WO2023068587A1 - Method for preparing gypsum by using bio-sulfur, and use thereof - Google Patents

Abstract

Disclosed are: a method for preparing gypsum, which contains a large amount of anhydrite, by using bio-sulfur; and a use of gypsum prepared thereby. The preparation method according to the present invention allows gypsum, which contains a large amount of anhydrite, to be prepared in an eco-friendly manner. The gypsum according to the present invention contains a large amount of anhydrite, and does not contain environmental pollutants such as heavy metal ions since bio-sulfur is used, and thus can be used as gypsum for a gypsum board, an auxiliary material for blast furnace slag grinding, an admixture for cement, gypsum for slag cement, and the like.

Description

Gypsum manufacturing method using biosulfur and its use

The present invention relates to a method for producing gypsum using biosulfur and its use, and more particularly, to a method for producing gypsum containing a high content of anhydrite using biosulfur and the use of gypsum prepared therefrom.

Gypsum can be largely divided into naturally produced natural gypsum and artificially manufactured gypsum. In most natural gypsum, CaCO ₃ is first precipitated as limestone by evaporation of seawater, and then the precipitated gypsum is deposited in layers as gypsum. There is no natural gypsum in Korea, so it is imported from Thailand and other countries.

In general, for the artificial production of gypsum, it is common to use desulfurized gypsum generated in a process for removing sulfur components generated during combustion of coal used in a fluidized bed boiler. In addition, phosphate by-product gypsum generated during the manufacture of phosphate fertilizer is being used. However, phosphate byproduct gypsum is not only unsuitable for use as a gypsum board or cement raw material due to its low quality, and is mostly neglected or landfilled due to the presence of various impurities such as unreacted phosphorus. The inclusion of heavy metals in leachate has become an environmental problem. In particular, recently, due to the generation of radon, its use as a raw material for cement or gypsum board is prohibited.

In addition, a method of neutralizing waste sulfuric acid generated in various industrial production processes with a calcium compound and producing gypsum as a by-product is widely known. However, waste sulfuric acid generated in general industrial production processes contains a lot of fluorine, so it is not suitable for use as a raw material for cement and gypsum board because the content of fluorine and chemical impurities in gypsum produced by simply neutralizing it is high.

On the other hand, there is also an attempt to manufacture a lime sulfur mixture using high purity quicklime and sulfur (99.5% or more). Since the conventional lime sulfur mixture manufacturing method uses high-purity quicklime and sulfur (99.5% or more) as raw materials, the price rises as the purity of quicklime increases, handling of high-purity quicklime is inconvenient, and when quicklime reacts with sulfur and water, excessive amounts In addition to rapidly generating heat, toxic gases such as H ₂ S, SO ₂ and SO ₃ are generated, so a separate removal device is required to remove toxic gases. In addition, after reacting quicklime and sulfur, waste sludge (occurring about 20%) and wastewater are generated in large quantities, so there is a problem in that a lot of environmental management costs are incurred to treat them. Powdered sulfur used in the manufacture of lime sulfur mixture has a melting point of 115 ° C or higher and does not change shape below the melting point, and problems such as irregular rapid rise in temperature and pressure due to temporary absorption of water by solid sulfur have been reported.

Meanwhile, in the cement industry, gypsum is used as an essential admixture for cement. Gypsum delays the hydration of components with fast hydration reactions, such as 3CaO-Al ₂ O ₃ among cement constituents, and serves to impart expansiveness to cement. Also, in the process of manufacturing slag cement, anhydrite is used a lot. The anhydrite used at this time serves to improve the activity of the blast furnace slag fine powder contained in the slag cement and reduce shrinkage (Republic of Korea Patent No. 10-0461586).

Therefore, there is an urgent need to develop a new method for producing gypsum having a high content of anhydrite without causing the problems of the prior art in the method for producing gypsum.

Accordingly, the present inventors have continued research to meet the needs of the prior art, and as a result, when gypsum is produced under specific conditions using biosulfur, it is environmentally friendly and has a high quality of 60% by weight or more of the content of anhydrite (CaSO ₄ ). It was confirmed that gypsum could be obtained and the present invention was completed.

Therefore, an object of the present invention is to provide an environmentally friendly method for producing gypsum containing a high content of anhydrite using biosulfur.

Another object of the present invention is to provide gypsum containing a high content of anhydrite prepared by the above production method.

Another object of the present invention is to provide a composition for gypsum board containing the gypsum.

