The first primary aluminium was produced in Ziar nad Hronom and the then Czechoslovakia on 29 August 1953 at Závod Slovenského národného povstania (abbr. ZSNP, The Factory of the Slovak National Uprising).
Since the start-up of production on 15 August 1953 until the shutdown of the last Söderberg pot on 15 February 1996, a total of 2,345,221 tons of aluminium were produced at ZSNP.
Söderberg technology based on the process of continual baking of anode paste by the heat originating from electrolytic aluminium production was used in the old Potroom. This technology, in view of the environment and working conditions, was highly unsuitable as during the anode paste baking and as a result of the insufficient exhaustion of fumes to a treatment facility, enormous volumes of tar and fluorine were emitted into the environment. The negative impact of Söderberg technology influenced the whole area around the Company, as the mountain ranges significantly influence the direction of winds. Easterly winds from Vtáčnik and North-western winds from Štiavnické vrchy are predominant. One third of all days yearly features no-wind conditions resulting in the valley being badly ventilated. Insufficient ventilation causes the occurrence of inversion and unfavorable meteorological conditions concerning the pollution of ground air levels by industrial emissions.
The inhabitants of the nearby village of Horné Opatovce were also significantly affected and were forced to remove from their village to less effected villages in the area.
Alumina, as a base material for the production of primary aluminium, was produced from 1957 in the Alumina plant from purchased bauxite. A sludge and process waste dumping site with high concentration of lye and alkaline water is the remainder and a result of the environmentally unfriendly production process. Leakages of these agents and the consequent pollution of ground water were eliminated by the construction of a bentonite wall around the site. The construction of the wall was finished in 1997.