Measurement of Granule Attrition and Fatigue in a Vibrating Box

This paper describes a new test machine that has been designed to measure the strength of single particles in the size range of 10²–10³ μm. The device is a vibrating box that subjects each particle in the sample to a large number of impacts of known but variable strength. By tracking the size and shape of the particles as a function of the number of impacts, their strength characteristics against the mechanisms of fracture, fatigue and attrition can be differentiated. The number of particles tested in one sample is restricted in order to make any particle‐particle interaction negligible but is sufficiently large that the distribution of these characteristics can be determined.     

Using Regularization Methods for Image Reconstruction of Electrical Capacitance Tomography

Image reconstruction of electrical capacitance tomography (ECT) is a typical inverse problem owing to non‐linearity and ill‐posedness. At the same time, progress towards the solution of this kind of problem has been made at good speed as a branch of mathematics in the past three decades. In this paper, most of the regularization tools developed for the inverse problem are applied to the reconstruction of various simulated images by ECT. The results show promise for ECT image reconstruction by regularization methods. The non‐linearity of the sensitivity matrix seems to be the major problem.     

Development of Displacement Current Tomography System

A novel tomography system based on the displacement current induced by charged particles has been developed. This measurement is sensitive to both the particle charge and velocity. This system differs from previous ones because it demands only one plane of sensors to measure velocity. This paper starts with modeling of the induction caused by a single charged particle. The model is validated by experiments and by three dimensional field calculations. This basic model is extended from the single particle system to multi-particle systems by Fourier transform and is also confirmed by experiments. Finally, a new image reconstruction method for this displacement current tomography system is proposed and the reconstructed images are compared with simple particle flows.     

In situ SAXS studies of the formation of sodium jarosite

This paper reports the results of time‐resolved synchrotron small‐angle scattering and powder diffraction experiments where natrojarosites were synthesized in situ in order to observe the species produced at the earliest stages of nucleation. The sample temperatures were 333, 353 and 368 K. These compounds were synthesized by co‐precipitation from solution on the Small and Wide Angle Scattering and Powder Diffraction beamlines at the Australian Synchrotron. Scattering data were collected continuously throughout the syntheses. The results presented here show that the first particles to form in solution appear to be amorphous and nucleate on the walls of the reaction vessel. Crucially, there is a single nucleation event which forms particles with an elliptical disc morphology which then grow uniformly before natrojarosite crystallization is observed in complementary powder diffraction data. This nucleation event may represent the key to controlling the growth of jarosites in industrial and environmental settings.     

A furnace and environmental cell for the in situ investigation of molten salt electrolysis using high‐energy X‐ray diffraction

This paper describes the design, construction and implementation of a relatively large controlled‐atmosphere cell and furnace arrangement. The purpose of this equipment is to facilitate the in situ characterization of materials used in molten salt electrowinning cells, using high‐energy X‐ray scattering techniques such as synchrotron‐based energy‐dispersive X‐ray diffraction. The applicability of this equipment is demonstrated by quantitative measurements of the phase composition of a model inert anode material, which were taken during an in situ study of an operational Fray–Farthing–Chen Cambridge electrowinning cell, featuring molten CaCl₂ as the electrolyte. The feasibility of adapting the cell design to investigate materials in other high‐temperature environments is also discussed.     

Characterization of Agglomerated and Aggregated Aerosol Particles Using Image Analysis

Accurate particle size characterization of aggregated and agglomerated particles is only possible by analysis of photographs. Both the primary particle size and the morphology of the aggregate are important experimental results. Since standard image analysis techniques for particle size analysis usually recognize only single particles, a new programme, called here Sparse Hough Transformation, was developed for the automated recognition of spherical particles within an aggregate. The method is shown to perform well, even for images with many overlapping particles. The structure of the aggregate is analysed using the fractal dimension, determined from the density-density correlation function. Finite size effects, important when dealing with aggregates containing few primary particles, are taken into account by including a cut-off function.     

The Use of Azimuthal Intensity Variations in Diffraction Patterns for Particle Shape Characterization

Forward light scattering is a well established technique for measuring particle size distributions. The light intensity fluctuations which can be observed in the diffraction plane of the instrument can be used to stabilize the inversion process [1]. Particle shape information is also present in these fluctuations. It is shown that an azimuthal-type of detector can be used to extract this information from the statistical correlations of the detector signals.