Method for preparing potassium sulfate using underground primary sulfur-rich potassium-containing minerals

Abstract

A method for preparing potassium sulfate using underground primary sulfur-rich potassium-containing minerals, comprising: mixing and stirring a potassium chloride raw material and a potassium magnesium vanadium raw material, adding water with TDS / mg / L＜45000 and an SOP mother liquor and stirring, then filtering a resulting slurry to obtain a washing mother liquor LLeo and a filter cake S2; conveying the filter cake S2 to a crystallizer, adding water with TDS / mg / L＜45000 and the SOP mother liquor, performing crystallization in the crystallizer while maintaining the temperature in the crystallizer at 40-65°C, filtering a crystallized slurry to obtain a wet potassium sulfate material and a filtrate, and returning the filtrate for use as SOP mother liquor. The product obtained using the solution of the present application has a relatively high yield and relatively low costs.

Description

A method for preparing potassium sulfate by using underground primary sulfur-rich potassium-containing minerals TECHNICAL FIELD

[0001] The present application relates to the field of potassium sulfate preparation methods, and particularly relates to a method for preparing potassium sulfate by using underground primary sulfur-rich potassium-containing minerals. BACKGROUND

[0002] At present, potassium sulfate is an important chlorine-free potassium fertilizer, which is widely used in agriculture and has a large market demand. In the prior art, CN108349743A discloses a method for producing potassium sulfate from potassium-containing ores at high ambient temperatures. The method comprises contacting an aqueous potassium- and sulfate-containing composition with magnesium chloride, thereby obtaining a composition comprising the potassium salt kieserite; concentrating the potassium salt kieserite from the composition; reacting the potassium salt kieserite with magnesium sulfate and potassium sulfate in order to convert the potassium salt kieserite into kieserite; contacting the kieserite with water in order to remove excess; and contacting the kieserite with water in order to leach the magnesium sulfate contained in the kieserite and at least substantially selectively precipitate potassium sulfate. The method can be operated at a higher temperature, in particular at a temperature higher than 35℃, but the total recovery rate of the product obtained by the method is about 48% in the laboratory scale experiment.

[0003] CN111533140B discloses a method for preparing potassium magnesium sulfate fertilizer, potassium chloride and potassium sulfate from sulfate-type carnallite. The method first performs flotation treatment on the sulfate-type carnallite ore by using an anionic flotation agent to obtain a potassium-sulfur mixed salt concentrate and a chloride-type tailing; then performs reverse flotation treatment on the chloride-type tailing by using a reverse flotation reagent to obtain a magnesium chloride-type tailing and sodium chloride; and finally performs washing and refining and decomposition treatment on the magnesium chloride-type tailing to obtain potassium chloride. The present application adopts a double-flotation separation technology to provide raw material basis for simultaneously and efficiently preparing potassium chloride and potassium magnesium sulfate fertilizer products; and simultaneously adopts a “reverse flotation-washing-hungstonite-decomposition” technology to remove sodium chloride and magnesium chloride from the chloride-type tailing in sequence, which is conducive to obtaining a carnallite concentrate and efficiently preparing a high-grade potassium chloride product. The method needs a flotation agent and a reverse flotation reagent, and a large amount of water is needed in the process, which is high in cost. SUMMARY

[0004] (I) Technical problems to be solved

[0005] In view of the above-mentioned defects and deficiencies of the prior art, the present application provides a method for preparing potassium sulfate by using underground primary sulfur-rich potassium-containing minerals, which can obtain a high yield and is low in cost under high temperature conditions.

[0006] (II) Technical solutions

[0007] In order to achieve the above-mentioned purposes, the present application provides a method for preparing potassium sulfate by using underground primary sulfur-rich potassium-containing minerals, which comprises the following steps:

[0008] Mixing and stirring the potassium chloride raw material and the potassium magnesium vanadium raw material, adding the SOP mother liquor and stirring, filtering the slurry to obtain a washing mother liquor L Leo and the filter cake S2;

[0009] The filter cake S2 is transported to a crystallizer, water with TDS / mg / L < 45000 and the SOP mother liquor are added, crystallization is carried out in the crystallizer, the temperature in the crystallizer is kept at 40-65°C, the slurry after crystallization is filtered to obtain potassium sulfate wet material and filtrate, and the filtrate is returned to the use of the SOP mother liquor.

[0010] In an embodiment, the potassium chloride raw material is obtained by the following method:

[0011] After mixing the carnallite and the sylvinite raw ore, the mixed raw material of the carnallite and the sylvinite is obtained after the first crushing, and the particle size of the mixed raw material is ≤20mm, accounting for ≥90%;

[0012] The mixed raw material is added to the saturated mother liquor for slurry preparation, and the saturated mother liquor is composed of the mother liquor of the carnallite, the sylvinite and the halite three-phase co-saturation point D point of the carnallite in the Na + , K + , Mg 2+ / / Cl - , SO4 2- -H2O quinary system 35°C metastable phase diagram;

[0013] The slurry after the slurry preparation is subjected to the second crushing, and the second crushed material is subjected to the decomposition;

[0014] The slurry after the decomposition is subjected to the third crushing, and the third crushed material is used for the flotation; wherein the particle size of the current crushing is smaller than that of the previous crushing;

[0015] The flotation collector is added and the coarse potassium flotation is carried out to obtain the coarse potassium slurry S1 and the tailings T1, the coarse potassium slurry S1 is filtered to obtain the coarse potassium filter cake K1 and the mother liquor L1, the tailings T1 is filtered to obtain T2 and the mother liquor L1, and the obtained K1 is washed, filtered and dried to obtain the potassium chloride product;

[0016] Preferably, before the first crushing, the carnallite and the sylvinite raw ore are mixed and sieved once, and the crushed oversize and undersize are combined to obtain the mixed raw material of the carnallite and the sylvinite;

[0017] The slurry after the slurry preparation is subjected to the second crushing, and the second crushed material is subjected to the decomposition;

[0018] The third screening is performed on the decomposed slurry before the third crushing, the oversize is crushed, and the undersize of the third screening and the crushed material are used for flotation; the particle size of the current screening is smaller than that of the previous screening.

