Pyrolysis residue and copper sulfide ore cooperative smelting method

Abstract

This invention discloses a method for co-smelting pyrolysis residue and copper sulfide ore, comprising: pyrolyzing halogen-containing waste circuit boards to obtain pyrolysis residue; mixing the pyrolysis residue with copper sulfide ore and flux, and feeding it into an oxygen-enriched side-blown smelting furnace for smelting, forming a copper matte phase, a slag phase, and a flue gas phase under side-blown oxygen-enriched conditions; by controlling the smelting temperature, oxygen supply intensity, and slag composition, gold and silver are enriched in the copper matte phase, and elements such as lead, zinc, antimony, arsenic, and bismuth are directionally distributed among the copper matte phase, slag phase, and flue gas phase; the copper matte phase, slag phase, and flue gas phase are discharged separately, and the copper matte phase is subsequently recycled. This invention combines pyrolysis dehalogenation of waste circuit boards with copper smelting, which can reduce the environmental risks of direct pyrometallurgical treatment of halogen-containing organic matter, improve the enrichment efficiency of rare and precious metals, and improve the adaptability of complex secondary resources in an oxygen-enriched side-blown smelting furnace.

Description

Technical Field

[0001] This invention belongs to the field of comprehensive resource utilization and non-ferrous metal metallurgy technology, specifically relating to a method for co-smelting pyrolysis residue and copper sulfide ore. Background Technology

[0002] With the surge in electronic waste, the clean and efficient recycling of valuable metals (such as copper, gold, and silver) from waste circuit boards has become a crucial issue in the field of resource recycling. Pyrometallurgy, due to its large processing capacity and adaptability to raw materials, is often used to process waste circuit boards. However, if halogen-containing waste circuit boards are directly subjected to pyrometallurgical treatment without pretreatment, the halogens will be released at high temperatures, resulting in complex flue gas composition, equipment corrosion, and increased environmental pressure.

[0003] Pyrolysis can be used as an effective pretreatment method to remove halogens and some organic matter through low-temperature pyrolysis, yielding pyrolysis residue. However, the residue has a complex composition (containing metals, glass fibers, pyrolytic carbon, etc.), which can easily lead to problems such as high slag viscosity, difficulty in separating matte slag, and dispersion of valuable metals when directly smelted, making it difficult to adapt to existing smelting systems.

[0004] Co-smelting pyrolysis residue with copper sulfide ore to capture precious metals in copper matte is a potential approach. However, a systematic method is currently lacking that can organically combine front-end dehalogenation, complex slag system control, and the directional distribution of multiple elements in copper matte, slag, and flue gas to achieve stable and efficient co-processing. Summary of the Invention

[0005] To address these issues, this invention provides a method for co-smelting pyrolysis residue and copper sulfide ore, which solves the above problems.

[0006] A method for co-smelting pyrolysis residue and copper sulfide ore, comprising:

[0007] S1. The halogen-containing waste circuit board is subjected to thermal dehalogenation treatment to obtain pyrolysis residue;

[0008] S2. The pyrolysis residue is mixed with copper sulfide ore and flux to obtain the material to be fed into the furnace.

[0009] S3. The material fed into the furnace is sent into an oxygen-enriched side-blown molten pool furnace for smelting, and copper matte phase, slag phase and flue gas phase are formed under side-blown oxygen-enriched conditions.

[0010] S4. By controlling the smelting temperature, oxygen supply intensity, and slag composition, Au and Ag are enriched in the copper matte phase, and at least one of Pb, Zn, Sb, As, and Bi is distributed in a targeted manner among the copper matte phase, slag phase, and flue gas phase.

[0011] S5. Discharge the copper matte phase, slag phase and flue gas phase respectively, and perform subsequent recycling treatment on the copper matte phase.

[0012] Furthermore, the pyrolysis dehalogenation process is carried out in an oxygen-free or low-oxygen atmosphere, with a pyrolysis temperature of 500-700℃ and a holding time of 30-120 min.

[0013] Furthermore, the thermal dehalogenation process is carried out using Ca(OH)2-assisted dehalogenation and / or steam-assisted enhanced dehalogenation.

