【作者】 刘志国；

【导师】 孙体昌；

【作者基本信息】 北京科技大学 ， 矿物加工工程， 2016， 博士

【摘要】 近年来采用直接还原-磁选工艺处理红土镍矿得到较多的关注并取得较大的研究进展,为镍资源的开发利用提供了一个新的途径。但是红土镍矿成矿规律比较复杂,不同类型的红土镍矿可能需要完全不同的工艺条件。因此,系统的研究矿石类型对红土镍矿直接还原-磁选工艺的影响及机理具有重要意义。选取铁质、铁镁质和镁质矿三种工业类型的红土镍矿为试样,系统研究了矿石类型对红土镍矿直接还原工艺的影响规律及机理。结果表明,无添加剂时铁质红土镍矿中的镍较易回收,但难以获得高镍品位的镍铁产品,铁镁质红土镍矿的镍较难回收,镁质红土镍矿的镍最难回收,而且这两种矿石所得镍铁产品的镍品位和回收率都不理想。不同类型的红土镍矿需使用不同的添加剂来解决上述问题。铁质红土镍矿添加硫酸钠效果较好,铁镁质和镁质红土镍矿添加氟化钙效果较好。在焙烧温度1200℃、焙烧时间50min、煤用量6%的焙烧条件下,铁质试样添加9%的硫酸钠可以获得镍品位为10.53%镍回收率为86.17%的镍铁产品；铁镁质和镁质试样添加9%的氟化钙可以分别获得镍品位为9.66%、8.67%镍回收率为84.82%、81.14%的镍铁产品。采用X射线粉晶衍射、扫描电镜和能谱分析等方法进行机理研究。发现矿石类型对红土镍矿焙烧产物中镍铁颗粒的大小有很大影响,对镍和铁的还原影响较小。无添加剂时,由铁质红土镍矿到镁质红土镍矿,焙烧产物中的镍铁颗粒逐渐变小,磁选回收镍的难度增大；红土镍矿中的铁含量是影响硫酸钠和氟化钙作用效果的重要因素。硫酸钠能够明显抑制铁矿物的还原,对铁质红土镍矿作用效果较好,而铁含量低的红土镍矿添加硫酸钠后会形成Fe-Ni-S对镍的回收造成不利影响。氟化钙能够明显促进镍铁颗粒的聚集长大,对铁镁质和镁质红土镍矿作用效果较好。但氟化钙不能有效抑制铁矿物的还原,对铁质红土镍矿作用效果不大。更多还原

【Abstract】 Extracting nickel from laterite nickel ore by direct reduction-magnetic separation process has gotten more attention and achieved greater progress in recent years, providing a new way for the utilization of nickel resources. However, the metallogenic regularity of laterite nickel ore is so complex that different laterite nickel ores may need completely different process conditions. Therefore, systematic studies on the influence and mechanism of ore types on its direct reduction-magnetic separation process are of great significance.Ferruginous, femic and magnesian laterite nickel ore of three industrial types were selected as the research object in this paper. The differences of direct reduction-magnetic separation process between the three samples were compared, and the effect of the ore types on direct reduction process was studied. It was found that nickel in ferruginous laterite ore is easy to recover without additives, but it is difficult to obtain nickalloy with high nickel grade. Compared with ferruginous laterite ore, nickel in femic laterite nickel ore is difficult to recover and nickel in magnesian laterite ore is more difficult to recover. The nickel recovery and grade of these two samples are unsatisfactory.To solve the above problems, different samples need different additives. Sodium sulfate is applicable to ferruginous laterite ore but not suitable for magnesia and femic laterite ore. On the contrary, calcium fluoride is applicable to magnesia and femic laterite ore but not suitable for ferruginous laterite ore. Under conditions of roasting temperature at 1200℃, roasting time for 50 min, coal dosage of 6%, ferruginous sample can obtain nickalloy containing 10.53% nickel with the nickel recovery of 86.17% when 9% sodium sulfate was added. Femic and magnesia sample sample can respectively obtain nickalloy containing 9.66%, 8.67% nickel with the nickel recovery of 84.82%,81.14% when 9% calcium fluoride was added.X-ray diffraction (XRD) and electron scanning electron microscopy and energy spectrum analysis (SEM-EDS) were used to analyse the mechanism of the difference between three samples’direct reduction process. It was found that the laterite nickel ore types have great influence on metal particles size in the roasted ore, but little influence on the nickel reduction. From ferruginous laterite nickel ore to magnesian laterite nickel ore, the metal particles size become smaller making them difficult to rocover in magnetic separation; The iron content in laterite nickel ore is the important factor affecting the effects of sodium sulfate and calcium fluoride. Sodium sulfate can obviously inhibit the reduction of iron ore, and has a good effect on ferruginous laterite nickel ore. But, when sodium sulfate is added into the laterite nickel ore with lower iron content, Fe-Ni-S will be generated and makes the nickel recovery rate lower. Calcium fluoride can obviously promote the nickel iron particles to grow up, so it has a good effect on femic and magnesian laterite nickel ore. But, calcium fluoride cannot be used on ferruginous laterite nickel ore because of the lack of capabilities to inhibit the reduction of iron minerals.更多还原