Fly ash washing method and fly ash washing system

Abstract

The present invention relates to the technical field of solid waste treatment, and provides a fly ash washing method and a fly ash washing system. The fly ash washing method comprises: setting a target viscosity of fly ash slurry and a target salinity of fly ash slurry; calculating a slurrying ratio of the fly ash, the slurrying liquid and clean water based on the target viscosity of the fly ash slurry, the target salinity of the fly ash slurry, the salt content of the fly ash and the salinity of the slurrying liquid; and making the fly ash slurry according to the slurrying ratio. The fly ash washing method provided by the present invention is used to solve the defect of heavy burden of fly ash water treatment in the prior art, and can control the slurry ratio of fly ash slurry raw materials with the target salinity as a guide, and can flexibly control the water consumption of fly ashes with different salinities, so that the salinity of the fly ash slurry and the fly ash filtrate is not affected by the fluctuation of the fly ash components, and effectively reduce the water consumption in the fly ash washing process, and reduce energy consumption and operating costs.

Description

Technical Field

[0001] The present invention relates to the technical field of solid waste treatment, and particularly to a fly ash water washing method and a fly ash water washing system. Background Art

[0002] During the resource utilization process of municipal solid waste incineration fly ash, problems such as equipment corrosion, system scaling and blockage, and unqualified product quality are likely to occur. Therefore, a water washing desalination technology needs to be used to efficiently wash and desalt the fly ash. The current fly ash water washing desalination technology generally makes fly ash slurry according to the mass ratio of fly ash to pulping water. The obtained fly ash slurry will undergo solid-liquid separation. The fly ash filtrate after solid-liquid separation will be discharged after water treatment. However, the composition of fly ash in different batches fluctuates greatly. When the salt content of fly ash is low, the salinity of the fly ash filtrate will also be low, which will not only cause a large waste of water resources, but also impose a huge burden on subsequent water treatment. Summary of the Invention

[0003] The first aspect of the present invention provides a fly ash water washing method to solve the defect of heavy burden on fly ash water treatment in the prior art. It can take the target salinity as a guide, control the slurry ratio of the raw materials of the fly ash slurry, and can flexibly control the water consumption of fly ash with different salinities. Furthermore, the salinity of the fly ash slurry and the fly ash filtrate can be made not to be affected by the fluctuation of fly ash composition, and the water consumption in the fly ash water washing process can be effectively reduced, and the energy consumption and operation cost can be reduced.

[0004] The second aspect of the present invention provides a fly ash water washing system.

[0005] The fly ash water washing method provided by the present invention includes:

[0006] Setting the target viscosity of the fly ash slurry and the target salinity of the fly ash slurry;

[0007] Based on the target viscosity of the fly ash slurry, the target salinity of the fly ash slurry, the salt content of the fly ash, and the salinity of the pulping liquid, calculating the pulping ratio of the fly ash, the pulping liquid, and the clear water;

[0008] Making the fly ash slurry according to the pulping ratio.

[0009] According to the fly ash water washing method provided by the present invention, after the step of making the fly ash slurry, it further includes:

[0010] When the actual viscosity of the fly ash slurry is lower than the target viscosity and the actual salinity of the fly ash slurry is higher than the target salinity, based on the target viscosity of the fly ash slurry, the target salinity of the fly ash slurry, the actual viscosity of the fly ash slurry, and the actual salinity of the fly ash slurry, adding the clear water and the fly ash to the fly ash slurry.

[0011] According to the fly ash washing method provided by the present invention, after the step of making the fly ash slurry, the following steps are further included:

[0012] Perform solid-liquid separation on the fly ash slurry through a first plate and frame filter press to obtain a fly ash filter cake and fly ash filtrate.

[0013] According to the fly ash washing method provided by the present invention, after the step of obtaining the fly ash filter cake and fly ash filtrate, the following steps are further included:

[0014] When the actual viscosity of the fly ash slurry is higher than the target viscosity and the actual salinity of the fly ash slurry is lower than the target salinity, based on the target viscosity of the fly ash slurry, the target salinity of the fly ash slurry, the actual salinity of the fly ash filtrate, the salt content of the fly ash, and the salinity of the slurry-making liquid, calculate the slurry-making ratio of the fly ash filtrate, the fly ash, the slurry-making liquid, and the clear water, and input the fly ash filtrate into the slurry preparation tank according to the slurry-making ratio for re-preparing the slurry.

[0015] According to the fly ash washing method provided by the present invention, after the step of obtaining the fly ash filter cake and fly ash filtrate, in-situ multi-stage countercurrent washing of the fly ash filter cake is further included;

[0016] Among them, the in-situ multi-stage countercurrent washing of the fly ash includes the following steps:

[0017] Based on the salinity values of the washing water in each first washing water tank, classify all the first washing water tanks from high salinity to low salinity, and let the first washing water tanks with high salinity to the first washing water tanks with low salinity wash the fly ash filter cake in sequence.

[0018] According to the fly ash washing method provided by the present invention, the step of classifying all the first washing water tanks from high salinity to low salinity based on the salinity values of the washing water in each first washing water tank, and letting the first washing water tanks with high salinity to the first washing water tanks with low salinity wash the fly ash filter cake in sequence includes:

[0019] The washing water obtained after washing the fly ash filter cake with the washing water in the nth first washing water tank enters the (n - 1)th first washing water tank. When the liquid level of the nth first washing water tank drops to the set target value, the in-situ washing at the nth stage ends;

[0020] Among them, the washing water obtained after washing the fly ash filter cake with the washing water in the first first washing water tank is used to form the slurry-making liquid.

[0021] According to the fly ash washing method provided by the present invention, after the washing water in the last-stage first washing water tank washes the fly ash filter cake, the last-stage first washing water tank is replenished with the clear water, and all the first washing water tanks are re-classified from high salinity to low salinity based on the salinity values of the washing water in each first washing water tank.

[0022] According to the fly ash washing method provided by the present invention, after the step of making the fly ash slurry, before the step of performing solid-liquid separation on the fly ash slurry by the first plate and frame filter press, the following steps are further included:

[0023] Adding a precipitant to the fly ash slurry according to a preset target to perform rough decalcification on the fly ash slurry.

[0024] According to the fly ash washing method provided by the present invention, the precipitant includes one of sulfates, carbonates, phosphates, and hydroxides.

[0025] According to the fly ash washing method provided by the present invention, when the precipitant is one of sulfates and hydroxides, adding a precipitant to the fly ash filtrate again according to a preset target to perform fine decalcification on the fly ash filtrate to obtain a decalcified slurry;

[0026] Performing solid-liquid separation on the decalcified slurry by a second plate and frame filter press to obtain a decalcified filter cake and a decalcified filtrate, and performing in-situ multi-stage countercurrent washing on the decalcified filter cake.

[0027] The fly ash washing system provided by the present invention includes a fly ash bin, a liquid storage tank, a clear water tank, and a slurry preparation tank. The inlet of the slurry preparation tank is respectively connected to the fly ash bin, the liquid storage tank, and the clear water tank. The fly ash bin is used to provide fly ash, the liquid storage tank is used to provide the slurry for preparation, the clear water tank is used to provide clear water, and the slurry preparation tank is used to prepare the fly ash slurry;

[0028] A viscometer and a salinity meter are provided in the slurry preparation tank. The salinity meter and the viscometer are used to detect the actual viscosity and actual salinity of the fly ash slurry in the slurry preparation tank.

