阅读说明：本技术 一种碳酸镁的生产工艺 (Production process of magnesium carbonate ) 是由 蔚永福 汤明松 张鹏 于 2021-02-26 设计创作，主要内容包括：本发明公开了一种碳酸镁的生产工艺,包括：将纯化后的氯化镁溶液加入反应器中,加入晶型控制剂,超声；得到混合物料；将乙醇雾化物通过载气通入反应器的混合物料中；将碳酸钠溶液注入注射泵中,然后以150～500mL/h的速度加入搅拌状态下的混合物料中,碳酸钠溶液加入完成后,继续搅拌,然后陈化,过滤,洗涤,得到碳酸镁；将碳酸镁加入到球磨罐中,同时加入不锈钢磨球,向球磨罐中通入液氮,将碳酸镁和不锈钢磨球全部浸没在液氮中,球磨,得到碳酸镁。通过本发明的碳酸镁的生产工艺,可以制备得到纯度高、含重金属离子极少、粒径分布窄的碳酸镁。(The invention discloses a production process of magnesium carbonate, which comprises the following steps: adding the purified magnesium chloride solution into a reactor, adding a crystal form control agent, and performing ultrasonic treatment; obtaining a mixed material; introducing the ethanol atomized substance into the mixed material in the reactor through carrier gas; injecting a sodium carbonate solution into an injection pump, adding the sodium carbonate solution into the mixed material under the stirring state at the speed of 150-500 mL/h, continuing stirring after the sodium carbonate solution is added, and then aging, filtering and washing to obtain magnesium carbonate; adding magnesium carbonate into a ball milling tank, simultaneously adding a stainless steel grinding ball, introducing liquid nitrogen into the ball milling tank, completely immersing the magnesium carbonate and the stainless steel grinding ball in the liquid nitrogen, and carrying out ball milling to obtain the magnesium carbonate. The magnesium carbonate with high purity, little heavy metal ion content and narrow particle size distribution can be prepared by the production process of the magnesium carbonate.)

1. The production process of magnesium carbonate is characterized by comprising the following steps of:

adding magnesium chloride into water, preparing a magnesium chloride solution, purifying the magnesium chloride solution, adding the purified magnesium chloride solution into a reactor, adding a crystal form control agent, and performing ultrasonic treatment; obtaining a mixed material;

step two, placing the ethanol aqueous solution in an ultrasonic atomizer for ultrasonic atomization to obtain ethanol atomized matter, and introducing the ethanol atomized matter into the mixed material in the reactor through carrier gas;

injecting a sodium carbonate solution into an injection pump, adding the sodium carbonate solution into the mixed material under the stirring state at the speed of 150-500 mL/h, continuing stirring for 30-60 min after the sodium carbonate solution is added, then aging for 5-8 h, filtering, and washing to obtain magnesium carbonate;

and step four, adding magnesium carbonate into a ball milling tank, simultaneously adding a stainless steel grinding ball, introducing liquid nitrogen into the ball milling tank, completely immersing the magnesium carbonate and the stainless steel grinding ball in the liquid nitrogen, and carrying out ball milling for 1.5-3 hours to obtain the magnesium carbonate.

2. The process for producing magnesium carbonate according to claim 1, wherein in the first step, the mass ratio of magnesium chloride to water is 1: 5-6; the method for purifying the magnesium chloride solution comprises the following steps: adjusting the pH value of the magnesium chloride solution to 3.5-4.5 by adopting hydrochloric acid with the concentration of 0.5-1.5 mol/L; then adding barium chloride and polyvinylpyrrolidone into the magnesium chloride solution, and carrying out pressure ultrasound for 30-60 min; filtering to obtain filtrate, namely the purified magnesium chloride solution; the molar concentration of the barium chloride is 0.8 percent greater than the molar concentration of sulfate ions in the magnesium chloride solution; the pressure of the pressurized ultrasonic wave is 2.5-3.5 MPa, and the frequency is 50-65 KHz; the mass ratio of the barium chloride to the polyvinylpyrrolidone is 1: 0.01 to 0.05.

3. The process for the production of magnesium carbonate according to claim 1, wherein the amount of the addition of the crystal form control agent is: adding 0.1-1.5 g of crystal form control agent into each liter of magnesium chloride solution; the preparation method of the crystal form control agent comprises the following steps: mixing 3-5 parts of inulin, 1-2 parts of thiourea, 0.2-0.5 part of alkyl glycoside, 1-2 parts of phytic acid, 0.5-0.8 part of 1-ethyl-3-methylimidazol lactic acid and 60-80 parts of water according to parts by weight, heating to 55-65 ℃, and stirring for 60-90 min at 500-800 r/min to obtain the crystal form control agent.

