Method for harmless disposal of electrolytic manganese residue by dry-wet combination

Abstract

The application discloses a harmless treatment method of electrolytic manganese residue by dry-wet combination. The method comprises the following steps: conveying electrolytic manganese residue, water and alkaline material discharged from a workshop into a slurry tank, mixing the electrolytic manganese residue, water and alkaline material under stirring, filtering the reactants to obtain filter residue and filtrate; adding water into the filter residue and washing the filter residue, filtering the washed material to obtain washed residue and washing liquid; adding alkaline material into the washed residue and introducing CO2 generated by combustion of biomass fuel and / or CO2 discharged from the workshop, and stacking and disposing the treated washed residue and / or recycling the treated washed residue; adding alkaline material into the filtrate and the washing liquid and carrying out stripping treatment, and conveying the treated filtrate and washing liquid to an electrolytic manganese workshop for reuse; and recycling ammonia gas overflowed in the above steps after absorption by an absorbent. The method greatly realizes stable solidification of heavy metals in the electrolytic manganese residue and recycling of ammonia nitrogen, and has obvious economic benefits.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solid waste harmless disposal and resource recycling, and particularly relates to a method for dry-wet combined harmless disposal of electrolytic manganese residue. BACKGROUND

[0002] The electrolytic manganese residue is an acidic waste residue produced after the acid leaching, neutralization and filter pressing process in the process of preparing metal manganese and its oxides by electrolysis. At present, most of the electrolytic manganese residues are disposed in the form of open-air stacking due to technical and economic considerations, and a large amount of leachate is generated during stacking. The electrolytic manganese residue and the leachate contain a large amount of soluble Mn 2+ , NH4 + , SO4 2- , etc. If appropriate protective measures are not taken, the leachate will enter the environment, causing serious pollution to the surrounding soil, air and water resources and endangering human health.

[0003] At present, domestic and foreign scholars have actively explored the harmless disposal of electrolytic manganese residue: such as through the leaching method to transfer the pollutants in the electrolytic manganese residue from solid phase to liquid phase to completely remove the pollutants in the manganese residue, which not only realizes the harmless of the electrolytic manganese residue, but also is beneficial to the resource utilization of the electrolytic manganese residue; or using high-temperature gas flow and high-alkaline materials to harmlessly treat the environmental harmful elements and components such as residual acid, soluble manganese and ammonia nitrogen in the electrolytic manganese residue. The current electrolytic manganese residue harmless disposal patents can realize the solidification of heavy metals and the removal of ammonia nitrogen, but there is still room for further improvement in the treatment process and harmless disposal effect.

[0004] In summary, the harmless disposal of electrolytic manganese residue is mainly aimed at the solidification of heavy metals and the removal of ammonia nitrogen. Therefore, the treatment of heavy metals and ammonia nitrogen is the most important in the harmless treatment of electrolytic manganese residue. However, the above-mentioned technical route of simply using water washing and simply mixing with alkaline materials for harmless disposal of electrolytic manganese residue not only has incomplete harmless disposal effect, but also easily causes secondary pollution. SUMMARY

[0005] The purpose of the present application is to provide a method for dry-wet combined harmless disposal of electrolytic manganese residue, which solves the technical problems of incomplete harmless disposal effect and easy secondary pollution in the prior art by simply using wet and dry methods for harmless disposal of electrolytic manganese residue. The technical effects of the preferred technical solution of the present application are described in detail below.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0007] The method for dry-wet combined harmless disposal of electrolytic manganese residue of the present application comprises the following steps:

[0008] Step S100: electrolytic manganese residue discharged from a workshop is delivered to a slurry tank together with water and alkaline material, and the electrolytic manganese residue is mixed with the water and the alkaline material under stirring to obtain filtrate and filter residue by filtering the reaction mixture;

[0009] Step S200: water is added to the filter residue obtained in step S100, and the filter residue is washed with water to obtain washed residue and washed water by filtering the washed mixture;

[0010] Step S300: alkaline material is added to the washed residue obtained in step S200, and CO2 generated by combustion of biomass fuel and / or CO2 discharged from the workshop is introduced into the washed residue, and the treated washed residue is stacked for disposal and / or resource utilization;

[0011] Step S400: alkaline material is added to the filtrate obtained in step S100 and the washed water obtained in step S200, and the treated filtrate and washed water are delivered to an electrolytic manganese workshop for reuse;

[0012] Step S500: ammonia gas overflowed in steps S100, S300 and S400 is absorbed by an absorbent and reused.

[0013] According to a preferred embodiment, step S100 further comprises the following process: after the electrolytic manganese residue is uniformly mixed with the water and the alkaline material under stirring, the reaction mixture is naturally placed for 0.5-72 hours.

[0014] According to a preferred embodiment, in step S100, the amount of water is 1-12 times the weight of the electrolytic manganese residue, and the alkaline material is quicklime and / or calcined raw material, and the amount of the alkaline material is 3-15% of the weight of the dry electrolytic manganese residue.

[0015] According to a preferred embodiment, in step S100, the reaction mixture is filtered by a diaphragm filter press, and the filtration time is 10-60 minutes, and the temperature of the reaction mixture during filtration is 20-70°C.

[0016] According to a preferred embodiment, in step S200, the solid-liquid ratio of the filter residue to water is 1-5:10, and the washed mixture is filtered by a diaphragm filter press, and the filtration time is 10-60 minutes, and the temperature of the reaction mixture during filtration is 20-70°C.

