A manganese residue field leachate resource treatment process
By treating the leachate from the manganese slag plantation through stepwise sedimentation and acidification, usable byproducts and directly usable nitrogen fertilizer water are formed. This solves the problems of difficult-to-obtain reagents and low byproduct utilization rate in existing technologies, and realizes the efficient resource utilization of the leachate from the manganese slag plantation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- XIUSHAN COUNTY XIUXING ECOLOGICAL ENVIRONMENT ENGINEERING CO LTD
- Filing Date
- 2024-12-25
- Publication Date
- 2026-07-28
AI Technical Summary
Existing methods for treating leachate from manganese slag plants suffer from problems such as the difficulty in obtaining reagents, the low manganese content of by-products making them difficult to utilize, and the need for further treatment of the treated wastewater.
By adding carbonate solution, inorganic alkali solution, carbonate solution, lime slurry and carbonate solution in steps, manganese carbonate, manganese dioxide, magnesium carbonate, gypsum and calcium magnesium carbonate are precipitated respectively. Then, sulfuric acid or nitric acid is added to the filtrate to obtain nitrogen fertilizer water, thus realizing the resource utilization treatment of leachate from manganese slag plantation.
This approach maximizes the resource utilization of leachate from the manganese slag plantation. Byproducts can be sold as industrial raw materials, and the wastewater can be used as fertilizer for greening the manganese slag plantation surface without further treatment, resulting in significant environmental benefits.
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Figure CN119898912B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of environmental protection technology, and in particular to a process for the resource-based treatment of leachate from manganese slag plants. Background Technology
[0002] Manganese resources are an important strategic mineral, widely used in steel production, non-ferrous metal alloys, aerospace, electronics, and new energy materials. Manganese slag dumps are the main sites for landfilling and disposing of manganese slag in the manganese industry, and are also one of the most significant sources of environmental pollution from the manganese industry. During landfilling, manganese slag continuously generates leachate containing high concentrations of manganese, ammonia nitrogen, and magnesium ions. If not collected and treated, this leachate will severely pollute the surrounding soil and water bodies.
[0003] Patent application CN 109851084 A discloses a resource-based treatment method for reducing the content of ammonia nitrogen, calcium, and magnesium ions in manganese-containing wastewater. The method includes: adjusting the pH value of manganese-containing wastewater at a temperature of 35℃-95℃ to 9.0-10.5 with lime; slowly adding Mn(H2PO4)2·2H2O to the manganese-containing wastewater under stirring conditions, and separating the solid and liquid to obtain struvite precipitate MgNH4PO4·6H2O and a first filtrate; adding MnSO4 to the first filtrate, stirring, and separating the solid and liquid to obtain a second filtrate; subjecting the second filtrate to adsorption and oscillation by adsorbents such as zeolite, maifanite, cinder, and vermiculite to obtain a third filtrate; and concentrating, crystallizing, washing, and drying the third filtrate to obtain manganese sulfate solid with low content of ammonia nitrogen, calcium, and magnesium ions. This method can obtain struvite precipitate MgNH4PO4·6H2O and manganese sulfate solid, and recover manganese and ammonia resources from wastewater. However, the Mn(H2PO4)2·2H2O reagent used is not easy to obtain, and the treated wastewater still needs further treatment.
[0004] Patent application CN 116332436 A discloses a method for treating manganese-containing wastewater. After pre-oxidation, a manganese removal agent is added to the wastewater, followed by a process of complexation reaction, neutralization reaction, flocculation reaction, and solid-liquid separation to remove manganese ions. This method involves numerous steps, a long process, and produces a large amount of slag, which has a low manganese content, making it unsuitable for reuse.
