Process for preparing potassium sulfate by using carnallite ore and elite ore

Abstract

The invention discloses a process for preparing potassium sulfate by using carnallite and epsomite, which comprises the following steps: immersing a mixture of carnallite and epsomite in water under heating and stirring conditions to obtain a leachate containing ions such as K < + >, Mg < 2 + >, Cl <-> and SO4 < 2->; adding KOH to adjust the pH value to 9-13 to generate magnesium hydroxide precipitate, and filtering to obtain a refined solution containing K < + >, Cl <-> and SO4 < 2->; adding ammonium sulfate into the refined solution, continuously stirring and heating, and reacting to generate potassium sulfate (K2SO4) and ammonium chloride (NH4Cl); cooling and crystallizing the reaction liquid, filtering, and drying the obtained filter residue to obtain a mixture of K2SO4 and NH4Cl; adding an alcohol extractant into the mixture of K2SO4 and NH4Cl, filtering after the extraction is completed, and drying the obtained filter residue to obtain potassium sulfate; the method overcomes the problem that high-purity potassium sulfate cannot be obtained due to many chloride types, and has the advantages of low requirement on impurity content of raw materials, simple process, and renewable recycling of the extraction agent and the aqueous solution.

Description

Technical Field

[0001] The invention belongs to the technical field of salt chemical industry, and specifically relates to a process for preparing potassium sulfate by utilizing carnallite ore and epsomite ore. Background Art

[0002] Potassium is one of the main elements in the growth process of plants, and potassium sulfate fertilizer is the most commonly used potassium fertilizer. The main resource type for potassium fertilizer production in my country is liquid potassium resources, which mainly exist in salt lake brine and underground brine. The production of potassium sulfate using salt lake brine as raw material will produce a large amount of carnallite and epsomite every year, and these mines also contain a certain amount of potassium resources. If these potassium resources cannot be used in time, it will not only cause waste and limit the extraction of other elements, but also affect the ecological environment of the salt lake, leading to the deterioration of the salt lake, thereby causing the grade of the salt lake to decline.

[0003] The main component of carnallite is 23.88% K + 、18.79%Na + 、10.7678%Mg 2+ 、33.42%Cl - and 8.897% SO4 2- The main component of Xieli salt mine is 15.07% K + 、2.69%Na + 、10.01%Mg 2+ 、31.44%Cl - and 22.89% SO4 2- , the two salts contain a large amount of K + and SO4 2- , both minerals need to be dechlorinated and magnesium removed for effective utilization. Considering that potassium sulfate has good solubility in water, the leaching rate can reach more than 99%, but due to the presence of other chlorides, the Cl in the refined potassium sulfate leachate is - The content is high and the separation is difficult.

[0004] How to use carnallite and epsomite to prepare high-purity potassium sulfate has become a technical problem that needs to be solved urgently. Summary of the invention

[0005] The purpose of the present invention is to provide a process for preparing high-purity potassium sulfate using carnallite ore and epsomite ore, so as to overcome the problem that the potassium sulfate product prepared by the prior art contains too many types of chlorides and cannot achieve high-purity potassium sulfate. At the same time, the present invention has low requirements on the impurity content of the raw materials, a simple process, and the extractant and the aqueous solution can be recycled and reused. No new impurities are introduced during the extraction process, which is conducive to the recycling of wastewater.

[0006] In order to achieve the above purpose, the technical solutions adopted are as follows:

[0007] A process for preparing potassium sulfate using carnallite ore and epsomite ore comprises the following steps:

[0008] (1) Immersing a mixture of carnallite and epsomite in water under heating and stirring conditions to obtain a K-containing + Mg 2+ , Cl - and SO4 2- Plasma leaching solution;

[0009] (2) Add KOH to adjust the pH to 9-13 to generate magnesium hydroxide precipitate, which is filtered to obtain K-containing + , Cl - and SO4 2- of a refined solution;

[0010] (3) adding ammonium sulfate to the obtained refined solution, stirring and heating continuously, and reacting to generate potassium sulfate (K2SO4) and ammonium chloride (NH4Cl);

[0011] (4) cooling the reaction solution for crystallization and filtering, and drying the obtained filter residue to obtain a mixture of K2SO4 and NH4Cl;

[0012] (5) adding the obtained mixture of K2SO4 and NH4Cl to an alcohol extractant, filtering after the extraction is completed, and drying the obtained filter residue to obtain potassium sulfate.

