Production process for preparing potassium chloride by utilizing mixture of carnallite ore and sylvinite ore

Abstract

A production process for preparing potassium chloride by using a mixture of carnallite ore and sylvinite ore comprises the following steps: mixing raw ore, and then crushing for the first time to obtain a mixed raw material which accounts for more than or equal to 90% of the mixed raw material with the particle size of less than or equal to 20mm; adding the mixed raw materials into the saturated mother liquor for size mixing; carrying out secondary crushing on the material subjected to size mixing, and then decomposing; the decomposed slurry is crushed for the third time and then used for flotation; the particle size after the crushing is smaller than that of the previous crushing; the method comprises the following steps: adding a flotation collecting agent and carrying out flotation to obtain crude potassium slurry S1 and tailings T1, filtering the crude potassium slurry S1 to obtain a crude potassium filter cake K1 and a mother solution L1, filtering the tailings T1 to obtain T2 and a mother solution L1, and washing, filtering, drying and dehydrating the obtained K1 to obtain a potassium chloride product. The method is simple in technological process and high in yield.

Description

Technical Field

[0001] The present invention relates to the field of a preparation method of potassium chloride, and particularly to a production process for preparing potassium chloride by using a mixture of carnallite ore and sylvite ore. Background Art

[0002] Currently, carnallite ore is generally processed by a decomposition - positive flotation or decomposition - crystallization - positive flotation process for the production of agricultural potassium chloride fertilizers. However, in these two processes, fresh water is often added in the decomposition or decomposition - crystallization process to decompose carnallite, and then flotation is carried out, such as the processes disclosed in CN107739037A, CN 102963912A, and CN 204079502U. The disadvantage of adding fresh water to decompose carnallite at the front end of the process is that the amount of decomposition fresh water is not easy to control. If the amount of fresh water added is too small, the concentration and viscosity of the decomposition liquid both increase, the decomposition speed becomes slower, the entrainment rate of impurities in the flotation foam increases, resulting in a significant decrease in the grade of crude potassium (the grade of crude potassium in Qarhan Salt Lake, Qinghai is generally between 58% and 70%), and the potassium chloride grade in the flotation tailings is 3 - 5.7%, resulting in a low potassium chloride recovery rate of the system. 2 The grade of crude potassium generally ranges from 58% to 70% in Qarhan Salt Lake, Qinghai. The potassium chloride grade in the flotation tailings is between 3% and 5.7%, leading to a low potassium chloride recovery rate of the system.

[0003] CN112551553B discloses a high - recovery production process for extracting potassium chloride from carnallite ore. This process requires multiple decomposition - crystallization steps and then obtains KCl through flotation concentration and filtration, and the process is quite complex. Summary of the Invention

[0004] (I) Technical Problems to be Solved

[0005] In view of the above - mentioned disadvantages and deficiencies of the prior art, the present invention provides a production process for preparing potassium chloride by using a mixture of carnallite ore and sylvite ore, which has a simple process and a high recovery rate.

[0006] Technical Solution

[0007] To achieve the above - mentioned purpose, an embodiment of the present invention provides a production process for preparing potassium chloride by using a mixture of carnallite ore and sylvite ore, including the steps of:

[0008] Mix carnallite and sylvite raw ore, and then perform the first crushing to obtain a mixed raw material of carnallite and sylvite, where the proportion of the mixed raw material with a particle size ≤ 20mm is ≥ 90% of the mixed raw material;

[0009] Add the mixed raw material to a saturated mother liquor for pulp - making. The saturated mother liquor consists of Na + , K + , Mg 2+ / / Cl - , SO 4 2- —H 2Mother liquor composition at the triple co-saturation point D of epsomite, KCl, and carnallite in the metastable phase diagram of the quinary system at 35 °C;

[0010] The slurried material is subjected to a second crushing, and the material after the second crushing is decomposed.

[0011] The decomposed slurry is subjected to a third crushing, and the material after the third crushing is used for flotation; the particle size after each crushing in the three crushings is smaller than that of the previous crushing.

