A Numerical Multi-Component Reactive Model for Pyrite Oxidation and Pollutant Transportation in a Pyritic,Carbonate-Rich Coal Waste Pile in Northern Iran

A one-dimensional numerical finite volume model is presented to simulate pyrite oxidation and reactive transportation of the oxidation products in a pyritic, carbonate-rich, coal waste pile. The proposed model incorporates the shrinking core concept for describing pyrite oxidation, pyrite surface area reduction, oxygen diffusion, and transport of the oxidation products through the waste pile. The model governing equations were solved using the PHOENICS computational fluid dynamics model. The accuracy of the model was verified with field data. Pyrite oxidation was more intense at shallower depths where oxygen decreased almost linearly from the pile surface to an approximate depth of 2 m. The lowest pH, 3.5, was predicted at a depth of 0.5 m. The waste pile has high neutralisation potential due to buffering by carbonate minerals. The maximum concentration of SO₄ ^2?, 31.6 mol/m³, was predicted at an approximate depth of 4 m and to remain constant throughout the rest of waste profile. Simulation of a scenario with a cap shows that iron and sulphate was removed from the upper parts of the pile; their peak concentrations shifted downward due to dilution. Oxygen source removal limited iron and sulphate production. These results will be useful for developing an appropriate remediation scheme.     

Mineralogical and Geochemical Characterization of Mine Tailings and Pb, Zn, and Cd Mobility in a Carbonate Setting (Northern Tunisia)

Millions of tonnes of Pb–Zn ore flotation tailings and waste rock have been discharged at sites in northern Tunisia without concern for environmental issues. The tailings are dominantly fine grained (<125 μm), with high porosity and permeability. The tailings were characterized to assess base metal (Pb, Zn, and Cd) mobility. The relatively low percentage of iron sulphide and the dominance of carbonates in the matrices of the tailings indicated that only neutral mine drainage is likely. Batch sequential testing showed that the calcium and sulphate, which are the major ionic species in solution, are derived mainly from the dissolution of gypsum and not from neutralization of acidity generated by pyrite oxidation. Yet, despite the carbonate setting, the resultant neutral to slightly alkaline pH, and prolonged weathering, the studied flotation tailings maintain their capacity to release contaminants, notably Zn and Cd, into the environment. The amount of Zn that dissolves (2,400 μg L^?1, on average), though significant, is below the background concentrations in the Mejerda River and the environmental norms established for surface waters. Pb concentrations come close to the standards, but only Cd (18 μg L^?1, on average) sometimes exceeds current river water concentrations and environmental standards.     

Detecting the Source of Contaminant Zones Down-Gradient of the Alborz Sharghi Coal Washing Plant Using Geo-electrical Methods,Northeastern Iran

Environmental contamination from the Alborz Sharghi coal washing plant in northeast Iran was evaluated with geo-electrical techniques. The internal structure of a coal waste pile was first studied using one dimensional geo-electrical techniques, including a Schlumberger array. The oxidised zone had low resistivity while the unoxidised shallower and middle to deeper levels had higher resistivity. Next, the geo-electrical surveys were repeated after 6 months to investigate possible changes in the oxidation zone associated with seasonal variations. Precipitation affected the shallower levels of the pile. Two dimensional geo-electrical surveys, including a dipole–dipole array, were then conducted between the pile and tailings impoundments. Low resistivity values in the area appeared to indicate contaminated zones at depth. Again, two surveys were conducted at a 6 month interval. Results indicate the transportation of contaminants to deeper layers due to atmospheric precipitation. Considering the expansion of the contamination zones, the results of prior chemical analysis of the tailings impoundment water, and the increasing trend of the resistivity values in the deeper layers of the pile, seepage from the tailings impoundment is the most likely source of pollution in the area.     

白龙选煤厂洗水平衡与闭路循环实践

介绍了白龙选煤厂煤泥水工艺流程、特点和管理方法及其保持洗水平衡 ,实现闭路循环的生产实践     

龙湖分公司选煤厂原煤准备系统技术改造实践

介绍了龙湖分公司选煤厂原煤车间的技术改造与效果     

Prediction of Pyrite Oxidation in a Coal Washing Waste Pile Applying Artificial Neural Networks (ANNs) and Adaptive Neuro-fuzzy Inference Systems (ANFIS)

Two models were evaluated as alternative methods for predicting pyrite oxidation in the Alborz Sharghi coal washing waste pile (in northeastern Iran). The first model applies a ‘feed-forward artificial neural network (ANN) with 4-7-1 structure’. The model uses depth, initial remaining pyrite fraction, mole fraction of oxygen, and annual precipitation as input parameters and returns the remaining pyrite fraction in the related depth of the pile as its output. In the second model, an adaptive neuro-fuzzy inference system (ANFIS), which uses generalised bell membership functions and the Takagi–Sugeno-type fuzzy inference system, was applied with the same input–output parameters. The correlation coefficient, root mean squared error, and average absolute relative error for the training stage of the ANNs were 0.81, 0.169, and 0.12, respectively, while the values for ANFIS were 0.91, 0.091, and 0.078, respectively. Comparison of the correlation coefficients and the error parameters revealed that both models successfully predicted remaining pyrite fraction from various depths of the pile. However, ANFIS was found to be more reliable and more accurate.     

