阅读说明：本技术 一种利用玉米浸泡水制备钾盐并副产镁盐的工艺方法 (Process method for preparing potassium salt and byproduct magnesium salt by using corn soaking water ) 是由 朱理平 崔鑫 王超 何报春 曲松杰 王银花 于 2021-09-09 设计创作，主要内容包括：本发明公开了一种利用玉米浸泡水制备钾盐并副产镁盐的工艺方法,包括以下步骤：(1)玉米浸泡水经过静置沉降后的上清液,进入强酸阳离子树脂交换柱吸附；(2)吸附饱和的阳离子树脂交换柱,用水置顶出残留玉米浸泡水后,采用铵盐解吸剂或者钠盐解吸剂进行解析,收集解吸液；(3)将解析液真空浓缩结晶、离心分离、洗涤,获得成品钾盐；(4)将离心母液,加入除镁试剂搅拌反应得到镁盐副产品；滤液用浓盐酸调pH至3～5,套用至下一批配制解析剂用。本发明用价格低廉的铵盐、钠盐做解析剂,获得高附加值的钾盐产品和镁盐副产品,高盐的结晶母液作为下一批次的解吸剂进行套用,避免了产生高盐废水,实现了污水零排放。(The invention discloses a process method for preparing potassium salt and a byproduct magnesium salt by using corn soaking water, which comprises the following steps of: (1) supernatant fluid of the corn soaking water after standing and settling enters a strong acid cation resin exchange column for adsorption; (2) adsorbing a saturated cation resin exchange column, ejecting residual corn soaking water by using water, resolving by using an ammonium salt desorbent or a sodium salt desorbent, and collecting a desorption solution; (3) vacuum concentrating, crystallizing, centrifuging, and washing the analytic solution to obtain potassium salt product; (4) adding a magnesium removal reagent into the centrifugal mother liquor, and stirring for reaction to obtain a magnesium salt byproduct; and adjusting the pH of the filtrate to 3-5 by using concentrated hydrochloric acid, and mechanically applying the filtrate to the next batch for preparing the resolving agent. According to the invention, low-cost ammonium salt and sodium salt are used as the desorbing agents to obtain high-added-value potassium salt products and magnesium salt byproducts, and the high-salt crystallization mother liquor is used as the desorbing agent for the next batch for reuse, so that high-salt wastewater is avoided, and zero discharge of sewage is realized.)

1. A process method for preparing potassium salt and byproduct magnesium salt by using corn soaking water is characterized by comprising the following steps:

(1) supernatant fluid of the corn soaking water after standing and settling enters a strong acid cation resin exchange column for adsorption;

(2) adsorbing a saturated cation resin exchange column, ejecting residual corn soaking water by using water, resolving by using an ammonium salt desorbent or a sodium salt desorbent, and collecting a desorption solution;

(3) transferring the obtained analytic solution to a continuous concentration crystallizer for vacuum concentration crystallization; centrifuging the concentrated crystal liquid, washing with at least 0.5 times of water to obtain wet potassium salt, and drying to obtain final potassium salt product;

(4) adding a magnesium removal reagent into the centrifugally separated centrifugal mother liquor, adjusting the pH value to 10.0-10.5, stirring to react completely, and filtering to obtain a filter cake, namely a magnesium salt byproduct; and adjusting the pH of the filtrate to 3-5 by using concentrated hydrochloric acid or dilute sulfuric acid, and mechanically applying the filtrate to the next batch of prepared resolving agent.

2. The process for preparing potassium salt and byproduct magnesium salt by using corn steep water as claimed in claim 1, wherein the process comprises the following steps: the strong acid cation resin is gel type strong acid cation resin; the model of the strong acid cation resin is 001 × 16 gel type strong acid cation resin.

3. The process for preparing potassium salt and byproduct magnesium salt by using corn steep water as claimed in claim 1, wherein the process comprises the following steps: and (3) collecting the adsorption effluent liquid in the step (1) and then further extracting phytic acid and lactic acid.

4. The process for preparing potassium salt and byproduct magnesium salt by using corn steep water as claimed in claim 3, wherein the process comprises the following steps: adsorbing phytic acid by the adsorption effluent liquid through anion exchange resin, performing nanofiltration or ultrafiltration on the effluent liquid after adsorbing the phytic acid, and adsorbing the permeate liquid through the anion exchange resin again to obtain the lactic acid.

