A method for treating electrolytic manganese slag solidified by medium temperature roasting

Abstract

The invention discloses a method for treating electrolytic manganese slag by medium-temperature roasting and solidification, and belongs to the technical field of solid waste treatment. The method comprises crushing the electrolytic manganese slag raw material, mixing it with calcium silicate and barium chloride by ball milling, obtaining a mixed material, and calcining the mixed material at a temperature of 750 to 1000°C to obtain solidified electrolytic manganese slag. The method can efficiently fix the heavy metal ions in the electrolytic manganese slag, and the heavy metal ion leaching concentration of the solidified electrolytic manganese slag is lower than the national limit standard, thereby preventing secondary pollution. The method has a short process flow, simple operation, low additive dosage, low cost, and can be widely promoted and applied.

Description

Technical Field

[0001] The present invention specifically relates to a solidification treatment method for electrolytic manganese slag, in particular to a treatment method for solidifying electrolytic manganese slag by medium-temperature roasting, and belongs to the technical field of solid waste treatment. Background Art

[0002] As a vital material, electrolytic manganese is widely used in the fields of steel manufacturing and metal alloy production. In the process of producing electrolytic manganese, a large amount of acidic waste slag, namely electrolytic manganese slag, is produced after manganese ore is leached with sulfuric acid. Generally speaking, for every ton of electrolytic manganese produced, 10 to 12 tons of electrolytic manganese slag will be produced. Electrolytic manganese slag contains a large amount of soluble manganese, ammonia nitrogen, heavy metal ions and other pollutants. At present, the disposal and utilization of electrolytic manganese slag in China is still in the application research stage. The research on its basic properties, especially from the perspective of comprehensive application, is still lagging behind. Industrial application cases are scarce, and the main treatment method is still slag storage. However, long-term weathering and rainwater leaching will cause the stored electrolytic manganese slag to release harmful substances such as ammonia nitrogen and heavy metals, which are easily migrated and released into the surrounding soil and surface and groundwater, posing a serious threat to the local environment and residents' health. Therefore, in order to achieve the safe storage of electrolytic manganese slag, it must be harmlessly treated.

[0003] At present, solidification / stabilization technology is the main technical means to achieve harmless treatment of electrolytic manganese slag. There are related patent technologies for the solidification treatment of electrolytic manganese slag: for example, the prior art (publication number: CN118702471A) discloses a method for solidifying manganese slag and a method for preventing seepage of manganese slag storage. This method uses one or more of mineral powder, cement clinker, calcium carbide slag, metakaolin, sodium silicate and coal gangue as modified materials to solidify and modify manganese slag, which can effectively fix heavy metal elements such as ammonia nitrogen, manganese, zinc, and copper in manganese slag and reduce its permeability. A Chinese patent (publication number: CN108246777A) discloses a method for solidification treatment of electrolytic manganese slag, which uses ferroferric oxide and composite phosphate solution as curing agents to achieve the solidification of electrolytic manganese slag. The above two electrolytic manganese slag curing technologies require additional doping of a large amount of curing agent, which not only increases the volume of the cured product, resulting in high storage costs, but also significantly increases the cost of the reagent. A Chinese patent (publication number: CN112279508A) discloses a method for producing microcrystalline glass by harmlessly treating electrolytic manganese slag. This method calcines the electrolytic manganese slag to 1100°C, allowing heavy metal trace elements to enter the mineral lattice and achieve harmlessness of heavy metals. However, its high calcination temperature results in high energy consumption in the treatment process. Summary of the invention

[0004] In view of the technical defects existing in the prior art, the object of the present invention is to provide a treatment method for medium-temperature roasting and solidifying electrolytic manganese slag. By adding a small amount of additives, the method can realize the solidification and stabilization of the electrolytic manganese slag at a relatively low temperature. The toxic leaching result of the solidified body reaches the first-level emission standard in the "National Integrated Sewage Discharge Standard" (GB 8978-1996), and at the same time meets the standard limit values ​​in the "Technical Specifications for Pollution Control of Manganese Slag" (HJ 1241-2022) and the "Technical Specifications for Co-treatment of Solid Waste in Cement Kilns" (GB 30760-2024). In addition, the method has low energy consumption and low cost of external agents, which meets the requirements of large-scale industrial promotion and application.

[0005] In order to achieve the above technical purpose, the present invention provides a method for treating electrolytic manganese slag by medium-temperature roasting and solidification. The method comprises the following steps: crushing the electrolytic manganese slag raw material, mixing it with calcium silicate and barium chloride by ball milling to obtain a mixed material, and calcining the mixed material at a temperature of 750-1000°C to obtain solidified electrolytic manganese slag.

