Countercurrent elutriation method and countercurrent elutriation device based on accurate control of nitrate content in nitrate co-production
By using countercurrent washing methods and devices in cogeneration of nitr salt, the upward impact force of washing brine is used to wash salt particles, and the problem of blockage of salt discharge ports in cogeneration of nitr salt is solved, and the precise control and reduction of nitr content is achieved, and product quality and production efficiency are improved.
Patent Information
- Application Number
- CN202510158215.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-13
- Publication Date
- 2025-05-23
AI Technical Summary
In co-production of nitr salt, large pieces of salt in the evaporation tank cause blockage of the salt discharge port, affecting the quality and production efficiency of the salt. The existing technology cannot accurately control the nitr content and reduce the nitr content.
Using a method and device based on countercurrent washing, the salt content is accurately controlled and reduced by injecting salt mother liquor and washing brine into the evaporation chamber, and the upward impact force of the washing brine is used to wash salt particles, and the process of two washing and circulating heating and evaporation is achieved.
The control accuracy of sodium sulfate content in salt products in co-production of nitr salt is improved, the nitr content in salt products is reduced, the product quality is ensured, and the heat transfer efficiency is improved, and the production cost is reduced.
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Figure CN120024913A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of salt processing, and specifically relates to a countercurrent elutriation method and a countercurrent elutriation device based on precise control of nitrate content in nitrate-salt co-production. Background Art
[0002] The salt-salt co-production process is based on the solution characteristics of sodium chloride and sodium sulfate for evaporation and separation. 2 SO 4 -H 2 In the O system, the solubility of NaCl increases with the increase of temperature, and the solubility of Na 2 SO 4 On the contrary, its solubility decreases with increasing temperature. According to this rule, the raw brine can be evaporated at a lower temperature first, and while a large amount of NaCl is precipitated, Na 2 SO 4 Concentrate. 2 SO 4 When the concentration reaches or approaches saturation, the temperature of the salt precipitation mother liquor is raised, and Na 2 SO 4 The solubility of NaCl decreases and precipitates, while the solubility of NaCl increases with the increase of temperature and becomes an unsaturated component. 2 SO 4 The precipitation continues, and the NaCl concentration increases. When the NaCl concentration reaches or approaches saturation, the mother liquor of nitrate precipitation is cooled and evaporated, which can make NaCl supersaturated and precipitate. 2 SO 4 The mother liquor is then returned to the temperature and recycled, and NaCl and Na 2 SO 4 Hence the separation.
[0003] Production practice has proved that sodium chloride and sodium sulfate can be completely separated, but the two sodium components between regions must be controlled stably. As the temperature of each evaporation group tank changes, the two sodium main components in the group tank must be controlled within this temperature range. If the two sodium components exceed the regional control point, sodium sulfate and sodium chloride will be at the co-saturation point, forming a eutectic, which will lead to the instability of the quality of the sodium chloride product and affect the purity of the sodium chloride. The main impurity of mirabilite-type brine salt is sodium sulfate, and other impurities such as calcium sulfate and magnesium sulfate can be removed during the two-alkali treatment process. In view of the presence of sodium sulfate impurities, salt washing is essential as the only means to improve the quality of raw salt.
[0004] In the nitrate and salt co-production, salt legs are usually provided at the bottom of the evaporation chamber. The salt legs can collect salt, grade, wash, dissolve soluble impurities, and cool. They are one of the key components for improving the quality of salt and reducing the energy consumption of the salt-making system. The washing brine is mainly a mixture of the clear liquid of nitrate and salt making and the purified refined brine, which is close to or reaches saturation. In the nitrate and salt co-production, the washing brine is pumped to each effect crystal collector to cool the salt slurry and nitrate slurry, wash the impurities of the product crystals, and return the fine crystals to the evaporation chamber, thereby achieving the purpose of improving the purity of nitrate and salt products and reducing the concentration of soluble impurities such as sulfates and carbonates in nitrate and salt products. However, in the actual joint production of nitrate and salt, large pieces of salt will be produced in the evaporator. When discharging salt, a certain amount of large salt pieces will gather at the salt leg discharge port, causing blockage of the salt discharge port and making salt discharge poor. At present, China generally adopts the method of refined brine washing to impulsively remove large pieces of salt and discharge a large amount of mother liquor to ensure the quality of salt. However, the unquantified and unfounded refined brine washing will cause a large amount of refined brine to enter the evaporation system and destroy the balance of the evaporation system. At the same time, a large amount of mother liquor will also cause heat energy loss in the salt discharge production device. Summary of the invention
[0005] In view of the above problems, the present invention provides a countercurrent elutriation method and a countercurrent elutriation device based on precise control of nitrate content in nitrate-salt co-production.
