Furnace Condition Assessment And Monitoring By Utilization Of Innovative NDT Techniques

Abstract

For most cases, remaining thickness and quality of the refractory lining is key to continuous operation of pyrometallurgical vessels in the copper industry. Melt penetration within refractory lining can result in delamination or, in severe cases, refractory lifting within the hearth of a flash or converting furnace. Formation of cracks and delaminations in hearth, sidewalls and roof refractory lining can lead to melt infiltration and increased likelihood of run-outs. Important areas such as tapholes should be constantly monitored for refractory deterioration within the tapping channel. Better lancing or drilling practice can be developed based on the feedback from such monitoring systems leading to increased tonnage of material tapped between each repair.

This paper describes application of new and innovative non-destructive testing (NDT) techniques that have been developed and applied by Hatch NDT Group on Flash Smelting, Flash Converting, Noranda/Teniente, Isasmelt and Mitsubishi process furnaces. These techniques include the acousto ultrasonic-echo (AU-E) technique, where the thickness and integrity of the refractory lining is evaluated from the cold face as the vessel is in operation. Additionally, the Taphole Acoustic Monitoring (TAM) technique, where the system is monitoring the refractory lining within the tapping channel round the clock for wear and for tapping practice improvement, is presented. 

We will introduce these AU-E and TAM techniques, their principles and data collection mechanisms and discuss selected case studies. Both techniques combine traditional means of data acquisition with state of the art signal processing, including pattern recognition based on Artificial Neural Networks. The increased computing power and access to fast communication channels via internet provide new capabilities for either periodic inspections or for continuous monitoring of operating furnaces. In addition, we also demonstrate the use of traditional techniques such as thermography and acoustic emission (AE) leak detection that was applied non-traditionally for refractory thickness measurements and cavity detection.