Method for high-value utilization of mirabilite resources

Abstract

The invention discloses a method for high-value utilization of mirabilite resources, which comprises the following steps: purifying and refining mirabilite to obtain a sodium sulfate saturated solution; the method comprises the following steps: adding potassium chloride into a sodium sulfate saturated solution, carrying out first reaction, and carrying out solid-liquid separation to obtain glaserite and mother liquor A; mixing glaserite, potassium chloride and water, carrying out a reaction II, carrying out solid-liquid separation to obtain wet potassium sulfate and mother liquor B, and drying the wet potassium sulfate to obtain a potassium sulfate product; evaporating and crystallizing the mother liquor A to obtain mother liquor C and wet sodium chloride, and drying the wet sodium chloride to obtain a sodium chloride product; returning the mother liquor C and the mother liquor B to react with sodium sulfate and potassium chloride, performing solid-liquid separation to obtain mother liquor A and glaserite, returning the mother liquor A to be evaporated and crystallized for preparing sodium chloride, and returning the glaserite for preparing potassium sulfate. According to the method for high-value utilization of the mirabilite resource, the conversion rate of sodium sulfate is high, the utilization rate of sodium sulfate reaches 99%, and obtained potassium sulfate and sodium chloride products are high in purity.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical industry, and more specifically, relates to a method for high-value utilization of mirabilite resources. Background Art

[0002] Sodium sulfate, also known as sodium sulfate, contains crystal water as Glauber's salt. It is an industrial by-product with a huge stock, mainly produced in flue gas desulfurization, wastewater treatment and other processes. Glauber's salt is mainly used in detergent and sodium sulfide industries, followed by pulp, man-made fiber and glass industries. The sodium sulfate produced by industrial production has low added value, narrow application fields, and no very effective resource utilization methods. Most of them are mainly stored; and sodium sulfate is easily soluble in water. The sodium sulfate produced by some enterprises contains a large amount of heavy metals, such as vanadium, chromium, zinc, etc., and the storage is very likely to cause environmental problems. Therefore, how to provide a method with high sodium sulfate utilization rate, low energy consumption and high recycling efficiency is still of great significance. Summary of the invention

[0003] An object of the present invention is to solve at least the above problems and / or disadvantages and to provide at least the advantages which will be described hereinafter.

[0004] In order to achieve these purposes and other advantages of the present invention, a method for high-value utilization of mirabilite resources is provided, comprising the following steps:

[0005] Step 1: removing impurities and refining the mirabilite to obtain a saturated sodium sulfate solution;

[0006] Step 2: adding potassium chloride to a saturated sodium sulfate solution to carry out reaction 1, and separating the solid from the liquid to obtain glauberite and mother liquor A;

[0007] Step 3: Mixing glauber's salt, potassium chloride and water to carry out reaction 2, separating the solid and liquid to obtain wet potassium sulfate and mother liquor B, and drying the wet potassium sulfate to obtain a potassium sulfate product;

[0008] Step 4, evaporating and crystallizing the mother liquor A to obtain mother liquor C and wet sodium chloride, and drying the wet sodium chloride to obtain a sodium chloride product;

[0009] Step 5: Return the mother liquor C and the mother liquor B to step 2, react with sodium sulfate and potassium chloride, separate the solid and liquid to obtain mother liquor A and glauberite, return the mother liquor A to step 4 for evaporation and crystallization to prepare sodium chloride, and return the glauberite to step 3 for preparation of potassium sulfate.

[0010] Preferably, in step 1, the thenardite can be replaced by other sodium sulfate raw materials, including but not limited to anhydrous thenardite, sodium sulfate decahydrate, glauber's salt, impure thenardite, thenardite aqueous solution and sodium sulfate solution.

[0011] Preferably, in the step 1, the thenardite is chromium-containing thenardite.

[0012] Preferably, the chromium-containing sodium sulfate comprises the following components based on its total weight: 70-97 wt % of sodium sulfate, 2-29 wt % of water and 0.01-1.0 wt % of hexavalent chromium (calculated as sodium chromium dichromate).

[0013] Preferably, in the step 1, the specific method for removing impurities and refining the mirabilite is: adding mirabilite into water to dissolve it, adding sulfuric acid to adjust the pH value to 2-3, adding excess sodium pyrosulfite as a reducing agent, stirring to react, then adding sodium hydroxide to adjust the pH value to 8-9, stirring to produce precipitation, and separating the solid and liquid to obtain a saturated sodium sulfate solution.

