Advanced treatment method of manganese residue leachate

Abstract

The invention discloses an advanced treatment method of manganese residue leachate, which comprises the following steps: mixing the manganese residue leachate and hydrogen peroxide, stirring, adjusting the pH value of the system to be greater than or equal to 11, adding carbonate for precipitation reaction, stirring, adding a flocculant for flocculation reaction, filtering, and sequentially performing ultrafiltration treatment, cyclic ammonia nitrogen removal treatment, cyclic absorption and evaporative crystallization on the filtrate, an ammonium sulfate product is obtained. Compared with a conventional method, the advanced treatment method for the manganese residue leachate can efficiently and thoroughly remove metal ions and ammonia nitrogen in the manganese residue leachate, meanwhile, an ammonium sulfate product with high purity can be obtained, the purity exceeds 98%, resource utilization of the ammonia nitrogen can be achieved, and the method is suitable for industrial production. The method has the advantages of simple process, low treatment cost, high treatment efficiency, good metal ion removal effect, high ammonia nitrogen recovery rate, high ammonium sulfate purity and the like, and is high in use value and good in application prospect.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of environmental engineering, and particularly relates to a deep treatment method of manganese residue leachate. BACKGROUND

[0002] Manganese residue leachate refers to leachate generated in the process of stacking manganese residue, and mainly contains ammonia nitrogen (NH3-N) and manganese (Mn 2+ ). However, if the manganese residue leachate is directly discharged without treatment, it will seriously pollute the surrounding ecological environment and affect the life and health of residents. Therefore, it is urgent to effectively reduce the content of ammonia nitrogen (NH3-N) and manganese (Mn 2+ ) in the manganese residue leachate and make them meet the discharge standard by deep treatment of the manganese residue leachate. In addition, the manganese residue is mainly electrolytic manganese residue, which is a high-moisture solid waste generated in the production process of electrolytic manganese and contains a large amount of soluble salt, solid mineral, heavy metal harmful elements such as chromium, lead and arsenic. At the same time, these components will also partially seep into the manganese residue leachate, which increases the difficulty of treatment of the manganese residue leachate.

[0003] Currently, the main methods for treating manganese slag leachate include stripping gas stripping method, biochemical method, catalytic oxidation method, chemical precipitation method, ion exchange method, etc. However, these methods still have the problems of high treatment cost, poor treatment effect, secondary pollution risk, etc., and are difficult to realize industrialization. In addition, some researchers have proposed a method for treating electrolytic manganese slag leachate and recovering manganese, magnesium and ammonium therefrom. The electrolytic manganese slag leachate is treated with carbonates, phosphates, lime and sodium carbonate in sequence, thereby converting manganese, magnesium, ammonium and calcium in the leachate into manganese carbonate, ammonium magnesium phosphate, calcium magnesium manganese slag and industrial calcium carbonate, and at the same time, the leachate is subjected to membrane deamination treatment, so that the wastewater is discharged in compliance with the standard and industrial ammonium sulfate is recovered. However, this method still has the following disadvantages: (1) low treatment efficiency, including four times of precipitation treatment, many steps, complex process, and difficult to quickly purify the leachate; (2) large amount of reagents, high treatment cost, and not suitable for industrial application; (3) poor purification effect on residual metal ions in the leachate, the leachate is treated with lime and sodium carbonate, which is difficult to effectively remove the residual calcium, magnesium and manganese ions and other impurities in the leachate, resulting in that the influent of the deamination membrane still contains a large amount of metal ions and impurities. The existence of these metal ions and impurities not only damages the deamination membrane, but also interferes with the separation effect of the deamination membrane on ammonia nitrogen, resulting in poor deamination effect or increasing the maintenance and replacement cost, and finally leading to a significant increase in the cost of membrane deamination treatment; (4) low recovery rate of manganese ions by using carbonates, and most of the manganese ions are transferred to calcium magnesium manganese slag, which not only easily causes resource waste, but also increases the production of calcium magnesium manganese slag, thereby increasing the subsequent treatment cost, such as significantly increasing the landfill cost, and increasing the secondary pollution risk caused by landfill; (5) using phosphates to remove ammonia, on the one hand, the obtained ammonium magnesium phosphate (bird nest stone) is a waste material without economic value, which is not used in industry, resulting in poor resource utilization effect of ammonia nitrogen; (6) using single treatment, which is difficult to effectively remove ammonia nitrogen in the leachate, resulting in that the concentration of ammonia nitrogen in the leachate is still high, and at the same time, the concentration of ammonium sulfate in the ammonium sulfate solution formed by absorbing ammonia gas with sulfuric acid is still low, which is not conducive to improving the utilization rate of sulfuric acid, and also easily increases the treatment amount of subsequent evaporation crystallization, resulting in high recovery cost of ammonium sulfate.

