CN113135581A - Process for preparing magnesium potassium sulfate and potassium sulfate by extracting potassium from corn soaking liquid - Google Patents
Process for preparing magnesium potassium sulfate and potassium sulfate by extracting potassium from corn soaking liquid Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D5/00—Sulfates or sulfites of sodium, potassium or alkali metals in general
- C01D5/02—Preparation of sulfates from alkali metal salts and sulfuric acid or bisulfates; Preparation of bisulfates
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D5/00—Sulfates or sulfites of sodium, potassium or alkali metals in general
- C01D5/12—Preparation of double sulfates of magnesium with sodium or potassium
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- C05—FERTILISERS; MANUFACTURE THEREOF
- C05D—INORGANIC FERTILISERS NOT COVERED BY SUBCLASSES C05B, C05C; FERTILISERS PRODUCING CARBON DIOXIDE
- C05D1/00—Fertilisers containing potassium
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- C05D1/00—Fertilisers containing potassium
- C05D1/02—Manufacture from potassium chloride or sulfate or double or mixed salts thereof
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Abstract
The invention relates to a process method for preparing magnesium potassium sulfate and potassium sulfate by extracting potassium from corn soaking liquid, belonging to the field of resource recycling. The method comprises the steps of corn soaking liquid pretreatment, adsorption treatment, analysis treatment, concentration treatment, potassium magnesium sulfate preparation, potassium sulfate preparation and the like, wherein potassium derived from corn is prepared into potassium salt for industry or agriculture, so that the recycling of renewable potassium resources is realized, the consumption of mineral resources is reduced, carbon neutralization is realized, and the import dependence of potassium raw materials is compensated to a certain extent. The process method can extract potassium from the corn soaking solution, the extraction rate can reach more than 95%, the prepared potassium magnesium sulfate can reach the quality requirements of GB/T20937-2018 potassium magnesium sulfate fertilizer of more than one grade, and the prepared potassium magnesium sulfate fertilizer can be sold as a commodity and can also be used for preparing potassium sulfate; the prepared potassium sulfate meets the quality requirements of superior potassium sulfate products for GB20406-2017 agriculture. Has great significance for agricultural development and environmental protection in China.
Description
Technical Field
The invention relates to the field of resource recycling, in particular to a process method for preparing magnesium potassium sulfate and potassium sulfate by extracting potassium from corn soaking liquid. Potassium element is extracted from corn soaking liquid, potassium magnesium sulfate and potassium sulfate are prepared, potassium from corn is prepared into potassium salt for industry or agriculture, and recycling of potassium resources is achieved.
Background
Potassium is one of three elements of the fertilizer, and the content of potassium in the plant body is generally 0.2-4.1% of the dry matter weight, and is only second to nitrogen. During the growth and development of plants, potassium is involved in the processes of activation of more than 60 enzyme systems, photosynthesis, transport of assimilation products, carbohydrate metabolism, protein synthesis and the like. China is both a big agricultural country and a potassium-poor country, the recoverable reserve of potassium resources in China accounts for about 9% of the world, the consumption accounts for about 26% of the world, the annual demand of sylvite in 2020 is about 1000 million tons, the self-supply rate is less than 60%, and the import dependence is higher. The domestic potash fertilizer mainly uses minerals containing potassium, salt lake resources, seawater bittern and the like as raw materials to produce potassium sulfate and potash magnesium sulphate fertilizer, consumes non-renewable mineral resources and has a certain influence on the ecological environment of the resource location.
Disclosure of Invention
The invention aims to provide a process method for preparing magnesium potassium sulfate and potassium sulfate by extracting potassium from corn soaking liquid, so that the recycling of renewable resources is realized, the consumption of mineral resources is reduced, and the ecological environment is protected. The potassium sulfate and the potassium magnesium sulfate are prepared by extracting potassium in the corn soaking solution, so that the recycling of potassium element in crop planting, agricultural product processing and potassium element extraction and recovery to prepare the potassium fertilizer is realized. The extraction rate of potassium in the corn soaking solution can reach more than 95%, the prepared potassium magnesium sulfate can meet the quality requirement of GB/T20937-2018 potassium magnesium sulfate fertilizer of more than one grade, and the prepared potassium magnesium sulfate can be sold as a commodity and also can be used for preparing potassium sulfate; the prepared potassium sulfate meets the quality requirements of superior potassium sulfate products for GB20406-2017 agriculture.
