A lime slurry reuse system and method

Abstract

This invention discloses a lime slurry reuse system and method, relating to the field of industrial waste recycling technology. The system includes a sedimentation tank for settling impurities in the lime slurry and controlling its calcium hardness; a sludge tank connected to the sedimentation tank for receiving the settled lime slurry; and a mixing tank connected to the sedimentation tank and the sludge tank for receiving lime slurry from both tanks and conveying it to a primary mixer for sintering mixing. By magnetically separating and settling the lime slurry used in the cast iron machine, iron impurities are removed, and the calcium hardness range of the lime slurry is controlled. The heated lime slurry is then conveyed to the primary mixer to replace part of the quicklime in the sintering mixing process, effectively treating solid waste, solving environmental problems, and further reducing the amount of quicklime required.

Description

Technical Field

[0001] This invention relates to the field of industrial waste recycling technology, and in particular to a lime slurry reuse system and method. Background Technology

[0002] In the production process of cast iron machines, lime slurry needs to be sprayed onto the iron molds to extend their service life and ensure smooth demolding of the iron blocks. This slurry is a mixture of quicklime and water, which is generated in large quantities during operation. Due to the high impurity content of the lime slurry, it is difficult to handle large quantities of lime slurry by simply filtering it to form lime paste, and there is also a lack of suitable storage locations. The temperature of this lime slurry is also relatively high, reaching 70 to 80 degrees Celsius in summer and about 50 to 60 degrees Celsius in winter. If this lime slurry is not treated in time, it will cause gypsum accumulation and environmental pollution; it will also seriously affect normal continuous production; the water temperature in the cooling water tank will be too high, resulting in poor effectiveness of hot water circulation for cooling the cast iron blocks, while generating a large amount of steam, which will seriously corrode the equipment on site; in addition, the energy of the hot water cannot be effectively utilized, resulting in a waste of thermal energy. Summary of the Invention

[0003] Therefore, the technical problem to be solved by the present invention is that the large amount of waste lime slurry generated during the cast iron production process is difficult to handle.

[0004] The above-mentioned technical problems are solved by the following technical solutions:

[0005] This invention proposes a lime slurry reuse system, which includes a sedimentation tank, a sludge tank, and a mixing water tank.

[0006] In a preferred embodiment of the lime slurry reuse system of the present invention: a sedimentation tank is used to settle impurities in the lime slurry and control calcium hardness;

[0007] A sludge tank, connected to the sedimentation tank, is used to receive the lime slurry after sedimentation in the sedimentation tank;

[0008] The mixing tank is connected to the sedimentation tank and the sludge tank, and is used to receive the lime slurry from the sedimentation tank and the sludge tank, and to transport the lime slurry to the primary mixer to participate in sintering mixing.

[0009] In a preferred embodiment of the lime slurry reuse system of the present invention: a first pipeline is provided upstream of the sedimentation tank for inputting the lime slurry into the sedimentation tank;

[0010] A high-powered magnetic separator is installed in the middle section of the first pipe to separate iron impurities from the lime slurry.

[0011] In a preferred embodiment of the lime slurry reuse system of the present invention: a steam heat exchanger is provided on one side of the sludge tank to increase the temperature of the lime slurry entering the sludge tank.

[0012] In a preferred embodiment of the lime slurry reuse system of the present invention: a second pipeline connects the sludge tank and the sedimentation tank, and also connects the mixing water tank and the sedimentation tank.

[0013] In a preferred embodiment of the lime slurry reuse system of the present invention: a first lift pump is provided in the sludge tank for transporting the lime slurry to the mixing tank.

[0014] In a preferred embodiment of the lime slurry reuse system of the present invention: a first flow meter and a density meter are installed on the pipeline that transports the lime slurry to the mixing tank to monitor the state of the lime slurry.

[0015] In a preferred embodiment of the lime slurry reuse system of the present invention: a second lift pump is provided in the mixing tank for conveying the lime slurry to the primary mixer.

[0016] In a preferred embodiment of the lime slurry reuse system of the present invention: a second flow meter is installed on the pipeline that transports the lime slurry to the primary mixer to monitor the state of the lime slurry.

[0017] In a preferred embodiment of the lime slurry reuse system of the present invention: a first stirring pump is provided in the sludge tank to prevent the lime slurry from settling;

[0018] The mixing tank is equipped with a second stirring pump to prevent the lime slurry from settling.

[0019] The present invention also proposes a method for reusing lime slurry, which includes magnetic separation sedimentation and production addition.

[0020] In a preferred embodiment of the lime slurry reuse method of the present invention: magnetic separation precipitation is used to remove iron impurities from the lime slurry generated by the iron casting machine, and the calcium hardness range of the lime slurry is controlled.

