Potassium salt flotation separation method based on inhibiting potassium-sodium adhesion and particle size regulation

Abstract

The application discloses a potassium salt flotation separation method based on inhibition of potassium-sodium adhesion and particle size control, and comprises the following steps: mixing carnallite, decomposition mother liquor and a surfactant to perform decomposition crystallization, so as to obtain a decomposition crystallization product; mixing the decomposition crystallization product with a pulp conditioning mother liquor, so as to obtain a flotation slurry; adding a collector and a foaming agent to the flotation slurry to perform flotation, so as to obtain a concentrate and a tailing; wherein, the surfactant and the collector are both octadecylamine hydrochloride solutions. By adding part of the octadecylamine hydrochloride solution as the surfactant in the carnallite decomposition crystallization stage, the particle size range of potassium chloride can be controlled, so that the particle size is distributed in the optimal flotation particle size range, and the phenomenon of potassium-sodium adhesion is reduced, thereby solving the technical problems that in the process of producing potassium chloride by using the carnallite cold decomposition crystallization-positive flotation method, potassium-sodium inclusions are serious, the particle size is difficult to control, the sodium grade of the potassium chloride concentrate obtained by flotation separation is high, and the potassium chloride concentrate yield and the potassium recovery rate are both low.

Description

Technical Field

[0001] This invention relates to the field of potassium salt flotation separation technology, and in particular to a potassium salt flotation separation method based on inhibiting potassium and sodium adhesion and particle size control. Background Technology

[0002] Salt lake brine deposits require a process involving solar crystallization to produce carnallite, followed by hydrolysis and flotation separation to produce potassium chloride. Existing production processes include: cold decomposition crystallization-direct flotation, reverse flotation-cold crystallization, hot dissolution-cold crystallization, and brine-mixing crystallization. Among these, cold decomposition crystallization-direct flotation is the most widely used and simplest. However, it is difficult to control the particle size of potassium chloride produced by this method within the optimal flotation range, and sodium chloride inclusions are severe, directly affecting the utilization efficiency of potassium resources and the market competitiveness of potash fertilizer products.

[0003] In the current carnallite cold decomposition crystallization-positive flotation process, the potassium chloride produced by carnallite decomposition crystallization is negatively charged, while the associated sodium chloride is positively charged. The two adhere together due to electrostatic attraction, resulting in severe potassium-sodium adhesion and poor control of the optimal flotation particle size range. Current technologies generally improve potassium chloride recovery and grade by optimizing downstream flotation processes or reagent formulations. However, the fresh potassium chloride generated from carnallite decomposition adheres to or embeds within the potassium chloride crystal particles due to electrostatic adsorption with the associated sodium chloride impurities. This adhesion or embedding is difficult to separate through downstream flotation processes, leading to sodium chloride being easily entrained during potassium chloride flotation, thus reducing the potassium chloride concentrate grade and worsening potassium-sodium separation efficiency.

[0004] Therefore, there is an urgent need to provide a new potassium salt flotation separation method that can inhibit potassium and sodium adhesion during the decomposition of carnallite and before potassium chloride flotation, and optimize the carnallite decomposition products to the optimal flotation particle size. This would solve the technical problems in the existing carnallite cold decomposition crystallization-positive flotation process for producing potassium chloride, which results in severe potassium and sodium inclusions, difficulty in controlling particle size, and consequently, high sodium content in the potassium chloride concentrate obtained from flotation separation, as well as low potassium chloride concentrate yield and potassium recovery rate. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical deficiencies and propose a potassium salt flotation separation method based on inhibiting potassium and sodium adhesion and particle size control. This method solves the technical problems in the existing process of producing potassium chloride by cold decomposition and crystallization of carnallite-positive flotation, which results in severe potassium and sodium inclusions and difficulty in controlling particle size, leading to high sodium grade in the potassium chloride concentrate obtained by flotation separation and low potassium chloride concentrate yield and potassium recovery rate.

[0006] This invention provides a potassium salt flotation separation method based on inhibiting potassium and sodium adhesion and particle size control, comprising the following steps: Provides carnallite, decomposition mother liquor and slurry preparation mother liquor; Carnallite, decomposition mother liquor and surfactant are mixed and decomposed and crystallized to obtain decomposition crystallization product; The decomposition and crystallization products are mixed with the mother liquor to obtain flotation slurry; Collectors and frothers are added to the flotation slurry for flotation to obtain concentrate and tailings; The surfactant and collector are both octadecylamine hydrochloride solutions.

