CN115991496B - Preparation method of hydrated magnesium ammonium sulfate - Google Patents

Abstract

The invention provides a preparation method of hydrated magnesium ammonium sulfate, which comprises the following steps: mixing serpentine raw material powder and acid salt solution, and carrying out a mixing reaction to obtain a first solid-liquid mixture; separating leaching liquid from the first solid-liquid mixture, and performing an aging reaction to obtain a second solid-liquid mixture; and separating a filter cake from the second solid-liquid mixture, washing and drying to obtain the hydrated magnesium ammonium sulfate. The invention has the advantages of easy realization of synthesis process technical conditions, simple synthesis method procedures, convenient operation, green and environment-friendly synthesis process, recycling of the generated filtrate and the like.

Description

A kind of preparation method of hydrated ammonium magnesium sulfate

Technical Field

The invention relates to the field of inorganic functional materials and mineral material preparation, and in particular to a method for preparing hydrated ammonium magnesium sulfate.

Background technique

Serpentine is a general term for a hydrous magnesium-rich silicate mineral, including antigorite, lizardite, chrysotile, etc. Serpentine can be used to produce building materials, refractory materials, chemicals, etc. Serpentine with fine crystals can be made into decorations or handicrafts. Serpentine tailings refer to the tailings produced during the mining of various types of serpentine. At present, the stockpile of serpentine tailings in my country is huge, especially chrysotile tailings, which are hazardous solid wastes and seriously endanger the ecological environment around the storage yard. In addition, a large amount of accumulated serpentine tailings is prone to cause geological disasters such as mudslides.

The main phases of serpentine and serpentine tailings are serpentine, magnetite, etc., which have a high MgO content and are suitable for use as raw materials for the preparation of hydrated ammonium magnesium sulfate/hydrated ammonium ferric sulfate. They have the advantages of solid waste utilization, turning waste into treasure, high product added value, and high ecological and environmental benefits.

At present, the production of ammonium magnesium sulfate hydrate mainly uses ammonium sulfate and magnesium sulfate as raw materials, and is produced by processes such as dissolution, impurity removal, recrystallization, high-temperature drying and dehydration under the action of auxiliary agents; the entire preparation process is long and the cost is high. No public reports have been found on the direct preparation of ammonium magnesium sulfate hydrate using solid waste as raw materials.

Summary of the invention

The object of the present invention is to solve at least one of the above-mentioned deficiencies in the prior art. For example, one of the objects of the present invention is to provide a method for preparing hydrated ammonium magnesium sulfate with mild reaction conditions, low energy consumption and environmental protection.

In order to achieve the above object, the present invention provides a method for preparing hydrated ammonium magnesium sulfate, which may include the following steps:

The serpentine raw material powder and the acid salt solution are mixed and mixed to obtain a first solid-liquid mixture; the leaching liquid is separated from the first solid-liquid mixture and subjected to an aging reaction to obtain a second solid-liquid mixture; the filter cake is separated from the second solid-liquid mixture, washed, and dried to obtain hydrated ammonium magnesium sulfate.

In an exemplary embodiment of the present invention, after separating the filter cake from the second solid-liquid mixture, there is filtrate, and the method may further include: using the filtrate to replace all or part of the acid salt solution and mixing with the serpentine raw material powder.

In an exemplary embodiment of the present invention, after separating the leachate from the first solid-liquid mixture, a filter cake is obtained, and the method may further include: washing and drying the filter cake to obtain a silicon source that can be used for synthesizing white carbon black or calcium silicate.

In an exemplary embodiment of the present invention, after the filtrate is returned to replace the acid salt solution for multiple times, if the concentration of Mg ²⁺ in the obtained leachate is lower than 0.03 g/100 mL, the filtrate reaches the standard of full circulation. The method may also include: adding ammonia water to the filtrate after full circulation to adjust the pH to neutral, and recovering ammonium sulfate by evaporation and crystallization.

In an exemplary embodiment of the present invention, the particle size of the serpentine raw material powder can be 80-200 mesh, and the serpentine raw material powder includes: serpentine raw material obtained by drying, crushing and ball milling, and the serpentine raw material includes one or more of natural serpentine minerals and tailings produced by mining serpentine minerals.

In an exemplary embodiment of the present invention, the acid salt solution may include one or more of an ammonium bisulfate solution and an ammonium sulfate solution.

In an exemplary embodiment of the present invention, the concentration of the acid salt solution may be 1-4 mol/L.

