Treatment method for removing ammonia nitrogen from electrolytic manganese residues through low-temperature roasting

Abstract

The invention discloses a treatment method for removing ammonia nitrogen from electrolytic manganese residues through low-temperature roasting, and belongs to the technical field of solid waste treatment. The treatment method comprises the following steps: crushing and grinding the electrolytic manganese residues to obtain electrolytic manganese residue powder, mixing the electrolytic manganese residue powder with a composite deamination agent (consisting of calcium oxide, calcium hydroxide, sodium hydroxide and activated carbon), and roasting, according to the method, the special composite deamination agent is adopted, low-temperature, rapid and efficient deamination of the electrolytic manganese residues can be achieved, operation is easy, energy consumption is low, cost is low, and application and popularization are facilitated.

Description

Technical Field

[0001] The invention relates to a method for removing ammonia and nitrogen from electrolytic manganese slag solid waste, and in particular to a method for removing ammonia and nitrogen from electrolytic manganese slag by low-temperature roasting, and belongs to the technical field of environmental protection application. Background Art

[0002] Manganese metal is one of the country's important strategic resources and is widely used in the steel industry. Currently, manganese metal is mainly produced by electrolysis and reduction. my country's electrolytic manganese industry started late, but has developed rapidly and has become the world's largest producer, exporter and consumer of electrolytic manganese. However, with the rapid development of the electrolytic manganese metal industry, a series of environmental and resource problems have followed, and the industry is facing increasing development pressure.

[0003] Electrolytic manganese production is a "three highs" industry with high material consumption, high energy consumption and high pollution. Electrolytic manganese slag is an acidic solid waste generated in the production process of metallic manganese. Electrolytic manganese slag is the largest and most dangerous pollution source in the electrolytic manganese industry, with extremely high environmental risks. It contains a large amount of Mn 2+ , ammonia nitrogen, sulfate, arsenic, mercury and other complex pollutants, and the particles are fine, with strong water retention, and they are in a muddy state for a long time, posing serious environmental pollution and safety hazards.

[0004] Chinese patent (publication number CN118768365A) discloses a process for harmless treatment of electrolytic manganese slag by wet method, which realizes harmless treatment of manganese slag by crushing manganese slag, first pulping, vacuum filtration, first-stage spray washing, second-stage spray washing, second-stage pulping and filter pressing, and performs manganese precipitation reaction, first-stage filtration, calcium and magnesium precipitation reaction, second-stage filtration, amination reaction, third-stage filtration and stripping on the filtrate of vacuum filtration, but the process is cumbersome and the cost is high. Chinese patent (publication number CN117776662A) discloses a method for curing electrolytic manganese slag, which uses appropriate sodium phosphate, quicklime, cement, fly ash or calcium oxide, sodium hydroxide, sodium silicate to treat electrolytic manganese slag, which can not only realize harmless treatment of electrolytic manganese slag, but also facilitate resource recycling of electrolytic manganese slag, and can be used to generate geopolymers, but the reagent cost is too high and the dosage is large, resulting in high treatment cost. A Chinese patent (publication number CN114632801A) discloses a method for deammoniation and desulfurization of manganese slag using a rotary kiln. In this method, a composite deammoniation agent and electrolytic manganese slag are placed in a mixer for stirring, and then heated using the waste heat from the kiln head and a hot air furnace, and treated at 200-300°C for 1 hour to obtain deammoniation slag and mixed gas.

[0005] In summary, the present invention aims at the problems of complicated process, high energy consumption and low efficiency in the prior art, and provides a low-temperature roasting deamination treatment process for electrolytic manganese slag, which overcomes the above-mentioned defects by reacting at low temperature and adding a deamination agent. Summary of the invention

[0006] In view of the technical problems existing in the prior art, the purpose of the present invention is to provide a treatment method for low-temperature roasting and deammoniation of electrolytic manganese slag, which can achieve rapid and efficient removal of ammonia nitrogen from electrolytic manganese slag at low temperature, so as to solve the technical problems existing in the prior art such as complicated electrolytic manganese slag treatment process, high cost and low efficiency.

[0007] In order to achieve the above technical objectives, the present invention provides a method for removing ammonia nitrogen by low-temperature roasting of electrolytic manganese slag, the method comprising crushing and grinding the electrolytic manganese slag to obtain electrolytic manganese slag powder, and roasting the electrolytic manganese slag powder after mixing with a composite deamination agent; the composite deamination agent is composed of calcium oxide, calcium hydroxide, sodium hydroxide and activated carbon.

