A method for reducing salt sludge in the production of pulverized, washed, and refined salt

Abstract

The present application belongs to the technical field of refined edible salt production, and discloses a method for reducing salt mud in the production of crushed and washed refined salt, wherein three streams of brine of different sources flowing into a brine storage tank to be sent to a clarifying tank are separated and treated respectively before entering the brine storage tank; the minimum nominal diameter of salt particles to be separated and recovered is determined according to the distribution rate of salt particles in the brine; a salt particle separator is designed and manufactured to separate out fine salt particle slurry; the separated fine salt particle slurry is combined into normal slurry of the corresponding process according to the characteristics of the separated fine salt particle slurry and the process conditions, so as to recover fine salt particles; and the brine from which the fine salt particles are separated is sent into the clarifying tank for precipitation treatment, thereby reducing the amount of salt mud formed by precipitation in the clarifying tank. The present application can separate and recover most of the fine salt particles contained in the brine into the product, reduce raw material consumption, increase product yield, reduce the amount of waste salt mud formed, and be beneficial to environmental protection and improvement of resource utilization rate and enterprise economic benefits.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of refined edible salt production, and particularly relates to a salt mud formed by the precipitation of fine salt particles contained in salt washing brine in a clarifying tank in the production of crushed and washed refined salt. BACKGROUND

[0002] At present, edible salt mainly includes refined salt, crushed and washed salt, and sun-dried salt. There are two process methods for the production of refined salt, namely, vacuum evaporation refined salt and crushed and washed refined salt. The crushed and washed refined salt process does not have an evaporation crystallization process compared with the vacuum evaporation refined salt process, and is a low-energy-consumption, green and environmentally-friendly production method, which is widely used in sea salt and lake salt production enterprises.

[0003] The production of crushed and washed refined salt mainly includes the following operation processes: the high-impurity-content raw salt (sea salt and lake salt) is crushed into particles of a required size, washed with saturated salt water (brine) to remove insoluble impurities (mud, grass, wood chips, algal debris, etc.) and soluble impurities (Ca 2+ , Mg 2+ , SO4 2- , K + , etc.), and then centrifuged, dried, screened and packaged into unit products.

[0004] Crushing, washing and centrifugal dewatering are the main links in the production of crushed and washed refined salt products.

[0005] The crushing function is to form salt particles and to break large particles into small particles, so as to increase the specific surface area of the salt and increase the solid-liquid contact surface during washing, so that the impurities can be removed in the washing process.

[0006] Washing is to use the property that saturated salt water (brine) no longer dissolves NaCl, while other compounds can continue to dissolve, to exchange the soluble and insoluble impurities from the surface of the salt crystals to the brine. Then, the brine and the impurities are separated from the qualified salt slurry in an overflow manner by using the principle that particles with different densities and particle sizes have different settling speeds in the brine.

[0007] The function of centrifugal dewatering is to spin out the brine in the salt slurry to form wet salt.

[0008] The production process of crushed and washed refined salt is shown in the attached Figure 2 The production process flow chart of crushed and washed refined salt is shown in the attached

[0009] Crushing is a key process for the formation of salt particles, but the maximum particle size can be controlled, while the minimum particle size cannot be controlled. Therefore, after crushing, the salt particles have a size distribution from the maximum particle size to 0 mm or above.

[0010] The washing process is a key process for forming the quality of the salt, and the raw material salt is washed with saturated brine (brine) to remove impurities therein. In the washing process, the brine maintains a certain flow rate, and the overflow discharges the impurity-containing washing salt brine into the brine storage tank, but at the same time, part of the fine salt particles are also taken into the brine storage tank with the overflow brine, and then all of them are sent into the brine clarifying tank for sedimentation treatment.

[0011] The centrifugal dewatering is a main link for forming the salt product. However, the centrifuge filter screen has a certain fixed gap, and in the process of centrifugal dewatering of the salt slurry, part of the salt particles with a particle size smaller than the filter screen gap pass through the filter screen gap to mix into the mother liquor brine and then enter the brine storage tank, and then all of them are sent into the brine clarifying tank for sedimentation treatment.

[0012] The brine entering the clarifying tank is changed into clear brine after the impurities are precipitated, and then is continuously used for washing new raw salt.

[0013] As can be seen, in addition to containing water-soluble impurities and water-insoluble impurities, the brine entering the clarifying tank also carries a considerable part of fine salt particles, and these fine salt particles are precipitated together with the impurities in the brine clarifying tank to form salt mud. When the brine clarifying tank is filled with salt mud, production has to be stopped to clean out the salt mud, and the brine clarifying tank has to be emptied to restore production.

[0014] The fine salt particles carried in the brine are already semi-finished products that have been processed and qualified, and as long as they are separated from the brine and dried, they are qualified products. However, because the particle size is smaller than the filter screen gap of the centrifuge and the settling speed is smaller than the rising speed of the overflow brine, the original production line solid-liquid separation device cannot effectively separate them, and they enter the clarifying tank with the brine to be precipitated together with other impurities to become salt mud.

[0015] Through testing and analysis of the salt mud, it is found that the main component of the salt mud is salt, the sodium chloride content is more than 93%, the water-insoluble component is less than 2%, and the salt particles with a particle size greater than 0.05 mm in the salt mud are more than 80%.

[0016] The problems and defects of the prior art are as follows:

[0017] (1) The particle formation in the crushing process is random, and the minimum particle cannot be controlled, so the salt particles after crushing are distributed from the maximum particle size to 0 mm or more;

[0018] (2) When the impurity-containing brine is overflowed and separated from the salt slurry, the fine salt particles cannot be effectively separated due to slow settling speed, and they enter the clarifying tank with the overflow brine to be precipitated together with other impurities to become salt mud;

[0019] (3) Part of the salt particles with a particle size smaller than the filter screen gap of the centrifuge pass through the filter screen gap to enter the mother liquor brine to the clarifying tank to be precipitated together with other impurities to become salt mud;

[0020] (4) Salt mud as soluble industrial waste residue, not only waste resources, but also increase the raw material consumption, piled up in the plant on the surrounding environment exist potential pollution threat. SUMMARY

[0021] In view of the problems existing in the prior art, the present application provides a method for reducing salt mud in the production of crushed washing refined salt.

[0022] The present application is achieved, a method for reducing salt mud in the production of crushed washing refined salt, the method for reducing salt mud in the production of crushed washing refined salt, comprising: the different sources of three impurity-containing brine flowing into the brine storage tank to be sent to the clarification tank are separated before entering the brine storage tank, and are treated respectively. The distribution rate of salt particles in each separated brine is determined, and the minimum nominal diameter of the salt particles to be separated and recovered is determined according to the distribution rate of salt particles. The brine containing fine salt particles is separated by using a salt particle separator designed and manufactured to separate fine salt particles, and the brine containing fine salt particles is circulated in the system to separate fine salt particles. The brine containing fine salt particles is subjected to salt particle separation treatment. Finally, the fine salt particles are recovered by filtering the salt particle filter cake formed by the centrifuge to the wet salt and become products. Thus, only the brine treated by the fine salt particle separation treatment is sent to the clarification tank for precipitation treatment, thereby reducing the generation of salt mud.

[0023] Further, the method for reducing salt mud in the production of crushed washing refined salt comprises the following steps:

[0024] Step one, for the overflow brine of the spiral salt washing machine, a natural sedimentation salt particle separator is designed and manufactured according to the brine flow and the minimum salt particle to be separated and recovered, and fine salt particles are separated from the brine by natural sedimentation using the salt particle separator; this mainly utilizes the high installation advantage of the spiral salt washing machine, without adding new power, fine salt particle separation and brine transportation to the clarification tank can be completed.

[0025] Step two, the fine particle salt slurry separated by the natural sedimentation salt particle separator is discharged to the stirring salt washing machine and is incorporated into the production line salt slurry, and becomes products after subsequent treatment; the recovery of fine salt particles separated from the overflow brine of the spiral salt washing machine is realized;

[0026] Step three, for the overflow brine of the salt slurry stirring tank, a centrifugal sedimentation salt particle separator combination kit is designed and manufactured according to the overflow brine flow of the salt slurry stirring tank and the minimum nominal diameter of the salt particles to be separated, and fine salt particles in the overflow brine of the salt slurry stirring tank are separated by using the centrifugal sedimentation salt particle separator combination kit;

[0027] Step four, the fine particle salt slurry separated by the centrifugal sedimentation salt particle separator combination kit is sprayed onto the salt particle filter cake formed by the centrifuge through the distributor, and the fine salt particles are recovered into the wet salt discharged from the centrifuge and incorporated into the products by using the interception effect of the salt particle filter cake formed in the centrifuge on the fine salt particles.

