An electrolytic manganese residue cyclic alkali washing harmless treatment system and method

Abstract

The present invention discloses an electrolytic manganese slag cyclic alkali washing harmless treatment system and method, which relates to the technical field of industrial solid waste disposal, and solves the problems of low lime utilization rate, high energy consumption, cumbersome operation and the need to adjust the pH value after treatment during the harmless treatment of electrolytic manganese slag. The system of the present invention includes an alkali washing stirring tank, a first filter press, a saturated lime water stirring barrel, a lime storage tank, a second filter press, a manganese slag air drying device and an ammonia absorption device; the method of the present invention includes the following steps: stirring alkali washing, solid-liquid separation, aeration alkalization, solid-liquid separation of the suspension, manganese slag air drying and ammonia absorption. The present invention realizes the harmlessness and reduction of the original electrolytic manganese slag and the backwashing filter press slag through cyclic alkali washing with saturated lime water by the electrolytic manganese slag cyclic alkali washing harmless treatment system. The process flow is simple, the operation method is simple, the operation cost is low, the treatment effect is good and the alkali liquid can be recycled, and the industrial application feasibility is relatively high.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial solid waste disposal, and particularly relates to an electrolytic manganese residue cyclic alkali washing harmless treatment system and method. Background Art

[0002] Electrolytic manganese residue is the filter residue produced by pressure filtration after the manganese ore powder is leached with sulfuric acid during the production of metallic manganese. In China, low-grade manganese carbonate is mainly used. For every 1t of electrolytic manganese produced, about 7-12t of wet residue is discharged, and a large amount of electrolytic manganese residue is generated every year. The wet residue contains 20%-35% of fresh liquid. With the continuous development of the electrolytic manganese industry in China, the continuously generated manganese residue poses a major challenge to the safe production of enterprises and environmental protection.

[0003] The water washing method is an important method for effectively recovering soluble manganese and ammonium sulfate in manganese residue. Using a filter press with a washing function for water washing is one of the main methods currently used in the industry. The solution after washing contains a relatively high concentration of manganese and ammonium sulfate and is returned to the electrolytic manganese production system for liquid preparation. Zhao Lvxuan et al. (2019) used a diaphragm filter press with a washing function and adopted the combined method of anolyte soaking and washing. After the soaking pulp ratio was 1:3 and the stirring time was 120 min, and then after water washing for 11 min, the concentrations of Mn and ammonium sulfate in the water tended to be stable, still being 1.6 g / L and 3.74 g / L respectively. Further treatment with sodium hydroxide solution was required to meet the requirements of Class I industrial solid waste for the manganese residue.

[0004] At present, for the alkali washing of manganese slag, inexpensive alkaline materials such as powdered quicklime and cement are mostly used for the harmless treatment of manganese slag. The powdered quicklime needs to react to form calcium hydroxide to stabilize manganese and stimulate the volatilization of ammonia nitrogen. In addition, hot air is needed to effectively stimulate the ammonia nitrogen in the manganese slag. It is found in the experiment that a large amount of unreacted lime often remains in the manganese slag, resulting in low utilization efficiency of lime; when the ammonia nitrogen is effectively treated, the pH value of the toxic leaching solution of the manganese slag exceeds 9, and the pH value needs to be adjusted back. The operation is cumbersome and the treatment cost is high. When adjusting the pH value of the manganese slag, it is easy to cause unstable adjustment due to the limitation of the mixing equipment. If the adjustment is too much, it will seriously affect the stability effect of manganese. At the same time, during the harmless treatment, the moisture content of the air-dried manganese slag has a great influence on the ammonia nitrogen content in its toxic leaching solution. When the air-dried moisture content of the manganese slag is too high, ammonia nitrogen is likely to remain in the manganese slag, and the ammonia nitrogen in its toxic leaching solution is likely to fail to meet the standard. The patent with the application number 202210231195.5 discloses a harmless treatment method and equipment for electrolytic manganese slag. The technical solution of this patent adopts a harmless treatment process of first washing with water, adding quicklime and water to the manganese slag after washing and stirring for reaction, and then adding dry fine sand for mixing treatment. The quicklime used is not prepared into saturated lime water but the solid powder is directly added to the manganese slag, and the addition amount is 4%-6% of the mass of the manganese slag. In the actual reaction, the pH value of the toxic leaching solution of the manganese slag after directly adding quicklime for treatment is above 11, and it is difficult to achieve the harmless (pH = 6-9) effect after adding fine sand for treatment. Moreover, there will still be unreacted quicklime remaining on the manganese slag in this scheme and it is not fully utilized.

