Preparation technology for magnesium sulfate heptahydrate

Abstract

The invention discloses a preparation process of magnesium sulfate heptahydrate, which comprises the following steps: S1100 step of removing impurities and extracting magnesium hydroxide material: using the magnesium hydroxide filter cake formed in the process of extracting lithium from salt lake brine as a raw material, the hydrogen The magnesium oxide filter cake is subjected to impurity removal treatment to extract the magnesium hydroxide material in the magnesium hydroxide filter cake, so that the mass fraction of Cl in the magnesium hydroxide material is below 0.01%; S1200 Magnesium sulfate synthesis steps: Add sulfuric acid solution to the magnesium hydroxide material, mix according to the ratio of the amount of magnesium hydroxide and sulfuric acid in the range of 1:1.7 to 1:1.8, a neutralization reaction occurs to form a magnesium sulfate solution; S1300 crystallization, separation, and drying steps : the magnesium sulfate solution forms a crystal primary body of magnesium sulfate heptahydrate through a crystallization process, and the magnesium sulfate heptahydrate crystal primary body undergoes a separation process and a drying process to obtain magnesium sulfate heptahydrate crystals.

Description

technical field [0001] The invention relates to the technical field of magnesium sulfate preparation, in particular to a preparation process for producing magnesium sulfate heptahydrate crystals from waste magnesium hydroxide filter cake produced in the process of extracting lithium from salt lake brine. Background technique [0002] Magnesium sulfate heptahydrate (molecular formula MgSO4 7H2O), also known as sulfur bitter, bitter salt, epsom salt, epsom salt, is white or colorless needle-like or oblique columnar crystals, odorless, cool and slightly bitter, molecular weight: 246.47, The specific gravity is 1.68, easily soluble in water, slightly soluble in ethanol and glycerin, and soluble in its own crystal water at 67.5°C. Thermal decomposition, 70, 80-85 ℃ is to lose four molecules of crystal water. At about 200°C, it loses all crystal water and becomes anhydrous. It is easily weathered into powder in the air (dry), and gradually loses crystal water when heated to beco...

AI Technical Summary

Problems solved by technology

Although magnesium hydroxide material is currently recognized as an excellent flame retardant material with triple functions of flame retardancy, smoke suppression and filling in the rubber and plastic industry, it is widely used in rubber, chemicals, building materials, plastics and electronics, unsaturated polyester and paints. , coatings and other polymer materials, but the magnesium hydroxide filter cake obtained in the process of extracting lithium from salt lake brine is usually used as a filler and flame retardant because of its low content, crystal morphology and dispersibility. It will be directly discarded, and the burial of a large amount of waste will not only increase the landfill cost but also cause a waste of resources

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