Selective separation of boron values from the tailing of a colemanite processing plant

摘要

As a primary boron mineral, colemanite is commonly associated with clay minerals. As the particle size of the colemanite ore gets smaller the clay/boron ratio increases. In the industrial practice of recovering boron from rich deposits in Turkey, the low grade fraction (typically finer than 3 mm) is discharged to tailings pond in order to produce a high grade concentrate (e.g., >40% B2O3) as a feed to boric acid plants. The current study examines the recoverability of boron values from the tailing pond. Since flotation is a well-established method for separation of fines, interfacial aspects associated with colemanite-clay separation have also been investigated.The effects of four collectors, namely sodium oleate and sodium dodecyl sulphate (SDS) as well as two commercial collectors, R801 and R825 were evaluated. The maximum difference in electrokinetic potential of colemanite and associated clay corresponds to about pH 9.3 which represents a pH buffer for the flotation environment. The electrokinetic behavior of these flotation systems was discussed in terms of electrostatic adsorption tendencies and their relevance to selective flotation. Overall, the flotation performance of R801 was clearly superior to that of other collectors. This was also supported by wettability data that indicated the highest contact angle with this collector. Batch flotation tests with deslimed tailing material have demonstrated that target concentrate grades of >40% B2O3 are achievable at excellent recoveries reaching 99%.