阅读说明：本技术 用高钠镁比硫酸钠工业废水制备花球状氢氧化镁的方法 (Method for preparing flower-ball-shaped magnesium hydroxide from industrial wastewater of sodium sulfate with high sodium-magnesium ratio ) 是由 刘志启 闫东强 赵鹏程 周自圆 李娜 焦玲丽 于 2021-09-29 设计创作，主要内容包括：本发明公开了一种用高钠镁比硫酸钠工业废水制备花球状氢氧化镁的方法,属氢氧化镁制备领域。该方法是在两个敞口容器中分别装入高钠镁比硫酸钠工业废水、氨水,再将两个容器在密闭环境反应一定时间后,装入高钠镁比硫酸钠工业废水的容器产生白色沉淀,经过滤、洗涤后得到滤渣,滤渣干燥后即为花球状的氢氧化镁。本发明解决了高钠镁比硫酸钠工业废水的绿色资源化利用问题,通过利用氨水的挥发性和溶解性将高钠环境中含量比较低的镁净化得到纯度高的硫酸钠溶液,同时使镁转化为实用价值高的氢氧化镁。(The invention discloses a method for preparing flower-ball-shaped magnesium hydroxide from industrial wastewater of sodium sulfate with high sodium-magnesium ratio, belonging to the field of magnesium hydroxide preparation. The method comprises the steps of respectively filling sodium sulfate industrial wastewater with high sodium magnesium ratio and ammonia water into two open containers, reacting the two containers in a closed environment for a certain time, filling the containers with the sodium sulfate industrial wastewater with high sodium magnesium ratio to generate white precipitates, filtering and washing to obtain filter residues, and drying the filter residues to obtain the flower-ball-shaped magnesium hydroxide. The method solves the problem of green resource utilization of the industrial wastewater with high sodium-magnesium ratio and sodium sulfate, purifies the magnesium with lower content in the high-sodium environment by utilizing the volatility and the solubility of ammonia water to obtain the sodium sulfate solution with high purity, and converts the magnesium into the magnesium hydroxide with high practical value.)

1. The method for preparing the flower-ball-shaped magnesium hydroxide by using the industrial wastewater with the high sodium-magnesium ratio sodium sulfate is characterized by comprising the following steps of:

step 1, taking ammonia water and high-sodium-magnesium-ratio sodium sulfate industrial wastewater, and respectively filling the ammonia water and the high-sodium-magnesium-ratio sodium sulfate industrial wastewater into different open containers, wherein the mass concentration of the ammonia water is 10-30%, and the volume mass ratio of the taken ammonia water to the high-sodium-magnesium-ratio sodium sulfate industrial wastewater is 1:0.1-1: 1;

step 2, respectively placing the open containers filled with ammonia water and the high sodium magnesium ratio sodium sulfate industrial wastewater in a closed environment, standing at 20-100 ℃ for reaction for 12-48h to volatilize ammonia gas from the ammonia water, dissolving the volatilized ammonia gas in the high sodium magnesium ratio sodium sulfate industrial wastewater to react with magnesium ions, and thus obtaining white solids in the open containers filled with the high sodium magnesium ratio sodium sulfate industrial wastewater;

and 3, after the step 2 is finished, filtering the industrial wastewater containing the white solid and high-sodium-magnesium-ratio sodium sulfate to obtain filter residue, and drying the filter residue at the temperature of 80-110 ℃ for 5-10h to obtain the magnesium hydroxide with the shape of a flower ball.

2. The method for preparing the flower-ball-shaped magnesium hydroxide by using the industrial wastewater with the high sodium-magnesium ratio and the sodium sulfate as claimed in claim 1, wherein in the industrial wastewater with the high sodium-magnesium ratio and the sodium-magnesium ratio in step 1, the content of magnesium sulfate is 0.1-0.2mol/L, and the sodium-magnesium ratio is 20-40.

3. The method for preparing flower-ball-shaped magnesium hydroxide by using the industrial wastewater with the high sodium-magnesium ratio and the high sodium-magnesium ratio as claimed in claim 1, wherein the reaction temperature in the step 2 is 20-100 ℃, and the reaction time is 12-48 h.

4. The method for preparing flower-ball-shaped magnesium hydroxide from the industrial wastewater with high sodium-magnesium ratio and sodium sulfate as claimed in claim 1, wherein after the reaction in step 2 is finished, the pH value of the industrial wastewater with high sodium-magnesium ratio and sodium sulfate is in the range of 10.5-12.5, and if the pH value is below 10.5, the standing reaction is continued for 5-10h according to step 2.

