Method for comprehensive utilization of sintering machine head dust and steelmaking refining dust

Abstract

The present application relates to metallurgical solid waste resource utilization technical field, disclose a kind of comprehensive utilization method of sintering machine head ash and steelmaking refining ash.The method provided in the present application, sintering machine head ash and steelmaking refining ash are treated using water washing process, while harmful impurities in the two ash fractions are immersed in aqueous solution and chemical reaction occurs, also through the reaction mechanism of ammonium sulfide solution under oxygen condition to generate sulfur and ammonia water, resources such as sulfur and ammonia water are recovered, effectively avoiding the release of toxic and harmful gases such as H2S and NH3, and the generation of NH4Cl in the recycling process of sintering machine head ash, the whole utilization process has no secondary pollution, realizes the maximum value utilization of metallurgical solid waste ash fraction.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metallurgical solid waste resource utilization, and particularly relates to a comprehensive utilization method of sintering machine head ash and steelmaking refining ash. BACKGROUND

[0002] As metallurgical solid waste, the steelmaking refining ash is often used to replace part of the flux to return to sintering due to its high calcium and magnesium content. One of the most common operations in the steelmaking refining process is desulfurization and denitrification, which requires the addition of a large amount of calcium and magnesium-based flux to form slag, producing desulfurization and denitrification products CaS and Mg3N2. After the reaction is completed, these products are extracted into the ash bin along with very fine flux powder by the dust removal system, and are an important component of the steelmaking refining ash. Therefore, the steelmaking refining ash contains CaS and Mg3N2, which will release toxic and harmful gases such as H2S and NH3 when coming into contact with water, not only polluting the environment, but also causing great harm to the health of the on-site personnel in the sintering process. Therefore, the steelmaking refining ash cannot be directly used for sintering, and must be pretreated before sintering to remove CaS and Mg3N2.

[0003] The main component of the sintering machine head ash is iron oxide, and it also contains harmful elements such as Zn, K, Na, and Cl. Some steel plants use a water washing process to remove chlorine and salt, and the sintering machine head ash is recycled after being washed with water. The water washing liquid is step crystallized to prepare high-purity chlorine salt. However, the sintering machine head ash contains nitrides such as Mg3N, and the ammonia gas generated during the water washing process cannot be completely removed in the purification and impurity removal section, which not only affects the purity of the subsequent products, but also seriously affects the service life of the equipment due to the generation of NH4Cl. SUMMARY

[0004] Therefore, the present application provides a comprehensive utilization method of sintering machine head ash and steelmaking refining ash to solve the problems of the generation of toxic and harmful gases during the reuse of steelmaking refining ash and the generation of NH4Cl during the reuse of sintering machine head ash in the related art.

[0005] In a first aspect, the present application provides a comprehensive utilization method of sintering machine head ash and steelmaking refining ash, comprising the following steps:

[0006] The sintering machine head ash is contacted with water for a first effective time, and the obtained slurry is subjected to primary solid-liquid separation to obtain first water washing residue and first water washing liquid;

[0007] The steelmaking refining ash is contacted with the first water washing liquid for a second effective time, and the obtained slurry is subjected to secondary solid-liquid separation to obtain second water washing residue and second water washing liquid;

[0008] The second water washing liquid is subjected to aeration treatment to obtain an aeration suspension liquid;

[0009] The aeration suspension is subjected to three solid-liquid separation to obtain a suspension and a recovery liquid.

[0010] In the comprehensive utilization method of sintering machine head ash and steelmaking refining ash provided by the application, first, the sintering machine head ash is contacted with water to wash the sintering machine head ash, and the ammonia component in the sintering machine head ash is washed out into a first washing liquid; then, the steelmaking refining ash is contacted with the first washing liquid, so that the H2S and NH3 contained in the steelmaking refining ash are dissolved in water and chemically react with the higher concentration of ammonium ions in the first washing liquid to generate ammonium sulfide (not ammonium bisulfide); and then, the second aqueous solution containing ammonium sulfide is subjected to aeration treatment to obtain a byproduct sulfur (suspension) and an ammonia-containing recovery liquid.

