A method for preparing soil conditioner from magnesium sulfite and co-producing sodium sulfite

Abstract

This invention provides a method for preparing soil conditioner and co-producing sodium sulfite from magnesium sulfite. The method includes the following steps: S1 Raw material metering and acidification reaction. Magnesium sulfite, a byproduct of magnesium desulfurization, is precisely metered using a weighing feeder and continuously fed into the acidification reactor. Compared with traditional aeration methods for preparing magnesium sulfate and sulfur combustion for preparing sodium sulfite, this invention significantly shortens reaction time, reduces energy consumption, and decreases carbon emissions. It transforms solid waste that previously required costly treatment into high-value-added products, simultaneously achieving a synergistic improvement in environmental, economic, and social benefits. This technology provides a stable, reliable, replicable, and scalable technical route for the efficient resource utilization of magnesium desulfurization byproducts, promoting the development of industrial solid waste utilization towards high value, closed-loop systems, and large-scale production.

Description

Technical Field

[0001] This invention relates to the field of environmental resource utilization technology, and in particular to a method for preparing a soil conditioner from magnesium sulfite and co-producing sodium sulfite. Background Technology

[0002] Magnesium sulfite is used to prepare soil conditioners. It is an alkaline soil amendment material made from magnesium sulfite, a byproduct of magnesium flue gas desulfurization, as the core raw material. After purification and activation, it is supplemented with auxiliary materials such as calcium, silicon, and humic acid. The mixture is then mixed, granulated, and dried. It can neutralize soil acidity, increase pH value, supplement magnesium and sulfur nutrients, improve soil aggregate structure, promote microbial activity, passivate heavy metals, and alleviate compaction. It has both soil amendment and fertilization effects, achieving the synergistic benefits of solid waste resource utilization and arable land quality improvement.

[0003] Using magnesium sulfite solid waste generated from magnesium desulfurization as the main raw material, an alkaline soil conditioner is prepared through purification, oxidation, and controlled reaction processes. This conditioner can improve acidic soil, supplement magnesium and sulfur elements, and restore arable land soil quality. During the production process, reaction conditions are optimized simultaneously to co-produce sodium sulfite, achieving efficient resource utilization of solid waste. This process combines the production of soil amendment materials with the output of chemical by-products, reducing treatment costs, improving the comprehensive utilization rate of resources, and possessing both environmental benefits and economic value.

[0004] Magnesium sulfite produced by magnesium desulfurization is mostly disposed of through stockpiling and disposal, which not only occupies land but also pollutes soil, water, and air, posing significant environmental risks. Existing mainstream resource-based magnesium sulfate production processes have high energy consumption, low conversion rates, and low added value. Traditional sodium sulfite production has high raw material costs and large carbon emissions. All existing processes generally suffer from insufficient resource utilization, mother liquor discharge, poor conversion efficiency, and cumbersome procedures, making them unsuitable for the development needs of clean production and high-value utilization of solid waste.

[0005] Therefore, it is necessary to provide a method for preparing soil conditioner from magnesium sulfite and co-producing sodium sulfite to solve the above-mentioned technical problems. Summary of the Invention

[0006] This invention provides a method for preparing soil conditioner from magnesium sulfite and co-producing sodium sulfite, which solves the problems of magnesium sulfite being prone to multiple pollutions due to random storage, and existing related production processes being energy-intensive, inefficient, costly, and difficult to achieve clean and high-value utilization.

