阅读说明：本技术 硫酸钙晶须及其原料硫酸钙的生产方法 (calcium sulfate whisker and production method of calcium sulfate as raw material thereof ) 是由 邓敏 石晓林 缑可贞 谢濠江 于 2019-09-19 设计创作，主要内容包括：本发明公开了一种用于生产硫酸钙晶须的原料硫酸钙的生产方法,包括以下步骤：a、向电石渣浆中通入氯气；b、加NaOH；c、固液分离后加Na<Sub>2</Sub>SO<Sub>4</Sub>；d、分离并洗涤固相物,得到用于生产硫酸钙晶须的原料硫酸钙。本发明还公开了一种用于生产硫酸钙晶须的原料硫酸钙,其即是由上述方法所制得。本发明还公开了一种硫酸钙晶须生产方法,该方法即是以上述的用于生产硫酸钙晶须的原料硫酸钙为生产原料进行生产。本发明还公开了一种硫酸钙晶须,该硫酸钙晶须即是由上述硫酸钙晶须生产方法所制得。其优点是：1)提高了硫酸钙晶须的长径比；2)不存在副产物排放问题；3)所使用的生产原料均来自工业副产物,具有显著的经济效益。(The invention discloses a production method of calcium sulfate used as a raw material for producing calcium sulfate whiskers, which comprises the following steps: a. introducing chlorine into the carbide slag slurry; b. adding NaOH; c. adding Na after solid-liquid separation 2 SO 4 (ii) a d. Separating and washing the solid phase substance to obtain the raw material calcium sulfate for producing the calcium sulfate whisker. The invention also discloses a raw material calcium sulfate for producing the calcium sulfate whisker, which is prepared by the method. The invention also discloses a production method of the calcium sulfate whisker, which takes the calcium sulfate used as the raw material for producing the calcium sulfate whisker as a production sourceAnd (5) producing the material. The invention also discloses a calcium sulfate whisker, which is prepared by the production method of the calcium sulfate whisker. The advantages are that: 1) the length-diameter ratio of the calcium sulfate whisker is improved; 2) the problem of byproduct emission does not exist; 3) all the used production raw materials are from industrial byproducts, and the economic benefit is remarkable.)

1. The production method of the raw material calcium sulfate for producing the calcium sulfate whisker comprises the following steps:

A. diluting the carbide slag subjected to solid-liquid separation with water, introducing chlorine gas to enable the pH of the solution to be 4-7, and fully reacting to obtain a first solution;

B. Adding NaOH into the first solution to enable the pH of the solution to be 7-9, and obtaining a second solution;

C. Performing solid-liquid separation on the second solution to obtain a third solution;

D. Adding Na into the third solution₂SO₄Fully reacting the reagent to obtain a fourth solution;

E. carrying out solid-liquid separation on the fourth solution to obtain a calcium sulfate solid phase substance and a clear solution;

F. And washing the calcium sulfate solid phase to obtain the raw material calcium sulfate for producing the calcium sulfate whisker.

2. The production method of the raw material calcium sulfate for producing calcium sulfate whiskers, according to claim 1, is characterized in that: also comprises the following steps: adding Na into the clear solution₂CO₃To make Ca in the solution²⁺The concentration is less than 50ppm, and NaClO solution is obtained by solid-liquid separation after full reaction.

3. The production method of the raw material calcium sulfate for producing calcium sulfate whiskers, according to claim 1, is characterized in that: in the step A, the carbide slag is diluted by adding water to the slurry to obtain Ca (OH)₂The mass concentration of (A) is 180-300 g/L.

4. the production method of the raw material calcium sulfate for producing calcium sulfate whiskers, according to claim 1, is characterized in that: and returning the washing water generated in the step F to the step A for diluting the carbide slag.

5. The production method of the raw material calcium sulfate for producing the calcium sulfate whiskers, according to any one of claims 1 to 4, is characterized in that: in the step A, the reaction temperature is 30-50 ℃, and Ca (ClO) in the mixed salt solution₂the concentration is 0.6-1.15 mol/L, and the content of available chlorine is 80-160 g/L.

6. the production method of the raw material calcium sulfate for producing the calcium sulfate whiskers, according to any one of claims 1 to 4, is characterized in that: and D, controlling the reaction temperature to be 40-60 ℃.

7. The production method of the raw material calcium sulfate for producing the calcium sulfate whiskers, according to any one of claims 1 to 4, is characterized in that: the Na is₂SO₄The reagent is mirabilite, and the chlorine gas is surplus chlorine gas in the chlor-alkali industry.

8. The raw material calcium sulfate for producing the calcium sulfate whisker prepared by the method of claims 1-7.

9. The production method of the calcium sulfate whisker is characterized in that: the production raw material adopted by the production method of the calcium sulfate whiskers is the raw material calcium sulfate for producing the calcium sulfate whiskers, which is defined in claim 8.