[0007] Furthermore, the carnallite is carnallite produced by sun-drying in salt lakes; and / or, by mass percentage, the main chemical composition of carnallite includes: 5wt%-10wt% potassium ions, 1wt%-5wt% sodium ions, 5wt%-10wt% magnesium ions, 25wt%-35wt% chloride ions, and 4wt%-8wt% sulfate ions.

[0008] Furthermore, by mass percentage, the decomposition mother liquor comprises: 4wt%-8wt% potassium ions, 1wt%-5wt% sodium ions, 1wt%-5wt% magnesium ions, 10wt%-15wt% chloride ions, 2wt%-6wt% sulfate ions, with the remainder being water and unavoidable impurities; and / or, by mass percentage, the slurry preparation mother liquor comprises: 1wt%-4wt% potassium ions, 0.5wt%-2wt% sodium ions, 3wt%-10wt% magnesium ions, 15wt%-20wt% chloride ions, 2wt%-6wt% sulfate ions, with the remainder being water and unavoidable impurities.

[0009] Furthermore, during the decomposition and crystallization process, the mass ratio of carnallite to the mother liquor is (1-2):1; and / or, during the decomposition and crystallization process, the decomposition and crystallization temperature is 20-35℃, the decomposition and crystallization time is 20-65 min, and the stirring rate is 1000-1200 rpm.

[0010] Furthermore, during the mixing of the decomposition crystallization product with the slurry mother liquor, the mass ratio of carnallite to the slurry mother liquor is (1-2):1; and / or, during the mixing of the decomposition crystallization product with the slurry mother liquor, the temperature is 20-35℃, the stirring time is 1-3 min, and the stirring rate is 1000-1200 rpm.

[0011] Furthermore, the octadecylamine hydrochloride solution is obtained by mixing concentrated hydrochloric acid, octadecylamine, and water in a mass ratio of 1:2:99; and / or, based on the total amount of carnallite, the total amount of surfactant and collector is 60-150 g / t; and / or, the amount of surfactant accounts for 20%-100% of the total amount of surfactant and collector, and the amount of collector accounts for 0%-80% of the total amount of surfactant and collector.

[0012] Furthermore, the foaming agent is No. 2 oil; and / or, The amount of foaming agent used is 5-10 g / t, based on the total amount of solids in the decomposition crystallization product.

[0013] Furthermore, during inflation, the airflow velocity is 0.1-0.3 m / s. 3 / h, inflation time is 100-200s.

[0014] Furthermore, during the flotation process, the temperature is 25-30℃ and the stirring speed is 1500-2200rpm.

[0015] Further, a collector and a frother are added to the flotation slurry for flotation, including: stirring the flotation slurry at a temperature of 25-30℃ and a rotation speed of 1500-2200 rpm for 1-3 minutes; then adding the collector and stirring for 1-3 minutes; followed by adding the frother, stirring for 1-3 minutes, and then starting to flotation at a speed of 0.1-0.3 m. 3 Air is introduced at a flow rate of / h for 100-200s; then, after skimming, concentrate slurry and tailings slurry are obtained.

[0016] Compared with the prior art, the beneficial effects of the present invention include: This invention addresses the technical problem of severe potassium and sodium inclusions and difficulty in particle size control in the potassium chloride production process via cold decomposition and crystallization-positive flotation. This is achieved by adding a portion of octadecylamine hydrochloride solution as a surfactant during the carnallite decomposition and crystallization stage, thereby controlling the particle size range of potassium chloride and ensuring its distribution within the optimal flotation particle size range. It also reduces the adhesion of potassium and sodium, thus solving the problem of high sodium grade, low potassium chloride concentrate yield, and low potassium recovery rate in the process of producing potassium chloride by cold decomposition and crystallization-positive flotation. Attached Figure Description

