A harmless treatment process for electrolytic manganese residue and ammonia recovery

Abstract

The present invention relates to the field of resource utilization of electrolytic manganese slag, and specifically relates to a process for harmless treatment of electrolytic manganese slag and ammonia recovery. The present invention adopts a multi-stage slurrying reaction and a liquid-solid reaction, and the process water is circulated countercurrently, with uniform and stable treatment effects. The pH value, manganese, and ammonia nitrogen of the leachate of the treated manganese slag can stably meet the requirements of Class I of general industrial solid wastes. Moreover, the process of the present invention is simple, with less water consumption and low cost. The treatment cost per ton of manganese slag is ≤ 80 yuan, and no wastewater is generated.

Description

Technical Field

[0001] The present invention relates to the field of resource utilization of electrolytic manganese slag, and particularly to a process for harmless treatment of electrolytic manganese slag and ammonia recovery. Background Art

[0002] Electrolytic manganese slag is a nearly neutral waste residue generated after the processes of acid leaching, neutralization, and pressure filtration of manganese carbonate ore. It contains a large amount of combined leaching liquid, which is 20% - 30% by water content, and has complex chemical components. Among them, ionic manganese (Mn 2+ ) and ammonia nitrogen (NH4 + ) are the main pollutants, and it also contains trace amounts of heavy metal ions such as As, Cr, Se, and Cd. At present, most electrolytic manganese slags are treated by direct stacking. The long-term stacked electrolytic manganese slag not only occupies land resources, but is also extremely likely to generate a large amount of leachate during the rainy season. The leachate enters the surrounding soil and groundwater, causing serious environmental pollution.

[0003] Through the pyrometallurgical process of roasting, sulfur and ammonia resources in the manganese slag can be recovered, and the roasted manganese slag can be used to produce building materials such as cement; in the dry process, by directly mixing and stirring the manganese slag with lime, ammonium sulfate in the manganese slag can be converted into ammonia gas, and at the same time, hot air is introduced to volatilize ammonia from the manganese slag. However, both of the above two methods have deficiencies in the harmless treatment and resource utilization of manganese slag. Among them, although the pyrometallurgical process has a good recovery effect on sulfur and ammonia, it has high energy consumption and large investment, and the roasted manganese slag is prone to exceed the pH standard of the manganese slag leaching solution due to the "calcium corrosion effect"; in the dry process, due to the solid-solid reaction, the stability and uniformity of the harmless treatment of manganese slag are poor, and the pH and ammonia nitrogen of the leaching solution of the treated manganese slag are difficult to stably meet the requirements of Class I general industrial solid waste, and the consumption of reagents is large. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defects in the harmless treatment and resource utilization of existing electrolytic manganese slag, such as high treatment energy consumption, large reagent consumption, and the difficulty in stably meeting the requirements of Class I general industrial solid waste for the pH and ammonia nitrogen of the leaching solution of the treated manganese slag, so as to provide a process for harmless treatment of electrolytic manganese slag and ammonia recovery to solve the above problems.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A process for harmless treatment of electrolytic manganese slag and ammonia recovery, comprising the following steps:

[0007] 1) Add pulping liquid A to electrolytic manganese residue for primary pulping to obtain electrolytic manganese residue slurry, then adjust the pH value of the electrolytic manganese residue slurry to 9.5 - 13 and the NH₃-N content to no more than 1.5 g / L, and then perform solid-liquid separation to obtain primary manganese residue and primary filtrate. The ammonia gas generated by adjusting pH after primary pulping is prepared into ammonia water by water absorption process;

[0008] 2) Add pulping liquid B to the primary manganese residue for secondary pulping, then adjust the pH value of the electrolytic manganese residue slurry to 9.0 - 10.0 and the NH₃-N content to no more than 0.3 g / L, and then perform solid-liquid separation to obtain secondary manganese residue and secondary filtrate;

[0009] 3) Add pulping liquid C to the secondary manganese residue for tertiary pulping, and then perform solid-liquid separation to obtain harmless manganese residue and tertiary filtrate;

[0010] The first pulping liquid A is water, and the subsequent is secondary filtrate;

[0011] The first pulping liquid B is water, and the subsequent is tertiary filtrate;

[0012] The pulping liquid C is the solution obtained by adding acid to adjust the pH value to 8 - 10 after the primary filtrate passes through the wastewater deammoniation process.

