Ammonia distillation tower and ammonia distillation process for high-purity magnesium hydroxide production

Abstract

The invention provides an ammonia distillation tower and an ammonia distillation process for producing high-purity magnesium hydroxide, and relates to the technical field of recycling ammonia raw materials, comprising: an ammonia distillation device and a reaction device; a liquid ammonium chloride solution to be decomposed is heated by a heating and decomposition section in the ammonia distillation device, free ammonia ions in the ammonium chloride solution are evaporated, ammonia gas and the liquid ammonium chloride solution to be reacted are formed, liquid in the heating and decomposition section enters the reaction device, reacts to generate a reaction mixture of calcium chloride and ammonia water, and enters the distillation section; the reaction mixture is heated by heating the distillation section, ammonia water in the reaction mixture is heated to form ammonia gas, and the ammonia gas is recovered, thereby alleviating the technical problem that in the prior art of manufacturing magnesium hydroxide by an ammonia precipitation method, ammonium chloride generated after the reaction cannot be recycled, resulting in waste of resources, and the ammonia gas is recycled, and the technical effect of effectively reducing the cost of manufacturing magnesium hydroxide is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of recycling ammonia raw materials, and in particular to an ammonia distillation tower and an ammonia distillation process for producing high-purity magnesium hydroxide. Background Art

[0002] Magnesium hydroxide is a medium-strong alkaline white amorphous powder, which is widely used in chemical, environmental protection, electronics, medicine and food industries. In particular, magnesium hydroxide can be used as an excellent flame retardant for plastics and rubber products, and as a flue gas desulfurizer and neutralizer for acidic wastewater in terms of environmental protection. Therefore, with the rapid economic development of today's society and the increasing emphasis on safety and environmental protection by the state, the demand for magnesium hydroxide continues to rise, and its value is self-evident. At present, the main methods for industrial production of magnesium hydroxide are divided into physical method (brucite grinding method) and chemical synthesis method.

[0003] (1) Physical method (brucite grinding method)

[0004] The main component of the natural mineral brucite is magnesium hydroxide, which is the mineral with the highest magnesium content found in nature so far. The brucite grinding method is to prepare magnesium hydroxide by crushing brucite into brucite powder (150μm), and then air-grinding the brucite powder into 1-26μm powder (magnesium hydroxide modified by surfactant). The manufacturing process of this magnesium hydroxide is simple and the price is relatively low, but it requires relatively pure natural brucite resources.

[0005] (2) Chemical synthesis

[0006] The chemical synthesis method is to use brine, brine ore, etc. containing magnesium chloride (MgCl2) to react with caustic substances in an aqueous medium to generate magnesium hydroxide slurry, which is filtered, washed, and dried to obtain magnesium hydroxide. The methods used more in the chemical synthesis method include calcium hydroxide precipitation method, sodium hydroxide precipitation method, and ammonia precipitation method. Among them, the ammonia precipitation method uses ammonia water as a precipitant and is an important method for producing magnesium hydroxide. The main chemical reaction formula: MgCl2+2NH3+2H2O=Mg(OH)2↓+2NH4ClThe ammonia precipitation method has a simple process and is easy to control. It can produce high-purity and fine magnesium hydroxide, and can also produce large-grained and easy-to-wash products. Although the utilization rate of ammonia in this method is low and the production cost is high, compared with the brine-sodium hydroxide precipitation method, its mother liquor is easy to recover and can be used for subsequent research and development.

[0007] However, in the ammonia precipitation method, the ammonium chloride produced after the reaction cannot be recycled, resulting in a waste of resources. Summary of the invention

[0008] The object of the present invention is to provide an ammonia still for producing high-purity magnesium hydroxide, so as to alleviate the technical problem that in the prior art of manufacturing magnesium hydroxide by an ammonia precipitation method, the ammonium chloride produced after the reaction cannot be recycled, resulting in a waste of resources.