[0011] Therefore, in the above method provided by the application, the sintering machine head ash and the steelmaking refining ash are treated by the water washing process, which not only immerses the harmful impurities in the two ash fractions in the aqueous solution and causes chemical reactions, but also recovers sulfur, ammonia water and other resources through the reaction mechanism of the generation of sulfur and ammonia water under the condition of oxygen addition in the ammonium sulfide solution, effectively avoids the release of toxic and harmful gases such as H2S and NH3, and the generation of NH4Cl in the recycling process of the sintering machine head ash, and the whole utilization process does not cause any secondary pollution, and realizes the maximum value utilization of metallurgical solid waste ash.

[0012] In an alternative embodiment, the comprehensive utilization method further comprises:

[0013] determining the ammonia concentration in the recovery liquid;

[0014] in the case where the ammonia concentration in the recovery liquid is less than a preset value, mixing the recovery liquid with the first washing liquid in the next cycle process, and contacting the obtained mixed liquid with the steelmaking refining ash until the ammonia concentration in the recovery liquid is not less than the preset value;

[0015] and / or, in the case where the ammonia concentration in the recovery liquid is not less than the preset value, passing the recovery liquid through an ion exchange resin to obtain an ammonia water solution and a high-salt solution.

[0016] In the above method provided by the application, in the case where the ammonia concentration in the recovery liquid is less than a preset value, the recovery liquid is used together with the first washing liquid for the water washing of the steelmaking refining ash in the next cycle process, which can significantly improve the ammonia concentration in the solution and is more conducive to the generation of ammonium sulfide; in the case where the ammonia concentration in the recovery liquid is not less than the preset value, the recovery liquid is separated into an ammonia water solution and a high-salt solution, which maximizes the recycling of resources.

[0017] In an alternative embodiment, the preset value is any value in the range of 3% to 5%.

[0018] In one optional implementation, the comprehensive utilization method further includes:

[0019] The high-salt solution is evaporated to extract salt, in order to prepare high-purity KCl and / or NaCl;

[0020] And / or, the ammonia solution may be used for cooling and / or desulfurization and denitrification of the sintering flue.

[0021] In one optional implementation, the first effective duration of contacting the sintering machine head ash with water includes:

[0022] The sintering machine head ash is mixed with water and stirred evenly at a speed of 5 r / min to 15 r / min, and then left to stand for 0.5 h to 1.0 h.

[0023] Optionally, the weight ratio of water to the sintering machine head ash is (3-6):1.

[0024] In an optional embodiment, the second effective duration of contacting the steelmaking refining ash with the first washing liquid includes:

[0025] Mix the steelmaking refining ash with the first washing liquid and let it stand for 2 to 5 hours.

[0026] Optionally, the weight ratio of the first washing liquid to the steelmaking refining ash is (6-10):1.

[0027] In one optional embodiment, the aeration treatment of the second washing liquid includes:

[0028] Air is introduced into the second washing solution at a flow rate of 60 L / min to 300 L / min.

[0029] In one optional implementation, the comprehensive utilization method further includes:

[0030] The first water-washed residue and / or the second water-washed residue are dehydrated, and the dehydrated product is returned to sintering to recover valuable elements in the sintering head ash and / or the steelmaking refining ash.

[0031] Optionally, the moisture content of the dehydrated product is not higher than 20%.

[0032] In one optional embodiment, the nitrogen content in the sintering machine head ash is not less than 1 wt%, based on the total weight of the sintering machine head ash.

[0033] In one optional implementation, the comprehensive utilization method further includes:

[0034] The suspension was dried to obtain sulfur. Detailed Implementation

[0035] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0036] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0037] To address the problems existing in the aforementioned related technologies, according to a first aspect of the present invention, a method for the comprehensive utilization of sintering mill head ash and steelmaking refining ash is provided, comprising the following steps:

[0038] The sintering machine head ash is brought into contact with water for a first effective time, and the resulting slurry is subjected to a first solid-liquid separation to obtain the first water-washed residue and the first water-washed liquid.