[0007] To solve the above-mentioned technical problems, the method for preparing soil conditioner and co-producing sodium sulfite using magnesium sulfite provided by the present invention includes the following steps: S1: Raw material metering and acidification reaction. Magnesium sulfite, a byproduct of magnesium desulfurization, is accurately metered by a weighing feeder and continuously fed into the acidification reactor. At the same time, 98% concentrated sulfuric acid is slowly added dropwise into the reactor to carry out the acidification reaction. The pH value at the end of the reaction is strictly controlled to be stable at 3-4, so that magnesium sulfite can fully react and be completely converted into magnesium sulfate solution, high-concentration SO2 gas and water. S2: Neutralization, pH adjustment and aging. Add magnesium oxide powder to the magnesium sulfate solution obtained in S1. Adjust the pH of the system to 7-8 under stirring conditions to neutralize the residual acidity in the solution. Then send the mixture into the aging chamber for full cooling and aging to promote the coagulation and sedimentation of trace insoluble impurities and improve the purity of the liquid phase. S3: Solid-liquid separation. The mixture after S2 maturation is sent to a filter press for solid-liquid separation to obtain filter residue and saturated magnesium sulfate filtrate. The main components of the filter residue are silicon dioxide, calcium sulfate and a small amount of magnesium sulfate, and the filtrate is a high-concentration qualified magnesium sulfate solution. S4: Soil conditioner preparation. The filter residue obtained from S3 is dried at low temperature, crushed, homogenized and modified to obtain a soil conditioner product that can improve soil structure and enhance water and fertilizer retention capacity. S5: Preparation of magnesium sulfate monohydrate fertilizer. The magnesium sulfate filtrate obtained in S3 is concentrated and then fed into Raymond mill through a bucket elevator to be ground to 200 mesh to obtain magnesium sulfate monohydrate powder. The powder is then granulated by disc granulation, dried and sieved to obtain magnesium sulfate monohydrate granular fertilizer with uniform particles. S6: SO2 gas purification. The SO2 gas generated in S1 is sequentially processed through dust removal, cooling, deep drying in a sulfuric acid tower, and pressurization by a gas booster to obtain high-purity, low-moisture dry SO2 gas, which is then sent to the alkali absorption system. S7: Sodium sulfite absorption and crystallization. Sodium carbonate solution is used to perform primary and secondary countercurrent absorption of SO2 gas purified by S6. During the absorption process, liquid alkali is added dropwise to control the pH of the absorption liquid at 9-12 to form a saturated sodium sulfite solution, which is then sent to a crystallizer for cooling and crystallization. S8: Sodium sulfite refining. The sodium sulfite crystal slurry obtained from S7 is sent to a centrifuge for solid-liquid separation. The separated wet crystals are dried with hot air to obtain industrial-grade sodium sulfite product with a purity of not less than 95%. All centrifugal mother liquor is returned to the absorption system for recycling. Throughout the preparation process, corrosion-resistant pipes and pumps must be used for material transport between different structures. In particular, pipes that come into contact with sulfuric acid, magnesium sulfate, and sodium sulfite solutions should be lined with PTFE or stainless steel to prevent leakage caused by media corrosion. The weighing feeder must be calibrated regularly to ensure metering accuracy and prevent pH loss at the reaction endpoint due to raw material metering deviations. The sulfuric acid dripping pipe should be equipped with an anti-clogging structure to prevent local crystallization or impurity deposition from affecting the uniformity of feeding.

[0008] Preferably, the acidification reaction temperature in S1 is controlled at 30℃-60℃, the reaction time is 30min-90min, and the sulfuric acid is fed by continuous dripping.

[0009] Preferably, the SO2 gas purification in step S6 includes cyclone dust removal, indirect cooling, deep drying with 98% sulfuric acid, and Roots blower pressurization, and the water content of the purified gas is ≤0.5%.

[0010] Preferably, in step S7, the mass concentration of the soda ash solution used for the first and second countercurrent absorption is 15%-30%, the absorption temperature is controlled at 20℃-45℃, the centrifugal separation speed in step S8 is 800r / min-1500r / min, the drying temperature is 80℃-120℃, and the moisture content of the dried product is ≤0.3%.

[0011] Preferably, the acidification reactor used in the S1 raw material metering and acidification reaction includes: a mounting base; An acidification reactor is mounted on top of a mounting base via a support. A stirring assembly, a gas collecting assembly, a sulfuric acid inlet assembly, and a feed pipe are installed at the top of the acidification reactor. A discharge structure is installed at the bottom of the acidification reactor.

[0012] Preferably, the acidification reactor includes a gas-liquid separation chamber, a main reaction chamber, a premixing chamber, and a top cover. The gas-liquid separation chamber is installed at the bottom of the main reaction chamber, the premixing chamber is installed at the top of the main reaction chamber, and the top cover is installed at the top of the premixing chamber. The gas-liquid separation chamber is conical, and a sealed connection is used between the top cover and the premixing chamber.

[0013] Preferably, a gas-liquid separation component is installed inside the gas-liquid separation chamber, multiple baffles are installed inside the main reaction chamber, and a spiral feeding plate is installed inside the premixing chamber.

[0014] Preferably, the mounting base includes a base plate, a mounting structure, and an adjustment structure. The mounting structure is used to mount the adjustment structure on the bottom of the base plate, and a control box with a door is mounted on the top of the mounting base. The control box contains power switches and controllers for auxiliary equipment operation. The threaded connection between the adjustment structure and the mounting structure allows for adjustment of the stability of the base plate as needed.

[0015] Preferably, the stirring assembly includes a drive structure, a rotating shaft, and a radial stirring blade, wherein the rotating shaft is mounted on the output end of the drive structure, and the radial stirring blade is mounted on the outer surface of the rotating shaft; There are multiple sets of radial stirring blades, each located between multiple baffles.

[0016] Preferably, the sulfuric acid inlet assembly includes an inlet pipe, a branch pipe, and multiple branch heads. The branch pipe is installed at the bottom of the top cover, and the multiple branch heads are installed at the bottom of the branch pipe. The inlet pipe is installed at the inlet of the branch pipe. The gas-liquid separation assembly includes a fixing frame and a separation cone. The fixing frame is used to fix the separation cone inside the gas-liquid separation chamber. The gas collection assembly includes a gas collection port and a gas collection hood. The gas collection port is opened at the top of the top cover, and the gas collection hood is installed at the top of the top cover.

