Method for preparing reagent potassium sulfate from salt lake source agricultural potassium sulfate

Abstract

The invention discloses a method for preparing reagent potassium sulfate from salt lake source agricultural potassium sulfate, which comprises the following steps: S1, adding a part of solvent into a reactor, slowly adding the salt lake source agricultural potassium sulfate while stirring, slowly adding AR sulfuric acid, and adding the rest of solvent; s2, extracting supernatant liquid in the storage container, spin-drying residual materials in the storage container in a rubber coating spin-drying machine, and leaching and spin-drying; s3, taking a part of the potassium sulfate primary product, adding a part of pure water into another reaction kettle, adding the potassium sulfate primary product, heating to 70-80 DEG C, and supplementing the remaining pure water; s4, adding AR potassium persulfate, activated carbon and pH, concentrating under reduced pressure, cooling to normal temperature, crystallizing, and dehydrating on a centrifugal machine; and S5, drying the potassium sulfate wet product. According to the method, the reagent potassium sulfate can be prepared from the salt lake source agricultural potassium sulfate purchased from the market.

Description

Technical Field

[0001] The invention relates to reagent production, in particular to a method for preparing reagent potassium sulfate from salt lake source agricultural potassium sulfate. Background Art

[0002] Potassium sulfate is a salt composed of sulfate ions and potassium ions. It is usually colorless or white crystals, granules or powder. It is odorless and bitter. It is hard. It is chemically inactive. It is stable in the air. The density is 2.66g / cm. The melting point is 1069℃. The aqueous solution is neutral, and the pH is about 7 at room temperature. 1g is soluble in 8.3ml water, 4ml boiling water, and 75ml glycerol, and is insoluble in ethanol. Potassium sulfate is the basic raw material for making various potassium salts such as potassium carbonate and potassium persulfate. It is used as a precipitant in the glass industry. It is used as an intermediate in the dye industry. It is used as an auxiliary agent in the fragrance industry. It is also used as a laxative in the pharmaceutical industry. Potassium sulfate is a commonly used potassium fertilizer in agriculture, with a potassium content of about 50%. In addition, potassium sulfate is also used in glass, dyes, fragrances, medicines, etc. in industry.

[0003] Most of the agricultural potassium sulfate currently sold on the market is made from seawater or salt lakes.

[0004] 20406-2017 Agricultural Potassium Sulfate stipulates that the first-class requirements are:

[0005] K2O ≥ 50.0%;

[0006] Cl - ≤1.5%;

[0007] Na + No requirements.

[0008] The reagent potassium sulfate (AR) requires (GB / T16496-1996): Cl - ≤0.0005%,Na + ≤0.03%, compared with reagent potassium sulfate (AR), agricultural potassium sulfate from salt lake source Cl - Content is reagent potassium sulfate (AR) Cl - The content is about 3000 times that of salt lake source agricultural potassium sulfate Na + Content is reagent potassium sulfate (AR) Na + The content is about 33 times (agricultural potassium sulfate Na + Content is about 1%), so how to reduce Cl in the preparation of reagent potassium sulfate (AR) from salt lake source agricultural potassium sulfate? - And Na + Content has become a difficulty in the industry.

[0009] The common practice of existing reagent production is to retain chloride and sodium in the mother liquor (recrystallization), so as to ensure that the chloride and sodium of the crystallized product meet the quality requirements of the reagent, but this method can usually only process raw materials with impurities 3-5 times that of the reagent, and the finished product yield can only reach about 80%. For processing raw materials with impurities exceeding 3-5 times that of the reagent, the method of foaming is generally adopted to remove, but only raw materials with impurities exceeding several dozen times that of the reagent can be processed, and the loss of foaming material makes the finished product yield far less than 80%. The precipitate of chloride is very small, such as silver chloride. Silver chloride can be used to precipitate chloride in valuable products, but the production of reagent potassium sulfate is obviously inappropriate using this method.

[0010] The existing methods are not suitable for preparing reagent potassium sulfate (AR) from salt lake source agricultural potassium sulfate.

[0011] The above background technology is for facilitating the understanding of the present invention and is not a known technology disclosed to the general public before the application of the present invention. Summary of the invention

[0012] In view of the above defects, the present invention provides a method for preparing reagent potassium sulfate from salt lake source agricultural potassium sulfate, which prepares reagent potassium sulfate from salt lake source agricultural potassium sulfate purchased from the market, has simple process engineering, low cost and high yield.

