Final answer:
Joining processes involve three major categories: preliminary treatment, smelting, and refining.
Step-by-step explanation:
The joining processes fall into three major categories: preliminary treatment, smelting, and refining.
These processes are commonly used for the isolation of metals like iron, copper, and silver.
Preliminary treatment involves the initial preparation of the metal ore, smelting is the process of extracting the metal from the ore, and refining is the final purification of the extracted metal.