[0012] A flotation collector is added and flotation is carried out to obtain a crude potassium slurry S1 and tailings T1. The crude potassium slurry S1 is filtered to obtain a crude potassium filter cake K1 and mother liquor L1. The tailings T1 are filtered to obtain T2 and mother liquor L1. The obtained K1 is washed, filtered, and dried and dehydrated to obtain potassium chloride products.

[0013] In one embodiment, before the first crushing, carnallite and sylvinite raw ore are mixed and subjected to a primary screening, and the oversize material is crushed to obtain a mixed raw material of carnallite and sylvinite.

[0014] Before the second crushing, the slurried material is subjected to a second screening. The oversize material is subjected to a second crushing, and the undersize material from the second screening and the material after the second crushing are used for decomposition.

[0015] Before the third crushing, the decomposed slurry is subjected to a third screening. The oversize material is subjected to a third crushing, and the undersize material from the third screening and the material after the third crushing are used for flotation; the particle size of each screening in the three screenings is smaller than that of the previous screening.

[0016] In one embodiment, the particle size of the first screening is 20 - 12.5 mm. The oversize material is crushed, and the crushing particle size P90 is between 20 - 12.5 mm. The particle size of the second screening is 5 - 2 mm. The oversize material is subjected to a secondary crushing, and the crushing particle size P90 is between 5 - 2 mm. The particle size of the third screening is 1 - 0.85 mm. The oversize material is crushed, and the crushing particle size P90 is between 1 - 0.85 mm.

[0017] In one embodiment, the carnallite ore is a natural solid carnallite ore containing sodium chloride and epsomite minerals; the sylvinite ore is a natural solid sylvinite ore containing sodium chloride, kieserite, and gypsum minerals.

[0018] In one embodiment, the ratio of carnallite to sylvinite is 6 - 8:2 - 4.

[0019] In one embodiment, the decomposition is carried out in a decomposition tank. The decomposition tank is provided with a draft tube. Under the action of a stirrer, the slurry is in a closed-circuit circulation flow state from bottom to top in the draft tube. The decomposition of carnallite is carried out during the upward stroke of the flow state. The residence time of the slurry in the decomposition tank is 30 min - 120 min.

[0020] In one embodiment, when decomposition is carried out in the decomposition tank, washing mother liquor is added to the decomposition tank.

[0021] In one embodiment, the washing mother liquor is the high-potassium mother liquor L2 obtained by washing and filtering K1; the mass contents of the main chemical components of the washing mother liquor are as follows: K + : 4.2 - 6.863%, Na + 0.36 - 3.96%, Mg 2+ 0.1 - 2.74%, SO 4 2- 2.189 - 5.542%, Cl - 13.05 - 15.405%. Preferably, the addition amount of the washing mother liquor is 30% - 45% of the total mass of the original ore.

[0022] In one embodiment, the third crushing is carried out by a rod mill for grinding, and the oversize materials are collected through a chute. Mother liquor L1 is added to the chute, and the addition amount of mother liquor L1 satisfies that the discharge concentration of the rod mill is 45 - 60%, and the grinding time is 1.0 - 6.0 minutes.

[0023] In one embodiment, the mass contents of the main components of the saturated mother liquor at point D are K + 1.40 - 2.069%, Na + 0.14 - 1.67%, Mg 2+ 0.1 - 7.20%, Cl - 19.74 - 21.46%, SO 4 2- 2.21 - 4.189%.

[0024] (III) Beneficial effects

[0025] The beneficial effects of the present invention are as follows: In the present invention, for the mixed ore raw materials of carnallite ore and sylvite ore, high-quality coarse-grained potassium chloride products are extracted through the combination of three-stage crushing process and cold decomposition - flotation - washing process, reducing the grinding treatment volume and improving the grinding efficiency. In addition, through the gradual reduction of the grinding particle size and the combination of cold decomposition - flotation - washing process, the system yield is improved, changing the disadvantages of the traditional grinding - decomposition - flotation process for producing potassium chloride products, such as finer particle size, poor product quality, and high process energy consumption. The purity of KCl obtained by the solution of the present invention is greater than or equal to 90%, and the decomposition yield of KCl reaches 119% (relative to the original ore), improving the product quality and market competitiveness. In addition, the production process of the present invention is simple and suitable for large-scale development. Description of the drawings

[0026] Figure 1Schematic diagram of the production process for preparing potassium chloride using a mixture of carnallite ore and sylvite ore in an embodiment. Specific embodiments

[0027] To better explain the present invention for easy understanding, the present invention will be described in detail below through specific embodiments.