In an exemplary embodiment of the present invention, the liquid-solid ratio of the mixed reaction may be 5-20 mL/g, the reaction temperature may be 50-100° C., and the reaction time may be 60-240 min.

In an exemplary embodiment of the present invention, the aging reaction may be carried out at a temperature of 10-40° C. and for a time of 12-48 hours.

In an exemplary embodiment of the present invention, the crystalline form of the hydrated ammonium magnesium sulfate may be kainite hexahydrate.

Compared with the prior art, the beneficial effects of the present invention may include at least one of the following:

(1) The present invention uses natural serpentine minerals, including tailings produced by mining natural serpentine minerals, as raw materials to prepare hydrated ammonium magnesium sulfate with a wide range of uses; it has important ecological and sustainable development significance for the high-value utilization of natural mineral resources, the high-value utilization of industrial solid wastes and resource protection;

(2) The present invention realizes the preparation of hydrated ammonium magnesium sulfate under low temperature and normal pressure conditions; it is of great significance to reduce the production cost of hydrated ammonium magnesium sulfate;

(3) The present invention selects ammonium bisulfate and ammonium sulfate as auxiliary agents, which have low economic cost and less corrosion to equipment; the entire process realizes the recycling and recovery of auxiliary agents; and the entire process does not discharge three wastes; it is of great significance to the green and high-value utilization of natural mineral resources and solid wastes and the low-cost preparation of high-value-added chemical products.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an XRD diagram of hydrated ammonium magnesium sulfate prepared according to Example 1 of the present invention.

Detailed ways

Hereinafter, a method for preparing hydrated ammonium magnesium sulfate of the present invention will be described in detail in conjunction with exemplary embodiments. It should be noted that "first", "second", etc. are only for the convenience of description and distinction, and cannot be understood as indicating or implying relative importance.

Exemplary Embodiment 1

In this exemplary embodiment, a method for preparing hydrated ammonium magnesium sulfate is provided.

The method may include the following steps:

S10, mixing serpentine raw material powder and acid salt solution, performing a mixing reaction, and obtaining a first solid-liquid mixture, wherein the serpentine raw material comprises one or more of natural serpentine minerals and tailings produced by mining serpentine minerals.

Specifically, the serpentine raw material powder can be obtained by drying, crushing and ball milling the serpentine raw material, and the particle size of the serpentine raw material powder can be 80-200 meshes, such as 90, 100, 110, 150, 180, 190 meshes, etc. The particle size of the serpentine raw material powder takes into account the leaching of magnesium in the serpentine raw material. When the particle size of the raw material powder is less than 80 meshes, the leaching reaction efficiency will be low due to the large particle size. When the particle size of the raw material powder is greater than 200 meshes, the grinding cost is high due to the small particle size.

Specifically, the acid salt solution may include one or more of an ammonium bisulfate solution and an ammonium sulfate solution, wherein the concentration of the acid salt solution may be 1-4 mol/L, such as 2, 2.5, 3, 3.6 mol/L, etc. When the concentration of the acid salt solution is less than 1 mol/L, the leaching efficiency is low due to the low concentration, and when the concentration of the acid salt solution is greater than 4 mol/L, the cost increases due to the high concentration.

Specifically, the mixed liquid-solid ratio of the leaching reaction can be 5-20mL/g, such as 6, 7, 8, 10, 15, 19mL/g, etc., and the reaction temperature can be 50-100°C, such as 51, 62, 70, 86, 91°C, etc. When the reaction temperature is less than 50°C, the leaching efficiency is low. When the temperature is higher than 100°C, the solution evaporates too fast, which is not conducive to the reaction and will also lead to increased costs. The reaction time can be 60-240min, such as 60, 70, 82, 110, 210min, etc. When the reaction time is less than 60min, it is easy to cause incomplete reaction. When the reaction time is greater than 240min, the reaction time is too long and wastes reaction time, resulting in increased costs.

S20, separating the leachate from the first solid-liquid mixture, and performing an aging reaction to obtain a second solid-liquid mixture.

Specifically, the aging reaction temperature can be 10-40°C, for example, 15, 20, 25, 30°C, etc. When the aging reaction temperature is less than 10°C, the reaction activity of ions in the solution is low and the product cannot be precipitated. When the aging reaction temperature is greater than 40°C, the increase in temperature increases the solubility of the system, and the product cannot be precipitated. The aging time can be 12-48h, for example, 15, 17, 24, 32h, etc. When the aging time is less than 12h, the product cannot be obtained or the product growth is imperfect due to the short aging time. When the reaction time is greater than 48h, the aging time is wasted due to the long time, resulting in increased costs.