The invention takes corn soaking liquid as raw material, potassium element is extracted from the corn soaking liquid, the corn soaking liquid is the first procedure of corn deep processing, namely, the corn needs to be soaked by sulfurous acid to soften seeds, the corn skin is separated from the endosperm, starch is separated from protein, and then subsequent grinding processing is carried out, the potassium element in the corn seeds is dissolved into the soaking liquid along with components such as soluble protein and the like in the soaking process, thereby providing opportunity for recycling of potassium. The potassium element is extracted from the corn soaking solution to prepare the potassium sulfate and the potassium sulfate magnesium fertilizer, so that the potassium element is recycled, the consumption of mineral resources and salt lake resources is reduced, carbon neutralization is realized, and the import dependence of potassium raw materials is compensated to a certain extent. Has great significance for Chinese agricultural development and environmental protection.
The above object of the present invention is achieved by the following technical solutions:
the process method for preparing magnesium potassium sulfate and potassium sulfate by extracting potassium from corn soaking solution comprises the following steps:
step (1), pretreatment of corn soaking liquid: removing solid matters in the corn soaking solution by adopting a sedimentation or membrane filtration mode, and collecting clear corn soaking solution for extracting potassium element;
step (2), adsorption treatment: absorbing potassium ions in the corn soaking solution by a cation resin exchange column in a forward feeding or reverse feeding mode;
step (3), analysis treatment: eluting the cation resin exchange column with saturated adsorption with eluent, and collecting the eluate;
step (4), concentration treatment: adjusting the pH value of the analytic solution obtained in the step (3) according to the process requirement, pre-concentrating by adopting membrane filtration or electrodialysis, and continuously concentrating by adopting heat to obtain a concentrated solution with the concentration required by subsequent crystallization;
step (5), preparation of potassium magnesium sulfate: cooling and crystallizing the concentrated solution obtained in the step (5), precipitating potassium magnesium sulfate crystals, and returning the residual crystallization mother liquor III to the step (3) for preparing the eluent;
step (6), preparation of potassium sulfate: performing water-salt conversion on the potassium magnesium sulfate obtained in the step (6) to obtain a potassium sulfate product; and (5) returning the residual crystallization mother liquor five to the step (3) for preparing the eluent.
Pretreating a corn soaking solution, wherein the corn soaking solution can be selected to remove calcium and magnesium ions in the corn soaking solution by adopting chelating cation exchange resin;
the packing in the cation resin exchange column is preferably strong acid type cation exchange resin, including but not limited to: crosslinked styrene type strong acid resin T42 or styrene-divinylbenzene strong acid resin D001.
And (3) enabling the corn steep liquor in the step (2) to enter a cation resin exchange column at a flow speed of 0.5-30 BV/h.
The flow rate of the eluent in the step (3) in the cation resin exchange column is 0.5-30 BV/h, and the eluent is preferably one or a combination of the following solutions:
sulfuric acid solution: w/w 2-15%
Magnesium sulfate solution: w/w is 3-15%;
acid magnesium sulfate solution: w/w is 3-15%, and the pH value is 0.5-4;
magnesium chloride and magnesium sulfate solution: 1-5% of w/w magnesium chloride and 2-10% of w/w magnesium sulfate;
wherein w/w represents mass percent concentration.
And (3) integrating the step (2) and the step (3) into a set of simulated moving bed or continuous moving bed to realize continuous operation of series adsorption, series desorption, adsorption and desorption.
When the pH value of the analytic solution in the step (4) is lower than 2, the pH value needs to be adjusted to 2-7, an alkaline substance used for adjusting the pH value can be potassium hydroxide or magnesium hydroxide or a combination of the potassium hydroxide and the magnesium hydroxide, equipment used for membrane filtration is a nanofiltration membrane or a reverse osmosis membrane with the molecular weight cutoff of less than 150 dadale, and the concentration multiple is 1.5-2.5 times; the electrodialysis adopts equipment equipped with a homogeneous membrane stack, and the concentration multiple is 2-4 times.
Taking the concentrated solution obtained in the step (4), and adopting a secondary, two-stage and circulating crystallization system, namely: performing primary crystallization at 20-50 ℃ to obtain magnesium potassium sulfate; continuously concentrating the residual mother liquor I until the total salt content is 30-40%, and performing primary secondary crystallization at 20-50 ℃ to obtain magnesium potassium sulfate; carrying out second-stage crystallization on the residual mother liquor II at the temperature of 0-20 ℃, and putting the second-stage crystallization as a seed crystal into the next batch of concentrated solution to enter the next crystallization operation; the residual mother liquor is mother liquor III, and the mother liquor III is returned to the step (3) for preparing the eluent; the circulating crystallization yield of the magnesium potassium sulfate reaches more than 90 percent based on the potassium sulfate.
