A wet desulfurization and harmless treatment process for electrolytic manganese slag

Abstract

This invention discloses a wet desulfurization and harmless treatment process for electrolytic manganese slag, comprising the following steps: S1, pretreatment of electrolytic manganese slag; S2, absorbing CO2 from the tail gas of electrolytic manganese production using dilute ammonia water to generate a mixed solution containing (NH4)2CO3 and NH4HCO3, then adding a composite additive and stirring evenly to obtain a desulfurizing agent; S3, mixing the desulfurizing agent with the pretreated electrolytic manganese slag evenly and reacting under stirring conditions, obtaining a mixed liquid after the reaction is complete; S4, solid-liquid separation; S5, filtrate treatment; S6, crushing and drying the filter residue; S7, collecting the ammonia-containing gas generated in step S6 and converting it into ammonia water, which is then returned to the electrolytic manganese production process for reuse. This invention achieves the harmless treatment and resource utilization of electrolytic manganese slag through pretreatment, desulfurization reaction, solid-liquid separation, and subsequent treatment.

Description

Technical Field

[0001] This invention belongs to the field of solid waste treatment technology, specifically relating to a wet desulfurization and harmless treatment process for electrolytic manganese slag. Background Technology

[0002] my country is a major producer, consumer, and exporter of electrolytic manganese. Most domestic electrolytic manganese producers use domestically produced low-grade manganese carbonate ore as raw material. With the rapid development of the industry, the usable grade of manganese ore has decreased rapidly. Currently, many companies directly use manganese carbonate ore with a manganese grade of 8-13% for electrolytic manganese production, generating more than 10 tons of electrolytic manganese slag for every ton of electrolytic manganese produced. Due to the limited dehydration capacity of current solid-liquid separation equipment, the manganese slag still has a high moisture content of over 20% after solid-liquid separation. This high-moisture-content electrolytic manganese slag contains a large amount of soluble salts, ammonia nitrogen, and heavy metal ions, classifying it as Class II general industrial solid waste. Since most domestic electrolytic manganese slag is currently disposed of by constructing manganese slag storage facilities, the open-air storage of electrolytic manganese slag, after being leached by rainfall, allows pollutants such as ammonia nitrogen, manganese ions, and heavy metal ions in the slag to easily enter the surrounding water environment, causing environmental pollution and damaging the ecosystem.

[0003] The harmless disposal and resource utilization of electrolytic manganese slag is a global challenge. Many scholars and enterprises both domestically and internationally have conducted extensive research and exploration into comprehensive utilization technologies for manganese slag. Based on the main chemical and mineral composition of manganese slag, researchers have conducted studies on various aspects, including the recovery of metallic manganese, fertilizer production, cement production, non-fired brick production, concrete aggregate preparation, roadbed material preparation, soil conditioner, and other roadbed applications. However, due to the high sulfate content in manganese slag, untreated manganese slag is difficult to apply as a raw material in cement production due to its low addition amount and increased desulfurization load, resulting in poor economic benefits.

[0004] When manganese slag is added to cement clinker, the SO3 content must be below 3.5% according to cement product standards. Excessive sulfur content reduces cement strength, increases setting time, and causes expansion cracks. When using manganese slag to prepare non-fired building materials, the high solubility of gypsum in the slag weakens the bonding between gypsum crystals after the product becomes damp, significantly reducing its strength. Furthermore, free water can penetrate the interior of gypsum products through microcracks and high porosity, leading to reduced strength and durability. Using manganese slag as a soil conditioner can also cause soil compaction due to its high gypsum content.

[0005] Currently, the main technologies for the harmless treatment of electrolytic manganese slag include high-temperature melting, high-temperature sintering, and solidification stabilization processes. These processes aim to remove ammonia nitrogen, organic matter, and heavy metal impurities from the electrolytic manganese slag, transforming it from Class II general industrial solid waste to Class I. High-temperature melting involves partially melting the manganese slag at approximately 1300℃, followed by cooling to form a sintered product, which can remove sulfur and ammonia nitrogen from the manganese slag. High-temperature sintering involves completely melting the manganese slag at 950℃, followed by cooling to form a dense glassy product, which can also remove ammonia nitrogen from the manganese slag. Solidification stabilization utilizes physical and chemical methods, or a combination of both, to transform manganese and other heavy metals in the manganese slag into a stable form or fix them in a dense inclusion of a certain strength, thereby reducing the migration of manganese and other heavy metals in the manganese slag and reducing or eliminating the environmental pollution risk posed by the manganese slag. However, all three methods mentioned above have shortcomings in terms of the harmless treatment and resource utilization of manganese slag. Among them, the high-temperature melting process has a good effect on the recovery of sulfur and ammonia, but it has high energy consumption and large investment. Moreover, the pH of the manganese slag leachate is prone to exceed the standard due to the "calcification effect" after melting. Although the high-temperature sintering process has slightly lower energy consumption than the high-temperature melting process, the sulfur resources in the manganese slag cannot be recovered at this temperature. The sulfur still exists in the manganese slag in the form of sulfate, which limits the resource utilization scenarios of the treated manganese slag. The solidification and stabilization process has low processing efficiency due to the batch solid-solid reaction. The stability and uniformity of the harmless treatment of manganese slag are poor. It is difficult for the pH and ammonia nitrogen of the leachate of the treated manganese slag to stably meet the requirements of Class I general industrial solid waste. In addition, the reagent consumption is large and the manganese slag still contains a large amount of sulfate, which is not conducive to resource utilization.