[0005] Patent application CN 107522324 A discloses a process for manganese recovery and comprehensive treatment of wastewater and exhaust gas from electrolytic manganese production wastewater. The process includes treating chromium-containing wastewater and polishing wastewater, manganese recovery, and sulfate treatment. The manganese recovery process involves first adding sodium hydroxide to the collected wastewater to adjust the pH to 7-8, then adding 1.5 times the chemical reaction volume of ammonium bicarbonate to precipitate Mn. 2+The process generates manganese carbonate, which is then precipitated and separated. The resulting manganese carbonate slag is reused in the production system, while the treated wastewater, meeting the water quality requirements for production, is also returned to the production system. However, this method suffers from several drawbacks. The use of ammonium bicarbonate increases the load on subsequent ammonia treatment of the wastewater. Furthermore, the precipitate is a mixture of manganese, magnesium, and calcium, and its reuse in the production system could disrupt the ecosystem's salt balance and affect the stability of the production system. In addition, for many abandoned manganese slag sites that have been shut down, the treated wastewater has no suitable production system and requires further treatment.
[0006] In summary, existing methods for treating leachate from manganese slag plants have several drawbacks, including the difficulty in obtaining reagents, the low manganese content of byproducts making them unusable, and the need for further treatment of the treated wastewater. Summary of the Invention
[0007] The inventors discovered that for manganese slag leachate, by adding carbonate solution, non-polar alkali solution, carbonate solution, lime slurry, and carbonate solution in steps, manganese carbonate, manganese dioxide, magnesium carbonate, gypsum, and calcium magnesium carbonate are precipitated respectively. Then, sulfuric acid or nitric acid is added to the filtrate to obtain nitrogen fertilizer water, which can be used as fertilizer water for greening the slag yard surface without discharge, thus maximizing the resource utilization of manganese slag leachate, thereby completing this invention.
[0008] The purpose of this invention is to provide a process for the resource utilization of leachate from manganese slag plantations, comprising the following steps: (1) Add sodium carbonate solution to the leachate from the manganese slag field at a constant rate while stirring until the pH of the reaction solution reaches 8.5-9.0. Filter and collect the manganese carbonate precipitate and the filtrate. (2) Add sodium hydroxide solution to filtrate one, control the pH of the solution to be stable at 8.7-9.0, aerate, filter, and obtain manganese dioxide precipitate and filtrate two; (3) Add sodium carbonate solution to filtrate II at once, wherein the amount of sodium carbonate is 1.0-1.2 times the chemical reaction equivalent of magnesium in the manganese slag leachate, and filter by sedimentation to collect magnesium carbonate precipitate and filtrate III; (4) Add lime slurry to the filtrate, wherein the amount of calcium is equal to the amount of SO4 in the leachate from the manganese slag field. 2- The chemical reaction equivalent is 0.9-1.0 times, filtered, to obtain gypsum precipitate and filtrate. (5) While stirring, slowly add sodium carbonate solution to filtrate four until the pH of the reaction solution is ≥11, filter, and obtain calcium magnesium carbonate and filtrate five; (6) Add sulfuric acid or nitric acid to the filtrate to adjust the pH to 6-9 to obtain nitrogen fertilizer water.
[0009] The leachate from the manganese slag plantation to be treated by this invention has a pH of 5-7, a manganese ion content of 800-1500 mg / L, a magnesium ion content of 400-800 mg / L, and an NH4+ content of...+ Content 600-1000 mg / L.
[0010] In a preferred embodiment, in step (1), the mass concentration of the sodium carbonate solution used is 10%-20%, more preferably about 10%, and the stirring rate is 15-30 r / min, more preferably about 15 r / min, so that the reaction proceeds uniformly and the reaction system solution is homogeneous.
[0011] In step (1), when the pH of the reaction system solution reaches 8.5-9.0, manganese carbonate can be effectively precipitated, the manganese concentration in the filtrate drops to below 50 mg / L, and calcium and magnesium ions do not precipitate, which facilitates full resource utilization.
[0012] At this point, filtration should be performed as soon as possible to separate the manganese carbonate precipitate from the filtrate. Studies have found that manganese ions precipitated in the form of manganese carbonate can account for more than 43% of the total manganese ions in the leachate from the manganese slag plantation. The obtained manganese carbonate can be sold as an industrial raw material, demonstrating a high degree of resource utilization.
[0013] In a preferred embodiment, in step (2), the pH of the solution is controlled to be stable at 8.7-9.0 by slowly adding sodium hydroxide solution and aeration is carried out for reaction. The reaction time is preferably 20-40 min, more preferably about 20 min. At this time, the manganese in the first filtrate precipitates out in the form of manganese dioxide, and the concentration of manganese ions in the second filtrate drops to below 5.0 mg / L, so that the manganese is fully precipitated further.
