Liquid copper smelting slag air quenching treatment method and system based on heat preservation and slow cooling

Abstract

This application belongs to the field of non-ferrous metal metallurgy and resource comprehensive utilization technology, and more specifically, relates to a method and system for air quenching liquid copper smelting slag based on heat preservation and slow cooling. This application uses compressed air or compressed waste nitrogen to air quench liquid copper smelting slag that has undergone heat preservation and slow cooling to achieve copper particle agglomeration and growth. This significantly shortens the processing time and achieves centralized and efficient recovery of waste heat. Simultaneously, it reduces the amount of slag bag used and the required site area. Furthermore, the copper slag particles obtained from air quenching are small in size and the copper-containing particles are fully grown, eliminating the need for multi-stage crushing processes. After ball milling, it can be used for mineral processing and recovery, significantly shortening the mineral processing flow and reducing the difficulty of mineral processing.

Description

Technical Field

[0001] This application belongs to the field of non-ferrous metal metallurgy and resource comprehensive utilization technology, and more specifically, relates to a method and system for air quenching treatment of liquid copper smelting slag based on heat preservation and slow cooling. Background Technology

[0002] During copper smelting, molten copper smelting slag with temperatures reaching 1200℃~1400℃ is produced. This slag typically contains valuable copper resources in the form of matte and carries a large amount of high-grade sensible heat (approximately 1.47 × 10⁻⁶). 6 (kJ / t). Currently, the industrial practice commonly uses a combination of natural slow cooling and in-bundle water cooling to slowly cool molten copper smelting slag. This slow cooling promotes the growth of matte (mainly Cu2S) particles to a flotationable size, facilitating subsequent copper resource recovery through flotation. While this method ensures the selectivity of the copper phase, it suffers from several drawbacks: a long slow cooling cycle (>48 hours), the need for numerous slag bags and large-area slow cooling facilities, almost complete natural heat dissipation, difficulty in heat recovery, and extremely low energy efficiency. Furthermore, the copper slag obtained from slow cooling requires multiple stages of crushing and grinding (coarse crushing, medium crushing, fine crushing, and coarse grinding) to reach the flotation particle size, resulting in high equipment investment and high energy consumption.

[0003] To improve the cooling rate of molten copper smelting slag and recover waste heat, the industry has tried various rapid quenching technologies (such as water quenching and air quenching), but all have failed to achieve the synergistic recovery of "copper and iron resources and waste heat" due to the introduction of new technical obstacles. While water quenching can shorten cooling time, it suffers from problems such as water pollution (unresolved heavy metal contamination), secondary pollution, and huge water consumption due to the contact between high-temperature copper smelting slag and water. Furthermore, rapid cooling leads to the formation of a large amount of hard glassy phase in the slag, preventing copper particles from growing sufficiently, significantly increasing the difficulty and cost of subsequent grinding. The copper recovery rate from the smelting slag is also low, and waste heat cannot be recovered. Existing air quenching processes typically add water to improve the cooling rate, achieving a higher cooling rate, but similarly, rapid cooling leads to the formation of a significant glassy phase in the slag, increasing the difficulty and cost of grinding, and resulting in an extremely low copper recovery rate from the smelting slag.

[0004] In summary, existing slow cooling processes have significant shortcomings in terms of processing time, waste heat recovery and utilization, and energy consumption. While rapid cooling processes such as water quenching and air quenching can accelerate cooling, they lead to problems such as increased glass phase, difficulty in recovering copper and iron resources, low waste heat recovery rate, safety risks, and environmental pollution. Therefore, there is an urgent need in this field to provide a method that can synergistically achieve centralized and efficient recovery of high-grade waste heat and the recovery of valuable copper and iron metals from copper smelting slag. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this application is to provide a method and system for air quenching treatment of liquid copper smelting slag based on heat preservation and slow cooling. The aim is to solve the problems that existing methods for treating molten copper smelting slag cannot centrally and efficiently recover waste heat, and have long treatment cycles, high ore beneficiation difficulty, large slag bag usage, large site area occupation, limited comprehensive recovery benefits, and cause safety, environmental protection and equipment operation problems.

[0006] To achieve the above objectives, in a first aspect, this application provides a method for air quenching liquid copper smelting slag based on heat preservation and slow cooling, comprising the following steps:

[0007] S1. Under the atmosphere of air quenching medium, liquid copper smelting slag is formed into a continuous slag flow, and air quenching medium is sprayed into the continuous slag flow to perform impact granulation and cooling to form copper slag particles. At the same time, the air quenching medium absorbs the sensible heat of the molten slag to form flue gas.

[0008] The liquid copper smelting slag mentioned above is the liquid copper smelting slag into which molten copper smelting slag is fed into a slag bag and kept at a temperature above 1205℃ for 8 to 12 hours to allow copper-containing particles to accumulate and grow; the air quenching medium mentioned above is compressed air or compressed waste nitrogen.

