A method for preparing gypsum from detoxified fly ash and waste acid from a detergent factory.

Abstract

This application discloses a method for preparing gypsum from detoxified fly ash and waste acid from a detergent plant, relating to the technical field of co-treatment of fly ash and waste acid. The gypsum is composed of the following raw materials: basic process gypsum, water-reducing agent, pH dispersant, α-gypsum, water, and gypsum activator. In preparing the basic process gypsum, this application adds an antifoaming agent and combines it with high-temperature treatment to promote the decomposition of organic matter and achieve deodorization and defoaming, thereby improving the performance of the gypsum and ensuring its normal use. Simultaneously, through the synergistic effect of the water-reducing agent and pH dispersant, the pH dispersant promotes the dispersion of the water-reducing agent and adjusts the pH of the slurry, thereby further reducing water demand. Furthermore, the synergistic effect of adding α-gypsum and the activator further improves the strength of the finished building gypsum product.

Description

Technical Field

[0001] This application relates to the technical field of co-processing fly ash and waste acid, and in particular to a gypsum prepared from detoxified fly ash and waste acid from a detergent plant, and a method for preparing the same. Background Technology

[0002] Among related technologies, neutralization is one of the simplest and most effective methods for treating low-concentration waste sulfuric acid, requiring minimal investment and being easy to operate. Research on waste acid from detergent factories revealed a high content of sulfate ions, while incinerator fly ash contains a large amount of CaO. Both can be used as reactants to synthesize calcium sulfate. However, due to the high COD content in this type of waste acid, the resulting gypsum has an irritating odor, and gypsum produced using traditional methods generates a large number of bubbles when mixed with water, severely affecting its performance and normal use.

[0003] Therefore, there is an urgent need for a gypsum product that can meet the relevant standards of GB / T9776—2022 "Building Gypsum" by using fly ash from waste incineration and waste acid from detergent plants. Summary of the Invention

[0004] The purpose of this application is to provide a gypsum prepared from detoxified fly ash and waste acid from a detergent plant, and a method for preparing the same, in order to solve the problems in related technologies where the waste acid has a high COD content, resulting in gypsum with an irritating odor, and where gypsum prepared by traditional processes produces a large number of bubbles when mixed with water, which seriously affects the performance and normal use of the gypsum.

[0005] On the one hand, the gypsum prepared from detoxified fly ash and waste acid from a detergent plant, as provided in this application, adopts the following technical solution:

[0006] A gypsum prepared from detoxified fly ash and waste acid from a detergent factory, composed of the following raw materials:

[0007] Basic process: gypsum, water-reducing agent, pH dispersant, α-gypsum, water, and gypsum activator;

[0008] The above-mentioned amounts of raw materials are based on the measurement standard of basic process gypsum:

[0009] The amount of water-reducing agent used is 0.2% to 0.45% of the mass of the base process gypsum.

[0010] The amount of the pH dispersant added is 0.1% to 1.0% of the mass of the base process gypsum.

[0011] The amount of α-gypsum used is 30%-50% of the mass of the base process gypsum;

[0012] The amount of water added is 50%-70% of the mass of the base process gypsum.

[0013] The amount of the gypsum activator added is 1.0% to 3.0% of the mass of the base process gypsum.

[0014] Furthermore, the mass ratio of the above raw materials is as follows:

[0015] Basic process: gypsum : water-reducing agent : pH dispersant : α-gypsum : water : gypsum activator = 0.7 : 0.0029 : 0.005 : 0.3 : 0.45 : 0.02.

[0016] Furthermore, the basic process gypsum is composed of the following raw materials:

[0017] Fly ash, waste acid from detergent factories, water, and defoamers;

[0018] The amount of fly ash added is 40g to 60g;

[0019] The amount of waste acid added from the detergent factory is 50g~70g;

[0020] The amount of water added is 180g~200g;

[0021] The amount of defoamer added is 0.10% of the mixture obtained by mixing the fly ash, the waste acid from the detergent factory, and the water.

