Potassium chloride production method

Abstract

The invention provides a potassium chloride production method. The potassium chloride production method comprises the following steps: performing primary screening on raw ore to obtain a first oversize product and a first undersize product, wherein the raw ore comprises carnallite particles; performing secondary screening on the first undersize product to obtain a second oversize product and a second undersize product, and introducing the second undersize product into the crystallizer; and adding the second oversize product into decomposition liquid for decomposition to form slurry to be treated, and introducing the slurry to be treated into the crystallizer. According to the potassium chloride production method provided by the technical scheme of the invention, the problem that the decomposition and crystallization effects of carnallite in a crystallizer are poor when potassium chloride is prepared by using the existing potassium chloride preparation method can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of potassium chloride production, and more particularly, to a method for producing potassium chloride. Background Art

[0002] Salt lake brine is rich in minerals such as sodium, potassium, lithium, and magnesium. Carnallite obtained by sun-drying salt lake brine is the main raw material for producing potassium chloride, magnesium chloride, and lithium carbonate. By decomposing and crystallizing carnallite ore, magnesium chloride enters the liquid phase. Then, in the medium of high-magnesium mother liquor, octadecylamine hydrochloride is used as a collector, and No. 2 oil is used as a foaming agent to perform flotation on the decomposed slurry. After the flotation concentrate is filtered, a small amount of fresh water is used to wash away sodium chloride, and finally a potassium chloride product can be obtained. In the decomposition stage of carnallite, the main equipment used includes a pair-roll crusher for crushing carnallite and a crystallizer for decomposing carnallite. The original carnallite ore includes heavier impurities such as stones, which generally settle to the bottom of the crystallizer by gravity during the decomposition process of carnallite ore and enter the crystallizer bottom flow pipeline together with the underflow slurry. The original carnallite ore also includes a mud layer ore encountered during mining. Because it contains a large amount of black mud and has not been mined for a long time, its mineral quality is extremely hard and often exists in the form of large blocks, making it extremely difficult to break.

[0003] Currently, when producing potassium chloride, usually carnallite is first crushed by a crusher, and then the crushed particles are added to a crystallizer for decomposition. However, the particles after crushing by the crusher are too large and do not meet the requirements of the preset particle size range, resulting in poor decomposition and crystallization effects of carnallite in the crystallizer. Summary of the Invention

[0004] The main object of the present invention is to provide a method for producing potassium chloride, which can solve the problem of poor decomposition and crystallization effects of carnallite in the crystallizer when using the existing potassium chloride preparation method to prepare potassium chloride.

[0005] To achieve the above object, the present invention provides a method for producing potassium chloride, including: performing primary screening on the raw ore to obtain a first oversize material and a first undersize material, the raw ore including carnallite particles; performing secondary screening on the first undersize material to obtain a second oversize material and a second undersize material, and introducing the second undersize material into the crystallizer; adding the second oversize material to a decomposition liquid for decomposition to form a slurry to be treated and introducing the slurry to be treated into the crystallizer.

[0006] Further, the step of adding the second oversize material to the decomposition liquid for decomposition includes: during the process of adding the second oversize material to the decomposition liquid for decomposition, performing impurity removal on the second oversize material in the slurry to be treated to obtain a target slurry, and then introducing the target slurry into the crystallizer.

[0007] Further, the step of removing impurities from the second oversize material in the slurry to be treated includes: cleaning the impurities settled at the bottom of the slurry to be treated and / or the impurities floating on the slurry to be treated, so as to obtain the target slurry.

[0008] Further, the step of adding the second oversize material into the decomposition liquid for decomposition to form the slurry to be treated includes: using a stirring device to stir the slurry to be treated, and controlling the stirring frequency of the stirring device, so that the carnallite particles larger than the first preset particle size in the slurry to be treated settle to the bottom of the slurry to be treated for decomposition.

[0009] Further, the step of adding the second oversize material into the decomposition liquid for decomposition to form the slurry to be treated includes: when the concentration of the slurry to be treated is within the first preset range, adding decomposition liquid into the slurry to be treated according to the first preset condition, where the first preset condition is: for every increase of the first preset value in the concentration of the slurry to be treated, add the first preset amount K1 of decomposition liquid, for every decrease of the first preset value in the concentration of the slurry to be treated, add the second preset amount K2 of decomposition liquid, and the first preset amount K1, the second preset amount K2, the first basic addition amount A1 and the first variable B1 satisfy: K1 = A1 + B1, K2 = A1 - B1; when the concentration of the slurry to be treated is outside the first preset range, adjust the water-mineral ratio according to the mass of the second oversize material.

[0010] Further, the step of adding the second oversize material into the decomposition liquid for decomposition to form the slurry to be treated includes: using a stirring device to stir the slurry to be treated, and when the current during the operation of the stirring device is greater than or equal to the second preset value, adding decomposition liquid into the slurry to be treated according to the second preset condition, where the second preset condition is: for every increase of the third preset value in the current during the operation of the stirring device, add the third preset amount K3 of decomposition liquid, for every decrease of the third preset value in the current during the operation of the stirring device, add the fourth preset amount K4 of decomposition liquid, and the third preset amount K3, the fourth preset amount K4, the second basic addition amount A2 and the second variable B2 satisfy: K3 = A2 + B2, K4 = A2 - B2; when the current during the operation of the stirring device is less than the second preset value, adjust the water-mineral ratio according to the mass of the second oversize material.

