Dielectric behaviour of MgFe2O4 prepared from chemically beneficiated iron ore rejects

Chemically beneficiated high silica/alumina iron ore rejects (27–76% Fe₂O₃) were used to synthesize iron oxides of purity 96–98% with SiO₂/Al₂O₃ ratio reduced to 0.03. The major impurities on chemical beneficiations were Al, Si, and Mn in the range 2–3%. A 99.73% purity Fe₂O₃ was also prepared by solvent extraction method using methyl isobutyl ketone (MIBK) from the acid extracts of the ore rejects. The magnesium ferrite, MgFe₂O₄, prepared from these synthetic iron oxides showed high resistivity of ∼ 10⁸ ohm cm. All ferrites showed saturation magnetization, 4πM_s, in the narrow range of 900–1200 Gauss and the Curie temperature,T, _cof all these fell within a small limit of 670 ± 30 K. All ferrites had low dielectric constants (ε′), 12–15, and low dielectric loss, tan δ, which decreased with the increase in frequency indicating a normal dielectric dispersion found in ferrites. The presence of insignificant amount of polarizable Fe²⁺ ions can be attributed to their high resistances and low dielectric constants. Impurities inherent in the samples had no marked influence on the electrical properties of the ferrites prepared from the iron ore rejects, suggesting the possibility of formation of ferrite of constant composition, MgFe₂O₄, of low magnetic and dielectric losses at lower temperatures of 1000°C by ceramic technique.     

Diagenesis of the Funing Sandstones (Paleogene), Gaoji Oilfield,Subei Basin,East of China

This study deals with the diagenesis of sandstones of the Funing Formation at Gaoji Oilfield, Subei Basin, east of China. Mineralogy was determined by X-ray diffraction and scanning electron microscopy. The sandstones are lithic arokose and feldspathic litharenite, with less subarkose and sublitharenite. The diagenetic processes include compaction, cementation, replacement, and dissolution, indicating an opportunity to study the diagenetic sequence. Among the diagenetic minerals, carbon forms the major cement, appearing as dominate pore occluding cement in the Funing sandstones. Smectite is helpful for the formation of chlorite. Quartz overgrowth may be inhibited by illite and chlorite. Pore types existing in the study area include a mix of primary intergranular, secondary intergranular, secondary intragranular, moldic pores, and micropores. The quality of reservoir sandstones is environmentally selective, and pores are mainly developed in sand bars, distributary channels, underwater distributary channels, and overflow environments.     

赤泥水热分级脱碱过程微粒元素分布规律及脱碱性能差异

基于赤泥微粒的工艺矿物学特征,对拜耳法赤泥进行水热分级脱碱,研究不同粒级赤泥微粒的矿物组成和元素分布规律,并对不同粒级赤泥微粒的脱碱性能进行对比。结果表明,原赤泥试样中氧化钠含量为7.34%,进行分级后,不同粒级赤泥在元素和矿物组成上,表现出较大差异,粗粒级(+100μm)氧化钠含量为3.23%,中间粒级(-100+38μm)氧化钠含量为2.32%,微细粒级(-38μm)氧化钠含量为8.22%。微细粒级赤泥产率为65.12%,粗粒级和中间粒级的产率分别为15.29%、19.58%。赤泥分级脱碱前后的化学成分分析和XRD检测结果显示,反应温度对赤泥脱碱具有显著影响,在反应温度为50℃,时间1 h,转速550 r/min的条件下进行脱碱时,钠碱含量明确减少,分级脱碱效果明显。脱碱后赤泥的氧化钠含量根据粒级由粗到细分别为1.04%、0.28%、3.01%,微细粒级脱碱难度较高,脱碱效率仅为63.38%。不同粒级赤泥的Na元素含量、物相组成,赋存状态及脱除的难易程度均存在差异,赤泥分级能有效提升赤泥处理效率,降低脱碱成本。     

湖北省郧县徐家院铅锌多金属矿地质特征及找矿潜力

通过对郧县徐家院铅锌多金属矿地质特征、物化探异常及遗留问题等系统研究和分析，得出该区存在寻找铅锌多金属矿的较大潜力的结论。     

排土场回收矿石的实践

针对石人沟铁矿露天开采后期生产能力下降、矿石资源紧缺的矛盾，探索性地对废弃排土场中残存的矿石进行了回收，有效缓解了生产矛盾，并取得了良好的经济效益和社会效益。     

东鞍山铁矿石工艺矿物学及选矿工艺的研究与建议

介绍了东鞍山铁矿不同类型铁矿石的化学成分、矿物成分、结构构造特点及铁的赋存状态，研究了东鞍山铁矿石的粒度特征，分析了东鞍山烧结厂改造前后各工艺流程的特点，提出了东鞍山烧结厂进一步完善工艺流程的建议。     

用非线性建模选取选矿工艺参数值

神经网络在用于选矿厂建模过程中，一般只用于预测选矿效果，很少用于指导选矿现场。本研究利用神经网络，从选矿生产历史数据本身出发，找到精矿品位和回收率与药剂用量的非线性关系，利用此关系确定药剂的用量，可用于指导选厂实际生产过程。     

沿脉进路无底分段崩落法的进路参数研究

分析了无底柱分段崩落法回采工作面放矿口尺寸对矿岩散体移动规律的影响，并根据椭球体放矿理论和随机介质放矿理论，得出了增大出矿口尺寸和全断面均匀放矿可改善矿石散体的移动条件进而增大矿石放出量的结论。将此结论应用到厚度中等及以下、倾角较大、下盘围岩不稳固矿体的无底柱分段崩落法开采实践中，其放矿效果明显改善，极大地提高了矿石回收率。     

OpenGL在放矿仿真系统开发中的应用

在Windows2000环境下，基于VisualC#和OpenGL开发了放矿仿真系统。介绍了使用OpenGL进行三维视景仿真设计的方法及放矿仿真系统的几个关键技术。该仿真系统采据放矿模型运算的结果，采用动画显示技术动态地绘制出模拟过程中每一位置的矿岩运动情况，即做到放矿的实时三维模拟仿真。     

改进的模拟退火算法在原料矿混匀优化中的应用

运用改进的模拟退火算法对钢铁原料矿的混匀进行了优化计算，计算结果符合实际生产情况，表明改进的模拟退火算法是一种切实可行的优化方法，该算法为原料矿混匀问题的优化求解提供了新的思路。