Furnace Tapping 2022: Session II
Sponsored by: The Southern African Institute of Mining and Metallurgy, TMS Extraction and Processing Division, TMS: Pyrometallurgy Committee, TMS: Process Technology and Modeling Committee, TMS: Materials Characterization Committee, Industrial Advisory Committee
Program Organizers: Joalet Steenkamp, XPS Glencore; Dean Gregurek, RHI Magnesita; Quinn Reynolds, Mintek; Gerardo Alvear Flores, CaEng Associates; Hugo Joubert, Tenova Pyromet; Phillip Mackey, P.J. Mackey Technology, Inc.
Monday 2:00 PM
February 28, 2022
Room: 213D
Location: Anaheim Convention Center
Session Chair: Hugo Joubert, Tenova Pyromet
2:00 PM Introductory Comments
2:05 PM
Furnace Tapping 101: Joalet Steenkamp1; Jan Olsen2; Quinn Reynolds1; 1MINTEK; 2SINTEF
The Furnace Tapping Conference series is an example of problem-based conferencing. It focusses on tasks all smelters have in common namely the tapping of liquid slag and alloy or matte from the reactor, and draws on perspectives from across commodities and across disciplines in Science, Engineering, and Technology. It is a platform where ideas are exchanged between operators, engineering and support, and researchers on how to optimally manage the processes involved. The paper presented here is aimed at new-comers to the field, hence the title Furnace Tapping 101, and is written in two parts. In Part 1, Natural Language Processing (NLP), a branch of Artificial Intelligence (AI), is applied in the review of papers included in the Proceedings of Furnace Tapping 2014 and Furnace Tapping 2018 which took place in South Africa. In Part 2, terminology which new-comers to the field might be unfamiliar with, is explained.
2:25 PM
Tapped Alloy Mass Prediction Using Data-driven Models with an Application to Silicomanganese Production: Alexey Cherkaev1; Khutso Rampyapedi2; Quinn Reynolds1; Joalet Steenkamp1; 1Mintek; 2Transalloys
The accounting mass balance on pyrometallurgical plants, to which the tapped masses of alloy and slag are essential inputs, forms an integral part of the process control and planning of any smelter. Thus, it is desirable to be able to predict tapped mass ahead of time. This paper examines three data-driven models that aim to predict tapped alloy mass for a submerged arc furnace producing silicomanganese. All the models are linear and based on lagged data and, thus, can be described as autoregressive models with exogenous inputs (ARX). They differ in the selection of the predictors. Ordinary least squares (OLS) model uses all of the available predictors, whereas least absolute shrinkage and selection operator (LASSO) model selects most important predictors and partial least squares (PLS) model finds best predictors in the latent space. Feature selection analysis is performed on the model results. It is shown that the model based on OLS with a reduced number of the predictors slightly outperforms other models. It is shown that power input is the strongest predictor of the tapped alloy mass, confirming current industry practice. Tap duration, energy input corresponding to the previous tap, and the previously tapped alloy mass are shown to be weak but statistically significant predictors. Using mutual information, it was shown that it was not possible to improve tapped mass prediction accuracy using tapping and recipe data alone.
2:45 PM
Slag Reduction and Viscosities Interaction in Ferromanganese Process: Tichaona Mukono1; Maria Wallin1; Merete Tangstad1; 1Norwegian University of Science and Technology
Slag reduction and viscosity are closely related in the practical operation of a submerged arc furnace for ferromanganese (FeMn) production. The viscosity of slag is dependent on temperature and its composition, and influences different aspects in the FeMn production process namely; reduction kinetics and final MnO content of slag, slag-metal separation, slag flow in the furnace and ultimately furnace tapping. As such, it is paramount to establish knowledge about the relationship between slag reduction and viscosities. The kinetics of MnO reduction in FeMn slags based on Nchwaning, Comilog and UMK ores were investigated between 1400 and 1550 °C. The extent of reduction was determined by thermogravimetry, slag morphology and change during reduction was examined by electron probe micro-analyser and slag viscosities calculated using FACTSage 7.3 thermochemical software. Results show that viscosity of primary FeMn slag is higher and decreases with increasing dissolution of solid phase into liquid as temperature increases.
3:10 PM Break
3:30 PM
Lab Scale Physical Model Experiments to Understand the Effect of Particle Bed on Tapping Flow Rates: Varun Loomba1; Hesam Pourfallah1; Jan Olsen2; Kristian Einarsrud1; 1Norwegian University of Science and Technology; 2SINTEF Industry
In this study, lab scale physical model experiments are performed to determine the effect of the coke bed on tapping rates of slag and metal in ferroalloy furnaces. A rectangular tank (dimensions 1x0.5x0.5 m) with a square shaped outlet (dimensions 0.02x0.02 m), is built out of plexiglass to emulate the region near the tap-hole. Water and a mineral oil are used as substitutes for the metal and the slag, and glass beads (diameter 0.01 m) are used as particle bed that hinders the mass flow rate of the fluids flowing out of the tap-hole. A weighing scale is used to record the mass of the tapped fluids and a high-speed camera is used to capture the interface heights of each fluid. The tapping mass flow rates will be compared in this study, with and without the particle bed in the tank, to visualize its effect.
3:55 PM
Theoretical Framework and Practical Recommendations for Proper Thermal Lance Use and Selection: Roberto Pena1; Sebastian Nunez1; Antonio Umana1; Darwin Morales1; 1Trefimet S.A.
Drill bits and thermal lances are both perforation tools used in a variety of situations. For drill bit solution there exists a lot of theory regarding the proper drill bit selection for each application. However, for thermal lances, despite being a century-old tool, there is no technical information neither a theoretical framework that allows to understand its underlying science, required to properly select a thermal lance for a specific application.This article presents a theoretical framework, developing the concepts and variables that rules the thermal lances behaviour and performance. The proposed framework fits well with experimental results, therefore could be used as a guide to select the proper thermal lance for each tapping process, potentially allowing time savings leading to an increase of the profitability of furnaces operation.
4:15 PM
Kansanshi Copper Smelter Isaconvert Furnace Tapping System Design, Operation and Improvements: Trevor Mwanza1; Matthias Eggert1; Winson Chirwa1; Nurzhan Dyussekenov1; Mark Prince2; Dennis Marschall3; Stanko Nikolic; 1Kansanshi Mining plc; 2Glencore Technology; 3Independent Consultant
In 2019, the construction and commissioning of what was to be the world’s first commercially operated ISACONVERT™ furnace was completed at the Kansanshi Copper Smelter. Between 2019 and 2021, the ISACONVERT™ furnace was operated in four campaigns in which the matte treated steadily increased from average of 35 tonnes per day to an average of 245 tonnes per day. Blister tapping and slag tapping were among the areas that had many challenges and initially had a negative impact on the plant availability. Frequent failures to close the tapholes and hot metal spills were experienced, giving rise to serious safety concerns. Several changes were implemented that resulted in a significant improvement in safety for the tappers as well as a reduction in plant down time This paper describes the design and operation of the ISACONVERT™ blister and slag tapping systems and the improvements that led to successful operation of the furnace.
4:35 PM Concluding Comments