4. The process for the production of magnesium carbonate according to claim 1 wherein in step two, the volume ratio of ethanol to water in the aqueous ethanol solution is 2: 1; the power of the ultrasonic atomization is 1-10 kW, the frequency is 1.5-3.5 MHz, and the atomization rate is 50-150 mL/min; the carrier gas is inert gas, and the flow rate of the carrier gas is 1-20L/min; the mass ratio of the magnesium chloride to the ethanol aqueous solution is 1: 6-8;

5. the magnesium carbonate production process of claim 1, wherein in the third step, the stirring speed is 150-300 r/min; the mass ratio of sodium carbonate to water in the sodium carbonate solution is 1: 8-12; the diameter of an injection needle of the injection pump is 0.5-2.5 mm; the mass ratio of the magnesium chloride solution to the sodium carbonate solution is 1: 1.5-1.6.

6. The process for producing magnesium carbonate according to claim 1, wherein in the third step, batch ultrasound is applied during aging, and the batch ultrasound comprises: performing ultrasonic treatment for 10-15 min, and stopping ultrasonic treatment for 5min to circulate; the frequency of the ultrasonic wave is 55-65 KHz.

7. The magnesium carbonate production process of claim 1, wherein in the fourth step, stainless steel grinding balls are added into a ball-milling tank according to a ball-material mass ratio of 20-30: 1; the stainless steel grinding ball comprises large balls and small balls in a number ratio of 2: 1; the diameter of the big ball is 15-20 mm, and the diameter of the small ball is 3-5 mm; the ball milling adopts an upright ball mill with the rotating speed of 300 r/min.

8. The process for producing magnesium carbonate according to claim 1, wherein in the first step, the frequency of the ultrasonic wave is 35 to 45 KHz.

Technical Field

The invention belongs to the field of inorganic material preparation, and particularly relates to a production process of magnesium carbonate.

Background

The magnesium carbonate is white tasteless powder, has two common forms of amorphous powder and monoclinic crystal, has the characteristics of no combustion and light texture, and can be used for a heat-insulating and high-temperature-resistant fireproof heat-insulating material. Asbestos-grade magnesium carbonate is an excellent insulating material, is used in the departments of shipbuilding, boiler manufacturing and the like, and can also be used for manufacturing daily chemicals such as high-grade glass products, magnesium salts, pigments, paints, fireproof coatings, printing inks, ceramics, cosmetics, toothpaste and the like, medical products and the like. The food-grade magnesium carbonate can be used as flour additive, and can also be used as desiccant, color fixative, carrier, anticaking agent, etc.

At present, the prior art mainly adoptsThe preparation of magnesium carbonate from magnesium ore has become a bottleneck in enterprise development due to the problems of low ore grade, high cost, poor environment and the like, high impurity content of products and wide particle size distribution of the products. The light magnesium carbonate is prepared by a brine soda process and a brine ammonium carbonate process, the process requirements of brine purification and the like are high, more equipment is needed, and Na in the product⁺、Cl^-The content of the ammonium chloride is high, the mother liquor contains a small amount of ammonium chloride, the ammonium chloride needs to be recovered through the working procedures of evaporation, crystallization and the like, the energy consumption is high, the cost is high, and the environmental pollution is caused if the ammonium chloride is directly discharged. The light magnesium carbonate product produced in China has low grade, and the special and functional products are few, mainly occupy the market share of low end, and the high-end fine magnesium chemical products still need to be imported. The prior art discloses a method (CN1463923A) for preparing magnesium carbonate whiskers, which is to add a proper amount of additive into a magnesium bicarbonate solution and obtain magnesium carbonate whiskers with different specifications by controlling the crystallization conditions of magnesium carbonate. Although the product purity is high, the reaction time is too long, and the industrial production is not facilitated. In addition, in the prior art, a method (CN101613120A) for preparing spherical magnesium carbonate is provided, which takes soluble magnesium salt and soluble carbonate as raw materials and obtains high-purity spherical magnesium carbonate powder by controlling reaction conditions under the action of additives. The product obtained by the process has high purity and short reaction time, but the heavy metal ions contained in the product exceed the standard.