[0013] The technical solution is: a method for preparing reagent potassium sulfate from salt lake source agricultural potassium sulfate, comprising the following steps:

[0014] S1, add a part of the solvent to the reactor, slowly add salt lake source agricultural potassium sulfate under stirring, then slowly add AR sulfuric acid, add the remaining solvent, boil and keep for 3-8h, and discharge into a storage container;

[0015] S2, extracting the supernatant in the storage container, drying the remaining material in the storage container in a plastic coating drying machine, rinsing and drying, and obtaining a primary potassium sulfate product;

[0016] S3, take part of the potassium sulfate product in S2, add a part of pure water into another reaction kettle, slowly add the potassium sulfate product under stirring, heat to 70-80°C, add the remaining amount of pure water, so that the potassium sulfate product is completely dissolved to form a solution;

[0017] S4, adding AR potassium persulfate and activated carbon to the solution of S3, adjusting the pH with AR potassium hydroxide and / or AR sulfuric acid, concentrating under reduced pressure, cooling to room temperature, crystallizing, and dehydrating on a centrifuge to obtain wet potassium sulfate;

[0018] S5, drying the wet potassium sulfate to obtain reagent potassium sulfate;

[0019] In S1, the mass ratio of agricultural potassium sulfate: AR sulfuric acid: solvent is 800-1500: 150-250: 1500-2500, and a portion of the solvent is 60%-90% of the total solvent; in S3-S4, the mass ratio of primary potassium sulfate: AR potassium persulfate: activated carbon: pure water is 400-600: 1-5: 1: 2500-3500, and a portion of the pure water is 50%-90% of the total pure water.

[0020] Further, S4 includes the following steps:

[0021] S41, add AR potassium persulfate to the solution of S3, continue stirring, adjust the pH to ≥ 10.0 with AR potassium hydroxide, add AR potassium carbonate, continue stirring, add activated carbon, turn off stirring, and keep warm and let stand;

[0022] S42, filter the solution of S41, adjust the pH of the filtrate to 6.0-7.0 with AR sulfuric acid, heat and boil, adjust the pH of the filtrate to 6.0-7.0 with AR sulfuric acid, and concentrate under reduced pressure to half the volume of the solution until a large amount of crystals are produced, then finish the concentration, cool to room temperature, crystallize, and dehydrate on a centrifuge to obtain wet potassium sulfate;

[0023] Among them, the mass ratio of AR potassium carbonate: potassium sulfate is 5-15:400-600.

[0024] Further, S4 includes the following steps:

[0025] S41, adjust the pH value of the solution in S3 to ≥ 10.0 with AR potassium hydroxide, add AR potassium carbonate, continue stirring, add activated carbon, turn off stirring, and keep warm and let stand;

[0026] S42, filter the solution of S41, adjust the pH of the filtrate to 6.0-7.0 with AR sulfuric acid, add AR potassium persulfate, heat and boil, adjust the pH of the filtrate to 6.0-7.0 with AR sulfuric acid, and concentrate under reduced pressure to half the volume of the solution until a large amount of crystals are produced, then finish the concentration, cool to room temperature, crystallize, and dehydrate on a centrifuge to obtain wet potassium sulfate;

[0027] Among them, the mass ratio of AR potassium carbonate: potassium sulfate is 5-15:400-600.

[0028] Further, S4 includes the following steps:

[0029] S41, add a portion of AR potassium persulfate to the solution of S3, continue stirring, adjust the pH to ≥ 10.0 with AR potassium hydroxide, add activated carbon, turn off stirring, and keep warm and let stand;

[0030] S42, filter the solution of S41, adjust the pH of the filtrate to 6.0-7.0 with AR sulfuric acid, add the remaining amount of AR potassium persulfate, heat and boil, adjust the pH of the filtrate to 6.0-7.0 with AR sulfuric acid, and concentrate under reduced pressure to half the volume of the solution until a large amount of crystals are produced, then end the concentration, cool to room temperature, crystallize, and dehydrate on a centrifuge to obtain a wet potassium sulfate product;

[0031] The part of AR potassium persulfate is 50% to 80% of the total amount of AR potassium persulfate.

[0032] Further, S4 includes the following steps:

[0033] S41, add a portion of AR potassium persulfate to the solution in S3, continue stirring, adjust the pH to ≥ 10.0 with AR potassium hydroxide, add AR potassium carbonate, continue stirring, add activated carbon, turn off stirring, and keep warm and let stand for more than 4 hours.