[0011] Further, the step of adding the second oversize material into the decomposition liquid for decomposition to form the slurry to be treated includes: using a stirring device to stir the slurry to be treated, and when the concentration of the slurry to be treated is within the first preset range, adjusting the frequency of the stirring device according to the third preset condition, where the third preset condition is: for every increase of the fourth preset value in the concentration of the slurry to be treated, the stirring device stirs the slurry to be treated at the first preset frequency, and for every decrease of the fourth preset value in the concentration of the slurry to be treated, the stirring device stirs the slurry to be treated at the second preset frequency. The first preset frequency f1, the second preset frequency f2, the base frequency A3, and the third variable B3 satisfy: f1 = A3 - B3, f2 = A3 + B3; when the concentration of the slurry to be treated is outside the first preset range, the stirring device stirs the slurry to be treated at the base frequency A3, and adjusts the water-mineral ratio according to the mass of the second oversize material.

[0012] Further, the density of the decomposition liquid ranges from 1.1 kg / L to 1.3 kg / L, and the density of the slurry to be treated ranges from 1.2 kg / L to 1.3 kg / L.

[0013] Further, after the step of performing primary screening on the raw ore to obtain the first oversize material and the first undersize material, it includes: crushing the first oversize material so that the particle size of the first oversize material reaches the second preset particle size, where the second preset particle size is smaller than the screen hole diameter of the screening device for performing primary screening, or the second preset particle size is smaller than the screen hole diameter of the screening device for performing secondary screening.

[0014] Further, the screen hole diameter of the screening device for primary screening ranges from 200 mm ≤ R1 ≤ 350 mm, and the screen hole diameter of the screening device for secondary screening ranges from 10 mm ≤ R2 ≤ 30 mm.

[0015] Applying the technical solution of the present invention, performing primary screening on the raw ore to screen out the larger carnallite particles can avoid the direct entry of large carnallite particles into the crystallizer, reduce the load on the crystallizer, and at the same time avoid uneven stirring and low decomposition efficiency caused by overly large carnallite particles. Then, performing secondary screening on the first undersize material to directly introduce the smaller carnallite particles (the second undersize material) into the crystallizer for decomposition. For the relatively larger carnallite particles (the second oversize material), adding them to the decomposition liquid to perform primary decomposition of the second oversize material in the decomposition liquid, so that the particle size of the second oversize material becomes smaller, enabling the large carnallite particles that were originally difficult to be completely decomposed in the crystallizer to be decomposed into smaller particles before entering the crystallizer. Finally, introducing the slurry to be treated into the crystallizer for secondary decomposition, thereby improving the decomposition and crystallization effect of the carnallite particles in the crystallizer. Description of the Drawings

[0016] The accompanying drawings forming a part of this invention are used to provide a further understanding of the invention. The schematic embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention. In the drawings:

[0017] Figure 1 A flowchart of the potassium chloride production method of the present invention is shown. Detailed implementation manners

[0018] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0019] With the continuous exploitation and consumption of mineral resources, the carnallite ore sources for the device are gradually inclined to marginal ores and impurity ores. These raw ores have disadvantages such as many impurities, low potassium content, and large salt lumps. During production, the operating efficiency of the crushing equipment and the crystallizer equipment is poor, the failure rate is high, and it has a greater impact on the subsequent production process. In the process of potassium fertilizer production in the prior art, there are the following problems: 1) Carnallite is extremely hygroscopic in the air. When the crusher processes carnallite with high humidity, sticking rollers and bin blockages often occur, resulting in a sudden increase in the operating load of the crushing equipment and overload, often causing faults such as bearing seizure or electrical burnout. In addition, due to its core components not being resistant to high temperatures, long-term operation leads to increased wear. Coupled with improper maintenance, frequent failures will also be caused after the lubrication system fails. Moreover, the impurities entering the crusher with carnallite also include some hard substances such as stones and iron blocks, which will increase the crushing difficulty, accelerate equipment wear, shorten the equipment service life, and increase the equipment maintenance cost. For example, iron blocks are likely to cause damage to key components such as crushers. 2) The crushing equipment fails to meet the process requirements. The failure of the crushing equipment to meet the process requirements when crushing carnallite is mainly reflected in the following aspects: In terms of product particle size, the particles after crushing are still too large and do not meet the requirements of the predetermined particle size range, affecting the normal development of the subsequent crystallizer decomposition. Table 1 shows the data of the particle size comparison of carnallite before and after crushing during the monitoring of the equipment operating efficiency. It can be seen from the table that the screening data of carnallite before and after the roll crusher are extremely close.

[0020] Table 1 Statistical table of the particle size proportion of carnallite before and after crushing

[0021] Screening Specification Before Crushing After Crushing +1180um 25.13％ 24.63％ -1180μm + 850um 8.60％ 8.06％ -850um~+710um 4.89％ 5.13％ -710um~+600um 5.90％ 6.01％ -600um~+500um 6.41％ 6.30％ -500um~+425um 22.26％ 21.99％ -425um~+300um 12.31％ 13.05％ -300um~+212um 4.05％ 4.11％ -212um~+100um 7.93％ 8.36％ -100um 2.53％ 2.35％