[0008] The key to the technical solution of the present invention is the use of a special composite deammoniation agent composed of calcium oxide, calcium hydroxide, sodium hydroxide and activated carbon, wherein calcium oxide, calcium hydroxide and sodium hydroxide as alkaline compounds can react with ammonium salts such as ammonium sulfate to release ammonia. Compared with a single alkaline compound, the composite alkaline compound composed of calcium oxide, calcium hydroxide and sodium hydroxide can better react with ammonium salts such as ammonium sulfate to release ammonia, and the activated carbon can effectively reduce the decomposition temperature of ammonium salts such as ammonium sulfate, promote the rapid and efficient release of ammonia from ammonium salts such as ammonium sulfate in electrolytic manganese slag at a lower temperature, shorten the ammonia nitrogen removal time, and reduce the agent consumption and energy consumption.

[0009] As a preferred solution, the main components and mass contents of the electrolytic manganese slag are: SiO2 37.52~46.22%, Al2O3 10.09~15.06%, CaO 6.03~10.2%, Fe2O3 5.79~7.03%, MnO 2.54~3.61%, MgO 1.82~2.68%, and the ammonia nitrogen leaching concentration is 1100~1300 mg / L.

[0010] As a preferred solution, calcium oxide and calcium hydroxide in the composite deamination agent are composed of 80-90% by mass: 10-20%, the mass of sodium hydroxide is 0.5-1.5% of the total mass of calcium oxide and calcium hydroxide, and the mass of activated carbon is 0.5-1.5% of the total mass of calcium oxide and calcium hydroxide. Calcium oxide and calcium hydroxide are used as the main active ingredients for removing ammonia nitrogen in the composite deamination agent, sodium hydroxide is used as a strong base promoter, and activated carbon is used as a catalyst promoter. Among them, calcium oxide and calcium hydroxide are preferably matched in an appropriate proportion. Calcium oxide can use the moisture in the electrolytic manganese slag to produce an exothermic reaction, store heat for the electrolytic manganese slag, and promote the reaction between ammonium salts such as ammonium sulfate and calcium hydroxide. At the same time, calcium oxide reacts with water to be converted into active calcium hydroxide, which can be used as the main component for reacting with ammonium salts such as ammonium sulfate. Therefore, based on the water content in the conventional electrolytic manganese slag, introducing an appropriate proportion of calcium oxide is beneficial for the removal of ammonia nitrogen in the electrolytic manganese slag, and further increasing the content of calcium oxide will not have a very high improvement on the deamination effect of the electrolytic manganese slag. Sodium hydroxide has a stronger alkalinity than calcium hydroxide. Its introduction can improve the efficiency of ammonia nitrogen removal. However, considering the cost and deammoniation effect of sodium hydroxide, a lower dosage is selected. A small amount of activated carbon can significantly reduce the efficiency and required temperature of ammonia nitrogen removal and shorten the ammonia nitrogen removal time. Since activated carbon does not participate in the reaction but only plays a promoting role, a lower addition amount can be used.

[0011] As a preferred solution, the mass ratio of the composite deamination agent to the electrolytic manganese slag is 2-4:6-8. If the usage ratio of the composite deamination agent is too low, it is difficult to promote the efficient removal of ammonia nitrogen in the electrolytic manganese slag. If the usage ratio of the composite deamination agent is too high, although the ammonia nitrogen removal efficiency can be improved, the cost is also increased accordingly. The introduction of too much composite deamination agent will affect the subsequent resource utilization of the electrolytic manganese slag.

[0012] As a preferred solution, the roasting temperature is 130-180°C and the roasting time is 10-30 minutes. A further preferred roasting temperature is 140-160°C. The roasting temperature is one of the important factors affecting the removal efficiency of ammonia nitrogen in electrolytic manganese slag. Under the same roasting time, as the roasting temperature increases, the removal efficiency of ammonia nitrogen in electrolytic manganese slag is higher. However, when the roasting temperature is lower than 130°C, it is difficult for the composite deamination agent to react with ammonium salts such as ammonium sulfate, and the purpose of efficient removal of ammonia nitrogen cannot be achieved. Of course, the higher the temperature, the higher the energy consumption, and low energy consumption is what the industry pursues.

[0013] As a preferred solution, the electrolytic manganese slag is crushed and ground to 100-120 meshes. Within the appropriate particle size range, it is beneficial for the electrolytic manganese slag to better contact and react with the composite deammoniation agent.