[0017] Compared with related technologies, the method for preparing soil conditioner and co-producing sodium sulfite using magnesium sulfite provided by the present invention has the following beneficial effects: This invention provides a method for preparing soil conditioner from magnesium sulfite and co-producing sodium sulfite. This method achieves full resource utilization, high-value utilization, and harmless treatment of magnesium sulfite, a byproduct of magnesium desulfurization. The raw material conversion rate reaches 100%, and magnesium and sulfur elements are completely recovered. It fundamentally solves the industry problem of long-term magnesium sulfite storage occupying land and polluting the environment. The process adopts a closed-loop sulfur dioxide circulation and mother liquor full reflux design, with no wastewater, waste gas, or solid waste discharge during production, truly achieving near-zero emissions of these three wastes. This aligns with the principles of green, low-carbon, and clean production. The process flow is concise, the reaction conditions are mild, and key process parameters are easily automated. All equipment used is general-purpose chemical equipment, resulting in low construction investment and low operating costs. It can quickly transition from pilot-scale to large-scale industrial production, and the product quality is stable and controllable. (The text also mentions sulfuric acid monohydrate, but this seems unrelated to the main topic and is likely a separate, incomplete sentence.) Magnesium fertilizer has uniform particle size and sufficient nutrients, making it suitable for various agricultural and cash crops. Sodium sulfite has a purity greater than 95%, meeting the requirements for industrial-grade products. Soil conditioner can effectively improve soil structure, enhance soil permeability and fertilizer retention capacity. All three products have strong market adaptability, high added value, and significant economic benefits. Compared with the traditional aeration method for preparing magnesium sulfate and the sulfur combustion method for preparing sodium sulfite, this invention significantly shortens reaction time, reduces energy consumption, and reduces carbon emissions. It transforms solid waste that originally required costly treatment into high-value-added products, while simultaneously achieving a synergistic improvement in environmental, economic, and social benefits. This technology provides a stable, reliable, replicable, and scalable technical route for the efficient resource utilization of magnesium-based desulfurization byproducts, promoting the development of industrial solid waste utilization towards high value, closed-loop, and large-scale development. Attached Figure Description

[0018] Figure 1 A schematic diagram of the first embodiment of the method for preparing soil conditioner and co-producing sodium sulfite from magnesium sulfite provided by the present invention; Figure 2 This invention provides a process flow diagram for the comprehensive utilization of magnesium sulfite; Figure 3 A schematic diagram of the structure of a second embodiment of the method for preparing soil conditioner and co-producing sodium sulfite from magnesium sulfite provided by the present invention; Figure 4 A schematic diagram of the installation structure is provided for this invention; Figure 5 Provided for the present invention Figure 4 An enlarged view of point A shown; Figure 6 Provided for the present invention Figure 4 An enlarged view of point B shown; Figure 7 Provided for the present invention Figure 4 A magnified view of point C shown.

[0019] The diagram is labeled as follows: 1. Mounting base frame; 101. Base plate; 102. Mounting structure; 103. Adjustment structure; 2. Control box; 3. Box door; 4. Support; 5. Discharge structure; 6. Acidification reactor; 601. Gas-liquid separation chamber; 602. Main reaction chamber; 603. Premixing chamber; 604. Top cover; 7. Gas collection assembly; 701. Gas collection port; 702. Gas collection hood; 8. Stirring assembly; 801. Drive structure; 802. Rotating shaft; 803. Radial stirring paddle; 9. Sulfuric acid inlet assembly; 901. Inlet pipe; 902. Diverter pipe; 903. Diverter head; 10. Feed pipe; 11. Spiral distribution plate; 12. Baffle plate; 13. Gas-liquid separation assembly; 131. Fixing frame; 132. Separation cone. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments. Example