[0022] Furthermore, the basic process gypsum is composed of the following raw materials:

[0023] The amount of fly ash added is 50g;

[0024] The amount of waste acid added from the detergent factory is 60g;

[0025] The amount of water added is 190g;

[0026] The amount of defoamer added is 0.10% of the mixture obtained by mixing the fly ash, the waste acid from the detergent factory, and the water.

[0027] Furthermore, it also includes the process of preparing the basic process plaster:

[0028] S1. Fly ash ball milling: First, the fly ash is ground using a ball milling process, and the grinding time is not less than 40 minutes.

[0029] S2. Stirring and defoaming: The fly ash and detergent waste acid after grinding in step S1 are mixed to obtain a mixture. Water is added to the mixture to make up the volume, and then defoamer is added. The mixture is stirred with stirring blades to obtain a mixed slurry. Finally, the mixed slurry is allowed to react and stand.

[0030] S3. Filtration: The mixed slurry in step S2 is extracted into a filter press for plate and frame filtration. After filtration, clean water is continuously pumped into the plate and frame until the pH of the effluent after filtration is neutral, so as to obtain gypsum.

[0031] S4. High-temperature deodorization and aging revival of gypsum: The gypsum obtained in step S3 is dried at high temperature to remove odors, and then the high-temperature dried gypsum is aged to obtain basic process gypsum.

[0032] Further, in step S2, water is added to the mixture to bring the volume to 300 ml, and then an antifoaming agent is added;

[0033] The stirring time using stirring blades is 10-60 minutes, and the stirring speed is not less than 30-360 r / min;

[0034] Furthermore, the reaction settling time of the mixed slurry should not be less than 1-48 hours.

[0035] Furthermore, in step S3, the filter cloth used in the plate and frame filter press process has a pore size of 10 micrometers.

[0036] Furthermore, in step S4, the gypsum is dried at high temperature for no less than 3 hours, and the drying temperature is 300°C; at the same time, the aging time is 48-72 hours.

[0037] Furthermore, the gypsum is composed of the following raw materials added in amounts based on the measurement of basic process gypsum:

[0038] The amount of water-reducing agent used is 0.275% of the mass of the base process gypsum.

[0039] The amount of pH dispersant added is 0.5% of the mass of the base process gypsum;

[0040] The amount of α-gypsum used is 40% of the mass of the base process gypsum;

[0041] The amount of water added is 60% of the mass of the base process gypsum.

[0042] The amount of gypsum activator added is 2.0% of the mass of the base process gypsum.

[0043] On the other hand, the method for preparing gypsum from detoxified fly ash and waste acid from a detergent plant provided in this application adopts the following technical solution:

[0044] A method for preparing gypsum from detoxified fly ash and waste acid from a detergent plant involves weighing the basic process gypsum, the water-reducing agent, the pH dispersant, the α-gypsum, and the gypsum activator, and adding water to mix them evenly.

[0045] Compared with the prior art, the beneficial effects of this application are as follows:

[0046] This application's method, during the preparation of basic process gypsum, promotes the decomposition of organic matter and achieves deodorization and defoaming by adding an antifoaming agent and combining it with high-temperature treatment, thereby improving the performance of the gypsum and ensuring its normal use. Simultaneously, through the synergistic effect of adding a water-reducing agent and a pH dispersant, the pH dispersant promotes the dispersion of the water-reducing agent and adjusts the pH of the slurry, thereby further reducing water demand. Furthermore, the synergistic effect of adding α-gypsum and an activator further enhances the strength of the finished building gypsum product. Attached Figure Description

[0047] Figure 1 This is the XRD pattern of the plaster gypsum used in the basic process of this application embodiment.

[0048] Figure 2 This is a super-depth-of-field photograph with a magnification of 50x, as described in this application embodiment.