[0039] The steelmaking refining ash is contacted with the first washing liquid for a second effective time, and the resulting slurry is subjected to a second solid-liquid separation to obtain the second washing residue and the second washing liquid.

[0040] The second washing solution is aerated to obtain an aerated suspension;

[0041] The aerated suspension was subjected to three solid-liquid separations to obtain the suspension and the recovered liquid.

[0042] In the comprehensive utilization method of sintering machine head ash and steelmaking refining ash provided by the present invention, firstly, the sintering machine head ash is contacted with water to wash it, and the ammonia component in the sintering machine head ash is washed into the first washing solution; then, the steelmaking refining ash is contacted with the first washing solution, so that the H2S and NH3 contained in the steelmaking refining ash dissolve in the water and react chemically with the higher concentration of ammonium ions in the first washing solution to generate ammonium sulfide (not ammonium hydrogen sulfide); then, the second aqueous solution containing ammonium sulfide is aerated to obtain byproduct sulfur (suspension) and ammonia-containing recovery liquid.

[0043] Therefore, in the method provided by this invention, the sintering machine head ash and steelmaking refining ash are treated by water washing. While the harmful impurities in the two types of ash are immersed in the aqueous solution and undergo a chemical reaction, sulfur and ammonia water are also recovered through the reaction mechanism of ammonium sulfide solution generating sulfur and ammonia water under oxygenated conditions. This effectively avoids the release of toxic and harmful gases such as H2S and NH3, as well as the generation of NH4Cl during the reuse of sintering machine head ash. The entire utilization process is free of any secondary pollution, realizing the maximum value utilization of metallurgical solid waste ash.

[0044] In one optional implementation, the comprehensive utilization method further includes:

[0045] Determine the ammonia concentration in the recovered liquid;

[0046] If the ammonia concentration in the recovered liquid is less than a preset value, the recovered liquid is mixed with the first washing liquid in the next cycle, and the resulting mixture is contacted with the steelmaking refining ash until the ammonia concentration in the recovered liquid is not less than the preset value.

[0047] And / or, if the ammonia concentration in the recovered liquid is not less than the preset value, the recovered liquid is passed through an ion exchange resin to obtain an ammonia aqueous solution and a high-salt solution.

[0048] In the method provided by the present invention, when the ammonia concentration in the recovered liquid is less than a preset value, the recovered liquid is used together with the first washing liquid in the next cycle for washing the steelmaking refining ash. This can significantly increase the ammonia concentration in the solution, which is more conducive to the formation of ammonium sulfide. When the ammonia concentration in the recovered liquid is not less than the preset value, the recovered liquid is separated into an ammonia solution and a high-salt solution, thereby maximizing the recycling of resources.

[0049] In one optional implementation, the preset value is any value between 3% and 5%.

[0050] In one optional implementation, the comprehensive utilization method further includes:

[0051] The high-salt solution is evaporated to extract salt, in order to prepare high-purity KCl and / or NaCl;

[0052] And / or, the ammonia solution may be used for cooling and / or desulfurization and denitrification of the sintering flue.

[0053] In one optional implementation, the first effective duration of contacting the sintering machine head ash with water includes:

[0054] The sintering machine head ash is mixed with water and stirred evenly at a speed of 5 r / min to 15 r / min, and then left to stand for 0.5 h to 1.0 h.

[0055] Optionally, the weight ratio of water to the sintering machine head ash is (3-6):1.

[0056] In an optional embodiment, the second effective duration of contacting the steelmaking refining ash with the first washing liquid includes:

[0057] Mix the steelmaking refining ash with the first washing liquid and let it stand for 2 to 5 hours.

[0058] Optionally, the weight ratio of the first washing liquid to the steelmaking refining ash is (6-10):1.

[0059] In one optional embodiment, the aeration treatment of the second washing liquid includes:

[0060] Air is introduced into the second washing solution at a flow rate of 60 L / min to 300 L / min.

[0061] In one optional implementation, the comprehensive utilization method further includes:

[0062] The first water-washed residue and / or the second water-washed residue are dehydrated, and the dehydrated product is returned to sintering to recover valuable elements in the sintering head ash and / or steelmaking refining ash.