[0019] In an embodiment, the potassium chloride raw material is obtained by the following method:

[0020] The collected underground primary sulfur-rich potassium-containing raw ore is subjected to multi-stage crushing to obtain sulfur-rich potassium-containing minerals of a desired particle size;

[0021] The sulfur-rich potassium-containing minerals are mixed with seawater and stirred and converted at a temperature of 35-50°C to obtain a solid-liquid mixed ore slurry;

[0022] The solid-liquid mixed ore slurry is adjusted with a kainite flotation mother liquor, and after adding and mixing flotation reagents, kainite flotation is performed, wherein the flotation reagents are an aqueous organic sodium salt solution produced by chlorination, sulfonation and saponification of heavy oil;

[0023] The flotation froth obtained in the flotation is filtered and separated, and the obtained solid is kainite concentrate, and part of the flotation mother liquor produced in the flotation is returned to the previous adjustment step.

[0024] In an embodiment, the first screening particle size is 20-12.5 mm, the oversize is crushed, and the crushing particle size is P90 between 20-12.5 mm; the second screening particle size is 5-2 mm, the oversize is crushed, and the crushing particle size is P90 between 5-2 mm, and the third screening particle size is 1-0.85 mm, the oversize is crushed, and the crushing particle size is P90 between 1-0.85 mm.

[0025] In an embodiment, the halite ore is a natural solid halite ore containing sodium chloride and leili salt minerals; the sylvinite ore is a natural solid sylvinite ore containing sodium chloride, kieserite and gypsum minerals, and the main components of the underground primary sulfur-rich potassium-containing raw ore are K + 8.0%-13.0%, Na + 8.0%-21.0%, Mg 2+ 5.0%-8.0%, Cl - 23.0%-35.0%, SO4 2- 20.0%-31.0%.

[0026] In an embodiment, the effective components of the aqueous organic sodium salt solution are sodium petroleum sulfonate with a carbon chain length of 12-16 and sodium chloride, and the mass percentage of sodium petroleum sulfonate in the flotation reagents is 24%-25%, and the mass percentage of sodium chloride is ≤8%.

[0027] In an embodiment, the decomposition is carried out in a decomposition tank, which is provided with a draft tube, under the action of a stirrer, the slurry is in a closed loop circulation flow state from bottom to top in the draft tube, and the carnallite decomposition is carried out in the upward flow state, and the residence time of the slurry in the decomposition tank is 30-120 min.

[0028] Preferably, when the decomposition is carried out in the decomposition tank, a washing mother liquor is added to the decomposition tank, and the addition amount of the washing mother liquor is 30-45% of the total mass of the raw ore.

[0029] In an embodiment, the mass content of the main chemical components of the washing mother liquor is as follows: 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%.

[0030] The mass content of the main components of the saturated mother liquor at point D is as follows: 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%.

[0031] In an embodiment, the kieserite flotation is a closed circuit process of one roughing, one cleaning and returning the cleaning middlings to the roughing, wherein the solid phase mass content in the roughing is 25-35%, and the solid phase mass content in the cleaning is 10-15%.

[0032] In an embodiment, the third crushing is carried out by using a rod mill for grinding, the oversize material is collected by a chute, and the mother liquor L1 is added to the chute, and the addition amount of the mother liquor L1 meets the discharge concentration of 45-60% of the rod mill, and the grinding time is 1.0-6.0 min.

[0033] (Three) beneficial effects

[0034] The beneficial effects of the present application are: in the present application, the potassium chloride raw material and the kieserite raw material are mixed and stirred, in the crystallization, the mixed solution of water and SOP mother liquor with TDS / mg / L<45000 can improve the yield, and due to the utilization of the subsequently generated SOP mother liquor returning system, the purity K2O of the potassium sulfate obtained by using the present scheme is higher than 50%, and the yield is higher than 52.9%. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 is a process flow diagram of a method for producing potassium sulfate using underground primary sulfur-rich potassium-containing minerals according to an embodiment. DETAILED DESCRIPTION

[0036] In order to better explain the present application, the following will be described in detail through specific embodiments.

[0037] Referring to Figure 1, the present application provides a method for producing potassium sulfate using underground primary sulfur-rich potassium-containing minerals, comprising the steps of:

[0038] Mixing and stirring the potassium chloride raw material and the potassium-magnesium-vanadium raw material, adding SOP mother liquor (potassium sulfate synthesis mother liquor) and stirring, filtering the slurry to obtain a washing mother liquor L Leo and a filter cake S2.

[0039] The filter cake S2 is transported to a crystallizer, water with TDS / mg / L < 45000 and SOP mother liquor are added, and crystallization is carried out in the crystallizer, the temperature in the crystallizer is maintained at 40-65°C, the crystallized slurry is filtered to obtain potassium sulfate wet material and filtrate, and the filtrate is returned to the SOP mother liquor for use.

[0040] The water in the present application refers to water with TDS / mg / L < 45000.

[0041] Specifically, a method for producing potassium sulfate using underground primary sulfur-rich potassium-containing minerals comprises the steps of:

[0042] S1, mixing and first crushing halite and sylvinite raw ore to obtain mixed raw materials of halite and sylvinite, the particle size of the mixed raw materials is ≤20mm and the proportion is ≥90%.

[0043] Preferably, the crushing particle size is P90 between 20-12.5mm.

[0044] In an embodiment, specifically, the halite ore is a natural solid halite ore containing sodium chloride and epsomite minerals; the sylvinite ore is a natural solid sylvinite ore containing sodium chloride, langbeinite and gypsum minerals. The ratio of halite to sylvinite is 6-8:2-4. The ratio control of halite and sylvinite generally needs to be considered according to the actual ratio of halite and sylvinite in the mining area. The prior art can only limit the ratio of halite and sylvinite to a relatively small range, for example, 6:4, which has an adverse effect on the effective application rate of raw ore in actual production and causes waste of resources. In the present application, since the actual mass ratio of halite and sylvinite in the mining area is about 7.2:2.8, the ratio of halite and sylvinite 6:4 in the prior art cannot fully utilize the halite raw ore. However, by using the process of the present application, the mass ratio range of halite and sylvinite is expanded, which can fully utilize the raw ore and has lower requirements for the actual ratio of raw ore and the mining method of raw ore.

