In-situ versus Post-mortem Process Control - How LIBS-based Slag Analysis Within 1-2 Minutes Enables a Completely New Process Management in Pyrometallurgical Processes

Abstract

Resource efficiency and process optimization are major targets in metals making. Today’s state of the art analytical approaches for slag analysis (e.g. XRF) requires tedious sample preparation which leads to significant loss of efficiency in terms of immediate decision making, fast setpoint adjustment as well as process correction. Due to this delay, if the analysis result reveals deviations from the target value (optimum), the melt is already one process step further and can no longer be adjusted or treated adequately. With minimum sample preparation, Laser Induced Breakdown Spectroscopy (LIBS) can analyse heterogeneous slag pieces in less than 2 minutes and delivers even more representative results while ensuring reasonable accuracy. In addition, due to the robustness, easy handling and required maintenance effort being minimum, LIBS systems can be placed on site (e.g. next to or close to the furnace) and can be operated by normal process personnel. Therefore, not only the sample preparation time is saved but also the conventional sample transportation time from the furnace to the lab can be shortened. Therefore corrective measures can be already initiated while the melt is still in a comparable state resulting a ‘in-situ’ adjustment of the process. This paper explores the potentials of LIBS technology to obtain representative data in process slag analysis and sheds some valuable insight in terms of analytical challenges faced by offline laboratory technologies.

Keywords: slag analysis, LIBS, sample preparation free analysis, in-situ slag analysis, XRF alternative, online furnace feed analysis