Preparation Of Crystalline Magnesium Hydroxide And Magnesium Salt Whisker

There are abundant resources of magnesium in our country, and both magnesium itself and its compounds have important uses. With a view to the special rich brine and natural magnesium mineral resources in our province, we focus our attention on the syntheses of magnesium hydroxide crystal and magnesium salt whisker, which have important value and applications.The paper include the following aspects:1. On the background of the preparation and application of the magnesium hydroxide flame ratardants, we synthesized magnesium hydroxide flame ratardants products using MgCl₂·6H₂O and NaOH from distilled bittern. Due to the different syntheses conditions, the products have different size of 200 ～ 500 nm or 1 ～ 2 μm. We found that the granularity, size and shape of the products were affected by the concentration of the reactants, the temperature and the time of the hydrothermal reaction. Furthermore, the ratio of Mg/OH was the most important factor. Under 160-180℃, with 6-8 h reaction time, when the concentration of the magnesium is 4mol/ml, we can obtain favorable magnesium hydroxide crystal, which is suitable for the flame ratardants. Pilot study indicated that the products had good performance used as EVA flame ratardants.The growth mechanism of the products was also discussed in the paper.2. Considering the cheapness of the preparation of magnesium products from natural mineral, we studied the preparation of magnesium hydroxide flame ratardants from the magnesite. Under alkaline conditions, with the MgO hydration, we obtained magnesium hydroxide nanocrystals with good crystallization. The size of the particles was about 200 nm in the testing. The whiteness of the products was lower than those prepared from MgCl₂. And the purity was also lower than the aforementioned products due to the small size of the particles. But the cost was much less, so they have broad marlet prospects.