[0014] Studies have found that manganese ions precipitated in the form of manganese dioxide account for more than 39% of the total manganese ions in the leachate of manganese slag fields. Manganese dioxide can be sold as an industrial raw material, and its resource utilization rate is high.
[0015] In a preferred embodiment, in step (3), sodium carbonate with a magnesium ion stoichiometric ratio of 1.0-1.2 times is added, and the mixture is stirred to react fully, such as for 20-60 minutes, and allowed to settle fully, such as for 4-6 hours, so that magnesium carbonate is fully precipitated and manganese ions are further precipitated. At this time, the concentration of manganese ions in the filtrate is reduced to below 2.0 mg / L and the concentration of magnesium ions is reduced to below 20.0 mg / L.
[0016] Studies have found that the precipitated byproduct, which is in the form of magnesium carbonate, contains magnesium ions accounting for more than 25% of the total magnesium ions in the leachate from the manganese slag plantation. It also contains a very small amount of manganese carbonate. This magnesium carbonate byproduct can be sold as an industrial raw material, and its resource utilization rate is high.
[0017] In a preferred embodiment, in step (4), after adding lime milk, the reaction is continued to be stirred for at least 2 hours, such as 2-3 hours, so that the gypsum can be fully precipitated.
[0018] Studies have found that the gypsum obtained in step (4) has a CaSO4·2H2O content of over 90%, and can be sold directly as an industrial raw material.
[0019] In a preferred embodiment, in step (5), sodium carbonate is added to control the pH of the reaction solution to be ≥11, preferably about 11.5-12.0, so that calcium and magnesium in the solution can react and precipitate. Furthermore, in order to promote the full reaction of calcium and magnesium, stirring is continued for at least 4 hours, such as 4-6 hours.
[0020] The calcium magnesium carbonate obtained in step (5) is discharged as solid waste.
[0021] In a preferred embodiment, in step (6), the pH is adjusted to 6-9, preferably about 7, by adding dilute sulfuric acid or dilute nitric acid to obtain nitrogen fertilizer water.
[0022] The nitrogen fertilizer water is of good quality and can be directly used as wastewater for on-site greening of the manganese slag plant without discharge, thus maximizing resource utilization.
[0023] Furthermore, the process of the present invention also includes step (7) nitrogen fertilizer water irrigation: the nitrogen fertilizer water obtained in step (6) is used as fertilizer water for greening the surface of the manganese slag yard, with a single application amount of 480m³ / ha and an interval of 7 days between each application, and the greening plants grow well.
[0024] The present invention has the following advantages: (1) This invention recovers manganese ions, magnesium ions, and SO4 from the leachate of manganese slag plantation through a step-by-step treatment process. 2- This process generates usable / sellable byproducts, and the final wastewater is used as fertilizer for greening the manganese slag pond surface, maximizing the resource utilization of manganese slag pond leachate. (2) The treated tailwater of this invention can be used as fertilizer for greening the surface of manganese slag yard. The water quality is good and there is no need to rely on the production process for reuse or to carry out standard treatment. It has a wide range of applications. (3) The materials used in this invention are inexpensive and the process conditions are easy to control. Except for the calcium magnesium carbonate obtained in step (5), which is a solid waste, there are almost no other wastes, and the environmental protection effect is significant. Attached Figure Description
[0025] Figure 1 This invention illustrates a preferred embodiment of the process. Detailed Implementation
[0026] The present invention will now be described in further detail with reference to the accompanying drawings and preferred embodiments. Through these descriptions, the features and advantages of the present invention will become clearer and more apparent.
