碳酸盐岩上覆红土的成因研究

 碳酸盐岩上覆红土的成因一直悬而未决,致使它成了制约我国红土、岩溶等学科领域进行系统深入研究的关键问题,越来越多欠客观科学的红土、岩溶研究结果又使它成为亟待解决的重要问题。通过对我国学术界在碳酸盐岩上覆红土成因认识、研究过程中出现的主要问题进行评述,在此基础上提出一种全新的研究思路,由此建立的碳酸盐岩上覆红土的形成模式既能系统科学地解释长期以来没有解决的诸多红黏土与碳酸盐岩之间的复杂关系,又能客观合理地解释自然界碳酸盐岩上覆红土形成的真实原因,该研究成果对红土、岩溶研究具有重要的指导意义。     

Application of response surface methodology in optimizaing the sulfation-roasting-leaching process of nickel laterite

Nickel was recovered from nickel laterite using a sulfation-roasting-leaching process and the effects of operation parameters in-cluding acid addition,roasting temperature,and roasting time on nickel extraction and iron dissolution were investigated using response surface methodology(RSM).Two second-order polynomial models of high significance were presented to show the relationship between the responses and the variables.The analysis of variance(ANOVA) showed high coefficients of determination(R2) of 0.894 and 0.980 for the two models,respectively.Optimum areas of ≥80% Ni extraction and ≥5% Fe dissolution were obtained by the overlaid contours.Verification experiments in the optimum areas were conducted and the results indicate a close agreement with the predicted values obtained from the models.     

Hybrid sorbent-ultrafiltration systems for fluoride removal from water

Fluoride contaminated water sources are found in many parts of the world and the consumption of such water is causing dental and skeletal fluorosis in humans, especially in developing countries. Hybrid sorbent-ultrafiltration (UF) systems are proposed for the removal of fluoride from water for the first time in this study. Laterite and bone char were selected as they are low cost, accessible sorbents in developing countries. The performances of the laterite-UF and bone char-UF systems were compared in terms of fluoride removal and membrane permeability under varying fluoride concentration, solution pH, and sorbent load. For equilibrium fluoride concentration of 1.5 mg/L, the World Health Organization guideline for safe drinking water, the sorption capacity of bone char (1.1 mg/g) was larger than that of laterite (0.40 mg/g) and this was attributed to the larger surface area of bone char. For the laterite-UF system, increase in fluoride concentration resulted in a decline in UF permeability whereas for the bone char-UF system there was no influence of fluoride concentration on membrane permeability. The optimal solution pH at which the systems are operated at maximum sorption capacity while avoiding membrane fouling was determined as pH 5-6 for the laterite-UF and pH 7 for the bone char-UF system. For both systems, the permeability declined in a similar manner as the sorbent load increased. Although both systems require further optimization, they showed to be viable defluoridation technologies.     

Reductive roasting of nickel laterite ore with sodium sulfate for Fe-Ni production. Part I: Reduction/sulfidation characteristics

The selective reduction of nickel and adequate growth of ferronickel grains are imperative for efficient preparation of ferronickel from nickeliferous laterite ore via the process of direct reduction followed by magnetic separation. In Part I, reduction/sulfidation behaviors of a saprolitic laterite ore in the presence of sodium sulfate were investigated, with an emphasis on thermodynamic analysis, selective reduction/sulfidation ratios and kinetics. To separate the interactions between Ni and Fe, chemical titration analysis was adopted to determine the contents of various Ni and Fe species in the roasted pellets, and a modified equation to assay metallic iron content was proposed.     

红土化作用及红土的工程地质特性研究

本文根据有关红土的最新研究成果，结合在红土地区大量的工程实践经验及现场对红土宏观特性的仔细观察和反复比较验证，提出了红土化作用的机理、过程及基本模式。在此基础上对红土所具有的特殊工程地质性质进行了讨论。     

江西省铁路沿线网纹红土的工程地质特征

根据江西铁路沿线网纹红土的工程地质特性 ,通过土工试验及工程实践 ,介绍了在工程建设过程中对网纹红土的一些认识及对其危害性的处理方法     

乳状液膜法提取酸浸液中铁的传质研究

采用Span80-TBP-NH3.H2O体系乳状液膜法提取溶液中的Fe(Ⅲ),研究表面活性剂含量、载体含量、内水相试剂浓度、外水相硫酸浓度等对铁离子提取效果的影响。确定了膜相组成为Span80:TBP:石蜡:煤油(体积比)=5:4:2:89、内水相氨水浓度为1.5 mol/L,用微分法求得该反应的反应级数为nC≈1.     

Span80-TBP-NaOH体系乳状液膜法富集红土矿浸出液中镍的研究

采用Span80-TBP-NaOH体系乳状液膜法,提取红土矿浸出液中的Ni（Ⅱ）;测定了表面活性剂含量、载体含量、内相试剂浓度、外水相酸度、温度等对提取速率的影响.根据温度对提取速率的影响求出反应的表观活化能,确定了该反应过程的速控类型.在最适分离条件下,做二级提取实验,其提取效果可达90%以上.     

一种新型土壤强固剂加固红土试验研究

土壤强固剂是一种新型的加固土体复合材料。文中通过室内击实、直剪以及无侧限抗压强度对比试验 ,分析了一种新型土壤强固剂对云南红土的加固效果。试验结果表明 :这种新型土壤强固剂对红土样的最大干密度基本无影响 ,但可提高红土样的最优含水量 ,特别是抗剪强度和无侧限抗压强度都有显著提高 ,强度加固效果系数都大于 1,变形加固效果系数都小于 1,其加固效果优于粉煤灰。证明这种新型土壤强固剂能够显著改善土体性能 ,减小变形 ,提高土体的承载能力。     

红土镍矿火法冶炼技术现状与研究进展

镍是生产不锈钢的主要合金元素之一,随着硫化镍矿资源的日益贫乏和镍需求量的不断增加,如何绿色高效利用储量丰富的红土镍矿对不锈钢产业的持续发展具有重要的现实意义。火法冶炼工艺具有流程短、原料适应范围广等优点,现已逐渐成为红土镍矿利用的主流工艺。阐述了RK-EF法、回转窑直接还原-磁选工艺、转底炉-熔分炉工艺、鼓风炉还原硫化熔炼镍锍工艺、高炉法等主要红土镍矿火法冶炼工艺的特点和优缺点,总结了国内外研究现状和发展前景,对火法冶炼技术绿色高效利用红土镍矿资源提出建议。