[0049] Figure 3 These are SEM images of the basic process plaster in the embodiments of this application. Among them, (a) is an SEM image with a magnification of 5000x and (b) is an SEM image with a magnification of 8000x. Detailed Implementation

[0050] The following is in conjunction with the appendix Figure 1-3 This application will be described in further detail.

[0051] On the one hand, this application discloses a gypsum prepared from detoxified fly ash and waste acid from a detergent factory. In this embodiment, the gypsum is composed of the following raw materials: basic process gypsum, water-reducing agent, pH dispersant, α-gypsum, water, and gypsum activator.

[0052] The above-mentioned amounts of raw materials are based on the measurement standard of basic process gypsum:

[0053] The dosage of water-reducing agent is 0.2% to 0.45% of the mass of the base process gypsum.

[0054] The amount of pH dispersant added is 0.1% to 1.0% of the mass of the base process gypsum.

[0055] The amount of α-gypsum used is 30%-50% of the mass of the base process gypsum;

[0056] The amount of water added is 50%-70% of the mass of the base process gypsum.

[0057] The amount of gypsum activator added is 1.0% to 3.0% of the mass of the base process gypsum.

[0058] Specifically, adding water-reducing agents can significantly reduce water demand, thereby noticeably improving gypsum performance. Furthermore, by simultaneously adding water-reducing agents and pH-adjusting dispersants to basic process gypsum, the pH dispersant promotes the dispersion of the water-reducing agent and adjusts the pH of the slurry, further reducing water demand. Additionally, adding gypsum activators can effectively increase gypsum strength while shortening setting time. Moreover, the synergistic effect of adding α-gypsum and gypsum activators can further enhance the strength of finished building gypsum products.

[0059] On the other hand, the method for preparing gypsum from detoxified fly ash and waste acid from a detergent plant provided in this application adopts the following technical solution:

[0060] In this embodiment, the gypsum is composed of the following raw materials added in amounts based on the basic process gypsum:

[0061] The amount of water-reducing agent used is 0.275% of the mass of the base process gypsum.

[0062] The amount of pH dispersant added is 0.5% of the mass of the base process gypsum.

[0063] The amount of α-gypsum used is 40% of the mass of the base process gypsum;

[0064] The amount of water added is 60% of the mass of the base process gypsum.

[0065] The amount of gypsum activator added is 2.0% of the mass of the gypsum in the basic process.

[0066] In this preparation method, the basic process gypsum, water-reducing agent, pH dispersant, α-gypsum and gypsum activator are weighed according to the mass percentage values, and water is added and stirred evenly to prepare a finished building gypsum product that meets the relevant standards of GB / T9776—2022 "Building Gypsum".

[0067] More specifically, in this embodiment, the basic process gypsum is composed of the following raw materials: fly ash, waste acid from a detergent factory, water, and defoamer;

[0068] The amount of fly ash added is 40g~60g;

[0069] The amount of waste acid added by the detergent factory is 50g~70g;

[0070] The amount of water added is 180g~200g;

[0071] The amount of defoamer added is 0.01% to 0.10% of the mixture obtained by mixing fly ash, waste acid from detergent plants and water.

[0072] In addition, this embodiment also includes a process for preparing basic process gypsum, which includes the following steps:

[0073] S1. Fly ash ball milling: First, the fly ash is ground using a ball milling process, and the grinding time is not less than 40 minutes.

[0074] S2. Stirring and Defoaming: The fly ash and waste acid from the detergent plant, processed in step S1, are mixed to obtain a mixture. Water is then added to the mixture to a final volume of 300 ml, followed by the addition of a defoamer. The mixture is then stirred using a stirring blade to obtain a slurry. Finally, the slurry is allowed to stand for reaction. Specifically, in step S2, the stirring time using the stirring blade is 10-60 min, preferably 40 min, and the stirring speed is not less than 30-360 r / min, preferably 240 r / min. The standing time for the slurry is not less than 1-48 h, preferably 12 h.

