求翻译：　　冶金及石油工业 　　用于冶金工业和金属加工在冶金工业部门，特别是有色金属的生产过程需要使用硫酸。例如用电解法精炼铜、锌、镉、镍时，电解液就需要使用硫酸，某些贵金属的精炼，也需要硫酸来溶解去夹杂的其他金属。在钢铁工业中进行冷轧、冷拔及冲压加工之前，都必须用硫酸清除钢铁表面的氧化铁。是什么意思？

　　Metallurgy and petroleum industries used in the metallurgical industry and metal processing in metallurgical industry sector, particularly non-ferrous metals production processes require the use of sulfuric acid. For example electricity when the solution of refined copper, zinc, cadmium, nickel, e

metallurgical and petroleum industries for metal and metal processing in metallurgical industry sectors, especially the non-ferrous metal production processes need to use sulfuric acid. For example, use electrolysis refined copper, zinc, cadmium, nickel, electrolyte will require the use of sulfuric

　　Metallurgy and oil industry 　　Uses in the metallurgical industry and the metal working in the metallurgical industry department, specially the non-ferrous metal production pro

　　Metallurgy and petroleum industries used in the metallurgical industry and metal processing in metallurgical industry sector, particularly non-ferrous metals production processes require the use of sulfuric acid. For example electricity when the solution of refined copper, zinc, cadmium, nickel, e