[0028] Step five, change the centrifuge mother liquor brine pipeline direction, make the centrifuge mother liquor brine return to the salt slurry stirring tank, and then enter the centrifuge again with the normal salt slurry, so that the centrifuge mother liquor brine always circulates in the closed loop of "salt slurry stirring tank - thickener - centrifuge - salt slurry stirring tank", after numerous cycles, the fine salt particles in the centrifuge mother liquor brine are gradually separated out by the filter cake interception, and finally recovered into the wet salt discharged by the centrifuge and become the product.

[0029] Further, in step one, according to the determination results of the salt particle distribution rate in the overflow brine of the spiral salt washing machine, the minimum nominal diameter of the salt particles to be separated and recovered is determined; combined with the overflow flow of the spiral salt washing machine under normal working conditions, the overflow cross-sectional area of the salt particle separator necessary for separating the minimum salt particles is calculated, and the salt particle separator is designed and manufactured. A flowmeter and a control valve are installed on the brine inlet pipe of the spiral salt washing machine to control the brine flow within the set range. The overflow brine of the spiral salt washing machine is separated from fine salt particles by natural sedimentation in the salt particle separator, and then the brine goes to the brine clarifying tank.

[0030] Further, in step three, according to the determination results of the salt particle distribution rate in the overflow brine of the salt slurry stirring tank, the minimum nominal diameter of the salt particles to be separated and recovered is determined; the nominal diameter and other parameters of the cyclone separator are calculated, and a special centrifugal sedimentation salt particle cyclone separator is designed and manufactured; the pressure drop of the cyclone separator is calculated, the processing flow of the cyclone separator is checked, the number of cyclone separators is determined, and they are installed in parallel combination; a brine pump that meets the set flow rate, flow and pressure drop of the cyclone separator is selected, and a flowmeter and a control valve are installed on the outlet of the brine pump to form a complete centrifugal sedimentation salt particle cyclone separator set with the cyclone separator; the brine flow is controlled within the set range so that it passes through the centrifugal sedimentation salt particle cyclone separator set to separate fine salt particles, and then the brine goes to the brine clarifying tank.

[0031] Further, in step five, the centrifuge mother liquid pipeline is modified from entering the brine storage tank to entering the salt slurry stirring tank, and combined with the salt slurry discharged from the countercurrent scrubber, so that the centrifuge mother liquid forms a closed loop infinite circulation of "salt slurry stirring tank - thickener - centrifuge - salt slurry stirring tank", and the fine salt particles in the centrifuge mother liquid are gradually separated out by the interception of the salt particle filter cake formed in the centrifuge, and recovered into the wet salt discharged by the centrifuge to become the product; the separation and recovery of fine salt particles in the centrifuge mother liquid brine are realized; at the same time, the centrifuge mother liquid finally becomes part of the overflow brine of the salt slurry stirring tank, which is included in the overflow brine of the salt slurry stirring tank for processing in the next step.

[0032] Another object of the present application is to provide a system for separating and recycling fine salt particles contained in salt washing brine in the production of crushed, washed and refined salt, which applies the method for reducing salt mud in the production of crushed, washed and refined salt.

[0033] A brine treatment module is used to separate and treat three streams of brine of different sources flowing into the brine storage tank before being sent to the clarifying tank.

[0034] A salt particle diameter determination module is used to determine the salt particle distribution rate in the brine, and determine the minimum nominal diameter of the salt particles to be separated and recycled according to the salt particle distribution rate.

[0035] A fine salt particle separation module is used to design and manufacture a salt particle separator to separate fine salt particle slurry, and combine the separated fine salt particle slurry to the normal salt slurry of the corresponding process.

[0036] A fine salt particle recycling module is used to recycle fine salt particles, and send the brine from which the fine salt particles are separated back to the clarifying tank for precipitation treatment.

[0037] Another object of the present application is to provide a computer device comprising a memory and a processor, wherein the memory stores a computer program, and the computer program is executed by the processor to enable the processor to perform the steps of the method for reducing salt mud in the production of crushed, washed and refined salt.

[0038] Another object of the present application is to provide a computer readable storage medium storing a computer program, wherein the computer program is executed by a processor to enable the processor to perform the steps of the method for reducing salt mud in the production of crushed, washed and refined salt.

[0039] Another object of the present application is to provide an information data processing terminal for implementing the system of the method for reducing salt mud in the production of crushed, washed and refined salt.

[0040] In combination with the above technical solutions and the technical problems solved, the technical solution of the present application has the following advantages and positive effects:

[0041] The present application provides a method for separating and recycling fine salt particles contained in salt washing brine in the production of crushed, washed and refined salt before the fine salt particles enter the clarifying tank for precipitation to form salt mud. The present application analyzes the size distribution of impurities and salt particles in three streams of brine of different sources, finds a way to separate fine salt particles from brine of different sources, and a recycling method, separates and recycles fine salt particles in the brine to the product, and reduces the number of salt particles in the brine precipitated in the clarifying tank to form salt mud.

[0042] The brine forming salt slurry has three sources, one is overflow brine from the spiral salt washing machine, one is overflow brine from the salt slurry mixing tank, and the other is mother liquor brine from the centrifuge.

[0043] The overflow brine from the spiral salt washing machine contains fine salt particles because the overflow brine outlet area of the spiral salt washing machine settling section is fixed. In order to make the overflow brine carry out the insoluble impurities washed out from the raw salt, the salt washing brine entering the spiral salt washing machine is set to a certain flow rate (1 m 3 The overflow brine outlet of the spiral salt washing machine settling section maintains a certain upward velocity, and the salt particles with a settling velocity less than the upward velocity of the brine will overflow the spiral salt washing machine into the brine storage tank along with the overflow brine (the upward velocity of the brine is 1.5 mm / s, and the salt particles in the overflow brine are mainly salt particles less than 0.125 mm). The brine in the brine storage tank is then pumped into the clarifier for natural settling into salt slurry. Since this part of the brine is the first washing of the raw salt, the impurity particles in the brine are larger in size and more in number. Also, the spiral salt washing machine is generally installed at a higher position, with an installation height generally higher than that of the mixing salt washing machine and the brine clarifier. Therefore, the separation of salt particles, brine and salt slurry by natural settling does not require additional power, and can be completed by gravity flow. The salt particles separated from this part of the brine by the natural settling separator contain some impurity particles with a larger settling velocity, so the separated salt particles are recycled into the mixing salt washing machine and combined with the main stream of normal salt slurry for further washing and treatment to ensure product quality. Through the above treatment, the brine containing fine salt particles is separated and then enters the clarifier. This reduces the amount of salt slurry formed from the overflow brine of the spiral salt washing machine.

[0044] The overflow brine from the salt slurry mixing tank contains fine salt particles, because the salt slurry mixing tank is designed with a certain overflow brine flow rate according to the cross-sectional area of the fixed cylinder, so that the overflow brine carries out the insoluble impurities washed out from the salt slurry. The overflow flow rate of the salt slurry mixing tank keeps the brine in the salt slurry mixing tank at a certain rising speed, and the settling speed of salt particles of different sizes in the brine is different, the smaller the salt particles, the slower the settling speed. The salt particles with a settling speed smaller than the rising speed of the brine will overflow the salt slurry mixing tank with the overflow brine, enter the brine storage tank, and then be pumped into the clarifying tank to naturally settle as salt mud. (According to the test, the rising speed of the overflow brine is about 1.5 mm / s during normal production, and most of the salt particles carried out by the brine are salt particles with a particle size of less than 0.125 mm.) However, this part of the salt slurry has been washed twice by the spiral salt washing machine and the counterflow salt washing device, and the insoluble impurities contained in the overflow brine are relatively small, and these impurities are light in density and small in particle size. By designing a suitable cyclone separator, the brine can pass through the cyclone separator at a certain rotating speed, so that fine salt particles can be separated from the brine. The separated fine salt slurry is sprayed onto the salt particle filter cake formed by the centrifuge by the distributor to utilize the interception of the filter cake to filter and recover the fine salt particles into the wet salt. The brine separated from the salt particles is then sent to the clarifying tank, thereby reducing the amount of salt mud formed by the salt particles contained in the overflow brine from the salt slurry mixing tank.

