CN112624163A

CN112624163A - Magnesium hydroxide production process based on loop reactor

Info

Publication number: CN112624163A
Application number: CN202011377940.4A
Authority: CN
Inventors: 张丽; 张莹; 冯颖; 董鑫; 张建伟
Original assignee: Shenyang University of Chemical Technology
Current assignee: Shenyang University of Chemical Technology
Priority date: 2020-12-01
Filing date: 2020-12-01
Publication date: 2021-04-09

Abstract

A production process of magnesium hydroxide based on a loop reactor relates to a production process of magnesium hydroxide, and adopts the loop reactor to continuously produce magnesium hydroxide. Taking magnesium salt and precipitator with certain concentration as raw materials, reacting the magnesium salt with the precipitator in a loop reactor to generate magnesium hydroxide precipitate, and aging, filtering and drying the obtained precipitate to finally obtain a magnesium hydroxide product. The residence time of the material in the reactor is extended by circulating the material in the loop reactor. The process can be operated continuously, and the magnesium hydroxide product has high purity, small particle size, good appearance, stable product quality and low process energy consumption.

Description

Magnesium hydroxide production process based on loop reactor

Technical Field

The invention relates to a magnesium hydroxide production process, in particular to a magnesium hydroxide production process based on a loop reactor.

Background

The magnesium hydroxide is an inorganic chemical raw material with wide application and has very wide market application prospect.

The current methods for preparing magnesium hydroxide mainly include chemical precipitation and natural brucite processing (physical pulverization). The two magnesium hydroxide products have different properties (physical properties and chemical component content), different use effects and very large market price difference. The magnesium hydroxide product produced by the chemical synthesis method has better adaptability in the aspects of purity and appearance and better market prospect.

The chemical precipitation method for preparing magnesium hydroxide is classified into a sodium hydroxide method, a calcium hydroxide method, an ammonia method and the like according to different precipitants. When the reaction is carried out in the traditional batch stirring reactor, the concentration of reactants in a reaction system is constantly changed, so that the magnesium hydroxide prepared in the batch reactor is mostly in an amorphous sheet shape, and the quality of the magnesium hydroxide product is poor; when the precipitation reaction is carried out in a continuous stirring groove type reactor, because the retention time of materials in the reactor is short, magnesium hydroxide crystals generated by the reaction cannot be in time to form good appearance, the product quality is not good, and the magnesium hydroxide is difficult to directly use in many occasions. Therefore, the method and the device for preparing the magnesium hydroxide have the advantages that a reaction device and a process capable of realizing continuous production are found, the retention time of materials in a reactor can be prolonged, so that magnesium hydroxide crystals generated by the reaction have enough time to grow into products with good shapes, the adaptability of the products on different occasions is improved, and the method and the device for preparing the magnesium hydroxide have important significance.

The circulation reaction technology prolongs the retention time of the materials in the process, and has obvious strengthening effect on the rapid reaction process controlled by external diffusion and crystallization. In addition, the loop reactor is adopted to replace the traditional stirring reactor, the circulation speed of materials in the equipment is improved through forced circulation, the process is not easy to block, and the production conditions are greatly improved.

Disclosure of Invention

The invention aims to provide a process for producing magnesium hydroxide based on a loop reactor. The continuous magnesium hydroxide production process can prolong the retention time of materials in the process, and has the advantages of short process flow, less equipment, and good and stable product quality.

The purpose of the invention is realized by the following technical scheme:

a magnesium hydroxide production process based on a loop reactor comprises the steps of solution preparation, reaction, aging, filtering and drying; the device comprises a loop reactor and an axial flow pump, and auxiliary equipment comprises a raw material storage tank, a pump, a flowmeter, a filter, an ageing tank and a dryer; the reaction temperature was 20 deg.C^oC~200^oC(ii) a The concentration of the raw material magnesium salt is 0.1-2.5 mol/L, and the molar ratio of the precipitator to the raw material magnesium salt is 1-5 times of the stoichiometric value; the aging temperature is 50-200 ℃, and the aging time is 0-10 hours; the precipitant is recycled or made into commodities for sale; the jacket is arranged outside the ring pipe, and steam, cooling water or heat conducting oil heat conducting media are introduced; the loop reactor is horizontally or vertically arranged.