[0017] Figure 1 This is a process flow diagram of one embodiment of the potassium salt flotation separation method based on inhibiting potassium and sodium adhesion and particle size control provided by the present invention. Figure 2 This is a particle size and volume distribution diagram of the decomposition and crystallization products obtained by adding different amounts of surfactants during the decomposition and crystallization stage of carnallite in Examples 1-5 and Comparative Example 1 of the present invention. Figure 3 This is a cumulative particle size distribution diagram of the decomposition and crystallization products obtained by adding different amounts of surfactants during the decomposition and crystallization stage of carnallite in Examples 1-5 and Comparative Example 1 of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0019] Please see Figure 1 This invention provides a potassium salt flotation separation method based on inhibiting potassium and sodium adhesion and particle size control, comprising the following steps: S1. Raw material preparation: Provide carnallite, decomposition mother liquor and slurry preparation mother liquor; S2. Decomposition and crystallization: Carnallite, mother liquor and surfactant are mixed and decomposed and crystallized to obtain the decomposition and crystallization product; S3. Slurry preparation: The decomposition and crystallization products are mixed with the slurry preparation mother liquor to obtain flotation slurry; S4. Flotation: Collectors and frothers are added to the flotation slurry to carry out flotation and obtain concentrate and tailings. The surfactant and collector are both octadecylamine hydrochloride solutions.

[0020] In this invention, carnallite, decomposition mother liquor, and surfactant are mixed for decomposition and crystallization. By adding a portion of octadecylamine hydrochloride solution as a surfactant in advance during the carnallite decomposition and crystallization stage, potassium and sodium adhesion is inhibited and the particle size of the potassium chloride crystallized product is optimized. Combined with the subsequent flotation stage, potassium chloride products with lower sodium grade and higher potassium chloride concentrate yield and potassium recovery rate can be obtained.

[0021] By using octadecylamine hydrochloride solution as a surfactant, the surface potential of potassium chloride can be changed from negative to positive, causing electrostatic repulsion between potassium chloride and sodium chloride. This reduces potassium-sodium adhesion and the particle size of the decomposition crystals, which is beneficial for subsequent flotation. Specifically, octadecylamine is added at the beginning of carnallite decomposition and before potassium chloride is formed. Due to its excellent selectivity and collection properties for potassium chloride, octadecylamine will preferentially adsorb onto the potassium chloride surface. On the one hand, as a cationic surfactant, octadecylamine can modify the negatively charged potassium chloride surface to a positively charged state, forming electrostatic repulsion with the positively charged sodium chloride, thereby inhibiting potassium-sodium adhesion. On the other hand, octadecylamine can selectively adsorb onto the crystal nucleus surface, changing the surface energy of the crystal and the growth rate of each crystal face, thereby inhibiting excessively rapid growth and preventing the formation of large particles. In addition, the steric hindrance effect of octadecylamine can increase the interaction between crystal particles, increasing the number of crystal nuclei, promoting uniform nucleation, reducing the formation of fine particles, and making the particle size distribution of potassium chloride particles more concentrated. Therefore, introducing octadecylamine during the decomposition of carnallite allows it to function as a collector, dispersant, and crystallizer, simultaneously achieving precise control over the dispersion of potassium and sodium particles and the crystal size of potassium chloride. Compared to the traditional "decomposition-flotation" process, this invention introduces octadecylamine during carnallite decomposition. Through its selective regulation of the surface charge of potassium chloride particles, it effectively inhibits the adhesion between potassium and sodium particles. Simultaneously, by utilizing octadecylamine's ability to regulate potassium salt crystal growth, precise control over the crystal size of potassium chloride is achieved, thereby synergistically improving flotation separation efficiency from multiple angles.

[0022] In this invention, a decomposition mother liquor and a slurry conditioning mother liquor are introduced. The decomposition mother liquor is used to accelerate the decomposition of carnallite and promote the crystallization of potassium chloride, so that more potassium chloride crystals precipitate. The slurry conditioning mother liquor is used to reduce the concentration of potassium chloride in the solution, so that its concentration is within the optimal flotation concentration range, which is beneficial to subsequent flotation.

[0023] In this invention, in step S1, the carnallite is carnallite produced by sun-drying in a salt lake. This invention utilizes an octadecylamine hydrochloride solution as a surfactant to enhance flotation separation through combined crystallization regulation. For complex salt lake systems, especially carnallite produced by sun-drying in salt lakes, this method effectively solves the problems of potassium-sodium adhesion and difficulty in particle size control during crystallization, overcoming the bottlenecks of high impurity content and low recovery rate in flotation concentrates.