[0004] Therefore, how to obtain a deep treatment method for manganese slag leachate, which has the advantages of simple process, low treatment cost, high treatment efficiency, good metal ion removal effect, high ammonia nitrogen recovery rate and high purity of ammonium sulfate, has great practical significance for realizing harmless treatment and resource recycling of ammonia nitrogen of manganese slag leachate. SUMMARY

[0005] The technical problem to be solved by the present application is to overcome the shortcomings of the prior art and provide a deep treatment method for manganese slag leachate, which has the advantages of simple process, low treatment cost, high treatment efficiency, good metal ion removal effect, high ammonia nitrogen recovery rate and high purity of ammonium sulfate.

[0006] To solve the above technical problems, the present application adopts the following technical solutions.

[0007] A method for deep treatment of manganese slag leachate, comprising the following steps: (1) mixing manganese slag leachate and hydrogen peroxide, stirring, adjusting the pH value of the system to be greater than or equal to 11, adding carbonate for precipitation reaction, stirring, adding flocculant for flocculation reaction, filtering to obtain filter residue and filtrate A; (2) performing ultrafiltration treatment on the filtrate A to obtain filtrate B; (3) performing cyclic deamination and denitrification treatment on the filtrate B until the ammonia nitrogen concentration in the effluent is less than or equal to 5 mg / L to obtain filtrate C; (4) using sulfuric acid to cyclically absorb ammonia gas generated in the process of cyclic deamination and denitrification treatment until the mass fraction of ammonium sulfate in the effluent is 15% to 20% to obtain an ammonium sulfate solution; (5) evaporating and crystallizing the ammonium sulfate solution to obtain ammonium sulfate products.

[0008] The above-mentioned method for deep treatment of manganese slag leachate is further improved, in step (1), the amount of hydrogen peroxide added is 0.08 L to 0.15 L per cubic meter of the manganese slag leachate; the mass concentration of H2O2 in the hydrogen peroxide is 27.5%.

[0009] The above-mentioned method for deep treatment of manganese slag leachate is further improved, in step (1), the pH value of the system is adjusted to 11 to 13 using an alkaline solution; the alkaline solution is at least one of a calcium hydroxide solution and a sodium hydroxide solution.

[0010] The above-mentioned method for deep treatment of manganese slag leachate is further improved, in step (1), the amount of carbonate added is 1.5 kg to 2.5 kg per cubic meter of the manganese slag leachate; the carbonate is at least one of ammonium carbonate, ammonium bicarbonate, and sodium carbonate.

[0011] The above-mentioned method for deep treatment of manganese slag leachate is further improved, in step (1), the amount of flocculant added is 0.3 L to 0.5 L per cubic meter of the manganese slag leachate; the flocculant is a polyacrylamide solution; the mass fraction of the polyacrylamide solution is 0.1%; the manganese slag leachate is electrolytic manganese slag leachate.

[0012] The above-mentioned method for deep treatment of manganese slag leachate is further improved, in step (1), a filter press is used to filter the product obtained after the flocculation reaction.

[0013] The improved manganese slag leachate deep treatment method, in the step (3), the process of the cyclic deamination and denitrification treatment further comprises: adding an alkaline solution to the leachate B, and filtering the leachate B; the alkaline solution is a sodium hydroxide solution.