[0021] In the production process, the lime slurry is heated and conveyed to a primary mixer to replace part of the quicklime in the sintering mixing process, and the addition ratio is dynamically adjusted according to the calcium hardness of the mixture.

[0022] The beneficial effects of this invention are as follows: by magnetically separating and settling the lime slurry used in the iron casting machine, iron impurities in the lime slurry are removed, and the calcium hardness range of the lime slurry is controlled. This lime slurry, after being heated, is then fed to a primary mixer to replace part of the quicklime in the sintering mixing process. This not only effectively treats solid waste and solves environmental problems, but also further reduces the amount of quicklime required. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments of the present invention will be briefly described below. Obviously, the drawings described below only relate to some embodiments of the present invention and are not intended to limit the present invention.

[0024] Figure 1 A schematic diagram of a lime slurry reuse system is shown.

[0025] Figure 2 A flowchart of a method for reusing lime slurry is shown. Detailed Implementation

[0026] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0027] The terminology used in this invention is that which is currently widely used in the art in consideration of the function of the invention; however, these terms may vary according to the intent of those skilled in the art, precedent, or new technology in the art. Furthermore, specific terms may be chosen by the applicant, and in such cases, their detailed meanings will be described in the detailed description of the invention. Therefore, the terms used in this specification should not be construed as simple names, but rather based on their meanings and the overall description of the invention.

[0028] Example 1, referring to Figure 1 This embodiment provides a lime slurry reuse system, including a sedimentation tank 29, a sludge tank 30, and a mixing tank 31.

[0029] Specifically, sedimentation tank 29 is used to settle impurities in lime slurry and control calcium hardness. The main function of sedimentation tank 29 is to preliminarily purify the lime slurry. After the raw lime slurry passes through a high-power magnetic separator to separate iron impurities, it enters sedimentation tank 29, where gravity settling removes some of the heavier and larger impurities. At the same time, this stage also regulates the calcium hardness of the lime slurry, controlling it within the range of 4000-7000 mg / L.

[0030] Sludge tank 30, connected to sedimentation tank 29, receives the lime slurry that has settled in sedimentation tank 29. The lime slurry, after preliminary treatment in sedimentation tank 29, enters sludge tank 30, which is connected to it. To prevent lime paste and other substances from settling and caking again in the sludge tank, a stirring pump is installed in sludge tank 30 to maintain a uniform mixing state of the slurry. In addition, a steam heat exchanger raises the temperature of the lime slurry from sedimentation tank 29 to above 90°C, which facilitates subsequent mixing and reaction processes.

[0031] The mixing tank 31, connected to the sedimentation tank 29 and the sludge tank 30, receives lime slurry from the sedimentation tank 29 and the sludge tank 30 and transports it to the primary mixer 35 for sintering mixing. The mixing tank 31 is connected to both the sedimentation tank 29 and the sludge tank 30, serving as a collection and supply unit for the treated lime slurry. The mixing tank 31 receives lime slurry from the sedimentation tank 29 and the sludge tank 30. A booster pump transports the lime slurry to the primary mixer 35, where it participates in the subsequent production process as part of the sintering mixture, thereby recovering the difficult-to-handle and store lime slurry and achieving its reuse.

[0032] Example 2, refer to Figure 1 This embodiment provides a lime slurry reuse system, including a sedimentation tank 29, a sludge tank 30, and a mixing tank 31.

[0033] Specifically, sedimentation tank 29 is used to settle impurities in lime slurry and control calcium hardness. The main function of sedimentation tank 29 is to preliminarily purify the lime slurry. After the raw lime slurry passes through a high-power magnetic separator to separate iron impurities, it enters sedimentation tank 29, where gravity settling removes some of the heavier and larger impurities. At the same time, this stage also regulates the calcium hardness of the lime slurry, controlling it within the range of 4000-7000 mg / L.

[0034] A slurry pump 12 is installed in the sedimentation tank 29 to pump lime slurry into the sludge tank 30 and the mixing tank 31. The output pipe of the sedimentation tank 29 is the first pipe 32, which branches to connect the sludge tank 30 and the mixing tank 31 respectively. A first electric shut-off valve 13 is installed at the unbranched end of the first pipe 32, a third electric shut-off valve 15 is installed at the branch connecting to the sludge tank 30, and a second electric shut-off valve 14 is installed at the branch connecting to the mixing tank 31. These three shut-off valves can control the lime slurry pumped from the sedimentation tank 29 in real time, allowing the lime slurry to directly enter the mixing tank 31 when the sludge tank 30 is under maintenance.

[0035] A steam heat exchanger 16 is provided between the first electric shut-off valve 13 and the sludge tank 30 to work with the steam delivery pipe 33 to heat the lime slurry.