[0009] S2. The flue gas is treated with dust removal and the sensible heat is recovered. The copper slag particles are then subjected to grinding and flotation to recover copper-containing particles, and magnetic separation is performed to recover magnetite, thereby realizing the beneficiation and recovery of copper and iron in copper smelting slag and the utilization of waste heat.

[0010] Preferably, in step S1, the oxygen volume concentration of the compressed waste nitrogen is 1% to 5%, which can partially oxidize the ferrous oxide and ferrous sulfide in the liquid copper smelting slag during the granulation process, while avoiding the oxidation of cuprous sulfide.

[0011] Preferably, in step S1, the mass percentage of copper in the liquid copper smelting slag is 0.5% to 8%, the mass percentage of iron is 35% to 50%, and the particle size D80 of the copper-containing particles is greater than 43 μm.

[0012] Preferably, the above-mentioned heat preservation and slow cooling treatment is carried out in a heat preservation chamber; and / or, multiple heat preservation mechanisms are provided for the above-mentioned slag bag.

[0013] Preferably, the aforementioned multiple insulation mechanisms include one or more of the following: an insulation cover agent covering the surface of the molten slag inside the slag ladle, an insulation cover disposed at the opening of the slag ladle, and a jacketed insulation box disposed outside the slag ladle.

[0014] Preferably, in step S1, the spraying direction of the air quenching medium forms an obtuse angle with the flow direction of the continuous slag flow, causing the slag flow to move in a parabolic motion.

[0015] Preferably, in step S1, the injection pressure of the air quenching medium is 0.6 MPa to 1 MPa.

[0016] Preferably, in step S1, the ratio of the volumetric flow rate of the air-quenching medium to the mass flow rate of the continuous slag flow is (400m³ / s). 3 ~700m 3 ): 1 ton of slag.

[0017] Preferably, the particle size of the copper slag particles is less than 3 mm; and / or, the temperature of the flue gas is 300℃~800℃.

[0018] Secondly, this application provides a system for implementing the above-mentioned air quenching treatment method, comprising an air quenching heat collection unit and a mineral processing unit; wherein...

[0019] The aforementioned air-quenching heat collection unit includes:

[0020] The air quenching chamber has a slag inlet on the upper part of its side wall and a slag outlet on the lower part of its side wall;

[0021] The slag chute introduces liquid copper smelting slag into the air quenching chamber through the slag inlet, forming a continuous slag flow.

[0022] An air quenching spray device is installed in the air quenching chamber and located below the slag inlet, and is used to spray air quenching medium into the continuous slag flow for impact granulation and cooling.

[0023] The dust removal, ventilation, and heat collection module is located at the top of the aforementioned air quenching chamber. It is used to draw in the flue gas formed after the air quenching medium absorbs the sensible heat of the molten slag, and to perform dust removal and sensible heat recovery.

[0024] A slag conveying device is located at the bottom of the aforementioned air quenching chamber and is used to convey the copper slag particles formed after air quenching to the slag outlet.

[0025] The aforementioned mineral processing unit includes a grinding unit and a flotation-magnetic separation unit.

[0026] Preferably, the above-mentioned air quenching spray device is an oblique blowing pneumatic granulation structure.

[0027] In summary, the technical solutions conceived in this application have the following main technical advantages compared with the prior art:

[0028] (1) Compared with the existing slow cooling process of copper smelting slag (natural slow cooling + in-bundle water cooling), the air quenching treatment method provided in this application uses compressed air or compressed waste nitrogen to quench the liquid copper smelting slag that has been slowly cooled and heated to achieve the aggregation and growth of copper particles. This significantly shortens the treatment time, achieves centralized and efficient recovery of waste heat, reduces the amount of slag bag used (reduced to 1 / 10 of the original), eliminates the original slow cooling field and stockpile (the site area is reduced to 1 / 20 of the original), and the copper slag particles obtained by air quenching are small in size (less than 3mm). There is no need to carry out multi-stage crushing processes such as coarse crushing, medium crushing, fine crushing, and coarse grinding. After ball milling, it can be recycled for mineral processing, which significantly shortens the mineral processing process and reduces the difficulty of mineral processing.

[0029] (2) The air quenching method provided in this application uses compressed waste nitrogen with an oxygen volume concentration of 1% to 5% as the air quenching medium. The high-temperature flue gas generated by air quenching can be recovered with high-quality sensible heat after simple dust removal, which greatly reduces the desulfurization and denitrification load and is environmentally friendly. In addition, the high-temperature flue gas has low corrosivity to the system, which can significantly improve the system's operational stability, extend the service life of the equipment, and improve the waste heat recovery efficiency and comprehensive recovery benefits. In actual production, the waste heat collected above can be used for copper concentrate drying or steam production, plant heating and power generation, etc., thereby greatly reducing the enterprise's energy consumption costs. Furthermore, the air quenching medium after waste heat recovery can also be recycled, greatly reducing the consumption cost of the air quenching medium. At the same time, using a low-oxygen air quenching medium for air quenching can also improve the magnetic separation recovery rate of iron while ensuring the copper beneficiation performance in copper smelting slag, fundamentally solving the problem of copper and iron co-recovery and realizing the fractional recovery of valuable metals.