[0029] According to the fly ash washing system provided by the present invention, it further includes a fly ash in-situ washing assembly;

[0030] The fly ash in-situ washing assembly includes:

[0031] A first plate and frame filter press, with the inlet connected to the outlet of the slurry preparation tank and the outlet connected to the inlet of the liquid storage tank;

[0032] A first washing water pump, with the outlet connected to the first plate and frame filter press;

[0033] Multiple first washing water tanks, the outlet of each of the first washing water tanks is connected to the inlet of the first washing water pump, and the inlet of each of the first washing water tanks is connected to the outlet of the first plate and frame filter press and is also connected to the outlet of the clean water tank.

[0034] The fly ash water washing system provided by the present invention further includes a fly ash filtrate treatment assembly;

[0035] The fly ash filtrate treatment assembly includes:

[0036] A precipitant storage tank, the outlet of which is connected to the inlet of the slurry preparation tank;

[0037] Multiple precipitation reaction tanks, the inlet of each of the precipitation reaction tanks is connected to the outlet of the precipitant storage tank and is also connected to the outlet of the first plate and frame filter press;

[0038] A second plate and frame filter press, the inlet of which is connected to the outlet of each of the precipitation reaction tanks, and the outlet of which is connected to the inlet of the liquid storage tank;

[0039] A second washing water pump, the outlet of which is connected to the inlet of the second plate and frame filter press;

[0040] Multiple second washing water tanks, the outlet of each of the second washing water tanks is connected to the inlet of the second washing water pump, and the inlet of each of the second washing water tanks is connected to the outlet of the second plate and frame filter press and is also connected to the outlet of the clean water tank.

[0041] In the fly ash water washing method provided by the embodiment of the present invention, by setting the target viscosity and target salinity and calculating the pulping ratio according to the salt content of the fly ash and the salinity of the pulping liquid, the salinity of the fly ash slurry can be accurately controlled. In this way, when the fly ash slurry is squeezed and filtered, fly ash filtrate with a preset salinity can be obtained; in the salt water mixture, the larger the proportion of the salt component, that is, the higher the salinity, the easier the salt crystallization process will be in the subsequent water treatment process. Based on this, the higher the salinity of the fly ash filtrate, the lower the water treatment difficulty of the fly ash filtrate. The salinity of the fly ash filtrate is directly related to the salinity of the fly ash slurry. Controlling the salinity of the fly ash slurry can control the salinity of the fly ash filtrate, which can effectively reduce the subsequent water treatment difficulty of the fly ash slurry.

[0042] Compared with the prior art, the fly ash washing method provided by the embodiment of the present invention can be guided by the target salinity. Before making the fly ash slurry, that is, at the stage of the raw material ratio, the slurry ratio of the fly ash slurry raw materials can be controlled in advance according to the preset requirements. In this way, the water consumption of fly ash with different salinities can be flexibly controlled, and further, the salinities of the fly ash slurry and the fly ash filtrate can be made unaffected by the fluctuations of the fly ash composition. When the salt content of the fly ash is low, the ratio of the pulping water can be increased and the ratio of the fresh water can be decreased, so as to obtain a fly ash slurry that meets the salinity. In this way, not only can the salinity of each fly ash slurry meet the standard and the composition of the fly ash filtrate be stabilized, but also the water consumption in the process of preparing the fly ash slurry can be effectively reduced, and the energy consumption and operation cost can be lowered; from the perspective of material balance, the greater the salinity in the fly ash filtrate, the smaller the water content. By controlling the salinity of the fly ash filtrate, the water consumption in the fly ash washing process can be effectively reduced.

[0043] Secondly, the fly ash washing system provided by the embodiment of the present invention can control the composition of the fly ash slurry based on the salinity at the raw material stage by precisely controlling the pulping ratio of the fly ash slurry. The water consumption in the subsequent fly ash slurry washing process can be directly determined. In this way, it is not necessary to perform feedback adjustment on the water consumption of the current batch of fly ash based on the water consumption of the previous batch of fly ash. In this way, the water consumption of the current batch of fly ash can be made independent of the water consumption of the previous batch of fly ash, and the problem of large hysteresis in feedback adjustment can be solved, thereby effectively reducing the waste of water resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0045] Figure 1 It is a schematic diagram of the principle of the fly ash washing method provided by the embodiment of the present invention.

[0046] Figure 2 It is a system structure diagram of the fly ash washing system provided by the embodiment of the present invention.

[0047] Figure 3 It is a flow schematic diagram of the fly ash washing method provided by the embodiment of the present invention.

[0048] Reference Signs:

[0049] 100: Fly ash bin; 110: Liquid storage tank; 120: Fresh water tank; 130: Slurry preparation tank; 200: First plate and frame filter press; 210: First washing water pump; 220: First washing water tank; 230: Fly ash filtrate tank; 300: Filter cake pulping tank; 310: Crusher; 320: Dryer; 330: Finished product ash bin; 400: Precipitant storage tank; 410: Precipitation reaction tank; 420: Second plate and frame filter press; 430: Second washing water pump; 440: Second washing water tank; 450: Storage bin; 500: Water treatment component. Detailed implementation manners

[0050] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without creative efforts shall fall within the protection scope of the present invention.

[0051] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly defined and limited, the terms "connected" and "connected to" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0052] In the embodiments of the present application, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "below" and "beneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0053] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the embodiments of this application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0054] The resource utilization of municipal solid waste incineration fly ash is an important way and development trend for the construction of a waste-free city. Currently, the technologies for fly ash resource utilization mainly include co-disposal in cement kilns, high-temperature melting, and high-temperature sintering, etc. Since fly ash contains 10 - 30% of high-concentration soluble salts, problems such as equipment corrosion, system scaling and blockage, and unqualified product quality are likely to occur during the resource utilization process. Therefore, a water washing desalination technology needs to be adopted to wash and desalt the fly ash.

[0055] The current fly ash water washing desalination technology mainly adopts a three-stage countercurrent water washing technology. Specifically, first, the municipal solid waste incineration fly ash is crushed, and then according to the mass ratio of fly ash to pulping water, the fly ash and pulping water are stirred to make a fly ash slurry. Then, the fly ash slurry is subjected to solid-liquid separation. The solid phase after solid-liquid separation is washed three times with water to obtain washed fly ash and washing water. Finally, the washed fly ash is dried to obtain the fly ash product, and the liquid phase after solid-liquid separation will be discharged after water treatment.

[0056] However, the composition of fly ash in different batches fluctuates greatly. When the salinity of fly ash is low, the salinity of the fly ash filtrate is also low, which will not only cause a large waste of water resources but also impose a huge burden on subsequent water treatment; when the salinity of fly ash is high, a large amount of water needs to be added for desalination during the three-stage washing process, which will also cause a great waste of water resources.

[0057] Secondly, in the prior art, the water consumption of the current batch of fly ash in the washing process is adjusted by feedback according to the water consumption of the previous batch of fly ash. However, the washing time of fly ash is relatively long, which will lead to a large lag in the feedback adjustment. If the composition difference between the front and back batches of fly ash is large, it will not only cause a large waste of water resources but also have a great impact on the washing effect of fly ash.

