A multi-component slag system for high oxygen-enriched copper bath smelting and a synergistic regulation method thereof

Abstract

This invention relates to the field of non-ferrous metal pyrometallurgy technology, and discloses a copper smelting method with synergistic control of a high-oxygen-enriched multi-component slag. The aim is to solve the problems of poor slag fluidity, large copper loss, and severe furnace lining erosion caused by over-oxidation of the molten pool in high-oxygen-enriched smelting. This method constructs a five-component slag system of FeO–SiO2–CaO–MgO–Al2O3, controlling the slag composition within a specific range: iron-silicon ratio 1.8–2.2, CaO 2.5%–4%, MgO 1%–2%, Al2O3 3%–5%, and SiO2 20%–25%. Simultaneously, synergistically matched process parameters are employed: oxygen enrichment rate 70%–85%, smelting temperature 1340–1360℃, and air supply intensity per unit area not less than 2100 Nm. 3 / (m 2 (h). Through a dynamic control mechanism, the physicochemical properties of the molten slag are monitored online and process variables are adjusted accordingly to control the slag viscosity to less than 0.3 Pa·s, the Fe3O4 content to 3%–5%, and the copper content to less than 1.5%. This invention achieves the technical effects of high slag-gold separation efficiency, low copper loss, and extended furnace lining life.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal pyrometallurgical technology, and particularly relates to a multi-component slag system for high oxygen-enriched copper molten pool smelting and its synergistic control method. Background Technology

[0002] With the continuous growth of global demand for copper resources and the increasing requirements for energy conservation and environmental protection, copper smelting technology is rapidly developing towards high oxygen enrichment, high strength, continuous operation, and automation. Among them, oxygen-enriched side-blown or bottom-blown smelting processes, such as China's Silver Process (SKS) and oxygen bottom-blown smelting technology (BCC), are widely used due to their advantages such as strong adaptability to raw materials, high smelting strength, and good environmental performance. In order to further improve production efficiency and energy utilization, the oxygen enrichment rate of modern copper smelting processes is constantly increasing, and some processes have entered the high oxygen enrichment stage with an oxygen enrichment rate exceeding 70%.

[0003] However, while high-oxygen-enriched operation brings significant advantages, it also raises a series of pressing technical challenges. Under conditions of high oxygen enrichment (e.g., oxygen enrichment rate > 70%) and high reaction intensity, a locally strong oxidizing atmosphere forms within the molten pool, leading to over-oxidation of the slag and the generation of large amounts of high-melting-point solid or semi-solid magnetite (Fe3O4). The precipitation of magnetite significantly increases the viscosity of the slag, drastically worsening its fluidity. This not only makes slag discharge difficult and affects production, but more importantly, the high-viscosity slag deteriorates the separation conditions between the slag and the metal (matte), resulting in a substantial increase in both mechanically entrained copper and chemically dissolved copper losses. Simultaneously, the high-temperature, high-oxygen-potential environment significantly intensifies the erosion of the furnace lining materials, while the poorly fluid slag makes it difficult to form a stable and uniform protective slag layer on the furnace wall, thus seriously affecting furnace life and operational safety.

[0004] To address the aforementioned issues, existing technologies have explored certain approaches. For example, patent CN117025971B discloses a high-oxygen-enriched carbon-free copper smelting method, which achieves self-heating smelting by adjusting the sulfur-copper ratio and iron-silicon ratio (Fe / SiO2) of the copper concentrate. Although it focuses on the flux ratio under high oxygen-enriched conditions, its control methods are still limited to the traditional iron-silicon ratio and do not systematically consider the synergistic effect of multi-component fluxes under high oxygen potential. Another patent, CN202164341U, discloses an oxygen-enriched bottom-blown copper smelting furnace, which reduces direct contact between oxygen-enriched gas and slag by blowing oxygen-enriched gas into the copper matte layer, aiming to reduce the formation of Fe3O4. This is an improvement in equipment structure and blowing method, but it does not propose a universal solution to the root cause of the slag's physicochemical properties. In terms of academic research, for example, the literature "Numerical simulation of multiphase flow in copper bottom-blown smelting furnace" analyzes the influence of process parameters such as gas flow velocity and slag layer thickness on multiphase flow in the molten pool through numerical simulation methods, revealing the complexity of the process. However, these studies focus on fluid dynamics analysis and have not yet formed a complete industrially applicable design and process synergistic control scheme for slag system.

