A process for recovering magnesium ions in corn soaking water to produce magnesium sulfate heptahydrate

Abstract

The present application relates to the technical field of corn soaking water treatment, and particularly relates to a process method for recovering magnesium ions in corn soaking water to produce magnesium sulfate heptahydrate, comprising the following steps: (1) taking corn soaking water, and passing supernatant after standing and settling into a cation resin column, and collecting a first effluent for standby; (2) using purified water to flush the cation resin column; then using sulfuric acid to continue flushing the cation resin column, and collecting a third effluent for standby; (3) taking the third effluent, and passing concentrated liquid obtained through concentration treatment to adjust pH to weak acidity, and collecting filtrate for standby; (4) taking the filtrate, and passing crystals collected through cooling and centrifugation to obtain magnesium sulfate heptahydrate products through drying. The process method is reasonable in design, simple in operation, can effectively recover magnesium ions in corn soaking water, and greatly improves the yield, yield and purity of magnesium sulfate heptahydrate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of corn soaking water treatment, and particularly relates to a process method for recovering magnesium ions in corn soaking water to produce magnesium sulfate heptahydrate. BACKGROUND

[0002] Corn soaking water is a by-product produced in the process of wet production of corn starch, which contains calcium, magnesium, potassium, phosphorus (phytic acid), lactic acid, protein and other resources. There are reports on the recovery of potassium and phosphorus resources from corn soaking water to produce inositol and potassium phosphate fertilizer. In the existing process, magnesium elements are removed as impurities affecting the clarity of the product during the production process, which not only increases the production cost, but also causes resource waste. If the magnesium elements in the corn soaking water can be recovered in advance, not only can the production cost of inositol and potassium phosphate fertilizer be reduced, the product quality can be improved, but also magnesium salt can be produced, further improving the comprehensive utilization value of corn soaking water.

[0003] Currently, there is a process method for preparing potassium salt and co-producing magnesium salt from corn soaking water, but the magnesium salt obtained by the method is magnesium hydroxide. There are also reports on a process method for preparing potassium dihydrogen phosphate and magnesium hydrogen phosphate from corn soaking water, and the magnesium salt obtained by the method is magnesium hydrogen phosphate. In addition, there are reports on a process method for preparing DL-magnesium lactate and phytic acid desorbent from corn soaking water, and the obtained product is DL-magnesium lactate. Although the above-mentioned process methods all obtain corresponding magnesium salt products, which realize the recovery of magnesium ions in corn soaking water, but the corn soaking water contains calcium ions, and when the corn soaking water passes through the cation resin column, calcium ions, potassium ions and magnesium ions are simultaneously adsorbed. Therefore, the magnesium salt obtained by the above-mentioned process methods all contains calcium, which greatly reduces the purity of the magnesium salt. Therefore, in view of the above problems, it is necessary to develop a process method for recovering magnesium ions in corn soaking water to produce magnesium sulfate heptahydrate. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a process method for recovering magnesium ions in corn soaking water to produce magnesium sulfate heptahydrate, which can effectively recover magnesium ions in corn soaking water and obtain high-purity, high-yield and high-yield magnesium sulfate products.

[0005] To solve the above technical problems, the technical scheme of the present application is:

[0006] A process method for recovering magnesium ions in corn soaking water to produce magnesium sulfate heptahydrate, comprising the following steps:

[0007] (1) Take corn soaking water, and the supernatant after standing and settling is introduced into a cation resin column, and a first effluent is collected for standby use;

[0008] (2) using purified water to rinse the cation resin column in step (1), and collecting the second effluent for standby; and using sulfuric acid to continue rinsing the cation resin column, and collecting the third effluent for standby;

[0009] (3) taking the third effluent in step (2), and adjusting the pH of the concentrated solution obtained through concentration treatment to be weakly acidic, and collecting the filtrate for standby;

[0010] (4) taking the filtrate in step (3), and obtaining the magnesium sulfate product through drying of the crystal collected through cooling and centrifugation.

[0011] As an improved technical solution, the filler in the cation resin column in step (1) is a macroporous cation resin containing an aminomethyl phosphonic group.

[0012] As an improved technical solution, the supernatant in step (1) enters at a flow rate of 1-2 BV / h.

[0013] As an improved technical solution, the purified water in step (2) rinses the cation resin column at a flow rate of 2-3 BV / h, and the amount of the purified water is 2-3 BV of the volume of the resin column.

