Separation of montmorillonite from sodium and calcium type bentonite

Usually in the quarried Bentonite in addition to Montmorillonite other clay minerals and non-clay minerals as impurities may be found. In some industries such as pharmaceutical industries, food production, nano-composites and catalysts, high purity Montmorillonite is required, therefore its separation from other minerals is essential. Montmorillonite separation may be carried out by its fine-grained crystals compared to impurities. In this study, first a sample of sodium Bentonite and calcium Bentonite from Kheirabad (Kerman) Bentonite mine were prepared and identified using the necessary measurements. Then, utilizing a new designed equipment Montmorillonite was separated from other minerals based on particle size. Separation of the sodium Montmorillonite sample was satisfactory but the calcium Montmorillonite sample separation was not efficient enough and even using calgon as dispersing agent has not improved its separation. Calcium ions in the calcium type sample were first exchanged with sodium using 2% (w/w) sodium carbonate solution. The results of separation show that the purity of sodium Montmorillonite and ion exchanged sample are 95% and 94% respectively, compared to the raw samples purity of about 65%.