[0027] Example 1 (1) Take 100L of leachate from the manganese slag field and add a 10% sodium carbonate solution at a constant rate while stirring. The stirring rate is 15r / min. When the pH of the reaction solution is 8.5-8.7, stop adding sodium carbonate solution and immediately perform a filtration to obtain manganese carbonate by-product and filtrate one. The manganese concentration in filtrate one drops to 48 mg / L. (2) Add sodium hydroxide solution slowly to filtrate one, control the pH of the solution to be stable at 8.7-9.0, aerate for 20 minutes, and filter twice to obtain manganese dioxide byproduct and filtrate two. The manganese concentration in filtrate two is reduced to 5.0 mg / L. (3) Add sodium carbonate solution to filtrate II at once. The amount added is 1.0 times the chemical reaction equivalent of magnesium ions in the manganese slag leachate. Stir and react for 20 min. Transfer to the clarification tank and continue to settle for 4 h. Detect the concentration of manganese ions in the supernatant as 1.7 mg / L and the concentration of magnesium ions as 19 mg / L. Perform three filtrations to obtain magnesium carbonate byproduct and filtrate III. (4) Add lime slurry to the filtrate three, the amount added being equal to the amount of SO4 in the leachate from the manganese slag field. 2- The chemical reaction volume was 1.0 times, and the reaction was continued with stirring for 2 hours. After four filtrations, gypsum by-products and filtrate were obtained. (5) Slowly add sodium carbonate solution to filtrate four, stir the reaction, stop adding sodium carbonate solution when the pH of the reaction solution is 11.5, continue stirring the reaction for 4 hours, and filter five times to obtain calcium magnesium solid waste and filtrate five. (6) Add dilute sulfuric acid to the filtrate until the pH is 7 to obtain nitrogen fertilizer solution; (7) Use nitrogen fertilizer water for greening the surface of the slag yard. The single application amount is 480 m³ / ha, and the interval between each application is 7 days. If there is rain, the application will be postponed to prevent nitrogen fertilizer water from overflowing out of the slag yard and entering the river.
[0028] Example 2 (1) Take 100L of leachate from the manganese slag field and add a 20% mass concentration sodium carbonate solution to the leachate at a uniform rate while stirring. The stirring rate is 20r / min. When the pH of the reaction solution is 8.7-9.0, stop adding sodium carbonate solution and immediately perform a filtration to obtain manganese carbonate by-product and filtrate one. The manganese concentration in filtrate one drops to 44 mg / L. (2) Add sodium hydroxide solution slowly to filtrate one, control the pH of the solution to be stable at 8.7-9.0, aerate for 40 min, and filter twice to obtain manganese dioxide byproduct and filtrate two. The manganese concentration in filtrate two is reduced to 3.2 mg / L. (3) Add sodium carbonate solution to filtrate II at once. The amount added is 1.2 times the chemical reaction equivalent of magnesium ions in the manganese slag leachate. Stir and react for 60 min. Transfer to the clarifier and continue to settle for 6 h. Detect the concentration of manganese ions in the supernatant as 1.2 mg / L and the concentration of magnesium ions as 12 mg / L. Perform three filtrations to obtain magnesium carbonate byproduct and filtrate III. (4) Add lime slurry to the filtrate three, the amount added being equal to the amount of SO4 in the leachate from the manganese slag field. 2- The chemical reaction volume was 1.0 times, and the reaction was continued with stirring for 3 hours. After four filtrations, gypsum by-products and filtrate were obtained. (5) Slowly add sodium carbonate solution to filtrate four, stir the reaction, stop adding sodium carbonate solution when the pH of the reaction solution is 11.8, continue stirring the reaction for 6 hours, and filter five times to obtain calcium magnesium solid waste and filtrate five; (6) Add dilute nitric acid to the filtrate until the pH is 7 to obtain nitrogen fertilizer solution; (7) Use nitrogen fertilizer water for greening the surface of the slag yard. The single application amount is 440 m³ / ha, and the interval between each application is 7 days. If there is rain, the application will be postponed to prevent nitrogen fertilizer water from overflowing out of the slag yard and entering the river.