[0063] Optionally, the moisture content of the dehydrated product is not higher than 20%.

[0064] In one optional embodiment, the nitrogen content in the sintering machine head ash is not less than 1 wt%, based on the total weight of the sintering machine head ash.

[0065] In one optional implementation, the comprehensive utilization method further includes:

[0066] The suspension was dried to obtain sulfur.

[0067] In the comprehensive utilization method of the present invention, steelmaking refining ash and sintering machine head ash are used to continuously replenish new ammonium ions to the washing liquid, and the conditions of excess ammonia are created by recycling the recovered liquid, so that the sulfur in the solution exists in the form of ammonium sulfide instead of ammonium hydrogen sulfide. Under aeration conditions, ammonium sulfide reacts with oxygen to generate sulfur and ammonia water, thereby maximizing the recycling of resources.

[0068] In the comprehensive utilization method of the present invention, without generating secondary pollution, the steel refining ash is co-processed with sintering machine head ash to achieve the resource recovery and utilization of valuable elements such as S and N, and to maximize the value utilization of metallurgical solid waste dust and sludge.

[0069] In the comprehensive utilization method of the present invention, harmful elements such as S, N, K, and Cl are removed by washing the steelmaking refining ash and sintering machine head ash with water. Then, the steelmaking refining ash and sintering machine head ash residue are returned to sintering to recover valuable elements such as Fe, Ca, Mg, and Si.

[0070] In the comprehensive utilization method of the present invention, by using the sintering machine head ash washing liquid to wash the steelmaking refining ash, not only is the wastewater after the sintering machine head ash washing treated, but the concentration of ammonium ions in the washing liquid is also increased, creating conditions for the generation of ammonium sulfide under conditions of excess ammonia.

[0071] In the comprehensive utilization method of the present invention, ammonium sulfide is decomposed into sulfur and ammonia-containing wastewater by aeration in the second washing liquid. After drying, the sulfur becomes sulfur, which is an important chemical raw material, truly realizing the transformation of waste into treasure.

[0072] In the comprehensive utilization method of this invention, the ammonia solution obtained by repeatedly recycling ammonia-containing wastewater through an ion exchange resin can be injected as an alkaline substance into the sintering flue gas duct, which can not only remove SO2 and NO from the flue gas. x Furthermore, it lowers the temperature of the flue gas in the flue, preventing excessively high temperatures in the sintering flue gas from causing hot spot accidents in the activated coke desulfurization and denitrification system.

[0073] In the comprehensive utilization method of this invention, steelmaking refining ash and sintering machine head ash are recycled after being treated by a water washing process. Other harmful substances are transformed into high-value products, sulfur and ammonia, through a series of chemical and physical methods, and high-chlorine wastewater is evaporated to extract salt. The entire process is interconnected, maximizing resource recovery and utilization while eliminating any secondary pollution.

[0074] The present invention will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed by the present invention.

[0075] Example 1

[0076] The following methods shall be used for the comprehensive utilization of sintering machine head ash and steelmaking refining ash:

[0077] (1) The sintering machine head ash (nitrogen content of 2wt%) is introduced into the water washing system silo by suction and discharge tanker. The sintering machine head ash and industrial water are added to the first-level water washing tank at a liquid-solid weight ratio of 4:1. The mixture is slowly stirred for 30 minutes at a stirring rate of 5r / min using a paddle mixer. Then it is left to stand for 0.5h to obtain the first layered slurry.

[0078] (2) The first layered slurry is separated into solid and liquid by using a filter screen to obtain the first water washing residue and the first water washing liquid. The first water washing residue is sent to a filter press for dewatering by a mud discharge pump to obtain the first residue with a water content of ≤20%, which is returned to sintering for use.

[0079] (3) Send the first washing liquid into the second washing tank, open the steelmaking refining ash silo and add an appropriate amount of steelmaking refining ash into the second washing tank so that the liquid-solid weight ratio in the second washing tank is 8:1, let it stand for 2 hours to obtain the second layered slurry.