[0014] Compared with the prior art, the beneficial technical effects brought by the technical solution of the present invention are as follows: (1) The present invention uses a special composite deamination agent to remove ammonia and nitrogen from electrolytic manganese slag, which can not only solve the problem of too high ammonia and nitrogen content in electrolytic manganese slag when it is recycled in the field of building materials, but also solve the problem of high cost and low efficiency in the deamination treatment of electrolytic manganese slag by small and medium-sized electrolytic manganese enterprises.

[0015] (2) The present invention adopts a special composite deamination agent to significantly reduce the deamination temperature and shorten the deamination time. While effectively removing ammonia nitrogen from electrolytic manganese slag, it effectively reduces energy consumption. The process operation is simple, the product added value is higher, and the cost is lower. It has important guiding significance in the field of solid waste treatment and environmental protection application technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a process flow chart for deammoniation by low-temperature roasting of electrolytic manganese slag. DETAILED DESCRIPTION

[0017] In order for those skilled in the art to better understand the present invention, the present invention is further described in detail below in conjunction with the following embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention.

[0018] In the following specific embodiments, the main components and mass contents of the electrolytic manganese slag involved are: SiO2 42.2%, SO3 20.87%, Al2O3 13.09%, CaO 8.03%, Fe2O3 4.79%, MnO 2.71%, MgO 2.12%, and ammonia nitrogen leaching concentration 1294.4 mg / L.

[0019] Example 1 (1) The electrolytic manganese slag is crushed, ground and sieved to 100-120 mesh, and the moisture content of the manganese slag is 15%; (2) Calcium oxide and calcium hydroxide are mixed in a mass ratio of 9:1, and 1% sodium hydroxide and 1% activated carbon are added to prepare a composite deammoniation agent; (3) The sieved electrolytic manganese slag and the composite deammoniation agent are mixed and stirred in a mass ratio of 8:2; (4) calcining the mixture in a tube furnace at 150°C for 10 min; (5) Leaching electrolytic manganese slag according to the "Horizontal Oscillation Method for Leaching Toxicity of Solid Waste" (HJ557-2010); (6) Determine the ammonia nitrogen concentration of the leaching solution according to the "Determination of Ammonia Nitrogen in Water - Nessler's Reagent Spectrophotometric Method" (HJ535-2009); (7) The ammonia nitrogen removal rate of the treated electrolytic manganese slag can reach 96.0%. Further extending the roasting time to 30 min, the ammonia nitrogen removal rate of the treated electrolytic manganese slag is increased to 98.1%. It is shown that under the conditions of this embodiment, the ammonia nitrogen in the electrolytic manganese slag can be efficiently removed at low temperature in a short time.

[0020] Example 2 (1) The electrolytic manganese slag is crushed and ground, and then sieved to 100-120 mesh. The moisture content of the manganese slag is 15%; (2) Calcium oxide and calcium hydroxide are mixed in a mass ratio of 9:1, and 1% sodium hydroxide and 1% activated carbon are added to prepare a composite deammoniation agent; (3) The sieved electrolytic manganese slag and the composite deammoniation agent are mixed and stirred in a mass ratio of 7:3; (4) calcining the mixture in a tube furnace at 100°C, 130°C, 150°C, and 180°C for 30 min respectively; (5) Leaching electrolytic manganese slag according to the "Horizontal Oscillation Method for Leaching Toxicity of Solid Waste" (HJ557-2010); (6) Determine the ammonia nitrogen concentration of the leaching solution according to the "Determination of Ammonia Nitrogen in Water - Nessler's Reagent Spectrophotometric Method" (HJ535-2009); (7) The ammonia nitrogen removal rates of the treated electrolytic manganese slag were 95.4%, 97.5%, 98.4% and 98.8%, respectively.

[0021] Example 3 (1) The electrolytic manganese slag is crushed, ground and sieved to 100-120 mesh, and the moisture content of the manganese slag is 15%; (2) Calcium oxide and calcium hydroxide are mixed in a mass ratio of 8:2, and 1% sodium hydroxide and 1% activated carbon are added to prepare a composite deammoniation agent; (3) The sieved electrolytic manganese slag and the composite deammoniation agent are mixed and stirred in a mass ratio of 8:2; (4) calcining the mixture in a tube furnace at 150°C for 10 min; (5) Leaching electrolytic manganese slag according to the "Horizontal Oscillation Method for Leaching Toxicity of Solid Waste" (HJ557-2010); (6) Determine the ammonia nitrogen concentration of the leaching solution according to the "Determination of Ammonia Nitrogen in Water - Nessler's Reagent Spectrophotometric Method" (HJ535-2009); (7) The ammonia nitrogen removal rate of the treated electrolytic manganese slag can reach 97.2%.

