Can I apply for a patent to reprocess a material for another purpose?

Patents are divided into inventions, utility models and appearances. Among them, the utility model is a structural patent, and its appearance is similar to that of the outer packaging. You can only apply for one invention patent, which is divided into three protection themes: product, method and use. If the substance you are talking about is known and the treatment method is unknown, you can apply for a patent for protection method or a patent for protection of product use. They can't apply for the same patent because there is no singularity. If the treatment method is known, you can only apply for a patent to protect the use of the product. If a material is not made public, it can protect the three themes of product, method and use in one patent at the same time, and of course it can also be declared in three patents.