[0022] Under normal circumstances, the proportion of carnallite with a particle size of more than 1180 μm is 25.13%. After crushing, the proportion of particles with a particle size of more than 1180 μm is 24.63%. The proportions of the remaining particle size layers are also not significantly different, and the crushed particle size is still relatively large. In terms of production capacity, the hourly ore feeding demand at the current production stage is about 300 t / h to 350 t / h, and the maximum throughput of the crusher is about 320 t / h. In case of wet ore, the maximum throughput is only about 280 t / h, which cannot meet the material supply demand of the subsequent production process. In terms of purity: Due to incomplete crushing, impurities cannot be fully separated from carnallite and are mixed into the crushed material, which not only affects the subsequent processes but also the subsequent utilization value. 3) Due to incomplete decomposition of carnallite, the load on the crystallizer equipment is heavy. The crystallizer is stirred by an open turbine agitator. The open turbine agitator is a radial flow agitator. The radial flow agitator transmits the power of the agitator to the fluid to form a radial flow state, usually forming relatively large eddies. The stirring effect is more intense compared to the axial flow agitator. However, this kind of stirring cannot push the fluid upward along the stirring shaft direction like the axial flow agitator, that is, the provided axial thrust is limited. When the particle size of the raw ore is too large and its own gravity exceeds the sum of the buoyancy and the upward thrust of the stirring, the particles fail to be fully mixed with water or the sizing mother liquor and directly settle to the bottom of the crystallizer. When large particles continuously settle and accumulate, the operating load of the crystallizer stirring also gradually increases, forming a vicious cycle that cannot be eliminated. Entering the underflow pipeline will also cause an increase in the operating load of the underflow pump, and in severe cases, it will block the underflow pipeline, resulting in the interruption of the feeding of the subsequent system. 4) Due to incomplete decomposition of carnallite, the decomposition index is poor and the system yield is low. Table 2 shows the comparison of process indexes in two states of complete and incomplete decomposition of carnallite. Since the content of magnesium chloride in the un-decomposed carnallite particles in this part is relatively high, it is the main reason for the low decomposition index. This part of carnallite can only be discharged from the system in the form of tail salt in the subsequent processes and cannot be recycled, which is also the main reason for the low system yield.

[0023] Table 2 Comparison of Decomposition Index and System Yield

[0024]

[0025] As can be seen from the above, when producing potassium chloride with the existing technology, carnallite needs to be crushed by a crusher, and then the crushed particles are added to the crystallizer for decomposition. However, the particles after crushing by the crusher are too large and do not meet the preset particle size range requirements, which will cause the above problems and also lead to poor decomposition and crystallization effects of carnallite in the crystallizer.

[0026] To solve the above problems, as Figure 1As shown in the figure, the present invention provides a method for producing potassium chloride. The method for producing potassium chloride includes: performing a primary screening on the raw ore to obtain a first oversize product and a first undersize product, wherein the raw ore includes carnallite particles; performing a secondary screening on the first undersize product to obtain a second oversize product and a second undersize product, and introducing the second undersize product into a crystallizer; adding the second oversize product into a decomposition liquid for decomposition to form a slurry to be processed and introducing the slurry into the crystallizer.

[0027] In this embodiment, by performing a primary screening on the raw ore to screen out the larger carnallite particles, it is possible to prevent large carnallite particles from directly entering the crystallizer, reduce the load on the crystallizer, and at the same time avoid uneven stirring and low decomposition efficiency caused by overly large carnallite particles. Then, perform a secondary screening on the first undersize product, directly introduce the smaller carnallite particles (the second undersize product) into the crystallizer for decomposition, and for the still relatively larger carnallite particles (the second oversize product), add them to the decomposition liquid to perform a primary decomposition of the second oversize product in the decomposition liquid, so that the particle size of the second oversize product becomes smaller, enabling the large carnallite particles that were originally difficult to completely decompose in the crystallizer to be decomposed into smaller particles before entering the crystallizer. Finally, introduce the slurry to be processed into the crystallizer for secondary decomposition, thereby improving the decomposition and crystallization effect of carnallite particles in the crystallizer without the need for a crushing operation.

[0028] The impurities contained in the carnallite raw ore mainly include three parts. First, heavier impurities such as stones generally settle to the bottom of the crystallizer due to gravity during the decomposition process of the carnallite raw ore, and enter the crystallizer bottom flow pipeline together with the underflow slurry, resulting in blockage of the bottom flow pipeline and affecting the feeding of subsequent processes. Second, the mud layer ore encountered during the mining of the raw ore contains a large amount of black mud. Since it has not been mined for a long time, its mineral quality is extremely hard and often exists in large block forms, making it extremely difficult to break. When it enters the crystallizer, it will seriously affect the decomposition efficiency of carnallite. Third, in addition to the above impurities, the raw ore also contains a large amount of lighter impurities such as grass roots, woven bag fragments, and domestic waste. After this part of the impurities enters the production system, they float on the liquid surface of each tank and enter various operating equipment and pipelines with the circulation of the slurry, resulting in a high failure rate of the equipment and affecting the product quality. In the prior art, the impurity removal device provided is only a magnetic separator assembled on a belt conveyor, which can only remove some magnetic domestic waste and solid waste such as scrap iron and cannot effectively remove all impurities.

[0029] To solve the above problems, in one embodiment of the present invention, the step of adding the second oversize product into the decomposition liquid for decomposition includes: during the process of adding the second oversize product into the decomposition liquid for decomposition, performing an impurity removal operation on the second oversize product in the slurry to be processed to obtain a target slurry, and then introducing the target slurry into the crystallizer.