[0058] Figure 1 is a schematic diagram of the principle of the fly ash water washing method provided by an embodiment of the present invention; Figure 2 is a system structure diagram of the fly ash water washing system provided by an embodiment of the present invention.

[0059] Refer toFigure 1 and Figure 2 In the first aspect of the embodiments of the present invention, a fly ash washing system is provided. The fly ash washing system includes a slurry preparation component, a fly ash washing component, a fly ash drying and treatment component, a fly ash filtrate treatment component, a precipitation drying and treatment component, and a water treatment component 500. The slurry preparation component is used to prepare fly ash slurry. The fly ash washing component is used to perform multi-stage countercurrent washing on the fly ash slurry and obtain fly ash filtrate and fly ash filter cake. The fly ash drying and treatment component is used to dry the fly ash filter cake. The fly ash filtrate treatment component is used to perform calcium precipitation treatment on the fly ash filtrate and obtain a demineralized filter cake and demineralized filtrate. The precipitation drying and treatment component is used to dry the demineralized filter cake. The water treatment component 500 is used to perform water treatment on the demineralized filtrate.

[0060] Among them, the slurry preparation component includes a fly ash bin 100, a liquid storage tank 110, a fresh water tank 120, and a slurry preparation tank 130. The fly ash bin 100 is used to store the pretreated and pulverized fly ash. The liquid storage tank 110 is used to store the liquid phase derived from the fly ash washing component and the fly ash filtrate treatment component, that is, the slurry for making (see details later). The fresh water tank 120 is used to provide fresh water. In some alternative embodiments, a live water source can also be used to replace the fresh water tank 120. The slurry preparation tank 130 is used to prepare slurry. The slurry preparation tank 130 includes components such as a tank body and a stirring device. The specific structure of the slurry preparation tank 130 can be designed adaptively with reference to the prior art.

[0061] The inlet of the slurry preparation tank 130 is respectively connected to the outlets of the fly ash bin 100, the liquid storage tank 110, and the fresh water tank 120 to facilitate obtaining the raw materials for slurry preparation. A viscometer and a salinometer are provided in the slurry preparation tank 130. The viscometer is used to detect the actual viscosity of the fly ash slurry, and the salinometer is used to detect the actual salinity of the fly ash slurry. The specific settings of the viscometer and the salinometer can be designed adaptively according to the prior art.

[0062] During use, the target viscosity and target salinity of the fly ash slurry can be preset in advance; then, calculations are performed based on the target viscosity and target salinity to obtain the raw material ratio required for the fly ash slurry to reach the target viscosity and target salinity, that is, the slurry preparation ratio of fly ash, slurry for making, and fresh water; finally, appropriate amounts of fly ash, slurry for making, and fresh water are added to the slurry preparation tank 130 according to the slurry preparation ratio, and the stirring device of the slurry preparation tank 130 is started for stirring to obtain the fly ash slurry.

[0063] It should be noted that since the salinity of the pulping liquid has a certain degree of uncertainty, which may affect the result of the pulping ratio, the salinity of the pulping liquid also needs to be measured in advance and incorporated into the calculation process of the pulping ratio. It should also be noted that the target viscosity can be adaptively designed according to the working requirements of the first plate and frame filter press 200; the target salinity can be adaptively selected according to the water output of the fly ash slurry in historical data, that is, the amount of fly ash filtrate obtained after the fly ash slurry is filtered, and the ease of salt crystallization precipitation in the salt water mixture.

[0064] It can be understood that in the salt water mixture, the greater the proportion of the salt component, that is, the greater the salinity, the easier the salt crystallization precipitation process will be in the subsequent water treatment process. In other words, the higher the salinity of the fly ash filtrate, the lower the water treatment difficulty of the fly ash filtrate. The salinity of the fly ash filtrate is directly related to the salinity of the fly ash slurry. By controlling the salinity of the fly ash slurry, the salinity of the fly ash filtrate can be controlled. In the fly ash washing system provided by the embodiment of the present invention, by setting the liquid storage tank 110 and the clean water tank 120, and arranging a viscometer and a salinity meter in the slurry preparation tank 130, in this way, during the preparation process of the fly ash slurry, the viscosity and salinity in the slurry preparation tank 130 can be detected in real time through the viscometer and the salinity meter. Based on this, the amounts of fly ash, pulping liquid, and clean water actually input into the slurry preparation tank 130 can be adjusted in a timely manner, so as to ensure that the obtained fly ash slurry meets the requirements of the preset viscosity and preset salinity; in this way, when the fly ash slurry is squeezed and filtered, a fly ash filtrate meeting the preset salinity can be obtained, thereby effectively reducing the subsequent water treatment difficulty of the fly ash slurry.

[0065] Compared with the prior art, in the fly ash washing system provided by the embodiment of the present invention, the target salinity can be used as a guide. Before the production of the fly ash slurry, that is, in the raw material ratio stage, the slurry ratio of the fly ash slurry raw materials can be controlled in advance according to the preset requirements. In this way, the salinities of the fly ash slurry and the fly ash filtrate can be made not affected by the fluctuations of the fly ash composition. When the salt content of the fly ash is low, the ratio of the pulping water can be increased and the ratio of the clean water can be decreased, so as to obtain a fly ash slurry meeting the salinity requirement. In this way, not only can it be ensured that the salinity of each fly ash slurry meets the standard, but also the water consumption in the fly ash slurry preparation process can be effectively reduced; from the perspective of material balance, the greater the salinity in the fly ash filtrate, the smaller the water content. By controlling the salinity of the fly ash filtrate, the water consumption in the fly ash washing process can be effectively reduced.

[0066] Secondly, the fly ash washing system provided by the embodiments of the present invention can control the composition of the fly ash slurry based on salinity at the raw material stage. In this way, the water consumption during the subsequent washing process of the fly ash slurry can be directly determined, and there is no need to perform feedback adjustment on the water consumption of the current batch of fly ash based on the water consumption of the previous batch of fly ash. This can make the water consumption of the current batch of fly ash independent of the water consumption of the previous batch of fly ash, and can solve the problem of large lag in feedback adjustment, thereby effectively reducing water resource waste.

[0067] Refer to Figure 1 and Figure 2 In an optional embodiment of the present invention, the in-situ fly ash washing assembly includes a first plate and frame filter press 200, a first washing water pump 210, a fly ash filtrate tank 230, and a plurality of first washing water tanks 220. In the embodiments of the present invention, 10 first washing water tanks 220 are taken as an example for illustration.

[0068] The inlet of the first plate and frame filter press 200 is connected to the outlet of the slurry preparation tank 130, and the outlet of the first plate and frame filter press 200 is respectively connected to the liquid storage tank 110 and the fly ash filtrate tank 230. The washing water obtained after washing the fly ash filter cake with the washing water in the first washing water tank 220 of the first stage in the multi-stage countercurrent washing can be used to form the preparation slurry, and enters the liquid storage tank 110 through the outlet of the first plate and frame filter press 200 for storage, for use in the fly ash treatment of the next batch.

