On the road to success with VTA
Whether it’s in the glass industry, at foundries or in the building materials sector, quartz sand from Šajdikove Humence in western Slovakia is in demand. The Kerkosand company there – a subsidiary of Quarzwerke GmbH, headquartered in Frechen, Germany – extracts a light-coloured, particularly round-grained raw material.
By washing out organic impurities, extraneous matter and accompanying minerals, and a number of further processing steps, it is ultimately turned into a high-quality industrial mineral. At Kerkosand, up to 100 tonnes per hour are extracted in this way.
The water required for washing out, around 600 m³ per hour, is purified and flows back into large, specially created pools. This is where VTA comes in: Special VTA polymers ensure that suspended solids and contaminants are eliminated before the water reaches the pools and that the sludge settles without leaving a residue.
Tailored exactly to raw sand
The challenge here is that to achieve the optimum effect, the flocking agent used must be tailored specifically to the raw sand. “If there are any changes in the composition or in the cleanliness of the starting material, the polymer has to be adjusted accordingly,” explains Alfred Baier from the VTA technical field service.
Since VTA started working at Kerkosand three years ago, the experienced polymer specialist has managed to further improve results through constant analysis and continuous optimisation of the polymer composition, and also through adaptations to the dosing system.
Today, turbidity values between 50 and 90 NTU are achieved at Kerkosand – not even a tenth of the initial values at the beginning of VTA dosing, when values of over 1000 NTU were measured. The company’s target (100 NTU) is reliably met.
Pool water for production
This is a crucial advantage, because at this level of quality, the pool water can be reused as process water for production. The purity of the production water is after all crucial to the quality of the quartz sands and quartz powders produced: under no circumstances should it contain fine particles that would contaminate the sands.
Exploitation of this cycle, which is now possible, makes the use of ground and drinking water in production at Kerkosand superfluous – a considerable environmental advantage given the quantities required. Pool water can even be used for preparation of the polymer solution, which takes place in a Eurodos dosing station. At the same time, the dosage quantities of the VTA polymer ensure that its use is also clearly cost-effective.
Last but not least, the VTA polymers already point to a profitable future for Kerkosand: once the raw material reserves are exhausted, both the extraction areas and the pools will be returned to their original natural state. Any sludge in the pools that is contaminated with residues would then have to be treated and disposed of at enormous cost. Thanks to VTA’s expertise, this can already be effectively prevented.
Field report from the VTA Group’s scientific journal “Laubfrosch”, issue 75