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1.
In an earlier paper (1978), Gottfried presented a method for combining distribution data for float-sink coal-cleaning devices into a single generalized distribution curve which, for a given device and feed size, is independent of specific gravity of separation. A non-linear, exponential-type equation was utilized to represent the generalized distribution curve, along with the corresponding generalized probable error. Distribution data for six common coal-cleaning devices have previously been treated by this method.This paper is an extension of two previous studies (Gottfried, 1978, 1980). The method described above is applied to three different float-sink coal-cleaning devices: Baum jig (replacing previously reported results), Batac jig and Dynawhirlpool separator. Results for the Baum jig and Batac jig reflect a two-stage separation process, with a set of generalized distribution curves obtained for each stage and another set for the overall separation. Several different feed size fractions are given for each vessel. 相似文献
2.
Byron S. Gottfried 《International Journal of Mineral Processing》1981,8(1):89-91
An earlier paper by this writer presented a method for combining distribution data for float-sink coal-cleaning devices into a single, generalized distribution curve which is independent of the specific gravity of separation. A nonlinear exponential-type equation was used to represent each of the curves and to determine the corresponding generalized probable error. Performance data for five common coal-cleaning devices were analyzed using this method.In this paper the method is applied to another common coal-cleaning device — the sand cone. Numerical values are presented for the constants in the exponential-type generalized distribution equation and for the corresponding generalized probable error. Several different feed size-fractions are considered. 相似文献
3.
P.C. Kapur 《International Journal of Mineral Processing》1983,10(2):81-88
A method is presented which seeks to overcome a number of disadvantages that are inherent in the conventional practice of plotting the Tromp curve and analysing it for its various measures, e.g., specific gravity of separation, probable error and error area. A sufficient condition is established for extracting the appropriate criteria of the sharpness of classification, which are independent of coal-feed distribution in specific gravity. Partition area, a modified areal measure, similar to the conventional error area, of the equipment's deviation from ideal classification behavior is derived from the theoretical partition function. A purely numerical procedure is developed for locating the specific gravity of separation and the partition area. Unlike the Tromp-curve-based conventional procedure, the proposed histogram-based method is fast, more convenient and objective for analysing the coal-cleaning plant data. 相似文献
4.
T.P. Meloy 《International Journal of Mineral Processing》1983,10(1):61-80
In mineral processing and coal cleaning operations, there are two classes of unit operations used in the separation processes. The first type — crushing, grinding, pelletizing and settling — modifies the size distribution of the feed. The second type — heavy media, sizing, flotation, magnetic, electrostatic and jigging — separates the particles. In these latter unit operations, the size distribution is not changed; rather, the feed stream is split into a product and waste stream based on subtle physical and physicochemical differences between the different types of feed particles. In separation unit operations, the mathematical functions, representing the behavior of the unit operations, are easy to manipulate. Thus, a number of theorems, useful to both the plant designer, and the plant engineer, can be proven.The work presented in this paper makes the fundamental assumption of linearity as do all current plant design analysis systems. The linearity assumption states that in a separation operation, there is no particle-particle interaction effecting the probability that a particle will be selected for the product or waste stream. In other words, if one doubles or triples the feed rate to a unit operation, the fraction of particles of a given characteristic selected to appear in the product stream remains unchanged. In actuality, this assumption is not true because higher feed rates affect the behavior of separation operations. However, when designing a plant, one can calculate the feed rate to a given unit operation and then select a piece of equipment large enough to handle the computed tonnage. Thus, the designed circuit behaves linearly. 相似文献
5.