Disclosure of Invention

An object of the present invention is to solve at least the above problems and/or disadvantages and to provide at least the advantages described hereinafter.

To achieve these objects and other advantages in accordance with the present invention, there is provided a process for the production of magnesium carbonate, comprising the steps of:

adding magnesium chloride into water, preparing a magnesium chloride solution, purifying the magnesium chloride solution, adding the purified magnesium chloride solution into a reactor, adding a crystal form control agent, and performing ultrasonic treatment; obtaining a mixed material;

step two, placing the ethanol aqueous solution in an ultrasonic atomizer for ultrasonic atomization to obtain ethanol atomized matter, and introducing the ethanol atomized matter into the mixed material in the reactor through carrier gas;

injecting a sodium carbonate solution into an injection pump, adding the sodium carbonate solution into the mixed material under the stirring state at the speed of 150-500 mL/h, continuing stirring for 30-60 min after the sodium carbonate solution is added, then aging for 5-8 h, filtering, and washing to obtain magnesium carbonate;

and step four, adding magnesium carbonate into a ball milling tank, simultaneously adding a stainless steel grinding ball, introducing liquid nitrogen into the ball milling tank, completely immersing the magnesium carbonate and the stainless steel grinding ball in the liquid nitrogen, and carrying out ball milling for 1.5-3 hours to obtain the magnesium carbonate.

Preferably, in the first step, the mass ratio of magnesium chloride to water is 1: 5-6; the method for purifying the magnesium chloride solution comprises the following steps: adjusting the pH value of the magnesium chloride solution to 3.5-4.5 by adopting hydrochloric acid with the concentration of 0.5-1.5 mol/L; then adding barium chloride and polyvinylpyrrolidone into the magnesium chloride solution, and carrying out pressure ultrasound for 30-60 min; filtering to obtain filtrate, namely the purified magnesium chloride solution; the molar concentration of the barium chloride is 0.8 percent greater than the molar concentration of sulfate ions in the magnesium chloride solution; the pressure of the pressurized ultrasonic wave is 2.5-3.5 MPa, and the frequency is 50-65 KHz; the mass ratio of the barium chloride to the polyvinylpyrrolidone is 1: 0.01 to 0.05.

Preferably, the addition amount of the crystal form control agent is as follows: adding 0.1-1.5 g of crystal form control agent into each liter of magnesium chloride solution; the preparation method of the crystal form control agent comprises the following steps: mixing 3-5 parts of inulin, 1-2 parts of thiourea, 0.2-0.5 part of alkyl glycoside, 1-2 parts of phytic acid, 0.5-0.8 part of 1-ethyl-3-methylimidazol lactic acid and 60-80 parts of water according to parts by weight, heating to 55-65 ℃, and stirring for 60-90 min at 500-800 r/min to obtain the crystal form control agent.

Preferably, in the second step, the volume ratio of ethanol to water in the ethanol aqueous solution is 2: 1; the power of the ultrasonic atomization is 1-10 kW, the frequency is 1.5-3.5 MHz, and the atomization rate is 50-150 mL/min; the carrier gas is inert gas, and the flow rate of the carrier gas is 1-20L/min; the mass ratio of the magnesium chloride to the ethanol aqueous solution is 1: 6-8;

preferably, in the third step, the stirring speed is 150-300 r/min; the mass ratio of sodium carbonate to water in the sodium carbonate solution is 1: 8-12; the diameter of an injection needle of the injection pump is 0.5-2.5 mm; the mass ratio of the magnesium chloride solution to the sodium carbonate solution is 1: 1.5-1.6.

Preferably, in the third step, intermittent ultrasound is applied during the aging process, and the intermittent ultrasound process is as follows: performing ultrasonic treatment for 10-15 min, and stopping ultrasonic treatment for 5min to circulate; the frequency of the ultrasonic wave is 55-65 KHz.

Preferably, in the fourth step, the stainless steel grinding balls are added into a ball grinding tank according to the ball material mass ratio of 20-30: 1; the stainless steel grinding ball comprises large balls and small balls in a number ratio of 2: 1; the diameter of the big ball is 15-20 mm, and the diameter of the small ball is 3-5 mm; the ball milling adopts an upright ball mill with the rotating speed of 300 r/min.

Preferably, in the first step, the frequency of the ultrasound is 35 to 45 KHz.

