Preparation of ferronickel from nickel laterite via coal-based reduction followed by magnetic separation

The sticking phenomenon between molten slag and refractory is one of the crucial problems when preparing ferronickel from laterite ore using rotary hearth fulnace or rotary kiln processes. This study aims to ameliorate sticking problems by using silicon dioxide （SiO2） to adjust the melting degree of file briquette during reduction roasting. Thermodynamic analysis indicates that the melting temperature of the slag gradually increases with an increase in the SiO2 proportion （SiO2/（SiO2 ＋ A1203 ＋ MgO） mass ratio）. Experimental validations also prove that the briquette retains its original shape when the SiO2 proportion is greater than 75wt%, and sticking problems axe avoided during reduction. A ferronickel product with 8.33wt% Ni and 84.71wt% Fe was prepared via reductive roasting at 1500~C for 90 min with a SiO2 proportion of 75wt% and a C/O molar ratio of 1.0 followed by dry magnetic separation; the corresponding recoveries of Ni and Fe reached 75.70% and 77.97%, respectively. The micro stxucture and phase txmlsformation of reduced briquette reveals that the aggregation and growth of ferroinckel particles were not significantly affected after adding SiO2 to the reduction process.

Thermal behaviors and growth of reduced ferronickel particles in carbon-laterite composites

The thermal behaviors of single laterite ore and graphite-laterite mixtures were investigated by thermogravimetry （TG）, derivative thermogravimetry （DTG）, and differential thermal analysis （DTA）. Four mass loss steps maximized at about 78, 272, 583, and 826℃ are observed for the laterite ore, representing the vaporization of free water, the dehydroxylation of goethite, the decomposition of serpentines, and the second dehydroxylation of serpentines, respectively. The reduction reactions of the graphite-laterite mixtures start at around 700℃ and can be divided into three major temperature regions. Coal-laterite composites with an addition of 10 wt.% CaO were roasted at 1100-1350℃ for 30 min, and the reduced samples were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The results indi- cate that the reduction reactions proceed more completely at higher temperatures. The growth of the reduced ferronickel particles is greatly influenced by the roasting temperature, Obvious growth of the reduced ferronickel particles appears with the formation of worm-like crystals for the sample reduced at 1250℃ and spheric particles are observed for the sample reduced at 1300℃. When the reduction temperature increases to 1350℃, the reduced ferronickel particles agglomerate to ferronickel granules of 3-8 mm in diameter. The main elements in the granules include iron, nickel, chromium, carbon, and sulfur, with the content of nickel and that of iron of 9.08 wt.% and 85.21 wt.%, respectively.

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–CaF_(2)–H_(3)BO_(3)

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,CaF_(2),and H_(3)BO_(3) additives on the evolution of ferronickel particle at≤1250℃were investigated.The experiments were conducted at 900–1250℃with the addition of CaO,CaF_(2),and H_(3)BO_(3).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%CaF_(2).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%CaF_(2),and 10 wt%H_(3)BO_(3).

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 degrees C, a roasting time > 30 min, 1.5wt% added anthracite coal, 5wt% added CaO, and a pellet size of similar to 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, 1550A degrees C; 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.

Petroleum coke as reductant in co-reduction of low-grade laterite ore and red mud to prepare ferronickel: Reductant and reduction effects

Petroleum coke is industrial solid wastes and its disposal and storage has been a great challenge to the environment. In this study, petroleum coke was utilized as a novel co-reduction reductant of low-grade laterite ore and red mud. A ferronickel product of 1.98wt% nickel and 87.98wt% iron was obtained with 20wt% petroleum coke, when the roasting temperature and time was 1250°C and 60 min, respectively. The corresponding recoveries of nickel and total iron were 99.54wt% and 95.59wt%, respectively. Scanning electron microscopy-energy dis- persive spectrometry (SEM-EDS) analysis showed metallic nickel and iron mainly existed in the form of ferronickel particles which distrib- uted uniformly at a size of approximately 30 μm with high purity. This study demonstrated that petroleum coke is a promising reductant in the co-reduction of laterite ore and red mud. Compared to other alternatives, petroleum coke is advantageous with reduced production cost and high applicability in anthracite-deficient areas.