[0069] The outlet of the first washing water pump 210 is connected to the inlet of the first plate and frame filter press 200. The outlet of each first washing water tank 220 is connected to the inlet of the first washing water pump 210, and the inlet of each first washing water tank 220 is connected to the outlet of the first plate and frame filter press 200 and the outlet of the clean water tank 120. For the specific washing process of the in-situ fly ash washing assembly, please refer to the process of multi-stage countercurrent washing in the following text. Among them, the fly ash filtrate tank 230 can send the fly ash filtrate with qualified salinity to the fly ash filtrate treatment assembly for treatment, and can also send the fly ash filtrate with unqualified salinity into the slurry preparation tank 130 as the raw material for the preparation of the fly ash slurry of the next batch, so as to realize the increase of the salinity of the fly ash filtrate. The specific implementation method is described in detail in the following text.

[0070] Refer to Figure 1 and Figure 2 It can be understood that the setting of the first plate and frame filter press 200 and the setting of the plurality of first washing water tanks 220 can achieve the effect of traditional multi-stage countercurrent washing with a short process and low cost. Compared with the elution method of three-stage elution in the prior art, during the process of washing fly ash, the fly ash washing system provided by the embodiments of the present invention can greatly reduce the total amount of wastewater, thereby greatly reducing the water treatment load and the evaporation amount of wastewater in subsequent evaporation and crystallization, and thus greatly reducing the operation energy consumption and cost; at the same time, it can also increase the salinity of the washing water, and further increase the salinity of the preparation slurry.

[0071] Refer to Figure 1 and Figure 2 In an alternative embodiment of the present invention, the fly ash drying and processing assembly includes a crusher 310, a dryer 320, a finished ash bin 330, and a filter cake pulping tank 300. The inlet of the crusher 310 is connected to the outlet of the first plate and frame filter press 200. The outlet of the crusher 310 is respectively connected to the dryer 320 and the filter cake pulping tank 300. The outlet of the dryer 320 is connected to the inlet of the finished ash bin 330. The outlet of the filter cake pulping tank 300 is connected to the inlet of the slurry preparation tank 130.

[0072] The fly ash filter cake obtained by the first plate and frame filter press 200 enters the crusher 310 for crushing to obtain fine fly ash particles. If the fly ash filter cake is a qualified product, the fine fly ash particles enter the dryer 320 for drying. The fly ash finished product obtained after drying is stored in the finished ash bin 330 for use in the production of building materials such as cement. When the fly ash filter cake is an unqualified product, the fine fly ash particles enter the filter cake pulping tank 300 for pulping, and after pulping, they enter the slurry preparation tank 130 for slurry preparation.

[0073] It should be noted that the cleanliness of the fly ash filter cake can be judged by detecting the salinity of the pressing filtrate after the last water wash of the fly ash filter cake. When the salinity of the pressing filtrate after the last water wash of the fly ash filter cake is qualified, it can represent that the fly ash filter cake is a qualified product. When the salinity of the pressing filtrate after the last water wash of the fly ash filter cake is unqualified, it can represent that the fly ash filter cake is an unqualified product.

[0074] It can be understood that by setting up the fly ash drying and processing assembly, the fly ash filter cake can be effectively processed and reused, which can greatly improve the utilization efficiency of resources. At the same time, the fly ash drying and processing assembly can also well control the qualification of the fly ash filter cake, and can timely put the unqualified fly ash filter cake into the slurry preparation tank 130 for secondary treatment, which can effectively ensure the quality of the fly ash finished product.

[0075] Refer to Figure 1 and Figure 2, in an alternative embodiment of the present invention, the fly ash filtrate treatment assembly includes a precipitant storage tank 400, a second plate and frame filter press 420, a second washing water pump 430, a plurality of precipitation reaction tanks 410, and a plurality of second washing water tanks 440; the outlet of the precipitant storage tank 400 is respectively connected to the inlet of the slurry preparation tank 130 and the inlet of each precipitation reaction tank 410. The precipitant storage tank 400 is used to provide a precipitant, and the precipitant includes one of sulfates, carbonates, phosphates, and hydroxides. In this article, a sodium sulfate solution in sulfates is taken as an example. The calcium ion content in the fly ash slurry is relatively high. During the preparation process of the fly ash slurry, according to a preset target, a sodium sulfate solution can be added into the slurry preparation tank 130. The sodium sulfate solution will react with the calcium ions in the fly ash slurry to form calcium sulfate precipitation.

[0076] However, since calcium sulfate is slightly soluble and the accuracy of single-stage decalcification is relatively low and difficult to control, the fly ash filtrate after filtering the fly ash slurry can be subjected to secondary fine decalcification through a plurality of precipitation reaction tanks 410. Specifically, when the fly ash filtrate enters the plurality of precipitation reaction tanks 410 through the fly ash filtrate tank 230, a sodium sulfate solution can be added to each of the plurality of precipitation reaction tanks 410 for precipitation reaction. Each precipitation reaction tank 410 includes a calcium ion concentration monitor, a stirrer, and a liquid level gauge. To ensure the stability of the gypsum reaction and the volume of gypsum agglomeration, the plurality of precipitation reaction tanks 410 can be controlled in an intermittent operation mode. Specifically, after metering and adding the fly ash filtrate and sodium sulfate during the stirring process, when the calcium ion concentration is within the set range, the stirring can be stopped for gypsum aging to increase the particle size.

[0077] When the gypsum reaction is completed, the decalcified slurry, that is, the gypsum slurry, can be obtained. After the decalcified slurry enters the second plate and frame filter press 420, it will be separated into a decalcified filter cake (gypsum filter cake) and a decalcified filtrate (gypsum filtrate). The plurality of second washing water tanks 440, the second plate and frame filter press 420, and the second washing water pump 430 can perform in-situ multi-stage countercurrent washing of the decalcified filter cake. For the specific in-situ multi-stage countercurrent washing process of decalcification, please refer to the following text.

[0078] The precipitation drying treatment assembly can dry and crush the decalcified filter cake after washing, and then the decalcified filter cake can be stored and processed by the storage bin 450. Specifically, reference can be made to the fly ash drying treatment assembly in the previous text, which will not be elaborated here; the water treatment assembly 500 can perform water treatment on the decalcified filtrate (gypsum filtrate). The specific structure and method of water treatment can refer to the prior art, which will not be elaborated here.

[0079] Among them, the washing water obtained by washing the decalcified filter cake with the washing water in the first-stage first washing water tank 220 during the in-situ multi-stage countercurrent washing of decalcification can be used to form the preparation slurry, and specifically, it can be adaptively set according to the actual situation.

[0080] Refer to Figure 1 and Figure 2 It can be understood that the fly ash filtrate treatment component provided in the embodiment of the present invention can perform two-stage decalcification treatment on fly ash, namely rough decalcification and fine decalcification. Dividing the decalcification treatment into two stages can effectively improve the error tolerance rate of the decalcification treatment, avoid the pollution of the precipitant and the waste of the precipitant caused by adding too much precipitant, and also avoid the problems of insufficient precipitation or incomplete decalcification caused by adding too little precipitant.

[0081] In addition, by combining multiple precipitation reaction tanks 410, precise control of the calcium ion concentration in the gypsum slurry can be achieved, which can save the dosage of chemicals to the greatest extent and stabilize the composition of the gypsum filtrate. At the same time, by controlling the rotation speed of the precipitation reaction tank 410, the functions of the reactor and the aging device can be combined into one, thereby reducing equipment investment and shortening the process flow. In addition, the in-situ multi-stage countercurrent water washing for decalcification adopts a single plate and frame filter press combined with a multi-stage simple water washing device, which can achieve the effect of traditional multi-stage countercurrent water washing with a short process and low cost, and at the same time can greatly reduce the water consumption for decalcification washing.