[0006] Chinese patent application CN102161048A discloses a method for the harmless treatment of electrolytic manganese slag, comprising: first, adding quicklime powder and water, and adding a certain amount of silicate additives and stirring; second, adding a certain amount of water-soluble resin sulfonate additives and oxidant ferric chloride to the stirring device; and third, stirring, recovering ammonia gas, and then drying. Chinese patent application CN103286116A discloses a method for the harmless treatment of electrolytic manganese slag, using calcium oxide and sodium phosphate as reagents. In addition, some studies on the harmless treatment of electrolytic manganese slag have been reported in the literature, such as the study on the leaching toxicity and harmless treatment of manganese sulfate waste residue published by Hu Nan et al., and the study on the leaching toxicity and treatment of manganese sulfate waste residue published by Peng Dejiao et al., both of which propose using quicklime to treat electrolytic manganese slag. While these methods are effective in removing soluble manganese and ammonia nitrogen from solidified manganese slag, the amount of quicklime or quicklime combined with other agents required is relatively high. Furthermore, it is difficult for the pH and ammonia nitrogen of the leachate from the treated manganese slag to simultaneously meet the requirements for Class I general industrial solid waste. In addition, these treatment technologies cannot recover sulfates from electrolytic manganese slag, and the sulfate content in the treated manganese slag remains high.

[0007] Therefore, developing a wet desulfurization and harmless treatment process for electrolytic manganese slag, which can harmlessly treat the electrolytic manganese slag and recover sulfates from the slag, thereby reducing the sulfate content of the treated electrolytic manganese slag, is of great significance for solving the problems of high cost and low resource utilization rate of harmless treatment of electrolytic manganese slag. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide a wet desulfurization and harmless treatment process for electrolytic manganese slag.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] A wet desulfurization and harmless treatment process for electrolytic manganese slag includes the following steps:

[0011] S1. Pretreatment of electrolytic manganese slag: After crushing the electrolytic manganese slag, wash it with water to remove soluble salts to obtain pretreated electrolytic manganese slag.

[0012] S2. Preparation of desulfurizing agent: Collect a large amount of carbon dioxide gas generated during the chemical reaction between sulfuric acid and manganese carbonate ore in the electrolytic production of manganese metal. After removing the sulfuric acid mist, mix it with carbon dioxide gas generated during the drying of electrolytic manganese slag and fuel combustion. Send it into a multi-stage absorption tower for absorption by dilute ammonia water to generate a mixed solution of (NH4)2CO3 and NH4HCO3. Then add composite additives and stir evenly to obtain the desulfurizing agent.

[0013] S3. Wet desulfurization reaction: The desulfurizing agent in step S2 is mixed evenly with the pretreated electrolytic manganese slag in step S1 and fed into the reactor. The reaction is carried out under stirring conditions. After the reaction is completed, a mixed liquid is obtained.

[0014] S4. Solid-liquid separation: The mixture in step S3 is separated into solid and liquid components by a chamber filter press. The filter cake is low-sulfur manganese slag after wet desulfurization, and the filtrate is a solution containing ammonium sulfate.

[0015] S5. Filtrate treatment: Evaporate and crystallize the filtrate from step S4 to produce ammonium sulfate fertilizer. The mother liquor from the crystallization is recycled for the preparation of desulfurizing agent.

[0016] S6. Filter residue crushing and drying: Add CaO fine powder to the low-sulfur manganese slag in step S4, crush it again, add it to a mixer after crushing and mix it thoroughly, and then dry it to obtain wet desulfurization low-sulfur manganese slag that can be used as cement admixture, concrete block or roadbed material.

[0017] S7. The ammonia-containing gas generated in step S6 is collected and converted into ammonia water, which is then returned to the electrolytic manganese production process for reuse.

[0018] Preferably, in step S1, the specific steps for pretreating manganese slag are as follows: after collecting the electrolytic manganese slag, it is crushed in a wet ball mill to a particle size ≤0.5mm, then washed with water to obtain a mixed slurry. Next, the mixed slurry is subjected to solid-liquid separation. The filtrate is a mixed solution containing manganese sulfate and ammonium sulfate, and the filter cake is electrolytic manganese slag with low soluble salts. The filter cake is crushed a second time to a particle size ≤1cm to obtain pretreated electrolytic manganese slag.

[0019] In this invention, the original electrolytic manganese slag is usually in the form of lumps or agglomerates with large and uneven particle size. The wet ball milling step can reduce the particle size of the manganese slag to less than 0.5 mm, increase its specific surface area, help improve the water washing efficiency of the manganese slag and the contact area with the desulfurizing agent, promote the reaction, and improve the desulfurization efficiency.

[0020] Preferably, the solid-liquid ratio of the water washing in step S1 is 1:6-8, the water washing temperature is 40-50℃, and the washing time is 30-40 min.

[0021] In this invention, electrolytic manganese slag contains a large amount of soluble salts, such as ammonium sulfate and manganese sulfate. These salts not only affect the subsequent utilization of manganese slag, but also react unnecessarily with desulfurizing agents during the desulfurization process, reducing the desulfurization efficiency of manganese slag and increasing the consumption of desulfurizing agents. Through the crushing and washing steps in the pretreatment, most of the soluble salts can be dissolved and removed, reducing the impurity content in the manganese slag and improving the efficiency and economy of subsequent treatment.

[0022] Preferably, the mass concentration of the dilute ammonia water in step S2 is 8-10%, the content ratio of ammonium carbonate to ammonium bicarbonate in the mixed solution is 1:1-1.5, and the amount of the composite additive added is 2-3% of the mass of the mixed solution.