[0075] S3. Filtration: The mixed slurry from step S2 is extracted into a filter press for plate and frame filtration. After filtration, clean water is continuously pumped into the plate and frame until the pH of the effluent is neutral, thus obtaining gypsum. Specifically, in step S3, the filter cloth used in the plate and frame filtration process has a pore size of 10 micrometers, which improves the filtration accuracy and achieves a better filtration effect.

[0076] S4. High-temperature deodorization and aging of gypsum: The gypsum obtained in step S3 is dried at high temperature to remove odors, and then aged to obtain basic process gypsum. Specifically, in step S4, the gypsum is dried at high temperature for no less than 3 hours, and the drying temperature is 280-400℃, preferably 300℃; at the same time, the aging time is 12-72 hours, preferably no less than 48 hours.

[0077] The large amount of surfactants in the waste acid from detergent factories significantly impacts the mixing process. This is primarily manifested in the instantaneous generation of numerous bubbles when the waste acid is mixed with fly ash, causing the liquid to overflow the container. The reason for this phenomenon is that the reaction between the waste acid and carbonates in the fly ash produces a large amount of gas, which the surfactants in the waste acid retain in the system, generating numerous persistent bubbles. As the reaction continues, the number of bubbles accumulates until they eventually overflow the container. Therefore, the solution proposed in this application, by adding a defoamer and combining it with high-temperature treatment during the preparation of basic process gypsum, can promote the decomposition of organic matter and achieve the purpose of deodorization and defoaming, thereby improving the performance of the gypsum and ensuring its normal use.

[0078] The raw materials involved in this application are listed below:

[0079] (1) Fly ash: This fly ash is obtained from the incineration and detoxification of municipal solid waste, and the main mineral components of fly ash include: calcium sulfate, calcium carbonate, calcium hydroxide and silicon dioxide. Among the above mineral phases, calcium sulfate, calcium carbonate and calcium hydroxide are all effective components of synthetic gypsum.

[0080] Referring to Table 1 below, chemical composition analysis and comparison of fly ash from different sampling points and at different sampling times show that the calcium oxide content of fly ash remains relatively stable between 48% and 51%. This stable data is the foundation and guarantee of this project.

[0081]

[0082] Waste acid from detergent factories: Some indicators of the components contained in waste acid from detergent factories. See Table 2 below for specific data.

[0083]

[0084] The above table shows that the waste acid from detergent factories also has a high sulfate content, indicating sufficient reactants for calcium sulfate synthesis. However, this type of waste acid has a high COD content, primarily derived from surfactants. These substances not only affect gypsum synthesis but also significantly impact the performance of the prepared gypsum products.

[0085] Meanwhile, the amount of defoamer added was 0%, 0.02%, 0.04%, 0.06%, 0.08%, and 0.10% of the total mass of the slurry, as shown in Table 3. It was found that the material would not overflow only when the amount of defoamer added was greater than 0.08%.

[0086]

[0087] Therefore, this basic process gypsum is composed of the following raw materials:

[0088] The amount of fly ash added is 50g;

[0089] The amount of waste acid added by the detergent factory is 60g;

[0090] The amount of water added is 190g;

[0091] The amount of defoamer added is 0.10% of the mixture obtained by mixing fly ash, waste acid from the detergent factory, and water.

[0092] By using the aforementioned raw materials and components, and the basic process gypsum prepared using the aforementioned preparation process, the problem of high COD content in such waste acid, mainly from surfactants, can be solved. These substances not only affect the synthesis of gypsum but also have a significant impact on the performance of the prepared gypsum products.

[0093] The following is an investigation into the effects of high-temperature deodorization and aging / reactivation on gypsum:

[0094] The gypsum produced by pressing and filtering waste acid from a detergent factory has an irritating odor, and the gypsum made by traditional firing processes produces a large number of bubbles when mixed with water, which seriously affects the performance and normal use of the gypsum.

