Recovery of potash by concentration and incineration of molasses spent wash was practiced abroad during the First World War.

Chakraborty and Bhaskar carried out Pilot study plant to recover potassium salts from spent wash of a molasses distillery in India.

In this process, the raw spent wash was neutralized with lime and evaporated about 75% solid in a forced circulation evaporator under vacuum by duplicating a multiple effect system.

Thick liquor was burnt in an incinerator where the spent wash coke which burnt itself under the grates of the incinerator and turned into ash, thereby supplying necessary heat required for the incoming thick liquor.

The process was continuous and self supporting. The ash was collected and leached with water by which all soluble K & Na salts dissolved in it leaving behind Fe, Ca and other impurities in the residue.

The solution was alkaline due to presence of potassium carbonate which was filtered and neutralized with sulphuric acid and further on concentrated in the evaporator.

Potassium salts in the form of chlorides and sulphateare crystallized from the concentrated solution.