Because of high iron content, hematite precipitate is a potential marketable byproduct as a material in the steel making, cement and pigment industries. While, sulfur content is a key factor which affects the hematite quality and its utilization as a resource. The residual sulfur in hematite precipitate is attributed to the part existing as metastable jarosite, irreversible absorption of SO42? ions and basic ferric sulfate, and jarosite appears to be the main sulfate-contaminating phase. The results shows that temperature is the key factor which affects the formation and conversion of metastable jarosite. Therefore, jarosite becomes thermodynamically unstable and to converses into hematite with increasing temperature. It is advantage for metastable jarosite conversion and obtaining high quality hematite precipitate with higher iron content and lower sulfur content by decreasing initial sulfuric acid concentration, prolonging retention time and addition of seed. High quality hematite precipitate with Fe, S and Na content of 66.6%, 0.92% and 0.033%, respectively, and with iron precipitation ratio of 95% are obtained under the condition as follows: initial solution containing 30 g/L ferrous ion, 0.15 mol/L sodium sulphate and 1.6×10?4mol/L initial acid, temperature of 200 ℃, oxygen partial pressure of 400 kPa, reaction time of 180 min and agitation speed of 500 r/min.%赤铁矿渣由于铁含量高,存在极大潜力作为副产品销售给钢铁、水泥制造以及涂料行业,从而实现铁资源化利用,硫含量是影响赤铁矿品质并实现其资源化利用的重要因素之一.赤铁矿渣中硫主要以亚稳态的铁矾、SO42?的不可逆吸附以及碱式硫酸铁等形式存在,其中铁矾是硫的主要存在形态.FeSO4-H2O体系中Fe(II)氧化水热水解赤铁矿沉铁及过程亚稳态铁物相转化研究表明:温度是影响亚稳态铁矾物相形成和转化的关键因素,升高温度亚稳态铁矾的热力学稳定性变差,有利于其向赤铁矿转变.降低初始硫酸浓度、延长反应时间、添加晶种均会促进Fe(II)氧化水解,也有利于亚稳态铁矾物相向赤铁矿转变,从而获得铁含量高、硫含量低的高品质沉铁渣.在初始Fe2+浓度30 g/L、Na2SO4浓度0.15 mol/L、初始酸浓度1.6×10?4mol/L、温度200 ℃、氧分压 400 kPa、反应时间180 min、搅拌转速500 r/min的优化技术参数下,Fe(II)氧化水热水解赤铁矿沉铁过程中沉铁率为95%,获得不含亚稳态铁矾的赤铁矿沉铁渣,其中铁、硫和钠硫含量分别为66.6%、0.92%和0.033%(质量分数).
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