[0006] The medium temperature roasting involved in the present invention refers to roasting at a temperature of 750-1000°C.

[0007] The key to the curing treatment of electrolytic manganese slag by the present invention is to add a calcium silicate and barium chloride combination agent to the electrolytic manganese slag, which can not only promote the physical phase reconstruction of the electrolytic manganese slag at a lower temperature to achieve medium and low temperature curing, but also effectively improve the stabilization efficiency of heavy metals. More specifically, calcium silicate can produce active silicon dioxide and calcium oxide by pyrolysis during high-temperature calcination, which can effectively activate the electrolytic manganese slag, and react chemically with the components in the electrolytic manganese slag to form glassy and crystalline products, so that the heavy metal ions in the electrolytic manganese slag can be incorporated into the amorphous network structure and the crystal structure, and the heavy metal ions can be stably fixed in the solid phase through substitution and encapsulation, thereby effectively reducing the migration of heavy metals and the risk of environmental pollution, and during the high-temperature calcination process, barium chloride changes the viscosity of the intermediate phase at high temperature by participating in chemical reactions to promote crystal growth, reduce the calcination temperature and shorten the calcination time, thereby not only improving the calcination efficiency, but also further optimizing the fixing effect of the crystalline structure on heavy metal ions. In summary, through the synergistic effect of calcium silicate and barium chloride, not only the medium-temperature solidification of electrolytic manganese slag is achieved, but also the efficient fixation of heavy metals in the electrolytic manganese slag is achieved, so as to achieve the purpose of harmless treatment of electrolytic manganese slag, while reducing energy consumption and reagent costs.

[0008] As a preferred solution, the mass of the calcium silicate is 0.75% to 4.5% of the mass of the electrolytic manganese slag. The amount of calcium silicate added relative to the electrolytic manganese slag has a significant effect on the curing effect of the electrolytic manganese slag. With the increase in the amount of calcium silicate added, the curing effect of the electrolytic manganese slag shows a trend of first strengthening and then weakening. When the mass percentage of calcium silicate relative to the electrolytic manganese slag is 1.5% and 2.25%, the curing effect is similar and reaches the best. Therefore, adding an appropriate amount of calcium silicate can significantly improve the curing effect, while excessive addition will have an adverse effect on the curing effect. The mass of the calcium silicate is further preferably 1.5% to 2.25% of the mass of the electrolytic manganese slag.

[0009] As a preferred solution, the mass of the barium chloride is 0.75% to 4.5% of the mass of the electrolytic manganese slag. The amount of barium chloride added relative to the electrolytic manganese slag also has a significant effect on the curing effect of the electrolytic manganese slag. With the gradual increase in the amount of barium chloride added, the curing performance of the electrolytic manganese slag first shows an enhanced trend, then enters a relatively stable plateau period, and finally gradually weakens. In particular, when the mass percentage of barium chloride relative to the electrolytic manganese slag is 0.75%, 1.5% or 3.0%, the curing performance reaches a similar optimal level. Therefore, reasonable control of the amount of barium chloride added can significantly improve the curing effect, however, once this suitable range is exceeded, excessive addition will cause the curing performance to decrease. The mass of the barium chloride is further preferably 1.5% to 3.0% of the mass of the electrolytic manganese slag.

[0010] As a preferred solution, the ball milling mixing conditions are: the ball milling speed is 150-300 r / min, and the ball milling time is 5-15 min. Ball milling mixing can not only achieve the refinement of raw material particles, but also improve the reactivity of the raw materials, which is beneficial to the subsequent high-temperature solid phase reaction process.

[0011] As a preferred solution, the calcination conditions are: calcination temperature is 800~950℃, and calcination time is 1~4h. As the calcination temperature increases, it helps to stabilize the heavy metals in the electrolytic manganese slag. When the calcination temperature reaches above 800℃, the toxic leaching results of the electrolytic manganese slag solid body are completely lower than the national standard. This is because the glassy and crystalline products produced by calcination can embed metal ions into the amorphous network and crystal structure, thereby achieving effective fixation of heavy metals, but the temperature is too high, and the energy consumption increases significantly, resulting in an increase in the cost of electrolytic manganese slag treatment. And as the calcination time increases, the solidification effect gradually increases and then tends to stabilize. This shows that after calcination for 2 hours, the heavy metals have been fixed in the electrolytic manganese slag in a stable form. Therefore, the further preferred calcination time is 2~2.5 hours.