5. The process for preparing potassium salt and byproduct magnesium salt by using corn steep water as claimed in claim 1, wherein the process comprises the following steps: the ammonium salt resolving agent comprises ammonium chloride or ammonium sulfate; the sodium salt resolving agent comprises sodium sulfate.

6. The process for preparing potassium salt and byproduct magnesium salt by using corn steep water as claimed in claim 5, wherein the process comprises the following steps: when the resolving agent uses ammonium sulfate or sodium sulfate, the obtained potassium salt is potassium sulfate; adjusting the pH of the filtrate obtained in the step (4) by using dilute sulfuric acid; when the resolving agent uses ammonium chloride, the obtained sylvite is potassium chloride; and (4) adjusting the pH of the filtrate in the step (4) by using concentrated hydrochloric acid.

7. The process for preparing potassium salt and byproduct magnesium salt by using corn steep water as claimed in claim 1, wherein the process comprises the following steps: the magnesium removal reagent comprises ammonia water or sodium hydroxide.

8. The process for preparing potassium salt and byproduct magnesium salt by using corn steep water as claimed in claim 7, wherein the process comprises the following steps: when the ammonium salt desorbent is used as the desorbent in the step (2), ammonia water is used as the magnesium removal reagent; when the sodium salt resolving agent is used as the resolving agent, sodium hydroxide is used as the magnesium removing agent.

9. The process for preparing potassium salt and byproduct magnesium salt by using corn steep water as claimed in claim 7, wherein the process comprises the following steps: the mass percentage concentration of the ammonia water is 20%; the mass percentage concentration of the sodium hydroxide is 30%.

10. The process for preparing potassium salt and byproduct magnesium salt by using corn steep water as claimed in claim 1, wherein the process comprises the following steps: the adsorption flow rate in the step (1) is 1.5-2.0 BV/h; the analysis flow rate in the step (2) is 0.5-1.0 BV/h.

Technical Field

The invention relates to the technical field of corn deep processing, in particular to a separation and extraction technology of corn soaking water.

Background

Potassium is an indispensable element for crop growth, and 95 percent of world potassium salt products are used for agricultural fertilizers. China proves that the potassium reserves only account for 2.6 percent of the total reserves in the world, and the method is a country with poor potassium ore resources. The source of the potash fertilizer mainly depends on import, and the imbalance of the proportion of the potash fertilizer seriously restricts the development of agricultural economy in China. Therefore, the development and utilization of potassium resources except minerals make up the current situation of serious shortage of potassium resources in China, so that the agricultural yield is increased, and the method has great economic and strategic significance. Two important varieties on the current domestic potash fertilizer market: the annual demand of potassium sulfate and potassium chloride is about 400 ten thousand tons and 600 ten thousand tons respectively.

The annual consumption of corns in deep processing enterprises in China is close to 7000 ten thousand tons, and the soaking water of the byproduct corns is 3500 ten thousand tons. The existing extraction and separation of corn soaking water generally comprises the extraction preparation of calcium lactate, calcium phytate or potassium phytate. However, in the prior art, potassium ions in the corn soaking water are not reasonably and effectively recovered, and high-salt wastewater or calcium chloride wastewater is difficult to treat, so that the problem of environmental protection is brought.

The potassium content in the corn soaking water is about 0.5 percent, namely the potassium content is 17.5 ten thousand tons, which is equivalent to 39 ten thousand tons of potassium sulfate or 33 ten thousand tons of potassium chloride. Therefore, the simple, economic and feasible technical process is developed, potassium ions in the corn soaking water are converted into potassium salt products, and the method has great economic and social benefits.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: aiming at the defects in the prior art, a process method for preparing potassium salt and a byproduct magnesium salt by using corn soaking water is provided; the process method realizes the comprehensive utilization of corn soaking water resources, obtains potassium salt products such as potassium chloride, potassium sulfate and the like and magnesium salt byproducts, not only realizes the full utilization of the corn soaking water resources, but also brings higher economic benefit and social benefit.