煤系关键金属的开发利用对于缓解我国战略性矿产资源紧缺具有重要意义。内蒙古胜利煤田乌兰图嘎低阶煤中除富集关键金属Ge以外,同时富集有害元素Be、F、As、Hg、Sb和W,出于对关键金属的提取利用及环境保护2个方面考虑,须对研究区煤炭进行洗选处理。基于前期研究认识,浮选对于乌兰图嘎煤中As、Sb和W脱除效果相对较好,对于F和Hg的脱除效果较差,基于此,采用浮沉实验(重选法)以及XRD、XRF、SEM-EDS和EMPA等实验方法和测试手段,研究关键金属Ge以及Be、F、As、Hg等有害元素在不同密度级煤中的分布特征,结果表明:(1) 乌兰图嘎煤中矿物主要包括石膏、石英、黄铁矿、高岭石等,矿物含量随煤密度级增大而增加,电子探针分析结果表明,Co、As、Sb和Hg赋存在黄铁矿中。(2) 经过重选,低密度精煤中Ge元素富集,表明Ge主要以有机态存在,Be、F、As等可能与有机质相关,或者赋存在嵌布于有机质中的微细粒矿物中,煤中Hg和大部分亲石性元素在高密度级煤中含量较高,表明其赋存在矿物中。(3) 重选对于Hg元素的脱除效果较好,对Be、F、As和一些亲硫或亲铁性元素浮选脱除效果优于重选。建议乌兰图嘎低阶煤使用重选?浮选联合脱除法进行有害元素的脱除。 相似文献
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The results of experiments on a 40 cm × 40 cm grate-discharge ball mill have been analysed for variation of mill hold-up weight of solids with solids feed rate, weight percent solids, mean feed particle size, material specific gravity and work-index. It is shown that mill hold-up weight is independent of the material specific gravity and mean feed particle size, and it varies linearly with solids feed rate and weight percent solids, at least over the range of practical interest. The variations in the transport behaviour of different materials have been attributed to the differences in the size distribution of the mill hold-up solids. It is shown that work-index can be used as the material characteristic for the development of an empirical correlation. Variation of mean residence time of solids with solids feed rate and weight-percent solids is also discussed. 相似文献
7.
T.C. Rao M. Vanangamudi K.Hanumantha Rao 《International Journal of Mineral Processing》1982,9(3):235-243
Experiments were carried out on coal fines of two different washeries, at different periods of agglomeration, to determine the size distribution of agglomerates with changes in feed size, pulp density and furnace oil dosage. It is found that the size distribution of the agglomerates follows a self-preserving growth. This behaviour has been generalised using a reduced dimensionless size axis to obtain a characteristic curve. It is shown that this curve is affected only by the nature of the feed and not by the process variables. An equation has been suggested to quantify this characteristic curve of the oil agglomeration process. 相似文献
8.
Beneficiation and direct reduction of the Ramim iron ore was studied. Feed concentrates were obtained by gravity concentration of oolites followed by wet, high-intensity magnetic separation. Poor liberation prohibits physical concentration of goethite from oolites. These concentrates were directly reduced with different reductants at varying temperatures, followed by dry magnetic separation. Quality of concentrates depends on temperature, iron content in feed, type of coal, residence time, and composition of pellets. Conditions of optimum temperature range 1250–1275°C, unmixed pellets, high iron content in feed, dense high carbon reductant, and 15 min residence time resulted in grades and recoveries better than 90%. It is shown that segregation and growth of the metallic iron nuclii must be achieved in order to get superior yields. 相似文献
9.
A microcomputer program for simulating coal-cleaning distribution curves has been developed and includes six different models and two different optimization methods. By displaying the simulated distribution curves on a graphic screen, the curves for different models can be compared and the most suitable model selected. The importance of using this graphics criterion as well as the conventional statistical measurements of error is illustrated. This program requires no user knowledge of either computer programming or of the mathematical procedures. 相似文献
10.
