Evolution of ferronickel particles during the reduction of low-grade saprolitic laterite nickel ore by coal in the temperature range of 900–1250℃with the addition of CaO–CaF2–H3BO3

The method of producing ferronickel at low temperature(1250–1400℃)has been applied since the 1950s at Nippon Yakin Kogyo,Oheyama Works,Japan.Limestone was used as an additive to adjust the slag composition for lowering the slag melting point.The ferronickel product was recovered by means of a magnetic separator from semi-molten slag and metal after water quenching.To increase the efficiency of magnetic separation,a large particle size of ferronickel is desired.Therefore,in this study,the influences of CaO,CaF₂,and H₃BO₃ additives on the evolution of ferronickel particle at≤1250℃were investigated.The experiments were conducted at 900–1250℃with the addition of CaO,CaF₂,and H₃BO₃.The reduction processes were carried out in a horizontal tube furnace for 2 h under argon atmosphere.At 1250℃,with the CaO addition of 10 wt%of the ore weight,ferronickel particles with size of 20μm were obtained.The ferronickel particle size increased to 165μm by adding 10 wt%CaO and 10 wt%CaF₂.The addition of boric acid further increased the ferronickel particle size to 376μm,as shown by the experiments with the addition of 10 wt%CaO,10 wt%CaF₂,and 10 wt%H₃BO₃.     

蛇纹石型红土矿常压酸浸实验研究

主要探讨了常压下盐酸对蛇纹石型红土镍矿进行浸出的工艺条件。考察了酸矿比、液固比、反应温度、反应时间等对蛇纹石型红土镍矿浸出的影响。通过实验得出最佳工艺条件:酸矿比为2.5∶1、液固比为5∶1、反应时间为0.5 h、反应温度为100℃。在此条件下镍、钴、铁浸出率分别为100%、100%和90%。     

红土镍矿焙烧过程中的矿相转变及其对气体还原的影响

研究了印度尼西亚红土镍矿焙烧过程中的矿相转变过程以及焙烧温度对混合气体 (V (CO) : V (O₂)=50 : 50)还原的影响. 采用差热/热重分析(differential scanning calorimeter/thermal gravimetric, DSC/TG)、比表面积分析法(Brunauer Emmett Teller, BET)、X射线衍射(X-ray diffraction, XRD)、扫描电镜(scanning electron microscope, SEM)等方法综合考察了各因素对红土镍矿焙烧过程及其对后续还原的影响. 结果表明: 在焙烧阶段, 红土镍矿中的针铁矿在 300°C 左右脱除结晶水形成赤铁矿, 600~700 °C时蛇纹石分解形成无定形态硅镁酸盐, 且当温度继续升高时无定形态硅镁酸盐会结晶形成橄榄石; 利用混合气体 (V (CO) : V (O2)=50 : 50)还原红土镍矿时, 随着焙烧温度的升高, 镍和铁的金属化率也逐渐升高, 经700°C焙烧后, 还原产物镍的金属化率最高可达86.81%, 但是当焙烧温度超过橄榄石结晶温度时则不利于红土镍矿的还原, 镍的金属化率降至66.73%.     

Two-stage reduction for the preparation of ferronickel alloy from nickel laterite ore with low Co and high MgO contents

The preparation of ferronickel alloy from the nickel laterite ore with low Co and high MgO contents was studied by using a pre-reduction-smelting method. The effects of reduction time, calcination temperature, quantity of reductant and calcium oxide (CaO), and pellet diameter on the reduction ratio of Fe and on the pellet strength were investigated. The results show that, for a roasting temperature >800℃, a roasting time >30 min, 1.5wt% added anthracite coal, 5wt% added CaO, and a pellet size of~10 mm, the reduction ratio of Fe exceeds 70% and the compressive strength of the pellets exceeds 10 kg per pellet. Reduction smelting experiments were performed by varying the smelting time, temperature, quantity of reductant and CaO, and reduction ratio of Fe in the pellets. Optimal conditions for the reduction smelting process are as follows:smelting time, 30-45 min; smelting temperature, 1550℃; quantity of reductant, 4wt%-5wt%; and quantity of CaO, 5wt%; leading to an Fe reduction ratio of 75% in the pellets. In addition, the mineral composition of the raw ore and that during the reduction process were investigated by process mineralogy.     