10. Calcium sulfate whiskers produced by the calcium sulfate whisker production method according to claim 9.

Technical Field

the invention relates to a production method of calcium sulfate chemical products, in particular to a production method of calcium sulfate whiskers.

Background

the carbide slag is a byproduct of acetylene gas obtained by hydrolyzing calcium carbide, and the main component of the carbide slag is Ca (OH)₂And contains various impurities. Under the influence of energy structures in China, vinyl chloride monomer produced by acetylene obtained by a calcium carbide method occupies a large proportion in China, and 1.0t of calcium carbide is added with water to generate more than 300kg of acetylene gas and more than 3.0t of calcium carbide slag with the solid content of about 50 percent. Because the carbide slag contains various impurities and has high purification cost, the carbide slag has low byproduct value and is even piled as waste in partial areas, thereby causing influence on the environment.

Calcium sulfate whiskers are a fibrous sub-nanomaterial that grows in the form of single crystals with needle-like, uniform cross-sections. The shape is caused by the difference of the growth rate of the crystal in the axial direction and the lateral surface, the crystal whisker mainly grows along the spiral dislocation of the axial direction, the lateral surface is a low energy surface, and the growth is very slow.

At present, the production method of the calcium sulfate whisker mainly comprises a hydrothermal method and an acidification method.

The hydrothermal method is characterized in that a gypsum solution is heated in a closed high-pressure reaction container, when the heat energy gathered by the gypsum is enough to overcome the attraction between individual molecules, the displacement defect is generated on crystal lattices, water molecules are prominent along the crystal lattice defect and the original surface defect, and Ca is used for removing the crystal lattice defect²⁺and SO₄ ^2-And (4) displacement is carried out, new balance is achieved, and finally the calcium sulfate whisker is generated.

the acidification method is that under a certain temperature and normal pressure, the high-concentration calcium sulfate dihydrate suspension can be converted into needle-shaped or fibrous calcium sulfate whiskers in a strong acid solution.

Chinese patent publication No. CN105483816A discloses a method for preparing calcium sulfate whiskers from carbide slag and waste sulfuric acid, in which calcium carbide slag slurry and hydrochloric acid are subjected to acid leaching reaction to remove impurities in the carbide slag slurry, then sulfuric acid is used to react with the purified carbide slag slurry to obtain calcium sulfate, and finally filtered calcium sulfate is used to prepare calcium sulfate whiskers by a hydrothermal method. The scheme provides that the carbide slag can be used for producing the calcium sulfate whiskers, widens the recovery path of the carbide slag and has positive significance. However, this solution still has the following drawbacks:

1. The calcium sulfate whisker produced by the method has poor quality, mainly has low length-diameter ratio and low utilization value.

2. The by-products of the scheme are a large amount of acidic wastewater which is difficult to treat, in the scheme, the acidic wastewater is returned to the acid leaching process to be mixed with hydrochloric acid for leaching the carbide slag slurry, but the HCl is continuously diluted after calcium sulfate is separated out, and the acid leaching is difficult to perform; moreover, impurity ions in the acidic wastewater are continuously enriched along with the process circulation, so that the quality of the calcium sulfate whisker is seriously influenced; therefore, the acidic waste water still has to be discharged periodically, and the problem of treatment is a big problem.

Disclosure of Invention

in order to improve the quality of the calcium sulfate whisker produced by taking the carbide slag as a raw material and improve the length-diameter ratio on the premise of ensuring economic feasibility, the invention provides a method for producing the raw material calcium sulfate for producing the calcium sulfate whisker by using the carbide slag.

The technical scheme adopted by the invention is as follows: the production method of the raw material calcium sulfate for producing the calcium sulfate whisker comprises the following steps:

A. Diluting the carbide slag subjected to solid-liquid separation with water, introducing chlorine gas to enable the pH of the solution to be 4-7, and fully reacting to obtain a first solution;

B. Adding NaOH into the first solution to enable the pH of the solution to be 7-9, and obtaining a second solution;

C. Performing solid-liquid separation on the second solution to obtain a third solution;

D. Adding Na into the third solution₂SO₄Fully reacting the reagent to obtain a fourth solution;

E. Carrying out solid-liquid separation on the fourth solution to obtain a calcium sulfate solid phase substance and a clear solution;

F. and washing the calcium sulfate solid phase to obtain the raw material calcium sulfate for producing the calcium sulfate whisker.

It has been found that the method disclosed in chinese patent publication No. CN105483816A has the following problems: electric powerThe stone slag brings Al into the system³⁺Ion, and Al³⁺The ions affect the length and width of the resulting calcium sulfate raw material crystals, ultimately resulting in shorter synthesized whiskers. In the invention, the purification process of the carbide slag and the process of generating the calcium sulfate raw material are always carried out under the acidic condition, and Al is carried out under the acidic condition³⁺ions are difficult to form precipitates to leave the system, so that the diameter-length ratio of the calcium sulfate whiskers is reduced, and only short rod-shaped whiskers can be obtained.