[0014] Furthermore, the pyrolysis residue is a carbon-rich black copper residue obtained after pyrolysis and dehalogenation of waste circuit boards. The carbon-rich black copper residue contains a metallic phase, a glass fiber phase, and a pyrolytic carbon phase, and contains at least three components from Cu, Fe, SiO2, Al2O3, CaO, and C.

[0015] Furthermore, the mass ratio of the pyrolysis residue to the copper sulfide ore is 1:(2-15), and the flux includes at least one of SiO2 regulator and CaO regulator.

[0016] Furthermore, the smelting temperature is 1150-1250℃, and the grade of the formed copper matte phase is controlled to be 50-70wt%.

[0017] Furthermore, the slag is controlled to be FeO during the smelting process. x The slag system is based on SiO2-Al2O3, and the amount of SiO2 added is adjusted to keep the slag in a suitable liquid phase zone, thereby improving the slag fluidity and promoting matte slag separation.

[0018] Furthermore, the Al2O3 content in the slag is controlled to be below 17wt%.

[0019] Furthermore, a CaO regulator is added, wherein the amount of CaO added is 1-8 wt% based on the total furnace charge mass, to adjust the slag composition and increase the distribution ratio of Se and / or Te to the copper matte phase.

[0020] Furthermore, the target allocation includes: Pb preferentially entering the copper matte phase, Zn and / or Sb preferentially entering the slag phase, and As and / or Bi preferentially volatilizing into the flue gas phase.

[0021] The method for co-smelting pyrolysis residue with copper sulfide ore in this application has the following specific advantages:

[0022] 1. The present invention first performs thermal dehalogenation treatment on waste circuit boards to achieve front-end cleaning treatment of halogen-containing waste circuit boards, which can significantly reduce the halogen content in the residue and reduce the risk of halogen contamination in the subsequent pyrometallurgical smelting process.

[0023] 2. This invention co-melts pyrolysis residue with copper sulfide ore, utilizing the matte-forming gold-capturing mechanism to preferentially enrich Au and Ag in the copper matte phase, thereby providing a high-grade enrichment carrier for subsequent blowing, electrolysis and anode mud treatment, and improving the comprehensive recovery efficiency of rare and precious metals.

[0024] 3. The pyrolysis residue is a complex multi-component system containing metallic phase, glass fiber phase and pyrolytic carbon phase. This invention achieves stable synergistic smelting of this complex secondary resource and copper sulfide ore by selecting an oxygen-enriched side-blown smelting furnace and cooperating with reasonable slag system control, thereby improving the adaptability of secondary resources to the existing copper smelting process. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 The flowchart illustrates a method for co-smelting pyrolysis residue and copper sulfide ore according to an embodiment of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] This invention provides a method for co-smelting pyrolysis residue and copper sulfide ore.

[0029] Please see Figure 1 The diagram shows a flowchart of a method for co-smelting pyrolysis residue and copper sulfide ore according to this application.

[0030] In the following embodiments, unless otherwise specified, the raw materials, equipment, reagents and testing methods used are all conventionally available in the art.

[0031] Example 1: Co-smelting of waste circuit board pyrolysis residue and copper sulfide ore.

[0032] First, raw material preparation is carried out. Halogen-containing waste circuit boards are selected as raw materials and crushed to control the particle size to no more than 20mm. The waste circuit boards contain metallic copper, iron, tin, lead, zinc, precious metals, as well as glass fiber and resin-based organic components, and contain bromine-based flame retardant components. Conventional copper concentrate is selected as the copper sulfide ore, with chalcopyrite and bornite as the main copper-bearing minerals, and also contains a certain amount of iron and sulfur, which can serve as a source of matte-forming components during co-smelting. Quartz sand is selected as the SiO2 regulator and quicklime as the CaO regulator as the flux.

[0033] Then, thermal desalination continues. The crushed waste circuit boards are placed in a pyrolysis device and heated to 600°C at 10°C / min under an oxygen-free atmosphere, and held at that temperature for 60 min to pyrolyze the organic components and obtain pyrolysis residue.

[0034] In this embodiment, Ca(OH)₂ is added as an auxiliary dehalogenating agent during pyrolysis to enhance the capture of hydrogen bromide and organic bromine components released during pyrolysis. After treatment, the halogen content in the pyrolysis residue is significantly reduced, which can effectively alleviate the flue gas purification pressure in subsequent pyrometallurgical smelting.

