Chamber Furnace-Middle East Leader in Recycled Copper
Conductivity fluctuations after annealing of miscellaneous copper ingots and manual handling injury rates
Recycled copper is an important part of resource recycling and sustainable development. However, the production of recycled copper faces a number of challenges, one of which is the high conductivity fluctuation of the tramp copper ingot after annealing. The electrical conductivity of copper is crucial for its applications, especially in power and electronics. Fluctuations in conductivity are often closely related to the grain structure, impurity distribution, internal stresses and the homogeneity of the annealing process within the ingot. The presence of impurity elements (e.g. oxygen, sulphur, iron, etc.) significantly reduces the electrical conductivity of copper. The purpose of annealing is to eliminate the internal stresses caused by cold work hardening through the heating and cooling process, and to promote grain growth and recrystallisation, thereby improving the electrical conductivity and plasticity of copper. Insufficient or uneven annealing, unsatisfactory grain structure, or ineffective solid solution or precipitation of impurities can lead to fluctuations in conductivity, which can affect product quality and even lead to customer returns.
In addition, traditional methods of handling copper ingots often rely on extensive manual labour, which is not only inefficient, but also carries a high risk of injury. The 67% year-on-year increase in injuries faced by the Middle East's leading recycled copper producer highlights the safety and efficiency shortcomings of the traditional production model, and the urgent need to introduce intelligent and automated solutions.
Unmanned Chamber Furnace Cluster (32 Zones with Dynamic Temperature Control)
In order to solve the problem of fluctuating conductivity of recycled copper ingots and to make the production process intelligent and unmanned, the company introduced an unmanned chamber furnace cluster with 32 zones with dynamic temperature control. The chamber furnace is a common type of cyclic heat treatment furnace, suitable for annealing of batch work
pieces. The unmanned furnace group and fine temperature control are its core advantages:
1. Furnace group layout and unmanned operation: The furnace group consists of several chamber furnaces, which are dispatched and managed via an automated control system. The loading and unloading of workpieces, opening and closing of the furnace doors, etc. are performed by robots or automated equipment, thus realising the unmanned operation of the entire annealing process. This layout not only improves the production efficiency, but also significantly reduces the risk of injury caused by manual operation. 2. 32-zone dynamic temperature control.
2. 32-zone dynamic temperature control: This is the key technology to ensure the stability of the conductivity of copper ingots. Conventional chamber furnaces usually have only a few temperature zones, which makes it difficult to achieve fine temperature control in the furnace. The furnace complex divides each chamber furnace into up to 32 independent temperature zones, each equipped with a separate heating element and a high-precision temperature sensor. Each zone is equipped with its own heating elements and high-precision temperature sensors. Advanced control algorithms enable individual temperature control and dynamic regulation of each zone, ensuring the ultimate uniformity of the temperature field inside the furnace. This means:
◦ Temperature gradient optimisation: The temperature gradient in the furnace can be precisely controlled with respect to the size and stacking of the ingots, ensuring that the ingots are heated uniformly from the surface to the core, avoiding localised overheating or underheating.
◦ Dynamic response: The system can monitor the temperature change in the furnace in real time and dynamically adjust the heating power in each temperature zone according to the heat absorption of the workpiece and the process requirements to ensure the accurate tracking of the temperature curve.
◦ Elimination of internal stress and promotion of recrystallisation: Precise and uniform temperature control helps to fully eliminate internal stresses in the copper ingot.
also promotes uniform grain growth and recrystallisation, which results in an ideal microstructure, maximised electrical conductivity and reduced volatility.
AGV logistics system
In order to solve the problem of work injuries caused by manual handling and to improve the logistics efficiency, the solution introduces an AGV (Automated Guided Vehicle) logistics system, which realises the full automation of material handling:
1. Automated material flow: The AGV system is responsible for the full automated handling of the ingots from the entry into the storage area, the waiting time in front of the furnace, loading and unloading in the furnace, the cooling after the furnace, and the exit from the storage area. According to the preset paths and scheduling instructions, the AGVs precisely transport the copper ingots to the designated positions
and seamlessly connect with the automated loading and unloading system of the furnaces.
2. Path Optimisation and Obstacle Avoidance: The AGV system is equipped with intelligent path planning and obstacle avoidance functions, capable of automatically selecting the optimal path and avoiding obstacles according to the production tasks and on-site conditions to ensure smooth and safe material flow. This completely eliminates collision, fall and other potential safety hazards in manual handling. 3.
3. Integration with production system: AGV system is deeply integrated with production management system such as furnace group control system and warehouse management system (WMS), which realises the synchronization of information flow and logistics. Production instructions can be directly sent to the AGV system to achieve on-demand delivery and accurate feeding, improving the flexibility and efficiency of production.
Real Time Copper Crystallinity Monitoring
In order to further ensure the stability of the electrical conductivity of annealed copper ingots, the programme introduces real time copper crystallinity monitoring. This is a major breakthrough from traditional off-line testing.
1. Monitoring principle: The electrical conductivity of copper is closely related to its internal grain structure and crystallinity. The higher the crystallinity, the better the grains, and the higher the electrical conductivity. Real-time monitoring technology could be based on non-contact methods, e.g. electromagnetic induction, ultrasound or X-ray diffraction, for online inspection of copper ingots during the annealing process to assess the state of crystallisation.
2. On-line feedback and process optimisation: The real-time monitoring system provides real-time feedback of crystallinity data to the furnace control system. If the crystallinity is not as expected, the system can immediately adjust the annealing parameters (e.g., extending the holding time, fine-tuning the temperature profile) to ensure that each ingot achieves the optimum crystallisation state. This closed-loop control mechanism increases the stability of the conductivity from ±12% IACS to 101% IACS (±0.8%), enabling precise control of product quality.
3. Data traceability and quality management: The crystallinity data is linked to the production batch and stored in the cloud database, providing a detailed basis for product quality traceability. This not only meets the strict requirements of customers for product quality, but also provides data support for internal quality management and process improvement.
The comprehensive application of these intelligent, unmanned and fine control technologies has enabled the Middle East copper recycling leader to make significant breakthroughs in product quality, production efficiency, production safety and labour cost control, and become a model in the industry.