[0005] Therefore, for the original electrolytic manganese slag and the backwashing filter press residue, it is of great significance to develop a harmless treatment system and method with low price, simple operation and recyclability for the clean production of electrolytic manganese. Summary of the Invention

[0006] In view of the above deficiencies, the present invention provides a cyclic alkali washing harmless treatment system and method for electrolytic manganese slag, which can solve the problems such as low utilization efficiency of lime, high energy consumption, cumbersome operation and the need to adjust the pH value after treatment during the harmless treatment of electrolytic manganese slag. The specific technical solutions are as follows:

[0007] A cyclic alkali washing harmless treatment system for electrolytic manganese slag, comprising:

[0008] An alkali washing stirring tank, a first filter press, a saturated lime water stirring barrel, a lime storage tank, a second filter press, a manganese slag air-drying device and an ammonia gas absorption device;

[0009] The alkali washing stirring tank is provided with an ammonia gas absorption port. The discharge port of the alkali washing stirring tank is connected to the feed port of the first filter press, and the ammonia gas absorption port of the alkali washing stirring tank is connected to the ammonia gas absorption device;

[0010] The filtrate outlet of the first filter press is connected to the liquid inlet of the saturated lime water stirring tank, and the filter residue of the first filter press is transported to the manganese slag air-drying device;

[0011] The saturated lime water stirring tank is provided with an aeration device and an ammonia absorption port. The feed inlet of the saturated lime water stirring tank is connected to the lime storage tank. The discharge outlet of the saturated lime water stirring tank is connected to the feed inlet of the second filter press, and the ammonia absorption port of the saturated lime water stirring tank is connected to the ammonia absorption device;

[0012] The filtrate outlet of the second filter press is connected to the liquid inlet of the alkali washing stirring tank, and the filter residue of the second filter press is transported to the saturated lime water stirring tank;

[0013] The manganese slag air-drying device is provided with an ammonia absorption port, and the ammonia absorption port of the manganese slag air-drying device is connected to the ammonia absorption device.

[0014] Preferably, both the alkali washing stirring tank and the saturated lime water stirring tank are equipped with stirring systems; both the first filter press and the second filter press are plate and frame filter presses.

[0015] Preferably, the ammonia absorption device is a negative pressure type ammonia absorption tower.

[0016] Preferably, the manganese slag air-drying device is a workshop, in which there is a blower and a manganese slag turning device. The air suction port of the blower is arranged on the side wall of the workshop. The manganese slag turning device is a crawler walking type turning machine. The top of the workshop is provided with an ammonia absorption port connected to the ammonia absorption device, and the air containing ammonia is sucked out through negative pressure. The manganese slag turning device turns back and forth to reduce the ammonia nitrogen and moisture in the slag.

[0017] Preferably, the aeration device consists of a plurality of disk microporous membrane aerators with a diameter of 215 mm and an air compressor, and the aeration device is arranged at the bottom of the saturated lime stirring tank.

[0018] An electrolytic manganese slag cyclic alkali washing and harmless treatment method, which is used in conjunction with the electrolytic manganese slag cyclic alkali washing and harmless treatment system described above, includes the following steps:

[0019] (1) Put electrolytic manganese slag and saturated lime water into the alkali washing stirring tank according to the wet weight mass ratio of 1:4 - 22 for alkali washing treatment, stir and react for 1 - 1.5 h to obtain a mixed slurry;

[0020] (2) Pump the mixed slurry onto the first filter press for pressure filtration. After the filter residue and the filtrate are separated, the filter residue is sent to the manganese slag air-drying device for air-drying to obtain deeply treated manganese slag;

[0021] (3) Pump the filtrate of the first filter press into the saturated lime water stirring tank, then add quicklime into the saturated lime water stirring tank, stir and aerate for reaction for 1 - 1.5 h to form saturated lime water in the solution. Pump the suspension containing lime to the second filter press for filtration to obtain the filtrate as saturated lime water and the filter residue as alkalized residue.

[0022] (4) Transport the filtrate of the second filter press to the alkali washing stirring tank in step (1) for continuous use; transport the alkalized residue to the saturated lime water stirring tank in step (3) for continuous use.

[0023] (5) Collect the ammonia gas generated during the reaction of the above alkali washing stirring tank, manganese slag air drying device and saturated lime water stirring tank with the ammonia nitrogen absorption device.