[0014] As an improved technical solution, the sulfuric acid in step (2) is 5-7 v / v%, the sulfuric acid rinses the cation resin column at a flow rate of 1-2 BV / h, and the amount of the sulfuric acid is 1.5-2.5 BV of the volume of the resin column.

[0015] As an improved technical solution, the solid content of the concentrated solution in step (3) is controlled to be 35-45 wt%.

[0016] As an improved technical solution, magnesium hydroxide is added in step (3) to adjust the pH to 5-6.

[0017] As an improved technical solution, the filtrate in step (4) is cooled to 25-35℃.

[0018] After the above technical solution is adopted, the application has the following beneficial effects:

[0019] The present application takes the supernatant of corn soaking water after standing as raw material, and when passing through a cation resin column, the calcium and magnesium ions in the corn soaking water are effectively adsorbed by the chelate cation resin, and most of the potassium ions, protein molecules and phytic acid in the corn soaking water flow out as components of the first effluent; the protein molecules, phytic acid and potassium ions in the resin column are first flushed out by using purified water, then the calcium and magnesium ions adsorbed by the resin are eluted into the third effluent by using sulfuric acid as an eluent, and then the third effluent is concentrated, magnesium hydroxide is added to adjust the pH, calcium precipitate is removed by filtration, and the collected filtrate is cooled, filtered and dried to obtain the magnesium sulfate product. The above process method is reasonable in design, simple in operation, can effectively recover the magnesium ions in the corn soaking water, and greatly improves the yield, yield and purity of the magnesium sulfate heptahydrate. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical scheme and advantages of the present application clearer and more apparent, the present application will be further described in detail below with examples. It should be understood that the specific examples described herein are only used to explain the present application and not to limit the present application.

[0021] Example 1

[0022] A process method for recovering magnesium ions in corn soaking water to produce magnesium sulfate heptahydrate, comprising the following steps:

[0023] (1) Take the supernatant of corn soaking water after standing and sedimentation 1000L (equivalent to 2.92kg of magnesium hydroxide), and make it enter a 50L cation resin column (macroporous cation resin containing aminomethyl phosphonic acid group) at a flow rate of 1BV / h, and collect the first effluent for standby;

[0024] (2) Use 100L of purified water to flush the cation resin column in step (1) at a flow rate of 2BV / h, and collect the second effluent for standby; then use 125L of 5v / v% sulfuric acid to continue flushing the cation resin column at a flow rate of 1BV / h, and collect 125L of third effluent for standby;

[0025] (3) Take the third effluent 125L in step (2), concentrate to obtain a concentrated solution with a solid content of 35wt%, add magnesium hydroxide to adjust the pH to 5, and collect 30L of filtrate by filtration for standby;

[0026] (4) Take the filtrate 30L in step (3), cool to 25℃, and collect the crystals by centrifugation to obtain 10.2kg of magnesium sulfate heptahydrate product by drying, with a yield of 61.8% and a purity of 96%.

[0027] Example 2

[0028] A process for recovering magnesium ions in corn soaking water to produce magnesium sulfate heptahydrate, comprising the following steps:

[0029] (1) Take the supernatant of corn soaking water after standing and settling 1000L (equivalent to 2.92kg of magnesium hydroxide), and enter a 50L cation resin column (macroporous cation resin containing aminomethyl phosphonic acid group) at a flow rate of 1.2BV / h, and collect the first effluent for standby;

[0030] (2) Use 115L of purified water to flush the cation resin column in step (1) at a flow rate of 2.3BV / h, and collect the second effluent for standby; then use 115L of 5.5v / v% sulfuric acid to continue flushing the cation resin column at a flow rate of 1.2BV / h, and collect 115L of the third effluent for standby;

[0031] (3) Take the third effluent 115L in step (2), concentrate to obtain a concentrated solution with a solid content of 38wt%, add magnesium hydroxide, adjust the pH to 5.3, filter and collect 28L of filtrate for standby;

[0032] (4) Take the filtrate 28L in step (3), cool to 28℃, centrifuge to collect the crystals, and dry to obtain 10.8kg of magnesium sulfate heptahydrate product, with a yield of 65.1% and a purity of 96.3%.