On the other hand, the system contains pH₃Leads to an increase in the crystal size of the calcium sulfate raw material to be produced, thereby increasing the diameter of the whiskers to be formed and leading to a decrease in the aspect ratio. And part of the pH value dissolved in the carbide slag slurry₃And traces of acetylene. In the invention, the purification process of carbide slag and the PH process of the process of generating calcium sulfate raw material₃And the calcium sulfate whisker is not effectively removed, so that the quality of the calcium sulfate whisker is poor.

In the present invention, the inventors introduced chlorine gas into carbide slag slurry to adjust the pH thereof₃Is oxidized into phosphate, thereby effectively removing the pH in the system₃(ii) a At the same time, the introduction of chlorine also leads to slightly soluble Ca (OH)₂conversion to more soluble CaCl₂and Ca (ClO)₂The salt solution (first solution) was mixed. The introduction of chlorine gas causes the pH value of the system to be acidic, which is not favorable for Al³⁺The invention removes the ions by adding NaOH to make the system alkalescent, thereby removing Al³⁺. It should be noted that the amount of NaOH added is controlled to be 7-9 pH to avoid Al³⁺Ion conversion to Al (OH)^4-Ions.

experiments show that the calcium sulfate whisker product with higher length-diameter ratio can be obtained by adopting the raw material calcium sulfate prepared by the method to produce the calcium sulfate whisker.

The main reactions involved in the present invention are as follows:

2Ca(OH)₂+2Cl₂→CaCl₂+Ca(ClO)₂+2H₂O

PH₃+4Cl₂+4H₂O+5Ca(OH)₂→CaHPO₄+CaCl₂+6H₂O

CaCl₂+Ca(ClO)₂+2Na₂SO₄+2H₂O→2CaSO₄·2H₂O↓+2NaCl+2NaClO

As a further improvement of the invention, the method also comprises the following steps: adding Na into the clear solution₂CO₃To make Ca in the solution²⁺the concentration is less than 50ppm, and NaClO solution is obtained by solid-liquid separation after full reaction. The obtained clear solution contains more Ca²⁺in order to realize the recycling of clear liquid, a proper amount of Na can be added₂CO₃Make Ca²⁺Precipitating to obtain a high-quality NaClO solution; the NaClO solution can be used as a raw material for producing hydrazine hydrate and can also be used as a bleaching agent.

For the convenience of pipeline transportation, the carbide slag is diluted by adding water, and in the step A, the carbide slag can be diluted by adding water to Ca (OH) in the slurry₂The mass concentration of (A) is 180-300 g/L.

As a further improvement of the invention, the washing water generated in the step F is returned to the step A for diluting the carbide slag, so that the water resource is recycled.

As a further improvement of the invention, the reaction temperature in the step A is 30-50 ℃, and Ca (ClO) in the first solution₂The concentration is 0.6-1.15 mol/L, and the content of available chlorine is 80-160 g/L. The available chlorine content is a term referring to the content of chlorine in the chlorine compound in the oxidized state.

As a further improvement of the method, the reaction temperature in the step D is 40-60 ℃.

as a further improvement of the invention, the Na₂SO₄The reagent is mirabilite, and the chlorine gas is surplus chlorine gas in the chlor-alkali industry. Mirabilite is a byproduct in the brine treatment process of chlor-alkali enterprises, and the brine contains a small amount of Na₂SO₄To avoid Na₂SO₄The ionic membrane of the electrolytic cell is influenced, so that the brine needs to be subjected to membrane separation on Na₂SO₄Concentrating, and coolingThe byproduct mirabilite can be obtained by freezing and crystallizing, the utilization value of the mirabilite is also low, the problem of treatment when the mirabilite is excessive is a big problem troubling chlor-alkali enterprises, and the proposal takes the mirabilite as Na₂SO₄The reagent is used, thereby solving the problem of mirabilite treatment to a certain extent and obviously reducing the production cost of the calcium sulfate whisker. Meanwhile, a large amount of surplus chlorine is generated in the chlor-alkali industry, so the scheme utilizes the surplus chlorine in the chlor-alkali industry as a production raw material, and further reduces the production cost of the calcium sulfate whisker.

the invention also discloses a raw material calcium sulfate for producing the calcium sulfate whisker, which is prepared by the method.

The invention also discloses a production method of the calcium sulfate whisker, which takes the calcium sulfate used as the raw material for producing the calcium sulfate whisker as the production raw material.

The invention also discloses a calcium sulfate whisker, which is prepared by the production method of the calcium sulfate whisker.

The invention has the beneficial effects that: 1) the length-diameter ratio of the calcium sulfate whisker is improved; 2) the byproduct is high-quality NaClO solution; the NaClO solution can be used as a hydrazine hydrate production raw material and can also be used as a bleaching agent, so that the problem of byproduct emission does not exist in the invention; 3) the used production raw materials are basically from industrial byproducts, the production cost is low, and the economic benefit is remarkable.

Detailed Description

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