[0005] In summary, existing technologies either focus on optimizing the furnace structure or are limited to adjusting a single iron-silicon ratio or changing the blowing method. While these technologies have improved certain problems to some extent, they have failed to systematically solve the three interconnected core technical challenges of poor fluidity, significant copper loss, and severe furnace lining erosion caused by slag over-oxidation under high oxygen-enriched (70%) smelting conditions. Under the harsh conditions of high oxygen enrichment and high intensity, how to design a multi-element slag system that can suppress the negative effects of magnetite while maintaining good fluidity, and how to establish a synergistic control mechanism between this slag type and high-intensity process parameters, is a major challenge currently facing this field. Summary of the Invention

[0006] The purpose of this invention is to solve a series of technical problems in existing copper smelting technology under high oxygen conditions, such as increased Fe3O4 content, increased slag viscosity, and decreased fluidity caused by slag over-oxidation, which in turn leads to low slag-gold separation efficiency, large copper loss in slag, and severe furnace lining erosion.

[0007] Therefore, the present invention provides a multi-component slag suitable for smelting copper in a high oxygen-enriched molten pool, characterized in that, by mass percentage, its composition includes: FeO / SiO2 of 1.8-2.2, CaO of 2.5%-4.0%, MgO of 1.0%-2.0%, Al2O3 of 3.0%-5.0%, and SiO2 of 20%-25%.

[0008] Preferably, the viscosity of the multi-component slag is less than 0.3 Pa·s at a temperature of 1340-1360℃.

[0009] Preferably, the Fe3O4 content of the multi-component slag is 3%–5%.

[0010] The present invention also provides a copper smelting system, including a furnace body and a molten pool, characterized in that the molten pool contains the aforementioned multi-component slag.

[0011] Preferably, the copper smelting system is configured with an oxygen enrichment rate of 70-85 vol% and a blower intensity of not less than 2100 Nm per unit hearth area. 3 / (m 2 It operates under the conditions of ·h).

[0012] Preferably, the multi-component slag forms a stable slag layer on the inner lining of the furnace body.

[0013] This invention also provides a method for smelting copper in a high-oxygen-enriched molten pool, using the aforementioned multi-component slag for smelting, and including the following steps: controlling the oxygen enrichment rate of the oxygen-enriched air during the smelting process to 70-85 vol%, controlling the temperature of the smelting reaction zone to 1340-1360℃, and controlling the air supply intensity per unit furnace bed area to be not less than 2100 Nm. 3 / (m 2 ·h).

[0014] Furthermore, the high oxygen-enriched copper smelting method further includes: monitoring the state of the slag and dynamically adjusting the CaO / SiO2 mass ratio, Fe / SiO2 mass ratio and / or blast oxygen concentration to maintain the slag viscosity at less than 0.3 Pa·s, the Fe3O4 content at 3%-5%, and the final discarded slag having a copper content of less than 1.5%.

[0015] Furthermore, the smelting blast pressure of the high oxygen-enriched copper molten pool smelting method is 110-125 kPa, and the slag layer thickness in the smelting furnace is controlled to be 100-120 cm.

[0016] Furthermore, the high-oxygen-enriched copper molten pool smelting method enables the multi-component slag to form and maintain a stable protective slag layer on the inner wall of the furnace lining.

[0017] The method of the present invention has the following advantages:

[0018] 1. Significantly improves the physicochemical properties of molten slag: Under harsh conditions of high oxygen enrichment (70%–85%), the negative impact of Fe3O4 is effectively suppressed through the synergistic effect of specific components such as CaO, MgO, and Al2O3, and the viscosity of molten slag is stably controlled below 0.3 Pa·s, ensuring good fluidity of molten slag and making the slag discharge operation smooth.