The filter cake is separated from the second solid-liquid mixture, washed, and dried to obtain hydrated ammonium magnesium sulfate.

Specifically, the crystal form of hydrated ammonium magnesium sulfate is kainite hexahydrate.

In this exemplary embodiment, the method may further include separating the filter cake from the second solid-liquid mixture, and obtaining a filtrate, and using the filtrate to replace all or part of the acid salt solution and mix with the serpentine raw material powder to achieve recycling of the filtrate. The criterion for stopping the circulation is that the concentration of Mg ²⁺ in the leachate is lower than 0.03 g/100 mL. When the concentration of Mg ²⁺ in the leachate is lower than 0.03 g/100 mL, the magnesium in the leachate cannot be precipitated, and thus the product cannot be obtained.

Specifically, after the filtrate is returned to replace the acid salt solution for multiple times, when the concentration of Mg ²⁺ in the obtained leaching solution is lower than 0.03 g/100 mL, the filtrate reaches the standard of full circulation. Ammonia water can be added to the filtrate after full circulation to adjust the pH to neutral, and ammonium sulfate can be recovered by evaporation and crystallization.

In this exemplary embodiment, the method may further include separating the leachate from the first solid-liquid mixture to obtain a filter cake, washing and drying the filter cake to obtain a silicon source that can be used for synthesizing white carbon black or calcium silicate.

In order to better understand the present invention, the content of the present invention is further explained below in combination with specific examples, but the content of the present invention is not limited to the following examples.

Example 1

The stone raw material used in this example is natural lizardite, which is mined from Donghai County, Jiangsu Province. The chemical composition of the raw material is: SiO ₂ 40.32%, CaO 0.85%, MgO 43.67%, Fe ₂ O ₃ 0.77%, Al ₂ O ₃ 0.33%, and H ₂ O 14.05%.

The natural serpentine raw material is dried, crushed and ball-milled to obtain serpentine raw material powder, and the particle size of the powder is controlled at 80-120 meshes.

Accurately weigh 20g of serpentine raw material powder sample, place it in a 250mL conical flask, and add 160mL of 3mol/L ammonium bisulfate solution to the conical flask. Place the conical flask in an oil bath with magnetic stirring, and install a condensation reflux device. The speed of the stirring bar is 240r/min, and react at 100°C for 100min to obtain a solid-liquid mixture of serpentine raw material powder and ammonium bisulfate solution. Filter the solid-liquid mixture to obtain a filtrate and a filter cake.

After the filter cake is washed, it is dried at 80° C. and can be used as a silicon source to prepare materials such as white carbon black and calcium silicate.

Pour 150 mL of the filtrate into a 200 mL beaker for aging reaction at 40°C for 20 h.

The filtrate after the aging reaction is filtered to obtain a filtrate and a filter cake. The filter cake is washed with industrial water until it is neutral and then dried at 40°C to obtain a hydrated ammonium magnesium sulfate product. After testing, the content of magnesium ions is 6.66%, and the physical phase of the product is hexahydrated ammonium magnesium sulfate. The XRD diagram of the obtained hydrated ammonium magnesium sulfate is shown in Figure 1, in which hexahydrated ammonium magnesium sulfate is represented by black dots.

The above steps are continued to be repeated to prepare a hydrated ammonium magnesium sulfate product, wherein the filtrate obtained above is circulated for subsequent leaching of serpentine raw materials instead of ammonium bisulfate solution until the concentration of Mg ²⁺ in the obtained leachate is lower than 0.03 g/100 mL, and the circulation is full when the concentration of Mg ²⁺ in the obtained leachate is lower than 0.03 g/100 mL. After the circulation is full, the pH value of the leachate is adjusted to neutral with ammonia water, and the leachate is evaporated and crystallized at 100° C. for 12 hours to recover ammonium sulfate.

Example 2

The raw material used in this example is chrysotile tailings, which are mined from Aksai, Gansu. The chemical composition of the raw material is: SiO ₂ 42.35%, CaO 0.77%, MgO 41.92%, Fe ₂ O ₃ 0.02%, Al ₂ O ₃ 1.56%, H ₂ O 13.05%, and others 0.33%.

The chrysotile tailings are dried, crushed and ball-milled to obtain chrysotile tailings powder, and the particle size of the powder is controlled at 100-140 meshes.