[0024] In this invention, in step S1, the main chemical composition of carnallite by mass percentage includes: potassium ions 5wt%-10wt%, sodium ions 1wt%-5wt%, magnesium ions 5wt%-10wt%, chloride ions 25wt%-35wt%, and sulfate ions 4wt%-8wt%.

[0025] In this invention, in step S1, the decomposition mother liquor, by mass percentage, comprises: 4wt%-8wt% potassium ions, 1wt%-5wt% sodium ions, 1wt%-5wt% magnesium ions, 10wt%-15wt% chloride ions, 2wt%-6wt% sulfate ions, with the remainder being water and unavoidable impurities.

[0026] In this invention, in step S1, the slurry preparation mother liquor, by mass percentage, comprises: 1wt%-4wt% potassium ions, 0.5wt%-2wt% sodium ions, 3wt%-10wt% magnesium ions, 15wt%-20wt% chloride ions, 2wt%-6wt% sulfate ions, with the remainder being water and unavoidable impurities.

[0027] In this invention, in step S2, the mass ratio of carnallite to decomposition mother liquor is (1-2):1, including but not limited to 1:1, 1.2:1, 1.5:1, 1.8:1, 2:1, etc.

[0028] In this invention, during step S2, the decomposition and crystallization process is carried out at a temperature of 20-35°C, including but not limited to 20°C, 22°C, 25°C, 28°C, 30°C, 32°C, and 35°C. The decomposition and crystallization time is 20-65 min, including but not limited to 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, and 65 min. The stirring speed is 1000-1200 rpm, including but not limited to 1000 rpm, 1100 rpm, and 1200 rpm.

[0029] In this invention, during step S3, when the decomposed crystallization product is mixed with the slurry mother liquor, the mass ratio of carnallite to the slurry mother liquor is (1-2):1, including but not limited to 1:1, 1.2:1, 1.5:1, 1.8:1, 2:1, etc.

[0030] In this invention, during step S3, the temperature is 20-35℃, including but not limited to 20℃, 22℃, 25℃, 28℃, 30℃, 32℃, 35℃, etc., the stirring time is 1-3 min, including but not limited to 1 min, 2 min, 3 min, etc., and the stirring speed is 1000-1200 rpm, including but not limited to 1000 rpm, 1100 rpm, 1200 rpm, etc.

[0031] In this invention, in steps S2 and S4, the octadecylamine hydrochloride solution is obtained by mixing concentrated hydrochloric acid, octadecylamine, and water in a mass ratio of 1:2:99.

[0032] In this invention, in steps S2 and S4, the total amount of surfactant and collector used is 60-150 g / t based on the total amount of carnallite, including but not limited to 60 g / t, 70 g / t, 80 g / t, 90 g / t, 100 g / t, 110 g / t, 120 g / t, 130 g / t, 140 g / t, 150 g / t, etc.

[0033] In this invention, in steps S2 and S4, the amount of surfactant used accounts for 20%-100% of the total amount of surfactant and collector used, including but not limited to 20%, 40%, 60%, 80%, 100%, etc., and the amount of collector used accounts for 0%-80% of the total amount of surfactant and collector used, including but not limited to 0%, 20%, 40%, 60%, 80%, etc. In this invention, the total amount of surfactant and collector used (i.e., the total amount of octadecylamine hydrochloride solution) is fixed. In the decomposition and crystallization stage, a portion of octadecylamine hydrochloride solution is added as a surfactant, and in the flotation stage, the remaining octadecylamine hydrochloride solution is added as a collector. Better flotation effect can be obtained by simply adjusting the timing of feeding, without the need for additional grinding and screening processes, and without additional reagent consumption.

[0034] In this invention, in step S4, the foaming agent is No. 2 oil (pine oil).

[0035] In this invention, in step S4, the amount of foaming agent used is 5-10 g / t based on the total amount of solids in the decomposed crystallization product, including but not limited to 5 g / t, 6 g / t, 7 g / t, 8 g / t, 9 g / t, 10 g / t, etc.

[0036] In this invention, during step S4, the temperature during the flotation process is 25-30℃, including but not limited to 25℃, 26℃, 27℃, 28℃, 29℃, 30℃, etc., and the stirring speed is 1500-2200 rpm, including but not limited to 1500rpm, 1600rpm, 1700rpm, 1800rpm, 1900rpm, 2000rpm, 2100rpm, 2200rpm, etc.

