Dispersion—flocculation studies on a Goethite-clay system

Dispersion–flocculation studies on a Goethite–clay system using flocculants were carried out as a function of flocculant concentrations, pH of slurry, time of agitation and dispersant dosage. Also, the effects of pH and polymer concentrations on the adsorption behaviour of the system were investigated. Results show that well flocculated goethite was preferentially obtained from 4% goethite/kaolinite clay suspensions, with 50 ppm causticised starch in the slurry at pH values of 3–11·5 and with 50 ppm polyacrylamide at pH values of 3–8. Good flocs were also obtained on flocculation of the goethite suspension with 50 ppm polyacrylamide at pH values of 5–7, while the kaolinite suspension did not respond to the same dosage of causticised starch in the same pH range. Results further reveal that for the goethite/kaolinite suspension, the best results was obtained with 50 ppm polyacrylamide at pH values of 7–10. Based on the data generated in the study, it was concluded that causticised starch is a better flocculant than polyacrylamide for goethite suspensions although polyacrylamide is an excellent flocculant for kaolinite suspensions.     

Extraction of valuable metals from low nickel matte by calcified roasting−acid leaching process

A calcified roasting−acid leaching process was developed as a highly effective method for the extraction of valuable metals from low nickel matte in the presence of CaO additive. The influences of process parameters on the metal extraction were studied, including the roasting temperature, roasting time, addition of CaO, H₂SO₄ concentration and liquid−solid ratio. Under the optimum condition, 94.2% of Ni, 98.1% of Cu, 92.2% of Co and 89.3% of Fe were recovered. Additionally, 99.6% of Fe was removed from the leachate as goethite by a subsequent goethite iron precipitation process. The behavior and mechanism of CaO additive in the roasting process was clarified. The role of CaO is to prevent the formation of nonferrous metal ferrite phases by a preferential reaction with Fe₂O₃ during the roasting process. The metal oxides (CuO and Ni_xCu_1−xO) remained stable during high-temperature roasting and were subsequently efficiently leached using a sulfuric acid solution.     

山西某针铁矿选矿试验研究

该铁矿为鸡窝矿，有用矿物以针铁矿为主，其次为褐铁矿，矿石性质复杂，且大部分矿石呈细粒嵌布。原矿分级后对粗、细粒级分别采用干式磁选和湿式磁选两种工艺，都获得了较好的指标，精矿品位比原矿提高6％以上，达到企业要求，可配矿后作为炼铁原料。     

天然针铁矿热处理产物的结构特征

采用X射线粉末衍射仪、热重分析仪、透射电子显微镜、比表面积分析仪等研究空气中热处理铜陵新桥天然针铁矿的结构演化。热分析结果表明:针铁矿在154.5℃开始脱羟基向赤铁矿转变,在300℃时相转变完全。煅烧温度250~700℃之间,虽然产物都是赤铁矿,但都保持针铁矿原有的形貌特征,且产物的比表面积和孔结构随煅烧温度变化有明显差异。300℃煅烧产物由于脱羟基水,针铁矿假象颗粒内部出现1~5μm大小的孔,且具有最大的比表面积(107.8m2/g);随着煅烧温度升高,由于赤铁矿晶体生长变大,赤铁矿晶体间空隙变大,比表面积逐步降低;煅烧温度大于700℃时,由于赤铁矿晶粒生长开始出现颗粒间烧结现象,针铁矿假象颗粒内部和外部空隙进一步减少,当煅烧温度达到900℃时,针状形貌变成粗短圆柱状,此时比表面积降至最小值为4.8m2/g。结果表明:铜陵新桥针铁矿可以在300~400℃空气中煅烧获得高比表面积的纳米孔材料,在环境保护领域具有很大的潜在应用价值。     

Negative effects of dissolved organic compounds on settling performance of goethite in Bayer red mud