[0030] (3) Compared with the existing air quenching rapid cooling system, the system provided in this application, by designing and optimizing the position of the air quenching jet device and the jetting angle of the air quenching medium in the air quenching heat collection unit, enables the air quenching medium sprayed by the air quenching jet device to form an upward oblique airflow that impacts the granulated continuous slag flow, making the continuous slag flow move in a parabolic trajectory, extending its residence time in the air and the gas-slag contact path, strengthening the convective heat transfer process, and completing the entire process of rapid cooling, crushing and spheroidizing of liquid copper smelting slag within 0.5s to 2s, effectively avoiding the adhesion of high-temperature molten slag to the ground, reducing the demand for lateral space in the air quenching heat collection unit, reducing the overall area of ​​the equipment, and reducing the entrainment of ambient air, thus reducing the risk of dust and equipment nodules. At the same time, the integrated dust removal and exhaust heat collection module makes it easier for the high-temperature flue gas formed after the air quenching medium absorbs the sensible heat of copper slag to form a stable and concentrated heat flow field in the heat collection module, significantly improving the uniformity of the inlet airflow and the stability of heat recovery, which is conducive to the efficient recovery and utilization of high-grade sensible heat. The system provided in this application achieves multiple technical effects, such as efficient slag granulation, no slag agglomeration, improved waste heat quality, and improved equipment operating environment, providing support for the integrated system of copper slag air quenching and waste heat recovery. Attached Figure Description

[0031] Figure 1 This describes the oxidation of cuprous sulfide under different oxygen and sulfur partial pressures.

[0032] Figure 2 The oxidation of cuprous sulfide and ferrous sulfide under different oxygen and sulfur partial pressures;

[0033] Figure 3 It describes the oxidation of cuprous sulfide and ferrous oxide under different oxygen and sulfur partial pressures.

[0034] Figure 4 This is a schematic flowchart of the air quenching treatment method for liquid copper smelting slag based on heat preservation and slow cooling provided in the embodiments of this application;

[0035] Figure 5 This is a schematic diagram of the structure of the air quenching heat collection unit in the liquid copper smelting slag air quenching treatment system based on heat preservation and slow cooling provided in this application;

[0036] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1-air quenching chamber; 2-slag inlet; 3-slag outlet; 4-slag chute; 5-air quenching jet device; 6-dust removal, exhaust and heat collection module; 7-slag receiving and conveying device. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0038] In the description of this application, it should be understood that the term "and / or" describes a relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. The symbol " / " in this document indicates that the related objects are in an "or" relationship; for example, A / B means A or B.

[0039] In the description of the embodiments in this application, the words "exemplary" or "for example" are used to indicate that they are examples, illustrations, or descriptions. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design options. Specifically, the use of the words "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0040] In the description of the embodiments in this application, unless otherwise stated, "multiple" means two or more.

[0041] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium. The directional terms mentioned in the embodiments of this application, such as "inner," "outer," "left," "right," "upper," and "lower," are only for reference to the directions in the accompanying drawings. The use of directional terms is for better and clearer explanation and understanding of the embodiments of this application, and is not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation on the embodiments of this application.

[0042] Valuable metals in copper smelting slag mainly exist in specific phases: copper primarily exists as cuprous sulfide (Cu₂S), while iron mainly exists as ferrous oxide and magnetite. These two phases, when individually exposed to oxygen, follow different reaction pathways: cuprous sulfide (Cu₂S) reacts violently with oxygen, first oxidizing to cuprous oxide (Cu₂O) and sulfur dioxide (SO₂), and then further oxidizing to the more stable copper oxide (CuO). Ferrous oxide (FeO), on the other hand, reacts with oxygen to form magnetite (Fe₃O₄).

[0043] Specifically, the transformation of cuprous sulfide (Cu2S) under different oxygen partial pressures is as follows: Figure 1As shown, when the logarithm of the oxygen partial pressure increases to greater than -4 atm, cuprous sulfide is violently oxidized to higher-valence copper oxides (such as Cu₂O, CuO) or sulfates (such as CuSO₄). The transformation of the matte components (coexisting cuprous sulfide and ferrous sulfide) under different oxygen partial pressures is shown in the figure. Figure 2 As shown, when the logarithm of the oxygen partial pressure increases to -9 atm to -3 atm, ferrous sulfide is oxidized to magnetite, while cuprous sulfide remains stable, indicating that the thermodynamic oxidation priority of ferrous sulfide is higher than that of cuprous sulfide. However, when cuprous sulfide (Cu₂S) coexists with ferrous oxide (0 < Cu / (Fe+Cu) < 0.333), under the same oxygen partial pressure conditions (logarithm of oxygen partial pressure increases to greater than -4 atm), cuprous sulfide will still preferentially oxidize to higher-valence copper oxides or sulfates (such as...). Figure 3 (As shown).

