Method for mixing and granulating copper concentrate and waste circuit board

Abstract

The application belongs to the technical field of waste circuit board pyroprocessing, and discloses a method for mixing and granulating copper concentrate and waste circuit boards. The method removes electronic components by two-stage temperature control processing of the waste circuit boards, crushes the copper concentrate and waste circuit board light boards, adjusts the mixing ratio of the crushed copper concentrate and waste circuit board light boards, and then controls the elevation angle, rotating speed and water spraying amount of the granulator, so that the copper concentrate and waste circuit boards are combined at high strength into mixed particles. The mixed particles quickly sink to the lower part of the molten pool after entering the smelting system, so that the heat of resin combustion is transferred to the reaction zone and fully combusted, the heat energy utilization rate of the waste circuit boards is improved, and the effective recovery of metal resources in the waste circuit boards is realized. The method has simple granulation process and is suitable for large-scale industrial production.

Description

Technical Field

[0001] This application relates to the field of pyrometallurgical treatment technology for waste circuit boards, and more particularly to a method for granulating copper concentrate and waste circuit boards. Background Technology

[0002] Waste circuit boards are mainly composed of electronic components, organic reinforced resin, glass fiber, and copper foil, with a metal content generally exceeding 40%. These include common metals such as Cu, Fe, Ni, and Zn, as well as precious metals like Au, Ag, Pt, and Pd, and a large amount of recyclable materials, making them a veritable "urban mine" with high recycling value. With rapid societal development, the demand for copper from traditional industries such as electrical engineering, machinery manufacturing, and infrastructure is constantly increasing. Simultaneously, the rapid development of emerging industries such as wind power, solar power, and new energy vehicles is also significantly boosting the demand for copper, presenting a major development opportunity for the copper non-ferrous metals industry. However, copper mineral resources are currently very scarce, with a resource self-sufficiency rate of only about 30%. Using waste circuit boards as raw material for pyrometallurgical copper smelting has advantages such as low energy consumption, small investment, and simple processes, and has gradually become an important way for my country to address its copper resource shortage.

[0003] Traditional processes employ a method of "separate granulation of copper concentrate + direct addition of blocky waste circuit boards." However, due to their low density and significant differences in ignition points, these blocky waste circuit boards float on the surface of the molten pool and burn after entering the furnace. Only 30%-40% of the heat is transferred to the reaction zone, and a large amount of organic matter loses its sensible heat through the flue gas. Furthermore, the lightweight waste circuit board fragments form high-metal-content airborne dust in the furnace turbulence, significantly increasing the dust concentration, far exceeding the processing limit of the ISA furnace dust return system. This results in excessively high local temperatures in the furnace and rising flue section, leading to heat loss.

[0004] Therefore, in order to address the issue of heat loss during the co-processing of waste circuit boards in oxygen-enriched pyrometallurgical smelting, which involves handling blocky waste circuit boards and lightweight waste circuit board fragments, a mixed granulation method is needed to improve the heat utilization rate of waste circuit boards. Summary of the Invention

[0005] This application addresses the aforementioned problems by providing a method for granulating copper concentrate and waste circuit boards. By adjusting and optimizing specific parameters such as the mixing ratio of copper concentrate and waste circuit boards, the tilt angle and rotation speed of the disc granulator, the granulation time, and the water volume, the pelletizing rate and drop strength of the mixed particles are ensured, the heat release mode is optimized, the heat energy utilization rate of waste circuit boards is improved, the load on the copper smelting flue gas system from the co-processing of waste circuit boards is reduced, and coal-fired energy substitution is achieved in the copper smelting process.

[0006] This application provides a method for granulating copper concentrate and waste circuit boards, the method comprising the following steps: S1, the waste circuit board undergoes a two-stage temperature-controlled treatment to obtain a bare waste circuit board; The first stage of the two-stage temperature control process has a temperature of 180℃ and a time of 15 minutes; the second stage of the two-stage temperature control process has a temperature of 250℃ and a time of 10 minutes. S2, after crushing the waste circuit board blank and copper concentrate, mix them in a mass ratio of (3-10):100 to obtain a mixture; S3. After the mixture is stirred evenly, water is sprayed on it and granulation is performed to obtain mixed granules.

