Fly ash washing method and fly ash washing system

Abstract

The 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 the following steps: setting target viscosity and target salinity of fly ash slurry; 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, calculating the slurrying ratio of the fly ash to the slurrying liquid to clear water; and preparing the fly ash slurry according to the slurry preparation ratio. The fly ash water washing method provided by the invention is used for solving the defect of heavy burden of fly ash water treatment in the prior art, can control the slurry ratio of the fly ash slurry raw material by taking the target salinity as a guide, and can flexibly control the water consumption of fly ash with different salinity; furthermore, the salinity of the fly ash slurry and the fly ash filtrate is not influenced by the fluctuation of fly ash components, the water consumption in the fly ash washing process is effectively reduced, and the energy consumption and the operation cost are reduced.

Description

Technical Field

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

[0002] In the process of recycling fly ash from incineration of domestic waste, problems such as equipment corrosion, system crusting and blockage, and substandard product quality are likely to occur, so water washing and desalination technology is required to efficiently wash and desalinate the fly ash. The current fly ash water washing and desalination technology generally performs fly ash slurrying according to the mass ratio of fly ash and slurrying water. The obtained fly ash slurry will undergo solid-liquid separation, and the fly ash filtrate after solid-liquid separation will be discharged after water treatment. However, the fly ash composition of different batches fluctuates greatly. When the fly ash salt content is low, the salinity of the fly ash filtrate will also be low, which will not only lead to 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 washing method to solve the defect of heavy fly ash water treatment burden in the prior art. The target salinity can be used as a guide to control the slurry ratio of fly ash slurry raw materials, and the water consumption of fly ash with different salinities can be flexibly controlled, so that the salinity of fly ash slurry and fly ash filtrate is not affected by the fluctuation of fly ash components, and the water consumption in the fly ash washing process is effectively reduced, thereby reducing energy consumption and operating costs.

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

[0005] The fly ash washing method provided by the present invention comprises: setting a target viscosity of the fly ash slurry and a target salinity of the fly ash slurry; 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; The fly ash slurry is prepared according to the slurry preparation ratio.

[0006] According to the fly ash washing method provided by the present invention, after the step of preparing the fly ash slurry, the method further comprises: 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, the clean water and the fly ash are added 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.

[0007] According to the fly ash washing method provided by the present invention, after the step of preparing the fly ash slurry, the method further comprises: The fly ash slurry is subjected to solid-liquid separation by a first plate-frame filter press to obtain a fly ash filter cake and a fly ash filtrate.

[0008] According to the fly ash washing method provided by the present invention, after the step of obtaining fly ash filter cake and fly ash filtrate, the method further comprises: 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 for re-slurrying according to the slurrying ratio.

[0009] According to the fly ash washing method provided by the present invention, after the step of obtaining the fly ash filter cake and the fly ash filtrate, the method further comprises performing in-situ multi-stage countercurrent water washing on the fly ash filter cake; Wherein, the fly ash in-situ multi-stage countercurrent water washing comprises the following steps: Based on the salinity value of the washing water in each first washing water tank, all the first washing water tanks are graded from high salinity to low salinity, so that the fly ash filter cake is washed in sequence from the first washing water tank with high salinity to the first washing water tank with low salinity.

[0010] According to the fly ash washing method provided by the present invention, the step of grading all the first washing water tanks from high salinity to low salinity based on the salinity value of the washing water in each first washing water tank, and washing the fly ash filter cake in sequence from the first washing water tank with high salinity to the first washing water tank with low salinity comprises: The washing water obtained after washing the fly ash filter cake with the washing water in the first washing water tank of the nth stage enters the first washing water tank of the n-1th stage. When the liquid level of the first washing water tank of the nth stage drops to the set target value, the in-situ washing of the nth stage is ended; Wherein, the washing water obtained after washing the fly ash filter cake with the washing water in the first washing water tank of the first stage is used to form the slurrying liquid.

[0011] According to the fly ash washing method provided by the present invention, after the wash water in the first wash water tank of the last stage washes the fly ash filter cake, the first wash water tank of the last stage is replenished with the clean water, and based on the salinity value of the wash water in each of the first wash water tanks, all the first wash water tanks are reclassified from high salinity to low salinity.

[0012] According to the fly ash washing method provided by the present invention, after the step of preparing 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, 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.

[0013] According to the fly ash washing method provided by the present invention, the precipitant includes one of sulfate, carbonate, phosphate and hydroxide.

[0014] According to the fly ash washing method provided by the present invention, 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 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.

[0015] The fly ash washing system provided by the present invention comprises a fly ash bin, a liquid storage tank, a clean water tank and a slurry preparation tank, wherein the inlet of the slurry preparation tank is connected to the fly ash bin, the liquid storage tank and the clean water tank respectively, the fly ash bin is used to provide fly ash, the liquid storage tank is used to provide slurry making liquid, the clean water tank is used to provide clean water, and the slurry preparation tank is used to prepare fly ash slurry; The slurry mixing tank is provided with a viscometer and a salinity meter, and the salinity meter and the viscometer are used to detect the actual viscosity and the actual salinity of the fly ash slurry in the slurry mixing tank.