[0017] According to a preferred embodiment, in step S300, the water content of the washed residue is 19-35%, the alkaline material is quicklime and / or calcined raw material, and the amount of the alkaline material is 1-5% of the weight of the dry electrolytic manganese residue, and the flow rate of CO2 is 200-900 L / min per ton of electrolytic manganese residue.

[0018] According to one preferred embodiment, in step S300, the pH value of the system is 8-9, the reaction temperature of the water washing residue with the alkaline material and CO2 is normal temperature, and the reaction time is 2-72 hours.

[0019] According to one preferred embodiment, in step S400, the alkaline material is NaOH, and the amount of the alkaline material is 1-5% of the weight of the dry electrolytic manganese residue.

[0020] According to one preferred embodiment, in step S400, the method of stripping treatment is:

[0021] The filtrate and the water washing liquid are mixed with the alkaline material in a pipeline mixer to adjust the pH of the wastewater to 10-13, and the alkaline mixed wastewater is obtained.

[0022] The obtained alkaline mixed wastewater is heated to 20-70 DEG C, and then the heated wastewater is sent into a stripping tower to contact and mass transfer with air and fluidized granular packing, the stripped wastewater is discharged from the bottom of the stripping tower, the air containing free ammonia is discharged from the top end of the stripping tower, and the stripping treatment time is 2-72 hours.

[0023] According to one preferred embodiment, in step S100, the overflowed ammonia gas is absorbed by water, and the amount of water is: for every 1 t of electrolytic manganese residue, the amount of water is dry electrolytic manganese residue: water = 1.25: 1-0.6;

[0024] The overflowed ammonia gas in steps S300 and S400 is absorbed by sulfuric acid with a concentration of 0.2-0.5 mol / L, and the amount of sulfuric acid is: for every 1 t of electrolytic manganese residue, the amount of sulfuric acid is dry electrolytic manganese residue: sulfuric acid = 1.25: 1-0.6;

[0025] The absorption time of the ammonia gas is 2-5 hours.

[0026] The method for harmless disposal of electrolytic manganese residue provided by the application at least has the following beneficial technical effects:

[0027] In the first aspect, the method for harmless disposal of electrolytic manganese residue by dry-wet method provided by the application uses low-cost alkaline material and water to carry out two hydration reactions on the electrolytic manganese residue discharged from the workshop, and through the reaction of the alkaline material with the sulfate ions, ammonium ions and manganese ions in the electrolytic manganese residue, the stable solidification of the heavy metals in the electrolytic manganese residue and the recycling of ammonia nitrogen are greatly realized, and obvious economic benefits are obtained.

[0028] In the second aspect, the method for harmless disposal of electrolytic manganese residue by dry-wet method provided by the application, the waste liquid and ammonia-containing waste gas generated during the treatment of the electrolytic manganese residue are treated by the treatment device and can be reused as production water and production auxiliary materials, and are not discharged, which greatly improves the water recycling rate and reduces the secondary pollution of the wastewater and the ammonia-containing waste gas.

[0029] In a third aspect, the method for harmless treatment of electrolytic manganese residue by dry-wet combination of the present application, while the water-washed residue is solidified again by adding alkaline material, CO2 is also introduced to assist and enhance the stable solidification of heavy metals in the water-washed residue by the alkaline material; at the same time, the CO2 is the CO2 produced by biomass fuel combustion and / or the CO2 discharged by the workshop, so that the carbon emission reduction target of the electrolytic manganese enterprise is achieved while the stable solidification of heavy metals is enhanced. In addition, the electrolytic manganese residue after harmless treatment can be used to prepare building material products such as synthetic sand, cement admixture and autoclaved aerated concrete.

[0030] In a fourth aspect, the method for harmless treatment of electrolytic manganese residue by dry-wet combination of the present application, by combining the wet method (adding water) with the dry method (adding alkaline material), the soluble heavy metals and ammonia nitrogen in the electrolytic manganese residue can be effectively removed, the resource utilization of heavy metals is realized, and the secondary pollution of ammonia nitrogen is reduced; at the same time, the method of the present application has simple process operation, low energy consumption, environmental safety and economic feasibility, which provides a new idea for the harmless treatment and resource utilization of electrolytic manganese residue, improves the environmental and social benefits of electrolytic manganese residue, and solves the problem that a single method is difficult to realize low-cost, large-scale, harmless and resourceful treatment of electrolytic manganese residue generated by electrolytic manganese enterprises.

[0031] Therefore, the method for harmless treatment of electrolytic manganese residue by dry-wet combination of the present application solves the technical problem that the existing technology uses only the wet method and the dry method to harmlessly treat electrolytic manganese residue, which is not thorough and easy to cause secondary pollution. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0033] Figure 1 is the process flow chart of the method for harmless treatment of electrolytic manganese residue by dry-wet combination of the present application. EMBODIMENT

[0034] In order to make the purpose, technical solutions and advantages of the present application more clear, the technical solutions of the present application will be described in detail below. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of the present application.

[0035] The harmless treatment of electrolytic manganese residue mainly aims at solidification of heavy metals and removal of ammonia nitrogen, however, the simple water washing (wet method) and the simple stirring and mixing with alkaline materials such as lime (dry method) and other technical routes for the harmless treatment of electrolytic manganese residue not only have incomplete harmless treatment effect, but also easily cause secondary pollution. Therefore, the present application is based on the fact that the electrolytic manganese residue contains a large amount of soluble manganese ions and ionic NH4 + , SO4 2- , and the electrolytic manganese residue is treated by the combined process of the on-site wet method and the dry method, and the production wastewater is recycled and not discharged, so that the stable solidification of heavy metals and the recycling of ammonia nitrogen are achieved. The present application provides a simple, environmentally safe and economically feasible method for the harmless treatment of electrolytic manganese residue.