[0013] According to the above scheme, the temperature of heating and leaching in step 1 is 40-70°C.

[0014] According to the above scheme, the leaching solution in step 1 contains 40-50 g / L of K + 20~40g / L Mg 2+ , 30~70g / L Cl - and 20~40g / L SO4 2- .

[0015] According to the above scheme, the pH of the leaching solution in step 1 is 6.5-7.5.

[0016] According to the above scheme, the reaction temperature used in step 2 is 40-70°C.

[0017] According to the above scheme, the amount of ammonium sulfate added in step 3 is Cl in the refined solution. - 0.5 to 0.75 times the amount of substance.

[0018] According to the above scheme, the reaction temperature in step 3 is 40-70°C and the reaction time is 30-60min.

[0019] According to the above scheme, the cooling temperature in step 4 is 0-10°C and the cooling time is 1-2h.

[0020] According to the above scheme, step 4 also includes returning the obtained filtrate to step 3, mixing it with the refined solution and then adding ammonium sulfate.

[0021] According to the above scheme, the alcohol extractant in step 5 is one of methanol, ethanol, cyclopentanol or any mixture thereof.

[0022] According to the above scheme, the amount of the alcohol extractant in step 5 is proportional to the content of ammonium chloride.

[0023] According to the above scheme, in step 5, the extraction temperature is 30-60°C, the stirring rate is 20-50r / min, and the time is 10-60min.

[0024] According to the above scheme, step 5 also includes sending the obtained filtrate into the evaporation crystallization section, evaporating at 60-140°C to obtain the by-product NH4Cl, and condensing and recovering the extractant for repeated use.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) It can fully utilize the potassium resources in carnallite and the sulfur resources in epsom salt to produce potassium sulfate products. (2) It consumes less raw materials, has a short process flow, simple equipment, easy operation, and low production cost, which is conducive to large-scale industrial production. (3) The raw material cost is low and the economic benefit is high. The extractant does not require a complex separation process. The extractant can be recycled by evaporation alone. The by-product ammonium chloride can be prepared into ammonium chloride fertilizer after subsequent processing. (4) It is green and environmentally friendly. The extractant and aqueous solution can be recycled and reused. The extraction process does not introduce new impurities, which is conducive to recycling. It is a green, efficient and low-cost potassium sulfate production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 : The present invention utilizes carnallite ore and epsom salt ore to prepare the process flow chart of potassium sulfate. DETAILED DESCRIPTION

[0028] The following will be described clearly and completely in conjunction with the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] The specific embodiment provides a process for preparing potassium sulfate using carnallite ore and epsom salt ore, referring to the attached Figure 1 As shown:

[0030] Step 1: Dissolve the mixture of carnallite and epsomite in water under heating and stirring conditions to make the K+ Mg 2+ , Cl - and SO4 2- Plasma leaching to obtain K-containing + Mg 2+ , Cl - and SO4 2- Plasma leaching solution;

[0031] Step 2: To remove Mg from the leaching solution 2+ The magnesium is converted into magnesium hydroxide (Mg(OH)2) precipitate by adding potassium hydroxide (KOH) to adjust the pH, and then filtered to obtain K-containing + , Cl - and SO4 2- of a refined solution;

[0032] Step 3: Add the recovered filtrate to the refined solution and adjust the mixture according to the Cl - The amount of substance to be added is calculated by the amount of ammonium sulfate ((NH4)2SO4). During the reaction, continuous stirring and heating are required to generate potassium sulfate (K2SO4) and ammonium chloride (NH4Cl);

[0033] Step 4: After the reaction is completed, the mixture is cooled and crystallized. The crystals are a mixture of K2SO4 and NH4Cl. After filtering and drying, a filter residue is obtained. The filtrate is recovered and added to the refined solution of step 3.

[0034] Step 5: adjusting the amount of alcohol extractant added according to the NH4Cl content in the mixture, and performing extraction operation under certain temperature and stirring conditions;

[0035] Step 6: After the extraction is completed, the extraction is filtered and the filter residue is dried to obtain high-purity potassium sulfate; the filtrate enters the evaporation and crystallization section to obtain the by-product NH4Cl, and at the same time, the extraction agent is condensed and recovered and returned to the extraction section.

