Process for preparing raw material of cementing material by using sintered desulfurized gypsum

Abstract

The invention provides a process for preparing a raw material of a cementing material by using sintered desulfurized gypsum. The process comprises the following preparation steps: S1, transferring the desulfurized gypsum into a steam dryer for preliminary dehydration; s2, discharging the dried flue gas desulfurization gypsum into scattering equipment, and crushing the dried flue gas desulfurization gypsum; s3, transferring the scattered desulfurized gypsum into calcining equipment, and dehydrating again; s4, cooling the desulfurized gypsum dehydrated again through a cooling assembly; s5, grinding the cooled desulfurized gypsum by using grinding equipment; in the step S4, the cooling assembly comprises a plurality of sets of pipeline walls, and the pipeline walls can transfer steam to the steam dryer through heat exchange pipes. According to the preparation process provided by the invention, the output capacity can be improved, and the energy consumption for preparing the desulfurized gypsum into the raw material of the cementing material can be reduced.

Description

Technical Field

[0001] This invention relates to the field of solid waste application technology, and in particular to a process for preparing cementitious material raw materials using sintered desulfurized gypsum. Background Technology

[0002] Desulfurization gypsum is a byproduct of flue gas desulfurization in coal-fired power plants or steel plants. Its resource utilization can effectively reduce solid waste emissions and lower environmental pollution.

[0003] By utilizing it in building materials, soil amendments, and environmental protection materials, "waste treatment" can be achieved, promoting the development of a circular economy. As an industrial byproduct, desulfurized gypsum requires no mining or transportation costs and is relatively inexpensive. Its application in building materials can replace some natural gypsum, reducing production costs; its application in agriculture can improve soil structure, increasing crop yield and quality; and its application in environmental protection can treat industrial wastewater, reducing the emission of harmful substances. Therefore, the utilization of desulfurized gypsum helps promote green development and facilitate the implementation of sustainable development strategies.

[0004] Desulfurized gypsum typically contains over 90% calcium sulfate, with particle sizes mostly ranging from 30 to 100 μm. Its properties are similar to natural gypsum, featuring renewability, small particle size, stable composition, and low levels of harmful impurities. Desulfurized gypsum is widely used as a raw material in the building materials industry, such as in cement retarders and wall materials.

[0005] To meet the setting requirements of desulfurized gypsum as a cementitious material raw material, dehydration treatment of the desulfurized gypsum is necessary. A Chinese invention patent application (application number 202011191793.1) discloses an apparatus and method for producing self-activated type II anhydrous gypsum using industrial by-product gypsum. The process and apparatus system are fully enclosed and operate under negative pressure, allowing for the cascaded utilization of system heat and energy conservation. High-quality type II anhydrous gypsum products with excellent mechanical properties and subsequent self-activation can be obtained from industrial by-product gypsum.

[0006] However, the aforementioned invention experiment used a rotary flash drying system and a dynamic cyclone calciner, which resulted in relatively low production capacity and high energy consumption. Summary of the Invention

[0007] Based on the above situation, the main objective of this invention is to provide a process for preparing cementitious material raw materials using sintered desulfurized gypsum, so as to solve the problems of insufficient production capacity and high energy consumption of existing preparation processes.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A process for preparing cementitious material raw materials using sintered desulfurized gypsum includes the following preparation steps: S1: Transfer the desulfurized gypsum to a steam dryer for initial dehydration; S2: The dried desulfurized gypsum is discharged to the dispersing equipment to crush the dried desulfurized gypsum; S3: Transfer the broken-up desulfurized gypsum to the calcination equipment for further dehydration; S4: The desulfurized gypsum after further dehydration is cooled by a cooling component; S5: Grind the cooled desulfurized gypsum using grinding equipment; In step S4, the cooling assembly includes multiple sets of pipe walls, which can transfer steam to the steam dryer through heat exchange pipes.

[0009] Preferably, the pipe wall includes multiple water pipes, which are arranged in parallel. The pipe walls and the steam dryer are connected by heat exchange pipes and cold water return pipes. The heat exchange pipes and the cold water return pipes are connected to the water pipes. A steam return pump is installed in the middle of the heat exchange pipes, and a circulating water pump is installed in the middle of the cold water return pipes.

[0010] Preferably, a gap is provided between multiple pipe walls, and the gap ranges from 180 to 220 mm.

[0011] Preferably, the calcining equipment is a rotary calcining kiln, and the axial direction of the rotary calcining kiln is parallel to the plane where the pipe wall is located.

