Mineral and trace element composition of the Lokpanta oil shales in the Lower Benue Trough, Nigeria

The concentrations of minerals and trace elements in the Lokpanta oil shale from the Lower Benue Trough, Nigeria have been determined by X-ray diffraction (XRD) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), respectively. X-ray diffraction data were evaluated using the SIROQUANT™ interactive data processing system based on Rietveld interpretation methods. A new method of trace element determination in oil shale, involving LA-ICP-MS analysis of glass beads prepared by fusing oil shale ash on an iridium strip heater was used, and the accuracy of the method was assessed by including a standard shale reference material (SGR-1b) in the analysis program.The minerals in the raw oil shales are mainly quartz, calcite and clay minerals, with the latter being represented by kaolinite and interstratified illite/smectite. Ashes of the oil shale samples prepared at 815 °C have quartz and (in some cases) illite as the dominant mineral phases, along with a significant proportion of amorphous materials. The Lokpanta oil shales are highly enriched in some potentially hazardous trace elements, including V, Cr and Ni, when compared with oil shales from other deposits around the world. The results obtained for the trace elements in the reference material show that the LA-ICP-MS method described in this study is very accurate and precise for the determination of a wide range of trace elements in oil shales.     

Mineralogy, elemental composition and modes of occurrence of elements in Canadian feed-coals

Feed-coals used in some Canadian power plants were examined for their mineralogical and elemental composition. The mode of occurrence of elements (organic/minerals) in these samples were determined using sequential leaching by H₂O, NH₄OAc and HCl.Canadian feed-coals examined in this study are subbituminous to bituminous rank (calorific values: 19.62-29.88 MJ/kg). The sulphur content of these coals is 0.32-3.55%.Quartz and aluminosilicates (clay minerals and feldspar) dominate the mineralogy of these samples. The accessory minerals consists of pyrite, sphalerite, barite, calcite, anhydrite, chromite, zircon, biotite, and monazite, which occur as both primary and secondary cell filling types. An interesting mineral found in one of the subbituminous feed-coals is the gorceixite that is normally associated with degraded volcanic ash.The sulphur content of the feed-coals is an indication of their geological setting with feed-coal formed in a fresh water setting containing the least amount of S and those associated with evaporites having the highest S content.The concentrations of Cd, Cr, Cu, Hg, Ni, Se, V, and Zn in these Canadian feed-coals are low compared to world coals. Mercury content of these feed-coals ranges from 0.04 to 0.16 ppm. Mercury is mostly associated with the pyretic portion of coal and has direct correlation to As and S content in these coals. Arsenic in low sulphur coals is mostly associated with coal macerals and in higher sulphur coals with pyrite. About 47% of As in high sulphur coal is removed after leaching by HCl.Water soluble elements consist of Co, Ni and Mn, which are associated only with bituminous feed-coals. The removal of these elements by water is possibly due to an increased acidity of leaching solution and presence of soluble Cl and S.Beryllium and vanadium in low S coals are mostly removed after leaching by HCl, indicating a possible association with clay minerals. Limited Be and V is removed from lower clay mineral content coals; however, in high S content coals, more Be and V are removed.The speciation of As, Cr and Ni indicates that As is mostly present in the less-toxic form As⁺⁵ and Cr is present entirely as Cr³⁺, an essential human trace nutrient, found in both subbituminous and bituminous ranked coals. Nickel is present mostly as Ni²⁺ in oxygen coordination in these milled coals and carcinogenic compounds of nickel are not present in these feed-coals.     

Geological and Physical Factors Affecting the Friction Angle of Compacted Sands

This study evaluated the effects of physical characteristics and geologic factors on the shear strength of compacted sands from Wisconsin that are used as granular backfill for mechanically stabilized earth walls and reinforced soil slopes. Physical properties and shear strength were determined for 30 compacted sands collected from a broad range of geological deposits. Relationships between strength/deformation behavior, geologic origin, and physical properties were used to categorize the sands into four friction angle groups. Sands with the lowest friction angle are derived from weathering of underlying sandstones, and tend to be medium-fine, well-rounded, and poorly graded sands. Sands with the highest friction angle are from recent glacial activity and tend to be coarser grained, well-graded, and/or angular sands. A multivariate regression model was developed that can be used to predict friction angle (?′) of compacted sands from comparable geological origins based on effective particle size (D10), maximum dry unit weight (γdmax), and Krumbein roundness (Rs).     

KR脱硫渣矿物学特征及渣中硫行为

为提高KR脱硫渣的资源化利用水平,利用XRF、XRD、SEM+EDS对某厂KR脱硫渣的矿物学特征进行研究,并用热力学软件FactSage对渣中硫的赋存形式及析出规律进行研究。结果表明,采用石灰系脱硫剂的KR脱硫渣,渣中的主要矿物相为钙铝硅酸盐相、硅酸钙相以及尖晶石相。钙铝硅酸盐相为连续延伸的无定形状,表面光滑平坦,无孔隙和裂纹;硅酸钙相为无规则形状,且表面较为粗糙,有较多的孔隙和裂纹;尖晶石相尺寸大小不一,形状多呈不规则多边板形,少量? 欢ㄐ巫础５蔽露雀哂?220℃时,试验KR脱硫渣中的硫会以SO2的形式存在,CaS约在1220℃时开始析出,CaSO4在1160℃时开始析出,约在1100℃时,CaS和CaSO4的析出量不再随温度的降低而变化,且最终渣中析出CaSO4的较CaS高。     