Another object of the present invention is to provide an auxiliary material for grinding blast furnace slag containing the gypsum.

Another object of the present invention is to provide an admixture for cement containing the gypsum.

Another object of the present invention is to provide a slag cement containing the gypsum.

Another object of the present invention is to provide a concrete composition containing the slag cement.

In order to achieve the above object, the present invention

In addition, the method for producing gypsum using biosulfur of the present invention,

i) heating bio-sulfur at 100 to 120° C. to dissolve contained sulfur;

ii) mixing 0.5 to 20 parts by weight of an anionic surfactant based on 100 parts by weight of sulfur contained in biosulfur;

iii) adding 100 to 600 parts by weight of water based on 100 parts by weight of CaO contained in circulating fluidized bed boiler coal ash and/or lime and mixing for 3 to 10 minutes;

iv) based on 100 parts by weight of the mixture of step ii), adding 80 to 150 parts by weight of the mixture of step iii) while stirring at a rotational speed of 300 rpm or more, heating and mixing at 100 to 120 ° C. for 6 to 10 hours; and

v) heating the mixture of step iv) at a heating rate of 5 to 10 °C/min to 300 to 500 °C and baking for 30 to 90 minutes;

In the present invention, 'biosulfur' refers to an aqueous suspension containing elemental sulfur produced through a biological sulfur conversion process. Compared to chemically produced sulfur, biosulfur is hydrophilic and is a stable aqueous phase suspension in which elemental sulfur is suspended in a particle size of less than 10 μm. In addition, biosulfur has little toxicity and can be used without the legalization required for chemically produced sulfur.

In order to use biogas or natural gas as a fuel, biosulfur goes through a desulfurization process to remove hydrogen sulfide (H ₂ S) contained in the gas to protect facilities and prevent air pollution. At this time, hydrogen sulfide (H ₂ S) It is produced in the treatment process and is also commercially available.

Gypsum is a sulfate mineral whose main component is calcium sulfate (CaSO ₄ ), and is composed of anhydrous gypsum (CaSO ₄ ), dihydrate gypsum (CaSO ₄ 2H ₂ O), and/or hemihydrate gypsum (CaSO ₄ 1/2H ₂ O). exist in the form Since anhydrite has various uses, such as being used as a setting agent for cement, it is preferable to manufacture gypsum having a high anhydrite content. In the present invention, 'gypsum' means containing 60% or more of anhydrite.

In the present invention, 'circulating fluidized bed boiler coal ash' refers to coal ash generated during coal combustion in a circulating fluidized bed boiler, and contains a large amount of CaO components.

In the present invention, 'lime flow' may include limestone, slaked lime, quicklime, waste limestone, limestone sludge, and slaked lime sludge containing CaO components.

Step i): Sulfur dissolution

Bio-sulfur is heated at 100 to 120 ° C. to dissolve contained sulfur.

In the present invention, it is preferable to use biosulfur containing 40% by weight or more of sulfur (solid content). If sulfur is less than 40% by weight in biosulfur, there is a disadvantage in that the amount of gypsum is reduced. Preferably, it is most preferable to use biosulfur having 50% by weight or more of sulfur.

At temperatures below 100 ° C, sulfur contained in biosulfur does not dissolve, and at temperatures above 120 ° C, energy efficiency decreases.

It is preferable to dissolve sulfur at 200 to 300 rpm for 1 hour or more while maintaining the above temperature so that the sulfur component contained in bio-sulfur is completely dissolved.

Step ii) Surfactant Mixing

0.5 to 20 parts by weight of an anionic surfactant is mixed with respect to 100 parts by weight of sulfur contained in biosulfur.

In the present invention, an anionic surfactant is used as a surfactant for accelerating the reaction. Anionic surfactants that may be used include sulfonic acid-based or sulfuric acid ester-based surfactants, and these surfactants may be used alone or in a mixture of two or more.

Mixing proceeds for 1 to 3 minutes at 200 to 300 rpm.

Step iii): Prepare the CaO mixture

100 to 600 parts by weight of water is added to 100 parts by weight of CaO contained in circulating fluidized bed boiler coal ash and/or lime, and mixed for 3 to 10 minutes.

In the present invention, the circulating fluidized bed boiler coal ash and limes have a CaO content of 30% by weight or more and are used in the form of a powder pulverized to a fineness of 1,000 to 2,000 Blaine (cm ² /g).

If the CaO content in the circulating fluidized bed boiler coal ash and lime is less than 30% by weight, the optimum effect cannot be obtained due to the low amount of gypsum produced, and the CaO content is preferably 40% by weight or more.