[0012] Preferably, the cooling assembly further includes a cooling hopper, and the pipe wall is disposed in the cooling hopper; The outer wall of the cooling silo is equipped with a vibrating feeder for conveying materials to the grinding equipment.

[0013] Preferably, the grinding equipment is a high-pressure roller mill.

[0014] Preferably, the rotary kiln and the steam dryer are connected by a connecting hood, and the hot exhaust gas from the rotary kiln flows back into the drying kiln through the connecting hood.

[0015] Preferably, the dispersing device is located below the connecting cover, and a bucket elevator is provided between the calcining device and the dispersing device assembly.

[0016] Preferably, an air cannon is installed on the outer wall of the cooling silo.

[0017] Preferably, the heating temperature of the steam dryer is 150℃~180℃; The calcination temperature of the calcination equipment is 300~600℃. The beneficial effects of this invention are as follows: Compared with the prior art, the process for preparing cementitious material raw materials using sintered desulfurized gypsum provided in this application has the following advantages: First, by adding a dispersing device before the calcination equipment, the lumps of desulfurized gypsum after preliminary heating and drying are dispersed, creating conditions for the rapid discharge of residual moisture and crystal water, thereby increasing production capacity. Second, by utilizing the hot exhaust gas from the rotary calcination kiln and the water vapor generated by the desulfurized gypsum after contact heating with the pipe wall, the residual heat generated after heating the desulfurized gypsum can be fully utilized, reducing energy consumption. Other beneficial effects of the present invention will be explained in detail through the introduction of specific technical features and technical solutions in specific embodiments. Those skilled in the art should be able to understand the beneficial technical effects brought about by these technical features and technical solutions through the introduction of these technical features and technical solutions. Attached Figure Description

[0018] Figure 1 This is a schematic flow diagram of a process for preparing cementitious material raw materials using sintered desulfurized gypsum according to the present invention.

[0019] Figure 2 This is a schematic diagram of a preparation apparatus for a process of preparing cementitious material raw materials using sintered desulfurized gypsum according to the present invention.

[0020] Figure 3 This is a schematic diagram illustrating the structure of water pipes in a pipe wall in this invention.

[0021] Figure 4 This is a schematic diagram illustrating the spacing between adjacent pipe walls in this invention. Explanation of reference numerals in the attached figures: 1. Steam dryer; 11. Cold water return pipe; 111. Circulating water pump; 12. Heat exchange pipe; 121. Steam return pump; 2. Dispersing equipment; 3. Bucket elevator; 4. Belt conveyor; 5. Connecting cover; 6. Calcination equipment; 61. Calcination cover; 7. Cooling components; 71. Cooling silo; 72. Pipe wall; 721. Water pipe; 722. Water inlet pipe; 723. Water outlet pipe; 73. Vibrating feeder; 74. Air cannon; 9. Grinding equipment. Detailed Implementation

[0022] The present invention is described below based on embodiments, but the present invention is not limited to these embodiments. In the following detailed description of the present invention, some specific details are described in detail, but well-known methods, processes, procedures, and elements are not described in detail in order to avoid obscuring the essence of the present invention.

[0023] Furthermore, those skilled in the art should understand that the accompanying drawings provided herein are for illustrative purposes only and are not necessarily drawn to scale.

[0024] Unless the context explicitly requires it, the words "comprising," "including," and similar terms throughout the specification and claims should be interpreted as encompassing rather than being exclusive or exhaustive; that is, meaning "including but not limited to."

[0025] In the description of this invention, it should be understood that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more. This invention provides a process for preparing cementitious material raw materials using sintered desulfurized gypsum. The process involves dehydrating and grinding the desulfurized gypsum to achieve the required setting properties, thus enabling it to be used as a raw material for gypsum cementitious materials. Specifically, refer to... Figure 1 and Figure 2 The process for preparing cementitious material raw materials using sintered desulfurized gypsum includes the following preparation steps: Step S1: Transfer the desulfurized gypsum to steam dryer 1 for preliminary dehydration.

[0026] In step S1, after preliminary crushing, the desulfurized gypsum is conveyed by belt conveyor 4 and transferred through a receiving hopper. The desulfurized gypsum meeting the process preparation standards is then fed into the feed end of steam dryer 1. During the initial dehydration process of the desulfurized gypsum, the temperature of steam dryer 1 can be controlled between 150℃ and 180℃, allowing free water to be quickly removed from the gypsum. After controlling the drying time, the moisture content of the desulfurized gypsum is reduced to below 4%, and it is then discharged into the next step.