[0037] In this invention, during step S4, the air flow rate is 0.1-0.3 m / s during the inflation process. 3 / h, including but not limited to 0.1m 3 / h, 0.15m 3 / h, 0.2m 3 / h, 0.25m 3 / h, 0.3m 3 / h, etc., the inflation time is 100-200s, including but not limited to 100s, 120s, 150s, 180s, 200s, etc.

[0038] In this invention, step S4, adding a collector and a frother to the flotation slurry for flotation, includes: stirring the flotation slurry for 1-3 minutes at a temperature of 25-30℃ and a rotation speed of 1500-2200 rpm; then adding the collector and stirring for 1-3 minutes; next, adding the frother, and after foaming for 1-3 minutes, starting at a speed of 0.1-0.3 m... 3 Air is introduced at a flow rate of / h for 100-200s; then, after skimming, concentrate slurry and tailings slurry are obtained.

[0039] To avoid redundancy, the main chemical compositions of the carnallite (from the Lop Nur salt lake), decomposition mother liquor (potassium washing liquid from the Lop Nur salt lake), and slurry conditioning mother liquor (liquid after filtration of potassium chloride concentrate from flotation separation from the Lop Nur salt lake) involved in the following embodiments and comparative examples of the present invention are shown in the table below: Table 1. Main chemical composition of carnallite produced by sun-drying in salt lakes.

[0040] Table 2. Main chemical composition of decomposition mother liquor and slurry preparation mother liquor

[0041] Example 1 (1) Decomposition and crystallization: Carnallite dried in salt lake and decomposition mother liquor were added to a double-jacketed crystallization reactor at a mass ratio of 6:5. Based on the total amount of carnallite dried in salt lake, 14 g / t of surfactant (octadecylamine hydrochloride solution, which is obtained by mixing concentrated hydrochloric acid, octadecylamine and water at a mass ratio of 1:2:99) was added to carry out decomposition and crystallization. The decomposition and crystallization temperature was controlled at 25℃. Mechanical stirring was used to stir at a speed of 1100 rpm for 60 min to obtain the decomposition and crystallization product. (2) Slurry preparation: Add the slurry preparation mother liquor to the decomposition crystallization product at a mass ratio of 1.5:1 for the raw ore (i.e., carnallite dried in the salt lake) to the slurry preparation mother liquor. Continue stirring for 2 minutes in a double-jacketed crystallization reactor at a temperature of 25℃ and a rotation speed of 1100rpm to obtain flotation slurry. (3) Flotation: The flotation slurry was added to the flotation cell and stirred for 2 minutes at a temperature of 25°C and a rotation speed of 1800 rpm. Then, based on the total amount of carnallite produced by the salt lake, 56 g / t of collector (octadecylamine hydrochloride solution, obtained by mixing concentrated hydrochloric acid, octadecylamine and water in a mass ratio of 1:2:99) was added and stirred for 2 minutes. Next, based on the total amount of solids in the decomposition crystallization product, 6 g / t of frother (No. 2 oil) was added and foamed for 2 minutes. Then, the flotation was started at 0.1 m 3 Air is introduced at a flow rate of / h for 150s; then, after skimming, potassium chloride concentrate slurry and tailings slurry are obtained; finally, the potassium chloride concentrate slurry and tailings slurry are filtered and dried (45℃, 20h) to obtain potassium chloride concentrate and tailings.

[0042] Example 2 Compared with Example 1, the only difference is that in step (1), during the decomposition and crystallization stage of carnallite, 28 g / t of surfactant (octadecylamine hydrochloride solution, which is obtained by mixing concentrated hydrochloric acid, octadecylamine and water in a mass ratio of 1:2:99) is added based on the total amount of carnallite produced by the salt lake; and in step (3), during the flotation stage, 42 g / t of collector (octadecylamine hydrochloride solution, which is obtained by mixing concentrated hydrochloric acid, octadecylamine and water in a mass ratio of 1:2:99) is added based on the total amount of carnallite produced by the salt lake.