[0082] Figure 3 is a schematic flow chart of the fly ash water washing method provided in the embodiment of the present invention.

[0083] Refer to Figures 1 to 3 In the second aspect of the embodiment of the present invention, a fly ash water washing method is provided, which specifically includes the following steps.

[0084] S100: Set the target viscosity and target salinity of the fly ash slurry.

[0085] Specifically, when setting the target viscosity, the requirements for the transmission fluidity of the fly ash slurry between the slurry preparation tank 130 and the first plate and frame filter press 200 and the water consumption and other issues need to be considered, and it can be adaptively set with reference to the prior art; the target salinity can be adaptively set according to the water output of the fly ash slurry in historical data, that is, the amount of fly ash filtrate obtained after the fly ash slurry is filtered, and the difficulty of salt crystallization precipitation in the salt water mixture.

[0086] S200: Calculate the slurry preparation ratio of fly ash, slurry-making liquid and clear water based on the target viscosity of the fly ash slurry, the target salinity of the fly ash slurry, the salt content of the fly ash and the salinity of the slurry-making liquid.

[0087] Specifically, the actual viscosity and actual salinity of the fly ash slurry can be detected by a viscometer and a salinity meter provided in the slurry preparation tank 130, and then calculated according to the target viscosity and target salinity to obtain the raw material ratio required for the fly ash slurry to reach the target viscosity and target salinity, that is, the slurry preparation ratio of fly ash, slurry-making liquid and clear water.

[0088] S300: Obtain the fly ash slurry according to the slurry preparation ratio.

[0089] Specifically, appropriate amounts of fly ash, pulping liquid, and fresh water are added to the slurry preparation tank 130 according to the pulping ratio, and the stirring device of the slurry preparation tank 130 is started for stirring to obtain fly ash slurry.

[0090] Refer to Figures 1 to 3 It can be understood that in the salt water mixture, the greater the proportion of salt components, that is, the greater the salinity, the easier the salt crystallization process will be in the subsequent water treatment process. Based on this, the higher the salinity of the fly ash filtrate, the lower the water treatment difficulty of the fly ash filtrate. The salinity of the fly ash filtrate is directly related to the salinity of the fly ash slurry. Controlling the salinity of the fly ash slurry can control the salinity of the fly ash filtrate. In the fly ash washing method provided by the embodiment of the present invention, by setting the target viscosity and target salinity, and calculating the pulping ratio according to the salt content of the fly ash and the salinity of the pulping liquid (formed by the subsequent washing water, which can be replaced by fresh water when washing the first batch of fly ash), the salinity of the fly ash slurry can be accurately controlled. In this way, when the fly ash slurry is subjected to extrusion filtration, fly ash filtrate with a preset salinity can be obtained, which can effectively reduce the subsequent water treatment difficulty of the fly ash slurry.

[0091] Compared with the prior art, the fly ash washing method provided by the embodiment of the present invention can use the target salinity as a guide. Before making the fly ash slurry, that is, at the stage of raw material ratio, the slurry ratio of the fly ash slurry raw materials can be controlled in advance according to the preset requirements. In this way, the water consumption of fly ash with different salinities can be flexibly controlled, and further, the salinities of the fly ash slurry and the fly ash filtrate are not affected by the fluctuation of the fly ash composition; when the salt content of the fly ash is low, the ratio of the pulping water can be increased and the ratio of fresh water can be reduced to obtain a fly ash slurry that meets the salinity. In this way, not only can the salinity of each fly ash slurry meet the standard and the composition of the fly ash filtrate be stabilized, but also the water consumption in the fly ash slurry preparation process can be effectively reduced, and the energy consumption and operation cost can be reduced; from the perspective of material balance, the greater the salinity in the fly ash filtrate, the smaller the water content. Controlling the salinity of the fly ash filtrate can effectively reduce the water consumption in the fly ash washing process.

[0092] Secondly, in the fly ash washing system provided by the embodiment of the present invention, by accurately controlling the pulping ratio of the fly ash slurry, the composition of the fly ash slurry can be controlled based on the salinity at the raw material stage. The water consumption in the subsequent fly ash slurry washing process can be directly determined, so that it is not necessary to perform feedback adjustment on the water consumption of the current batch of fly ash based on the water consumption of the previous batch of fly ash. In this way, the water consumption of the current batch of fly ash can be freed from the influence of the water consumption of the previous batch of fly ash, and the problem of large hysteresis in feedback adjustment can be solved, thereby effectively reducing the waste of water resources.

[0093] Refer to Figures 1 to 3, in an alternative embodiment of the present invention, after the step of S300, it further includes that when the actual viscosity of the fly ash slurry is lower than the target viscosity and the actual salinity of the fly ash slurry is higher than the target salinity; based on the target viscosity of the fly ash slurry, the target salinity of the fly ash slurry, the actual viscosity of the fly ash slurry, and the actual salinity of the fly ash slurry, an appropriate amount of clear water and fly ash is added to the fly ash slurry. It can be understood that when a gap occurs between the fly ash slurry and the preset target due to unexpected circumstances, this step can be used as a remedial measure after the fly ash slurry is formulated, thereby ensuring the salinity of the fly ash slurry.

[0094] Refer to Figures 1 to 3 , in an alternative embodiment of the present invention, after the step of S300, it further includes solid-liquid separation of the fly ash slurry by a first plate and frame filter press 200 to obtain fly ash filter cake and fly ash filtrate. Specifically, the inlet of the first plate and frame filter press 200 is connected to the outlet of the slurry preparation tank 130. The first plate and frame filter press 200 can squeeze and filter the fly ash slurry, thereby realizing solid-liquid separation. The solid phase is intercepted by the filter cloth in the first plate and frame filter press 200 to form a fly ash filter cake, and the liquid phase forms fly ash filtrate. The fly ash filtrate enters the fly ash filtrate treatment component for treatment.

[0095] Refer to Figures 1 to 3 , in an alternative embodiment of the present invention, after the step of obtaining the fly ash filter cake and fly ash filtrate, it further includes: when the actual viscosity of the fly ash slurry is higher than the target viscosity and the actual salinity of the fly ash slurry is lower than the target salinity; based on the target viscosity of the fly ash slurry, the target salinity of the fly ash slurry, the actual salinity of the fly ash filtrate, the salt content of the fly ash, and the salinity of the slurry-making liquid, calculate the slurry-making ratio of the fly ash filtrate, fly ash, slurry-making liquid, and clear water, and put the fly ash filtrate obtained in the previous step into the slurry preparation tank 130 according to the slurry-making ratio for re-slurry preparation.

[0096] It can be understood that this step is mainly aimed at the first batch of fly ash. When the salinity of the first batch of fly ash itself is low, it will cause the salinity of the fly ash filtrate to not meet the standard. In this case, if the fly ash filtrate is directly put into the subsequent treatment process, it will cause an unnecessary burden on the subsequent treatment; at the same time, since it is the first batch of fly ash, there is no washing water as the slurry-making liquid to supplement the salinity of the fly ash slurry. If more fly ash is added, although the salinity of the fly ash slurry will be increased, the distance between the viscosity of the fly ash slurry and the target viscosity will be farther. In this embodiment, by using the fly ash filtrate as the raw material for making slurry for the next batch of fly ash, since the fly ash filtrate has been washed, its salinity is relatively high. In this way, the salinity of the fly ash slurry can be increased on the premise of ensuring the viscosity of the fly ash slurry, thereby ensuring the salinity of the fly ash filtrate and reducing the difficulty of formulating the fly ash slurry at the same time.