[0014] Preferably, the mass ratio of the thenardite to water is 1:1-3; and the amount of sodium pyrosulfite added is 1.1-2.0 times the amount required to completely reduce the hexavalent chromium in the thenardite to trivalent chromium.

[0015] Preferably, the sulfuric acid for adjusting the pH value may be concentrated sulfuric acid or a sulfuric acid aqueous solution; the sodium hydroxide for adjusting the pH value may be pure sodium hydroxide or a sodium hydroxide aqueous solution; when a sulfuric acid aqueous solution or a sodium hydroxide aqueous solution is used to adjust the pH value, the amount of water introduced by adding the sulfuric acid aqueous solution or the sodium hydroxide aqueous solution should be such that the sodium sulfate aqueous solution obtained after the hexavalent chromium is reduced to trivalent chromium is a saturated solution.

[0016] Preferably, in step 2, the mass ratio of potassium chloride to saturated sodium sulfate solution is 1:2-5.

[0017] Preferably, in step 2 and step 5, the reaction temperature of reaction 1 is 20-60° C., and the reaction time is 1-3 h.

[0018] Preferably, in step three, the reaction temperature of reaction two is 20 to 60° C., and the reaction time is 1 to 3 hours.

[0019] Preferably, in step 3, the mass ratio of glauberite, potassium chloride and water is 1:0.5 to 1:1 to 3.

[0020] Preferably, in step 4, the evaporation crystallization temperature is 90-140°C.

[0021] Preferably, in step three and step four, the drying temperature is 140-150°C.

[0022] Preferably, in step five, the mass ratio of mother liquor C, mother liquor B, sodium sulfate and potassium chloride is 1:0.1-0.3:0.05-0.3:0.01-0.04.

[0023] Preferably, in the step 1, the specific method for removing impurities and refining the mirabilite is: adding mirabilite into water to dissolve, adding sulfuric acid to adjust the pH value to 2-3, adding excess sodium pyrosulfite as a reducing agent, turning on radio frequency and microwave to treat the reaction solution for 5-15 minutes, then adding sodium hydroxide to adjust the pH value to 8-9, stirring to produce precipitation, separating the solid and the liquid, and obtaining a saturated sodium sulfate solution; wherein the specific parameters for treating the reaction solution with radio frequency and microwave are: radio frequency frequency of 27.12 MHz, radio frequency power of 200-500 W, microwave frequency of 2450 MHz, and microwave power of 300-900 W.

[0024] The present invention at least includes the following beneficial effects: the present invention provides a method for high-value utilization of mirabilite resources, the sodium sulfate conversion rate is high, the sodium sulfate utilization rate can reach 99%, the obtained potassium sulfate and sodium chloride products are of high purity, the potassium oxide content in the potassium sulfate is ≥52.00%, and the sodium chloride purity is ≥99%, both of which meet the national standards; the present invention only uses sodium sulfate and potassium chloride as raw materials, and no other additives are added, so the product purity is high, no impurity removal operation is required, the production cost and production time are saved, and the mother liquor is recycled; in addition, the present invention only uses the evaporation operation during the evaporation in step four, so the present invention has the advantage of low energy consumption, and the present invention does not discharge the three wastes, and all materials are recycled in the system.

[0025] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0028] It should be understood that the terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0029] In the following embodiments, the sodium sulfate used is chromium-containing sodium sulfate, and its main components include: 93wt% sodium sulfate, 6.5wt% water, and 0.1wt% hexavalent chromium (calculated as sodium chromium dichromate).

[0030] Example 1

[0031] A method for high-value utilization of mirabilite resources comprises the following steps:

[0032] Step 1, by weight, add 1 part of Glauber's salt to 2 parts of water to dissolve, add sulfuric acid to adjust the pH value to 2, add 0.002 parts of sodium pyrosulfite as a reducing agent to reduce hexavalent chromium to trivalent chromium, then add sodium hydroxide to adjust the pH value to 8, continue stirring to convert the trivalent chromium into chromium hydroxide precipitate, and obtain a saturated sodium sulfate solution and chromium hydroxide slag by solid-liquid separation;

[0033] Step 2: Add 1 part of potassium chloride to 3 parts of saturated sodium sulfate solution, react at room temperature for 2 hours, and separate the solid and liquid to obtain potassium sulfate and mother liquor A;