Making Ferronickel from Laterite Nickel Ore by Coal-Based Self-Reduction and High Temperature Melting Process

Based on the process of coal-based self-reduction and melting separation at high temperature, it was investigated that the effect of process factors on the reduction of iron and nickel oxide, the metal yield and the nickel content in ferronickel about the laterite nickel ore, was from Philippines and contented low nickel, high iron and aluminum. The results showed that if the C/O mole ratio was not higher than 0.5 and the reduction temperature was kept as 1200°C and then increased up to 1500°C, the metal could not separate from molten slag for the A series of experiments, which were only added CaF2. However, when the C/O ratio was added up to 0.6 - 0.8, the metal could separate well from the slag, and the yields of Fe and Ni increased gradually. But the nickel content in the metal declined from 1.79% to 1.34%. When the C/O ratio increased to 1.2, and the temperature of melting products obtained at 1200°C and rose to 1550°C, the separation of metal from slag could not be realized in B group of tests, which were only added hydrated lime. However, when both of CaF2 and hydrated lime were added, the metal could separate from slag in C group. In order to increase the content of nickel in the metal, it is necessary to restrain the reduction of iron oxide. When the C/O mole ratio is 0.6, the nickel content of metal could be 1.79%, which was higher than the theoretical ratio 1.65% of Ni/(Ni + Fe) of the latcritic nickel ore, but the yield of nickle was only 71.3%.

Ferronickel Slag Performance from Reclamation Area in Pomalaa, Southeast Sulawesi, Indonesia

This study aimed to assess the differences of characteristics between the new ferronickel slag generated from the production of nickel and the slag which had been used as a material reclamation. The Toxicity Characteristic Leaching Procedure (TCLP) test was conducted on ferronickel slag to determine the concentration of heavy metals leaching. Then, the tests of X-Ray Diffraction (XRD), Scanning Electron Microscopic (SEM) and Energy-Dispersive X-Ray Spectroscopy (EDX) are also conducted on the ferronickel slag samples. The results of TCLP test show that the new ferronickel slag samples contain Fe (158, 6775 ppm), Cr (0.64465 ppm), and Pb (0.0219 ppm), and that the ferronickel slag has been used as a reclamation material containing Fe (3.94 ppm) and Cr (2.91 ppm). The result of EDX test shows that the slag sample from the reclamation area contains higher Ni concentration than the new slag sample. Slag that has been used for reclamation contains high SiO2 and Mg2(SiO6). The XRD analysis result shows that the highest elements in the slag are Si and Mg with 18.94% and 15.83% respectively. The dominant mineral in the slag is forsterite (Mg 1.784 FeSiO4 0216) by 41% and the rest is magnesium silicate (Mg2(SiO6)).

硅灰对高炉镍铁渣粉水泥土性能影响机制研究

高炉镍铁渣粉是一种前期火山灰活性较低的绿色可持续新型建筑材料。本文探讨了外掺硅灰对高炉镍铁渣粉水泥土无侧限抗压强度的影响规律,分析高炉镍铁渣粉和硅灰替代率对其无侧限抗压强度和破坏模式的影响。结合扫描电子显微镜(Scanning Electron Microscope, SEM)和X-射线衍射仪(X-ray Diffractometer, XRD)揭示硅灰对高炉镍铁渣粉水泥土性能影响机制。研究结果表明:在一定范围内,高炉镍铁渣粉水泥土的强度随硅灰掺量的增加而提升,归因于硅灰促进水泥水化反应以及硅灰发生二次火山灰反应生成C-S-H凝胶包裹土颗粒表面,未发生水化反应的颗粒减少,凝胶将土壤颗粒、高炉镍铁渣粉颗粒和小硅球等共同构建“网络状”空间骨架填充在大土壤颗粒之间,进一步提升了水泥土的密实性与强度,硅灰的最佳掺量为10%。硅灰掺量高会消耗大量Ca(OH)_(2),影响硅灰发生二次火山灰反应,特别是掺量增加至30%时,水泥土强度降低3.6%。

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.