[0030] In this embodiment, in the process of adding the second screen material to the decomposition liquid for decomposition, the second screen material in the slurry to be treated is subjected to an impurity removal operation, which can effectively remove impurities contained in the carnallite particles. The impurity removal operation not only improves the purity of the raw materials, but also reduces the impact of impurities on the subsequent crystallization process, avoids equipment blockage and wear, and reduces maintenance costs. Through the above steps, the particle size and impurity content of the target slurry finally obtained are optimized when entering the crystallizer, which helps to form a more uniform and controllable crystallization environment in the crystallizer, thereby improving the crystallization quality and yield of potassium chloride.

[0031] The raw ore may also include impurities such as stones. As can be seen from the above, the present application includes two stages: screening and impurity removal and decomposition and impurity removal. In the screening and impurity removal process, large pieces of carnallite particles and stones that exist alone are removed by primary screening. Since the number of impurities removed in this part is small, they can be cleaned manually after being screened out. The remaining impurities are mainly impurities mixed in large particles of carnallite, which are gradually separated from mineral particles during the decomposition of large particles of carnallite. The impurity removal process is divided into two methods: sedimentation impurity removal and floating impurity removal according to the gravity of the separated impurities, and the impurities are removed by regular cleaning and discharge.

[0032] In one embodiment of the present invention, the step of removing impurities from the second oversize material in the slurry to be treated includes: cleaning impurities settled at the bottom of the slurry to be treated and / or impurities floating on the slurry to be treated to obtain the target slurry.

[0033] In this embodiment, by removing the settled and / or floating impurities, on the one hand, the purity of the slurry to be processed can be significantly improved, especially when the raw ore contains more insoluble impurities (such as stones, iron blocks) or light impurities (such as grass roots, woven bag fragments), the removal of these impurities can ensure that the slurry to be processed entering the crystallizer is mainly composed of decomposed carnallite particles, reducing the interference of impurities on subsequent processes. On the other hand, after removing the impurities, the composition of the slurry is more uniform, which is conducive to controlling key parameters in the decomposition process, such as the concentration, density and temperature of the slurry. It helps the decomposition reaction to proceed under more ideal conditions, improves the decomposition efficiency and the quality of the decomposition products, and thus provides favorable conditions for subsequent crystallization operations.

[0034] On the other hand, by removing impurities before the treated slurry enters the crystallizer, large particles of impurities and light floating objects can be avoided from causing blockage or wear inside the crystallizer, reducing the failure rate of equipment and the need for regular maintenance and cleaning, thereby effectively reducing production costs and improving production efficiency.

[0035] In one embodiment of the present invention, the step of adding the second oversize material to the decomposition liquid for decomposition to form a slurry to be treated includes: using a stirring device to stir the slurry to be treated and controlling the stirring frequency of the stirring device so that carnallite particles larger than a first preset particle size in the slurry to be treated settle to the bottom of the slurry to be treated for decomposition.

[0036] In this embodiment, by controlling the stirring frequency, the floating and sinking state of large particles of carnallite in the slurry to be treated can be effectively controlled, so that carnallite particles larger than the first preset particle size in the slurry to be treated settle to the bottom of the slurry to be treated and continue to decompose, thereby ensuring that the carnallite particles in the slurry to be treated can be decomposed into carnallite particles with smaller particle sizes. At the same time, by controlling the stirring frequency, unnecessary over-stirring is avoided, energy consumption is reduced, and energy conservation and emission reduction can be achieved.

[0037] In one embodiment of the present invention, the step of adding the second oversize material to the decomposition liquid for decomposition to form a slurry to be treated includes: when the concentration of the slurry to be treated is within a first preset range, adding decomposition liquid to the slurry to be treated according to a first preset condition, where the first preset condition is: for every increase of a first preset value in the concentration of the slurry to be treated, add a first preset amount K1 of decomposition liquid; for every decrease of a first preset value in the concentration of the slurry to be treated, add a second preset amount K2 of decomposition liquid, and the first preset amount K1, the second preset amount K2, the first basic addition amount A1, and the first variable B1 satisfy: K1 = A1 + B1, K2 = A1 - B1. When the concentration of the slurry to be treated is outside the first preset range, adjust the water-mineral ratio according to the mass of the second oversize material.

[0038] In this embodiment, when the concentration of the slurry to be treated is within the first preset range, and for every increase or decrease of a first preset value in the concentration of the slurry to be treated, different amounts of decomposition liquid are added respectively, which keeps the concentration of the slurry to be treated within the range of better decomposition conditions and improves the decomposition efficiency. By dynamically adjusting the addition amount of the decomposition liquid, excessive or insufficient liquid addition is avoided, and unnecessary energy consumption is reduced. When the concentration of the slurry to be treated is too high, increasing the addition of the decomposition liquid can reduce the energy consumption of stirring and heating; when the concentration of the slurry to be treated is too low, reducing the addition of the decomposition liquid can avoid material waste and excessive energy consumption, realizing energy conservation and consumption reduction in the process. By controlling the concentration of the slurry to be treated, it can be ensured that the decomposition reaction proceeds under suitable conditions, which is beneficial to the uniform decomposition of carnallite particles, not only improving the decomposition effect, but also enhancing the quality and purity of the final product.

[0039] The water-mineral ratio refers to the proportional relationship between the amount of decomposition liquid used and the amount of carnallite ore during the process of treating carnallite. The decomposition liquid can be water or mother liquor (a liquid phase containing substances such as potassium chloride, sodium chloride, and magnesium chloride). Specifically, in the technological process of carnallite decomposition and crystallization, water or mother liquor is used as the decomposition medium to dissolve carnallite.

