Study On The Gas-Liquid Reactive Crystallization Of Magnesium Hydroxidee

It has very important research value for using of magnesium resources efficiently, receiving high added-value magnesium products and high-purify magnesium compound in China, where there are abundant magnesium resources in brine resources, especially for the product of widely applicable magnesium hydroxide in many areas. It’s an important part of study magnesium products subjects that preparation of magnesium hydroxide by using of ammonia gas passing through a solution contain magnesian ion. Therefore, a study on the gas-liquid reactive crystallization of magnesium hydroxide was carried out systematically.The properties and application of magnesium hydroxide were provided in the summarizing literatures part, the process or production methods were also reviewed. Experiments were carried out by passing ammonia gas through the solution of magnesium chloride in a two-liter double glass jacketed tank reactor with two-tier stirring to mix the solution and the gaseous fluid. Based on the double-film theory, the effective gas-liquid contact areas were calculated at different stir speeds by measuring the ammonia gas chemical absorbent process with hydrochloric acid.The reactive crystallization kinetics of magnesium hydroxide was experimentally measured by particle population balance in bath crystallization. The model equations of the nucleation rate and the crystal growth rate of magnesium hydroxide were obtained through solving the batch conservation equations. The effects of the dynamics were analyzed.The reactive crystallization process of magnesium hydroxide was optimized experimentally. The effect of operational parameters, such as crystallization temperature, the flow rate of ammonia gas, stir speed, on the product yield coefficient was studied, and ammonia gas feed way of ammonia gas pipe undersurface and headspace of magnesium chloride solution on the size distribution was also studied.