Effective beneficiation of low content nickel ferrous laterite using fluxing agent through Na2SO4 selective reduction

To address the issue of high energy employment and un-green processing in limonitic laterites extraction, selective reduction using Na₂SO₄ additive with the introduction of different fluxes including quicklime, dolomite, and limestone followed by magnetic separation was studied. The objective of the research was to find out the influence of fluxes in optimizing ferronickel product of reduction. The reduction process was carried out at 1400 °C for 6 hours and the obtained product was characterized by scanning electron microscopy (SEM), emission dispersive x-ray (EDX), and x-ray diffraction (XRD) to image the morphology, determine the composition, and examine the mineralogical structure. Result showed that the employment of fluxes exhibited positive effect in improving the product. The highest nickel grade was 21.68 % using limestone flux, while the most promising recovery was 93.73 % utilizing dolomite flux. Meanwhile, mineralogical assessment also proved that the ascending of nickel content is due to the formation of troilite (FeS) as the result of synergy between Na₂SO₄ additives and carbonate minerals from fluxes. This result exhibits a notable performance of fluxes for improving the product of selective reduction.     

海洋环境下复合镍铁渣粉水泥土的强度劣化研究

采用实验室模拟的方法,研究海洋环境对掺复合镍铁渣粉水泥土强度的影响。本文将镍铁渣粉和矿粉混合后,作为掺和料掺入到水泥土中。通过海洋环境侵蚀分析、无侧限抗压强度试验、SEM和EDS试验分析,研究了海洋环境对复合镍铁渣粉水泥土的表观特征、强度性能及微观形貌的影响。试验结果表明：海洋环境对水泥土的表观结构具有侵蚀作用,同时对其强度也具有劣化作用,而且随着侵蚀时间的增加海洋环境对其侵蚀劣化作用越来越强;水泥土中掺入的复合镍铁渣粉能发挥出微集料效应和活性效应,因而具有良好的耐久性。复合镍铁渣粉不仅能提升水泥土的强度,同时能降低海洋环境对其表观结构的侵蚀,缓解海洋环境对其强度的劣化作用。     

海水环境下镍铁渣粉水泥土的抗渗性能

为研究镍铁渣粉对水泥土渗透性能的影响,采用加压型渗透装置对镍铁渣粉水泥土在清水环境和海水环境下进行渗透试验,并用压汞试验和扫描电镜-能谱分析试验对镍铁渣粉水泥土进行微观分析.结果表明：清水环境和海水环境下镍铁渣粉的掺入均能提升水泥土的抗渗性能,而海水环境下尤为明显;镍铁渣粉掺量超过20%后,镍铁渣粉掺量增加对水泥土抗渗性能的影响逐渐变小;镍铁渣粉能发挥微集料效应和活性效应,减小水泥土的最可几孔径和总孔隙率,增强其抗海水侵蚀性能;镍铁渣粉能使水泥土的微细观结构更加致密,同时能促进水泥土生成具有低钙硅比的水化产物,增强其抗渗性能.     

Desulphurization of Hot Metal and Ferronickel With Calcium Aluminate Fluxes

Traditionally, fluxes containing calcium fluoride and other additives are used for the treatment of hot metal and molten steel. Recently, magnesium powder or lime-Mg mixture is used more popularly in hot metal desulphurization. However, the use of calcium fluoride has been restricted due to environmental concerns, and the supply of magnesium is uncertain for the countries, which are short of magnesium resource. For those reasons, calcium aluminate fluxes are a possible alternative to replace slags containing calcium fluoride or magnesium. Calcium aluminate fluxes can be produced from three different raw materials: (1) high-quality bauxite, (2) residuals from aluminum dross treatment processes and (3) waste products from alumina production. Due to the limited amount and high cost associated with high-quality bauxite, the other two sources are preferred based on both economic and environmental considerations. The objective of this paper is to examine the use of waste slags and by-products from the aluminum industry as potential refining fluxes for the steel industry so that waste disposal from the aluminum industry can be reduced with economical and environmental benefits for both industrial sectors.     

