Coal-based granular activated carbon manufacturers have developed different materials for various applications, and the types of materials are continuously increasing. The mixture of so many different types of materials makes the recycling of waste materials very difficult. Therefore, from the perspective of improving the recyclability of metal materials, it is ideal for all parts of metal products to be manufactured from a single alloy system, and the fewer and simpler the types of alloy elements contained, the easier the recyclability of coal-based granular activated carbon becomes.