[0036] Example 1

[0037] Step 1: Add 500 g of water to a mixture of 200 g of carnallite and 200 g of epsomite at 50°C and stir to obtain a K-containing + 44g / L, Cl - The concentration of the leaching solution is 66 g / L, and the pH of the leaching solution is 6.7;

[0038] Step 2: Use KOH to + The pH value of the leaching solution was adjusted to 12.5, and a large amount of Mg(OH)2 precipitate was produced. After filtration, K-containing + , Cl - 、SO42- of a refined solution;

[0039] Step 3: Add the recovered filtrate to the refined solution, and add (NH4)2SO4 in an amount equal to the Cl content in the mixed solution. - 0.65 times the amount of substance. During the reaction, continuous stirring and heating are required to generate K2SO4 and NH4Cl;

[0040] Step 4: After the reaction is completed, the mixture is cooled and crystallized at a temperature of 5°C for 1 hour. The crystals are a mixture of K2SO4 and NH4Cl. After filtration and drying, a filter residue is obtained; the filtrate is recycled and returned to the reaction section;

[0041] Step 5: according to the content of NH4Cl in the mixture, methanol is added as an extractant for extraction. The extraction process is carried out at a temperature of 50°C, a stirring speed of 30r / min, and an extraction time of 60min;

[0042] Step 6: After the extraction is completed, the filtration process is carried out. The filter residue is dried to obtain K2SO4; the filtrate enters the next evaporation process, the evaporation temperature is 60°C, and the by-product NH4Cl is obtained through evaporation and crystallization. The extractant is condensed and recovered and returned to the extraction process.

[0043] The purity of K2SO4 prepared by the above process is 98.65wt%, Cl - The content is 0.27wt%, and the purity of NH4Cl is 93.65wt%.

[0044] Example 2

[0045] Step 1: Add 500 g of water to a mixture of 200 g of carnallite and 200 g of epsomite at 50°C and stir to obtain a K-containing + 47g / L, Cl - The concentration of the leaching solution is 63g / L, and the pH of the leaching solution is 7.4;

[0046] Step 2: Use KOH to + The pH value of the leaching solution was adjusted to 12.6, and a large amount of Mg(OH)2 precipitate was produced. After filtration, K-containing + , Cl - 、SO4 2- of a refined solution;

[0047] Step 3: Add the recovered filtrate to the refined solution, and add (NH4)2SO4 in an amount equal to the Cl content in the mixed solution. - 0.65 times the amount of substance. During the reaction, continuous stirring and heating are required to generate K2SO4 and NH4Cl;

[0048] Step 4: After the reaction is completed, the mixture is cooled and crystallized at a temperature of 5°C for 1 hour. The crystals are a mixture of K2SO4 and NH4Cl. After filtration and drying, a filter residue is obtained; the filtrate is recycled and returned to the reaction section;

[0049] Step 5: according to the content of NH4Cl in the mixture, ethanol is added as an extractant for extraction. The extraction process is carried out at a temperature of 50°C, a stirring speed of 30r / min, and an extraction time of 60min;

[0050] Step 6: After the extraction is completed, the filtration process is carried out. The filter residue is dried to obtain K2SO4; the filtrate enters the next evaporation process, the evaporation temperature is 80°C, and the by-product NH4Cl is obtained through evaporation and crystallization. The extractant is condensed and recovered and returned to the extraction process.

[0051] The purity of K2SO4 prepared by the above process is 91.38wt%, Cl - The content is 2.93wt%, and the purity of NH4Cl is 87.36wt%.