[0021] Please refer to the following: Figure 1 , Figure 2 ,in, Figure 1 A schematic diagram of the first embodiment of the method for preparing soil conditioner and co-producing sodium sulfite from magnesium sulfite provided by the present invention; Figure 2 This invention provides a process flow diagram for the comprehensive utilization of magnesium sulfite. The method for preparing soil conditioners and co-producing sodium sulfite from magnesium sulfite includes the following steps: S1: Raw material metering and acidification reaction. Magnesium sulfite, a byproduct of magnesium desulfurization, is accurately metered by a weighing feeder and continuously fed into the acidification reactor. At the same time, 98% concentrated sulfuric acid is slowly added dropwise into the reactor to carry out the acidification reaction. The pH value at the end of the reaction is strictly controlled to be stable at 3-4, so that magnesium sulfite can fully react and be completely converted into magnesium sulfate solution, high-concentration SO2 gas and water. S2: Neutralization, pH adjustment and aging. Add magnesium oxide powder to the magnesium sulfate solution obtained in S1. Adjust the pH of the system to 7-8 under stirring conditions to neutralize the residual acidity in the solution. Then send the mixture into the aging chamber for full cooling and aging to promote the coagulation and sedimentation of trace insoluble impurities and improve the purity of the liquid phase. S3: Solid-liquid separation. The mixture after S2 maturation is sent to a filter press for solid-liquid separation to obtain filter residue and saturated magnesium sulfate filtrate. The main components of the filter residue are silicon dioxide, calcium sulfate and a small amount of magnesium sulfate, and the filtrate is a high-concentration qualified magnesium sulfate solution. S4: Soil conditioner preparation. The filter residue obtained from S3 is dried at low temperature, crushed, homogenized and modified to obtain a soil conditioner product that can improve soil structure and enhance water and fertilizer retention capacity. S5: Preparation of magnesium sulfate monohydrate fertilizer. The magnesium sulfate filtrate obtained in S3 is concentrated and then fed into Raymond mill through a bucket elevator to be ground to 200 mesh to obtain magnesium sulfate monohydrate powder. The powder is then granulated by disc granulation, dried and sieved to obtain magnesium sulfate monohydrate granular fertilizer with uniform particles. S6: SO2 gas purification. The SO2 gas generated in S1 is sequentially processed through dust removal, cooling, deep drying in a sulfuric acid tower, and pressurization by a gas booster to obtain high-purity, low-moisture dry SO2 gas, which is then sent to the alkali absorption system. S7: Sodium sulfite absorption and crystallization. Sodium carbonate solution is used to perform primary and secondary countercurrent absorption of SO2 gas purified by S6. During the absorption process, liquid alkali is added dropwise to control the pH of the absorption liquid at 9-12 to form a saturated sodium sulfite solution, which is then sent to a crystallizer for cooling and crystallization. S8: Sodium sulfite refining. The sodium sulfite crystal slurry obtained from S7 is sent to a centrifuge for solid-liquid separation. The separated wet crystals are dried with hot air to obtain industrial-grade sodium sulfite product with a purity of not less than 95%. All centrifugal mother liquor is returned to the absorption system for recycling. Throughout the preparation process, corrosion-resistant pipes and pumps must be used for material transport between different structures. Pipelines in contact with sulfuric acid, magnesium sulfate, and sodium sulfite solutions should be lined with PTFE or stainless steel to prevent leaks caused by media corrosion. Weighing feeders must be calibrated regularly to ensure metering accuracy and prevent pH loss at the reaction endpoint due to raw material metering deviations. Sulfuric acid dripping pipelines should be equipped with anti-clogging structures to prevent localized crystallization or impurity deposition from affecting feed uniformity. Acidification reactors, maturation chambers, and filter presses must be equipped with online anti-scaling and regular cleaning devices to prevent magnesium sulfate crystals from adhering to the inner walls of the equipment, affecting heat exchange and mass transfer efficiency. SO2 gas transport pipelines must be equipped with water seals and emergency vent valves to prevent gas backflow or abnormal pressure. The concentration of concentrated sulfuric acid used for drying in the sulfuric acid tower must be monitored regularly; it should be replaced promptly when the concentration falls below 93% to ensure efficient gas drying. When preparing the soda ash absorption solution, soft water should be used to dissolve the solid soda ash to prevent calcium and magnesium ions in the water from forming precipitates that clog the absorption tower packing. The liquid ash dripping system should use a corrosion-resistant metering pump to prevent strong alkali from corroding and damaging the equipment. During the concentration of magnesium sulfate filtrate, the evaporation temperature should be controlled to not exceed 120℃ to avoid oversaturation of the solution and scaling of the equipment. The Raymond mill grinding and disc granulation processes require control of ambient humidity to prevent magnesium sulfate monohydrate powder from absorbing moisture and clumping. The filter residue drying temperature should be controlled below 105℃ to prevent the magnesium sulfate in the filter residue from decomposing due to excessive temperature. During the crystallization of sodium sulfite, the cooling rate should be controlled at 5-8℃ / h to prevent crystal growth from being too rapid and carrying impurities. During the operation of each piece of equipment, the wear of the stirring paddle, filter press frame, absorption tower packing, and internal components of the dryer should be checked regularly, and damaged parts should be replaced in a timely manner to ensure continuous and stable production.

[0022] The acidification reaction temperature in S1 is controlled at 30℃-60℃, and the reaction time is 30min-90min. Sulfuric acid is fed by continuous dropwise addition.

[0023] The SO2 gas purification process in S6 includes cyclone dust removal, indirect cooling, deep drying with 98% sulfuric acid, and pressurization by a Roots blower. The water content of the purified gas is ≤0.5%.