[0024] Preferably, the electrolytic manganese slag is the original electrolytic manganese slag or the backwashing filter residue.

[0025] Preferably, in step (1), the wet weight mass ratio of the backwashing filter residue to saturated lime water is 1:4 - 7.

[0026] Preferably, in step (2), the moisture content of the deeply treated manganese slag is lower than 9.5%.

[0027] Preferably, in step (3), the dosage of quicklime is 0 - 0.25% of the mass of the filtrate of the first filter press.

[0028] In step (3), the dosage of quicklime for the first alkali washing can be 0.25% of the mass of the filtrate of the first filter press; for the second, third, fourth, and fifth alkali washings, use the alkalized residue generated from the previous alkali washing to react in the saturated lime water stirring tank to prepare saturated lime water. At this time, the addition amount of quicklime can be 0; for the sixth and seventh alkali washings, use the alkalized residue generated from the previous alkali washing and the quicklime in the lime storage tank to react in the saturated lime water stirring tank to prepare saturated lime water. At this time, the addition amount of quicklime is very small, which are 0.05% and 0.025% of the mass of the filtrate of the first filter press respectively.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] 1. The present invention realizes the harmlessness and reduction of the original electrolytic manganese slag and the backwashing filter residue through a cyclic alkali washing and harmless treatment system for electrolytic manganese slag with saturated lime water circulation. The process flow is simple, the operation method is simple, the operation cost is low, the treatment effect is good, and the alkali solution can be recycled, and it has high feasibility in industrial application.

[0031] 2. The method of the present invention uses saturated lime water to render manganese slag harmless. Saturated lime water is formed by the full reaction of quicklime and water. Quicklime reacts with water to form ionic calcium hydroxide, which can directly react with water-soluble manganese and ammonium sulfate in the slag during stirring, that is, hydroxide reacts with water-soluble manganese in the slag to produce manganese hydroxide and reacts with ammonium sulfate to produce free ammonia. The aeration device of the saturated lime water stirring barrel and the manganese slag turning device in the manganese slag air drying device can promote the full escape of ammonia nitrogen, so that the reaction can proceed smoothly at room temperature without the need for additional hot air, thereby achieving low energy consumption.

[0032] 3. The pH value of saturated lime water in the reaction of the present invention is 12.25-12.75. After being fully stirred and reacted with manganese slag, the pH value is reduced to 9.1-9.5 (the pH value when ammonia nitrogen in manganese slag meets the standard). After being treated by a subsequent manganese slag air-drying device, the residual ammonia nitrogen in the slag continues to react with hydroxide to form free ammonia, which is converted into ammonia gas and volatilized, thereby further reducing the pH value of the manganese slag. The toxic leaching pH of the manganese slag after the final treatment is 8.1-8.6, and manganese and ammonia nitrogen all meet the standards. Therefore, after the continued reaction of the manganese slag air-drying device, the pH value of the manganese slag does not need to be adjusted, which effectively avoids the problem that the adjustment of the pH value of the manganese slag is unstable due to the limitation of the mixing equipment and the stability of manganese is affected by too much adjustment.

[0033] 4. The manganese slag air-drying device of the present invention air-dries the manganese slag to a moisture content of less than 9.5%, which is beneficial to the volatilization of ammonia and can make the ammonia nitrogen meet the standard.

[0034] 5. When preparing saturated lime water, the CaO in the quicklime is not completely reacted and remains in the alkalized slag. Therefore, the alkalized slag can be continuously put into the saturated lime water stirring barrel for the next cycle to prepare saturated lime water. The prepared saturated lime water is circulated for the alkali washing reaction in the alkali washing stirring tank, thereby effectively improving the utilization rate of lime and reducing the processing cost.

[0035] 6. The system of the present invention recovers the volatilized ammonia gas for the preparation of ammonia water and returns it to the production system. At the same time, the recycling of alkali solution can also treat the manganese slag to a better effect. The removal rate of ammonia nitrogen in the manganese slag can reach more than 99%, and the stability rate of manganese can reach more than 99%. The treated manganese slag meets the requirements of Class I general industrial solid waste in the "General Industrial Solid Waste Storage and Landfill Pollution Control Standards" (GB 18599-2020), and can achieve the effect of harmless and reduced manganese slag. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. In all drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn according to the actual scale.

[0037] Figure 1 It is a schematic structural diagram of the harmless treatment system for cyclic alkali washing of electrolytic manganese slag in the present invention;

[0038] Figure 2 It is a process flow chart of the method for harmless treatment of cyclic alkali washing of electrolytic manganese slag in the present invention.