[0044] The aforementioned phase reaction characteristics dictate that for molten copper smelting slag with its unique phase composition, simply using oxygen-enriched gas or nitrogen as the quenching medium without heat preservation and slow cooling will not only fail to achieve effective copper particle growth but also hinder the synergistic recovery of copper and iron resources. Therefore, the core technical problem this application aims to solve is how to improve the iron recovery rate while ensuring the copper beneficiation performance in copper smelting slag, thereby synergistically recovering valuable copper and iron metals and efficiently recovering high-quality waste heat.

[0045] To address this core issue, this application provides a method for air quenching liquid copper smelting slag based on heat preservation and slow cooling, such as... Figure 4 As shown, it includes the following steps:

[0046] S1. Under the atmosphere of air quenching medium, liquid copper smelting slag is formed into a continuous slag flow, and air quenching medium is sprayed into the continuous slag flow to perform impact granulation and cooling to form copper slag particles. At the same time, the air quenching medium absorbs the sensible heat of the molten slag to form flue gas.

[0047] The liquid copper smelting slag mentioned above is the liquid copper smelting slag into which molten copper smelting slag is fed into a slag bag and kept at a temperature above 1205℃ for 8 to 12 hours to allow copper-containing particles to accumulate and grow; the air quenching medium mentioned above is compressed air or compressed waste nitrogen.

[0048] S3. The flue gas is treated by dust removal and the sensible heat is recovered. The copper slag particles are floated to recover copper-containing particles and magnetically separated to recover magnetite, thereby realizing the beneficiation and recovery of copper and iron in copper smelting slag and the utilization of waste heat.

[0049] The core idea of ​​this application is to use a precisely controlled oxygen concentration air quenching medium to treat liquid copper smelting slag that has undergone specific heat preservation and slow cooling treatment, thereby achieving the synergistic recovery of copper and iron resources and efficient utilization of waste heat. Firstly, the object of the air quenching treatment is the liquid copper smelting slag that has been fed into a slag bag and then kept at a temperature above 1205℃ for 8-12 hours to allow copper particles to aggregate and grow. This is because the copper phase matte particles (mainly Cu2S and FeS) that can be recovered by flotation in the copper smelting slag precipitate within the temperature range of 1020℃-1190℃, while during the cooling process, iron-containing minerals (melting point 1205℃), with a content of up to 80%, as well as other phases such as Al2O3 and SiO2, precipitate before the matte phase. The inventors discovered through experiments that the rapid precipitation of iron-containing minerals increases the viscosity of the system. Simultaneously, the encapsulation of small-particle liquid matte within these iron-containing minerals severely hinders the movement and collision of matte particles within the slag phase, slowing their settling, aggregation, and growth rates, thus affecting the subsequent flotation's selectivity and recovery efficiency. Therefore, by adding molten copper smelting slag to a slag bag and then slowly cooling it at above 1205℃ for 8-12 hours, the aim is to ensure the slag remains in a low-viscosity state, providing conditions for the settling, aggregation, and growth of copper particles, thereby fundamentally guaranteeing the copper beneficiation performance.

[0050] Subsequently, compressed air or compressed waste nitrogen is used for air quenching. The air quenching medium is then recovered to absorb the sensible heat of the molten slag and form flue gas, thus realizing the centralized and efficient utilization of waste heat. At the same time, the copper slag particles obtained from air quenching are recycled through mineral processing, which effectively shortens the mineral processing process and has the advantages of short processing cycle, small slag bag usage, and small site area.

[0051] In some embodiments, the aforementioned air quenching medium is compressed waste nitrogen with an oxygen volume concentration of 1% to 5%. It is understood that the aforementioned waste nitrogen can be the vented waste nitrogen generated during the oxygen production process in copper smelting, which can reduce the treatment cost of the air quenching medium. When using compressed waste nitrogen with a low oxygen concentration for air quenching, on the one hand, it can promote the preferential reaction of ferrous oxide in the liquid copper smelting slag with the limited oxygen during the granulation process, oxidizing it to generate magnetic magnetite (Fe3O4), creating conditions for subsequent magnetic separation and recovery of iron resources; on the other hand, because the oxygen concentration is limited and rapidly depleted, the oxygen potential of the system decreases rapidly, and the remaining oxygen preferentially reacts with ferrous sulfide in matte, thereby effectively inhibiting the oxidation of cuprous sulfide (Cu2S), maintaining it in a stable sulfide state, and preserving good flotation performance. Furthermore, by using compressed waste nitrogen with strictly controlled oxygen concentration for air quenching, efficient waste heat recovery is achieved while avoiding environmental pollution. In actual production, this can significantly reduce the desulfurization and denitrification load and significantly improve the overall recovery efficiency.

[0052] This application achieves clean and efficient utilization of waste heat by combining the strategy of "heat preservation and slow cooling to promote copper particle growth" with "selective oxidation of ferrous oxide in low-oxygen air quenching medium". It also successfully solves the problem of the difficulty in co-recovering copper and iron in the slow cooling treatment of copper smelting slag, and improves the iron recovery rate while ensuring the copper beneficiation performance.

