WO2012065338A1 - Method for preparing anhydrous magnesium chloride by calcining and deaminating magnesium chloride hexammoniate - Google Patents

Abstract

Provided is a method for preparing anhydrous magnesium chloride by calcining and deaminating magnesium chloride hexammoniate, which comprises steps: (1) drying and purifying magnesium chloride hexammoniate at low temperature under the protection of ammonia; (2) calcining magnesium chloride hexammoniate at high temperature, wherein the magnesium chloride hexammoniate dried under the protection of ammonia is conveyed into high temperature calcining device through a closed conduit to calcine and deaminate, during the calcining and deaminating, the stream keeps moving state all the time, the initial temperature of calcination is 200 - 300 ℃, the temperature of calcination is rised step by step, and the final temperature is 380 - 450 ℃, the time of calcination is 2 - 4 hours, electric heating is used, or direct heating outside the device is used by using fuel gas; (3) cooling and packaging under closed environment to obtain anhydrous magnesium chloride. The advantages of the method are that the ammonia produced in subsequent calcination stage is used as the ammina used in drying stage, heat energy is utilized at the same time, efficient utilization of energy is realized, the technical process is simple, the operation is convenience, and the cost is low.

Description

 Description

 Method for preparing anhydrous magnesium chloride by calcination and deamination of hexaammonium chloride

[Technical Field]

 The invention relates to the technical field of anhydrous magnesium chloride, in particular to a method for preparing anhydrous magnesium chloride by calcination and deamination of hexaammonium chloride.

【Background technique】

 Anhydrous magnesium chloride is an important raw material for the preparation of magnesium metal by electrolysis, and is also an important raw material for the production of chemical petrochemical catalysts. The preparation process of anhydrous magnesium chloride is mainly prepared by adding chlorination of magnesite granules to carbon, and also obtained by heating dehydration process of hydrous magnesia. In addition, anhydrous magnesium chloride is a main process in the process of producing titanium sponge. by-product. Different regions determine their own process methods for producing anhydrous magnesium chloride according to their own resource conditions and process technology levels.

 Among the numerous routes for the preparation of anhydrous magnesium chloride, one of the technical routes is to prepare anhydrous chlorinated magnesium by preparing hexaammonium chloride intermediates and then deaminating the route. Regarding the preparation of anhydrous magnesium chloride from aqueous magnesium chloride, there are a large number of patents at home and abroad, involving the preparation of hexaammonium chloride using aqueous magnesium chloride to prepare anhydrous magnesium chloride, which is mainly explained in detail how to prepare qualified hexaammonium chloride for aqueous magnesium chloride. Such as

US5514359,ZL94194221.X,ZL01126495.0,ZL200510028286.5,CN10173469

3A and so on. From the published patents, the calcination of hexaammonium chloride is expressed as low temperature drying, high temperature calcination, and no control conditions are involved. Chinese patent ZL94194221.X gives operating parameters in its examples, and argon or nitrogen or carbon dioxide is introduced during drying and calcination. Gas. Since hexaammonium chloride can be decomposed and removed at a lower temperature to remove part of ammonia, forming pentaammonium chloride and tetraammonium chloride, it is easy to form a magnesium chloride complex with an organic solvent, such as MgCl ₂ · 5 H ₃ with methanol. CH3OH and MgCl ₂ · 4 H ₃ · 2CH ₃ OH, etc., organic matters in magnesium chloride complex are difficult to remove, easily cracked at high temperature to form carbon, water and other substances, magnesium chloride and water form magnesium oxide and basic magnesium chloride to form a product Purity and color. At the same time, the inert calcination process is added to the dry calcination process, and the ammonia must be separated before use.

[Summary of the Invention]

 The object of the present invention is to overcome the defects of low purity and high impurities of anhydrous magnesium chloride in the deamination process of hexaammine magnesium chloride in the prior art, and to provide a method for preparing anhydrous magnesium chloride by calcination and deamination of hexaammonium chloride.

 The idea of the present invention is: drying hexaammonium chloride under an ammonia protective atmosphere under low temperature conditions to remove organic impurities such as a reaction medium, and hexa-ammonium chloride does not decompose under low temperature conditions due to protection of an ammonia atmosphere, organic compounds It is impossible to form a magnesium chloride compound with magnesium chloride to be effectively removed. In actual production, a higher temperature ammonia gas generated by subsequent calcination is used as a shielding gas, and at the same time, heat energy required for drying is provided. The hexammine magnesium chloride after effective removal of the organic medium is subjected to high temperature removal of ammonia under micro-vacuum conditions to obtain anhydrous magnesium chloride, and the ammonia is compressed by a compression device for other industrial use and recycling itself. Ammonia protection drying-micro vacuum calcination process, the ammonia used in the drying stage can use ammonia produced by subsequent calcination, while using heat energy, simple drying energy consumption, no other waste is generated during the whole production process, and energy is realized. Effective use.

