Method for producing potassium chloride by using potassium mixed salt and carnallite based on mixed slurry method

Abstract

The invention discloses a method for producing potassium chloride by using potassium mixed salt and carnallite based on a mixed slurry method. The method is specifically realized through the steps of raw material grinding, raw material mixing, decomposition, suction filtration, flotation, suction filtration, weighing, test analysis and potassium chloride purification. According to the method, the raw ore (carnallite and potassium mixed salt) and the mother liquor are mixed and optimized to prepare potassium chloride, the optimal proportion of the potassium mixed salt ore to the carnallite is obtained, qualified potassium chloride with high yield is produced, and the problems of high cost and low quality of potassium chloride production are solved; the recovery rate of potassium in the potassium mixed salt mine is low, the resource utilization rate is not high, and the production pressure of carnallite is high. And the problems that the quality of the prepared product and the recovery rate of potassium in the potassium mixed salt mine are different due to the inaccuracy of the ratio and the technical points of the process in the actual production are also solved. Particularly, the composition of the carnallite slurry is not greatly changed; and interference on devices of a carnallite production line and influence on decomposition and batching work of an efficient decomposition machine are avoided.

Description

Technical Field

[0001] The invention relates to the technical field of inorganic salt production, and in particular to a method for producing potassium chloride based on a mixed slurry method by using potassium mixed salt and carnallite. Background Art

[0002] The brine in the mining area is rich in salt resources, and its chemical properties belong to the magnesium sulfate subtype. At present, the main raw material for producing potassium chloride is carnallite, but the resources of carnallite are limited.

[0003] Potassium mixed salt mines are mainly composed of epsom salt, sodium chloride and potassium chloride. Potassium sulfate is produced using the existing potassium mixed salt as raw material. The ratio of sulfate to potassium ion in normal potassium mixed salt is 2.5:1, but currently it is only 1:1. Due to the lack of sulfate, the production indicators of the potassium sulfate process cannot be met. Even if qualified potassium sulfate can be produced, it will lead to excessively high long-term production costs and low utilization of potassium resources.

[0004] At present, potassium chloride is also produced from potassium mixed salt mines, and through comparison, it is found that the cost of producing potassium sulfate from potassium mixed salt mines is much higher than the cost of producing potassium chloride. In actual production, potassium chloride is produced from potassium mixed salt. During the commissioning process in the workshop, it was found that the existing process and equipment for potassium mixed salt production will greatly increase the potassium beneficiation ratio, the tailing solid emission is high, and the potassium ion has a large loss rate during the production process. The recovery rate of potassium chloride produced from potassium mixed salt is not high, which is far from the expected effect.

[0005] The mixed slurry production technology is a process in which carnallite and potassium mixed salt are respectively transported to the crusher through the feeding unit in a certain proportion. The carnallite ore is transported to the high-efficiency decomposer after being crushed. The potassium mixed salt ore enters the ball mill for further fine grinding after being crushed. The finely ground slurry is swirl-flowed by the cyclone. The fine-grained slurry directly enters the high-efficiency decomposer, and the coarse-grained slurry returns to the ball mill for further grinding. At the entrance of the high-efficiency decomposer, an appropriate amount of fresh water and mother liquor are added in proportion (controlled according to laboratory data) and then transported to the slurry mixing tank through the underflow pump of the high-efficiency decomposer. Flotation reagents are added to the slurry mixing tank. After the flotation process, potassium chloride is separated from sodium chloride and magnesium sulfate. The slurry enters the flat filter for dehydration, enters the washing tank through the belt for washing, and then passes through the flat filter and centrifuge for dehydration. After dehydration, it is sent to the drying drum by the belt for drying, and finally packaged after drying.

[0006] However, due to the inaccuracy of the proportion and process technology in the actual production of the above method, the quality of the prepared product and the recovery rate of potassium in the potassium mixed salt ore are different. Specifically, (1) the amount of mixing must be accurately positioned, and the composition of the carnallite slurry cannot be significantly changed; (2) after mixing, it cannot interfere with the equipment of the carnallite production line and affect the decomposition and batching work of the high-efficiency decomposition machine; (3) after the potassium mixed salt slurry is mixed, the crystallization of the single salt and the double salt under the action of the high-efficiency decomposition machine forms a particle size difference according to the different crystallization speeds of the single salt and the double salt, thereby improving the quality of the product.

