Beneficiation and applications of an Egyptian bentonite

Samples of Egyptian bentonitic sediments, representing Gabal Hamdal (Miocene) of Abu-Zeneima locality, were evaluated by different techniques for some applications such as bleaching, refining of oils and drilling mud. Mineralogically the samples were characterized as low grade of Ca–Mg smectite. The dominant gangue mineral is calcite with accessory amounts of kaolinite, quartz, feldspar and dolomite. Characterization of these samples indicated that the clay response for Na-exchange was poor while their hydration, plastic and rheological properties were inferior to those of commercial bentonites. The samples were processed by crushing, attrition scrubbing followed by hydrocycloning to give pre-concentrates which were leached with diluted HCl. Application of such simple flowsheet effectively removed the majority of the associated calcite, dolomite, feldspar and quartz. These concentrates were further refined by a series of acid and alkaline treatments prior to their evaluation as industrial bentonites. The mineralogy, chemical analysis and physical properties of final concentrates and their activated products successfully match the required specifications for many industrial processes. The bentonite concentrates after alkaline activation are suitable for drilling muds while the products of acid activation can be used as bleaching clay. Cost–benefit analysis of the suggested flowsheet, of beneficiation and activation, proved the economic viability of such processes. Utilization of these clays, after their upgrading and activation, can represent a value-added to the Egyptian economy by preventing the importation of high quality activated clays.