Taking the potassium magnesium sulfate crystal obtained in the step (5), adopting a multi-cycle water-salt conversion technology, and performing first-cycle reaction on wet potassium magnesium sulfate crystals and mother liquor obtained by cycle crystallization at the temperature of 20-60 ℃ according to a mass ratio of 1: 0.6-1.0, preparing slurry, stirring and converting for 20-150 minutes, and then carrying out centrifugal separation to obtain crude potassium sulfate and mother liquor IV; cooling the mother liquor IV to-20 ℃ for low-temperature crystallization, performing solid-liquid separation to obtain crystallized potassium magnesium sulfate and mother liquor V, returning the obtained crystallized potassium magnesium sulfate to the first-round conversion reaction tank for next-round conversion, and returning the obtained mother liquor V to the step (3) for preparing the eluent; mixing the crude potassium sulfate obtained by the first round of conversion with pure water 1: preparing slurry according to the proportion of 0.4-1.0, stirring and converting for 20-90 minutes at the temperature of 20-60 ℃, and performing solid-liquid separation to obtain a potassium sulfate product and a mother liquor six, wherein the mother liquor six is used for next cycle conversion ingredient; the yield of the potassium sulfate obtained by multiple cycles of circulation is more than 85 percent.
And (4) washing the potassium sulfate obtained in the step (6) by using 50-99% of ethanol or ethyl ether in an amount of 50-200% of the dry weight of the potassium sulfate according to the quality requirement to improve the purity of the potassium sulfate.
The invention has the beneficial effects that: as an original technology for extracting potassium from corn soaking liquid to prepare potassium salt, the invention opens up a process route for extracting potassium element from the corn soaking liquid to prepare potassium magnesium sulfate and potassium sulfate, namely, the potassium fertilizer is applied from corn planting, corn is harvested, corn is processed, the potassium element is extracted, the potassium fertilizer is manufactured, the potassium element applied to the corn planting is recycled, the consumption of mineral resources is reduced, carbon neutralization is realized, and the import dependence of potassium raw materials is compensated to a certain extent. Has great significance for agricultural development and environmental protection in China. The process method can extract potassium from the corn soaking solution, the extraction rate can reach more than 95%, and the prepared potassium magnesium sulfate can meet the quality requirements of GB/T20937-2018 potassium magnesium sulfate fertilizer of more than first-class products, and can be sold as a commodity and used for preparing potassium sulfate; the prepared potassium sulfate meets the quality requirements of superior potassium sulfate products for GB20406-2017 agriculture.
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The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention.
FIG. 1 is a diagram showing the effect of recycling potassium in the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail with reference to the accompanying drawings and the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Referring to fig. 1, the process for preparing magnesium potassium sulfate and potassium sulfate by extracting potassium from corn steep liquor of the invention prepares potassium from corn into potassium salt for use in industry or agriculture, namely, realizes potassium fertilizer application from corn planting, corn harvesting, corn processing, potassium element extraction, potassium fertilizer manufacturing, potassium element recycling of potassium fertilizer application for corn planting, and realizes recycling of potassium resources. The process method can extract potassium from the corn soaking solution, the extraction rate can reach more than 95%, the prepared potassium magnesium sulfate can reach the quality requirements of GB/T20937-2018 potassium magnesium sulfate fertilizer of more than one grade, and the prepared potassium magnesium sulfate fertilizer can be sold as a commodity and can also be used for preparing potassium sulfate; the prepared potassium sulfate meets the quality requirements of superior potassium sulfate products for GB20406-2017 agriculture. The method comprises the following steps:
step (1), pretreatment of corn soaking liquid: removing solid matters in the corn soaking solution by adopting a sedimentation or membrane filtration mode, and collecting clear corn soaking solution for extracting potassium element;
step (2), adsorption treatment: absorbing potassium ions in the corn soaking solution by a cation resin exchange column in a forward feeding or reverse feeding mode;
step (3), analysis treatment: eluting the cation resin exchange column with saturated adsorption with eluent, and collecting the eluate;
step (4), concentration treatment: after the pH value of the analytic liquid obtained in the steps (2) to (3) is adjusted according to the process requirement, membrane filtration or electrodialysis is adopted for pre-concentration, and then thermal concentration is continuously adopted to obtain the concentrated liquid with the concentration required by subsequent crystallization;
step (5), preparation of potassium magnesium sulfate: cooling and crystallizing the concentrated solution obtained in the step (5), precipitating potassium magnesium sulfate crystals, and returning the residual crystallization mother liquor III to the step (3) for preparing the eluent;
step (6), preparation of potassium sulfate: performing water-salt conversion on the potassium magnesium sulfate obtained in the step (6) to obtain a potassium sulfate product; and (5) returning the residual crystallization mother liquor five to the step (3) for preparing the eluent.
Pretreating a corn soaking solution, wherein the corn soaking solution can be selected to remove calcium and magnesium ions in the corn soaking solution by adopting chelating cation exchange resin;
the packing in the cation resin exchange column is preferably strong acid type cation exchange resin, including but not limited to: crosslinked styrene type strong acid resin T42 or styrene-divinylbenzene strong acid resin D001.