[0023] In this invention, dilute ammonia water is used to absorb CO2 in the tail gas of electrolytic manganese production as a raw material for desulfurization agent, realizing the resource utilization of waste gas and wastewater, turning waste into treasure, and reducing the production cost of desulfurization agent; at the same time, it reduces the emission of CO2 and ammonia nitrogen wastewater, which is environmentally friendly; the generated ammonium carbonate and ammonium bicarbonate have good desulfurization effect, and the product ammonium sulfate can be used as fertilizer, realizing the recycling of resources.

[0024] In this invention, the composite additive stabilizes the mixed solution of ammonium carbonate and ammonium bicarbonate through chelation and buffering, inhibiting its decomposition, and improves the contact and reaction activity between the desulfurizing agent and manganese slag through surfactants and dispersants, promoting the desulfurization reaction and ultimately improving the properties of the desulfurization products, thus achieving efficient desulfurization of electrolytic manganese slag.

[0025] Preferably, the preparation method of the composite additive in step S2 includes the following steps:

[0026] (a) Sodium gluconate and alkylphenol polyoxyethylene ether are added to deionized water and stirred until homogeneous to obtain solution A;

[0027] (b) Add trisodium citrate and aspartic acid to solution A, and continue stirring until homogeneous to obtain the composite additive.

[0028] Preferably, in step (a), the mass ratio of sodium gluconate, alkylphenol polyoxyethylene ether, and deionized water is 15-25:10-20:100-130, the stirring temperature is 30-40℃, and the stirring time is 20-30 min.

[0029] Preferably, in step (b), the mass ratio of trisodium citrate, aspartic acid, and solution A is 20-30:5-10:125-175, and the stirring time is 20-30 min.

[0030] In this invention, the prepared composite additives, sodium gluconate and trisodium citrate, act as chelating agents, forming stable chelates with metal ions in manganese slag to prevent them from interfering with the desulfurization reaction and to promote the dissolution of sulfides; alkylphenol polyoxyethylene ether, as a nonionic surfactant, reduces surface tension and improves wettability and emulsifying dispersibility; aspartic acid plays a buffering and dispersing role, stabilizing the pH value of the desulfurization system and preventing particle agglomeration; these components work synergistically to improve the overall performance of the desulfurizer.

[0031] Preferably, in step S3, the mass ratio of the desulfurizing agent to the pretreated manganese slag is 2-3:1; the reaction temperature is 25-35℃, the stirring speed is 80-100 r / min, and the time is 2-3 h.

[0032] In the wet desulfurization reaction of this invention, CaSO4, MgSO4, etc. in the electrolytic manganese slag undergo a displacement reaction with (NH4)2CO3 and NH4HCO3 to form more insoluble carbonate precipitates that enter the solid phase. A small amount of Mn in the solution... 2+ With CO3 2- The reaction generates MnCO3 precipitate, which replaces (NH4)2SO4 generated in the reaction and enters the liquid phase, significantly reducing the sulfur content in the electrolytic manganese slag. This achieves the goal of removing most of the sulfate in the solid phase of the electrolytic manganese slag, and the sulfur content of the desulfurized manganese slag meets the standards for resource utilization.

[0033] Preferably, the pressure of the filter press in step S4 is 0.2-0.25 MPa.

[0034] Preferably, the amount of CaO fine powder added in step S6 is 3-5% of the mass of low-sulfur manganese slag, and the wet desulfurization low-sulfur manganese slag accounts for 6-8% of the gel material in cement admixtures, concrete blocks or roadbed materials.

[0035] In this invention, due to the very obvious sticky and wet characteristics of low-sulfur manganese slag, to avoid the manganese slag from sticking together again after crushing and affecting the treatment effect, a specially designed four-shaft shredder is used for the low-sulfur manganese slag crushing equipment, and CaO fine powder with a fineness of ≥100 mesh is added simultaneously during the crushing process. The CaO fine powder has three functions: 1. Dispersing effect, preventing the manganese slag from sticking together again after crushing, thus affecting the treatment effect; 2. CaO fine powder reacts chemically with water in the low-sulfur manganese slag, releasing a large amount of heat of reaction, which can be used to reduce the subsequent drying cost of the low-sulfur manganese slag; 3. CaO fine powder reacts with water in the low-sulfur manganese slag to generate Ca(OH)2, which can further remove or solidify the residual (NH4)2SO4, heavy metal ions, etc. in the manganese slag, achieving the effect of harmless treatment of low-sulfur manganese slag.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) The wet desulfurization and harmless treatment process for electrolytic manganese slag provided by this invention achieves harmless treatment and resource utilization of electrolytic manganese slag through pretreatment, desulfurization reaction, solid-liquid separation and subsequent treatment. Specifically, the pretreatment step effectively removes soluble salts from the manganese slag, reducing the difficulty of subsequent treatment; the desulfurization reaction utilizes the tail gas from electrolytic manganese production to prepare desulfurizing agent, which not only turns waste into treasure and reduces costs, but also significantly reduces the sulfur content in the manganese slag, solving the problem that manganese slag is difficult to utilize due to its high sulfur content; after solid-liquid separation, the low-sulfur manganese slag can be safely used in the building materials field, while the filtrate is used to produce ammonium sulfate fertilizer, realizing the recycling of resources. The entire process is environmentally friendly, economical and efficient.

[0038] (2) The electrolytic manganese slag wet desulfurization and harmless treatment process provided by this invention involves crushing and washing during the pretreatment stage. Crushing increases the specific surface area, which helps to increase the contact area between the manganese slag and the desulfurizing agent, promotes the reaction, and improves the desulfurization efficiency. At the same time, the electrolytic manganese slag contains a large amount of soluble salts, such as ammonium sulfate and manganese sulfate. These salts not only affect the subsequent utilization of manganese slag, but also react unnecessarily with the desulfurizing agent during the desulfurization process, reducing the desulfurization efficiency of manganese slag and increasing the consumption of desulfurizing agent. Through the crushing and washing steps in the pretreatment, most of the soluble salts can be dissolved and removed, reducing the impurity content in the manganese slag and improving the efficiency and economy of subsequent treatment.

