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Tonnage
225tph
Material
Limestone, Sand & Gravel
Output
2 Washed Sands & 5 Washed Aggregates
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THE CHALLENGE
Pehofer GmbH is an Austrian family business founded in 1979. The main activity of the company is the supply of ready-mixed concrete, as well as sand, gravel and grit for private, commercial and public construction sites. A partner company, BT3 is responsible for monitoring quality at the Pehofer concrete and gravel works and performs all product testing and concrete/gravel technology services to ensure the high quality requirements are met.
When Pehofer began looking for a supplier for the new gravel washing plant at Wiener Neustadt they had some very specific requirements in order to ensure that the sand and gravel production process at the new site was designed with efficiency in mind. This not only related to the performance of the washing and classification plant but to how its operation would be managed as exploitation of the new resource developed in the years ahead.
“We investigated a number of technology options based on previous experience and research into the latest technology available” explains partner Mr Peter Pehofer.
“We also required that the plant be sufficiently mobile that we would be able to move it as extraction progresses. We anticipate this will happen every two or three years.”
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THE SOLUTION
The plant includes the M2500 E3X mobile washing plant and an AggMax™ 153 semi-mobile logwasher and processes 225 t/h of limestone raw material. The washed sand and gravel from the new plant is used by Pehofer in their own ready-mixed concrete production plants, and the products are also offered for sale on the market. Pehofer purchased the new site in order to ensure complete independence in the area of sand and gravel for decades.
The AggMax™ is required in this instance to effectively remove raw gravel material from the clay and fine particles which bind the material together. As material enters the AggMax™ it is subjected to a high level of attrition from the integrated Rotomax logwasher. In this instance a RotoMax RX153 is employed which has a capacity of 150 t/h. The scrubbed material is then discharged onto a triple deck horizontal sizing screen for classification into the required aggregate grades. The wastewater containing the liberated fines and clay is returned to the sand washing phase on the M2500 to maximise sand recovery. As the feed material contains a small proportion of material in the 0-4 mm range this step is critical to ensuring production of a manufactured sand product that meets the required standards for use in concrete.
The plant is configured in such a way as to allow three production modes each delivering a different suite of final sand and aggregate products according to the specific requirements of Pehofer at any given time. This is achieved without any requirement to change screen media and is facilitated by the introduction of a number of diverter chutes and the introduction of two radial stockpile conveyors.
THE RESULTS
The plan to move the plant as extraction progresses is designed to minimise the costs of transport movements at the new site. Over time the processing plant gets further away from the quarry face and the subsequent increase in transport movements adds significant cost to production.
“The capability of the CDE equipment to deliver on this requirement was critical to our decision to buy the washing plant from them” says Mr Helmut Pehofer. “They were able to demonstrate a portfolio of previous projects where the requirement for mobility had been similar to ours and a visit to see similar plants in operation confirmed that this could be achieved without compromising on the capability of the plant to maximise production of the highest quality sand and gravel products.”
Pehofer is confident that this investment will bring big benefits. “Given our new aggregate production capability, the flexibility of our new CDE system and the continued growth of our concrete and gravel business we are looking forward to enjoying the efficiency gains that this plant will deliver” says Helmut Pehofer. “We are now set up for a period of further expansion in the years ahead.”
