Magnesium Citrate Powders from Waste Bitterns via Crystallization and Spray Drying

Abstract

The pilot-scale production of two magnesium citrate products, using a waste bittern discharged from a salt work as the raw material, was conducted in this study. Magnesium citrate nonahydrate and anhydrous magnesium citrate were prepared via crystallization and spray drying techniques, respectively, and characterized for purity, crystalline structure, particle shape, particle size distribution, and other properties. The material and energy costs were estimated based on technical data obtained from the pilot trials in conjunction with specific energy consumption of equivalent industrial-scale equipment. The costs were used to evaluate and compare the economic feasibility of both processes on a commercial scale. Although the material and energy costs at US$ 924 and US$ 33–81 per tonne, respectively, required to make magnesium citrate nonahydrate are lower than for anhydrous magnesium citrate at US$ 1256 and US$ 141 per tonne, respectively, the higher market price of anhydrous magnesium citrate at US$ 5000 per tonne compared to US$ 3000 per tonne for the hydrated form suggests production via spray drying is potentially the more profitable approach.