[0040] When the concentration of the slurry to be treated is outside the first preset range, the operator needs to adjust the water-mineral ratio according to the mass of the second oversize material added. If the slurry concentration is too high, the operator needs to increase the amount of water or increase the amount of mother liquor or reduce the amount of ore to dilute the slurry and lower its concentration until the slurry concentration is within the first preset range. If the slurry concentration is too low, the operator should reduce the amount of water or reduce the amount of mother liquor or increase the amount of ore to increase the concentration of the slurry and also ensure that it is within the first preset range.

[0041] In one embodiment, the first preset value is 0.01×10 -3 kg / m 3 , the first variable B1 is 2m 3 .

[0042] In one embodiment, when the decomposition liquid is mother liquor, the value of the first basic addition amount A1 is 0.6W to 1.2W, and when the decomposition liquid is water, the value of the first basic addition amount A1 is 0.4W to 0.7W, where W is the mass of the second oversize material.

[0043] In one embodiment of the present invention, the step of adding the second oversize material to the decomposition liquid for decomposition to form the slurry to be treated includes: adding the second oversize material to the decomposition liquid for decomposition to form the slurry to be treated. The step includes: using a stirring device to stir the slurry to be treated. When the current during the operation of the stirring device is greater than or equal to the second preset value, add decomposition liquid to the slurry to be treated according to the second preset condition. The second preset condition is: for every increase of the third preset value in the current during the operation of the stirring device, add the third preset amount K3 of decomposition liquid, and for every decrease of the third preset value in the current during the operation of the stirring device, add the fourth preset amount K4 of decomposition liquid. The third preset amount K3, the fourth preset amount K4, the second basic addition amount A2, and the second variable B2 satisfy: K3 = the second basic addition amount A2 + B2, K4 = A2 - B2; when the current during the operation of the stirring device is less than the second preset value, adjust the water-mineral ratio according to the mass of the second oversize material.

[0044] In this embodiment, when the current during the operation of the stirring device is greater than or equal to the second preset value, it indicates that the stirring device may bear an excessive load due to the presence of large particles of carnallite or high-concentration slurry. By adding additional decomposition liquid, the concentration of the slurry to be treated can be reduced, the load on the stirring device can be decreased, equipment overload can be avoided, and the service life of the equipment can be extended. When the current during the operation of the stirring device is less than the second preset value, it indicates that the added amount of the decomposition liquid exceeds the amount consumed by the decomposition of the carnallite particles. At this time, there is no need to continue adding the decomposition liquid. By dynamically adjusting the added amount of the decomposition liquid, it is possible to ensure that the slurry to be treated has appropriate fluidity during the decomposition process, enabling the carnallite particles to be fully dispersed in the decomposition liquid, increasing the contact area, and thus improving the decomposition efficiency. As can be seen from the above, through the interlock control of the current during the operation of the stirring device and the added amount of the decomposition liquid, this application not only helps to maintain the stable operation of the stirring device, avoid equipment failures or production interruptions caused by current fluctuations, but also can reduce the frequency of manual adjustment and improve the automation level.

[0045] When the current during the operation of the stirring device is less than the second preset value, the operator needs to adjust the water-mineral ratio according to the mass of the second oversize material added. If the slurry concentration is too high, the operator needs to increase the amount of water or the amount of mother liquor or reduce the amount of ore to dilute the slurry and lower its concentration until the slurry concentration is within the first preset range. If the slurry concentration is too low, the operator should reduce the amount of water or the amount of mother liquor or increase the amount of ore to increase the concentration of the slurry and also ensure that it is within the first preset range.

[0046] In one embodiment, when the decomposition liquid is mother liquor, the value of the second basic addition amount A2 is 0.6W to 1.2W, and when the decomposition liquid is water, the value of the second basic addition amount A2 is 0.4W to 0.7W, where W is the mass of the second oversize material.

[0047] In one embodiment, the second preset value is 100A, the third preset value is 1A, and the second variable B2 is 5m 3 。

[0048] In one embodiment of the present invention, the step of adding the second oversize material into the decomposition liquid for decomposition to form the slurry to be treated includes: using a stirring device to stir the slurry to be treated, and when the concentration of the slurry to be treated is within the first preset range, adjusting the frequency of the stirring device according to the third preset condition, where the third preset condition is: when the concentration of the slurry to be treated increases by the fourth preset value, the stirring device stirs the slurry to be treated at the first preset frequency f1, and when the concentration of the slurry to be treated decreases by the fourth preset value, the stirring device stirs the slurry to be treated at the second preset frequency f2, and the first preset frequency f1, the second preset frequency f2, the base frequency A3, and the third variable B3 satisfy: f1 = A3 - B3, f2 = A3 + B3; when the concentration of the slurry to be treated is outside the first preset range, the stirring device stirs the slurry to be treated at the base frequency A3, and adjusts the water-mineral ratio according to the mass of the second oversize material.

[0049] In this embodiment, when the concentration of the slurry to be treated is within the first preset range and the concentration of the slurry to be treated increases by the fourth preset value each time, reducing the stirring frequency of the stirring device can reduce the over-stirring of the carnallite particles that have been sufficiently decomposed, avoiding waste of energy. When the concentration of the slurry to be treated is within the first preset range and the concentration of the slurry to be treated decreases by the fourth preset value each time, increasing the stirring frequency can ensure sufficient contact between the decomposition liquid and the carnallite particles, promoting the decomposition reaction. The adjustment of the frequency of the stirring device directly affects the internal circulation of the slurry to be treated and the mixing effect of the materials. Within the first preset range, by adjusting the stirring frequency of the stirring device, the decomposition process of large-grained carnallite can be more effectively controlled, avoiding affecting the decomposition efficiency due to insufficient or excessive stirring.

