... , zinc standard potential of-0.76V, the iron standard potential of -0.44 V., zinc and iron to form a micro-battery, zinc ... . (2) Pickling H2SO4 15% can be used, thiourea 0.1%, from 40 to 60 ° C, or with HCl 20%, methenamine 3 ~ 5g ... the iron loss caused by zinc slag, are 450 to 470 ° C, 0.5 to 1.5min. Some factories for large workpiece and ...