[0034] S42, filter the solution of S41, adjust the pH of the filtrate to 6.0-7.0 with AR sulfuric acid, add the remaining amount of AR potassium persulfate, heat and boil, adjust the pH of the filtrate to 6.0-7.0 with AR sulfuric acid, and concentrate under reduced pressure to half the volume of the solution until a large amount of crystals are produced, then end the concentration, cool to room temperature, crystallize, and dehydrate on a centrifuge to obtain a wet potassium sulfate product;

[0035] The mass ratio of AR potassium carbonate to potassium sulfate is 5-15:400-600, and the part of AR potassium persulfate is 50%-80% of the total amount of AR potassium persulfate.

[0036] Furthermore, in S1, the solvent is pure water.

[0037] Furthermore, in S1, the supernatant liquid, the spin liquid generated by the spin dryer and the spray liquid formed by elution are recycled. During the recycling, the newly generated supernatant liquid is not enriched with chloride ions.

[0038] Furthermore, in S1, the solvent is a mixture of the supernatant produced in the previous production process, the spin liquid produced by the spin dryer, and the spray liquid formed by elution.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The present invention utilizes the acidity of potassium hydrogen sulfate formed by sulfuric acid and potassium sulfate to volatilize chloride and acid to form hydrogen chloride, thereby preventing chloride from accumulating in the solution. Therefore, the addition of sulfuric acid not only drives away the potassium sulfate crystals from which chlorine and sodium leave during crystallization, but also prevents the accumulation of chloride in the solution, so that the mother liquor chloride ions are not enriched and can be recycled. According to the production characteristics of salt lake source agricultural potassium sulfate, the present invention also adds potassium persulfate in the subsequent purification process to oxidize low-priced metals into high-priced substances, and utilizes the strong oxidizing property of potassium persulfate to oxidize organic matter. The present invention also utilizes the double decomposition of potassium carbonate to remove sodium ions. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram of the process route of the present invention. DETAILED DESCRIPTION

[0042] As used herein:

[0043] "Prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0044] The conjunction "consisting of excludes any unspecified element, step, or component. If used in a claim, this phrase renders the claim closed-ended so that it does not include materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim rather than immediately following the subject matter, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0045] When an amount, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed separately. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described in this article, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range.

[0046] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] Those skilled in the art will appreciate that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. If specific conditions are not specified in the examples, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0048] In these examples, parts and percentages are by mass unless otherwise indicated.

[0049] "Parts by mass" refers to the basic unit of measurement for expressing the mass ratio of multiple components. 1 part can represent any unit mass, such as 1g or 2.689g. If we say that the mass of component A is a parts and the mass of component B is b parts, it means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it means that the mass of component A is aK and the mass of component B is bK (K is an arbitrary number, indicating a multiple factor). It should not be misunderstood that, unlike the mass parts, the sum of the mass of all components is not limited to 100 parts.

[0050] "And / or" is used to indicate that one or both of the stated situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0051] The production process of preparing reagent potassium sulfate from salt lake source agricultural potassium sulfate is as follows: Figure 1 .

[0052] In the following examples, the salt lake source agricultural potassium sulfate (first-class product) has a purity of 93.16%, Cl - The content is 0.9%, Na + The content is about 1%.

[0053] Example 1

[0054] A method for preparing reagent potassium sulfate from salt lake source agricultural potassium sulfate comprises the following steps:

[0055] S1, add 1500-1800L pure water to a 2000L enamel reactor, slowly add 1000Kg of salt lake source agricultural potassium sulfate under stirring, then slowly add 190Kg of AR sulfuric acid, add pure water to 2000L, boil and keep for 5-6h, and discharge the materials into a barrel.

[0056] S2, the supernatant liquid (mother liquor) in the barrel is removed, crystallized, dried in an SS800 encapsulated drying machine, rinsed and dried, and a primary potassium sulfate product is obtained. The yield of the primary potassium sulfate product is as shown in Table 1. The Cl content in the primary potassium sulfate product is detected. - And Na + Content, the results are shown in Table 1, Cl in the mother liquor was detected - The results are shown in Table 1 below.

[0057] S3, add 2000-2500L of pure water into a 3000L stainless steel reactor, slowly add 450Kg of S2 potassium sulfate under stirring, heat to 70-80℃, add pure water to 3000L, and dissolve all the potassium sulfate.

[0058] S4, purification, comprises the following steps:

[0059] S41, add 1.0 kg of AR potassium persulfate to the solution in S3, continue stirring for 30 min, adjust the pH to ≥ 10.0 with AR potassium hydroxide, add 8 kg of AR potassium carbonate, continue stirring for 30 min, add 1 kg of activated carbon, turn off stirring, and keep warm and let stand for more than 4 h.