[0024] In S7, the mass concentration of the soda ash solution used in the first and second countercurrent absorption is 15%-30%, and the absorption temperature is controlled at 20℃-45℃. In S8, the centrifugal separation speed is 800r / min-1500r / min, the drying temperature is 80℃-120℃, and the moisture content of the dried product is ≤0.3%.

[0025] The working principle of the method for preparing soil conditioner from magnesium sulfite and co-producing sodium sulfite provided by this invention is as follows: This method uses magnesium sulfite, a byproduct of magnesium desulfurization, as the main raw material. Based on the overall mechanism of directional sulfuric acid acidification, efficient gas-liquid separation, gas-phase purification and absorption, liquid-phase neutralization and controlled crystallization, and solid slag resource utilization, it constructs a clean co-production technology system capable of achieving full utilization of solid waste, complete element recovery, and near-zero emissions of waste gas, wastewater, and solid waste. Its core mechanism involves precisely controlling the reaction pH, material ratio, reaction temperature, and material residence time to enable magnesium sulfite to undergo a highly efficient and specific metathesis reaction under set weakly acidic conditions. This completely dissociates magnesium and sulfur elements, allowing them to enter the liquid and gas phases respectively, achieving a high-value phase-separated conversion of the two elements. During the acidification reaction stage, magnesium sulfite and sulfuric acid react at a specific pH... Complete conversion occurs within the range of 3 to 4, producing a soluble magnesium sulfate solution, high-concentration sulfur dioxide gas, and water. This reaction is conducted under mild conditions, requiring neither high temperature nor high pressure, nor prolonged aeration oxidation, significantly reducing energy consumption, shortening the production cycle, and improving conversion efficiency. Strict control of the amount of sulfuric acid added and the final pH value prevents insufficient reaction or over-acidification, ensuring 100% conversion of magnesium sulfite and providing stable and pure intermediate materials for subsequent product preparation. The sulfur dioxide gas generated during acidification undergoes multi-stage dust removal, cooling and dehydration, deep drying in a sulfuric acid tower, and pressurized transportation, effectively removing dust, free water, and other impurities from the gas and preventing contamination. The entry of sulfur dioxide into the absorption system affects the purity of the sodium sulfite product. The purified sulfur dioxide is absorbed using a primary and secondary countercurrent process with a soda ash solution. The pH of the absorption solution is stabilized at 9-12 by adding liquid alkali dropwise, allowing for rapid formation and saturation of sodium sulfite, creating favorable conditions for crystallization. The liquid magnesium sulfate solution is neutralized and adjusted by adding magnesium oxide, raising the pH to 7-8, eliminating residual acidity, improving solution stability, promoting the coagulation and sedimentation of trace insoluble impurities, and enhancing the quality of the final product. The neutralized solution enters a maturation chamber for cooling and stabilization, followed by solid-liquid separation via pressure filtration. The filtrate is then concentrated, ground, and granulated to prepare a 200-mesh monohydrate solution. Magnesium sulfate powder and granular fertilizer, with the filter residue mainly composed of silicon dioxide, calcium sulfate, and a small amount of magnesium sulfate, are dried, crushed, and modified to produce a soil conditioner, achieving full utilization of the solid residue. This method adopts a closed-loop sulfur dioxide circulation and full mother liquor reflux process throughout the entire process, with no waste gas escape and no waste liquid discharge. Through multi-parameter synergistic control, side reactions are suppressed and impurity accumulation is reduced, achieving 100% resource utilization of magnesium and sulfur elements. It integrates the harmlessness of solid waste, resource extraction, and high-value product development into a waste-free, efficient, low-carbon, and stable industrial conversion mechanism, effectively solving common industry problems such as low resource utilization, high energy consumption, long process, low added value, and high environmental pressure of traditional processes.

[0026] Compared with related technologies, the method for preparing soil conditioner and co-producing sodium sulfite using magnesium sulfite provided by the present invention has the following beneficial effects: This method achieves the full resource utilization, high-value utilization, and harmless treatment of magnesium sulfite, a byproduct of magnesium desulfurization. The raw material conversion rate reaches 100%, and magnesium and sulfur elements are completely recovered. It fundamentally solves the industry problem of long-term magnesium sulfite storage occupying land and polluting the environment. The process adopts a closed-loop sulfur dioxide circulation and mother liquor full reflux design, with no wastewater, waste gas, or solid waste discharge during production, truly achieving near-zero emissions of these three wastes. This aligns with the green, low-carbon, and clean production guidelines. The process flow is concise, the reaction conditions are mild, and key process parameters are easily automated. All equipment used is general-purpose chemical equipment, resulting in low construction investment and low operating costs. It can quickly transition from pilot-scale to large-scale industrial production. Product quality is stable and controllable; the monohydrate magnesium sulfate fertilizer has uniform particle size and sufficient nutrients, suitable for... Sodium sulfite with a purity greater than 95% is suitable for various agricultural and cash crops, meeting the requirements for industrial-grade products. Soil conditioners can effectively improve soil structure, enhance soil permeability and fertilizer retention capacity. All three products have strong market adaptability, high added value, and significant economic benefits. Compared with traditional processes for preparing magnesium sulfate by aeration and sodium sulfite by sulfur combustion, this invention significantly shortens reaction time, reduces energy consumption, and reduces carbon emissions. It transforms solid waste that originally required costly treatment into high-value-added products, while simultaneously achieving a synergistic improvement in environmental, economic, and social benefits. This technology provides a stable, reliable, replicable, and scalable technical route for the efficient resource utilization of magnesium desulfurization byproducts, promoting the development of industrial solid waste utilization towards high value, closed-loop, and large-scale development. Example