[0016] The fly ash water washing system provided according to the present invention also includes a fly ash in-situ water washing component; The fly ash in-situ water washing component comprises: A first plate-frame filter press, the inlet of which is connected to the outlet of the slurry preparation tank, and the outlet of which is connected to the inlet of the liquid storage tank; a first washing water pump, the outlet of which is connected to the first plate-and-frame filter press; A plurality of first washing water tanks, each of the first washing water tanks having an outlet connected to the inlet of the first washing water pump, each of the first washing water tanks having an inlet connected to the outlet of the first plate and frame filter press, and connected to the outlet of the clean water tank.

[0017] The fly ash washing system provided according to the present invention also includes a fly ash filtrate processing component; The fly ash filtrate treatment component comprises: A precipitant storage tank, the outlet of which is connected to the inlet of the slurry preparation tank; A plurality of precipitation reaction tanks, wherein the inlet of each precipitation reaction tank is connected to the outlet of the precipitant storage tank and to the outlet of the first plate-frame filter press; A second plate-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; a second washing water pump, the outlet of which is connected to the inlet of the second plate and frame filter press; A plurality of second washing water tanks, each of which has an outlet connected to the inlet of the second washing water pump, each of which has an inlet connected to the outlet of the second plate and frame filter press, and connected to the outlet of the clean water tank.

[0018] In the fly ash washing method provided by the embodiment of the present invention, the salinity of the fly ash slurry can be accurately controlled by setting the target viscosity and the target salinity, and calculating the slurry ratio according to the salt content of the fly ash and the salinity of the slurry. In this way, when the fly ash slurry is squeezed and filtered, a fly ash filtrate meeting the preset salinity can be obtained; in the brine mixture, the greater the proportion of salt components, that is, the greater the salinity, in the subsequent water treatment process, the salt crystallization process will be easier. Based on this, the higher the salinity of the fly ash filtrate, the lower the difficulty of water treatment 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 difficulty of subsequent water treatment of the fly ash slurry.

[0019] Compared with the prior art, the fly ash washing method provided in the embodiment of the present invention can be guided by the target salinity. Before the fly ash slurry is produced, that is, in the raw material proportioning stage, the slurry proportion of the fly ash slurry raw materials can be controlled in advance according to preset requirements. In this way, the water consumption of fly ashes with different salinities can be flexibly controlled, so that the salinity of the fly ash slurry and the fly ash filtrate is not affected by the fluctuation of the fly ash composition. When the salt content of the fly ash is low, the proportion of slurrying water can be increased and the proportion of clean water can be reduced, so as to obtain a fly ash slurry that meets the salinity. In this way, not only can it be ensured that the salinity of the fly ash slurry meets the standard each time and the composition of the fly ash filtrate is stabilized, but it can also effectively reduce the water consumption in the fly ash slurry preparation process and reduce energy consumption and operating costs. 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.

[0020] 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 salinity at the raw material stage by accurately controlling the slurry preparation ratio of the fly ash slurry, and the water consumption in the subsequent fly ash slurry washing process can be directly determined. In this way, there is no need to feedback and adjust 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, which can solve the problem of large feedback adjustment lag, thereby effectively reducing the waste of water resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 It is a schematic diagram of the principle of the fly ash washing method provided by an embodiment of the present invention.

[0023] Figure 2 It is a system structure diagram of a fly ash washing system provided in an embodiment of the present invention.

[0024] Figure 3 It is a schematic flow chart of a fly ash washing method provided in an embodiment of the present invention.

[0025] Reference numerals: 100: fly ash bin; 110: liquid storage tank; 120: clean 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 slurry tank; 310: crusher; 320: dryer; 330: finished 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 DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to specific circumstances.

[0028] In the embodiments of the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0029] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiments of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0030] The resource utilization of fly ash from the incineration of domestic waste is an important way and development trend for the construction of a waste-free city. The current technologies for fly ash resource utilization mainly include cement kiln co-disposal, high-temperature melting and high-temperature sintering. Because fly ash contains 10-30% high-concentration soluble salts, it is easy to cause equipment corrosion, system crusting and blockage, and substandard product quality during the resource utilization process, so water washing and desalination technology is required to wash and desalinate the fly ash.

[0031] The current fly ash washing and desalination technology mainly adopts a three-stage countercurrent washing technology. Specifically, the waste incineration fly ash is first crushed and then mixed with pulping water according to the mass ratio of fly ash and pulping water to obtain fly ash slurry. The fly ash slurry is then subjected to solid-liquid separation. The solid phase after solid-liquid separation is subjected to three-stage elution with water to obtain washed fly ash and washing water. Finally, the washed fly ash is dried to obtain the finished fly ash product. The liquid phase after solid-liquid separation will be discharged after water treatment.

[0032] However, the fly ash composition of different batches fluctuates greatly. When the fly ash salinity is low, the salinity of the fly ash filtrate is also low, which not only leads to a large waste of water resources, but also imposes a huge burden on subsequent water treatment. When the fly ash salinity is high, a large amount of water needs to be added for desalination during the tertiary elution process, which also causes a huge waste of water resources.

