Carbide end mills are used in the machining process and one of the greatest values in them is that they can cut in many different directions. These are very valuable bits for the machining world but they often get replaced due to wear and tear. The parts that are being machined need to have high precision and the old end mills will need to be replaced and recycled.
Carbide tips and bits are almost always going to be mixed together and have dark grey color. These will have a slight pull with a magnet but will not have a heavy stick to them. If you have hard-sticking bits they are most likely going to be either tool steel or regular steel.
Tungsten is used in welding applications as well as inside many tooling industries. Tungsten electrodes are used in special metal welding as well and could have a very high scrap value as well.