[0029] Example 3 (1) Take 100L of leachate from the manganese slag field and add a 15% sodium carbonate solution at a constant rate while stirring. The stirring rate is 30r / min. When the pH of the reaction solution is 8.8-9.0, stop adding sodium carbonate solution and immediately perform a filtration to obtain manganese carbonate by-product and filtrate one. The manganese concentration in filtrate one drops to 36mg / L. (2) Add sodium hydroxide solution slowly to filtrate one, control the pH of the solution to be stable at 8.7-9.0, aerate for 60 min, and filter twice to obtain manganese dioxide byproduct and filtrate two. The manganese concentration in filtrate two is reduced to 2.1 mg / L. (3) Add sodium carbonate solution to filtrate II at once. The amount added is 1.2 times the chemical reaction equivalent of magnesium ions in the manganese slag leachate. Stir for 60 min and transfer to the clarification tank for further sedimentation for 6 h. Detect the concentration of manganese ions in the supernatant as 1.6 mg / L and the concentration of magnesium ions as 14 mg / L. Perform three filtrations to obtain magnesium carbonate byproduct and filtrate III. (4) Add lime slurry to the filtrate three, the amount added being equal to the amount of SO4 in the leachate from the manganese slag field. 2- The chemical reaction volume was 0.9 times, and the reaction was continued with stirring for 3 hours. After four filtrations, gypsum by-products and filtrate were obtained. (5) Slowly add sodium carbonate solution to filtrate four, stir the reaction, stop adding sodium carbonate solution when the pH of the reaction solution is 12, continue stirring the reaction for 4 hours, and filter five times to obtain calcium magnesium solid waste and filtrate five. (6) Add dilute nitric acid to the filtrate until the pH is 7 to obtain nitrogen fertilizer solution; (7) Apply nitrogen fertilizer water to the greening of the slag yard surface. The single application amount is 520 m³ / ha, and the interval between each application is 7 days. If there is rain, the application will be postponed to prevent nitrogen fertilizer water from overflowing out of the slag yard and entering the river.
[0030] Test case The quality of the by-products obtained in Examples 1-3 was tested, and the results are shown in Table 1 below.
[0031] Table 1. By-product quality
[0032] Comparative Example 1 (1) Take 100L of leachate from the manganese slag field and add it at once to a 15% sodium carbonate solution with a mass concentration of 1.2 times the chemical reaction equivalent of manganese, magnesium and calcium ions in the leachate. Stir and react for 60 minutes. Filter to obtain manganese-magnesium by-product and filtrate one. The total manganese content in the manganese-magnesium by-product is 8%, the divalent manganese content is 4%, and the total magnesium content is 5% (the total manganese content is low, and the divalent manganese and total magnesium content are high, so it is not suitable for use). (2) The pH of the filtrate was adjusted to approximately 12 using dilute nitric acid (Mn). 2+ (For ammonia nitrogen concentrations ≤2.0 mg / L and total calcium and magnesium ion concentrations ≤50.0 mg / L), the nitrogen is treated by stripping to meet emission standards.
[0033] Comparative Example 2 (1) Take 100L of leachate from the manganese slag field and add it at once to a 15% sodium carbonate solution with a mass concentration of 1.0 times the chemical reaction equivalent of manganese ions in the leachate. Stir and react for 60 minutes. Filter to obtain manganese carbonate product (total manganese content 20%, divalent manganese content 14%, total magnesium content 4%) and filtrate one; (2) Add a 15% sodium carbonate solution with a mass concentration of 1.0 times the chemical reaction equivalent of magnesium ions in the manganese slag leachate to the first filtrate in one go, stir and react for 60 min, filter to obtain magnesium carbonate by-product and filtrate two. The total manganese content in the magnesium carbonate by-product is 6% and the total magnesium content is 9% (the total manganese content is low, and the divalent manganese and total magnesium content are high, so it is not suitable for use). (3) The pH of the filtrate was adjusted to 12 (Mn) using dilute nitric acid. 2+ (For ammonia nitrogen concentrations ≤2.0 mg / L and total calcium and magnesium ion concentrations ≤50.0 mg / L), the nitrogen is treated by stripping to meet emission standards.
[0034] The present invention has been described in detail above with reference to preferred embodiments and exemplary examples. However, it should be noted that these specific embodiments and examples are merely illustrative explanations of the present invention and do not constitute any limitation on the scope of protection of the present invention. Various improvements, equivalent substitutions, or modifications can be made to the technical content and implementation methods of the present invention without departing from the spirit and scope of protection of the present invention, and all such modifications fall within the scope of protection of the present invention. The scope of protection of the present invention is defined by the appended claims.