5. The method for preparing flower-ball-shaped magnesium hydroxide from the industrial wastewater with the high sodium-magnesium ratio and the high sodium-magnesium ratio as claimed in claim 1, wherein the drying temperature of the filter residue in the step 3 is 80-110 ℃, and the drying time is 5-10 h.

6. The method for preparing flower-ball-shaped magnesium hydroxide from the industrial wastewater containing sodium sulfate and magnesium sulfate with high sodium-magnesium ratio as claimed in claim 1, wherein the filtrate obtained after filtration in step 3 is a high-purity saturated sodium sulfate solution.

Technical Field

The invention relates to the field of magnesium hydroxide preparation methods, in particular to a method for preparing flower-ball-shaped magnesium hydroxide from industrial wastewater with high sodium-magnesium ratio sodium sulfate.

Background

With the improvement of environmental protection standards in recent years in China, the green resource utilization of industrial waste liquid is greatly developed. At the present stage, the large-scale treatment of the high-salinity wastewater still has the characteristics of low treatment efficiency and high operation cost, and has a plurality of key technical problems which need to be broken through and solved. The industrial wastewater with high sodium-magnesium ratio mainly comes from drainage generated in the production processes of enterprises such as printing and dyeing, refining, pharmacy, salt manufacturing and the like, and has the characteristics of high content of sodium sulfate and small amount of magnesium sulfate. If the direct evaporation crystallization is not processed, the purity of the sodium sulfate is too low, and the magnesium resource cannot be comprehensively utilized, so that the resource is seriously wasted. If the waste water is directly discharged, the waste water can cause serious pollution to soil and water quality.

Magnesium hydroxide is used as an inorganic material, has the characteristics of no toxicity, no odor, no corrosiveness, high decomposition temperature and the like, and has very important application in the fields of flame retardance, environmental protection, medical use, food, ceramics, cosmetics and the like. With the continuous development of modern society science and technology, the requirements of people on new materials are continuously improved, and the requirements of magnesium hydroxide used in different fields are different, so that the appearance, the specific surface area, the granularity and other properties of the magnesium hydroxide are mainly concerned in recent years.

The current methods for producing magnesium hydroxide include the following: the first is prepared by reacting bittern with slaked lime. Secondly, the brine which is purified to remove impurities such as sulfate, carbon dioxide, a small amount of boron and the like is used as a raw material, and ammonia water is used as a precipitator to carry out precipitation reaction in a reaction kettle, so that the magnesium hydroxide is prepared. And thirdly, calcining the magnesite ore and anthracite or coke in a shaft kiln to generate magnesium oxide and carbon dioxide. The bitter earth powder is mixed into slurry with water and then reacts with hydrochloric acid with specified concentration to prepare magnesium chloride solution. The magnesium chloride solution reacts with ammonia water with certain concentration in a reactor, and the product is washed, settled, filtered, separated, dried and crushed to obtain the magnesium hydroxide product. Fourthly, extracting the pulpous magnesium hydroxide by using concentrated seawater. The prior art has no method for recycling magnesium hydroxide from industrial wastewater with high sodium-magnesium ratio sodium sulfate, so that a method for recycling magnesium hydroxide in industrial wastewater is needed.

The method for preparing magnesium hydroxide from a magnesium-containing solution in the prior art mostly directly adds strong base for precipitation to obtain a magnesium hydroxide product, and the magnesium hydroxide prepared by the process is mostly flaky and has the technical problem of difficult solid-liquid separation. In other methods, ammonia water is directly added, and magnesium hydroxide is obtained by stirring, the reaction is violent in the process, and a large amount of unreacted ammonia water cannot be recycled.

Disclosure of Invention

The invention aims to provide a method for preparing flower-ball-shaped magnesium hydroxide from industrial wastewater containing sodium sulfate with a high sodium-magnesium ratio, so as to solve the problem that magnesium hydroxide is not recycled from industrial wastewater containing sodium sulfate with a high sodium-magnesium ratio in the prior art.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

the method for preparing the flower-ball-shaped magnesium hydroxide by using the industrial wastewater of the sodium sulfate with the high sodium-magnesium ratio comprises the following steps:

step 1, taking ammonia water and high-sodium-magnesium-ratio sodium sulfate industrial wastewater, and respectively filling the ammonia water and the high-sodium-magnesium-ratio sodium sulfate industrial wastewater into different open containers, wherein the mass concentration of the ammonia water is 10-30%, and the volume mass ratio of the taken ammonia water to the high-sodium-magnesium-ratio sodium sulfate industrial wastewater is 1:0.1-1: 1;

step 2, respectively placing the open containers filled with ammonia water and the high sodium magnesium ratio sodium sulfate industrial wastewater in a closed environment, standing at 20-100 ℃ for reaction for 12-48h to volatilize ammonia gas from the ammonia water, dissolving the volatilized ammonia gas in the high sodium magnesium ratio sodium sulfate industrial wastewater to react with magnesium ions, and thus obtaining white solids in the open containers filled with the high sodium magnesium ratio sodium sulfate industrial wastewater;

and 3, after the step 2 is finished, filtering the industrial wastewater containing the white solid and high-sodium-magnesium-ratio sodium sulfate to obtain filter residue, and drying the filter residue at the temperature of 80-110 ℃ for 5-10h to obtain the magnesium hydroxide with the shape of a flower ball.