[0035] Next, the furnace charge is prepared. The obtained pyrolysis residue is crushed and sieved to 0-10mm, and then mixed with copper sulfide ore at a mass ratio of 1:6. Quartz sand and quicklime are added as flux, with the amount of quicklime added being 3wt% of the total furnace charge mass. To ensure uniform mixing, the pyrolysis residue, copper sulfide ore, and flux are first mechanically mixed before being sent to the silo for later use.

[0036] Next, oxygen-enriched side-blown smelting is carried out. The prepared furnace charge is continuously added to the oxygen-enriched side-blown smelting furnace, and smelting is carried out at 1180-1220℃. During the smelting process, oxygen is supplied by side-blowing oxygen enrichment, and the target grade of copper matte phase is controlled within the range of 50-70wt%. During the smelting process, quartz sand is added to adjust the slag to FeO. x A SiO2-Al2O3-based slag system is used, and the slag is kept in the liquid phase to improve slag fluidity and matte-slag separation. The Al2O3 content in the slag is controlled to be below 17 wt%.

[0037] Finally, phase separation and recovery are performed. After smelting, clearly separated copper matte phase, slag phase, and flue gas phase are obtained. The copper matte phase collects at the bottom of the furnace and is discharged, the slag phase is discharged from the top, and the flue gas phase is sent to the subsequent dust collection and purification system through the flue.

[0038] Detection and analysis revealed that in this embodiment, Au and Ag were mainly enriched in the copper matte phase; Pb preferentially distributed to the copper matte phase; Zn and Sb mainly entered the slag phase; and As and Bi mainly volatilized with the flue gas and were captured in the subsequent dust collection system. This indicates that the method described in this invention can effectively enrich rare and precious metals and achieve phase separation and migration of associated impurity elements during the co-smelting of pyrolysis residues and copper sulfide ore.

[0039] Example 2: Co-melting after steam-assisted deep dehalogenation.

[0040] The difference between this embodiment and Embodiment 1 is that the thermal dehalogenation step uses a steam-assisted enhanced dehalogenation method, while the remaining steps are basically the same.

[0041] Thermal dehalogenation is performed. The crushed halogen-containing waste circuit boards are placed in a pyrolysis device and heated to 600°C in an oxygen-free atmosphere. During the heat preservation stage, steam is introduced at a flow rate of 0.1 g / min and the holding time is 60 min.

[0042] The introduction of steam can improve the carbonaceous structure of pyrolysis residue, transforming the originally dense pyrolysis carbon into a porous and loose structure, thereby improving the escape capacity of volatile bromides and mass transfer efficiency. After this treatment, the bromine removal rate in waste circuit boards can be further improved, and the halogen residue in the pyrolysis residue is significantly reduced.

[0043] The furnace charge is prepared by mixing the pyrolysis residue after steam-assisted deep dehalogenation with copper sulfide ore at a mass ratio of 1:8, adding quartz sand and quicklime as flux, and adding CaO at a mass of 5 wt% of the total furnace charge.

[0044] Smelting is then carried out. The prepared feed materials are sent into an oxygen-enriched side-blown smelting furnace and smelted together at around 1200℃, controlling the copper matte phase grade to be about 60wt%. The amount of quartz sand added is adjusted to keep the slag system in the liquid phase region, controlling the Al2O3 content to be below 17wt%.

[0045] In this embodiment, due to the lower halogen content in the pyrolysis residue, the corrosive load and halogen-containing pressure of the flue gas system during smelting are further reduced, the furnace conditions are more stable, the smelting process is more stable, and the separation of copper matte from slag is clearer. Au and Ag are still mainly enriched in the copper matte phase.

[0046] In addition, the migration tendency of Se and Te to the copper matte phase is enhanced when 5wt% CaO is added, which is beneficial for their further enrichment and recovery in subsequent copper matte blowing, electrolysis and anode mud treatment.

[0047] Example 3: Synergistic melting under conditions of high proportion of pyrolysis residue.

[0048] This embodiment is used to illustrate the adaptability of the method of the present invention to a higher proportion of pyrolysis residue.

