CN113620323A

CN113620323A - Preparation method of flame retardant magnesium hydroxide

Info

Publication number: CN113620323A
Application number: CN202110941370.5A
Authority: CN
Inventors: 奚志雄; 马萱航; 赵旭宁; 张娜
Original assignee: Shanghai Institute of Technology
Current assignee: Shanghai Institute of Technology
Priority date: 2021-08-17
Filing date: 2021-08-17
Publication date: 2021-11-09

Abstract

The invention discloses a preparation method of flame retardant magnesium hydroxide, which comprises the following steps: taking magnesium oxide waste, grinding, crushing and calcining, adding the residual solid into hydrochloric acid for acid dissolution, and filtering the solution to generate precipitate; adding H into the filtered solution under stirring₂O₂Changing the solution from green to yellow, precipitating, filtering, dropwise adding ammonia water into the filtered solution, adjusting pH value, and obtaining precipitate Mg (OH)₂And filtering and drying. The invention recycles silicon steel grade magnesium oxide, reduces the environmental pressure, and is a green and environment-friendly preparation scheme of flame retardant magnesium hydroxide.

Description

Preparation method of flame retardant magnesium hydroxide

Technical Field

The invention relates to a preparation method and application of magnesium hydroxide used for preparing a flame retardant from silicon steel grade magnesium oxide, and belongs to the technical field of recycling of silicon steel grade magnesium oxide.

Background

In recent years, many serious fires have been associated with polymer materials. High molecular materials are used in large quantities due to their characteristics of low cost, easy processing, good formability, low specific gravity, and the like. Therefore, research on flame retardancy of polymer materials has also been urgently conducted.

The quality of the oriented silicon steel is improved by the imported silicon steel grade magnesium oxide in a factory, and a large amount of waste is caused by the high value-added product while the product competitiveness is improved. Meanwhile, the market demands fire-retardant grade magnesium hydroxide and other magnesium salt products are vigorous, and the magnesium hydroxide is an environment-friendly fire retardant. Therefore, the technology for recycling the magnesium oxide waste not only accords with the current national industrial policies of energy conservation, emission reduction and sustainable development, but also has huge market potential of magnesium hydroxide and good economic benefit.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: how to utilize magnesium oxide waste to produce the magnesium hydroxide reduces the market price of the magnesium oxide.

In order to solve the technical problems, the invention provides the following technical scheme:

a preparation method of flame retardant magnesium hydroxide comprises the following steps:

step 1): taking magnesium oxide waste, grinding, crushing, putting into a crucible, calcining at 600 ℃, and reacting carbon in the magnesium oxide waste with oxygen in the air to generate CO₂Weighing the residual solid;

step 2): adding the rest solid into hydrochloric acid for acid dissolution, and adding Mg in the waste²⁺And Fe²⁺Then the reaction is carried out, the solution is filtered, and the generated precipitate is impurities;

step 3): adding H into the filtered solution under stirring₂O₂Changing the solution from green to yellow, i.e. Fe²⁺Conversion to Fe³⁺Precipitating, filtering, and filtering to obtain yellow solid Fe³⁺；

Step 4): dropwise adding ammonia water into the filtered solution, adjusting the pH value, and obtaining a precipitate Mg (OH)₂And filtering and drying.

Preferably, the calcination time in step 1) is 6h, and then carbon and oxygen completely react, and ferrous ions are partially oxidized into ferric ions, so as to facilitate later removal.

Preferably, the molar ratio of the magnesium oxide to the hydrochloric acid in the residual solid in the step 2) is 1:2-2.25, and the acid dissolution mode is stirring in a water bath at 60 ℃ for 5 hours.

Preferably, the impurities in step 2) comprise SiO₂And unreacted C.

Preferably, H is added in the step 3)₂O₂The pH of the solution was then 8.5.

Preferably, PEG is added to the solution filtered in the step 4) in addition to ammonia water, so that Mg (OH) obtained by precipitation can be obtained₂The size is thinner.

The process route provided by the invention can ensure that 100% of resources of magnesium oxide waste for oriented silicon steel are recycled, the process route for preparing flame-retardant grade magnesium hydroxide from the magnesium oxide waste is obtained, and the key technology and process for preparing the flame-retardant grade magnesium hydroxide from the magnesium oxide waste are mastered.

