Zinc production

There are three different types of primary zinc production. The first method is a metallurgical process called electro-thermic distillation. The process is uses to combine roasted concentrate and secondary zinc products into a sinter feed that is burned to remove zinc, halides, cadmium and other impurities. The resulting zinc oxide-rich sinter is combines with metallurgical coke in an electric retort furnace that reduces the zinc oxides and produces vaporized zinc which is captured in a vacuum condenser. The reduction results in the release of non-energy carbon dioxide (CO2) emissions. The electro-thermic distillation process is used in the United State and in Japan.

The second method of zinc production is a pyrometallurgical process involving the use of an Imperial Smelting Furnace, which allows for the simultaneous treatment of lead and zinc concentrates. The process results in the simultaneous production of lead and zinc and the release of non-energy CO2 emissions. The metallurgical coke/coal reductant used in this process must be allocated to lead and zinc production in order to perform an emission calculation without double counting. A mass based allocation results in a factor of 0.74 tonnes coke/tonne zinc.

The third zinc production method is the electrolytic process, which is a hydrometallurgical technique. In this process, zinc sulphide is calcined, resulting in the production of zinc oxide. The zinc oxide is then leached in sulphuric acid and purified to remove iron impurities, copper, and cadmium. The zinc is then drawn out of the solution using electrolysis. The electrolytic process does not result in non-energy CO2 emissions.

How to use this category

To use this category use the zincProductionBySource drill-down to select the zinc production process from the following options:

1. default
2. waelz kiln production
3. pyrometallurgical (imperial smelting furnace) production
4. electro-thermic distillation production

The only required profile item value is the quantity of lead produced, productQuantity. The emission factor for each production process has a default value provided, but this can be over-ridden, using the massCO2PerMassProduct profile item value, by the user if more precise site or country-specific values are known. Over-riding the default values represents the Tier 2 approach described by the IPCC Guidelines for National Greenhouse Gas Inventories (NGGIP) and should be used where users have facility-specific data.