ABSTRACT

The reduction roasting followed by magnetic separation process is considered to be a suitable method to treat the high-phosphorus oolitic iron ore. Currently, the dephosphorization mechanism of additives such as CaCO₃, Ca(OH)₂, Na₂SO₄, and Na₂CO₃ on the reduction roasting of the iron ore in which phosphorus occurs in apatite have been thoroughly studied. The effect of sodium salts (Na₂CO₃, NaCl and Na₂SO₄) on reduction roasting and magnetic separation of high-phosphorus oolitic iron ore containing phosphorus in iron oxides was investigated, and the mechanisms of sodium salts were expounded using XRD and SEM-EDS. The results show that the dephosphorization ability of sodium salts was in the order of Na₂SO₄> Na₂CO₃> NaCl>no sodium salts. Na₂CO₃ and Na₂SO₄ transferred Fe₃PO₇ from the iron oxides to nepheline, which upgraded the separation of iron and phosphorus. However, NaCl did not inhibit the reduction of phosphorus in the iron minerals. In addition, Na₂CO₃ strengthened the reduction of iron oxides. However, a small amount of wustite failed to be reduced to metallic iron with the addition of NaCl, and troilite and wustite formed hindered the reduction of iron minerals after adding Na₂SO₄.

摘要

还原焙烧后磁选工艺被认为是处理高磷鲕状铁矿石的合适方法。目前，已深入研究了CaCO ₃、Ca(OH) ₂、Na ₂ SO ₄、Na ₂ CO ₃等添加剂对磷灰石中含磷铁矿石还原焙烧的脱磷机理。钠盐（Na ₂ CO ₃、NaCl 和 Na ₂ SO _{4 ）的影响})研究了氧化铁中含磷的高磷鲕状铁矿石的还原焙烧和磁选，并利用XRD和SEM-EDS阐明了钠盐的形成机理。结果表明，钠盐的脱磷能力顺序为Na ₂ SO ₄ > Na ₂ CO ₃ > NaCl>无钠盐。Na ₂ CO ₃和Na ₂ SO ₄将Fe ₃ PO ₇从氧化铁中转移到霞石上，提高了铁和磷的分离效率。然而，NaCl并没有抑制铁矿物中磷的还原。此外，Na ₂CO ₃加强了氧化铁的还原。但加入NaCl后，少量方晶石未能还原成金属铁，而形成的陨硫铁和方晶石阻碍了加入Na ₂ SO ₄后铁矿物的还原。