[0033] Secondly, in the prior art, the amount of water used in washing the current batch of fly ash is feedback-regulated according to the amount of water used in the previous batch of fly ash. However, the fly ash washing time is relatively long, which will cause a huge lag in the feedback regulation. If the fly ash composition of the previous and next batches is greatly different, this will not only lead to a large waste of water resources, but also have a great impact on the washing effect of the fly ash.

[0034] Figure 1 Schematic diagram of the principle of the fly ash washing method provided by an embodiment of the present invention; Figure 2 It is a system structure diagram of a fly ash washing system provided in an embodiment of the present invention.

[0035] See also Figure 1 and Figure 2 The first aspect of the embodiment of the present invention provides a fly ash washing system, which includes a slurry preparation component, a fly ash washing component, a fly ash drying component, a fly ash filtrate treatment component, a precipitation drying 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 water washing on the fly ash slurry, and obtain fly ash filtrate and fly ash filter cake, the fly ash drying component is used to dry the fly ash filter cake, the fly ash filtrate treatment component is used to perform precipitation decalcification on the fly ash filtrate, and obtain decalcified filter cake and decalcified filtrate, the precipitation drying component is used to dry the decalcified filter cake, and the water treatment component 500 is used to perform water treatment on the decalcified filtrate.

[0036] Among them, the slurry preparation component includes a fly ash bin 100, a liquid storage tank 110, a clean water tank 120 and a slurry preparation tank 130. The fly ash bin 100 is used to store the fly ash after pre-treatment and crushing, and 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 (see below for details); the clean water tank 120 is used to provide clean water. In some optional embodiments, a running water source can also be used to replace the clean 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 refer to the adaptive design of the prior art.

[0037] The inlet of the slurry preparation tank 130 is connected to the outlets of the fly ash bin 100, the liquid storage tank 110 and the clean water tank 120 respectively, so as to obtain the raw materials for slurry preparation; a viscometer and a salinometer are arranged 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 adaptively designed according to the existing technology.

[0038] When in use, the target viscosity and target salinity of the fly ash slurry can be set 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 ratio of fly ash, slurrying liquid and clean water; finally, according to the slurry ratio, an appropriate amount of fly ash, slurrying liquid and clean water are added to the slurry mixing tank 130, and the stirring device of the slurry mixing tank 130 is started for stirring to obtain the fly ash slurry.

[0039] It should be noted that, since the salinity of the pulping liquid has a certain uncertainty, it may affect the result of the pulping ratio, so the salinity of the pulping liquid also needs to be measured in advance and added to 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 the historical data, that is, the amount of fly ash filtrate obtained after the fly ash slurry is filtered, and the difficulty of salt crystallization in the brine mixture.

[0040] It is understandable that the greater the proportion of salt in the brine mixture, that is, the greater the salinity, the easier the salt crystallization process will be in the subsequent water treatment process. In other words, the higher the salinity of the fly ash filtrate, the easier the water treatment of the fly ash filtrate will be. 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 system provided by the embodiment of the present invention, a liquid storage tank 110 and a clean water tank 120 are provided, and a viscometer and a salinometer are provided in the slurry mixing tank 130. Thus, during the mixing process of the fly ash slurry, the viscosity and salinity in the slurry mixing tank 130 can be detected in real time by the viscometer and the salinity meter. Based on this, the amounts of fly ash, slurry making liquid and clean water actually put into the slurry mixing tank 130 can be adjusted in time, thereby ensuring that the obtained fly ash slurry meets the requirements of the preset viscosity and the preset salinity. Thus, after the fly ash slurry is squeezed and filtered, a fly ash filtrate meeting the preset salinity can be obtained, thereby effectively reducing the difficulty of subsequent water treatment of the fly ash slurry.

[0041] Compared with the prior art, in the fly ash washing system provided in the embodiment of the present invention, the target salinity can be used as a guide. Before the fly ash slurry is produced, that is, in the raw material proportioning stage, the slurry proportion of the fly ash slurry raw materials can be controlled in advance according to preset requirements. In this way, the salinity of the fly ash slurry and the fly ash filtrate will not be affected by the fluctuation of the fly ash components. When the salt content of the fly ash is low, the proportion of the slurrying water can be increased and the proportion of the clean water can be reduced, so as to obtain a fly ash slurry that meets the salinity requirements. This not only ensures that the salinity of the fly ash slurry meets the standard each time, but also effectively reduces the water consumption in the fly ash slurry preparation process. 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.

[0042] 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 salinity at the raw material stage. In this way, the water consumption in the subsequent fly ash slurry washing process can be directly determined, and there is no need to feedback and adjust 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, which can solve the problem of large feedback adjustment lag, thereby effectively reducing the waste of water resources.

[0043] See also Figure 1 and Figure 2 In an optional embodiment of the present invention, the fly ash in-situ water 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. The embodiment of the present invention takes 10 first washing water tanks 220 as an example for illustration and description.

