# Evaluation and Current State of Primary and Secondary Zinc Production--A Review
## 1 Introduction  
Zinc is one of the most important non-ferrous metals used in society. Its properties that protect steel against corrosion give immense economic and environmental effects [1]. However, the increasing demand for this metal may limit its availability [2, 3], as zinc has been used since ancient times. Romans produced significant amounts of brass products, i.e., an alloy of copper and zinc, around 200 BC. However, the ancient Greeks knew this metal under the name \"pseudargyras\", which can be translated as \"fake silver\". Archaeological discoveries confirm its presence from around 300 BC in the form of artifacts made of zinc, including a sheet of zinc from Athens [4]. However, a rational and efficient method of producing zinc was not known at that time, which significantly limited its use. Zinc was probably first obtained in India. Already in ancient Indian writings, the first descriptions of the processes of producing metallic zinc from ores were found [5]. In 1374 it was identified as a new metal. Wastes from the zinc smelter in Zawar, Rajasthan (India) testify to the large scale of zinc production in the period from 1100 to 1500 [6]. Sources report that during this period, this smelter could produce from 60,000 tons of metallic zinc [7] to about a million tons of metallic zinc and zinc oxide [8]. At the end of the thirteenth century, [PERSON] described the production of zinc oxide in Persia, where it was used in the form of pills to treat eye infections [5]. These pills, made of hydrometall and smithsonite, were found aboard the Roman ship Relitto del Pozzino, which was shipwecked in 140 BC [9]. At the same time, zinc production also developed in China [10]. In Europe first descriptions of experiments with calamine and the resulting product can be found in the works of [PERSON] (ca. 1248), [PERSON] (ca. 1540), [PERSON] (1546), [PERSON](1540) and [PERSON] (1596) [11; 12; 13]. In 1742 work on the distillation of zinc from calamine was carried out by the Swedish chemist [PERSON] [13]. [PERSON] developed zinc production in vertical retorts and patented it. In 1743, the first zinc smelter with an annual capacity of about 200 tons was built in Bristol [14]. Oddly enough, the official discovery of zinc as a metal dates back three years later and is attributed to the German chemist [PERSON], who described the zinc production process in great detail [6]. The improved retort process was used by [PERSON], who, in 1798, built a zinc smelter in Wesola in Upper Silesia [14]. The main advantage of this technique was that the retorts were mounted horizontally in the furnace, which allowed them to be loaded and unloaded without cooling. The [PERSON] method became a rational and economical method for large-scale zinc production in Europe. Further zinc smelters were established in Upper Silesia, but zinc production also developed in the Liege region in Belgium, in Aachen, in the Rhineland and in the Ruhr area in Germany [6; 12]. Zinc production in the United States began in 1850 with the retort process, but progress was made in the 1920s with the patenting of the continuous retort process. In 1917, a process for the electrospinning of zinc was developed (roasting-leaching-electrowinning). Another modification of the zinc production process was the introduction of pressure leaching in the 1980s [13]. The presented description of zinc production in the old days indicates problems with its acquisition. With the development of civilization, there was a leap in the industry's interest in zinc, which entailed the need to develop rational and efficient methods of obtaining it, which consequently made this metal one of the most important metals used today in technology. Zinc is a component of many alloys, including brass, aluminum zinc alloy. Rolled zinc sheets with the addition of titanium are used for roofing. It is used in electrical cells and in the form of zinc compounds.