[0019] 2. Significantly reduced metal loss: The optimized slag system promotes rapid and effective separation of slag and gold, successfully reducing the copper content in the slag from over 2% in existing technologies to below 1.5%, significantly improving the direct copper recovery rate and resulting in significant economic benefits.

[0020] 3. Effectively extends furnace life: The slag composition designed in this invention can form a stable and dense protective slag layer on the furnace lining, effectively resisting the chemical and physical erosion of high-temperature melt and high oxygen potential atmosphere, reducing the furnace lining erosion rate by more than 40%, extending furnace life, and improving production efficiency and safety.

[0021] 4. Achieving energy conservation, consumption reduction, and high-efficiency production: The optimized slag system with high oxygen enrichment rate and high air supply intensity enhances metallurgical reaction kinetics, improves smelting efficiency, reduces unit fuel consumption by 10% to 15%, and enhances the process's adaptability to low-grade and complex raw materials, providing key technical support for efficient, low-consumption, and long-cycle copper smelting production. Detailed Implementation

[0022] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the technical solutions of this invention are described in detail below through specific implementation examples. These embodiments are intended to illustrate the application of this invention and are not intended to limit the scope of protection of this invention.

[0023] This invention provides an innovative multi-component slag system and its synergistic control method specifically applicable to copper smelting conditions with high oxygen enrichment (oxygen enrichment rate greater than 70%). The core of this system lies in constructing a slag phase that remains stable in a highly oxidizing environment by precisely controlling the proportions of FeO, SiO2, CaO, MgO, and Al2O3. Coupled with a strictly matched process parameter window, this invention suppresses the excessive formation of magnetic iron oxide (Fe3O4) at its source, effectively maintaining the low viscosity and good fluidity of the slag, thereby achieving the comprehensive goals of efficient slag-gold separation, significantly improved copper recovery rate, and long-term protection of the furnace lining.

[0024] Example 1

[0025] This embodiment describes a smelting application for processing high-grade copper concentrate. An 80 m³ smelter is used. 3The furnace is an oxygen-enriched double-sided blowing furnace with a magnesia-chrome brick lining. The copper concentrate processed has the following composition: copper 25.2%, iron 27.8%, sulfur 29.5%, silica 7.8%, and alumina 1.9%. By adding fluxes such as quartz, limestone, and lightly calcined magnesia, the final slag composition is precisely controlled within the following ranges: iron-silicon ratio (Fe / SiO2) of 2.0, calcium oxide content of 3.2%, magnesium oxide content of 1.8%, alumina content of 4.0%, and silica content of 21.5%. The co-operational process parameters are: oxygen-enriched air concentration of 80% (volume fraction), smelting reaction zone temperature stabilized at 1350℃, and air supply intensity per unit hearth area of ​​2250 Nm. 3 / (m 2 The blast pressure was 118 kPa, and the slag layer thickness was controlled at 110 cm. Under these conditions, the smelting process was stable and continuous. Actual operation monitoring showed that the viscosity of the slag at 1350℃ was approximately 0.25 Pa·s, and the Fe3O4 content remained stable between 3.8% and 4.2%, exhibiting excellent fluidity and smooth slag discharge. The grade of the produced matte remained stable at around 71.5%, while the copper content in the discarded slag averaged only 1.08%, resulting in a copper recovery rate of 98.3%. A shutdown inspection revealed that the furnace lining surface was covered with a uniform (5-10 cm) and dense, firmly bonded slag layer, and the refractory bricks themselves were intact, fully demonstrating the furnace lining protection effect of this invention.