[0045] The mother liquor brine from the centrifuge contains fine salt particles, because the filter screen of the centrifuge has a fixed gap (0.16 mm or 0.25 mm gap filter screen is generally selected for the production of crushed, washed and refined salt), so that during the dehydration process of the salt slurry in the centrifuge, part of the salt particles smaller than the filter screen gap pass through the filter screen gap and enter the mother liquor brine with the spun-out mother liquor brine into the brine storage tank, and then are pumped into the clarifying tank to naturally settle as salt mud. Among the salt slurry entering the centrifuge, salt particles of sizes between 0.85 mm and 0.01 mm are distributed, but not all salt particles smaller than the filter screen gap will pass through the filter screen gap and enter the mother liquor brine. Only when the salt slurry contacts the bare filter screen for an instant, a large number of salt particles smaller than the filter screen gap will pass through the gap and enter the brine. Once the salt slurry filters part of the brine to form a filter cake, due to the interception of the filter cake, most of the salt particles smaller than the gap in the salt slurry will be filtered down by the filter cake. Only a small part of the smaller salt particles will pass through the filter cake and the filter screen gap and enter the brine. Therefore, by returning the mother liquor brine from the centrifuge to the salt slurry mixing tank and then entering the centrifuge again with the normal salt slurry, part of the salt particles smaller than the filter screen gap will be filtered and recovered into the product due to the interception of the filter cake. Although the salt slurry entering the centrifuge always has salt particles smaller than the filter screen gap entering the mother liquor brine, the mother liquor brine is not directly discharged from the system, but always circulates in a closed loop inside the "salt slurry mixing tank - thickener - centrifuge - salt mixing and washing machine". After countless cycles, the salt particles contained in the mother liquor brine from the centrifuge will be filtered out by the filter cake and recovered into the product, thereby reducing the amount of salt mud formed by the salt particles contained in the mother liquor brine from the centrifuge.

[0046] The present application separates the salt particles contained in the three groups of brine by different methods, and then sends them into the clarification tank for treatment, thereby reducing the amount of salt particles in the clarification tank and the amount of salt mud formed.

[0047] The method for reducing salt mud in the production of crushed and washed refined salt provided by the present application provides a method for separating and recovering fine salt particles contained in the salt washing brine in the production of crushed and washed refined salt, separates the three groups of brine flowing into the brine storage tank, respectively processes each group, separates the salt particles in the brine, and recovers them into the product, thereby reducing the salt particle content of the brine entering the clarification tank and reducing the amount of salt mud generated in the clarification tank.

[0048] Compared with the current production method of crushed and washed refined salt, the present application separates most of the fine salt particles contained in the brine before entering the clarification tank, recovers them into the product, reduces raw material consumption, increases product yield, reduces the amount of waste salt mud formed, protects the environment, improves resource utilization, and is beneficial to improving the economic benefits of enterprises.

[0049] The expected income and commercial value of the technical solution of the present application after transformation are: the present application only adds a cyclone separator combination kit and a natural sedimentation separator, two simple devices, to the original crushed and washed refined salt production line, adds a cloth pipe to the centrifuge, and makes some corresponding modifications to the brine pipeline. Fine salt particles in the brine can be separated and recovered. The technical solution transformation investment is small, all the separated salt particles are recovered and converted into refined salt products, the amount of salt mud formed is reduced, the consumption and production cost are reduced, the product yield is increased, and good economic benefits are obtained.

[0050] Refined salt products play an important role in industry, agriculture, and human health. Salt is a necessity for human life and a basic raw material for the chemical industry, and also has a wide range of uses in other industries and agriculture.

[0051] People must eat salt, it is not only an important seasoning, but also essential minerals in human tissues, closely related to health. Adults generally contain 90 g of sodium, 85 g of chlorine, most of which exists in body fluids. Sodium is the main cation in extracellular fluid (plasma and interstitial fluid, including lymphatic fluid) electrolyte, is the mainstay of maintaining extracellular fluid volume and osmotic pressure, has an important role in muscle contraction, heart beat, blood circulation, nerve information transmission, carbohydrate and protein metabolism, body fluid acid-base balance, etc. Chlorine also has the effect of maintaining the balance of acid-base balance and osmotic pressure in the body, and is the main anion of electrolytes in gastric juice, which can promote hydrochloric acid and help digestion. If the body lacks salt, it will be weak, apathetic, and dizzy when standing; if it is serious, it will be nausea and vomiting, painful muscle spasm, edema, and blood pressure drop; if it is extremely serious, it will be stupor, nausea, vomiting, and even coma, and further blood pressure drop. This requires the supplement of sodium chloride excreted with urine and sweat, and adults generally need to intake 5-8 g of sodium chloride per day, and the intake amount should be appropriately increased in summer or high-temperature environment due to more sweating.

[0052] As a means of production, salt is the mother of chemical industry, which is the basic industry of national economy, and three acids (hydrochloric acid, sulfuric acid, nitric acid) and two alkalis (caustic soda and soda ash) are basic chemical industries, and among them, hydrochloric acid, caustic soda and soda ash are all produced by taking salt as the main raw material. Therefore, it can be said that the overall development of the national economy depends on the development of the chemical industry, and the development of the chemical industry depends on the development of the salt industry. Most of the chlorine and sodium used in other chemical products are obtained from table salt. In addition, table salt has a wide range of uses in food, feed, leather, ceramics, glass, soap, dye, oil, mining, pharmaceutical and other industrial departments, as well as water treatment, ice making and refrigeration, highway snow removal, etc.

[0053] The technical scheme of the present application fills the technical gap at home and abroad: the production of crushed, washed and refined salt has a production history of more than 50 years, but there is no relevant research report and intellectual property protection announcement on the research of reducing the amount of salt mud formed by recovering fine salt particles in salt washing brine at home and abroad, and the technical scheme of the present application fills the technical gap at home and abroad.

[0054] The technical scheme of the present application solves the technical problem that people have been eager to solve but have always failed to succeed: the crushed, washed and refined salt process is one of the main methods of edible salt production, and the important link production technology is mature. In the salt washing process, the water-insoluble substances are separated and washed out, and the clarification is a necessary link. It is a heavy work to clear and dig the salt mud in the clarification tank, especially when it is found that most of the salt mud is salt particles. It is thought to reduce the amount of salt mud, but this part of the fine salt particles is too small, and a suitable solution has always been found. The present application creatively solves the problem of salt mud.

[0055] The technical scheme of the present application overcomes the technical prejudice: as the salt making industry is a traditional industry, most enterprises survive and develop by scale effect, and do not pay enough attention to the proportion of raw material consumption, and secondly, the movement mechanics law of the fine salt particles in the salt washing brine is not well understood, and no in-depth research is conducted on the design of separation equipment by using the movement characteristics of the salt particles in the brine, and it is considered that the fine salt particles cannot be separated. Only the salt mud is washed and dissolved by water, and discharged as waste water, or directly dug out and treated as waste residue. The technical scheme of the present application analyzes and studies the fluid dynamics movement law of the salt particles and insoluble impurities in the salt washing brine, designs a fine salt particle separation equipment by using the movement law of the salt particles, first separates the fine salt particles from the brine, and then uses the interception and filtration effect of the normal salt particle filter cake on the fine salt particles to dry the water in the filter cake and recover it into the product, and creatively solves the problem of salt mud. BRIEF DESCRIPTION OF DRAWINGS

[0056] In order to more clearly illustrate the technical scheme of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly introduced as follows. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0057] Figure 1 is a flow chart of the method for reducing salt mud in the production of crushed and washed refined salt provided by the embodiments of the present application;

[0058] Figure 2 is a process flow chart of the production process of crushed and washed refined salt provided by the embodiments of the present application;

[0059] Figure 3 is a process flow chart of the method for reducing salt mud in the production of crushed and washed refined salt provided by the embodiments of the present application;

[0060] Figure 4 is a process flow chart of the method for reducing salt mud in the production of crushed and washed refined salt provided by the embodiments of the present application;

[0061] Figure 5 is a process flow chart of the method for reducing salt mud in the production of crushed and washed refined salt provided by the embodiments of the present application;

[0062] Figure 6 is a schematic diagram of the installation position of the fine salt slurry distribution pipe provided by the embodiments of the present application;

[0063] Figure 7 is an analysis schematic diagram of the circular motion of the salt particles in the cyclone provided by the embodiments of the present application;

[0064] Figure 8 is a design parameter schematic diagram of a cyclone separator provided by the embodiment of the present application;

[0065] In the figure: 1, control valve; 2, flow meter; 3, spiral salt washing machine; 4, settling separator; 5, stirring salt washing machine; 6, salt slurry pump; 7, crusher; 8, brine storage tank; 9, brine pump; 10, control valve; 11 flow meter; 12, cyclone separator; 13, salt slurry stirring tank; 14, salt slurry pump; 15, thickener; 16, centrifuge; 17, brine clarifier; 18, rotary drum; 19, filter screen; 20, salt slurry feeding pipe; 21, salt particle filter cake; 22, piston pusher; 23, feeding hopper; 24, fine particle salt slurry distribution pipe; 25, wet salt; 26, filtrate brine; 27, mother liquor brine. DETAILED DESCRIPTION

[0066] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and do not limit the present application.