[0036] The method for the combined dry and wet harmless treatment of electrolytic manganese residue will be described in detail below in combination with the accompanying Figure 1 and examples 1-3.

[0037] Figure 1 The process flow diagram of the combined dry and wet harmless treatment of electrolytic manganese residue is shown.

[0038] As shown in the figure, the method for the combined dry and wet harmless treatment of electrolytic manganese residue comprises the following steps: Figure 1 Step S100: conveying the electrolytic manganese residue discharged from the workshop, water and alkaline materials into a slurry tank, mixing the electrolytic manganese residue, water and alkaline materials under stirring conditions, and filtering the reactants to obtain filter residue and filtrate.

[0039] Specifically, in this step, the initial material is the electrolytic manganese residue discharged from the workshop (the electrolytic manganese residue is one or more of the residues discharged from the filter pressing workshop or the on-line countercurrent backwashing equipment), the treatment agent added is water and alkaline materials (such as lime and / or calcined raw material), then after uniform stirring and mixing, the mixture is placed for a period of time, and then pressure filtration is performed. The finally formed new material is Ca(OH)2, CaSO4·2H2O, Mn(OH)2, MnOOH, MnO2, etc. The lime and / or calcined raw material provides an alkaline environment, which is beneficial to the generation of Mn(OH)2, and Mn(OH)2 is easily oxidized to MnO2 (stable form of insoluble substance). The reaction between lime and / or calcined raw material and manganese residue releases heat to evaporate part of the water, and the addition of extra water can enhance the hydration and improve the mixing effect. The chemical reaction equation of this step is:

[0040] (1) CaO + H2O → Ca(OH)2↓

[0041] (2) CaO + 3H2O + MnSO4 → CaSO4·2H2O↓ + Mn(OH)2↓

[0042] (3) Mn(OH)2 + 2H2O + 1 / 2O2 → MnO2↓ + 2H2O

[0043] (4) MnOOH + 2H2O + 1 / 2O2 → MnO2↓ + 2H2O(3) Ca(OH)2+ (NH4)2SO4→ CaSO4·2H2O↓ + 2NH3↑

[0044] (4) 4Mn(OH)2+ O2→ 4MnOOH + 2H2O

[0045] (5) 2Mn 3+ + 2H2O→ Mn 2+ + MnO2↓ + 4H +

[0046] Preferably, the step further comprises the following process: after the electrolytic manganese residue is mixed with water and alkaline material uniformly under stirring, the reactants are left naturally for 0.5-72 hours. More preferably, the reactants are left naturally for 72 hours. Since the free ammonia nitrogen in the electrolytic manganese residue is physically wrapped, its release is a very slow process. The present application helps the free ammonia nitrogen in the electrolytic manganese residue to be released fully by leaving the reactants naturally for a period of time after they are mixed with water and alkaline material uniformly under stirring, thereby improving the treatment effect of the method of the present application on ammonia nitrogen.

[0047] Preferably, in the step, the reactants are filtered by a diaphragm filter press, and the filtration time is 10-60 minutes, and the temperature of the reactants during the filtration is 20-70°C. The present application controls the filtration time to be 10-60 minutes, which can ensure that the reactants are filtered thoroughly, avoiding the problem that the filter residue contains too many heavy metal ions and sulfate, which leads to heavier subsequent treatment burden. When the temperature is too low, ammonium sulfate precipitates due to supersaturation, which blocks the pipeline and makes water washing and final filtration unable to proceed smoothly. When the temperature is too high, water evaporation is accelerated, which is not conducive to the subsequent hydration of the alkaline material, and has an opposite effect on the removal of ammonia nitrogen in the alkaline material treated manganese residue. The present application controls the temperature of the reactants during the filtration to be 20-70°C, which not only ensures the normal progress of the filtration process, but also avoids the problem that the quicklime and / or calcined raw material become dry due to too high temperature.

[0048] Preferably, in the step, the amount of water is 1-12 times the weight of the electrolytic manganese residue (the electrolytic manganese residue herein usually has a moisture content of 19-35%). The present application controls the amount of water to be 1-12 times the weight of the electrolytic manganese residue, which is conducive to keeping the consistency of the reactants (a mixture of alkaline material, electrolytic manganese residue and water) in the slurry tank appropriate, which is conducive to the full progress of the hydration reaction and the escape of ammonia nitrogen, thereby enabling the ammonia nitrogen in the electrolytic manganese residue to be released fully, improving the treatment effect of the method of the present application on ammonia nitrogen. Specifically, if the amount of water is too small, the consistency of the reactants will be too dry, which is not conducive to the full progress of the hydration reaction, and also causes the manganese residue to be severely agglomerated and not conducive to the escape of ammonia nitrogen. If the amount of water is too large, the consistency of the reactants will be too thin, and the free ammonia will dissolve in water, which is not easy to escape, thereby increasing the difficulty of subsequent sewage treatment and increasing secondary pollution.