[0007] Furthermore, the crushing described in S2 employs a three-stage crushing process consisting of plate shearing, biaxial crushing, and ball milling shaping.

[0008] Furthermore, the particle size of the crushed waste circuit board blanks and copper concentrate is 0.25-0.75mm.

[0009] Furthermore, the water atomization particle size of the sprayed water is 50-200μm, the pressure is 0.2-0.8 MPa, and the dosage is 0.5-2t / h.

[0010] Furthermore, the granulation speed is 5-15 r / min and the tilt angle is 40-45°.

[0011] Furthermore, the granulation time is 5-8 minutes.

[0012] Furthermore, in the mixture of S2, the proportion of particles with a particle size of 0.25-0.75 mm is ≥90%, and the moisture content is ≤5%.

[0013] Furthermore, the moisture content of the mixed particles in S3 is 8%-12%, and the particle size is 6-14 mm.

[0014] Furthermore, the stirring speed in S3 is 20-50 rpm.

[0015] This application also provides an application of the mixed particles obtained by the above method in an Isa furnace smelting system.

[0016] Beneficial effects: 1. This application provides a method for granulating copper concentrate and waste circuit boards. The method involves removing electronic components from the waste circuit boards through a two-stage temperature-controlled process, crushing the copper concentrate and the bare waste circuit boards, adjusting and optimizing the mixing ratio of copper concentrate and bare waste circuit boards to achieve the target particle size, and then controlling specific parameters such as the granulator's elevation angle, rotation speed, and water spray volume to achieve a high-strength bond between the copper concentrate and the bare waste circuit boards into mixed particles. After entering the smelting system, the mixed particles quickly sink to the lower part of the molten pool, allowing the heat from resin combustion to be transferred to the reaction zone for complete combustion. This method solves the problem of heat loss from blocky waste circuit boards and lightweight waste circuit board fragments, improving the thermal energy utilization rate of waste circuit boards.

[0017] 2. Compared with the direct smelting process of copper concentrate without adding waste circuit boards, this application mixes crushed waste circuit board blanks with copper concentrate at a mass ratio of (3-10):100, and processes the waste circuit board blanks while smelting the copper concentrate. This increases the contribution of heat generated by the waste circuit board blanks to the heat income to 11.81%-34.77%, and reduces the proportion of self-generated heat in copper concentrate smelting from 73.93% to 65.3%. For every ton of waste circuit board processed, coal consumption can be reduced by 0.45-0.6 tons, CO2 emissions can be reduced by 1.1-1.5 tons, and the thermal energy utilization rate is significantly improved.

[0018] 3. By relying on large-scale integrated smelting enterprises and using pyrometallurgical smelting to co-process waste circuit boards, the high-calorific-value resins in the waste circuit boards can be used as fuel for smelting, thereby reducing the amount of coke or coal used.

[0019] 4. This application utilizes the characteristic that copper concentrate must be granulated separately when processed by the Isa furnace smelting system. By adjusting and optimizing the specific parameters of the mixing ratio of copper concentrate and waste circuit board blanks, the tilt angle and speed of the disc granulator, the granulation time, and the water volume, the resulting pellets have a moisture content of ≤12%, a mixed particle size of 6-14mm, a pelletizing rate of over 90%, a compressive strength of over 50 N / particle, a drum breakage rate of ≤12%, and a drop strength of ≥5 times (impact of a 500 mm steel plate). The overall strength of the pellets meets the feeding requirements of the Isa furnace smelting system. The granulation process is simple and suitable for large-scale production.

