Zinc is an inherently recyclable non-ferrous metal and can be recycled indefinitely without any loss of physical or chemical properties. At present, approximately 70% of zinc comes from primary refining of zinc ores (including 10-15% from recycled sources) and about 30% comes directly from recycled zinc (representing 80% of the zinc available for recycling). The recycling level continues to increase as technology improves. The long life of zinc coated steel products in construction makes forecast of their emergence in waste streams difficult to model, hence more work will be required on this.
Zinc is an inherently recyclable non-ferrous metal and can be recycled indefinitely
The zinc recycling circuit
Zinc is the 27th most common element in the earth’s crust. The world is naturally abundant in zinc. Even a cubic mile of seawater is estimated to contain 1 tonne of zinc. It is estimated that the first mile of the earth’s crust under land contains 224,000,000 million tonnes of zinc, with a further 15 million tonnes in the seabed. Such estimates, however, take no account of whether or not it is economic, or environmentally acceptable, to exploit these resources.
Reserves of zinc – like those of any natural resource – are not a fixed amount stored in nature. Reserves are determined by geology and the interaction of economics, technology and politics. The term Reserves denotes the portion of resources that has been mapped and measured and which may be used, now or in the future.
Thus, Reserves reflect the state of knowledge, technology and the value of zinc at a given time. These natural resources are increasingly augmented by the supply of recycled zinc.
Proven Reserves of zinc have increased significantly since the 1950s, as large new ore bodies have been discovered in many areas of the world.
The sustainability of zinc ore supplies cannot therefore be judged simply by extrapolating the combined mine life of today’s zinc mines. Despite increasing consumption of zinc from 1995-2005, the world’s zinc reserves substantially increased over that same period, as shown in the table.
(Source: U.S. Geological Survey,)
1. Reserves are defined as, “That part of the reserve base which could be economically extracted or produced at the time of determination.”
2. Reserve base is defined as, “That part of an identified resource that meets specified minimum physical and chemical criteria related to current mining and production practices, including those for grade, quality, thickness, and depth.