[0007] Therefore, this application urgently needs to find a potassium mixed salt mine and carnallite to produce qualified potassium chloride in a certain ratio through exploration and debugging, precise proportioning and strict control, in an attempt to solve the above-mentioned problems of high cost and low quality of potassium chloride production; low potassium recovery rate and low resource utilization rate in potassium mixed salt mines and high production pressure of carnallite. Summary of the invention

[0008] Based on the above technical problems, the object of the present invention is to provide a method for producing potassium chloride based on a mixed slurry method using potassium mixed salt and carnallite.

[0009] The method for producing potassium chloride based on a mixed slurry method using potassium mixed salt for protection and carnallite of the present invention specifically comprises the following steps:

[0010] Step 1, raw material grinding: grind the potash mixed salt ore and carnallite separately for later use;

[0011] Step 2, raw material mixing: the ground potassium mixed salt ore and carnallite are mixed in a ratio of 1:1-2, and then mixed with the mother liquor in a ratio of 1:0.55 for standby use;

[0012] Step 3, decomposition: stirring the mixed raw materials to undergo decomposition reaction at a decomposition temperature of 25°C for a reaction time of 30 to 50 minutes to obtain decomposed ore pulp;

[0013] Step 4, filtration: filtration of the decomposed slurry to obtain a decomposed solid phase, and analysis of the potassium ion grade in the decomposed solid phase; weighing the decomposed solid phase, and calculating the yield and the yield of potassium ions;

[0014] Step 5, flotation: Place the above decomposed solid phase in a flotation tank, add pulping mother liquor and flotation agent for stirring flotation, and the stirring intensity is 2400r·min -1 , stirring time is 1 min, scraping time is 4 min, flotation concentration is 24%, temperature is 24°C, time is 4 min; flotation concentrate and tailings are obtained;

[0015] Step 6, filtration, weighing and chemical analysis: the above flotation concentrate and tailings are filtered, weighed and analyzed respectively to determine the grades of potassium ions, sodium ions and sulfate ions in the flotation concentrate and tailings; the weight of the flotation product is weighed, and the yield and the yield of potassium ions are calculated;

[0016] Step 7, stirring and washing: Stir and wash the above flotation concentrate. The amount of washing water needs to be determined according to the amount and properties of the flotation concentrate. The stirring and washing speed is 30 to 60 r / min. -1 , stirring time is 15 to 30 minutes;

[0017] Step 8, solid-liquid separation: after the stirring and washing is completed, solid-liquid separation is performed by vacuum filtration or centrifugation, the vacuum degree of the vacuum filtration is -0.05-0.08MPa, so that the liquid passes through the filter cloth, and the wet potassium concentrate solid remains on the filter cloth. After separation, the wet potassium concentrate solid is sampled and analyzed to ensure that KCl is ≥78.3%;

[0018] Step 9, potassium chloride sodium removal and purification: the washed wet potassium concentrate solid is transferred to a dissolution tank and hot water at a temperature of 60 to 80°C is added. The heated water allows the wet potassium concentrate solid to be fully dissolved to form a saturated or nearly saturated potassium chloride solution; during the dissolution process, stirring is continued at a speed of 60 to 90 r / min. -1 , the dissolution time is 30 to 60 minutes;

[0019] Step 10, cooling and crystallization: the dissolved potassium chloride solution is cooled in a crystallizer at a moderate cooling rate to avoid too fast cooling resulting in too small crystal particles or the formation of inclusions; the temperature is reduced to 10-20°C to allow potassium chloride crystals to precipitate; during the cooling and crystallization process, the stirring speed is 30-40 r / min per minute -1 , to promote the growth and uniform distribution of potassium chloride crystals;

[0020] Step 11, centrifugal separation: centrifuge the cooled potassium chloride crystals and the mother liquor, the centrifugal speed is set according to the crystal size and properties, and is 1000-2000 r / min; after separation, NaCl in the potassium chloride product is ≤3.5%; KCl in the mother liquor is ≤11%, and NaCl is ≥15%; the mother liquor is returned to the previous step for recycling.

[0021] Furthermore, in step 2, the potash mixed salt ore and carnallite are mixed in a ratio of 1:1 to 1.5.

[0022] Furthermore, in step 3, the decomposition is performed using a high-efficiency decomposition machine.

[0023] Furthermore, in step 4, the potassium ion grade in the decomposed solid phase is 11-12%, the yield is 75-80%, and the yield of potassium ions is 120-135%.