[0022] Example 4 (1) The electrolytic manganese slag is crushed, ground and sieved to 100-120 mesh, and the moisture content of the manganese slag is 15%; (2) Calcium oxide and calcium hydroxide are mixed in a mass ratio of 8:2, and 1% sodium hydroxide and 1% activated carbon are added to prepare a composite deammoniation agent; (3) The sieved electrolytic manganese slag and the composite deammoniation agent are mixed and stirred in a mass ratio of 7:3; (4) calcining the mixture in a tube furnace at 150°C for 10 min; (5) Leaching electrolytic manganese slag according to the "Horizontal Oscillation Method for Leaching Toxicity of Solid Waste" (HJ557-2010); (6) Determine the ammonia nitrogen concentration of the leaching solution according to the "Determination of Ammonia Nitrogen in Water - Nessler's Reagent Spectrophotometric Method" (HJ535-2009); (7) The ammonia nitrogen removal rate of the treated electrolytic manganese slag after low-temperature roasting can reach 97.4%.

[0023] Comparative Example 1 (1) The electrolytic manganese slag is crushed, ground and sieved to 100-120 mesh, and the moisture content of the manganese slag is 15%; (2) placing the screened electrolytic manganese slag in a tube furnace and roasting at 400° C. for 20 min; (4) Leaching electrolytic manganese slag according to the "Horizontal Oscillation Method for Leaching Toxicity of Solid Waste" (HJ557-2010); (5) Determine the ammonia nitrogen concentration of the leaching solution according to the "Determination of Ammonia Nitrogen in Water - Nessler's Reagent Spectrophotometric Method" (HJ535-2009); (6) The ammonia nitrogen removal rate of the treated electrolytic manganese slag after low-temperature roasting reaches 94.5%.

[0024] This comparative example shows that if no composite deamination agent is added, calcination at a high temperature of 400° C. is required to achieve a better deamination effect.

[0025] Comparative Example 2 (1) The electrolytic manganese slag is crushed, ground and sieved to 100-120 mesh, and the moisture content of the manganese slag is 15%; (2) mixing and stirring the sieved electrolytic manganese slag and calcium hydroxide in a mass ratio of 9:1; (3) calcining the mixture in a tube furnace at 300°C for 20 min; (4) Leaching electrolytic manganese slag according to the "Horizontal Oscillation Method for Leaching Toxicity of Solid Waste" (HJ557-2010); (5) Determine the ammonia nitrogen concentration of the leaching solution according to the "Determination of Ammonia Nitrogen in Water - Nessler's Reagent Spectrophotometric Method" (HJ535-2009); (6) The ammonia nitrogen removal rate of the treated electrolytic manganese slag after low-temperature roasting reached 93.8%.

[0026] This comparative example shows that calcium hydroxide alone is used as a deammoniation agent and needs to be calcined at a high temperature of 300° C. to achieve a better deammoniation effect.

[0027] Comparative Example 3 (1) The electrolytic manganese slag is crushed, ground and sieved to 100-120 mesh, and the moisture content of the manganese slag is 15%; (2) mixing calcium oxide and calcium hydroxide in a mass ratio of 9:1 to prepare a composite deammoniation agent; (3) The sieved electrolytic manganese slag and the composite deammoniation agent are mixed and stirred in a mass ratio of 8:2; (4) calcining the mixture in a tube furnace at 150°C for 30 min; (5) Leaching electrolytic manganese slag according to the "Horizontal Oscillation Method for Leaching Toxicity of Solid Waste" (HJ557-2010); (6) Determine the ammonia nitrogen concentration of the leaching solution according to the "Determination of Ammonia Nitrogen in Water - Nessler's Reagent Spectrophotometric Method" (HJ535-2009); (7) The ammonia nitrogen removal rate of the treated electrolytic manganese slag after low-temperature roasting reaches 93.3%.

[0028] Compared with Example 1, only calcium oxide and calcium hydroxide are used as the composite deamination agent. Under the same roasting temperature and conditions, even if the deamination time is extended, the deamination effect is still relatively poor.