Accurately weigh 20g of the above-mentioned chrysotile tailing powder sample, place it in a 500mL conical flask, and add 400mL of 2.5mol/L ammonium sulfate solution to the conical flask. Place the conical flask in an oil bath with magnetic stirring, and install a condensation reflux device, the speed of the stirring bar is 180r/min, and react at 85°C for 140min to obtain a solid-liquid mixture of chrysotile tailing powder and ammonium sulfate solution. Filter the solid-liquid mixture to obtain a filtrate and a filter cake.

After the filter cake is washed, it is dried at 80° C. and can be used as a silicon source to prepare materials such as white carbon black and calcium silicate.

300 mL of the filtrate of the serpentine raw material powder was poured into a 500 mL beaker for aging reaction at a temperature of 25° C. for 33 h.

The filtrate after the aging reaction is filtered to obtain a filtrate and a filter cake. The filter cake is washed with industrial water until it is neutral and then dried at 40° C. to obtain a hydrated ammonium magnesium sulfate product. After testing, the content of magnesium ions is 6.65%, and the physical phase of the product is ammonium kainite hexahydrate.

Continue to repeat the above steps to prepare a hydrated ammonium magnesium sulfate product, wherein the filtrate obtained above can be circulated for leaching of serpentine raw material powder until the concentration of Mg ²⁺ in the obtained leachate is lower than 0.03 g/100 mL, and the circulation is full when the concentration of Mg ²⁺ in the obtained leachate is lower than 0.03 g/100 mL. After the circulation is full, the pH value of the leachate is adjusted to neutral with ammonia water, and the leachate is evaporated and crystallized at 100° C. for 48 hours to recover ammonium sulfate.

Although the present invention has been described above by combining with exemplary embodiments, it will be apparent to those skilled in the art that various modifications and changes may be made to the exemplary embodiments of the present invention without departing from the spirit and scope defined in the claims.

Claims (8)

1. A method for preparing hydrated ammonium magnesium sulfate, characterized in that the preparation method comprises the following steps: Mixing serpentine raw material powder and acid salt solution, and performing a mixing reaction to obtain a first solid-liquid mixture; wherein the acid salt solution includes: one or more of ammonium hydrogen sulfate solution and ammonium sulfate solution; the mixing reaction temperature is 50-100° C., and the time is 60-240 min; Separating the leachate from the first solid-liquid mixture and subjecting it to an aging reaction to obtain a second solid-liquid mixture; wherein the aging reaction is carried out at a temperature of 10-40° C. and for a time of 12-48 h; The filter cake is separated from the second solid-liquid mixture, washed, and dried to obtain hydrated ammonium magnesium sulfate. 2. The method for preparing hydrated ammonium magnesium sulfate according to claim 1, characterized in that after separating the filter cake from the second solid-liquid mixture, there is a filtrate, and the method further comprises: using the filtrate to replace all or part of the acid salt solution and mixing with the serpentine raw material powder. 3. The method for preparing hydrated ammonium magnesium sulfate according to claim 1, characterized in that a filter cake is obtained after the leachate is separated from the first solid-liquid mixture, and the method further comprises: washing and drying the filter cake to obtain a silicon source that can be used for the synthesis of white carbon black or calcium silicate. 4. The method for preparing hydrated ammonium magnesium sulfate according to claim 2, characterized in that, after the filtrate is returned multiple times to replace the acid salt solution, if the concentration of Mg ²⁺ in the obtained leachate is lower than 0.03 g/100 mL, the filtrate reaches the standard of full circulation; The method further comprises: adding ammonia water to the filtrate after the circulation is fully completed to adjust the pH to neutral, and recovering ammonium sulfate by evaporation and crystallization. 5. The method for preparing hydrated ammonium magnesium sulfate according to claim 1, characterized in that the particle size of the serpentine raw material powder is 80-200 meshes, the serpentine raw material powder is obtained by drying, crushing and ball milling the serpentine raw material, and the serpentine raw material includes one or more of natural serpentine minerals and tailings produced by mining serpentine minerals. 6. The method for preparing hydrated ammonium magnesium sulfate according to claim 1, wherein the concentration of the acid salt solution is 1-4 mol/L. 7. The method for preparing hydrated ammonium magnesium sulfate according to claim 1, wherein the liquid-to-solid ratio of the mixed reaction is 5-20 mL/g. 8. The method for preparing hydrated ammonium magnesium sulfate according to claim 1, wherein the crystalline form of the hydrated ammonium magnesium sulfate is kainite hexahydrate.