The invention also provides application of the flame retardant magnesium hydroxide prepared by the preparation method of the flame retardant magnesium hydroxide in ultrahigh engineering plastic composite materials.

Preferably, the flame retardant magnesium hydroxide and the ultra-high molecular weight polyethylene are prepared into the filter through a sintering process. The filter can resist the temperature of 80-160 ℃.

Compared with the prior art, the invention has the beneficial effects that:

1. large-area waste magnesium oxide does not need to be re-buried, so that the treatment cost of industrial waste is reduced;

2. the waste industrial waste residue is recycled, so that the environment is protected;

3. the market price of the magnesium oxide can be reduced by utilizing the magnesium hydroxide produced by the magnesium oxide waste.

Detailed Description

In order to make the invention more comprehensible, preferred embodiments are described in detail below.

Examples

1) and (3) calcining to remove carbon: calcining magnesium oxide waste gas in a muffle furnace at 600 ℃ for 2h to remove impurities such as black carbon, and reacting carbon with oxygen in air to generate CO in the heating process₂Meanwhile, slurry components organic matters in the waste also undergo the reaction; the metal oxides in the waste are further oxidized to higher oxides, such as oxygenThe ferrous oxide is oxidized to ferric oxide. The process can achieve the carbon removal effect, activate the waste and facilitate the subsequent acid dissolution experiment.

2) Acid dissolution to form crude magnesium salts: the magnesium oxide is dissolved by using hydrochloric acid with the concentration of 6mol/L as a dissolving agent under the condition of stirring at 60 ℃, and finally, crude magnesium salt containing more impurities, particularly high iron content is generated, and the dissolving time is controlled to be 1 h.

3) Purification of crude magnesium salts high purity magnesium salts: compressed air and ammonia water are introduced into the solution to oxidize part of ferrous ions in the solution into ferric ions, which is beneficial to Fe (OH)₃Is Fe with a pH of 9³⁺Complete sedimentation, and Mg (OH)₂No sedimentation occurred, and the reaction time in this case was preferably controlled to 45 min.

4)Mg(OH)₂Generation of (1): to promote flaky Mg (OH)₂Adding a surfactant and ethanol into the solution, controlling the concentration of ammonia water to be 1 wt% ammonia water and 5 wt% ethanol solution, allowing the generated magnesium hydroxide to flow out from the bottom of a sedimentation tank, and allowing the supernatant of the sedimentation tank to be used as a fertilizer material.

Claims

1. The preparation method of the flame retardant magnesium hydroxide is characterized by comprising the following steps:

step 1): taking magnesium oxide waste, grinding, crushing, putting into a crucible, calcining at 600 ℃, and reacting carbon in the magnesium oxide waste with oxygen in the air to generate CO²Weighing the residual solid;

Step 4): dropwise adding the filtered solutionAdding ammonia water, adjusting pH value, and obtaining Mg (OH) as precipitate₂And filtering and drying.

2. The method for preparing magnesium hydroxide as a flame retardant of claim 1, wherein the calcination time in the step 1) is 2 to 6 hours.

3. The method for preparing magnesium hydroxide as a flame retardant according to claim 1, wherein the molar ratio of magnesium oxide to hydrochloric acid in the remaining solid in the step 2) is 1:2-2.25, and the acid-soluble form is stirring in a water bath at 60 ℃ for 5 hours.

4. The method for preparing magnesium hydroxide as a flame retardant according to claim 1, wherein the impurities in the step 2) comprise SiO₂And unreacted C.

5. The method for preparing magnesium hydroxide as a flame retardant according to claim 1, wherein H is added in the step 3)₂O₂The pH of the solution is then 8-9.

6. The method for preparing magnesium hydroxide as a flame retardant of claim 1, wherein PEG is added to the solution filtered in the step 4) in addition to ammonia water.

7. The use of the flame retardant magnesium hydroxide prepared by the method of any one of claims 1 to 6 in ultra-high engineering plastic composites.

8. The use of claim 7, wherein the flame retardant magnesium hydroxide is made into a filter with ultra high molecular weight polyethylene by a sintering process.