共查询到20条相似文献，搜索用时 31 毫秒
1.
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
2.
The performance of float-sink coal cleaning devices customarily is characterized by a distribution curve, in which the percent of feed reporting to clean coal is plotted against specific gravity. For a given vessel and a given feed a family of distribution curves can be obtained, each having its own specific gravity of separation.This paper presents a method for combining these distribution curves at different specific gravities of separation, for a given coal cleaning vessel and a given feed, into a single, generalized distribution curve which is independent of the specific gravity of separation. This curve can be expressed in tabular form or it can be represented mathematically by an exponential type equation, known as a Weibull function.A different generalized distribution curve will be obtained for each of several different size fractions. A method is presented for utilizing these curves with feeds which encompass a broad spectrum of sizes.The well-known concepts of error area and probable error are extended to the generalized distribution curve. It is shown that the conventional probable error, and — under certain conditions — the conventional error area, are directly proportional to the specific gravity of separation for a given vessel and a given feed size. 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.
In jigging, amplitude and frequency of pulsation, and feed characteristics are the most important process parameters. Effects of these parameters on particle segregation during jigging are studied and explained through experimental as well as numerical means by drawing parallel to liquid/solid fluidization process. This is permissible because jigging could also be viewed as a repetitive process of fluidization and defluidization. Unlike a normal fluidization process, in jigging, particle segregation takes place under rapid rate of change of water velocity. The rate of change of water velocity is decided by the maximum water velocity of the jig cycle, which in turn is controlled primarily by the amplitude. Experimental evidence of the role of maximum water velocity on jigging is given. Next, the feed to the jig that varies in both size and density is conceived as a mixture of many density variant binary systems. This way, the effect of feed characteristic is conveniently analyzed through several indicators of the binary feed namely size ratio, volume fraction, and particle size. Finally, the effect of frequency is studied by considering the particles in the jig bed analogous to tuned mass dampers. This concept is used to explain the preferential segregation of particles at certain jig frequency. 相似文献
5.
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
6.
Regrinding is an essential step in many mineral processing flowsheets as a final preparatory step for mineral separation. It is normally carried out in open-circuit ball mills or rod mills. Wide fluctuations occurring in the hardness and size distribution of feed materials to regrinding mills result in a nonuniform product fineness and processing inefficiency. Using a previously developed regrinding model, this paper presents the dynamic analysis and design considerations of a control system for open-circuit grinding, using the traditional P-, PI-, and PID-control algorithms. This study shows the utility of simple analysis techniques in designing a mineral process control system with special attention given to the effect of sampling and analysis time on control system performance. 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.
T.P. Meloy 《International Journal of Mineral Processing》1984,13(4):313-324
Eight, simple theorems are derived for locked particles. For the locked particles: the volume or mass size distribution curve slope is steep — 1.6 to 2.0, the surface area is constant, the total volume is proportional to the fineness of grind, and the fraction of particles locked at a given size decreases with particle size. 相似文献
9.
10.
D. W. HUMPHRIES 《Sedimentology》1966,6(4):241-245
A technique for mounting sand grains in transparent plastic rods is outlined. Four simple devices to facilitate the preparation and handling of the rods are described. These comprise a demountable mould, a grain lifter, a polishing jig and a microscope stage jig. 相似文献
11.
A study on selection of probability distributions for at-site flood frequency analysis in Australia 总被引：1，自引：0，他引：1
Ayesha S. Rahman Ataur Rahman Mohammad A. Zaman Khaled Haddad Amimul Ahsan Monzur Imteaz 《Natural Hazards》2013,69(3):1803-1813
The most direct method of design flood estimation is at-site flood frequency analysis, which relies on a relatively long period of recorded streamflow data at a given site. Selection of an appropriate probability distribution and associated parameter estimation procedure is of prime importance in at-site flood frequency analysis. The choice of the probability distribution for a given application is generally made arbitrarily as there is no sound physical basis to justify the selection. In this study, an attempt is made to investigate the suitability of as many as fifteen different probability distributions and three parameter estimation methods based on a large Australian annual maximum flood data set. A total of four goodness-of-fit tests are adopted, i.e., the Akaike information criterion, the Bayesian information criterion, Anderson–Darling test, and Kolmogorov–Smirnov test, to identify the best-fit probability distributions. Furthermore, the L-moments ratio diagram is used to make a visual assessment of the alternative distributions. It has been found that a single distribution cannot be specified as the best-fit distribution for all the Australian states as it was recommended in the Australian rainfall and runoff 1987. The log-Pearson 3, generalized extreme value, and generalized Pareto distributions have been identified as the top three best-fit distributions. It is thus recommended that these three distributions should be compared as a minimum in practical applications when making the final selection of the best-fit probability distribution in a given application in Australia. 相似文献
12.