[0045] S2, the mixed raw materials are added to the saturated mother liquor for pulp conditioning, and the saturated mother liquor is prepared from the Na + , K + , Mg 2+ / / Cl - , SO4 2- -H2O quinary system at 35℃.

[0046] In an embodiment, specifically, the mass content of the main components of the D-point saturated mother liquor 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%。

[0047] S3, the conditioned material is subjected to a second crushing, and the second crushed material is subjected to a decomposition.

[0048] In an embodiment, specifically, the crushing particle size is P90 between 5~2mm. In this particle size range, the carnallite decomposition is facilitated.

[0049] Specifically, the decomposition is carried out in a decomposition tank provided with a draft tube, and under the action of an agitator, the slurry is in a closed-circuit upward flow state in the draft tube, and the carnallite decomposition is carried out in the upward flow state, and the slurry stays in the decomposition tank for 30min-120min.

[0050] When the decomposition is carried out in the decomposition tank, a 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 raw ore. The washing mother liquor addition amount needs to be strictly controlled. Too much mother liquor is located in the kieserite phase area in the K + , Na + , Mg 2+ / / Cl - , SO4 2- -H2O quinary salt system at 35℃, close to the kainite phase area, which causes the occurrence of kieserite during the decomposition, and the KCl collector cannot collect the kieserite, which will lead to a high K + content in the tailings. In order to avoid this phenomenon, the amount of the potassium-mixed washing mother liquor needs to be reduced. When the amount of the potassium-mixed washing mother liquor is reduced to 30~45%, the flotation mother liquor point is far away from the kieserite phase area and close to the carnallite phase area. However, if the amount of the potassium-mixed washing mother liquor is continuously reduced, the Mg 2+ content in the solid phase is too high, the carnallite decomposition is not sufficient, the concentrate yield and grade are reduced, and the K+content in the tailings is increased.

[0051] S4, the decomposed slurry is subjected to third crushing, and the crushed material is used for flotation; wherein the particle size of the material after each crushing is smaller than that after the previous crushing.

[0052] In an embodiment, specifically, the third screening particle size is 1-0.85 mm. Since the particle size after the third crushing is 1-0.85 mm, a rod mill is used to achieve this function because a general crusher in actual production is difficult to meet this particle size requirement.

[0053] Preferably, the carnallite and sylvinite raw ore are mixed before the first crushing, and then subjected to a first screening, and the screened material and the undersize material are combined to obtain a mixed raw material of the carnallite and sylvinite;

[0054] The material after the mixing is subjected to a second screening before the second crushing, the oversize material is subjected to the second crushing, and the undersize material of the second screening and the material after the second crushing are used for decomposition;

[0055] The material after the decomposition is subjected to a third screening before the third crushing, the oversize material is subjected to the third crushing, and the undersize material of the third screening and the material after the third crushing are used for flotation; wherein the particle size of the material after each screening is smaller than that after the previous screening.

[0056] The screening before each crushing can screen out the material meeting the particle size requirement, thereby reducing the amount of material that needs to be crushed, reducing the cost and time, and reducing the damage to the equipment.

[0057] Specifically, the first screening particle size is 20-12.5 mm, the oversize material is crushed, and the crushing particle size is P90 between 20-12.5 mm; thereby the particle size of most of the material after the first screening + crushing is P90 between 20-12.5 mm, that is, the minimum particle size requirement of the first screening and crushing is 12.5 mm, and through the screening + crushing, the particle size of most of the material can reach 12.5 mm, and the proportion can reach more than 90%. The first screening and crushing coarsely and crush the large raw ore, and the particle size is relatively large compared with the subsequent screening and crushing. However, if the ore is crushed to a very small particle at one time, the crushing energy consumption and time will be greatly increased, thereby increasing the cost and being not conducive to industrial production. The above particle size control is not only conducive to saving the crushing energy consumption and time, but also can ensure that the subsequent mixing and pumping can be smoothly carried out.

[0058] The second screening particle size is 5-2 mm, the oversize material is subjected to the second crushing, and the crushing particle size is P90 between 5-2 mm. Through the second screening + crushing, the particle size of most of the material is controlled to be between 5-2 mm. Within this range, the material flow can achieve efficient decomposition.

[0059] Through three screening and three crushing, and each time the particle size is gradually reduced, the particle size is finally controlled below 1-0.85mm, and in this particle size range, the sylvite can be floated out. If one crushing is used, it is impossible to achieve this particle size, and by using three-stage crushing, the particle size of the raw material after the first crushing can be smoothly pumped after slurry preparation, without causing blockage, and this particle size control can save costs and time to the greatest extent, and the particle size control of the second crushing can achieve the most effective decomposition, and the third crushing can help achieve efficient flotation.

[0060] Specifically, the third crushing uses a rod mill for grinding, and before grinding, the material on the screen of the screening machine is collected through a chute, and mother liquor L1 is added in the chute, and the addition amount of the mother liquor L1 satisfies that the discharge concentration (solid-liquid mass percentage) of the rod mill is 45-60%, and the grinding time is 1.0-6.0 minutes.

[0061] S5, a flotation collector is added and coarse potassium flotation is carried out to obtain coarse potassium slurry S1 and tailings T1, and the coarse potassium slurry S1 is filtered to obtain coarse potassium filter cake K1 and mother liquor L1, and the tailings T1 are filtered to obtain T2 and mother liquor L1.

