Water-washing salt extraction equipment for cement and kiln dust

Abstract

The utility model provides water washing and salt extracting equipment for cement and kiln dust. Comprising the following equipment units which are connected through pipelines: a kiln dust bin, a kiln dust washing storage tank, a washing suction filter, a primary impurity removal reactor, a secondary impurity removal reactor, a multi-medium filter, a multi-effect evaporation crystallization system, an evaporation feeding buffer tank, a dead steam condensate water preheater, a steam condensate water preheater, a crystal thickener, a centrifugal machine and a saline water tank, harmless treatment of the high-chlorine kiln dust is achieved through a water washing-impurity removal-evaporation full-process closed-loop system, and the kiln returning rate of the ash is increased; a two-stage condensate water waste heat recycling technology is innovated, the steam energy consumption is reduced by 60% or above, the water resource circulation rate reaches 90%, and environmental protection compliance and resource economic benefits are achieved.

Description

Technical Field

[0001] This utility model relates to the field of hazardous waste treatment technology, and in particular to a cement co-processing kiln ash washing and salt extraction device. Background Technology

[0002] Currently, co-processing in cement kilns is one of the main technologies for disposing of hazardous waste. However, with the operation of cement kilns, the salt content in cement kiln ash also increases, especially with excessive chloride ions, seriously affecting the quality of the final cement product. Therefore, to ensure cement production quality meets standards, ash discharge is necessary in the chloride ion enrichment section of the cement kiln, removing the high-chlorine-content kiln ash from the cement production system. This discharged kiln ash, due to its high salt content, poses difficulties in solid waste treatment and also wastes salt resources. During cement production, kiln ash accumulates large amounts of chloride ions (typically 3-15 wt%), and direct return to the kiln can lead to scaling and blockage of the kiln system. Existing technologies commonly use water washing for dechlorination, but this method has the following key drawbacks:

[0003] 1) The water washing salt extraction process is inefficient; solid-liquid separation is incomplete: traditional filtration equipment (such as belt filter press) has a retention rate of less than 60% for kiln ash particles with a diameter ≤50μm, resulting in a moisture content of ash slag >35%, and an increase in heat consumption of more than 15% when returning to the kiln for calcination (industry standard GB / T 35151-2017).

[0004] Insufficient impurity removal precision: Conventional single-stage impurity removal reactors can only remove 80% of calcium and magnesium ions, with residual calcium ion concentration >500mg / L, resulting in a shortened scaling cycle of the evaporation crystallization system to 72 hours.

[0005] 2) Serious waste of energy and water resources; existing technologies have not achieved the cascade reuse of condensate, steam consumption is as high as 1.2-1.5t / t-brine (industry survey data), and more than 40% of exhaust steam is directly discharged. The water ratio in the washing process is as high as 8:1 (water:kiln ash), and the industrial water reuse rate is <60%.

[0006] 3) Insufficient equipment integration and stability; the traditional equipment adopts a decentralized layout, which leads to an increase of 20 kPa in pressure loss and the risk of secondary pollution of crude brine. The key equipment lacks liquid level interlock control, resulting in large fluctuations in the feed rate of the multi-effect evaporation crystallization system.

[0007] 4) The quality of by-products is substandard; the crystalline salt has a moisture content of >2% due to insufficient centrifugal dehydration, and the salt purity is only 90-93% (lower than the 98% requirement of Grade I industrial salt in GB / T 5468-2012).

[0008] The aforementioned deficiencies result in kiln ash treatment costs for cement companies reaching as high as 120-150 yuan / ton (according to statistics from the China Cement Association in 2022), and also pose compliance risks related to hazardous waste disposal. This application addresses these technical bottlenecks through innovative equipment layout and process control. Utility Model Content

[0009] This utility model proposes a cement co-processing kiln ash washing and salt extraction device, which solves the problems existing in the background technology. The technical solution of this utility model is implemented as follows:

[0010] A cement co-processing kiln ash washing and salt extraction device includes the following equipment units connected by pipelines: kiln ash silo, kiln ash washing storage tank, washing filter, primary impurity removal reactor, secondary impurity removal reactor, multi-media filter, multi-effect evaporation crystallization system, evaporation feed buffer tank, exhaust steam condensate preheater, steam condensate preheater, crystallizer thickener, centrifuge, and brine tank; wherein:

[0011] The kiln ash silo is connected to the kiln ash inlet of the kiln ash washing storage tank via a screw conveyor for conveying kiln ash powder. The bottom outlet of the kiln ash washing storage tank is connected to the inlet of the washing filter via a slurry pump. The solid outlet of the filter is connected to the ash and slag return channel, and the clear liquid and coarse brine outlet is connected to the primary impurity removal reactor, the secondary impurity removal reactor, and the multi-media filter via a coarse brine pipe. The outlet of the media filter is connected to the inlet of the multi-effect evaporation crystallization system via an evaporation feed buffer tank. The steam inlet of the system is connected to the saturated steam pipe. The condensate outlet of the multi-effect evaporation crystallization system is divided into two paths: the first path is connected to the exhaust steam condensate preheater and then back to the water supply inlet of the kiln ash washing storage tank; the second path is connected to the steam condensate preheater and then goes outside for reuse. The inlet of the crystal thickener receives the concentrated crystal slurry discharged from the multi-effect evaporation crystallization system, and the outlet is connected to the crystal slurry inlet of the centrifuge. The salt crystal outlet of the centrifuge is connected to the crystallized salt packaging system.

[0012] As a preferred technical solution, the filter plate pore size of the water washing filter is 5-10 μm, the working pressure is negative pressure, and the pressure is -0.06 to -0.1 MPa; the volume of the evaporation feed buffer tank is 2-5 m³. 3 Set up liquid level interlock control.

[0013] As a preferred technical solution, the multi-effect evaporation crystallization system adopts a triple-effect countercurrent layout, with a multi-effect evaporation chamber temperature of 60–120℃ and a forced circulation pump flow rate of 150–800 m³ / h. 3 / h; the cone angle of the crystallizer is ≤60°, and it is equipped with an ultrasonic level gauge.

[0014] As a preferred technical solution, the centrifuge is a horizontal screw discharge type with a rotation speed of 1000-3000 rpm, and the water content of the crystallized salt after separation is ≤0.5%; the brine tank is equipped with a liquid level control to monitor the balance of the inlet and outlet water of the brine tank.

[0015] As a preferred technical solution, the cement co-kiln ash washing and salt extraction equipment is connected to the cement kiln calcination system in a closed loop through the ash and slag return conveying channel; the multi-media filter is filled with a composite filter layer of quartz sand and activated carbon, with a total height ≥1.2m.

[0016] Compared with existing technologies, this solution has the following advantages:

[0017] (1) Full-process resource utilization. Achieve full-chain treatment of chlorine-containing kiln ash from cleaning, separation to crystallization, and transform industrial waste into reusable raw materials and qualified industrial salt.

[0018] (2) Efficient utilization of energy and water resources. Through multi-stage heat recovery and condensate reuse design, production energy consumption and freshwater consumption are significantly reduced, practicing green manufacturing.

[0019] (3) Overall improvement in production stability. Intelligent linkage control between equipment ensures continuous and stable operation from raw material processing to crystallized finished products, reducing the frequency of downtime maintenance.

[0020] (4) Zero waste discharge. All by-products (ash, wastewater, waste salt) are recycled within the plant or sold externally in compliance with regulations, completely eliminating the risk of environmental pollution. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the structure of a cement co-processing kiln ash washing and salt extraction device according to the present invention;

[0023] Figure 2 This is a flowchart of a cement co-process with kiln ash washing and salt extraction according to the present invention.

[0024] Explanation of reference numerals in the attached figures:

[0025] 1. Kiln ash silo; 2. Kiln ash washing tank; 3. Washing filter; 4. Primary impurity removal reactor; 5. Secondary impurity removal reactor; 6. Brine tank; 7. Multi-media filter; 8. Evaporation feed buffer tank; 9. Exhaust steam condensate preheater; 10. Steam condensate preheater; 11. Multi-effect evaporation crystallization system; 12. Crystallizer thickener; 13. Centrifuge. Detailed Implementation

[0026] The technical solution of this utility model will be clearly and completely described below with reference to its embodiments. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0027] Reference Figure 1 This utility model provides a cement co-processing kiln ash washing and salt extraction equipment, comprising the following equipment units connected by pipelines: kiln ash silo 1, kiln ash washing storage tank 2, washing filter 3, primary impurity removal reactor 4, secondary impurity removal reactor 5, multi-media filter 7, multi-effect evaporation crystallization system 11, evaporation feed buffer tank 8, exhaust steam condensate preheater 9, steam condensate preheater 10, crystallizer thickener 12, centrifuge 13, and brine tank; wherein:

[0028] The kiln ash silo 1 is connected to the kiln ash inlet of the kiln ash washing storage tank 2 via a screw conveyor for conveying kiln ash powder. The bottom outlet of the kiln ash washing storage tank 2 is connected to the inlet of the washing filter 3 via a slurry pump. The solid outlet of the filter 3 is connected to the ash and slag return channel, and the clear liquid coarse brine outlet is connected to the primary impurity removal reactor 4, the secondary impurity removal reactor 5, and the multi-media filter 7 via a coarse brine pipe. The outlet of the multi-media filter 7 is connected to the inlet of the multi-effect evaporation crystallization system 11 via an evaporation feed buffer tank 8. The steam inlet of the system is connected to the saturated steam pipe. The condensate outlet of the multi-effect evaporation crystallization system 11 is divided into two paths: the first path is connected to the exhaust steam condensate preheater 9 and then back to the water inlet of the kiln ash washing storage tank 2, and the second path is connected to the steam condensate preheater 10 and then sent outside for reuse. The inlet of the crystal thickener 12 receives the concentrated crystal slurry discharged from the multi-effect evaporation crystallization system 11, and the outlet is connected to the crystal slurry inlet of the centrifuge 13. The salt crystal outlet of the centrifuge 13 is connected to the crystallized salt packaging system.

[0029] The water washing filter has a filter plate pore size of 5–10 μm and operates under negative pressure, with a pressure range of -0.06 to -0.1 MPa; the evaporation feed buffer tank has a volume of 2–5 m³. 3 A liquid level interlock control system is installed. The multi-effect evaporation crystallization system adopts a triple-effect counter-current layout, with a multi-effect evaporation chamber temperature of 60–120℃ and a forced circulation pump flow rate of 150–800 m³ / h. 3 / h; the cone angle of the crystallizer is ≤60°, equipped with an ultrasonic level gauge. The centrifuge is a horizontal screw discharge type, with a speed of 1000~3000rpm, and the water content of the crystallized salt after separation is ≤0.5%; the brine tank is equipped with a level control to monitor the balance of the inlet and outlet water in the brine tank. The cement co-kiln ash washing and salt extraction equipment is connected to the cement kiln calcination system in a closed loop through the ash and slag return conveying channel; the multi-media filter 7 is filled with a composite filter layer of quartz sand and activated carbon, with a total height ≥1.2m.

[0030] See Figure 2 The main process of a cement co-process with kiln ash washing and salt extraction is as follows:

[0031] A-Kiln ash, B-Kiln ash slurry, C-Ash residue, D-Crude brine, E-Refined brine, F-Evaporated brine, G-Concentrated crystal slurry, H-Crystallized crystal slurry, I-Crystallized salt, S-Saturated steam, L-Steam condensate, Q-Exhaust steam condensate, W-Industrial water.

[0032] The saline kiln ash discharged from the cement co-kiln is stored in the kiln ash silo 1 through the ash discharge system. It is then metered and transported to the kiln ash washing tank 2, where it is mixed with industrial water in a certain proportion for washing. After thorough washing, the ash slurry is pumped to the washing filter 3 for solid-liquid separation. The separated ash residue can be returned to the cement kiln for cement production. The separated crude brine is passed through the primary impurity removal reactor 4 and the secondary impurity removal reactor 5. Impurity ions in the crude brine are removed by adding impurity removal agents while controlling the pH value of the washing solution. The filter residue produced by precipitation is collected separately for recycling.

[0033] After two stages of purification, the refined brine is stored in brine tank 6. Then, after passing through a multi-media filter 7 to remove suspended solids from the brine, it becomes evaporated brine and enters the evaporation feed buffer tank 8 for storage.

[0034] The brine evaporated in the evaporation feed buffer tank 8 then passes through the exhaust steam condensate preheater 9 and the steam condensate preheater 10 before entering the multi-effect evaporation crystallization system 11 for evaporation, concentration and crystallization. The concentrated crystal slurry is then enriched and thickened in the crystallizer 12 to form a crystal slurry, and finally the final product, crystallized salt, is obtained by centrifuging 13.

[0035] The saturated steam condensate of the multi-effect evaporation crystallization system 11 is recycled outside the boundary after the heat is recovered and utilized by the steam condensate preheater 10.