The invention at least comprises the following beneficial effects: the magnesium carbonate with high purity, little heavy metal ion content and narrow particle size distribution can be prepared by the production process of the magnesium carbonate.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.

The specific implementation mode is as follows:

the present invention is further described in detail below with reference to examples so that those skilled in the art can practice the invention with reference to the description.

It will be understood that terms such as "having," "including," and "comprising," as used herein, do not preclude the presence or addition of one or more other elements or groups thereof.

Example 1:

a production process of magnesium carbonate comprises the following steps:

adding magnesium chloride into water, preparing a magnesium chloride solution, purifying the magnesium chloride solution, adding the purified magnesium chloride solution into a reactor, adding a crystal form control agent, and performing ultrasonic treatment; obtaining a mixed material; the mass ratio of the magnesium chloride to the water is 1: 5; the frequency of the ultrasonic wave is 35 KHz;

the method for purifying the magnesium chloride solution comprises the following steps: adjusting the pH value of the magnesium chloride solution to 4 by adopting hydrochloric acid with the concentration of 0.5 mol/L; then adding barium chloride and polyvinylpyrrolidone into the magnesium chloride solution, and carrying out pressure ultrasound for 60 min; filtering to obtain filtrate, namely the purified magnesium chloride solution; the molar concentration of the barium chloride is 0.8 percent greater than the molar concentration of sulfate ions in the magnesium chloride solution; the pressure of the pressurized ultrasound is 3MPa, and the frequency is 55 KHz; the mass ratio of the barium chloride to the polyvinylpyrrolidone is 1: 0.02;

the addition amount of the crystal form control agent is as follows: adding 0.5g of crystal form control agent into each liter of magnesium chloride solution; the preparation method of the crystal form control agent comprises the following steps: mixing 3kg of inulin, 1kg of thiourea, 0.2kg of alkyl glycoside, 1kg of phytic acid, 0.5kg of 1-ethyl-3-methylimidazol lactic acid and 60kg of water, heating to 55 ℃, and stirring for 90min at 800r/min to obtain a crystal form control agent;

step two, placing the ethanol aqueous solution in an ultrasonic atomizer for ultrasonic atomization to obtain ethanol atomized matter, and introducing the ethanol atomized matter into the mixed material in the reactor through carrier gas; the volume ratio of ethanol to water in the ethanol water solution is 2: 1; the power of the ultrasonic atomization is 5kW, the frequency is 2.5MHz, and the atomization rate is 100 mL/min; the carrier gas is inert gas, and the flow rate of the carrier gas is 5L/min; the mass ratio of the magnesium chloride to the ethanol aqueous solution is 1: 8;

step three, injecting a sodium carbonate solution into an injection pump, then adding the sodium carbonate solution into the mixed material in a stirring state (150r/min) at the speed of 300mL/h, continuing stirring at the speed of 150r/min for 60min after the sodium carbonate solution is added, then aging for 5h, filtering and washing to obtain magnesium carbonate; the mass ratio of sodium carbonate to water in the sodium carbonate solution is 1: 8; the diameter of the injection needle of the injection pump is 1 mm; the mass ratio of the magnesium chloride solution to the sodium carbonate solution is 1: 1.5; applying intermittent ultrasound in the aging process, wherein the intermittent ultrasound process comprises the following steps: performing ultrasonic treatment for 15min, stopping ultrasonic treatment for 5min, and circulating; the ultrasonic frequency is 65 KHz;

adding magnesium carbonate into a ball milling tank, simultaneously adding a stainless steel grinding ball, introducing liquid nitrogen into the ball milling tank, completely immersing the magnesium carbonate and the stainless steel grinding ball in the liquid nitrogen, and carrying out ball milling for 1.5 hours to obtain magnesium carbonate;

wherein, the stainless steel grinding balls are added into a ball grinding tank according to the ball material mass ratio of 20: 1; the stainless steel grinding ball comprises large balls and small balls in a number ratio of 2: 1; the diameter of the big ball is 15mm, and the diameter of the small ball is 3 mm; the ball milling adopts an upright ball mill with the rotating speed of 300 r/min;

through detection, the purity of the magnesium carbonate prepared by the embodiment is 99.8%, the content of heavy metal is less than 8ppm, the content of chloride ion is less than 0.02%, and the particle size range is 1.8-2.2 μm.