[0027] It should be noted that there are no restrictions on the method of feeding materials into the desulfurized gypsum. Other feeding components can also be used, such as vacuum feeders, screw conveyors, etc. In addition, manual handling can also be used to feed materials, as long as a stable and accurate feeding effect can be achieved.

[0028] As one embodiment, the desulfurized gypsum in the state before entering the steam dryer 1 for drying, that is, before entering the process of preparing cementitious material raw materials using sintered desulfurized gypsum, should have a moisture content of 10% to 15% and a maximum particle size of lumps of less than 25 mm. Under these conditions, after being processed by the preparation process of this application, the desulfurized gypsum can be used to obtain cementitious material raw materials with fineness and moisture content that meet the requirements.

[0029] Step S2: The dried raw materials are discharged to the dispersing equipment 2 to crush the dried desulfurized gypsum.

[0030] Specifically, a connecting hood 5 is fixed at the discharge end of the steam dryer. The dispersing device 2 can be a dispersing machine, the outer shell of which can be fixed inside the connecting hood 5. A receiving hopper (not shown in the figure) is installed inside the connecting hood 5. This receiving hopper is located between the steam dryer and the connecting hood 5, transferring the heated desulfurized gypsum into the dispersing machine. The dispersing machine can break up and pulverize the dried desulfurized gypsum. By setting up the dispersing machine, conditions are created for the rapid discharge of residual free water and crystal water, which can improve the processing efficiency of the entire desulfurized gypsum raw material preparation process. It is understood that the dispersing device 2 can also be other equipment with a dispersing effect, such as a mixer with a dispersing function.

[0031] Step S3: Transfer the dispersed raw materials to the calcination equipment 6 for further dehydration.

[0032] The calcining equipment 6 is installed on the side of the connecting hood 5 away from the steam dryer. As one embodiment, a bucket elevator 3 is provided between the disperser and the calcining equipment 6. The bucket elevator 3 can stably transfer materials. The bucket elevator 3 can adapt to the height difference between the disperser and the calcining equipment 6, and the material transfer is flexible. In addition, the bucket elevator 3 can withstand high temperatures and is suitable for transferring desulfurized gypsum powder at high temperatures.

[0033] The calcination equipment 6 can be a rotary calcination kiln, wherein the calcination temperature inside the rotary calcination kiln is 300℃~600℃ and the calcination time is 3min-5min. After the desulfurized gypsum powder is dispersed, the bound water carried in the desulfurized gypsum powder can be removed after high-temperature calcination.

[0034] In one embodiment, the rotary calcining kiln and the steam dryer 1 are connected by a connecting cover 5. The connecting cover 5 is enclosed inside. The exhaust outlet of the rotary calcining kiln is connected to the connecting cover 5. The exhaust gas discharged from the rotary calcining kiln carries heat and can flow directly back into the drying kiln from the connecting cover 5 to assist in heating and dehydrating the desulfurized gypsum inside the steam dryer kiln, thereby improving the utilization rate of the heat energy generated by the rotary calcining kiln and reducing the energy consumption of the steam dryer 1.

[0035] Step S4: The desulfurized gypsum after dehydration is cooled by the cooling component 7. In this step, the pipe wall 72 can transfer steam to the steam dryer 1 through the heat exchange pipe 12.

[0036] Reference Figure 2 and Figure 3 Specifically, the cooling assembly 7 includes a cooling silo 71 and a pipe wall 72. The pipe wall 72 is fixed in the cooling silo 71. The calcining equipment 6 and the cooling silo are connected by a calcining hood 61. The desulfurized gypsum that has been calcined at high temperature has completed the dehydration process and enters the cooling assembly 7 for cooling in order to proceed with subsequent processing.

[0037] During the cooling process, the high-temperature desulfurized gypsum enters the cooling silo 71 and comes into contact with the pipe wall 72 containing heat dissipation water. The pipe wall 72 achieves heat exchange, rapidly transferring the heat of the desulfurized gypsum to the cooling water, thereby achieving rapid cooling of the desulfurized gypsum. The heat transferred to the cooling water also enables the cooling water to generate a large amount of water vapor, which is then returned to the steam pipeline of the steam dryer 1 to raise the temperature of the steam dryer 1 and reduce the energy consumption of the steam dryer 1 when initially heating the desulfurized gypsum.

[0038] The process in this application utilizes the hot waste gas from the rotary kiln and the water vapor generated by the desulfurized gypsum after contact heating with the pipe wall 72. This fully utilizes the residual heat generated after heating the desulfurized gypsum, reduces the energy consumption of the desulfurized gypsum in the preparation of cementitious material raw materials, reduces energy expenditure in production, and has better economic benefits.