[0024] Furthermore, in step 5, the amount of the slurry adjusting mother liquor potassium chloride slurry adjusting mother liquor is 3 to 3.5 times that of the decomposed solid phase.

[0025] Furthermore, in step 5, the flotation agents are 2# oil, hydrochloric acid and octadecylamine, and the dosage is 2# oil: hydrochloric acid + octadecylamine = 1:6-6.8.

[0026] Furthermore, in step 6, the potassium ion grade in the flotation concentrate is 22-25%, the sodium ion grade is 12-14%, and the sulfate ion grade is 3-7.5%; the potassium ion grade in the flotation tailings is 4-6%, the sodium ion grade is 14-22%, and the sulfate ion grade is 13-16%; the flotation product yield is 35-40%, and the potassium ion yield is 78-94%.

[0027] Furthermore, in steps 4 and 6, the filter cloth is used for washing water during suction filtration.

[0028] Compared with the existing technology, the present invention has the following beneficial effects:

[0029] The method of the present invention optimizes the preparation of potassium chloride by mixing raw ore (carnallite and potassium mixed salt) and mother liquor, obtains the best ratio of potassium mixed salt ore and carnallite, produces qualified potassium chloride with high yield, and solves the problems of high cost and low quality in the production of potassium chloride; low potassium recovery rate in potassium mixed salt ore, low resource utilization rate and high production pressure of carnallite. It also solves the problem of different quality of prepared products and different potassium recovery rates in potassium mixed salt ore due to inaccurate ratios and process technology points in actual production. Specifically, the composition of carnallite slurry is not significantly changed; the device of carnallite production line is not interfered with and the decomposition and batching work of the high-efficiency decomposer is not affected; the defect of different particle sizes formed due to different crystallization speeds of single salt and complex salt after the potassium mixed salt slurry is mixed and crystallized by the high-efficiency decomposer is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a process flow chart of the method of the present invention;

[0031] Figure 2 It is the relationship diagram of flotation product yield change;

[0032] Figure 3 This is a graph showing the relationship between the yield of potassium ions in flotation products. DETAILED DESCRIPTION

[0033] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Example 1

[0035] The method for producing potassium chloride based on a mixed slurry method using potassium mixed salt and carnallite is carried out under laboratory conditions in this embodiment, and the specific process is as follows:

[0036] 1. Raw material grinding

[0037] Grind the potash mixed salt ore and carnallite separately for later use;

[0038] 2. Raw material mixing

[0039] The ground potassium mixed salt ore and carnallite were mixed in a ratio of 1:1-2, and then mixed again with the mother liquor in a ratio of 1:0.55. The proportion results are shown in Table 1;

[0040] Table 1 Raw material mixing ratio

[0041] raw material Group 1 Group 2 Group 3 Group 4 Potassium mixed salt (g) 300 300 300 300 Carnallite(g) 300 350 400 450 Mother liquor (g) 330 357.5 385 412.5

[0042] 3. Decomposition and filtration

[0043] Carnallite, potassium mixed salt and mother liquor are placed in a beaker and stirred for decomposition reaction. The decomposition temperature is 25°C and the reaction time is 30-50 min to obtain a decomposed slurry. The decomposed slurry is decomposed and filtered to obtain a decomposed solid phase, and the potassium ion grade in the decomposed solid phase is analyzed. The decomposed solid phase is weighed, and the yield and the yield of potassium ions are calculated. The analysis data of the decomposed inlet and outlet materials are shown in Table 2 below.

[0044] Table 2 Decomposition of incoming and outgoing material data

[0045]

[0046]

[0047] It can be seen from Table 2 that when carnallite ore and potassium mixed salt ore are mixed and decomposed according to the above ratio (Table 1), the potassium ion grades in the decomposed solid phase are 11.00%, 11.22%, 11.45% and 11.98%, respectively, showing an overall upward trend.

[0048] Table 3 Decomposition solid phase weight, yield, K + Yield

[0049]

[0050] The weight, yield and potassium ion yield of the decomposed solid phase are shown in Table 3. After decomposition, it can be seen that the average yield of the decomposed solid phase is 78.10%, and the average yield of potassium ions is 129.23%. The yield and potassium ion yield fluctuate greatly.