Example 2:

a production process of magnesium carbonate comprises the following steps:

adding magnesium chloride into water, preparing a magnesium chloride solution, purifying the magnesium chloride solution, adding the purified magnesium chloride solution into a reactor, adding a crystal form control agent, and performing ultrasonic treatment; obtaining a mixed material; the mass ratio of the magnesium chloride to the water is 1: 6; the frequency of the ultrasonic wave is 35 KHz;

the method for purifying the magnesium chloride solution comprises the following steps: adjusting the pH value of the magnesium chloride solution to 4 by adopting hydrochloric acid with the concentration of 1 mol/L; then adding barium chloride and polyvinylpyrrolidone into the magnesium chloride solution, and carrying out pressure ultrasound for 60 min; filtering to obtain filtrate, namely the purified magnesium chloride solution; the molar concentration of the barium chloride is 0.8 percent greater than the molar concentration of sulfate ions in the magnesium chloride solution; the pressure of the pressurized ultrasound is 3MPa, and the frequency is 55 KHz; the mass ratio of the barium chloride to the polyvinylpyrrolidone is 1: 0.03;

the addition amount of the crystal form control agent is as follows: adding 1g of crystal form control agent into each liter of magnesium chloride solution; the preparation method of the crystal form control agent comprises the following steps: mixing 5kg of inulin, 1.5kg of thiourea, 0.5kg of alkyl glycoside, 1kg of phytic acid, 0.5kg of 1-ethyl-3-methylimidazol lactic acid and 80kg of water, heating to 65 ℃, and stirring for 80min at the speed of 800r/min to obtain a crystal form control agent;

step two, placing the ethanol aqueous solution in an ultrasonic atomizer for ultrasonic atomization to obtain ethanol atomized matter, and introducing the ethanol atomized matter into the mixed material in the reactor through carrier gas; the volume ratio of ethanol to water in the ethanol water solution is 2: 1; the power of the ultrasonic atomization is 5kW, the frequency is 2.5MHz, and the atomization rate is 100 mL/min; the carrier gas is inert gas, and the flow rate of the carrier gas is 10L/min; the mass ratio of the magnesium chloride to the ethanol aqueous solution is 1: 6;

step three, injecting a sodium carbonate solution into an injection pump, then adding the sodium carbonate solution into the mixed material in a stirring state (150r/min) at the speed of 150mL/h, continuing stirring at the speed of 150r/min for 60min after the sodium carbonate solution is added, then aging for 8h, filtering and washing to obtain magnesium carbonate; the mass ratio of sodium carbonate to water in the sodium carbonate solution is 1: 6; the diameter of the injection needle of the injection pump is 1.2 mm; the mass ratio of the magnesium chloride solution to the sodium carbonate solution is 1: 1.5; applying intermittent ultrasound in the aging process, wherein the intermittent ultrasound process comprises the following steps: performing ultrasonic treatment for 15min, stopping ultrasonic treatment for 5min, and circulating; the ultrasonic frequency is 65 KHz;

adding magnesium carbonate into a ball milling tank, simultaneously adding a stainless steel grinding ball, introducing liquid nitrogen into the ball milling tank, completely immersing the magnesium carbonate and the stainless steel grinding ball in the liquid nitrogen, and carrying out ball milling for 2 hours to obtain magnesium carbonate;

wherein, stainless steel grinding balls are added into the ball-milling tank according to the ball material mass ratio of 25: 1; the stainless steel grinding ball comprises large balls and small balls in a number ratio of 2: 1; the diameter of the big ball is 20mm, and the diameter of the small ball is 5 mm; the ball milling adopts an upright ball mill with the rotating speed of 300 r/min;

through detection, the purity of the magnesium carbonate prepared by the embodiment is 99.7%, the content of heavy metal is less than 8ppm, the content of chloride ion is less than 0.02%, and the particle size range is 2-2.4 μm.

Example 3:

a production process of magnesium carbonate comprises the following steps:

adding magnesium chloride into water, preparing a magnesium chloride solution, purifying the magnesium chloride solution, adding the purified magnesium chloride solution into a reactor, adding a crystal form control agent, and performing ultrasonic treatment; obtaining a mixed material; the mass ratio of the magnesium chloride to the water is 1: 5; the frequency of the ultrasonic wave is 40 KHz;