[0050] When the concentration of the slurry to be treated exceeds the first preset range, stirring is carried out at the base frequency to ensure the stability and safety of the decomposition process. Dynamically adjusting the stirring frequency of the stirring device can avoid over-stirring when the concentration of the slurry to be treated is low, reducing unnecessary energy consumption and achieving the purpose of energy conservation and consumption reduction. Through the interlocking control of the concentration of the slurry to be treated and the stirring frequency of the stirring device, it helps to maintain the stable operation of the system and avoid process interruption caused by abnormal fluctuations in concentration or stirring state. This ensures the continuity and high efficiency of the decomposition process, which is crucial for improving the stability of the entire production system and the product quality. As can be seen from the above, in this application, by setting parameter interlocks, that is, setting interlocking control between the concentration of the slurry to be treated and the stirring frequency of the stirring device, and monitoring various decomposition parameters, the decomposition effect is made better by adjusting the stirring frequency.

[0051] When the concentration of the slurry to be processed is outside the first preset range, the stirring device stirs the slurry to be processed at the base frequency A3. At the same time, the operator needs to adjust the water-mineral ratio according to the mass of the second oversize material added. If the slurry concentration is too high, the operator should increase the amount of water or the amount of mother liquor or reduce the amount of ore to dilute the slurry and lower its concentration until the slurry concentration is within the first preset range. If the slurry concentration is too low, the operator should reduce the amount of water or the amount of mother liquor or increase the amount of ore to increase the concentration of the slurry and also ensure that it is within the first preset range.

[0052] In one embodiment, the first preset range is 1.35×10 -3 kg / m 3 ~1.7×10 -3 kg / m 3 。

[0053] In one embodiment, the fourth preset value is 0.05×10 -3 kg / m 3 , and the third variable B3 is 1HZ.

[0054] In one embodiment, the value of the base frequency A3 is 20hz to 50hz.

[0055] In one embodiment of the present invention, the density range of the decomposition liquid is 1.1 kg / L to 1.3 kg / L, and the density range of the slurry to be processed is 1.2 kg / L to 1.3 kg / L.

[0056] In this embodiment, the density range of the decomposition liquid is 1.1 kg / L to 1.3 kg / L, which can ensure that the decomposition liquid has sufficient buoyancy to disperse the carnallite particles evenly in the decomposition tank and improve the decomposition efficiency. At the same time, this density range also helps to promote the collision and dissolution between particles and further optimize the decomposition conditions. The density range of the slurry to be processed is 1.2 kg / L to 1.3 kg / L, which can ensure that when the stirring device provides axial thrust, it will neither be excessive nor insufficient. In addition, through the above settings, the specific gravity difference of different materials can be utilized to achieve effective impurity removal. Heavier impurities (such as stones, iron blocks, etc.) are likely to settle in the decomposition liquid with a lower density, while lighter impurities (such as grass roots, woven bag fragments) may float in the slurry to be processed with a higher density. Through gravity sedimentation and flotation separation, impurities can be efficiently removed to improve the product quality.

[0057] In one embodiment of the present invention, after the step of performing primary screening on the raw ore to obtain the first oversize material and the first undersize material, it includes: crushing the first oversize material so that the particle size of the first oversize material reaches a second preset particle size, where the second preset particle size is smaller than the screen hole aperture of the screening device for primary screening, or the second preset particle size is smaller than the screen hole aperture of the screening device for secondary screening.

[0058] In this embodiment, crushing the first oversize material to the second preset particle size reduces the particle size after crushing, which can avoid the blockage and wear of equipment (such as crystallizers and stirring devices) by large particles during the decomposition process. Moreover, the smaller particles flow more smoothly in the equipment, reducing the risk of equipment failure and extending the service life of the equipment. The crushed carnallite can be more fully decomposed during the decomposition process, reducing the emission of undecomposed carnallite, thereby improving the yield of the system. Additionally, when the second preset particle size is smaller than the screen hole aperture of the screening device for primary screening, secondary screening is still required, and only the second undersize material after secondary screening can be directly fed into the crystallizer. When the second preset particle size is smaller than the screen hole aperture of the screening device for secondary screening, then the crushed carnallite can be directly fed into the crystallizer, simplifying the secondary screening step and improving production efficiency.

[0059] From the sampling situation of the underflow pipeline of the crystallizer, the particle size of the undecomposed carnallite mainly concentrates in the range of 18 mm to 60 mm, and the proportion of particles with a particle size above 1180 μm in the screening of carnallite is 25%. It can be concluded that the proportion of particles with a particle size above 18 mm should be less than 25%.

[0060] In one embodiment of the present invention, the value range of the screen hole aperture of the screening device for primary screening is 200 mm ≤ R1 ≤ 350 mm, and the value range of the screen hole aperture of the screening device for secondary screening is 10 mm ≤ R2 ≤ 30 mm.

[0061] In this embodiment, the main purpose of primary screening is to remove large carnallite particles. Setting the value range of the screen hole aperture of primary screening as 200 mm ≤ R1 ≤ 350 mm can ensure that all large-sized carnallite particles are effectively screened out, preventing these large-sized carnallite particles from entering the subsequent decomposition process and reducing equipment wear and failure rate. The value range of the screen hole aperture of secondary screening is 10 mm ≤ R2 ≤ 30 mm, enabling the second undersize material to be more evenly mixed with the decomposition liquid, improving the efficiency and uniformity of the decomposition reaction.