[0095] The gypsum produced from waste acid in detergent factories has a pungent odor, and after washing and low-temperature firing, the gypsum is further diluted with water, resulting in a large number of bubbles in the slurry. To remove the odor and eliminate the foam, the gypsum needs to be treated at high temperatures.

[0096] While high temperatures can facilitate the decomposition of organic matter in gypsum during high-temperature treatment, thus achieving deodorization and defoaming, excessively high temperatures can also convert most of the dihydrate calcium sulfate in the gypsum into insoluble anhydrous calcium sulfate. Once the gypsum has undergone high-temperature calcination and transformed into insoluble anhydrous gypsum, its strength will significantly decrease and cannot be restored. Therefore, finding the balance between these two factors is crucial; that is, finding the minimum temperature at which the gypsum can effectively deodorize and defoam.

[0097] Considering that the decomposition temperature of most organic compounds is concentrated between 300℃ and 500℃, and taking into account the principle of prioritizing lower temperatures, the proposed high-temperature treatment temperatures are 280℃, 300℃, 320℃, 340℃, 360℃, 380℃, and 400℃. Since high-temperature treatment time and drying temperature are correlated, i.e., the higher the temperature, the shorter the drying time.

[0098] The optimal drying time was determined by controlling the drying time until the material reached a constant weight under different temperature conditions. Specific experimental results are shown in Table 4-1.

[0099]

[0100] Furthermore, water was added to and stirred the gypsum dried to constant weight at different temperatures to observe whether a large number of bubbles were still generated and to determine whether there was an irritating odor. The specific deodorization and defoaming effects are shown in Table 4-2 below:

[0101]

[0102] As shown in Table 4-2, deodorization and defoaming of gypsum can be achieved when the temperature reaches 300℃. Combined with Table 4-1, it can be seen that constant weight can be achieved by drying at 300℃ for 4 hours. Therefore, the optimal parameters for this process are: high-temperature treatment temperature of 300℃ and drying time of 4 hours.

[0103] Due to the excessively high drying temperature, there is a possibility that a large amount of dihydrate gypsum may be converted into insoluble anhydrous gypsum. Therefore, gypsum dried at 300℃ for 3 hours needs to undergo a reactivation and aging process. The resulting gypsum material will still contain a large amount of soluble anhydrous gypsum, which can absorb moisture from the air and transform into β-type hemihydrate gypsum.

[0104] The initial aging times were determined to be 12h, 24h, 36h, 48h, and 72h. The three-phase data of the gypsum after aging are shown in Table 4-3 below:

[0105]

[0106] As shown in Table 4-3 above, after treatment at 300℃, most of the gypsum is soluble anhydrous gypsum, which gradually transforms into hemihydrate gypsum. When the aging time is 48 hours, most of the soluble anhydrous gypsum transforms into hemihydrate gypsum. At the same time, the amount of dihydrate phase also gradually increases.

[0107] To investigate the effect of different drying temperatures on the three phases of gypsum, a process was adopted with a high-temperature drying time of 3 hours and an aging time of 48 hours. The high-temperature drying temperatures were controlled at 280℃, 300℃, 320℃, 340℃, 360℃, 380℃, and 400℃ to treat the gypsum. The results of the gypsum three-phase analysis are shown in Table 4-4 below.

[0108]

[0109] As shown in Table 4-4, the hemihydrate phase of the aged gypsum decreases continuously with increasing drying temperature. When the temperature rises from 280℃ to 400℃, the hemihydrate phase of the gypsum decreases from 78.31% to 0.26%. This means that when the treatment temperature reaches 400℃, most of the dihydrate gypsum is converted into insoluble anhydrous gypsum, indicating that the gypsum cannot be reactivated through aging.

[0110] The roasting and aging process used in this study is as follows: high-temperature drying time of not less than 3 hours, drying temperature of 300℃, and aging time of not less than 48 hours.