Further, in the sodium sulfate industrial wastewater with high sodium magnesium ratio in the step 1, the content of magnesium sulfate is 0.1-0.2mol/L, and the sodium magnesium ratio is 20-40.

Further, the reaction temperature in the step 2 is 20-100 ℃, and the reaction time is 12-48 h.

Further, after the reaction in the step 2 is finished, and after the reaction in the step 2 is finished, the pH value of the industrial wastewater with high sodium-magnesium ratio is 10.5-12.5, and if the pH value is below 10.5, the industrial wastewater needs to be kept standing for 5-10 hours according to the step 2.

Further, the drying temperature of the filter residue in the step 3 is 80-110 ℃, and the drying time is 5-10 h.

Further, the filtrate obtained after filtration in step 3 is a high-purity saturated sodium sulfate solution.

The method can purify and remove magnesium in the industrial waste liquid with high sodium-magnesium ratio and prepare the flower-ball-shaped magnesium hydroxide at the same time. Through the precipitation reaction between the industrial waste liquid of sodium sulfate with high sodium magnesium ratio and ammonia water volatilized ammonia gas, magnesium ions in the industrial waste liquid of sodium sulfate with high sodium magnesium ratio, ammonium ions in the volatilized ammonia gas and water react to generate magnesium hydroxide precipitate, and the reaction equation is as follows:

Mg²⁺+2NH₃+2H₂O=Mg(OH)₂↓+2NH₄ ⁺

compared with the prior art, the invention has the advantages that: the method solves the problem of green resource utilization of the industrial wastewater with high sodium-magnesium ratio and sodium sulfate, purifies and removes the magnesium with lower content in the high-sodium environment to obtain the sodium sulfate solution with high purity by utilizing the volatility and the solubility of the ammonia water, and simultaneously converts the magnesium into the magnesium hydroxide with high practical value; the process has simple flow and low production cost, and does not need any additive.

Compared with the prior art, the invention has the advantages that: according to the invention, ammonia is formed by ammonia water instead of directly mixing the ammonia-containing raw material with other raw materials, so that the ammonia is dissolved in the sodium sulfate industrial wastewater with high sodium-magnesium ratio, the reaction is stable and stable, and the safety is high.

Compared with the prior art, the invention has the advantages that: the method does not prepare the magnesium hydroxide by directly reacting the solution containing magnesium with strong alkali, so that the solid-liquid separation rate is obviously improved after the reaction is finished.

Compared with the prior art, the invention has the advantages that: the invention does not need stirring in the reaction process, so that the prepared magnesium hydroxide is in a flower ball shape, and the ammonia water is not directly added into the reaction raw materials, so that the ammonia water can be recycled after the reaction is finished until the ammonia water has no volatility completely.

Drawings

FIG. 1 is an X-ray diffraction pattern of the product of the present invention.

FIG. 2 is a scanning electron microscope image of the product of the present invention at a magnification of 3 kXe.

FIG. 3 is a scanning electron microscope image of the product of the present invention at a magnification of 1.1 ten thousand times.

Detailed Description

The present invention will be further described with reference to the following examples.

Example 1

The method for preparing the flower-ball-shaped magnesium hydroxide by using the industrial wastewater of the sodium sulfate with the high sodium-magnesium ratio comprises the following steps:

step 1, measuring 150ml of high sodium magnesium ratio sodium sulfate industrial wastewater, placing the industrial wastewater in a beaker A, and measuring 100ml of ammonia water with the mass fraction of 25% and placing the industrial wastewater in a beaker B.

The sodium sulfate in the adopted high sodium magnesium ratio sodium sulfate industrial wastewater is nearly saturated, the content of magnesium sulfate is lower, the content of magnesium sulfate is 0.2mol/L, and the sodium magnesium ratio is 25.

And 2, putting the beaker A filled with the industrial wastewater with the high sodium magnesium ratio sodium sulfate and the beaker B filled with ammonia water into a sealed reactor C in an alternate mode, standing for 24 hours at the temperature of 25 ℃, volatilizing the ammonia water to form ammonia gas in the standing reaction process, taking the industrial wastewater with the high sodium magnesium ratio sodium sulfate dissolved in the beaker A as a precipitator, and reacting the dissolved ammonia gas with magnesium ions in the industrial wastewater with the high sodium magnesium ratio sodium sulfate, thereby generating white precipitates in the beaker A.