[0020] 5. The mixed particles obtained in this application are subsequently transported to the Isa furnace smelting system. In the smelting system, crude copper captures rare and precious metals from waste circuit boards. Copper and rare and precious metals such as gold, silver, platinum, and palladium are recovered through leaching and electrolytic refining processes. Therefore, this granulation process can also achieve effective recycling of metal resources. Attached Figure Description

[0021] Figure 1 This is a process flow diagram related to the embodiments of this application.

[0022] Figure 2This is a particle size distribution diagram of the mixed granulation involved in the embodiments of this application.

[0023] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0024] To better understand the above technical solutions, exemplary embodiments of this disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of this disclosure are shown in the drawings, it should be understood that this disclosure can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of this disclosure to those skilled in the art.

[0025] Experimental principle: This application leverages the characteristic of the Isa furnace smelting system that copper concentrate must be granulated separately during processing. It removes electronic components from waste circuit boards through a two-stage temperature-controlled treatment, crushes the copper concentrate and the waste circuit board blanks, adjusts and optimizes the mixing ratio of copper concentrate and waste circuit board blanks to achieve the target particle size, and then controls specific parameters such as the granulator's elevation angle, rotation speed, and water spray volume to achieve a high-strength bond between the copper concentrate and waste circuit board into mixed particles. The resulting mixed particles achieve a pelletizing rate of over 90% and a drop strength of ≥5 times (500 mm). (mm steel plate impact), the overall strength of the spheres meets the feeding requirements of the Isa furnace smelting system; compared with the problem of heat loss when blocky waste circuit boards and lightweight waste circuit board fragments are directly added, after mixing and granulation, the mixed particles enter the smelting system and quickly sink to the lower part of the molten pool. The heat of resin combustion is transferred to the reaction zone and fully utilized. In the subsequent smelting system, crude copper captures rare and precious metals in waste circuit boards. Copper and rare and precious metals such as gold, silver, platinum, and palladium are recovered through leaching, electrolytic refining and other processes. Therefore, this granulation process can improve the heat utilization rate of waste circuit boards while achieving effective recycling of metal resources.

[0026] All experimental data were obtained in a laboratory environment that meets the requirements of ISO / IEC 17025:2017, and the test methods strictly followed the relevant standards and requirements. Each experiment was repeated 3 times, and the average value was taken. The standard deviation was ≤5%.

[0027] 1. Ball formation rate determination Reference standard: GB / T 10322.7-2004 "Determination of particle size distribution of iron ore by sieve analysis"; Operating steps: Take 500 g of granulated mixed granules and manually remove obviously deformed granules; use a standard sieve set (6 mm, 8 mm, 10 mm, 12 mm, 14 mm) for mechanical sieving (amplitude 2 mm, frequency 50 Hz, sieving time 5 min); weigh the mass of granules in the 6-14 mm range and calculate the percentage, which is the pelleting rate.

[0028] Acceptance criteria: Isa furnaces require a feed pelleting rate of ≥85%, while the embodiment of this application requires ≥90%.

[0029] 2. Compressive strength determination Reference standard: ISO 4700:2015 "Determination of compressive strength of iron ore particles"; Operating steps: Randomly select 30 intact particles (6-8 mm) and place them in a constant temperature and humidity environment (25℃, 50% RH) for equilibration for 24 h; use a universal testing machine, set the loading rate to 5 mm / min, and record the maximum pressure at the moment of particle breakage; take the average value of the test results of 30 particles as the compressive strength.

[0030] Qualification criteria: Isa furnace feed requirement ≥ 50 N / piece (smelter enterprise standard).

[0031] 3. Drum breakage rate Reference standard: ASTM E382-2020, "Standard Test Method for Resistance of Iron Ore Particles to Crushing". Operating steps: Take 500 g of mixed granules and place them in a rotating drum (Φ1000×500 mm, smooth inner wall); set the rotation speed to 25 rpm and run for 15 min; use a 6.3 mm sieve to calculate the percentage of material passing through the sieve, which is the breakage rate.

[0032] The standard for compliance is: the breakage rate should be ≤15% according to the prevailing standards in the copper smelting industry.

