How do supernovae recycle matter?
Supernovae are important for creating the heavier elements.
The majority of matter in the universe is hydrogen and secondly helium.
Most stars convert hydrogen into helium by nuclear fusion.
More massive stars use the Carbon-Nitrogen-Oxygen fusion process to convert hydrogen into helium.
In order to produce the more heavy elements a lot more energy is required and supernovae provide the energy to do this. The fusion process liberates energy until the nucleus is iron/nickel after this fusion requires more energy to create nuclei than is released.
Supernovae have the energy to produce the heavier elements using processes such as neutron capture.