[0051] 4. Flotation and filtration

[0052] The decomposed solid phase is placed in the flotation tank, and the pulping mother liquor and flotation agent (2# oil, hydrochloric acid, octadecylamine) are added for stirring flotation. The stirring intensity is 2400r·min -1 , stirring time is 1 min, scraping time is 4 min, flotation concentration is 24%, temperature is 24°C, and time is 4 min (see Table 4 for details).

[0053] Table 4 Flotation process control parameters

[0054]

[0055] The raw ore for flotation this time is the above-mentioned decomposed solid phase, the average potassium ion grade of the raw ore is 11.41%, and the slurry adjustment mother liquor is potassium chloride slurry adjustment mother liquor.

[0056] The concentrate and tailings obtained after flotation were filtered, weighed, and analyzed to obtain flotation concentrate and tailings, and the grades of potassium ions, sodium ions, and sulfate ions in the flotation concentrate and tailings were determined (see Table 5 for details).

[0057] Table 5 Flotation inlet and outlet test data

[0058]

[0059] From Table 5, we can see that K in flotation concentrate + The average grade is 23.73%, Na + The average grade is 12.96%, K + and Na + The grade tends to be stable. SO4 2- The average value is 4.51%, showing a clear downward trend. + The average grade is 4.91%, Na + The average grade is 17.14%, with large fluctuations. SO4 2- The average value is 14.75%, and the grade fluctuates greatly. From the test data, the fourth group of flotation concentrate has high potassium, the tailings has low potassium, and the flotation effect is better.

[0060] The flotation product was weighed and the yield and potassium ion yield were calculated (see Table 6 for details).

[0061] Table 6 Flotation product weight, yield, K + Yield

[0062]

[0063]

[0064] 5. Stirring and washing

[0065] The above flotation concentrate is placed in a washing device for stirring and washing, and then washing water is added to the washing device. The amount of washing water needs to be determined according to the amount and properties of the flotation concentrate to ensure that the concentrate can be fully soaked. During the water addition process, the stirring device is turned on to fully mix the concentrate with water. The stirring and washing speed is 30 to 60 r·min -1 The stirring time is 15 to 30 minutes to avoid the flotation concentrate particles from being broken due to excessive stirring, and to allow the soluble impurities in the concentrate, such as part of the sodium chloride, to dissolve in the water.

[0066] 6. Solid-liquid separation

[0067] After stirring and washing, solid-liquid separation is carried out by vacuum filtration or centrifugation. During the filtration process of the vacuum filter, the vacuum degree of vacuum filtration is -0.05~0.08MPa, so that the liquid passes through the filter cloth, while the wet potassium concentrate solid remains on the filter cloth. After separation, the wet potassium concentrate solid is sampled and analyzed to ensure that KCl is ≥78.3%.

[0068] 7. Purification of potassium chloride by removing sodium

[0069] The washed wet potassium concentrate solid is transferred to the dissolution tank, and hot water with a temperature of 60-80°C is added. A higher temperature can increase the solubility of potassium chloride without excessive energy consumption. The heated water can fully dissolve the wet potassium concentrate solid to form a saturated or nearly saturated potassium chloride solution. During the dissolution process, stirring is continued at a speed of 60-90 r·min -1 , the dissolution time is 30 to 60 minutes.

[0070] 8. Cooling crystallization

[0071] The dissolved potassium chloride solution is transported to the crystallizer through a pipeline for cooling. The cooling speed is moderate to avoid too fast cooling resulting in too small crystal particles or the formation of inclusions. The temperature is reduced to 10-20°C to allow potassium chloride crystals to precipitate. During the cooling and crystallization process, the stirring speed is 30-40 r / min per minute. -1 , to promote the growth and uniform distribution of potassium chloride crystals.

[0072] 9. Centrifugal separation

[0073] The potassium chloride crystals and mother liquor after cooling and crystallization are separated by centrifugation. The centrifugal speed of the centrifuge is set according to the size and properties of the crystals, and is 1000-2000 r / min. The potassium chloride product after separation is analyzed, wherein NaCl is ≤3.5%; KCl in the mother liquor is ≤11%, and NaCl is ≥15%; the mother liquor is returned to the previous step for recycling.

[0074] Comparative Example 1

[0075] The comparative example uses potassium mixed salt to produce potassium chloride, which is a preliminary exploration scheme based on the above-mentioned scheme of this application. The reason for this is that the production task is arduous, and the existing carnallite ore is limited, and potassium mixed salt is needed to supplement the output. Through workshop experiments, the process of producing potassium chloride with potassium mixed salt has been basically characterized, and there is no problem in producing high-grade products. However, due to the constraints of some rigid equipment conditions, the output has not been increased. The purpose of this experiment is to continue to increase the development and tap the potential of workshop equipment, further determine the stability of the process and equipment, and maximize the production capacity.