[0052] Example 3

[0053] Step 1: Add 500 g of water to a mixture of 200 g of carnallite and 200 g of epsomite at 50°C and stir to obtain a K-containing + 46g / L, Cl - The concentration of the leaching solution is 61g / L, and the pH of the leaching solution is 7.1;

[0054] Step 2: Use KOH to + The pH value of the leaching solution was adjusted to 12.3, and a large amount of Mg(OH)2 precipitate was produced. After filtration, K-containing + , Cl - 、SO4 2- of a refined solution;

[0055] Step 3: Add the recovered filtrate to the refined solution, and add (NH4)2SO4 in an amount equal to the Cl content in the mixed solution. - 0.65 times the amount of substance. During the reaction, continuous stirring and heating are required to generate K2SO4 and NH4Cl;

[0056] Step 4: After the reaction is completed, the mixture is cooled and crystallized at a temperature of 5°C for 1 hour. The crystals are a mixture of K2SO4 and NH4Cl. After filtration and drying, a filter residue is obtained; the filtrate is recycled and returned to the reaction section;

[0057] Step 5: according to the content of NH4Cl in the mixture, cyclopentanol was added as an extractant for extraction, the extraction process was carried out at a temperature of 50°C, a stirring speed of 30r / min, and an extraction time of 60min;

[0058] Step 6: After the extraction is completed, the filtration process is carried out. The filter residue is dried to obtain K2SO4; the filtrate enters the next evaporation process, the evaporation temperature is 140°C, and the by-product NH4Cl is obtained through evaporation and crystallization. The extractant is condensed and recovered and returned to the extraction process.

[0059] The purity of K2SO4 prepared by the above process is 94.53wt%, Cl - The content is 1.13wt%, and the purity of NH4Cl is 92.65wt%.

[0060] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A process for preparing potassium sulfate using carnallite ore and epsomite ore, characterized in that The following steps are involved: (1) Immersing a mixture of carnallite and epsomite in water under heating and stirring conditions to obtain a K-containing + Mg 2+ , Cl - and SO4 2- Plasma leaching solution; (2) Add KOH to adjust the pH to 9-13 to generate magnesium hydroxide precipitate, which is filtered to obtain K-containing + , Cl - and SO4 2- A refined solution of (3) adding ammonium sulfate to the obtained refined solution, stirring and heating continuously, and reacting to generate potassium sulfate and ammonium chloride; (4) cooling the reaction solution for crystallization, filtering, and drying the obtained filter residue to obtain a mixture of K2SO4 and NH4Cl; (5) adding the obtained mixture of K2SO4 and NH4Cl to an alcohol extractant, filtering after the extraction is completed, and drying the obtained filter residue to obtain potassium sulfate.

2. The process for preparing potassium sulfate using carnallite and epsomite as claimed in claim 1, characterized in that The temperature of heating and leaching in step 1 is 40-70°C.

3. The process for preparing potassium sulfate using carnallite ore and epsomite ore as claimed in claim 1, characterized in that The leaching solution in step 1 contains 40-50 g / L of K + 20~40g / L Mg 2+ , 30~70g / L Cl - and 20~40g / L SO4 2- ; The pH of the extract is 6.5-7.

5.

4. The process for preparing potassium sulfate using carnallite ore and epsomite ore as claimed in claim 1, characterized in that Step 2: Add KOH to adjust the pH reaction temperature to 40-70°C.

5. The process for preparing potassium sulfate using carnallite ore and epsomite ore as claimed in claim 1, characterized in that Step 3: The amount of ammonium sulfate added is the amount of Cl in the refined solution. - 0.5 to 0.75 times the amount of substance.

6. The process for preparing potassium sulfate using carnallite ore and epsomite ore as claimed in claim 1, characterized in that The reaction temperature of step 3 is 40-70° C. and the reaction time is 30-60 min.

7. The process for preparing potassium sulfate using carnallite and epsomite as claimed in claim 1, characterized in that In step 4, the cooling temperature is 0 to 10° C. and the cooling time is 1 to 2 hours.

8. The process for preparing potassium sulfate using carnallite ore and epsomite ore as claimed in claim 1, characterized in that Step 4 also includes returning the obtained filtrate to step 3 to mix with the refined solution and then adding ammonium sulfate.

9. The process for preparing potassium sulfate using carnallite and epsomite as claimed in claim 1, characterized in that The alcohol extractant in step 5 is one of methanol, ethanol, and cyclopentanol or any mixture thereof.

10. The process for preparing potassium sulfate using carnallite ore and epsomite ore as claimed in claim 1, characterized in that Step 5 also includes sending the obtained filtrate into an evaporation and crystallization section, evaporating at 60-140° C. to obtain by-product NH 4 Cl, and condensing and recovering the extractant for repeated use.

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