[0033] 4. Drop Intensity Reference standard: Improved method of ASTM D440-86, "Standard Test Method for Fall Crushing of Coal"; Operating procedures: Randomly select 10 intact particles (6-8 mm) and equilibrate them in a constant temperature and humidity environment (25℃, 50% RH) for 24 h; drop the particles freely from a height of 500 mm onto a 10 mm thick steel plate, which is rigidly fixed to a cement base; repeat the drop test on each particle until visible cracks or breakage occur, and record the number of drops before breakage; take the average number of drops of the 10 particles as the drop intensity.

[0034] Criteria for qualification: Although oxygen-enriched top-blown molten pool smelting technology such as the Isa furnace improves reaction efficiency by strengthening the stirring of the molten pool, it has extremely stringent requirements on the physical and chemical properties of the materials fed into the furnace: the particles must have a high pelletizing rate (≥85%) and drop resistance (≥5 times of 500 mm free fall), and the particle transfer breakage rate ≤3% to ensure that the structural integrity is maintained under the impact of the spray gun airflow and the high-temperature molten pool environment, so as to achieve the step-by-step release of heat energy and efficient metal capture.

[0035] Based on the above description, embodiments of the method for granulating copper concentrate and waste circuit boards according to this application are presented.

[0036] First embodiment: Low-proportion circuit board co-granulation (waste circuit board bare board to copper concentrate ratio 3:100) In this embodiment, the raw material composition of copper concentrate and waste circuit board blanks was determined, and the test results are shown in Table 1 below: Table 1 Composition of Copper Concentrate and Waste Circuit Board Raw Materials The copper concentrate measured in the above experiment was mixed with waste circuit boards and granulated. Process parameters: The detinning process yields bare waste circuit boards: two-stage temperature control (180℃×15 min + 250℃×10 min), with an electronic component removal rate ≥98%; the waste circuit boards include block-shaped waste circuit boards and lightweight waste circuit board fragments. The particle size of the waste circuit board blank is 0.5-0.75 mm (75% of the total, GB / T 14260-2010 screening standard); the particle size of the copper concentrate is 0.25-0.75 mm. Granulation parameters: disc tilt angle 42°, rotation speed 10 r / min (n·sinα=6.7), water spray volume 1.2 t / h (atomized particle size 120 μm, pressure 0.5 MPa), granulation time 6 min.

[0037] Table 2 Performance test results of the mixed particles in this embodiment As shown in Table 2, the pelletizing rate of the mixed particles is 93% (the furnace entry standard is ≥85%), and the drop strength is 6 times (the furnace entry standard is ≥5 times, 500 mm free drop). This ensures the pelletizing rate and drop strength of the mixed particles, achieving efficient recycling of metal resources while the Isa furnace smelting system can also synergistically process blocky waste circuit boards and lightweight waste circuit board fragments.

[0038] Second embodiment: Medium-proportion circuit board co-granulation (waste circuit board bare board to copper concentrate ratio 7:100) The particle size of crushed waste circuit board blanks is 0.3-0.6 mm (accounting for 80%). Copper concentrate crushing particle size: 0.25-0.75 mm; Granulation parameters: disc tilt angle 45°, rotation speed 8 r / min (n⋅sinα=8⋅sin45°≈5.7), water spray volume 1.8 t / h (atomized particle size 80 μm, pressure 0.6 MPa), granulation time 7 min.

[0039] Table 3 Performance test results of the mixed particles in this embodiment As shown in Table 3, the pelletizing rate of the mixed particles is 91% (the furnace entry standard is ≥85%), and the drop strength is 5 times (the furnace entry standard is ≥5 times, 500 mm free drop). This ensures the pelletizing rate and drop strength of the mixed particles, achieving efficient recycling of metal resources while the Isa furnace smelting system can also synergistically process blocky waste circuit boards and lightweight waste circuit board fragments.

