The Study Of New Technology On Preparation Of Flame Retardant Type Magnesium Hydroxide By Brine

There is a large number of saline lake in China, there are rich brine resources in salt lakes, brine contains more than 60 kinds of components, magnesium is an important part of the brine, so there are rich magnesium resources, however, the development and utilization of magnesium resource is very little, both caused a waste of resources, but also caused harm on the environment. Make full use of magnesium resources in the saline lake and convert it to flame retardant magnesium hydroxide with high added value, which is of great value. But the flame retardant magnesium hydroxide prepared by precipitation method are difficult to filter, easy agglomeration, and poor compatibility with polymer materials, so hydrothermal method and magnesium hydroxide was modified under the conditions of high temperature and pressure was used frequently. Therefore, this topic put forward the preparation of magnesium hydroxide by precipitation transformation method in nonhigh temperature and nonhigh pressure conditions, in order to improve the filtering and dispersion of magnesium hydroxide and the modifier is added to the method. The contents of this topic are as follows:1. This paper have studied the theory of the process of preparing magnesium hydroxide by precipitation conversion method, analyzed the process of nucleation and growth and the causes and elimination of agglomeration, and the comparison of the effects on filter and dispersion of magnesium hydroxide by ordinary precipitation and precipitation transformation method.2. Preparation of magnesium hydroxide by precipitation conversion method, and investigated the effects of the concentration of magnesium chloride solution, stirring rate, reaction temperature, aging time and ultrasonic on the dispersion and surface polarity of the magnesium hydroxide. The results show that the magnesium hydroxide with good dispersion and lower surface polarity under the following conditions can be prepared:the concentration of magnesium chloride is 1.5mol/L, stirring speed is 400r/min, the reaction temperature is 90?, the aging time is 6h and ultrasound after adding sodium hydroxide.3. On the basis of precipitation transformation method, the effect of paraffin system and surfactant on dispersion and surface polarity of magnesium hydroxide was investigated. The conclusions can be drawn:in the liquid paraffin system, the paraffin wax can be recycled for many times, the magnesium hydroxide with a larger thickness and good dispersion was prepared when taking the modified temperature 90?, aging time 6h, liquid paraffin content of 35%. By adding different surfactants to the modification, the conclusion was that the stearic acid has better effect on the modification, and under the conditions of adding stearic acid the modification effect of magnesium hydroxide can be obviously improved by adding modification of stearic acid after adding NaOH and taking the modified method of surfactant mixture, and obtained the best condition when adding stearic acid as modifier: the mixing rate is 300r/min, the modified time is 4h, the adding amount of the modifier is 5%, the modified temperature is 80?.