Gypsum slurry and gypsum board

Abstract

The invention discloses a gypsum slurry which comprises a dry material component and water, the dry material component comprises gypsum, starch, an additive and water, the water comprises waste water, and the content of the waste water is at least 30% of the total weight of the water. The invention further discloses a gypsum board which comprises upper surface protection paper, a board core and lower surface protection paper, and the board core is made of the gypsum slurry. According to the technical scheme, the gypsum board can be produced by using wastewater, and the performance of the gypsum board is equivalent to that of a traditional gypsum board produced by using tap water, so that water can be saved, and environmental protection and emission reduction are realized.

Description

Technical Field

[0001] The present invention relates to gypsum board production, and more particularly to gypsum slurry using wastewater and gypsum board produced therefrom. Background Art

[0002] Gypsum board is a lightweight building material widely used in construction and interior decoration. It is made of gypsum (the main component is calcium sulfate dihydrate) as the core material, and paper or other materials are wrapped on the outside to form a strong and easy-to-process board. Gypsum board has good fire resistance, sound insulation and moisture resistance, so it has been widely used in modern buildings.

[0003] In the production of gypsum board, raw materials need to be mixed with water to form slurry. The raw materials include calcined gypsum powder, starch, fiber and additives. The slurry is spread on the lower face paper through the slurry discharge equipment, and the upper face paper is laid on the slurry. After the slurry is initially set, it is cut and dried to obtain the finished gypsum board.

[0004] The water used in gypsum board production is usually tap water, that is, water that meets the national domestic water standards, such as the "National Drinking Water Standard" (GB 5749-2006). Summary of the invention

[0005] The purpose of the present invention is to use waste water to at least partially replace tap water in the production process of gypsum boards, so as to save water and achieve environmental protection and emission reduction.

[0006] To this end, according to one aspect of the present invention, a gypsum slurry comprises dry components and water, wherein the dry components include gypsum, starch, additives and water, wherein the water contains waste water, and the content of the waste water is at least 30% of the total weight of the water.

[0007] Wherein, the additive comprises sodium trimetaphosphate in an amount of up to 0.5% based on the weight of the gypsum.

[0008] Wherein, the additive comprises a bacteriostatic agent in an amount of at most 0.5% based on the weight of the gypsum.

[0009] The total weight of the water is 50%-75% based on the total weight of the dry material.

[0010] Wherein, the dry material component further includes organic fiber, inorganic fiber or a combination thereof.

[0011] Wherein, the additives include accelerators, retarders, rheological agents, foaming agents or any combination thereof.

[0012] Wherein, the wastewater is at least one of preliminarily treated domestic sewage and power plant wastewater.

[0013] According to another aspect of the present invention, a gypsum board comprises an upper facing paper, a board core and a lower facing paper, wherein the board core is made of the aforementioned gypsum slurry.

[0014] Wherein, the density of the board core is 0.045-0.067 kilograms per cubic meter.

[0015] The technical solution of the present invention enables waste water to be used to produce gypsum boards, the performance of which is comparable to that of gypsum boards traditionally produced using tap water, thereby saving water and achieving environmental protection and emission reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Graphs showing sag deformation of the test examples and reference examples according to the present invention.

[0017] Figure 2a and 2b 2 are cross-sectional views of the cores of the test examples and the reference examples according to the present invention. DETAILED DESCRIPTION

[0018] According to a specific embodiment of the present invention, a gypsum slurry includes dry material components and water, wherein the total weight of the water is 50%-75% of the total weight of the dry material.

[0019] Wherein, the dry material components include gypsum, starch, fiber and additives. Gypsum can be any one or any combination of anhydrous gypsum, hemihydrate gypsum and dihydrate gypsum. In a specific example, the gypsum is calcined desulfurized gypsum. Starch is a starch that can be obtained through commercial channels and is suitable for making gypsum boards, and also includes pretreated starch, such as pregelatinized starch and modified starch. Fiber can be one of organic fibers and inorganic fibers or a combination thereof, such as polypropylene fibers and glass fibers. Additives can include any one or any combination of accelerators, retarders, rheological agents, and foaming agents, which are preparations suitable for gypsum boards that can be obtained through commercial channels. The additives also include sodium trimetaphosphate, whose content is less than or equal to 0.5% of the weight of gypsum, that is, at most 0.5%. The role of sodium trimetaphosphate is to improve the anti-sagging performance of the finished gypsum board. The addition also includes an antibacterial agent, whose content is also at most 0.5% of the weight of gypsum. In one example, the antibacterial agent can be sodium pyrithione. The function of the antimicrobial agent is to prevent the growth of fungi on the surface of the gypsum board.

[0020] The water includes wastewater, the content of wastewater is at least 30% of the total weight of the water, and the rest is tap water, that is, water that meets the national domestic water standards. The wastewater can be preliminarily treated domestic sewage or treated water from a power plant, or a mixture thereof.

