还原剂与脱硫剂对硫酸渣直接还原焙烧同步脱硫的影响

Influence of the reducing agent and desulfurizer on desulfurization froma sulfuric acid residue by using direct reduction and roasting

研究了还原剂云南煤和脱硫剂SH对硫酸渣在直接还原焙烧过程中提铁降硫效果的影响.采用X射线衍射与扫描电镜方法分析了云南煤与脱硫剂SH的作用机理.结果表明:在高温还原气氛下,硫酸渣中的黄铁矿生成具有挥发性的气态单质硫和气态羰基硫、金属铁和非磁性的陨硫铁;硫酸渣中的赤铁矿和磁铁矿则被还原为金属铁;云南煤对硫酸渣在焙烧过程中的脱硫效果比较明显,但无法达到要求的指标;添加脱硫剂SH可以进一步降低还原铁中的硫,其机理是脱硫剂与硫酸渣中的黄铁矿在直接还原焙烧过程中反应生成金属铁和没有磁性的硫化钙,通过磨矿--磁选的方法将硫化钙与金属铁分离,从而达到脱硫目标.

The effects of Yunnan coal as a reducing agent and the desulfurizer SH on the improvement in iron grade and the desulfurization of a sulfuric acid residue were investigated in direct reduction and roasting processes. The mechanisms of action of Yunnan coal and the desulfurizer SH were analyzed by X-ray diffraction and scanning electron microscopy. It is shown that in the high-temperature reducing atmosphere, volatile elemental sulfur and carbonyl sulfur, metallic iron and nonmagnetic troilite are produced from pyrite in the residue. Magnetite and hematite in the residue are reduced into iron. In the roasting process of the residue, Yunnan coal has obvious desulfurization effect; however it cannot meet the requirement. The addition of the desulfurizer SH can reduce sulfur further more. Its mechanism of action is that in the direct reduction and roasting processes, the desulfurizer and pyrite generate iron and calcium sulfide without magnetic, which can be separated by a grinding and magnetic method, so the aim of desulfurization is reached.