[0039] Main reference numerals description:

[0040] 1 - Alkali washing stirring tank, 2 - First filter press, 3 - Saturated lime water stirring barrel, 4 - Lime storage tank, 5 - Second filter press, 6 - Manganese slag air drying device and 7 - Ammonia absorption device. Detailed implementation manners

[0041] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0042] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0043] In the description of the present invention, the meaning of "several" is one or more, the meaning of "multiple" is two or more, "greater than", "less than", "exceeding", etc. are understood as not including the present number, and "above", "below", "within", etc. are understood as including the present number. If terms such as "first", "second", "third" are described only for the purpose of description and distinguishing technical features, they cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence relationship of the indicated technical features.

[0044] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0045] Embodiment Example 1

[0046] As Figure 1 shown, an innocuous treatment system for cyclic alkali washing of electrolytic manganese slag includes: an alkali washing stirring tank 1, a first filter press 2, a saturated lime water stirring barrel 3, a lime storage tank 4, a second filter press 5, a manganese slag air drying device 6, and an ammonia absorption device 7. The alkali washing stirring tank 1 is connected to the first filter press 2; the first filter press 2 is respectively connected to the saturated lime water stirring barrel 3 and the manganese slag air drying device 6; the saturated lime water stirring barrel 3 is respectively connected to the lime storage tank 4 and the second filter press 2; the alkali washing stirring tank 1, the saturated lime water stirring barrel 3, and the manganese slag air drying device 6 are respectively connected to the ammonia absorption device 7; the second filter press 5 is connected to the alkali washing stirring tank 1.

[0047] The alkali washing stirring tank 1 is used for the alkali washing reaction of electrolytic manganese slag (the reaction of electrolytic manganese slag and saturated lime water). The first filter press 2 is used for the solid-liquid separation of the alkali washing reaction products (manganese slag and alkali washing liquid). The saturated lime water stirring barrel 3 is used for the aeration reaction to prepare saturated lime water. The lime storage tank 4 is used for storing quicklime and providing quicklime for the reaction in the saturated lime water stirring barrel 3. The second filter press 5 is used for the solid-liquid separation of the suspension (containing saturated lime water and alkalized slag) in the saturated lime water stirring barrel 3. The manganese slag air drying device 6 is used for air drying the filter residue (manganese slag) of the first filter press 2 and stimulating the escape of the remaining ammonia nitrogen in the manganese slag. The ammonia absorption device 7 is used for absorbing the ammonia gas generated by the reactions of the alkali washing stirring tank 1, the saturated lime water stirring barrel 3, and the manganese slag air drying device 6.

[0048] Specifically, the alkali washing stirring tank 1 is provided with an ammonia absorption port, the discharge port of the alkali washing stirring tank 1 is connected to the feed port of the first filter press 2, and the ammonia absorption port of the alkali washing stirring tank 1 is connected to the ammonia absorption device 7. Preferably, the alkali washing stirring tank 1 is equipped with a stirring system.

[0049] Specifically, the filtrate outlet of the first filter press 2 is connected to the liquid inlet of the saturated lime water stirring barrel 3, and the filter residue of the first filter press 2 is transported to the manganese slag air drying device 6.

[0050] Specifically, the saturated lime water stirring tank 3 is provided with an aeration device and an ammonia absorption port. The feed port of the saturated lime water stirring tank 3 is connected to the lime storage tank 4, the discharge port of the saturated lime water stirring tank 3 is connected to the feed port of the second filter press 5, and the ammonia absorption port of the saturated lime water stirring tank 3 is connected to the ammonia absorption device 7. Preferably, the saturated lime water stirring tank 3 is equipped with a stirring system. The aeration device consists of multiple disk microporous membrane aerators with a diameter of 215 mm and an air compressor, and the aeration device is arranged at the bottom of the saturated lime stirring tank 3. The aeration device is beneficial to the removal of ammonia nitrogen in the filtrate (alkali washing solution) of the first filter press 2 during the preparation of saturated lime water, reducing the ammonia nitrogen concentration in the circulating liquid and improving the circulating washing effect.