[0012] Compared with the prior art, the technical solution of the present invention has the following beneficial technical effects:

[0013] (1) The present invention can achieve efficient fixation of heavy metal ions in electrolytic manganese slag.

[0014] (2) The present invention uses calcium silicate and barium chloride as additives. Under the premise of ensuring the harmless treatment of electrolytic manganese slag, the reaction raw materials are added at one time, which reduces the amount of additives used, greatly reduces the curing and roasting temperature, reduces energy consumption, reduces the cost of electrolytic manganese slag curing treatment, simplifies the process flow, and is conducive to industrial production.

[0015] (3) The electrolytic manganese slag treated by the present invention is not only harmlessly treated, but also has good material properties and can be further used as a building material, effectively broadening the resource utilization path of the electrolytic manganese slag. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The manganese leaching effect of solidified electrolytic manganese slag at different dosages when calcium silicate, barium chloride, calcium chloride or calcium oxide is used as additive.

[0017] Figure 2 The manganese leaching effect of solidified electrolytic manganese slag when calcium silicate and calcium oxide are used as additives at different dosages.

[0018] Figure 3 The manganese leaching effect of solidified electrolytic manganese slag when calcium silicate and barium chloride are used as additives at different dosages. DETAILED DESCRIPTION

[0019] The following examples are intended to further illustrate the present invention in detail, but are not intended to limit the scope of protection of the claims of the present invention.

[0020] The heavy metal leaching of electrolytic manganese slag and solidified electrolytic manganese slag involved in the following embodiments refers to the leaching method in "Solid Waste Leaching Toxicity Leaching Method Sulfuric Acid and Nitric Acid Method" (HJ / T 299-2007).

[0021] The electrolytic manganese slag (EMR) used in the following examples is waste slag separated from manganese carbonate ore by sulfuric acid leaching, which is composed of excessive manganese dioxide introduced during purification and anode mud during electrolysis and is piled up in a slag yard for a long time.

[0022] The element composition of the electrolytic manganese slag was analyzed by X-ray fluorescence spectrometer. The original electrolytic manganese slag contained relatively high amounts of silicon, aluminum, iron, calcium, manganese and a large amount of sulfur. The results are shown in Table 1.

[0023]

[0024] The manganese ion concentration of the electrolytic manganese slag leached is 1877.6 mg / L.

[0025] Condition optimization experiment 1:

[0026] S1: crushing the bulk electrolytic manganese slag raw material to obtain electrolytic manganese slag particles with uniform particle size;

[0027] S2: 5g of electrolytic manganese slag particles and an appropriate amount of additives, the additives are selected from calcium silicate, barium chloride, calcium oxide or calcium oxide, put into a ball mill, set the speed to 200r / min, the time is 10min, and mix them thoroughly to obtain a mixed material;

[0028] S3: The mixed material is placed in a muffle furnace for calcination, the set temperature is 800° C., the calcination time is 2 h, and after natural cooling, a solidified electrolytic manganese slag is obtained.

[0029] The manganese leaching concentration of the solidified electrolytic manganese slag obtained with different additive amounts is as follows: Figure 1 As shown. Figure 1 It can be seen that the use of single calcium silicate, barium chloride, calcium oxide or calcium oxide as additives is not ideal for the solidification of electrolytic manganese slag. The leaching method refers to the "Solid Waste Leaching Toxicity Leaching Method Sulfuric Acid and Nitric Acid Method" (HJ / T 299-2007).

[0030] Condition optimization experiment 2

[0031] S1: crushing the bulk electrolytic manganese slag raw material to obtain electrolytic manganese slag particles with uniform particle size;

[0032] S2: 5g of electrolytic manganese slag particles and appropriate amounts of calcium silicate and calcium oxide combined additives (a total of 10 groups of combined additives were set as controls, and the mass percentages of calcium silicate and calcium oxide relative to the electrolytic manganese slag were: Group 1: 0% + 0%, Group 2: 1.5% + 1.5%, Group 3: 1.5% + 3.0%, Group 4: 1.5% + 4.5%, Group 5: 3.0% + 1.5%, Group 6: 3.0% + 3.0%, Group 7: 3.0% + 4.5%, Group 8: 4.5% + 1.5%, Group 9: 4.5% + 3.0%, Group 10: 4.5% + 4.5%), put into a ball mill, set the speed to 200r / min, the time to 10min, make it fully mixed to obtain a mixed material;

[0033] S3: The mixed material is placed in a muffle furnace for calcination, the set temperature is 800° C., the calcination time is 2 h, and after natural cooling, a solidified electrolytic manganese slag is obtained.