[0028] Please refer to Figure 1 , an embodiment of the present invention provides a production process for preparing potassium chloride using a mixture of carnallite ore and sylvite ore, including the steps:

[0029] S1. After mixing carnallite and sylvite raw ores, perform the first crushing to obtain a mixed raw material of carnallite and sylvite, and the proportion of the mixed raw material with a particle size ≤ 20 mm is ≥ 90%.

[0030] In one embodiment, specifically, the carnallite ore is a natural solid carnallite ore containing sodium chloride and epsomite minerals; the sylvite ore is a natural solid sylvite ore containing sodium chloride, kieserite and gypsum minerals. The ratio of carnallite to sylvite is 6 - 8:2 - 4. Generally, the ratio of carnallite to sylvite needs to be controlled according to the actual ratio of carnallite and sylvite in the ore source. In the prior art, the ratio of carnallite to sylvite can only be limited to a relatively small range, such as 6:4, which has an adverse effect on the effective application rate of the raw ore in actual production and will cause waste of resources. In this application, since the actual mass ratio of carnallite and sylvite in the ore source is about 7.2:2.8, the ratio of carnallite to sylvite of 6:4 in the prior art will cause the carnallite raw ore to not be fully utilized. By adopting the process of this application, the mass ratio range of carnallite and sylvite can be expanded, the raw ore can be fully utilized, and the requirements for the actual ratio of the raw ore and the mining method of the raw ore are lower.

[0031] Preferably, specifically, before the first crushing, mix the carnallite and sylvite raw ores and perform a first screening, and crush the oversize material to obtain a mixed raw material of carnallite and sylvite. More preferably, the particle size of the first screening is 20 - 12.5 mm, the oversize material is crushed, and the crushing particle size P90 is between 20 - 12.5 mm; thus, the particle size of most of the materials after the first screening + crushing is P90 between 20 - 12.5 mm, that is to say, the minimum particle size requirement for the first screening and crushing can be 12.5 mm. Through screening + crushing, the particle size of most of the materials can reach 12.5 mm, and this proportion can reach more than 90%. The first screening and crushing perform rough screening and crushing on the large - sized raw ore, and the particle size is relatively large compared with the subsequent screening and crushing. However, if the ore is crushed into very small particles at one time, it will cause a significant increase in the crushing energy consumption and time, thereby increasing the cost and being unfavorable for industrial production. The above - mentioned particle size limit not only helps to save crushing energy consumption and time, but also ensures the smooth progress of the next slurry - making and pumping.

[0032] S2. Add the mixed raw materials to the saturated mother liquor for pulp mixing. The saturated mother liquor is composed of the mother liquor composition at the triple co-saturation point D of Glauber's salt, KCl, and carnallite in the metastable phase diagram of the five-component system of Na + , K + , Mg 2+ / / Cl - , SO 4 2- —H 2 O at 35°C.

[0033] In one embodiment, specifically, the mass content of the main components of the saturated mother liquor at point D is K+1.40 - 2.069%, Na+0.14 - 1.67%, Mg2+0.1 - 7.20%, Cl-19.74 - 21.46%, SO42-2.21 - 4.189%.

[0034] S3. The pulp after pulp mixing is subjected to secondary crushing, and the materials after secondary crushing are decomposed.

[0035] Preferably, the pulp after pulp mixing is subjected to secondary screening. The oversize is subjected to secondary crushing, and the materials after secondary crushing and the undersize after secondary screening are decomposed.

[0036] In one embodiment, specifically, the particle size of the secondary screening is 5 - 2 mm. The oversize goes for secondary crushing, and the crushing particle size with P90 ranging from 5 - 2.0 mm. This particle size range is beneficial to the decomposition of carnallite, enabling the materials to reach the particle size for decomposition and dissociation, improving the decomposition effect and shortening the decomposition time.