[0111] The following section describes the performance testing of basic process gypsum under optimal process conditions:

[0112] The optimal reaction parameters are summarized in Table 5-1 below:

[0113]

[0114] The physical properties of the gypsum prepared according to the above process are shown in Table 5-2:

[0115]

[0116] Note: The test method refers to GB / T9776—2022. Due to the limited number of samples, the size of the test block is 30mm cube when conducting the compressive strength test.

[0117] (1) The gypsum prepared by the basic process was subjected to full elemental chemical analysis using X-ray fluorescence spectrometry (XRF). The results are shown in Table 5-3:

[0118]

[0119] Note: Hydrogen and carbon are not included in the elemental analysis.

[0120] Reference Figure 1 The mineral phases of the prepared gypsum were analyzed using X-ray diffraction (XRD). Figure 1 This is the XRD pattern of the basic process gypsum.

[0121] Analysis of the XRD results showed that the hemihydrate gypsum had the highest strength among the tested samples. Furthermore, the characteristic peaks of soluble anhydrous gypsum were also quite prominent. The mineral phase is very similar to that of gypsum prepared from waste acid from electronics factories.

[0122] (3) Reference Figure 2 The morphology of the prepared plaster was analyzed using a super depth-of-field 3D display system. Figure 2 This is a super depth-of-field photo magnified 50 times.

[0123] from Figure 2 As can be seen from the super depth-of-field image, the gypsum prepared using waste acid from a detergent factory exhibits significant agglomeration, with agglomerated particles measuring approximately several hundred micrometers.

[0124] (4) Reference Figure 3 The microstructure of the prepared gypsum was analyzed using scanning electron microscopy (SEM). Figure 3 The left image is a SEM image of basic plasterwork at 5000x magnification, and the right image is a SEM image of basic plasterwork at 8000x magnification.

[0125] from Figure 3 The SEM images clearly show that the gypsum produced from the waste acid from the detergent factory also contains a large number of needle-like and fibrous crystals interspersed throughout, along with some flaky crystals. The surface is coated with fine particulate matter. These encapsulated impurities may potentially affect the strength and setting time of the gypsum.

[0126] The gypsum prepared from waste acid from a detergent factory exhibits typical characteristics of β-type hemihydrate gypsum crystals. The more needle-like and fibrous structures present, the better the crystallization effect; conversely, the more platy structures, the worse the crystallization effect. Based on this, the gypsum prepared by the basic process has a acceptable crystallization effect. However, due to the presence of impurities in the waste acid and fly ash, the surface of the prepared gypsum is inevitably coated with impurities, and some of the gypsum crystallizes into a platy structure.

[0127] The following is a study on the effect of additives on the properties of modified gypsum:

[0128] Optional additives can be added:

[0129] Water-reducing agent: The dosage is 0.2%~0.45% of the mass of the base process gypsum, which can significantly reduce water demand and significantly improve the performance of gypsum;

[0130] pH adjusting dispersant: The addition amount is 0.5% of the mass of the basic process gypsum. Adding both water-reducing agent and pH adjusting dispersant to the basic process gypsum can further reduce the water requirement of the gypsum.

[0131] Gypsum activator: The addition amount is 2.0% of the mass of the base process gypsum. Adding gypsum activator can effectively increase the strength of gypsum while shortening the setting time;

[0132] α-gypsum: α-gypsum that meets the requirements of JC / T2038-2010 standard; to achieve standard consistency of gypsum, the specific formulation is shown in Table 6-1 of the seventh batch of modified gypsum.

[0133]

[0134] The following are the performance tests conducted on the seventh batch of modified gypsum. The test results are shown in Table 6-2:

[0135]

[0136] Note: The test method refers to GB / T9776—2022. Due to the limited number of samples, the size of the test block is 30 mm cubic when conducting the compressive strength test.