[0062] Preferably, the screen hole aperture of the screening device for primary screening is 300 mm, and the screen hole aperture of the screening device for secondary screening is 20 mm. First, the carnallite particles larger than 300 mm are screened out to avoid blockage of the feeding port. The screen hole aperture of secondary screening is 20 mm, making the amount of the second oversize material at most only 25% of the amount of the incoming ore.

[0063] In one embodiment, the potassium chloride production method further includes using a magnetic separator to remove magnetic impurities from the raw ore. The magnetic separator is a prior art, and its specific structure will not be described here.

[0064] The carnallite decomposition process requires strict control of process parameters such as particle size, density, and flow rate. The prior art cannot make timely and effective adjustments to the material characteristics and parameter changes during the decomposition in the crystallizer. When the decomposition is completed and the indicators deviate, timely and effective adjustments cannot be made, which easily leads to unqualified control indicators in the subsequent process. To solve the above problems, in one embodiment, the potassium chloride production method further includes real-time monitoring of various parameters such as the concentration, density, temperature, and flow rate of the material, which can reflect the decomposition state of the material at any time, reducing the labor intensity of personnel while also reducing measurement errors caused by human operation mistakes or errors.

[0065] In one embodiment, the stirring device is designed with an axial flow impeller to increase the axial lifting force of the stirring on the decomposed material. After the material is fully mixed with water or mother liquor under the action of the stirring force, it flows from below the draft tube to the space between the outer wall of the draft tube and the wall of the dissolution tank, and then returns to the draft tube through the holes in the draft tube and enters the stirring area, forming an internal and external circulation centered on the draft tube. When the liquid level in the tank reaches the overflow level, the slurry starts to overflow into the crystallizer.

[0066] In summary, the potassium chloride production method of the present application has the following advantages:

[0067] 1) It can reduce the failure rate of equipment and improve the stability of the process. By combining screening, decomposition, and impurity removal, it effectively solves problems such as equipment or pipeline blockage, wear and damage, and overload. By concentrating the treatment of large particles of carnallite, the operation load of the equipment is reduced, and the influence of particles and impurities on the decomposition effect during the carnallite decomposition process is eliminated, thereby reducing the equipment failure rate and ensuring the normal operation of the equipment.

[0068] 2) The method of separately treating large particles of carnallite by screening and decomposition operations replaces the prior art crushing method, specifically solving a series of problems caused by low crushing efficiency (such as material interruption, incomplete decomposition, low yield, etc.). To a great extent, it ensures the continuous stability of the production process. While improving the decomposition efficiency, it effectively improves the decomposition index and the yield of the system, achieving the purpose of improving quality and increasing efficiency.

[0069] 3) Screen and dissolve to control the particle size. By optimizing the process flow of the decomposition process, using screening and dissolution instead of crushing, and specifically crushing large particles of carnallite separately, the problem that large particles cannot be crushed and the particle size of the feed into the crystallizer is too large is solved. After decomposition, the particle size distribution of all materials entering the crystallizer is relatively uniform, which can ensure the axial lifting force of the crystallizer on small particles, reduce material sedimentation and accumulation, and achieve the purpose of efficiently improving the decomposition efficiency, providing a favorable basis for the index control of subsequent processes. In addition, the carnallite in the crystallizer is effectively decomposed, and the solid-phase materials after decomposition are fully utilized, and the amount of external discharged tail salt that cannot be utilized by the system is significantly reduced, effectively improving the yield of the system and achieving the purpose of energy conservation and emission reduction.

[0070] 4) In this application, ultra-large particles and magnetic impurities are removed first, and then different-density impurities are accurately separated by gravity separation. This multi-dimensional impurity removal method is more comprehensive and thorough than traditional single impurity removal, and has strong applicability in an environment where the raw ore has many impurities and the impurity types are relatively complex, which can greatly improve the purity of the carnallite raw material and create good conditions for subsequent decomposition. This physical impurity removal method does not involve the design and installation of many impurity removal devices and has no use and maintenance costs.

[0071] 5) Dynamic monitoring and refined control. Real-time monitoring of various parameters such as the concentration, density, and temperature of the material can reflect the decomposition state of the material at any time, reducing the labor intensity of personnel and also reducing the measurement deviation caused by human operation errors or inaccuracies.

[0072] 6) Through various interlock controls, real-time control is carried out, solving the lag of manual control. On the basis of ensuring the good operation of the equipment, the refined control of the decomposition process of large particles of carnallite can be greatly improved, making the indexes after the decomposition of large particles of carnallite closer to the feed indexes of the crystallizer, effectively ensuring the stability and efficiency of the decomposition reaction.

[0073] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects: The raw ore is screened once to screen out large particles of carnallite, which can avoid large particles of carnallite directly entering the crystallizer, reduce the load of the crystallizer, and at the same time avoid uneven stirring and low decomposition efficiency caused by too large carnallite particles. Then, the first screen undersize is screened a second time, and the smaller particles of carnallite (the second screen undersize) are directly fed into the crystallizer for decomposition. For the relatively larger particles of carnallite (the second screen oversize), they are added to the decomposition liquid, and the second screen oversize is decomposed once in the decomposition liquid to further reduce the particle size, so that the large particles of carnallite that are difficult to be completely decomposed in the crystallizer can be decomposed into smaller particles before entering the crystallizer. Finally, the slurry to be treated is fed into the crystallizer for secondary decomposition, thereby improving the decomposition and crystallization effect of carnallite particles in the crystallizer.

