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By Maycon Athayde

Samarco produces high quality iron ore pellets processed in straight grate furnaces. This process is essential in order to obtain adequate mechanical strength to the pellet transportation and operation in the reduction reactors. All mechanical properties of the agglomerates are obtained during the stage of firing where the slag and sintering bond happens, thus it is a decisive step to improve the pellet quality. Therefore, the velocity distribution of gas flow within this zone must have homogeneous and even velocity distribution. Hence, it was developed a mathematical CFD model to characterize the gas flow in the burning zone, applying the equations of conservation of momentum, mass and energy and an uneven flow distribution was identified and the gas velocity analyzed and validated through experimental data. On the other hand, on the present paper, an improved firing zone burner were developed and industrially implemented in a way to mitigate the uneven flow pattern detected aided by CFD. Different burner designs, based on CFD analysis, were experimented in order to succeed on the aggressive condition. The combustion was investigated and burner efficiency evaluated and compared with the simulation purposed.

Aug 2, 2018

By Antonio Adel dos Santos, Carmos Antonio Gandra, Fabricio Mazola da Silva Paiva, Vicente Tadeu Lopes Buono

Abstract Usiminas Steel Plant in Ipatinga installed an accelerated cooling device named CLC (Continuous On-Line Control) in 2010, enabling it to supply steels produced by TMCP (Thermo Mechanical Control Process) technology. This technology complements the TMCR (Thermo Mechanical Control Rolling), with the inclusion of the accelerated cooling process after controlled rolling. There are various gains in terms of quality and productivity associated to the application of such technology. However, the flatness control for API steel becomes crucial because large thermal stresses may be generated due to thermal heterogeneity during the fast cooling when the austenite phase decomposes mostly into ferrite and bainite. In literature, there is lack of knowledge regarding a full understanding of the relation among cooling conditions and plate flatness. Therefore, this work has focused on the effect of the cooling strategy for API steels, aiming at optimizing flatness and keeping the mechanical properties within the specified ranges. The starting point was dilatometer simulation, where cooling conditions such as start cooling temperature, SCT, finish rolling temperature, FRT, and cooling rate, CR, were changed in order to evaluate their effect on microstructure. Those laboratory conditions supposed to give the best results were transposed to industrial scale, so as to produce experimental lots of plates with five different cooling strategies. It was shown the possibility to find a cooling profile that guarantees the balance between mechanical properties and flatness requirements. The influence of cooling strategy on flatness was explained by the varied heat transfer regimes occurring from hot steel surface to the ambient

Oct 1, 2019

By Yong Tian, Tian Zhang, Zhao-Dong Wang

To meet the requirements of high-performance steel plates, while reducing manufacturing costs and saving energy, the advanced cooling system for plate mill (ADCOS-PM) with functions of accelerated cooling (ACC), ultra-fast cooling (UFC), and direct quenching (DQ) was researched and developed by the State Key Laboratory of Rolling and Automation (RAL). Since 2003, several sets of ADCOS-PM device were developed and implemented in industrial practice. To fully utilize the ADCOS-PM technology, the combination of various strengthening mechanisms was promoted by NG-TMCP technology and low-cost, high performance plates were produced such as pipeline steels, and high-strength construction machinery steel.

Oct 1, 2019

By Leonardo Araújo Peruch, José Fagundes, Henrique Carneiro Pinto, Marco Túlio Costa, Nayara Coutinho, José Fabiano Martins Assunção

The objective of this project was to increase the hot charge by reducing reheating energy consumption and raising the productivity of ArceloMittal Tubarão's hot strip mill by changing the HSM’s schedule process with optimization of the relocation process of slabs after HSM’s chance with focus on slab temperature in reheating time. The project began with the revision of metallurgical rules for the relocation of materials, definition of criteria temperature setting (hot / cold), definition of restrictions of the process and review of modus operandi scheduling process. With the implementation of the process / system it is expected to achieve a 10% increase in the hot charge index in slabs reheating furnaces and increase productivity of the ArcelorMittal Tubarão hot strip mill

Oct 3, 2019

By Ronaldo Esteves Ribeiro, Jefferson Felipe Faria Clemente, Carlos Victor Francisco dos Santos, José Herbert Dolabela da Silveira

n recent years, the market for thick plates has been highly competitive, in this scenario the plates quality is a critical success factor. In this process, the quality of the cut in thick plates is one of the important requirements for the customers, by the visual aspect as well as the technical aspect of the plate application. In the shear line, the cutting is done by shearing to trim tips, subdivide plates, trim side edges, remove samples, eliminate defects, etc. The cut is obtained by the penetration of the upper knife in the plate, causing plastic deformation in a certain region and hardening. If the clearance between the knives is adequate, the cracks will be close to the centre of the plate thickness and will result in a good cut quality. This work will present the theory of cutting of thick plates, the types of shearing, the quality of the edge in the cut, the types and the main characteristics of the knives.