[0062] Since the washing mother liquor produced after washing in S5 is returned to the decomposition step, the single-pass yield of KCl is greatly improved. In the prior art, the washing mother liquor is generally transported to a salt field for salt field spreading to obtain KCl, and the decomposition yield of KCl is only about 70%. Through the reflux control of the present application, the decomposition yield of KCl can be increased to 119% (relative to the raw ore), because the KCl contained in the washing mother liquor is recovered and utilized. At the same time, the decomposition of the present application uses the washing mother liquor generated in the process as the liquid, and no water is used in the decomposition step, greatly reducing the water usage of the system and reducing the cost. + The recycling is carried out. At the same time, the liquid used in the decomposition of the present application is the washing mother liquor generated in the process, and no water is used in the decomposition step, greatly reducing the water usage of the system and reducing the cost.

[0063] S6, the underground primary sulfur-rich potassium-containing raw ore is subjected to multi-stage crushing to obtain a sulfur-rich potassium-containing mineral with a required particle size;

[0064] Specifically, in an embodiment, two-stage crushing or more than two-stage crushing can be used, and the particle size of the first-stage crushing is smaller than that of the second-stage crushing, and the final particle size of the last-stage crushing is 1mm-2mm. By using multi-stage crushing, the energy consumption and crushing time can be effectively saved compared with one-stage crushing. In addition, by controlling the particle size to be 1mm-2mm, better subsequent conversion can be achieved, and the cost is controlled within a reasonable range.

[0065] Specifically, the main components of the underground primary sulfur-rich potassium-containing raw ore are K + 8.0%-13.0%, Na + 8.0%-21.0%, Mg 2+ 5.0%-8.0%, Cl -23.0%~35.0%, SO4 2- 20.0%~31.0%.

[0066] S7, stirring the sulfur-rich potassium-containing mineral and seawater after mixing, the stirring time is 40 min~150 min, the conversion temperature is controlled at 35℃~50℃, to obtain a solid-liquid mixed ore pulp.

[0067] Specifically, in an embodiment, the mass ratio of the primary sulfur-rich potassium-containing raw ore and seawater is 1:0.45~0.75, K + When the concentration is higher, the required amount of seawater is higher, when K + When the concentration is lower, the required amount of seawater can be appropriately reduced, in any case, the mass ratio is controlled within the range of 1:0.45~0.75.

[0068] S8: The solid-liquid mixed ore pulp is adjusted to a flotation concentration with a leonite flotation mother liquor, and after adding and uniformly mixing a flotation reagent, leonite flotation is carried out, the dosage of the flotation reagent is 250 g / t of raw ore~500 g / t of raw ore, and the flotation reagent is an organic sodium salt aqueous solution produced after chlorination, sulfonation and saponification of heavy oil.

[0069] Specifically, the flotation is a closed circuit process of one roughing, one cleaning and middlings returning to roughing. The solid phase mass content in roughing is 25%~35%, and the solid phase mass content in cleaning is 10%~15%.

[0070] Specifically, the effective components of the organic sodium salt aqueous solution are petroleum sodium sulfonate with a carbon chain length of 12~16 and sodium chloride. The mass percentage content of petroleum sodium sulfonate in the flotation reagent is 24%-25%, and the mass percentage content of sodium chloride is ≤8%.

[0071] In the present application, the flotation reagent is an organic sodium salt aqueous solution produced after chlorination, sulfonation and saponification of heavy oil. The effective components of the organic sodium salt aqueous solution are petroleum sodium sulfonate with a carbon chain length of 12~16 and sodium chloride. The mass percentage content of petroleum sodium sulfonate in the flotation reagent is 24%-25%, and the mass percentage content of sodium chloride is ≤8%. Compared with directly using petroleum sodium sulfonate with a carbon chain length of 12~16 and sodium chloride pure substances to configure the flotation reagent or other flotation reagents, the effect cannot reach the flotation effect of the present application.

[0072] S9, the flotation froth obtained in the flotation is filtered and separated, the obtained solid is leonite concentrate, and the tailings obtained after concentration are discharged as high-concentration tailings, the flotation mother liquor produced by flotation filtration or concentration is partially returned to step S8 for slurry adjustment, and the excess part enters a salt field for evaporation concentration and grading and solarization of potassium-containing minerals and then returns to the processing system.

[0073] Specifically, through the above process and the selected reagent, the leonite flotation concentrate K+ The recovery rate is about 70%, and the flotation concentrate yield is between 42-51%.

[0074] S10, the crude potassium filter cake K1 and the kainite concentrate are mixed and stirred, the SOP mother liquor is added and stirred, and the slurry is filtered to obtain a washing mother liquor L Leo and a filter cake S2, the washing mother liquor L Leo Return to the previous carnallite and sylvinite decomposition step.

[0075] Specifically, in an embodiment, the mass ratio of the crude potassium filter cake K1 and the kainite concentrate is 1.0-1.6:1, which is fed into a stirring tank, the subsequent system obtains the SOP mother liquor, the amount of the SOP mother liquor is 2.2-3.2 times the mass of K1, and the slurry is obtained after being kept in the stirring tank for 30-60 minutes.

[0076] S11, the filter cake S2 is fed into a crystallizer, water with TDS / mg / L < 45000 and the SOP mother liquor, the temperature in the crystallizer is kept at 40-65°C, the crystallized slurry is filtered to obtain potassium sulfate wet material and the SOP mother liquor, and the SOP mother liquor is returned for use. Preferably, the water with TDS / mg / L < 45000 can be seawater, and in areas where fresh water resources are lacking, seawater can be directly used as process water, saving the investment cost of seawater desalination devices. The main use of the SOP mother liquor is to adjust the slurry, and if all water is used, the recovery rate will be greatly reduced. Therefore, the addition of seawater and the SOP mother liquor in crystallization not only saves water cost, but also improves the recovery rate. The mass ratio of seawater and the SOP mother liquor is 4:6-7:3. Preferably, it is 5:5.

[0077] Preferably, in an embodiment, the addition of seawater or the subsequent obtained SOP mother liquor adjusts the slurry concentration (mass percentage) to 35-45%. The addition amount of seawater or the subsequent obtained SOP mother liquor is 0.45-0.55 times S2 (calculated according to mass).