[0006] The present invention is achieved through the following technical solutions.
[0007] In a first aspect, the present invention provides a countercurrent elutriation method based on precise control of nitrate content in nitrate-salt co-production, characterized in that it comprises the following steps: S1, mother liquor feeding: inject a proper amount of salt-making mother liquor into the current effect evaporation chamber, and fill the salt slurry washing chamber with washing brine through the refined brine feeding pipe; S2, circulating heating evaporation: Turn on the centrifugal pump to send the salt-making mother liquor in the evaporation chamber to the upper circulation pipe through the lower circulation pipe, and then heat it through the heating jacket and return it to the evaporation chamber, so that the salt-making mother liquor in the evaporation chamber maintains the temperature and continues to evaporate to precipitate salt particles; S3, the first washing: after a large number of salt particles are precipitated in the evaporation chamber, the salt valve on the salt pipe is opened, and the refined brine feed pump is turned on to continuously inject washing brine into the salt slurry washing chamber. At this time, the salt particles fall into the salt slurry washing chamber through the salt pipe, and the washing brine is sent upward into the evaporation chamber through the salt pipe. The salt particles are washed by the washing brine in the salt pipe to achieve the first washing. The salt-making mother liquor stays in the evaporation chamber due to the upward impact force of the washing brine, and the salt-making mother liquor-salt particles-washing brine are in a dynamic equilibrium state; S4, second washing: salt particles enter the salt slurry washing chamber through the salt drop pipe and continue to settle and contact with the washing brine to achieve the second washing; during this period, the salt discharge foot is opened at regular intervals to discharge the salt particles at the bottom of the salt slurry washing chamber; S5. Mother liquor replenishment: When there is no large amount of salt particles precipitated in the evaporation chamber, a part of the salt-making mother liquor in the evaporation chamber is discharged to the next-effect evaporation chamber through the material transfer jacket, and new salt-making mother liquor is added to the current-effect evaporation chamber at the same time.
[0008] Preferably, in step S3, when the refined brine feed pump is turned on to continuously inject washing brine into the salt slurry washing chamber, the injection amount of the washing brine is controlled to be 0.8-1.2 times the evaporation amount of the salt making mother liquor in the evaporation chamber.
[0009] Preferably, in step S3, when the refined brine feed pump is turned on to continuously inject washing brine into the salt slurry washing chamber, the rotation speed of the refined brine feed pump is controlled to be 25-40 rpm.
[0010] Preferably, the washing brine is refined brine.
[0011] In the second aspect, the present invention provides a countercurrent washing device for the co-production of nitrate and salt, comprising an evaporation chamber, characterized in that it also includes a salt slurry washing chamber arranged directly below the evaporation chamber, a salt drop pipe connected at the upper end to the bottom of the evaporation chamber and sealed at the lower end to penetrate into the washing chamber, a salt discharge foot connected to the bottom of the salt slurry washing chamber, a refined brine feeding pipe connected to one side of the washing chamber, a refined brine feed pump arranged on the refined brine feeding pipe, a centrifugal pump, a lower circulation pipe connected at one end to one side of the evaporation chamber and at the other end to a feed port of the centrifugal pump, an upper circulation pipe connected at one end to the other side of the evaporation chamber and at the other end to a discharge port of the centrifugal pump, and a heating jacket arranged on the upper circulation pipe for heating the material transported in the upper circulation pipe.
[0012] Preferably, a salt block crushing cone is provided at the bottom of the evaporation chamber, and the salt block crushing cone includes a hydraulic cylinder fixedly arranged at the bottom of the evaporation chamber and a crushing cone; the crushing cone is arranged at the telescopic end of the hydraulic cylinder and the end head has a sharp portion, and the hydraulic cylinder drives the crushing cone to move toward the top pipe opening of the salt falling pipe to impact the salt particles that have formed large lumps and blocked the pipe opening of the salt falling pipe.
[0013] Preferably, a manhole is provided on the top of the salt slurry washing chamber.