In order to solve the technical problems, the technical scheme of the invention is as follows:

a process method for preparing potassium salt and byproduct magnesium salt by using corn soaking water comprises the following steps:

(1) supernatant fluid of the corn soaking water after standing and settling enters a strong acid cation resin exchange column for adsorption;

(2) adsorbing a saturated cation resin exchange column, ejecting residual corn soaking water by using water, resolving by using 1.5BV and 2mol/L ammonium salt desorbent or sodium salt desorbent, and collecting desorption liquid;

(3) transferring the obtained analytic solution to an MVR continuous concentration crystallizer for vacuum concentration crystallization; transferring the concentrated crystal liquid to a transfer tank, performing solid-liquid separation by using a centrifugal machine, then performing online washing by using water at least 0.5 times of the crystal to obtain a wet potassium salt, and drying to obtain a finished potassium salt product;

(4) adding a magnesium removal reagent into the centrifugally separated centrifugal mother liquor, adjusting the pH value to 10.0-10.5, stirring and reacting completely, and filtering by using a plate frame to obtain a filter cake, namely a magnesium salt byproduct; and adjusting the pH of the filtrate to 3-5 by using concentrated hydrochloric acid, and mechanically applying the filtrate to the next batch for preparing the resolving agent.

As a preferred technical solution, the strong acid cation resin is a gel type strong acid cation resin; the model of the strong acid cation resin is 001 × 16 gel type strong acid cation exchange resin.

As an improved technical scheme, the adsorption effluent in the step (1) is collected and then used for further extracting phytic acid and lactic acid.

Preferably, the adsorption effluent is firstly subjected to adsorption of phytic acid by anion exchange resin, the effluent after adsorption of phytic acid is subjected to nanofiltration or ultrafiltration, and the permeate is subjected to adsorption of anion exchange resin again to obtain lactic acid.

Preferably, the ammonium salt resolving agent comprises ammonium chloride or ammonium sulfate; the sodium salt resolving agent comprises sodium sulfate.

As a preferable technical scheme, when the resolving agent uses ammonium sulfate or sodium sulfate, the obtained potassium salt is potassium sulfate; adjusting the pH of the filtrate obtained in the step (4) by using dilute sulfuric acid; when the resolving agent uses ammonium chloride, the obtained sylvite is potassium chloride; and (4) adjusting the pH of the filtrate in the step (4) by using concentrated hydrochloric acid.

Preferably, the magnesium removing reagent comprises ammonia water or sodium hydroxide.

Preferably, when the ammonium salt desorbent is used as the desorbent in the step (2), ammonia water is used as the magnesium removal reagent; when the sodium salt resolving agent is used as the resolving agent, sodium hydroxide is used as the magnesium removing agent.

As a further preferable technical scheme, the mass percentage concentration of the ammonia water is 20%; the percentage concentration of sodium hydroxide was 30%.

As a preferable technical scheme, the adsorption flow rate in the step (1) is 1.5-2.0 BV/h; the analysis flow rate in the step (2) is 0.5-1.0 BV/h.

As a preferable technical scheme, in the step (4), the mass percent of the concentrated hydrochloric acid is 30%; the mass percentage of the sulfuric acid is 50 percent.

Due to the adoption of the technical scheme, the invention has the beneficial effects that:

the invention relates to a process method for preparing sylvite and byproduct magnesium salt by using corn steep water, which comprises the steps of allowing the supernatant obtained after standing and settling the corn steep water to enter a strong acid cation resin exchange column for adsorption, adsorbing a saturated cation resin exchange column, adopting an ammonium salt desorbent or a sodium salt desorbent for resolution, and obtaining a sylvite product after vacuum concentration crystallization, centrifugal separation and washing of the resolution solution; then centrifuging the mother liquor, adding a magnesium removal reagent for reaction, and filtering to obtain a magnesium salt byproduct; the filtered filtrate is adjusted in pH by concentrated hydrochloric acid and then is applied to the next batch of preparation of the resolving agent. According to the invention, cheap ammonium salt and sodium salt are used as resolving agents to obtain high-added-value potassium salt products (potassium chloride and potassium sulfate), the pH value of a corn soaking water system is not changed in the process, and the separation and extraction of subsequent products such as phytic acid, protein, lactic acid and the like are facilitated; the high-salt crystallization mother liquor is used as the desorbent for the next batch for reuse, thereby avoiding the generation of high-salt wastewater and realizing zero discharge of sewage; and before the centrifugal mother liquor is used mechanically, adding alkali corresponding to the cation of the resolving agent to adjust the pH value to 10.0-10.5, and removing magnesium ions in the centrifugal mother liquor, so that a byproduct magnesium salt is obtained, and the sustainable and stable operation of the whole process is increased.