[0043] Example 3 Compared with Example 1, the only difference is that in step (1), during the decomposition and crystallization stage of carnallite, 42 g / t of surfactant (octadecylamine hydrochloride solution, which is obtained by mixing concentrated hydrochloric acid, octadecylamine and water in a mass ratio of 1:2:99) is added based on the total amount of carnallite produced by the salt lake; and in step (3), during the flotation stage, 28 g / t of collector (octadecylamine hydrochloride solution, which is obtained by mixing concentrated hydrochloric acid, octadecylamine and water in a mass ratio of 1:2:99) is added based on the total amount of carnallite produced by the salt lake.

[0044] Example 4 Compared with Example 1, the only difference is that in step (1), during the decomposition and crystallization stage of carnallite, 56 g / t of surfactant (octadecylamine hydrochloride solution, which is obtained by mixing concentrated hydrochloric acid, octadecylamine and water in a mass ratio of 1:2:99) is added based on the total amount of carnallite produced by the salt lake; and in step (3), during the flotation stage, 14 g / t of collector (octadecylamine hydrochloride solution, which is obtained by mixing concentrated hydrochloric acid, octadecylamine and water in a mass ratio of 1:2:99) is added based on the total amount of carnallite produced by the salt lake.

[0045] Example 5 Compared with Example 1, the only difference is that in step (1), during the decomposition and crystallization stage of carnallite, 70 g / t of surfactant (octadecylamine hydrochloride solution, which is obtained by mixing concentrated hydrochloric acid, octadecylamine and water in a mass ratio of 1:2:99) is added based on the total amount of carnallite produced by the salt lake; and in step (3), during the flotation stage, 0 g / t of collector (octadecylamine hydrochloride solution, which is obtained by mixing concentrated hydrochloric acid, octadecylamine and water in a mass ratio of 1:2:99) is added based on the total amount of carnallite produced by the salt lake.

[0046] Comparative Example 1 Compared with Example 1, the only difference is that in step (1), during the decomposition and crystallization stage of carnallite, 0 g / t of surfactant (octadecylamine hydrochloride solution, which is obtained by mixing concentrated hydrochloric acid, octadecylamine and water in a mass ratio of 1:2:99) is added based on the total amount of carnallite produced by the salt lake; and in step (3), during the flotation stage, 70 g / t of collector (octadecylamine hydrochloride solution, which is obtained by mixing concentrated hydrochloric acid, octadecylamine and water in a mass ratio of 1:2:99) is added based on the total amount of carnallite produced by the salt lake.

[0047] Performance testing and results analysis The particle size distribution of the decomposition and crystallization products obtained by different surfactant addition amounts during the decomposition and crystallization stage of carnallite in the above-mentioned different embodiments and comparative examples was tested. The test results are shown in […]. Figure 2-3 The flotation effects of different surfactant addition amounts during the decomposition and crystallization stage of carnallite in different embodiments and comparative examples are summarized in Table 3. The particle size distribution test steps for the decomposition crystallization product are as follows: Take a small amount of the decomposition crystallization product, filter it, dry it at 45℃ for 20 hours until it is dry, loose and non-clumping, and measure its particle size distribution with a laser particle size analyzer.

[0048] Table 3. Flotation effect with different surfactant dosages

[0049] Please see Figure 2-3 ,pass Figure 2-3It can be seen that the particle size of the decomposition crystallization product obtained in Comparative Example 1 of this invention is between 10-320 μm, d 50 =97.374μm, with a relatively wide particle size distribution range, and the particle size of the decomposition crystallization products is relatively large; the particle size of the decomposition crystallization products obtained in Example 1 of this invention is between 10-330μm. Although the absolute particle size distribution boundary (10-330μm) of its decomposition crystallization products is slightly wider than that of Comparative Example 1, its volume median diameter (d) is larger. 50 The particle size (d = 75.875 μm) decreased significantly from 97.374 μm in Comparative Example 1 to 75.875 μm, indicating that the intervention of trace surfactants can effectively intervene in the crystallization kinetics of the system, inhibit the disordered excessive growth of most crystals, and cause a significant "leftward shift" (concentration towards finer particles) in the main particle size group of the product. Most target particles have been successfully guided to a more suitable particle size window for flotation, resulting in a significantly improved flotation effect compared to Comparative Example 1 (as shown in Table 3). The decomposition crystallization products obtained in Examples 2-5 of this invention are all in the range of 10-280 μm. 50 The corresponding particle sizes are 68.273 μm, 71.391 μm, 66.602 μm, and 61.189 μm, respectively. The overall particle size range is very suitable for flotation, and the overall particle size range is narrower than that of the decomposition crystallization products without surfactant, which can further improve the flotation effect (see Table 3). These results indicate that adding octadecylamine hydrochloride solution as a surfactant during the decomposition crystallization stage of carnallite can control the particle size of potassium chloride crystals, thereby enhancing the flotation effect of potassium chloride.