[0034] The manganese leaching concentration of the solidified electrolytic manganese slag obtained by combining additives of calcium silicate and calcium oxide with different dosages is as follows: Figure 2 As shown. Figure 2 It can be seen that the use of calcium silicate and calcium oxide as a combined additive has a poor solidification effect on electrolytic manganese slag and poor stability.

[0035] Condition optimization experiment 3

[0036] S1: crushing the bulk electrolytic manganese slag raw material to obtain electrolytic manganese slag particles with uniform particle size;

[0037] S2: 5g of electrolytic manganese slag particles were mixed with appropriate amounts of calcium silicate and barium chloride combined additives (a total of 18 groups of combined additives were set as controls, and the mass percentages of calcium silicate and barium chloride relative to the electrolytic manganese slag were: Group 1: 0% + 0.75%; Group 2: 0.75% + 0.75%; Group 3: 1.5% + 0.75%; Group 4: 2.25% + 0.75%; 5 groups: 3.0%+0.75%; 6 groups: 4.5%+0.75%; 7 groups: 0%+1.5%; 8 groups: 0.75%+1.5%; 9 groups: 1.5%+1.5%; 10 groups: 2.25%+1.5%; 11 groups: 3.0%+1.5%; 12 groups: 4.5%+1.5%; 13 groups: 0%+3.0%; 14 groups: 0.75%+3.0%; 15 groups: 1.5%+3.0%; 16 groups: 2.25%+3.0%; 17 groups: 3.0%+3.0%; 18 groups: 4.5%+3.0%), put into a ball mill, set the speed to 200r / min, the time to 10min, make it fully mixed to obtain a mixed material;

[0038] S3: The mixed material is placed in a muffle furnace for calcination, the set temperature is 800° C., the calcination time is 2 h, and after natural cooling, a solidified electrolytic manganese slag is obtained.

[0039] The manganese leaching concentration of the solidified electrolytic manganese slag obtained by combining additives of calcium silicate and barium chloride with different dosages is as follows: Figure 3 As shown. Figure 3 It can be seen that the use of calcium silicate and calcium chloride as a combined additive has a better solidification effect on the electrolytic manganese slag, which is significantly better than single calcium silicate, barium chloride, calcium chloride or calcium oxide as an additive, and is also better than the combined additive of calcium silicate and calcium oxide. In particular, when the addition amount of calcium silicate is 1.5~2.25% of the mass of the electrolytic manganese slag and the addition amount of barium chloride is 1.5~3.0% of the mass of the electrolytic manganese slag, the solidification effect of the electrolytic manganese slag is the best.

[0040] Here are some specific embodiments with better effects:

[0041] Example 1

[0042] S1: crushing the bulk electrolytic manganese slag raw material to obtain electrolytic manganese slag particles with uniform particle size;

[0043] S2: 5 g of electrolytic manganese slag particles, 0.075 g of calcium silicate and 0.075 g of barium chloride (the mass percentages of calcium silicate and barium chloride relative to the electrolytic manganese slag are 1.5% and 1.5%, respectively) are put into a ball mill, the speed is set to 200 r / min, the time is 10 min, and the mixture is fully mixed to obtain a mixed material;

[0044] S3: The mixed material is placed in a muffle furnace for calcination, the temperature is set to 800° C., the calcination time is 2 h, and solidified electrolytic manganese slag is obtained after natural cooling.

[0045] Example 2

[0046] S1: crushing the bulk electrolytic manganese slag raw material to obtain electrolytic manganese slag particles with uniform particle size;

[0047] S2: 5 g of electrolytic manganese slag particles, 0.1125 g of calcium silicate and 0.075 g of barium chloride (the mass percentages of calcium silicate and barium chloride relative to the electrolytic manganese slag are 2.25% and 1.5%, respectively) are put into a ball mill, the speed is set to 200 r / min, the time is 10 min, and the mixture is fully mixed to obtain a mixed material;

[0048] S3: The mixed material is placed in a muffle furnace for calcination, the temperature is set to 800° C., the calcination time is 2 h, and solidified electrolytic manganese slag is obtained after natural cooling.

