Date of Award

6-1990

Degree Type

Thesis

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

Supervisor

O. E. Hileman

Abstract

The formation of hetero-epitaxial deposits of Sa, Pb and
mixed Ba/Pb and Ba/Ra sulfates on quartz and mica surfaces
has been demonstrated. The kinetics of their growth and
dissolution has been established. The importance of the
formation and dissolution of these deposits is found in the
observation that they are all host solids for the formation of
solid solutions of 228-radium (and by extension 226-radium).

Desorption studies caried out on Ba²⁺, Ca²⁺ and SO₄²⁻ from quartz and mica surfaces into water indicate that these
ions are strongly retained by mica surfaces, with retention
times which are of sufficient duration to permit the formation
of the potential host solids required by the National Uranium
Mine Tailings model.

The equilibrium solubility of PbSO₄ in Na₂SO₄ solutions
and in H₂SO₄ solutions from 0 to 6m has been measured
experimentally at 60ºC with subsequent modelling by means of
the Pitzer formulation for ion activities at high ionic strength.
The equilibrium solubility of BaSO₄ in H₂SO₄ solutions from 0
to 6m has been measured experimentally at both 25ºC and
60ºC with subsequent modelling. Such data are a necessary requirement for the modelling of the evolution of uranium mill wastes by the National Uranium Mine Tailings model and for
understanding the fate of radium during the milling and
leaching processes.


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