[0013] Preferably, the pH value of the electrolytic manganese residue slurry after primary pulping is adjusted by treatment agent A; the treatment agent A is selected from at least one of calcium oxide, calcium hydroxide, and sodium hydroxide, and preferably calcium oxide;

[0014] And / or, the pH value of the electrolytic manganese residue slurry after secondary pulping is adjusted by treatment agent B; the treatment agent B is selected from at least one of calcium oxide, calcium hydroxide, sodium hydroxide, and sulfuric acid;

[0015] The pH value of the pulping liquid C is adjusted by sulfuric acid.

[0016] Preferably, the dosages of the pulping liquid A, the pulping liquid B, and the pulping liquid C are all 6 - 10 times the water content of the manganese residue.

[0017] Preferably, the electrolytic manganese residue is also subjected to crushing treatment before primary pulping.

[0018] Preferably, stirring treatment is carried out during the processes of primary pulping, secondary pulping, and tertiary pulping.

[0019] Preferably, the stirring time of primary pulping ≥ 90 min;

[0020] And / or, the stirring time of secondary pulping and tertiary pulping ≥ 60 min.

[0021] Preferably, the wastewater deammoniation process uses a membrane deammoniation method, and the specific process is as follows: sodium carbonate is added to the primary filtrate for precipitation, followed by microfiltration, ultrafiltration, and deammoniation membrane treatment.

[0022] Preferably, the wastewater deammoniation process uses a stripping method, and the specific process is as follows: sodium carbonate is added to the primary filtrate for precipitation, followed by filtration and stripping treatment.

[0023] Preferably, ammonium sulfate is prepared by using sulfuric acid as the absorption acid in the deammoniation membrane treatment or stripping treatment.

[0024] Preferably, the ammonium sulfate is recycled to the primary pulping.

[0025] In the present invention, the ammonia gas generated by adjusting the pH after the primary pulping is sent into the water absorption system under negative pressure to produce ammonia water products.

[0026] In the present invention, the primary pulping, secondary pulping, and tertiary pulping are all carried out in a pulping reactor.

[0027] The technical solution of the present invention has the following advantages:

[0028] 1. An electrolytic manganese residue harmless treatment and ammonia recovery process, comprising the following steps: 1) adding pulping liquid A to the electrolytic manganese residue for primary pulping to obtain an electrolytic manganese residue pulp, then adjusting the pH value of the electrolytic manganese residue pulp to 9.5 - 13 and the NH3-N content not exceeding 1.5 g / L, and then performing solid-liquid separation to obtain primary manganese residue and primary filtrate. The ammonia gas generated by adjusting the pH after the primary pulping is prepared into ammonia water by using a water absorption process; 2) adding pulping liquid B to the primary manganese residue for secondary pulping, then adjusting the pH value of the electrolytic manganese residue pulp to 9.0 - 10.0 and the NH3-N content not exceeding 0.3 g / L, and then performing solid-liquid separation to obtain secondary manganese residue and secondary filtrate; 3) adding pulping liquid C to the secondary manganese residue for tertiary pulping, and then performing solid-liquid separation to obtain harmless manganese residue and tertiary filtrate; the first pulping liquid A is water, and the subsequent is the secondary filtrate; the first pulping liquid B is water, and the subsequent is the tertiary filtrate; the pulping liquid C is a solution obtained by adding acid to the primary filtrate after the wastewater deammoniation process and adjusting the pH value to 8 - 10. The present invention adopts a multi-stage pulping reaction and a liquid-solid reaction, and the treatment effect is uniform and stable. The pH, manganese, and ammonia nitrogen of the leachate of the treated manganese residue can stably meet the requirements of Class I general industrial solid waste. Moreover, the process of the present invention is simple, with less water consumption and low cost. The treatment cost per ton of manganese residue is ≤ 80 yuan, and no wastewater is generated;

[0029] In addition, the present invention does not require drying and roasting of the manganese residue, the process water is recycled countercurrently, the treatment energy consumption is low, the dosage of chemicals is small, and there is no secondary pollution.