[0080] (4) The second layered slurry is separated into solid and liquid by using a filter screen to obtain the second water washing residue and the second water washing liquid. The second water washing residue is sent to a filter press for dewatering by a mud discharge pump to obtain the second residue with a water content of ≤20%, which is then returned to sintering for use.

[0081] (5) The above second washing liquid is sent into the third-stage reaction tank, and air is introduced into the reaction tank at a flow rate of 200L / min for aeration treatment to obtain an aerated suspension.

[0082] (6) Use a filter screen to separate the above aerated suspension into solid and liquid, and obtain the suspension and the recovery liquid. The suspension is dried to obtain sulfur. The recovery liquid is returned to the secondary water washing tank and steps (1)-(5) are repeated until the ammonia concentration in the recovery liquid is not less than 5%.

[0083] (7) The recovered liquid is separated into ammonia solution and high salt solution by passing it through an ion exchange resin. The ammonia solution is used for cooling of the sintering flue and desulfurization and denitrification of flue gas. The high salt solution is used to prepare high-purity KCl and NaCl by evaporation and salt extraction process.

[0084] In this embodiment, after repeating steps (1)-(5) 5 times, the ammonia concentration in the recovered liquid obtained in step (6) is 6%, which meets the requirement of not less than 5%. Therefore, step (7) is executed, and this embodiment ends. At this time, in this embodiment, a total of 500 kg of sintering machine head ash and 200 kg of steelmaking refining ash were consumed, and 10 kg of sulfur, 100 kg of potassium chloride, 15 kg of sodium chloride, and 200 L of 10% ammonia solution were recovered.

[0085] Example 2

[0086] The sintering machine head ash and steelmaking refining ash were comprehensively utilized according to the method of Example 1. The difference is that in step (1) of this example, the liquid-solid ratio of industrial water and sintering machine head ash is 3:1. After stirring, the mixture was allowed to stand for 0.5 hours to obtain the first layered slurry.

[0087] In this embodiment, after repeating steps (1)-(5) 6 times, the ammonia concentration in the recovered liquid obtained in step (6) is 9%, which meets the requirement of not less than 5%. Therefore, step (7) is executed, and this embodiment ends. At this time, this embodiment consumes a total of 600 kg of sintering machine head ash and 250 kg of steelmaking refining ash, and recovers 12.5 kg of sulfur, 120 kg of potassium chloride, 20 kg of sodium chloride, and 240 L of a 10% ammonia solution.

[0088] Example 3

[0089] The sintering machine head ash and steelmaking refining ash were comprehensively utilized according to the method of Example 1. The difference is that in step (1) of this example, the liquid-solid ratio of industrial water and sintering machine head ash is 6:1. After stirring, the mixture was allowed to stand for 1 hour to obtain the first layered slurry.

[0090] In this embodiment, after repeating steps (1)-(5) 8 times, the ammonia concentration in the recovered liquid obtained in step (6) is 12%, which meets the requirement of not less than 5%. Therefore, step (7) is executed, and this embodiment ends. At this time, this embodiment consumes a total of 800 kg of sintering machine head ash and 350 kg of steelmaking refining ash, and recovers 17.5 kg of sulfur, 160 kg of potassium chloride, 27 kg of sodium chloride, and 320 L of a 10% ammonia solution.

[0091] Example 4

[0092] The sintering machine head ash and steelmaking refining ash were comprehensively utilized according to the method of Example 1. The difference is that in step (3) of this example, the liquid-solid weight ratio of the first washing liquid to the steelmaking refining ash is 6:1. After mixing, the mixture is allowed to stand for 2 hours to obtain the second layered slurry.

[0093] In this embodiment, after repeating steps (1)-(5) 5 times, the ammonia concentration in the recovered liquid obtained in step (6) is 6%, which meets the requirement of not less than 5%. Therefore, step (7) is executed, and this embodiment ends. At this time, this embodiment consumes a total of 500 kg of sintering machine head ash and 200 kg of steelmaking refining ash, and recovers 10 kg of sulfur, 100 kg of potassium chloride, 15 kg of sodium chloride, and 200 L of a 10% ammonia solution.