[0027] Please refer to the following: Figures 3-4 - Figures 5-6 - Figure 7 , Figure 3 A schematic diagram of the structure of a second embodiment of the method for preparing soil conditioner and co-producing sodium sulfite from magnesium sulfite provided by the present invention; Figure 4 A schematic diagram of the installation structure is provided for this invention; Figure 5 Provided for the present invention Figure 4 An enlarged view of point A shown; Figure 6 Provided for the present invention Figure 4 An enlarged view of point B shown; Figure 7 Provided for the present invention Figure 4 The enlarged view at point C shows a method for preparing soil conditioner and co-producing sodium sulfite from magnesium sulfite, based on the first embodiment of this application. The second embodiment of this application proposes another method for preparing soil conditioner and co-producing sodium sulfite from magnesium sulfite. The second embodiment is merely a preferred embodiment of the first embodiment, and its implementation will not affect the individual implementation of the first embodiment.

[0028] Specifically, the method for preparing soil conditioner and co-producing sodium sulfite from magnesium sulfite provided in the second embodiment of this application differs in that the acidification reactor required in the S1 raw material metering and acidification reaction includes: mounting base 1; Acidification reactor 6 is mounted on top of mounting base 1 via bracket 4. A stirring assembly 8 is mounted on top of acidification reactor 6. A gas collecting assembly 7 is mounted on top of acidification reactor 6. A sulfuric acid inlet assembly 9 is mounted on top of acidification reactor 6. A feed pipe 10 is mounted on top of acidification reactor 6. A discharge structure 5 is mounted on bottom of acidification reactor 6. The discharge structure 5 includes pipes and valves, the movable end of the stirring assembly 8 is located inside the acidification reactor 6, and the gas collection assembly 7 is located on the outer surface of the stirring assembly 8.

[0029] Please refer to Figure 3 and Figure 4 The acidification reactor 6 includes a gas-liquid separation chamber 601, a main reaction chamber 602, a premixing chamber 603, and a top cover 604. The gas-liquid separation chamber 601 is installed at the bottom of the main reaction chamber 602, the premixing chamber 603 is installed at the top of the main reaction chamber 602, and the top cover 604 is installed at the top of the premixing chamber 603. The gas-liquid separation chamber 601 is conical, and a sealed connection is used between the top cover 604 and the premixing chamber 603.

[0030] Please refer to Figure 3 and Figure 4 The gas-liquid separation chamber 601 is equipped with a gas-liquid separation component 13, the main reaction chamber 602 is equipped with multiple baffles 12, and the premixing chamber 603 is equipped with a spiral cloth plate 11. The spiral feeding plate 11 adopts a downward-sloping spiral ring plate structure, made of 316L stainless steel, and is a spiral with equal pitch that slopes downward. It is welded and fixed to the inner wall of the upper material premixing chamber. The baffle 12 is a conical plate that tapers downward in the middle, also made of 316L stainless steel. It slopes downward from the cylinder wall to the center. The multi-layer baffles are welded and fixed in an axially staggered manner. A circular through hole is reserved in the center for the stirring shaft to pass through. The gas-liquid separation component 13 is a conical stainless steel cone welded to the inside of the gas-liquid separation chamber. The whole is made of 316L stainless steel and is coaxially and sealed with the central main reaction chamber to achieve gas-liquid gravity separation.

[0031] Please refer to Figure 3 and Figure 4 The mounting base 1 includes a base plate 101, a mounting structure 102 and an adjustment structure 103. The mounting structure 102 is used to install the adjustment structure 103 at the bottom of the base plate 101. A control box 2 with a door 3 is installed on the top of the mounting base 1. The control box 2 is equipped with a power switch and a controller for the operation of auxiliary equipment. The threaded connection between the adjustment structure 103 and the mounting structure 102 can adjust the stability of the base plate 101 as needed.

[0032] Please refer to Figure 3 and Figure 4 The stirring assembly 8 includes a drive structure 801, a rotating shaft 802 and a radial stirring blade 803. The rotating shaft 803 is installed at the output end of the drive structure 801 and the radial stirring blade 803 is installed on the outer surface of the rotating shaft 802. There are multiple sets of radial stirring paddles 803, which are located between multiple baffles 12.