[0078] After the slurry is kept in the crystallizer for 1.5-2.5 hours, the slurry in the crystallizer is filtered to obtain potassium sulfate wet material and the SOP mother liquor, and the composition of the SOP mother liquor is K + 6.54-8.78%, Na + 1.33-3.71%, Mg 2+ 2.0-2.46%, Cl - 13.38-14.07%, SO4 2- 4.34-5.61%.

[0079] The SOP mother liquor is stored in a storage tank and returned to the previous system (used for the mixture of the crude potassium filter cake and the kainite concentrate in S10, and the crystallization liquid supplement in S11), and the excess mother liquor is fed into a salt field for mining. The composition of the potassium sulfate wet material is K+ 41.03%-42.74% Na + 0.15%-1.14% Mg 2+ 1.22%-2.08% Cl - 1.06-3.97% SO4 2- 46.43%-51.83%, the rest is water.

[0080] The application will be further described in connection with the following examples. The raw materials used in the implementation of the application are underground primary carnallite of a certain potash mine in Africa.

[0081] Example No. Ion composition of the raw ore (mass percentage %)

[0082] Example 1

[0083] (1) Collect the underground primary potassium-containing ore (carnallite) and S ore (sylvite) of a certain potash mine, and mix the two to obtain a mixed raw material in a mass ratio of 6:4.

[0084] (2) Screen the mixed raw material by first screening, with a screen size of 12.5 mm. The oversize material is first crushed to P90 of -12.5 mm.

[0085] (3) Add the crushed mixed material to a stirring tank containing a saturated solution to make a slurry. The mother liquor is composed of halite, KCl, and carnallite near the triple saturation point D of the Na + , K + , Mg 2+ / / Cl - , SO4 2- -H2O quinary salt metastable phase diagram, and 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%.

[0086] (4) Screen the slurry after the slurry is made, with a screen size of 2 mm. The oversize material is second crushed to P90 of -2 mm. The second crushed material and the undersize material of the second screening are transported to a decomposition tank,

[0087] (5) Add a washing mother liquor L Leo, the liquid addition amount is 35% of the raw material amount, and water is insufficient to supplement, the decomposition tank is provided with a flow guide cylinder, and under the action of the stirrer, the slurry flows in the flow guide cylinder in a closed loop from bottom to top P90, and the carnallite is decomposed in the upward flow state.

[0088] (6) After the slurry stays in the decomposition tank for 30 minutes to fully decompose the carnallite, the slurry is transported to a sieve with a mesh size of 0.85 mm for the third screening, and the sieve upper material is crushed for the third time by a rod mill, the grinding time is 5 minutes, and the grinding concentration (solid-liquid mass percentage) is 55%, and the material after the third crushing and the sieve underflow are transported to the flotation slurry tank together.

[0089] (7) The flotation collector is added in the flotation slurry tank, the slurry is transported to the flotation machine, and through flotation, the coarse potassium slurry S1 and the tailings T1 are obtained, the tailings T1 are transported to the tail salt yard, and the T2 and the mother liquor L1 are obtained by natural filtration, and the S1 is filtered to obtain the coarse potassium filter cake K1 and the mother liquor L1,

[0090] (8) Collecting the underground primary potassium-containing ore kai mine (sulfur-rich potassium-containing raw ore) of a certain potassium salt mine, and crushing it to P90 of-2 mm through multiple screening.

[0091] (9) The crushed raw ore and seawater are mixed and stirred at a mass ratio of 1:0.55, the stirring time is 150 min, and the decomposition temperature is controlled at 35°C, to obtain a decomposed solid-liquid mixed ore slurry;

[0092] (10) The solid-liquid mixed ore slurry is adjusted to a certain concentration with the kieserite flotation mother liquor, and after the flotation reagent is added and mixed, it is fed into the flotation machine for flotation. The flotation process is a closed circuit process of one roughing and one cleaning, and the middlings of the cleaning are returned to the roughing. The mass concentration of the roughing is 35%, and the concentration of the cleaning is 15%. The flotation reagent is an organic sodium salt aqueous solution produced by chlorination, sulfonation and saponification of heavy oil, and is only added in the roughing. The dosage of the reagent is 375 g / t of raw ore.

[0093] (11) The flotation froth obtained in the flotation is filtered and separated, and the obtained solid is the kieserite concentrate, and the chemical composition is K + 17.13%, Na + 1.320%, Mg 2+ 5.629%, Cl - 3.920%, SO4 2- 40.74%, and the tailings are concentrated to obtain high-concentration tailings for discharge. Part of the flotation mother liquor produced by filtering the concentrate and concentrating the tailings in the flotation is returned to step (10) for circulation; the excess part is evaporated and concentrated in the salt field, and the processed potassium-containing minerals are returned to the processing system.

[0094] (12) The crude potassium filter cake K1 obtained in step (7) and the potassium magnesium alum concentrate obtained in step (11) are mixed in a ratio of 1.44:1 and transported to a stirring tank. The SOP mother liquor is added to the subsequent system and the amount of SOP mother liquor is 2.78 times the mass of K1. After staying in the stirring tank for 45 minutes, a slurry is obtained. The slurry is filtered to obtain washing mother liquor L. Leo And filter cake S2. Washing mother liquor L Leo Store in a storage tank for later use.

[0095] (13) The filter cake S2 ​​is fed into the crystallizer. Seawater is added to the crystallizer at a rate of 0.55 times the mass of S2. If the amount is insufficient, the subsequent SOP mother liquor is added to adjust the slurry concentration to 42.05%. The temperature inside the crystallizer is maintained at 45°C. After the slurry has been kept in the crystallizer for 2 hours, it is filtered to obtain potassium sulfate wet material and SOP mother liquor. The composition of the SOP mother liquor is K + 7.78%, Na + 1.83%, Mg 2+ 2.46%, Cl - 13.88%, SO4 2- 4.34%.

[0096] SOP mother liquor is stored in a storage tank and returned to the system for use; excess mother liquor is transported to the salt field for ore drying. The wet potassium sulfate composition is K... + 41.03%, Na + 0.15%, Mg 2+ 2.08%, Cl - 3.97%, SO4 2- 46.43%.