And (3) enabling the corn steep liquor in the step (2) to enter a cation resin exchange column at a flow speed of 0.5-30 BV/h.
The flow rate of the eluent in the step (3) in the cation resin exchange column is 0.5-30 BV/h, and the eluent is preferably one or a combination of several of the following solutions (wherein w/w represents the mass percentage concentration):
sulfuric acid solution: w/w 2-15%
Magnesium sulfate solution: w/w is 3-15%;
acid magnesium sulfate solution: w/w is 3-15%, and the pH value is 0.5-4;
magnesium chloride and magnesium sulfate solution: 1-5% w/w magnesium chloride and 2-10% w/w magnesium sulfate.
And (3) integrating the step (2) and the step (3) into a set of simulated moving bed or continuous moving bed to realize continuous operation of series adsorption, series desorption, adsorption and desorption. The moving bed equipment can effectively improve the potassium content in the analysis liquid and reduce the consumption of the eluent.
When the pH value of the analytic solution in the step (4) is lower than 2, the pH value needs to be adjusted to 2-7, an alkaline substance used for adjusting the pH value can be potassium hydroxide or magnesium hydroxide or a combination of the potassium hydroxide and the magnesium hydroxide, equipment used for membrane filtration is a nanofiltration membrane or a reverse osmosis membrane with the molecular weight cutoff of less than 150 dadale, and the concentration multiple is 1.5-2.5 times; the electrodialysis adopts equipment equipped with a homogeneous membrane stack, and the concentration multiple is 2-4 times.
Taking the concentrated solution obtained in the step (4), and adopting a secondary, two-stage and circulating crystallization system, namely: performing primary crystallization at 20-50 ℃ to obtain magnesium potassium sulfate; continuously concentrating the residual mother liquor I until the total salt content is 30-40%, and performing primary secondary crystallization at 20-50 ℃ to obtain magnesium potassium sulfate; carrying out second-stage crystallization on the residual mother liquor II at the temperature of 0-20 ℃, and putting the second-stage crystallization as a seed crystal into the next batch of concentrated solution to enter the next crystallization operation; the residual mother liquor is mother liquor III, and the mother liquor III is returned to the step (3) for preparing the eluent; the circulating crystallization yield of the magnesium potassium sulfate reaches more than 90 percent based on the potassium sulfate.
Taking the potassium magnesium sulfate crystal obtained in the step (5), adopting a multi-cycle water-salt conversion technology, and performing first-cycle reaction on wet potassium magnesium sulfate crystals and mother liquor obtained by cycle crystallization at the temperature of 20-60 ℃ according to a mass ratio of 1: 0.6-1.0, preparing slurry, stirring and converting for 20-150 minutes, and then carrying out centrifugal separation to obtain crude potassium sulfate and mother liquor IV; cooling the mother liquor IV to-20 ℃ for low-temperature crystallization, performing solid-liquid separation to obtain crystallized potassium magnesium sulfate and mother liquor V, returning the obtained crystallized potassium magnesium sulfate to the first-round conversion reaction tank for next-round conversion, and returning the obtained mother liquor V to the step (3) for preparing the eluent; mixing the crude potassium sulfate obtained by the first round of conversion with pure water 1: preparing slurry according to the proportion of 0.4-1.0, stirring and converting for 20-90 minutes at the temperature of 20-60 ℃, and performing solid-liquid separation to obtain a potassium sulfate product and a mother liquor six, wherein the mother liquor six is used for next cycle conversion ingredient; the yield of the potassium sulfate obtained by multiple cycles of circulation is more than 85 percent.
And (4) washing the potassium sulfate obtained in the step (6) by using 50-99% of ethanol or ethyl ether in an amount of 50-200% of the dry weight of the potassium sulfate according to the quality requirement to improve the purity of the potassium sulfate.
Example 1:
a process method for preparing magnesium potassium sulfate and potassium sulfate by extracting potassium from corn soaking liquid comprises the following steps:
(1) pretreatment of corn soaking liquid: after the corn soaking solution is subjected to sedimentation treatment, a nanofiltration membrane is used for filtering flocculate.
(2) Adsorption treatment: and (2) adsorbing potassium by the corn soaking solution treated in the step (1) through a continuous moving bed filled with D001 type resin, wherein the flow rate of the corn soaking solution entering a continuous moving bed adsorption unit is 15 BV/h.
(3) And (3) analysis treatment: preparing a magnesium sulfate solution with the mass percentage concentration of 10% for the resin in the desorption step (2), entering a resin column in an elution area after the resin is adsorbed and saturated, controlling the flow rate of an eluent entering an elution unit to be 6BV/h, and continuously collecting the desorption solution.
