Environmental Isotope Investigation of Groundwater in the Sarcheshmeh Copper Mine Area,Iran

Precipitation, surface, and groundwater samples were collected during 2009–2010 in the Sarcheshmeh copper mine drainage basin, Kerman Province, Iran. Groundwater samples were collected from both shallow and deep aquifers. All of the samples were analyzed for stable isotopes, deuterium (²H), and oxygen-18 (¹⁸O), and some were analyzed for tritium (³H). The results show a more restricted range of isotopic composition in groundwater samples than in precipitation samples based on the isotopic composition of the precipitation. The isotopic composition of surface and groundwater samples plot to the right of the local meteoric water line of the Sarcheshmeh area and around the evaporation line, indicating that the groundwater within the study area originates from meteoric water that has undergone secondary evaporation before or during recharge. Tritium was below the detection limit in the deep groundwater samples while shallow groundwater samples had tritium concentrations between 1.2 and 1.7 TU, which indicates a longer residence time for deep groundwater.     

Successful Use of Geoelectrical Surveys in Area 3 of the Gol-e-Gohar Iron Ore Mine,Iran

Geoelectrical surveys were conducted in Area 3 of the Gol-e-Gohar iron ore mine to provide geological and hydrogeological information. Open pit mining is currently underway in the northern part of the Area, and underground mining operations are planned for the southern section. Groundwater has already been encountered in the open pit mine. Twenty five resistivity soundings were first performed in the mine area; then, induced polarization (IP) measurements were carried out to remove ambiguities between clay and water-bearing layers. To investigate fault zones as water conduits, combined resistivity profiling surveys were also carried out. These measurements provided a detailed structural map of the pit area. Resistivity and IP results have subsequently been confirmed by observations at three monitoring wells and the mine pit wall. Monitoring and piezometric wells will be drilled at locations suggested by the results of the geoelectrical surveys. Drainage galleries may be developed to dewater the open pit mine. However, another option being considered is to start the underground mining with the idea that it will initially simply serve as a dewatering mechanism.     

Groundwater Circulation and Origin of Salinity in a Multi-aquifer System: The Gohar-Zamin Mining Area,Iran

Mine Water and the Environment - Determining the origin of groundwater in active and unstable mining environments has proven quite challenging. We evaluated the origin and salinity of the...     

非洲铬铁矿资源分布与找矿潜力

铬是我国确定的战略性矿产,同时也是我国大宗紧缺矿种之一,对外依存度极高。全球超过一半的铬铁矿资源分布在非洲,南非、津巴布韦和马达加斯加是非洲最重要的铬铁矿资源国。非洲铬铁矿床主要有层状型和豆荚状型两种类型,前者集中分布在布什维尔德层状基性-超基性杂岩体和津巴布韦大岩墙内,后者在非洲南部和中北部的绿岩带内都有产出。本文综合成矿地质条件、资源分布特点、勘查开发现状等因素,划分出4个铬铁矿资源潜力区,并进行了初步的找矿潜力分析。     

西藏铬铁矿资源的合理开采和利用刍议

西藏地区的铬铁矿蕴藏量和开采量均居全国首位。国内铬铁矿石现产量远远满足不了冶金、化工、纺织等行业的生产需要。文中就西藏铬铁矿石的开采与利用状况，提出了相应的改革建议。     

The reduction of chromite in the presence of silica flux

The mechanism and kinetics of the carbothermic reduction of a natural chromite was studied at 1300–1500 °C in the presence of silica. Thermogravimetry, X-ray diffraction (XRD) analysis, energy dispersive X-ray analysis (EDAX) and metallography were the experimental techniques used. Silica affected the reduction at and above 1400 °C. A two stage reduction mechanism was established. The first stage, up to about 40% reduction, is primarily limited to iron metallization and zoning is observed in partially reduced chromites. In this stage silica does not interfere with the reduction. The second stage is mainly confined to chromium metallization and formation of a silicate slag alters the reduction mechanism. Ion-exchange reactions between the reducible cations (Cr³⁺ and Fe²⁺) in the spinel and the dissolved cations (A1³⁺ and Mg²⁺) in the slag allow further reduction. Due to the very high driving force for the diffusion, the overall process is shifted toward a more chemical reaction controlled mechanism. A generalized rate equation was then applied to the individual metallization curves of iron and chromium from which respective rate constants and diffusion coefficients were derived. The rate constants were in the range 6.74 × 10⁻⁴–9.01 × 10⁻⁴ s⁻¹ for iron and 7.20 × 10⁻⁴–8.50 × 10⁻⁴ s⁻¹ for chromium reduction at 1500 °C in the presence of silica. At 1500 °C, the corresponding diffusion coefficients were in the range 3.14 × 10⁻⁸–4.78 × 10⁻⁸ m²/s for Fe²⁺ diffusion in the spinel and in the range 1.70 × 10⁻⁸–2.03 × 10⁻⁸ m²/s for the respective diffusion of Cr³⁺. Finally using Arrhenius plots activation energies were derived.     

