Lime slurry recycling system and method

Abstract

The invention discloses a lime slurry recycling system and method, and relates to the technical field of industrial waste recycling, the system comprises a sedimentation tank used for precipitating impurities in lime slurry and controlling calcium hardness; the sludge tank is communicated with the settling tank and is used for receiving the lime slurry settled in the settling tank; and the mixing water tank is communicated with the sedimentation tank and the sludge tank and is used for receiving the lime slurry from the sedimentation tank and the sludge tank and conveying the lime slurry into the primary mixer to participate in sintering and mixing. Lime slurry used when the pig casting machine is used is subjected to magnetic separation precipitation, iron impurities in the lime slurry are removed, and the calcium hardness range of the lime slurry is controlled. Lime slurry is heated and then conveyed to the primary mixer to replace part of quicklime to participate in the sintering and mixing process, solid waste is effectively treated, the environmental protection problem is solved, and the batching amount of the quicklime can be further reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial waste recycling, in particular to a lime slurry recycling system and method. Background Art

[0002] During the iron casting process, lime slurry is sprayed onto the cast iron molds to extend the life of the chain belt and ensure smooth demolding of the cast iron. This slurry, a mixture of quicklime and water, is produced in large quantities during operation. Due to the high impurity content in the lime slurry, processing the resulting lime paste through filtration alone is difficult, and suitable storage facilities are lacking. The resulting lime slurry is also quite hot, reaching 70 to 80 degrees Celsius in the summer and around 50 to 60 degrees Celsius in the winter. If this lime slurry is not promptly processed, it will cause gypsum accumulation and environmental pollution, seriously impacting normal continuous production. The water temperature in the cooling pool will be too high, rendering the hot water circulation ineffective for cooling the cast iron, generating large amounts of steam and severely corroding on-site equipment. Furthermore, the hot water's energy cannot be effectively utilized, resulting in wasted heat. Summary of the Invention

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

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

[0005] The present invention provides a lime slurry recycling system, which comprises a sedimentation tank, a sludge tank and a mixing water tank.

[0006] In a preferred embodiment of the lime slurry recycling system of the present invention: a sedimentation tank for settling impurities in the lime slurry and controlling calcium hardness;

[0007] A sludge tank, connected to the sedimentation tank, for receiving the lime slurry after precipitation in the sedimentation tank;

[0008] The mixing water 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 transport the lime slurry to the primary mixer to participate in sintering and mixing.

[0009] In a preferred embodiment of the lime slurry recycling system of the present invention: a first pipeline is provided upstream of the sedimentation tank and is used to input the lime slurry into the sedimentation tank;

[0010] A strong magnetic separator is arranged in the middle section of the first pipeline and is used to separate iron impurities in the lime slurry.

[0011] In a preferred embodiment of the lime slurry recycling 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 recycling system of the present invention: the 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 recycling system of the present invention, a first lifting pump is provided in the sludge tank for transporting the lime slurry to the mixing water tank.

[0014] In a preferred embodiment of the lime slurry recycling 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 water tank to monitor the state of the lime slurry.

[0015] In a preferred embodiment of the lime slurry recycling system of the present invention, a second lifting pump is provided in the mixing water tank for conveying the lime slurry to the primary mixer.

[0016] In a preferred embodiment of the lime slurry recycling 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 recycling system of the present invention: a first stirring pump is provided in the sludge tank to prevent the lime slurry from settling;

[0018] A second stirring pump is provided in the mixing water tank to prevent the lime slurry from settling.

[0019] The present invention also provides a lime slurry recycling method, which includes magnetic separation precipitation and production addition.

[0020] In a preferred embodiment of the lime slurry recycling method of the present invention: magnetic separation and precipitation are performed to remove iron impurities in the lime slurry produced by the iron casting machine and to control the calcium hardness range of the lime slurry;

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

[0022] The present invention has the beneficial effects of removing iron impurities from lime slurry used in cast iron machines by subjecting it to magnetic separation and precipitation, thereby controlling the calcium hardness of the lime slurry. The lime slurry is heated and then transported to a primary mixer to replace some of the quicklime in the sintering and mixing process, effectively treating solid waste and addressing environmental concerns while also further reducing the amount of quicklime required. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings of the embodiments of the present invention. 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 shows a schematic diagram of a lime slurry recycling system;

[0025] Figure 2 A flow chart showing a lime slurry reuse method. DETAILED DESCRIPTION

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

[0027] The terms used in the present invention are those commonly used in the art in view of the functions of the present invention, but these terms may vary according to the intentions of those skilled in the art, precedents, or new technologies in the art. In addition, specific terms may be selected by the applicant, and in such cases, their detailed meanings will be described in the detailed description of the present invention. Therefore, the terms used in the specification should not be understood as simple names, but rather as the meanings of the terms and the overall description of the present invention.