[0049] Preferably, in this step, the alkaline material is quicklime and / or calcined raw meal, and the amount of the alkaline material is 3-15% of the weight of the dry basis electrolytic manganese residue (the dry basis electrolytic manganese residue refers to the part of the electrolytic manganese residue with a moisture content of 19-35%, excluding water). The present application controls the amount of the alkaline material to be 3-15% of the weight of the dry basis electrolytic manganese residue, which can ensure that the alkaline material and the electrolytic manganese residue are fully reacted. Further, the alkaline material is quicklime and / or calcined raw meal, which can react with the moisture in the manganese residue to release heat, and has the following effects: (1) adsorption, the hydration product of quicklime and / or calcined raw meal has the characteristics of large specific surface area, small crystal grains, and many micropores, etc., which can adsorb and encapsulate Mn 2+ , NH4 + -N, etc.; (2) chemical reaction, the hydration reaction can form a good alkaline environment, and react with Mn 2+ , NH4 + -N, etc. in the micropores of the manganese residue particles to fix Mn 2+ in the precipitate, and convert NH4 + -N into free NH3; (3) Mn 2+ solidification, the solidification of Mn 2+ includes immobilization and encapsulation, and a stabilization reaction, i.e., Mn 2+ is encapsulated and fixed, and at the same time, a chemical reaction occurs, and then Mn 2+ is converted into a stable form of difficultly soluble substance through oxidation, and is stabilized in the manganese residue, the manganese residue and the quicklime and / or calcined raw meal are mixed with air, and O2oxidizes Mn + to MnO2; (4) NH4 + -N removal, after the manganese residue and the quicklime and / or calcined raw meal are mixed, the system is alkaline, and the ammonium salt can be converted into free ammonia in a suitable alkaline environment, the heat released by the reaction of the quicklime and / or calcined raw meal with water accelerates the conversion of free ammonia into gaseous ammonia, and finally, the NH4 + -N is removed in the form of ammonia gas. Without being limited thereto, the alkaline material in this step can also be NaOH, etc.

[0050] Step S200: water is added to the filter residue obtained in step S100, and the filter residue is washed with water, and the washed material is filtered to obtain a washed residue and a washing liquid.

[0051] Specifically, the initial material of this step is the filter residue (still containing part of the heavy metal ions and ammonium salt) after the pressure filtration of step S100, and the treatment agent added is water. By washing the filter residue in step S100 with water, the impurities, harmful substances and water-soluble salts (such as soluble salt substances such as chlorine and iron) in the filter residue can be separated out by the flushing and dissolving action of water, and then the impurities, harmful substances and water-soluble salts in the aqueous solution can be separated out by filtration, precipitation and other methods, so as to achieve the purpose of cleaning and harmless treatment of the filter residue.

[0052] Preferably, in this step, the solid-liquid ratio of the filter residue to water is 1-5:10. The present application controls the amount of water added to be 2-10 times the weight of the filter residue, which can ensure the complete dissolution and removal of impurities, harmful substances and water-soluble salts in the filter residue.

[0053] Preferably, the water-washed material is pressure-filtered by a diaphragm filter press, and the pressure filtration time is 10-60 min, and the temperature of the reaction material during pressure filtration is 20-70°C. In step S100, the present application controls the pressure filtration time to be 10-60 min, which can ensure complete pressure filtration of the reaction material and avoid the problem of too many heavy metal ions and sulfate salts in the filter residue, which leads to an increased burden on subsequent treatment; the present application controls the temperature of the reaction material during pressure filtration to be 20-70°C, which not only ensures the normal progress of the pressure filtration process, but also avoids the problem of the quicklime and / or calcined raw material becoming dry due to too high a temperature.

[0054] Step S300: adding an alkaline material to the water-washed residue obtained in step S200 and introducing CO2 produced by the combustion of biomass fuel and / or CO2 discharged from the workshop, and then stacking and disposing of the treated water-washed residue and / or recycling it.

[0055] Specifically, in this step, the initial material is the water-washed residue obtained in step S200, an alkaline material is added, and CO2 produced by the combustion of biomass fuel and / or CO2 discharged from the workshop is introduced, so that the heavy metals and ammonia nitrogen that have not been completely treated in step S100 can be stabilized and solidified again or escaped. Preferably, the alkaline material introduced is quicklime and / or calcined raw material, and after treatment by this step, the generated products are not only Ca(OH)2, CaSO4·2H2O, Mn(OH)2, MnOOH, MnO2, but also MnCO3, CaCO3, MgCO3, etc. The quicklime and / or calcined raw material introduced here can also play a role in strengthening the stable solidification of heavy metals and the efficient removal of ammonia nitrogen, as in step S100; at the same time, the CO2 discharged from the manganese ore workshop and the CO2 produced by the combustion of biomass fuel are captured by the manganese slag, which not only achieves the carbon emission reduction target of the electrolytic manganese enterprise, but also solves the problem of manganese slag pollution in the electrolytic manganese enterprise.

[0056] The chemical reaction equation of this step (and the repeated reaction in step S100 is not listed):

[0057] (6) CO2 + 2OH − → CO3 2− + H2O

[0058] (7) Mn 2+ + CO3 2− → MnCO3↓

[0059] (8) Ca 2+ + CO3 2− → CaCO3↓

[0060] (9) Mg 2+ + CO3 2− → MgCO3↓

[0061] Preferably, in this step, the water content of the water washed residue is 19-35%. Not only can it ensure the full hydration of the quicklime and / or calcined raw material, thereby ensuring the heavy metal solidification and ammonia-nitrogen removal effect, but also can avoid the problem that the water washed residue is too sticky, which is not conducive to the ammonia-nitrogen escaping and the alkalinity of the reaction system being too low, resulting in a decrease in the heavy metal solidification and ammonia-nitrogen removal rate.