 The object of the present invention is achieved by the following technical solutions:

A method for preparing anhydrous magnesium chloride by calcining and deaminating hexaammonium chloride, the specific step is (1) Low-temperature drying and impurity removal of hexaammonium chloride under ammonia protection

 Whether it is hexaammonium chloride magnesium chloride prepared by reactive crystallization, or hexamine ammonia chloride produced by other processes such as silicon production, the hexaammonium chloride obtained by solid-liquid separation is inevitably entrained with mother liquor, and the mother liquor is mainly organic compound. In the sealed drying equipment, the material is always in motion and dried by ammonia protection for drying and decontamination. The drying temperature is 60~120 °C. The ammonia gas of 300~450 °C generated by the subsequent calcination section can also be used. It is fully contacted with the hexamine ammonia chloride to be dried and decontaminated, which fully utilizes the heat energy of the high-temperature ammonia gas generated by the calcination, reduces the heat demand of the drying process, and reduces the ammonia gas temperature for subsequent use. The heterogeneous process can be continuous production or batch process, and can be produced by a continuous process, and the residence time is 0.5~2 hours; the batch process can be used for 1 hour after the end of the feed;

 (2) High-temperature calcination treatment of hexaammonium chloride

 The ammonia-protected and dried hexaammonium chloride is transported into the high-temperature calcining equipment through a sealed pipeline for calcination and deamination, the high-temperature calcination equipment is a closed device, and the material is always in a moving state for calcination and deamination; the calcination start temperature is controlled at 200~300 °C, the calcination temperature increases with the calcination process, the final calcination temperature is 380~450 °C, the pressure in the high temperature calcination equipment is micro vacuum pressure; the calcination time is 2~4 hours, the heating is electrically heated, or Direct heating outside the equipment using gas;

 (3) Sealed and cooled package to obtain qualified anhydrous magnesium chloride product. The ammonia gas is directly compressed for use in the next stage process without separation and purification.

 Compared with the prior art, the positive effects of the present invention are:

(1) The invention adopts the high-temperature ammonia gas generated by the process itself as the shielding gas, and simultaneously provides the heat required for the drying process of the hexaammonium chloride to avoid decomposition of the hexaammonium chloride in the low-temperature drying stage. The complex vacancy prevents the organic matter from forming chloride with magnesium chloride in the drying stage, thereby avoiding decomposition of organic matter during high temperature calcination to form water, thereby forming basic magnesium chloride and magnesium oxide with magnesium chloride, affecting the purity and use value of anhydrous magnesium chloride;

 (2) The calcination process of the present invention does not add other gases, providing good conditions for subsequent use of ammonia gas, and avoiding subsequent gas separation;

 (3) The process of the invention is simple, convenient to operate, and low in cost.

[Description of the Drawings]

 Figure 1 is a process flow diagram of the present invention. 【detailed description】

 A specific embodiment of a method for producing anhydrous magnesium chloride by calcination and deamination of hexaammonium chloride according to the present invention is provided below. Example 1

A sample of hexaammonium chloride is prepared by the method of Chinese patent ZL01126495.0, wherein Chinese Patent No. 01126495.0 relates to a method for preparing anhydrous magnesium chloride, which is a patent previously filed by the applicant, and the main step is organic hydrated magnesium chloride. Preparation of solution; reaction crystallization coupling to prepare anhydrous magnesium chloride complex; solid-liquid separation and washing; crystallization mother liquor and precipitant recycling; heat treatment complex intermediate to prepare anhydrous magnesium chloride. The water content was analyzed to be 0.21%, and 200 g of hexaammonium chloride was taken. In a 500 ml round bottom flask, the flask was stirred with a glass impeller, and externally heated by an electric heating sleeve, and protected with ammonia gas, the flow rate of ammonia gas was 50 ml/ Min, under the condition of temperature control 100 °C, stir and dry for 1.5 hours, stop the ammonia protection, and heat up to 400 °C for six The ammonia magnesium chloride is calcined, and the ammonia gas released by the vacuum pump is maintained, and the micro-negative pressure is maintained, and calcination is carried out for 4 hours to obtain an anhydrous magnesium chloride product. The final product was analyzed by anhydrous magnesium chloride, wherein the main impurity water content was 0.2% and the magnesium oxide content was 0.18%. Example 2