[0014] The improved manganese slag leachate deep treatment method, in the step (4), the process of the cyclic absorption further comprises: filtering the sulfuric acid; the mass fraction of the sulfuric acid is 10%-20%.

[0015] The improved manganese slag leachate deep treatment method, in the step (5), before the evaporation crystallization of the ammonium sulfate solution, the following treatment is further included: adjusting the pH value of the ammonium sulfate solution to 5-6.5 by using an alkaline reagent; the alkaline reagent is at least one of ammonium carbonate and ammonia water.

[0016] The improved manganese slag leachate deep treatment method, in the step (1), the subsequent treatment of the manganese slag is landfill.

[0017] The improved manganese slag leachate deep treatment method, in the step (2), the ultrafiltration membrane is used for the ultrafiltration treatment of the leachate A.

[0018] The improved manganese slag leachate deep treatment method, in the step (3), the subsequent treatment of the leachate C is: adjusting the pH value of the leachate C to 7.1, and discharging after reaching the standard.

[0019] The improved manganese slag leachate deep treatment method, in the step (5), the MVR equipment is used for the evaporation crystallization of the ammonium sulfate solution; the purity of the ammonium sulfate product is 98.3%.

[0020] Compared with the prior art, the manganese slag leachate deep treatment method has the following advantages: In view of the problems of complex process, difficult operation, high treatment cost, poor metal ion removal effect, low ammonia nitrogen recovery rate and low ammonium sulfate purity in the existing treatment method, the application creatively provides a deep treatment method of manganese residue leachate, first mixes the manganese residue leachate and hydrogen peroxide, under the action of hydrogen peroxide, manganese ions in the leachate can be promoted to be oxidized into high-valence manganese oxide, then by adjusting the pH value of the leachate to be greater than or equal to 11 and adding carbonate, under the action of carbonate ions, precipitates such as manganese carbonate, trimanganese tetroxide and manganese dioxide can be generated, and under the promoting action of the flocculating agent, the particle size of the above-mentioned precipitates becomes large to form large particles and agglomerate, and the precipitation of the precipitates is promoted, so that the metal ions in the leachate can be quickly and effectively removed through simple filtration, at the same time, by effectively removing the heavy metal ions in the filtrate and optimizing the pH value of the filtrate, it is also beneficial to improve the ammonia nitrogen removal effect and treatment efficiency of the subsequent filtrate, and at the same time, the treatment amount of the solution can be reduced, on this basis, the filtrate is subjected to ultrafiltration treatment, which can effectively remove macromolecular substances such as suspended particles and colloids in the filtrate, so as to prevent them from blocking the degassing membrane in the ammonia nitrogen removal device, thereby the subsequent cyclic ammonia nitrogen removal treatment can be smoothly carried out, and the separation effect of the degassing membrane on ammonia nitrogen and the service life of the degassing membrane can be improved, at this time, the filtrate subjected to the ultrafiltration treatment is subjected to cyclic ammonia nitrogen removal treatment, the ammonia nitrogen in the leachate can be quickly and completely separated out, and the related discharge requirements can be met, that is, the effluent quality reaches the first level standard of the Comprehensive Sewage Discharge Standard (GB 8978-1996), at the same time, the ammonia gas generated in the process of the cyclic ammonia nitrogen removal treatment is absorbed by sulfuric acid, the ammonia nitrogen separated out from the leachate is transferred to the sulfuric acid to form an ammonium sulfate solution, in this process, the remaining sulfuric acid in the ammonium sulfate solution continuously absorbs ammonia gas, more ammonia nitrogen is transferred to the sulfuric acid, and the concentration of ammonium sulfate in the solution is significantly increased, finally, the ammonium sulfate solution is subjected to evaporation crystallization, and high-purity ammonium sulfate products can be obtained, thereby the deep treatment and resource recovery of the manganese residue leachate are completed. Compared with the conventional method, the deep treatment method of the manganese residue leachate can efficiently and completely remove the metal ions and ammonia nitrogen in the manganese residue leachate, and high-purity ammonium sulfate products can also be obtained, the purity of the ammonium sulfate products is more than 98%, the resource utilization of ammonia nitrogen can be realized, and the method has the advantages of simple process, low treatment cost, high treatment efficiency, good metal ion removal effect, high ammonia nitrogen recovery rate, high ammonium sulfate purity and the like, has high use value and good application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 Figure 1 is a deep treatment process flow diagram of the manganese residue leachate in the embodiment 1 of the application. DETAILED DESCRIPTION

[0022] The application will be further described in conjunction with the accompanying drawings and specific preferred embodiments, but the protection scope of the application shall not be limited thereby. The materials and instruments used in the following examples are commercially available.