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

[0029] Specifically, sedimentation tank 29 is used to precipitate impurities in the lime slurry and control calcium hardness. The primary function of sedimentation tank 29 is to initially purify the lime slurry. After the raw lime slurry passes through a powerful magnetic separator to remove iron impurities, it enters sedimentation tank 29, where gravity sedimentation removes some of the heavier, larger impurities. Simultaneously, during this stage, the calcium hardness of the lime slurry is regulated to maintain a range of 4000-7000 mg / L.

[0030] Sludge tank 30, connected to sedimentation tank 29, receives the lime slurry after settling in sedimentation tank 29. After initial treatment in sedimentation tank 29, the lime slurry enters the connected sludge tank 30. To prevent lime paste and other substances from settling and hardening 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 transported from sedimentation tank 29 to above 90°C, facilitating the subsequent mixing and reaction processes.

[0031] The mixing tank 31 is connected to the sedimentation tank 29 and the sludge tank 30. It receives lime slurry from these two tanks and delivers it to the primary mixer 35 for sintering. 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 treated lime slurry. The mixing tank 31 receives lime slurry from the sedimentation tank 29 and the sludge tank 30. This slurry is delivered to the primary mixer 35 via a lift pump, where it is used as part of the sintering process and subsequently used in the production process. This allows for the recycling of lime slurry that is difficult to process and store, enabling its reuse.

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

[0033] Specifically, sedimentation tank 29 is used to precipitate impurities in the lime slurry and control calcium hardness. The primary function of sedimentation tank 29 is to initially purify the lime slurry. After the raw lime slurry passes through a powerful magnetic separator to remove iron impurities, it enters sedimentation tank 29, where gravity sedimentation removes some of the heavier, larger impurities. Simultaneously, during this stage, the calcium hardness of the lime slurry is regulated to maintain a range of 4000-7000 mg / L.

[0034] A slurry pump 12 is provided in the sedimentation tank 29 to pump lime slurry into the sludge tank 30 and the mixing water tank 31. The output pipe from the sedimentation tank 29 is a first pipe 32. The first pipe 32 bifurcates, connecting the sludge tank 30 and the mixing water tank 31, respectively. A first electric shut-off valve 13 is provided at the unbranched portion of the first pipe 32. A third electric shut-off valve 15 is provided at the bifurcated portion connecting to the sludge tank 30. A second electric shut-off valve 14 is provided at the bifurcated portion connecting to the mixing water tank 31. These three shut-off valves allow real-time control of the lime slurry pumped from the sedimentation tank 29. This allows the lime slurry to flow directly into the mixing water tank 31 during equipment maintenance in the sludge tank 30.

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

[0036] Sludge tank 30, connected to sedimentation tank 29, receives the lime slurry after settling in sedimentation tank 29. After initial treatment in sedimentation tank 29, the lime slurry enters the connected sludge tank 30. To prevent lime paste and other substances from settling and hardening 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 transported from sedimentation tank 29 to above 90°C, facilitating the subsequent mixing and reaction processes.

[0037] There are two first lifting pumps 18 in the sludge tank 30 for transporting lime slurry to the mixing water tank 31. One of the first lifting pumps 18 is provided with a fourth electric stop valve 19, and the other first lifting pump 18 is provided with a fifth electric stop valve 20.

[0038] The mixing tank 31 is connected to the sedimentation tank 29 and the sludge tank 30. It receives lime slurry from these two tanks and delivers it to the primary mixer 35 for sintering. 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 treated lime slurry. The mixing tank 31 receives lime slurry from the sedimentation tank 29 and the sludge tank 30. This slurry is delivered to the primary mixer 35 via a lift pump, where it is used as part of the sintering process and subsequently used in the production process. This allows for the recycling of lime slurry that is difficult to process and store, enabling its reuse.

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

[0040] A powerful 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 belt iron mold and ensure effective demolding of the iron blocks, the mold is sprayed with a mixture of quicklime and water. This produces a large amount of lime slurry, and iron impurities in the lime slurry can enter the lime slurry in contact with the mold. During recycling, the iron impurities must be removed to improve the purity of the slurry, reduce subsequent equipment wear, and reduce the impact on product quality.

[0041] Specifically, a steam heat exchanger 16 is provided on one side of the sludge tank 30 for increasing 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 pipe network within the production enterprise.

[0042] Specifically, the second pipeline 36 connects the sludge tank 30 and the sedimentation tank 29, and also connects the mixing water tank 31 and the sedimentation tank 29. The mixing water tank is a water tank originally designed and used for normal production. The sedimentation tank and the sludge tank are newly added water tanks. The sludge tank is mainly responsible for transfer and heating.

