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The current work proposes a novel approach to the production of sorbent materials, which integrates recycling of calcium silicate-based industrial residues and sequestration of carbon dioxide in the process of accelerated carbonation. The concept was tested on model substrates of suitable mineralogy, namely Portland cement and dicalcium silicate, which were carbonated, and examined by nitrogen adsorption, XRD, NMR, SEM, TG-DTA analytical techniques. The carbonated materials were evaluated in batch sorption studies with the solutions of cadmium, lead, nickel, cobalt, zinc, strontium and cesium. The findings of the structural examination indicated the transformation of nesosilicate-type calcium silicates during carbonation into polymerized Ca-silicate frameworks, aragonite (in carbonated cement only) and calcite. The NMR investigation, for the first time, described in detail the nature of polymerized silicates (predominantly Q3 and Q4 silicon environment) in carbonated cement and dicalcium silicate. The carbon dioxide uptake measured by thermogravimetric analysis was equivalent to 480 kg/t and 370 kg/t of CO2 reacted with dicalcium silicate and Portland cement, respectively. Batch sorption experiments demonstrated better metal removal efficiencies by carbonated cement, particularly for cadmium and cesium. It was concluded that the metal removal mechanisms ranged from adsorption (e.g. ion-exchange, complexation, isomorphic substitution) to surface and bulk precipitation. The main solubility-limiting phases identified for cadmium, lead, strontium and zinc were otavite CdCO3 (only detected in carbonated cement), (hydro-)cerussite, strontianite, and hydrozincite. Cobalt, nickel, cesium were selectively sorbed within the Si-rich phase of both carbonated cement and dicalcium silicate. The leach study demonstrated an adequate containment of sorbed/precipitated metals within carbonated cement (= 2.5% leached) and carbonated dicalcium silicate (= 12% leached) in water. Metal mobility, however, increased during the exposure to acidic conditions, with = 5% of cadmium, lead, cobalt, nickel and 15- 75% of zinc, cesium, strontium being mobilized into leachates.

vi, 146 leaves : ill. ; 25 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.1974) from the Dept. of Applied Mathematics, University of Adelaide

In recent years a number of research centres have endeavoured to provide a mathematical model that indicates the chief characteristics of ore flow in the sublevel caving mining method. Optimization of the design parameters for sublevel caving has ensued with the objective of maximizing ore recovery while minimizing waste dilution. Past studies have been confined by two simplifying assumptions: that the region of flow be approximated by a simple mathematical function, and that the flow analysis is static, ie extraction is calculated by employing an idealized ore-waste boundary position for each ring. Further investigation into models of ore flow has been stimulated on two counts.1. full scale tests have indicated that a more complex description is required;2. as a design tool, a dynamic analysis that monitors the displacement of the broken rock mass during extraction would yield more realistic recovery predictions under operating conditions, and enable variations on the method to be evaluated.This study reviews the various formulations currently available, or being developed to describe the flow of granular material. A viable solution in a mining context would be three dimensional, time dependent, and incorporate stress conditions. Although workers in diverse fields have analyzed the problem no solution exists at present. The majority of studies are either empirical in nature, or deficient in one or other of the above criteria. Two approaches are developed and implemented on a digital computer:(i) stochastic flow model(ii) empirical flow model based on the results of modelling studies, and full scale test. Although a number of concepts introduced in these models remain to be verified, the validity of these models would be measured by their success or failure as a simulation tool in a mining environment.

Thesis(MSc)--University of Stellenbosch, 2008. / Bibliography. Also available via the Internet.

Thesis (M.Eng.(Mining Engineering))--University of Pretoria, 2000. / Includes abstract in English. Includes bibliographical references.

Thesis (M.S.)--University of Missouri, School of Mines and Metallurgy, 1922. / The entire thesis text is included in file. Typescript. Title from title screen of thesis/dissertation PDF file (viewed April 7, 2010)