Zinc ore is crushed to separate the zinc from other elements, then roasted or sintered to produce zinc oxide before an electrolytic process is used to obtain the zinc. Zinc ore contains only 5 to 15 percent zinc.
After roasting the ore, sulphuric acid is added. The zinc is dissolved into the acid, and any other elements present are separated from the solution easily. The solution is then pumped into an electrolytic cell. Next, an electric current is applied, and the positively charged zinc ions migrate towards the negative electrode.
Most zinc is obtained using this electrolytic process. A smaller percentage is obtained using a pyrometallurgical process, which uses intense heat in specially designed furnaces to smelt zinc and lead into metal. This process is so energy-intensive, and thus expensive, that it has largely been replaced by the electrolytic process, except in China, India, Japan and Poland.