# Evaluation and Current State of Primary and Secondary Zinc Production--A Review
## 5 Summary  
Zinc can be produced from primary raw materials by pyrometallurgical or hydrometallurgical methods. Pyrometallurgical methods are still used in different parts of the world but gradually lose their importance and are no longer used, e.g., in the EU for the treatment of zinc concentrates, except in Poland. The main factors determining this are the need for an additional distillation step in order to obtain high-quality zinc and the relatively low efficiency of zinc extraction. In hydrometallurgical methods, there are problems with the emission of residual sulfur dioxide, NO\({}_{\rm X}\) and acidic effluents and the release of metals such as arsenic, mercury and cadmium, and additionally organic pollutants. Therefore, emissions to air and water, waste management and energy considerations are among the key factors influencing the choice of techniques used in the processing of zinc-bearing ores. Currently, around 30-35% of the zinc consumed annually comes from recycling. Production of zinc from secondary sources brings a number of measurable benefits, such as saving primary resources and fossil resources used to provide energy in primary mining processes, reducing zinc storage and losses (maintenance of landfills and increasing the amount of waste cost a lot), reclamation of waste, mitigation of environmental effects and health, and improving the economic efficiency of existing infrastructure. Dust, metal particles, chemicals and harmful gases are released into the environment during the zinc mining and refining process. Although companies try to keep emissions to a minimum, the process \begin{table}
\begin{tabular}{c c c c c c c} \hline Year & **1991** & **1995** & **2000** & **2005** & **2010** & **2015** & **2017** \\ \hline Primary production, thous. tone & 4370 & 4160 & 4330 & 4680 & 4810 & 12,600 & 12,700 \\ Secondary production, thous. tone & 376 & 345 & 348 & 298 & 279 & 409 & 447 \\ Undistinguished production, thous. tone & 2570 & 2980 & 4460 & 5770 & 7710 & 711 & 691 \\ \hline \end{tabular}
\end{table} 
Table 10: Total zinc production broken down into primary and secondary zinc production and non-differentiated production in thousands of tons, based on data from [89; 90; 91]. \begin{table}
\begin{tabular}{c c c} \hline
**Indicator** & **Description** & **Estimated Global Recycling Rate** \\ \hline Recycled content (RC) & Zinc scrap fraction (new and old) in the total use of & 25\% \\  & metal in production & \\ Ratio of old scrap & Zinc fraction from old scrap in the general recycling loop & 70\% \\ EOL recycling rate & Fraction of recycled zinc in relation to the amount of & 45\% \\  & zinc available at the end of its life & \\ \hline \end{tabular}
\end{table} 
Table 9: Recycling process indicators, worked out based on [71]. still harms the environment. The recycling process is also safer and cheaper. Recycling rates are increasing with advances in zinc production and zinc recycling technologies. However, it is estimated that this level will not increase rapidly due to the large dispersion of zinc products and the problematic collection of zinc scrap. For the recycling process, one of the problems is the service life of the products, which is relatively long for steel, e.g., bridges, and steel structures that are in constant use. At present, the service life of zinc-coated steel products is extended. The long service life of products, as well as changes in the corrosiveness of atmospheric environments at that time, make the life of products less predictable. Both in the case of zinc and steel itself, the amount of scrap for secondary production may change, and shortages are observed periodically. In this case, primary production from ores and concentrates is based. Both steel and zinc are 100% recyclable with no loss of chemical or physical properties. For steel, it is estimated that virtually 100% of all structural steel is recovered for reuse; the same index for zinc is over 80%. Galvanized steel can be easily recycled with other scrap steel in the electric arc furnace (EAF) steelmaking process.