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

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

[0045] There are two second lift pumps 22 , which are connected to the primary mixer 35 via a fourth pipeline 34 . The second lift pumps 22 are respectively connected to the sixth electric stop valve 23 and the seventh electric stop 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 proportion. The pipeline that transports the lime slurry to the primary mixer 35 is the fourth pipeline 34.

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

[0048] In order to prevent the lime slurry from settling during storage and transportation, which may lead to pipe blockage or uneven composition, stirring devices are installed inside the sludge tank 30 and the mixing water tank 31, and continuous stirring is used to maintain the suspension and uniformity of the lime slurry.

[0049] Example 3, reference Figure 2 This embodiment provides a method for recycling lime slurry, including magnetic separation precipitation and production addition.

[0050] Specifically, magnetic separation and precipitation are used to remove iron impurities from the lime slurry produced by the cast iron machine and control the calcium hardness range of the lime slurry; the calcium hardness of the lime slurry after precipitation is controlled at 4000-7000 mg / L, and slurry is added. According to the chemical formula, the molar mass of CaO is 56g / mol, and Ca 2+ Calculated based on the molar mass of 40g / mol, each liter of lime slurry can replace 5.04-8.8g of quicklime CaO. The lime slurry usage per hour in production is ≈12t / h, which can reduce the quicklime consumption by 60.48-105.84kg / h.

[0051] During production, the lime slurry is heated and transported 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 tank to raise the temperature of the lime slurry in the sludge tank to above 90°C. This increased the average temperature of the mixed material from 45°C to 63°C when the lime slurry was transported to the mixing tank, improving the permeability of the material bed during the sintering process. Furthermore, the flue gas pressure during sintering increased from an average of -14.36 kPa to -13.28 kPa. 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 from impurities by a strong magnetic separator, and the sediment in the sedimentation tank is filtered out and dehydrated before being transported to the sintering plant for sintering and ore blending. The CaO content of the magnetically separated impurities and sediment is 50-55%. Adding 2% of the CaO content can maintain production balance. Based on a 100kg / m / s batching amount, the quicklime batching amount can be reduced by 1.11-1.12kg / m / s, and environmental protection issues can be effectively addressed.

[0054] Finally, it should be pointed out 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 without departing from the scope of the present invention.

Claims

1. A lime slurry recycling system, characterized by: include, a sedimentation tank (29) for controlling the calcium hardness of the lime slurry; A sludge tank (30) is connected to the sedimentation tank (29) and is used to receive the heated lime slurry; The mixing water tank (31) is connected to the sedimentation tank (29) and the sludge tank (30), and is used to receive the lime slurry from the sedimentation tank (29) and the sludge tank (30), and transport the lime slurry to the primary mixer (35) to replace part of the quicklime to participate in the sintering mixture, and at the same time dynamically adjust the addition ratio according to the calcium hardness of the mixture.

2. The lime slurry recycling system according to claim 1, characterized in that: Also includes, a first pipe (32), disposed upstream of the sedimentation tank (29), for inputting the lime slurry into the sedimentation tank (29); A strong magnetic separator (11) is arranged in the middle section of the first pipe (32) and is used to separate iron impurities in the lime slurry.

3. The lime slurry recycling system according to claim 2, characterized in that: A steam heat exchanger (16) is provided on one side of the sludge tank (30) for increasing the temperature of the lime slurry entering the sludge tank (30).

4. The lime slurry recycling system according to claim 3, characterized in that: Also includes, The second pipeline (36) connects the sludge tank (30) and the sedimentation tank (29), and also connects the mixing water tank (31) and the sedimentation tank (29).

5. The lime slurry recycling system according to claim 4, characterized in that: The sludge tank (30) is provided with a first lifting pump (18) for transporting the lime slurry to the mixing water tank (31).

6. The lime slurry recycling system according to claim 5, characterized in that: A first flow meter (27) and a density meter (28) are installed on the pipeline for transporting the lime slurry to the mixing water tank (31) to monitor the state of the lime slurry.

7. The lime slurry recycling system according to claim 6, characterized in that: The mixing water tank (31) is provided with a second lifting pump (22) for conveying the lime slurry to the primary mixer (35).

8. The lime slurry recycling system according to claim 7, characterized in that: 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.

9. The lime slurry recycling system according to claim 8, characterized in that: A first stirring pump (17) is provided in the sludge tank (30) to prevent the lime slurry from settling; A second stirring pump (21) is provided in the mixing water tank (31) to prevent the lime slurry from settling.

10. A method for recycling lime slurry, characterized in that: include, Magnetic separation and precipitation to remove iron impurities from the lime slurry produced by the iron casting machine and control the calcium hardness range of the lime slurry; Magnetic separation and precipitation, the lime slurry is heated and transported to a primary mixer to replace part of the quicklime to participate in the sintering mixing process, and the addition ratio is dynamically adjusted according to the calcium hardness of the mixture.

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