Goethite, a typical iron-containing monomineral in red mud, was synthesized under the simulated Bayer digestion condition during the alumina production. The effects of dissolved organic compounds including sodium formate, sodium acetate, sodium oxalate, sodium salicylate and disodium phthalate on the settling performance of goethite slurries were studied. The settling performance of the slurries was also investigated with the addition of self-made hydroxamated polyacrylamide flocculant (HCPAM). The adsorption mechanism of dissolved organic compounds on the goethite surfaces was studied by FT-IR and XPS, respectively. The results show that the addition of organic compounds lowers the settling performance of the slurries and a deterioration in settling performance is observed in the order of sodium oxalate > sodium salicylate (～ disodium phthalate) > sodium formate > sodium acetate. Moreover, HCPAM can efficiently eliminate the negative effects of sodium formate, sodium acetate and sodium oxalate on the settling performance of the goethite slurries, but it can only partially improve the settling performance of the goethite slurries containing sodium salicylate or disodium phthalate. FT-IR and XPS results show that these organic compounds are chemically adsorbed on the goethite surface.     

锌冶炼过程中除铁方法的研究进展

湿法炼锌厂产出的铁渣量大,不仅含有H2S04,而且还有Cu、Cd、Pb、Zn、In、As、Sb、F、Cl等有害杂质,长期堆存会造成环境污染和资源浪费,必须加强研发渣的无害化处理和回收方法.本文综合论述了国内外各种除铁方法和最新进展,可为湿法炼锌厂的除铁工艺选择提供参考.针铁矿法、赤铁矿法、渣中铁的深加工方法最有可能实现渣的无害化处理,值得重点开发和应用.     

Preparation of Nanosized Hematite Particles by Mechanical Activation of Goethite Samples

Nanosized single crystals of hematite with a very narrow particle size distribution were prepared by mechanical activation of two different goethite samples. Both goethite samples transformed completely into hematite after 70 h grinding time. Transmission electron microscopy showed that the final particles were spherical in shape and of ∼17 nm average particle size. This particle size was coincident with that estimated from specific surface measurements, indicating that the hematite samples consisted of nonporous and nonaggregated particles. The crystallite size, calculated from the broadening of the XRD peaks, in the hematite samples indicated that particles consisted of single crystals. No influence of the precursor was observed in the products, so both goethite samples yielded identical rounded single crystals with a narrow particle size distribution.     

凹凸棒石-针铁矿改性麦秸木质陶瓷的微观结构

以凹凸棒石、针铁矿和小麦秸秆为原料,添加少量的环氧树脂作为黏结剂,在适宜的温度和气氛下煅烧,同步完成了生物质碳化、凹凸棒石热活化及针铁矿的还原,获得了具有高气孔率和强磁性的凹凸棒石-针铁矿改性麦秸木质陶瓷,利用XRD和SEM分析了原料质量比及焙烧温度对其物相及微观结构的影响。结果表明:凹凸棒石-针铁矿改性麦秸木质陶瓷是一种非晶态多孔质碳素材料,在相同温度下,原料的质量比对其物相几乎无影响;随着焙烧温度的升高,凹凸棒石的特征衍射峰逐渐消失,凹凸棒石-针铁矿改性麦秸木质陶瓷中有新的物相产生。     

某微细粒嵌布复杂铁矿的选矿工艺流程研究

矿石中铁矿物主要以不规则状产出,粒度以微、细粒为主,嵌布关系复杂,且矿物种类繁多,主要为赤铁矿、假象赤铁矿,其次为磁铁矿、褐铁矿、针铁矿及少量菱铁矿,尚有微量磁赤铁矿、自然铁、磷铁矿等;脉石矿物主要为石英,其它是辉石、绿泥石、云母、长石、黏土矿物等;本研究采用合理多段、适当细磨工艺,强化微、细粒赤铁矿及假象赤铁矿的回收。试验推荐重选—磁选—反浮选联合流程,获得品位为67.79%、回收率为83.23%的铁精矿。