Oil spillages and industrial discharge of oily water have caused severe damage to global environment. Currently a great many of oil-absorbing materials including graphene aerogels, superhydrophobic cellulose aerogels and polymer foams have been developed to effectively separate oil and water. However, most of the absorbing materials show limitations in separation of high-viscosity oils because the diffusion speed of high-viscosity oils into the porous materials is very slow at room temperature. In this article, a novel oil/water separation material was fabricated from rock wool superhydrophobically modified by PDMS/SiO2 nanoparticle treatment. The modified rock wool could circularly absorb spilled oil and reload after combustion or squeezing. Most importantly, the modified rock wool worked well in continuously collecting high-viscosity oil with the aid of electric heating due to its excellent heat resistance. Because the rock wools have been industrially produced in large scale with very low prices and they are degradable naturally, this kind of spilled oil treatment was demonstrated to be a low-cost and environment-friendly method for the high-viscosity oil separation.