the method for purifying the magnesium chloride solution comprises the following steps: adjusting the pH value of the magnesium chloride solution to 4 by adopting hydrochloric acid with the concentration of 1.5 mol/L; then adding barium chloride and polyvinylpyrrolidone into the magnesium chloride solution, and carrying out pressure ultrasound for 45 min; filtering to obtain filtrate, namely the purified magnesium chloride solution; the molar concentration of the barium chloride is 0.8 percent greater than the molar concentration of sulfate ions in the magnesium chloride solution; the pressure of the pressurized ultrasonic wave is 3.5MPa, and the frequency is 65 KHz; the mass ratio of the barium chloride to the polyvinylpyrrolidone is 1: 0.05;

the addition amount of the crystal form control agent is as follows: adding 1g of crystal form control agent into each liter of magnesium chloride solution; the preparation method of the crystal form control agent comprises the following steps: mixing inulin 4kg, thiourea 2kg, alkyl glycoside 0.3kg, phytic acid 1.5kg, 1-ethyl-3-methylimidazol lactic acid 0.5kg and water 80kg, heating to 65 ℃, and stirring at 800r/min for 80min to obtain a crystal form control agent;

step two, placing the ethanol aqueous solution in an ultrasonic atomizer for ultrasonic atomization to obtain ethanol atomized matter, and introducing the ethanol atomized matter into the mixed material in the reactor through carrier gas; the volume ratio of ethanol to water in the ethanol water solution is 2: 1; the power of the ultrasonic atomization is 10kW, the frequency is 3MHz, and the atomization rate is 120 mL/min; the carrier gas is inert gas, and the flow rate of the carrier gas is 10L/min; the mass ratio of the magnesium chloride to the ethanol aqueous solution is 1: 6;

step three, injecting a sodium carbonate solution into an injection pump, then adding the sodium carbonate solution into the mixed material in a stirring state (150r/min) at the speed of 300mL/h, continuing stirring at the speed of 150r/min for 60min after the sodium carbonate solution is added, then aging for 6h, filtering and washing to obtain magnesium carbonate; the mass ratio of sodium carbonate to water in the sodium carbonate solution is 1: 6; the diameter of the injection needle of the injection pump is 1.2 mm; the mass ratio of the magnesium chloride solution to the sodium carbonate solution is 1: 1.6; applying intermittent ultrasound in the aging process, wherein the intermittent ultrasound process comprises the following steps: performing ultrasonic treatment for 15min, stopping ultrasonic treatment for 5min, and circulating; the frequency of the ultrasonic wave is 60 KHz;

adding magnesium carbonate into a ball milling tank, simultaneously adding a stainless steel grinding ball, introducing liquid nitrogen into the ball milling tank, completely immersing the magnesium carbonate and the stainless steel grinding ball in the liquid nitrogen, and carrying out ball milling for 2 hours to obtain magnesium carbonate;

wherein, stainless steel grinding balls are added into the ball-milling tank according to the ball material mass ratio of 25: 1; the stainless steel grinding ball comprises large balls and small balls in a number ratio of 2: 1; the diameter of the big ball is 20mm, and the diameter of the small ball is 5 mm; the ball milling adopts an upright ball mill with the rotating speed of 300 r/min;

through detection, the purity of the magnesium carbonate prepared by the embodiment is 99.8%, the content of heavy metal is less than 8ppm, the content of chloride ion is less than 0.02%, and the particle size range is 1.8-2.1 μm.

Comparative example 1:

a production process of magnesium carbonate comprises the following steps:

adding magnesium chloride into water, preparing a magnesium chloride solution, adding the magnesium chloride solution into a reactor, adding a crystal form control agent, and performing ultrasonic treatment; obtaining a mixed material; the mass ratio of the magnesium chloride to the water is 1: 5; the frequency of the ultrasonic wave is 40 KHz;

the addition amount of the crystal form control agent is as follows: adding 1g of crystal form control agent into each liter of magnesium chloride solution; the preparation method of the crystal form control agent comprises the following steps: mixing inulin 4kg, thiourea 2kg, alkyl glycoside 0.3kg, phytic acid 1.5kg, 1-ethyl-3-methylimidazol lactic acid 0.5kg and water 80kg, heating to 65 ℃, and stirring at 800r/min for 80min to obtain a crystal form control agent;

step two, placing the ethanol aqueous solution in an ultrasonic atomizer for ultrasonic atomization to obtain ethanol atomized matter, and introducing the ethanol atomized matter into the mixed material in the reactor through carrier gas; the volume ratio of ethanol to water in the ethanol water solution is 2: 1; the power of the ultrasonic atomization is 10kW, the frequency is 3MHz, and the atomization rate is 120 mL/min; the carrier gas is inert gas, and the flow rate of the carrier gas is 10L/min; the mass ratio of the magnesium chloride to the ethanol aqueous solution is 1: 6;