(4) Concentration treatment: and (4) carrying out electrodialysis concentration on the analysis solution obtained in the step (3) until the salt content is 26%, and then concentrating the analysis solution by a heat concentrator until the total salt content is 38%.
(5) Crystallizing potassium magnesium sulfate: taking the concentrated solution of the step (4) to crystallize, adopting a secondary, two-stage and circulating crystallization system, and carrying out primary crystallization and centrifugal separation at 30 ℃ to obtain potassium magnesium sulfate; continuously concentrating the residual mother liquor I until the total salt content is 35%, and crystallizing at 10 ℃ for the second time to obtain magnesium potassium sulfate; carrying out second-stage crystallization on the residual mother liquor at the temperature of between two and 5 ℃, and putting the second-stage crystallization serving as a seed crystal into the next batch of concentrated solution to enter the next crystallization operation; returning the rest mother liquor as mother liquor III to the step (3) for preparing the eluent; the circulating crystallization yield of the magnesium potassium sulfate reaches 92.8 percent.
(6) Potassium sulfate conversion: preparing the potassium magnesium sulfate crystal obtained in the step (5) and deionized water into slurry according to the wet crystal-water mass ratio of 1:0.6, stirring and converting the slurry for 120 minutes at the first wheel at the rotating speed of 200rpm at the temperature of 60 ℃, and then carrying out centrifugal separation to obtain crude potassium sulfate and mother liquor IV; and (4) cooling the mother liquor IV to 0 ℃ for low-temperature crystallization, performing solid-liquid separation to obtain crystallized potassium magnesium sulfate, returning the crystallized potassium magnesium sulfate to the first-round conversion reaction tank for next-round conversion, and returning the rest mother liquor V to the step (3) for preparing the eluent. Preparing slurry from the crude potassium sulfate obtained by the first round of conversion and pure water according to the proportion of 1:0.5 of wet crystal weight, stirring and converting for 45 minutes at the temperature of 60 ℃, carrying out solid-liquid separation to obtain a potassium sulfate product and a mother liquor six, converting the mother liquor six for the next round to replace deionized water, and recycling for multiple rounds to obtain the potassium sulfate with the yield of 90 percent and the potassium oxide content of 52 percent.
Example 2:
a process method for preparing magnesium potassium sulfate and potassium sulfate by extracting potassium from corn soaking liquid comprises the following steps:
(1) pretreatment of corn soaking liquid: and settling the corn soaking solution, and taking the supernatant for later use.
(2) Adsorption treatment: and (2) taking the supernatant of the corn steep liquor subjected to sedimentation treatment in the step (1), and adsorbing potassium by using D001 type resin, wherein the flow rate of the corn steep liquor entering a cation resin exchange column is 5 BV/h.
(3) And (3) analysis treatment: and (3) using acidic magnesium sulfate for resolution, preparing a magnesium sulfate solution with the mass percentage concentration of 6%, using sulfuric acid to adjust the pH value to 2, using the sulfuric acid to absorb saturated potassium ions on the resin in the resolution step (2), controlling the flow rate of the eluent in the resin exchange column to be 3BV/h, and collecting a resolution solution.
(4) Concentration treatment: concentrating the analytic solution obtained in the step (3) by a heat concentrator until the total salt content is 35%.
(5) Crystallizing potassium magnesium sulfate: taking the concentrated solution of the step (4) to crystallize, adopting a secondary, two-stage and circulating crystallization system, and carrying out primary crystallization and centrifugal separation at 20 ℃ to obtain potassium magnesium sulfate; continuously concentrating the residual mother liquor I until the total salt content is 34%, and performing secondary crystallization at 20 ℃ to obtain magnesium potassium sulfate; carrying out second-stage crystallization on the residual mother liquor at the temperature of two 0 ℃, and putting the second-stage crystallization as a seed crystal into the next batch of concentrated solution to enter the next round of crystallization operation; returning the residual mother liquor III to the step (3) for preparing the eluent; the yield of the potassium magnesium sulfate circulating crystallization reaches 89 percent.
(6) Potassium sulfate conversion: taking the potassium magnesium sulfate crystal obtained in the step (5) and deionized water according to the mass ratio of wet crystal to water of 1: 0.8 is prepared into slurry, the first wheel is stirred and converted for 90 minutes at the temperature of 50 ℃ and the rotating speed of 200rpm, and then the coarse potassium sulfate and the mother solution IV are obtained by centrifugal separation; and (4) cooling the mother liquor IV to 0 ℃ for low-temperature crystallization, performing solid-liquid separation to obtain crystallized potassium magnesium sulfate, returning the crystallized potassium magnesium sulfate to the first-round conversion reaction tank for next-round conversion, and returning the rest mother liquor V to the step (3) for preparing the eluent. Mixing the crude potassium sulfate obtained by the first round of conversion with pure water 1: preparing slurry according to the proportion of 0.6, stirring and converting for 60 minutes at the temperature of 50 ℃, performing solid-liquid separation to obtain a potassium sulfate product and a mother liquor six, converting the mother liquor six for the next cycle to replace deionized water, and performing multiple cycles to obtain the potassium sulfate with the yield of 86 percent and the potassium oxide content of 51.5 percent.