[0036] The exhaust steam condensate generated by the multi-effect evaporation crystallization system 11 is sent to the kiln ash washing tank 2 for ash mixing and washing after the heat is recovered and utilized by the exhaust steam condensate preheater 9, which will not cause waste of water resources.

[0037] The entire process maximizes resource recycling and reuse.

[0038] The control parameters for this process are as follows:

[0039] The water-to-ash ratio for washing kiln ash is (2-6):1 (by mass).

[0040] The moisture content of the kiln ash residue after washing is ≤30%;

[0041] The chloride ion concentration in the ash residue after washing with water is ≤1%;

[0042] pH range for impurity removal reaction: 8–14;

[0043] After impurity removal, the calcium ion concentration of the refined saline solution is ≤200mg / L.

[0044] This solution achieves harmless treatment of high-chlorine kiln ash through a closed-loop system of "water washing-impurity removal-evaporation," with an ash and slag return rate of ≥95% and crystallized salt purity reaching the first-class industrial standard. It also features an innovative two-stage condensate waste heat recovery technology, which reduces steam energy consumption by more than 60% and achieves a water resource recycling rate of 90%, combining environmental compliance with resource-based economic benefits.

[0045] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0046] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A cement co-processing kiln ash washing and salt extraction device, characterized in that, The equipment units connected by pipelines include: kiln ash silo (1), kiln ash washing storage tank (2), washing filter (3), primary impurity removal reactor (4), secondary impurity removal reactor (5), multi-media filter (7), multi-effect evaporation crystallization system (11), evaporation feed buffer tank (8), exhaust steam condensate preheater (9), steam condensate preheater (10), crystallizer thickener (12), centrifuge (13), and brine tank (6); wherein: The kiln ash silo (1) is connected to the kiln ash inlet of the kiln ash washing tank (2) via a screw conveyor for conveying kiln ash powder. The bottom outlet of the kiln ash washing tank (2) is connected to the feed end of the washing filter (3) via a slurry pump. The solid outlet of the filter is connected to the ash return channel, and the clear liquid crude brine outlet is connected to the primary impurity removal reactor (4), the secondary impurity removal reactor (5), and the multi-media filter (7) in sequence via a crude brine pipe. The outlet of the multi-media filter (7) is connected to the multi-effect evaporation crystallization system (11) via an evaporation feed buffer tank (8). At the feed end, the steam inlet of the system is connected to the saturated steam pipe; the condensate outlet of the multi-effect evaporation crystallization system (11) is divided into two paths: the first path is connected to the exhaust steam condensate preheater (9) and then back to the water supply port of the kiln ash washing tank (2); the second path is connected to the steam condensate preheater (10) and then sent to the outside for reuse; the inlet of the crystal thickener (12) receives the concentrated crystal slurry discharged from the multi-effect evaporation crystallization system (11), and the outlet is connected to the crystal slurry inlet of the centrifuge (13); the salt crystal outlet of the centrifuge (13) is connected to the crystallized salt packaging system.

2. The cement co-processing kiln ash washing and salt extraction equipment as described in claim 1, characterized in that, It also includes the water washing filter (3) with a filter plate pore size of 5-10 μm, a working pressure of negative pressure, and a pressure of -0.06 to -0.1 MPa; and the evaporation feed buffer tank (8) with a volume of 2-5 m³. 3 Set up liquid level interlock control.

3. The cement co-processing kiln ash washing and salt extraction equipment as described in claim 1, characterized in that, The multi-effect evaporation crystallization system (11) adopts a three-effect counter-current layout, with a multi-effect evaporation chamber temperature of 60–120°C and a forced circulation pump flow rate of 150–800 m³ / h. 3 / h; the cone angle of the crystallizer (12) is ≤60° and it is equipped with an ultrasonic level gauge.

4. The cement co-processing kiln ash washing and salt extraction equipment as described in claim 1, characterized in that, The centrifuge (13) is a horizontal screw discharge type with a rotation speed of 1000-3000 rpm. The water content of the crystallized salt after separation is ≤0.5%. The brine tank (6) is equipped with a liquid level control to monitor the balance of water entering and leaving the brine tank.

5. A cement co-processing kiln ash washing and salt extraction device according to any one of claims 1 to 4, characterized in that: The cement co-kiln ash washing and salt extraction equipment is connected to the cement kiln calcination system in a closed loop through the ash and slag return conveying channel; the multi-media filter (7) is filled with a composite filter layer of quartz sand and activated carbon, with a total height ≥1.2m.

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