[0039] (3) The electrolytic manganese slag wet desulfurization and harmless treatment process provided by the present invention incorporates a composite additive in the preparation of the desulfurizing agent. The composite additive is composed of sodium gluconate, alkylphenol polyoxyethylene ether, trisodium citrate and aspartic acid. The synergistic effect between the various components can improve the dispersibility and stability of the desulfurizing agent, enhance its reactivity with sulfides in manganese slag, thereby improving the desulfurization efficiency and reducing the amount of desulfurizing agent used, thus reducing the treatment cost. Furthermore, the residual components of the composite additive may continue to play a role when the low-sulfur manganese slag is used in concrete. For example, the residue of alkylphenol polyoxyethylene ether can improve the workability of concrete, the residue of chelating agents such as sodium gluconate and trisodium citrate can improve the strength of concrete, and the residue of components such as aspartic acid helps to improve the durability of concrete and improve the overall performance of concrete. Detailed Implementation

[0040] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0041] In this invention, the alkylphenol polyoxyethylene ether is one or more of OP-6, OP-8, and OP-10, preferably OP-8; the electrolytic manganese slag raw material has a moisture content of 25%, a sulfate content of 23.5% (calculated as SO3), and a sulfur content of 12.34%.

[0042] Example 1

[0043] A wet desulfurization and harmless treatment process for electrolytic manganese slag includes the following steps:

[0044] S1. Pretreatment of electrolytic manganese slag: After collecting the electrolytic manganese slag, it is crushed in a wet ball mill to a particle size ≤0.5mm, and then washed with water. The solid-liquid ratio of the water is 1:7, the washing temperature is 45℃, and the time is 35min to obtain a mixed slurry. Then, the mixed slurry is subjected to solid-liquid separation. The filtrate is a mixed solution containing manganese sulfate and ammonium sulfate, and the filter cake is electrolytic manganese slag with low soluble salts. The filter cake is crushed a second time to a particle size ≤1cm to obtain pretreated electrolytic manganese slag.

[0045] S2. Preparation of desulfurizing agent: Collect a large amount of carbon dioxide gas generated during the chemical reaction between sulfuric acid and manganese carbonate ore in the electrolytic production of manganese metal. After removing the sulfuric acid mist, mix it with carbon dioxide gas generated during the drying of electrolytic manganese slag and fuel combustion. Then, send it into a multi-stage absorption tower and absorb it with 9% dilute ammonia water to generate a mixed solution of (NH4)2CO3 and NH4HCO3. Control the content ratio of ammonium carbonate to ammonium bicarbonate in the mixed solution to be 1:1.3. Then, add a composite additive (2.5% of the mass of the mixed solution) and stir evenly to obtain the desulfurizing agent.

[0046] S3. Wet desulfurization reaction: The desulfurizing agent in step S2 is mixed evenly with the pretreated manganese slag in step S1. The mass ratio of the desulfurizing agent to the pretreated manganese slag is 2.5:1. The reaction is carried out under stirring conditions. The reaction temperature is 30℃, the stirring speed is 90r / min, and the time is 2.5h. After the reaction is completed, a mixed liquid is obtained.

[0047] S4. Solid-liquid separation: The mixture in step S3 is separated into solid and liquid components by a chamber filter press. The pressure of the filter press is 0.23 MPa. The filter cake is low-sulfur manganese slag after wet desulfurization, and the filtrate is a solution containing ammonium sulfate.

[0048] S5. Filtrate treatment: The filtrate from step S4 is evaporated and crystallized to produce ammonium sulfate fertilizer. The mother liquor from the crystallization is recycled for the preparation of desulfurizing agent.

[0049] S6. Filter residue crushing and drying: Add CaO fine powder to the low-sulfur manganese slag in step S4. The amount of CaO fine powder added is 4% of the mass of the low-sulfur manganese slag. Use a four-shaft shredder to crush it. After crushing, send it to a mixer through a sealed conveying device to mix it thoroughly, ensuring that the CaO fine powder and the low-sulfur manganese slag react fully. Then send it to a drying oven to dry it. Dry the moisture to 3% to obtain wet desulfurization low-sulfur manganese slag that can be used as cement admixture, concrete block or roadbed material.

[0050] S7. The ammonia-containing gas generated in step S6 is collected and converted into ammonia water, which is then returned to the electrolytic manganese production process for reuse.

[0051] The preparation method of the composite additive in step S2 includes the following steps:

[0052] (a) Add 20g sodium gluconate and 15g OP-8 to 120g deionized water, stir until homogeneous, and stir at 35℃ for 25min to obtain solution A;

[0053] (b) Add 25g of trisodium citrate and 8g of aspartic acid to 155g of solution A, and continue stirring for 25min to obtain the composite additive.

[0054] Example 2

[0055] A wet desulfurization and harmless treatment process for electrolytic manganese slag includes the following steps:

[0056] S1. Pretreatment of electrolytic manganese slag: After collecting the electrolytic manganese slag, it is crushed in a wet ball mill to a particle size ≤0.5mm, and then washed with water. The solid-liquid ratio of the water is 1:6, the washing temperature is 40℃, and the time is 40min to obtain a mixed slurry. Then, the mixed slurry is subjected to solid-liquid separation. The filtrate is a mixed solution containing manganese sulfate and ammonium sulfate, and the filter cake is electrolytic manganese slag with low soluble salts. The filter cake is crushed a second time to a particle size ≤1cm to obtain pretreated electrolytic manganese slag.

