As a flame retardant magnesium hydroxide(MDH) researcher, always I need to talk about this product for different persons, they may purchasing, boss, R&D, engineer, student, customers, or my colleagues. So I have an idea that I can write down it and help more people if it used for you, I will be much happy.

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Flame retardant magnesium hydroxide have different type and grade, according to the production method, there will have precipitated grade MDH, mineral method MDH, Hydrothermal method MDH; According to the surface coated modification classification, there will have the uncoated grade, stearic acid surface coated, silane coated, composite additives coated;  According to particle size classification, will have 325 mesh, 1250 mesh, 2500 mesh, 5000 mesh, 10000mesh; (Regarding ‘mesh’, you can check in google for an easy reference, believe you will have a good understand) According to magnesium hydroxide crystal structure classification, will have hexagonal structure MDH, fiber structure MDH, flake structure MDH, fiber and flake mixing MDH.

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1.According to the production method

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1.1 Preparation principle of synthetic magnesium hydroxide:

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Seawater extraction or salt lake water reaction with alkali;

Common preparation principles:

MgCl2+Ca(OH)2→CaCl2+Mg(OH)2↓;

MgCl2+2NH3·H2O→Mg(OH)2↓+2NH4Cl  (KMT XK series magnesium hydroxide adopts this preparation method);

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The synthetic magnesium hydroxide obtained by chemical reaction has the characteristics of high purity, high whiteness, and few impurities. Processing performance and flame retardancy are better than ore-method magnesium hydroxide.

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1.2 Hydrothermal method magnesium hydroxide

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1.3 Ore method magnesium hydroxide (also called brucite powder)

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The preparation principle of ore-method magnesium hydroxide:

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Brucite ore mining-ore selection-jaw crusher for preliminary crushing-Raymond mill grinding-packaging and delivery

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Brucite ore mining-ore selection-jaw crusher for preliminary crushing-Raymond mill grinding-vertical mill grinding-packaging and delivery

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Brucite ore mining-ore selection-jaw crusher for preliminary crushing-Raymond mill grinding-jet mill grinding-packaging and delivery

Brucite ore mining-ore selection-jaw crusher for preliminary crushing-hammer crushing-packaging and delivery

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Brucite ore mining-ore selection-jaw crusher for preliminary crushing-environmentally friendly calcination-packaging and delivery

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Brucite ore mining-ore selection-jaw crusher for preliminary crushing-Raymond mill grinding-powder modification-packaging and delivery

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2. According to the surface coated modification classification

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2.1 Uncoated grade: original powder, non-coated.

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2.2 Stearic acid surface coated: Use different types of stearic acid coated the powder surface, like using a high-speed mixer to finish.

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2.3 Silane surface coated: silane coating treatment on the surface of the powder (The effects of different silane additives will be quite different. I would like to share in detail in another article “Silane additives that can be used for surface modification of magnesium hydroxide”), use a high-speed mixer to complete the dry modification.

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2.4 Composite additives coated

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This one seems no need explanation, easy to understand.

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3. According to particle size classification

325 mesh: D50>10 micron, representative grade XK-325 series

1250 mesh: D50: 6-7 microns, representative grade XK-1250 series

2500 mesh: D50: 5-6 microns, representative grade XK-2500 series

5000 mesh: D50: 2.6-3 microns, representative grade XK-5000/99 series

10000 mesh: D50=1-2 microns, representative grade XK-10000/99 series, MAGNIFIN H5, MAGNIFIN H5IV,

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4. According to magnesium hydroxide crystal structure classification

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4.1 Hexagonal flake magnesium hydroxide

The crystal photo shows a standard hexagonal plate, and the best-performing hexagonal plate has a very regular hexagonal shape control and a very uniform size. The thickness of the hexagonal plate is very suitable. For example, the picture below is a standard hexagonal sheet crystal form:

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4.2 Fibrous magnesium hydroxide

The crystal structure is thick rod-like and fibrous; the mechanical properties are better in tensile strength and worse in elongation.

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4.3 Flaky non-hexagonal magnesium hydroxide

Flakes, different sizes, not strictly hexagonal in shape, larger specific surface area. The processing performance is worse than regular hexagonal tablets.

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4.4 Magnesium hydroxide with a mixed structure of flake and fiber

This one seems no need explanation, easy to understand.

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Wrote by Ara king, on 2020/10/27