探索了一种由土壤基本物性指标、气象数据预测非饱和土表层蒸发过程的方法。通过土壤基本物理性质（颗粒分布、土粒相对密度、干密度）预测出土-水特征曲线（SWCC）,进而得到土壤气相对湿度与含水率的关系,采用Penman-Wilson模型预测出了非饱和土表面的蒸发曲线。通过该方法,只需实地采取土样,获取其基本物理性质,由任意时刻土壤的含水率及气象数据就能预测出该时刻土表的蒸发速率。采用自制的自动蒸发测量系统进行浅层土蒸发试验,得到了蒸发曲线,与预测结果进行比较发现预测蒸发过程与实测结果一样皆由临界含水率和风干含水率将其分为3个阶段：稳定阶段、减速阶段和残余阶段,且蒸发量吻合,证明了所提出方法的准确性和实用性,对工程界估计土表蒸发量,确定水流量边界有重要意义。 相似文献
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毛管压力是影响煤层气赋存和开发的重要参数,为建立能够有效表征高阶煤煤岩毛管压力曲线的数学模型,以高阶煤为研究对象,开展了高压压汞实验,系统评价了目前常用的典型毛管压力曲线数学模型的适应性,建立拟合程度更高的数学模型。结果表明,6块高阶煤煤样毛管压力曲线基本没有中间平缓段,整体表现为向左上方凸出的形态,与常规砂岩、低阶煤差异明显;BC模型、贺承祖模型和Li模型均不能很好地拟合高阶煤的毛管压力曲线;建立的新毛管压力曲线数学模型,能够很好地拟合高煤阶煤样毛管压力实验数据,拟合程度达到97%以上;在双对数坐标中,毛管压力和最小毛管压力的对数差与进汞饱和度与最小毛管压力的对数差呈线性关系,可利用该线性关系直接求取毛管压力模型的斜率a和幂指数b,求解步骤较为简单;在其他条件相同时,毛管压力与斜率a和幂指数b均成反比。 相似文献
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Three types of distribution curve error are defined, i.e., the fitting deviation, the real deviation and the test error. Since the absolute distribution curve is never known, both the real deviation and the test error are unknown. Only the fitting deviation can be calculated and is a measure of the difference between a calculated distribution curve and the experimental data. However, the real deviation is of primary importance in evaluating the reliability of calculated distribution curves. This paper uses a microcomputer to simulate absolute distribution curves and obtains numerical relationships between the real deviation, the fitting deviation and the test error.More than 500 tests using a microcomputer show that a relationship exists between the fitting deviation, test error and real deviation. In most cases, the fitting deviation and the real deviation are close to each other. Both the fitting and the real deviation are smaller than the test error if the selected model is suitable. 相似文献
15.
Sripriya Rajendran M. NarasimhaA. Dutta M.K. SinhaArun Misra 《International Journal of Mineral Processing》2006
The biased subdivision of slurry feed to a number of unit operations in parallel results in each unit operating under different density volumetric flow rate, feed concentration. Consequently some of the units may operate under sub-optimal conditions leading to reduced operating efficiencies of sizing and cleaning units. The objective of this work was to identify the reasons for biased slurry subdivision in the feed distributor of Washery-II, West Bokaro, Tata Steel, Jamshedpur, India. A lab model of the feed distributor was set up at R&D using the principles of geometric similarity and dynamic similarity. A number of experimental investigations were carried out based on Design Of Experiments and the results analysed using ANOVA. The variation of feed rate of coal and its size distribution through different outlet ports were quantified through two terms, the coal split ratio and the variation index. The design of the insert, the number of water inlets, and the feeding position of coal in the distributor were the most important factors affecting the variation index. In case of coal split ratio, apart from the first two variables, none of the others had a significant effect. Four water inlets with symmetrically arranged outlets, equal water flow rate in the inlets and the material being fed in an annular ring into the distributor was found to reduce both the coal split ratio and the variation index. 相似文献
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A coal preparation plant typically operates with multiple cleaning circuits to clean individual size fractions of run-of-mine coal. Coal preparation plants are traditionally optimized using the equalization of incremental product quality approach. Individual cleaning circuits are operated at the same specific incremental product quality so that the targeted overall plant product quality is achieved. Over the years, it has been well established that equal incremental product quality approach maximizes plant-yield for a given product quality constraint. 相似文献
18.
Jan D. Miller Chen-Luh Lin Lukasz Hupka Mohamed I. Al-Wakeel 《International Journal of Mineral Processing》2009,93(1):48-53
Procedures for 3D mineral liberation analysis by X-ray micro CT (XMT) are presented and discussed including the construction of liberation-limited grade/recovery curves for specific feed materials. In this way, actual separation efficiencies can be compared to what might be expected for a perfect separation limited only by the extent of liberation. It is shown that 3D mineral liberation analysis based on XMT is preferred to 2D section analysis which overestimates the extent of liberation. By way of example, procedures and experimental results are presented and discussed for feed material in the case of phosphate rock flotation. 相似文献
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为查明抚顺煤矿采空区的位置、深度和分布范围,综合考虑城市中影响物探方法的因素,首次在该地区采用高精度重力测量方法进行采空区探测。先通过分析采空区的物性差异,建立理论模型进行正演计算,预研究重力方法的适用性。然后在研究区布设大比例尺面积性高精度重力测量工作,通过对布格重力异常进行位场分离、三维视密度反演和边界识别计算,推断了煤矿采空区的位置、深度、边界及该区内的构造分布。研究结果表明,高精度重力测量方法结合有效的数据处理方法,能在城市煤矿采空区的探测中发挥重要作用。 相似文献