Jot them on a piece of paper. Now think about what they are made of. You may have picked your computer screen. Good, because it is made of glass and plastic. Glass is silica, and is a highly popular item to recycle.
Recycled glass is very abrasive.
Chutes, conveyors, and crushing equipment must all be hardfaced to protect it against excessive wear. The plastic housing of the monitor is made of plastic, which is usually an extruded product. Plastic is a polymer, and quite abrasive. In the processing of many objects, the polymer is extruded into a mold under tremendous pressures and heat, all of which contribute to the excessive wear of the extrusion machine. Hardfacing with Cobalt alloys is a common method to increase the life of the extrusion press.