[0037] Specifically, the decomposition is carried out in a decomposition tank. The decomposition tank is equipped with a draft tube. Under the action of a stirrer, the slurry flows in a closed-loop upward flow state in the draft tube, and the carnallite decomposition occurs during the upward stroke of the flow state. The residence time of the slurry in the decomposition tank is 30 min - 120 min.

[0038] When carrying out the decomposition in the decomposition tank, washing mother liquor is added to the decomposition tank. The addition amount of the washing mother liquor is 30 - 45% of the total mass of the original ore. The addition amount of the washing mother liquor needs to be strictly controlled. Excessive mother liquor points in the potassium magnesium alum phase region in the phase diagram of the five-component water-salt system of K + , Na + , Mg 2+ / / Cl - , SO 4 2- —H 2 O, close to the potassium kainite phase region. This causes potassium kainite to appear during decomposition, and the KCl collector cannot collect potassium kainite, which will lead to tailings K +The content is on the high side. To avoid this phenomenon, it is necessary to reduce the amount of mother liquor after mixing potassium washing. When the mother liquor after mixing potassium washing is reduced to 30-45%, the flotation mother liquor point moves away from the kainite phase region and approaches the carnallite phase region. However, if the amount of mother liquor after mixing potassium washing is further reduced, the Mg in the solid phase 2+ has too high a content, the carnallite is not decomposed sufficiently, which will reduce the concentrate yield and grade and increase the K+ content in the tailings.

[0039] S4. The slurry after decomposition is crushed for the third time, and the material after the third crushing is used for flotation; the particle size after each crushing during the three crushings is smaller than that of the previous crushing.

[0040] Preferably, the slurry after decomposition is screened for the third time, the oversize is crushed for the third time, and the material after the third crushing and the undersize after the third screening are used for flotation together; the particle size of each screening during the three screenings is smaller than that of the previous screening.

[0041] In one embodiment, specifically, the particle size of the third screening is 1-0.85 mm. Since the particle size of this crushing is 1-0.85 mm, and it is difficult for general crushers in actual production to reach this particle size requirement, a rod mill is used to achieve this function. Through three screenings and three crushings, and the particle size is gradually reduced each time, finally the particle size is controlled below 1-0.85 mm. In this particle size range, sylvite can be floated out. In addition, if single-stage crushing is used, it is impossible to achieve this particle size. With three-stage crushing, the raw material after the first screening and crushing can be pumped after pulp adjustment, and this particle size control can save costs and time to the greatest extent. The particle size control of the second screening and crushing can achieve the most effective decomposition and improve the decomposition effect. The last screening and crushing can meet the particle size requirements for flotation, achieve efficient flotation, and improve the recovery rate.

[0042] Specifically, the third crushing is carried out by a rod mill for grinding. The oversize of the screening machine before grinding is collected through a chute, and mother liquor L1 is added to the chute. The addition amount of mother liquor L1 satisfies that the discharge concentration of the rod mill is 45-60%, and the grinding time is 1.0-6.0 minutes.

[0043] S5. Add a flotation collector and carry out flotation to obtain a crude potassium slurry S1 and tailings T1. After filtering the crude potassium slurry S1, a crude potassium filter cake K1 and mother liquor L1 are obtained. After filtering the tailings T1, T2 and mother liquor L1 are obtained. The obtained K1 is washed, filtered, and dried and dehydrated to obtain potassium chloride products.

[0044] Preferably, the flotation collector can be: an amine cationic flotation collector. Specifically, the amine cationic collector can be octadecylamine or an octadecylamine triple-agent.

[0045] Specifically, in one embodiment, the washing mother liquor is K1, and the high-potassium mother liquor L2 is obtained through washing and filtration; the high-potassium mother liquor L2 is obtained by washing and filtering the washing mother liquor K1; the mass contents of the main chemical components of the washing mother liquor are as follows: K + : 4.2 - 6.863%, Na + 0.36 - 3.96%, Mg 2+ 0.1 - 2.74%, SO 4 2- 2.189 - 5.542%, Cl - 13.05 - 15.405%. The washing mother liquor is returned to the decomposition tank for decomposition.