[0014] Preferably, salt slurry viewing mirrors are provided on the bottom and side walls of the middle portion of the salt slurry washing chamber.
[0015] Preferably, the lower circulation pipe is provided with a material transfer jacket for discharging a portion of the salt-making mother liquor in the evaporation chamber to the next-effect evaporation chamber.
[0016] Preferably, a salt dropping valve is provided on the salt dropping pipe.
[0017] Preferably, a temperature probe is provided at the bottom of the evaporation chamber near the opening of the salt pipe.
[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The present invention can improve the control accuracy of the sodium sulfate content in the salt product during the co-production of nitrate and salt and reduce the nitrate content in the salt product to ensure product quality.
[0019] (2) In the present invention, the washing brine is sent into the evaporation chamber through the salt drop pipe, and the continuous upward impact of the washing brine can be used to solve the problem of large pieces of salt blocking the pipe when the salt drop pipe is discharged.
[0020] (3) The present invention pumps washing brine into the salt slurry washing chamber. At this time, salt particles fall into the salt slurry washing chamber through the salt drop pipe, and the washing brine is sent upward into the evaporation chamber through the salt drop pipe. The salt-making mother liquor stays in the evaporation chamber due to the upward impact force of the washing brine. The salt-making mother liquor-salt particles-washing brine are in a dynamic equilibrium state. In this way, the salt-making mother liquor will not flow into the salt slurry washing chamber or be discharged with the salt particles through the salt discharge foot to cause heat loss. At the same time, with the continuous impact of the washing brine, the bed temperature in the evaporation chamber can be made more uniform, thereby improving the heat and mass transfer efficiency of the nitrate-salt co-production and reducing the production cost. In addition, the salt particles within a certain particle size range precipitated in the evaporation chamber are continuously settled and washed by the washing brine transported downward through the salt drop pipe for the first washing, and then automatically fall into the salt slurry washing chamber for the second washing, and finally sent to the centrifuge through the salt discharge foot. The salt particles can be discharged without the help of additional operations during the whole process, so the production efficiency is higher, and after two washings, the quality of the salt product is better. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 The present invention is a process flow chart of a countercurrent washing method for accurately controlling the nitrate content in the nitrate-salt co-production.
[0022] Figure 2 It is a schematic diagram of the structure of the countercurrent elutriation device of the present invention.
[0023] Figure 3 This is a schematic diagram of the countercurrent elutriation device of the present invention being used in series in the II effect, III effect and IV effect evaporation of the salt production mother liquor.
[0024] The meanings of the symbols in the above figure are: evaporation chamber 1, salt slurry washing chamber 2, salt drop pipe 3, salt drop valve 301, refined brine feeding pipe 4, refined brine feed pump 5, centrifugal pump 6, upper circulation pipe 7, salt discharge foot 8, heating jacket 9, manhole 10, salt slurry sight glass 11, material transfer jacket 12, temperature probe 13, upper circulation pipe 13, salt block crushing cone 14. DETAILED DESCRIPTION
[0025] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention. Example 1
[0026] This embodiment provides a countercurrent washing device for the co-production of nitrate and salt, see Figure 2 , including an evaporation chamber 1, a salt slurry washing chamber 2 arranged just below the evaporation chamber 1, a salt drop pipe 3 whose upper end is connected to the bottom of the evaporation chamber 1 and whose lower end is sealed and passes through the inside of the washing chamber 2, a salt discharge foot 8 connected to the bottom of the salt slurry washing chamber 2, a refined brine feeding pipe 4 connected to one side of the washing chamber 2, a refined brine feed pump 5 arranged on the refined brine feeding pipe 4, a centrifugal pump 6, a lower circulation pipe 7 whose one end is connected to one side of the evaporation chamber 1 and the other end is connected to the feed port of the centrifugal pump 6, an upper circulation pipe 7 whose one end is connected to the other side of the evaporation chamber 1 and the other end is connected to the discharge port of the centrifugal pump 6, and a heating jacket 9 arranged on the upper circulation pipe 7 for heating the material transported in the upper circulation pipe 7; wherein the evaporation chamber 1 is a container for evaporating the salt-making mother liquor, and a feeding pipe and an exhaust port are arranged on the top of the evaporation chamber 1; the salt drop pipe 3 is where the salt-making mother liquor is discharged after evaporation in the evaporation chamber 1 The salt particles enter the channel of the salt slurry washing chamber 2; the salt slurry washing chamber 2 is used to receive and wash the salt particles precipitated from the salt mother liquor after evaporation in the evaporation chamber 1; the refined brine feeding pipe 4 is used to supplement the salt slurry washing chamber 2 or the entire system with washing brine; the heating jacket 9 uses high-temperature steam at different pressures as the heating medium to heat the material transported in the upper circulation pipe 7; the upper circulation pipe 13, the lower circulation pipe 7 and the centrifugal pump 6 cooperate with each other to circulate the salt mother liquor in the evaporation chamber 1, and heat the salt mother liquor through the heating jacket 9; the salt discharge foot 8 is used to discharge the salt particles in the salt slurry washing chamber 2 to the centrifuge, and the salt discharge foot 8 is provided with a salt discharge valve 801; in the joint production of nitrate and salt, since the I-effect evaporation of the salt mother liquor will not precipitate salt particles, the device of the present invention is usually used for the II-effect, III-effect and IV-effect evaporation of the salt mother liquor, such as Figure 3 As shown, three sets of the devices of the present invention can be connected in series and respectively applied to the II effect, III effect and IV effect evaporation of the salt production mother liquor.
