... risk), technology is very important, we had been doing oil refining for ten years, actually, have been experienced times ... is by-product, if it is made by plastic oil refining, it can be made of coal and brick. ... it is made by tires oil refining, it is called carbon black, it is valued about 400-500 Yuan per ton ... process to 800-1200 mesh, it can be value about 4000-5000 Yuan per ton, this kind of slag ...