Example 3:
a process method for preparing magnesium potassium sulfate and potassium sulfate by extracting potassium from corn soaking liquid comprises the following steps:
(1) pretreatment of corn soaking liquid: after the corn soaking solution is subjected to sedimentation treatment, a nanofiltration membrane is used for filtering flocculate.
(2) Adsorption treatment: and (2) adsorbing potassium by the corn soaking solution treated in the step (1) through a continuous moving bed filled with D001 type resin, wherein the flow rate of the corn soaking solution entering a continuous moving bed adsorption unit is 10 BV/h.
(3) And (3) analysis treatment: and (3) preparing a mixed solution containing 3.1% of magnesium sulfate and 3.8% of magnesium chloride for resolving the resin in the step (2), introducing the resin into a resin column of an elution area after the resin is adsorbed and saturated, controlling the flow rate of an eluent entering an elution unit to be 4BV/h, and continuously collecting a resolving solution.
(4) Concentration treatment: and (4) concentrating the analytic solution obtained in the step (3) by adopting electrodialysis until the salt content is 26%, and concentrating by adopting a heat concentrator until the total salt content is 35%.
(5) Potassium mixed salt preparation (potassium magnesium sulfate obtained contains part of potassium chloride and magnesium chloride due to the use of mixed eluent, so called potassium mixed salt): cooling the concentrated solution obtained in the step (4) to 15 ℃, crystallizing, and performing centrifugal separation to obtain potassium mixed salt; continuously concentrating the residual mother liquor I until the total salt content is 35%, and crystallizing at 10 ℃ for the second time to obtain potassium mixed salt; carrying out second-stage crystallization on the residual mother liquor at the temperature of two 0 ℃, and putting the second-stage crystallization as a seed crystal into the next batch of concentrated solution to enter the next round of crystallization operation; returning the residual mother liquor III to the step (3) for preparing the eluent; the crystallization yield of the potassium mixed salt is up to 90 percent based on potassium.
(6) Potassium sulfate conversion: taking the potassium mixed salt obtained in the step (5) and deionized water according to the mass ratio of wet crystal to water of 1: 0.8, preparing slurry, stirring and converting the first wheel at the rotating speed of 200rpm for 120 minutes at the temperature of 55 ℃, cooling to 25 ℃, and performing centrifugal separation to obtain crude potassium sulfate and mother liquor IV; and (4) cooling the obtained mother liquor IV to 0 ℃ for low-temperature crystallization, performing solid-liquid separation to obtain crystallized potassium magnesium sulfate, returning the crystallized potassium magnesium sulfate to the first-round conversion reaction tank for next-round conversion, and returning the rest mother liquor V to the step (3) for preparing the eluent. Mixing the crude potassium sulfate obtained by the first round of conversion with pure water 1: preparing slurry according to the proportion of 0.5, stirring and converting for 45 minutes at the temperature of 60 ℃, performing solid-liquid separation to obtain a potassium sulfate product and a mother solution six, performing first-cycle conversion on the mother solution six to replace deionized water, performing multiple cycles to obtain the potassium sulfate with the yield of 90%, washing the obtained potassium sulfate by using 90% ethanol solution with the dry weight of 100%, and finally obtaining the sulfuric acid finished product with the potassium oxide content of 52%.
Example 4:
a process method for preparing magnesium potassium sulfate and potassium sulfate by extracting potassium from corn soaking liquid comprises the following steps:
(1) pretreatment of corn soaking liquid: and settling the corn soaking solution, and taking the supernatant for later use.
(2) Adsorption treatment: and (2) taking the supernatant of the corn steep liquor subjected to sedimentation treatment in the step (1), and adsorbing potassium by using D001 type resin, wherein the flow rate of the corn steep liquor entering a cation resin exchange column is 6 BV/h.
(3) And (3) analysis treatment: and (3) resolving by using sulfuric acid, preparing a sulfuric acid solution with the mass percentage concentration of 6%, using the sulfuric acid solution to resolve the saturated potassium ions adsorbed on the resin in the step (2), controlling the flow rate of the eluent in the resin exchange column to be 2.5BV/h, and collecting a resolving solution.
(4) Concentration treatment: and (4) adding the analysis solution obtained in the step (3) into the analysis solution for multiple times by using a small amount of potassium hydroxide particles, adjusting the pH value to 4.5, concentrating by adopting electrodialysis until the total salt content is 25%, and concentrating by adopting a heat concentrator until the total salt content is 34%.