[0057] S2. Preparation of desulfurizing agent: Collect a large amount of carbon dioxide gas generated during the chemical reaction between sulfuric acid and manganese carbonate ore in the electrolytic production of manganese metal. After removing the sulfuric acid mist, mix it with carbon dioxide gas generated during the drying of electrolytic manganese slag and fuel combustion. Then, send it into a multi-stage absorption tower and absorb it with 8% dilute ammonia water to generate a mixed solution of (NH4)2CO3 and NH4HCO3. Control the content ratio of ammonium carbonate to ammonium bicarbonate in the mixed solution to be 1:1. Then, add a composite additive (2% of the mass of the mixed solution) and stir evenly to obtain the desulfurizing agent.

[0058] S3. Wet desulfurization reaction: The desulfurizing agent in step S2 is mixed evenly with the pretreated manganese slag in step S1. The mass ratio of the desulfurizing agent to the pretreated manganese slag is 2:1. The reaction is carried out under stirring conditions. The reaction temperature is 25℃, the stirring speed is 80r / min, and the time is 3h. After the reaction is completed, a mixed liquid is obtained.

[0059] S4. Solid-liquid separation: The mixture in step S3 is separated into solid and liquid components by a chamber filter press. The pressure of the filter press is 0.2 MPa. The filter cake is low-sulfur manganese slag after wet desulfurization, and the filtrate is a solution containing ammonium sulfate.

[0060] S5. Filtrate treatment: The filtrate from step S4 is evaporated and crystallized to produce ammonium sulfate fertilizer. The mother liquor from the crystallization is recycled for the preparation of desulfurizing agent.

[0061] S6. Filter residue crushing and drying: Add CaO fine powder to the low-sulfur manganese slag in step S4. The amount of CaO fine powder added is 3% of the mass of the low-sulfur manganese slag. Use a four-shaft shredder to crush it. After crushing, send it to a mixer through a sealed conveying device to mix it thoroughly, ensuring that the CaO fine powder and the low-sulfur manganese slag react fully. Then send it to a drying oven to dry it. Dry the moisture to 3% to obtain wet desulfurization low-sulfur manganese slag that can be used as cement admixture, concrete block or roadbed material.

[0062] S7. The ammonia-containing gas generated in step S6 is collected and converted into ammonia water, which is then returned to the electrolytic manganese production process for reuse.

[0063] The preparation method of the composite additive in step S2 includes the following steps:

[0064] (a) Add 15g sodium gluconate and 10g OP-10 to 100g deionized water, stir until homogeneous, and stir at 30℃ for 30min to obtain solution A;

[0065] (b) Add 20g of trisodium citrate and 5g of aspartic acid to 125g of solution A, and continue stirring for 20min to obtain the composite additive.

[0066] Example 3

[0067] A wet desulfurization and harmless treatment process for electrolytic manganese slag includes the following steps:

[0068] S1. Pretreatment of electrolytic manganese slag: After collecting the electrolytic manganese slag, it is crushed in a wet ball mill to a particle size ≤0.5mm, and then washed with water at a solid-liquid ratio of 1:8, a washing temperature of 50℃, and a washing time of 30min to obtain a mixed slurry. The mixed slurry is then subjected to solid-liquid separation. The filtrate is a mixed solution containing manganese sulfate and ammonium sulfate, and the filter cake is electrolytic manganese slag with low soluble salts. The filter cake is crushed a second time to a particle size ≤1cm to obtain pretreated electrolytic manganese slag.

[0069] S2. Preparation of desulfurizing agent: Collect a large amount of carbon dioxide gas generated during the chemical reaction between sulfuric acid and manganese carbonate ore in the electrolytic production of manganese metal. After removing the sulfuric acid mist, mix it with carbon dioxide gas generated during the drying of electrolytic manganese slag and fuel combustion. Then, send it into a multi-stage absorption tower and absorb it with 10% dilute ammonia water to generate a mixed solution of (NH4)2CO3 and NH4HCO3. Control the content ratio of ammonium carbonate to ammonium bicarbonate in the mixed solution to be 1:1.5. Then, add a composite additive (3% of the mass of the mixed solution) and stir evenly to obtain the desulfurizing agent.

[0070] S3. Wet desulfurization reaction: The desulfurizing agent in step S2 is mixed evenly with the pretreated manganese slag in step S1. The mass ratio of the desulfurizing agent to the pretreated manganese slag is 2.5:1. The reaction is carried out under stirring conditions. The reaction temperature is 35℃, the stirring speed is 100r / min, and the time is 2h. After the reaction is completed, a mixed liquid is obtained.

[0071] S4. Solid-liquid separation: The mixture in step S3 is separated into solid and liquid components by a chamber filter press. The pressure of the filter press is 0.25 MPa. The filter cake is low-sulfur manganese slag after wet desulfurization, and the filtrate is a solution containing ammonium sulfate.

[0072] S5. Filtrate treatment: The filtrate from step S4 is evaporated and crystallized to produce ammonium sulfate fertilizer. The mother liquor from the crystallization is recycled for the preparation of desulfurizing agent.

[0073] S6. Filter residue crushing and drying: Add CaO fine powder to the low-sulfur manganese slag in step S4. The amount of CaO fine powder added is 5% of the mass of the low-sulfur manganese slag. Use a four-shaft shredder to crush it. After crushing, send it to a mixer through a sealed conveying device to mix it thoroughly, ensuring that the CaO fine powder and the low-sulfur manganese slag react fully. Then send it to a drying oven to dry it. Dry the moisture to 3% to obtain wet desulfurization low-sulfur manganese slag that can be used as cement admixture, concrete block or roadbed material.