[0097] In a specific embodiment, when the original salinity of the fly ash is extremely low, it is impossible to obtain fly ash slurry with qualified salinity only by adding fly ash; in other possible embodiments, the salinity of the slurry prepared by the subsequent primary washing water may also be low. In this case, it may also be impossible to obtain fly ash slurry that meets the requirements of salinity and viscosity only relying on the salinity of the slurry and fly ash; in this embodiment, by first performing solid-liquid separation on the fly ash slurry with qualified viscosity but unqualified salinity, and then putting the fly ash filtrate obtained from the liquid phase into the next batch of fly ash pulping, in this way, even in this unexpected situation, the salinity of the fly ash filtrate can be fully guaranteed in this way. In other words, this method effectively improves the fault tolerance and versatility of the fly ash washing method.

[0098] Refer to Figures 1 to 3 , in an alternative embodiment of the present invention, after the steps of obtaining the fly ash filter cake and the fly ash filtrate, fly ash in-situ multi-stage countercurrent washing of the fly ash filter cake is further included; wherein, the fly ash in-situ multi-stage countercurrent washing includes the following steps: based on the salinity values of the washing water in each first washing water tank 220, all the first washing water tanks 220 are classified from high to low, and each level of the first washing water tanks 220 sequentially washes the fly ash filter cake.

[0099] Specifically, n-level washing devices are provided, such as 10 levels. Each level of the washing device includes a first washing water tank 220, a liquid level gauge, a salinity meter, an inlet pipeline and a valve, and an outlet pipeline and a valve. The outlet pipelines of each first washing water tank 220 converge into one outlet pipeline, and the outlet pipeline is connected to the inlet of the first washing water pump 210. The outlet of the first washing water pump 210 is connected to the filter cake washing inlet of the first plate and frame filter press 200 through a pipeline. A salinity meter is provided at the filter cake washing outlet pipeline of the first plate and frame filter press 200 and is connected to the inlet pipeline valve of each first washing water tank 220.

[0100] The basic process of the fly ash in-situ multi-stage countercurrent washing is as follows: First, each first washing water tank 220 is sorted according to the salinity data measured by the salinity meter in the tank from high to low. The first washing water tank 220 with the highest salinity is the first-level first washing water tank 220. The washing water in the first-level first washing water tank 220 is pumped into the first plate and frame filter press 200 by the first washing water pump 210 to perform in-situ washing on the fly ash filter cake. The washing water with higher salinity obtained after washing the fly ash filter cake is used for slurry preparation, that is, the aforementioned slurry is formed. When the liquid level of the first-level first washing water tank 220 drops to the set target value, the first-level in-situ washing ends. The target value is ideally 0, but considering the actual situation of the tank body and other objective factors, the target value can be adaptively set.

[0101] Then, the washing water in the first washing water tank 220 of the second stage is pumped into the first plate and frame filter press 200 through the first washing water by the first washing water pump 210 for in-situ washing of the fly ash filter cake. The washing water with a higher salinity obtained after washing the fly ash filter cake then enters the first washing water tank 220 of the first stage. When the liquid level in the first washing water tank 220 of the second stage drops to the set target value, the in-situ washing of the second stage ends.

[0102] Then, the washing water in the first washing water tank 220 of the third stage is pumped into the first plate and frame filter press 200 through the first washing water by the first washing water pump 210 for in-situ washing of the fly ash filter cake. The washing water with a higher salinity obtained after washing the fly ash filter cake then enters the first washing water tank 220 of the second stage. When the liquid level in the first washing water tank 220 of the third stage drops to the set target value, the in-situ washing of the third stage ends.

[0103] And so on. The washing water in the first washing water tank 220 of the nth stage is pumped into the first plate and frame filter press 200 through the first washing water by the first washing water pump 210 for in-situ washing of the fly ash filter cake. The washing water with a higher salinity obtained after washing the fly ash filter cake then enters the first washing water tank 220 of the (n - 1)th stage. When the liquid level in the first washing water tank 220 of the nth stage drops to the set target value, the in-situ washing of the nth stage ends.

[0104] Finally, fresh water is replenished to the set liquid level in the first washing water tank 220 of the last stage, ending the process of in-situ multi-stage countercurrent washing of fly ash. It should be noted that when the fly ash in the in-situ multi-stage countercurrent washing of fly ash is the first batch, if there is no washing water from the previous batch to serve as the pulping liquid at this time, fresh water can be used instead. First, separate the solid and liquid of the fly ash slurry with qualified viscosity but unqualified salinity, and then use the separated fly ash filtrate as the raw material for pulping in the next batch for "salt increase". In addition, even if it is not the first batch of fly ash, when the salinity of the fly ash filtrate is unqualified (not reaching the concentration suitable for crystallization), the fly ash filtrate can also be washed again to increase the salinity of the fly ash filtrate. For the washing of the first batch of fly ash, fresh water can be filled in all the first washing water tanks 220. After multiple in-situ multi-stage countercurrent washings of fly ash, the washing water reaching the target salinity can be formed, and then used to form the pulping liquid.

[0105] It should also be noted that when the salinity of the washing water displayed by the salinity meter installed at the filter cake washing outlet of a first plate and frame filter press 200 is stably lower than a certain set value, it means that the in-situ washing of the filter cake ends early in the water washing process of this stage. At this time, clean water should be added to the first washing water tank 220 of this stage of water washing. The set value here can be adaptively set according to actual conditions. In an optional embodiment of the present invention, when the salinity of the washing water in each first washing water tank 220 is stable, it is necessary to sort the washing water again according to the salinity level to prepare for the next washing. Specifically, the order and number of washing levels can be automatically adjusted according to the washing effect in combination with the salinity, liquid level and algorithm, so as to maximize the washing efficiency and reduce the washing time and operating cost.

[0106] After the fly ash is washed with multi-stage countercurrent water in situ, the first plate-frame filter press 200 needs to perform the pressing operation again, pressurizing both sides of the fly ash filter cake in the first plate-frame filter press 200, and further discharging the residual water in the fly ash filter cake to reduce the moisture content of the fly ash filter cake. The discharged water forms the pressed filtrate, which is tested for salinity by a salinometer, and the pressed filtrate is added to the corresponding first washing water tank 220 according to the salinity value.

[0107] Then, after the fly ash filter cake is unloaded, it is crushed by crusher 310 to obtain fine fly ash particles. When the salinity of the pressed filtrate is lower than a certain set value (which may be the same as the set value when "in-situ washing ends early" in the previous text), it means that the washing effect of the fly ash filter cake is good. At this time, the crushed fly ash fine particles are fed into the dryer 320, and the finished fly ash is obtained after drying for the production of cement and other building materials.