The production process of the magnesium hydroxide based on the loop reactor is characterized in that the loop reactor is a single loop or double loop or multi-loop.

In the production process of the magnesium hydroxide based on the loop reactor, the raw material magnesium salt is magnesium chloride or magnesium nitrate or magnesium sulfate.

According to the production process of the magnesium hydroxide based on the loop reactor, the precipitator is lime or sodium hydroxide, or ammonia water, ammonia gas or alkaline substances thereof.

Compared with the traditional stirred tank magnesium hydroxide production process, the invention has the following advantages:

1. the total heat transfer coefficient is high;

2. the total heat transfer area is large;

3. the yield per unit volume is high;

4. the conversion per pass of the raw materials is high;

5. the flow rate of the medium in the reactor is high, the temperature concentration is uniform, and the product quality is stable; the wall surface medium has high speed and is not easy to stick to the wall.

6. The reaction conditions in the loop reactor are easier to control.

7. The loop reactor has simple structure, compact arrangement and small occupied area.

Drawings

FIG. 1 is a flow chart of the magnesium hydroxide production process of the present invention.

Detailed Description

The present invention will be described in detail with reference to the embodiments shown in the drawings.

The process comprises the steps of taking magnesium salt and a precipitator as raw materials, adopting a loop reactor, reacting the magnesium salt and the precipitator in the loop reactor at 50-200 ℃ to generate magnesium hydroxide precipitate, aging the obtained precipitate at 50-200 ℃ for 0-10 hours, filtering and drying to finally obtain a magnesium hydroxide product. The auxiliary equipment of the process comprises a raw material storage tank, a pump, a flowmeter, a filter, an ageing tank, a dryer and the like.

Example 1. magnesium chloride solution of 0.5mol/L and sodium hydroxide of 1mol/L are used as raw materials, equal volume is fed, a single-ring tube vertical reactor is used for reaction, the reaction temperature is 90 ℃, continuous production is carried out, precipitates after reaction are filtered, aged for 4 hours at 100 ℃, and then the magnesium hydroxide product is obtained after filtering, washing and drying.

Embodiment 2. magnesium sulfate solution of 1.5mol/L and ammonia water of mass concentration 26% -28% are used as raw materials, feeding is carried out according to molar equivalent ratio, a double-loop horizontal reactor is adopted for reaction, the reaction temperature is 95 ℃, continuous production is carried out, precipitates after reaction are filtered, aging is carried out for 2 hours at 140 ℃, and then the magnesium hydroxide product is obtained after filtering, washing and drying.

Example 3 magnesium hydroxide product is obtained by using 1mol/L magnesium nitrate solution and ammonia gas as raw materials, feeding the raw materials according to a molar equivalent ratio, reacting the raw materials in a multi-loop vertical reactor at the reaction temperature of 100 ℃, continuously producing the raw materials, filtering precipitates after the reaction, aging the precipitates for 2 hours at the temperature of 120 ℃, and filtering, washing and drying the precipitates.

Claims

1. A magnesium hydroxide production process based on a loop reactor is characterized in that the magnesium hydroxide production process comprises the steps of solution preparation, reaction, aging, filtering and drying; its device bagThe system comprises a loop reactor and an axial flow pump, and auxiliary equipment comprises a raw material storage tank, a pump, a flowmeter, a filter, an ageing tank and a dryer; the reaction temperature was 20 deg.C^oC~200^oC(ii) a The concentration of the raw material magnesium salt is 0.1-2.5 mol/L, and the molar ratio of the precipitator to the raw material magnesium salt is 1-5 times of the stoichiometric value; the aging temperature is 50-200 ℃, and the aging time is 0-10 hours; the precipitant is recycled or made into commodities for sale; the jacket is arranged outside the ring pipe, and steam, cooling water or heat conducting oil heat conducting media are introduced; the loop reactor is horizontally or vertically arranged.

2. The process for producing magnesium hydroxide based on a loop reactor according to claim 1, wherein the loop reactor is a single loop or double loop or multi loop.

3. The process for producing magnesium hydroxide based on a loop reactor according to claim 1, wherein the raw magnesium salt is magnesium chloride or magnesium nitrate or magnesium sulfate.

4. The process for producing magnesium hydroxide based on a loop reactor according to claim 1, wherein the precipitant is lime or sodium hydroxide, or ammonia water, or ammonia gas, or alkaline substance.