[0060] S42, filter the solution of S41 into a 5000L stainless steel reactor, adjust the pH to 6.0-7.0 with AR sulfuric acid, add 0.5Kg of AR potassium persulfate, heat and boil, and adjust the pH to 6.0-7.0 with AR sulfuric acid, and concentrate under reduced pressure to half the volume of the solution until a large amount of crystals are produced. Then, the concentration is completed, cooled to room temperature, crystallized, and dehydrated on a centrifuge to obtain wet potassium sulfate.

[0061] S5, the wet potassium sulfate was dried on a rotary drum at 90°C for 2 hours to obtain analytically pure potassium sulfate. The yield is shown in Table 1. The Cl in analytically pure potassium sulfate was detected. - And Na + The results are shown in Table 1 below.

[0062] S6, packaging and storage.

[0063] Example 2

[0064] A method for preparing reagent potassium sulfate from salt lake source agricultural potassium sulfate comprises the following steps:

[0065] S1, add 1500-1800L pure water to a 2000L enamel reactor, slowly add 1100Kg of salt lake source agricultural potassium sulfate under stirring, then slowly add 190Kg of AR sulfuric acid, add pure water to 2000L, boil and keep for 5-6h, and discharge into a barrel.

[0066] S2, the supernatant liquid (mother liquor) in the barrel is removed, crystallized, dried in an SS800 encapsulated drying machine, rinsed and dried, and a primary potassium sulfate product is obtained. The yield of the primary potassium sulfate product is as shown in Table 1. The Cl content in the primary potassium sulfate product is detected. - And Na + Content, the results are shown in Table 1, Cl in the mother liquor was detected - The results are shown in Table 1 below.

[0067] S3, add 2000-2500L of pure water into a 3000L stainless steel reactor, slowly add 500Kg of potassium sulfate from S2 under stirring, heat to 70-80℃, add pure water to 3000L, and dissolve all the potassium sulfate.

[0068] S4, purification, comprises the following steps:

[0069] S41, add 1.5 kg of AR potassium persulfate to the solution in S3, continue stirring for 30 min, adjust the pH to ≥ 10.0 with AR potassium hydroxide, add 8 kg of AR potassium carbonate, continue stirring for 30 min, add 1 kg of activated carbon, turn off stirring, and keep warm and let stand for more than 4 h.

[0070] S42, filter the solution of S41 into a 5000L stainless steel reactor, adjust the pH to 6.0-7.0 with AR sulfuric acid, add 1.0Kg of AR potassium persulfate, heat and boil, and adjust the pH to 6.0-7.0 with AR sulfuric acid, and concentrate under reduced pressure to half the volume of the solution until a large amount of crystals are produced. Then, the concentration is completed, cooled to room temperature, crystallized, and dehydrated on a centrifuge to obtain wet potassium sulfate.

[0071] S5, the wet potassium sulfate was dried on a rotary drum at 90°C for 2 hours to obtain analytically pure potassium sulfate. The yield is shown in Table 1. The Cl in analytically pure potassium sulfate was detected. - And Na + The results are shown in Table 1 below.

[0072] S6, packaging and storage.

[0073] Example 3

[0074] A method for preparing reagent potassium sulfate from salt lake source agricultural potassium sulfate comprises the following steps:

[0075] S1, add 1500-1800L pure water to a 2000L enamel reactor, slowly add 1100Kg of salt lake source agricultural potassium sulfate under stirring, then slowly add 190Kg of AR sulfuric acid, add pure water to 2000L, boil and keep for 5-6h, and discharge into a barrel.

[0076] S2, the supernatant liquid (mother liquor) in the barrel is removed, crystallized, dried in an SS800 encapsulated drying machine, rinsed and dried, and a primary potassium sulfate product is obtained. The yield of the primary potassium sulfate product is as shown in Table 1. The Cl content in the primary potassium sulfate product is detected. - And Na + Content, the results are shown in Table 1, Cl in the mother liquor was detected - The results are shown in Table 1 below.

[0077] S3, add 2000-2500 kg of pure water into a 3000 L stainless steel reactor, slowly add 500 kg of potassium sulfate from S2 under stirring, heat to 70-80 °C, add pure water to 3000 L, and dissolve all the potassium sulfate.

[0078] S4, purification, comprises the following steps:

[0079] S41, add 1.0 kg of AR potassium persulfate to the solution in S3, continue stirring for 30 min, adjust the pH to ≥ 10.0 with AR potassium hydroxide, add 8 kg of AR potassium carbonate, continue stirring for 30 min, add 1 kg of activated carbon, turn off stirring, and keep warm and let stand for more than 4 h.