[0062] Preferably, in this step, the alkaline material is quicklime and / or calcined raw material, and the amount of the alkaline material is 1-5% of the dry basis weight of the electrolytic manganese residue. The quicklime and / or calcined raw material has the same effect as in step S100, and the addition of the alkaline material to the water washed residue is to further stabilize the residual soluble manganese ions and efficiently remove the residual ammonia-nitrogen. Since the water washed residue contains less heavy metals and ammonium salt than the electrolytic manganese residue discharged from the workshop, controlling the amount of quicklime and / or calcined raw material to be 1-5% of the dry basis weight of the electrolytic manganese residue can ensure that the quicklime and / or calcined raw material fully reacts with the residual soluble manganese ions and ammonia-nitrogen in the water washed residue, thereby further improving the heavy metal stabilization and ammonia-nitrogen removal effect. Without being limited thereto, the alkaline material in this step can also use NaOH and other alkaline materials.

[0063] Preferably, in this step, the pH value of the system is 8-9, and the reaction temperature of the water washed residue with the alkaline material and CO2 is room temperature, and the reaction time is 2-72h. After the addition of the alkaline material, the pH value of the system is 8-9, and CO2 will generate CO3 2− in the alkaline environment. CO3 2− can react with a small amount of heavy metal ions in the water washed residue to generate carbonate precipitate, thereby further improving the heavy metal stabilization effect. Further, before the CO2 is introduced, the addition of the alkaline material makes the pH value of the system 8-9, which is conducive to the formation of CO3 2−and the ammonium ions and the sulfate ions in the water washing residue can be removed again by the alkaline material (in step S100, most of the ammonium ions and the sulfate ions in the electrolytic manganese residue have been removed by the alkaline material), so that the CO3 2− reacts with the small amount of heavy metal ions remaining in the water washing residue to form carbonate precipitate, so that the heavy metal stabilization and solidification effect can be further improved. 2− The reaction between the CO3 2− and the heavy metal ions in the water washing residue is a slow process, and the conversion of ammonia nitrogen into gaseous ammonia is also a very slow process. If the reaction time is controlled to be 2-72h, the ammonium salt and the sulfate salt can be diffused out of the impurities, the carbonation reaction and the generation of ammonia gas can be promoted, and the heavy metal stabilization and solidification effect and the ammonia nitrogen removal effect can be further improved.

[0064] Preferably, in this step, the flow rate of CO2 is 200-900L / min per ton of electrolytic manganese residue. In the alkaline environment, the CO2 reacts with the OH- to form CO3 2− , and the CO3 2− reacts with the heavy metal ions in the water washing residue to form carbonate precipitate. By controlling the flow rate of CO2, the concentration of CO3 2− can be controlled. Specifically, the flow rate of CO2 is 200-900L / min per ton of electrolytic manganese residue. Not only can the concentration of CO3 2− in the system be kept in a supersaturated state, but also the supersaturation degree is the driving force of the crystallization reaction. Moreover, the carbonate crystallization can generate small-particle-size particles. The smaller the crystal grain size is, the more the number of crystal grain boundaries is, and the greater the resistance of dislocation movement is, so that the plastic deformation resistance of the metal is increased. Specifically, if the amount of CO2 introduced is too large, the CO3 2− will be enriched, the local carbonate concentration will be too high, and the formation of small-particle-size particles will be adversely affected. When the temperature is 80-100℃, the reaction rate is increased, but high temperature is not conducive to nucleation reaction. Only by increasing the supersaturation degree of the system can the nucleation rate be increased and the carbonate particle size be reduced. If the flow rate of CO2 is too small, the concentration of CO3 2− in the system cannot reach a supersaturated state, so that the crystal nucleus cannot be aggregated and grown, and small-size particles cannot be formed. Therefore, the carbonate particle size is affected by both the temperature and the CO2 flow rate. Under normal temperature conditions, the control of the CO2 flow rate to be 200-900L / min is beneficial to the carbonate crystallization to generate small-particle-size particles.

[0065] Step S400: The alkaline material is added to the filtrate obtained in step S100 and the water washing liquid obtained in step S200, and the blow-off treatment is performed. The treated filtrate and water washing liquid are transported to the electrolytic manganese workshop for reuse.

[0066] Specifically, the initial material of this step is the filtrate obtained in step S100 and the water washing liquid obtained in step S200. Since there is soluble ammonia nitrogen in the filtrate and the water washing liquid, the ammonia nitrogen can be converted into ammonia gas by adding alkaline material, and then the free ammonia can be removed from the system by stripping treatment and converted into ammonia gas which is collected for resource utilization. The chemical reaction equation of this step is:

[0067] (10) NH4 + + OH − → NH3↑ + H2O

[0068] Preferably, in this step, the alkaline material is NaOH, and the amount of the alkaline material is 1-5% of the weight of the dry electrolytic manganese residue. The alkaline material is added again in the water washing liquid and the filtrate to make the system alkaline, so that the ammonia nitrogen in the solution is converted into gaseous ammonia to escape, so as to further improve the ammonia nitrogen removal effect. Since the water washing liquid and the filtrate contain less ammonia nitrogen than the manganese residue discharged from the workshop, the amount of the alkaline material is controlled to be 1-5% of the weight of the dry electrolytic manganese residue, so as to ensure that the ammonia nitrogen in the solution fully escapes.

[0069] Preferably, in this step, the stripping treatment method is as follows:

[0070] The filtrate and the water washing liquid are mixed with the alkaline material in a pipeline mixer to adjust the pH of the wastewater to 10-13 to obtain alkaline mixed wastewater;

[0071] The obtained alkaline mixed wastewater is heated to 20-70°C, and then the heated wastewater is sent into a stripping tower to contact and mass transfer with air and fluidized granular packing (the granular packing is one or more of activated carbon, biological ceramsite or rare earth porcelain sand), the wastewater after stripping is discharged from the bottom of the stripping tower, the air containing free ammonia is discharged from the top of the stripping tower, and the stripping treatment time is 2-72h.

