Magnesium sulphate is a typical hygroscopic inorganic salt, and the difficulty sits at the material end rather than the heat end. It absorbs moisture quickly and takes it back just as quickly; the mother liquor carries seven waters of crystallisation, and dehydration has to happen in one step, because stopping halfway is what makes it cake. Our standard configuration is a flash airflow line: the material reaches the target moisture within seconds, the residence time is too short for any window to re-absorb moisture, and the discharge end goes straight into sealed packaging, which is the single most important step in the process.
Magnesium sulphate is a typical hygroscopic inorganic salt, and the difficulty sits at the material end rather than the heat end. It absorbs moisture quickly and takes it back just as quickly; the mother liquor carries seven waters of crystallisation, and dehydration has to happen in one step, because stopping halfway is what makes it cake. Our standard configuration is a flash airflow line: the material reaches the target moisture within seconds, the residence time is too short for any window to re-absorb moisture, and the discharge end goes straight into sealed packaging, which is the single most important step in the process. The rotary drum is the alternative, used when throughput is larger or when a longer residence time is needed to convert the heptahydrate fully to the anhydrous form. Natural gas or direct-fired biomass both work, but biomass needs flame isolation and spark capture: magnesium sulphate itself is not combustible, whereas ash carried into the product is the real problem. Final moisture is usually set below 0.5 percent, and that figure has to be confirmed by trial run, because variation in the incoming moisture of a batch shows up directly in the finished product.