Hot water separation process for copper and insulating material recovery from electric cable waste

Abstract

Recycling in the electric cable industry, especially the complete separation of metal and insulating material for re‐use, has always been a problem. The present processes to recover copper and insulating material from cable waste involve the grinding of cables into smaller pieces to improve metal liberation from the insulating material. The method results in fine thread‐shaped metal wedges in the insulating material, which prevents the re‐use of the insulating material. A ‘hot water separation process’ was used to recover metal and insulating material from cable waste, with no need to grind the cable into smaller pieces to improve the liberation of copper from the insulating material. Based on the differences in coefficient of thermal expansion of the insulating material and copper, the cables are cut into a suitable length and placed into a blender with hot water. The insulating material and copper are separated and collected individually. By controlling the water temperature, blending speed and cutting length, complete separation can be achieved. This process is suitable for recycling many types of cable waste, including oil‐containing wires, which are usually more difficult to recover.

Polyvinyl Chloride and Halogen-free Electric Wires Thermal Decomposition

“…The most commonly used conductors are copper and aluminum, while the preferred insulating material is polyvinyl chloride (PVC), polyethylene (PE), rubber, and paper. 1 Electric wires are designed and manufactured for many years of problem-free operation, normally in the range of 10-30 years. However, it is clear that, for a variety of reasons, these electric wires will reach a point at which they can no longer operatesthe "end of life" or EOL.…”

“…Those electric wires consist of one or several metal circuit lines and layers of plastic insulation. The most commonly used conductors are copper and aluminum, while the preferred insulating material is polyvinyl chloride (PVC), polyethylene (PE), rubber, and paper …”

Pyrolysis Behavior of Polyvinyl Chloride with Sodium Hydroxide and Application to Copper Recovery from Multiwire Tinned Copper Cables

“…Multi-step techniques are employed to recycle thin waste cables with diameters in the order of millimeters. These multistep techniques typically involve mechanical methods (such as the use of ultrasound [13] or hot-water processes [14] combined with a blender to disassemble the cables, followed by electrostatic separation [15,16], size classification [17], flotation [18][19][20], or dense medium separation [21] to separate the plastic and copper components), chemical methods (such as dissolution and cementation [22], chemical-or bio-leaching [23], and chloride volatilization [24]), and/or energy recovery processes (such as pyrolysis [25][26][27][28] and steam gasification [29]). Incineration and cement rotary kiln co-processing are alternative techniques for the treatment and disposal of PVC-containing Pyrolysis Behavior of Polyvinyl Chloride with Sodium Hydroxide and Application to Copper Recovery from Multiwire Tinned Copper Cables Takaaki WAJIMA* wastes that also afford energy recovery [30,31].…”