[0046] Since the washing mother liquor generated after washing in S5 is returned to the decomposition step, the single-pass yield of KCl is greatly improved. In the prior art, generally, the washing mother liquor is transported to the salt field for salt field spreading and drying, and the decomposition yield of KCl obtained is only about 70%. Through the reflux control of this application, the decomposition yield of KCl can be increased to 119% (relative to the original ore), which is due to the recycling of K + contained in the washing mother liquor. At the same time, the liquid used in the decomposition of this application is the washing mother liquor generated in the process. In this decomposition step, fresh water is not used, which greatly reduces the fresh water consumption of the system and lowers the cost. And in some ore source areas, due to environmental reasons, the nearby fresh water resources are very scarce. If fresh water needs to be used, seawater needs to be treated to obtain fresh water. The process of this application solves this problem, greatly improves the applicability of the process, and reduces the cost of the entire process.

[0047] In the present invention, for the mixed ore raw materials of carnallite ore and sylvite ore, through the combination of a three-stage crushing process and a cold decomposition - flotation - washing process, high-quality coarse-grained potassium chloride products are extracted, reducing the grinding treatment volume and improving the grinding efficiency. In addition, through the gradual reduction of the grinding particle size and the combination of the cold decomposition - flotation - washing process, the system yield is increased, and the disadvantages of the traditional grinding - decomposition - flotation process for producing potassium chloride products with very fine particle size (F 50 is about 74 microns), poor product quality, and high process energy consumption are improved. The purity of KCl obtained by the method of the present invention is greater than or equal to 90%, the decomposition yield of KCl reaches 119% (relative to the original ore), and the product particle size reaches F 50 is 206 microns, improving the product quality and market competitiveness. In addition, the production process of the present invention is simple and suitable for large-scale development.

[0048] The following further illustrates the present invention with reference to embodiments. The raw materials used in the implementation of the present invention are the underground primary carnallite ore of a potassium salt mine in Africa.

[0049] Example 1

[0050] In this implementation case, the composition of the potassium mixed salt co-saturated mother liquor is at a certain point in the KCl phase region at a temperature of 35 °C, and its composition is Na + 1.591%, K + 2.069%, Mg 2+ 6.342%, SO 4 2- 4.189%, Cl - 19.740%.

[0051] (1) Collect the underground primary carnallite ore (the main component content in the original ore is K + 5.70%, Na + 12.17%, Mg 2+ 7.70%, Cl - 35.81%, SO 4 2- 15.13%) and sylvite ore (the main component content in the original ore is K + 13.86%, Na + 25.45%, Mg 2+ 0.1793%, Cl - 51.96%, SO4 2- 3.937%), and mix them to obtain a mixed raw material according to the mass ratio of 6:4.

[0052] (2) Screen the mixed raw material for the first time, with a screening particle size of 12.5 mm. The oversize material is subjected to the first crushing until P90 is 12.5 mm.

[0053] (3) Add the crushed mixed material to a stirring tank filled with a saturated solution for pulp mixing. The saturated mother liquor is composed of Na + , K + , Mg 2+ / / Cl - , SO4 2- —The mother liquor composition near the triple co-saturation point D of the metastable phase diagram of the five-component hydrosalt of H2O, kainite, KCl, and carnallite. The mass content of the main components is Na + 1.591%, K + 2.069%, Mg 2+ 6.342%, SO4 2- 4.189%, Cl - 19.740%.

[0054] (4) Screen the pulp-mixed material for the second time, with a screening particle size of 2 mm. The oversize material is subjected to the second crushing until P90 is 2 mm. The material after the second crushing and the undersize material after the second screening are transported to the decomposition tank 。

[0055] (5) Add washing mother liquor into the decomposition tank. Its composition is Na + 3.51%, K + 5.70%, Mg 2+ 1.342%, SO4 2- 2.189%, Cl - 14.740%. The liquid addition amount is 45% of the raw material amount. The decomposition tank is equipped with a draft tube. Under the action of the stirrer, the slurry flows in a closed-loop circulation from bottom to top in the draft tube, and carnallite decomposition occurs during the upward stroke of the flow state.

[0056] (6) After the slurry stays in the decomposition tank for 30 minutes until the carnallite is fully decomposed, the slurry is transported to a sieve with a screen hole size of 0.85 mm for the third screening. The oversize of the rod mill is used for the third crushing. The grinding time is 5 minutes and the grinding concentration is 55%. After the third crushing, the material and the undersize are transported to the flotation conditioning tank together.

