渣中橄榄石相大幅度增加,提高了钢渣的应用范围,这为含磷钢渣有价元素回收及资源化利用提供了研究基础。

Recovery of valuable elements from molten modified phosphorous steel slag by carbothermic reduction

For the recovery of valuable elements(Fe,P,Mn) in phosphorus-containing converter slag and the utilization of disposed slag,the thermodynamic conditions and influence laws of carbothermal reduction and recovery of valuable elements from the phosphorous-containing steel slag after melting and reforming were systematically analyzed through the theoretical calculation,experiments in resistance furnace,induction furnace test and other research methods. The research results showed that,the reduction temperature was 1 723 K,the basicity was 1.0-2.0,and the low basicity was beneficial to the reduction of Fe₂O₃ and P₂O₅ and the recovery of Fe and P resources in the slag. When the basicity of slag was 1.0,the reduction rates of Fe₂O₃,P₂O₅ and MnO could reach 99.50%,84.47% and 3.26% respectively,and the recovery rates of Fe and P in slag were 99.50% and 68.69% respectively. When the basicity was 1.5,the reduction rates of Fe₂O₃ and P₂O₅ were 90.45% and 63.73% respectively,which were lower than that of when the basicity was 1.0. When the basicity was 2.0,the reduction rate of Fe₂O₃ in slag was 71.43%,slag and iron was not separated completely. At the condition of that basicity was 1.0,the temperature was 1 723 K,the recovery rate of Fe was over 99% and that of P in the slag was 47.18%,in induction furnace experiments on carbonthermal reduction of molten modified industrial slag. Through thermodynamic analysis,it was found that FeO and P₂O₅ were easier to be reduced by carbon than MnO. At the same time, FeO and P₂O₅ were reduced firstly,and MnO began to be reduced after 20 min in slag,the MnO content in slag decreased slightly during the whole reduction process. at the end of the reduction process. The content of FeO,P₂O₅ and MnO after carbonthermal reduction in slag were 0.07%,0.93% and 2.83% respectively. Using FactSage to compare the phase composition of modified slag before and after reduction,it could be seen that the iron-containing phase(Ca₃Fe₂Si₃O₁₂) in steel slag was effectively controlled,calcium phosphate content decreased obviously,and olivine content increased greatly,which improved the application range of steel slag. A reference for recycling and resource utilization of valuable elements in steel slag containing phosphorus is provided.