[0027] Furthermore, in a preferred embodiment, a salt block crushing cone 14 is provided at the bottom of the evaporation chamber 1, and the salt block crushing cone 14 includes a hydraulic cylinder fixedly arranged at the bottom of the evaporation chamber 1, and a crushing cone 1401; wherein the hydraulic cylinder is a conventional hydraulic actuator that converts hydraulic energy into mechanical energy to perform linear reciprocating motion, and the crushing cone is arranged at the telescopic end of the hydraulic cylinder and the end has a sharp portion, and the hydraulic cylinder drives the crushing cone 1401 to move toward the top nozzle of the salt drop pipe 3 to impact and block the salt particles that have formed large lumps at the nozzle of the salt drop pipe 3, thereby preventing the salt particles from precipitating and forming large lumps to block the nozzle of the salt drop pipe 3; in order to reduce the influence of the salt block crushing cone 14 on the sedimentation of salt particles or the rise of brine, the salt block crushing cone 14 adopts an intermittent working mode.
[0028] In order to facilitate the maintenance and cleaning of the salt slurry washing chamber 2 , further, in a preferred embodiment, a manhole 10 is provided on the top of the salt slurry washing chamber 2 .
[0029] Furthermore, in a preferred embodiment, salt slurry sight glasses 11 are provided on the side walls at the bottom and the middle of the salt slurry washing chamber 2, and the amount of salt in the washing chamber can be conveniently observed through the salt slurry sight glasses 11, so as to control the salt discharge foot 8 to discharge salt at the appropriate time.
[0030] Furthermore, in a preferred embodiment, a material transfer jacket 12 is provided on the lower circulation pipe 7 to discharge a portion of the salt-making mother liquor in the evaporation chamber 1 to the next-effect evaporation chamber; the material transfer jacket 12 is similar to a three-way valve, which has an inlet and two outlets, one of which is connected to the next-effect evaporation chamber through a pipeline. When the salt-making mother liquor in the evaporation chamber 1 is excessive, a portion of the salt-making mother liquor is discharged to the next-effect evaporation chamber by controlling the material transfer jacket 12 to prevent the salt-making mother liquor from overflowing, or when there is no large amount of salt particles precipitated from the salt-making mother liquor in the evaporation chamber 1, a portion of the salt-making mother liquor is discharged to the next-effect evaporation chamber by controlling the material transfer jacket 12, and new salt-making mother liquor is added to the evaporation chamber 1 at the same time, so that the material transfer jacket 12 of the previous effect can be connected to the evaporation chamber of the next effect, so that three sets of the apparatus of the present invention are connected in series and applied to the II effect, III effect, and IV effect evaporation of the salt-making mother liquor, respectively.
[0031] Furthermore, in a preferred embodiment, a salt dropping valve 301 is provided on the salt dropping pipe 3 .