[0057] (7) Add a flotation collector into the flotation conditioning tank. The slurry is transported to the flotation machine. Through flotation, crude potassium slurry S1 and tailings T1 are obtained. The tailings T1 are transported to the tail salt yard and naturally filtered to obtain T2 and mother liquor L1. After filtration of S1, crude potassium filter cake K1 and mother liquor L1 are obtained. The K + mass content in the tailings T1 is 0.970%.

[0058] (8) Fresh water is added to wash the filter cake K1. The fresh water addition amount is 0.74 times the mass of K1. It is stirred and washed in the stirring tank. After 40 minutes of stirring and washing, the slurry is filtered to obtain mother liquor L2 and refined potassium K2. K2 is dried and dehydrated to obtain potassium chloride KCl (mass percentage content 92%) potassium chloride product. The product particle size F 50 is about 200 microns.

[0059] Example 2

[0060] In this embodiment, the composition of the potassium mixed salt co-saturated mother liquor is at a certain point in the KCl phase region at 35°C. Its composition is Na + 1.591%, K + 2.069%, Mg 2+ 6.342%, SO 4 2- 4.189%, Cl - 19.740%.

[0061] (1) Collect the underground primary carnallite ore from a potassium salt mine in Africa (the main component content in the raw ore is K + 6.92%, Na + 12.25%, Mg 2+7.52%, Cl - 38.86%, SO 4 2- 13.42%) and sylvinite ore (the main component content in the raw ore is K + 14.7%, Na + 24.75%, Mg 2+ 0.34%, Cl - 51.71%, SO4 2- 4.73%), and they are mixed in a mass ratio of 7:3 to obtain the mixed raw material.

[0062] (2) The mixed raw material is subjected to the first screening, the screening particle size is 20 mm, and the oversize material is subjected to the first crushing until P95 is 20 mm.

[0063] (3) The crushed mixture is added to a stirring tank containing a saturated solution for pulp mixing. The composition of the saturated mother liquor is Na at 35 °C + , K + , Mg 2+ / / Cl - , SO 4 2- —The mother liquor composition near the triple co-saturation point D of the metastable phase diagram of the five-component hydrosalt of MgSO4·KCl·MgCl2·6H2O, KCl, and carnallite, and the mass content of the main components is Na + 1.451%, K + 1.869%, Mg 2+ 6.62%, SO 4 2- 3.189%, Cl - 20.040%.

[0064] (4) The pulp-mixed material is subjected to the second screening, the screening particle size is 5 mm, and the oversize material is subjected to the second crushing until P95 is 5 mm. The material after the second crushing and the undersize material after the second screening are transported to the decomposition tank.

[0065] (5) Wash mother liquor is added to the decomposition tank. The wash mother liquor is a high-potassium mother liquor, and its component mass composition is Na + 3.604%, K + 6.368%, Mg 2+ 2.154%, SO4 2- 5.452%, Cl - 13.7%, and the addition amount is 35% of the mass of the raw ore.

[0066] (6) The residence time of the slurry in the decomposition tank is 60 minutes. After the carnallite is fully decomposed, the slurry is transported to a sieve with a screen size of 1 mm for the third screening. The oversize material is subjected to the third crushing, and after the third crushing, the material and the undersize material are transported to the flotation conditioning tank together.

[0067] (7) A flotation collector is added to the flotation conditioning tank, and the slurry is transported to the flotation machine. Through flotation, a crude potassium slurry S1 and tailings T1 are obtained. The tailings T1 are transported to the tail salt yard, and after natural filtration, T2 and mother liquor L1 are obtained. After filtration of S1, a crude potassium filter cake K1 and mother liquor L1 are obtained. The K + mass content in the tailings T1 is 1.46%.

[0068] (8) The obtained K1 is washed by adding fresh water. The addition amount of fresh water is 0.74 times the mass of K1. After stirring and washing in the stirring tank for 40 minutes and then filtering the slurry, mother liquor L2 and refined potassium K2 are obtained. K2 is dried and dehydrated to obtain a potassium chloride KCl (mass percentage content 93%) potassium chloride product, and the product particle size F 50 is about 200 microns.