[0033] Example 3

[0034] A process for recovering magnesium ions in corn soaking water to produce magnesium sulfate heptahydrate, comprising the following steps:

[0035] (1) Take the supernatant of corn soaking water after standing and settling 1000L (equivalent to 2.92kg of magnesium hydroxide), and enter a 50L cation resin column (macroporous cation resin containing aminomethyl phosphonic acid group) at a flow rate of 1.2BV / h, and collect the first effluent for standby;

[0036] (2) Use 115L of purified water to flush the cation resin column in step (1) at a flow rate of 2.3BV / h, and collect the second effluent for standby; then use 115L of 5.5v / v% sulfuric acid to continue flushing the cation resin column at a flow rate of 1.2BV / h, and collect 115L of the third effluent for standby;

[0037] (3) Take the third effluent 115L in step (2), concentrate to obtain a concentrated solution with a solid content of 38wt%, add magnesium hydroxide, adjust the pH to 5.3, filter and collect 28L of filtrate for standby;

[0038] (4) Take the filtrate 28L in step (3), cool to 28℃, centrifuge to collect the crystals, and dry to obtain 10.8kg of magnesium sulfate heptahydrate product, with a yield of 65.1% and a purity of 96.3%.

[0039] Example 4

[0040] A process for recovering magnesium ions in corn soaking water to produce magnesium sulfate heptahydrate, comprising the following steps:

[0041] (1) Take the supernatant of corn soaking water after standing and settling 1000L (equivalent to 2.92 kg of magnesium hydroxide), and enter a 50L cation resin column (macroporous cation resin containing aminomethyl phosphonic acid group) at a flow rate of 1.8BV / h, and collect the first effluent for standby;

[0042] (2) Use 140L of purified water to flush the cation resin column in step (1) at a flow rate of 2.8BV / h, and collect the second effluent for standby; then use 90L of 6.5v / v% sulfuric acid to continue flushing the cation resin column at a flow rate of 1.8BV / h, and collect 90L of the third effluent for standby;

[0043] (3) Take the third effluent 90L in step (2), concentrate to obtain a concentrated solution with a solid content of 42wt%, add magnesium hydroxide, adjust the pH to 5.8, filter and collect 23L of filtrate for standby;

[0044] (4) Take the filtrate 23L in step (3), cool to 32℃, and centrifuge to collect the crystals, which are dried to obtain 10.6Kg of magnesium sulfate heptahydrate product, with a yield of 64.8% and a purity of 97.8%.

[0045] Example 5

[0046] A process for recovering magnesium ions in corn soaking water to produce magnesium sulfate heptahydrate, comprising the following steps:

[0047] (1) Take the supernatant of corn soaking water after standing and settling 1000L (equivalent to 2.92 kg of magnesium hydroxide), and enter a 50L cation resin column (macroporous cation resin containing aminomethyl phosphonic acid group) at a flow rate of 1.8BV / h, and collect the first effluent for standby;

[0048] (2) Use 140L of purified water to flush the cation resin column in step (1) at a flow rate of 2.8BV / h, and collect the second effluent for standby; then use 90L of 6.5v / v% sulfuric acid to continue flushing the cation resin column at a flow rate of 1.8BV / h, and collect 90L of the third effluent for standby;

[0049] (3) Take the third effluent 90L in step (2), concentrate to obtain a concentrated solution with a solid content of 42wt%, add magnesium hydroxide, adjust the pH to 5.8, filter and collect 23L of filtrate for standby;

[0050] (4) Take the filtrate 20L in step (3), cool to 35℃, and collect the crystal by centrifugation. After drying, 10.3Kg of magnesium sulfate heptahydrate product is obtained, with a yield of 62.3% and a purity of 98.0%.

[0051] In order to better prove that the process of the present application can effectively recover magnesium ions in corn soaking water, while obtaining a high yield, high yield and high purity of magnesium sulfate heptahydrate product, 11 comparative examples are given with reference to Example 3, which are described in detail below:

[0052] Comparative Example 1

[0053] Different from Example 3, the filler of the cation resin column in step (1) is (001 x 16 strong acid cation exchange resin), and the rest of the operations are the same; in step (4), 8.5kg of magnesium sulfate heptahydrate product is obtained, with a yield of 21.3% and a purity of 58.5%.

[0054] Comparative Example 2

[0055] Different from Example 3, 3v / v% sulfuric acid is used to flush the resin column in step (2), and the rest of the operations are the same; in step (4), 7.8kg of magnesium sulfate heptahydrate product is obtained, with a yield of 53.8% and a purity of 96.5%.