[0009] The ammonia still for producing high-purity magnesium hydroxide provided by the present invention comprises: an ammonia still device and a reaction device;

[0010] The ammonia evaporation device comprises a heating decomposition section and a distillation section, wherein the heating decomposition section is arranged above the distillation section, and the liquid to be decomposed enters into the heating decomposition section, and the heating decomposition section is used to heat and decompose the liquid to be decomposed to form ammonia gas and a liquid to be reacted;

[0011] The heating and decomposition section is connected to the reaction device, the liquid to be reacted enters into the reaction device, and the reaction device is used to make the liquid to be reacted undergo a chemical reaction to generate a reaction mixture;

[0012] The reaction device is communicated with the distillation section, and the reaction mixture enters the distillation section. The distillation section is used to heat and decompose the reaction mixture to form ammonia gas and waste liquid.

[0013] Furthermore, a liquid outlet is provided at the bottom of the heating and decomposition section;

[0014] The liquid outlet is communicated with the reaction device, and the liquid to be reacted in the heating and decomposition section enters the reaction device through the liquid outlet.

[0015] Furthermore, a reactant addition port is provided on the side wall of the reaction device;

[0016] The reactant enters the reaction device through the reactant inlet, and the reactant undergoes a chemical reaction with the liquid to be reacted in the reaction device.

[0017] Furthermore, a reaction liquid inlet is provided on the distillation section;

[0018] The reaction device is connected to the reaction liquid inlet through a liquid transport pipe, and the reaction mixture in the reaction device enters the distillation section through the liquid transport pipe.

[0019] Furthermore, a hot steam port is provided on the distillation section;

[0020] The hot steam port is located below the reaction liquid inlet, and hot steam enters the distillation section through the hot steam port. The hot steam is used to heat and decompose the reaction mixture in the distillation section.

[0021] Furthermore, a first gas outlet is provided at the top of the distillation section;

[0022] The first gas outlet is communicated with the reaction device, and the ammonia gas and the hot steam in the distillation section enter the reaction device through the first gas outlet.

[0023] Furthermore, a second gas outlet is provided at the top of the reaction device;

[0024] The second gas outlet is communicated with the heating decomposition section, and the ammonia gas and the hot steam in the reaction device enter the heating decomposition section through the second gas outlet.

[0025] Furthermore, the ammonia evaporation device also includes an ammonia condenser;

[0026] A third gas outlet is provided at the top of the heating and decomposition section, and the third gas outlet is communicated with the ammonia condenser. The ammonia gas and the hot steam in the heating and decomposition section enter the ammonia condenser through the third gas outlet.

[0027] Furthermore, a waste liquid transport pipe is provided between the distillation section and the reaction device;

[0028] The waste liquid in the distillation section enters the reaction device through the waste liquid transport pipe.

[0029] The ammonia evaporation process provided by the present invention comprises the following steps: conveying the liquid to be decomposed to a heating decomposition section to evaporate free ammonia in the liquid to be decomposed to form ammonia gas and a liquid to be reacted; conveying the liquid to be reacted to a reaction device to chemically react the liquid to be reacted to form a reaction mixture; conveying the reaction mixture to a distillation section to decompose the reaction mixture into hot ammonia gas and waste liquid; and conveying the hot steam and hot ammonia gas in the distillation section to the heating decomposition section to heat the liquid to be decomposed.

[0030] The ammonia still for producing high-purity magnesium hydroxide provided by the present invention comprises: an ammonia still device and a reaction device; the ammonia still device comprises a heating decomposition section and a distillation section, the heating decomposition section is arranged above the distillation section, the liquid to be decomposed enters into the heating decomposition section, the heating decomposition section is used to heat and decompose the liquid to be decomposed to form ammonia gas and the liquid to be reacted; the heating decomposition section is connected with the reaction device, the liquid to be reacted enters into the reaction device, the reaction device is used to make the liquid to be reacted undergo a chemical reaction to generate a reaction mixture; the reaction device is connected with the distillation section, the reaction mixture enters into the distillation section, the distillation section is used to heat and decompose the reaction mixture to form ammonia gas and waste liquid. The liquid ammonium chloride solution to be decomposed is heated by the heating and decomposition section in the ammonia distillation device, so that free ammonia ions in the ammonium chloride solution are evaporated to form ammonia gas and the liquid ammonium chloride solution to be reacted. The liquid in the heating and decomposition section enters the reaction device, reacts to generate a reaction mixture of calcium chloride and ammonia water, and enters the distillation section. The distillation section heats the reaction mixture, so that the ammonia water in the reaction mixture is heated to form ammonia gas, and the ammonia gas is recovered, thereby alleviating the technical problem that the ammonium chloride produced after the reaction cannot be recycled in the prior art for manufacturing magnesium hydroxide, resulting in waste of resources, and realizing the technical effect of recycling ammonia gas and effectively reducing the cost of manufacturing magnesium hydroxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 A schematic diagram of the overall structure of an ammonia distillation tower for producing high-purity magnesium hydroxide provided in an embodiment of the present invention;