[0051] Specifically, the filtrate outlet of the second filter press 5 is connected to the liquid inlet of the alkali washing stirring tank 1, and the filter residue of the second filter press 5 is transported to the saturated lime water stirring tank 3; the filtrate separated by the second filter press 5 is saturated lime water, and the saturated lime water enters the alkali washing stirring tank 1 through the filtrate outlet of the second filter press 5 and the liquid inlet of the alkali washing stirring tank 1 to continue to be used for the alkali washing reaction of electrolytic manganese slag. The filter residue of the second filter press 5, the alkali slag (containing unreacted CaO), is transported to the saturated lime water stirring tank 3 to continue to be recycled for the preparation of saturated lime water. After adding quicklime once to the saturated lime water stirring tank 3 from the lime storage tank 4, the saturated lime water can be recycled and prepared separately with the alkali slag 4 - 5 times without adding quicklime additionally, and it can also meet the requirements of the alkali washing reaction, making the quicklime in the lime storage tank 4 be utilized efficiently. Preferably, both the first filter press 2 and the second filter press 5 are plate and frame filter presses.

[0052] Specifically, the manganese slag air drying device 6 is provided with an ammonia absorption port, and the ammonia absorption port of the manganese slag air drying device 6 is connected to the ammonia absorption device 7. The manganese slag air drying device 6 is a workshop, and a blower and a manganese slag turning device are arranged in the workshop. The air suction port of the blower is arranged on the side of the workshop, and an ammonia absorption port connected to the ammonia absorption device 7 is arranged at the top of the workshop, and the air containing ammonia is sucked out through negative pressure; the manganese slag turning device is a crawler - type turning machine, which turns back and forth. During the turning process, the residual ammonia nitrogen in the manganese slag continues to react with hydroxide ions to form free ammonia, which volatilizes as ammonia gas, thereby reducing the ammonia nitrogen content and pH value of the manganese slag. After final treatment, the pH value of the toxic leaching of the manganese slag meets the standard, and it is not necessary to readjust the pH value of the manganese slag again, effectively avoiding the problems of unstable readjustment and excessive readjustment affecting the stability of manganese caused by the limitation of the mixing equipment when readjusting the pH value of the manganese slag. At the same time, the blower and the manganese slag turning device also overcome the problem that conventional methods need to be supplemented with hot air to stimulate the volatilization of ammonia nitrogen in the manganese slag, and can stimulate the volatilization of ammonia gas at normal temperature, achieving low energy consumption.

[0053] The ammonia absorption device 7 is a negative-pressure ammonia absorption tower, using water as the absorbent to absorb and form ammonia water.

[0054] Example 2

[0055] Take the fresh electrolytic manganese slag from a certain factory, and conduct toxicity leaching according to the "Solid Waste - Leaching Toxicity Leaching Method - Horizontal Oscillation Method" (HJ557—2010). The manganese in the leachate is 1004.18 mg / L, ammonia nitrogen is 1311.74 mg / L, and pH = 7.18. Alkaline wash the above manganese slag according to the mass ratio of wet weight to saturated lime water = 1:22, stir and react for 1.5 h, filter it on the first filter press, add quicklime and alkalized slag with a mass of 0.25% of the filtrate quality to the filtrate, stir and aerate and react for 1.5 h; pump the lime-containing suspension to the second filter press for filtration, obtain saturated lime water and return it to the alkaline wash of electrolytic manganese slag, and the alkalized slag after filtration is returned to continue to be used for preparing saturated lime water; air-dry the filter residue of the first filter press, and the moisture content of the manganese slag after air-drying is 9.5%; collect the overflowing ammonia gas during the treatment process. After treatment, the mass of the manganese slag is reduced by 7% (based on dry basis); conduct toxicity leaching on the treated manganese slag according to HJ557—2010. The manganese in the leachate is 0.23 mg / L, ammonia nitrogen is 7.10 mg / L, and pH = 8.37, meeting the requirements of the first type of general industrial solid waste in the "General Industrial Solid Waste Storage and Landfill Pollution Control Standard" (GB 18599-2020).