[0049] Thermal dehalogenation was performed. The same method as in Example 1 was used to thermally dehalogenate the halogen-containing waste circuit boards, that is, the temperature was raised to 600°C and held for 60 minutes in an oxygen-free atmosphere, while Ca(OH)2 was used to assist in dehalogenation.

[0050] The pyrolysis residue was mixed with copper sulfide ore at a mass ratio of 1:3, and quartz sand and quicklime were added to adjust the slag system. The amount of quartz sand was appropriately increased compared with Example 1 to compensate for the influence of the fluctuation of SiO2 and Al2O3 brought in by the higher proportion of pyrolysis residue on the slag shape.

[0051] Smelting is carried out in an oxygen-enriched side-blown smelting furnace at 1150-1200℃, with the oxygen supply intensity controlled to maintain the copper matte phase grade at 50-60wt%.

[0052] Due to the increased proportion of pyrolysis residue and the increased introduction of glass fiber and residual carbon into the furnace charge, the slag is kept in good fluidity and the Al2O3 content is controlled to not exceed 17wt% by increasing the SiO2 adjustment amount and appropriately adding CaO during the smelting process.

[0053] The results show that even with a high proportion of pyrolysis residue, relatively stable matte-slag separation can still be achieved by controlling appropriate oxygen supply intensity, copper matte grade, and slag composition. Au and Ag remain enriched in the copper matte phase, Zn and Sb tend to enter the slag phase, while As and Bi mainly enter the flue gas phase.

[0054] This embodiment illustrates that the method of the present invention has a certain adaptability to different pyrolysis residue addition ratios, and can achieve stable operation by adjusting the flux and oxygen supply conditions according to fluctuations in raw material composition.

[0055] Comparative Example 1: Waste circuit boards without dehalogenation treatment were directly co-smelted. To illustrate the importance of the thermal dehalogenation step, halogen-containing waste circuit board fragments without thermal dehalogenation treatment were directly mixed with copper sulfide ore and flux and then fed into an oxygen-enriched side-blown smelting furnace for smelting. The remaining conditions were basically the same as in Example 1.

[0056] The results show that untreated waste circuit boards, still containing a large amount of organic components and halogen flame-retardant components, are more likely to cause an increase in the halogen load of the flue gas system and an increase in flue gas purification pressure during the smelting process, and the furnace conditions fluctuate more significantly; at the same time, it is not conducive to stable matte slag separation. Compared with Example 1, using thermal dehalogenation pretreatment followed by co-smelting is more conducive to achieving a clean and stable smelting process.

[0057] Comparative Example 2: Co-melting without CaO regulator. To illustrate the role of the CaO regulator, the process conditions were basically the same as in Example 2, but no CaO regulator was added during the batching process; only SiO2 regulator was added to control the slag shape.

[0058] The results show that, although synergistic smelting of pyrolysis residue and copper sulfide ore can still be achieved without the addition of CaO, and Au and Ag can be enriched in the copper matte phase, the enrichment trend of Se and Te in the copper matte phase is relatively weak, and the slag system adjustment range is also relatively narrow. This indicates that the appropriate addition of CaO helps to further optimize the elemental distribution behavior and improve the controllability of slag composition.

[0059] Comparative Example 3: Smelting under conditions of high Al2O3 content. To illustrate the importance of controlling the Al2O3 content in the slag, the proportion of pyrolysis residue was increased and the amount of SiO2 regulator added was reduced in this comparative example, so that the Al2O3 content in the slag exceeded 17 wt%. The other conditions were basically the same as in Example 1.

[0060] The results showed that when the Al2O3 content in the slag was too high, the slag viscosity increased, the fluidity decreased, which was not conducive to matte-slag separation and easily caused local furnace condition fluctuations, leading to a decrease in the stability of the smelting process. Compared with Example 1, controlling the Al2O3 content to below 17 wt% was more conducive to maintaining the slag in the liquid phase region and ensuring the stable progress of the synergistic smelting process.

[0061] It should be noted that, in the method described in this invention, the mass ratio of pyrolysis residue to copper sulfide ore can be adjusted according to the raw material composition, target copper matte grade, and slag flowability requirements, and is typically selected in the range of 1:(2-15). The smelting temperature is preferably 1150-1250℃, and the target copper matte phase grade is preferably controlled at 50-70wt%.