[0033] Figure 2 A schematic diagram of the structure of an ammonia evaporation device in an ammonia evaporation tower for producing high-purity magnesium hydroxide provided in an embodiment of the present invention;

[0034] Figure 3 A schematic diagram of the structure of a reaction device in an ammonia still for producing high-purity magnesium hydroxide provided in an embodiment of the present invention;

[0035] Figure 4 A schematic structural diagram of an ammonia evaporation tower with an ammonia condenser for producing high-purity magnesium hydroxide provided in an embodiment of the present invention.

[0036] Icons: 100-ammonia evaporation device; 110-heating decomposition section; 111-liquid outlet; 112-third gas outlet; 120-distillation section; 121-reaction liquid inlet; 122-hot steam outlet; 123-first gas outlet; 130-ammonia condenser; 140-mixed solution inlet; 200-reaction device; 210-reactant addition port; 220-second gas outlet; 230-waste liquid outlet; 300-waste liquid transport pipe. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0038] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0040] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0041] In addition, the terms "horizontal", "vertical", "overhanging" and the like do not mean that the components are required to be absolutely horizontal or overhanging, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0042] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0043] Some embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0044] Figure 1 The overall structural schematic diagram of the ammonia distillation tower for the production of high-purity magnesium hydroxide provided in this embodiment; Figure 2 A schematic diagram of the structure of an ammonia evaporation device in an ammonia evaporation tower for the production of high-purity magnesium hydroxide provided in this embodiment; Figure 3 A schematic diagram of the structure of a reaction device in an ammonia still for producing high-purity magnesium hydroxide provided in this embodiment; Figure 4 A schematic diagram of the structure of an ammonia evaporation tower with an ammonia condenser for the production of high-purity magnesium hydroxide provided in this embodiment.

[0045] like Figure 1-4 As shown, the ammonia evaporation tower for high-purity magnesium hydroxide production provided in this embodiment includes: an ammonia evaporation device 100 and a reaction device 200; the ammonia evaporation device 100 includes a heating decomposition section 110 and a distillation section 120, the heating decomposition section 110 is arranged above the distillation section 120, the liquid to be decomposed enters the heating decomposition section 110, and the heating decomposition section 110 is used to heat and decompose the liquid to be decomposed to form ammonia gas and a liquid to be reacted; the heating decomposition section 110 is connected to the reaction device 200, the liquid to be reacted enters the reaction device 200, and the reaction device 200 is used to cause the liquid to be reacted to undergo a chemical reaction to generate a reaction mixture; the reaction device 200 is connected to the distillation section 120, the reaction mixture enters the distillation section 120, and the distillation section 120 is used to heat and decompose the reaction mixture to form ammonia gas and waste liquid.

[0046] Specifically, in the process of manufacturing magnesium hydroxide by ammonia precipitation method, a solid-liquid mixture of magnesium hydroxide and ammonium chloride is produced, and the specific formula is: MgCl2+2NH3+2H2O=Mg(OH)2↓+2NH4Cl. After the solid-liquid mixture is separated into solid and liquid, the mixed solution is passed through the mixed solution inlet 140 on the top side wall of the ammonia evaporation device 100 and enters the heating and decomposition section 110 in the ammonia evaporation device 100. The hot gas in the heating and decomposition section 110 heats the mixed solution, and the free chlorine in the mixed solution forms ammonia gas and is separated from the liquid, and the ammonia gas is recovered.