[0036] Sludge tank 30, connected to sedimentation tank 29, receives the lime slurry that has settled in sedimentation tank 29. The lime slurry, after preliminary treatment in sedimentation tank 29, enters sludge tank 30, which is connected to it. To prevent lime paste and other substances from settling and caking again in the sludge tank, a stirring pump is installed in sludge tank 30 to maintain a uniform mixing state of the slurry. In addition, a steam heat exchanger raises the temperature of the lime slurry from sedimentation tank 29 to above 90°C, which facilitates subsequent mixing and reaction processes.

[0037] The sludge tank 30 contains two first lift pumps 18, which are used to transport lime slurry to the mixing tank 31. One first lift pump 18 is equipped with a fourth electric shut-off valve 19, and the other first lift pump 18 is equipped with a fifth electric shut-off valve 20.

[0038] The mixing tank 31, connected to the sedimentation tank 29 and the sludge tank 30, receives lime slurry from the sedimentation tank 29 and the sludge tank 30 and transports it to the primary mixer 35 for sintering mixing. The mixing tank 31 is connected to both the sedimentation tank 29 and the sludge tank 30, serving as a collection and supply unit for the treated lime slurry. The mixing tank 31 receives lime slurry from the sedimentation tank 29 and the sludge tank 30. A booster pump transports the lime slurry to the primary mixer 35, where it participates in the subsequent production process as part of the sintering mixture, thereby recovering the difficult-to-handle and store lime slurry and achieving its reuse.

[0039] Specifically, the first pipe 32 is located upstream of the sedimentation tank 29 and is used to input lime slurry into the sedimentation tank 29; the first pipe 32 is the starting point for recycling lime slurry.

[0040] A high-powered magnetic separator 11, located in the middle section of the first pipe 32, is used to separate iron impurities from the lime slurry. To extend the life of the chain conveyor iron mold and ensure effective demolding of the iron blocks, a mixture of quicklime and water is sprayed onto the iron mold, generating a large amount of lime slurry. Iron impurities will enter the lime slurry in contact with the iron mold. During recycling, the iron impurities must be removed first to improve the purity of the slurry, reduce subsequent equipment wear, and minimize the impact on product quality.

[0041] Specifically, a steam heat exchanger 16 is provided on one side of the sludge tank 30 to increase the temperature of the lime slurry entering the sludge tank 30. The steam heat exchanger 16 uses steam as a heat source, and the steam comes from the steam pipeline network within the production enterprise.

[0042] Specifically, the second pipeline 36 connects the sludge tank 30 and the sedimentation tank 29, as well as the mixing tank 31 and the sedimentation tank 29. The mixing tank is an existing tank in the original design and is used for normal production. The sedimentation tank and the sludge tank are new additions. The sludge tank is mainly responsible for transfer and heating.

[0043] Specifically, the sludge tank 30 is equipped with a first lift pump 18 for transporting lime slurry to the mixing tank 31. A first flow meter 27 and a density meter 28 are installed on the pipeline transporting the lime slurry to the mixing tank 31 to monitor the state of the lime slurry. The first flow meter 27 and the density meter 28 are used to monitor the flow rate and density of the lime slurry in real time during the transport process, providing data support for operators to adjust and control the process. The pipeline transporting the lime slurry to the mixing tank 31 is a third pipeline 37.

[0044] Specifically, a second lift pump 22 is provided in the mixing tank 31 to transport lime slurry to the primary mixer 35, which is the final point of use for the recycled lime slurry.

[0045] There are two second booster pumps 22, which are connected to the primary mixer 35 through the fourth pipe 34. The second booster pumps 22 are respectively connected to the sixth electric shut-off valve 23 and the seventh electric shut-off valve 24.

[0046] Specifically, a second flow meter 25 is installed on the pipeline that transports the lime slurry to the primary mixer 35 to monitor the state of the lime slurry and ensure the accuracy of the mixing ratio. The pipeline that transports the lime slurry to the primary mixer 35 is a fourth pipeline 34.

[0047] Specifically, the sludge tank 30 is equipped with a first stirring pump 17 to prevent lime slurry from settling; the mixing tank 31 is equipped with a second stirring pump 21 to prevent lime slurry from settling.

[0048] To prevent lime slurry from settling during storage and transportation, which could lead to pipe blockage or uneven composition, both sludge tank 30 and mixing tank 31 are equipped with stirring devices. Through continuous stirring, the lime slurry is kept in suspension and homogeneous.

[0049] Example 3, referring to Figure 2 This embodiment provides a method for reusing lime slurry, including magnetic separation sedimentation and production addition.

[0050] Specifically, magnetic separation and precipitation are used to remove iron impurities from the lime slurry produced by the iron casting machine, and the calcium hardness of the lime slurry is controlled within a certain range. The calcium hardness of the precipitated lime slurry is controlled at 4000-7000 mg / L, and mineral slurry is added. According to the chemical formula, the molar mass of CaO is 56 g / mol, and Ca... 2+ Based on a molar mass of 40 g / mol, each liter of lime slurry can replace 5.04-8.8 g of quicklime (CaO). The lime slurry consumption per hour is approximately 12 t / h, which can reduce quicklime consumption by 60.48-105.84 kg / h.