[0023] Example 1 A method for deep treatment of manganese slag leachate according to the present application, as shown in the figure, comprises the following steps: Figure 1 (1) Collecting manganese slag leachate, adding hydrogen peroxide according to the amount of 0.1 L / m 3 , i.e. adding 0.1 L of industrial hydrogen peroxide (purchased in the market) with a mass concentration of 27.5% of H2O2 into the manganese slag leachate, and stirring, which can promote the oxidation of manganese ions in the leachate into high-valence manganese oxides under the action of hydrogen peroxide, adding sodium hydroxide solution to adjust the pH value of the system to 11.8, adding sodium carbonate according to the amount of 2 kg / m 3 for precipitation reaction, stirring, and generating manganese carbonate, trimanganese tetroxide and manganese dioxide and other precipitates under the action of carbonate ions, adding 0.1% polyacrylamide (PAM) solution according to the amount of 0.3 L / m 3 for flocculation reaction, so that the particle size of the above-mentioned precipitates becomes large to form large particles and agglomerate, promoting the precipitation of the precipitates, and using a filter press to filter the product after flocculation reaction to obtain filter residue and filtrate A.

[0024] In this step, the collected manganese slag leachate is electrolytic manganese slag leachate, the content of Mn in the manganese slag leachate is 267 mg / L, the content of NH3-N is 193 mg / L, the content of Cr 6+ is 39 mg / L, the content of Pb is 3.7 mg / L, the content of COD is 67 mg / L, and the content of SS is 163 mg / L, and the pH of the manganese slag leachate is 3.8.

[0025] After testing, the content of Mn in the filtrate A is 2 mg / L, the content of NH3-N is 186 mg / L, the content of Cr 6+ is 0.5 mg / L, the content of Pb is 0.9 mg / L, the content of COD is 81 mg / L, and the content of SS is 61 mg / L.

[0026] In this step, the filter residue (manganese slag) is sent to a manganese slag landfill site for landfill.

[0027] (2) Using an ultrafiltration device (ultrafiltration membrane) to perform ultrafiltration treatment on the filtrate A obtained in step (1) to remove suspended particles, colloids and other macromolecular substances in the filtrate to obtain filtrate B.

[0028] ​(3) The filtrate B is subjected to cyclic deamination and denitrification treatment until the ammonia nitrogen concentration in the effluent is ≤5 mg / L, to obtain filtrate C, specifically as follows: (3.1) The filtrate B is filtered by using a ceramic filter to remove fine particles.

[0029] (3.2) The filtered filtrate B is pumped into a degassing membrane device, and ammonia nitrogen is separated from the filtrate B and forms ammonia gas into the other side of the degassing membrane under the action of the degassing membrane. The effluent in the degassing membrane device is returned to the circulating pool where the filtrate B is located, and the deamination and denitrification treatment is continued.

[0030] (3.3) Repeat steps (3.1) to (3.2) to cyclically deaminate and denitrify the filtrate B until the ammonia nitrogen concentration in the effluent is ≤5 mg / L, to obtain the filtrate C.

[0031] In step (3), the filtration treatment of the filtrate B can also be omitted.

[0032] In step (3), during the cyclic deamination and denitrification treatment, an alkaline solution is added to the filtrate B to adjust the filtrate B to be alkaline, wherein the alkaline solution is a sodium hydroxide solution. In the present application, by adjusting the filtrate B to be alkaline, the separation effect of ammonia nitrogen in the degassing membrane can be promoted.