[0044] 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 connected to the liquid storage tank 110 and the fly ash filtrate tank 230 respectively. 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 water washing can be used to form a slurry, and enters the liquid storage tank 110 through the outlet of the first plate and frame filter press 200 for storage for the next batch of fly ash treatment.

[0045] The outlet of the first washing water pump 210 is connected to the inlet of the first plate-frame filter press 200, and 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-frame filter press 200, and is connected to the outlet of the clean water tank 120. For the specific washing process of the fly ash in-situ washing component, please refer to the multi-stage countercurrent washing process later. Among them, the fly ash filtrate tank 230 can send the fly ash filtrate with qualified salinity to the fly ash filtrate treatment component for treatment, and can also send the fly ash filtrate with unqualified salinity to the slurry preparation tank 130 as the raw material for the next batch of fly ash slurry preparation, thereby achieving the improvement of the salinity of the fly ash filtrate. The specific implementation method is detailed later.

[0046] See also Figure 1 and Figure 2 It can be understood that the arrangement of the first plate-frame filter press 200 and the arrangement of the plurality of first washing water tanks 220 can achieve the traditional multi-stage countercurrent washing effect with a short process and low cost. Compared with the three-stage elution method in the prior art, in the process of washing fly ash, the fly ash washing system provided by the embodiment 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 the subsequent evaporation and crystallization, thereby greatly reducing the operating energy consumption and cost; at the same time, it can also increase the salinity of the washing water, thereby increasing the salinity of the pulping liquid.

[0047] See also Figure 1 and Figure 2 In an optional embodiment of the present invention, the fly ash drying processing component includes a crusher 310, a dryer 320, a finished ash bin 330 and a filter cake slurry 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 connected to the dryer 320 and the filter cake slurry tank 300 respectively, the outlet of the dryer 320 is connected to the inlet of the finished ash bin 330, and the outlet of the filter cake slurry tank 300 is connected to the inlet of the slurry preparation tank 130.

[0048] The fly ash filter cake obtained by the first plate and frame filter press 200 enters the crusher 310 for crushing to obtain fly ash fine particles. If the fly ash filter cake is a qualified product, the fly ash fine 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. If the fly ash filter cake is an unqualified product, the fly ash fine particles enter the filter cake slurrying tank 300 for slurrying, and after slurrying, enter the slurry preparation tank 130 for slurry preparation.

[0049] It should be noted that the cleanliness of the fly ash filter cake can be judged by testing the salinity of the filtrate after the last water washing of the fly ash filter cake. When the salinity of the filtrate after the last water washing of the fly ash filter cake is qualified, it means that the fly ash filter cake is a qualified product. When the salinity of the filtrate after the last water washing of the fly ash filter cake is unqualified, it means that the fly ash filter cake is an unqualified product.

[0050] It can be understood that by setting up a fly ash drying treatment component, 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 treatment component can also well control the qualification of the fly ash filter cake, and can promptly 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.

[0051] See also Figure 1 and Figure 2 In an optional embodiment of the present invention, the fly ash filtrate treatment assembly includes a precipitant storage tank 400, a second plate-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 connected to the inlet of the slurry preparation tank 130 and the inlet of each precipitation reaction tank 410, respectively, and the precipitant storage tank 400 is used to provide a precipitant, and the precipitant includes one of sulfate, carbonate, phosphate and hydroxide. This article takes the sodium sulfate solution in the sulfate as an example. The calcium ion content in the fly ash slurry is relatively high. During the preparation of the fly ash slurry, sodium sulfate solution can be added to the slurry preparation tank 130 according to the preset target. The sodium sulfate solution will react with the calcium ions in the fly ash slurry to generate calcium sulfate precipitate.

[0052] However, since calcium sulfate is slightly soluble and the accuracy of single decalcification is low and difficult to control, the fly ash filtrate after filtering the fly ash slurry can be subjected to secondary fine decalcification through multiple precipitation reaction tanks 410. Specifically, after the fly ash filtrate enters the multiple precipitation reaction tanks 410 through the fly ash filtrate tank 230, sodium sulfate solution can be added to the multiple precipitation reaction tanks 410 for precipitation reaction. Each precipitation reaction tank 410 includes a calcium ion concentration monitor, an agitator and a liquid level meter. In order to ensure the stability of the gypsum reaction and the volume of the gypsum agglomerates, the multiple precipitation reaction tanks 410 can be controlled by intermittent operation. Specifically, after the fly ash filtrate and sodium sulfate are metered into the stirring process, when the calcium ion concentration is within the set range, the stirring can be stopped to age the gypsum to increase the particle size.

[0053] When the gypsum reaction is completed, decalcified slurry, that is, gypsum slurry, can be obtained. After the decalcified slurry enters the second plate and frame filter press 420, it will be separated into decalcified filter cake (gypsum filter cake) and decalcified filtrate (gypsum filtrate). Multiple second washing water tanks 440, second plate and frame filter presses 420 and second washing water pumps 430 can perform in-situ multi-stage countercurrent water washing on the decalcified filter cake. The specific in-situ multi-stage countercurrent water washing process of decalcification is shown below.