[0080] S42, filter the solution of S41 into a 5000L stainless steel reactor, adjust the pH to 6.0-7.0 with AR sulfuric acid, add 0.5Kg of AR potassium persulfate, heat and boil, and adjust the pH to 6.0-7.0 with AR sulfuric acid, and concentrate under reduced pressure to half the volume of the solution until a large amount of crystals are produced. Then, the concentration is completed, cooled to room temperature, crystallized, and dehydrated on a centrifuge to obtain wet potassium sulfate.

[0081] S5, the wet potassium sulfate was dried on a rotary drum at 90°C for 2 hours to obtain analytically pure potassium sulfate. The yield is shown in Table 1. The Cl in analytically pure potassium sulfate was detected. - And Na + The results are shown in Table 1 below.

[0082] S6, packaging and storage.

[0083] Example 4

[0084] A method for preparing reagent potassium sulfate from salt lake source agricultural potassium sulfate comprises the following steps:

[0085] S1, add 1500-1800L pure water to a 2000L enamel reactor, slowly add 1000Kg of salt lake source agricultural potassium sulfate under stirring, then slowly add 190Kg of AR sulfuric acid, add pure water to 2000L, boil and keep for 5-6h, and discharge the materials into a barrel.

[0086] S2, the supernatant liquid (mother liquor) in the barrel is removed, crystallized, dried in an SS800 encapsulated drying machine, rinsed and dried, and a primary potassium sulfate product is obtained. The yield of the primary potassium sulfate product is as shown in Table 1. The Cl content in the primary potassium sulfate product is detected. - And Na + Content, the results are shown in Table 1, Cl in the mother liquor was detected - The results are shown in Table 1 below.

[0087] S3, add 2000-2500L of pure water into a 3000L stainless steel reactor, slowly add 450Kg of S2 potassium sulfate under stirring, heat to 70-80℃, add pure water to 3000L, and dissolve all the potassium sulfate.

[0088] S4, purification, comprises the following steps:

[0089] S41, add 1.5 kg of AR potassium persulfate to the solution in S3, continue stirring for 30 min, adjust the pH to ≥ 10.0 with AR potassium hydroxide, add 8 kg of AR potassium carbonate, continue stirring for 30 min, add 1 kg of activated carbon, turn off stirring, and keep warm and let stand for more than 4 h.

[0090] S42, filter the solution of S41 into a 5000L stainless steel reactor, adjust the pH to 6.0-7.0 with AR sulfuric acid, heat and boil, and adjust the pH to 6.0-7.0 with AR sulfuric acid, and concentrate under reduced pressure to half the volume of the solution until a large amount of crystals are produced. Then, the concentration is completed, cooled to room temperature, crystallized, and dehydrated on a centrifuge to obtain wet potassium sulfate.

[0091] S5, the wet potassium sulfate was dried on a rotary drum at 90°C for 2 hours to obtain analytically pure potassium sulfate. The yield is shown in Table 1. The Cl in analytically pure potassium sulfate was detected. - And Na + The results are shown in Table 1 below.

[0092] S6, packaging and storage.

[0093] Example 5

[0094] A method for preparing reagent potassium sulfate from salt lake source agricultural potassium sulfate comprises the following steps:

[0095] S1, add 1500-1800L pure water to a 2000L enamel reactor, slowly add 1000Kg of salt lake source agricultural potassium sulfate under stirring, then slowly add 190Kg of AR sulfuric acid, add pure water to 2000L, boil and keep for 5-6h, and discharge the materials into a barrel.

[0096] S2, the supernatant liquid (mother liquor) in the barrel is removed, crystallized, dried in an SS800 encapsulated drying machine, rinsed and dried, and a primary potassium sulfate product is obtained. The yield of the primary potassium sulfate product is as shown in Table 1. The Cl content in the primary potassium sulfate product is detected.- And Na + Content, the results are shown in Table 1, Cl in the mother liquor was detected - The results are shown in Table 1 below.

[0097] S3, add 2000-2500L of pure water into a 3000L stainless steel reactor, slowly add 450Kg of S2 potassium sulfate under stirring, heat to 70-80℃, add pure water to 3000L, and dissolve all the potassium sulfate.

[0098] S4, purification, comprises the following steps:

[0099] S41, adjust the pH value of the solution in S3 to ≥ 10.0 with AR potassium hydroxide, add 8 kg of AR potassium carbonate, continue stirring for 30 min, add 1 kg of activated carbon, turn off stirring, and keep warm and let stand for more than 4 h.

[0100] S42, filter the solution of S41 into a 5000L stainless steel reactor, adjust the pH to 6.0-7.0 with AR sulfuric acid, add 1.5Kg of AR potassium persulfate, heat and boil, and adjust the pH to 6.0-7.0 with AR sulfuric acid, and concentrate under reduced pressure to half the volume of the solution until a large amount of crystals are produced. Then, the concentration is completed, cooled to room temperature, crystallized, and dehydrated on a centrifuge to obtain wet potassium sulfate.