[0034] Step 3: Mix 1 part of glauber's salt, 0.7 part of potassium chloride and 2 parts of water, react at room temperature for 2 hours, separate the solid and liquid to obtain wet potassium sulfate and mother liquor B, and dry the wet potassium sulfate at 140° C. to obtain a potassium sulfate product;

[0035] Step 4, evaporating and crystallizing the mother liquor A at 110° C. to obtain mother liquor C and wet sodium chloride, and drying the wet sodium chloride at 140° C. to obtain a sodium chloride product;

[0036] Step 5: Mix 1 part of mother liquor C, 0.25 parts of mother liquor B, 0.1 parts of sodium glauberite and 0.025 parts of potassium chloride, react at room temperature for 2 hours, separate the solid and liquid to obtain mother liquor A and glauberite, return mother liquor A to step 4 for evaporation and crystallization to prepare sodium chloride, and return glauberite to step 3 for preparation of potassium sulfate.

[0037] In this embodiment, the potassium sulfate product prepared has a potassium oxide content of 52.36%, a sodium chloride product purity of 99.28%, and a sodium sulfate utilization rate of 99%.

[0038] Draw the process flow chart of this embodiment, such as Figure 1 shown.

[0039] Example 2

[0040] A method for high-value utilization of mirabilite resources comprises the following steps:

[0041] Step 1: by weight, add 1 part of Glauber's salt (containing a trace amount of hexavalent chromium) to 2 parts of water to dissolve, add sulfuric acid to adjust the pH value to 2, add 0.002 parts of sodium pyrosulfite as a reducing agent to reduce the hexavalent chromium to trivalent chromium, then add sodium hydroxide to adjust the pH value to 8, continue stirring to convert the trivalent chromium into chromium hydroxide precipitate, and obtain a saturated sodium sulfate solution and chromium hydroxide slag by solid-liquid separation;

[0042] Step 2: Add 1 part of potassium chloride to 3 parts of saturated sodium sulfate solution, react at room temperature for 2 hours, and separate the solid and liquid to obtain potassium sulfate and mother liquor A;

[0043] Step 3: Mix 1 part of glauber's salt, 0.7 part of potassium chloride and 2 parts of water, react at room temperature for 2 hours, separate the solid and liquid to obtain wet potassium sulfate and mother liquor B, and dry the wet potassium sulfate at 140° C. to obtain a potassium sulfate product;

[0044] Step 4, evaporating and crystallizing the mother liquor A at 110° C. to obtain mother liquor C and wet sodium chloride, and drying the wet sodium chloride at 140° C. to obtain a sodium chloride product;

[0045] Step 5: Mix 1 part of mother liquor C, 0.25 parts of mother liquor B, 0.15 parts of sodium sulfate decahydrate and 0.025 parts of potassium chloride, react at room temperature for 2 hours, separate the solid and liquid to obtain mother liquor A and glauberite, return mother liquor A to step 4 for evaporation and crystallization to prepare sodium chloride, and return glauberite to step 3 for preparation of potassium sulfate.

[0046] In this embodiment, the potassium sulfate product prepared has a potassium oxide content of 52.48%, a sodium chloride product purity of 99.16%, and a sodium sulfate utilization rate of 99%.

[0047] Example 3

[0048] The present embodiment provides a method for high-value utilization of mirabilite resources, which is different from Example 1 only in that step one is replaced by: adding 1 part of mirabilite to 2 parts of water to dissolve, adding sulfuric acid to adjust the pH value to 2, adding 0.002 parts of sodium metabisulfite as a reducing agent, turning on radio frequency and microwave to treat the reaction solution at the same time to reduce hexavalent chromium to trivalent chromium, then adding sodium hydroxide to adjust the pH value to 8, continuously stirring to convert the trivalent chromium into chromium hydroxide precipitate, and obtaining a saturated sodium sulfate solution and chromium hydroxide slag through solid-liquid separation; wherein the specific parameters for treating the reaction solution with radio frequency and microwave are: radio frequency frequency of 27.12 MHz, radio frequency power of 300 W, microwave frequency of 2450 MHz, microwave power of 700 W, and treatment for 10 min; and the remaining steps are the same as Example 1.

[0049] In this embodiment, in the step 1, radio frequency and microwave are introduced to jointly treat the reaction liquid during the refining process of mirabilite impurities removal, which can enhance the reaction activity, promote the reduction and precipitation of hexavalent chromium, and facilitate the further removal of impurities. The obtained sodium sulfate solution has a higher purity, and the potassium sulfate and sodium chloride products prepared by the subsequent reaction have a higher purity. The potassium sulfate product prepared has a potassium oxide content of 52.89%, a sodium chloride product purity of 99.77%, and a sodium sulfate utilization rate of 99%.