复合正弦筛在洗煤厂输煤系统中的应用分析

介绍了复合正弦筛的工作原理,及其在洗煤厂输煤系统中的应用。认为复合正弦筛在筛分原煤工艺中工作稳定可靠、不堵煤、筛分效率高,从而提高输煤系统的经济技术指标。     

裕源矿选煤厂选煤方法及入洗方式的分析确定

分析了裕源矿选煤厂的煤质特点,对50～0 mm粒级原煤的选煤方法和原煤入洗方式以及-0.5 mm粒级煤泥的选煤方法进行了分析确定,得出结论:裕源矿选煤厂50～0 mm粒级原煤采用选前不脱泥无压三产品重介旋流器分选,-0.5 mm粒级粗煤泥采用煤泥重介分选,细煤泥采用浮选。     

末煤车间混料桶的更换与改进

原末煤车间的混料桶在使用中存在料桶变形 ,耐靡材料掉落等问题 ,影响正常生产。通过对原混料桶在设计上的改进和耐磨材料粘贴工艺的改进 ,解决了料桶变形和耐磨材料掉落问题 ,实现了正常生产。     

石灰混凝法处理洗煤废水的几个问题

试验研究了石灰投加方式、聚丙烯酰胺种类以及加药顺序对洗煤废水处理效果的影响。研究结果表明,石灰与聚丙烯酰胺的投加顺序对处理效果有显著影响,而且是先投聚丙酰胺的效果明显好于先投石灰;石灰的投加方式和聚丙烯酰胺的种类对处理效果也有不同程度的影响。     

洗煤废水难处理的原因及处理方法研究

分析了洗煤废水的特点及其难处理的原因,并依此提出用石灰和聚丙烯酰胺进行混凝沉淀的处理方法,同时对其实际工程应用、混凝机理进行了简单的介绍和分析。     

选煤创新无止境——冀中能源股份有限公司选煤煤质工作实践

简要介绍了冀中能源股份有限公司洗选加工现状和选煤工艺技改历程,重点阐述了公司选煤煤质管理工作中的亮点以及选煤煤质管理理念的创新过程。     

漳村选煤厂洗水平衡与闭路循环实践

介绍了漳村矿选煤厂煤泥水系统工艺流程、特点、管理方法。通过实践,认为煤泥水系统只有工艺 设计合理、设备运行可靠,同时经过科学管理才可以达到洗水平衡、闭路循环。     

镇城底选煤厂原煤仓基桩施工及检测

镇城底选煤厂原煤仓为钢筋混凝土筒体结构,由两个钢筋混凝土预应力筒仓组成,单仓直径30 m,地基采用钢筋混凝土灌注桩,桩底入岩2 m,直径1.8 m及1.2 m,设计桩长有19.5 m和18.5 m.桩基采用冲击钻成孔,由于该工程锚桩所提供反力不足,且检测工作要在开挖基坑后进行,无法采用传统的堆载进行静载试验,特采用锚桩内植入钢筋,利用多个油压千斤顶提供反力进行试验,为西山矿区首次应用.     

电石渣处理选煤废水的效果及作用机理研究

介绍了电石渣处理选煤废水的效果,并对电石渣处理选煤废水的作用机理进行了研究。研究结果表明:电石渣对选煤废水的混凝作用不是补给了OH~-,而是提供了大量的Ca~(2+),Ca~(2+)通过压缩双电层,破坏了煤泥颗粒的稳定性,从而使煤泥颗粒凝聚,OH~-和Ca(OH)_2对选煤废水的混凝不起直接作用。     

洗煤厂矸石再洗工艺与效果分析

主要阐述了七台河选煤厂矸石再洗的价值、工艺流程、再洗的效果、工艺改造支出、再洗的经济效益、工艺系统等问题。具有一定的借鉴意义。     

西曲矿选煤厂浮选尾煤回收系统的改造

西曲矿选煤厂根据矿井原煤中煤泥含量较以前有大幅增加的实际情况，对原有的浮选尾煤回收系统进行了改造和完善，采用了浓缩旋流器和高频筛，解决了浮选尾煤回收压力，取得了显著效果。     

新庄选煤厂洗水恶化问题及处理方法

分析了新庄选煤厂洗水恶化的原因,探讨了解决办法。