[0108] When the salinity of the pressed filtrate is higher than a certain set value, it means that the washing effect of the fly ash filter cake is insufficient. At this time, the crushed fly ash fine particles are fed into the filter cake slurry tank 300, and mixed with the washing water to form a uniform slurry, and then the slurry is pumped into the slurry mixing tank for slurry mixing and fly ash washing again. By judging the salinity of the pressed filtrate, different response strategies such as drying or slurrying and re-washing can be automatically adopted for the washed fly ash filter cake according to the effect, so as to fully ensure the washing effect of the fly ash.

[0109] It can be understood that in the fly ash washing method provided by the embodiments of the present invention, through in-situ multi-stage countercurrent washing of fly ash, the water consumption in the fly ash washing process can be effectively reduced. Among them, the washing water with a higher salinity obtained after the first-stage fly ash filter cake washing can form the aforementioned slurry for slurry preparation, which can further improve the utilization efficiency of water resources in the fly ash washing process, thereby effectively reducing the difficulty of subsequent water treatment of fly ash filtrate. In addition, in-situ multi-stage countercurrent washing of fly ash can achieve the effect of traditional multi-stage countercurrent washing with a short process and low cost by using a single plate and frame filter press combined with a multi-stage simple washing device. At the same time, the total amount of wastewater can be greatly reduced, thereby greatly reducing the water treatment load and the evaporation amount of wastewater in subsequent evaporation and crystallization, and significantly reducing the operating energy consumption and cost.

[0110] In an alternative embodiment of the present invention, after the step of obtaining the fly ash slurry and before the step of performing solid-liquid separation on the fly ash slurry by the first plate and frame filter press 200, it further includes: adding a precipitant to the fly ash slurry according to a preset target to perform rough decalcification on the fly ash slurry. The specific process of rough decalcification can refer to the foregoing, and will not be elaborated herein. It can be understood that in the alternative embodiment of the present invention, adding a precipitant to the fly ash slurry for rough decalcification in the slurry preparation link can effectively reduce the control difficulty of subsequent decalcification, thereby achieving the purpose of reducing the dosage of chemicals, stabilizing the decalcification effect, and stabilizing the composition of the decalcification filtrate, creating control conditions for subsequent water treatment and evaporation crystallization, and reducing the operating cost.

[0111] In an alternative embodiment of the present invention, when the precipitant is one of sulfates and hydroxides, since the precipitates formed by sulfates and hydroxides are both slightly soluble substances, further fine decalcification is required. The precipitant can be added to the fly ash filtrate again according to a preset target to perform fine decalcification on the fly ash filtrate to obtain a decalcified slurry; the decalcified slurry is subjected to solid-liquid separation by the second plate and frame filter press 420 to obtain a decalcified filter cake and a decalcified filtrate, and the decalcified filter cake is subjected to in-situ multi-stage countercurrent washing for decalcification.

[0112] The embodiments of the present invention take a sodium sulfate solution as a precipitant for example and illustration. The following is the specific process of fly ash filtrate treatment.

[0113] The fly ash filtrate coming out of the first plate and frame filter press 200 is high-salt wastewater. At the same time, after the rough decalcification of the calcium ion concentration through slurry preparation, there is still a high residue. Therefore, it is necessary to continue to add a sodium sulfate solution to generate calcium sulfate precipitate with calcium ions and obtain a gypsum product.

[0114] The aged gypsum slurry is obtained as a decalcified slurry under the condition of re-stirring. The decalcified slurry is pumped into the second plate and frame filter press 420 for solid-liquid separation. The liquid phase in the decalcified slurry passes through the filter cloth under the action of the feed pressure to obtain gypsum filtrate, that is, decalcified filtrate, and the decalcified filtrate will enter the subsequent water treatment and evaporation crystallization process to achieve wastewater treatment.

[0115] The solid phase in the decalcified slurry is intercepted by the filter cloth inside the second plate and frame filter press 420 to form a gypsum filter cake, i.e., the decalcified filter cake. Since the decalcified filter cake contains high-concentration brine, it is necessary to further adopt in-situ multi-stage countercurrent washing for decalcification. This process is basically the same as the aforementioned in-situ multi-stage countercurrent washing process for fly ash.

[0116] The specific process is as follows: Set up n-stage washing devices, such as 10 stages. Among them, each stage of the washing device includes a second washing water tank 440, a liquid level gauge, a salinity meter, an inlet pipeline and a valve, and an outlet pipeline and a valve. The outlet pipelines of each second washing water tank 440 converge into one outlet pipeline, and the outlet pipeline is connected to the inlet of the second washing water pump 430. The outlet of the second washing water pump 430 is connected to the filter cake washing inlet of the second plate and frame filter press 420 through a pipeline. The filter cake washing outlet pipeline of the second plate and frame filter press 420 is provided with a salinity meter and is connected to the inlet pipeline valve of each second washing water tank 440.

[0117] The basic process of in-situ multi-stage countercurrent washing for decalcification is as follows: First, the salinity data measured by the salinity meters in each second washing water tank 440 are sorted according to high and low. The second washing water tank 440 with the highest salinity is the first-stage second washing water tank 440. The washing water in the first-stage second washing water tank 440 is pumped into the second plate and frame filter press 420 by the second washing water pump 430 to perform in-situ washing on the decalcified filter cake. The washing water with a higher salinity obtained after washing the decalcified filter cake is used for slurry preparation, that is, the aforementioned slurry for production is formed. When the liquid level in the first-stage second washing water tank 440 drops to the set target value, the first-stage in-situ washing ends. Among them, the ideal value of the target value is 0, but considering the actual situation of the tank body and other objective factors, the target value can be set adaptively.

[0118] Then, the washing water in the second-stage second washing water tank 440 is pumped into the second plate and frame filter press 420 by the second washing water pump 430 to perform in-situ washing on the decalcified filter cake. The washing water with a higher salinity obtained after washing the decalcified filter cake enters the first-stage second washing water tank 440. When the liquid level in the second-stage second washing water tank 440 drops to the set target value, the second-stage in-situ washing ends.

[0119] Then, the washing water in the third-stage second washing water tank 440 is pumped into the second plate and frame filter press 420 by the second washing water pump 430 to perform in-situ washing on the decalcified filter cake. The washing water with a higher salinity obtained after washing the decalcified filter cake enters the second-stage second washing water tank 440. When the liquid level in the third-stage second washing water tank 440 drops to the set target value, the third-stage in-situ washing ends.

[0120] And so on, the washing water in the nth-stage second washing water tank 440 is pumped into the second plate and frame filter press by the second washing water pump 430 for in-situ water washing of the demineralized filter cake. The washing water with a higher salinity obtained after washing the demineralized filter cake then enters the (n - 1)th-stage second washing water tank 440. When the liquid level in the nth-stage second washing water tank 440 drops to the set target value, the n-stage in-situ water washing ends.

[0121] Finally, fresh water is replenished to the last-stage second washing water tank 440 to the set liquid level, ending the process of in-situ multi-stage countercurrent water washing for demineralization.

[0122] It should be noted that when the salinity of the washing water shown by the salinity meter set at the filter cake washing outlet of a certain-stage second plate and frame filter press 420 is stably lower than a certain set value, it means that the in-situ washing of the filter cake ends prematurely. At this time, fresh water should be replenished to the second washing water tank 440 for this-stage water washing. This set value can be adaptively set according to the actual situation. When the salinity of the washing water in each second washing water tank 440 is stable, it is necessary to sort them again according to the salinity level for the next water washing.