[0050] Example 4

[0051] The present embodiment provides a method for high-value utilization of mirabilite resources, which differs from the embodiment 1 only in that step one is replaced by: adding 1 part of mirabilite to 2 parts of water to dissolve, adding sulfuric acid to adjust the pH value to 2, adding 0.002 parts of sodium metabisulfite as a reducing agent, turning on radio frequency to treat the reaction solution to reduce hexavalent chromium to trivalent chromium, then adding sodium hydroxide to adjust the pH value to 8, continuously stirring to convert the trivalent chromium into chromium hydroxide precipitate, and obtaining a saturated sodium sulfate solution and chromium hydroxide slag through solid-liquid separation; wherein, the specific parameters of the radio frequency treatment of the reaction solution are: radio frequency frequency of 27.12 MHz, radio frequency power of 300 W, and treatment for 10 min; and the remaining steps are the same as those in the embodiment 1.

[0052] In this embodiment, the potassium sulfate product prepared has a potassium oxide content of 52.45%, a sodium chloride product purity of 99.41%, and a sodium sulfate utilization rate of 99%.

[0053] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A method for high-value utilization of mirabilite resources, characterized in that: The following steps are involved: Step 1: removing impurities and refining the mirabilite to obtain a saturated sodium sulfate solution; Step 2: adding potassium chloride to a saturated sodium sulfate solution to carry out reaction 1, and separating the solid from the liquid to obtain glauberite and mother liquor A; Step 3: Mixing glauber's salt, potassium chloride and water to carry out reaction 2, separating the solid and liquid to obtain wet potassium sulfate and mother liquor B, and drying the wet potassium sulfate to obtain a potassium sulfate product; Step 4, evaporating and crystallizing the mother liquor A to obtain mother liquor C and wet sodium chloride, and drying the wet sodium chloride to obtain a sodium chloride product; Step 5: Return the mother liquor C and the mother liquor B to step 2, react with sodium sulfate and potassium chloride, separate the solid and liquid to obtain mother liquor A and glauberite, return the mother liquor A to step 4 for evaporation and crystallization to prepare sodium chloride, and return the glauberite to step 3 for preparation of potassium sulfate.

2. The method for high-value utilization of mirabilite resources according to claim 1, characterized in that: In the step 1, the specific method for removing impurities and refining the mirabilite is: adding mirabilite into water to dissolve it, adding sulfuric acid to adjust the pH value to 2-3, adding an excess of sodium pyrosulfite as a reducing agent, and then adding sodium hydroxide to adjust the pH value to 8-9, and separating the solid and liquid to obtain a saturated sodium sulfate solution.

3. The method for high-value utilization of mirabilite resources as claimed in claim 2, characterized in that: The mass ratio of the sodium sulfate to water is 1:1-3.

4. The method for high-value utilization of mirabilite resources according to claim 1, characterized in that: In the step 2, the mass ratio of potassium chloride to the saturated sodium sulfate solution is 1:2-5.

5. The method for high-value utilization of mirabilite resources as claimed in claim 1, characterized in that: In step 2 and step 5, the reaction temperature of reaction 1 is 20-60° C., and the reaction time is 1-3 hours.

6. The method for high-value utilization of mirabilite resources according to claim 1, characterized in that: In the step 3, the reaction temperature of the reaction 2 is 20 to 60° C., and the reaction time is 1 to 3 hours.

7. The method for high-value utilization of mirabilite resources as claimed in claim 1, characterized in that: In the step 3, the mass ratio of glauberite, potassium chloride and water is 1:0.5 to 1:1 to 3.

8. The method for high-value utilization of mirabilite resources as claimed in claim 1, characterized in that: In the step 4, the evaporation crystallization temperature is 90-140°C.

9. The method for high-value utilization of mirabilite resources as claimed in claim 1, characterized in that: In the step 3 and the step 4, the drying temperature is 140-150°C.

10. The method for high-value utilization of mirabilite resources according to claim 1, characterized in that: In the step 5, the mass ratio of mother liquor C, mother liquor B, sodium sulfate and potassium chloride is 1:0.1-0.3:0.05-0.3:0.01-0.04.

Images