(5) Potassium magnesium sulfate and potassium sulfate crystal (using sulfuric acid as eluent and potassium hydroxide to regulate pH value, concentrating and crystallizing to obtain the mixture of potassium magnesium sulfate and potassium sulfate): taking the concentrated solution of the step (4) to crystallize, adopting a secondary, two-stage and circulating crystallization system, and carrying out primary crystallization and centrifugal separation at 20 ℃ to obtain potassium magnesium sulfate; continuously concentrating the residual mother liquor I until the total salt content is 34%, and performing secondary crystallization at 20 ℃ to obtain magnesium potassium sulfate; carrying out second-stage crystallization on the residual mother liquor at the temperature of two 0 ℃, and putting the second-stage crystallization as a seed crystal into the next batch of concentrated solution to enter the next round of crystallization operation; returning the residual mother liquor III to the step (3) for preparing the eluent; the circulating crystallization yield of the potassium magnesium sulfate and the potassium sulfate reaches 90 percent based on potassium.
(6) Potassium sulfate conversion: taking the crystal of the potassium magnesium sulfate and the potassium sulfate obtained in the step (5) and deionized water according to the mass ratio of wet crystal to water of 1: 0.8 is prepared into slurry, the first wheel is stirred and converted for 60 minutes at the rotating speed of 200rpm under the condition of 45 ℃, and then the coarse potassium sulfate and the mother solution IV are obtained by centrifugal separation; and (4) cooling the mother liquor IV to 0 ℃ for low-temperature crystallization, performing solid-liquid separation to obtain crystallized magnesium potassium sulfate and potassium sulfate, returning the crystallized magnesium potassium sulfate and potassium sulfate to the first-round conversion reaction tank for next-round conversion, and returning the rest mother liquor V to the step (3) for preparing the eluent. Mixing the crude potassium sulfate obtained by the first round of conversion with pure water 1: preparing slurry according to the proportion of 0.5, stirring and converting for 45 minutes at the temperature of 50 ℃, performing solid-liquid separation to obtain a potassium sulfate product and a mother liquor six, converting the mother liquor six for the next cycle to replace deionized water, and performing multiple cycles to obtain the potassium sulfate with the yield of 90 percent and the potassium oxide content of 52 percent.
The above description is only a preferred example of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like of the present invention shall be included in the protection scope of the present invention.
Claims (10)
1. A process method for preparing magnesium potassium sulfate and potassium sulfate by extracting potassium from corn soaking solution is characterized in that: the method comprises the following steps:
step (1), pretreatment of corn soaking liquid: removing solid matters in the corn soaking solution by adopting a sedimentation or membrane filtration mode, and collecting clear corn soaking solution for extracting potassium element;
step (2), adsorption treatment: absorbing potassium ions in the corn soaking solution by a cation resin exchange column in a forward feeding or reverse feeding mode;
step (3), analysis treatment: eluting the cation resin exchange column with saturated adsorption with eluent, and collecting the eluate;
step (4), concentration treatment: adjusting the pH value of the analytic solution obtained in the step (3) according to the process requirement, pre-concentrating by adopting membrane filtration or electrodialysis, and then continuously adopting a thermal concentration mode to obtain a concentrated solution with the concentration required by subsequent crystallization;
step (5), preparation of potassium magnesium sulfate: cooling and crystallizing the concentrated solution obtained in the step (4), precipitating potassium magnesium sulfate crystals, and returning the residual crystallization mother liquor III to the step (3) for preparing the eluent;
step (6) preparation of potassium sulfate: carrying out water-salt conversion on the potassium magnesium sulfate obtained in the step (5) to obtain a potassium sulfate product; and (5) returning the residual crystallization mother liquor five to the step (3) for preparing the eluent.
2. The process for preparing magnesium potassium sulfate and potassium sulfate by extracting potassium from corn steep liquor as claimed in claim 1, wherein the process comprises the steps of: and (2) pretreating the corn soaking solution, wherein the corn soaking solution can be selected to remove calcium and magnesium ions in the corn soaking solution by adopting chelating cation exchange resin.
3. The process for preparing magnesium potassium sulfate and potassium sulfate by extracting potassium from corn steep liquor as claimed in claim 1, wherein the process comprises the steps of: the packing in the cation resin exchange column is preferably strong acid type cation exchange resin, including but not limited to: crosslinked styrene type strong acid resin T42 or styrene-divinylbenzene strong acid resin D001.
4. The process for preparing magnesium potassium sulfate and potassium sulfate by extracting potassium from corn steep liquor as claimed in claim 1, wherein the process comprises the steps of: and (3) enabling the corn steep liquor in the step (2) to enter a cation resin exchange column at a flow speed of 0.5-30 BV/h.
