UBC Theses and Dissertations
The physical and chemical characteristics of kimberlite Howe, Diane Joan
A detailed study of the physical and chemical characteristics of kimberlite fines provided the basis for this study which was to determine the factors that govern the flocculation processes. These studies showed that there are many physical and chemical characteristics which are similar and many which differ between the kimberlite samples. The mineralogical study showed that the type of minerals present were the same for each pipe, however their modal distribution varied. This difference is related to the type and intensity of alteration and the subsequent formation of clay-type minerals. The presence or absence of these alteration minerals also accounts for the differences found in the particle size distributions, in the surface areas, in the cation exchange capacities and densities. The zeta potential was found to be similar, with ranges between -15 to -35 mV, between the samples. Tests also showed the zeta potential could be further reduced by the addition of a Mg2 + ion. This reduction in zeta potential did cause some of the pipes to coagulate and settle. Although no one variable could be found, flocculant preference of the individual kimberhte samples appears to be related to the interaction of particle and polymer as a function of solution chemistry. It is postulated that the dissolution of magnesium bearing minerals (olivine) play a significant role. The dissolution of olivine increases the concentration of Mg2 + in solution thus promoting the attraction between particles and between the particle and polymer. In fact, chemical leach tests showed that Mg2 + and Ca 2 + were readily leached into solution, albeit not all pipes leached these ions at the same rate. Values of up to pH 9.5 can be accounted for by the dissolution of olivine. Alkaline pH's >9.5 are assumed to be the result of the formation of calcium hydroxide after the magnesium ion precipitates out of solution as Mg(OH)2. Pipes which produce a very high pH therefore do not have the Mg2 + ion readily available in solution to act as a coagulant. Coincidentally, these pipes required the addition of a coagulant to promote flocculation and a produce a clear supernatant.
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