 A sample of hexaammonium chloride was prepared by the method of Chinese patent ZL01126495.0, and the water content was 0.21%, and 200 g of hexaammonium chloride was taken. In a 500 ml round bottom flask, the flask was equipped with a glass impeller stirring, and the external was electrically heated. Warm heating, pass ammonia protection, ammonia flow rate is 50ml/min, stir and dry at 90 °C for 1 hour, stop ammonia protection, further heat up to 450 °C for hexaammonium chloride calcination, pass The vacuum pump draws the released ammonia gas, maintains a slight negative pressure, and calcines for 3 hours to obtain an anhydrous magnesium chloride product. The final product was analyzed to be anhydrous magnesium chloride, in which the main impurity water content was 0.18% and the magnesium oxide content was 0.19%. Example 3

A sample of hexaammonium chloride was prepared by the method of Chinese patent ZL01126495.0, and the water content was 0.21%, and 200 g of hexaammonium chloride was taken. In a 500 ml round bottom flask, the flask was equipped with a glass impeller stirring, and the external was electrically heated. Warm heating, pass ammonia protection, ammonia flow rate is 50ml/min, stir and dry at 90 °C for 1 hour, stop ammonia protection, further heat up to 450 °C for hexaammonium chloride calcination, pass The vacuum pump draws the released ammonia gas, maintains a slight negative pressure, and calcines for 3 hours to obtain an anhydrous magnesium chloride product. The final product was analyzed by anhydrous magnesium chloride, wherein the main impurity water content was 0.18% and the magnesium oxide content was 0.19%. Example 4 Using the method of Chinese patent ZL01126495.0, a sample of hexaammonium chloride was prepared and analyzed to have a water content of 0.21%. Two continuous fluidized beds were used for drying and degassing and calcination deamination, and hexaammonium chloride was introduced into the first fluidized bed. Drying and impurity removal, the ammonia gas from the second fluidized bed calcination is protected by ammonia gas, and the residence time is 1 hour under the temperature control temperature of 120 ° C. After drying and removing the hexammine magnesium chloride into the secondary calcination deamination flow The chemical bed, the calcination temperature is 380 ° C, the material residence time is 4 hours, the micro-negative pressure is maintained, and the ammonia gas released by the blower is transported into the dry decontamination fluidized bed. Anhydrous magnesium chloride product is obtained. The final product was analyzed by anhydrous magnesium chloride, in which the main impurity water content was 0.16% and the magnesium oxide content was 0.18%.

Claims

Claim A method for preparing anhydrous magnesium chloride by calcination and deamination of hexaammonium chloride, characterized in that the specific step is  (1) Low-temperature drying and impurity removal of hexaammonium chloride under ammonia protection  (2) High-temperature calcination treatment of hexaammonium chloride The ammonia-protected dried hexaammonium chloride is transported through a sealed pipeline into a high-temperature calcining apparatus for calcination and deamination, and the material is always in a state of motion for calcination and deamination; the calcination starting temperature is 200 to 300 ° C, and the calcination temperature is accompanied by the calcination process. The gradual increase is carried out, the final calcination temperature is 380~450 ° C _{; the} calcination time is 2 to 4 hours, the heating is heated by electric heating, or the gas is directly heated outside the apparatus;  (3) Sealed and cooled package to obtain anhydrous magnesium chloride product.  2. A method for preparing anhydrous magnesium chloride by calcination and deamination of hexaammonium chloride according to claim 1, wherein in the step (1), in the sealed drying device, the material is always in motion In the state, drying and drying is performed by drying under ammonia protection, and the drying temperature is 60 to 120 ° C; or the ammonia gas of 300 to 450 ° C produced by the subsequent calcination section is sufficiently contacted with the hexamine ammonia chloride to be dried to remove impurities.  3. The method for preparing anhydrous magnesium chloride by calcining and deaminating hexaammonium chloride according to claim 2, wherein the drying and removing process is continuous production or batch process production, using a continuous process to produce and staying. The time is 0.5 to 2 hours; the production by batch method is kept for 1 hour after the end of the feed. The method for preparing anhydrous magnesium chloride by calcination and deamination of hexaammonium chloride according to claim 1, wherein in the step (2), the high temperature calcining device is sealed. Equipment.  The method for preparing anhydrous magnesium chloride by calcination and deamination of hexaammonium chloride according to claim 1, wherein in the step (2), the pressure in the high temperature calcining apparatus is a micro vacuum pressure.