5. The process for preparing magnesium potassium sulfate and potassium sulfate by extracting potassium from corn steep liquor as claimed in claim 1, wherein the process comprises the steps of: the flow rate of the eluent in the step (3) in the cation resin exchange column is 0.5-30 BV/h, and the eluent is preferably one or a combination of the following solutions:
sulfuric acid solution: w/w 2-15%
Magnesium sulfate solution: w/w is 3-15%;
acid magnesium sulfate solution: w/w is 3-15%, and the pH value is 0.5-4;
magnesium chloride and magnesium sulfate solution: 1-5% of w/w magnesium chloride and 2-10% of w/w magnesium sulfate;
wherein w/w represents mass percent concentration.
6. The process for preparing magnesium potassium sulfate and potassium sulfate by extracting potassium from corn steep liquor as claimed in claim 1, wherein the process comprises the steps of: and (3) integrating the step (2) and the step (3) into a set of simulated moving bed or continuous moving bed to realize continuous operation of series adsorption, series desorption, adsorption and desorption.
7. The process for preparing magnesium potassium sulfate and potassium sulfate by extracting potassium from corn steep liquor as claimed in claim 1, wherein the process comprises the steps of: when the pH value of the analytic solution in the step (4) is lower than 2, the pH value needs to be adjusted to 2-7, an alkaline substance used for adjusting the pH value can be potassium hydroxide or magnesium hydroxide or a combination of the potassium hydroxide and the magnesium hydroxide, equipment adopted for membrane filtration is a nanofiltration membrane or a reverse osmosis membrane with the molecular weight cutoff of less than 150 dadall, and the concentration multiple is 1.5-2.5 times; the electrodialysis adopts equipment equipped with a homogeneous membrane stack, and the concentration multiple is 2-4 times.
8. The process for preparing magnesium potassium sulfate and potassium sulfate by extracting potassium from corn steep liquor as claimed in claim 1, wherein the process comprises the steps of: taking the concentrated solution obtained in the step (4), and adopting a secondary, two-stage and circulating crystallization system, namely: performing primary crystallization at 20-50 ℃ to obtain magnesium potassium sulfate; continuously concentrating the residual mother liquor I until the total salt content is 30-40%, and performing primary secondary crystallization at 20-50 ℃ to obtain magnesium potassium sulfate; carrying out second-stage crystallization on the residual mother liquor II at the temperature of 0-20 ℃, and putting the second-stage crystallization as a seed crystal into the next batch of concentrated solution to enter the next crystallization operation; the residual mother liquor is mother liquor III, and the mother liquor III is returned to the step (3) for preparing the eluent; the circulating crystallization yield of the magnesium potassium sulfate reaches more than 90 percent based on the potassium sulfate.
9. The process for preparing magnesium potassium sulfate and potassium sulfate by extracting potassium from corn steep liquor as claimed in claim 1, wherein the process comprises the steps of: taking the potassium magnesium sulfate crystal obtained in the step (5), adopting a multi-cycle water-salt conversion technology, and performing first-cycle reaction on wet potassium magnesium sulfate crystals and mother liquor obtained by cycle crystallization at the temperature of 20-60 ℃ according to a mass ratio of 1: 0.6-1.0, preparing slurry, stirring and converting for 20-150 minutes, and then carrying out centrifugal separation to obtain crude potassium sulfate and mother liquor IV; cooling the mother liquor IV to-20 ℃ for low-temperature crystallization, performing solid-liquid separation to obtain crystallized potassium magnesium sulfate and mother liquor V, returning the obtained crystallized potassium magnesium sulfate to the first-round conversion reaction tank for next-round conversion, and returning the obtained mother liquor V to the step (3) for preparing the eluent; mixing the crude potassium sulfate obtained by the first round of conversion with pure water 1: preparing slurry according to the proportion of 0.4-1.0, stirring and converting for 20-90 minutes at the temperature of 20-60 ℃, and performing solid-liquid separation to obtain a potassium sulfate product and a mother liquor six, wherein the mother liquor six is used for next cycle conversion ingredient; the yield of the potassium sulfate obtained by multiple cycles of circulation is more than 85 percent.
10. The process for preparing magnesium potassium sulfate and potassium sulfate by extracting potassium from corn steep liquor as claimed in claim 1, wherein the process comprises the steps of: and (4) washing the potassium sulfate obtained in the step (6) by using 50-99% of ethanol or ethyl ether in an amount of 50-200% of the dry weight of the potassium sulfate to improve the purity of the potassium sulfate.
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| CN114031097A (en) * | 2021-12-09 | 2022-02-11 | 吉林海资生物工程技术有限公司 | Separation and purification technology of potassium salt extract obtained by extracting potassium from corn soaking solution |
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