Preparation method for synthesizing platy flame-retardant magnesium hydroxide by using light burned magnesia powder

Abstract

The invention relates to a preparation method for synthesizing platy flame-retardant magnesium hydroxide by using light burned magnesia powder. The method comprises the following steps of: preparing MgSO4 solution from light burned magnesia serving as a magnesium ion providing source by using sulfuric acid, filtering to remove impurities, controlling the ratio of [NH3.H2O] to [Mg<2+>] to be 1.5-1 and the ratio of [OH<->] to the [Mg<2+>] to be 2-1.5 by using ammonia water and NaOH solution as precipitating agents, and synthesizing the platy flame-retardant magnesium hydroxide by a two-step method, wherein the temperature of the ammonia water precipitating stage is between 50 and 60 DEG C, the temperature of the NaOH solution precipitating stage is between 120 and 160 DEG C, and the hydrothermal reaction time is 2 to 10 hours. The obtained platy magnesium hydroxide has the primary particle size of 0.5 to 1mu m and the magnesium hydroxide content of over 97 percent. The method is low in cost and high in added value; the prepared magnesium hydroxide has high purity, a stable structure and narrow particle size distribution; and a good way is provided for highly utilizing magnesium hydroxide and even magnesite resources. The magnesium hydroxide product prepared by the method can be used as a flame retardant in the industries of rubber, plastic, electric wires and cables, building materials and the like.

Description

technical field [0001] The present invention relates to a preparation method of flake flame-retardant grade magnesium hydroxide, in particular to a preparation method of flake flame-retardant grade magnesium hydroxide using light-burned magnesium oxide powder as magnesium source, ammonia water and sodium hydroxide as precipitating agent The method belongs to the technical field of inorganic chemical industry. Background technique [0002] my country is rich in magnesite resources, among which the proven reserves of magnesite resources in Liaoning Province have reached 3 billion tons. Magnesite is widely used as a raw material for refractory materials, and is used to prepare light-burned magnesia and heavy-burned magnesia respectively. Magnesium oxide and fused magnesium, and a small amount for the preparation of various magnesium salts. However, the utilization of magnesite for many years has the problem of taking the rich and giving up the poor, and a large amount of powder...

AI Technical Summary

Problems solved by technology

Most of the existing magnesium hydroxide products have wide particle size distribution, severe agglomeration, and low purity (magnesium hydroxide content is lower than 90-96%), which makes them cheap and limited in application; while the added value is high and the market demand The output of high-purity flaky magnesium hydroxide flame retardants, which is growing rapidly, is very small, resulting in a sharp contrast between the high-performance magnesium hydroxide flame retardants required by industries such as plastics, rubber, wires and cables, and the status quo of a large number of idle magnesium resources.

[0004] Since magnesium hydroxide is an inorganic compound with very strong surface polarity, its crystal surface has hydrophilicity, and the surface polarity of magnesium hydroxide synthesized by traditional technology under normal temperature conditions is relatively strong, and it is easy to agglomerate to form a particle size of 10- The 100μm secondary particle has a large surface area, and when it is directly added to the polymer, the dispersion and compatibility are poor, which affects the processing performance of the composite material