[0026] Example 2

[0027] This embodiment describes the smelting application of low-grade copper concentrate. Its composition is: copper 7.6%, iron 34.5%, sulfur 24.8%, silicon dioxide 10.2%, aluminum oxide 4.5%, and a small amount of zinc oxide. Considering the high iron and aluminum content of this material, the slag system was adapted: the iron-silicon ratio was controlled at 2.1, and the calcium oxide content was appropriately increased to 3.8%, magnesium oxide to 2.0%, aluminum oxide to 4.8%, and silicon dioxide to 20.5%. Simultaneously, process parameters were moderately adjusted, with an oxygen enrichment rate of 75%, a smelting temperature of 1345℃, and a blower strength of 2150 Nm. 3 / (m 2 ·h). Under this optimized configuration, the system still achieved stable operation, successfully producing 64% grade copper matte, and the copper content of the waste slag was controlled at an excellent level of 1.42%, effectively recovering valuable metals from low-grade resources.

[0028] Example 3

[0029] This embodiment uses the same raw materials as Example 1, but the operating conditions are adjusted as follows: the oxygen enrichment rate is increased to 85%, the melting temperature is 1360℃, and the unit air supply intensity is increased to 2450 Nm. 3 / (m 2The blast pressure was 125 kPa. The final slag composition was adjusted accordingly to an iron-silicon ratio of 2.2, calcium oxide 3.0%, magnesium oxide 1.5%, aluminum oxide 4.5%, and silicon dioxide 22.0%. Despite the harsh environment of high oxygen potential and high stirring intensity, no abnormalities occurred in the production process due to the optimized design of the slag system itself. The slag viscosity remained at a low level of 0.28 Pa·s, the Fe3O4 content was 4.7%, and the slag-metal separation effect was good, ultimately yielding 67.5% grade matte and 1.28% copper-containing waste slag.

[0030] The above description is a preferred embodiment of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A multi-component slag suitable for high-oxygen-enriched copper molten pool smelting, characterized in that, By mass percentage, its composition includes: FeO / SiO2 of 1.8–2.2, CaO of 2.5%–4.0%, MgO of 1.0%–2.0%, Al2O3 of 3.0%–5.0%, and SiO2 of 20%–25%.

2. The multi-component slag according to claim 1, characterized in that, At a temperature of 1340-1360℃, its viscosity is less than 0.3 Pa·s.

3. The multi-component slag according to claim 1 or 2, characterized in that, Its Fe3O4 content is 3%–5%.

4. A copper molten pool smelting system, comprising a furnace body and a molten pool, characterized in that, The molten pool contains the multi-component slag as described in any one of claims 1-3.

5. The copper molten pool smelting system according to claim 4, characterized in that, The system is configured with an oxygen enrichment rate of 70-85 vol% and a blower intensity of not less than 2100 Nm per unit hearth area. 3 / (m 2 It operates under the conditions of ·h).

6. The copper molten pool smelting system according to claim 4 or 5, characterized in that, The multi-component slag forms a stable slag layer on the inner lining of the furnace body.

7. A method for smelting copper in a high-oxygen-enriched molten pool, characterized in that, The smelting process employs the multi-component slag as described in any one of claims 1-3, and includes the following steps: controlling the oxygen enrichment rate of the oxygen-enriched air during the smelting process to 70-85 vol%, controlling the temperature of the smelting reaction zone to 1340-1360℃, and controlling the air supply intensity per unit furnace bed area to be not less than 2100 Nm. 3 / (m 2 ·h).

8. The high-oxygen-enriched copper molten pool smelting method according to claim 7, characterized in that, Also includes: The state of the slag is monitored, and the mass ratio of CaO / SiO2, the mass ratio of Fe / SiO2 and / or the oxygen concentration of the blower are dynamically adjusted to maintain the slag viscosity at less than 0.3 Pa·s, the Fe3O4 content at 3%-5%, and the final discarded slag with a copper content of less than 1.5%.

9. The high-oxygen-enriched copper molten pool smelting method according to claim 7, characterized in that, The blast pressure for smelting is 110-125 kPa, and the slag layer thickness inside the smelting furnace is controlled to be 100-120 cm.

10. The method for high-oxygen-enriched copper molten pool smelting according to any one of claims 7-9, characterized in that, The method enables the multi-component slag to form and maintain a stable protective slag layer on the inner wall of the furnace lining.