Effect of temperature and impurities on electrostatic separation of boron minerals

Although the element boron is virtually a nonconductor, a series of hydrated boron minerals, colemanite, ulexite and borax were found to exhibit varying degrees of conductivity. The conductivity acquired by boron and clay minerals is ascribed to the presence of micro impurities in the form of substituted alkali earth elements such as lithium and strontium. While temperature has a pronounced influence on the conductivity of ulexite and borax, colemanite is not so sensitive to changes in temperature. This behavior correlates well with the onset of dehydration of the former boron minerals. The accompanying clay minerals, characterized by montmorillonite, also act as conductors and increasing the temperature does not cause any difference in their conductivity. Beneficiation strategies for each boron mineral on the basis of differences in conductivities of the accompanying minerals is proposed.