[0053] In some embodiments, in step S1, the mass percentage of copper in the liquid copper smelting slag is 0.5% to 8%, the mass percentage of iron is 35% to 50%, and the particle size D80 of the copper-containing particles is greater than 43 μm.

[0054] In some embodiments, the above-mentioned heat preservation and slow cooling treatment in step S1 is carried out in a heat preservation chamber. In some embodiments, the temperature of the heat preservation chamber is maintained between the slag receiving temperature and 1205°C (the melting point of ferrous oxide), which can keep the liquid copper smelting slag in a high-temperature liquid phase window period, so that the copper-containing droplets continue to settle, collide and aggregate under the action of gravity, thereby achieving macroscopic segregation and coarsening of copper particles, and promoting the continuous settling and rapid aggregation and growth of copper particles.

[0055] In some embodiments, to further improve the heat preservation effect, the above-mentioned heat preservation and slow cooling treatment also includes setting multiple heat preservation mechanisms for the slag ladle. It is understood that this application does not limit the form of the heat preservation mechanism. Those skilled in the art can set appropriate heat preservation mechanisms according to actual production conditions. As long as the molten copper smelting slag added to the slag ladle can be kept at a temperature above 1205°C for 8-12 hours for slow cooling, allowing copper particles in the slag to accumulate and grow, it is within the scope of protection of this application. For example, the above-mentioned multiple heat preservation mechanisms include, but are not limited to, one or more of the following: a heat preservation covering agent covering the surface of the molten slag inside the slag ladle, a heat preservation cover set at the slag ladle opening, and a jacketed heat preservation box set outside the slag ladle. These mechanisms can effectively solve the problem of small copper particles in the slag surface crust at the ladle opening that cannot be floated and recovered, resulting in high copper content in the tailings, allowing the slag to remelt and providing favorable conditions for the sedimentation, aggregation, and growth of copper particles.

[0056] To verify the effectiveness of heat preservation and slow cooling, this application conducted simulation experiments on a 12m² directly air-cooled structure. 3 Foundry ladle, 12m 3 Welding package, 24m 3 Casting ladle, and 24m² insulated box equipped with insulation covering, insulation cover, and jacketed insulation box. 3 A simulation of a (insulated) casting ladle was conducted, and the liquid phase content was measured 8-12 hours after slag collection and solidification. The results showed that the insulation effect of the casting ladle was superior to that of the welded ladle, and the insulation performance of a large-volume slag ladle was better than that of a small-volume slag ladle. Specifically, 24m... 3(Insulated) When the casting ladle is held at the same temperature and slowly cooled for 8 hours, the mass percentage of liquid molten slag with a temperature above 1205℃ in the ladle is greater than 90%; when held at the same temperature and slowly cooled for 12 hours, the mass percentage of liquid molten slag with a temperature above 1205℃ in the ladle is still 88.7%. Furthermore, 12m 3 When the casting ladle was kept at a constant temperature and cooled slowly for 12 hours, a solidified shell appeared on the ladle wall, while at 24m... 3 When the casting ladle was kept at a high temperature and cooled slowly for 12 hours, no solidified shell layer appeared on the ladle wall. This indicates that the high temperature liquid phase window of 8 to 12 hours above 1205℃ can be achieved by keeping the ladle at a high temperature and cooling slowly for 12 hours, which is beneficial to the sedimentation, aggregation and growth of copper particles.

[0057] In some embodiments, at the end of the above-mentioned heat preservation and slow cooling treatment, the mass percentage of liquid slag with a temperature above 1205°C in the slag bag is maintained at more than 80%, that is, the mass percentage of liquid slag with a temperature above 1205°C in the liquid copper smelting slag is greater than 80%.

[0058] In some embodiments, in step S1, the injection direction of the air-quenching medium forms an obtuse angle with the flow direction of the continuous slag flow. By injecting the air-quenching medium, an upward oblique airflow can be formed to impact and granulate the continuous slag flow, causing the slag flow to move in a parabolic motion. This prolongs its residence time in the air and the gas-slag contact path, enhancing the convective heat transfer process. The entire process of rapid cooling, crushing, and spheroidizing of liquid copper smelting slag can be completed within 0.5s to 2s, effectively preventing the high-temperature molten slag from agglomerating upon landing. Simultaneously, the high-temperature flue gas formed after the air-quenching medium absorbs the sensible heat of the liquid copper smelting slag is more likely to form a stable and concentrated heat flow field in the heat collection device, significantly improving the uniformity of the inlet airflow and the stability of heat recovery, which is beneficial for achieving efficient recovery and utilization of high-grade sensible heat. In some embodiments, the angle is 100° to 170°, preferably 100° to 150°.

[0059] In some embodiments, in step S1, the injection pressure of the aforementioned air-quenching medium is 0.6 MPa to 1 MPa. Specifically, the injection pressure can be 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1.0 MPa, etc. By injecting high-speed air-quenching medium, the slag flow is induced to disperse and granulate, thereby forming copper slag particles with a particle size of less than 3 mm. When these copper slag particles are subsequently processed for mineral processing and recovery, there is no need for crushing, semi-autogenous grinding, or other processes, significantly reducing the number of steps in the mineral processing.