[0072] Specifically, the stripping treatment is a slow process. In the conversion process of ammonia nitrogen, the release of ammonia nitrogen is a long-term process, and the stripping mainly enhances the gas convection to enhance the release of ammonia nitrogen in the solution, so the stripping treatment time is controlled to be 2-72h to ensure that the ammonia nitrogen is fully released. On the other hand, the system is heated to 20-70°C, which can greatly promote the conversion of NH4 + to NH3 in the alkaline and heated system, and can also avoid the problem of excessive temperature and accelerated water evaporation, which has an opposite effect on the removal of ammonia nitrogen in the alkaline material treatment solution, and also causes waste of energy consumption.

[0073] Step S500: The ammonia gas overflowed in steps S100, S300 and S400 is reused after being absorbed by an absorbent.

[0074] Specifically, the initial material of this step is ammonia gas, by adding an absorbent (water, dilute sulfuric acid, anode liquid, etc. one or more of them), (NH4)2SO4 and NH3·H2O, etc. new materials can be formed and recycled. The chemical reaction equation of this step is:

[0075] (11) NH3↑+ H2O → NH3·H2O;

[0076] (12) NH3↑+ H2SO4→ (NH4)2SO4

[0077] Preferably, the ammonia gas overflowed in step S100 is absorbed by water, and the amount of water used is: for every 1 t of electrolytic manganese residue, the amount of water used is dry basis electrolytic manganese residue: water = 1.25:1~0.6 (dry basis electrolytic manganese residue is weight, unit is g; absorbent is volume, unit is mL), and the absorption time of ammonia gas is 2~5h.

[0078] Preferably, the ammonia gas overflowed in steps S300 and S400 is absorbed by sulfuric acid with a concentration of 0.2~0.5mol / L, and the amount of sulfuric acid used is: for every 1 t of electrolytic manganese residue, the amount of sulfuric acid used is dry basis electrolytic manganese residue: sulfuric acid (referring to dilute sulfuric acid with a concentration of 0.2~0.5mol / L) = 1.25:1~0.6 (dry basis electrolytic manganese residue is weight, unit is g; absorbent is volume, unit is mL), and the absorption time of ammonia gas is 2~5h.

[0079] The ammonia gas escaped in step S100 has a high concentration, and is absorbed by clean water. High-concentration ammonia gas is easily dissolved in water to form ammonia water, which can be recycled to the electrolytic manganese process. The clean water here can be the water produced in the method of the present application. The ammonia gas overflowed in steps S300 and S400 has a low concentration and can be absorbed by dilute sulfuric acid. The ammonia gas overflowed in steps S300 and S400 has a lower concentration than the ammonia gas produced in step S100, because the manganese ions and ammonia nitrogen are treated for the first time in the pulping tank using alkaline materials, and the remaining ammonia nitrogen in the entire system is much less, so the released ammonia gas is also less.

[0080] Without limitation, the escaped ammonia gas can also be absorbed by anode liquid, which is a liquid produced in the electrolytic manganese workshop, and the main components are: 12~15g / L of MnSO4, 80~90g / L of (NH4)2SO4 and 35~45g / L of H2SO4.

[0081] The method for harmless treatment of electrolytic manganese residue by dry-wet combination of the above scheme first carries out two hydration reactions on the electrolytic manganese residue discharged from the workshop by using low-cost alkaline materials and water. Through the reaction of alkaline materials with sulfate ions, ammonium ions and manganese ions in the electrolytic manganese residue, the stable solidification of heavy metals in the electrolytic manganese residue and the recycling of ammonia nitrogen are greatly realized, which has obvious economic benefits. Second, the waste liquid and ammonia-containing waste gas generated in the process of treating the electrolytic manganese residue can be reused as production water and production auxiliary materials after being treated by the treatment device, without being discharged, which greatly improves the water recycling rate and reduces the secondary pollution of waste water and ammonia-containing waste gas. Third, while the water-washed residue is solidified again by adding alkaline materials, CO2 is also introduced to assist the stable solidification of heavy metals in the water-washed residue by the alkaline materials. At the same time, the CO2 is the CO2 generated by the combustion of biomass fuel and / or the CO2 discharged from the workshop, so that the stable solidification of heavy metals is enhanced while achieving the carbon emission reduction target of the electrolytic manganese enterprise. The electrolytic manganese residue after harmless treatment can also be used to prepare synthetic sand, cement admixture and autoclaved aerated concrete and other building material products. Fourth, the method combines wet method (adding water) with dry method (adding alkaline materials) to effectively remove soluble heavy metals and ammonia nitrogen in the electrolytic manganese residue, realize the resource utilization of heavy metals and reduce the secondary pollution of ammonia nitrogen. At the same time, the method has simple process operation, low energy consumption, environmental safety and economic feasibility, which provides a new idea for the harmless treatment and resource utilization of electrolytic manganese residue, improves the environmental and social benefits of electrolytic manganese residue, and solves the problem that a single method is difficult to realize low-cost, large-scale, harmless and resourceful treatment of electrolytic manganese residue generated by electrolytic manganese enterprises.