[0056] Example 3

[0057] Take the fresh electrolytic manganese backwashing filter residue 1# from a certain factory, and conduct toxicity leaching according to the "Solid Waste - Leaching Toxicity Leaching Method - Horizontal Oscillation Method" (HJ557—2010). The manganese in the leachate is 261.42 mg / L, ammonia nitrogen is 495.25 mg / L, and pH = 7.37. Alkaline wash the above manganese slag according to the mass ratio of wet weight to saturated lime water = 1:7, stir and react for 1 h, filter it on the first filter press, add quicklime and alkalized slag with a mass of 0.05% of the filtrate quality to the filtrate, stir and aerate and react for 1.5 h; pump the lime-containing suspension to the second filter press for filtration, obtain saturated lime water and return it to the alkaline wash of electrolytic manganese slag, and the alkalized slag after filtration is returned to continue to be used for preparing saturated lime water; air-dry the filter residue of the first filter press, and the moisture content of the manganese slag after air-drying is 6.48%; collect the overflowing ammonia gas during the treatment process. After treatment, the mass of the manganese slag is reduced by 3% (based on dry basis); conduct toxicity leaching on the treated manganese slag according to HJ557—2010. The manganese in the leachate is 1.85 mg / L, ammonia nitrogen is 7.94 mg / L, and pH = 8.07, meeting the requirements of the first type of general industrial solid waste in the "General Industrial Solid Waste Storage and Landfill Pollution Control Standard" (GB 18599-2020).

[0058] Example 4 of implementation

[0059] Take the fresh electrolytic manganese backwashing and pressure-filtering residue 2# from a certain factory, and conduct toxicity leaching according to the "Solid Waste - Leaching Toxicity Leaching Method - Horizontal Oscillation Method" (HJ557—2010). The manganese in the leachate is 137.93 mg / L, ammonia nitrogen is 76.32 mg / L, and pH = 7.20. Alkaline wash the above manganese residue according to the mass ratio of wet weight to saturated lime water = 1:4, stir and react for 1 h, filter on the first filter press, add alkalized slag to the filtrate, stir and aerate and react for 1 h; pump the lime-containing suspension to the second filter press for pressure filtration, obtain saturated lime water and return it to the alkaline washing of electrolytic manganese slag, and the pressure-filtered alkalized slag is returned and continued to be used for the preparation of saturated lime water; air-dry the filter residue of the first filter press, and the moisture content of the air-dried manganese slag is 7.76%; collect the overflowing ammonia gas during the treatment process. After treatment, the mass of the manganese slag is reduced by 2% (based on dry basis); conduct toxicity leaching on the treated manganese slag according to HJ557—2010, the manganese in the leachate is 0.68 mg / L, ammonia nitrogen is 5.00 mg / L, and pH = 8.31, meeting the requirements of Class I general industrial solid waste in the "General Industrial Solid Waste Storage and Landfill Pollution Control Standard" (GB 18599-2020).

[0060] Comparative Example 1

[0061] Compared with Example 3 of implementation, the moisture content of the electrolytic manganese air-dried manganese slag in Comparative Example 1 is 20.75%. Specifically, take the fresh electrolytic manganese backwashing and pressure-filtering residue 1# from a certain factory, and conduct toxicity leaching according to the "Solid Waste - Leaching Toxicity Leaching Method - Horizontal Oscillation Method" (HJ557—2010). The manganese in the leachate is 261.42 mg / L, ammonia nitrogen is 495.25 mg / L, and pH = 7.37. Alkaline wash the above manganese residue according to the mass ratio of wet weight to saturated lime water = 1:7, stir and react for 1 h, filter on the first filter press, add quicklime and alkalized slag with a mass of 0.05% of the filtrate mass to the filtrate, stir and aerate and react for 1.5 h; pump the lime-containing suspension to the second filter press for pressure filtration, obtain saturated lime water and return it to the alkaline washing of electrolytic manganese slag, and the pressure-filtered alkalized slag is returned and continued to be used for the preparation of saturated lime water; air-dry the filter residue of the first filter press, and the moisture content of the air-dried manganese slag is 20.75%; collect the overflowing ammonia gas during the treatment process. After treatment, the mass of the manganese slag is reduced by 3% (based on dry basis); conduct toxicity leaching on the treated manganese slag according to HJ557—2010, the manganese in the leachate is 1.95 mg / L, ammonia nitrogen is 16.85 mg / L (>15mg / L), and pH = 8.03, not meeting the requirements of Class I general industrial solid waste in the "General Industrial Solid Waste Storage and Landfill Pollution Control Standard" (GB 18599-2020).