[0050] Please refer to Table 3. As can be seen from Table 3, compared with Comparative Example 1, the addition of different amounts of octadecylamine hydrochloride solution as a surfactant in Examples 1-5 of this invention during the carnallite decomposition and crystallization stage resulted in significantly better flotation effects than Comparative Example 1, which did not add a surfactant during the carnallite decomposition and crystallization stage. This is because adding octadecylamine hydrochloride solution as a surfactant during the carnallite decomposition and crystallization stage can synergistically regulate the particle size range of potassium chloride and reduce potassium-sodium adhesion, thereby reducing the Na+ content in the potassium chloride concentrate obtained from flotation. + The addition of octadecylamine hydrochloride solution as a surfactant during the decomposition and crystallization stage of carnallite can improve the grade of potassium chloride concentrate, increase the yield of potassium chloride concentrate and the recovery rate of potassium chloride in potassium chloride concentrate. At the same time, as can be seen from Table 3, the addition of octadecylamine hydrochloride solution as a surfactant during the decomposition and crystallization stage of carnallite can also help increase the solid content in the decomposition and crystallization products.

[0051] A comparison of the results from Examples 1-5 shows that the best effect was achieved when the surface activity addition during the carnallite decomposition and crystallization stage was 42 g / t (Example 3), resulting in a potassium chloride concentrate yield of 74.30% and a potassium chloride recovery rate of 95.77%. The Na content in the potassium chloride concentrate was also low. + The content is 9.36%. Under these conditions, K +The recovery rate was very close to the highest level (96.02%), and the Na content in the concentrate was low. + The lowest content is beneficial to subsequent washing processes, effectively reducing water demand and water consumption, thereby improving the economy and resource utilization efficiency of the entire process.

[0052] In summary, compared with the prior art, the beneficial effects of the present invention include: (1) Compared with the traditional process of producing potassium chloride by cold decomposition and crystallization of carnallite followed by positive flotation, this invention adds a portion of octadecylamine hydrochloride solution as a surfactant during the carnallite decomposition and crystallization stage, which can inhibit the adhesion of potassium and sodium, thereby enhancing flotation separation and reducing sodium content. + The effect of carrying, reducing energy consumption, and improving potassium utilization efficiency is achieved, thereby obtaining potassium chloride products with lower sodium grade, higher potassium chloride concentrate yield, and higher potassium recovery rate. (2) Compared with the traditional process of improving the grade and recovery rate of potassium chloride by controlling the particle size through grinding and screening, the present invention adds part of octadecylamine hydrochloride solution as a surfactant during the decomposition and crystallization stage of carnallite, which can control the particle size of potassium chloride crystals, making the potassium chloride grow more uniformly and finer, controlling the decomposition and crystallization products within a narrower particle size range, thereby strengthening flotation and avoiding the problem of partial loss of potassium chloride caused by screening, thus better improving the grade of potassium chloride (i.e., low sodium grade) and recovery rate, and simplifying the process flow. (3) Compared with the traditional process of producing potassium chloride by cold decomposition crystallization-positive flotation of carnallite, the present invention adds part of octadecylamine hydrochloride solution as a surfactant during the decomposition crystallization stage of carnallite, which can inhibit the adhesion of potassium and sodium and control the particle size, thereby strengthening the flotation separation. Under the premise of ensuring the reduction of sodium grade in potassium chloride concentrate and the improvement of potassium chloride concentrate yield and potassium recovery rate, it has the advantages of being more convenient and greener.

[0053] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A potassium salt flotation separation method based on inhibiting potassium-sodium adhesion and particle size control, characterized in that, Includes the following steps: Provides carnallite, decomposition mother liquor and slurry preparation mother liquor; The carnallite, the mother liquor, and the surfactant are mixed and decomposed and crystallized to obtain the decomposition and crystallization product. The decomposition and crystallization product is mixed with the slurry preparation mother liquor to obtain flotation slurry; Collectors and frothers are added to the flotation slurry for flotation to obtain concentrate and tailings; The surfactant and the collector are both octadecylamine hydrochloride solutions.