Oct 1, 2019

By Francesco Toschi

The Special Bar Quality family comprises a wide range of steel grades, mainly requested by the automotive, energy and engineering sectors, for applications where significant performances are required (eg. stresses, temperatures, working cycles, etc.). To meet these requirements it is necessary to reach a precise control of both the mechanical characteristics and metallurgy structures along the whole production chain. For semi-product with large dimensions, such as equivalent diameters around 300 mm, this is traditionally obtained through a manufacturing route which comprises the casting in ingots followed by reheating, forging and rolling. After 2010, new processes were investigated and technologies developed to replace the ingot route with a continuous casting followed by controlled high-reduction rolling. In these processes a seamless integration of CCM with rolling is implemented so to obtain the precise control of material flow, applied deformation and working temperatures. By using the proper combination of rolling diameter, speed and applied reduction, a very good control of the metallurgy structure across the whole section can be obtained, so to also remove the internal discontinuities ("voids") generated during the continuous casting. These processes, which can be defined "forging-like", are applicable to several grades also with large semi-product dimensions (300 mm and more). Besides, removing the ingot route means increased yield and productivity, which is very beneficial to the economical management of the plant. An example of this "forging-like" process is represented by the high-reduction blooming stand installed by Acciaierie Venete in the Padova-Camin mill. This article describes its main concepts as well as its technology and process features.

Oct 30, 2017

By Jônatas Venancio Barbosa, Dagoberto Brandão Santos, Túlio Magno Füzessy de Melo

In this work, the mechanical and metallurgical behavior of titanium added ultra-low carbon (ULC-Ti) steel under hot and warm working conditions was studied by means of dilatometer compression tests. Double compression schedules were performed at temperatures between 700°C and 1000°C, inter-pass times of 0.5-100 s, and deformations of 0.5 and 0.3 in the first and second stages, respectively, with strain rate of 1 s-1. The analysis of the flow curves obtained allowed the evaluation of the softening characteristics of the steel. The softening and microstructure features indicate different restoration mechanisms depending on the temperature range. Static recrystallization with rapid microstructure restoration is observed at temperatures within the austenitic and intercritical field. Strain induced boundary motion and recovery mechanisms apparently control the restoration process in the ferrite region. In general, flow stress curves showed dynamic recovery behavior. Only the deformation in the intercritical region produced a peak in the flow stress curves. Isothermal holding tests associated with single hit compression indicated the presence of dynamic strain induced transformation, accelerating the softening kinetics at the intercritical region.

Oct 1, 2019

By Samuel F. Rodrigues, Clodualdo Aranas Jr., Fulvio Siciliano

The application of thermo-mechanical control processing (TMCP) in hot rolling of steels has become a common routine since the last 60 years. The understanding of the physical metallurgy behind TMCP played a major role in the early developments. Physical and numerical simulation works are performed firstly to derive the fundamental metallurgical knowledge and secondly to conceive existing TMCP practices. In this paper, a summary TMCP techniques is presented. The occurrence of dynamic transformation of ferrite in the austenite region is shown by means of synchrotron light diffraction methods. This phase transformation mechanism is taken into consideration and its effects on TMCP are proposed in an exploratory way.

Oct 1, 2019

By Eduardo Vitral

The present study focuses in the simulation of pattern formation by ion beam sputtering on a material surface. This process is responsible for the appearance of unexpectedly organized patterns, such as ripples, nanodots and hexagonal arrays of nanoholes. A numerical analysis of preexisting patterns is proposed to investigate surface dynamics, based on a model derived from a Kuramoto-Sivashinsky anisotropic equation, in a two dimensional surface with periodic boundary conditions. While deterministic, its highly nonlinear character gives a rich range of results, making it possible to describe accurately different patterns. A finite-difference semi-implicit splitting scheme is employed on the discretization of the governing equation. Simulations were conducted with realistic coefficients related to physical parameters (anisotropies, beam orientation, diffusion). The study dealt with a random and a monomode 1D structure initial condition in order to understand how the shape and wavelength of the initial pattern evolve with time. Ripples and hexagonal patterns were observed in the results, being physically consistent with the phenomenon. Moreover, the Method of Manufactured Solution has been used as verification of the developed numerical scheme.