Step 3, after the step 2 is finished, carrying out suction filtration on the solution in the beaker A to obtain filter residue and filtrate, wherein the filtrate is high-purity saturated sodium sulfate solution; washing the filter residue for multiple times, and drying the washed filter residue for 5 hours at the temperature of 95 ℃ to obtain the flower-ball-shaped magnesium hydroxide.

Example 2

The method for preparing the flower-ball-shaped magnesium hydroxide by using the industrial wastewater of the sodium sulfate with the high sodium-magnesium ratio comprises the following steps:

step 1, measuring 150ml of high sodium magnesium ratio sodium sulfate industrial wastewater, placing the industrial wastewater in a beaker A, and measuring 100ml of ammonia water with the mass fraction of 10% and placing the industrial wastewater in a beaker B.

The sodium sulfate in the adopted high sodium magnesium ratio sodium sulfate industrial wastewater is nearly saturated, the content of magnesium sulfate is lower, the content of magnesium sulfate is 0.2mol/L, and the sodium magnesium ratio is 25.

And 2, putting the beaker A filled with the industrial wastewater with the high sodium magnesium ratio sodium sulfate and the beaker B filled with ammonia water into a sealed reactor C in an alternate mode, standing for 24 hours at the temperature of 25 ℃, volatilizing the ammonia water to form ammonia gas in the standing reaction process, taking the industrial wastewater with the high sodium magnesium ratio sodium sulfate dissolved in the beaker A as a precipitator, and reacting the dissolved ammonia gas with magnesium ions in the industrial wastewater with the high sodium magnesium ratio sodium sulfate, thereby generating white precipitates in the beaker A.

Step 3, after the step 2 is finished, carrying out suction filtration on the solution in the beaker A to obtain filter residue and filtrate, wherein the filtrate is high-purity saturated sodium sulfate solution; washing the filter residue for multiple times, and drying the washed filter residue for 5 hours at the temperature of 95 ℃ to obtain the flower-ball-shaped magnesium hydroxide.

Example 3

The method for preparing the flower-ball-shaped magnesium hydroxide by using the industrial wastewater of the sodium sulfate with the high sodium-magnesium ratio comprises the following steps:

step 1, measuring 150ml of high sodium magnesium ratio sodium sulfate industrial wastewater, placing the industrial wastewater in a beaker A, and measuring 100ml of ammonia water with the mass fraction of 25% and placing the industrial wastewater in a beaker B.

The sodium sulfate in the adopted high sodium magnesium ratio sodium sulfate industrial wastewater is nearly saturated, the content of magnesium sulfate is lower, the content of magnesium sulfate is 0.2mol/L, and the sodium magnesium ratio is 25.

And 2, putting the beaker A filled with the industrial wastewater with the high sodium magnesium ratio sodium sulfate and the beaker B filled with ammonia water into a sealed reactor C in an alternate mode, standing for 12 hours at the temperature of 60 ℃, volatilizing the ammonia water to form ammonia gas in the standing reaction process, taking the industrial wastewater with the high sodium magnesium ratio sodium sulfate dissolved in the beaker A as a precipitator, and reacting the dissolved ammonia gas with magnesium ions in the industrial wastewater with the high sodium magnesium ratio sodium sulfate, thereby generating white precipitates in the beaker A.

Step 3, after the step 2 is finished, carrying out suction filtration on the solution in the beaker A to obtain filter residue and filtrate, wherein the filtrate is high-purity saturated sodium sulfate solution; washing the filter residue for multiple times, and drying the washed filter residue for 5 hours at the temperature of 95 ℃ to obtain the flower-ball-shaped magnesium hydroxide.

FIG. 1 is an X-ray diffraction pattern of the products obtained in examples 1, 2 and 3. from FIG. 1, it can be seen that the prepared sample corresponds to a standard card of magnesium hydroxide, indicating that the product obtained by the above-described method corresponds to the product of the present application.

FIGS. 2 and 3 show the regular spherical shapes of the products obtained in example 1 by scanning electron microscopy at 3 and 1.1 times magnification, indicating that the morphology of the products obtained in the above-described manner is consistent with that of the present application.

The embodiments of the present invention are described only for the preferred embodiments of the present invention, and not for the limitation of the concept and scope of the present invention, and various modifications and improvements made to the technical solution of the present invention by those skilled in the art without departing from the design concept of the present invention shall fall into the protection scope of the present invention, and the technical content of the present invention which is claimed is fully set forth in the claims.