[0056] Comparative Example 3

[0057] Different from Example 3, 8v / v% sulfuric acid is used to flush the resin column in step (2), and the rest of the operations are the same; in step (4), 15.7kg of magnesium sulfate product is obtained, with a yield of 72.6% and a purity of 96.5%.

[0058] Comparative Example 4

[0059] Different from Example 3, the solid content of the concentrated solution in step (3) is controlled at 30wt%, and the rest of the operations are the same; in step (4), 9.8kg of magnesium sulfate heptahydrate product is obtained, with a yield of 60.2% and a purity of 97.9%.

[0060] Comparative Example 5

[0061] Different from Example 3, the solid content of the concentrated solution in step (3) is controlled at 50wt%, and the rest of the operations are the same; in step (4), 11.6kg of magnesium sulfate heptahydrate product is obtained, with a yield of 74.7% and a purity of 95.2%.

[0062] Comparative Example 6

[0063] Different from Example 3, the filtrate is cooled to 20℃ in step (4), and the rest of the operations are the same; in step (4), 11.9kg of magnesium sulfate heptahydrate product is obtained, with a yield of 72.8% and a purity of 95.5%.

[0064] Comparative Example 7

[0065] Different from Example 3, the filtrate was cooled to 40℃ in step (4), and the rest of the operations were the same; the product of magnesium sulfate heptahydrate in step (4) was 10.9 kg, the yield was 67.4%, and the purity was 98.1%.

[0066] Comparative Example 8

[0067] Different from Example 3, the pH was adjusted to 4.5 in step (3), and the rest of the operations were the same; the product of magnesium sulfate heptahydrate in step (4) was 9.1 kg, the yield was 68.5%, and the purity was 98.0%.

[0068] Comparative Example 9

[0069] Different from Example 3, the pH was adjusted to 8 in step (3), and the rest of the operations were the same; the product of magnesium sulfate heptahydrate in step (4) was 18.5 kg, the yield was 68.3%, and the purity was 88.2%.

[0070] Comparative Example 10

[0071] Different from Example 3, the purified water was used to flush the resin column at a flow rate of 1 BV / h in step (2), and the rest of the operations were the same; the product of magnesium sulfate heptahydrate in step (4) was 11.4 kg, the yield was 69.7%, and the purity was 96.3%.

[0072] Comparative Example 11

[0073] Different from Example 3, the sulfuric acid was used to flush the resin column at a flow rate of 0.5 BV / h in step (2), and the rest of the operations were the same; the product of magnesium sulfate heptahydrate in step (4) was 10.4 kg, the yield was 62.2%, and the purity was 96.6%.

[0074] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, and improvement within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A process for the recovery of magnesium ions from corn steep liquor for the production of magnesium sulfate heptahydrate, characterized in that The method comprises the following steps: (1) corn soaking water is taken, and supernatant after standing and sedimentation is introduced into a cation resin column, and the first effluent is collected for standby; the filler in the cation resin column is macroporous cation resin containing aminomethyl phosphonic acid group; (2) the cation resin column in step (1) is washed with purified water, and the second effluent is collected for standby; the cation resin column is further washed with sulfuric acid, and the third effluent collected is standby; the sulfuric acid is 5-7 v / v%, the sulfuric acid is used to wash the cation resin column at a flow rate of 1-2 BV / h, and the amount of the sulfuric acid is 1.5-2.5 BV of the volume of the resin column; (3) the third effluent in step (2) is taken, the concentrated liquid obtained by concentration treatment is added with magnesium hydroxide to adjust pH to 5-6, and the collected filtrate is standby after filtration; the solid content of the concentrated liquid is controlled to be 35-45 wt%; (4) the filtrate in step (3) is taken, cooled to 25-35 DEG C, and the collected crystal after centrifugation is dried to obtain a magnesium sulfate product.

2. The process for the production of magnesium sulfate heptahydrate from magnesium ions in corn steep liquor according to claim 1, characterized in that: The supernatant in step (1) is introduced at a flow rate of 1-2 BV / h.

3. The process for the production of magnesium sulfate heptahydrate from magnesium ions in corn steep liquor according to claim 1, characterized in that: In step (2), the cation resin column is washed with purified water at a flow rate of 2-3 BV / h, and the amount of the purified water is 2-3 BV of the volume of the resin column.