[0033] Please refer to Figure 4 , Figure 5 , Figure 6 and Figure 7 The sulfuric acid inlet assembly 9 includes an inlet pipe 901, a diversion pipe 902, and multiple diversion heads 903. The diversion pipe 902 is installed at the bottom of the top cover 604, and the multiple diversion heads 903 are installed at the bottom of the diversion pipe 902. The inlet pipe 901 is installed at the inlet of the diversion pipe 902. The gas-liquid separation assembly 13 includes a fixing frame 131 and a separation cone 132. The fixing frame 131 is used to fix the separation cone 132 inside the gas-liquid separation chamber 601. The gas collection assembly 7 includes a gas collection port 701 and a gas collection hood 702. The gas collection port 701 is opened at the top of the top cover 604, and the gas collection hood 702 is installed at the top of the top cover 604. The top of the gas collection hood 702 is equipped with a gas exhaust pipe and a corresponding storage structure.

[0034] Compared with related technologies, the method for preparing soil conditioner and co-producing sodium sulfite using magnesium sulfite provided by the present invention has the following beneficial effects: To achieve a highly efficient acidification reaction between magnesium sulfite and sulfuric acid, and to strictly ensure both gas phase purity and liquid phase quality, this process employs a dedicated acidification reactor. This equipment mainly consists of a gas-liquid separation chamber 601, a main reaction chamber 602, a premixing chamber 603, and a top cover. Through a staged contact reaction mode, the acidification reaction between magnesium sulfite and sulfuric acid is effectively enhanced. Simultaneously, the spiral feed plate 11, baffle 12, gas-liquid separation component 13, and stirring component 8 inside the acidification reactor 601 ensure rapid and uniform dispersion and full contact between the magnesium sulfite and sulfuric acid materials entering the equipment, effectively extending the material residence path and enhancing mass transfer efficiency. It also rapidly and completely separates the generated SO2 gas from the magnesium sulfate solution. The gas collection component 7 at the top of the equipment enables comprehensive gas collection, effectively preventing SO2 gas leakage and ensuring safe and environmentally friendly production. During actual operation, the magnesium sulfite... Magnesium sulfate, after precise weighing, is conveyed to the premixing chamber 603 through the feed pipe 10. Under the action of the spiral distribution plate 11, it is evenly spread and distributed. Sulfuric acid is simultaneously dripped into the chamber through the sulfuric acid inlet component 9, completing the initial mixing with the magnesium sulfite material. The premixed material enters the central main reaction chamber 602. Under the synergistic action of the multi-layer baffle 12 and the stirring component 8, the material slowly moves downward along the baffle path, greatly extending the effective reaction time and ensuring that the material reacts fully. At the same time, the pH value of the system is stably controlled in the optimal reaction range of 3-4. The SO2 gas generated by the reaction gathers upward and is uniformly discharged and collected by the top gas collection component 7. The reaction liquid flows downward into the lower gas-liquid separation chamber 601. Relying on the inclined guide slope structure of the gas-liquid separation component 13, the gas rises rapidly and the liquid is discharged downward in a directional manner, efficiently completing the gas-liquid separation operation and ensuring the stability of the reaction and the high purity of the product throughout the process.

[0035] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for preparing a soil conditioner from magnesium sulfite and co-producing sodium sulfite, characterized in that, Includes the following steps: S1: Raw material metering and acidification reaction. Magnesium sulfite, a byproduct of magnesium desulfurization, is accurately metered by a weighing feeder and continuously fed into the acidification reactor. At the same time, 98% concentrated sulfuric acid is slowly added dropwise into the reactor to carry out the acidification reaction. The pH value at the end of the reaction is strictly controlled to be stable at 3-4, so that magnesium sulfite can fully react and be completely converted into magnesium sulfate solution, high-concentration SO2 gas and water. S2: Neutralization, pH adjustment and aging. Add magnesium oxide powder to the magnesium sulfate solution obtained in S1. Adjust the pH of the system to 7-8 under stirring conditions to neutralize the residual acidity in the solution. Then send the mixture into the aging chamber for full cooling and aging to promote the coagulation and sedimentation of trace insoluble impurities and improve the purity of the liquid phase. S3: Solid-liquid separation. The mixture after S2 maturation is sent to a filter press for solid-liquid separation to obtain filter residue and saturated magnesium sulfate filtrate. The main components of the filter residue are silicon dioxide, calcium sulfate and a small amount of magnesium sulfate, and the filtrate is a high-concentration qualified magnesium sulfate solution. S4: Soil conditioner preparation. The filter residue obtained from S3 is dried at low temperature, crushed, homogenized and modified to obtain a soil conditioner product that can improve soil structure and enhance water and fertilizer retention capacity. S5: Preparation of magnesium sulfate monohydrate fertilizer. The magnesium sulfate filtrate obtained in S3 is concentrated and then fed into Raymond mill through a bucket elevator to be ground to 200 mesh to obtain magnesium sulfate monohydrate powder. The powder is then granulated by disc granulation, dried and sieved to obtain magnesium sulfate monohydrate granular fertilizer with uniform particles. S6: SO2 gas purification. The SO2 gas generated in S1 is sequentially processed through dust removal, cooling, deep drying in a sulfuric acid tower, and pressurization by a gas booster to obtain high-purity, low-moisture dry SO2 gas, which is then sent to the alkali absorption system. S7: Sodium sulfite absorption and crystallization. Sodium carbonate solution is used to perform primary and secondary countercurrent absorption of SO2 gas purified by S6. During the absorption process, liquid alkali is added dropwise to control the pH of the absorption liquid at 9-12 to form a saturated sodium sulfite solution, which is then sent to a crystallizer for cooling and crystallization. S8: Sodium sulfite refining. The sodium sulfite crystal slurry obtained from S7 is sent to a centrifuge for solid-liquid separation. The separated wet crystals are dried with hot air to obtain industrial-grade sodium sulfite product with a purity of not less than 95%. All centrifugal mother liquor is returned to the absorption system for recycling.

