Sensors and Measurement Techniques. Laser-based analysis methods Scrap, steel & slag

Transcription

1 Sensors and Measurement Techniques Laser-based analysis methods Scrap, steel & slag Cord Fricke-Begemann, Fraunhofer ILT Aachen contact: VALEAF seminar at Stahl-Zentrum /VDEh Düsseldorf, , No Laser-induced breakdown spectroscopy LIBS a method predestined for inline analysis Parameter material analytes distance between optics and measuring object measuring time limit of detection measuring frequency Data metallic, non-metallic, solid, liquid, gaseous all elements 1 cm 10 m < 100 μs 100 ppb ppm 0.1 Hz Hz 1

2 Comparison of spatial characteristics spark OES vs. LIBS 3 LIBS analysis industrial process control State of the art Established everyday applications in the last years Raw material inline analysis: ore, coal, salt Automated mix-up inspection of steel goods Mobile material identification Related to steelmaking incl. EAF, supported by RFCS, e.g., Elemental mapping for inclusions and segregations REAL Steel and slag sample analysis at steel workshop SALIS Topgas dust inline Procssymo Scrap recycling inline LCS, IPRO Molten steel and slag inline SELA, Inquisss 2

3 Inline ash analysis of coal 24/7 operation automatic system monitoring and recalibration web interface plasma C Mg [m.-%] date 6 [1] Spectrochimica Acta Part B 93(2014)41-51 ESCS/RFCS projects directly related to EAF Inline analysis of scrap charging LCS, Laser-Induced Breakdown Spectroscopy for Advanced Characterization and Sorting of Steel Scrap LCS RFS-CT Swerea KIMAB, Fraunhofer ILT, CSM, Univ. Malaga, ORI Martin, Arcelor Mittal Research, Stena Stainless IPRO, Inline elemental characterisation of scrap charging for improved EAF charging control and internal scrap recycling IPRO RFS-CT Fraunhofer ILT, Swerea KIMAB, Centro Sviluppo Materiali CSM, O.R.I. Martin - Brescia, Outokumpu Stainless AB, RWTH Aachen University 7 3

4 Steel recycling: characterization of scrap fractions LIBS module LCS measurement campaign at Stena Recycling Scrap quality management for EAF steelmaking application scenarios for inline scrap analysers Check composition of shipments or sub-fractions regularly Discriminate processing batches in internal recycling Monitor composition during EAF charging and blend different qualities Sort steel scrap piece by piece 9 4

5 Internal recycling control at Stena Recycling (IPRO) variation of scrap charging observed inline comparison values (red line) obtained by XRF on handpicked samples accuracy unknown Discrimination for processed steel grades exactly detected 10 Single piece analysis with LIBS for sorting measuring frequency 40 Hz simultaneously detected elements 16 speed of belt conveyor 3 m/s 11 5

6 On-site scrap monitoring by LIBS Position for scrap monitoring by LIBS, approx. 25 m from EAF LIBS: Laser-Induced Breakdown Spectroscopy LIBS at scrap fraction C with added high Si scrap Si mass fraction [m.-%], LIBS Si mass fraction by LIBS, moving average of 200 values C fraction with high Si scrap added (heat 1452) 1 min Pulse number LCS measurement campaign at ORI Martin 6

7 Improved charging procedure control system scrap deposit with different grades of steel scrap blend scrap grades to optimize charge composition for each heat guidance for crane operators from inline measurements 14 Data evaluation of ICPC at Ori Martin 15 7

8 Calibration of laser analyser for low alloyed steel element Si required* Si achieved Ni achieved Mo achieved c max [m.-%] accuracy s x,0 [m.-%] Calibration under plant conditions Working distance 1.2 m (usage: m) Measurement time per sample 7 s 16 *) requirements defined by Ori Martin for ICPC, not specified for Ni and Mo Measurement data of laser analyser laser measurement scrap height profile co-located with LIBS analysis plant estimation of current scrap velocity on pendulum conveyor v(t) volume mass flow on conveyor: V(t) = h(t) * d * v(t) plant measurement of mass change in EAF: M(t) average density of each scrap grade j: = < M / V(t) > j d mean height h(t) height profile of scrap measured by light section h(t,y) 8

9 Estimation of elemental charge in the furnace current flow per element: c El (t) * V(t) mass at analyser position: M El (t)= c El (t) * V(t) * Heat AJ1240 AJ1241 M(Si) inline 195 kg 347 kg SiO 2 in slag 5.5 % 7.6 % campaign with > 200 heats, not always good correlation example of two subsequent heats on February 20 th 18 Estimation of elemental charge in the furnace 2 approaches for the accumulated elemental mass per heat laser analyser M El = M El (t) summed over time steps of t = 5 to 10 s v(t) c El (t) h(t) t del M(t) 1. from laser analyser only: M El (t+t del ) = c El (t) * * V(t) with V(t) = h(t) * d * v(t) * t = < M / V(t) > j j scrap class 2. using total mass increment M(t) in EAF also: M El (t+t del ) = c El (t) * M (t+t del ) mean height h(t) d height profile of scrap measured by light section h(t,y) 19 = laser = works 9

10 Conclusions on LIBS for scrap control Inline analysis of scrap on conveyor offers different application options Operation of laser analysers in industrial environments in EAF plant and scrap yards demonstrated in several measurement campaign Issues to be solved for routine application determination of mass flow in case of Consteel pendulum conveyor handling and storage of mass flows for internal EAF recycling incorporation of scrap analysis in EAF basket charging procedure Direct analysis of liquid steel with LIBS RFCS SELA Int. Meeting on Chemical Engineering, ACHEMA Applied Optics 42 (2003) , Materials Technology and Testing,

11 LIBS analysis of liquid steel RFCS SELA calibration of C and P at a 100 kg induction furnace estimated LOD 3s C 5 μg/g P 21 μg/g industrial installation not realised at that time for technical reasons Applied Optics 42 (2003) Inline Analysis of Liquid Slag Non-ferrous metals beyond RFCS Inline analysis at slag runner of furnace Multi metal analysis of slag, e.g. valuables and heavymetal contaminations Successful on-site trials LIBS analyser for galvanising Zn-bath now commercially available 25 11

12 Laser analysis of liquid slags from steelmaking LIBS analysis of slag composition, determination of basicity Measurement and assessment in slag bucket of truck prior to access to slag dump Inline measurement < 2 min Plant for 24/7-operation fully automated [3] K. Pilz, Berg- und Hüttenmännische Monatshefte, vol. 157 (6-7), , Liquid slag analyser Optical module with laser head, optics, fibre optic cable to spectrometer Measuring distance 3.7 m N2 purged measuring probe Automatic adaption to varying filling heights (> 1m) Scanning across slag surface V. Sturm et al, Analytical Chemistry 2014, 86,

13 Results for liquid slag: Elemental mass fractions Comparison of LIBS with reference analysis Reference analysis by steel works laboratory Cooled material manually sampled from slag pits Source: V. Sturm et al, Analytical Chemistry 2014, 86, American Chemical Society Inline Analysis of Liquid Steel and Slag Developed throughout several R&D projects since 1990s Feasibility demonstrated, e.g. SELA project Integration into process not realised satisfyingly at that time Recent progress made Inline analysis at slag runner, non-ferrous Zinc bath analysis in routine operation First system for routine steel slag analysis 24/7 installed New project on steel bath analysis proposed 13