[0094] Example 5

[0095] The sintering machine head ash and steelmaking refining ash are comprehensively utilized according to the method of Example 1. The difference is that in step (3) of this example, the liquid-solid weight ratio of the first washing liquid to the steelmaking refining ash is 10:1. After mixing, the mixture is left to stand for 4 hours to obtain the second layered slurry.

[0096] In this embodiment, after repeating steps (1)-(5) 8 times, the ammonia concentration in the recovered liquid obtained in step (6) is 12%, which meets the requirement of not less than 5%. Therefore, step (7) is executed, and this embodiment ends. At this time, this embodiment consumes a total of 800 kg of sintering machine head ash and 350 kg of steelmaking refining ash, and recovers 17.5 kg of sulfur, 160 kg of potassium chloride, 27 kg of sodium chloride, and 320 L of a 10% ammonia solution.

[0097] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for comprehensive utilization of sintering machine head dust and steelmaking refining dust, characterized in that, The method comprises the following steps: contacting sintering machine head ash with water for a first effective duration, and performing primary solid-liquid separation on the obtained slurry to obtain first water washing residue and first water washing liquid; contacting steelmaking refining ash with the first water washing liquid for a second effective duration, and performing secondary solid-liquid separation on the obtained slurry to obtain second water washing residue and second water washing liquid; performing aeration treatment on the second water washing liquid to obtain an aeration suspension; performing three times of solid-liquid separation on the aeration suspension to obtain suspension and recovery liquid; The method further comprises: determining the ammonia concentration in the recovery liquid; in the case that the ammonia concentration in the recovery liquid is less than a preset value, mixing the recovery liquid with the first water washing liquid in the next cycle, and contacting the obtained mixed liquid with the steelmaking refining ash until the ammonia concentration in the recovery liquid is not less than the preset value; in the case that the ammonia concentration in the recovery liquid is not less than the preset value, passing the recovery liquid through ion exchange resin to obtain ammonia water solution and high-salt solution.

2. The integrated utilization method according to claim 1, characterized by, The preset value is any value in the range of 3% to 5%.

3. The integrated utilization method according to claim 1, characterized by, The method further comprises: evaporating the high-salt solution to prepare high-purity KCl and / or NaCl; using the ammonia water solution for sintering flue gas cooling and / or flue gas desulfurization and denitrification.

4. The integrated utilization method according to claim 1, characterized by, The step of contacting the sintering machine head ash with water for a first effective duration comprises: mixing the sintering machine head ash with water, uniformly stirring under the condition of 5 r / min to 15 r / min, and then standing for 0.5 h to 1.0 h.

5. The integrated utilization method according to claim 1, characterized by, The weight ratio of water to the sintering machine head ash is (3-6):

1.

6. The integrated utilization method according to claim 1, characterized by, The step of contacting the steelmaking refining ash with the first water washing liquid for a second effective duration comprises: mixing the steelmaking refining ash with the first water washing liquid, and standing for 2 h to 5 h.

7. The integrated utilization method according to claim 1, characterized by, The weight ratio of the first water washing liquid to the steelmaking refining ash is (6-10):

1.

8. The integrated utilization method according to claim 1, characterized by, The step of performing aeration treatment on the second water washing liquid comprises: introducing air into the second water washing liquid, and the air flow is 60 L / min to 300 L / min.

9. The integrated utilization method according to claim 1, characterized by, The method further comprises: dehydration of the first water washing residue and / or the second water washing residue, and returning the dehydration product to sintering to recover valuable elements in the sintering machine head ash and / or the steelmaking refining ash.

10. The integrated utilization method according to claim 9, characterized by, The moisture content in the dehydration product is not higher than 20%.

11. The integrated utilization method according to claim 1, characterized by, The content of nitrogen in the sintering machine head ash is not less than 1 wt% based on the total weight of the sintering machine head ash.

12. The integrated utilization method according to claim 1, characterized by, The method further comprises: drying the suspension to obtain sulfur.