[0054] The sedimentation and drying treatment component can dry and crush the decalcified filter cake after washing, and then the decalcified filter cake can be stored and treated in the storage bin 450. For details, please refer to the fly ash drying treatment component mentioned above, which will not be repeated here in this article; the water treatment component 500 can perform water treatment on the decalcified filtrate (gypsum filtrate). The specific structure and method of water treatment can refer to the existing technology, which will not be repeated here in this article.

[0055] Among them, the washing water obtained after washing the decalcified filter cake with the washing water in the first-stage first washing water tank 220 in the decalcification in-situ multi-stage countercurrent washing can be used to form the pulping liquid. Specifically, it can be adaptively set according to actual conditions.

[0056] See also 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 decalcification treatments on the fly ash, namely, coarse decalcification and fine decalcification. The decalcification treatment is divided into two times, which can effectively improve the fault tolerance of the decalcification treatment, avoid precipitant contamination and waste of precipitant due to excessive addition of precipitant, and avoid the problem of insufficient precipitation or incomplete decalcification due to insufficient addition of precipitant.

[0057] In addition, the precipitation reaction tank 410 can realize the precise control of the calcium ion concentration in the gypsum slurry through multiple joint use, which can save the amount of reagents used and stabilize the composition of the gypsum filtrate to the greatest extent. 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 decalcification in-situ multi-stage countercurrent washing adopts a single plate frame machine combined with a multi-stage simple washing device, which can achieve the traditional multi-stage countercurrent washing effect in a short process and at a low cost, and can greatly reduce the water consumption of decalcification washing.

[0058] Figure 3 It is a schematic flow chart of a fly ash washing method provided in an embodiment of the present invention.

[0059] See also Figures 1 to 3 A second aspect of an embodiment of the present invention provides a fly ash washing method, which specifically includes the following steps.

[0060] S100: setting a target viscosity of the fly ash slurry and a target salinity of the fly ash slurry.

[0061] Specifically, the setting of the target viscosity needs to take into account 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 water consumption, and specific reference may be made to the adaptability setting of the prior art; the target salinity can be adaptively set based on the water output of the fly ash slurry in historical data, that is, the amount of fly ash filtrate obtained after filtration of the fly ash slurry, and the difficulty of salt crystallization in the brine mixture.

[0062] S200: Calculate the slurry ratio of fly ash, slurry 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 slurry.

[0063] Specifically, the actual viscosity and actual salinity of the fly ash slurry can be detected by the viscometer and salinity meter installed in the slurry mixing tank 130, and 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 ratio of fly ash, slurrying liquid and clean water.

[0064] S300: Obtain the fly ash slurry according to the slurry preparation ratio.

[0065] Specifically, according to the slurry ratio, appropriate amounts of fly ash, slurry and clean water are added to the slurry preparation tank 130, and the stirring device of the slurry preparation tank 130 is started to stir, so as to obtain fly ash slurry.

[0066] See also Figures 1 to 3 It can be understood that the greater the proportion of salt in the brine mixture, 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 difficulty of water treatment 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 water washing method provided by the embodiment of the present invention, by setting the target viscosity and the target salinity, and calculating the pulping ratio according to the salt content of the fly ash and the salinity of the slurry (formed by the subsequent washing water, which can be replaced by clean water when the first batch of fly ash washing is carried out), the salinity of the fly ash slurry can be accurately controlled. In this way, after the fly ash slurry is squeezed and filtered, a fly ash filtrate that meets the preset salinity can be obtained, which can effectively reduce the difficulty of subsequent water treatment of the fly ash slurry.

[0067] Compared with the prior art, the fly ash washing method provided in the embodiment of the present invention can be guided by the target salinity. Before the fly ash slurry is produced, that is, in the raw material proportioning stage, the slurry proportion of the fly ash slurry raw materials can be controlled in advance according to preset requirements. In this way, the water consumption of fly ashes with different salinities can be flexibly controlled, so that the salinity of the fly ash slurry and the fly ash filtrate is not affected by the fluctuation of the fly ash composition. When the salt content of the fly ash is low, the proportion of slurrying water can be increased and the proportion of clean water can be reduced, so as to obtain a fly ash slurry that meets the salinity. In this way, not only can it be ensured that the salinity of the fly ash slurry meets the standard each time and the composition of the fly ash filtrate is stabilized, but it can also effectively reduce the water consumption in the fly ash slurry preparation process and reduce energy consumption and operating costs. 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.

[0068] 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 salinity at the raw material stage by accurately controlling the slurry preparation ratio of the fly ash slurry. The water consumption in the subsequent fly ash slurry washing process can be directly determined. In this way, there is no need to feedback and adjust 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, which can solve the problem of large feedback adjustment lag, thereby effectively reducing the waste of water resources.

[0069] See also Figures 1 to 3 In an optional embodiment of the present invention, after step S300, it is further included 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 clean water and fly ash are added to the fly ash slurry. It is understandable that when there is a gap 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 prepared, thereby ensuring the salinity of the fly ash slurry.

