Efficient utilization of lithium extraction by-products: purification technology and diversified application scenarios of magnesium hydroxide

The by-product magnesium hydroxide (Mg(OH)_2) produced during the lithium extraction process has high recovery value. Through purification and modification, it can be converted into high value-added products and used in many fields. The following is an overview of the purification and application of magnesium hydroxide, a by-product of lithium extraction:

Purification method 1. Solid-liquid separation and washing: A common purification method is to first wash the by-product magnesium hydroxide with water to remove impurity ions. Use water to wash once or multiple times at a temperature range of 10°C to 90°C, and then perform solid-liquid separation to obtain a relatively pure filter cake and filtrate.

2. Heat treatment: Heat treatment of the washed filter cake, such as calcination, can convert magnesium hydroxide into magnesium oxide (MgO), further improving the purity, and can be used for subsequent material synthesis or as a flame retardant, etc.

3. Surface modification: By coating or grafting organic matter on the surface, such as stearic acid, silane coupling agent, etc., the surface properties of magnesium hydroxide can be improved, and its dispersibility in organic media can be enhanced to prepare for specific applications.

4. Membrane separation technology: Using ceramic membrane or other high-precision filtration technology can effectively separate fine particles and impurities in the solution to obtain magnesium hydroxide with higher purity.

Application areas 1. Flame retardant: Purified magnesium hydroxide is an environmentally friendly inorganic flame retardant and is widely used in polymer materials such as plastics, rubber, and coatings. It can effectively slow down the combustion process and reduce toxic gas emissions.

2. Medical field: High-purity magnesium hydroxide can be used as antacids, laxatives, etc. because of its good biocompatibility and low toxicity.

3. Environmentally friendly materials: In wastewater treatment, it can be used as a neutralizer to remove acidic pollutants; it can also be used as an adsorbent to remove heavy metal ions.

4. Catalysts and catalyst carriers: Modified magnesium hydroxide can be used as a catalyst or carrier for certain chemical reactions to improve catalytic efficiency and selectivity.

5. Agricultural application: Improve soil pH and serve as magnesium fertilizer to supplement the magnesium required by plants.

6. New material development: As a functional filler, it is added to composite materials to improve the mechanical properties, thermal stability and flame retardancy of the materials.

Through the above-mentioned purification and modification technology, magnesium hydroxide produced as a by-product of lithium extraction can not only reduce environmental pollution, but also create additional economic benefits and realize the recycling of resources.