[0060] In some embodiments, in step S1, the ratio of the volumetric flow rate of the air-quenching medium to the mass flow rate of the continuous slag flow is (400m³ / s). 3 ~700m 3 ): 1 ton of slag.

[0061] In some embodiments, the temperature of the flue gas in step S1 is 300℃~800℃. Compared with the traditional method of treating copper smelting slag by natural slow cooling followed by in-bottle water cooling, this application uses heat preservation and slow cooling treatment on the copper smelting slag to cause copper-containing particles to aggregate and grow, and then uses compressed waste nitrogen with a suitable oxygen volume concentration for air quenching and granulation. This can oxidize some of the ferrous oxide and some of the ferrous sulfide in the liquid copper smelting slag into magnetite and inhibit the oxidation of cuprous sulfide. This enables centralized recovery of waste heat and significantly reduces the amount of SO2 generated in the flue gas, achieving high-quality and efficient recovery and utilization of waste heat.

[0062] On the other hand, this application provides a system for implementing the above-mentioned air quenching treatment method for liquid copper smelting slag, comprising an air quenching heat collection unit and a mineral processing unit; wherein,

[0063] The aforementioned air-quenching heat collection unit includes:

[0064] The air quenching chamber has a slag inlet on the upper part of its side wall and a slag outlet on the lower part of its side wall;

[0065] The slag chute introduces liquid copper smelting slag into the air quenching chamber through the slag inlet, forming a continuous slag flow.

[0066] The air quenching spray device is located in the air quenching chamber and below the slag inlet. It is used to spray air quenching medium into the continuous slag flow for impact granulation and cooling.

[0067] The dust removal, ventilation, and heat collection module is located at the top of the air quenching chamber. It is used to draw in the flue gas formed after the air quenching medium absorbs the sensible heat of the molten slag, and to perform dust removal and sensible heat recovery.

[0068] The slag conveying device is located at the bottom of the air quenching chamber and is used to transport the copper slag particles formed after air quenching to the slag outlet.

[0069] The aforementioned mineral processing unit includes a grinding unit and a flotation-magnetic separation unit.

[0070] In some embodiments, the above-mentioned mineral processing unit does not include a multi-stage crushing device. It is understood that those skilled in the art can adapt the addition of crushing devices to ensure that the particle size of the copper slag obtained from air quenching meets the flotation requirements based on the actual air quenching production conditions, and all such additions are within the scope of protection of this application.

[0071] It is understood that this application does not impose any special limitations on the structure, quantity, or number of layers of the spraying units in the aforementioned air quenching spraying device. Those skilled in the art can select appropriate spraying units as the air quenching spraying device based on the actual production scale, all of which are within the scope of protection of this application. In some embodiments, to improve the particle size uniformity of copper slag particles and enhance heat exchange efficiency, multiple spraying units can be configured to form an oblique-blowing pneumatic granulation structure, thereby segmenting and repeatedly impacting and granulating the continuous slag flow. For example, the number of spraying unit layers can be, but is not limited to, 2 to 4 layers.

[0072] Compared to existing copper smelting slag slow cooling + beneficiation equipment, the air quenching system provided in this application, through the design and optimization of the position of the air quenching jet device and the jet angle of the air quenching medium in the air quenching heat collection unit, effectively reduces the requirement for lateral space, eliminates the need for water cooling and slow cooling areas, significantly reduces the overall equipment footprint, and reduces the entrainment of ambient air, thereby lowering the risk of dust and equipment nodule formation. Simultaneously, since the entire air quenching and rapid cooling process is completed under the air quenching medium atmosphere, the SO2 content in the generated high-temperature flue gas is significantly reduced, effectively mitigating corrosion of the subsequent dust removal, exhaust, and heat collection modules. This helps reduce equipment wear, extend equipment lifespan, improve waste heat recovery efficiency, and enhance overall recovery benefits.

[0073] It should be understood that materials of the same or similar type, model, quality, properties, or function as the reagents and instruments used in the following embodiments can be used to implement this application. Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods. Unless otherwise specified, the materials and reagents used in the following embodiments are commercially available.

[0074] The following are examples and comparative examples:

[0075] Example 1

[0076] This embodiment provides a system for air quenching liquid copper smelting slag to achieve copper smelting slag beneficiation and centralized waste heat recovery. The system includes an air quenching heat collection unit and a beneficiation unit. A schematic diagram of the air quenching heat collection unit is shown below. Figure 5 As shown, it includes an air quenching chamber 1, a slag inlet 2, a slag outlet 3, a slag chute 4, an air quenching jet device 5, a dust removal, ventilation, and heat collection module 6, and a slag receiving and conveying device 7.