[0097] Example 2

[0098] (1) Collect underground primary potassium-bearing minerals Car and S from a certain potassium salt mine and mix them in a mass ratio of 7:3 to obtain mixed raw materials.

[0099] (2) The mixed raw materials are screened for the first time with a particle size of 20mm. The material on the screen is crushed for the first time to P95-20m.

[0100] (3) Add the crushed mixture to a stirring tank containing a saturated solution for slurry preparation. The saturated mother liquor is prepared at 35°C using Na + K + Mg 2+ / / Cl - SO4 2- —The mother liquor composition near point D, the co-saturation point of the three-phase system of ezetene, KCl, and carnallite in the pentagonal hydrous salt metastable phase diagram of H2O, mainly consists of Na. +1. 59.1% K + 2. 69.0% Mg 2+ 6. 42.0% SO4 2- 4. 18.9% Cl - 19. 74.0%.

[0101] (4) The material after sizing is subjected to second screening with a particle size of 5 mm, the oversize is subjected to second crushing to P95-5 mm, and the second crushed material and undersize of the second screening are transported to a decomposition tank,

[0102] (5) A washing mother liquor L Leo is added to the decomposition tank, and the liquid addition amount is 35% of the amount of the raw material, and water is used to supplement the deficiency. The decomposition tank is provided with a draft tube, and under the action of the stirrer, the slurry flows in a closed loop from bottom to top in the draft tube, and the carnallite is decomposed in the upward flow state.

[0103] (6) After the slurry stays in the decomposition tank for 60 minutes to fully decompose the carnallite, the slurry is transported to a sieve with a mesh size of 0.85 mm for third screening, and the oversize is subjected to third crushing by a rod mill for 5 minutes, and the grinding concentration (solid-liquid mass percentage) is 55%. The third crushed material and undersize are transported together to a flotation sizing tank.

[0104] (7) A flotation collector is added to the flotation sizing tank, and the slurry is transported to a flotation machine to obtain a crude potassium slurry S1 and a tailings T1 by flotation. The tailings T1 are transported to a tail salt yard to obtain T2 and a mother liquor L1 by natural filtration, and the S1 is filtered to obtain a crude potassium filter cake K1 and a mother liquor L1,

[0105] (8) The underground primary potassium-containing ore kai mine of a certain potassium salt mine is subjected to multiple screening and crushing to -2 mm.

[0106] (9) The crushed raw ore and seawater are mixed at a mass ratio of 1:0.75 and stirred, the stirring time is 120 min, and the decomposition temperature is controlled at 40°C to obtain a decomposed solid-liquid mixed ore slurry;

[0107] (10) The solid-liquid mixed ore slurry is sized with a potassium magnesium sulfate flotation mother liquor, and after the flotation reagent is added and mixed, it is fed into a flotation machine for flotation. The flotation process is a closed circuit process of one roughing and one cleaning, and the roughing mass concentration is 30%, and the cleaning concentration is 12%. The flotation reagent is an organic sodium salt aqueous solution produced by chlorination, sulfonation and saponification of heavy oil, and is only added in roughing. The reagent dosage is 500 g / t of raw ore.

[0108] (11) Concentration and filtration: the flotation froth obtained by flotation is separated by filtration, and the obtained solid is a potassium magnesium sulfate concentrate, and the chemical composition is K +16.65% Na + 2.01% Mg 2+ 5.240% Cl - 2.555% SO4 2- 41.90%, retained; the high concentration tailings obtained after concentration are discharged. Part of the flotation mother liquor produced during flotation concentrate filtration and tailings concentration is returned to step (10) for recycling; the excess part is taken to the salt pan for evaporation concentration, grading and drying of the potassium-containing minerals before being returned to the processing system.

[0109] (12) The S1 obtained in step (7) and the kieserite concentrate obtained in step (11) are mixed in a ratio of 1.54:1 and transported to a stirred tank to obtain the SOP mother liquor after being added to the subsequent system. The amount of the SOP mother liquor is 2.78 times the mass of K1, and the slurry is obtained after being kept in the stirred tank for 45 minutes. The slurry is filtered to obtain the washing mother liquor L Leo and the filter cake S2. The washing mother liquor L Leo is stored in a storage tank for standby use.

[0110] (13) The filter cake S2 is transported to a crystallizer, seawater is added to the crystallizer, the amount of seawater added is 0.66 times the mass of S2, and the insufficient part is added to the subsequent SOP mother liquor to adjust the concentration of the mixed slurry to 42.05%. The temperature in the crystallizer is kept at 40°C, and the slurry in the crystallizer is filtered after being kept in the crystallizer for 2 hours to obtain potassium sulfate wet material and SOP mother liquor. The composition of the SOP mother liquor is: K + 7.96% Na + 1.62% Mg 2+ 2.41% Cl - 13.66% SO4 2- 4.48%. The SOP mother liquor is stored in a storage tank and returned to the system for use before being used, and the excess mother liquor is transported to the salt pan for mineral drying. The composition of the potassium sulfate wet material is K + 42.74% Na + 0.41% Mg 2+ 1.86% Cl - 1.41% SO4 2- 49.76%.

[0111] Example 3

[0112] (1) The underground primary potassium-containing minerals Car and S of a certain potash mine are collected and mixed to obtain a mixed raw material in a mass ratio of 8:2.

[0113] (2) The mixed raw material is subjected to first screening with a screening size of 12.5 mm, and the oversize is subjected to first crushing to P95 of -12.5 mm.

[0114] (3) the broken mixed material is added into a stirring tank containing saturated solution for slurry preparation, the saturated mother liquor is composed near the three-phase co-saturation point D of carnallite, KCl and sylvite in the quinary water-salt metastable phase diagram of Na + , K + , Mg 2+ / / Cl - , SO4 2- -H2O, the mass content of main components is Na + 1.591%, K + 2.069%, Mg 2+ 6.342%, SO4 2- 4.189%, Cl - 19.740%.