[0067] In view of the problems existing in the prior art, the present application provides a method for reducing salt mud in the production of crushed, washed and refined salt, which is described in detail below in combination with the accompanying drawings.

[0068] In order to enable those skilled in the art to fully understand how the present application is specifically implemented, this part is an explanatory description of the embodiments of the technical scheme of the claims.

[0069] As shown in the figure, the method for reducing salt mud in the production of crushed, washed and refined salt provided by the embodiment of the present application comprises the following steps: Figure 1

[0070] S101, three streams of brine of different sources flowing into the brine storage tank to be sent to the clarifier are separated before entering the brine storage tank and are respectively treated;

[0071] S102, the salt particle distribution rate in the brine is measured, and the minimum salt particle nominal diameter to be separated and recovered is determined according to the salt particle distribution rate;

[0072] S103, a salt particle separator is designed and manufactured to separate fine salt particle salt slurry, and the separated fine salt particle salt slurry is combined into normal salt slurry of the corresponding process according to the characteristics of the separated fine salt particle salt slurry and the process conditions thereof;

[0073] S104, the fine salt particles are recovered, and the brine from which the fine salt particles are separated is sent into the clarifier for sedimentation treatment again.

[0074] As a preferred embodiment, as shown in the figure, the method for reducing salt mud in the production of crushed, washed and refined salt provided by the embodiment of the present application comprises the following steps: Figure 3 ​As shown, the method for reducing salt mud in the production of crushed, washed and refined salt provided by the embodiment of the application specifically comprises the following steps:

[0075] Step 1, first, the salt particle distribution rate in the overflow brine of the spiral salt washing machine is determined, according to the salt particle distribution rate, the minimum nominal diameter of the salt particles to be separated and recovered is determined, and a salt particle separator is designed and manufactured according to the same. The overflow brine of the spiral salt washing machine is allowed to pass through the salt particle separator, the salt particles are separated from the brine, the brine is then sent to the clarifier, and the separated fine salt slurry is discharged to the agitated salt washing machine, combined with the normal salt slurry, treated subsequently, and incorporated into the product, so that the separation and recovery of the fine salt particles in the overflow brine of the spiral salt washing machine are realized.

[0076] Step 2, the centrifuge mother liquor brine pipeline is modified from entering the brine storage tank to entering the salt slurry agitated tank, and is mixed with the salt slurry discharged from the countercurrent washer, so that the centrifuge mother liquor brine is always circulated in the closed loop of “salt slurry agitated tank-thickener-centrifuge-salt slurry agitated tank”, the fine salt particles in the centrifuge mother liquor brine are gradually separated out by the interception of the salt particle filter cake formed by the centrifuge, and are recovered into the wet salt discharged from the centrifuge and incorporated into the product, so that the separation and recovery of the fine salt particles in the centrifuge mother liquor brine are realized.

[0077] Step 3, after the above two brines are separately treated, only the overflow brine of the salt slurry agitated tank is left to enter the brine storage tank. First, the salt particle distribution rate in the overflow brine of the salt slurry agitated tank is determined, according to the salt particle distribution rate, the minimum nominal diameter of the salt particles to be separated and recovered is determined, and a salt particle separator (cyclone separator) is designed and manufactured according to the same. The brine in the brine storage tank is first pumped into the cyclone separator, so that the brine is rotated at high speed, the salt particles are separated out by the centrifugal force, and then the brine is sent to the clarifier. The separated fine salt slurry is sprayed onto the salt particle filter cake formed by the centrifuge through a distributor, the fine salt particles are filtered and recovered into the wet salt discharged from the centrifuge by the interception of the salt particle filter cake, and are incorporated into the product, so that the separation and recovery of the fine salt particles in the overflow brine of the salt slurry agitated tank are completed.

[0078] The process flow is shown in the accompanying Figure 3 The process flow chart of the method for reducing salt mud in the production of crushed, washed and refined salt.

[0079] The method for reducing salt mud in the production of crushed, washed and refined salt provided by the embodiment of the application further comprises:

[0080] The design, manufacture and operation control method of the settling separator. The key size of the settling separator, i.e. the overflow port cross-sectional area, is determined according to the overflow brine flow rate, brine solid-liquid ratio, brine viscosity and salt particle density of the spiral salt washing machine during normal production, and the settling separator special for the production of crushed, washed and refined salt is designed and manufactured. Meanwhile, a brine flow meter and a control valve are installed on the brine inlet pipe of the spiral salt washing machine, the brine flow rate into the settling separator is indirectly limited to not more than the set maximum flow rate by controlling the brine flow rate into the spiral salt washing machine, and thus the fine salt particles can be separated and recovered from the brine. Details are shown in the attached Figure 4 The process flow diagram for separating and recovering the salt particles in the overflow brine of the spiral salt washing machine.

[0081] The design, manufacture and operation control method of the cyclone separator. The cyclone separator is calculated and designed according to the overflow brine flow rate, brine solid-liquid ratio, brine viscosity and salt particle density of the salt slurry stirring tank during normal production, and a suitable brine pump (the flow rate and head of the brine pump are consistent with the design requirements of the flow rate and pressure drop of the cyclone separator) is selected, a flow meter and a control valve are installed on the outlet of the brine pump, and the brine flow rate is controlled to not less than the limited flow rate, so that the brine reaches the specified rotation speed, and thus the fine salt particles can be centrifugally separated from the brine. Details are shown in the attached Figure 5 The process flow diagram for separating and recovering the salt particles in the overflow brine of the salt slurry stirring tank and the mother liquor brine of the centrifugal machine.

[0082] The design and installation method of the fine salt slurry distributor. The fine salt slurry separated by the cyclone separator is sprayed onto the salt particle filter cake just formed in the centrifugal machine by the fine salt slurry distributor, the brine in the fine salt slurry is thrown away by the interception of the salt particle filter cake, the fine salt is filtered into the wet salt, and the fine salt is recovered. Specifically, the centrifugal settling salt particle separator is installed above the centrifugal machine and parallel to the thickener, the fine salt slurry pipeline at the bottom of the centrifugal settling separator is connected to the normal salt slurry inlet pipeline and enters the centrifugal machine, and then the pipeline opening is installed at the position of the salt particle filter cake just formed in the rotating drum, the fine salt slurry is sprayed onto the salt particle filter cake just formed by the normal salt slurry, the brine in the fine salt slurry is thrown away by the interception of the salt particle filter cake, the fine salt is filtered into the wet salt, and the fine salt is recovered. Details are shown in the attached Figure 6 The installation schematic diagram of the fine salt slurry distributor.

[0083] Through the above steps and methods, most of the fine salt particles contained in the three streams of brine are separated and recovered into the product, so that the total amount of salt particles entering the brine clarifier is reduced, and the amount of salt mud formed is reduced.

[0084] The separation of the fine salt particles contained in the overflow brine of the spiral salt washing machine in the method for reducing salt mud in the production of crushed, washed and refined salt provided by the embodiments of the present application is implemented as follows:

[0085] The natural settlement salt particle separator is used for treating overflow brine from a spiral salt washing machine to separate fine salt particles from the brine. The design of the natural settlement salt particle separator mainly determines the overflow section area and the brine flow.

[0086] Firstly, the force acting on the salt particles in the natural settlement separator is analyzed to calculate the settlement speed of the salt particles.

[0087] It is assumed that the salt particles are small spherical and the salt particles are linearly and uniformly downwardly settled at a constant speed.

[0088] And it is assumed that:

[0089] U0——the settlement speed of the salt particles, m / s;

[0090] ρ S ——the density of the salt particles, kg / m 3 ;

[0091] ρ——the density of the clear brine, kg / m 3 ;

[0092] d——the nominal diameter of the smallest salt particles to be separated and recovered, m;

[0093] g——the gravity acceleration, m / s 2 ;

[0094] ζ——the resistance coefficient, dimensionless;

[0095] π——the circular constant;

[0096] μ——the viscosity of the brine, kg / m s (Pa s);

[0097] Then:

[0098]

[0099]

[0100] The force acting on the salt particles during the linear and uniform downward settlement of the salt particles is:

[0101] Gravity - buoyancy = resistance

[0102] That is:

[0103] Solving the equation:

[0104] The settlement speed of the salt particles:

[0105] The resistance coefficient ζ

[0106] The drag coefficient of brine to salt particles is a function of Reynolds number when brine and salt particles move relatively: ζ = f (Re)

[0107] And

[0108] Because the salt particles have a slow settling speed, the flow of brine around the salt particles can be considered as laminar flow, and in the laminar flow state, ζ = 24 / Re (Re < 0.3).