[0069] Example 3

[0070] In this embodiment, the composition of the potassium mixed salt co-saturated mother liquor is at a certain point in the KCl phase region at 35 °C, and its composition is K + 1.96%, Na + 1.67%, Mg 2+ 7.20%, Cl - 19.81%, SO4 2- 3.13%.

[0071] (1) Collect the underground primary carnallite ore (the main component content in the raw ore is K + 6.030%, Na + 12.78%, Mg 2+ 6.480%, Cl - 36.88%, SO4 2- ) and sylvinite ore (the main component content in the raw ore is K + 12.76%, Na + 24.06%, Mg 2+ 0.31%, Cl - 48.77%, SO4 2- ) from a potassium salt mine in Africa, and mix them in a mass ratio of 8:2 to obtain a mixed raw material.

[0072] (2) The mixed raw material is subjected to the first screening, and the screening particle size is 12.5 mm. The oversize material is subjected to the first crushing and crushed to P95 of 12.5 mm.

[0073] (3) Add the crushed mixed raw materials to the stirring tank filled with the saturated solution to adjust the pulp. The composition of the saturated mother liquor is Na at 35 °C + , K + , Mg 2+ / / Cl - , SO4 2- —the mother liquor composition near the triple co-saturation point D of the metastable phase diagram of the five-component hydrous salts of epsomite, KCl, and carnallite, and the mass content of the main components is K + 1.96%, Na + 1.67%, Mg 2+ 7.20%, Cl - 19.81%, SO4 2- 3.13%.

[0074] (4) Screen the material after pulp adjustment for the second time. The screening particle size is 2 mm. The oversize material is crushed for the second time until P95 is 2 mm. The material after the second crushing and the undersize material from the second screening go to the decomposition tank.

[0075] (5) Add washing mother liquor to the decomposition tank. The washing mother liquor is high-potassium mother liquor, and its component mass composition is Na + 2.604%, K + 5.24%, Mg 2+ 0.34%, SO 4 2- 3.467%, Cl - 13.7%, and the addition amount is 30% of the original ore amount.

[0076] (6) The residence time of the slurry in the decomposition tank is 60 minutes. After the carnallite is fully decomposed, the slurry is transported to a sieve with a screen hole size of 0.85 mm for the third screening. The oversize material is crushed for the third time. The material after the third crushing and the undersize material are transported to the flotation and pulp adjustment tank together.

[0077] (7) Add a flotation collector to the flotation and pulp adjustment tank. The slurry is transported to the flotation machine. Through flotation, a crude potassium slurry S1 and tailings T1 are obtained. The tailings T1 are transported to the tail salt yard and naturally filtered to obtain T2 and mother liquor L1. After S1 is filtered, a crude potassium filter cake K1 and mother liquor L1 are obtained. The mass content of K in the tailings T1 + is 1.039%.

[0078] (8) Step 8: The obtained K1 is washed by adding fresh water. The addition amount of fresh water is 1.02 times the mass of K1. Stir and wash in the stirring tank. After 40 minutes of stirring and washing, the slurry is filtered to obtain mother liquor L2 and refined potassium K2. K2 is dried and dehydrated to obtain a potassium chloride product with a potassium chloride (mass percentage content of 95%), and the product particle size F 50 is about 206 microns.

[0079] In the description of this specification, the descriptions of terms such as "one embodiment", "some embodiments", "embodiment", "example", "specific example" or "some examples" mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0080] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A production process for preparing potassium chloride using a mixture of carnallite ore and sylvite ore, characterized in that: include: The carnallites and sylvite ores are mixed and crushed for the first time to obtain a mixed raw material of the carnallites and sylvite, wherein the mixed raw material has a particle size of ≤20 mm and accounts for ≥90%; The mixed raw materials are added to the saturated mother liquor for slurry adjustment. The saturated mother liquor is Na + , K + Mg 2+ / / Cl - 、SO4 2- —The mother liquor composition of the three-phase saturation point D of Epsom salt, KCl and carnallite in the metastable phase diagram of the H2O quinary system at 35℃; The slurry-adjusted material is crushed for the second time, and the second crushed material is decomposed; After decomposition, the slurry is crushed for the third time, and the material after the third crushing is used for flotation; the particle size after the third crushing is smaller than the particle size after the previous crushing; A flotation collector is added and flotation is performed to obtain a crude potassium slurry S1 and tailings T1. The crude potassium slurry S1 is filtered to obtain a crude potassium filter cake K1 and a mother liquor L1. The tailings T1 is filtered to obtain T2 and a mother liquor L1. The obtained K1 is washed, filtered, dried and dehydrated to obtain a potassium chloride product.