[0074] S7. The ammonia-containing gas generated in step S6 is collected and converted into ammonia water, which is then returned to the electrolytic manganese production process for reuse.

[0075] The preparation method of the composite additive in step S2 includes the following steps:

[0076] (a) Add 25g sodium gluconate and 20g OP-6 to 130g deionized water, stir until homogeneous, and stir at 40℃ for 20min to obtain solution A;

[0077] (b) Add 30g of trisodium citrate and 10g of aspartic acid to 175g of solution A, and continue stirring for 30min to obtain the composite additive.

[0078] Comparative Example 1

[0079] A wet desulfurization and harmless treatment process for electrolytic manganese slag includes the following steps:

[0080] S1. Pretreatment of electrolytic manganese slag: After collecting the electrolytic manganese slag, it is crushed in a wet ball mill to a particle size ≤0.5mm, and then washed with water. The solid-liquid ratio of the water is 1:7, the washing temperature is 45℃, and the time is 35min to obtain a mixed slurry. Then, the mixed slurry is subjected to solid-liquid separation. The filtrate is a mixed solution containing manganese sulfate and ammonium sulfate, and the filter cake is electrolytic manganese slag with low soluble salts. The filter cake is crushed a second time to a particle size ≤1cm to obtain pretreated electrolytic manganese slag.

[0081] S2. Preparation of desulfurizing agent: Collect a large amount of carbon dioxide gas generated during the chemical reaction between sulfuric acid and manganese carbonate ore in the electrolytic production of manganese metal. After removing the sulfuric acid mist, mix it with carbon dioxide gas generated during the drying of electrolytic manganese slag and fuel combustion. Then, send it into a multi-stage absorption tower and absorb it with 9% dilute ammonia water to generate a mixed solution of (NH4)2CO3 and NH4HCO3. Control the content ratio of ammonium carbonate to ammonium bicarbonate in the mixed solution to be 1:1.3. Then, add a composite additive (2.5% of the mass of the mixed solution) and stir evenly to obtain the desulfurizing agent.

[0082] S3. Wet desulfurization reaction: The desulfurizing agent in step S2 is mixed evenly with the pretreated manganese slag in step S1. The mass ratio of the desulfurizing agent to the pretreated manganese slag is 2.5:1. The reaction is carried out under stirring conditions. The reaction temperature is 30℃, the stirring speed is 90r / min, and the time is 2.5h. After the reaction is completed, a mixed liquid is obtained.

[0083] S4. Solid-liquid separation: The mixture in step S3 is separated into solid and liquid components by a chamber filter press. The pressure of the filter press is 0.23 MPa. The filter cake is low-sulfur manganese slag after wet desulfurization, and the filtrate is a solution containing ammonium sulfate.

[0084] S5. Filtrate treatment: The filtrate from step S4 is evaporated and crystallized to produce ammonium sulfate fertilizer. The mother liquor from the crystallization is recycled for the preparation of desulfurizing agent.

[0085] S6. Filter residue crushing and drying: Add CaO fine powder to the low-sulfur manganese slag in step S4. The amount of CaO fine powder added is 4% of the mass of the low-sulfur manganese slag. Use a four-shaft shredder to crush it. After crushing, send it to a mixer through a sealed conveying device to mix it thoroughly, ensuring that the CaO fine powder and the low-sulfur manganese slag react fully. Then send it to a drying oven to dry it. Dry the moisture to 3% to obtain wet desulfurization low-sulfur manganese slag that can be used as cement admixture, concrete block or roadbed material.

[0086] S7. The ammonia-containing gas generated in step S6 is collected and converted into ammonia water, which is then returned to the electrolytic manganese production process for reuse.

[0087] The preparation method of the composite additive in step S2 includes the following steps:

[0088] Add 45g sodium gluconate and 23g OP-8 to 120g deionized water, stir evenly, and then stir at 35℃ for 25 minutes to obtain the compound additive.

[0089] Compared with Example 1, this comparative example of compound additives did not contain trisodium citrate and aspartic acid.

[0090] Comparative Example 2

[0091] A wet desulfurization and harmless treatment process for electrolytic manganese slag includes the following steps:

[0092] S1. Pretreatment of electrolytic manganese slag: After collecting the electrolytic manganese slag, it is crushed in a wet ball mill to a particle size ≤0.5mm, and then washed with water. The solid-liquid ratio of the water is 1:7, the washing temperature is 45℃, and the time is 35min to obtain a mixed slurry. Then, the mixed slurry is subjected to solid-liquid separation. The filtrate is a mixed solution containing manganese sulfate and ammonium sulfate, and the filter cake is electrolytic manganese slag with low soluble salts. The filter cake is crushed a second time to a particle size ≤1cm to obtain pretreated electrolytic manganese slag.

[0093] S2. Preparation of desulfurizing agent: Collect a large amount of carbon dioxide gas generated during the chemical reaction between sulfuric acid and manganese carbonate ore in the electrolytic production of manganese metal. After removing the sulfuric acid mist, mix it with carbon dioxide gas generated during the drying of electrolytic manganese slag and fuel combustion. Then, send it into a multi-stage absorption tower and absorb it with 9% dilute ammonia water to generate a mixed solution of (NH4)2CO3 and NH4HCO3. Control the content ratio of ammonium carbonate to ammonium bicarbonate in the mixed solution to be 1:1.3. Then, add a composite additive (2.5% of the mass of the mixed solution) and stir evenly to obtain the desulfurizing agent.