Claims
1. A process for the resource utilization of leachate from a manganese slag dump, comprising the stepwise addition of carbonate solution, inorganic alkali solution, carbonate solution, lime slurry, and carbonate solution to precipitate manganese carbonate, manganese dioxide, magnesium carbonate, gypsum, and calcium magnesium carbonate, respectively; and the subsequent addition of sulfuric acid or nitric acid to the filtrate to obtain nitrogen fertilizer water, which can be used for greening the slag dump surface without discharge. Includes the following steps: (1) Add sodium carbonate solution to the leachate from the manganese slag field at a constant rate while stirring until the pH of the reaction solution reaches 8.5-9.
0. Filter and collect the manganese carbonate precipitate and the filtrate. (2) Add sodium hydroxide solution to filtrate one, control the pH of the solution to be stable at 8.7-9.0, aerate, filter, and obtain manganese dioxide precipitate and filtrate two; (3) Add sodium carbonate solution to filtrate II at once, wherein the amount of sodium carbonate is 1.0-1.2 times the chemical reaction equivalent of magnesium in the manganese slag leachate, and filter by sedimentation to collect magnesium carbonate precipitate and filtrate III; (4) Add lime slurry to the filtrate, wherein the amount of calcium is equal to the amount of SO4 in the leachate from the manganese slag field. 2- The chemical reaction equivalent is 0.9-1.0 times, filtered, to obtain gypsum precipitate and filtrate. (5) While stirring, slowly add sodium carbonate solution to filtrate four until the pH of the reaction solution is ≥11, filter, and obtain calcium magnesium carbonate and filtrate five; (6) Add sulfuric acid or nitric acid to the filtrate to adjust the pH to 6-9, thus obtaining nitrogen fertilizer solution. In step (1), the sodium carbonate solution used has a mass concentration of 10%-20%, the stirring rate is 15-30 r / min, and the manganese concentration in the filtrate is reduced to below 50 mg / L. In step (2), the pH of the solution is controlled to be stable at 8.7-9.0 by slowly adding sodium hydroxide solution, and the reaction is carried out by aeration. The reaction time is 20-40 min, and the concentration of manganese ions in the second filtrate drops to below 5.0 mg / L.
2. The resource utilization process for leachate from manganese slag plantations as described in claim 1, wherein, In step (1), the sodium carbonate solution used has a mass concentration of 10% and a stirring rate of 15 r / min.
3. The resource utilization process for leachate from manganese slag plantations as described in claim 1, wherein, In step (2), the reaction time is 20 min.
4. The resource utilization process for leachate from manganese slag plantations as described in claim 1, wherein, In step (3), sodium carbonate with a stoichiometric ratio of 1.0-1.2 times that of magnesium ions is added, and the mixture is stirred to react fully and allow to settle completely, so that magnesium carbonate is fully precipitated.
5. The resource utilization process for leachate from manganese slag plantations as described in claim 4, wherein, In step (3), stir for 20-60 minutes to allow the mixture to fully react and allow it to settle for 4-6 hours.
6. The resource utilization process for leachate from manganese slag plantations as described in claim 1, wherein, In step (3), the concentration of manganese ions in the filtrate is reduced to below 2.0 mg / L and the concentration of magnesium ions is reduced to below 20.0 mg / L.
7. The resource utilization process for leachate from manganese slag plantations as described in claim 1, wherein, In step (4), after adding lime milk, continue stirring the reaction for at least 2 hours, and the content of CaSO4·2H2O in the resulting gypsum will reach more than 90%.
8. The resource utilization process for leachate from manganese slag plantations as described in claim 7, wherein, In step (4), continue stirring the reaction for 2-3 hours.
9. The resource utilization process for leachate from manganese slag plantations as described in claim 1, wherein, In step (5), sodium carbonate is added, the pH of the reaction solution is controlled to be ≥11, and stirring is continued for at least 4 hours.
10. The resource utilization process for leachate from manganese slag plantations as described in claim 9, wherein, In step (5), sodium carbonate is added, the pH of the reaction solution is controlled at 11.5-12.0, and stirring is continued for 4-6 hours.