EUROVIA-Kameňolomy produces aggregates in 10 rock quarries across Slovakia, and has one sand and gravel plant. The CDE wet processing plant was installed in the firm’s Dubná Skala quarry in 2016. The main product from the quarry is a 0-4mm crushed granite.
EUROVIA- Kameňolomy supplies concrete for urban development and road projects, including a major road construction project to develop an 11km stretch of the D1 highway between the cities of Martin and Zilina, currently under construction with work continuing until October 2018. This project has a budget of €427.2 million and comprises 11 bridges and two tunnels so the requirements for aggregates is ongoing and significant.
The Dubná Skala quarry is a 100 year-old granite quarry situated in rural Slovakia. Due to the remoteness of its location and the lack of access to a water supply, the customer needed their new wet processing plant to have a low energy requirement and to be able to recirculate the water through the system.
EUROVIA Kameňolomy’s main objective was to turn an unsaleable 0-4 crushed granite sand fraction due to high levels of contamination (contamination of 0/0,063mm fraction in the feed material at a range of 8 – 9%) into a high value product. As the quarry is located at the top of a mountain and has limited access to water supplies, ridding the granite of contaminants was challenging.
During a process of co-creation with EUROVIA-Kameňolomy , CDE prepared a bespoke design for a modular installation that would fit the limited space available on the quarry whilst addressing water efficiencies and significantly increasing product quality.
After investigating various options over a number of years, EUROVIA-Kameňolomy opted for the only comprehensive solution that could meet their specific circumstances: a CDE EvoWash wet processing plant combined with an AquaCycle thickener and a Filter Press.
Meetings with the CDE team convinced EUROVIA-Kameňolomy that CDE had the technical capabilities and experience to deliver the project successfully. Jaroslaw Modrzejewski, CDE area sales manager for Poland, the Czech Republic and Slovakia was the main point of contact for EUROVIA-Kameňolomy. He was able to use a number of previous reference projects and organise site visits to other CDE installations.
CDE places great importance on using technical expertise to provide tailored solutions that are unique to each customer’s requirements.
Modrzejewski says: “To ensure we provided the best solution I arranged for several material samples to be washed by another local company’s CDE plant and quality-checked at CDE’s headquarters in Northern Ireland. This allowed us to make an accurate calculation of the output for the new plant in order to provide guaranteed rates in our contract, providing additional confidence for the customer to proceed.”
A first within the region, the EUROVIA-Kameňolomy CDE installation comprises an EvoWash 71 wet processing plant, an A200 AquaCycle thickener and a Filter Press. The plant is completed by a buffer tank, an AquaStore and a FlocStation.
Modrzejewski adds: “This is the first full water treatment plant in this region. It solves the problem which all other quarries have experienced and struggled with: what to do with the final fraction 0-4mm which is heavily contaminated with dusts after the crushing process?
“EUROVIA-Kameňolomy has now positioned itself as the leader in this field and we are proud to have achieved this project as a reference site in the Slovak and Czech markets.”
Commenting on EUROVIA-Kameňolomy’s specific need for a low water requirement, Modrzejewski says: “Our plant uses only a few cublic meters of water per hour, which allows EUROVIA to wash its low value product and turn it into high value washed crushed sand, opening up new markets for the company.”
The extracted dry material travels by conveyor to the feedbox from where it enters the sump of the EvoWash 71. From the sump the sand is pumped to a cyclone which separates the material into the required size, with one of the key benefits of the EvoWash being that it does this without losing fines materials. From the cyclone the washed sand is sent to a dewatering screen and after further dewatering on the screen the 0-4 mm sand travels by conveyor and forms a stockpile.
The fine material sized under 63 microns is send to the AquaCycle thickener. In the AquaCycle a small amount of polyelectrolyte flocculant is added to the water from the automatic dosing station which forces fine particles to settle at the bottom of the thickener tank. The clean water on the top overflows the weir and is stored in the AquaStore tank before being re-circulated around the plant again, helping to reduce the amount of fresh water required. The waste sludge is discharged into a buffer tank where a motorised rake in constant rotation ensures the material does not settle and solidify. The sludge is held in the buffer tank before being processed to recover more water in the Filter Press.
Following testing of the materials it was determined that the Side Beam Filter Press required 36 of the 800mm² plates to achieve a processing rate of 3 tonnes/hour. Currently the Filter Press is completing 4 press cycles/hour. During each cycle the filter plates fill with sludge and are compressed under high pressure to remove moisture. A dry filter cake then drops into a holding bay from which it can be easily transported and stored.
Vladimir Sulovec, main production director at EUROVIA-Kameňolomy, concludes: “Working with the CDE team has been a very positive experience. Thanks to the professionalism and collaborative spirit of the CDE team, EUROVIA has installed the most efficient wet processing solution for the requirements of our quarry… and the first one of its kind in the region, which we are very proud of.
“Not only are we saving water and increasing the quality of our overall product, but we have gone further and turned a highly contaminated granite product we believed we could never sell into a highly profitable sand product.”
A world leader in transport infrastructure construction and urban development, EUROVIA, the parent Group of EUROVIA-Kameňolomy, is active in 15 countries across the world with close to 1,300 industrial and commercial entities. It employs over 38,000 people with a total revenue of €8.188 billion in 2014.