If the fineness of circulating fluidized bed boiler coal ash and lime is less than 1,000 Blaine (cm ² /g), the gypsum formation reaction is weakened because the particles are large, and if it exceeds 2,000 Blaine, it is economically undesirable. Preferably, the powder degree is 1,200 to 1,800 blades.

In the present invention, the circulating fluidized bed boiler fly ash and lime may be used alone or in combination of two or more.

100 to 600 parts by weight of water is mixed and used, preferably 150 to 450 parts by weight, based on 100 parts by weight of CaO contained in coal ash and lime in a circulating fluidized bed boiler. If less than 100 parts by weight of water is used, there is a problem in that slaked lime may be produced by rapid hydration reaction, so the production of gypsum is hindered. there is

In this step, mixing is preferably performed at 200 to 300 rpm for 3 to 10 minutes.

Step iv): Gypsum Formation Reaction

With respect to 100 parts by weight of the mixture of step ii), 80 to 150 parts by weight of the mixture of step iii) was added while stirring at a rotational speed of 300 rpm or more, and heated and mixed at 100 to 120 ° C. for 6 to 10 hours to form gypsum. do.

If the mixture of step iii) is less than 80 parts by weight relative to 100 parts by weight of the mixture of step ii), there is a disadvantage in that the amount of gypsum is reduced, and if it is more than 150 parts by weight, unreacted CaO remains and exists as an impurity for gypsum. There is a problem. Preferably, 110 to 140 parts by weight of the mixture of step iii) is mixed with 100 parts by weight of the mixture of step ii).

In this step, if the stirring speed is less than 300 rpm, a problem of weakening the reactivity of the surfactant may occur. In addition, it is necessary to stir for 6 to 10 hours for a complete gypsum formation reaction between sulfur in biosulfur and circulating fluidized bed boiler coal ash and/or CaO in lime. If the stirring time is less than 6 hours, the gypsum formation reaction is not complete. Precipitates of reactive sulfur or CaO may occur. Stirring for more than 10 hours is economically undesirable. It is good to stir preferably for 7 to 9 hours.

Step v): Firing

While heating the mixture in step iv) at a heating rate of 5 to 10 °C/min, the temperature is increased to 300 to 500 °C and calcined for 30 to 90 minutes.

If the firing temperature is less than 300 ° C., there is a disadvantage in that the amount of gypsum produced is reduced, and if it exceeds 500 ° C., it is economically undesirable. Preferably, the firing temperature is 350 to 450 °C.

If necessary, before firing, the mixture of step iv) may be dried in a dryer at 105±10° C. for 12 hours. When the drying step is performed in this way, it is possible to prevent the life of the heating element from being weakened due to rapid evaporation of moisture in the firing furnace during the firing process.

The manufacturing method according to the present invention is environmentally friendly and economical, and the produced gypsum is a high-quality gypsum containing 60% by weight or more of anhydrite (Figs. 2 and 3).

According to another object of the present invention, to provide gypsum containing a high content of anhydrite prepared by the above production method.

According to another object of the present invention, it provides a composition for gypsum board containing the gypsum.

According to another object of the present invention, an auxiliary material for grinding blast furnace slag containing the gypsum is provided. The auxiliary material according to the present invention may be used in about 2 to 3% of the weight of the blast furnace slag.

According to another object of the present invention, it provides an admixture for cement containing the gypsum. The admixture according to the present invention may be used in about 5 to 8% of the cement weight.

According to another object of the present invention, it provides a slag cement containing the gypsum.

According to another object of the present invention, it provides a concrete composition containing the slag cement.

The manufacturing method according to the present invention makes it possible to manufacture gypsum containing a high content of anhydrite in an environmentally friendly manner.

Since the gypsum produced by the manufacturing method of the present invention has a high anhydrite content and uses biosulfur, it does not contain environmental pollutants such as heavy metal ions, so gypsum for gypsum board, auxiliary material for blast furnace slag grinding, admixture for cement, It can be used as gypsum for slag cement.

In addition, the gypsum according to the present invention is a high-purity gypsum containing a high content of anhydrite, so it can be used in a small amount, so it has excellent economical additional effects, and it can replace natural gypsum, which has no resources in Korea, and has an import substitution effect.

1 is a photograph of gypsum prepared according to the present invention.

2 is an X-ray quantitative analysis result of the gypsum of Example 1.

3 is an X-ray quantitative analysis result of the gypsum of Example 2.