[0021] According to another embodiment of the present invention, a gypsum board comprises a lower face paper, a board core and an upper face paper, wherein the board core is made of the aforementioned gypsum slurry. In one embodiment, the gypsum board having a board core density of 0.045-0.067 kg / m3 is made by the above slurry.

[0022] In the following comparative test, two groups of four gypsum board test samples were prepared.

[0023] The first group of samples is Reference Example 1 and Test Example 1, which are based on the same dry powder combination, wherein the content of sodium trimetaphosphate is 0%. Tap water is used to make gypsum board as Reference Example 1, and wastewater is used to make gypsum board as Test Example 1.

[0024] The second group of samples is Reference Example 2 and Test Example 2, and the difference between the dry powder combination of the first group of samples is only that the content of sodium trimetaphosphate is 0.1%. Similar to the first group of samples, tap water is used to make gypsum board as Reference Example 2, and wastewater is used to make gypsum board as Test Example 2.

[0025] The thickness of the obtained gypsum board is 9.5 mm and the weight is 5-7 kg per square meter.

[0026] The wastewater specifications used in Test Examples 1 and 2 are shown in Table 1.

[0027] Table 1

[0028] index Sampling Data CODcr (Potassium dichromate oxygen demand) 7mg / L <![CDATA[BOD5 (5-day Biochemical Oxygen Demand)]]> 1.6mg / L <![CDATA[NH3-N (Ammonia nitrogen content)]]> 0.109mg / L SS (suspended solids concentration) <4mg / L TP (Total Phosphorus) 15.5mg / L

[0029] Figure 1 The comparison of the anti-sagging performance of the reference example and the test example is shown. In this test, the gypsum board sample is made into a long strip, for example, 30 cm long and 5 cm wide.

[0030] The test method is as follows: Place the sample surface horizontally, that is, the surface of the face paper is horizontal; support the two ends of the sample in the length direction and let the middle of the sample hang in the air; let it stand for 24 hours, and measure the vertical deformation of the gypsum board in millimeters. The smaller the deformation, the better the anti-sagging performance of the gypsum board.

[0031] It can be seen that without using sodium trimetaphosphate, the sagging deformation of Test Example 1 is significantly greater than that of Reference Example 1; while the 24-hour sagging deformation of Reference Example 2 and Test Example 2 with 0.1% sodium trimetaphosphate added are comparable.

[0032] Table 2 is the color difference LAB test results of Reference Example 2 and Test Example 2.

[0033] Table 2

[0034] L(Brightness) a*(red / green) b*(blue / yellow) Reference example 2 95.42±0.1525 0.83±0.0243 4.10±0.1620 Test Example 2 95.96±0.1646 0.77±0.0127 4.01±0.0861

[0035] It can be seen that the color of the gypsum board made using wastewater is comparable to that of ordinary gypsum board.

[0036] Figure 2a is the cross-sectional view of the core of Reference Example 2. Figure 2b : is a cross-sectional view of the plate core of Test Example 2. The distribution of voids in the plate core of Test Example 2 using wastewater is not abnormal compared with that of Reference Example 2.

[0037] In addition, due to the presence of nitrogen and phosphorus in the wastewater, an antibacterial agent was added to prevent fungal growth on the surface of the gypsum board. Sodium pyrithione was added to the dry powder components of Test Examples 1 and 2 at a content of 0.05%. After one month of observation and testing, no fungal growth was found on the sample surface.

[0038] In the above description, the details of the technical solution of the present application are explained. However, those skilled in the art will appreciate that the present application is not limited to the specific details listed in the above embodiments, but may vary within the scope defined by the claims.

Claims

1. A gypsum slurry comprising dry material components and water, wherein the dry material components include gypsum, starch, fiber, additives and water, wherein: The water comprises waste water, and the content of the waste water is at least 30% of the total weight of the water.

2. The gypsum slurry according to claim 1, wherein The additive includes sodium trimetaphosphate in an amount up to 0.5% based on the weight of the gypsum.

3. The gypsum slurry according to claim 1, wherein The additives include a bacteriostat in an amount of up to 0.5% based on the weight of the gypsum.

4. The gypsum slurry according to claim 1, wherein The total weight of the water is 50%-75% based on the total weight of the dry materials.

5. The gypsum slurry according to claim 1, wherein The dry material component further includes organic fiber, inorganic fiber or a combination thereof.

6. The gypsum slurry according to claim 1, wherein The additives include any one of a coagulant, a retarder, a rheological agent, and a foaming agent, or any combination thereof.

7. The gypsum slurry according to claim 1, wherein The wastewater is at least one of preliminarily treated domestic sewage and power plant wastewater.

8. A gypsum board comprising an upper face paper, a board core and a lower face paper, wherein: The board core is made of the gypsum slurry according to any one of claims 1-7.

9. The gypsum board according to claim 8, wherein The density of the board core is 0.045-0.067 kilograms per cubic meter.

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