含铅锌赤褐铁矿氧化焙烧脱硫性能和机理

Performance and mechanism of oxidative roasting desulphurisation of hematite-limonite containing lead and zinc

针对含铅锌赤褐铁矿中主要以铅、锌、铁等金属硫化物形式存在的杂质硫,在还原焙烧过程中不能被有效脱除而影响铁精矿质量的问题,采用氧化焙烧方式研究含铅锌赤褐铁矿中硫的脱除效果和脱硫机理。通过脱硫率、焙烧前后产物的矿相分析、显微观察鉴定以及拉曼光谱测试等表征方法,研究焙烧温度、焙烧时间对含铅锌赤褐铁矿脱硫效果的影响,探讨含铅锌赤褐铁矿的脱硫机理及金属硫化物的转化过程。研究结果表明:含铅锌赤褐铁矿中硫、铅、锌的质量分数分别为3.34%、1.50%和1.25%,在焙烧温度为600~1050℃和焙烧时间为5~120 min的条件下,氧化焙烧对脱硫过程有不同程度的影响,且随着氧化焙烧温度的提高和焙烧时间的延长,脱硫效果提高。在焙烧温度为1050℃、焙烧时间为60 min的条件下,硫质量分数降至0.25%,总脱硫率可达92.51%,对低价硫的脱硫率达98.64%。随着氧化焙烧温度的提高,焙烧产物中逐渐呈现多孔微小固熔体形貌和表面高温釉质层。脱硫过程主要为FeS_(2)、PbS、ZnS等金属硫化物在高温下发生不同的氧化反应,且铅锌等金属含量无明显变化,说明含硫杂质被氧化为SO2而脱除,反应生成Fe_(2)O_(3)、Fe_(3)O_(4)、PbO、ZnO、PbSO4等物质,少量硫酸盐成为焙烧产物中的残余硫。

Sulphur is mainly present in the form of lead,zinc and iron sulphides when it is found in hematites ores.In order to mitigate the problem caused by different desulphurisation methods especially the reduction roasting which does not effectively remove sulphur but affect the quality of iron concentration,the oxidative roasting method was used to investigate the removal of sulphur from lead-zinc bearing hematites ores and its mechanism.Thus,the sample of hematite ore was subjected to the analysis of mineral phases before and after roasting,microscopic observation and identification,as well as Raman spectroscopy,and the mechanism of desulfurization and the transformation process of metal sulphides in Pb-Zn-bearing hematite were studied.The influences of roasting temperature and roasting time on desulfurization effect were also studied.The results show that the mass fractions of sulphur,lead and zinc in the Pb-Zn-bearing hematite were 3.34%,1.50%and 1.25%,respectively,and the oxidative roasting has different effects on the desulphurisation process at 600-1050℃when the roasting time is between 5-120 min.Under the conditions of roasting temperature of 1050℃and roasting time of 60 min,the sulphur mass fraction is reduced to 0.25%,the total desulphurisation rate reaches 92.51%,and the desulphurisation rate of low-valent sulphur reaches 98.64%.With the increase of oxidation roasting temperature,the roasted products gradually shows porous micro solid melt morphology and high-temperature glaze layer on the surface.The desulphurisation process is mainly composed of different oxidation reactions of FeS_(2),PbS,ZnS and other metal sulphides at high temperature.During the oxidation of sulphur-containing impurities,the reaction produces Fe_(2)O_(3),Fe_(3)O_(4),PbO,ZnO,PbSO4 and other substances,and a small amount of sulphate becomes residual sulphur in the roasted products.