step three, injecting a sodium carbonate solution into an injection pump, then adding the sodium carbonate solution into the mixed material in a stirring state (150r/min) at the speed of 300mL/h, continuing stirring at the speed of 150r/min for 60min after the sodium carbonate solution is added, then aging for 6h, filtering and washing to obtain magnesium carbonate; the mass ratio of sodium carbonate to water in the sodium carbonate solution is 1: 6; the diameter of the injection needle of the injection pump is 1.2 mm; the mass ratio of the magnesium chloride solution to the sodium carbonate solution is 1: 1.6; applying intermittent ultrasound in the aging process, wherein the intermittent ultrasound process comprises the following steps: performing ultrasonic treatment for 15min, stopping ultrasonic treatment for 5min, and circulating; the frequency of the ultrasonic wave is 60 KHz;

adding magnesium carbonate into a ball milling tank, simultaneously adding a stainless steel grinding ball, introducing liquid nitrogen into the ball milling tank, completely immersing the magnesium carbonate and the stainless steel grinding ball in the liquid nitrogen, and carrying out ball milling for 2 hours to obtain magnesium carbonate;

wherein, stainless steel grinding balls are added into the ball-milling tank according to the ball material mass ratio of 25: 1; the stainless steel grinding ball comprises large balls and small balls in a number ratio of 2: 1; the diameter of the big ball is 20mm, and the diameter of the small ball is 5 mm; the ball milling adopts an upright ball mill with the rotating speed of 300 r/min;

through detection, the purity of the magnesium carbonate prepared by the embodiment is 99.3%, the content of heavy metal is less than 10ppm, the content of chloride ion is less than 0.02%, and the particle size range is 2-2.5 μm.

Comparative example 2:

a production process of magnesium carbonate comprises the following steps:

adding magnesium chloride into water, preparing a magnesium chloride solution, purifying the magnesium chloride solution, adding the purified magnesium chloride solution into a reactor, and performing ultrasonic treatment; obtaining a mixed material; the mass ratio of the magnesium chloride to the water is 1: 5; the frequency of the ultrasonic wave is 40 KHz;

the method for purifying the magnesium chloride solution comprises the following steps: adjusting the pH value of the magnesium chloride solution to 4 by adopting hydrochloric acid with the concentration of 1.5 mol/L; then adding barium chloride and polyvinylpyrrolidone into the magnesium chloride solution, and carrying out pressure ultrasound for 45 min; filtering to obtain filtrate, namely the purified magnesium chloride solution; the molar concentration of the barium chloride is 0.8 percent greater than the molar concentration of sulfate ions in the magnesium chloride solution; the pressure of the pressurized ultrasonic wave is 3.5MPa, and the frequency is 65 KHz; the mass ratio of the barium chloride to the polyvinylpyrrolidone is 1: 0.05;

step two, placing the ethanol aqueous solution in an ultrasonic atomizer for ultrasonic atomization to obtain ethanol atomized matter, and introducing the ethanol atomized matter into the mixed material in the reactor through carrier gas; the volume ratio of ethanol to water in the ethanol water solution is 2: 1; the power of the ultrasonic atomization is 10kW, the frequency is 3MHz, and the atomization rate is 120 mL/min; the carrier gas is inert gas, and the flow rate of the carrier gas is 10L/min; the mass ratio of the magnesium chloride to the ethanol aqueous solution is 1: 6;

step three, injecting a sodium carbonate solution into an injection pump, then adding the sodium carbonate solution into the mixed material in a stirring state (150r/min) at the speed of 300mL/h, continuing stirring at the speed of 150r/min for 60min after the sodium carbonate solution is added, then aging for 6h, filtering and washing to obtain magnesium carbonate; the mass ratio of sodium carbonate to water in the sodium carbonate solution is 1: 6; the diameter of the injection needle of the injection pump is 1.2 mm; the mass ratio of the magnesium chloride solution to the sodium carbonate solution is 1: 1.6; applying intermittent ultrasound in the aging process, wherein the intermittent ultrasound process comprises the following steps: performing ultrasonic treatment for 15min, stopping ultrasonic treatment for 5min, and circulating; the frequency of the ultrasonic wave is 60 KHz;