[0029] Comparative Example 4 (1) The electrolytic manganese slag is crushed, ground and sieved to 100-120 mesh, and the moisture content of the manganese slag is 15%; (2) Calcium oxide and calcium hydroxide are mixed in a mass ratio of 9:1, and 1% sodium hydroxide is added to prepare a composite deammoniation agent; (3) The sieved electrolytic manganese slag and the composite deammoniation agent are mixed and stirred in a mass ratio of 8:2; (4) calcining the mixture in a tube furnace at 150°C for 30 min; (5) Leaching electrolytic manganese slag according to the "Horizontal Oscillation Method for Leaching Toxicity of Solid Waste" (HJ557-2010); (6) Determine the ammonia nitrogen concentration of the leaching solution according to the "Determination of Ammonia Nitrogen in Water - Nessler's Reagent Spectrophotometric Method" (HJ535-2009); (7) The ammonia nitrogen removal rate of the treated electrolytic manganese slag after low-temperature roasting reaches 95.4%.

[0030] Compared with Example 1, the composite deamination agent does not introduce activated carbon, and the deamination effect is relatively poor.

[0031] Comparative Example 5 (1) The electrolytic manganese slag is crushed, ground and sieved to 100-120 mesh, and the moisture content of the manganese slag is 15%; (2) Calcium oxide and calcium hydroxide are mixed in a mass ratio of 9:1, and 1% activated carbon is added to prepare a composite deammoniation agent; (3) The sieved electrolytic manganese slag and the composite deammoniation agent are mixed and stirred in a mass ratio of 8:2; (4) calcining the mixture in a tube furnace at 150°C for 30 min; (5) Leaching electrolytic manganese slag according to the "Horizontal Oscillation Method for Leaching Toxicity of Solid Waste" (HJ557-2010); (6) Determine the ammonia nitrogen concentration of the leaching solution according to the "Determination of Ammonia Nitrogen in Water - Nessler's Reagent Spectrophotometric Method" (HJ535-2009); (7) The ammonia nitrogen removal rate of the treated electrolytic manganese slag after low-temperature roasting reaches 94.0%.

[0032] Compared with Example 1, the composite deamination agent does not introduce sodium hydroxide, and the deamination effect is relatively poor.

[0033] By comparing the comparative example of the present invention with the embodiment, it is obvious that, on the basis of the mass ratio of calcium oxide and calcium hydroxide, an appropriate amount of sodium hydroxide and activated carbon are added to carry out low-temperature roasting and deammoniation of electrolytic manganese slag, which can effectively remove ammonia nitrogen while lowering the temperature. Adding an appropriate amount of activated carbon can effectively reduce the decomposition temperature of sulfate, effectively reduce energy consumption, simplify the process operation, and have higher added value and lower cost.

[0034] The above embodiments should be understood as being merely used to illustrate the present invention in more detail and specifically, and should not be understood as limiting the present invention in any form. Although some materials and operating methods used to implement the present invention are well known in the art, the present invention is still described as detailed as possible herein. In the context, unless otherwise specified, the materials and operating methods used in the present invention are well known in the art.

Claims

1. A method for removing ammonia nitrogen by low temperature roasting of electrolytic manganese slag, characterized in that: The electrolytic manganese slag is crushed and ground to obtain electrolytic manganese slag powder, and the electrolytic manganese slag powder is mixed with a composite deamination agent and then roasted; the composite deamination agent is composed of calcium oxide, calcium hydroxide, sodium hydroxide and activated carbon.

2. The method for removing ammonia nitrogen by low temperature roasting of electrolytic manganese slag according to claim 1, characterized in that: The composite deammoniation agent comprises calcium oxide and calcium hydroxide in a mass percentage of 80-90%:10-20%, the mass of sodium hydroxide is 0.5-1.5% of the total mass of calcium oxide and calcium hydroxide, and the mass of activated carbon is 0.5-1.5% of the total mass of calcium oxide and calcium hydroxide.

3. A method for removing ammonia nitrogen by low temperature roasting of electrolytic manganese slag according to claim 1 or 2, characterized in that: The mass ratio of the composite deammoniation agent to the electrolytic manganese slag is 2-4:6-8.

4. The method for removing ammonia nitrogen by low temperature roasting of electrolytic manganese slag according to claim 1 or 2, characterized in that: The calcination conditions are as follows: temperature of 130-180° C. and time of 10-30 min.

5. The method for removing ammonia nitrogen by low temperature roasting of electrolytic manganese slag according to claim 1, characterized in that: The electrolytic manganese slag is crushed and ground to 100-120 meshes.

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