Zinc production

80% of zinc mines are underground, 8% are of the open pit type and the remainder are a combination of both. Rarely is the ore, as mined, rich enough to be used directly by smelters; it needs to be concentrated.
Zinc ores contain 5-15% zinc. To concentrate the ore it is first crushed and then ground to enable optimal separation from the other minerals.
Typically, a zinc concentrate contains about 55% of zinc, usually in the form of zinc sulphide. Zinc concentration is usually done at the mine site to keep transport costs to smelters as low as possible.
Zinc concentrates are then roasted or sintered to convert zinc sulphide to zinc oxide. Zinc oxides are then processed in either pyrometallurgical, or more commonly, hydrometallurgical processes to produce zinc metal. The most common products are High Grade Zinc (99.95%) and Special High Grade Zinc (99.99%).
The zinc production industry’s commitment to sustainable development
In addition to the adoption of their Sustainability Charter in 2001, members of the International Zinc Association (IZA) defined an action plan to bring the zinc industry’s activities into harmony with the principles of sustainability.
Key elements of IZA’s sustainability strategy include:
• assessing future trends and developing zinc sustainability indicators
• developing and communicating a full understanding of the impact of zinc on the environment and its essential contribution to human health and eco-systems, based on a sound scientific risk assessment appropriate for zinc
• ensuring efficient use of resources to produce and recycle zinc
• reducing the energy intensity of all processes along the value-chain
• controlling emissions of zinc from point and diffuse sources
• producing according to appropriate social and environmental standards worldwide
• developing an integrated product policy throughout zinc’s life cycle
More information on the implementation of IZA’s sustainability strategy can be found at www.zinc.org/sustainability