[0030] 2. In the process of the present invention, the conversion rate of ammonium sulfate in the manganese residue to ammonia water is ≥ 97%, and the recovery is sufficient. Brief Description of the Drawings

[0031] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0032] Figure 1 It is the process flow diagram of Embodiments 1-3 of the present invention. Detailed Description of the Embodiments

[0033] The following embodiments are provided to better understand the present invention further. It is not limited to the best embodiment described, and does not limit the content and protection scope of the present invention. Any product obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior art features and being the same as or similar to the present invention falls within the protection scope of the present invention.

[0034] For those embodiments where specific experimental steps or conditions are not indicated, the operations or conditions of the conventional experimental steps described in the literature in this field can be followed. For the reagents or instruments whose manufacturers are not indicated, they are all conventional reagent products that can be obtained through commercial purchase.

[0035] Embodiment 1

[0036] This embodiment provides a harmless treatment process for electrolytic manganese slag and ammonia recovery process. The process flow is as Figure 1 shown, and specifically includes the following steps:

[0037] 1) Crush the fresh manganese slag. After detection, its water content is 25%;

[0038] 2) Feed the crushed manganese slag into the first-stage pulping reactor, and add pulping liquid A with a dosage 6 times the water content of the manganese slag. That is, when the manganese slag content is 100 kg, the dosage of pulping liquid A is 100×25%×6 = 150 kg. For the first treatment, use clear water as pulping liquid A, and use the secondary filtrate as pulping liquid A subsequently. Then stir for 90 min for the first-stage pulping, and add calcium oxide to adjust the pH of the electrolytic manganese slag slurry to 13, with the NH3-N content being 0.7 g / L. The ammonia gas generated from adjusting the pH is sent into the water absorption system under negative pressure to produce ammonia products, and the mass content of ammonia in the ammonia products is 10%. After the first-stage pulping reaction ends, perform solid-liquid separation to obtain the first-stage manganese slag and the first-stage filtrate, and the first-stage filtrate enters the wastewater deammoniation process for treatment. The specific process of the wastewater deammoniation process is as follows: Add sodium carbonate to the first-stage filtrate for precipitation, and then obtain the effluent of the wastewater deammoniation process through microfiltration, ultrafiltration, and deammoniation membrane treatment. The effluent of the wastewater deammoniation process is added with sulfuric acid to adjust the pH to 10 and used as pulping liquid C for the third-stage pulping. The deammoniation membrane treatment uses sulfuric acid as the absorption acid to produce ammonium sulfate, and the ammonium sulfate formed in the wastewater deammoniation process is returned to the first-stage pulping reactor;

[0039] 3) Feed the first-stage manganese slag into the second-stage pulping reactor, and add pulping liquid B with a dosage 6 times the water content of the manganese slag. That is, the dosage of pulping liquid B is also 150 kg. For the first treatment, use clear water as pulping liquid B, and use the third-stage filtrate as pulping liquid B subsequently. Stir for 90 min for the second-stage pulping, and add sulfuric acid to adjust the pH of the electrolytic manganese slag slurry to 9.0, with the NH3-N content being 0.3 g / L. Then perform solid-liquid separation to obtain the second-stage manganese slag and the second-stage filtrate;

[0040] 4) Feed the second-stage manganese slag into the third-stage pulper, and add pulping liquid C with a dosage 6 times the water content of the manganese slag. That is, the dosage of pulping liquid C is also 150 kg. Stir for 90 min for the third-stage pulping, and then perform solid-liquid separation to obtain harmless manganese slag and the third-stage filtrate, and the third-stage filtrate is used as pulping liquid B for the second-stage pulping.

[0041] Example 2

[0042] This example provides an electrolytic manganese slag harmless treatment and ammonia recovery process, and the process flow is as Figure 1 shown, specifically including the following steps:

[0043] 1) Crush the old slag in the manganese slag yard. After detection, its water content is 24%;