[0077] The air quenching treatment method for liquid copper smelting slag based on heat preservation and slow cooling provided in this embodiment includes the following steps:

[0078] 1) Introduce molten copper smelting slag at 1250°C into a 24m... 3In the casting ladle, an 80mm thick insulating cover is applied to the surface of the slag to isolate oxygen and reduce heat loss. Then, an insulating cover is placed at the mouth of the casting ladle on the surface of the cover. The sealed ladle is then transferred to a jacketed insulation box for slow cooling for 12 hours to allow the copper-containing particles in the slag to aggregate and grow, resulting in liquid copper smelting slag. The slag contains Cu2S with a copper content of 1.05% by mass, FeS with an iron content of 0.41% by mass, fir olivine with a content of 35.96% by mass, and copper-containing particles with a particle size D80 > 75μm.

[0079] 2) First, turn on the air quenching spray device 5 to introduce the air quenching medium to expel the air in the air quenching heat collection unit. Then, under the air quenching medium atmosphere, the liquid copper smelting slag is introduced into the air quenching chamber 1 at a flow rate of 1.5 tons of slag / min through the slag inlet chute 4 to the slag inlet 2 at the end of the slag inlet chute, thereby introducing the liquid copper smelting slag into the air quenching chamber 1 and forming a continuous slag flow. The air quenching medium is sprayed obliquely upwards into the continuous slag flow through the air quenching spray device 5 for impact granulation and cooling. At the same time, the air quenching medium absorbs the sensible heat of the copper smelting slag to form high-temperature flue gas (temperature 300°C~800°C), which is then treated by the dust removal and exhaust heat collection module 6 to remove dust and recover the sensible heat.

[0080] The aforementioned air quenching medium is waste nitrogen gas discharged from an oxygen production station with an oxygen volume concentration of 5%, and the pressure of the air quenching medium is 1.0 MPa; the air quenching spray device is a Venturi / Laval nozzle array with a nozzle throat diameter of 5 mm and the spray direction of the air quenching medium is at a 150° angle to the flow direction of the continuous slag flow; the dust removal, exhaust, and heat collection module includes a cyclone dust removal device and a heat collection device.

[0081] 3) The copper slag particles at the bottom of the air quenching chamber are transported to the slag outlet 3 by the slag receiving and conveying device 7, and the air-quenched copper slag particles are collected. The temperature of the discharged slag is 350°C, which meets the requirements of subsequent mineral processing.

[0082] 4) After the collected copper slag particles are sent to the mineral processing unit for ball milling, the fineness reaches 80% to -200 mesh, and then the flotation-magnetic separation combined process can be carried out to realize the separate recovery of copper and iron resources in the slag.

[0083] Example 2

[0084] The method for air quenching liquid copper smelting slag based on heat preservation and slow cooling provided in this embodiment is the same as that in embodiment 1, except that the air quenching medium is waste nitrogen gas discharged from an oxygen production station with an oxygen volume concentration of 3%.

[0085] Example 3

[0086] The method for air quenching liquid copper smelting slag based on heat preservation and slow cooling provided in this embodiment is the same as that in embodiment 1, except that the air quenching medium is waste nitrogen gas discharged from an oxygen production station with an oxygen volume concentration of 1%.

[0087] Comparative Example 1

[0088] The method for achieving efficient recovery of copper smelting slag beneficiation and waste heat provided in this comparative example is the same as that in Example 1, except that the air quenching medium is oxygen-containing nitrogen gas with an oxygen volume concentration of 0.5%.

[0089] Example 4

[0090] The method for achieving efficient recovery of copper smelting slag beneficiation and waste heat provided in this comparative example is the same as that in Example 1, except that the air quenching medium is air with an oxygen volume concentration of 21%.

[0091] Example 5

[0092] The method for air quenching liquid copper smelting slag based on heat preservation and slow cooling provided in this embodiment is the same as in Embodiment 1, except that the mass percentage of copper in Cu2S in the liquid copper smelting slag is 3.91%, the mass percentage of iron in FeS is 1.63%, the mass percentage of fir olivine is 47.59%, and the particle size D80 of copper-containing particles is >75μm.

[0093] By performing phase analysis on the copper slag particles obtained by air quenching, the contents of Cu2S, FeS, and ferrous oxide in the copper slag particles are determined. Then, by comparing the initial contents of each phase in the liquid copper smelting slag, the oxidation rate of Cu2S, FeS, and ferrous oxide can be calculated, thereby assessing the impact of oxygen volume concentration in the air quenching medium on the recovery of copper and iron resources from the liquid copper smelting slag.

[0094] The results are shown in Table 1.