粒度分布数据的计算机光滑插值绘线方法 总被引：3，自引：0，他引：3
以一种单调光滑的分段插值函数为基础，在计算机上实现了光滑的粒度分布累积频率曲线和频率分布曲线的绘制。这一方法为编制软件在计算机上实现粒度分析数据高效高质量的系统处理提供了基础，为粒度分布特征的普遍表述向更精确、更全面的方向深化提供了途径。 相似文献
13.
K. Viswanathan 《International Journal of Mineral Processing》1985,14(2):127-147
A comparative assessment of the attrition phenomena occurring in fluidized beds, pneumatic pipelines, and spouted beds has been made using the distributed fracture model. The controlling mechanisms responsible for attrition in these systems have been identified. The model is shown to correctly predict the interrelationship between the fraction of feed attriting and the distribution of sizes produced on attrition. A simple method is developed to estimate attrition in continuous fluidized and spouted beds. An analytical expression is also derived to calculate the size distribution of the product fines when the feed follows a specific distribution equation. 相似文献
14.
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
15.
《Physics and Chemistry of the Earth, Part A: Solid Earth and Geodesy》2000,25(2):169-174
A simple cutoff approach based on the capillary bundle model has become an industrial standard method to quickly obtain the irreducible water saturation from NMR T2 distribution. However this approach is not always valid. To overcome the shortcoming of the capillary bundle model that ignores pore-pore connectivity, we have conducted a two-phase flow simulation in a CT-based pore network. The CT -based pore network is a representation of a real rock pore structure that is described by a binary X-ray tomographic data set. Simulation on such network mimics a process of the porous plate measurement. The generated capillary curve is quite reasonable. The oil accession distributions at different water saturations plotted as a function of pore size provide an insight for the immiscible displacement process in the real rock pore structure. Water is trapped not only in dead ends but also in the well-connected pores due to a pore level by-pass mechanism. At the capillary end point pressure, a plot of the trapped water distribution as a function of pore size has the same lognormal distribution as the pore size distribution, which is much different from what the simple capillary bundle model suggests. 相似文献
16.
Classification tests have been carried out on limestone in 10.2-, 15.2-, 25.4- and 38.1-cm “Krebs” hydrocyclones in order to study the effect of cyclone diameter on the reduced-efficiency curve. Parameters which were varied included the vortex finder and spigot diameter, throughput and feed-solids content, but the feed size remained constant. The reduced-efficiency curve was found to be constant for all tests and the conclusion is that for constant feed size this curve is a function of the material being classified only for geometrically similar cyclones and is independent of the cyclone diameter. 相似文献
17.
广义极值分布频率曲线,也可采用均值、变差系数和偏态系数等三个统计参数来进行计算。通过建立离均系数表,可以方便地进行频率分析计算。现以澧水某站年最大流量系列为例,采用广义极值分布的适线法进行频率分析计算,成果表明广义极值分布具有一定适应性。 相似文献
18.
The literature review on discrete element (DEM) model analysis of jigging reveals that an idealized fluid behavior is assumed and the damping of the fluid motion across the mineral bed is generally ignored. A microscopic model based on the principles of Computational Fluid Dynamics (CFD) is used to simulate the liquid flow and stratification of coal particles with a wide size range and density distribution in jigging. Fluid motion is calculated by directly solving the Navier–Stokes equations. Coal particles are moved in a Lagrangian frame through the action of forces imposed by the fluid and gravity. Particle effects on fluid motion are fed back at each time step through calculating the velocity disturbance caused by the particle. Particle–particle and particle–wall collisions are also considered. The snapshots of particle configurations for the simulation of stratification in oscillating flow show that the model predicts the macroscopic behavior, such as segregation and stratification, of particles reasonably well. 相似文献
19.
面波频散曲线的提取是面波资料处理的关键.鉴于S变换和广义S变换不能全时段兼顾频率分辨率和时间分辨率的缺点,提出了含可变因子广义S变换进行瑞雷面波频散曲线的提取方法.可变因子的引入使得高斯窗函数的宽度随频率发生变化时具有目的性,而不是简单地随着频率的增大而变窄.该方法可以有针对性地改善局部频段(特别是低频段和高频段)的频率分辨率及时间分辨率.通过理论模型和实际资料试算表明:含可变因子广义S变换提取面波频散曲线的方法具有可行性和实用性. 相似文献
20.
针对油气勘探中大地电磁(MT)数据易受各类干扰的污染,且信噪难以分离的问题,把基于广义S变换的时频滤波技术应用于MT数据处理中来,得到MT数据的S域时频分布,分析受噪MT数据在S域的时频分布特征,再在S变换时频域进行时频阈值去噪,并对滤波后的S域时频谱进行逆变换重构,分离得到去噪后的MT数据。给出了基于广义S域时频滤波的方法原理与应用步骤,对被污染的仿真和实测MT数据进行了时频阈值滤波,并与小波阈值去噪方法进行了比较研究。结果表明：基于广义S变换的时频滤波方法可有效抑制MT数据中的干扰,从噪声信号中分离出有效的大地电磁数据,且减少了人为参与,提高了MT勘测的数据质量。 相似文献