摘要:

AbstractThis paper describes preliminary work carried out on the applicability of fractal geometry in describing the products of comminution events.A nickel sulphide ore was subjected to two comminution events, impact shattering and ball milling. Fractal analysis was performed on samples of the resulting comminution products.Two differing fractal populations resulted, with the impact sample exhibiting particles having higher boundary fractal dimensions than the milled sample. The fractal dimension of the impact fragments increased with decreasing size, whereas the milled particles displayed a more complex distribution.The under‐fractal distributions, of the two populations of fragments, generate straight lines when plotted on Gaussian probability paper. This leads to the possibility of being able to predict the distribution of fragments, in fractal terms, of a particular material when subjected to comminutio

ISSN:0934-0866    

DOI:10.1002/ppsc.19930100102

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

摘要:

AbstractAn image analysis system for extracting on‐line quantitative geometric and densitometric information from images of ore samples is described. The apparatus employs a pulsed semiconductor laser as the light source for illuminating of a flowing stream of particles and a non‐interlaced solid‐state TV camera as size measurement device in a shadowgraph imaging system. The problem of the sampling volume is discussed and several size distributions of solid particulates are presented. The particle size measurement range is 2

ISSN:0934-0866    

DOI:10.1002/ppsc.19930100103

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

摘要:

AbstractAccurate information on the size distribution of fly ash is needed to determine its role in the radiation transfer process in pulverized coal combustors. The Coulter Multisizer was used to determine the size distribution in the particle diameter range 1–200 μm. To size over such large diameter ranges, data must be obtained using several orifices, and then combined. In order to use the smaller orifices, the larger particles have to be removed from the sample. A wet‐sieving apparatus, designed for accurate separation of the particles by size, is described. A scheme for combining data obtained using orifices of different diameters is presented. It appears from this study that the lower limit of size measurement using an orifice is set by sensitivity, rather than by signal/noise. A lognormal distribution function, truncated outside the measurement limits, fits the size distribution data well. This function allows detailed size information to be stored compactly using four parameters. Size parameters for six fly ashes representative of U. S. coals are prese

ISSN:0934-0866    

DOI:10.1002/ppsc.19930100104

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

摘要:

AbstractThe angular patterns of the polarization ratio were calculated for droplets with diameters between 0.020 and 50 μm at 500 nm wavelength. It was observed that the patterns for droplets slightly smaller than 1 μm were dominated by a backward peak belonging to the glory. The peak was successfully used to characterize aerosols of light and heavy oils with a Junge‐like size distribution. Experiments conducted with heavy oil sprays produced by air‐assisted atomization presented the same feature. A quantitative comparison of the experimental results with the Lorenz‐Mie theory showed that the size distribution of these sprays was

ISSN:0934-0866    

DOI:10.1002/ppsc.19930100105

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

摘要:

AbstractIt is often necessary to estimate the properties of particle size distributions from limited samples taken from large populations. When the distributions are broad, and higher order moments required, as in the case of volume based particle size distributions, the inferred parameters d3,50(volume median diameter) and GSD (geometric standard deviation) can have high intrinsic errors not immediately obvious to the measuring scientist. We show that there is a critical number of particles,Ncrit, which must be counted or else the error may blow up catastrophically.Ncritis very sensitive to the width of the distribution, and is approximately proportional to GSD11We develop formulae to estimate the random sampling error inherent in measured values of the d3,50and GSD for the log‐normal distribution; compare the predictions to a typical experimental particle size measurement; and then generalize to the median of any arbitrary moment, dr, 5

ISSN:0934-0866    

DOI:10.1002/ppsc.19930100106

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

摘要:

AbstractA scattered light photometer which monitors the particle number concentration of aerosols is described. The photometer measures the scattered light from illuminated submicron particle clouds with known material properties at certain scattering angles. Intensity ratios in combination with the degree of polarization are used to determine the mean particle diameter and the geometric standard deviation of an assumed log‐normal particle size distribution. The determination of the particle size distribution is based on an algorithm which compares the measured and calculated (Mie theory) relative intensity quantities described. Furthermore, the particle number concentration is monitored from a single absolute intensity measurement at one scattering angle. In order to obtain quantitative results a spherical particle shape is require

ISSN:0934-0866    

DOI:10.1002/ppsc.19930100107

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

ISSN:0934-0866    

DOI:10.1002/ppsc.19930100108

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY

ISSN:0934-0866    

DOI:10.1002/ppsc.19930100101

出版商:WILEY‐VCH Verlag GmbH    

年代:1993

数据来源: WILEY