[0070] See also Figures 1 to 3 In an optional embodiment of the present invention, after step S300, the step further includes performing solid-liquid separation on the fly ash slurry through the first plate-frame filter press 200 to obtain a fly ash filter cake and a fly ash filtrate. Specifically, the inlet of the first plate-frame filter press 200 is connected to the outlet of the slurry preparation tank 130, and the first plate-frame filter press 200 can squeeze and filter the fly ash slurry to achieve solid-liquid separation. The solid phase is retained by the filter cloth in the first plate-frame filter press 200 to form a fly ash filter cake, and the liquid phase forms a fly ash filtrate. The fly ash filtrate enters the fly ash filtrate treatment component for treatment.

[0071] See also Figures 1 to 3In an optional embodiment of the present invention, after the step of obtaining fly ash filter cake and fly ash filtrate, it also 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 slurrying liquid, the slurrying ratio of the fly ash filtrate, fly ash, slurrying liquid and clean water is calculated, and the fly ash filtrate obtained in the previous step is put into the slurry preparation tank 130 for re-slurrying according to the slurrying ratio.

[0072] It can be understood that this step is mainly for the first batch of fly ash. When the salinity of the first batch of fly ash itself is low, the salinity of the fly ash filtrate will not meet the standard. In this case, if the fly ash filtrate is directly put into the subsequent treatment process, it will create 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 slurrying liquid to supplement the salinity of the fly ash slurry. If fly ash is continued to be added, although the salinity in the fly ash slurry will increase, the viscosity of the fly ash slurry will be further away from the target viscosity. In this embodiment, the fly ash filtrate is used as the slurry raw material for the next batch of fly ash. Since the fly ash filtrate has been washed, its salinity is higher. In this way, the salinity of the fly ash slurry can be increased while ensuring the viscosity of the fly ash slurry, thereby ensuring the salinity of the fly ash filtrate and reducing the difficulty of preparing the fly ash slurry.

[0073] In a specific embodiment, when the original salinity of the fly ash is extremely low, it is impossible to obtain a fly ash slurry with qualified salinity simply by adding fly ash; in other possible embodiments, the salinity of the slurry obtained by the subsequent primary washing water may also be relatively low. In this case, it may be impossible to obtain a fly ash slurry that meets the salinity and viscosity requirements simply by relying on the salinity of the slurry and fly ash; in this embodiment, the fly ash slurry with qualified viscosity but unqualified salinity is first separated into solid and liquid, and the fly ash filtrate obtained from the liquid phase is then put into the next batch of fly ash slurry. In this way, even in such an 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 water washing method.

[0074] See also Figures 1 to 3 In an optional embodiment of the present invention, after the step of obtaining the fly ash filter cake and the fly ash filtrate, the step also includes performing in-situ multi-stage countercurrent water washing on the fly ash filter cake; wherein 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 to low, and the first washing water tanks 220 at each level wash the fly ash filter cake in turn.

[0075] Specifically, n-stage water washing devices are set, such as 10 stages, wherein each stage of the water washing device includes a first washing water tank 220, a liquid level meter, a salinity meter, an inlet pipe and a valve, and an outlet pipe and a valve. The outlet pipes of each first washing water tank 220 converge into an outlet pipe, and the outlet pipe is connected to the water 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 via a pipe. A salinity meter is provided at the filter cake washing outlet pipe of the first plate and frame filter press 200, and is connected to the water inlet pipe valve of each first washing water tank 220.

[0076] The basic process of in-situ multi-stage countercurrent washing of fly ash is as follows: first, each first washing water tank 220 is sorted in order according to the salinity data measured by the salinity meter in the tank, and the first washing water tank 220 with the highest salinity is the first-stage first washing water tank 220. The washing water in the first-stage first washing water tank 220 is pumped into the first plate and frame filter press 200 by the first washing water pump 210 to wash the fly ash filter cake in situ, and the washing water with higher salinity obtained after washing the fly ash filter cake is used for slurry preparation, that is, to form the aforementioned slurry making liquid. When the liquid level of the first-stage first washing water tank 220 drops to the set target value, the first-stage in-situ washing is terminated, wherein 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.

[0077] Then the washing water in the second-stage first washing water tank 220 is pumped into the first plate and frame filter press 200 through the first washing water pump 210 to wash the fly ash filter cake in situ, and the washing water with higher salinity obtained after washing the fly ash filter cake enters the first-stage first washing water tank 220. When the liquid level in the second-stage first washing water tank 220 drops to the set target value, the second-stage in-situ washing is ended.

[0078] Then the washing water in the third-stage first washing water tank 220 is pumped into the first plate and frame filter press 200 through the first washing water pump 210 to wash the fly ash filter cake in situ, and the washing water with higher salinity obtained after washing the fly ash filter cake enters the second-stage first washing water tank 220. When the liquid level in the third-stage first washing water tank 220 drops to the set target value, the third-stage in-situ washing is ended.

[0079] Similarly, the washing water in the nth-stage first washing water tank 220 is pumped into the first plate and frame filter press 200 through the first washing water pump 210 to wash the fly ash filter cake in situ, and the washing water with higher salinity obtained after washing the fly ash filter cake enters the n-1th-stage first washing water tank 220. When the liquid level in the nth-stage first washing water tank 220 drops to the set target value, the nth-stage in-situ washing is terminated.