[0074] Obviously, the embodiments described above are only some of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0075] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless otherwise clearly specified in the context, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0076] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for producing potassium chloride, characterized in that, include: Screening the raw ore once to obtain a first oversize and a first undersize, wherein the raw ore includes carnallite particles; Performing secondary screening on the first undersize to obtain a second oversize and a second undersize, and passing the second undersize into a crystallizer; The second oversize material is added into the decomposition liquid for decomposition to form a slurry to be treated and then introduced into the crystallizer.

2. The method for producing potassium chloride according to claim 1, wherein The step of adding the second oversize material into the decomposition liquid for decomposition includes: in the process of adding the second oversize material into the decomposition liquid for decomposition, performing impurity removal operation on the second oversize material in the slurry to be processed to obtain target slurry, and then passing the target slurry into the crystallizer.

3. The method for producing potassium chloride according to claim 2, wherein The step of removing impurities from the second oversize material in the slurry to be processed comprises: The impurities settled at the bottom of the slurry to be treated and / or the impurities floating on the slurry to be treated are cleaned to obtain the target slurry.

4. The method for producing potassium chloride according to any one of claims 1 to 3, characterized in that The step of adding the second screened material into the decomposition liquid for decomposition and forming a slurry to be treated includes: using a stirring device to stir the slurry to be treated, and controlling the stirring frequency of the stirring device so that the carnallite particles larger than the first preset particle size in the slurry to be treated settle to the bottom of the slurry to be treated for decomposition.

5. The method for producing potassium chloride according to any one of claims 1 to 3, characterized in that The step of adding the second oversize material into a decomposition liquid for decomposition to form a slurry to be treated comprises: When the concentration of the slurry to be treated is within the first preset range, the decomposition liquid is continuously added to the slurry to be treated according to the first preset condition, wherein the first preset condition is: every time the concentration of the slurry to be treated increases by the first preset value, a first preset amount K1 of the decomposition liquid is added, and every time the concentration of the slurry to be treated decreases by the first preset value, a second preset amount K2 of the decomposition liquid is added, and the first preset amount K1, the second preset amount K2, the first basic addition amount A1 and the first variable B1 satisfy: K1=A1+B1, K2=A1-B1; When the concentration of the slurry to be treated is outside the first preset range, the water-ore ratio is adjusted according to the mass of the second oversize material.

6. The method for producing potassium chloride according to any one of claims 1 to 3, characterized in that The step of adding the second oversize material into a decomposition liquid for decomposition to form a slurry to be treated comprises: A stirring device is used to stir the slurry to be treated. When the current of the stirring device during operation is greater than or equal to a second preset value, the decomposition liquid is continuously added to the slurry to be treated according to the second preset condition, wherein the second preset condition is: when the current of the stirring device during operation increases by a third preset value, a third preset amount K3 of the decomposition liquid is added, and when the current of the stirring device during operation decreases by the third preset value, a fourth preset amount K4 of the decomposition liquid is added, and the third preset amount K3, the fourth preset amount K4, the second basic addition amount A2 and the second variable B2 satisfy: K3=A2+B2, K4=A2-B2; When the current of the stirring device during operation is less than the second preset value, the water-ore ratio is adjusted according to the mass of the second screen material.

7. The method for producing potassium chloride according to any one of claims 1 to 3, characterized in that The step of adding the second oversize material into a decomposition liquid for decomposition to form a slurry to be treated comprises: A stirring device is used to stir the slurry to be treated. When the concentration of the slurry to be treated is within a first preset range, the frequency of the stirring device is adjusted according to a third preset condition, wherein the third preset condition is: when the concentration of the slurry to be treated increases by a fourth preset value, the stirring device stirs the slurry to be treated at a first preset frequency f1, and when the concentration of the slurry to be treated decreases by the fourth preset value, the stirring device stirs the slurry to be treated at a second preset frequency f2, and the first preset frequency f1, the second preset frequency f2, the base frequency A3 and the third variable B3 satisfy: f1=A3-B3, f2=A3+B3; When the concentration of the slurry to be processed is outside the first preset range, the stirring device stirs the slurry to be processed at the basic frequency A3, and adjusts the water-ore ratio according to the mass of the second oversize material.

8. The method for producing potassium chloride according to any one of claims 1 to 3, characterized in that The density of the decomposition liquid ranges from 1.1 kg / L to 1.3 kg / L, and the density of the slurry to be treated ranges from 1.2 kg / L to 1.3 kg / L.

9. The method for producing potassium chloride according to any one of claims 1 to 3, characterized in that After the step of screening the original ore once to obtain the first overscreen material and the first underscreen material, the step includes: crushing the first overscreen material so that the particle size of the first overscreen material reaches a second preset particle size, and the second preset particle size is smaller than the sieve hole diameter of the screening device for realizing the primary screening, or the second preset particle size is smaller than the sieve hole diameter of the screening device for realizing the secondary screening.

10. The method for producing potassium chloride according to any one of claims 1 to 3, characterized in that The aperture diameter of the sieve hole of the screening device for the primary screening is in the range of 200mm≤R1≤350mm, and the aperture diameter of the sieve hole of the screening device for the secondary screening is in the range of 10mm≤R2≤30mm.

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