[0033] In step (3.2), the pH value of the filtrate C is adjusted to 7.1 by using an acid, which meets the relevant discharge standards and can be directly discharged.

[0034] (4) The ammonia gas generated during the cyclic deamination and denitrification treatment in step (3) is cyclically absorbed by using sulfuric acid with a mass fraction of 10%, until the mass fraction of ammonium sulfate in the effluent is 18.7%, to obtain an ammonium sulfate solution, specifically as follows: (4.1) The sulfuric acid is filtered by using a carbon ceramic filter to remove fine particles.

[0035] (4.2) The filtered sulfuric acid is pumped into a degassing membrane device to absorb the ammonia gas generated during the cyclic deamination and denitrification treatment. The obtained ammonium sulfate solution (effluent) is returned to the circulating pool where the sulfuric acid is located, and is continuously used to absorb the ammonia gas generated during the cyclic deamination and denitrification treatment.

[0036] (4.3) Repeat steps (4.1) to (4.2) to cyclically absorb the ammonia gas until the mass fraction of ammonium sulfate in the effluent is 18.7%, to obtain the ammonium sulfate solution.

[0037] (5) The pH value of the ammonium sulfate solution is adjusted to 6.1 by using ammonium carbonate, and the ammonium sulfate solution is evaporated and crystallized in an MVR device to produce ammonium sulfate crystals, to obtain ammonium sulfate products with a purity of 98.3%.

[0038] In this embodiment, the influence of different hydrogen peroxide dosages on the removal effect of metal ions in the manganese slag leachate is also investigated. Except that the hydrogen peroxide dosages are different, other conditions are the same as those in Example 1, as shown in Table 1.

[0039] Table 1 Influence of different hydrogen peroxide dosages on the removal effect of metal ions in the manganese slag leachate

[0040] As shown in Table 1, in the present application, under the combined action of hydrogen peroxide, carbonate and flocculant, the heavy metal ions in the manganese slag leachate can be quickly and completely removed. In particular, when the addition amount of hydrogen peroxide is 0.08L / m 3 ~0.15L / m 3 , the heavy metal ions in the manganese slag leachate can be more efficiently and completely removed, and at the same time, the treatment cost is relatively lower.

[0041] In this embodiment, the influence of different pH values of the system on the removal effect of metal ions in the manganese slag leachate is also investigated. Except that the pH value of the system in step (1) is different, other conditions are the same as those in Example 1, as shown in Table 2.

[0042] Table 2 Influence of different pH values of the system on the removal effect of metal ions in the manganese slag leachate

[0043] As shown in Table 2, in the present application, by adjusting the pH value of the system to be ≥11, the removal effect of manganese ions in the leachate can be improved, and each metal ion in the leachate can meet the discharge standard. However, when the pH value of the system is <11, the metal ions in the leachate cannot be effectively removed, which eventually leads to a high concentration of metal ions in the leachate. On the one hand, the heavy metal concentration of the final effluent is difficult to meet the discharge standard, and on the other hand, a large amount of manganese ions in the leachate also leads to poor separation effect of the degassing membrane on ammonia nitrogen, which is not conducive to the resource utilization of ammonia nitrogen, and easily damages the degassing membrane, resulting in a significant increase in treatment cost.

[0044] Comparative Example 1 A manganese slag leachate treatment method is basically the same as that in Example 1, except that in step (1), no hydrogen peroxide is added, and the pH value of the system is adjusted to 10.

[0045] After testing, the Mn content in the leachate A is 35mg / L, which cannot meet the relevant discharge requirements.

[0046] From the above results, compared with the conventional treatment method, the manganese slag leachate deep treatment method has the advantages of simple process, low treatment cost, high treatment efficiency, good metal ion removal effect, high ammonia nitrogen recovery rate, high ammonium sulfate purity and the like, can efficiently and completely remove metal ions and ammonia nitrogen in the manganese slag leachate, and also can obtain high-purity ammonium sulfate product, the purity is more than 98%, can realize the resource utilization of ammonia nitrogen, the use value is high, and the application prospect is good.