[0080] Finally, clean water is added to the last first washing water tank 220 to the set liquid level, and the process of the fly ash in-situ multi-stage countercurrent washing is ended. It should be noted that when the fly ash in the fly ash in-situ multi-stage countercurrent washing is the first batch, if there is no washing water from the previous batch to serve as the pulping liquid, clean water can be used instead, and the fly ash slurry with qualified viscosity but unqualified salinity is first separated into solid and liquid, and then the separated fly ash filtrate is used as the next batch of pulping raw materials for "salting". 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 a concentration suitable for crystallization), the fly ash filtrate can be re-washed to increase the salinity of the fly ash filtrate. For the first batch of fly ash washing, all the first washing water tanks 220 can be filled with clean water. After multiple fly ash in-situ multi-stage countercurrent washings, the clean water can form washing water with the target salinity, which is then used to form pulping liquid.

[0081] It should also be noted that when the salinity of the washing water displayed by the salinity meter set at the filter cake washing outlet of a first plate-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.

[0082] After the fly ash is washed with multi-stage countercurrent water in situ, the first plate and frame filter press 200 needs to perform the pressing operation again to apply pressure to both sides of the fly ash filter cake in the first plate and frame filter press 200 to further discharge the residual moisture in the fly ash filter cake to reduce the moisture content of the fly ash filter cake. The discharged moisture forms the squeezed filtrate, which is tested for salinity by a salinity meter. The squeezed filtrate is added to the corresponding first washing water tank 220 according to the salinity value.

[0083] Then, after the fly ash filter cake is discharged, it is crushed by a 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 a dryer 320, and the finished fly ash is obtained after drying for the production of building materials such as cement.

[0084] When the salinity of the squeezed 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 squeezed 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 that the washing effect of the fly ash can be fully guaranteed.

[0085] It can be understood that in the fly ash washing method provided by the embodiment of the present invention, the water consumption in the fly ash washing process can be effectively reduced by the in-situ multi-stage countercurrent washing of the fly ash, wherein the washing water with higher salinity obtained after washing the first-stage fly ash filter cake can form the aforementioned slurry liquid 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 the fly ash filtrate. In addition, the in-situ multi-stage countercurrent washing of the fly ash can achieve the traditional multi-stage countercurrent washing effect in a short process and at a low cost by using a single plate frame machine combined with a multi-stage simple washing device, and at the same time can also greatly reduce the total amount of wastewater, thereby greatly reducing the water treatment load and the amount of wastewater evaporation of subsequent evaporation and crystallization, and greatly reducing the operating energy consumption and cost.

[0086] In an optional embodiment of the present invention, after the step of obtaining the fly ash slurry, before the step of solid-liquid separation of the fly ash slurry by the first plate and frame filter press 200, it also includes: adding a precipitant to the fly ash slurry according to a preset target to roughly decalcify the fly ash slurry. The specific process of rough decalcification can be referred to the above description, and will not be repeated here. It can be understood that in an optional embodiment of the present invention, adding a precipitant to roughly decalcify the fly ash slurry in the slurry preparation link can effectively reduce the control difficulty of subsequent decalcification, thereby achieving the purpose of reducing the amount of reagents, stabilizing the decalcification effect, and stabilizing the decalcification filtrate composition, creating control conditions for subsequent water treatment and evaporation crystallization, and reducing operating costs.

[0087] In an optional embodiment of the present invention, when the precipitant is one of sulfate and hydroxide, since the precipitates formed by sulfate and hydroxide are both slightly soluble, further fine decalcification is required. The precipitant can be added to the fly ash filtrate again according to the 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 and frame filter press 420 to obtain a decalcified filter cake and a decalcified filtrate, and the decalcified filter cake is decalcified by in-situ multi-stage countercurrent water washing.

[0088] The present invention uses sodium sulfate solution as a precipitant for example and description, and the following is a specific process of fly ash filtrate treatment.

[0089] The fly ash filtrate from the first plate and frame filter press 200 is high-salt wastewater. At the same time, the calcium ion concentration is still relatively high after the slurry is prepared for coarse decalcification, so it is necessary to continue to add sodium sulfate solution and calcium ions to generate calcium sulfate precipitation and obtain gypsum products.

[0090] The aged gypsum slurry is stirred again to obtain decalcified slurry, which 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, i.e., decalcified filtrate. The decalcified filtrate will enter the subsequent water treatment and evaporation crystallization process to achieve wastewater treatment.

[0091] The solid phase in the decalcified slurry is retained by the filter cloth inside the second plate and frame filter press 420 to form a gypsum filter cake, i.e., a decalcified filter cake. Since the decalcified filter cake contains highly concentrated brine, it needs to be further decalcified by in-situ multi-stage countercurrent water washing. This process is basically the same as the aforementioned in-situ multi-stage countercurrent water washing process for fly ash.