[0082] Example 1

[0083] The method for harmless treatment of electrolytic manganese residue by dry-wet combination of the present embodiment includes the following steps:

[0084] Step S100: 1t of electrolytic manganese residue with a water content of 27% (the manganese content of the electrolytic manganese residue is 1481.22mg / L, NH4 + -N concentration is 680.99mg / L, that is, m1=1481.22mg / L, h1=680.99mg / L) discharged from the filter press workshop is transported to the slurry tank, then 5t of water and 43.8kg of quicklime are added to the slurry tank, and after reacting for 72h, it is transported to the diaphragm filter press for solid-liquid separation under the conditions of pressure filtration for 16min and pressure filtration temperature of 60℃, to obtain filter residue and filtrate.

[0085] Step S200: after water washing of the filter residue by adding 3.5t of water, it is transported to the diaphragm filter press for solid-liquid separation under the conditions of pressure filtration for 16min and pressure filtration temperature of 60℃, to obtain water-washed residue with a water content of 27% and water washing liquid.

[0086] Step S300: 7.3 kg of calcined raw material was added to the water washed residue with a water content of 27% for reaction and 600 L / min of CO2 was introduced, and the reaction was carried out for 72 h without additional heating.

[0087] Step S400: At the same time, 7.3 kg of NaOH was added to the water washing liquid and filtrate for stripping treatment, and after the reaction was carried out for 72 h at a temperature of 60 ℃, the treated water washing liquid and filtrate could be reused in the electrolytic manganese workshop.

[0088] Step S500: The ammonia gas emitted from the slurry tank was absorbed by 480 L of clean water and could be reused in the electrolytic manganese production system, and the ammonia gas collected during the treatment of the water washed residue, water washing liquid and filtrate was absorbed by 480 L of dilute sulfuric acid.

[0089] The concentration of manganese was detected by the method in "Determination of Manganese in Water by Potassium Periodate Spectrophotometry" GB11906-89; the content of manganese in the electrolytic manganese residue before treatment was measured as m1, the content of manganese after treatment of the manganese residue was measured as m2, and the solidification rate of manganese was (m1-m2) / m1x100%; the concentration of ammonia nitrogen was measured by the method in "Determination of Ammonia Nitrogen in Water by Nessler's Reagent Spectrophotometry" HJ535-2009; the content of ammonia nitrogen before treatment of the manganese residue was measured as h1, the content of ammonia nitrogen after treatment of the manganese residue was measured as h2, and the removal rate of ammonia nitrogen was (h1-h2) / h1x100%.

[0090] The results showed that the soluble manganese concentration in the leaching liquid of the treated water washed residue obtained in step S300 was 61.14 mg / L (i.e. m2) when the treated water washed residue was placed in storage, the solidification rate of manganese was 95.87%, the concentration of NH4 + -N was 80.95 mg / L (i.e. h2), and the removal rate of NH4 + -N was 88.11%.

[0091] Example 2

[0092] The method for harmless disposal of electrolytic manganese residue by dry-wet combined method in this embodiment comprises the following steps:

[0093] Step S100: 1 t of electrolytic manganese residue with a water content of 27% discharged from the filter press workshop (the content of manganese in the electrolytic manganese residue was 1481.22 mg / L, and the concentration of NH4 + -N was 680.99 mg / L) was transported to the slurry tank, then 5 t of water and 58.4 kg of quicklime were added to the slurry tank, and after the reaction was carried out for 72 h, the slurry was transported to the diaphragm filter press for solid-liquid separation under the conditions of pressure filtration for 16 min and pressure filtration temperature of 60 ℃, to obtain filter residue and filtrate.

[0094] Step S200: After adding 3.5 tons of water to the filter residue for water washing, the residue is transported to a diaphragm filter press for solid-liquid separation under the conditions of pressure filtration for 16 minutes and pressure filtration temperature of 60°C, to obtain water-washed residue with a water content of 27% and water-washed liquid.

[0095] Step S300: 10.95 kg of calcined raw material is added to the water-washed residue with a water content of 27% for reaction and 600 L / min of CO2 is introduced, and the reaction is carried out for 72 hours without additional heating.

[0096] Step S400: 10.95 kg of NaOH is added to the water-washed liquid and filtrate for stripping treatment, and after the reaction is carried out for 72 hours at a temperature of 60°C, the treated water-washed liquid and filtrate can be reused in the electrolytic manganese workshop.

[0097] Step S500: The ammonia gas overflowing from the slurry tank is absorbed by 480 L of clean water and can be reused in the electrolytic manganese production system, and the ammonia gas collected during the treatment of the water-washed residue, water-washed liquid and filtrate is absorbed by 480 L of dilute sulfuric acid.

[0098] Using the same detection method as in Example 1, the results show that the soluble manganese concentration in the leaching solution is 39.36 mg / L, and the solidification rate is 97.34%; the NH4 + -N concentration is 47.12 mg / L, and the removal rate is 93.08%.

[0099] Example 3

[0100] Step S100: 1 ton of electrolytic manganese residue with a water content of 27% (the manganese content of the electrolytic manganese residue is 1481.22 mg / L, and the NH4 + -N concentration is 680.99 mg / L) discharged from the pressure filtration workshop is transported to the slurry tank, then 5 tons of water and 73.0 kg of raw lime are added to the slurry tank, and after the reaction is carried out for 72 hours, the residue is transported to a diaphragm filter press for solid-liquid separation under the conditions of pressure filtration for 16 minutes and pressure filtration temperature of 60°C, to obtain filter residue and filtrate.

[0101] Step S200: After adding 3.5 tons of water to the filter residue for water washing, the residue is transported to a diaphragm filter press for solid-liquid separation under the conditions of pressure filtration for 16 minutes and pressure filtration temperature of 60°C, to obtain water-washed residue with a water content of 27% and water-washed liquid.