[0137] Therefore, the optimal ratio of the above raw material mass ratios is: basic process gypsum ∶ water-reducing agent ∶ pH dispersant regulated agent ∶ α-gypsum ∶ water ∶ gypsum activator = 0.7 ∶ 0.0029 ∶ 0.005 ∶ 0.3 ∶ 0.45 ∶ 0.02.

[0138] As shown in Table 6-2, the strength of gypsum increases with the addition of α-gypsum, while the setting time decreases. Furthermore, the addition of α-gypsum also partially reduces water content; the higher the α-gypsum content, the lower the amount of water-reducing agent required to achieve the same consistency. Additionally, reducing the amount of water used for standard consistency can also significantly improve strength and shorten setting time.

[0139] Meanwhile, as can be seen from Table 6-2, by comparing Comparative Example 2 with Sample No. 7-1, it can be seen that after adding gypsum activator, the activator and α-gypsum work synergistically to further enhance the strength of gypsum and reduce setting time.

[0140] The comparison of examples 1-3 shows that the addition of water-reducing agents can significantly reduce the water demand of gypsum. As the water demand decreases, the strength of the gypsum continuously increases. However, compared to ordinary building gypsum, the water demand is still relatively high.

[0141] A comparison of samples 7-4, 7-8, and 7-12 shows that as the amount of water-reducing agent increases, the setting time of gypsum decreases.

[0142] Therefore, by adding a small amount of pH-adjusting dispersant, the water-reducing agent is dispersed and the pH of the slurry is adjusted, thereby further reducing the water requirement. A comparison of the sample numbers shows that the water-reducing effect is significantly improved when the amount of water-reducing agent increases. With further reduction in water content, the gypsum strength increases markedly.

[0143] Sample number 7-12 was subjected to full testing as required by the national standard GB / T9776—2022 "Building Gypsum", and radioactivity testing was conducted in accordance with the national standard GB6566—2010 "Limits of Radionuclides in Building Materials". The specific test results, testing basis, standard values, and sample standard compliance are shown in Table 6-3 below:

[0144]

[0145] In conclusion, the following conclusions can be drawn:

[0146] (1) The building gypsum prepared using the basic process has a high calcium sulfate content, but the gypsum made from the waste acid of the detergent factory after high-temperature treatment has insufficient activity, high water demand, low strength and slow setting time.

[0147] (2) Adding water-reducing agent to basic process gypsum, the amount of which is 0.2% to 0.45% of the mass of basic process gypsum can significantly reduce water demand and significantly improve gypsum performance, but still cannot meet the standard requirements.

[0148] (3) Adding both water-reducing agent and pH-adjusting dispersant to the basic process gypsum can further reduce the water demand of the gypsum. The amount of pH-adjusting dispersant added should be 0.5% of the mass of the basic process gypsum.

[0149] (4) Adding gypsum activator to the modified gypsum with water-reducing agent and pH-adjusting dispersant can effectively increase the strength of gypsum while shortening the setting time. The addition amount should be 2.0%.

[0150] (5) Adding α-gypsum and reducing water demand can effectively improve the strength of gypsum and shorten the setting time. Under the synergistic effect of the two, building gypsum that meets the standard requirements can be prepared.

[0151] (6) After modification, the prepared gypsum meets the requirements of the national standard. Its optimal ratio is: basic process gypsum: water reducing agent: pH dispersant: α gypsum: water: gypsum activator = 0.7: 0.0029: 0.005: 0.3: 0.45: 0.02 (mass ratio).