2. The potassium salt flotation separation method based on inhibiting potassium-sodium adhesion and particle size control according to claim 1, characterized in that, The carnallite is carnallite produced by sun-drying in a salt lake; and / or... The main chemical composition of the carnallite, by mass percentage, includes: 5wt%-10wt% potassium ions, 1wt%-5wt% sodium ions, 5wt%-10wt% magnesium ions, 25wt%-35wt% chloride ions, and 4wt%-8wt% sulfate ions.

3. The potassium salt flotation separation method based on inhibiting potassium-sodium adhesion and particle size control according to claim 1, characterized in that, By mass percentage, the decomposition mother liquor comprises: 4wt%-8wt% potassium ions, 1wt%-5wt% sodium ions, 1wt%-5wt% magnesium ions, 10wt%-15wt% chloride ions, 2wt%-6wt% sulfate ions, with the remainder being water and unavoidable impurities; and / or, By mass percentage, the slurry preparation mother liquor comprises: 1wt%-4wt% potassium ions, 0.5wt%-2wt% sodium ions, 3wt%-10wt% magnesium ions, 15wt%-20wt% chloride ions, 2wt%-6wt% sulfate ions, with the remainder being water and unavoidable impurities.

4. The potassium salt flotation separation method based on inhibiting potassium-sodium adhesion and particle size control according to claim 1, characterized in that, During the decomposition and crystallization process, the mass ratio of carnallite to the mother liquor is (1-2):1; and / or, During the decomposition and crystallization process, the decomposition and crystallization temperature is 20-35℃, the decomposition and crystallization time is 20-65 min, and the stirring rate is 1000-1200 rpm.

5. The potassium salt flotation separation method based on inhibiting potassium-sodium adhesion and particle size control according to claim 1, characterized in that, During the process of mixing the decomposed crystallization product with the slurry mother liquor, the mass ratio of carnallite to the slurry mother liquor is (1-2):1; and / or, During the process of mixing the decomposed crystallization product with the slurry mother liquor, the temperature is 20-35℃, the stirring time is 1-3 minutes, and the stirring speed is 1000-1200 rpm.

6. The potassium salt flotation separation method based on inhibiting potassium-sodium adhesion and particle size control according to claim 1, characterized in that, The octadecylamine hydrochloride solution is obtained by mixing concentrated hydrochloric acid, octadecylamine, and water in a mass ratio of 1:2:99; and / or, Based on the total amount of carnallite, the total amount of the surfactant and the collector is 60-150 g / t; and / or, The amount of the surfactant used accounts for 20%-100% of the total amount of the surfactant and the collector, and the amount of the collector accounts for 0%-80% of the total amount of the surfactant and the collector.

7. The potassium salt flotation separation method based on inhibiting potassium-sodium adhesion and particle size control according to claim 1, characterized in that, The foaming agent is No. 2 oil; and / or, The amount of foaming agent used is 5-10 g / t, based on the total amount of solids in the decomposition crystallization product.

8. The potassium salt flotation separation method based on inhibiting potassium-sodium adhesion and particle size control according to claim 1, characterized in that, During inflation, the airflow velocity is 0.1-0.3m. 3 / h, inflation time is 100-200s.

9. The potassium salt flotation separation method based on inhibiting potassium-sodium adhesion and particle size control according to claim 1, characterized in that, During the flotation process, the temperature is 25-30℃ and the stirring speed is 1500-2200rpm.

10. The potassium salt flotation separation method based on inhibiting potassium-sodium adhesion and particle size control according to claim 1, characterized in that, The process of adding a collector and a frother to the flotation slurry for flotation includes: stirring the flotation slurry for 1-3 minutes at a temperature of 25-30℃ and a rotation speed of 1500-2200 rpm; then adding the collector and stirring for 1-3 minutes; followed by adding the frother, stirring for 1-3 minutes, and then starting to stir at a speed of 0.1-0.3 m... 3 Air is introduced at a flow rate of / h for 100-200s; then, after skimming, concentrate slurry and tailings slurry are obtained.

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