# Evaluation and Current State of Primary and Secondary Zinc Production--A Review
## 2 Zinc Production, Demand and Applications
### Application and Demand
The galvanizing bath always contained lead with a content close to the solubility limit in liquid zinc of 1.2 wt.% [41]. Lead was willingly used as an alloying additive to the bath because it lowers the surface tension of liquid zinc and improves the castability of the bath [42]. This results in better zinc flow from the surface of the product, which results in reduced zinc losses and its lower consumption during the galvanizing process. However, the presence of Pb in the bath is very controversial due to its negative impact on the environment and human health [43, 44]. In the 80 s of the last century [40], the production of Special High Grade (SHG) zinc with high purity of 99.995 wt.%, in which the level of all impurities does not exceed 0.005 wt.%, significantly increased [45]. The use of GOB zinc for galvanizing systematically decreased, and SHG zinc took its place. Currently, practically only SHG zinc is used for galvanizing in Europe. Although Pb is sometimes added to baths, its content does not exceed 0.4-0.5 wt.% [46]. However, most galvanizing plants reduce or completely eliminate the addition of Pb to the bath, replacing it with the addition of Bi [47] or BiSn [48, 49]. The specificity of the hot dip galvanizing process causes the efficiency of zinc used to be lower compared to other areas of zinc production and consumption. Zinc consumption depends not only on the thickness of the coating but also on the losses resulting from the specificity of the technology, i.e., the formation of hard zinc and galvanizing ashes, oxidation of the bath surface and formation of precipitations of solidified zinc. Studies have shown that one ton of zinc used in the hot dip galvanizing process generates 147.6 kg of hard zinc and 139.3 kg of zinc ashes. The average zinc content in hard zinc ranges from 94 to 96 wt.%, while the average zinc content in galvanizing ashes ranges from approximately 70 wt.%. This means that for each tone of SHG zinc delivered to the galvanizing plant, on average, approx. 240 kg of zinc is ineffectively used to create waste in the form of hard zinc and zinc ashes [49]. These are, of course, by-products rich in zinc, which is the raw material for the production of secondary zinc. The main areas of application of zinc are the following: construction and infrastructure (66%), automotive industry and industrial machinery (28%), consumer goods and electrical appliances (23%) and general engineering (7%) (Figure 5). It should be noted that both steel structures, infrastructure and car bodies are commonly protected against corrosion by hot dip galvanizing coating. This explains such a large share of these areas of application in the global structure of zinc consumption. However, in recent years, new directions for zinc applications have emerged. Agriculture may be a growing end market for zinc applications. Zinc is currently recognized, together with potassium, as one of the most intensive organic fertilizers. It is predicted that China and India will be potential areas for the application of zinc-based fertilizers in the future [50].