Effect of basicity and Al2O3 on viscosity of ferronickel smelting slag

The effect of the Al2O3 content and basicity (the molar ratio of MgO to SiO2) on the viscosity of a SiO2-MgO-FeOAl2O3-CaO slag was studied to fully understand the smelting process of the ferronickel alloy. Experimental results show that the slag is a mixture of liquid and solid phases at the experimental temperature. The viscosity decreased as the basicity increased and increased as the Al2O3 content increased. To determine the effect of the Al2O3 content and basicity on the structure of the molten slag, Raman spectroscopy was performed on the slag sample, which was quenched from the high temperature with water. The Raman spectra showed that the fractions of the polymerization structural units decreased significantly as the basicity of the slag increased, resulting in a decrease in the apparent viscosity. However, Al2O3 acts as a network former in the slag system, thereby making the slag structure further polymerized and increasing the viscosity.

镍铁渣硫酸浸出渣制备硅酸盐水泥熟料工艺研究

以镍铁渣硫酸浸出渣为原料制备硅酸盐水泥熟料,研究不同石灰饱和系数和不同焙烧温度对硅酸盐水泥熟料物相结构与微观形貌的影响。通过测定熟料中f-CaO浓度来判断水泥熟料的易烧性,通过XRD、EDS、SEM分析熟料的物相结构、元素分布及微观形貌。结果表明,焙烧温度越高,f-CaO浓度越低,易烧性越好。当焙烧温度为1350℃时,硅酸盐水泥熟料焙烧后出现了粉化现象且未形成C_(3)S相;而当1400℃焙烧时,硅酸盐水泥熟料中出现了以C_(2)S和C_(3)S为主的晶相,未出现粉化现象;当焙烧温度达到1450℃时,水泥相晶粒组织发育比较充分。该熟料与石膏混合制成水泥,其水泥砂浆的水化产物经28 d养护后抗压和抗折强度分别为37.34和7.01 MPa。

海水侵蚀作用对水泥土抗拉强度劣化影响研究

【目的】探究海水侵蚀环境下水泥土所表现出的抗拉强度劣化特性。【方法】选用镍铁渣粉和矿渣作为复合外掺料,通过开展劈裂间接抗拉试验,研究不同镍铁渣粉掺量、不同养护环境(清水与海水)对水泥土的抗拉强度、表观侵蚀以及破坏性状的影响。【结果】清水环境和海水环境水泥土中掺入镍铁渣粉,可提升其抗拉强度,其抗拉强度随掺量增加先增大后减小,最优镍铁渣粉掺量为45%,且两种养护条件下均表现为脆性破坏。【结论】研究成果可为沿海地区软基处理工程提供技术参考。

RKOEF法制备高品级含镍母液研究

介绍了针对现有RKEF镍铁生产工艺存在的问题提出一种称为RKOEF工艺的革新方案,即“红土镍矿内配碳压块自还原–选择性氧化–矿热炉熔分”新工艺。针对这一新工艺,在实验室条件下研究了腐泥土型红土镍矿自还原反应规律,以及自还原产物选择性氧化的反应机制,试样熔分后的实际效果。研究结果表明:(1)温度对自还原速率和最终还原率影响很大,C/O比1.2的试样在1200~1250℃自还原25~30 min,氧化镍和氧化铁都能得到比较充分的还原;(2)内配煤压块在1200℃自还原25 min后直接升温至1600℃熔分,镍和铁的综合收得率随自还原压块内配碳比增加而增加,相应地镍铁合金中金属镍含量随内配碳比增加而下降。缺碳配煤(C/O≤1)方案可以提高镍铁合金中金属镍的含量,但牺牲其综合收得率;(3)温度显著影响CO_(2)对自还原产物中金属铁的选择性氧化,与未经选择性氧化的工艺相比,红土镍矿自还原–选择性氧化–高温熔分工艺制备的镍铁合金的镍含量可从8%~10%提高到34%~37%,金属镍综合收得率大于95%。

海水侵蚀下复掺矿粉和镍铁渣粉的水泥土力学性能分析

【目的】研究地基处理采用的水泥土在海水侵蚀环境影响下的力学性能,为沿海地区地基处理工程提供技术支持。【方法】将复合镍铁渣粉以等质量替代的方式掺入到水泥土中,通过无侧限抗压强度试验,进行抗侵蚀系数分析。【结果】海洋环境对水泥土的强度具有劣化作用,而掺入复合镍铁渣粉能提升水泥土的强度性能,缓解海洋环境对其强度的劣化作用。【结论】复合镍铁渣粉能起到微集料效应、形貌效应和活性效应,提升水泥土的密实程度,对水泥土的性能产生有利影响。