[0039] As one embodiment, the pipe wall 72 includes multiple water pipes 721 arranged in parallel. Water outlet pipe 723 and water inlet pipe 722 are connected to the upper and lower ends of the water pipes 721 respectively. Water inlet pipe 722 and water outlet pipe 723 are connected to each water pipe 721 for the circulation of liquid in and out of the water pipes 721.

[0040] The pipe wall 72 and the steam dryer 1 are connected by a heat exchange pipe 12 and a cold water return pipe 11. The heat exchange pipe 12 and the cold water return pipe 11 can be connected to the outlet pipe 723 and the inlet pipe 722, respectively, thereby connecting the heat exchange pipe 12 and the cold water return pipe 11 to the water pipe 721. A steam return pump 121 is installed in the middle of the heat exchange pipe 12, and a circulating water pump 111 is installed in the middle of the cold water return pipe 11. The steam return pump 121 can process the water vapor generated by the heating of the pipe wall 72 and discharge it into the steam dryer 1, while the circulating water pump 111 can discharge the low-temperature water of the steam drying kiln from the cold water return pipe 11 into the water pipe 721 for reuse as cooling desulfurization gypsum. This process can realize the flow of water vapor and low-temperature water, realize the internal water circulation between the pipe wall 72 and the steam dryer 1, and reduce water consumption. It should be noted that those skilled in the art should know that the water inlet pipe 722 or the steam dryer 1 can also be connected to an external water supply system to provide water for the initial stage of the process or to replenish the water loss during the circulation process. This is prior art and will not be described in detail in this application.

[0041] Reference Figure 4As one embodiment, a spacing is provided between the multiple pipe walls 72, ranging from 180 to 220 mm, preferably 200 mm. Maintaining a suitable spacing can improve the heat exchange efficiency in the cooling assembly 7 and accelerate the process progress, as well as improve the steam generation efficiency, providing sufficient steam for the steam dryer 1 to initially heat the desulfurized gypsum.

[0042] As one embodiment, the material discharge direction of the rotary calcining kiln is parallel to the plane of the pipe wall 72. After being heated by the rotary calcining kiln, the desulfurized gypsum is discharged and falls from top to bottom into the cooling hopper. By setting the pipe wall 72 parallel to the discharge direction, the desulfurized gypsum will not directly hit the water pipe 721 when it falls, thus avoiding the water pipe 721 from breaking due to collision between the desulfurized gypsum and the water pipe 721.

[0043] Step S5: Grind the cooled desulfurized gypsum.

[0044] The cooling silo 71 is connected to the grinding equipment 9. After the desulfurized gypsum in the cooling silo 71 is cooled, it can be discharged into the grinding equipment 9 for grinding. After the roller mill, the finished gypsum powder can be obtained for filling.

[0045] As one embodiment, a vibrating feeder 73 is fixed to the outer wall of the cooling silo 71. The vibrating feeder 73 can transfer the desulfurized gypsum after cooling to the grinding equipment 9, and can also adjust the discharge speed of the desulfurized gypsum in the cooling silo 71 according to the cooling situation.

[0046] As one embodiment, the grinding equipment 9 is a high-pressure roller mill. Existing grinding equipment 9 typically uses a ball mill, but ball mills often result in excessively fine grinding when grinding desulfurized gypsum. By using a high-pressure roller mill, the spacing of the grinding rollers is adjusted to allow desulfurized gypsum particles of appropriate size to pass through directly, preventing them from becoming excessively fine and increasing the yield of the finished product.

[0047] As one embodiment, an air cannon 74 is fixed to the outer wall of the cooling silo 71. The air cannon 74 can emit compressed gas in the cooling silo 71 to break up arches and allow the material to be discharged smoothly from the cooling silo 71.

[0048] The process for preparing cementitious material raw materials using sintered desulfurized gypsum provided in this application utilizes the above technical solutions. On the one hand, by adding a dispersing device 2 before the calcining equipment 6, the lumps of desulfurized gypsum after preliminary heating and drying are dispersed, creating conditions for the rapid discharge of residual moisture and crystal water. On the other hand, by utilizing the hot exhaust gas from the rotary calcining kiln and the water vapor generated by the desulfurized gypsum after contact heating with the pipe wall 72, the residual heat generated after heating the desulfurized gypsum can be fully utilized, reducing energy consumption.

