阅读说明：本技术 一种由镁法脱硫废渣生产高纯硫酸镁的方法 (Method for producing high-purity magnesium sulfate from magnesium-method desulfurization waste residues ) 是由 肖建楠 陈居玲 邢东伟 闫合静 于 2019-12-18 设计创作，主要内容包括：本发明公开了一种由镁法脱硫废渣生产高纯硫酸镁的方法,将镁法脱硫废渣与清水或硫酸镁循环母液混合,打制成浆,泵入连续式氧化反应器；通风氧化后再加适量增溶剂,使镁法脱硫废渣中的亚硫酸镁被氧化、溶出,再经过滤得氧化后液；将氧化后液送多功能结晶器,首先加析晶剂硫酸,然后进行结晶操作,结晶完成经分离、洗涤、脱水、干燥制得高纯硫酸镁。该方法免蒸发结晶分离硫酸镁,大幅度降低了因溶液蒸发造成的能源消耗量,明显地降低了生产成本,避免了催化氧化法由镁法脱硫废渣生产硫酸镁所存在的亏损现象,具有氧化耗时短、能耗低、反应尾气得到有效利用、生产成本低等特点。(The invention discloses a method for producing high-purity magnesium sulfate from magnesium desulfurization waste residue, which comprises the steps of mixing the magnesium desulfurization waste residue with clear water or magnesium sulfate circulating mother liquor, pulping, and pumping into a continuous oxidation reactor; after ventilation and oxidation, adding a proper amount of solubilizer to oxidize and dissolve out magnesium sulfite in the magnesium desulfurization waste residue, and filtering to obtain oxidized liquid; and (3) feeding the oxidized liquid into a multifunctional crystallizer, firstly adding sulfuric acid serving as a crystallization agent, then carrying out crystallization operation, and separating, washing, dehydrating and drying the crystallized liquid to obtain the high-purity magnesium sulfate. The method has the advantages of avoiding evaporation crystallization to separate magnesium sulfate, greatly reducing energy consumption caused by solution evaporation, obviously reducing production cost, avoiding loss phenomenon of magnesium sulfate production from magnesium desulfurization waste residue by a catalytic oxidation method, along with short oxidation time, low energy consumption, effective utilization of reaction tail gas, low production cost and the like.)

1. A method for producing high-purity magnesium sulfate from magnesium desulfurization waste residue is characterized by comprising the following steps:

mixing the magnesium desulfurization waste residue with clear water or magnesium sulfate circulating mother liquor, pulping, and pumping into a continuous oxidation reactor; after ventilation and oxidation, adding a proper amount of solubilizer to oxidize and dissolve out magnesium sulfite in the magnesium desulfurization waste residue, and filtering to obtain oxidized liquid; and (3) feeding the oxidized liquid into a multifunctional crystallizer, firstly adding sulfuric acid serving as a crystallization agent, then carrying out crystallization operation, and separating, washing, dehydrating and drying the crystallized liquid to obtain the high-purity magnesium sulfate.

2. The method for producing high-purity magnesium sulfate from magnesium desulfurization waste residues as recited in claim 1, characterized by comprising the steps of:

step 1: controlling the target concentration of magnesium sulfate to be 400-450 g/L, sending the calculated amount of magnesium desulfurization waste residue into a slurry preparation tank, mixing with clear water or magnesium sulfate circulating mother liquor, and beating to prepare slurry;

step 2: pumping the magnesium desulfurization waste residue slurry obtained in the step 1 into an oxidation reactor, heating to 45-80 ℃ by using steam under the stirring condition, ventilating and oxidizing in the heating process, and carrying out heat preservation reaction for 180min when the temperature reaches a preset value; meanwhile, when the oxidation time is 30-120 min, adding a solubilizer, filtering after the reaction is finished to obtain oxidized liquid and oxidized residues; in the oxidation process, the induced draft fan will contain SO₂Introducing the reaction tail gas into a tail gas absorption system, and absorbing the reaction tail gas by taking a sodium carbonate solution as an absorbent to generate sodium bisulfite to obtain a sodium bisulfite solution; this stepThe solubilizer used in the step is one or two of sulfuric acid or sulfur dioxide gas;