[0115] (4) the slurry after slurry preparation is subjected to second screening, the screening size is 5 mm, the oversize is subjected to second crushing, the crushing is to P95-2 mm, the second crushed material and undersize of the second screening are transported to a decomposition tank,

[0116] (5) washing mother liquor L Leo is added into the decomposition tank, the liquid addition amount is 40% of the raw material amount, water is used for supplement if insufficient, the decomposition tank is provided with a draft tube, under the action of a stirrer, the slurry is in a closed loop circulation flow from bottom to top in the draft tube, and carnallite is decomposed in the flow state in the upward stroke.

[0117] (6) after the slurry stays in the decomposition tank for 60 minutes to fully decompose the carnallite, the slurry is transported to a screen with a screen size of 0.85 mm for third screening, a grinding machine is used to crush the oversize, the grinding time is 5 minutes, and the grinding concentration (solid-liquid mass percentage) is 65%, the third crushed material and undersize are transported to a flotation slurry preparation tank together.

[0118] (7) a flotation collector is added into the flotation slurry preparation tank, the slurry is transported to a flotation machine, through flotation, a crude potassium slurry S1 and a tailing T1 are obtained, the tailing T1 is transported to a tail salt yard, and T2 and mother liquor L1 are obtained through natural filtration, K1 and mother liquor L1 are obtained after filtration of S1,

[0119] (8) the underground primary potassium-containing ore kai mine of a certain potassium salt mine is collected, and is subjected to multiple screening and crushing to-2 mm.

[0120] (9) the crushed raw ore and seawater are mixed according to a mass ratio of 1:0.45, and are stirred, the stirring time is 60 min, and the decomposition temperature is controlled at 45℃, to obtain a decomposed solid-liquid mixed slurry;

[0121] (10) The solid-liquid mixed ore slurry is adjusted in concentration by using the kainite flotation mother liquor, and after adding the flotation reagent and mixing, it is fed into the flotation machine for flotation. The flotation process is a closed circuit process of one roughing and one cleaning, wherein the mass concentration of roughing is 25%, and the concentration of cleaning is 10%. The flotation reagent is an organic sodium salt aqueous solution produced by chlorination, sulfonation and saponification of heavy oil, and is only added in roughing, with a dosage of 250 g / t of raw ore.

[0122] (11) The flotation froth obtained in the flotation is filtered and separated, and the obtained solid is kainite concentrate, which has a chemical composition of K + 16.74%, Na + 1.965%, Mg 2+ 5.247%, Cl - 2.139%, SO4 2- 42.51%. The tailings are concentrated, and the obtained high-concentration tailings are discharged. Part of the flotation mother liquor produced in the filtration of the concentrate and the concentration of the tailings in the flotation is returned to step (10) for circulation, and the excess part is fed into a salt field for evaporation and concentration, and then is returned to the processing system after being dried to contain potassium minerals.

[0123] (12) The S1 obtained in step (7) and the kainite concentrate obtained in step (11) are mixed in a ratio of 1.54:1, and are fed into a stirring tank. A subsequent system obtains an SOP mother liquor, and the amount of the SOP mother liquor is 2.78 times the mass of K1. After being kept in the stirring tank for 45 minutes, a slurry is obtained, and the slurry is filtered to obtain a washing mother liquor L Leo and a filter cake S2. The washing mother liquor L Leo is stored in a storage tank for standby use.

[0124] (13) The filter cake S2 is fed into a crystallizer, and seawater is added into the crystallizer. The amount of the seawater added is 0.80 times the mass of S2, and the insufficient part is mixed with the subsequent SOP mother liquor to adjust the concentration of the mixed slurry to 45%. The temperature in the crystallizer is kept at 65°C, and after being kept in the crystallizer for 2 hours, the slurry in the crystallizer is filtered to obtain a potassium sulfate wet material and an SOP mother liquor. The SOP mother liquor has a composition of K + 8.08%, Na + 1.61%, Mg 2+ 2.26%, Cl - 13.33%, SO4 2- 4.20%. The SOP mother liquor is stored in a storage tank, and is returned to the system before use. The excess mother liquor is fed into a salt field for drying. The potassium sulfate wet material has a composition of K + 41.37%, Na + 1.14%, Mg 2+ 1.22%, Cl - 1.06%, SO4 2- 51.83%.

[0125] In the method for preparing potassium sulfate by using underground primary sulfur-rich potassium-containing minerals, high-purity and high-yield KCl is first obtained. The high-quality coarse-grained potassium chloride product is extracted by combining the three-stage screening and three-stage crushing open-circuit crushing process and the cold decomposition-flotation-washing process, which reduces the grinding treatment capacity and improves the grinding efficiency. In addition, by gradually reducing the grinding particle size and combining the cold decomposition-flotation-washing process, the system yield is improved, and the defects of the traditional grinding-decomposition-flotation process for producing potassium chloride product particle size washing, high grinding energy consumption, etc. are changed. The purity of the obtained KCl is greater than or equal to 90%, and the decomposition yield of KCl reaches 119% (relative to the raw ore). Then, through the crushing-conversion-flotation and concentration filtration, the kainite product can be obtained, and the energy consumption and cost of the process are relatively low, and the product yield and quality are good. The Na + and Cl - removal rate reaches 88%, and the conversion rates of K + , Mg 2+ and SO4 2- reach 90%. Then, the KCl and kainite are reacted and crystallized to obtain the potassium sulfate product, and the purity of the obtained potassium sulfate is higher than 50%, and the yield is higher than 52.9%.

[0126] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "embodiment", "example", "specific example" or "some examples" and the like means 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 application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, different embodiments or examples described in the present specification and the features of different embodiments or examples can be combined and modified by those skilled in the art without contradiction.

[0127] Although the embodiments of the present application have been shown and described above, it should be understood that the above-described embodiments are exemplary and should not be construed as limiting the present application, and those skilled in the art can modify, modify, replace and change the above-described embodiments within the scope of the present application.