[0152] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A gypsum made from detoxified fly ash and waste acid from a detergent plant, characterized in that, consists of: The basic process gypsum, water reducing agent, pH dispersion regulator, alpha gypsum, water and gypsum activator; The addition amount of the above raw materials is based on the basic process gypsum as the measurement reference: The amount of the water reducing agent is 0.2%-0.45% of the mass of the basic process gypsum; The addition amount of the pH dispersion regulator is 0.1%-1.0% of the mass of the basic process gypsum; The amount of the alpha gypsum is 30%-50% of the mass of the basic process gypsum; The addition amount of the water is 50%-70% of the mass of the basic process gypsum; The addition amount of the gypsum activator is 1.0%-3.0% of the mass of the basic process gypsum; The basic process gypsum consists of: Fly ash, dishwashing detergent factory waste acid, water and defoaming agent; Among them, the addition amount of the fly ash is 40g-60g; The addition amount of the dishwashing detergent factory waste acid is 50g-70g; The addition amount of the water is 180g-200g; The addition amount of the defoaming agent is 0.10% of the mass of the mixture obtained after the fly ash, the dishwashing detergent factory waste acid and the water are mixed with each other; It also includes the process of preparing the basic process gypsum: S1, fly ash ball milling: first, the fly ash is ground by ball milling process, and the grinding time is not less than 40min; S2, stirring and defoaming: then the fly ash, dishwashing detergent factory waste acid after grinding treatment in step S1 are mixed to obtain a mixture, then water is added to the mixture to constant volume, defoaming agent is added, and mixing and stirring are carried out by stirring blade to obtain a mixed slurry, finally the mixed slurry is reacted and placed; S3, filtration: the mixed slurry in step S2 is extracted into a plate and frame filter press for plate and frame filter pressing process treatment, and after being filtered clean, clean water is continuously pumped into the plate and frame until the pH of the water after filtration is neutral, to obtain gypsum; S4, high temperature odor removal and aging of gypsum: the gypsum obtained in step S3 is high temperature dried to remove odor, and finally the high temperature dried gypsum is aged to obtain the basic process gypsum; in step S4, the high temperature drying time of the gypsum is not less than 3h, and the drying temperature is 300℃; at the same time, the aging time is 48-72h.

2. The gypsum of claim 1, wherein, The mass ratio of the above raw materials is: Basic process gypsum: water reducing agent: pH dispersion regulator: alpha gypsum: water: gypsum activator = 0.7: 0.0029: 0.005: 0.3: 0.45: 0.

02.

3. The gypsum prepared from detoxified fly ash and waste acid from a detergent factory according to claim 1, characterized in that, The basic process gypsum consists of: The addition amount of the fly ash is 50g; The addition amount of the dishwashing detergent factory waste acid is 60g; The addition amount of the water is 190g; The addition amount of the defoaming agent is 0.10% of the mass of the mixture obtained after the fly ash, the dishwashing detergent factory waste acid and the water are mixed with each other.

4. The gypsum of claim 1, wherein the fly ash is detoxified fly ash, and the waste acid is waste acid from a detergent factory. In step S2, after adding water to constant volume to 300ml, defoaming agent is added; ​ The stirring time by stirring blade is 10-60min, the stirring rate is 30-360r / min; and the reaction and standing time of the mixed slurry is 1-48h.

5. The gypsum of claim 1, wherein the fly ash is detoxified fly ash, and the waste acid is waste acid from a detergent factory. In step S3, the filter cloth aperture used in the plate and frame filter pressing process treatment is 10 microns. ​ 6. The gypsum of claim 1, wherein the fly ash is detoxified fly ash, and the waste acid is waste acid from a detergent factory. The gypsum is composed of the following components, with the addition amount of each component being based on the base process gypsum as the measurement reference: ​ The amount of the water reducing agent is 0.275% of the mass of the base process gypsum; The addition amount of the pH dispersion regulator is 0.5% of the mass of the base process gypsum; The amount of the α gypsum is 40% of the mass of the base process gypsum; The addition amount of the water is 60% of the mass of the base process gypsum; The addition amount of the gypsum activator is 2.0% of the mass of the base process gypsum.

7. A process for the preparation of gypsum from a detoxified fly ash and a synergistic detergent plant waste acid according to any one of claims 1 to 6, characterized in that, The base process gypsum, the water reducing agent, the pH dispersion regulator, the α gypsum, and the gypsum activator are weighed respectively, and water is added for stirring and mixing until uniform.

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