and step 3: feeding the oxidized liquid obtained in the step (2) into a multifunctional crystallizer, adding sulfuric acid serving as a crystallization agent, carrying out crystallization, and leading reaction tail gas (containing SO) to be discharged by a draught fan₂) Introducing a tail gas absorption system, and taking a sodium carbonate solution as an absorbent to absorb the reaction tail gas to generate sodium bisulfite to obtain a sodium bisulfite solution; then carrying out vacuum cooling on the oxidized liquid under the negative pressure condition, wherein the negative pressure is controlled to be-0.06 to-0.098 MPa in the cooling process; when the temperature is reduced to 45 ℃, switching to cold water for forced cooling, cooling the oxidized liquid to 20-30 ℃, and then separating; and washing, dehydrating and drying to obtain the high-purity magnesium sulfate, wherein the purity of the obtained magnesium sulfate meets the requirements of feed grade and food grade.

3. The method for producing high-purity magnesium sulfate from magnesium desulfurization waste residues as recited in claim 2, wherein: and (3) absorbing the reaction tail gas generated in the step (2) and the step (3) to prepare a sodium bisulfite solution, and evaporating, crystallizing, separating and drying the sodium bisulfite solution to prepare a sodium bisulfite product.

4. The method for producing high-purity magnesium sulfate from magnesium desulfurization waste residues as recited in claim 2, wherein: absorbing the reaction tail gas generated in the step 2 and the step 3 to prepare a sodium bisulfite solution, and adding sodium hydroxide into the sodium bisulfite solution to convert the sodium bisulfite into sodium sulfite; and then the anhydrous sodium sulfite product is prepared by concentration, crystallization, separation, dehydration and drying.

Technical Field

The invention belongs to the field of solid waste resource utilization, and particularly relates to a method for producing high-purity magnesium sulfate from magnesium-method desulfurization waste residues.

Background

The magnesium desulphurization waste residue is industrial waste residue generated in the magnesium desulphurization process, the main chemical composition of the magnesium sulfite hexahydrate is magnesium sulfite, and the dry basis analysis content is usually between 80 and 105 percent. In recent years, the production amount of magnesium sulfite of a byproduct of magnesium desulfurization in China is increased year by year, and the annual output is usually between 5 and 30 million tons and more million tons according to different production scales of enterprises. The desulfurization storage of the desulfurization by-product not only occupies a large amount of land, but also causes pollution to the environment and huge ecological damage. Therefore, a comprehensive utilization way of the magnesium desulfurization waste residue is urgently needed to be found, and the pollution to the environment is solved.

The main component of the magnesium desulphurization waste residue is magnesium sulfite, so the magnesium desulphurization waste residue has certain utilization value. Since a period of time, relevant scientific research departments in China and production enterprises pay more attention to resource utilization of magnesium sulfite, and some researches are carried out and some progress is made. The reported processes include sulfuric acid acidification sulfur dioxide recovery method, roasting magnesium oxide and sulfur dioxide recovery method, magnesium sulfite purification method, catalytic oxidation method, etc.

Disclosure of Invention

Aiming at the defects of the currently reported process and overcoming the defects of the prior art, the application provides a method for producing high-purity magnesium sulfate from magnesium desulfurization waste residues. The method has the characteristics of short oxidation time, low energy consumption, effective utilization of reaction tail gas and low production cost.

In order to achieve the purpose, the invention adopts the technical scheme that: a method for producing high-purity magnesium sulfate from magnesium desulfurization waste residues is characterized by comprising the following steps:

mixing the magnesium desulfurization waste residue with clear water or magnesium sulfate circulating mother liquor, pulping, and pumping into a continuous oxidation reactor; after ventilation and oxidation, adding a proper amount of solubilizer to oxidize and dissolve out magnesium sulfite in the magnesium desulfurization waste residue, and filtering to obtain oxidized liquid; and (3) feeding the oxidized liquid into a multifunctional crystallizer, firstly adding sulfuric acid serving as a crystallization agent, then carrying out crystallization operation, and separating, washing, dehydrating and drying the crystallized liquid to obtain the high-purity magnesium sulfate.