[0076] 1. Key points of test control

[0077] Monitor the ball mill's processing capacity for raw ore; the supply flow rate of mother liquor; the solid-liquid ratio of the slurry; the stability of the liquid level in the slurry feed tank; the diversion capacity of the cyclone's cyclone pressure and slurry particle size; the flotation effect and product quality.

[0078] 2. Test equipment

[0079] Workshop ball mill; cyclone; flotation C line and other equipment.

[0080] 3. Test raw materials

[0081] Potassium mixed salt ore; Potassium mixed salt circulating mother liquor; Flotation reagents are octadecylamine and 2# oil.

[0082] 4. Analysis methods

[0083] K + The sodium tetraphenylborate-quaternary ammonium salt volumetric method was used; Mg 2+ Using EDTA volumetric method; Cl - Using silver volume method; SO4 2- The analysis was performed by barium chloride volumetric method; Na + Use the subtraction method.

[0084] 5. Workshop production process

[0085] The ore intake is controlled at 160-180t / h, and two ball mills, Line A and Line B, are used for grinding. The total mother liquor volume is controlled at 200m 3 / h, and then sampling and screening and solid-liquid ratio determination are carried out at the cyclone outlet. The specific data (see Table 7 for details)

[0086] Table 7 Slurry particle size ratio and solid-liquid ratio

[0087]

[0088] The data showed that the proportion of solid phase exceeded the original setting of 40%, resulting in the slurry being too thick. The cyclone diversion effect was poor, resulting in a high tail solid discharge content. The data of the flotation workshop under this state are as follows (see Table 8 for details).

[0089] Table 8 Composition of samples in each link

[0090]

[0091] Later, considering that the insufficient supply of mother liquor inhibited the increase of ball mill ore loading, the ball mill of line B was shut down after discussion, and all the mother liquor was supplied to the ball mill of line A for slurry preparation. After adjustment, the ore loading on line A was adjusted to 170t / h, and the mother liquor was adjusted to 220m 3 / h, and then sampling and screening are carried out at the cyclone outlet to test the data (see Table 9 for details).

[0092] Table 9 Slurry particle size and solid-liquid ratio after adjustment

[0093]

[0094] After the adjustment, the proportion of -40 mesh slurry swirled out of the cyclone is greatly increased and can meet the flotation requirements for slurry particle size. The data of each link of flotation in the workshop (see Table 10 for details).

[0095] Table 10 Slurry particle size and solid-liquid ratio after adjustment

[0096]

[0097] 6. Experimental summary

[0098] Through this experiment, the processing capacity of a single ball mill has been increased from the original 65t / h to the current 170t / h, reaching the set processing capacity of the ball mill, thus meeting the material supply of the flotation workshop.

[0099] The ratio of raw ore to mother liquor was adjusted from the original 1:1 to 1:1.3, so that the slurry can fully meet the flotation requirements after being diverted by the hydrocyclone. However, due to the defects of the long mother liquor pipeline, which is easy to be blocked by salt, the small diameter, and the insufficient flow of the mother liquor pump, the mother liquor supply is insufficient and cannot meet the production. Therefore, the mixed ore production of carnallite and potassium mixed salt in this application was adopted, and its optimal production process parameters were found.

