Crystal transformation centrifugal detoxification method for gypsum solid waste at low temperature
By using transcrystalline detoxifier and centrifugal sorting technology at room temperature and pressure, the problems of unenvironmental and high energy consumption of gypsum solid waste treatment are solved, and efficient detoxification of gypsum solid waste and the production of anhydrous gypsum are achieved, which improves treatment efficiency and economic benefits.
Patent Information
- Application Number
- CN202510343391.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-21
- Publication Date
- 2025-06-20
AI Technical Summary
In the prior art, the treatment method of gypsum solid waste is mainly concentrated in the application of the building materials industry, long-term stacking or direct landfill, resulting in large land resource occupation and potential environmental threats. The production path of anhydrous gypsum requires high temperature and high pressure, high equipment requirements, complex operation and large energy consumption.
The gypsum solid waste is transformed into crystal centrifugal detoxification method at low temperature. By configuring a transformed detoxification agent (including sulfuric acid, acid etchant and retarder), the gypsum solid waste is wet under normal temperature and pressure, and then left to dry and centrifugal sorting to achieve solid separation of toxic substances and anhydrous gypsum, and a modified detoxified anhydrous gypsum is obtained.
This method can efficiently convert gypsum solid waste into anhydrous gypsum, eliminating repeated washing and dehydration processes, improving treatment efficiency, saving water and environmental protection, reducing treatment difficulty, and improving economic benefits.
Smart Images
Figure CN120172665A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of gypsum treatment, and in particular to a method for crystallizing and centrifuging gypsum solid waste at low temperature. Background Art
[0002] At present, desulfurized gypsum is an industrial solid waste with calcium sulfate dihydrate (CaSO4·2H2O) as the main component. It is usually produced as a by-product of desulfurized flue gas treatment, mainly from the flue gas desulfurization (FGD) technology used in steel plants and coal-fired power plants. In recent years, with the rapid development of my country's economy and the continuous growth of electricity and steel production, the output of desulfurized gypsum has also increased year by year.
[0003] At present, the treatment methods of desulfurized gypsum in my country are mainly concentrated in the application of building materials industry, long-term stacking or direct landfill. However, these treatment methods not only occupy a large amount of land resources, but also bring potential threats to the environment. Anhydrous gypsum can replace gypsum and be crushed for soil treatment. In the soil treatment process, one ton of anhydrous gypsum contains more calcium than one ton of gypsum because gypsum contains about 21% water. Anhydrous gypsum also has higher solubility, which helps the soil to absorb calcium ions quickly. In addition, anhydrous gypsum is also used together with gypsum as gypsum, joint compounds, wallboards and other products in the construction industry. In the production of sulfuric acid, hard gypsum is also used as a source of sulfur.
[0004] The traditional production methods of anhydrous gypsum mainly involve dehydrating hydrated gypsum under high temperature and high pressure and mining anhydrous gypsum ore. These methods have high requirements on equipment, complex operations, and great energy consumption. In addition, the abundance of anhydrous gypsum ore is far less than that of gypsum. Summary of the invention
[0005] The present application provides a low-temperature gypsum solid waste crystallization centrifugal detoxification method, which realizes the phase change of gypsum solid waste into anhydrous gypsum and removes toxic substances at normal temperature and pressure to generate detoxified anhydrous gypsum.
[0006] The present application provides a method for centrifugal detoxification of gypsum solid waste at low temperature, comprising preparing a crystal detoxification agent, the crystal detoxification agent comprising sulfuric acid, an acid etchant and a retarder; wetting the gypsum solid waste with the crystal detoxification agent; standing and drying the wetted gypsum solid waste to obtain a transition product; centrifugally sorting the transition product to obtain separated non-toxic gypsum and toxic substances; and drying the non-toxic gypsum to obtain a modified detoxified anhydrous gypsum product.
[0007] In the above technical scheme, after the gypsum in the gypsum solid waste is dehydrated, centrifugal separation is used to achieve solid-solid separation of toxic substances and anhydrous gypsum, which can save the process of repeatedly washing and dehydrating the non-toxic gypsum to remove toxic substances on the surface of the gypsum, and has high treatment efficiency for gypsum solid waste, saving water and being environmentally friendly.