[0051] In the production process, lime slurry is heated and conveyed to a primary mixer to replace part of the quicklime in the sintering mixing process, and the addition ratio is dynamically adjusted according to the calcium hardness of the mixture.

[0052] A steam heat exchanger was added next to the sludge pond to raise the temperature of the lime slurry in the pond to over 90℃. This increased the average temperature of the mixed material from 45℃ to 63℃ when the lime slurry was transported to the mixing pond, improving the permeability of the material layer during sintering. Simultaneously, the negative pressure in the flue gas increased from an average of -14.36 kPa to -13.28 kPa during sintering; the electricity consumption per ton of ore decreased from 28.59 kWh / t to 26.73 kWh / t, and the solid fuel consumption per ton decreased from 58.70 kg / t to 55.38 kg / t.

[0053] The lime slurry from the cast iron machine is separated into impurities by a high-power magnetic separator and the sediment from the settling tank is dewatered by pressure filtration before being transported to the sintering plant for batching in sintering. The CaO content of the magnetically separated impurities and sediment is 50-55%. Adding 2% of the slurry at this ratio can maintain production balance. Based on a batching rate of 100 kg / m / s, this can reduce the amount of quicklime required by 1.11-1.12 kg / m / s and effectively address environmental issues.

[0054] Finally, it should be noted that the methods and devices described in detail above are merely embodiments, and those skilled in the art can modify these embodiments in different ways as long as they do not depart from the scope of the present invention.

Claims

1. A method for recycling and reusing lime slurry from a cast iron machine, based on a lime slurry recycling system, characterized in that: The system includes a sedimentation tank (29) for controlling the calcium hardness of lime slurry; a sludge tank (30) connected to the sedimentation tank (29) for receiving the heated lime slurry; and a mixing tank (31) connected to the sedimentation tank (29) and the sludge tank (30) for receiving the lime slurry from the sedimentation tank (29) and the sludge tank (30), and conveying the lime slurry to a primary mixer (35) to replace part of the quicklime in the sintering mixture, while dynamically adjusting the addition ratio according to the calcium hardness of the mixture. The method includes the following steps: Magnetic separation precipitation is used to remove iron impurities from the lime slurry produced by the iron casting machine, and to control the calcium hardness range of the lime slurry. In the production process, the lime slurry is heated and conveyed to a primary mixer to replace part of the quicklime in the sintering mixing process, and the addition ratio is dynamically adjusted according to the calcium hardness of the mixture.

2. The method for recycling and reusing lime slurry from a cast iron machine according to claim 1, characterized in that: The lime slurry reuse system also includes, The first pipe (32) is located upstream of the sedimentation tank (29) for feeding the lime slurry into the sedimentation tank (29); A powerful magnetic separator (11) is installed in the middle section of the first pipe (32) to separate iron impurities in the lime slurry.

3. The method for recycling and reusing lime slurry from a cast iron machine according to claim 2, characterized in that: A steam heat exchanger (16) is provided on one side of the sludge tank (30) to increase the temperature of the lime slurry entering the sludge tank (30).

4. The method for recycling and reusing lime slurry from a cast iron machine according to claim 3, characterized in that: The lime slurry reuse system also includes, The second pipeline (36) connects the sludge tank (30) and the sedimentation tank (29), and also connects the mixing tank (31) and the sedimentation tank (29).

5. The method for recycling and reusing lime slurry from a cast iron machine according to claim 4, characterized in that: The sludge tank (30) is equipped with a first lift pump (18) for transporting the lime slurry to the mixing tank (31).

6. The method for recycling and reusing lime slurry from a cast iron machine according to claim 5, characterized in that: A first flow meter (27) and a density meter (28) are installed on the pipeline that transports the lime slurry to the mixing tank (31) to monitor the state of the lime slurry.

7. The method for recycling and reusing lime slurry from a cast iron machine according to claim 6, characterized in that: The mixing tank (31) is equipped with a second lift pump (22) for conveying the lime slurry to the primary mixer (35).

8. The method for recycling and reusing lime slurry from a cast iron machine according to claim 7, characterized in that: A second flow meter (25) is installed on the pipeline that delivers the lime slurry to the primary mixer (35) to monitor the state of the lime slurry.

9. The method for recycling and reusing lime slurry from a cast iron machine according to claim 8, characterized in that: The sludge tank (30) is equipped with a first stirring pump (17) to prevent the lime slurry from settling. The mixing tank (31) is equipped with a second stirring pump (21) to prevent the lime slurry from settling.

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