[0047] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Although the present application has been disclosed as above with a preferred embodiment, it is not intended to limit the present application. Any person skilled in the art can make many possible changes and modifications to the technical solutions of the present application, or modify equivalent embodiments with equivalent changes, without departing from the spirit and technical solutions of the present application. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments according to the technical essence of the present application, without departing from the technical solutions of the present application, still belongs to the protection scope of the technical solutions of the present application.

Claims

1. A method for deep treatment of manganese slag leachate, characterized in that: The following steps are involved: (1) Mixing the manganese slag leachate and hydrogen peroxide, stirring, adjusting the pH value of the system to ≥11, adding carbonate to carry out precipitation reaction, stirring, adding flocculant to carry out flocculation reaction, filtering, and obtaining filter residue and filtrate A; (2) Ultrafiltration treatment is performed on filtrate A to obtain filtrate B; (3) Circulating the filtrate B to remove ammonia nitrogen until the ammonia nitrogen concentration in the effluent is ≤5 mg / L, thereby obtaining filtrate C; (4) Circulating and absorbing the ammonia gas generated during the cyclic deammoniation and nitrogen treatment process with sulfuric acid until the mass fraction of ammonium sulfate in the effluent is 15% to 20%, thereby obtaining an ammonium sulfate solution; (5) Evaporating and crystallizing the ammonium sulfate solution to obtain an ammonium sulfate product.

2. The deep treatment method of manganese slag leachate according to claim 1, characterized in that: In step (1), the amount of hydrogen peroxide added is 0.08L to 0.15L per cubic meter of manganese slag leachate; the mass concentration of H2O2 in the hydrogen peroxide is 27.5%.

3. The deep treatment method of manganese slag leachate according to claim 2, characterized in that: In step (1), an alkaline solution is used to adjust the pH value of the system to 11-13; the alkaline solution is at least one of a calcium hydroxide solution and a sodium hydroxide solution.

4. The deep treatment method of manganese slag leachate according to claim 3, characterized in that: In step (1), the amount of carbonate added is 1.5 kg to 2.5 kg per cubic meter of the manganese slag leachate; and the carbonate is at least one of ammonium carbonate, ammonium bicarbonate and sodium carbonate.

5. The deep treatment method of manganese slag leachate according to claim 4, characterized in that: In step (1), the amount of the flocculant added is 0.3L to 0.5L per cubic meter of the manganese slag leachate; the flocculant is a polyacrylamide solution; the mass fraction of the polyacrylamide solution is 0.1%; and the manganese slag leachate is electrolytic manganese slag leachate.

6. The deep treatment method of manganese slag leachate according to claim 5, characterized in that: In step (1), a filter press is used to filter the product obtained after the flocculation reaction.

7. The method for deep treatment of manganese slag leachate according to any one of claims 1 to 6, characterized in that: In step (3), the cyclic deammoniation and nitrogen removal process further includes: adding an alkaline solution to the filtrate B and filtering the filtrate B; the alkaline solution is a sodium hydroxide solution.

8. The method for deep treatment of manganese slag leachate according to any one of claims 1 to 6, characterized in that: In step (4), the cyclic absorption process further includes: filtering the sulfuric acid; the mass fraction of the sulfuric acid is 10%.

9. The method for deep treatment of manganese slag leachate according to any one of claims 1 to 6, characterized in that: In step (5), the following treatment is also included before the ammonium sulfate solution is evaporated and crystallized: an alkaline agent is used to adjust the pH value of the ammonium sulfate solution to 5-6.5; the alkaline agent is at least one of ammonium carbonate and ammonia water.

10. The method for deep treatment of manganese slag leachate according to any one of claims 1 to 6, characterized in that: In step (1), the subsequent treatment of the manganese slag is landfill; In step (2), the filtrate A is ultrafiltered using an ultrafiltration membrane; In step (3), the subsequent treatment of the filtrate C is as follows: adjusting the pH value of the filtrate C to 7.1 and discharging it after reaching the standard; In step (5), the ammonium sulfate solution is evaporated and crystallized using MVR equipment; the purity of the ammonium sulfate product is 98.3%.

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