adding magnesium carbonate into a ball milling tank, simultaneously adding a stainless steel grinding ball, introducing liquid nitrogen into the ball milling tank, completely immersing the magnesium carbonate and the stainless steel grinding ball in the liquid nitrogen, and carrying out ball milling for 2 hours to obtain magnesium carbonate;

wherein, stainless steel grinding balls are added into the ball-milling tank according to the ball material mass ratio of 25: 1; the stainless steel grinding ball comprises large balls and small balls in a number ratio of 2: 1; the diameter of the big ball is 20mm, and the diameter of the small ball is 5 mm; the ball milling adopts an upright ball mill with the rotating speed of 300 r/min;

through detection, the purity of the magnesium carbonate prepared by the embodiment is 99.7%, the content of heavy metal is less than 8ppm, the content of chloride ion is less than 0.02%, and the particle size range is 2.2-3 μm.

Comparative example 3:

a production process of magnesium carbonate comprises the following steps:

adding magnesium chloride into water, preparing a magnesium chloride solution, purifying the magnesium chloride solution, adding the purified magnesium chloride solution into a reactor, adding a crystal form control agent, and performing ultrasonic treatment; obtaining a mixed material; the mass ratio of the magnesium chloride to the water is 1: 5; the frequency of the ultrasonic wave is 40 KHz;

the method for purifying the magnesium chloride solution comprises the following steps: adjusting the pH value of the magnesium chloride solution to 4 by adopting hydrochloric acid with the concentration of 1.5 mol/L; then adding barium chloride and polyvinylpyrrolidone into the magnesium chloride solution, and carrying out pressure ultrasound for 45 min; filtering to obtain filtrate, namely the purified magnesium chloride solution; the molar concentration of the barium chloride is 0.8 percent greater than the molar concentration of sulfate ions in the magnesium chloride solution; the pressure of the pressurized ultrasonic wave is 3.5MPa, and the frequency is 65 KHz; the mass ratio of the barium chloride to the polyvinylpyrrolidone is 1: 0.05;

the addition amount of the crystal form control agent is as follows: adding 1g of crystal form control agent into each liter of magnesium chloride solution; the preparation method of the crystal form control agent comprises the following steps: mixing inulin 4kg, thiourea 2kg, alkyl glycoside 0.3kg, phytic acid 1.5kg, 1-ethyl-3-methylimidazol lactic acid 0.5kg and water 80kg, heating to 65 ℃, and stirring at 800r/min for 80min to obtain a crystal form control agent;

step two, placing the ethanol aqueous solution in an ultrasonic atomizer for ultrasonic atomization to obtain ethanol atomized matter, and introducing the ethanol atomized matter into the mixed material in the reactor through carrier gas; the volume ratio of ethanol to water in the ethanol water solution is 2: 1; the power of the ultrasonic atomization is 10kW, the frequency is 3MHz, and the atomization rate is 120 mL/min; the carrier gas is inert gas, and the flow rate of the carrier gas is 10L/min; the mass ratio of the magnesium chloride to the ethanol aqueous solution is 1: 6;

step three, injecting a sodium carbonate solution into an injection pump, then adding the sodium carbonate solution into the mixed material in a stirring state (150r/min) at the speed of 300mL/h, continuing stirring at the speed of 150r/min for 60min after the sodium carbonate solution is added, then aging for 6h, filtering and washing to obtain magnesium carbonate; the mass ratio of sodium carbonate to water in the sodium carbonate solution is 1: 6; the diameter of the injection needle of the injection pump is 1.2 mm; the mass ratio of the magnesium chloride solution to the sodium carbonate solution is 1: 1.6; applying intermittent ultrasound in the aging process, wherein the intermittent ultrasound process comprises the following steps: performing ultrasonic treatment for 15min, stopping ultrasonic treatment for 5min, and circulating; the frequency of the ultrasonic wave is 60 KHz;

through detection, the purity of the magnesium carbonate prepared by the embodiment is 99.8%, the content of heavy metal is less than 8ppm, the content of chloride ion is less than 0.02%, and the particle size range is 3.5-4.5 μm.

While embodiments of the invention have been described above, it is not limited to the applications set forth in the description and the embodiments, which are fully applicable to various fields of endeavor for which the invention may be embodied with additional modifications as would be readily apparent to those skilled in the art, and the invention is therefore not limited to the details given herein and to the examples shown and described without departing from the generic concept as defined by the claims and their equivalents.