煤种类及添加剂对红土镍矿选择性直接还原的影响规律

以含Ni 1.49%, Fe 34.69%的红土镍矿为研究对象, 采用煤基直接还原法选择性还原镍铁矿物, 研究并分析了焙烧过程中还原剂和添加剂种类及用量、焙烧温度以及焙烧时间对镍铁选择性还原的影响规律。结果表明: 以宁夏烟煤为还原剂, NCS为添加剂, 1 200 ℃焙烧50 min, 磁选得到镍铁产品中含镍9.51%, 镍的回收率为84.04%, 镍铁回收率差为54.49%。通过X射线衍射(XRD)、扫描电镜(SEM)及X射线能谱分析(EDS)等测试手段分析了磁选镍铁产品中镍铁的存在形式, 结果表明: 红土镍矿直接还原过程中铁矿物大部分被还原成浮士体, 仅有少部分铁矿物被还原成金属铁, 并与镍矿物还原金属镍形成铁纹石和镍纹石, 实现了红土镍矿中镍铁的选择性还原。

Effects of Coal Types and Additives on Selective Direct Reduction of Nickel Laterite

An experimental study was conducted on nickel laterite samples graded 1.49% Ni, 34.69% Fe by coal-based direct reduction, with Ni-Fe mineral selectively reduced. The effects of reductant, additives, roasting temperature, as well as roasting time on selective reduction of Ni-Fe during roasting process were all investigated. Results showed, with Ningxia bituminite as reductant and NCS as additive, being roasted for 50 min at 1 200 ℃, Ni-Fe concentrate approaching 9.51% Ni grade at 54.49% recovery was obtained by magnetic separation, with 54.49% difference between the recovery of Ni and Fe. The existence of Ni and Fe in the Ni-Fe products from magnetic separation was analyzed with X-ray diffraction(XRD), scanning electron microscopy(SEM) and EDS. Results showed that the majority of iron mineral was reduced to wuite during direct reduction of nickel laterite, only a minority was reduced to metallic iron, together with some reduced metallic Ni to form kamacite and taenite. Thus the selective reduction of Ni and Fe in nickel laterite can be realized.