In 1996, guarantee tests were conducted at Slovalco. The purpose of the tests was to prove, among other things, that the emission sources at Slovalco were in accordance with the environmental standards of the Slovak Republic and the European Union. The results of the guarantee tests were as follows:
- out of 23 emission sources all 23 sources met the emission limits of the Slovak Republic,
- the specific emission limits of the Slovak Republic regarding solid polluting matters from the whole site and specific HF emissions from the Fume Treatment Plants and exhaust air were met to the full extent,
- the guaranteed values/limits according to the Know-how agreement were met in every indicator during the guarantee tests as well as during the 6 month testing period,,
- the quality of the working environment in the Potroom regarding fluoride concentration met the limits stipulated in Slovak hygienic standards.
Part of Slovalco’s mission is to produce aluminium through a modern ecological process with minimum negative impacts on the Environment. In its vision Slovalco, a. s., declares that it will be a model for the environmental care.
All our activities are aimed at the establishment of Slovalco, a. s., on the top level among modern, safe, efficient and environmentally friendly producers of products and eventually suppress the myth that connects aluminium production with damaging of the environment and health of people and other living organisms.
The slag field/sludge bed was completely stabilized and recovered. The whole process was carried out in three steps. In the first stage, from 1992 to 1997, an underground insulating wall was built around the whole slag field/sludge bed creating an impermeable barrier that prevents spreading of pollution to the surrounding and underground waters. The insulating wall is made of 60 cm wide bentonite-concrete compound that is embedded in impermeable bed, reaching 7-15 m below the surface.
The stage two included building of a plant for processing and treatment of alkaline water from the sludge field. The processing is done in several technological steps. The first is physical and chemical treatment/purification of water by adding chemical agents which reduce pH of the alkaline water and subsequently, heavy metals are removed through solid phase. In the second stage, the purified water undergoes electro dialysis which divides it into two streams. The first one, diluate, is purified water which is sent to Hron river through sewer system. The second stream is a concentrate processed in the third technological stage at crystallizing evaporator. The stage of processing of alkaline water is still in progress.
Recultivation of the slag field/sludge bed carried out in stage three had four major goals:
- considerable reduction of ingress of rainwater into the slag field/sludge bed
- stabilization of the slag field/sludge bed (elimination of earth slide and erosion of the slopes)
- elimination of dusting
- improvement of aesthetic look of the country
This stage took place from 2006 to 2016. Insulating layers (HDPE UV stabilized film or bentonite layer) were applied first, followed by drainage layers and finally gravel mixed with humus soil. Thanks to comprehensive and complex recovery process, ZSNP, as the investor successfully integrated the slag field/sludge bed into the surrounding environment without disturbing elements. The costs for the complex solution of the issue reached 53 million $ paid by ZSNP from own sources. This recovery and recultivation became the largest single project focused on elimination of old environmental load carried out by private Slovak company.