[0040] Third embodiment: High-proportion circuit board co-granulation (waste circuit board bare board to copper concentrate ratio 10:100) Broken particle size of circuit board blanks: 0.25-0.5 mm (accounting for 80%); Copper concentrate crushing particle size: 0.25-0.75 mm; Granulation parameters: disc tilt angle 40°, rotation speed 5 r / min (n⋅sinα=5⋅sin40°≈3.2), water spray volume 2 t / h (atomized particle size 50 μm, pressure 0.8 MPa), granulation time 8 min.

[0041] Table 4 Performance test results of the mixed particles in this embodiment As shown in Table 4, the pelletizing rate of the mixed particles is 90% (the furnace entry standard is ≥85%), and the drop strength is 5 times (the furnace entry standard is ≥5 times, 500 mm free drop). This ensures the pelletizing rate and drop strength of the mixed particles, achieving efficient recycling of metal resources while the Isa furnace smelting system can also synergistically process blocky waste circuit boards and lightweight waste circuit board fragments.

[0042] Fourth embodiment: Super-proportional granulation of circuit boards (comparative verification of waste circuit board bare board and copper concentrate ratio of 15:100). Broken particle size of circuit board blanks: 0.25-0.5 mm (accounting for 80%); Copper concentrate crushing particle size: 0.25-0.75 mm; Granulation parameters: disc tilt angle 40°, rotation speed 5 r / min (n⋅sinα=5⋅sin40°≈3.2), water spray volume 2 t / h (atomized particle size 50 μm, pressure 0.8 MPa), granulation time 8 min.

[0043] Table 5 Performance test results of the mixed particles in this embodiment As shown in Table 5, the pelletizing rate of the mixed particles is 72% (the furnace entry standard is ≥85%), and the drop strength is 4 times (the furnace entry standard is ≥5 times, 500 mm free drop). The pelletizing rate and drop strength of the mixed particles do not meet the furnace entry requirements of the Isa furnace melting system.

[0044] Fifth embodiment: This embodiment only changes the amount of waste circuit board bare board added in Embodiment 1, and compares the impact of different addition amounts on the Isa furnace system; Table 6 Summary of the main impacts of adding waste circuit boards on the Isa furnace system When the mixed particles burn, they exhibit a stepped heat release in the 1000-1200℃ range, lasting for ≥50 seconds, with an instantaneous peak heat release ≤800 kJ / kg·s (determined according to ISO 11357-3:2018 differential scanning calorimetry). Table 6 shows that the unit oxygen consumption of pulverized coal (wet) is 1153.25 Nm³. 3 / t, the oxygen consumption per unit area of ​​waste circuit board bare (wet) is 619.10 Nm³. 3 / t, the oxygen consumption per unit of copper concentrate is 131.93 Nm³. 3 The calorific value contribution of pulverized coal to the molten pool is 20410.5 kJ / t, while that of waste circuit board blanks is 10685.6 kJ / t. Therefore, adding 6.69 t / h of waste circuit board blanks can completely replace the calorific value contribution of pulverized coal, achieving zero fossil energy consumption. Thus, as the amount of waste circuit board blanks added gradually increases, the amount of pulverized coal added gradually decreases until the amount of waste circuit board blanks added exceeds 6.69 t / h, at which point the amount of pulverized coal added is 0 t / h. Determination of the ratio of waste circuit board blanks in mixed particles to copper concentrate (3-10):100: When the ratio of waste circuit board blanks to copper concentrate is (0-3):100, although the sum of the combustion heat and physical heat of the circuit board increases rapidly (from 0% to 11.81%), the amount of waste circuit board blanks processed is relatively small and the processing time is relatively long, making it unsuitable for processing large quantities of waste circuit boards.

[0045] When the ratio of waste circuit board blanks to copper concentrate is 10-12 and above: 100, although the sum of the combustion heat and physical heat of the circuit board gradually increases, the flue gas volume also gradually increases. When the ratio of waste circuit board blanks to copper concentrate is 10:100, the flue gas volume is 21.70 t / h, and the flue gas treatment capacity of the Isa furnace smelting system reaches its peak capacity. Sixth embodiment: The mixed particles prepared in Example 1 are fed into the Isa furnace smelting system.