[0062] Comparative Example 2

[0063] Compared with Example 4, in Comparative Example 2, the solid-liquid ratio of electrolytic manganese slag to saturated lime water during alkali washing was 1:3. Specifically, take the fresh electrolytic manganese backwashing filter press slag 2# from a certain factory, and conduct toxicity leaching according to "Solid Waste - Extraction Procedure for Toxicity Characteristics - Horizontal Vibration Method" (HJ557—2010). The manganese in the leachate was 137.93 mg / L, ammonia nitrogen was 76.32 mg / L, and pH = 7.20. The above manganese slag was alkali-washed with saturated lime water at a mass ratio of wet weight to saturated lime water of 1:3, stirred and reacted for 1 h, filtered on the first filter press, and then alkalized slag was added to the filtrate, stirred and aerated for 1 h; the lime-containing suspension was pumped to the second filter press for filtration, and after obtaining saturated lime water, it was returned to the alkali washing of electrolytic manganese slag, and the filtered alkalized slag was returned and continued to be used for the preparation of saturated lime water; the filter residue of the first filter press was air-dried, and the moisture content of the air-dried manganese slag was 7.87%; ammonia gas overflowing during the treatment process was collected. After treatment, the mass of the manganese slag decreased by 1% (dry basis); according to HJ557—2010, the treated manganese slag was subjected to toxicity leaching. The manganese in the leachate was 3.18 mg / L (>2 mg / L), ammonia nitrogen was 8.48 mg / L, and pH = 7.96, which did not meet the requirements of Class I general industrial solid waste in the "Pollution Control Standard for Storage and Landfill of General Industrial Solid Wastes" (GB 18599-2020).

[0064] Table 1 Toxicity leaching of manganese slag before and after treatment in the cases

[0065]

[0066] As can be seen from Table 1, after being treated by the system and method of the present invention, the stabilization rate of manganese was 99.29% - 99.98%, the ammonia nitrogen removal rate was 93.45% - 99.46%, the dry basis of the manganese slag decreased by 2% - 7%, and in the toxicity leaching solution of the manganese slag, manganese < 2 mg / L, ammonia nitrogen < 15 mg / L, and pH = 6 - 9, meeting the requirements of Class I general industrial solid waste in the "Pollution Control Standard for Storage and Landfill of General Industrial Solid Wastes" (GB 18599-2020), and achieving the effects of harmlessness and reduction of manganese slag; and as can be seen from Table 2, the alkali-washed slag after 7 cycles all met the requirements of Class I solid waste. When the moisture content of the manganese slag was relatively high after air-drying and the air-drying time was insufficient and the ammonia nitrogen escape was insufficient, the ammonia nitrogen in the toxicity leaching solution did not meet the standard; when reducing the proportion of the alkali-washing solution of saturated lime water, the provided hydroxide was insufficient and the stabilization rate of manganese in the slag was relatively low, resulting in the non-compliance of manganese in the toxicity leaching solution of the manganese slag.

[0067] The electrolytic manganese backwashing filter press residue 1# was subjected to cyclic alkali washing according to Example 3. Each time, 300 kg of manganese residue with a water content of 31.73% was taken, and alkali washing was carried out according to the mass ratio of wet weight to saturated lime water = 1:7. Samples were taken after 7 cycles of alkali washing. The Mn content in the toxic leachate was 0.50 - 1.71 mg / L, the ammonia nitrogen content was 7.25 - 12.75 mg / L, and the pH value was 8.13 - 8.40. The alkali washing residues after 7 cycles all met the requirements of Class I solid waste, as shown in Table 2 specifically. The recycling effect of the quicklime alkalized residue during 7 cycles of alkali washing is shown in Table 3.

[0068] Table 2 Toxic leaching situation of manganese residue after 7 cycles of alkali washing in Example 3

[0069]

[0070] Table 3 Recycling effect of quicklime alkalized residue during 7 cycles of alkali washing in Example 3

[0071]

[0072] As can be seen from Table 3, after 7 consecutive cycles of alkali washing, the alkalized residue can be reused, and only a small amount of quicklime needs to be supplemented to recycle and prepare saturated lime water for alkali washing manganese residue. Calculation shows that after 7 cycles of alkali washing, a total of 2100 kg of wet electrolytic manganese residue with a water content of 31.73% was treated. Then the total amount of quicklime accounted for 0.33% of the wet weight of the manganese residue or 0.48% of the dry weight of the manganese residue, which is much less than the mass of lime used for the harmless treatment of electrolytic manganese residue after water washing with solid quicklime directly (4% - 6%, from the invention patent 202210231195.5, a method and equipment for the harmless treatment of electrolytic manganese residue).

