Enhanced Smelting Furnace Sustainability Using Non Destructive Testing (NDT) and Monitoring

David Chataway, Richard MacRosty, Ravi Pula, Afshin Sadri, Wai Lai Ying

The sustainability of a smelting furnace manifests itself through its ability to operate safely and to save resources. These qualities, the safe operation of a furnace and the amount of resources it saves, are primarily influenced by the campaign life length of the furnace and the prevention of run outs and maintenance outages. New developments in non destructive testing (NDT) and monitoring have allowed furnace operational management teams to have a greater understanding of their furnace and process. This has led to longer furnace campaign lives and improved prevention of run outs and furnace maintenance. As a result, smelting furnaces are safer and have lower environmental and economic impacts by reducing the frequency and scale of maintenance and rebuilds. To inspect and monitor smelting furnace integrity, a number of non-destructive testing (NDT) and monitoring techniques have been developed by the Hatch NDT Group. NDT inspections refer to periodic measurement services while NDT monitoring refers to technology which is installed and provides continuous measurements. NDT inspection techniques utilized by smelting furnaces include the patented Acousto Ultrasonic-Echo (AU-E) and Low Frequency Pulsed Ultrasonic (LFPU) techniques. NDT monitoring technologies provided to smelting furnaces include various patented Acoustic Emission (AE), eddy current, radar and fiber optic systems. Each of these technologies and services are designed to deal with unique challenges facing smelting furnaces. One of the main challenges facing smelting furnaces is the refractory wear of the furnace lining. Furnaces are lined by refractory bricks or castables to protect the structure against the harsh operational environment. With time, refractory linings in smelting furnaces undergo deterioration and wear. The deterioration is mainly caused by thermal stresses and chemical attacks, resulting in loss of heattransfer and load-bearing capabilities. Failure of the lining is dangerous and can affect the structuralintegrity of the furnace. Aside from refractory wear, other challenges facing smelting furnaces include wear of the tapblocks and control of the matte, slag and feed/charge levels in the furnace. This paper will discuss the various NDT techniques and how they help solve the challenges presented by smelting furnaces. This paper will show how the NDT inspection and monitoring of a smelting furnace leads to better safety, longer service life of the furnaces, controlled maintenance and increased production.