[0062] In practical industrial applications, the content of SiO2, Al2O3, CaO, Fe, and C in the pyrolysis residue can be adjusted in conjunction with the levels of quartz sand, quicklime, and oxygen supply to maintain the FeO content. x The SiO2-Al2O3-based slag system is located in a suitable liquid phase region, which enhances the enrichment and migration of valuable elements to the target phase.

[0063] The copper matte phase obtained in step S5 can be further processed into blowing, electrolytic refining and anode mud recovery processes to achieve high-value recovery of elements such as Au, Ag, Se, and Te. Elements such as As and Bi volatilized in the flue gas phase can be separated and safely disposed of through dust collection and flue gas purification systems. As for the slag phase, it can be subsequently utilized for resource recovery or harmless treatment according to its composition.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for co-smelting pyrolysis residue and copper sulfide ore, characterized in that, include: S1. The halogen-containing waste circuit board is subjected to thermal dehalogenation treatment to obtain pyrolysis residue; S2. The pyrolysis residue is mixed with copper sulfide ore and flux to obtain the material to be fed into the furnace. S3. The material fed into the furnace is sent into an oxygen-enriched side-blown molten pool furnace for smelting, and copper matte phase, slag phase and flue gas phase are formed under side-blown oxygen-enriched conditions. S4. By controlling the smelting temperature, oxygen supply intensity, and slag composition, Au and Ag are enriched in the copper matte phase, and at least one of Pb, Zn, Sb, As, and Bi is distributed in a targeted manner among the copper matte phase, slag phase, and flue gas phase. S5. Discharge the copper matte phase, slag phase and flue gas phase respectively, and perform subsequent recycling treatment on the copper matte phase.

2. The method for co-smelting pyrolysis residue and copper sulfide ore according to claim 1, characterized in that, The pyrolysis dehalogenation process is carried out in an oxygen-free or low-oxygen atmosphere, with a pyrolysis temperature of 500-700℃ and a holding time of 30-120 min.

3. The method for co-smelting pyrolysis residue and copper sulfide ore according to claim 1, characterized in that, The thermal dehalogenation process is carried out using Ca(OH)2-assisted dehalogenation and / or steam-assisted enhanced dehalogenation.

4. The method for co-smelting pyrolysis residue and copper sulfide ore according to claim 1, characterized in that, The pyrolysis residue is a carbon-rich black copper residue obtained after pyrolysis and dehalogenation of waste circuit boards. It contains a metallic phase, a glass fiber phase and a pyrolytic carbon phase, and contains at least three components from Cu, Fe, SiO2, Al2O3, CaO and C.

5. The method for co-smelting pyrolysis residue and copper sulfide ore according to claim 1, characterized in that, The mass ratio of the pyrolysis residue to the copper sulfide ore is 1:(2-15), and the flux includes at least one of SiO2 regulator and CaO regulator.

6. The method for co-smelting pyrolysis residue and copper sulfide ore according to claim 1, characterized in that, The smelting temperature is 1150-1250℃, and the grade of the formed copper matte phase is controlled to be 50-70wt%.

7. The method for co-smelting pyrolysis residue and copper sulfide ore according to claim 1, characterized in that, Controlling the slag to FeO during the smelting process x -SiO2-Al2O3 based slag system, and the slag is kept in the liquid phase region by adding SiO2.

8. The method for co-smelting pyrolysis residue and copper sulfide ore according to claim 1, characterized in that, The Al2O3 content in the slag is controlled to be below 17wt%.

9. The method for co-smelting pyrolysis residue and copper sulfide ore according to claim 1, characterized in that, A CaO regulator is added to the flux, wherein the amount of CaO added is 1-8 wt% based on the total furnace charge mass, to adjust the slag composition and increase the distribution ratio of Se and / or Te to the copper matte phase.

10. A method for co-smelting pyrolysis residue and copper sulfide ore according to claim 1, characterized in that, The target allocation includes: Pb preferentially enters the copper matte phase, Zn and / or Sb preferentially enter the slag phase, and As and / or Bi preferentially volatilize into the flue gas phase.

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