Home made potash

india, which entirely depends on import to meet its requirement of two million tonnes of the potassic fertiliser, has taken the first step towards manufacturing the vital plant nutrient. The Bhavnagar-based Central Salt and Marine Chemicals Research Institute (csmcri) has developed a technology to produce potash from seawater.

Though seawater is a potential source of potash, it is hardly exploited by the Indian salt industry, which produces 14.5 million tonnes of common salt. Reasons: firstly non-availability of indigenous technology; secondly, the salt industry, for which the potash production could be a viable side business, comprises mainly of widely dispersed small and medium scale units. For these enterprises, potash recovery from seawater is generally an unattractive proposition. Even the csmcri technology has not linked production of salt with potash. "This is because the volume of potash that can be produced as a by-product by the salt industry is limited and hence the profits may not match with the investment required,' says P K Ghosh, director of csmcri.

The institute, which sustained a laboratory-scale 100 kilogrammes per day production facility for two years, has recently handed over the technology to a shipping firm, which is diversifying into the production of fertilisers and other chemicals. The firm, with part funding from the Technology Information, Forecasting and Assessment Council of the Department of Science and Technology, is setting up a semi-commercial plant with an annual capacity of 2,500 tonnes at the Cori basin of the Great Rann of Kachchh. "The Rs four crore plant is expected to be up and running in 18-24 months,' says Ghosh.

Cori basin is a low-lying area. The entire region is swamped by seawater during tides. A concentrated solution, called sea bittern, mainly containing salts of potassium, sodium and magnesium is left behind as the water evaporates or penetrates into the soil. Sparsely populated, the area currently produces bromine, an industrially important chemical also extracted from sea bittern.

According to Ghosh, the technology, to be soon patented, entails the use of the effluent discharged from the bromine manufacturing plants as the major raw material. The fertiliser is expected to be of a much superior quality than the imported variety. World over, two types of potassic fertilisers are produced: muriate of potash, which is nothing but potassium chloride, and sulphate of potash. The latter is considered to be of superior quality, as it also supplies another important plant nutrient