[0094] S3. Wet desulfurization reaction: The desulfurizing agent in step S2 is mixed evenly with the pretreated manganese slag in step S1. The mass ratio of the desulfurizing agent to the pretreated manganese slag is 2.5:1. The reaction is carried out under stirring conditions. The reaction temperature is 30℃, the stirring speed is 90r / min, and the time is 2.5h. After the reaction is completed, a mixed liquid is obtained.

[0095] S4. Solid-liquid separation: The mixture in step S3 is separated into solid and liquid components by a chamber filter press. The pressure of the filter press is 0.23 MPa. The filter cake is low-sulfur manganese slag after wet desulfurization, and the filtrate is a solution containing ammonium sulfate.

[0096] S5. Filtrate treatment: The filtrate from step S4 is evaporated and crystallized to produce ammonium sulfate fertilizer. The mother liquor from the crystallization is recycled for the preparation of desulfurizing agent.

[0097] S6. Filter residue crushing and drying: Add CaO fine powder to the low-sulfur manganese slag in step S4. The amount of CaO fine powder added is 4% of the mass of the low-sulfur manganese slag. Use a four-shaft shredder to crush it. After crushing, send it to a mixer through a sealed conveying device to mix it thoroughly, ensuring that the CaO fine powder and the low-sulfur manganese slag react fully. Then send it to a drying oven to dry it. Dry the moisture to 3% to obtain wet desulfurization low-sulfur manganese slag that can be used as cement admixture, concrete block or roadbed material.

[0098] S7. The ammonia-containing gas generated in step S6 is collected and converted into ammonia water, which is then returned to the electrolytic manganese production process for reuse.

[0099] The preparation method of the composite additive in step S2 includes the following steps:

[0100] (a) Add 35g sodium gluconate to 120g deionized water, stir until homogeneous, and stir at 35℃ for 25min to obtain solution A;

[0101] (b) Add 33g of trisodium citrate to 155g of solution A and continue stirring for 25min to obtain the composite additive.

[0102] Compared to Example 1, OP-8 and aspartic acid were not added to the composite additive in this comparative example.

[0103] Comparative Example 3

[0104] A wet desulfurization and harmless treatment process for electrolytic manganese slag includes the following steps:

[0105] S1. Pretreatment of electrolytic manganese slag: After collecting the electrolytic manganese slag, it is crushed in a wet ball mill to a particle size ≤0.5mm, and then washed with water. The solid-liquid ratio of the water is 1:7, the washing temperature is 45℃, and the time is 35min to obtain a mixed slurry. Then, the mixed slurry is subjected to solid-liquid separation. The filtrate is a mixed solution containing manganese sulfate and ammonium sulfate, and the filter cake is electrolytic manganese slag with low soluble salts. The filter cake is crushed a second time to a particle size ≤1cm to obtain pretreated electrolytic manganese slag.

[0106] S2. Preparation of desulfurizing agent: Collect a large amount of carbon dioxide gas generated during the chemical reaction between sulfuric acid and manganese carbonate ore in the electrolytic production of manganese metal. After removing the sulfuric acid mist, mix it with carbon dioxide gas generated during the drying of electrolytic manganese slag and fuel combustion. Then, send it into a multi-stage absorption tower and absorb it with 9% dilute ammonia water to generate a mixed solution of (NH4)2CO3 and NH4HCO3. Control the content ratio of ammonium carbonate to ammonium bicarbonate in the mixed solution to be 1:1.3. Then, add a composite additive (2.5% of the mass of the mixed solution) and stir evenly to obtain the desulfurizing agent.

[0107] S3. Wet desulfurization reaction: The desulfurizing agent in step S2 is mixed evenly with the pretreated manganese slag in step S1. The mass ratio of the desulfurizing agent to the pretreated manganese slag is 2.5:1. The reaction is carried out under stirring conditions. The reaction temperature is 30℃, the stirring speed is 90r / min, and the time is 2.5h. After the reaction is completed, a mixed liquid is obtained.

[0108] S4. Solid-liquid separation: The mixture in step S3 is separated into solid and liquid components by a chamber filter press. The pressure of the filter press is 0.23 MPa. The filter cake is low-sulfur manganese slag after wet desulfurization, and the filtrate is a solution containing ammonium sulfate.

[0109] S5. Filtrate treatment: The filtrate from step S4 is evaporated and crystallized to produce ammonium sulfate fertilizer. The mother liquor from the crystallization is recycled for the preparation of desulfurizing agent.

[0110] S6. Filter residue crushing and drying: Add CaO fine powder to the low-sulfur manganese slag in step S4. The amount of CaO fine powder added is 4% of the mass of the low-sulfur manganese slag. Use a four-shaft shredder to crush it. After crushing, send it to a mixer through a sealed conveying device to mix it thoroughly, ensuring that the CaO fine powder and the low-sulfur manganese slag react fully. Then send it to a drying oven to dry it. Dry the moisture to 3% to obtain wet desulfurization low-sulfur manganese slag that can be used as cement admixture, concrete block or roadbed material.

[0111] S7. The ammonia-containing gas generated in step S6 is collected and converted into ammonia water, which is then returned to the electrolytic manganese production process for reuse.

[0112] The preparation method of the composite additive in step S2 includes the following steps:

[0113] (a) Add 35g sodium gluconate to 120g deionized water, stir until homogeneous, and stir at 35℃ for 25min to obtain solution A;

[0114] (b) Add 33g of aspartic acid to 155g of solution A and continue stirring for 25min to obtain the composite additive.

[0115] Compared with Example 1, OP-8 and trisodium citrate were not added to the composite additive in this comparative example.

