摘要:

AbstractA knowledge of the effects of the physical parameters of solids on the product quality – the property function – is necessary for selective optimisation, to determine the cause of discrepancies and to permit corrections to be made as early as possible in a process. Property functions apply not only to the end products but to every stage of the process. The particle properties of the end product affect the quality, for example the colour strength, while those of the intermediates influence processing properties, for example the filtration resistance and subsequent process stages such as washing and granulation.In order that the property functions can be determined, the properties, performance characteristics as well as physical characteristics, must be quantifiable. Particle measuring technology was initially restricted to the measurement of physical characteristics but is increasingly becoming concerned also with performance characteristics such as the flow behavior of bulk solids and their abrasion resistance. The remaining performance characteristics can either be estimated, quantified or merely treated qualitativ

ISSN:0934-0866    

DOI:10.1002/ppsc.19870040112

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

AbstractFractal geometry developed byMandelbrotis finding many applications in the description of rugged fineparticles and fineparticle systems such as packed powder beds. In the earlier publications dealing with the fractal structure of fineparticle boundaries a great deal of the experimental work was carried out manually. This was time consuming and limited the amount of investigative work which could be undertaken in a given context. In this communication several algorithms for automating the evaluation of the fractal dimensions of rugged fineparticle boundaries by automated image analysis are explored. Comparative data generated by the various procedures are presented.

ISSN:0934-0866    

DOI:10.1002/ppsc.19870040113

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

AbstractThe in‐situ determination of the molecular composition of aerosol particles, composed of DES and DBP and suspended in an air flow, is described. The laser‐Raman scattering technique was applied to determine the composition of a monodisperse, model aerosol, 10 m̈m in diameter, which flows through the scattering vo

ISSN:0934-0866    

DOI:10.1002/ppsc.19870040114

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

AbstractStudies of and experiences with the reduction of errors in test sieving are presented. The preparation of the test material and, above all, the errors in sample splitting are included in the considerations. Errors due to the manufacture of test sieves are discussed, for example the influence of the aperture width distribution. The method applied at the Forschungsinstitut für Aufbereitung (FIA) for the inspection and calibration of test sieves is described in detail. The use of test materials for the calibration of sieves is recommended

ISSN:0934-0866    

DOI:10.1002/ppsc.19870040115

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

AbstractAn evaluation was made to assess whether linear grade distribution measurements determined from polished sections of randomly oriented particles can be used to estimate the extent of liberation for multiphase particles of specified size. Two techniques, optical image analysis and microprobe analysis, were used to establish the linear grade distributions for samples of different composition from a copper porphyry flotation circuit and these two were found to be equivalent. An estimate of the variance in the experimental data was made by measuring the average chalcopyrite content in these samples and comparing the results to chemical assays. The statistical significance of the linear grade distribution data obtained by optical image analysis was assessed and, for a given accuracy, the number of particles required to obtain an unbiased representation of the sample was determined.

ISSN:0934-0866    

DOI:10.1002/ppsc.19870040116

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

ISSN:0934-0866    

DOI:10.1002/ppsc.19870040117

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

AbstractThe liquid‐air interface causes the droplet to act as an optical cavity which provides large internal fields and feedback. The stimulated Raman scattering (SRS) spectra of micrometer‐size water droplets containing different anions (e.g., NO 3−, SO 42−, and PO 43−) can be generated by a single laser pulse and detected by an optical multichannel analyzer. When the spontaneous Raman intensity of the ν1mode of the anions is larger than that of the O‐H stretching mode of water, the SRS spectra consist of the peak at ν1and multiple peaks of nearly equal wavelength separation within the O‐H stretching mode of water. These multiple peaks are associated with the morphology‐dependent resonances of a sphere and the refractive index of water. Thus, the wavelength spacing of these SRS peaks provides information on the droplet radius. At higher anion concentrations, sequentially pumped SRS involving the ν1anion mode can also be detected at Raman shifts equal to 2ν1and equal to the O‐H stretching mode plus ν1. The Raman shift of the ν1mode in wavenumbers provides m

ISSN:0934-0866    

DOI:10.1002/ppsc.19870040118

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

AbstractIn the measurement of dust particles or droplets with cascade impactors, coarser particles are lost both in the impactor and in the sampling train. In order to reduce these losses and to recover this coarse fraction, the use of a precollector is recommended. As a rule, measurements in industry must generally be made with sampling probes. It is, therefore, reasonable to combine the probe and precollector.We measured the particle losses which occur in probes as a consequence of sedimentation and inertial forces. Wall losses through turbulent deposition seem to play only a minor role. By adjusting the gas inlet to a nozzle‐impaction plate sampling system, the coarse fraction can be collected and assessed quantitatively. Particle losses in the subsequent probe and impactor can, thus, be kept very low.By using nozzles of different apertures and by varying the gas flow rate, isokinetic sampling conditions can be achieved. The collecting properties of the nozzle‐impaction plate system inlet correspond very closely to those predicted by impaction theory. A special adaptation of the nozzle can give a cut point of the precollector close to 10 microns. Cut points at greater particle sizes are not recommended because of uncontrollable particle losses in the pr

ISSN:0934-0866    

DOI:10.1002/ppsc.19870040119

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

AbstractAccuracy, range, noise tolerance and resolution of turbitidy spectra analysis as a particle sizing method are discussed with respect to simulated data and data on latex spheres. The fine structure in the turbidity spectra is used to measure multimodal distributions with no apriori assumptions about the distribution.

ISSN:0934-0866    

DOI:10.1002/ppsc.19870040120

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY

摘要:

AbstractCharacterization of the overall (lage scale) shape of rugged particles poses a problem which is not readily solved by existing shape analysis techniques. Recent research on the divider stepping method used in factal analysis has led to the examination ofpolygonal harmonicswhich can be constructed in both smooth and rugged particle silhouettes. Thepersistenceof these harmonics is defined as the ratio of the longest step length to shortest step length which can be used to create that harmonic. It is proposed that the persistences of the first three harmonics provide useful descriptors for particle shape. Variation of these persistences within several geometric figures is explored, protocols for the analysis are adopted and some preliminary work on rugged silhouettes is discussed. Characterization by this technique holds great promise in the development of a general approach to particle shape description.

ISSN:0934-0866    

DOI:10.1002/ppsc.19870040121

出版商:WILEY‐VCH Verlag GmbH    

年代:1987

数据来源: WILEY