The exposure to weathering conditions improve the plasticity of the clay considerably. The percolating rain water carrying the natural chemicals disintegrates the clay particles finer and finer and improves the plasticity of the clay. In some parts of the world in the Ball clay beneficiation plant, the clay yards are exposed to the weathering conditions for few years before usage. In some Ball clay beneficiation plants, people use to spray natural lignin derived from lignite on the clay beds stored in the storage yard.
During rainy season the spraying of lignin is done frequently with some fixed interval of time. The percolating rain water carries the lignin deep into the clay beds and coats each individual clay particle with the lignin.
to be contd…..