人工神经网络及其在岩土建模中的应用

探讨了应用人工神经网络技术模拟岩土本构特征的可行性,认为神经网络为岩土材料本构特性的研究提供了一种新方法,并结合重庆红粘土本构特性的社会网络模型,介绍了该方法的具体应用,计算结果与试验结果均说明了该方法的有效性。     

贵州岩溶地区红土的地球化学特征及其意义

选择贵州岩溶地区具有典型亚热带岩溶地貌和生态环境特征，发育完整的白云岩和灰岩红土剖面，依据１２个剖面７２件样品的常量和微量元素化学分析资料，研究了岩溶地区经土的地球化学特征，提出了碳酸盐岩红土成土地球化学的三个主要过程：富硅铝脱钙镁过程，富铁锰过程和富铝脱硅过程，在碳到盐红的形成和演化过程中，Ｃｕ，Ｐｂ，Ｚｎ，Ｎｉ，Ｃｏ，Ｃｒ，Ｒｂ，Ｆ，Ｃｌ和Ａｓ等微量元素也发生了明显的富集和分异。     

碳酸盐岩红土中氧化铁矿物的穆斯堡尔谱学研究

本文在高梯度磁选法分离红土中氧化铁矿物基础上，运用穆斯堡尔谱学方法对红土中氧化铁矿物进行了系统研究，并建立起红土中氧化铁矿物分析流程和研究方法体系。研究表明，红土中氧化铁矿物主要有针铁矿、赤铁矿和磁赤铁矿。氧化铁矿物沿红土剖面分布的规律性，记录了成土环境和古气候的周期性变化特征，具有重要的环境指示意义。     

洞庭盆地红土地层中网纹的成因探讨

在野外考察的基础上,运用化学全量分析、X射线衍射分析、红外光谱分析和扫描电镜微形貌分析等实验方法和手段,对洞庭盆地第四系红土地层中网纹的元素地球化学、矿物组合特征和微形貌特征进行了系统研究,对洞庭盆地红土地层中2种主要的网纹类型——蠕虫状网纹和根状网纹的成因进行了探讨。认为：土壤孔隙空间的形成和化学元素的迁移是网纹产生的2个必要条件。蠕虫状网纹孔隙空间的产生是由于地层静压力和地下水位季节性变化造成的,而根状网纹的孔隙空间则是植物根系腐烂分解后提供的。地下水和地表水强烈的淋溶作用使土壤中硅、铝、铁、锰等元素的迁移能力增强,土壤胶体粒子之间的化学反应,使得这些孔隙空间在后期逐渐被次生黏土矿物和石英所充填,最终,在洞庭盆地第四系红土地层中形成大量的蠕虫状和根状白色网纹。     

红土镍矿还原熔炼制备镍铁的试验研究

对低铁、高硅、高镁腐殖土型红土镍矿的脱水和碳还原过程进行DTA-TG分析,确定脱水和固体碳还原反应的温度区间。在煅烧-还原熔炼红土镍矿制备镍铁中,针对矿石自然渣型碱度低、黏度及密度大,不利于金属与渣分离及镍回收率提高等问题,采用控制CaO加入量的方法,调节CaO-FeO-MgO-SiO2系炉渣的黏度和密度;探讨还原剂焦粉及CaO用量、温度、时间对熔炼效果的影响。综合考虑镍铁品位和镍的回收率,确定最佳还原熔炼试验条件:焦粉、石灰与矿石质量比分别为9.0%和8.3%,温度为1 550℃,时间为40 min。在最佳试验条件下,产出的镍铁品位为22.0%,镍、钴回收率分别为92.5%和70.0%。     

水泥红土的力学性能试验研究

通过对不同水泥掺入比．不同龄期的水泥红土的无侧限抗压试验．分析了水泥红土的无侧限抗压强度和模量随水泥掺入比及龄期的变化规律；并对水泥红土会应力应变曲线的特性进行了总结．根据所得的结论对水泥红土的应用提出了一些建议．