[0008] This solution does not require the detoxification and dehydration treatment of gypsum solid waste to be carried out in a traditional high-temperature and high-pressure environment, which can reduce the treatment difficulty of gypsum solid waste and improve economic benefits. Description of the Drawings
[0009] Figure 1 It is the SEM image before the treatment of Example 1 of this application.
[0010] Figure 2 It is the SEM image after the treatment of Example 1 of this application.
[0011] Figure 3 It is the comparison chart of XRD of Examples 1, 2, and 3 of this application before treatment with the standard card. PDF#00-033-0311 is the standard card of gypsum dihydrate. It can be seen from the figure that the main phase before treatment is gypsum dihydrate.
[0012] Figure 4 It is the comparison chart of XRD of Examples 1, 2, and 3 of this application after treatment with the standard card. PDF#00-037-1496 is the standard card of anhydrous gypsum. It can be seen from the figure that the main phase after treatment is anhydrous gypsum. Detailed Embodiments
[0013] The present application will be further described in detail below with reference to the drawings and embodiments. Through these descriptions, the features and advantages of the present application will become clearer and more definite.
[0014] The special term "exemplary" here means "serving as an example, embodiment, or illustrative". Any embodiment described as "exemplary" here does not have to be construed as superior to or better than other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings do not have to be drawn to scale unless otherwise specified.
[0015] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.
[0016] In the present application, unless otherwise specified, all components are commercially available products well-known to those skilled in the art.
[0017] The embodiment of the present application discloses a method for crystal transformation and centrifugal detoxification of gypsum solid waste at low temperature. There is a method for efficiently detoxifying heavy metal gypsum slag at normal temperature and pressure in the prior art. The method steps are as follows: 1) A sulfuric acid solution with a concentration of 0.1 - 8 mol / kg is dropped on the surface of the heavy metal gypsum slag to obtain an insufficiently wetted solid. The solid-liquid mass ratio of the gypsum slag to the sulfuric acid solution is 1:1 - 20:1; 2) Leave the solid obtained in step 1) standing for 0 - 36 hours in an environment with a temperature of 15 - 60 °C until the acidic solution fully wets the solid particles to promote the phase change of gypsum and achieve detoxification; 3) Wash and centrifuge the product obtained in step 2) to obtain a washing solution and a solid product.
[0018] In the prior art, for the method of highly efficient detoxification of heavy metal gypsum slag under normal temperature and pressure, through steps 1 and 2, the toxic substances in the heavy metal gypsum slag are converted into a liquid phase. At this time, anhydrous detoxified gypsum and an acidic solution containing toxic substances are obtained. Then, the obtained product is washed and centrifuged for dehydration. Step 3 is a process of solid - liquid separation. After separating the solution from the anhydrous detoxified gypsum in step 3, there will be toxic substances remaining on the surface of the anhydrous detoxified gypsum. To wash the toxic substances on the surface of the anhydrous detoxified gypsum clean, it is necessary to wash and dehydrate repeatedly, resulting in low detoxification efficiency and large water consumption. Example
[0019] This application discloses a method for crystal transformation and centrifugal detoxification of gypsum solid waste at low temperature, and the specific operation steps are as follows: Prepare a crystal transformation detoxification agent, which includes sulfuric acid, an acid etching agent, and a setting retarder; Use the crystal transformation detoxification agent to wet the gypsum solid waste; Leave the wetted gypsum solid waste standing for drying to obtain a transition product; Centrifugally separate the transition product to obtain separated non - toxic gypsum and toxic substances; Dry the non - toxic gypsum to obtain a modified anhydrous detoxified gypsum product.
[0020] Specifically, the gypsum solid waste in this application includes at least one of phosphogypsum, desulfurized gypsum, and red gypsum. In this example, desulfurized gypsum is taken as an example for illustration.
