红土镍矿冶金技术研究进展

如今世界经济迅猛发展,金属镍的需求量也在加速增长。人们主要从硫化镍矿和红土镍矿中提炼金属镍。然而硫化镍矿资源因大规模开发而不断减少,红土镍矿未来将成为镍的主要来源。因此研究红土镍矿的高效开发利用,是当今围绕镍资源研究的热点,对实际生产具有重要的现实意义。本文简要介绍了镍的应用、开发红土镍矿的意义、红土镍矿的矿物学特性、红土镍矿世界范围内的储量和分布,并且列举并分析了红土镍矿的各种冶炼工艺及其优点与不足,同时综述了有关红土镍矿研究的新方法,为红土镍矿高附加值综合利用研究提出思路。     

Use of oxidation roasting to control NiO reduction in Ni-bearing limonitic laterite

Use of limonitic laterite as an iron source in conventional ironmaking is restricted due to its gangue composition and small particle size. Even direct reduction cannot effectively produce direct reduced iron (DRI) because NiO would be reduced together with iron oxide to form Fe–Ni. A small amount of Ni (about 2 wt.%) in DRI degrades the physical properties of final steel products. The current study investigated how oxidation roasting of limonitic laterite ores affected NiO reduction, with the goal of producing Ni-free DRI and Ni-bearing slag. Ni-bearing slag can be a good secondary Ni resource. Oxidation roasting made NiO inert under H₂ reduction at 900 °C by forming Ni-olivine. Optimum roasting temperature was proposed by examining phase transformation of limonitic laterite ores during heating and by FactSage calculation of the equilibrium Ni fraction in Ni-bearing phases. Furthermore, the effect of Mg–silicate forming additives on the control of NiO reducibility was clarified to maximize the suppression of NiO reduction. Among various additives such as MgSiO₃, Mg₂SiO₄ and Fe–Ni smelting slag, Ni-free olivine-typed flux was found to be the most effective form of Ni-olivine because Ni–Mg ion exchange between Ni-bearing phase and Ni-free olivine occurs more readily than other Ni-olivine formation schemes. Finally, the mechanism of Ni-olivine formation during roasting was studied using a diffusion couple test. Calculated diffusivity values of Ni in Mg₂SiO₄ indicated that the two major routes of Ni-olivine formation while roasting limonitic laterite ore are (1) Ni partitioning within Mg–Ni silicate before crystallization and (2) Ni diffusion from spinel to Ni free olivine after crystallization.     

红土镍矿分解实验研究

提出了酸碱交替分解、互为活化的工艺思路,通过实验确定了优化工艺条件和工艺流程。在优化工艺条件下,红土镍矿中Fe2O3、NiO、MgO、Co、SiO2分解率分别达到96.78%、99.62%、94.39%、100%和98.60%,从而为实现对红土镍矿的全元素综合利用奠定了基础。     

重庆红粘土本构模型验证

以重庆红粘土为研究对象，通过对重庆红粘土在不同应力路径加荷条件下的应力－应变关系的分析研究，运用“土的本构关系图象程序”对重庆红粘土本构关系，进行了四种本要模型验证，认为非线性弹性成都科技大学Ｋ－Ｇ模型和殷宗泽双曲服面弹塑性模型能反映重庆红粘土应力－应变关系的本构模型，提出了相应的模型参数。     

Acid leaching and rheological behaviour of a siliceous goethitic nickel laterite ore: Influence of particle size and temperature

This study investigates the isothermal, batch, H₂SO₄ acid leaching behaviour of siliceous goethitic (SG) nickel (Ni) laterite ore and its links to pulp rheology. Specifically, the effect of feed ore particle size (−0.2 vs −2.0 mm), leaching temperature (70 vs 95 °C) and pulp rheology on Ni and pay metal, cobalt (Co) extraction kinetics and yield was studied for 4 h on 40 wt.% solid dispersions at pH 1. The leaching behaviour was distinctly incongruent, reflecting the disproportionate proliferation of major gangue mineral’s constituent elements (e.g., Fe, Al, Mg, Na, Si) alongside Ni and Co in the pregnant leach solution. At 70 °C, Ni/Co extraction rates were notably lower (<20%) in contrast with 95 °C where a significant increase in Ni/Co extraction to 78/77% and 74/77%, respectively, for the −0.2 and −2.0 mm feeds occurred. The slurries displayed a non-Newtonian, shear thinning Bingham plastic rheological behaviour of which the viscosity and shear yield stress increased markedly in the course of 4 h leaching. The pulp viscosity and shear yield stress were greater at lower temperature than at higher temperature and they were also greater in slurries with finer than coarser feed particles. The dynamic pulp rheology, however, had no marked effect on the overall Ni/Co extraction rates. Whilst the feed ore particle size had no remarkable impact on overall Ni/Co extraction, it led to noticeably higher acid consumption and enhanced slurry rheology in the finer sized ore. The mechanism of leaching the SG ore followed a two-stage, first order chemical reaction-controlled shrinking core model, the kinetics of which gave higher rate constants and lower activation energies for the release of Ni, Co, Fe and Mg in the first stage. A faster leaching process involving more reactive minerals during the first 30 min is envisaged to be followed by leaching of the more refractory minerals.     

Key factors affecting nickel recovery during the segregation of laterite ores

The segregation process as applied to nickel laterite ores involves the formation of gaseous nickel and iron chlorides which are subsequently reduced to form ferronickel on the surface of a solid carbon reductant. A fundamental study of the process has been carried out using limonite, nontronite and garnierite ores. The study highlighted the significant impacts that ore mineralogy and carbon addition have on the amount of nickel which is segregated rather than retained within the ore due to in situ reduction. These important aspects affecting nickel recovery and the success of the process are discussed in this paper.     

压实红黏土的湿化变形试验研究

为模拟路基土体在湿化与交通荷载耦合作用下的变形规律,对传统湿化变形试验方法进行了改进,并研制出一套改进后的湿化变形试验装置。认为湿化变形是由基质吸力丧失而产生,由此推导出丧失基质吸力与湿化变形的定量关系。利用改进的装置研究了红黏土的湿化变形规律及其湿化变形模量。结果表明,红黏土的初始压实状态对其变形影响显著,变形过程可以分为启动、加速和稳定三个阶段。未湿化试样的变形主要发生在启动阶段,而湿化试样的变形则主要发生在加速阶段。     

红土矿微波处理后冶炼镍铁试验研究

以微波处理后的红土矿为原料,分别进行了熔炼温度、熔炼时间及炉渣碱度3个单因素的试验研究.实验结果表明:提高熔炼温度对熔炼效果有积极的影响,当温度超过1530℃后,继续升高熔炼温度,熔炼效果没有明显的变化.增加熔炼时间能使反应充分进行,当熔炼时间超过50 min后,继续增加熔炼时间,熔炼效果没有明显的变化.提高炉渣碱度对熔炼效果有积极的影响,当炉渣碱度超过1.1后,继续增大炉渣碱度,熔炼效果反而变差.确定冶炼镍铁的工艺条件为:熔炼温度为1 515～1 530℃,熔炼时间为50～60 min,炉渣碱度为1.1左右.     

红土镍矿处理工艺的现状及发展方向

介绍了电炉法、鼓风炉法、烧结-高炉还原等火法和氨浸、加压酸浸、常压酸浸等湿法处理红土镍矿的主要工艺特点及其现状,结合红土镍矿的性质及其分布特点分析了几种常用处理方法的优势与不足,探讨了未来处理红土镍矿的工艺发展方向.