[0109] Therefore, the settling speed of the salt particles is:

[0110] The settling speed of the minimum nominal diameter salt particles to be separated and recovered is calculated according to the above formula.

[0111] To separate these salt particles, the upward velocity of the brine in the natural settling tank must be less than the settling speed of the salt particles.

[0112] The flow rate of the brine entering the spiral salt washing machine is equal to the flow rate of the brine entering the natural settling tank, and the normal working brine flow rate of the spiral salt washing machine is Q (m 3 / h);

[0113] Therefore, the minimum design area of the overflow section of the natural settling tank is A = Q ÷ U0 (m 2 ). The natural settling tank is manufactured with an overflow area greater than A, and the brine flow rate is controlled to be no more than Q (m 3 / h), so that the upward velocity of the brine is less than U0 (m / h), and the minimum nominal diameter salt particles to be separated and recovered can be settled at the bottom of the tank and separated from the brine. The overflow brine of the settling tank is directly discharged to the clarifier.

[0114] In the method for reducing salt mud in the production of crushed and washed refined salt, the separation of fine salt particles from the overflow brine of the salt slurry stirring tank is achieved as follows:

[0115] The fine salt particles separated from the natural settling tank are discharged into the agitated salt washing machine and into the salt slurry production line, and are treated and added to the product after subsequent treatment, thereby completing the recovery of fine salt particles from the overflow brine of the spiral salt washing machine.

[0116] In the method for reducing salt mud in the production of crushed and washed refined salt, the separation of fine salt particles from the overflow brine of the salt slurry stirring tank is achieved as follows:

[0117] A special centrifugal settling salt particle separator is designed and manufactured to separate the salt particles from the overflow brine of the salt slurry stirring tank by using centrifugal force, and the centrifugal settling salt particle separator is designed as follows.

[0118] The centrifugal sedimentation salt particle separator adopts the circular cone structure of a long conical cyclone separator, which makes the brine move in a circular motion inside the circular cone, generating a centrifugal force field in the brine. This gives the salt particles sufficient centrifugal force and radial velocity. Before the brine leaves the centrifugal sedimentation salt particle separator, the salt particles pass through the brine and reach the wall of the separator, where they are separated from the underflow.

[0119] To separate salt particles of a set size using a centrifugal sedimentation separator, two steps are required: first, to calculate and determine the critical dimensions of the centrifugal separator and design and manufacture the corresponding centrifugal sedimentation separator; second, to calculate and determine the critical parameters of the brine pump—flow rate and head—so that the brine pump flow rate matches the processing flow rate of the centrifugal sedimentation separator, and the brine pump head is greater than the pressure drop required by the centrifugal separator, so that the brine reaches the set tangential rotation speed within the centrifugal separator.

[0120] The following steps involve calculating and determining three key parameters of the centrifugal sedimentation separator:

[0121] 1. The nominal diameter of the hydrocyclone;

[0122] 2. The corresponding throughput of the hydrocyclone;

[0123] 3. Hydrocyclone brine inlet pressure.

[0124] The first step is to determine the nominal diameter and other dimensional parameters of the hydrocyclone.

[0125] First, the force situation of the salt particles in the hydrocyclone is analyzed (see appendix for details). Figure 7 (A schematic diagram illustrating the circular motion of salt particles in a hydrocyclone). See attached diagram. Figure 7 As shown, the brine undergoes circular motion in the hydrocyclone, generating a centrifugal force field. The salt particles are subjected to three forces in this field: the centrifugal force on the salt particles, the centrifugal force on the brine displaced by the salt particles, and the resistance force from the brine on the salt particles.

[0126] For ease of analysis, the force factors are set as follows:

[0127] u t — Tangential velocity of the salt grain, m / s;

[0128] u r —Radial settling velocity of salt particles, m / s;

[0129] r—radius of rotation of the salt grain, in meters;

[0130] ρ S —Density of salt grains, kg / m³ 3 ;

[0131] ρ — density of clear brine, kg / m³ 3 ;

[0132] d - the nominal diameter of the salt particles, m;

[0133] ζ - the drag coefficient, dimensionless;

[0134] π - the circle constant;

[0135] μ - the viscosity of the brine, kg / m s = Pa s;

[0136] then:

[0137]

[0138]

[0139]

[0140] The direction of the resistance is also radial, but points to the center of rotation.

[0141] The force and the resistance reach equilibrium, then the velocity u of the salt particles leaving the center of rotation r reaches a constant (acceleration is zero).

[0142] Let the magnitude of the force and the resistance be equal, and the solution to reach equilibrium is:

[0143]

[0144] u r is the settling velocity of the salt particles under the action of centrifugal force,

[0145] The radial movement of the salt particles in the brine is slow, and the relative motion of the salt particles and the brine belongs to laminar flow, the drag coefficient ζ = 24 / Re, (Re < 0.3).

[0146]

[0147] After simplifying, we get:

[0148]

[0149] The maximum distance of the salt particles running in the radial direction before reaching the wall of the device is equal to the width b of the brine inlet, that is, the thickness of the brine.

[0150] Therefore,

[0151] Let the number of revolutions of the brine before entering the center overflow pipe in the cyclone be N, then the distance of movement is 2πrN, so we get:

[0152] The settling time of the salt particles to reach the wall of the cyclone is just the time for the salt particles to be separated from the brine, so the settling time is just equal to the residence time of the salt particles, and the salt particles with the settling time equal to the residence time are the smallest salt particles that can be separated. Let the expressions of the above two times be equal, and let d in the expression be changed to the critical diameter d c , we have:

[0153]

[0154]

[0155] It can be seen from the expression that the nominal diameter of the smallest salt particles that can be settled is related to the material properties (μ, ρ, ρ s ), the tangential velocity of the salt particles (u t ), and the inlet width b of the cyclone and the number of rotations N (the size of N depends on the cone angle, and the smaller the cone angle, the larger N is).

[0156] Under normal production conditions, the material properties are basically stable, and (μ, ρ, ρ s ) can be regarded as constants.

[0157] The nominal diameter of the smallest salt particles that can be settled is only related to the brine flow rate (u t ), the inlet thickness (b) of the cyclone, and the cone angle.

[0158] Here, by setting a fixed minimum tangential velocity u t of the salt particles (u t is approximately equal to the inlet flow rate of the brine) and a minimum number of rotations N of the brine (N is set to be 5), and the nominal diameter of the smallest salt particles to be separated, the inlet width (b) of the cyclone can be calculated.

[0159]

[0160] The inlet height a of the cyclone is calculated as twice the width b to obtain the cross-sectional area of the rectangular inlet of the cyclone:

[0161] S 矩形 = b x 2b

[0162] The equivalent area of the circular tube inlet pipe diameter d1 is calculated:

[0163]

[0164]

[0165] According to the design of the long cone type cyclone, see the attached Figure 8 cyclone design parameter diagram.

[0166] The nominal diameter of the cyclone is D = 4d1;

[0167] Overflow pipe diameter: d2 = D / 3

[0168] Underflow pipe diameter: d3 = D / 4 (a valve is installed on the underflow pipe outlet flange to adjust the underflow area or a Venturi short pipe with different diameter is installed to adjust the discharge to achieve the best separation effect).

[0169] Cone angle α = 10°;

[0170] Second step, calculation of the cyclone processing capacity.

[0171] The nominal diameter and other size parameters of the cyclone are determined based on the set tangential velocity of the salt particles and the number of rotations, as well as the formula for calculating the nominal diameter of the critical minimum salt particles to be separated.

[0172] That is, according to: Formula.

[0173] Therefore, to achieve the goal of separating the critical minimum nominal diameter salt particles, the rotation speed of the salt particles in the cyclone (i.e. the rotation speed of the brine) must reach the set speed. Because the brine enters the cyclone and the speed gradually increases as the cone angle decreases, the brine inlet speed is the minimum speed of the outer cyclone of the cyclone, which does not affect the separation efficiency.

[0174] In this way, the processing capacity Q of the cyclone is approximately equal to the product of the cross-sectional area of the inlet pipe and the flow speed of the brine.

[0175] Q = a x b x u t

[0176] Where: b is the width of the cyclone inlet pipe, m;

[0177] a is the height of the cyclone inlet pipe, m;

[0178] u t is the flow speed of the brine in the cyclone inlet pipe, m / s.

