论文部分内容阅读
世界对铁矿石需求的不断增长导致磁铁矿资源逐渐枯竭,高磷铁矿的利用成为焦点.分别以碳酸钙(CaCO3)、氯化钙(CaCl2)、硫酸钙(CaSO4)为添加剂,使用直接还原-磨矿-磁选的方法,从热力学、铁金属化率、矿物组成和微观结构等方面研究了高磷铁矿(磷主要以Fe3PO7和磷灰石形式赋存)直接还原提铁降磷的过程.结果表明:在无钙化合物条件下,Fe3PO7中的磷被还原为单质磷,磷和金属铁反应生成铁磷合金,导致还原铁产品中磷含量高.CaCO3促进了赤铁矿和磁铁矿的还原,提高了铁金属化率,但抑制了金属铁颗粒的生长.CaCl2有利于金属铁颗粒的长大,由于挥发性FeCl2的生成,降低了铁的回收率.CaSO4促进了铁颗粒的生长,由于非磁性FeS的生成,铁的回收率急剧降低.CaCO3、CaCl2或CaSO4均可与Fe3PO7反应生成磷酸钙(Ca3(PO4)2).添加CaCO3生成的Ca3(PO4)2与细小铁颗粒结合紧密,通过磨矿磁选难以铁磷分离,还原铁产品中磷含量为0.18％.添加CaCl2或CaSO4,生成的Ca3(PO4)2与金属铁颗粒的界限明显,磷通过磨矿磁选除去,还原铁产品中磷含量低于0.10％.“,”The increasing demand for iron ore in the world causes the continuous exhaustion of magnetite resources. The utilization of high-phosphorus iron ore becomes the focus. With calcium carbonate (CaCO3), calcium chloride (CaCl2), or calcium sulfate (CaSO4) as additive, the process of direct reduction and phosphorus removal of high-phosphorus iron ore (phosphorus mainly occurred in the form of Fe3PO7 and apatite) was studied by using the technique of direct reduction-grinding-magnetic separation. The mechanism of calcium compounds to reduce phosphorus was investigated from thermodynamics, iron metallization degree, mineral composition and microstructure. Results showed that Fe3PO7 was reduced to elemental phosphorus without calcium compounds. The iron-phosphorus alloy was generated by react of metallic iron and phosphorus, resulting in high phosphorus in reduced iron products. CaCO3 promoted the reduction of hematite and magnetite, and improved iron metallization degree, but inhibited the growth of metallic iron particles. CaCl2 strengthened the growth of iron particles. However, the recovery of iron was reduced due to the formation of volatile FeCl2. CaSO4 promoted the growth of iron particles, but the recovery of iron was drastically reduced due to the formation of non-magnetic FeS. CaCO3, CaCl2 or CaSO4 could react with Fe3PO7 to form calcium phosphate (Ca3(PO4)2). With the addition of CaCO3, Ca3(PO4)2 was closely combined with fine iron particles. It is difficult to separate iron and phosphorus by grinding and magnetic separation, resulting in the reduced iron product phosphorus content of 0.18％. In the presence of CaCl2 or CaSO4, the boundary between the generated Ca3(PO4)2 and the metallic iron particles was obvious. Phosphorus was removed by grinding and magnetic separation, and the phosphorus content in the reduced iron product was less than 0.10％.