CN-116219529-B - Method for preparing dendritic calcium sulfate by disposing waste liquid from gasified ash

Abstract

The invention provides a method for preparing dendritic calcium sulfate whiskers from gasified ash disposal waste liquid, which mainly comprises the steps of preparing calcium sulfate dihydrate, mixing gasified ash disposal waste liquid with calcium chloride, filtering to obtain a calcium sulfate dihydrate wet filter cake after ageing, adding anhydrous calcium sulfate whisker seed crystal into water, adding zinc acetate and ethylene glycol bis (2-aminoethyl ether) tetra-sodium acetate as a targeting control agent, preparing dendritic calcium sulfate hemihydrate under certain temperature and pressure conditions, filtering, washing and drying to obtain the finished product of dendritic calcium sulfate hemihydrate. The method is simple to operate and low in cost, and the dendritic calcium sulfate hemihydrate whisker is prepared for the first time, has complete crystals and strong supporting force, and is widely applied to industries such as rubber, paint, papermaking, friction materials and the like.

Inventors

• LV LINGLING
• YAN HUILI
• JIA GUODONG
• ZHAO JIE
• LI JIANLONG
• SHAO LEI
• ZHANG XINGONG
• LIU CHENGUANG

Assignees

• 青岛惠城环保科技集团股份有限公司
• 中国石油大学(华东)

Dates

Publication Date

20260508

Application Date

20221125

Claims (4)

1. 1. A method for preparing dendritic calcium sulfate from gasification ash disposal waste liquid, which is characterized by comprising the following steps: Step 1, adding a mixed solution of calcium chloride and urea into gasified ash disposal waste liquid, stirring and ageing for a period of time, and filtering to obtain calcium sulfate dihydrate; Step 2, adding anhydrous calcium sulfate seed crystal into water, adding ethylene glycol bis (2-aminoethyl ether) tetra sodium acetate, stirring for a certain time, adding the calcium sulfate dihydrate obtained in the step 1, adding zinc acetate, filtering and drying after the reaction is finished to obtain dendritic calcium sulfate whiskers; The main component of the gasification slag treatment waste liquid in the step 1 is sodium sulfate, the molar concentration is 10% -20%, and the main component is calcium sulfate, magnesium sulfate, aluminum sulfate, ferrous sulfate and vanadyl sulfate, wherein the pH value is 2-3; In the step 1, the co-current flow and the simultaneous addition of gasified ash treatment waste liquid and calcium chloride are controlled, the supersaturation degree of the system is controlled to be 0.05-0.1, and the molar ratio of urea to calcium chloride is 1-5:1; the ageing temperature in the step 1 is less than 5 ℃ and the ageing time is more than 12 hours; The gasified ash slag in the step1 refers to petroleum coke gasified ash slag; the length-diameter ratio of the calcium sulfate dihydrate in the step 1 is 20-30; The anhydrous calcium sulfate seed crystal in the step 2 is anhydrous calcium sulfate baked at 600 ℃ and has an aspect ratio of more than 20; in the step 2, the molar ratio of ethylene glycol bis (2-aminoethyl ether) tetra-sodium acetate to calcium sulfate dihydrate is=3-5:1, the molar ratio of zinc acetate to calcium sulfate dihydrate is=10-15:1, the temperature is raised to 80-90 ℃ after the ethylene glycol bis (2-aminoethyl ether) tetra-sodium acetate is added, the temperature is raised to 100-105 ℃ after the zinc acetate is added, and the reaction is closed; In the step 2, the stirring rotation speed is 50-150 r/min, and the stirring time is 2-5 h; the calcium sulfate dihydrate added in the step 2 is a filtered wet filter cake which is not dried, and the water content of the filter cake is 30% -40% after the filter cake is dried at 110 ℃ for 2 hours.
2. 2. A method for preparing dendritic calcium sulfate from waste liquid from gasification ash disposal according to claim 1, wherein said filtration is by centrifugation or suction filtration.
3. 3. The method for preparing dendritic calcium sulfate from gasified ash disposal waste liquid according to claim 1, wherein the filtering time of the step 2 is <5min, and the filtrate is used as chlor-alkali raw salt dissolution water.
4. 4. The method for preparing dendritic calcium sulfate from gasified ash disposal waste liquid according to claim 1, wherein the drying temperature of the dendritic calcium sulfate whisker is 140-160 ℃.