[0049] The following are the finished products obtained by using the processing technology of this application for desulfurized gypsum with different moisture contents and agglomeration sizes: Example

[0050] Before dehydration, the desulfurized gypsum contained 11% moisture and had a maximum agglomerate size of 15mm. After processing using this process, the product has a fineness of less than 200 mesh (71%) and a water content of 0.5%. Example

[0051] Before dehydration, the desulfurized gypsum contained 12% moisture and had a maximum agglomerate size of 13mm. After processing using this process, the product has a fineness of less than 200 mesh (74%) and a water content of 0.8%. Example

[0052] Before dehydration, the desulfurized gypsum contained 13% moisture and had a maximum agglomerate size of 12.5 mm. After processing using this process, the product has a fineness of less than 200 mesh (73%) and a water content of 0.4%. Example

[0053] Before dehydration, the desulfurized gypsum contained 15% moisture and had a maximum agglomerate size of 19mm. After processing using this process, the resulting product has a fineness of less than 200 mesh (70%) and a water content of 0.8%.

[0054] Therefore, it can be seen that, after processing by the preparation process of this application, the desulfurized gypsum with a moisture content of 10% to 15% and a maximum particle size of less than 25 mm, has a final product with a fineness of less than 200 mesh accounting for more than 70%, which meets the requirements for gypsum for filling. Those skilled in the art will understand that, without conflict, the above-mentioned preferred solutions can be freely combined and superimposed.

[0055] It should be understood that the above embodiments are merely exemplary and not restrictive. Various obvious or equivalent modifications or substitutions that can be made by those skilled in the art regarding the above details without departing from the basic principles of the present invention will be included within the scope of the claims of the present invention.

Claims

1. A process for preparing cementitious material raw materials using sintered desulfurized gypsum, characterized in that, The preparation steps include the following: S1: Transfer the desulfurized gypsum to a steam dryer for initial dehydration; S2: The dried desulfurized gypsum is discharged to the dispersing equipment to crush the dried desulfurized gypsum; S3: Transfer the broken-up desulfurized gypsum to the calcination equipment for further dehydration; S4: The desulfurized gypsum after further dehydration is cooled by a cooling component; S5: Grind the cooled desulfurized gypsum using grinding equipment; In step S4, the cooling assembly includes multiple sets of pipe walls, which can transfer steam to the steam dryer through heat exchange pipes.

2. The process for preparing cementitious material raw materials using sintered desulfurized gypsum as described in claim 1, characterized in that, The pipe wall includes multiple water pipes, which are arranged in parallel. The pipe walls and the steam dryer are connected by heat exchange pipes and cold water return pipes. The heat exchange pipes and the cold water return pipes are connected to the water pipes. A steam return pump is installed in the middle of the heat exchange pipes, and a circulating water pump is installed in the middle of the cold water return pipes.

3. The process for preparing cementitious material raw materials using sintered desulfurized gypsum as described in claim 1, characterized in that, There are gaps between the pipe walls at multiple locations, and the gaps range from 180 to 220 mm.

4. The process for preparing cementitious material raw materials using sintered desulfurized gypsum as described in claim 1, characterized in that, The calcining equipment is a rotary calcining kiln, and the axial direction of the rotary calcining kiln is parallel to the plane where the pipe wall is located.

5. The process for preparing cementitious material raw materials using sintered desulfurized gypsum as described in claim 1, characterized in that, The cooling assembly also includes a cooling hopper, and the pipe wall is disposed in the cooling hopper; The outer wall of the cooling silo is equipped with a vibrating feeder for conveying materials to the grinding equipment.

6. The process for preparing cementitious material raw materials using sintered desulfurized gypsum as described in claim 1, characterized in that, The grinding equipment is a high-pressure roller mill.

7. The process for preparing cementitious material raw materials using sintered desulfurized gypsum as described in claim 4, characterized in that, The rotary kiln and the steam dryer are connected by a connecting hood, and the hot exhaust gas from the rotary kiln flows back into the drying kiln through the connecting hood.

8. The process for preparing cementitious material raw materials using sintered desulfurized gypsum as described in claim 7, characterized in that, The dispersing device is located below the connecting cover, and a bucket elevator is provided between the calcining device and the dispersing device assembly.

9. The process for preparing cementitious material raw materials using sintered desulfurized gypsum as described in claim 5, characterized in that, An air cannon is installed on the outer wall of the cooling silo.

10. The process for preparing cementitious material raw materials using sintered desulfurized gypsum as described in any one of claims 1-9, characterized in that, The heating temperature of the steam dryer is 150℃~180℃; The calcination temperature of the calcination equipment is 300~600℃.

Images