[0047] After the ammonia gas is separated, the solution enters the reaction device 200. The reactants are placed in the reaction device 200. The reactants react with the ammonium chloride solution to generate ammonia water and waste liquid. The ammonia water and the waste liquid enter the distillation section 120 in the ammonia distillation device 100 together. A steam inlet is provided at the bottom of the distillation section 120. Hot steam enters the distillation section 120 from the bottom of the distillation section 120 to heat the ammonia water and the waste liquid, converting the ammonia water into ammonia gas, and recovering the ammonia gas.

[0048] In addition, the ammonia and hot steam in the distillation section 120 reflux into the reaction device 200, and enter the heating decomposition section 110 through the reaction device 200. The ammonia and hot steam in the heating decomposition section 110 are discharged from the top together to achieve the recovery of ammonia.

[0049] The reactant in the reaction device 200 is set to calcium hydroxide, the specific formula is: 2NH4Cl+Ca(OH)2=CaCl2+2H2O+2NH3↑, and the ammonium chloride solution is reacted to generate ammonia water to achieve the recovery of ammonia.

[0050] The reaction device 200 can be configured as a reaction tank, and the ammonia evaporation device 100 is specifically configured as an ammonia evaporation tower, which adopts a Ф3000 sieve plate ammonia evaporation tower and mainly consists of two major sections. The 1st to 22nd tower layers are the ammonia evaporation tower distillation section 120, and the 23rd to 37th tower layers are the ammonia evaporation tower heating decomposition section 110.

[0051] The ammonia evaporation tower for high-purity magnesium hydroxide production provided in this embodiment includes: an ammonia evaporation device 100 and a reaction device 200; the ammonia evaporation device 100 includes a heating decomposition section 110 and a distillation section 120, the heating decomposition section 110 is arranged above the distillation section 120, the liquid to be decomposed enters the heating decomposition section 110, and the heating decomposition section 110 is used to heat and decompose the liquid to be decomposed to form ammonia gas and a liquid to be reacted; the heating decomposition section 110 is connected to the reaction device 200, the liquid to be reacted enters the reaction device 200, and the reaction device 200 is used to cause the liquid to be reacted to undergo a chemical reaction to generate a reaction mixture; the reaction device 200 is connected to the distillation section 120, the reaction mixture enters the distillation section 120, and the distillation section 120 is used to heat and decompose the reaction mixture to form ammonia gas and waste liquid. The liquid ammonium chloride solution to be decomposed is heated by the heating and decomposition section 110 in the ammonia distillation device 100, so that free ammonia ions in the ammonium chloride solution are evaporated to form ammonia gas and the liquid ammonium chloride solution to be reacted. The liquid in the heating and decomposition section 110 enters the reaction device 200, reacts to generate a reaction mixture of calcium chloride and ammonia water, and enters the distillation section 120. The distillation section 120 heats the reaction mixture to heat the ammonia water in the reaction mixture to form ammonia gas, and the ammonia gas is recovered, thereby alleviating the technical problem that the ammonium chloride produced after the reaction cannot be recycled in the prior art for manufacturing magnesium hydroxide, resulting in a waste of resources, and realizing the technical effect of recycling ammonia gas and effectively reducing the cost of manufacturing magnesium hydroxide.

[0052] On the basis of the above embodiments, further, the bottom of the heating decomposition section 110 in the ammonia evaporation tower for the production of high-purity magnesium hydroxide provided in this embodiment is provided with a liquid outlet 111; the liquid outlet 111 is connected to the reaction device 200, and the liquid to be reacted in the heating decomposition section 110 enters the reaction device 200 through the liquid outlet 111.

[0053] Specifically, a liquid outlet 111 is provided at the bottom of the heating decomposition section 110, and the liquid to be decomposed generated by the reaction of magnesium chloride and ammonia water enters the heating decomposition section 110. The hot ammonia gas and hot steam in the heating decomposition section 110 evaporate the free ammonia in the liquid to be decomposed to form ammonia gas, and recover the ammonia in the liquid to be decomposed. After the recovery is completed, the liquid to be reacted is formed, and the liquid to be reacted enters the reaction device 200 through the liquid outlet 111.

[0054] Furthermore, a reactant inlet 210 is provided on the side wall of the reaction device 200 ; the reactant enters the reaction device 200 through the reactant inlet 210 , and the reactant undergoes a chemical reaction with the liquid to be reacted in the reaction device 200 .