[0101] S5, dry the wet potassium sulfate product on a rotary drum at 90°C for 2 hours to obtain reagent potassium sulfate. The yield is as shown in Table 1. Detect Cl in the reagent potassium sulfate - And Na + The results are shown in Table 1 below.

[0102] S6, packaging and storage.

[0103] Example 6

[0104] A method for preparing reagent potassium sulfate from salt lake source agricultural potassium sulfate comprises the following steps:

[0105] S1, add 1500-1800L pure water to a 2000L enamel reactor, slowly add 1000Kg of salt lake source agricultural potassium sulfate under stirring, then slowly add 190Kg of AR sulfuric acid, add pure water to 2000L, boil and keep for 5-6h, and discharge the materials into a barrel.

[0106] S2, the supernatant liquid (mother liquor) in the barrel is removed, crystallized, dried in an SS800 encapsulated drying machine, rinsed and dried, and a primary potassium sulfate product is obtained. The yield of the primary potassium sulfate product is as shown in Table 1. The Cl content in the primary potassium sulfate product is detected. - And Na + Content, the results are shown in Table 1, Cl in the mother liquor was detected - The results are shown in Table 1 below.

[0107] S3, add 2000-2500L of pure water into a 3000L stainless steel reactor, slowly add 450Kg of S2 potassium sulfate under stirring, heat to 70-80℃, add pure water to 3000L, and dissolve all the potassium sulfate.

[0108] S4, purification, comprises the following steps:

[0109] S41, add 1.0 kg of AR potassium persulfate to the solution in S3, continue stirring for 30 min, adjust the pH to ≥ 10.0 with AR potassium hydroxide, add 1 kg of activated carbon, turn off stirring, and keep warm and let stand for more than 4 h.

[0110] S42, filter the solution of S41 into a 5000L stainless steel reactor, adjust the pH to 6.0-7.0 with AR sulfuric acid, add 0.5Kg of AR potassium persulfate, heat and boil, and adjust the pH to 6.0-7.0 with AR sulfuric acid, and concentrate under reduced pressure to half the volume of the solution until a large amount of crystals are produced. Then, the concentration is completed, cooled to room temperature, crystallized, and dehydrated on a centrifuge to obtain wet potassium sulfate.

[0111] S5, dry the wet potassium sulfate product on a rotary drum at 90°C for 2 hours to obtain reagent potassium sulfate. The yield is as shown in Table 1. Detect Cl in the reagent potassium sulfate - And Na + The results are shown in Table 1 below.

[0112] S6, packaging and storage.

[0113] Example 7

[0114] A method for preparing reagent potassium sulfate from salt lake source agricultural potassium sulfate comprises the following steps:

[0115] S0, take the mother liquor of Example 1S2, the spin liquid produced by the spin dryer of Example 1S2 and the spray liquid formed by the elution of Example 1S2, and mix them to form a mixed liquid.

[0116] S1, add 1500-1800L of S0 mixed solution into a 2000L enamel reactor, slowly add 1000Kg of salt lake source agricultural potassium sulfate under stirring, add S0 mixed solution to 2000L, boil and keep for 5-6h, and discharge into a barrel.

[0117] S2, the supernatant in the barrel (new mother liquor) was removed, crystallized, dried in SS800 encapsulated drying machine, rinsed and dried, and potassium sulfate was obtained. The yield of potassium sulfate was as shown in Table 1. Cl in potassium sulfate was detected. - And Na + Content, the results are shown in Table 1, Cl in the mother liquor was detected - The results are shown in Table 1 below.

[0118] S3, add 2000-2500L of pure water into a 3000L stainless steel reactor, slowly add 450Kg of S2 potassium sulfate under stirring, heat to 70-80℃, add pure water to 3000L, and dissolve all the potassium sulfate.

[0119] S4, purification, comprises the following steps:

[0120] S41, add 1.0 kg of AR potassium persulfate to the solution in S3, continue stirring for 30 min, adjust the pH to ≥ 10.0 with AR potassium hydroxide, add 8 kg of AR potassium carbonate, continue stirring for 30 min, add 1 kg of activated carbon, turn off stirring, and keep warm and let stand for more than 4 h.