[0046] After the mixed particles enter the smelting system, they quickly sink to the lower part of the molten pool, allowing the heat from the resin combustion to be transferred to the reaction zone and fully combusted. In the smelting system, crude copper captures rare and precious metals from waste circuit boards, and copper, gold, silver, platinum, palladium and other rare and precious metals are recovered through processes such as leaching and electrolytic refining, thus achieving effective recycling of metal resources from waste circuit boards.

[0047] Conclusion: Through systematic verification of six embodiments, the copper concentrate and waste circuit board mixing and granulation method provided in this application demonstrates significant advantages in process parameters, performance indicators, and overall benefits. By detinning treatment, optimizing the crushing process, doping ratio, and granulation parameters, within the ratio of waste circuit board bare plates to copper concentrate (3-10:100), the mixture and granulation parameters are well matched, and the performance indicators are stable and meet the standards. This achieves an average particle size of 8.5-10.2 mm, a pelletizing rate ≥89%, a compressive strength ≥50 N / particle, a drum breakage rate ≤12%, and a drop strength ≥5 times. When the proportion of circuit board bare plates exceeds 10:100, the particles become loose, and the pelletizing rate, drop strength, and compressive strength decrease significantly. This indicates that the amount of waste circuit board bare plates added must meet the final furnace feeding standards. Within the ratio of waste circuit board bare plates to copper concentrate (3-10:100), the pelletizing rate and compressive strength of the mixed particles after granulation can fully meet the furnace feeding standards. Within this range, the combined heat of combustion and physical heat of circuit boards increased from 11.81% to 34.77%, the surplus heat increased from 9.45% to 17.90%, and the combined heat of combustion and physical heat of pulverized coal decreased from 14.26% to 0. Therefore, the method of mixing copper concentrate with waste circuit boards for granulation achieves efficient recovery of metal resources while enhancing the utilization of thermal energy from waste circuit boards.

[0048] It should be noted that although preferred embodiments of this application have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

Claims

1. A method for granulating copper concentrate with waste circuit boards, characterized in that, The method includes the following steps: S1, the waste circuit board undergoes a two-stage temperature-controlled treatment to obtain a bare waste circuit board; The first stage of the two-stage temperature control process has a temperature of 180℃ and a time of 15 minutes; the second stage of the two-stage temperature control process has a temperature of 250℃ and a time of 10 minutes. S2, after crushing the waste circuit board blank and copper concentrate, mix them in a mass ratio of (3-10):100 to obtain a mixture; S3. After the mixture is stirred evenly, water is sprayed on it and granulation is performed to obtain mixed granules.

2. The method according to claim 1, characterized in that, The crushing described in S2 employs a three-stage crushing process: plate shearing, biaxial crushing, and ball milling shaping.

3. The method according to claim 1, characterized in that, The particle size of the crushed waste circuit board blanks and copper concentrate is 0.25-0.75mm.

4. The method according to claim 1, characterized in that, The water atomization particle size of the sprayed water is 50-200μm, the pressure is 0.2-0.8 MPa, and the dosage is 0.5-2 t / h.

5. The method according to claim 1, characterized in that, The granulation speed is 5-15 r / min, and the tilt angle is 40-45 degrees. ° .

6. The method according to claim 1, characterized in that, The granulation time is 5-8 minutes.

7. The method according to claim 1, characterized in that, The S2 mixture contains ≥90% particles with a size of 0.25-0.75 mm and a moisture content ≤5%.

8. The method according to claim 1, characterized in that, The mixed particles in S3 have a moisture content of 8%-12% and a particle size of 6-14 mm.

9. The method according to claim 1, characterized in that, The stirring speed in S3 is 20-50 rpm.

10. The application of a mixed particle obtained by the method of claim 1 in an Isa furnace smelting system.

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