[0055] Specifically, a reactant inlet 210 is provided on the side wall of the reaction device 200, and the reactant enters the reaction device 200 through the reactant inlet 210, and the reactant chemically reacts with the liquid to be reacted in the reaction device 200. The reactant is specifically calcium hydroxide, generating a reaction mixture of calcium chloride and ammonia water.

[0056] Furthermore, a reaction liquid inlet 121 is provided on the distillation section 120 ; the reaction device 200 is connected to the reaction liquid inlet 121 through a liquid transport pipe, and the reaction mixture in the reaction device 200 enters the distillation section 120 through the liquid transport pipe.

[0057] Furthermore, a hot steam port 122 is provided on the distillation section 120 ; the hot steam port 122 is located below the reaction liquid inlet 121 , and hot steam enters the distillation section 120 through the hot steam port 122 , and the hot steam is used to heat and decompose the reaction mixture in the distillation section 120 .

[0058] Specifically, a reaction liquid inlet 121 and a hot steam inlet 122 are provided on the distillation section 120. The reaction mixture of calcium chloride and ammonia water produced after the reaction in the reaction device 200 enters the distillation section 120 through the reaction liquid inlet 121, and external hot steam enters the distillation section 120 through the hot steam inlet 122 at the bottom of the distillation section 120. The hot steam is used to heat the reaction mixture, so that the ammonia water in the reaction mixture is converted into ammonia gas, thereby realizing the recovery of the ammonia gas.

[0059] The ammonia distillation tower for the production of high-purity magnesium hydroxide provided in this embodiment is provided with a liquid outlet 111 at the bottom of the heating decomposition section 110. The liquid to be decomposed in the heating decomposition section 110 evaporates the free ammonia to form a reaction solution which enters the reaction device 200 through the liquid outlet 111. The reaction device 200 reacts with the liquid to be reacted to generate a mixed liquid of calcium chloride and ammonia water, and the mixed liquid enters the distillation section 120 through the reaction liquid inlet 121. The ammonia water in the mixed liquid is converted into ammonia gas by the hot steam entering from the bottom of the distillation section 120.

[0060] On the basis of the above embodiments, further, the top of the distillation section 120 in the ammonia evaporation tower for the production of high-purity magnesium hydroxide provided in this embodiment is provided with a first gas outlet 123; the first gas outlet 123 is connected to the reaction device 200, and the ammonia and hot steam in the distillation section 120 enter the reaction device 200 through the first gas outlet 123.

[0061] Specifically, a first gas outlet 123 is provided at the top of the distillation section 120 , and the ammonia gas and hot steam in the distillation section 120 enter the reaction device 200 through the first gas outlet 123 .

[0062] Furthermore, a second gas outlet 220 is provided at the top of the reaction device 200 ; the second gas outlet 220 is connected to the heating decomposition section 110 , and the ammonia and hot steam in the reaction device 200 enter the heating decomposition section 110 through the second gas outlet 220 .

[0063] Specifically, a second gas outlet 220 is disposed on the top of the reaction device 200 , and the ammonia gas and hot steam in the reaction device 200 enter the heating and decomposition section 110 through the second gas outlet 220 .

[0064] Furthermore, the ammonia evaporation device 100 also includes an ammonia condenser 130; a third gas outlet 112 is provided at the top of the heating and decomposition section 110, and the third gas outlet 112 is connected to the ammonia condenser 130, and the ammonia gas and hot steam in the heating and decomposition section 110 enter the ammonia condenser 130 through the third gas outlet 112.

[0065] Specifically, a third gas outlet 112 is provided at the top of the heating decomposition section 110, and the third gas outlet 112 is connected to the ammonia condenser 130. The ammonia gas and hot steam in the heating decomposition section 110 enter the ammonia condenser 130 through the third gas outlet 112. The ammonia condenser 130 condenses the ammonia gas and the hot steam, condenses the hot steam into liquid, and discharges the ammonia gas for easy recycling, thereby realizing the separation of the hot steam and the ammonia gas.