[0032] Furthermore, in a preferred embodiment, a temperature probe 13 is provided at a position near the mouth of the salt drop pipe 3 at the bottom of the evaporation chamber 1; the temperature probe 13 is linked with the brine feed pump 5 and the salt drop valve 301, and the temperature probe 13 is used to monitor the temperature of the salt mother liquor in the evaporation chamber 1. When the salt mother liquor reaches the boiling temperature and a large amount of salt particles are precipitated, the temperature probe 13 sends a signal to control the opening of the washing brine feed pump 5 and the salt drop valve 301 to pump the washing brine into the salt slurry washing chamber 2. At this time, the salt particles fall into the salt slurry washing chamber 2 through the salt drop pipe 3, and the washing brine is sent into the evaporation chamber 1 through the salt drop pipe 3. The salt particles are washed by the washing brine in the salt drop pipe to achieve the first washing. The salt mother liquor stays in the evaporation chamber 1 due to the upward impact force of the washing brine. At this time, the salt mother liquor-salt particles-washing brine are in a dynamic equilibrium state. Example 2
[0033] This embodiment provides a countercurrent elutriation method based on precise control of nitrate content in nitrate-salt co-production. Figure 1 , which is applied in the II-effect evaporation of salt production mother liquor, and specifically includes the following steps: S1. Mother liquor feeding: inject a suitable amount of salt-making mother liquor into the evaporation chamber 1 of the current effect (i.e., effect II), and fill the salt slurry washing chamber 2 with refined brine as washing brine through the refined brine feeding pipe 4; wherein, the specific parameters of refined brine used in this embodiment are as follows:
[0034] S2, circulating heating evaporation: Turn on the centrifugal pump 6 to send the salt-making mother liquid in the evaporation chamber 1 to the upper circulation pipe 7 through the lower circulation pipe 7, and then heat it through the heating jacket 9 and flow back to the evaporation chamber 1, so that the salt-making mother liquid in the evaporation chamber 1 maintains the temperature and continues to evaporate to precipitate salt particles; S3, the first washing: after a large amount of salt particles are precipitated in the evaporation chamber 1, open the salt valve 301 on the salt pipe 3, and at the same time, open the refined brine feed pump 5 to continuously inject refined brine into the salt slurry washing chamber 2. At this time, salt particles of a certain size range fall into the salt slurry washing chamber through the salt pipe, and the refined brine is sent upward into the evaporation chamber through the salt pipe. The salt particles are washed by the refined brine in the salt pipe to achieve the first washing. The mother liquor of salt production stays in the evaporation chamber due to the upward impact force of the refined brine. The mother liquor of salt production-salt particles-washing brine The water is in a dynamic equilibrium state; the size of the salt particles falling from the salt pipe can be adjusted by controlling the speed of the refined brine feed pump 5 and then changing the flow rate of the brine in the salt pipe. Usually, the speed of the refined brine feed pump 5 is 25-40rpm. In addition, the injection amount of the washing brine should be controlled to be basically balanced with the evaporation amount of the salt mother liquor in the evaporation chamber to prevent excessive evaporation of the salt mother liquor in the evaporation chamber. Usually, the injection amount of the washing brine is 0.8-1.2 times the evaporation amount of the salt mother liquor in the evaporation chamber. S4, second washing: salt particles enter the salt slurry washing chamber through the salt drop pipe and continue to settle and contact with the refined brine to achieve the second washing; during this period, the salt discharge foot 8 is opened at regular intervals to discharge the salt particles at the bottom of the salt slurry washing chamber; S5. Mother liquor replenishment: When there is no large amount of salt particles precipitated in the evaporation chamber 1, a part of the salt-making mother liquor in the evaporation chamber 1 is discharged to the next effect (i.e., effect III) evaporation chamber 1 through the material transfer jacket 12, and at the same time, new salt-making mother liquor is added to the current effect evaporation chamber 1.
[0035] The countercurrent elutriation method of the present invention is applied to the III-effect and IV-effect evaporation of the salt-making mother liquor in the same manner as the above steps, except that the working parameters of the heating jackets and evaporation chambers of different effects are different, as follows:
[0036] Example 3 This example verifies the application effect of the countercurrent elutriation device provided in Example 1 and the countercurrent elutriation method provided in Example 2. The specific process is as follows: 1. Preparation of brine and salt making mother liquor
[0037] Washing brine: Take refined brine as washing brine. After testing, the sodium sulfate content of the refined brine in this embodiment is 23.71 g / L.
[0038] Salt making mother liquor: weigh 250 g of nitrate-containing salt (Na 2 SO 4 The content is 2.30%) is placed in a measuring cylinder, and then the above-mentioned refined brine is added to a total volume of 1000 mL, so that the salt-making mother liquor with a solid-liquid ratio of 25% is obtained.