2. The method for preparing soil conditioner and co-producing sodium sulfite from magnesium sulfite according to claim 1, characterized in that, The acidification reaction in S1 is controlled at a temperature of 30℃-60℃ and a reaction time of 30min-90min. Sulfuric acid is fed by continuous dripping.

3. The method for preparing soil conditioner and co-producing sodium sulfite from magnesium sulfite according to claim 1, characterized in that, The SO2 gas purification process in S6 includes cyclone dust removal, indirect cooling, deep drying with 98% sulfuric acid, and Roots blower pressurization. The purified gas has a moisture content of ≤0.5%.

4. The method for preparing soil conditioner and co-producing sodium sulfite from magnesium sulfite according to claim 1, characterized in that, In S7, the mass concentration of the soda ash solution used in the first and second countercurrent absorption is 15%-30%, and the absorption temperature is controlled at 20℃-45℃. In S8, the centrifugal separation speed is 800r / min-1500r / min, the drying temperature is 80℃-120℃, and the moisture content of the dried product is ≤0.3%.

5. The method for preparing soil conditioner and co-producing sodium sulfite from magnesium sulfite according to claim 1, wherein the acidification reactor used in the S1 raw material metering and acidification reaction is characterized in that, include: Install the base frame; An acidification reactor is mounted on top of a mounting base via a support. A stirring assembly, a gas collecting assembly, a sulfuric acid inlet assembly, and a feed pipe are installed at the top of the acidification reactor. A discharge structure is installed at the bottom of the acidification reactor.

6. The method for preparing soil conditioner and co-producing sodium sulfite from magnesium sulfite according to claim 5, characterized in that, The acidification reactor includes a gas-liquid separation chamber, a main reaction chamber, a premixing chamber, and a top cover. The gas-liquid separation chamber is installed at the bottom of the main reaction chamber, the premixing chamber is installed at the top of the main reaction chamber, and the top cover is installed at the top of the premixing chamber.

7. The method for preparing soil conditioner and co-producing sodium sulfite from magnesium sulfite according to claim 6, characterized in that, The gas-liquid separation chamber is equipped with a gas-liquid separation component, the main reaction chamber is equipped with multiple baffles, and the premixing chamber is equipped with a spiral feeding plate.

8. The method for preparing soil conditioner and co-producing sodium sulfite from magnesium sulfite according to claim 5, characterized in that, The mounting base includes a base plate, a mounting structure, and an adjustment structure. The mounting structure is used to install the adjustment structure at the bottom of the base plate, and a control box with a door is installed at the top of the mounting base.

9. The method for preparing soil conditioner and co-producing sodium sulfite from magnesium sulfite according to claim 5, characterized in that, The stirring assembly includes a drive structure, a rotating shaft, and a radial stirring paddle. The rotating shaft is installed at the output end of the drive structure, and the radial stirring paddle is installed on the outer surface of the rotating shaft.

10. The method for preparing soil conditioner and co-producing sodium sulfite from magnesium sulfite according to claim 5, characterized in that, The sulfuric acid inlet assembly includes an inlet pipe, a branch pipe, and multiple branch heads. The branch pipe is installed at the bottom of the top cover, and the multiple branch heads are installed at the bottom of the branch pipe. The inlet pipe is installed at the inlet of the branch pipe. The gas-liquid separation assembly includes a fixing frame and a separation cone. The fixing frame is used to fix the separation cone inside the gas-liquid separation chamber. The gas collection assembly includes a gas collection port and a gas collection hood. The gas collection port is opened at the top of the top cover, and the gas collection hood is installed at the top of the top cover.

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