[0121] S42, filter the solution of S41 into a 5000L stainless steel reactor, adjust the pH to 6.0-7.0 with AR sulfuric acid, add 0.5Kg of AR potassium persulfate, heat and boil, and adjust the pH to 6.0-7.0 with AR sulfuric acid, and concentrate under reduced pressure to half the volume of the solution until a large amount of crystals are produced. Then, the concentration is completed, cooled to room temperature, crystallized, and dehydrated on a centrifuge to obtain wet potassium sulfate.

[0122] S5, the wet potassium sulfate was dried on a rotary drum at 90°C for 2 hours to obtain analytically pure potassium sulfate. The yield is shown in Table 1. The Cl in analytically pure potassium sulfate was detected. - And Na + The results are shown in Table 1 below.

[0123] S6, packaging and storage.

[0124] Comparative Example 1

[0125] A method for preparing pure potassium sulfate from salt lake source agricultural potassium sulfate comprises the following steps:

[0126] S1, add 1500-1800L pure water to a 2000L enamel reactor, slowly add 1000Kg of salt lake source agricultural potassium sulfate under stirring, then slowly add 190Kg of AR nitric acid, add pure water to 2000L, boil and keep for 5-6h, and discharge into a barrel.

[0127] S2, the supernatant liquid (mother liquor) in the barrel is removed, crystallized, dried in an SS800 encapsulated drying machine, rinsed and dried, and a primary potassium sulfate product is obtained. The yield of the primary potassium sulfate product is as shown in Table 1. The Cl content in the primary potassium sulfate product is detected. - And Na + Content, the results are shown in Table 1, Cl in the mother liquor was detected - The results are shown in Table 1 below.

[0128] S3, add 2000-2500L of pure water into a 3000L stainless steel reactor, slowly add 450Kg of S2 potassium sulfate under stirring, heat to 70-80℃, add pure water to 3000L, and dissolve all the potassium sulfate.

[0129] S4, add 1.0 kg of AR potassium persulfate to the solution of S3, continue stirring for 30 min, adjust the pH to ≥ 10.0 with AR potassium hydroxide, add 8 kg of AR potassium carbonate, continue stirring for 30 min, add 1 kg of activated carbon, turn off stirring, and keep warm and let stand for more than 4 hours.

[0130] S5, filter the solution of S4 into a 5000L stainless steel reactor, adjust the pH to 6.0-7.0 with AR sulfuric acid, add 0.5Kg of AR potassium persulfate, heat and boil, and adjust the pH to 6.0-7.0 with AR sulfuric acid, and concentrate under reduced pressure to half the volume of the solution until a large amount of crystals are produced. Then, the concentration is completed, cooled to room temperature, crystallized, and dehydrated on a centrifuge to obtain wet potassium sulfate.

[0131] S5, drying the wet potassium sulfate product on a rotary drum at 90°C for 2 hours to obtain potassium sulfate product. The yield is as shown in Table 1. The Cl in the potassium sulfate product is detected. - And Na + The results are shown in Table 1 below.

[0132] S6, packaging and storage.

[0133] Table 1

[0134]

[0135] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0136] In addition, those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the above claims, any one of the claimed embodiments may be used in any combination. The information disclosed in this background technology section is intended only to deepen the understanding of the overall background technology of the present application and should not be regarded as an admission or in any form of implication that the information constitutes prior art known to those skilled in the art.

Claims

1. A method for preparing reagent potassium sulfate from salt lake source agricultural potassium sulfate, characterized in that: The following steps are involved: S1, add a part of the solvent to the reactor, slowly add salt lake source agricultural potassium sulfate under stirring, then slowly add AR sulfuric acid, add the remaining solvent, boil and keep for 3-8h, and discharge into a storage container; S2, extracting the supernatant in the storage container, drying the remaining material in the storage container in a plastic coating drying machine, rinsing and drying, and obtaining a primary potassium sulfate product; S3, take part of the potassium sulfate product in S2, add a part of pure water into another reaction kettle, slowly add the potassium sulfate product under stirring, heat to 70-80°C, add the remaining amount of pure water, so that the potassium sulfate product is completely dissolved to form a solution; S4, adding AR potassium persulfate and activated carbon to the solution of S3, adjusting the pH with AR potassium hydroxide and / or AR sulfuric acid, concentrating under reduced pressure, cooling to room temperature, crystallizing, and dehydrating on a centrifuge to obtain wet potassium sulfate; S5, drying the wet potassium sulfate to obtain reagent potassium sulfate; In S1, the mass ratio of agricultural potassium sulfate: AR sulfuric acid: solvent is 800-1500: 150-250: 1500-2500, and a portion of the solvent is 60%-90% of the total solvent; in S3-S4, the mass ratio of primary potassium sulfate: AR potassium persulfate: activated carbon: pure water is 400-600: 1-5: 1: 2500-3500, and a portion of the pure water is 50%-90% of the total pure water.