镍铁渣混凝土的力学性能、干缩行为及其与浆体孔结构的关系

制备了不同掺量的镍铁渣混凝土,对其抗压强度、劈裂抗拉强度、弹性模量和干燥收缩进行了测试,并使用压汞法对同配比净浆的孔结构进行了表征。结果表明,镍铁渣混凝土的抗压强度随镍铁渣掺量的提高出现先提高后下降的现象,这与孔结构变化有显著关系。当镍铁渣掺量在20%以上时,混凝土早期强度增长较为缓慢,经90 d龄期养护后基本可以弥补早期形成的强度差。镍铁渣的掺入降低了混凝土的劈裂抗拉强度,但混凝土的弹性模量提高。蒸汽养护可以一定程度激发镍铁渣的活性,但并不能弥补其取代水泥造成的强度损失。20%掺量以内的镍铁渣混凝土具有比纯水泥混凝土较小的干燥收缩,这与镍铁渣掺入后混凝土孔隙率降低、弹性模量提高等相关。     

硫酸法常压浸出镍铁渣中镁的正交试验及动力学分析

镍铁渣产量大,富含Mg元素,具有较高的回收价值。基于镍铁渣成分及矿相结构等特性,采用常压硫酸浸出法,研究镍铁渣中Mg的浸出反应规律和影响因素。结果表明,在液固比20∶1、浸出温度180℃、浸出时间120min、硫酸质量分数80%的条件下,镁浸出率达到83.73%。该浸出受界面化学反应控制,表观活化能12.72kJ/mol。     

72000kVA矿热电炉冶炼镍铁生产工艺

详细介绍了大型72 000 kVA矿热电炉冶炼镍铁的生产工艺——回转窑-电炉熔炼(RKEF)工艺。该工艺是处理红土镍矿生产镍铁的主流工艺,可有选择地进行脱硫、脱硅、脱碳和脱磷,采用镍铁精炼新工艺对粗镍铁金属液进行喷吹和升温,得到满足不锈钢生产所需的合格镍铁原料,具有一定的推广应用前景。     

红土镍矿钠盐还原焙烧-磁选的机理

配加钠盐焙烧可改善红土镍矿的还原-磁选效果,显著提高磁性产品的镍、铁品位及回收率。通过热力学计算,并结合X射线衍射、光学显微镜以及环境扫描电镜分析,对硫酸钠和碳酸钠作用下红土镍矿的还原行为进行研究。结果表明:钠盐在红土镍矿还原焙烧过程中,可以破坏硅酸盐矿物的结构,有利于镍的还原富集。碳酸钠强化镍还原的能力强于硫酸钠的,硫酸钠则因还原过程中形成的硫具有降低镍铁金属颗粒表面张力的作用,因而其促进镍铁颗粒聚集长大的能力明显高于碳酸钠的,且硫酸钠作用下FeS的形成也有利于提高镍的品位。所以,硫酸钠和碳酸钠的共同作用下可获得高镍品位的磁性产品及较高的镍回收率。     

RKEF工艺处理缅甸镍红土矿

介绍了采用回转窑—电炉法(RKEF)处理缅甸达贡山镍红土矿生产镍铁的中试试验过程,得到了下述最佳工艺参数:干燥后原矿含水20%～22%、回转窑预还原温度900℃、还原剂煤的配入量7%、镍品位19%,烟尘制粒时湿矿配入量为烟尘的25%、尘球含水30%,电炉熔炼时放渣温度1 550～1 600℃、镍铁合金放出温度1 450～1 500℃。     

红土镍矿还原熔炼镍铁的试验研究

为提高金属回收率和镍的品位,通过对两种红土镍矿进行化学成分的测定和X射线衍射分析确定了镍矿的化学成分和矿物组成,使用两种红土镍矿按照1∶1的比例进行混合,在实验室条件下进行单因素试验,考察熔炼温度、煤粉配比和渣型对红土镍矿还原熔炼的影响.综合考虑金属回收率和镍品位,确定最佳还原熔炼条件：配加5％煤粉和10％石灰石,在1 550℃下熔炼50 min,在最优试验条件下,镍、铁的回收率分别为96.95％和85.15％,镍的品位达到21.89％,所得镍铁合金质量可以满足生产要求.