ShouSteel Mining Ltd., located in QianAn City, China, runs a pelletizing plant that uses iron ore as a raw material combined with limestone, dolostone, or olivine, with bentonite as a binder. After mixing the raw materials they are formed into small spherical balls and fired in kilns for hardening. Finished pellets are used as raw materials in blast furnaces producing industrial metals such as iron. ShouSteel’s handling capacity is about 27 million STPY (Short Tons Per Year) of oxide pellets and 650 million STPY of sinters.
ShouSteel’s Existing Plant
ShouSteel uses electronic scales in a series of ingredient chambers but because of wear and tear and age the weighing system began to encounter regular problems. A high failure rate from the integrator, unstable signals, weak anti-interference ability and low accuracy to name a few. In addition spare parts required for repairs were expensive and system recalibration was becoming more frequent.
The design of the electronic scales was unnecessarily complex and maintenance was inconvenient and time-consuming. As a result ShouSteel had a tough time meeting its accuracy requirements as incorrect mixing and feeding of materials occurred frequently. The baseline error rate allowed in production is a maximum of 0.5% but ShouSteel’s ingredient system was only achieving 2.0%. As a result product quality and profits suffered.
Siemens Upgrades to ShouSteel’s Plant
In order to meet high-accuracy targets ShouSteel installed four Siemens automatic weighfeeds called “Sitrans WW 300” which has a simple design. There are no levers, fulcrums or balance weights and the weighing system reduces the dead zone of the load. The load cell is directly mounted to the weighing idler to achieve better measurements. The dual-load cell is mounted externally where it is easy to maintain and calibrate.
After installing Siemens weighfeeders and integrators ShouSteel achieved better remote and centralized control of the ingredient system. There was better mixing continuity and maintenance downtime was significantly reduced. The cantilevered design of the weighing system allows for quicker belt removal and the patented design of the in-feed lessens the amount of wear and tear on the belt and material containment parts. Spare parts costs have been significantly reduced.
Improvements Achieved by Plant Upgrades
With a single idler dual-cell scale design the accuracy of the entire weighing system, when combined with a Milltronics BW500 controller is guaranteed. ShouSteel has improved its bottom line as its materials and feeding measurements are more accurate, materials are now more smoothly transported and the whole system is automatically controlled thereby increasing production efficiency and decreasing waste bringing the plant up to world-class standards.
Future Articles on Manufacturing Plant Re-tooling
In future IndustryTap articles we will continue to look at innovative plant upgrades and the companies carrying them out. Current trends include but are not limited to upgrades to make plants more energy efficient and environmentally friendly, the application of smart technology to industrial processes including the use of robots. Additional topics in energy include gasification, turbines, fuel cells and advanced research. Stay tuned!
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