01:00 pm
End of petroleum tar binder, new generation of tap-hole clay. Formaldehyde and PAH free technology
Dr. Thierry Joly | Vesuvius Europe | France
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Authors:
Dr. Thierry Joly | Vesuvius Europe | France
Roger Isenbarger | VESUVIUS USA | United States
Stephen Draper | VESUVIUS USA | United States
Taphole clay is used to control the pig iron flow and hearth liquid levels in the blast furnace to maintain process stability, protect the hearth, extend campaign life and reduce costly repairs. Taphole clay consists of a solid part and a binder phase. In two previous publications [1] & [2], we presented the development of a new concept of a binder for taphole clays which does not contain PAHs and formaldehyde. This solution has been on the market for more than two years and is working for most of our customers who have chosen the Eco & Health Friendly transition. However, in some rare cases, we observe a hardening of the taphole mass in the plugging machine, this defect required from us a new step in the development of our very clean binder. We have worked to reduce this hardening phenomenon, correlated to the high temperature in the mud gun, by developing a binder based on the same concept but developing a higher boiling temperature. By increasing the boiling temperature of the binder, we succeeded in shifting the setting of the binder to higher temperatures, which solved the hardening problem. At the same time, in a way that could not be predicted at the Laboratory scale, this modification of the binder has a positive influence on the length of the tap hole, the duration of the casting and the specific consumption of the tap-hole clay in grams per ton of hot metal.
01:20 pm
Comparative study between coal tar pitch and lower polycyclic aromatic hydrocarbon (PAH) alternative binders for use in taphole clays
Izak Cameron | University of Pretoria | South Africa
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Authors:
Izak Cameron | University of Pretoria | South Africa
Dr. Shatish Ramjee | University of Pretoria | South Africa
Prof. Andrie Garbers-Craig | University of Pretoria | South Africa
The conventional binder used in taphole clay is high volatile coal tar pitch (CTPht) or a similar low softening point pitch which poses great health and environmental risks due to the polycyclic aromatic hydrocarbon (PAH) present in the binder. Less toxic or non-toxic (lower PAH content) alternatives that have been identified as substitutions are distilled coal tar, petroleum-based phenolic pitch, waxy (paraffin) crude oil, and wood-based tars which are derived from the Kraft process. The behaviour of the CTPht was evaluated with respect to its rheological properties (Newtonian behaviour, thermal stability), its thermal behaviour (using thermogravimetric analysis, TGA-DTG) as well as its chemical composition (using gas chromatography mass spectroscopy, GC-MS) to identify critical binder properties. The proposed alternative binders were then evaluated against the critical binder properties of the CTPht and the most suitable alternative proposed.
01:40 pm
Development of High Performance Tap Hole Clay
Tuhin Patranabish | Calderys | India
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Dr. Saumen Sinha | Calderys | India
Tuhin Patranabish | Calderys | India
Kazi Asif Ahmed | Calderys India Refractories Ltd | India
Dr. Indranath Chakraborty | India
Consistent Performance of Tap Hole Clay (THC) is essential for smooth blast furnace (BF) operation. Challenges increase with the increased BF productivity, quality variation of iron ore and cost of refractory raw materials. In this paper we report the development of THC for big and jumbo furnaces. Formulation was developed following a thermodynamic approach. Thermodynamic results were verified by Induction furnace corrosion study and estimation of mineralogical phases by XRD. Influence of THC raw materials was evident in thermodynamic simulation as well as corrosion of the refractory, by a representative BF slag. Corrosion of the THC, observed during induction furnace interaction study, was correlated with the quantum of liquid as well as the minerals formed during THC - Slag interaction and viscosity of the liquid formed . Desired performance, with the developed THC formulations, was achieved during field trials in BF with critical furnace operating conditions. THC properties, such as volatile matter, workability index, apparent porosity, bulk density and strength, after curing as well as firing in reducing atmosphere, and linear change after firing were optimised for the developed formulation.
02:00 pm
Behavior of carbon-based binders for blast furnace taphole clays focused on environment, safety, and performance
Tomás Oliveira | Universidade Federal de Minas Gerais | Brazil
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Authors:
Tomás Oliveira | Universidade Federal de Minas Gerais | Brazil
Aloísio Simões Ribeiro | RHI Magnesita | Brazil
Dr. Paschoal Bonadia | RHI Magnesita | Brazil
Eduardo Henrique Martins Nunes | Universidade Federal de Minas Gerais | Brazil
The liquid binder plays an essential role in taphole clay composition to guarantee its properties such as plasticity, adhesion, corrosion/erosion resistance, and ease of drilling during use in blast furnaces. Additionally, the binder also has a major role concerning environmental and safety aspects. Several studies have been carried out on taphole clay binders, but it is not common to find an in-depth comparative analysis between the different existing types. In this study, four commercially available carbon-based binders were investigated, namely a traditional coal tar pitch, novolak phenolic resin, low benzopyrene coal tar pitch, and petroleum-based binder. This study aims to understand the main characteristics of each taphole clay binder examined and define the best option to be used, depending on the needs of each blast furnace related to environmental, safety, and performance aspects. Specific tests to evaluate binders were carried out and associated to taphole clay properties.