2. The method for preparing reagent potassium sulfate from salt lake source agricultural potassium sulfate according to claim 1, characterized in that: S4 includes the following steps: S41, add AR potassium persulfate to the solution of S3, continue stirring, adjust the pH to ≥ 10.0 with AR potassium hydroxide, add AR potassium carbonate, continue stirring, add activated carbon, turn off stirring, and keep warm and let stand; S42, filter the solution of S41, adjust the pH of the filtrate to 6.0-7.0 with AR sulfuric acid, heat and boil, adjust the pH of the filtrate to 6.0-7.0 with AR sulfuric acid, and concentrate under reduced pressure to half the volume of the solution until a large amount of crystals are produced, then finish the concentration, cool to room temperature, crystallize, and dehydrate on a centrifuge to obtain wet potassium sulfate; Among them, the mass ratio of AR potassium carbonate: potassium sulfate is 5-15:400-600.

3. The method for preparing reagent potassium sulfate from salt lake source agricultural potassium sulfate according to claim 1, characterized in that: S4 includes the following steps: S41, adjust the pH value of the solution in S3 to ≥ 10.0 with AR potassium hydroxide, add AR potassium carbonate, continue stirring, add activated carbon, turn off stirring, and keep warm and let stand; S42, filter the solution of S41, adjust the pH of the filtrate to 6.0-7.0 with AR sulfuric acid, add AR potassium persulfate, heat and boil, adjust the pH of the filtrate to 6.0-7.0 with AR sulfuric acid, and concentrate under reduced pressure to half the volume of the solution until a large amount of crystals are produced, then finish the concentration, cool to room temperature, crystallize, and dehydrate on a centrifuge to obtain wet potassium sulfate; Among them, the mass ratio of AR potassium carbonate: potassium sulfate is 5-15:400-600.

4. The method for preparing reagent potassium sulfate from salt lake source agricultural potassium sulfate according to claim 1, characterized in that: S4 includes the following steps: S41, add a portion of AR potassium persulfate to the solution of S3, continue stirring, adjust the pH to ≥ 10.0 with AR potassium hydroxide, add activated carbon, turn off stirring, and keep warm and let stand; S42, filter the solution of S41, adjust the pH of the filtrate to 6.0-7.0 with AR sulfuric acid, add the remaining amount of AR potassium persulfate, heat and boil, adjust the pH of the filtrate to 6.0-7.0 with AR sulfuric acid, and concentrate under reduced pressure to half the volume of the solution until a large amount of crystals are produced, then end the concentration, cool to room temperature, crystallize, and dehydrate on a centrifuge to obtain a wet potassium sulfate product; The part of AR potassium persulfate is 50% to 80% of the total amount of AR potassium persulfate.

5. The method for preparing reagent potassium sulfate from salt lake source agricultural potassium sulfate according to claim 1, characterized in that: S4 includes the following steps: S41, add a portion of AR potassium persulfate to the solution in S3, continue stirring, adjust the pH to ≥ 10.0 with AR potassium hydroxide, add AR potassium carbonate, continue stirring, add activated carbon, turn off stirring, and keep warm and let stand for more than 4 hours. S42, filter the solution of S41, adjust the pH of the filtrate to 6.0-7.0 with AR sulfuric acid, add the remaining amount of AR potassium persulfate, heat and boil, adjust the pH of the filtrate to 6.0-7.0 with AR sulfuric acid, and concentrate under reduced pressure to half the volume of the solution until a large amount of crystals are produced, then end the concentration, cool to room temperature, crystallize, and dehydrate on a centrifuge to obtain a wet potassium sulfate product; The mass ratio of AR potassium carbonate to potassium sulfate is 5-15:400-600, and the part of AR potassium persulfate is 50%-80% of the total amount of AR potassium persulfate.

6. The method for preparing reagent potassium sulfate from salt lake source agricultural potassium sulfate according to any one of claims 1 to 5, characterized in that: In S1, the solvent is pure water.

7. The method for preparing reagent potassium sulfate from salt lake source agricultural potassium sulfate according to claim 6, characterized in that: In S1, the supernatant, the spin liquid produced by the spin dryer and the spray liquid formed by elution are recycled. When recycled, the chloride ions in the newly produced supernatant are not enriched.

8. The method for preparing reagent potassium sulfate from salt lake source agricultural potassium sulfate according to any one of claims 1 to 5, characterized in that: In S1, the solvent is a mixture of the supernatant produced in the previous production process, the spin liquid produced by the spin dryer, and the spray liquid formed by elution.

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