[0044] 2) Feed the crushed manganese slag into the first-stage pulping reactor, and add pulping liquid A with a dosage 8 times the water content of the manganese slag. That is, when the manganese slag content is 100 kg, the dosage of pulping liquid A is 100×24%×8 = 192 kg. For the first treatment, use clear water as pulping liquid A, and use the secondary filtrate as pulping liquid A subsequently. Then stir for 90 min for first-stage pulping, and add calcium oxide to adjust the pH of the electrolytic manganese slag slurry to 10, with the NH3-N content being 1.5 g / L. The ammonia gas generated during pH adjustment is sent into the water absorption system under negative pressure to produce ammonia products, and the mass content of ammonia in the ammonia products is 9%; after the first-stage pulping reaction is completed, perform solid-liquid separation to obtain first-stage manganese slag and first-stage filtrate, and the first-stage filtrate enters the wastewater deammoniation process for treatment. The specific process of the wastewater deammoniation process is as follows: add sodium carbonate to the first-stage filtrate for precipitation, and then obtain the effluent of the wastewater deammoniation process through microfiltration, ultrafiltration, and deammoniation membrane treatment. The effluent of the wastewater deammoniation process is added with sulfuric acid to adjust the pH to 8 and used as pulping liquid C for third-stage pulping. The deammoniation membrane treatment uses sulfuric acid as the absorption acid to produce ammonium sulfate, and the ammonium sulfate formed in the wastewater deammoniation process is returned to the first-stage pulping reactor;

[0045] 3) Feed the first-stage manganese slag into the second-stage pulping reactor, and add pulping liquid B with a dosage 8 times the water content of the manganese slag. That is, the dosage of pulping liquid B is also 192 kg. For the first treatment, use clear water as pulping liquid B, and use the third-stage filtrate as pulping liquid B subsequently. Stir for 60 min for second-stage pulping, and then add sodium hydroxide to adjust the pH of the electrolytic manganese slag slurry to 10.0, with the NH3-N content being 0.2 g / L, and then perform solid-liquid separation to obtain second-stage manganese slag and second-stage filtrate;

[0046] 4) Feed the second-stage manganese slag into the third-stage pulper, and add pulping liquid C with a dosage 8 times the water content of the manganese slag. That is, the dosage of pulping liquid C is also 192 kg. Stir for 60 min for third-stage pulping, and then perform solid-liquid separation to obtain harmless manganese slag and third-stage filtrate, and the third-stage filtrate is used as pulping liquid B for second-stage pulping.

[0047] Example 3

[0048] This example provides an electrolytic manganese slag harmless treatment and ammonia recovery process, and the process flow is as Figure 1 shown, specifically including the following steps:

[0049] 1) Mix fresh manganese slag and old manganese slag in the manganese slag yard at a mass ratio of 1:1 and perform crushing treatment. After detection, its water content is 26%;

[0050] 2) Feed the crushed manganese slag into the first-stage pulping reactor, and add pulping liquid A with a dosage of 10 times the water content of the manganese slag. That is, when the manganese slag content is 100 kg, the dosage of pulping liquid A is 100×26%×10 = 260 kg. For the first treatment, use clear water as pulping liquid A, and use the secondary filtrate as pulping liquid A subsequently. Then stir for 120 min for first-stage pulping, and then add calcium oxide to adjust the pH of the electrolytic manganese slag slurry to 11, with the NH₃-N content being 1.0 g / L. The ammonia gas generated by adjusting the pH is sent into the water absorption system under negative pressure to produce ammonia products, and the mass content of ammonia in the ammonia products is 9%; after the first-stage pulping reaction, perform solid-liquid separation to obtain first-stage manganese slag and first-stage filtrate, and the first-stage filtrate enters the wastewater deammoniation process for treatment. The specific process of the wastewater deammoniation process is as follows: add sodium carbonate to the first-stage filtrate for precipitation, and then obtain the effluent of the wastewater deammoniation process through microfiltration, ultrafiltration, and deammoniation membrane treatment. The effluent of the wastewater deammoniation process is added with sulfuric acid to adjust the pH to 9 and used as pulping liquid C for third-stage pulping. The deammoniation membrane treatment uses sulfuric acid as the absorption acid to produce ammonium sulfate, and the ammonium sulfate formed in the wastewater deammoniation process is returned to the first-stage pulping reactor;

[0051] 3) Feed the first-stage manganese slag into the second-stage pulping reactor, and add pulping liquid B with a dosage of 10 times the water content of the manganese slag. That is, the dosage of pulping liquid B is also 260 kg. For the first treatment, use clear water as pulping liquid B, and use the third-stage filtrate as pulping liquid B subsequently. Stir for 120 min for second-stage pulping, and then add sulfuric acid to adjust the pH of the electrolytic manganese slag slurry to 10.0, with the NH₃-N content being 0.2 g / L. Then perform solid-liquid separation to obtain second-stage manganese slag and second-stage filtrate;

[0052] 4) Feed the second-stage manganese slag into the third-stage pulper, and add pulping liquid C with a dosage of 10 times the water content of the manganese slag. That is, the dosage of pulping liquid C is also 260 kg. Stir for 120 min for third-stage pulping, and then perform solid-liquid separation to obtain harmless manganese slag and third-stage filtrate. The third-stage filtrate is used as pulping liquid B for second-stage pulping.