[0102] Step S300: 10.95 kg of calcined raw material is added to the water-washed residue with a water content of 27% for reaction and 600 L / min of CO2 is introduced, and the reaction is carried out for 72 hours without additional heating.

[0103] Step S400: 10.95 kg of NaOH is added to the water washing liquid and filtrate, and blow-off treatment is performed, after 72 h of reaction at a temperature of 60 DEG C, the treated water washing liquid and filtrate can be reused in the electrolytic manganese workshop.

[0104] Step S500: the ammonia gas overflowed from the slurry tank is absorbed by 480 L of clean water and can be reused in the electrolytic manganese production system, and the ammonia gas collected in the treatment process of the water washing residue, water washing liquid and filtrate is absorbed by 480 L of dilute sulfuric acid.

[0105] Using the same detection method as in Example 1, the results show that the soluble manganese concentration in the leaching liquid is 0.7 mg / L, and the solidification rate reaches 99.95%; the NH4 + The -N concentration is 8.1 mg / L, and the removal rate is 98.81%.

[0106] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited to this, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for dry-wet combined harmless disposal of electrolytic manganese residue, characterized in that, The method comprises the following steps: Step S100: electrolytic manganese residue discharged from a workshop is transported into a slurry tank together with water and alkaline material, and the electrolytic manganese residue is mixed with the water and the alkaline material under stirring to obtain filter residue and filter liquor; Step S200: water is added to the filter residue obtained in step S100, and the filter residue is washed with water to obtain washed residue and washed liquor; Step S300: alkaline material is added to the washed residue obtained in step S200, and CO2 generated by combustion of biomass fuel or CO2 discharged from the workshop is introduced into the washed residue, and the treated washed residue is stacked for disposal and / or resource utilization, wherein the pH value of the system after the addition of the alkaline material is 8-9, and the flow rate of the CO2 is 200-900 L / min per ton of electrolytic manganese residue; Step S400: alkaline material is added to the filter liquor obtained in step S100 and the washed liquor obtained in step S200, and stripping treatment is performed, and the treated filter liquor and washed liquor are transported to an electrolytic manganese workshop for reuse; Step S500: ammonia gas overflowed in steps S100, S300 and S400 is absorbed by an absorbent and reused.

2. The method for dry-wet combined harmless disposal of electrolytic manganese residue according to claim 1, characterized in that, In step S100, the electrolytic manganese residue is uniformly mixed with the water and the alkaline material under stirring, and then the reaction mixture is naturally placed for 0.5-72 h.

3. The method for dry-wet combined harmless disposal of electrolytic manganese residue according to claim 1, characterized in that, In step S100, the amount of water is 1-12 times the weight of the electrolytic manganese residue, and the alkaline material is quicklime and / or calcined raw material, and the amount of the alkaline material is 3-15% of the weight of the dry electrolytic manganese residue.

4. The method for dry-wet combined innocuous treatment of electrolytic manganese residue according to any one of claims 1 to 3, characterized in that, In step S100, the reaction mixture is pressure-filtered by a diaphragm filter, and the pressure-filtering time is 10-60 min, and the temperature of the reaction mixture during pressure-filtering is 20-70°C.

5. The method for dry-wet combined harmless disposal of electrolytic manganese residue according to claim 1, characterized in that, In step S200, the solid-liquid ratio of the filter residue to water is 1-5:10, and the washed material is pressure-filtered by a diaphragm filter, and the pressure-filtering time is 10-60 min, and the temperature of the reaction mixture during pressure-filtering is 20-70°C.

6. The method for dry-wet combined harmless disposal of electrolytic manganese residue according to claim 1, characterized in that, In step S300, the water content of the washed residue is 19-35%, the alkaline material is quicklime and / or calcined raw material, and the amount of the alkaline material is 1-5% of the weight of the dry electrolytic manganese residue.

7. The method for dry-wet combined harmless disposal of electrolytic manganese residue according to claim 1, characterized in that, In step S300, the reaction temperature of the washed residue, the alkaline material and CO2 is room temperature, and the reaction time is 2-72 h. 8.The method for dry-wet combined harmless disposal of electrolytic manganese residue according to claim 1, characterized in that, In step S400, the alkaline material is NaOH, and the amount of the alkaline material is 1-5% of the weight of the dry electrolytic manganese residue. 9.The method for dry-wet combined harmless disposal of electrolytic manganese residue according to claim 1, characterized in that, In step S400, the stripping treatment method is as follows: The filter liquor and the washed liquor are mixed with the alkaline material in a pipeline mixer to adjust the pH of the wastewater to 10-13 to obtain alkaline mixed wastewater; The obtained alkaline mixed wastewater is heated to 20-70°C, and then the heated wastewater is introduced into a stripping tower to contact mass transfer with air and fluidized granular packing, and the stripped wastewater is discharged from the bottom of the stripping tower, and the air containing free ammonia is discharged from the top end of the stripping tower, and the stripping treatment time is 2-72 h. 10.The method for dry-wet combined harmless disposal of electrolytic manganese residue according to claim 1, characterized in that, In step S100, the ammonia gas overflow is absorbed by water, and the amount of water is 1 t of electrolytic manganese residue: dry electrolytic manganese residue: water = 1.25:1-0.

6. The ammonia overflow in steps S300 and S400 is absorbed by sulfuric acid with a concentration of 0.2-0.5 mol / L, and the amount of sulfuric acid used is: for every 1 t of electrolytic manganese residue, the amount of sulfuric acid used is dry electrolytic manganese residue:sulfuric acid = 1.25:1-0.6; The absorption time of ammonia is 2-5 h.

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