Further, the operation is carried out according to the following steps:

step 1: controlling the target concentration of magnesium sulfate to be 400-450 g/L, sending the calculated amount of magnesium desulfurization waste residue into a slurry preparation tank, mixing with clear water or magnesium sulfate circulating mother liquor, and beating to prepare slurry;

step 2: pumping the magnesium desulfurization waste residue slurry obtained in the step 1 into an oxidation reactor, heating to 45-80 ℃ by using steam under the stirring condition, ventilating and oxidizing in the heating process, and carrying out heat preservation reaction for 180min when the temperature reaches a preset value; meanwhile, when the oxidation time is 30-120 min, the solubilizer is added. Filtering to obtain oxidized liquid and oxidized residue after the reaction is finished; in the oxidation process, the induced draft fan will contain SO₂Introducing the reaction tail gas into a tail gas absorption system, and absorbing the reaction tail gas by taking a sodium carbonate solution as an absorbent to generate sodium bisulfite to obtain a sodium bisulfite solution; the solubilizer used in the step is one or two of sulfuric acid or sulfur dioxide gas;

and step 3: feeding the oxidized liquid obtained in the step (2) into a multifunctional crystallizer, adding sulfuric acid serving as a crystallization agent, carrying out crystallization, and leading reaction tail gas (containing SO) to be discharged by a draught fan₂) Introducing a tail gas absorption system, and taking a sodium carbonate solution as an absorbent to absorb the reaction tail gas to generate sodium bisulfite to obtain a sodium bisulfite solution; then carrying out vacuum cooling on the oxidized liquid under the negative pressure condition, wherein the negative pressure is controlled to be-0.06 to-0.098 MPa in the cooling process; when the temperature is reduced to 45 ℃, switching to cold water for forced cooling, cooling the oxidized liquid to 20-30 ℃, and then separating; and washing, dehydrating and drying to obtain the high-purity magnesium sulfate, wherein the purity of the obtained magnesium sulfate meets the requirements of feed grade and food grade.

And (3) absorbing the reaction tail gas generated in the step (2) and the step (3) to prepare a sodium bisulfite solution, and evaporating, crystallizing, separating and drying the sodium bisulfite solution to prepare a sodium bisulfite product.

Absorbing the reaction tail gas generated in the step 2 and the step 3 to prepare a sodium bisulfite solution, and adding sodium hydroxide into the sodium bisulfite solution to convert the sodium bisulfite into sodium sulfite; and then the anhydrous sodium sulfite product is prepared by concentration, crystallization, separation, dehydration and drying.

Compared with the prior art, the invention has the advantages that:

1. the oxidation speed is high, only 180min, and the method saves more than 180min compared with other processes. Greatly reduces the production process and reduces the energy consumption.

2. The concentration of magnesium sulfate in the oxidized liquid can be effectively controlled to be 30-37%, and the method has the conditions of evaporation-free crystallization and separation of magnesium sulfate heptahydrate.

3. The crystallization mode of firstly carrying out negative pressure cooling and then carrying out water forced cooling greatly reduces the energy consumption caused by solution evaporation due to the realization of the separation of magnesium sulfate by evaporation-free crystallization, obviously reduces the production cost and avoids the defect phenomenon of magnesium sulfate production from magnesium desulfurization waste residue by a catalytic oxidation method.

4. The treatment mode of the reaction tail gas in the oxidation and crystallization processes prepares a sodium bisulfite or sodium sulfite product by absorbing the tail gas, thereby not only avoiding the pollution of tail gas emission to the environment, but also increasing the economic benefit of comprehensive utilization.

Drawings

The following describes in further detail specific embodiments of the present invention with reference to the accompanying drawings.

FIG. 1 is a process flow diagram of the present invention.

Detailed Description