[0095]

[0096] This application uses exhaust nitrogen gas with an oxygen volume concentration of 1% to 5% as the air quenching medium to quench liquid copper smelting slag that has undergone heat preservation and slow cooling to enrich and grow copper particles. By precisely controlling the oxidizing atmosphere, selective oxidation of the components in the slag is achieved, allowing oxygen to follow a clear reaction priority during the rapid cooling process: ferrous oxide (FeO) → ferrous sulfide (FeS) → cuprous sulfide (Cu2S). The reason for this may be that cuprous sulfide in the liquid copper smelting slag is dispersed as tiny droplets in the slag matrix, and this phase distribution structure constitutes a physical barrier that hinders the diffusion of oxygen to matte; at the same time, the weight percentage of cuprous sulfide in the liquid copper smelting slag is low (usually less than 2%), and its total exposed surface area is limited, further reducing the effective contact efficiency with oxygen. Therefore, when oxygen in the air-quenching medium enters the system, it preferentially reacts with and is largely consumed by the more readily accessible components (mainly iron-containing minerals) present in the slag. This process oxidizes ferrous oxide to precipitate magnetic Fe3O4, laying the foundation for subsequent magnetic separation and recovery of iron resources. After the ferrous oxide component has consumed most of the oxygen, the oxygen potential of the system decreases, and the remaining trace amounts of oxygen preferentially react with ferrous sulfide in the matte, thereby effectively inhibiting the oxidation of cuprous sulfide and ensuring its subsequent flotationability.

[0097] This application employs a uniquely designed air-quenching heat collection unit. The air-quenching medium ejected by the air-quenching jet device forms an upward oblique impact airflow, effectively dispersing the liquid slag flow falling from the slag inlet, causing it to move in a parabolic trajectory and inducing its dispersion and granulation. This process significantly extends the residence time of liquid copper smelting slag in the air-quenching heat collection unit and the gas-slag contact path, enhancing the convective heat transfer process. This allows the liquid copper smelting slag to complete the entire process of rapid cooling, crushing, and spheroidization within 2 seconds, resulting in copper slag particles with a particle size of less than 3 mm, effectively preventing the high-temperature molten slag from agglomerating upon landing. Simultaneously, the high-temperature flue gas formed after the air-quenching medium absorbs the sensible heat of the copper smelting slag, and after purification by the rotary dust collector, is more likely to form a stable and concentrated heat flow field in the heat collection device. This significantly improves the uniformity of the inlet airflow and the stability of the heat recovery system, which is conducive to achieving efficient recovery and utilization of high-grade sensible heat.

[0098] Furthermore, this structural design effectively reduces the lateral space requirement for the air-quenching heat collection unit, shrinks the overall footprint of the equipment, and reduces the entrainment of ambient air. The entire process is completed in an air-quenching medium atmosphere, resulting in extremely low SO2 content in the generated high-temperature flue gas, which significantly reduces corrosion of the subsequent dust removal, exhaust, and heat collection modules. This helps reduce equipment wear and tear, extend equipment lifespan, and reduce the environmental treatment load.

[0099] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for air quenching liquid copper smelting slag based on heat preservation and slow cooling, characterized in that, Includes the following steps: S1. Under the atmosphere of air quenching medium, liquid copper smelting slag is formed into a continuous slag flow, and air quenching medium is sprayed into the continuous slag flow for impact granulation and cooling to form copper slag particles. At the same time, the air quenching medium absorbs the sensible heat of the molten slag to form flue gas. The liquid copper smelting slag is the liquid copper smelting slag into which molten copper smelting slag is fed into a slag bag and kept at a temperature above 1205℃ for 8 to 12 hours to allow copper-containing particles to aggregate and grow. The air quenching medium is compressed waste nitrogen gas with an oxygen volume concentration of 1% to 5%, which can partially oxidize the ferrous oxide and ferrous sulfide in the liquid copper smelting slag during the granulation process, while avoiding the oxidation of cuprous sulfide. S2. The flue gas is treated with dust removal and the sensible heat is recovered. The copper slag particles are then subjected to grinding and flotation to recover copper-containing particles, and magnetic separation is performed to recover magnetite, thereby realizing the beneficiation and recovery of copper and iron in copper smelting slag and the utilization of waste heat.

2. The method according to claim 1, characterized in that, In step S1, the liquid copper smelting slag contains 0.5% to 8% copper by mass, 35% to 50% ferrous oxide and ferrous sulfide by mass, and the copper particles have a particle size D80 greater than 43 μm.

3. The method according to claim 1 or 2, characterized in that, The heat preservation and slow cooling treatment is carried out in a heat preservation chamber; and / or, the slag bag is provided with multiple heat preservation mechanisms; The multiple insulation mechanism includes one or more of the following: an insulation cover agent covering the surface of the molten slag inside the slag ladle, an insulation cover set at the opening of the slag ladle, and a jacketed insulation box set outside the slag ladle.

4. The method according to claim 1, characterized in that, In step S1, the spraying direction of the air quenching medium forms an obtuse angle with the flow direction of the continuous slag flow, causing the slag flow to move in a parabolic motion.

5. The method according to claim 1 or 4, characterized in that, The injection pressure of the air quenching medium is 0.6MPa~1MPa.

6. The method according to claim 1 or 4, characterized in that, The ratio of the volumetric flow rate of the wind quenching medium to the mass flow rate of the continuous slag stream is (400 m 3 700 m 3 ): 1 ton of slag.

7. The method according to claim 1, characterized in that, In step S1, the particle size of the copper slag particles is less than 3 mm; and / or, The temperature of the flue gas is 300℃~800℃.

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