In the process of removing magnesium ions in the centrifugal mother liquor, when ammonium sulfate or sodium sulfate is used as an analytical agent, the obtained potassium salt is potassium sulfate; adjusting the pH of the filtrate obtained in the step (4) by using sulfuric acid; when the resolving agent uses ammonium chloride, the obtained sylvite is potassium chloride; and (4) adjusting the pH of the filtrate in the step (4) by using concentrated hydrochloric acid. When the ammonium salt desorbent is used as the desorbent, ammonia water is used as the magnesium removal reagent; when sodium salt is used as the resolving agent, sodium hydroxide is used as the magnesium removing agent. The introduced cation is the cation (ammonium ion or sodium ion) corresponding to the resolving agent, and the pH is adjusted to 3-5 with acid corresponding to the anion (chloride ion or sulfate ion) of the resolving agent. Namely, magnesium ions introduced by the raw material of the corn soaking water are removed, a magnesium hydroxide byproduct is obtained, impurity ions are not introduced, the purity of the obtained product and byproduct is high, and the whole system runs stably.

Compared with the common clinoptilolite or macroporous potassium-absorbing resin, the gel type strong acid cation exchange resin 001 x 16 adopted by the invention is not easy to be blocked by organic molecules such as solid suspension, protein and the like in the corn soaking water, and has the advantages of strong pollution resistance and long service life. And the resin has large exchange capacity: the exchange capacity of the resin is more than or equal to 2.4mmol/mL, and the adsorption capacity is more than or equal to 1.8mmol/mL of the conventional potassium absorbing materials such as clinoptilolite, potassium absorbing resin and the like.

Detailed Description

The invention is further illustrated below with reference to specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.

Example 1

(1) Taking 600L of supernatant obtained after the corn soaking water is settled for 4 hours, (the potassium ion content in the supernatant is 0.55%, and the magnesium ion content in the supernatant is 0.15%), feeding the supernatant into a cation resin exchange column at the flow rate of 1.5BV/h to adsorb potassium ions, wherein the resin is 001 x 16 in model and the volume is 50L; the adsorption effluent is used for extracting and separating other products such as phytic acid, protein, lactic acid and the like.

(2) Adsorbing a saturated cation resin exchange column, ejecting residual corn soaking water by using water, feeding 1.5BV of ammonium chloride solution with the ammonium ion concentration of 2mol/L to resolve the resin, and feeding 1.5BV of water to wash the resin column after feeding; the analysis flow rate is 0.5 BV/h.

(3) Transferring the analytic solution to an MVR continuous concentration crystallizer for vacuum concentration crystallization; transferring the concentrated crystal liquid to a transfer tank, performing solid-liquid separation by using a centrifugal machine, washing the crystal liquid on line by using 3L of water, and drying to obtain 5.7kg of potassium chloride product with the potassium oxide content of more than or equal to 62% (other indexes meet the powder crystal I type standard of fertilizer grade potassium chloride GBT 37918-2019); the centrifugal mother liquor is used as an analysis agent for the next batch of analysis.

(4) Adding 20% ammonia water into the centrifugal mother liquor to adjust the pH value to 10.0-10.5, stirring and reacting completely, and filtering. 1.2kg of magnesium hydroxide byproduct is obtained, and the pH of the filtrate is adjusted to 3-5 by 30 percent concentrated hydrochloric acid and is applied to the next batch of the filtrate to be used as a resolving agent.

Example 2

(1) Taking 600L of supernatant (potassium ion content is 0.55%, magnesium ion content is 0.15%) of corn soaking water after 4h sedimentation, and feeding the supernatant into a cation resin exchange column at a flow rate of 1.8BV/h to adsorb potassium ions, wherein the resin is 001 x 16 in volume of 50L; the adsorption effluent is used for extracting and separating other products such as phytic acid, protein, lactic acid and the like.