[0116] The sulfur content of the treated electrolytic manganese slag in each example and comparative example was determined, and the results are shown in Table 1 below.

[0117] Table 1

[0118]

[0119]

[0120] As can be seen from Table 1 above, the wet desulfurization and harmless treatment process for electrolytic manganese slag provided by the present invention can significantly improve the desulfurization effect of electrolytic manganese slag.

[0121] The dried low-sulfur manganese slag obtained in Example 1 and Comparative Examples 1-3 was used in concrete. The low-sulfur manganese slag accounted for 7% of the cementitious material. The specific proportions were as follows: 450g of PI 42.5 cement, 34g of low-sulfur manganese slag, 968g of crushed stone, 1452g of sand, and 218g of water. After being mixed evenly, the concrete was cured according to standard conditions, and the performance of the concrete was tested. The specific results are shown in Table 2 below.

[0122] Table 2

[0123] 7d flexural strength 28-day flexural strength 7-day compressive strength 28-day compressive strength Example 1 7.5 8.9 40.1 53.2 Comparative Example 1 5.2 7.0 33.4 47.5 Comparative Example 2 5.8 7.7 37.1 50.6 Comparative Example 3 5.7 7.5 35.9 49.3

[0124] As can be seen from Table 2 above, the dry low-sulfur manganese slag prepared by this invention can be used in concrete to give the concrete better mechanical properties and has good application prospects.

[0125] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A wet desulfurization and harmless treatment process for electrolytic manganese slag, characterized in that, Includes the following steps: S1. After crushing the electrolytic manganese slag, wash it with water to remove soluble salts to obtain pretreated electrolytic manganese slag. S2. CO2 in the tail gas of electrolytic manganese production is absorbed by dilute ammonia water to generate a mixed solution containing (NH4)2CO3 and NH4HCO3. Then, a composite additive is added and stirred evenly to obtain a desulfurizing agent. S3. Mix the desulfurizing agent with the pretreated electrolytic manganese slag evenly and react under stirring conditions. After the reaction is completed, a mixed solution is obtained. S4. After the mixture is filtered by hydraulic pressure, low-sulfur manganese slag and filtrate containing ammonium sulfate are obtained; S5. The filtrate is evaporated and crystallized to produce ammonium sulfate fertilizer. The mother liquor from the crystallization is recycled for the preparation of desulfurizing agent. S6. Add CaO fine powder to the low-sulfur manganese slag, crush it again, mix it thoroughly after crushing, and dry it to obtain wet desulfurization low-sulfur manganese slag that can be used as cement admixture, concrete block or roadbed material. S7. The ammonia-containing gas generated in step S6 is collected and converted into ammonia water, which is then returned to the electrolytic manganese production process for reuse. The preparation method of the composite additive in step S2 includes the following steps: (a) Sodium gluconate and alkylphenol polyoxyethylene ether are added to deionized water and stirred until homogeneous to obtain solution A; (b) Add trisodium citrate and aspartic acid to solution A and continue stirring until homogeneous to obtain a composite additive.

2. The wet desulfurization and harmless treatment process for electrolytic manganese slag according to claim 1, characterized in that, In step S1, the specific steps for pretreating electrolytic manganese slag are as follows: after collecting the electrolytic manganese slag, it is crushed in a wet ball mill to a particle size ≤0.5mm, then washed with water to obtain a mixed slurry. Next, the mixed slurry is subjected to solid-liquid separation. The filtrate is a mixed solution containing manganese sulfate and ammonium sulfate, and the filter cake is electrolytic manganese slag with low soluble salts. The filter cake is crushed a second time to a particle size ≤1cm to obtain pretreated electrolytic manganese slag.

3. The wet desulfurization and harmless treatment process for electrolytic manganese slag according to claim 1, characterized in that, In step S1, the solid-liquid ratio of the water wash is 1:6-8, the water wash temperature is 40-50℃, and the time is 30-40 minutes.

4. The wet desulfurization and harmless treatment process for electrolytic manganese slag according to claim 1, characterized in that, In step S2, the mass concentration of the dilute ammonia solution is 8-10%, the content ratio of ammonium carbonate to ammonium bicarbonate in the mixed solution is 1:1-1.5, and the amount of the composite additive added is 2-3% of the mass of the mixed solution.

5. The wet desulfurization and harmless treatment process for electrolytic manganese slag according to claim 1, characterized in that, In step (a), the mass ratio of sodium gluconate, alkylphenol polyoxyethylene ether, and deionized water is 15-25:10-20:100-130, and the stirring temperature is 30-40℃ for 20-30 min.

6. The wet desulfurization and harmless treatment process for electrolytic manganese slag according to claim 1, characterized in that, In step (b), the mass ratio of trisodium citrate, aspartic acid, and solution A is 20-30:5-10:125-175, and the stirring time is 20-30 min.

7. The wet desulfurization and harmless treatment process for electrolytic manganese slag according to claim 1, characterized in that, In step S3, the mass ratio of the desulfurizing agent to the pretreated electrolytic manganese slag is 2-3:1; the reaction temperature is 25-35℃, the stirring speed is 80-100r / min, and the time is 2-3h.

8. The wet desulfurization and harmless treatment process for electrolytic manganese slag according to claim 1, characterized in that, The pressure of the filter press in step S4 is 0.2-0.25 MPa.

9. The wet desulfurization and harmless treatment process for electrolytic manganese slag according to claim 1, characterized in that, The amount of CaO fine powder added in step S6 is 3-5% of the mass of low-sulfur manganese slag, and the wet desulfurization low-sulfur manganese slag accounts for 6-8% of the gel material in cement admixtures, concrete blocks or roadbed materials.

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