[0179] In the case of a fixed and unchangeable inlet size, u t only depends on the inlet speed provided by the brine pump. However, from the perspective of economic efficiency, it is not possible to infinitely increase the pressure to increase the flow speed, but a certain pressure is selected to maintain a reasonable flow speed range.

[0180] Although the size of the overflow and the size of the cone angle also affect the processing capacity, the impact is not very large, and in actual production, it is within the range of adjustment and control, therefore, the processing capacity of the cyclone calculated according to the above formula can be used as the basis for determining the number of units required. If the processing capacity (Q) is greater than the task capacity (W), then install one; if the processing capacity is less than the task capacity, then the number of units is equipped according to the result of dividing the task capacity (W) by the processing capacity (Q), and is installed in parallel.

[0181] Third step, according to the empirical formula to calculate the brine through the cyclone pressure drop:

[0182]

[0183] In the formula: -ΔP is the pressure drop of cyclone, Pa;

[0184] a is the cyclone brine inlet height, m;

[0185] b is the cyclone brine inlet width, m;

[0186] d2 is the cyclone overflow pipe diameter, m;

[0187] ρ is the density of the clear brine, kg / m 3 ;

[0188] u t is the brine inlet velocity, m / s.

[0189] When the brine pump is selected, the brine pump head should be increased by the pressure drop corresponding to the original brine pump head.

[0190] The brine pump thus selected is used with the designed and manufactured cyclone in one or parallel with several to separate all salt particles larger than the planned particle size to be separated.

[0191] The recovery of fine salt particles in the brine overflow from the salt slurry stirring tank in the method for reducing salt mud in the production of crushed, washed and refined salt is realized as follows:

[0192] The centrifugal settling salt particle separator is installed above the centrifuge and parallel to the thickener. The fine particle salt slurry pipeline of the centrifugal settler underflow is connected to the normal salt slurry feeding pipe and enters the centrifuge. Then the pipe opening is installed at the position of the salt particle filter cake just formed by the rotating drum. The fine particle salt slurry is sprayed onto the normal salt slurry filter cake just formed, and the interception of the salt particle filter cake will shake off the brine in the fine particle salt slurry and filter the fine particle salt into the wet salt, thus realizing the recovery of fine particle salt. See the attached Figure 6 Installation diagram of fine particle salt slurry distributor.

[0193] The separation of the fine salt particles in the centrifuge mother liquor brine in the method for reducing salt mud in the production of the finely crushed, washed and refined salt is achieved by modifying the pipeline of the centrifuge mother liquor from the brine storage tank to the salt slurry stirring tank, mixing the salt slurry discharged from the countercurrent washer, forming a closed loop of the centrifuge mother liquor in the "salt slurry stirring tank-thickener-centrifuge-salt slurry stirring tank", gradually separating the fine salt particles in the centrifuge mother liquor by using the interception of the salt particle filter cake formed in the centrifuge, recycling the fine salt particles into the wet salt discharged from the centrifuge and into the product, and realizing the separation and recycling of the fine salt particles in the centrifuge mother liquor brine.

[0194] The separation and recycling system for the fine salt particles in the washing brine in the production of the finely crushed, washed and refined salt in the method for reducing salt mud in the production of the finely crushed, washed and refined salt comprises:

[0195] The brine treatment module is used for separating and treating three streams of brine from different sources flowing into the brine storage tank and to be sent to the clarifying tank.

[0196] The salt particle diameter determination module is used for measuring the salt particle distribution rate in the brine, and determining the minimum nominal diameter of the salt particles to be separated and recycled according to the salt particle distribution rate.

[0197] The fine salt particle separation module is used for designing and manufacturing a salt particle separator to separate the fine salt particle slurry, and combining the separated fine salt particle slurry into the normal salt slurry of the corresponding process.

[0198] The fine salt particle recycling module is used for recycling the fine salt particles, and sending the brine with the separated fine salt particles to the clarifying tank for precipitation treatment.

[0199] As shown in Figure 3 the brine treatment module, the overflow brine of the spiral salt washer is separated and treated by the natural settling separator; the overflow brine of the salt slurry stirring tank is separated and treated by the centrifugal settling separator; and the centrifuge mother liquor brine is separated and treated by the "internal system circulation".

[0200] As shown in Table 1, the salt particle distribution rate in the brine is measured by the test in the salt particle diameter determination module.

[0201] Table 1 Salt particle distribution rate in the brine

[0202]

[0203] The salt particles below 0.044 mm in the overflow brine of the spiral salt washer and the salt slurry stirring tank account for only 17% and 16% of the total amount of salt particles respectively, so it can be determined that the salt particles with a particle size of 0.05 mm are the minimum salt particles to be separated and recycled.

[0204] As Figure 4 shown in the fine salt grain separation module, the spiral salt washing machine 3 overflow brine salt grain separation and recovery system provided by the embodiment of the application includes: control valve 1, flow meter 2, spiral salt washing machine 3, natural sedimentation separator 4 and stirring salt washing machine 5. The raw salt from the previous crushing process enters the spiral salt washing machine 3, and the clear brine from the clarification tank enters the spiral salt washing machine 3 to wash the raw salt through the control valve 1 and the flow meter 2 to regulate the flow. The washed brine enters the sedimentation separator 4, and the fine salt slurry is separated out. The separated fine salt slurry is discharged into the stirring salt washing machine 5 and enters the normal salt slurry. The brine after separating the salt grains is sent to the clarification tank for sedimentation treatment.

[0205] As Figure 5 shown in the fine salt grain separation module, the spiral salt washing machine 3 overflow brine salt grain separation and recovery system provided by the embodiment of the application includes: control valve 1, flow meter 2, spiral salt washing machine 3, natural sedimentation separator 4 and stirring salt washing machine 5. The raw salt from the previous crushing process enters the spiral salt washing machine 3, and the clear brine from the clarification tank enters the spiral salt washing machine 3 to wash the raw salt through the control valve 1 and the flow meter 2 to regulate the flow. The washed brine enters the sedimentation separator 4, and the fine salt slurry is separated out. The separated fine salt slurry is discharged into the stirring salt washing machine 5 and enters the normal salt slurry. The brine after separating the salt grains is sent to the clarification tank for sedimentation treatment.

[0206] As Figure 6As shown, in the fine salt particle recovery module, the fine salt slurry distribution pipe provided by the embodiment of the application involves: a rotary drum 18, a filter screen 19, a salt slurry feeding pipe 20, a salt particle filter cake 21, a feeding hopper 23, a fine salt slurry distribution pipe 24, wet salt 25, filtrate brine 26, mother liquor brine 27. The fine salt slurry distribution pipe 23 is installed on the salt slurry feeding pipe 20 in parallel with the salt slurry feeding pipe 20 into the centrifuge rotary drum 18, the salt slurry feeding pipe 20 is inserted into the inside of the feeding hopper 23, and the salt slurry distribution pipe 23 is arranged at the innermost end of the edge outside the feeding hopper 23, and the pipe opening is just above the salt particle filter cake 21 just formed. In this way, the fine salt particles in the fine salt slurry will be filtered to the surface of the filter cake under the interception of the salt particle filter cake, and enter the product with the wet salt. The filtrate brine is discharged from the centrifuge rotary drum 18 together with the mother liquor brine.

[0207] In order to prove the creativity and technical value of the technical scheme of the application, this part is an application example of the technical scheme of the claim on a specific product or related technology.

[0208] A set of 100,000 t / a fine washing and refining salt production line, 300 days a year, 24 hours a day, product output is 14 t / h. Under normal production conditions, 1.15 t of raw salt is consumed per ton of product, the raw salt input is 16.1 t / h, and 1 m 3 .

[0209] The salt washing machine washes the brine circulation flow (overflow flow) of 16.1 m 3 / h, and the salt particle content is 22 kg / m 3 , and the salt particle size is less than 0.125 mm;

[0210] The salt slurry stirring tank overflow brine flow is 15 m 3 / h, and the salt particle content is 24 kg / m 3 , and the salt particle size is less than 0.125 mm;

[0211] The centrifuge mother liquor brine flow is 4 m 3 / h, and the salt particle content is 20 kg / m 3 , and the salt particle size is less than 0.25 mm.

[0212] Table 2 shows the salt particle distribution rate in the brine determined by the test

[0213]

[0214] The three brines shown in Table 2 are treated respectively, and the salt particles with a size of more than 0.05 mm contained therein are separated and recovered, so as to reduce the amount of salt mud precipitated in the clarifying tank.

[0215] The salt particles in the salt washing machine wash brine are separated and recovered as follows:

[0216] Firstly, a natural settling salt particle separator is designed.