The present invention is explained in more detail by the following examples. These examples are intended to illustrate the present invention, and the scope of the present invention should not be limited thereto.

Preparation Example 1: Preparation of gypsum 1 using biosulfur

100 g of the sulfur component contained in 250 g of biosulfur (sulfur component 40%; Eco Bio Holdings Co., Ltd.) was stirred at 120 ° C. at 300 rpm for 6 hours to completely dissolve. Then, after adding 0.8 g of sodium lauryl sulfonate, an anionic surfactant, the mixture was stirred and mixed at 300 rpm for 3 minutes to prepare a biosulfur mixture.

As lime, 180 g of slaked lime (CaO 99 g) having a CaO content of 55% by weight and 450 g of water were mixed at 250 rpm for 5 minutes to prepare a mixed lime slurry.

While gradually adding 145 g of the lime mixed slurry to 100 g of the biosulfur mixture, the mixture was stirred at 120 ° C. at 300 rpm for 6 hours to cause a gypsum production reaction. After the reaction was completed, the mixture was dried in a dryer at 105 ° C for 12 hours, and then fired at 400 ° C for 60 minutes while raising the drying rate at a heating rate of 5 ° C / min to complete the production of gypsum. A photograph of Example 1) is shown in FIG. 1 .

Preparation Example 2: Preparation of gypsum 2 using biosulfur

Gypsum was prepared in the same manner as in Preparation Example 1 (Example 2), except that 80 g of the lime mixed slurry was used.

Test Example 1: Analysis of anhydrite content

For the gypsum of Examples 1 and 2 prepared in Preparation Examples 1 and 2, the content of components such as anhydrite was analyzed using an X-ray quantitative component analyzer (Rigaku, D/Max-2500V), and the results were analyzed, respectively. It is shown in Figures 2 and 3.

As shown in the drawings, the prepared gypsum has anhydrite (CaSO ₄ ) and dihydrate gypsum (CaSO _4· 2H ₂ O) as main components.

Specifically, as shown in FIGS. 2 and 3, in the case of the gypsum of Example 1 and Example 2 prepared according to the present invention, the content of anhydrite was high at 80.5% by weight and 67.7% by weight, respectively.

Claims (13)

1. A method for producing gypsum using biosulfur, the method comprising:

   i) heating bio-sulfur at 100 to 120° C. to dissolve contained sulfur;

   ii) mixing 0.5 to 20 parts by weight of an anionic surfactant based on 100 parts by weight of sulfur contained in biosulfur;

   iii) adding 100 to 600 parts by weight of water based on 100 parts by weight of CaO contained in circulating fluidized bed boiler coal ash or lime and mixing for 3 to 10 minutes;

   iv) based on 100 parts by weight of the mixture of step ii), adding 80 to 150 parts by weight of the mixture of step iii) while stirring at a rotational speed of 300 rpm or more, heating and mixing at 100 to 120 ° C. for 6 to 10 hours; and

   v) heating the mixture of step iv) at a heating rate of 5 to 10 °C/min to 300 to 500 °C and baking for 30 to 90 minutes.
2. The method of preparing gypsum using bio-sulfur according to claim 1, wherein the bio-sulfur contains 40% by weight or more of sulfur.
3. The method of preparing gypsum using biosulfur according to claim 1, wherein the anionic surfactant is at least one selected from the group consisting of sulfonic acid surfactants and sulfuric acid ester surfactants.
4. The biosulfur according to claim 1, wherein the circulating fluidized bed boiler coal ash and lime have a CaO content of 30% by weight or more and a powdery form of 1,000 to 2,000 Blaine (cm ² /g). Method for producing gypsum using
5. The method of claim 1, wherein the lime is at least one selected from the group consisting of limestone, slaked lime, quicklime, waste limestone, limestone sludge and slaked lime sludge.
6. The method of preparing gypsum using biosulfur according to claim 1, wherein the mixture of step iv) is dried in a dryer at 105 ± 10 ° C for 12 hours before firing.
7. Gypsum prepared according to any one of claims 1 to 6.
8. The gypsum according to claim 7, wherein the gypsum contains 60% by weight or more of anhydrite.
9. A composition for a gypsum board comprising the gypsum according to claim 7.
10. An auxiliary material for blast furnace slag grinding comprising the gypsum according to claim 7.
11. A cement admixture comprising the gypsum according to claim 7.
12. Slag cement comprising gypsum according to claim 7.
13. A concrete composition comprising the slag cement according to claim 12.

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