TABLE OF CONTENTS Frothers are heteropolar surface-active compounds containing a polar group (OH, COOH, C=O, OSO 2 and SO 2OH) and a hydrocarbon radical, capable of adsorbing in the water air interface. The frother molecules are arranged at the air water interface such that the hydrophilic or polar groups are oriented into the water phase, and the hydrophobic or nonpolar hydrocarbon chain in the air phase. In fact, the frother creates conditions for froth formation. The flotation froth is a three-phase system. The frother concentrates at the interface of water and air bubbles, forming an envelope around the bubbles, which prevents them from colliding or touching. Frothers also lower the surface tension of the water. The forces created around the air bubble in the presence of a frother prevent the bubbles from collapsing.
Many investigations have been carried out on froths and free liquid films [1 4] and extensive reviews are available on the theory of frothing and the stability of froths [5 8]. From the practical point of view, difficulties still remain in selecting an efficient frother for many operating plants. This is because the ionic composition of the pulp and the presence of various ultra-fine clay minerals have a dramatic effect on the frothing properties and froth stability in the flotation pulps.
Recent attempts to provide guidelines for frother selection [9] suggested that using technical concepts and extensive flotation cell experience can lead to the identification of frothers possessing a range of desirable performance characteristics. However, this...