[0053] Test Example 1

[0054] For the manganese slag before and after harmless treatment in the above Examples 1-3, prepare leachate according to the "Horizontal Oscillation Method for the Leaching Toxicity of Solid Wastes" (HJ 557-2010) and measure the pH, manganese content, and ammonia nitrogen content of the leachate. The test results are shown in Table 1 below;

[0055] Table 1 pH, manganese, and ammonia nitrogen content of the leachate of manganese slag before and after treatment

[0056]

[0057] As can be seen from Table 1, the pH value, manganese content, and ammonia nitrogen content of the leachate of the harmless manganese slag obtained by the present invention all meet the requirements of Class I general industrial solid waste. The present invention provides a new treatment method for the harmless treatment of electrolytic manganese slag.

[0058] Obviously, the above embodiments are merely examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or alterations can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or alterations derived therefrom are still within the protection scope of the present invention.

Claims

1. An innocuous treatment process for electrolytic manganese residue and ammonia recovery process, characterized in that, It includes the following steps: 1) Add pulping liquid A to electrolytic manganese residue for primary pulping to obtain electrolytic manganese residue slurry, then adjust the pH value of the electrolytic manganese residue slurry to 9.5 - 13 and the NH3-N content not exceeding 1.5 g / L, and then perform solid-liquid separation to obtain primary manganese residue and primary filtrate. The ammonia gas generated by adjusting pH after primary pulping is prepared into ammonia water by water absorption process; 2) Add pulping liquid B to the primary manganese residue for secondary pulping, then adjust the pH value of the electrolytic manganese residue slurry to 9.0 - 10.0 and the NH3-N content not exceeding 0.3 g / L, and then perform solid-liquid separation to obtain secondary manganese residue and secondary filtrate; 3) Add pulping liquid C to the secondary manganese residue for tertiary pulping, and then perform solid-liquid separation to obtain harmless manganese residue and tertiary filtrate; The first pulping liquid A is water, and the subsequent is secondary filtrate; The first pulping liquid B is water, and the subsequent is tertiary filtrate; The pulping liquid C is the solution obtained by adding acid to adjust the pH value to 8 - 10 after the primary filtrate passes through the wastewater deammoniation process; The wastewater deammoniation process is to add sodium carbonate to the primary filtrate for precipitation, and then through microfiltration, ultrafiltration, and deammoniation membrane treatment; The deammoniation membrane treatment uses sulfuric acid as the absorption acid to prepare ammonium sulfate; The ammonium sulfate is recycled for primary pulping.

2. The process according to claim 1, characterized in that, The pH value of the electrolytic manganese residue slurry after primary pulping is adjusted by treatment agent A; The treatment agent A is selected from at least one of calcium oxide, calcium hydroxide, and sodium hydroxide; And / or, the pH value of the electrolytic manganese residue slurry after secondary pulping is adjusted by treatment agent B; The treatment agent B is selected from at least one of calcium oxide, calcium hydroxide, sodium hydroxide, and sulfuric acid; The pH value of the pulping liquid C is adjusted by sulfuric acid.

3. The process according to claim 1, characterized in that, The dosages of the pulping liquid A, the pulping liquid B, and the pulping liquid C are all 6 - 10 times the water content of the manganese residue.

4. The process according to claim 2, characterized in that, The electrolytic manganese residue is also subjected to crushing treatment before primary pulping.

5. The process according to claim 1, characterized in that, Stirring treatment is performed during the processes of primary pulping, secondary pulping, and tertiary pulping.

6. The process according to claim 5, characterized in that, The stirring time of primary pulping ≥ 90 min; And / or, the stirring time of secondary pulping and tertiary pulping ≥ 60 min.

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