[0217] The salt particle settling velocity is calculated according to the following formula:

[0218]

[0219] In the formula, U0 is the settling velocity of the salt particle, m / s;

[0220] d is the nominal diameter of the smallest salt particle to be separated, 0.05 mm;

[0221] ρ S is the density of the salt particle, 2165 kg / m 3 ;

[0222] ρ is the density of the brine, 1202 kg / m 3 ;

[0223] g is the acceleration of gravity, 9.8 m / s 2 ;

[0224] μ is the viscosity of the brine, 0.002179 kg / m s (Pa s);

[0225] The calculation result is: U0 = 0.0006015 m / s = 2.16 m / h

[0226] To separate the salt particles with a particle size of 0.05 mm or larger, the upward velocity of the brine in the natural settling tank should be less than 0.0006015 m / s (2.16 m / h).

[0227] The normal working flow rate of the brine in the spiral salt washing machine Q = 16.1 m 3 / h, so the design area of the overflow surface of the natural settling tank A = Q ÷ U0 = 16.1 ÷ 2.16 = 7.45 m 2 ;

[0228] The natural settling tank is manufactured with an overflow surface area greater than 7.45 m 2 . Because the flow rate of the brine entering the spiral salt washing machine is equal to the flow rate of the brine entering the natural settling tank, a flow meter is installed at the brine inlet pipe of the spiral salt washing machine, and the brine flow rate is controlled not to exceed 16.1 m 3 / h, the upward velocity of the brine is less than 0.000601 m / s (2.16 m / h), which can make the salt particles larger than 0.05 mm settle at the bottom of the tank and be separated from the brine. The overflow brine of the settling tank is directly sent to the clarifier.

[0229] In the method for reducing salt mud in the production of crushed, washed, and refined salt, the separation and recovery of fine salt particles from the overflow brine of the spiral salt washing machine is realized as follows:

[0230] The fine salt slurry separated by the natural settling tank is deposited at the bottom of the tank, and the flow rate of the underflow slurry is controlled at about 0.7m 3 / h, which is discharged into the agitated washing machine and into the production line slurry, and is treated and incorporated into the product. The supply of brine to the agitated washing machine is reduced by 0.7m 3 / h, so that the material handling capacity of the agitated washing machine remains relatively stable. The fine salt particles in the overflow brine from the screw washing machine are thus recovered.

[0231] The salt particles in the overflow brine from the salt slurry agitated tank are separated and recovered as follows:

[0232] Design of the centrifugal settling salt particle separator.

[0233] The flow rate of the overflow brine from the salt slurry agitated tank is w = 15m 3 / h, which is used as the flow rate of the cyclone;

[0234] The minimum particle size d c = 0.05mm, is required for separation;

[0235] It is determined that:

[0236] The density of the salt particles p S = 2165kg / m 3 ;

[0237] The density of the clear brine p = 1202kg / m 3 ;

[0238] The viscosity of the clear brine at room temperature u = 0.002179kg / m s;

[0239] The salt particle velocity (brine inlet flow rate) u t = 5m / s is set;

[0240] The number of rotations of the salt particles (brine) N = 5;

[0241] Substitute the above parameters into the following formula:

[0242]

[0243] The inlet width of the cyclone b = 0.009637m is calculated;

[0244] The inlet height of the cyclone a is calculated as twice the width b to obtain the cross-sectional area of the rectangular inlet of the cyclone;

[0245] S 矩形 = b x 2b

[0246] The equivalent area of the circular tube inlet pipe diameter d1 is calculated:

[0247]

[0248]

[0249] d1 = 0.01596 (m) ~ 0.016 m

[0250] Again press long cone type cyclone design, see Figure 8 cyclone design parameters schematic diagram.

[0251] Cyclone nominal diameter: D = 4d1 = 4 x 0.016 = 0.064 (m);

[0252] Overflow pipe diameter: d2 = 0.064 / 3 = 0.021 (m);

[0253] Underflow pipe diameter: d3 = 0.064 / 4 = 0.016 mm (underflow pipe outlet flange on the installation of valve to adjust the underflow cross-sectional area size or device different diameter of the Venturi short pipe, adjust the discharge, to obtain the most ideal separation effect)

[0254] Cone angle α = 10 °.

[0255] Cyclone processing capacity calculation:

[0256] Cyclone processing capacity Q is approximately equal to the cross-sectional area of the inlet pipe and the brine flow rate product.

[0257] Q = a x b x u t ;

[0258] Q = (2 x 0.0096) x 0.096 x 5 = 0.0009216 m 3 / s = 3.318 m 3 / h;

[0259] Salt slurry mixing tank overflow brine flow w = 15 m 3 / h;

[0260] Cyclone processing flow is less than the salt slurry mixing tank overflow brine flow, a single cyclone can not meet the work requirements, need cyclone number n = W ÷ Q = 15 ÷ 3.318 = 4.52

[0261] Need 5 cyclone parallel installation.

[0262] Second step, according to the empirical formula to calculate the pressure drop of the brine through the cyclone;

[0263]

[0264] In the formula:

[0265] -ΔP is the pressure drop of the cyclone, Pa

[0266] b is the width of the inlet pipe of the cyclone, 0.0096 m

[0267] a is the height of the inlet pipe of the cyclone, 0.0192 m

[0268] d2 is the diameter of the overflow pipe of the cyclone, 0.021 m

[0269] p is the density of the clear brine, 1202 kg / m 3 ;

[0270] u t is the inlet velocity of the brine, 5 m / s.

[0271] Substitute b = 0.0096 m, a = 0.0192 m, d2 = 0.021 m, p = 1202 kg / m 3 , u t = 5 m / s into the above formula to calculate:

[0272] - ΔP = 100477 Pa = 0.10 MPa

[0273] 0.10 MPa is equivalent to the pressure of 10 m of water column;

[0274] Therefore, the brine pump head needs to be increased by 10 m on the basis of the original brine pump head, which is used as the selection parameter of the brine pump.

[0275] If the original brine pump head is 20 m and the flow rate is 20 m 3 , a pump with a head of 30 m and a flow rate of 20 m 3 can be selected, and a flowmeter and a control valve are installed at the outlet of the brine pump. The centrifugal settling separator set consisting of 5 parallelly installed cyclones is used in combination, so that the salt particles in the overflow brine of the salt slurry mixing tank can be separated.

[0276] The salt particles in the mother liquor brine of the centrifuge are separated and recovered as follows: The centrifuge mother liquor brine discharge pipeline is modified from the brine storage tank to the salt slurry mixing tank, and is combined with the normal salt slurry from the countercurrent washer. The centrifuge mother liquor brine forms a closed loop of "salt slurry mixing tank - thickener - centrifuge - salt slurry mixing tank". The fine salt particles in the centrifuge mother liquor brine are gradually separated through repeated circulation by using the interception effect of the centrifuge salt particle filter cake, and are recovered into the wet salt filtered out of the centrifuge and into the product. At the same time, the brine flow rate supplied to the salt slurry mixing tank is correspondingly reduced, so that the overflow flow rate of the salt slurry mixing tank is controlled at about 15 m 3 / h, the relative stability of the overflow flow rate is maintained, and the balanced operation of the entire process system is maintained. Through the implementation of the above three measures, the salt particles contained in the brine from different sources are all treated by separation and recovery. The brine after the separation and recovery of the salt particles is then sent to the clarifier, and the amount of salt mud generated is correspondingly reduced.

[0277] The embodiment of the present application has achieved some positive effects in research and development or use, and has great advantages compared with the prior art, which will be described below in combination with data and graphs of the test process.

[0278] The method for reducing salt mud in the production of the pulverized washing refined salt provided by the embodiment of the present application separates and recovers all salt particles with a particle size of more than 0.05 mm in the brine after being used in a 100,000 t / a pulverized washing refined salt production line, and the salt particle content in the brine entering the clarifying tank is reduced from the original 22 kg / m 3 to 5 kg / m 3 The separated and recovered salt particles account for about 80% of the total salt particle content in the brine. The consumption of raw salt is reduced from the original 1.15 tons to 1.112 tons, and the production capacity of the existing 100,000 t / a pulverized washing refined salt production line is increased by 3.83%.

[0279] The clarifying tank needs to be cleaned once for salt mud every 25 days or so in the original continuous production, and the amount of salt mud excavated each time is about 370 tons. Now the period for cleaning salt mud is extended to 90 days.