[0066] The ammonia still provided in this embodiment for the production of high-purity magnesium hydroxide separates ammonia gas and hot steam by means of the ammonia condenser 130, so as to facilitate the recovery and utilization of ammonia gas.

[0067] On the basis of the above embodiments, further, a waste liquid transport pipe 300 is provided between the distillation section 120 and the reaction device 200 in the ammonia evaporation tower for high-purity magnesium hydroxide production provided in this embodiment; the waste liquid in the distillation section 120 enters the reaction device 200 through the waste liquid transport pipe 300.

[0068] Furthermore, a waste liquid outlet 230 is provided at the bottom of the reaction device 200 ; the waste liquid in the reaction device 200 is discharged through the waste liquid outlet 230 .

[0069] Specifically, a waste liquid transport pipe 300 is arranged between the distillation section 120 and the reaction device 200, and the residual calcium chloride waste liquid in the distillation section 120 enters the bottom of the reaction device 200 through the waste liquid transport pipe 300. Since the pressure at the bottom of the reaction device 200 is higher than the temperature and pressure of the distillation section 120, after the calcium chloride waste liquid enters the bottom of the reaction device 200, the calcium chloride waste liquid will flash steam for recovery, and the recovered steam will re-enter the distillation section 120. The recovered steam can also be used for other purposes, and the waste liquid is discharged through the waste liquid discharge port 230 arranged at the bottom of the reaction device 200.

[0070] In addition, a drain port is provided at the bottom of the distillation section 120 , and when the waste liquid transport pipe 300 is in a closed state, the waste liquid in the distillation section 120 can be discharged through the drain port.

[0071] The ammonia distillation tower for high-purity magnesium hydroxide production provided in this embodiment allows the waste liquid in the distillation section 120 to enter the reaction device 200 through the setting of the waste liquid transport pipe 300, and is discharged through the waste liquid discharge port 230 together with the residual waste liquid in the reaction device 200.

[0072] The ammonia evaporation process provided in this embodiment includes the following steps: conveying the liquid to be decomposed to the heating decomposition section 110 to evaporate the free ammonia in the liquid to be decomposed to form ammonia gas and a liquid to be reacted; conveying the liquid to be reacted to the reaction device 200 to chemically react the liquid to be reacted to form a reaction mixture; conveying the reaction mixture to the distillation section 120 to decompose the reaction mixture into hot ammonia gas and waste liquid; and conveying the hot steam and hot ammonia gas in the distillation section 120 to the heating decomposition section 110 to heat the liquid to be decomposed.

[0073] Specifically, after magnesium hydroxide is generated, solid-liquid separation is performed, and the solution generated when magnesium hydroxide is generated is separated to obtain a liquid to be decomposed, which contains an ammonium chloride solution and free ammonium ions. The liquid to be decomposed enters the heating and decomposition section 110, and the hot steam and hot ammonia gas in the heating and decomposition section 110 heat the liquid to be decomposed, evaporate the free ammonium ions in the liquid to be decomposed to form ammonia gas, and form a liquid to be reacted. The liquid to be reacted enters the reaction device 200, and the reaction device 200 stores reactants. The liquid to be reacted reacts chemically with the reactants to form a reaction mixture, wherein the reactant is calcium hydroxide, and the following reaction occurs: 2NH4Cl+Ca(OH)2=CaCl2+2H2O+2NH3↑. The reaction mixture includes calcium chloride and ammonia water, and enters the distillation section 120. The hot steam in the distillation section 120 heats the reaction mixture, and the ammonia water is heated to form hot ammonia gas. The hot steam and the hot ammonia gas re-enter the heating and decomposition section 110 to achieve ammonia recovery.

[0074] The ammonia evaporation process provided in this embodiment realizes the recycling of ammonia through the above steps, and the recycled ammonia can be further used to manufacture magnesium hydroxide, thus saving energy.

