铁矿尾矿的活化及蒸养砖的制备

采用煅烧、磁选工艺对铁矿尾矿的惰性进行改性. 以改性后的铁矿尾矿为原料制备了蒸养砖，实现了对铁矿尾矿的废物利用. 将选矿尾矿与一定量煤粉混合煅烧，使其具有火山灰活性并使尾矿中的矿石矿物转变成磁铁矿. 对煅烧尾矿进行磁选，并检测三氧化二铝和二氧化硅的总溶出率. 以活化磁选后的铁矿尾矿为主要原料，采取干压成型制备了蒸养砖. 结果表明，煅烧后磁选能够将重选尾矿、浮选尾矿中的铁含量分别降低39.41 %和45.10 %，分选出来的铁精矿的品位均在57 %以上. 同时，重选尾矿的火山灰活性提高了近3倍，磁选尾矿的火山灰活性提高近2倍. 制备蒸养砖的最佳配合比为:水泥、建筑砂与尾矿的质量比为1∶1∶8，水料比0.15，石膏掺量为总干物料的2%. 所制得蒸养砖的抗折强度、抗压强度、吸水率、软化系数、干质量损失、干燥收缩率等性能指标都达到了非烧结砖的国标要求.

Activation of Iron Ore Tailings and Preparation of Steam-Cured Bricks

?The iron ore tailings were used as the raw materials to prepare steam-cured bricks for better use of the waste materials， and the calcination and magnetic separation technology was employed to modify the reactivity of the starting iron ore tailings. The mixtures of the tailings and a certain amount of coal powder were calcined, so that they gained the pozzolanicity activities, the ore minerals in the tailings were transformed to magnetite iron minerals. After magnetic separation， the total dissolution rate of alumina and silicon dioxide was determined. Finally， by using the activated and magnetic separated iron ore tailings as the major raw materials， the steamed curing bricks were obtained by the dry pressing method. The results show that the iron content in reelected tailings and flotation tailings in the magnetic separation after calcining reduces by 39.41% and 45.10 %， respectively， and the iron ore concentration is higher than 57% in the sorting out. Meanwhile， the pozzolanic activities of the tailings achieves 3 fold increase by the gravitational separation and 2 fold increas by the magnetic separation. The optimum compounding ratios for preparing steam-cured bricks are obtained at the mass ratio of cement and building sand and tail ore of 1∶1∶8 ， the ratio of water and dry powders of 0.15， and 2% for the dosage of the gypsum in the total dry powders. All the physical parameters， including flexural strength， compressive strength， water absorption， softening coefficient， dry mass loss and drying shrinkage performance indicators of the prepared steam-cured bricks have reached the national standard of baked brick.