(2) Adsorbing a saturated cation resin exchange column, after water is used for ejecting residual corn soaking water, feeding 1.8BV ammonium sulfate solution with ammonium ion concentration of 2mol/L to resolve the resin, and feeding 1.8BV water to wash the resin column after the resin is completely fed; the analysis flow rate is 0.6 BV/h.

(3) Transferring the analytic solution to an MVR continuous concentration crystallizer for vacuum concentration crystallization; transferring the concentrated crystal liquid to a transfer tank, performing solid-liquid separation by using a centrifuge, washing the crystal liquid on line by using 3L of water, and drying to obtain 6.72kg of potassium sulfate product with the potassium oxide content of more than or equal to 52% (other indexes meet the powder crystal I standard of fertilizer-grade potassium chloride GBT 37918-2019); the centrifugal mother liquor is used as an analysis agent for the next batch of analysis.

(4) Adding 20% ammonia water into the centrifugal mother liquor to adjust the pH value to 10.0-10.5, stirring and reacting completely, and filtering. 1.2kg of magnesium hydroxide byproduct is obtained, and the pH of the filtrate is adjusted to 3-5 by 50% sulfuric acid and is indiscriminately used as a resolving agent in the next batch.

Example 3

(1) Taking 600L of supernatant (potassium ion content is 0.55%, magnesium ion content is 0.15%) of corn soaking water after 4h sedimentation, and feeding the supernatant into a cation resin exchange column at a flow rate of 1.6BV/h to adsorb potassium ions, wherein the resin is 001 x 16 in volume of 50L; the adsorption effluent is used for extracting and separating other products such as phytic acid, protein, lactic acid and the like.

(2) Adsorbing a saturated cation resin exchange column, ejecting residual corn soaking water by using water, feeding 1.5BV of sodium sulfate solution with the sodium ion concentration of 2mol/L to resolve the resin, and feeding 1.5BV of water to wash the resin column after the resin is completely fed; the analysis flow rate is 0.8 BV/h.

(3) Transferring the analytic solution to an MVR continuous concentration crystallizer for vacuum concentration crystallization; transferring the concentrated crystal liquid to a transfer tank, performing solid-liquid separation by using a centrifuge, washing the crystal liquid on line by using 2.5L of water, and drying to obtain 6.7kg of potassium sulfate product with the potassium oxide content of more than or equal to 52% (other indexes meet the powder crystal I type standard of fertilizer grade potassium chloride GBT 37918-2019); the centrifugal mother liquor is used as an analysis agent for the next batch of analysis.

(4) Adding 30% liquid sodium hydroxide into the centrifugal mother liquor to adjust the pH value to 10.0-10.5, stirring and reacting completely, and filtering. 1.2kg of magnesium hydroxide byproduct is obtained, and the pH of the filtrate is adjusted to 3-5 by 50% sulfuric acid and is indiscriminately used as a resolving agent in the next batch.

Example 4

(1) Taking 600L of supernatant (potassium ion content is 0.55%, magnesium ion content is 0.15%) of corn soaking water after 4h sedimentation, and feeding the supernatant into a cation resin exchange column at a flow rate of 1.5BV/h to adsorb potassium ions, wherein the resin is 001 x 16 in volume of 50L; the adsorption effluent is used for extracting and separating other products such as phytic acid, protein, lactic acid and the like.

(2) Adsorbing a saturated cation resin exchange column, ejecting residual corn soaking water by using water, preparing 1.5BV of ammonium chloride solution with ammonium ion concentration of 2mol/L from the resolving agent ammonium chloride solution obtained in the step (4) in the embodiment 1 into an ammonium chloride solution resolving resin, and feeding 1.5BV of water to wash the resin column after the solution is completely fed; the analysis flow rate is 0.5 BV/h.

(3) Transferring the analytic solution to an MVR continuous concentration crystallizer for vacuum concentration crystallization; transferring the concentrated crystal liquid to a transfer tank, performing solid-liquid separation by using a centrifugal machine, washing the crystal liquid on line by using 3L of water, and drying to obtain 5.69kg of potassium chloride product with the potassium oxide content of more than or equal to 62% (other indexes meet the powder crystal I type standard of fertilizer grade potassium chloride GBT 37918-2019); the centrifugal mother liquor is used as an analysis agent for the next batch of analysis.

