Production process for removing free acid on surface of manganese sulfate crystal

Abstract

The invention discloses a production process for removing free acid on the surface of a manganese sulfate crystal, which comprises the following steps of: 1) preparing a crystal deacidification detergent: respectively selecting a crystal stabilizer and a surfactant according to the mass percentage, the mass percentage of the crystal stabilizer is 99.5-99.9%, the mass percentage of the surfactant is 0.1-0.5%, and the mass percentage of the surfactant is 0.1-0.5%; after the two components are uniformly mixed, the crystal deacidification detergent with the pH value of 4.5-7.2 can be obtained; 2) a washing process: conveying the acidification crystallization slurry containing the manganese sulfate crystals into centrifugal equipment, and performing centrifugal separation to obtain mother liquor and separated crystals; carrying out secondary centrifugal separation, and continuously washing with the obtained crystal deacidification detergent to obtain washing liquor and manganese sulfate crystals, and recycling mother liquor and washing liquor; and (3) drying: conveying the obtained manganese sulfate crystals to a drying machine for drying, and controlling the drying temperature to be 110-450 DEG C and the drying time to be 15-30 minutes to obtain a target product.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical production, and specifically refers to a production process for removing free acid from the surface of manganese sulfate crystals. Background Art

[0002] At present, the crystallization process of industrial manganese sulfate generally adopts atmospheric or pressurized evaporation crystallization method. For the production of high-purity manganese sulfate, an MVR system needs to be configured to reduce energy consumption, but the thermal energy cost per ton of product is still high. The traditional evaporation process has the following defects: a dedicated heating boiler needs to be built to provide steam or heat-conducting oil for heating, resulting in huge thermal energy consumption and high carbon emissions; at the same time, a large number of evaporation crystallization tanks or high-temperature crystallization kettles need to be configured, with large equipment investment and expensive maintenance costs for the crystallization evaporation system.

[0003] In the prior art, an attempt has been made to directly crystallize manganese sulfate by concentrated sulfuric acid acid precipitation method to avoid the evaporation process. However, a large amount of free sulfuric acid remains on the surface of the acid-precipitated crystals after separation from the acid solution, resulting in the following problems:

[0004] 1) The equipment in the subsequent process is corroded due to a large amount of free acid on the crystal surface. Due to the difficulty of anti-corrosion of the drying equipment, not only the equipment manufacturing cost is high, but also the production continuity is affected;

[0005] 2) Severe environmental pollution is caused by the emission of acid mist during drying;

[0006] 3) The pH value of the product exceeds the range of pH 5.0 - 7.0 required by the national standard GB / T 15899 - 2021. The surface of the crystal turns black after drying, and the product deteriorates, unable to meet the application standard for feed grade;

[0007] 4) Alcohol-based detergents can be used to remove the free acid on the crystal surface, but due to the high price of the detergents and the lack of reusability, they lack economic efficiency. Therefore, there is an urgent need for an economic solution that can effectively remove free acid, maintain the stability of the crystal structure, and meet the product purity standard. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to overcome the above-mentioned technical defects and provide a production process for removing free acid from the surface of manganese sulfate crystals.

[0009] To solve the above technical problem, the technical solution provided by the present invention is a production process for removing free acid from the surface of manganese sulfate crystals, including the following steps:

[0010] Step 1) Prepare a crystal deacidification detergent:

[0011] Select a crystal stabilizer and a surfactant by mass percentage. The mass percentage of the crystal stabilizer is 99.5 - 99.9%, and the mass percentage of the surfactant is 0.1 - 0.5 wt%. After mixing them evenly, a crystal deacidifying detergent with a pH of 4.5 - 7.2 can be obtained.

[0012] Step 2) Washing process:

[0013] Transport the acid precipitation crystallization slurry containing manganese sulfate crystals to a centrifugal device. First, perform centrifugal separation to obtain mother liquor and separated crystals. Then, perform a second centrifugal separation and continuously wash with the obtained crystal deacidifying detergent to obtain washing liquid and manganese sulfate crystals, where the mother liquor and the washing liquid are recycled.

[0014] Step 3) Drying:

[0015] Transport the obtained manganese sulfate crystals to a dryer for drying. Control the drying temperature at 110 - 450 °C and the drying time at 15 - 30 minutes to obtain the target product.

[0016] Furthermore, the crystal stabilizer in step 1 is a manganese sulfate solution, where the manganese ion concentration is 0.5 - 3 mol / L.

[0017] Furthermore, the surfactant in step 1 is hydroxyethyl cellulose.

[0018] Furthermore, the centrifugal device in step 2 is a centrifuge with a radial spraying or vacuum filtration function.

[0019] Furthermore, the washing working temperature in step 2 is 35 - 90 °C, and the rotation speed of the centrifugal device is 300 - 1200 rpm.

[0020] Furthermore, the mother liquor obtained in step 2 is a sulfuric acid-containing liquid, which is refluxed to the previous manganese ore acid leaching process; the washing liquid is a solution containing sulfuric acid and manganese sulfate after washing, which is refluxed to the purification process for repeated use.