Description

Method for preparing dendritic calcium sulfate by disposing waste liquid from gasified ash Technical Field The invention provides a method for preparing dendritic calcium sulfate by treating waste liquid with gasified ash, and relates to the field of comprehensive utilization of high-salt waste water and functional materials. Background With the increasing of environmental protection, china has proposed to limit the import of high sulfur petroleum coke along with the stricter national environmental protection policy, 9 th 2013, the atmospheric pollution control action plan issued by the national institutes, and the current atmospheric pollution control method implemented from 1 st 2016 has stipulated that the import, sales and burning of petroleum coke which does not meet the quality standard are forbidden, so that new demands are put forward on the use direction of petroleum coke, and the petroleum coke is used as a raw material of a gasification device to be a good choice. At present, the gasification devices of some enterprises are mainly used in coal gasification technology, but the mixing amount is less than 30 percent and not more than 50 percent, so that the heavy metal content in the produced ash is low, and the heavy metal content in the gasified slag is over standard due to the heavy metal in the petroleum coke in the gasified slag of the petroleum coke, so that harmless treatment is required, wherein wet leaching is a relatively common method, but a large amount of acid and alkali are used in the wet treatment process, so that a large amount of sodium sulfate high-salt wastewater is produced, and in recent years, the national requirements on the discharge of the high-salt wastewater are increasingly strict, and how to comprehensively utilize the high-salt wastewater to a high value is a direction of attention and research. Calcium sulfate whisker, english name is Calcium Sulfate Whisker, abbreviation is CSW, alias is gypsum whisker or gypsum fiber, molecular formula is CaSO 4. The calcium sulfate whisker is a fibrous monocrystal of calcium sulfate, is in the shape of a needle, has a relatively perfect white loose structure, relatively complete appearance, specific cross section, high strength, high modulus, high insulativity, high temperature resistance, corrosion resistance, good infrared reflectivity, convenient surface treatment, easy compounding with polymer, no toxicity and other good physical and chemical properties. The calcium sulfate whisker has three existence modes, namely calcium sulfate dihydrate, anhydrous calcium sulfate and calcium sulfate hemihydrate. According to the ion arrangement of the calcium sulfate, the semi-hydrated calcium sulfate is used more in practical application because of the self performance advantage, but the semi-hydrated calcium sulfate is easy to hydrate to form the calcium sulfate dihydrate, but the original fiber shape is destroyed in the hydration process, so that the calcium sulfate dihydrate loses excellent performances such as reinforcement, wear resistance and the like, and the calcium sulfate hemihydrate can absorb water in the hydration process, so that the calcium sulfate hemihydrate can be used for absorbing impurity ions in the wastewater to purify the wastewater. The existing common methods for preparing the calcium sulfate whisker mainly comprise a salt solution method, an alcohol solution method, a hydrothermal method, an autoclaved method and the like, for example, patent CN105948547B discloses a method for preparing alpha-type calcium sulfate hemihydrate by utilizing calcium sulfate dihydrate, uniformly mixing the calcium sulfate dihydrate with an additive solution to prepare a mixture, heating the mixture to 130-150 ℃ for 20-120min, crystallizing the calcium sulfate dihydrate in the mixture into alpha-type calcium sulfate hemihydrate, and then drying to obtain the alpha-type calcium sulfate hemihydrate finished product. Patent CN110818304B proposes a method for preparing calcium sulfate dihydrate by using salt gypsum with citric acid as a crystal transformation agent, and then preparing calcium sulfate hemihydrate on the premise of taking calcium sulfate hemihydrate whisker as a seed crystal, wherein the added citric acid reduces the nucleation rate, and the prepared calcium sulfate hemihydrate has large granularity and high strength. However, the semi-hydrated gypsum used as a seed crystal in the process is partially hydrated in the process of the reaction, so that the semi-hydrated gypsum cannot be used as a supporting point for attaching the semi-hydrated calcium sulfate crystals. Patent CN113089076B discloses a method for preparing calcium sulfate whisker based on chlor-alkali salt mud, which comprises the steps of adding calcium sulfate seed crystal into pretreated salt mud solution, adding sulfuric acid to prepare rod-shaped unidirectional fiber calcium sulfate whisker, and simultaneously realizing the reduction of salt mud and the re