Slovakia Steel Mills, a.s., Strážské, Slovakia, has placed an order with Siemens to supply a water treatment plant for its new steelworks. The order is said to be worth some ten million euros.
The plant will treat the water used for direct and indirect cooling for Slovakia Steel Mills’ new minimill in Strážské, which is designed to produce around 600,000 tonnes of structural steel per year. The new mill incorporates the complete process chain, including an electric arc furnace, ladle metallurgy facility, a three-strand continuous casting plant and a rolling mill.
To support the plant’s treated water requirements for direct and indirect cooling, the central Siemens treatment plant will supply some 7,000 cubic meters of treated water every hour. The technical equipment includes cooling towers, pumping stations, pressure sand filters, metering stations and sludge treatment facilities.
Heavily polluted water returning from the casting plant’s and rolling mill’s direct cooling system will first be fed into a cyclone separator to remove scale. Oil will then be removed by a skimmer and the remaining solids will be filtered out by downstream pressure sand filters. The water temperature will then be lowered by 10 to 15 °C in a cooling tower before it is fed back into the cooling systems.
Less heavily polluted water from the secondary cooling system will pass through bypass filtration, where the concentration of suspended solids will be reduced before the water is pumped into the cooling towers.
Backwash water from the sand filters, still contaminated with sludge, will pass through the sludge treatment plant, and suitable polymers will be added to the sludge to make it easier to separate the solids from the water in a lamella separator. Pre-clarified water will pass through a sand filter again, after which it can also be fed back into the cooling system. The remaining sludge will be thickened and dewatered in a filter press. Part of the metal-bearing sludge can be recycled back into the production.
The entire water treatment plant will be automated by Simatic type S7 300 programmable logic controllers, with visualization provided by a WinCC HMI system. Siemens is also supplying the process instrumentation equipment for monitoring water quality, including instruments to measure flow rates, pressures, temperatures and levels. All the pump drives will be equipped with frequency converters, enabling energy savings by running the pumps according to demand.
The new plant is scheduled to come on stream by the end of 2010.
The Siemens Industry Sector (Erlangen, Germany) is a leading international supplier of environmentally friendly production, transportation, building and lighting technologies. The Sector comprises six divisions: Building Technologies, Drive Technologies, Industry Automation, Industry Solutions, Mobility und Osram. With around 207,000 employees worldwide (September 30), Siemens Industry achieved in fiscal year 2009 total sales of approximately €35 billion.
The Siemens Industry Solutions Division (Erlangen, Germany) is one of the world's leading solution and service providers for industrial and infrastructure facilities comprising the business activities of Siemens VAI Metals Technologies, Water Technologies and Industrial Technologies. With around 31,000 employees worldwide (September 30), Siemens Industry Solutions posted sales of €6.8 billion in fiscal year 2009.