[0092] The specific process is: n-level water washing devices are set, such as 10 levels, wherein each level of the water washing device includes a second washing water tank 440, a liquid level meter, a salinity meter, an inlet pipe and a valve, an outlet pipe and a valve, the outlet pipes of each second washing water tank 440 converge into an outlet pipe, the outlet pipe is connected to the water 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 via a pipe, the filter cake washing outlet pipe of the second plate and frame filter press 420 is provided with a salinity meter, and is connected to the inlet pipe valve of each second washing water tank 440.

[0093] The basic process of decalcification in-situ multi-stage countercurrent washing is as follows: first, the salinity data measured by the salinity meter in each second washing water tank 440 are sorted in order, and the second washing water tank 440 with the highest salinity is the first-stage second washing water tank 440. The washing water of 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 wash the decalcified filter cake in-situ. The washing water with higher salinity obtained after washing the decalcified filter cake is used for slurry preparation, that is, to form the aforementioned slurry making liquid. When the liquid level of the first-stage second washing water tank 440 drops to the set target value, the first-stage in-situ washing is terminated, wherein 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.

[0094] Then the washing water in the second-stage second washing water tank 440 enters the second plate and frame filter press 420 through the second washing water pump 430 to wash the decalcified filter cake in situ. The washing water with 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 is ended.

[0095] Then the washing water in the third-stage second washing water tank 440 is pumped into the second plate and frame filter press 420 through the second washing water pump 430 to wash the decalcified filter cake in situ. The washing water with 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 is ended.

[0096] Similarly, the washing water in the nth-stage second washing water tank 440 is pumped into the second frame filter press by the second washing water pump 430 to wash the decalcified filter cake in situ, and the washing water with higher salinity obtained after washing the decalcified filter cake enters the n-1th-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 nth-stage in-situ washing is terminated.

[0097] Finally, clean water is added to the second washing water tank 440 of the last stage to reach the set liquid level, thus completing the decalcification in-situ multi-stage countercurrent washing process.

[0098] It should be noted that when the salinity of the washing water displayed by the salinity meter installed at the filter cake washing outlet of a certain stage of the second plate-frame filter press 420 is stably lower than a certain set value, it means that the filter cake in-situ washing is terminated ahead of schedule. At this time, clean water should be added to the second washing water tank 440 of this stage of washing. This set value can be adaptively set according to actual conditions. When the salinity of the washing water in each second washing water tank 440 is stable, it is necessary to sort the washing water by salinity again to prepare for the next washing.

[0099] After the decalcification in-situ multi-stage countercurrent washing, the second plate-frame filter press 420 performs a squeezing operation, and by applying pressure to both sides of the decalcified filter cake in the second plate-frame filter press 420, the residual water in the decalcified filter cake is further discharged to reduce the moisture content of the decalcified filter cake. The discharged water forms a squeezed filtrate, which is tested for salinity by a salinometer, and the squeezed filtrate is added to the corresponding first washing water tank 220 according to the salinity value. The decalcified filter cake is then dried and crushed, or directly discharged for the production of building materials such as cement.

[0100] It should be noted that the technical solutions in various embodiments of the present invention can be combined with each other, but the basis for the mutual combination is that it can be implemented by ordinary technicians in the field; when the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist, that is, it does not belong to the protection scope of the present invention.

[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A fly ash washing method, characterized in that: include: setting a target viscosity of the fly ash slurry and a target salinity of the fly ash slurry; 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; The fly ash slurry is prepared according to the slurry preparation ratio.

2. The fly ash washing method according to claim 1, characterized in that: The step of preparing the fly ash slurry further comprises: 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, the clean water and the fly ash are added 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.

3. The fly ash washing method according to claim 1, characterized in that: The step of preparing the fly ash slurry further comprises: The fly ash slurry is subjected to solid-liquid separation by a first plate-frame filter press (200) to obtain a fly ash filter cake and a fly ash filtrate.

4. The fly ash washing method according to claim 3, characterized in that: The step of obtaining fly ash filter cake and fly ash filtrate 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, 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.

5. The fly ash washing method according to claim 3, characterized in that: 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; Wherein, the fly ash in-situ multi-stage countercurrent water washing comprises 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 fly ash filter cake is washed in sequence from the first washing water tank (220) with high salinity to the first washing water tank (220) with low salinity.

6. The fly ash washing method according to claim 5, characterized in that: 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.

7. The fly ash washing method according to claim 6, 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.

8. The fly ash washing method according to claim 3, 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.

9. The fly ash washing method according to claim 8, characterized in that: The precipitating agent includes one of sulfate, carbonate, phosphate and hydroxide.

10. The fly ash washing method according to claim 9, 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.

11. A fly ash washing system, characterized in that: The invention comprises a fly ash bin (100), a liquid storage tank (110), a clean water tank (120) and a slurry preparation tank (130), wherein an 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; A viscometer and a salinity meter are provided in the slurry mixing tank (130), and the salinity meter and the viscometer are used to detect the actual viscosity and the actual salinity of the fly ash slurry in the slurry mixing tank (130).

12. The fly ash washing system according to claim 11, characterized in that: Also included are fly ash in-situ water washing components; 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).

13. The fly ash washing system according to claim 12, 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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