[0039] 2. Countercurrent elutriation experimental steps
[0040] S1, mother liquor feeding: inject a proper amount of salt-making mother liquor into the evaporation chamber 1, and fill the salt slurry washing chamber 2 with refined brine as washing brine through the refined brine feeding pipe 4; S2, circulating heating evaporation: Turn on the centrifugal pump 6 to send the salt-making mother liquid in the evaporation chamber 1 to the upper circulation pipe 7 through the lower circulation pipe 7, and then heat it through the heating jacket 9 and flow back to the evaporation chamber 1, so that the salt-making mother liquid in the evaporation chamber 1 maintains the temperature and continues to evaporate to precipitate salt particles; S3, first washing: after a large amount of salt particles are precipitated in the evaporation chamber 1, open the salt valve 301 on the salt pipe 3, and at the same time, start the refined brine feed pump 5 to continuously inject refined brine into the salt slurry washing chamber 2, and control the pump speed to 30 rpm. At this time, the salt particles fall into the salt slurry washing chamber through the salt pipe, and the refined brine is sent upward into the evaporation chamber through the salt pipe. The salt particles are washed by the refined brine in the salt pipe to achieve the first washing. The salt-making mother liquor stays in the evaporation chamber due to the upward impact force of the refined brine, and the salt-making mother liquor-salt particles-washing brine are in a dynamic equilibrium state; S4, second washing: salt particles enter the salt slurry washing chamber through the salt drop pipe and continue to settle and contact with the refined brine to achieve the second washing; during this period, the salt discharge foot 8 is opened at regular intervals to discharge the salt particles in the salt slurry washing chamber 2; S5, mother liquor feed: after continuous injection of washing brine for 36 min, no large amount of salt particles are precipitated in evaporation chamber 1. At this time, the mother liquor in evaporation chamber 1, the washing brine in salt slurry washing chamber 2 and the salt discharged from the salt discharge foot 8 are taken as samples in turn, and the Na 2 SO 4 The content.
[0041] 3. Experimental results
[0042] Table 1 Na of each component in countercurrent elutriation 2 SO 4 content
[0043] It can be seen from Table 1 that after countercurrent washing, the Na 2 SO 4 The content is significantly greater than the Na in the liquid in the salt slurry washing chamber 2 SO 4 The content of Na in the nitrate-containing salt, that is, the mother liquor in the evaporation chamber did not flow downward, which preliminarily verified the feasibility of the countercurrent washing device. 2 SO 4 The content of Na in the salt product after the first washing by the device of the present invention is 2.30%. 2 SO 4 The Na in the salt product after the second washing was reduced to 0.19%. 2 SO 4 Reduced to 0.049%, SO 4 2- The content is 0.033% (after centrifugation and drying before testing), while the SO content of high-grade refined salt in GB / T 5461 Edible Salt is 4 2- The content must be ≤0.4%, SO4 2- The content is usually ≤0.1%, so the method and device of the present invention can effectively reduce the Na in salt 2 SO 4 content to meet the needs.
Claims
1. A countercurrent elutriation method based on precise control of nitrate content in nitrate-salt co-production, characterized in that: The steps include: S1, mother liquor feeding: inject a suitable amount of salt-making mother liquor into the current-effect evaporation chamber (1), and fill the salt slurry washing chamber (2) with washing brine through the brine feeding pipe (4); S2, circulating heating evaporation: turning on the centrifugal pump (6) to allow the salt-making mother liquor in the evaporation chamber (1) to be sent to the upper circulation pipe (7) through the lower circulation pipe (7), and then heated by the heating jacket (9) and then refluxed into the evaporation chamber (1), so that the salt-making mother liquor in the evaporation chamber (1) maintains the temperature and continues to evaporate to precipitate salt particles; S3, first washing: after a large amount of salt particles are precipitated in the evaporation chamber (1), the salt dropping valve (301) on the salt dropping pipe (3) is opened, and at the same time, the refined brine feed pump (5) is turned on to continuously inject washing brine into the salt slurry washing chamber (2). At this time, the salt particles fall into the salt slurry washing chamber through the salt dropping pipe, and the washing brine is sent upward into the evaporation chamber through the salt dropping pipe. The salt particles are washed by the washing brine in the salt dropping pipe to achieve the first washing. The salt making mother liquor stays in the evaporation chamber due to the upward impact force of the washing brine, and the salt making mother liquor-salt particles-washing brine are in a dynamic equilibrium state; S4, second washing: salt particles enter the salt slurry washing chamber through the salt drop pipe and continue to settle and contact with the washing brine to achieve the second washing; during this period, the salt discharge foot (8) is opened at regular intervals to discharge the salt particles at the bottom of the salt slurry washing chamber; S5. Mother liquor replenishment: When there is no large amount of salt particles precipitated in the evaporation chamber (1), a portion of the salt-making mother liquor in the evaporation chamber (1) is discharged to the next-effect evaporation chamber through the material transfer jacket (12), and at the same time, new salt-making mother liquor is replenished in the current-effect evaporation chamber (1).