Petrology,physicochemical and thermal analyses of selected cretaceous coals from the Benue Trough Basin in Nigeria

Abundant coal resources that were previously neglected due to a crude oil boom need revitalisation and integration into the national electricity mix to address the energy demands of the Nigerian population.Selected coal samples from the Benue Trough sedimentary basin in Nigeria were examined by various techniques,including proximate and ultimate analyses,organic petrography,Fourier transform infrared ray spectroscopy,and thermogravimetric analysis.Based on vitrinite reflectance,the Lafia-Obi(OLB),Garin Maiganga(GMG),Imiegba(IMG),and Okaba(OKB)coals are classified as subbituminous,while the Lamja1(LMJ1),Lamja2(LMJ2)and Chikila(CHK)coals are high volatile B bituminous.The Enugu(ENG)coal is on the boundary between subbituminous and high volatile C bituminous.Organic petrographic results indicate vitrinite and fusinite contents steadily increase from the Lower Benue Trough coals to the Upper Benue Trough coals,while semifusinite and total mineral contents follow a reverse pattern.Thermal decomposition occurred in three stages,i.e.,drying,devolatilization,and coke formation above 700°C;and the coal reactivity follows the following order,ENG>IMG>IGH>CHK>LMJ>OKB>GMG>LFB.The higher temperatures(above 900°C)are required to decompose the coals for efficient energy recovery.The LMJ1,LMJ2,OLB,CHK,GMG,and OKB coals can be exploited for electricity power generation.However,the Imeagha and Enugu coals are best suitable for both cement and power generation.     

世界铬矿开发现状及投资建议

铬作为我国一种重要的战略资源。近年来,其消费量居世界第一位,然而,我国铬资源严重匮乏,供需矛盾日益突出。基于这一国情,鼓励开发利用国外资源将是缓解我国资源紧张最为有效的方法之一。本文从近年全球铬矿产出水平和主要生产国家、世界级大型铬矿山开发情况和主要铬生产企业产能情况三方面进行了系统的分析,得出适应我国实施海外投资的以下三点形势:1津巴布韦资源量大,但开发程度低;2国外铂族金属矿山中铬金属浪费严重;3世界铬矿业公司兼并、收购活动频繁。基于这一形势,提出如下建议:1津巴布韦是我国实施海外投资的优选地区;2我国可通过与国外铂族金属企业合作,综合利用铂矿中的铬资源;3我国可在频繁的的兼并、收购活动中作好投资规划和准备;4需借鉴国内外企业投资铬业的成功经验等。     

丁青宗白蛇绿混杂岩岩石地球化学及Sr-Nd-Pb同位素特征

丁青宗白蛇绿混杂岩位于班公湖—怒江蛇绿混杂岩带东部,研究区内主要由辉长岩组成。通过对辉长岩的岩石地球化学及Sr-Nd-Pb同位素进行测试分析,研究了丁青宗白蛇绿混杂岩中辉长岩的地球化学特征,探讨了岩浆源区及其结晶分异作用。岩石地球化学及Sr-Nd-Pb同位素特征反映出,丁青宗白蛇绿混杂岩中辉长岩的具有富镁、较贫碱、铝和钙的特点,且轻重稀土元素分馏不明显,基本不显Eu异常,稀土元素配分曲线呈宽缓右倾型。辉长岩具有较高的(~(87)Sr/~(86)Sr)_i和(~(143)Nd/~(144)Nd)_i,相对较高的~(207)Pb/~(204)Pb和~(208)Pb/~(204)Pb,说明辉长岩的源岩可能来源于富集地幔,并且在上升侵位过程中混入了地壳物质。     

Evaluating the Origin of Seepage Water in the Golgohar Iron Mine,Iran

The Golgohar mine produces iron ore from an open pit in south-central Iran that is now more than 100 m below the water table, and dewatering has not solved the mine’s water seepage problem. Previous studies had reported that Kheirabad (Sirjan) Playa, 13 km north of the mine, was the most probable groundwater source. A combination of geological, hydrogeological, hydrochemical, and isotopic techniques were used to evaluate the hydraulic connectivity between the mine and the lake, and to characterize the probable water sources. Thirty-two surface and groundwater samples were collected and analyzed for major and minor (Li, B, and Br) constituents. Ten water samples were analyzed for oxygen-18 and deuterium and three samples were analyzed for tritium. The results indicated that impermeable formations and very low-permeability alluvial deposits lie between lake and the pit. In addition, the chemical and isotopic signatures of the two water sources indicated different origins. Inverse geochemical modeling and the mine water’s isotopic signatures suggest that the water is coming from the surrounding alluvial aquifer, or is deep basin water from within the fractured bedrock, or a mixture of the two.     

