The phrase "to grind up" means to reduce something into small pieces or particles by using a machine called a grinder. This can refer to various materials such as food, metal, or even rocks and minerals. The process involves placing the material in the grinding chamber where it is hit with high-speed rotating blades that break it down into smaller pieces. Grinders are commonly used for many different purposes including making coffee, sharpening knives, cutting metal, and crushing rock samples to analyze their composition.