Step 1: Understanding the Concept:
Zone refining is used for metals that require very high purity (e.g., semiconductors, zinc).
Step 2: Detailed Explanation:
Zone refining is based on the principle that impurities are more soluble in the melt than in the solid. It produces ultra-pure metals. Zinc is purified by zone refining. Mond process is for nickel, van-Arkel for titanium/zirconium.
Step 3: Final Answer:
Zone refining