[0075] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An ammonia still for the production of high-purity magnesium hydroxide, characterized in that: include: An ammonia distillation device (100) and a reaction device (200); The ammonia evaporation device (100) comprises a heating decomposition section (110) and a distillation section (120), wherein the heating decomposition section (110) is arranged above the distillation section (120), and the liquid to be decomposed enters into the heating decomposition section (110), and the heating decomposition section (110) is used to heat and decompose the liquid to be decomposed to form ammonia gas and a liquid to be reacted; The heating and decomposition section (110) is fluidically connected to the reaction device (200), the liquid to be reacted enters into the reaction device (200), and the reaction device (200) is used to cause the liquid to be reacted to undergo a chemical reaction to generate a reaction mixture; The reaction device (200) is connected to the distillation section (120), the reaction mixture enters the distillation section (120), and the distillation section (120) is used to heat and decompose the reaction mixture to form ammonia gas and waste liquid; The ammonia gas and the hot steam in the distillation section (120) are refluxed into the reaction device (200), and enter the heating and decomposition section (110) through the reaction device (200), and the ammonia gas and the hot steam in the heating and decomposition section (110) are discharged from the top together; A waste liquid transport pipe (300) is provided between the distillation section (120) and the reaction device (200); The waste liquid in the distillation section (120) enters the reaction device (200) through the waste liquid transport pipe (300); The top of the distillation section (120) is provided with a first gas outlet (123); The first gas outlet (123) is in communication with the reaction device (200), and the ammonia gas and the hot steam in the distillation section (120) enter the reaction device (200) through the first gas outlet (123); The top of the reaction device (200) is provided with a second gas outlet (220); The second gas outlet (220) is connected to the heating decomposition section (110), and the ammonia gas and the hot steam in the reaction device (200) enter the heating decomposition section (110) through the second gas outlet (220).

2. The ammonia still for producing high-purity magnesium hydroxide according to claim 1, characterized in that: The bottom of the heating and decomposition section (110) is provided with a liquid outlet (111); The liquid outlet (111) is in communication with the reaction device (200), and the liquid to be reacted in the heating and decomposition section (110) enters the reaction device (200) through the liquid outlet (111).

3. The ammonia still for producing high-purity magnesium hydroxide according to claim 2, characterized in that: A reactant inlet (210) is provided on the side wall of the reaction device (200); The reactant enters the reaction device (200) through the reactant inlet (210), and the reactant undergoes a chemical reaction with the liquid to be reacted in the reaction device (200).

4. The ammonia still for producing high-purity magnesium hydroxide according to claim 3, characterized in that: The distillation section (120) is provided with a reaction liquid inlet (121); The reaction device (200) is connected to the reaction liquid inlet (121) via a liquid transport pipe, and the reaction mixture in the reaction device (200) enters the distillation section (120) via the liquid transport pipe.

5. The ammonia still for producing high-purity magnesium hydroxide according to claim 4, characterized in that: The distillation section (120) is provided with a hot steam port (122); The hot steam port (122) is located below the reaction liquid inlet (121), and hot steam enters the distillation section (120) through the hot steam port (122). The hot steam is used to heat and decompose the reaction mixture in the distillation section (120).

6. The ammonia still for producing high-purity magnesium hydroxide according to claim 5, characterized in that: The ammonia evaporation device (100) further includes an ammonia condenser (130); A third gas outlet (112) is provided at the top of the heating and decomposition section (110), and the third gas outlet (112) is connected to the ammonia condenser (130). The ammonia gas and the hot steam in the heating and decomposition section (110) enter the ammonia condenser (130) through the third gas outlet (112).

7. An ammonia distillation process based on an ammonia distillation tower for high-purity magnesium hydroxide production according to any one of claims 1 to 6, characterized in that: The following steps are involved: The liquid to be decomposed is transported to the heating decomposition section (110) to evaporate the free ammonia in the liquid to be decomposed to form ammonia gas and the liquid to be reacted; The liquid to be reacted is transported to the reaction device (200) so as to chemically react the liquid to be reacted to form a reaction mixture; The reaction mixture is conveyed to the distillation section (120) to decompose the reaction mixture into hot ammonia gas and waste liquid; The hot steam and hot ammonia gas in the distillation section (120) are transported to the heating decomposition section (110) to heat the liquid to be decomposed; The ammonia gas and hot steam in the distillation section (120) reflux into the reaction device (200), and enter the heating decomposition section (110) through the reaction device (200), and the ammonia gas and hot steam in the heating decomposition section (110) are discharged from the top together.

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