Claims

1. A method for producing potassium sulfate using a subsurface primary sulfur-rich potassium-bearing mineral, characterized by, The method comprises the following steps: The potassium chloride raw material and the potassium magnesium vanadium raw material are mixed and stirred, the SOP mother liquor is added and stirred, and the slurry is filtered to obtain a washing mother liquor L Leo and the filter cake S2; The filter cake S2 is transported into a crystallizer, water with TDS / mg / L < 45000 and SOP mother liquor are added, crystallization is carried out in the crystallizer, the temperature in the crystallizer is kept at 40-65℃, the crystallized slurry is filtered, and potassium sulfate wet material and filtrate are obtained, and the filtrate is returned to the use of the SOP mother liquor.

2. The method for producing potassium sulfate from underground primary sulfur-rich potassium-containing minerals according to claim 1, characterized in that, The potassium chloride raw material is obtained by the following method: The carnallite and sylvinite raw ore are mixed, and then first crushed to obtain a mixed raw material of carnallite and sylvinite, and the particle size of the mixed raw material is ≤20 mm, and the proportion is ≥90%; The mixed raw materials were added to a saturated mother liquor for mixing, and the saturated mother liquor was prepared by dissolving Na + , K + , Mg 2+ / / Cl - , SO4 2- -H2O quinary system at 35°C. The mother liquor composition of the three-phase co-saturation point D of halite, KCl, and carnallite in the metastable phase diagram of Na The slurried material is secondly crushed, and the secondly crushed material is decomposed; The decomposed slurry is thirdly crushed, and the thirdly crushed material is used for flotation; wherein the particle size of the thirdly crushed material is smaller than that of the secondly crushed material; A flotation collector is added, and coarse potassium flotation is carried out to obtain coarse potassium slurry S1 and tailings T1, the coarse potassium slurry S1 is filtered to obtain coarse potassium filter cake K1 and mother liquor L1, the tailings T1 is filtered to obtain T2 and mother liquor L1, and the obtained K1 is washed, filtered and dried to obtain potassium chloride products; Preferably, before the first crushing, the carnallite and sylvinite raw ore are mixed and once screened, and the screened upper and lower materials are combined to obtain the mixed raw material of carnallite and sylvinite; Before the second crushing, the slurried material is secondly screened, the screened upper material is secondly crushed, and the screened lower material of the second screening and the secondly crushed material are used for decomposition; Before the third crushing, the decomposed slurry is thirdly screened, the screened upper material is thirdly crushed, and the screened lower material of the third screening and the thirdly crushed material are used for flotation; wherein the particle size of the thirdly screened material is smaller than that of the secondly screened material.

3. The method of producing potassium sulfate using underground primary sulfur-rich potassium-bearing minerals according to claim 2, characterized in that, The potassium-magnesium-vanadium raw material is obtained by the following method: The collected underground primary sulfur-rich potassium-containing raw ore is multi-stage crushed to obtain a sulfur-rich potassium-containing mineral with a required particle size; The sulfur-rich potassium-containing mineral and seawater are mixed and stirred to convert at a temperature of 35-50℃ to obtain a solid-liquid mixed ore slurry; The solid-liquid mixed ore slurry is slurried with a kainite flotation mother liquor, and after the flotation reagent is added and uniformly mixed, kainite flotation is carried out, and the flotation reagent is an organic sodium salt aqueous solution produced by chlorination, sulfonation and saponification of heavy oil; The flotation froth obtained in the flotation is filtered and separated, and the obtained solid is kainite concentrate, and part of the flotation mother liquor produced in the flotation is returned to the previous slurry preparation step.

4. The method of claim 2, wherein the underground primary sulfur-rich potassium-bearing mineral is sylvite. The first screening particle size is 20-12.5 mm, the screened upper material is crushed, and the crushing particle size is P90 between 20-12.5 mm; the second screening particle size is 5-2 mm, the screened upper material is secondly crushed, and the crushing particle size is P90 between 5-2 mm, and the third screening particle size is 1-0.85 mm, the screened upper material is crushed, and the crushing particle size is P90 between 1-0.85 mm.

5. The method of claim 3, wherein the underground primary sulfur-rich potassium-bearing mineral is sylvite. The halite ore is a natural solid halite ore containing sodium chloride, sylvite mineral; the sylvinite ore is a natural solid sylvinite ore containing sodium chloride, langbeinite and gypsum mineral, the main components of the underground primary sulfur-rich potassium-containing raw ore are K + 8.0%~13.0%, Na + 8.0%~21.0%, Mg 2+ 5.0%~8.0%, Cl - 23.0%~35.0%, SO4 2- 20.0%~31.0%. ​ 6. The method of claim 3, wherein the underground primary sulfur-rich potassium-bearing mineral is sylvite. The effective components of the organic sodium salt aqueous solution are petroleum sodium sulfonate with a carbon chain length of 12-16 and sodium chloride, the mass percentage of the petroleum sodium sulfonate in the flotation reagent is 24%-25%, and the mass percentage of the sodium chloride is ≤8%.

7. The method of claim 2, wherein the underground primary sulfur-rich potassium-bearing mineral is sylvite. The decomposition is carried out in a decomposition tank provided with a draft tube, under the action of a stirrer, the slurry is in a closed loop circulation flow state from bottom to top in the draft tube, and the carnallite decomposition is carried out in the upward flow state, and the slurry stays in the decomposition tank for 30-120 minutes; Preferably, when the decomposition is carried out in the decomposition tank, a washing mother liquor is added into the decomposition tank, and the addition amount of the washing mother liquor is 30-45% of the total mass of the raw ore.

8. The method of producing potassium sulfate using underground primary sulfur-rich potassium-bearing minerals according to claim 7, characterized in that, The mass content of 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%; The mass content of main components 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%。 9. The method of claim 3, wherein the underground primary sulfur-rich potassium-bearing mineral is sylvite. The carnallite flotation is a closed circuit process of one roughing, one cleaning and returning the cleaning middlings to the roughing, wherein the solid phase mass content in the roughing is 25-35%, and the solid phase mass content in the cleaning is 10-15%.

10. The method of claim 2, wherein the underground primary sulfur-rich potassium-bearing mineral is sylvite. The third crushing adopts a rod mill for grinding, the oversize material is collected through a chute, a mother liquor L1 is added into the chute, the addition amount of the 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.

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