[0021] Wet the gypsum solid waste with the crystal transformation detoxification agent. The method of wetting the gypsum solid waste can be spraying; it can also be soaking the gypsum solid waste and then filtering. One state of wetting the gypsum solid waste is to infiltrate the gypsum solid waste until there is a liquid film with a thickness of 10 - 200 nm on the surface of the gypsum solid waste.
[0022] Leave the wetted gypsum solid waste standing for drying to obtain a transition product. At this time, the transition product is dehydrated gypsum solid waste, and the dehydrated gypsum solid waste is a solid mixture of toxic substances and non - toxic gypsum.
[0023] The drying method of leaving standing for drying in this example means leaving the wetted gypsum solid waste standing at normal temperature for natural drying. In another example, drying can also be carried out by blowing air or stirring and other drying methods. The environmental temperature during drying should generally not be greater than 100 °C, which can achieve the purpose of reducing the high energy consumption of treating gypsum solid waste.
[0024] Centrifuge and separate the transition products to achieve the separation of solid particles of toxic substances with different properties and non-toxic gypsum. Generally, the non-toxic gypsum is located at the bottom after separation, and the toxic substances are located above the non-toxic gypsum.
[0025] Finally, dry the non-toxic gypsum to obtain a modified detoxified anhydrous gypsum product. One way to dry the non-toxic gypsum is natural air drying. Another way to dry the non-toxic gypsum is to use a dryer for drying, and the temperature of the dryer is between 30 - 100 °C.
[0026] This solution converts the toxic substances in the gypsum solid waste into solids and uses centrifugal separation to achieve solid-solid separation, which can eliminate the process of repeatedly washing and dehydrating the non-toxic gypsum to remove the toxic substances on the surface of the gypsum. It has high processing efficiency for gypsum solid waste, saves water and is environmentally friendly.
[0027] This solution does not require the detoxification and dehydration treatment of gypsum solid waste to be carried out in a traditional high-temperature and high-pressure environment, which can reduce the processing difficulty of gypsum solid waste and improve economic benefits.
[0028] As an alternative solution, desulfurized gypsum is selected as an example for the gypsum solid waste in this embodiment. The desulfurized gypsum can be flue gas desulfurized gypsum obtained under any working conditions, such as gypsum produced naturally, or gypsum produced in the phosphate industry, or gypsum and calcined gypsum produced in some other industries.
[0029] As an alternative solution, the static temperature for static drying is between 15 - 60 °C, and the static drying time is between 0.5 - 36 hours. Static drying is to dry the wet gypsum solid waste at normal pressure in this embodiment. In another embodiment, the wet gypsum solid waste is dried in a reduced-pressure environment.
[0030] As an alternative solution, the method of centrifugal separation is centrifugal fluidization composite separation. The centrifugal force of the centrifugal fluidization composite separation is between 10 - 150G, and the fluidization backwash water pressure is between 4 - 40 kPa.
[0031] As an alternative solution, the proportion of sulfuric acid, acid etchant, and retarder in the crystal transformation detoxifying agent is any ratio in (10 - 15):(2 - 8):(10 - 20).
[0032] In this embodiment, the crystal transformation detoxifying agent contains 15 parts of sulfuric acid, 5 parts of acid etchant, and 15 parts of retarder.
[0033] In another embodiment, the proportion of sulfuric acid, acid etchant, and setting retarder is 10:2:10. In another embodiment, the proportion of sulfuric acid, acid etchant, and setting retarder is 15:8:20. In another embodiment, the proportion of sulfuric acid, acid etchant, and setting retarder is 10:8:20. In another embodiment, the proportion of sulfuric acid, acid etchant, and setting retarder is 15:2:20. In another embodiment, the proportion of sulfuric acid, acid etchant, and setting retarder is 15:8:10. In another embodiment, the proportion of sulfuric acid, acid etchant, and setting retarder is 13:5:15.
[0034] As an alternative, the crystal conversion detoxifying agent contains 15 parts of sulfuric acid, 5 parts of acid etchant, and 15 parts of setting retarder.