[0021] The advantages of the present invention compared with the prior art are as follows: The production process provided by the present invention, through an innovative free acid cleaning agent, realizes the effective removal of free acid and the stable maintenance of the crystal structure. At the same time, it realizes the energy-saving benefit of completely avoiding the evaporation process in the manganese sulfate crystallization process. The main content of the obtained product reaches the feed grade standard, that is, Mn ≥ 31.8%. At the same time, the crystal deacidifying detergent can be recycled, greatly reducing the cost. Brief Description of the Drawings

[0022] Figure 1 is a flow chart of a production process for removing free acid on the surface of manganese sulfate crystals of the present invention. Detailed Embodiments

[0023] The following further elaborates on the production process for removing free acid from the surface of manganese sulfate crystals according to the present invention in conjunction with the embodiments.

[0024] Example 1

[0025] A production process for removing free acid from the surface of manganese sulfate crystals includes the following steps:

[0026] Prepare the crystal deacidification detergent: Take a 99.7% manganese sulfate solution with a manganese ion concentration of 1.5 mol / L, and at the same time, take 0.3% hydroxyethyl cellulose and mix evenly to obtain a crystal deacidification detergent with a pH of 5.8;

[0027] Washing process: Convey the acid precipitation crystallization slurry containing manganese sulfate crystals to a centrifuge with a radial spraying function. First, perform centrifugal separation to obtain the mother liquor and separated crystals; then perform a second centrifugal separation and continuously wash with the obtained crystal deacidification detergent to obtain the washing liquid and manganese sulfate crystals; the washing working temperature is 60 °C, and the centrifuge speed is 800 rpm;

[0028] Drying: Convey the obtained manganese sulfate crystals to a dryer for drying, control the drying temperature at 360 °C, and the drying time at 20 minutes to obtain the target product.

[0029] Example 2:

[0030] A production process for removing free acid from the surface of manganese sulfate crystals includes the following steps:

[0031] Prepare the crystal deacidification detergent: Take a 99.9% manganese sulfate solution with a manganese ion concentration of 1.5 mol / L, and at the same time, take 0.1% hydroxyethyl cellulose and mix evenly to obtain a crystal deacidification detergent with a pH of 6.5;

[0032] Washing process: Convey the acid precipitation crystallization slurry containing manganese sulfate crystals to a centrifuge with a vacuum filtration function. First, perform centrifugal separation to obtain the mother liquor and separated crystals; then perform a second centrifugal separation and continuously wash with the obtained crystal deacidification detergent to obtain the washing liquid and manganese sulfate crystals; the washing working temperature is 75 °C, and the centrifuge speed is 1000 rpm;

[0033] Drying: Convey the obtained manganese sulfate crystals to a dryer for drying, control the drying temperature at 260 °C, and the drying time at 25 minutes to obtain the target product.

[0034] The above describes the present invention and its implementation manners. Such description is not restrictive. What is shown in the drawings is only one of the implementation manners of the present invention, and the actual structure is not limited thereto. Generally speaking, if those of ordinary skill in the art are inspired by it and, without departing from the gist of the present invention, design similar structural manners and embodiments to this technical solution without creative efforts, they shall fall within the protection scope of the present invention.

Claims

1. A production process for removing free acid from the surface of manganese sulfate crystals, characterized in that: The following steps are involved: Step 1) Prepare crystal deacidification detergent: A crystal stabilizer and a surfactant are selected according to mass percentage, wherein the mass percentage of the crystal stabilizer is 99.5-99.9% and the mass percentage of the surfactant is 0.1-0.5wt%. After the two are evenly mixed, a crystal deacidifying detergent with a pH of 4.5-7.2 can be obtained; Step 2) Washing process: The acid-precipitated crystal slurry containing manganese sulfate crystals is transported to a centrifugal device, and first centrifuged to obtain a mother liquor and separated crystals; then a second centrifugation is performed, and the obtained crystals are continuously washed with a deacidifying detergent to obtain a washing liquid and manganese sulfate crystals, wherein the mother liquor and the washing liquid are recycled; Step 3) Drying: The obtained manganese sulfate crystals are transported to a dryer for drying, the drying temperature is controlled to be 110-450° C., and the drying time is 15-30 minutes, to obtain the target product.

2. The production process according to claim 1, characterized in that: The crystal stabilizer in step 1 is a manganese sulfate solution, wherein the manganese ion concentration is 0.5-3 mol / L.

3. The production process according to claim 1, characterized in that: The surfactant in step 1 is hydroxyethyl cellulose.

4. The production process according to claim 1, characterized in that: The centrifugal device in step 2 is a centrifuge with radial spraying or vacuum filtration function.

5. The production process according to claim 1, characterized in that: The washing working temperature in step 2 is 35-90° C., and the rotation speed of the centrifugal device is 300-1200 rpm.

6. The production process according to claim 1, characterized in that: The mother liquor obtained in step 2 is a liquid containing sulfuric acid, which is refluxed to the previous manganese ore acid leaching process; the washing liquid is a solution containing sulfuric acid and manganese sulfate after washing, which is refluxed to the purification process for repeated use.

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