2. A countercurrent elutriation method based on precise control of nitrate content in nitrate-salt co-production according to claim 1, characterized in that: In the step S3, when the refined brine feed pump (5) is turned on to continuously inject washing brine into the salt slurry washing chamber (2), the injection amount of the washing brine is controlled to be 0.8-1.2 times the evaporation amount of the salt production mother liquor in the evaporation chamber (1).
3. A countercurrent elutriation method based on precise control of nitrate content in nitrate-salt co-production according to claim 1, characterized in that: In the step S3, when the refined brine feed pump (5) is turned on to continuously inject washing brine into the salt slurry washing chamber (2), the rotation speed of the refined brine feed pump (5) is controlled to be 25-40 rpm.
4. A countercurrent elutriation method based on precise control of nitrate content in nitrate-salt co-production according to claim 1, characterized in that: The washed brine is refined brine.
5. A countercurrent elutriation device for the co-production of nitrate and salt, comprising an evaporation chamber (1), characterized in that: The invention also comprises a salt slurry washing chamber (2) arranged directly below the evaporation chamber (1), a salt drop pipe (3) whose upper end is connected to the bottom of the evaporation chamber (1) and whose lower end is sealed and extends into the washing chamber (2), a salt discharge foot (8) connected to the bottom of the salt slurry washing chamber (2), a refined brine feeding pipe (4) connected to one side of the washing chamber (2), a refined brine feeding pump (5) arranged on the refined brine feeding pipe (4), a centrifugal pump (6), a lower circulation pipe (7) whose one end is connected to one side of the evaporation chamber (1) and whose other end is connected to the feeding port of the centrifugal pump (6), an upper circulation pipe (13) whose one end is connected to the other side of the evaporation chamber (1) and whose other end is connected to the discharging port of the centrifugal pump (6), and a heating jacket (9) arranged on the upper circulation pipe (7) for heating the material transported in the upper circulation pipe (7).
6. A countercurrent elutriation device for nitrate-salt co-production as claimed in claim 5, characterized in that: A salt block crushing cone (14) is arranged at the bottom of the evaporation chamber (1), and the salt block crushing cone (14) comprises a hydraulic cylinder fixedly arranged at the bottom of the evaporation chamber (1), and a crushing cone (1401); the crushing cone is arranged at the telescopic end of the hydraulic cylinder and the end has a sharp portion, and the hydraulic cylinder drives the crushing cone (1401) to move toward the top of the salt drop pipe (3) to impact the salt particles that have formed large blocks at the mouth of the salt drop pipe (3).
7. A countercurrent elutriation device for nitrate-salt co-production as claimed in claim 5, characterized in that: A manhole (10) is provided on the top of the salt slurry washing chamber (2).
8. A countercurrent elutriation device for nitrate-salt co-production as claimed in claim 5, characterized in that: Salt slurry viewing mirrors (11) are provided on the bottom and the side walls at the middle position of the salt slurry washing chamber (2).
9. A countercurrent elutriation device for nitrate-salt co-production as claimed in claim 5, characterized in that: The lower circulation pipe (7) is provided with a material transfer jacket (12) for discharging a portion of the salt-making mother liquor in the evaporation chamber (1) to the next-effect evaporation chamber.
10. A countercurrent elutriation device for nitrate-salt co-production as claimed in claim 5, characterized in that: The salt dropping pipe (3) is provided with a salt dropping valve (301).
11. A countercurrent elutriation device for nitrate-salt co-production as claimed in claim 10, characterized in that: A temperature probe (13) is provided at the bottom of the evaporation chamber (1) at a position close to the opening of the salt drop pipe (3).