[0280] The original circulating flow rate Q of the salt washing brine is 35 m 3 / h, and the salt particle content in the brine is about 22 kg / m 3 . The salt particles brought into the clarifying tank per hour are 770 kg / h, and the salt particles brought into the clarifying tank per day are 18.48 tons. With 300 days of effective production time per year, the salt particles brought into the clarifying tank to form salt mud are 5544 tons. After the implementation of the present application, 80% (about 4435 tons) of these salt particles are separated and recovered. With the raw salt entering the factory at a price of 260 yuan per ton, and the waste residue treatment cost being 40 yuan per ton (excavation cost 15 yuan / ton, transportation cost 25 yuan / ton), the production cost is equivalent to 300 yuan per ton of salt mud reduced, and the annual cost can be saved by about 1.33 million yuan. At the same time, 4435 tons of refined edible salt products are increased, and the added value (sales revenue) is 443.5 million yuan (calculated at a product factory price of 1000 yuan per ton). The national edible salt production is about 10 million tons, and the production of edible salt by the pulverized washing refined method is about 20%, i.e. 200 million tons. After the completion and popularization of the project, the national cost can be reduced by about 26.61 million yuan, the refined edible salt can be increased by 8.87 million tons, and the added value (sales revenue) can be increased by 88.7 million yuan (calculated at a product factory price of 1000 yuan per ton). Accordingly, the industrial waste salt mud is reduced by 8.87 million tons, the raw salt is saved by 8.87 million tons, the waste of resource exploitation is reduced, which is conducive to promoting the sustainable development of society and improving the competitiveness of salt making enterprises in China.

[0281] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, any modification, equivalent replacement and improvement within the technical range disclosed by the present application and in the spirit and principle of the present application should be covered within the protection scope of the present application.

Claims

1. A method for reducing salt mud in the production of refined salt through crushing and washing, characterized in that, include: The three streams of brine from different sources that flow into the brine storage tank and are destined for the clarification tank are separated and treated separately before entering the brine storage tank. The distribution rate of salt particles in the brine is measured, and the nominal diameter of the minimum salt particles to be separated and recovered is determined based on the distribution rate. A salt particle separator is designed and manufactured to separate fine salt particles into a slurry. Based on the characteristics of the separated fine salt particles and the process conditions, the slurry is combined with the normal slurry of the corresponding process to recover the fine salt particles. The brine from which the fine salt particles have been separated is then sent to a clarifier for sedimentation treatment to reduce the amount of salt mud formed in the clarifier. The method for reducing salt mud in the production of refined salt by crushing and washing also includes: Before entering the clarification tank, the brine containing salt particles that has settled into salt mud is treated separately using different methods to separate and recover the salt particles. The brine from the spiral salt washing machine is separated from the salt particles by natural sedimentation and then added to the new salt slurry for recovery. The brine from the salt slurry mixing tank is separated from the fine salt particles by centrifugal sedimentation and then sprayed onto the salt particle filter cake formed by the centrifuge by a distributor for dehydration and recovery. The mother liquor brine from the centrifuge is added to the new salt slurry in the salt slurry mixing tank and then separated and recovered again in the centrifuge through closed-loop circulation.

2. The method for reducing salt mud in the production of refined salt by crushing and washing as described in claim 1, characterized in that, The method for reducing salt mud in the production of refined salt by crushing and washing includes the following steps: Step 1: Calculate the overflow cross-sectional area of ​​the salt particle separator required for the smallest salt particles to be separated from the overflow brine of the spiral salt washing machine, manufacture a natural settling salt particle separator, and use the natural settling salt particle separator to separate the salt particles from the brine. Step 2: The fine salt slurry separated by the natural sedimentation salt particle separator is discharged into the stirred salt washing machine and incorporated into the production line salt slurry; after subsequent processing, it is incorporated into the product, realizing the recovery of fine salt particles in the overflow brine of the spiral salt washing machine; Step 3: Determine the nominal diameter of the smallest salt particles to be separated from the overflow brine from the salt slurry mixing tank, and manufacture a centrifugal sedimentation salt particle separator; allow the overflow brine from the salt slurry mixing tank to pass through the centrifugal sedimentation salt particle separator kit to separate the salt particles from the brine; Step 4: The fine salt slurry separated by the centrifugal sedimentation salt particle separator is sprayed onto the salt particle filter cake formed by the centrifuge through the distributor. The fine salt particles are recycled back into the wet salt ejected from the centrifuge and incorporated into the product by the interception and filtration effect of the salt particle filter cake. Step 5: Utilize the filtering effect of the salt cake formed in the centrifuge to allow the mother liquor system to circulate infinitely, gradually separating the fine salt particles from the mother liquor and recovering them into the wet salt filtered out by the centrifuge, which is then incorporated into the product.

3. The method for reducing salt mud in the production of refined salt by crushing and washing as described in claim 2, characterized in that, In step one, based on the measurement results of the salt particle distribution rate in the overflow brine of the spiral salt washing machine, the nominal diameter of the smallest salt particle to be separated and recovered is determined; then, combined with the normal working brine overflow flow of the spiral salt washing machine, the overflow cross-sectional area of ​​the salt particle separator to be designed for separating the smallest salt particle is calculated, and a flow meter and control valve are installed on the brine inlet pipe of the spiral salt washing machine; so that the overflow brine of the spiral salt washing machine is separated into fine salt particles through the natural sedimentation salt particle separator, and the brine is then sent to the brine clarification tank.

4. The method for reducing salt mud in the production of refined salt by crushing and washing as described in claim 2, characterized in that, In step three, based on the measurement results of the salt particle distribution rate in the overflow brine of the salt slurry mixing tank, the minimum nominal diameter of the salt particles to be separated and recovered is determined; the nominal diameter and other parameters of the hydrocyclone separator are calculated, and a special centrifugal sedimentation salt particle separator is manufactured; the pressure drop of the hydrocyclone is calculated, the processing flow rate of the hydrocyclone separator is verified, the number of hydrocyclones is determined, and they are installed in parallel; a brine pump that meets the set flow velocity and flow rate of the hydrocyclone is selected, and a flow meter and control valve are installed at the outlet of the brine pump to form a complete centrifugal sedimentation salt particle separator kit with the hydrocyclone assembly; the brine flow rate is controlled within the set range, so that the overflow brine of the salt slurry mixing tank passes through the centrifugal sedimentation salt particle separator kit, and the salt particles are separated from the brine, and the brine is then sent to the brine clarification tank.

5. The method for reducing salt mud in the production of refined salt by crushing and washing as described in claim 2, characterized in that, In step five, the centrifuge mother liquor brine pipeline is modified from entering the brine storage tank to entering the salt slurry mixing tank, where it is combined with the salt slurry discharged from the countercurrent scrubber. This creates a closed-loop circulation of the centrifuge mother liquor brine: "salt slurry mixing tank - thickener - centrifuge - salt slurry mixing tank". Utilizing the filtering effect of the salt cake formed in the centrifuge, fine salt particles in the centrifuge mother liquor brine are gradually separated and recycled back into the wet salt ejected from the centrifuge, and then incorporated into the product. This achieves the separation and recycling of fine salt particles in the centrifuge mother liquor brine. Ultimately, the centrifuge mother liquor becomes part of the overflow brine from the salt slurry mixing tank, which is then incorporated into the overflow brine for further processing in the next step.

6. A method for reducing salt mud in the production of refined salt by crushing and washing as described in any one of claims 1 to 5, comprising a system for separating and recovering fine salt particles contained in the brine during the production of refined salt by crushing and washing, characterized in that, The system for separating and recovering fine salt particles contained in the brine during the production of crushed and washed refined salt includes: The brine treatment module is used to separate three streams of brine from different sources that flow into the brine storage tank and are to be sent to the clarification tank before entering the brine storage tank, and to process them separately. The module for determining the diameter of salt particles to be recovered is used to measure the distribution rate of salt particles in brine and determine the minimum nominal diameter of the salt particles to be separated and recovered based on the distribution rate. The fine salt particle separation module is used to design and manufacture salt particle separators to separate fine salt particle slurry and combine the separated fine salt particle slurry into the normal slurry of the corresponding process. The fine salt particle recovery module is used to recover fine salt particles, and the brine from which the fine salt particles are separated is then sent to a clarification tank for sedimentation treatment.

7. A computer device, characterized in that, The computer device includes a memory and a processor. The memory stores a computer program that, when executed by the processor, causes the processor to perform the steps of the method for reducing salt mud in the production of crushed and washed refined salt as described in any one of claims 1 to 5.

8. A computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform the steps of the method for reducing salt mud in the production of crushed and washed refined salt as described in any one of claims 1 to 5.

9. An information data processing terminal, characterized in that, The information data processing terminal is used to implement the system for recovering and utilizing fine salt particles in the production of crushed, washed, and refined salt as described in claim 6.

Images