[0123] After the in-situ multi-stage countercurrent water washing for demineralization, the second plate and frame filter press 420 performs a pressing operation. By applying pressure on both sides of the demineralized filter cake in the second plate and frame filter press 420, the residual moisture in the demineralized filter cake is further discharged to reduce the moisture content of the demineralized filter cake. The discharged moisture forms pressing filtrate, which is subjected to salinity detection by a salinity meter. The pressing filtrate is replenished to the corresponding first washing water tank 220 according to the salinity value. Then, the demineralized filter cake is subjected to drying and pulverizing treatment, or directly unloaded for use in the production of building materials such as cement.

[0124] It should be noted that the technical solutions in the various embodiments of the present invention can be combined with each other, but the basis for combination is that those skilled in the art can implement it. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist, that is, it does not fall within the protection scope of the present invention either.

[0125] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A fly ash washing method, characterized in that: include: Setting the target viscosity of the fly ash slurry, and setting the target salinity of the fly ash slurry based on the water output of the fly ash slurry and the difficulty of salt crystallization in the brine mixture in historical data; Calculating a slurry ratio of the fly ash, the slurry and clean water based on a target viscosity of the fly ash slurry, a target salinity of the fly ash slurry, a salt content of the fly ash and a salinity of the slurry; According to the slurry ratio, the fly ash slurry is prepared; When the actual viscosity of the fly ash slurry is lower than the target viscosity and the actual salinity of the fly ash slurry is higher than the target salinity, adding the clean water and the fly ash to the fly ash slurry based on the target viscosity of the fly ash slurry, the target salinity of the fly ash slurry, the actual viscosity of the fly ash slurry and the actual salinity of the fly ash slurry; Performing solid-liquid separation on the fly ash slurry by means of a first plate-frame filter press (200) to obtain a fly ash filter cake and a fly ash filtrate; In this step, for the first batch of fly ash, when the actual viscosity of the fly ash slurry is higher than the target viscosity and the actual salinity of the fly ash slurry is lower than the target salinity, the slurrying ratio of the fly ash filtrate, the fly ash, the slurrying liquid and the clean water is calculated based on the target viscosity of the fly ash slurry, the target salinity of the fly ash slurry, the actual salinity of the fly ash filtrate, the salt content of the fly ash and the salinity of the slurrying liquid, and the fly ash filtrate is put into the slurry mixing tank (130) for re-slurrying according to the slurrying ratio; After the step of obtaining the fly ash filter cake and the fly ash filtrate, the step further includes performing in-situ multi-stage countercurrent water washing on the fly ash filter cake; the in-situ multi-stage countercurrent water washing of the fly ash includes the following steps: Based on the salinity value of the washing water in each first washing water tank (220), all the first washing water tanks (220) are graded from high salinity to low salinity, so that the first washing water tanks (220) with high salinity to the first washing water tanks (220) with low salinity sequentially wash the fly ash filter cake with water; The step of grading all the first washing water tanks (220) from high salinity to low salinity based on the salinity value of the washing water in each first washing water tank (220), and washing the fly ash filter cake in sequence from the first washing water tank (220) with high salinity to the first washing water tank (220) with low salinity comprises: The washing water obtained after the fly ash filter cake is washed with washing water in the first washing water tank (220) of the nth stage enters the first washing water tank (220) of the n-1th stage. When the liquid level of the first washing water tank (220) of the nth stage drops to a set target value, the in-situ washing of the nth stage is terminated. The washing water obtained after washing the fly ash filter cake with the washing water in the first washing water tank (220) of the first stage is used to form the slurry.

2. The fly ash washing method according to claim 1, characterized in that: After the wash water in the last stage of the first wash water tank (220) washes the fly ash filter cake, the last stage of the first wash water tank (220) is replenished with the clean water, and based on the salinity value of the wash water in each of the first wash water tanks (220), all the first wash water tanks (220) are reclassified from high salinity to low salinity.

3. The fly ash washing method according to claim 1, characterized in that: After the step of preparing the fly ash slurry, and before the step of performing solid-liquid separation on the fly ash slurry by means of a first plate and frame filter press (200), the method further comprises: A precipitant is added to the fly ash slurry according to a preset target to roughly decalcify the fly ash slurry.

4. The fly ash washing method according to claim 3, characterized in that: The precipitating agent includes one of sulfate, carbonate, phosphate and hydroxide.

5. The fly ash washing method according to claim 4, characterized in that: When the precipitant is one of sulfate and hydroxide, the precipitant is added to the fly ash filtrate again according to a preset target, and the fly ash filtrate is finely decalcified to obtain a decalcified slurry; The decalcified slurry is subjected to solid-liquid separation by a second plate-frame filter press (420) to obtain a decalcified filter cake and a decalcified filtrate, and the decalcified filter cake is subjected to in-situ multi-stage countercurrent water washing.

6. A fly ash washing system, used for executing the fly ash washing method according to any one of claims 1 to 5, characterized in that: The invention comprises a fly ash bin (100), a liquid storage tank (110), a clean water tank (120), a slurry preparation tank (130) and a fly ash in-situ water washing assembly, wherein the inlet of the slurry preparation tank (130) is connected to the fly ash bin (100), the liquid storage tank (110) and the clean water tank (120), respectively; the fly ash bin (100) is used to provide fly ash, the liquid storage tank (110) is used to provide slurry making liquid, the clean water tank (120) is used to provide clean water, and the slurry preparation tank (130) is used to prepare fly ash slurry; The slurry mixing tank (130) is provided with a viscometer and a salinity meter, and the salinity meter and the viscometer are used to detect the actual viscosity and actual salinity of the fly ash slurry in the slurry mixing tank (130); The fly ash in-situ water washing component comprises: A first plate-frame filter press (200), the inlet of which is connected to the outlet of the slurry preparation tank (130), and the outlet of which is connected to the inlet of the liquid storage tank (110); A first washing water pump (210), the outlet of which is connected to the first plate and frame filter press (200); A plurality of first washing water tanks (220), the outlet of each of the first washing water tanks (220) being connected to the inlet of the first washing water pump (210), the inlet of each of the first washing water tanks (220) being connected to the outlet of the first plate and frame filter press (200), and being connected to the outlet of the clean water tank (120).

7. The fly ash washing system according to claim 6, characterized in that: Also included is a fly ash filtrate treatment component; The fly ash filtrate treatment component comprises: A precipitant storage tank (400), the outlet of which is connected to the inlet of the slurry preparation tank (130); A plurality of precipitation reaction tanks (410), wherein the inlet of each precipitation reaction tank (410) is connected to the outlet of the precipitant storage tank (400) and is connected to the outlet of the first plate and frame filter press (200); A second plate-frame filter press (420), the inlet of which is connected to the outlet of each precipitation reaction tank (410), and the outlet of which is connected to the inlet of the liquid storage tank (110); A second washing water pump (430), the outlet of which is connected to the inlet of the second plate and frame filter press (420); A plurality of second washing water tanks (440), each of the outlets of the second washing water tanks (440) being connected to the inlet of the second washing water pump (430), each of the inlet of the second washing water tanks (440) being connected to the outlet of the second plate and frame filter press (420), and being connected to the outlet of the clean water tank (120).

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