Effects of frother type and froth height on the flotation behaviour of chromite in UG2 ore

About 70% of the UG2 reef consists of the gangue mineral chromite (FeO · Cr₂O₃). In the processing of UG2 ore by flotation for the recovery of platinum group elements (PGEs) the presence of chromite in the concentrates can cause serious downstream processing problems and a grade of less than 3% Cr₂O₃ is sought. This constrains operating procedures and compromises optimum recovery of the PGEs.In this study, the influence of the froth phase on the recovery of chromite was investigated by changing both frother type and dosage and froth height in batch scale flotation tests. The results obtained showed that it was possible to obtain concentrates with less than 3% Cr₂O₃ content by increasing the froth height, allowing for better drainage of both entrained gangue particles and coarse particles with low hydrophobicity. At a 3 cm froth height, very low water and mass recovery were obtained and thus low entrainment. Nevertheless a small amount of chromite particles coarser than 45 μm was persistently recovered which may be attributed to the true flotation of these particles.The mechanism of chromite recovery was discussed on the basis of the difference in the appearance of the froth structure and water recovery.     

沁水盆地安泽区块煤岩特征及分析

采取安泽区块3~#和15~#煤心样,依据宏观特征,将全区煤炭资源分为北-中-南3个区段,并分析其显微煤岩组分特征、裂隙和煤变质等特征。初步推断区内成煤环境存在显著差异。结果为煤炭资源的合理利用提供依据。     

伊朗SAGHAND矿主立井马头门施工

伊朗SAGHAND矿主立井设计有6个水平连接处，马头门施工是该工程的重点和难点。6个马头门结构复杂，地质条件各不相同，安全威胁大，施工中采取特殊的措施，保证了施工安全和工程质量，取得了良好的效果。     

Investigating the effects of particle shape on chromite entrainment at a platinum concentrator

In flotation, entrainment is undesirable as it results in the recovery of hydrophilic gangue particles which reduces the concentrate grade. For UG2 ore, a South African platinum group mineral (PGM) ore, entrainment is particularly problematic because it leads to the recovery of chromite in the final concentrate which can cause severe problems in the smelter. It is therefore important to understand all factors affecting entrainment. These factors include froth characteristics, as well as particle size distribution and density, which have been studied widely. Theoretically, they should also include shape, as shape affects drag coefficients of particles and thus hindered settling rates of particles within plateau borders. In this study, detailed mineral-specific shape characterisation with Quantitative Evaluation of Minerals by Scanning Electron Microscopy (QEMSCAN) was used to assess the effect of particle shape on chromite entrainment during flotation of UG2 ore at a South African platinum concentrator. This plant-scale study suggests that shape does affect entrainment, with more rounded particles showing higher entrainment than angular, elongated particles.     

西山煤田山西组煤层煤岩学和煤质特征

以西山煤田西峪煤矿山西组2~#、3~#煤为研究对象,采用显微光学、X射线荧光光谱法等方法,分析了其煤岩学、煤地球化学、煤相和煤质特征。结果表明:山西组煤层的显微组分以镜质组为主,其次是惰质组,壳质组含量极少;煤相主要为潮湿森林沼泽相区,GI指数不小于7.77,TPI指数介于1.32~1.77;2~#煤属易选、优等煤,3~#煤属难选、良等煤,变质阶段为Ⅴ-Ⅵ阶段。     

Electrochemical enhanced oxidative decomposition of chromite ore in highly concentrated KOH solution

A novel method which introduces an electrochemical field to enhance the oxidative decomposition of chromite in a KOH sub-molten salt medium was proposed and proven to be feasible and efficient. Under optimal reaction conditions (slot current density 750 A/m², alkali concentration 60 wt.%, reaction temperature 150 °C, alkali-to-ore mass ratio 6:1, and particle size <200 mesh), the extraction rate of chromium reached 99%, after reacting for 480 min. In comparison with the current liquid-phase oxidation technologies, the reaction temperature in the new approach is 150–250 °C lower, and the alkali concentration of the reaction medium is lower by more than 20%, showing substantial advantages in terms of energy efficiency, equipment corrosion alleviation and prospects for industrial application. The reaction kinetics study shows that the extraction process under optimal reaction conditions is jointly governed by surface chemical reaction and solid product layer diffusion with the apparent activation energy calculated to be 17.56 kJ/mol.     

Potential Release of Metals from Tailings and Soil at the Hamekasi Iron Mine,Hamadan, Iran

This study focused on acid neutralization reactions and the effects of water composition on the release and mobility of metals from mine tailings. The aims of this study were to: investigate leaching of metals from neutral mine tailings, determine the factors responsible for metal leaching, and investigate potential metal filtering by the soil. Tailings and soil samples were collected from an iron mine and analyzed. Equilibrium thermodynamic data and metal fractionation were then used to predict precipitation/dissolution of minerals and ion adsorption/desorption. Three column experiments were designed. The first column was filled with tailings, while the second column contained tailings above a layer of soil; both were leached with distilled water as rainfall. The third column was packed with soil and percolated with synthetic groundwater. The results indicated that iron (Fe) and zinc (Zn) mobility are mainly controlled by precipitation–dissolution mechanisms, while sorption onto oxides and carbonates limit the mobility of copper (Cu) and nickel (Ni). Cadmium (Cd) and manganese (Mn) mobility are affected by both mechanisms. Water discharging from column 3 (soil washed with groundwater) contained high concentrations of dissolved metals, indicating that water composition played an important role in metal mobility. Buffering minerals like carbonates and hornblende, chlorite, and albite decreased acid generation.