[0035] In this embodiment, the concentration of sulfuric acid is 0.5 - 7 mol / kg, and the acid etchant is perchloric acid. In another embodiment, the acid etchant is formic acid. In another embodiment, the acid etchant is phosphoric acid. In another embodiment, the acid etchant is chloroacetic acid. In another embodiment, the acid etchant is chlorosulfonic acid. In another embodiment, the acid etchant is citric acid. In another embodiment, the acid etchant is boric acid. In another embodiment, the acid etchant is sulfonyl chloride. In another embodiment, the acid etchant is sodium hydride. In another embodiment, the acid etchant is sodium amide.
[0036] In another embodiment, the acid etchant is at least two of formic acid, phosphoric acid, chloroacetic acid, chlorosulfonic acid, citric acid, boric acid, sulfonyl chloride, sodium hydride, or sodium amide.
[0037] As an alternative, the solid-liquid ratio of gypsum solid waste to the crystal conversion detoxifying agent is any ratio from 1:1 to 100:1. In one embodiment, the solid-liquid ratio of gypsum solid waste to the crystal conversion detoxifying agent is 50:1. In another embodiment, the solid-liquid ratio of gypsum solid waste to the crystal conversion detoxifying agent is 1:1. In another embodiment, the solid-liquid ratio of gypsum solid waste to the crystal conversion detoxifying agent is 100:1. In another embodiment, the solid-liquid ratio of gypsum solid waste to the crystal conversion detoxifying agent is 25:1. In another embodiment, the solid-liquid ratio of gypsum solid waste to the crystal conversion detoxifying agent is 331. In another embodiment, the solid-liquid ratio of gypsum solid waste to the crystal conversion detoxifying agent is 76:1. In another embodiment, the solid-liquid ratio of gypsum solid waste to the crystal conversion detoxifying agent is 64:1. In another embodiment, the solid-liquid ratio of gypsum solid waste to the crystal conversion detoxifying agent is 88:1.
[0038] As an alternative, centrifugal sorting uses a centrifugal concentrator capable of separating solid particles of different properties to sort the intermediate product.
[0039] Centrifugal fluidization composite sorting is an efficient sorting technology that combines a centrifugal force field and fluidization technology. The principle of centrifugal fluidization composite sorting is described as follows: Centrifugal force effect: By using high-speed rotation to generate a strong centrifugal force, particles with different properties are subjected to different magnitudes of forces in the centrifugal force field. In a high-magnitude enhanced gravity field, the centrifugal force is dozens to hundreds of times that of gravity, the sedimentation velocity of particles is high, and the movement differences of particles with different properties are greatly amplified, making the separation between particles with different properties easier than in the natural gravity field.
[0040] Fluidization principle: By introducing a fluid, such as water flow, to make the particle group in a fluidized state, the particles can move relatively freely among themselves, avoiding particle agglomeration or blockage, and creating good conditions for particle separation.
[0041] Composite action mechanism: The centrifugal force causes particles to have different sedimentation or movement velocities in the radial direction, while the fluidization effect acts on the particles in the tangential and axial directions. The two cooperate with each other to achieve effective separation of particles according to characteristics such as density, particle size, and shape.