(4) Adding 20% ammonia water into the centrifugal mother liquor to adjust the pH value to 10.0-10.5, stirring and reacting completely, and filtering. 1.2kg of magnesium hydroxide byproduct is obtained, and the pH of the filtrate is adjusted to 3-5 by 30 percent concentrated hydrochloric acid and is applied to the next batch of the filtrate to be used as a resolving agent.

Example 5

(1) Taking 600L of supernatant (potassium ion content is 0.55%, magnesium ion content is 0.15%) of corn soaking water after 4h sedimentation, and feeding the supernatant into a cation resin exchange column at a flow rate of 1.5BV/h to adsorb potassium ions, wherein the resin is 001 x 16 in volume of 50L; the adsorption effluent is used for extracting and separating other products such as phytic acid, protein, lactic acid and the like.

(2) Adsorbing a saturated cation resin exchange column, ejecting residual corn soaking water by using water, preparing 1.5BV of ammonium chloride solution with ammonia ion concentration of 2mol/L from the ammonium chloride solution serving as the resolving agent obtained in the step (4) in the embodiment 4, and washing the resin column by using 1.5BV of water after the solution is completely fed; the analysis flow rate is 0.5 BV/h.

(3) Transferring the analytic solution to an MVR continuous concentration crystallizer for vacuum concentration crystallization; transferring the concentrated crystal liquid to a transfer tank, performing solid-liquid separation by using a centrifugal machine, washing the crystal liquid on line by using 3L of water, and drying to obtain 5.68kg of potassium chloride product with the potassium oxide content of more than or equal to 62% (other indexes meet the powder crystal I type standard of fertilizer grade potassium chloride GBT 37918-2019); the centrifugal mother liquor is used as an analysis agent for the next batch of analysis.

(4) Adding 20% ammonia water into the centrifugal mother liquor to adjust the pH value to 10.0-10.5, stirring and reacting completely, and filtering. 1.2kg of magnesium hydroxide byproduct is obtained, and the pH of the filtrate is adjusted to 3-5 by 30 percent concentrated hydrochloric acid and is applied to the next batch of the filtrate to be used as a resolving agent.

Comparative test example 1

Comparative test example 1 differs from examples 1, 4 and 5 in that the used resolving agent was an ammonium chloride solution obtained in step (3) of example 1, i.e., a centrifuged mother liquor without removing magnesium ions. The potassium chloride product with the potassium oxide content of more than or equal to 62 percent is obtained after analysis, vacuum concentration, centrifugal separation and drying in comparative test example 1 (other indexes all meet the powder crystal I type standard of fertilizer-grade potassium chloride GBT 37918-2019).

Comparative test example 2

Comparative test example 2 is different from comparative test example 1 in that the used resolving agent is an ammonium chloride solution obtained by centrifugal separation in comparative example 1, that is, a centrifugal mother liquor without magnesium ion removal is reused. Comparative test example 2 was analyzed, vacuum-concentrated, centrifugally separated, and dried to obtain 5.0kg of a potassium chloride product having a potassium oxide content of not less than 62% (other indexes all meet the type I standard of powder crystals in "fertilizer-grade potassium chloride GBT 37918-2019").

From the experimental results of the above examples 1-5 and comparative test examples 1-2, it can be seen that the potassium salt product obtained by separation and extraction in the present invention can completely meet the standard requirements of fertilizer-grade potassium chloride or potassium sulfate, and the system runs stably after the centrifugal mother liquor is reused for many times, and is hardly affected. In contrast, in comparative test examples 1 and 2, when the centrifugal mother liquor without removing magnesium ions was recovered and reused, not only was no magnesium salt byproduct obtained, but also the potassium salt product was obtained, and the yield was significantly reduced. The analysis reason is that the corn soaking water contains more magnesium ions which are absorbed by the resin together with potassium ions. The method has no outlet in the analysis system, continuous enrichment is realized, the magnesium content in the analysis liquid is continuously increased, the yield of concentrating, crystallizing and separating potassium salt is influenced, and the balance of the whole system is broken.