[0073] As mentioned above, the above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A method for harmless treatment of electrolytic manganese residue by cyclic alkali washing, characterized in that, The method uses an electrolytic manganese slag circulating alkali washing harmless treatment system to treat the electrolytic manganese slag. The electrolytic manganese slag circulating alkali washing harmless treatment system comprises: Alkali washing mixing tank, first filter press, saturated lime water mixing barrel, lime storage tank, second filter press, manganese slag air drying device and ammonia absorption device; The alkali washing stirring tank is provided with an ammonia absorption port, the discharge port of the alkali washing stirring tank is connected to the feed port of the first filter press, and the ammonia absorption port of the alkali washing stirring tank is connected to the ammonia absorption device; The filtrate outlet of the first filter press is connected to the liquid inlet of the saturated lime water mixing barrel, and the filter residue of the first filter press is transported to the manganese residue air drying device; The saturated lime water mixing barrel is provided with an aeration device and an ammonia absorption port, the feed port of the saturated lime water mixing barrel is connected to the lime storage tank, the discharge port of the saturated lime water mixing barrel is connected to the feed port of the second filter press, and the ammonia absorption port of the saturated lime water mixing barrel is connected to the ammonia absorption device; The filtrate outlet of the second filter press is connected to the liquid inlet of the alkali washing stirring tank, and the filter residue of the second filter press is transported to the saturated lime water stirring barrel; The manganese slag air drying device is provided with an ammonia absorption port, and the ammonia absorption port of the manganese slag air drying device is connected to the ammonia absorption device; The harmless treatment method comprises the following steps: (1) placing electrolytic manganese slag and saturated lime water in the alkali washing stirring tank at a wet weight ratio of 1:4-22 for alkali washing, stirring for 1-1.5 hours to obtain a mixed slag slurry; (2) pumping the mixed slurry to the first filter press for filtering, and after the filter residue and the filtrate are separated, sending the filter residue to the manganese residue air drying device for air drying to obtain a deeply treated manganese residue; (3) The filtrate from the first filter press is pumped into the saturated lime water mixing barrel, quicklime is added into the saturated lime water mixing barrel, and the mixture is stirred and aerated for 1-1.5 hours to form saturated lime water, and the suspension containing lime is pumped into the second filter press for filter pressing, so that the filtrate is saturated lime water and the filter residue is alkalized residue; (4) conveying the filtrate from the second filter press to the alkali washing stirring tank in step (1) for continued use; conveying the alkalized slag to the saturated lime water stirring tank in step (3) for continued use; (5) The ammonia gas generated during the reaction of the above-mentioned alkali washing stirring tank, manganese slag air drying device and saturated lime water stirring barrel is collected by the ammonia gas absorption device.

2. The method for harmless treatment of electrolytic manganese residue by cyclic alkali washing according to claim 1, characterized in that, The alkaline washing stirring tank and the saturated lime water stirring barrel are both provided with stirring systems; the first filter press and the second filter press are both plate and frame filter presses.

3. The method for harmless treatment of electrolytic manganese residue by cyclic alkali washing according to claim 1, characterized in that, The ammonia absorption device is a negative pressure ammonia absorption tower.

4. The method for harmless treatment of electrolytic manganese residue by cyclic alkali washing according to claim 1, characterized in that, The manganese slag air-drying device is a workshop, which is equipped with a blower and a manganese slag turning device. The exhaust port of the blower is arranged on the side wall of the workshop. The manganese slag turning device is a crawler-type turning machine. The top of the workshop is provided with an ammonia absorption port connected to the ammonia absorption device.

5. The method for harmless treatment of electrolytic manganese residue by cyclic alkali washing according to claim 1, characterized in that, The aeration device is composed of a plurality of disc-type microporous membrane aerators with a diameter of 215 mm and an air compressor, and the aeration device is arranged at the bottom of the saturated lime water mixing barrel.

6. The method for harmless treatment of electrolytic manganese residue by cyclic alkali washing according to claim 1, characterized in that, The electrolytic manganese residue is the original electrolytic manganese residue or the backwashing pressure filtration residue.

7. The method for harmless treatment of electrolytic manganese residue by cyclic alkali washing according to claim 1, characterized in that, In step (1), the wet weight mass ratio of the electrolytic manganese residue to saturated lime water is 1:4 - 7.

8. The method for harmless treatment of electrolytic manganese residue by cyclic alkali washing according to claim 1, characterized in that, In step (2), the moisture content of the deeply treated manganese residue is lower than 9.5%.

9. The method for harmless treatment of electrolytic manganese residue by cyclic alkali washing according to claim 1, characterized in that, In step (3), the dosage of quicklime is 0 - 0.25% of the mass of the filtrate of the first pressure filter.

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