[0049] Example 3

[0050] S1: crushing the bulk electrolytic manganese slag raw material to obtain electrolytic manganese slag particles with uniform particle size;

[0051] S2: 5 g of electrolytic manganese slag particles, 0.075 g of calcium silicate and 0.075 g of barium chloride (the mass percentages of calcium silicate and barium chloride relative to the electrolytic manganese slag are 1.5% and 1.5%, respectively) are put into a ball mill, the speed is set to 200 r / min, the time is 10 min, and the mixture is fully mixed to obtain a mixed material;

[0052] S3: The mixed material is placed in a muffle furnace for calcination, the temperature is set to 950° C., the calcination time is 2 h, and solidified electrolytic manganese slag is obtained after natural cooling.

[0053] Example 4

[0054] S1: crushing the bulk electrolytic manganese slag raw material to obtain electrolytic manganese slag particles with uniform particle size;

[0055] S2: 5 g of electrolytic manganese slag particles, 0.075 g of calcium silicate and 0.075 g of barium chloride (the mass percentages of calcium silicate and barium chloride relative to the electrolytic manganese slag are 1.5% and 1.5%, respectively) are put into a ball mill, the speed is set to 200 r / min, the time is 10 min, and the mixture is fully mixed to obtain a mixed material;

[0056] S3: The mixed material is placed in a muffle furnace for calcination, the temperature is set to 800° C., the calcination time is 3 hours, and the solidified electrolytic manganese slag is obtained after natural cooling.

[0057] In Examples 1 to 4, the solidified electrolytic manganese slag was leached by the "Solid Waste Leaching Toxicity Leaching Method Sulfuric Acid and Nitric Acid Method" (HJ / T 299-2007), and the toxic leaching results (as shown in Table 2) were all lower than the first-level emission standard in the "National Integrated Sewage Discharge Standard" (GB 8978-1996). The heavy metal leaching results of Examples 1 and 2 can also reach the standard limits in the "Technical Specifications for Pollution Control of Manganese Slag" (HJ 1241-2022) and the "Technical Specifications for Co-treatment of Solid Wastes in Cement Kilns" (GB 30760-2024), indicating that the solidification method provided by the present invention has a good solidification effect on electrolytic manganese slag.

[0058]

[0059] Note: ND means below the detection limit of the method.

[0060] Comparative Example 1

[0061] S1: crushing the bulk electrolytic manganese slag raw material to obtain electrolytic manganese slag particles with uniform particle size;

[0062] S2: 5 g of electrolytic manganese slag particles, 0.075 g of calcium silicate and 0.075 g of barium chloride (the mass percentages of calcium silicate and barium chloride relative to the electrolytic manganese slag are 1.5% and 1.5%, respectively) are put into a ball mill, the speed is set to 200 r / min, the time is 10 min, and the mixture is fully mixed to obtain a mixed material;

[0063] S3: The mixed material is placed in a muffle furnace for calcination, the temperature is set to 700° C., the calcination time is 2 h, and the solidified electrolytic manganese slag is obtained after natural cooling.

[0064]

[0065] Note: ND means below the detection limit of the method.

[0066] It can be seen from Table 3 that if the roasting temperature is too low, the manganese in the electrolytic manganese slag cannot be effectively fixed, and the manganese leaching concentration of the obtained solidified electrolytic manganese slag is too high, which cannot meet the first-level emission standards in the "National Integrated Wastewater Discharge Standard" (GB 8978-1996), let alone the "Technical Specifications for Manganese Slag Pollution Control" (HJ 1241-2022) and the standard limits in the "Technical Specifications for Co-treatment of Solid Waste in Cement Kilns" (GB 30760-2024).

[0067] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for treating electrolytic manganese slag by medium temperature roasting and solidification, characterized in that: The electrolytic manganese slag raw material is crushed and then ball-milled with calcium silicate and barium chloride to obtain a mixed material, and the mixed material is calcined at a temperature of 750-1000° C. to obtain solidified electrolytic manganese slag; the mass of the calcium silicate is 0.75%-4.5% of the mass of the electrolytic manganese slag; the mass of the barium chloride is 0.75%-4.5% of the mass of the electrolytic manganese slag.

2. The method for treating electrolytic manganese slag solidified by medium temperature roasting according to claim 1, characterized in that: The ball milling mixing conditions are: the ball milling speed is 150-300 r / min, and the ball milling time is 5-15 min.

3. The method for treating the medium-temperature calcined and solidified electrolytic manganese slag according to claim 1, characterized in that: The calcination conditions are as follows: the calcination temperature is 800-950° C. and the calcination time is 1-4 h.

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