2. The production process for preparing potassium chloride using a mixture of carnallite ore and sylvite ore according to claim 1, characterized in that: The carnallites and sylvite raw ore mixture is screened once before the first crushing, and the sieved material is crushed to obtain a mixed raw material of the carnallites and sylvite; Before the second crushing, the slurry-adjusted material is screened for the second time, the screened material is crushed for the second time, and the screened material of the second screening and the second crushed material are used for decomposition; Before the third crushing, the decomposed slurry is screened for the third time, the screened material is crushed for the third time, and the screened material of the third screening and the material after the third crushing are used for flotation; wherein the screening particle size of the third screening is smaller than the previous screening particle size.

3. The production process for preparing potassium chloride by utilizing a mixture of carnallite ore and sylvite ore according to claim 2, characterized in that: The particle size of the first screening is 20-12.5mm, the material on the screen is crushed, and the crushed particle size P90 is between 20-12.5mm; the particle size of the second screening is 5-2mm, the material on the screen is crushed for the second time, and the crushed particle size P90 is between 5-2mm, the particle size of the third screening is 1-0.85mm, the material on the screen is crushed, and the crushed particle size P90 is between 1-0.85mm.

4. The production process for preparing potassium chloride using a mixture of carnallite ore and sylvite ore according to claim 1, characterized in that: The carnallite ore is a natural solid carnallite ore containing sodium chloride and epsomite minerals; the sylvite ore is a natural solid sylvite ore containing sodium chloride, kieserite and gypsum minerals.

5. The production process for preparing potassium chloride using a mixture of carnallite ore and sylvite ore according to claim 4, characterized in that: The ratio of carnallite to sylvite is 6-8:2-4.

6. The production process for preparing potassium chloride using a mixture of carnallite ore and sylvite ore according to claim 1, characterized in that: The decomposition is carried out in a decomposition tank, which is provided with a guide tube. Under the action of the agitator, the slurry flows in a closed-loop circulation state from bottom to top in the guide tube, and the carnallite is decomposed in the upward stroke of the flow state. The slurry stays in the decomposition tank for 30 minutes to 120 minutes.

7. The production process for preparing potassium chloride using a mixture of carnallite ore and sylvite ore according to claim 1, characterized in that: When decomposition is carried out in the decomposition tank, washing mother liquor is added to the decomposition tank.

8. The production process for preparing potassium chloride using a mixture of carnallite ore and sylvite ore according to claim 7, characterized in that: The washing mother liquor is the high potassium mother liquor L2 obtained by washing and filtering K1; the mass content of the main chemical components of the washing mother liquor is: K + :4.2~6.863%,Na + 0.36~3.96%,Mg 2+ 0.1~2.74%, SO4 2- 2.189~5.542%, Cl - 13.05-15.405%, preferably, the addition amount of the washing mother liquor is 30%-45% of the total mass of the original ore.

9. The production process for preparing potassium chloride using a mixture of carnallite ore and sylvite ore according to claim 1, characterized in that: The third crushing adopts rod mill for grinding, the material on the screen is collected through a chute, and mother liquor L1 is added to the chute. The addition amount of mother liquor L1 satisfies the discharge concentration of rod mill to be 45-60%, and the grinding time is 1.0 to 6.0 minutes.

10. The production process for preparing potassium chloride using a mixture of carnallite ore and sylvite ore according to claim 1, characterized in that: The mass content of the main component of the saturated mother liquor at point D is K + 1.40~2.069%、Na + 0.14~1.67%、Mg 2+ 0.1~7.20%、Cl - 19.74~21.46%、SO4 2- 2.21~4.189%.

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