国外某高磷鲕状赤铁矿直接还原——磁选降磷研究

Study on Phosphorus Removal of High——Phosphorus Oolitic Hematite Abroad by Direct Reduction and Magnetic Separation

以国外某高磷鲕状赤铁矿为研究对象进行脱磷研究,该高磷矿铁品位为55.81%,磷含量为0.72%,铁矿物主要为磁铁矿和赤铁矿,48.61%的磷存在于磷酸盐中,47.22%的磷分布于铁矿物中。研究了脱磷剂用量、秸秆炭用量、还原温度以及还原时间对粉末还原铁指标的影响。结果表明:无脱磷剂碳酸钙时,无法获得合格的指标;在碳酸钙用量为25%,秸秆炭用量为12.5%,还原温度1200℃,还原时间为75 min,还原产品两段磨矿两段磁选的条件下,可获得铁品位、铁回收率以及磷含量分别为94.27%、87.34%以及0.077%的粉末还原铁,该产品可作为电炉炼钢的优质原料。不加添加剂时,部分含磷矿物被还原成单质磷进入到金属铁中,故粉末还原铁磷含量较高,当碳酸钙用量为25%时,含磷矿物的还原受到抑制而保留在脉石相中,可实现降磷目的,而还原时间过长时,磷仍在脉石相中,铁颗粒将部分含磷矿物包裹,磨矿难以分离,导致磷含量升高。

A high-phosphorus oolitic hematite from abroad was used as a research object for dephosphorization.The iron grade and phosphorus content of the high-phosphorus oolitic hematite were 55.81%and 0.72%respectively.48.61%phosphorus was present in the phosphate and 47.22%is present in the iron minerals.The effects of dephosphorization agent dosage,straw carbon dosage,reduction temperature and reduction time on the indexes of powdery reduced iron were studied.The results showed that the qualified indexes could not be obtained without additives.In the case of calcium carbonate dosage of 25%,straw carbon dosage of 12.5%,reduction temperature of 1200℃,reduction time of 75 min,two sections of grinding and two sections of magnetic separation,iron grade,iron recovery and phosphorus content of 94.27%,87.34%and 0.077%powdery reduced iron can be obtained respectively,which can be used as high quality raw material for electric furnace steelmaking.When no additives were added,some phosphorus-containing minerals were reduced to elemental phosphorus and enter the metal iron.Therefore,the phosphorus content in powdery reduced iron is high.When the amount of calcium carbonate added was 25%,the reduction of the phosphorus-containing mineral was inhibited and remains in the gangue phase,which can achieve the purpose of phosphorus removal.When the reduction time was too long,the phosphorus was still in the gangue phases,and the iron particles would partially encapsulate the phosphorus-containing minerals,and the grinding was difficult to separate,resulting in an increase in phosphorus content.