[0100] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for producing potassium chloride based on a mixed slurry method using potassium mixed salt and carnallite, characterized in that: The specific steps include: Step 1, raw material grinding: grind the potash mixed salt ore and carnallite separately for later use; Step 2, raw material mixing: the ground potassium mixed salt ore and carnallite are mixed in a ratio of 1:1-2, and then mixed with the mother liquor in a ratio of 1:0.55 for standby use; Step 3, decomposition: stirring the mixed raw materials to undergo decomposition reaction at a decomposition temperature of 25°C for a reaction time of 30 to 50 minutes to obtain decomposed ore pulp; Step 4, filtration: filtration of the decomposed slurry to obtain a decomposed solid phase, and analysis of the potassium ion grade in the decomposed solid phase; weighing the decomposed solid phase, and calculating the yield and the yield of potassium ions; Step 5, flotation: Place the above decomposed solid phase in a flotation tank, add pulping mother liquor and flotation agent for stirring flotation, and the stirring intensity is 2400r·min -1 , stirring time is 1 min, scraping time is 4 min, flotation concentration is 24%, temperature is 24°C, time is 4 min; flotation concentrate and tailings are obtained; Step 6, filtration, weighing and chemical analysis: the above flotation concentrate and tailings are filtered, weighed and analyzed respectively to determine the grades of potassium ions, sodium ions and sulfate ions in the flotation concentrate and tailings; the weight of the flotation product is weighed, and the yield and the yield of potassium ions are calculated; Step 7, stirring and washing: Stir and wash the above flotation concentrate. The amount of washing water needs to be determined according to the amount and properties of the flotation concentrate. The stirring and washing speed is 30 to 60 r / min. -1 , stirring time is 15 to 30 minutes; Step 8, solid-liquid separation: after the stirring and washing is completed, solid-liquid separation is performed by vacuum filtration or centrifugation, the vacuum degree of the vacuum filtration is -0.05-0.08MPa, so that the liquid passes through the filter cloth, and the wet potassium concentrate solid remains on the filter cloth. After separation, the wet potassium concentrate solid is sampled and analyzed to ensure that KCl is ≥78.3%; Step 9, potassium chloride sodium removal and purification: the washed wet potassium concentrate solid is transferred to a dissolution tank and hot water at a temperature of 60 to 80°C is added. The heated water allows the wet potassium concentrate solid to be fully dissolved to form a saturated or nearly saturated potassium chloride solution; during the dissolution process, stirring is continued at a speed of 60 to 90 r / min. -1 , the dissolution time is 30 to 60 minutes; Step 10, cooling and crystallization: the dissolved potassium chloride solution is cooled in a crystallizer at a moderate cooling rate to avoid too fast cooling resulting in too small crystal particles or the formation of inclusions; the temperature is reduced to 10-20°C to allow potassium chloride crystals to precipitate; during the cooling and crystallization process, the stirring speed is 30-40 r / min per minute -1 , to promote the growth and uniform distribution of potassium chloride crystals; Step 11, centrifugal separation: centrifuge the cooled potassium chloride crystals and the mother liquor, the centrifugal speed is set according to the crystal size and properties, and is 1000-2000 r / min; after separation, NaCl in the potassium chloride product is ≤3.5%; KCl in the mother liquor is ≤11%, and NaCl is ≥15%; the mother liquor is returned to the previous step for recycling.

2. The method for producing potassium chloride based on a mixed slurry method using potassium mixed salt and carnallite according to claim 1, characterized in that: In step 2, the potash mixed salt ore and carnallite are mixed in a ratio of 1:1 to 1.

5.

3. The method for producing potassium chloride based on a mixed slurry method using potassium mixed salt and carnallite according to claim 1, characterized in that: In step 3, the decomposition is performed using a high-efficiency decomposition machine.

4. The method for producing potassium chloride based on a mixed slurry method using potassium mixed salt and carnallite according to claim 1, characterized in that: In step 4, the potassium ion grade in the decomposed solid phase is 11-12%, the yield is 75-80%, and the yield of potassium ions is 120-135%.

5. The method for producing potassium chloride based on a mixed slurry method using potassium mixed salt and carnallite according to claim 1, characterized in that: In step 5, the amount of the slurry adjusting mother liquor potassium chloride slurry adjusting mother liquor is 3 to 3.5 times the amount of the decomposed solid phase.

6. The method for producing potassium chloride based on a mixed slurry method using potassium mixed salt and carnallite according to claim 1, characterized in that: In step 5, the flotation agents are 2# oil, hydrochloric acid and octadecylamine, and the dosage is 2# oil: hydrochloric acid + octadecylamine = 1:6-6.

8.

7. The method for producing potassium chloride based on a mixed slurry method using potassium mixed salt and carnallite according to claim 1, characterized in that: In step 6, the potassium ion grade in the flotation concentrate is 22-25%, the sodium ion grade is 12-14%, and the sulfate ion grade is 3-7.5%; the potassium ion grade in the flotation tailings is 4-6%, the sodium ion grade is 14-22%, and the sulfate ion grade is 13-16%; the flotation product yield is 35-40%, and the potassium ion yield is 78-94%.

8. The method for producing potassium chloride based on a mixed slurry method using potassium mixed salt and carnallite according to claim 1, characterized in that: In steps 4 and 6, the filter cloth is used for washing water during suction filtration.

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