镍铁在不同含镍品种冶炼中的应用

本文介绍了生产不同含镍品种时,使用含镍生铁替代金属镍的生产工艺、冶炼成本等情况。采用镍铁在不同品种生产中的应用,证明镍铁可以替代金属镍应用到不同含镍品种冶炼上,并且能够在保证质量的前提下,有效地降低冶炼成本。

镍铁冶炼厂电能质量监测及改进实践

本文描述了镍铁冶炼厂因电能质量低导致设备故障频发,监测工厂电能质量对运行设备的影响,并对造成电能质量下降的因素进行了探讨,最后提出改善冶炼厂电能质量的方案,实施效果良好。

Fe-(NiSe_(2)/Ni_(3)Se_(4))@NFF电极的制备及其电解水性能研究

利用亚硒酸钠在溶剂热条件下直接对镍铁合金泡沫(NFF)进行硒化,后热处理成功制备了具有纳米结构的Fe-(NiSe_(2)/Ni_(3)Se_(4))@NFF材料。没有外加金属源,将NFF作为唯一金属来源,成功制备了铁掺杂镍硒化物自支撑电极。该材料在碱性介质中对析氢和析氧均表现出优异的催化性能。若将该材料同时作为阴极和阳极驱动全解水时,仅需1.55 V的槽电势就可以到达10 mA/cm^(2)的电流密度。该合成方法简单、操作易行、环保节能,旨在创造一种有较强本征活性和耐久性的全解水催化剂。

镍铁渣水泥与粉煤灰水泥的力学性能对比试验

通过对69组镍铁渣掺合料水泥与粉煤灰掺合料水泥进行配合比对比试验,研究镍铁渣掺量、镍铁渣与硅灰不同比例对复合水泥胶砂抗压强度、抗折强度的影响;同时,以相同掺量粉煤灰掺合料进行对比试验。试验结果表明:镍铁渣具有与粉煤灰类似的火山灰活性,可作为胶凝材料代替部分水泥使用;在总掺量不超过30%的情况下,无论是单掺镍铁渣或粉煤灰,还是复掺镍铁渣&硅灰,或复掺粉煤灰&硅灰,二者配置的水泥胶砂抗压强度与抗折强度性能相当。随着镍铁渣掺量的增加,复合镍铁渣水泥胶砂抗压强度与抗折强度均逐渐降低;无论是单掺镍铁渣,还是复掺镍铁渣、硅灰水泥中镍铁渣与硅灰总掺量均不宜超过30%,镍铁渣与硅灰比例分别为2∶1、1∶1、1∶2时,3种比例下的强度关系满足2∶1>1∶1>1∶2。

红土镍矿还原焙烧-磁选制取镍铁合金原料的新工艺

采用钠盐添加剂强化红土镍矿的还原焙烧-磁选,确定了添加剂存在下适宜的焙烧和磁选技术参数,开发出红土镍矿还原焙烧-磁选制取镍铁合金原料的新工艺。结果表明:钠盐添加剂具有显著降低焙烧温度、大幅提高产品镍、铁品位和回收率的作用;对一种含镍1.58%、铁22.06%的红土镍矿配加添加剂后,在还原温度1 100℃、还原时间60 min、磁场强度0.1 T的条件下,磁性产品的镍、铁品位可分别从无添加剂时的2.0%、57.2%提高到7.5%、80.5%,镍、铁回收率也相应从19.1%、33.6%增加到82.7%、62.8%。XRD结果表明:红土镍矿在无添加剂作用下经还原焙烧-磁选所得的磁性产物中仍有部分镁橄榄石及顽火辉石存在;而有添加剂存在时,还原生成的镍铁合金通过磁选可与非磁性脉石成分得到更为有效的分离,产品可作为不锈钢的生产原料。

红土镍矿资源现状及加工工艺综述

综合论述了世界红土镍矿的资源概况和利用现状,分析了我国对镍的需求情况,对红土镍矿的处理方法和目前有前景的加工工艺进行了较为详细的阐述和分析。