工艺矿物学研究对选矿工艺的重要作用—以宁乡式鲕状赤铁矿为例

对鄂西宁乡式某矿区的矿样进行了详细的工艺矿物研究,结合宁乡式铁矿特性,不再单一的以某种矿物为目标,而是将可有效选别的集合体(鲕粒)和粒状赤铁矿作为单位,将选矿的选别目标进行了重新的归类和划分,并详细研究了各选别目标的工艺特性及其对选矿工艺的影响,为甄别合适的选矿工艺、确定最终的优质选矿流程提供了重要的依据。     

广东大尖山某铅锌多金属矿石工艺矿物学研究

广东大尖山某铅锌多金属矿石铅品位为1.10%,锌品位为4.95%,银品位为23.4 g/t,铁品位仅10.79%,硫品位为7.30%,其中铅、锌、银具有较高的利用价值。为给该矿石选别工艺流程的制定提供依据,对该地区代表性矿石进行了工艺矿物学研究。结果表明:(1)矿石金属矿物主要有方铅矿、铁闪锌矿、闪锌矿、黄铁矿、磁黄铁矿、黄铜矿、白铁矿,银分散在方铅矿、闪锌矿等硫化矿物中,未形成独立银矿物。(2)矿石闪锌矿、方铅矿、黄铁矿呈致密块状分布;黄铁矿、闪锌矿呈浸染状分布;磁黄铁矿、黄铁矿、闪锌矿、方铅矿组成不规则团块与脉石构成不规则斑染状分布;由方铅矿、闪锌矿及脉石组成的矿脉穿切黄铁矿、石英、绢云母;黄铁矿呈自形晶产出,浸染状分布,被闪锌矿、方铅矿脉穿切交代。(3)方铅矿和铁闪锌矿、闪锌矿的嵌布粒度均属极不等粒嵌布,方铅矿嵌布粒度较铁闪锌矿、闪锌矿更为分散。(4)方铅矿单体解离较差,-0.076 mm粒级仅有90.38%单体解离,-0.045 mm粒级也未达到完全解离;铁闪锌矿、闪锌矿单体解离度较方铅矿高,-0.076 mm粒级92.91%已单体解离。     

Importance of Mineralogy in the Geoenvironmental Characterization and Treatment of Chromite Ore Processing Residue

The geoenvironmental characterization of COPR at two deposition sites (New Jersey and Maryland) included geotechnical, chemical, mineralogical, and leaching analyses of three main chromite ore processing residue (COPR) types [gray-black (GB), hard brown (HB), clayey (C)]. Quantitative mineralogical analyses were instrumental in the delineation of the geochemical differences between the three COPR types, which enabled a framework to predict COPR response to potential remediation schemes. Overall, COPR mineralogy resembled cement, with hydration and pozzolanic reactions dominating its geochemistry. GB COPR was largely unreacted despite its prolonged exposure to humid conditions, while HB COPR was completely hydrated and contained high Cr(VI) concentrations. The two materials were chemically similar, with dilution accounting for the chemical and density differences. While the total acid neutralization capacity (ANC) of GB and HB was the same, the ANC at high pH (8–12) was higher in HB due to the dominance of hydrating materials, leading to more buffering capacity and lower Cr(VI) leaching levels. It is concluded that GB and HB were derived from the same ore and process and that postdepositional transformations account for the emergence of HB layers in COPR sites. The physicochemical properties of HB [hardness, high and inaccessible Cr(VI), high ANC] are complicating factors for in situ COPR reductive treatment in the presence of HB.     

鞍山式铁矿重选精矿工艺矿物学研究

随着辽宁某选厂重选精矿的铁品位变低,其已不能作为精矿产品汇入总精矿,为给该选厂工艺流程改善提供指导,从化学组成、元素赋存状态、矿物组成、矿物间的嵌布关系及连生关系等方面,对重选精矿进行了工艺矿物学研究。结果表明：重选精矿铁品位为60.62%,铁主要赋存于赤铁矿和磁铁矿中,主要的脉石矿物为石英;铁主要分布在-0.074 mm粒级,铁在该粒级分布率高达84.47%,TFe品位64.52%,只有通过细磨才能实现铁矿物与脉石的较好解离;在有用矿物与脉石的连生体中,以赤铁矿与脉石结合形成的连生体为主,其次为磁铁矿、赤铁矿与脉石矿物结合形成的连生体;随着粒度变细,试样中赤铁矿和磁铁矿的单体解离度快速提高,尤其在-0.045 mm粒级产品中,绝大多数赤铁矿和磁铁矿颗粒完成了单体解离;赤铁矿和磁铁矿的浸染粒度以中粒、细粒嵌布为主,中粒级试样中脉石含量仍较高,细粒赤铁矿和磁铁矿含量较高,铁主要赋存在-0.074 mm粒级中。建议采用细筛分级-载体浮选工艺进行试验研究,即重选精矿筛上返回再磨,筛下产品进入浮选,背负细粒磁选精矿完成回收。     

瓷石的工艺矿物学特征与选矿研究

论述了瓷石的工艺矿物学持证，研究了瓷石的选矿工艺，并对江西宁村和上祝瓷石进行选矿实验取得了满意结果。