[0042] The specific implementation method is as follows: Take 100 g of desulfurized gypsum, moisten it with 16 mL of crystal transformation and detoxification agent, with a solid-liquid ratio of 6.3, and let it stand at 25 °C for 24 h. Centrifugally separate the solid product obtained after standing, and under the operating conditions of a centrifugal force of 60G and a fluidization water pressure of 25 kPa, obtain the underflow product, and conduct relevant SEM and XRD tests on it (see the attached figure description Figures 1 - 4 ). The test results show that the desulfurized gypsum is transformed into the anhydrite phase. Example
[0043] A method for centrifugal detoxification of gypsum solid waste by crystal transformation at low temperature, including the following operating steps: Take 100 g of gypsum dihydrate, moisten it with 4 mL of crystal transformation and detoxification agent, with a solid-liquid ratio of 25, let it stand at 25 °C for 12 h, and under the conditions of a centrifugal force of 70G and a fluidization water pressure of 30 kPa, obtain the product, and conduct relevant SEM and XRD tests on it (see the attached figure description Figures 1 - 4 ). The test results show that the desulfurized gypsum is transformed into the anhydrite phase under the action of the crystal transformation and detoxification agent. Example
[0044] A method for centrifugal detoxification of gypsum solid waste by crystal transformation at low temperature, including the following operating steps: Take 100 g of gypsum dihydrate, moisten it with 38 mL of crystal transformation and detoxification agent, with a solid-liquid ratio of 2.6, let it stand at 25 °C for 4 h, and after separation under the conditions of a centrifugal force of 50G and a fluidization water pressure of 20 kPa, obtain the product, and conduct relevant SEM and XRD tests on it (see the attached figure description Figures 1 - 4 ). The test results show that the desulfurized gypsum is transformed into the anhydrite phase under the action of the crystal transformation and detoxification agent.
[0045] In the description of the present application, it should be noted that the orientation or positional relationship indicated by terms such as "upper", "lower", "inner", "outer", "front", "rear", "left", "right", etc. is based on the orientation or positional relationship in the working state of the present application. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present application.
[0046] In the description of the present application, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", and "coupled" shall be understood in a broad sense. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.
[0047] The present application has been described in combination with preferred embodiments above. However, these embodiments are only exemplary and only serve an illustrative purpose. On this basis, various substitutions and improvements can be made to the present application, and these all fall within the protection scope of the present application.
Claims
1. A method for centrifugal detoxification of gypsum solid waste at low temperature, characterized in that: The method comprises the following steps: A crystal transformation and detoxification agent is provided, wherein the crystal transformation and detoxification agent comprises sulfuric acid, an acid etching agent and a retarder; Wetting the gypsum solid waste with the crystal transformation and detoxification agent; Standing and drying the wetted gypsum solid waste to obtain a transition product; Centrifugally separating the transition product to obtain separated non-toxic gypsum and toxic substances; The non-toxic gypsum is dried to obtain a modified detoxified anhydrous gypsum product.
2. The method for centrifugal detoxification of gypsum solid waste at low temperature according to claim 1, characterized in that: The gypsum solid waste includes phospho-gypsum, desulfurized gypsum and red gypsum.
3. The method for centrifugal detoxification of gypsum solid waste at low temperature according to claim 1, characterized in that: The static drying temperature is between 15 and 60°C.
4. The method for centrifugal detoxification of gypsum solid waste at low temperature according to claim 1, characterized in that: The centrifugal separation method is centrifugal fluidization composite separation, the centrifugal force of the centrifugal fluidization composite separation is between 10 and 150 G, and the fluidization recoil water pressure is between 4 and 40 kPa.
5. The method for centrifugal detoxification of gypsum solid waste at low temperature according to claim 1, characterized in that: The transition product is dehydrated gypsum solid waste.
6. The method for centrifugal detoxification of gypsum solid waste at low temperature according to claim 1, characterized in that: The ratio of sulfuric acid, acid etchant and retarder contained in the crystal transformation and detoxification agent is any one of (10-15): (2-8): (10-20).
7. The method for centrifugal detoxification of gypsum solid waste at low temperature according to claim 6, characterized in that: The acid etchant is perchloric acid; The crystal transformation and detoxification agent contains 15 parts of sulfuric acid, 5 parts of perchloric acid and 15 parts of retarder.
8. The method for centrifugal detoxification of gypsum solid waste at low temperature according to claim 1, characterized in that: The solid-liquid ratio of the gypsum solid waste to the crystallization detoxification agent is any ratio between 1:1 and 100:
1.
9. The method for centrifugal detoxification of gypsum solid waste at low temperature according to claim 1, characterized in that: The method of drying the non-toxic gypsum includes natural air drying or drying with a dryer.
10. The low temperature gypsum solid waste crystallization centrifugal detoxification method according to claim 1, characterized in that: The centrifugal separation uses a centrifugal concentrator capable of separating solid particles of different properties to separate the transitional products.