Aug 16, 2017

By Juliano Braz Possatti, José Fagundes Júnior

This project involved a teamwork including process control, maintenance and operation specialists, R&D and CTO experts to identify and actuate on each opportunity to increase charging temperature, furnace efficiency, decrease discharging temperature when possible, decrease FM and RM cycle time (mainly speed increase and interpass time decrease), tracking zones optimization, safe use of equipment power limits, safety interlocks revision and tune models for Mill Pacing Control and Slab Design.As result of these efforts, ArcelorMittal Tubarão HSM today occupies a prominent position among the best HSM of similar layout and produced mix of the group and worldwide. This paper will show the path which was followed by the AMT HSM team to achieve more than a 20% productivity increase resulting in a hot coils production per year more than 700 million tons higher.

Oct 1, 2019

By Jean-Philippe Houde

The Blast Furnace Campaign lifetime is highly depending on the wear progress of the hearth lining. This progress is monitored in general through single and double thermocouples at the cold side of the lining. This type of monitoring becomes ineffective as soon as heat resistance will be formed in the refractory lining. Paul Wurth’s monitoring system, consisting of MTP-Sensor and Heat Flux Probes, is able to identify such heat resistances to give a true hearth lining wear. Since last year Paul Wurth is also able to install safely those MTP-Sensor and Heat Flux Probes on running blast furnace without salamander tapping, thanks to a newly developed cooled core drilling device. Blast Furnaces that are equipped with Paul Wurth’s monitoring system have optimized their campaign lifetime as they received right information upon the true wear lining such as detection of heat flux transfer failure, detection and monitoring of brittle layer or detection of hot spot.

Aug 16, 2017

By Michel Rodrigo Luiz, Glaudistoni da Silva Félix, Osmar Duarte Junior

This article deals with a project to reduce the preparation time and threading the coils in the input section of a pickling line coupled to the cold strip mill (PLTCM) at ArcelorMittal Vega. The project developed serves for the detection and elimination of bottlenecks in the input section. The project was conceived by the philosophy of the Theory of Constraints (TOC) and Lean Six Sigma (6 sigma), here seen as sequencing serial / parallel in the preparation and threading the coils. In this context, a proposal to modify the automatic sequencing and reduction of interruptions due to failure of the automation / equipment confirmed its effectiveness reducing the total time preparation time and threading the coils in the entry section by 15%. This project was developed without investment costs, bringing gains on the order of US$613,769.00.

Oct 1, 2019

By Rogério Martins Pereira, Charles Pierri de Souza, Lucas Gabriel Correa

The Tandem Cold Mill is composed by stands with rolls positioned so that the rolling force can be transmitted to the strip being processed. Due to the mechanical stresses inherent in the process, the roll bearings are heated and are equipped with lubrication and cooling systems. Nevertheless, there is the challenge of continuously monitoring the temperature of the bearings, which would allow preventive intervention in case of overheating. This paper presents an in-house solution to temperature measuring system applied to the backup roll bearings of a continuous Tandem Cold Mill. The system uses Zigbee technology and is integrated with the main control system, allowing early diagnosis of bearing heating and proper intervention. Results and features of the system are discussed.

Oct 1, 2019

By Jerin Russell

This paper presents a new instrument for real-time detection of excessively coarse material in the overflow pipes of individual hydrocyclones using a non-invasive acoustic measurement technique. The hydrocyclone is an important device used in mineral processing beneficiation circuits for classification of mineral slurries by particle size. It separates a single input stream into two output streams; an underflow of coarse particles that undergo additional grinding for further size reduction, and an overflow stream of finer particles that typically goes directly into a flotation circuit for recovery of the desired mineral. However the hydrocyclone is a major piece of equipment in the beneficiation process that has no instrumentation for directly measuring its performance. The parameters currently measured – inlet pressure, feed flow rate, feed flow density – are common to the entire hydrocyclone cluster which typically has three to twelve hydrocyclones. Thus no information is available to detect individual hydrocyclones that are operating poorly. The system described in this paper detects the presence of unwanted excessively coarse material in the overflow stream of a hydrocyclone using sensors mounted to the exterior pipe surface. It provides real-time monitoring, trending and alarming of the coarse material level. This enables operators to identify poorly performing hydrocyclones, and enables corrective action to reduce or eliminate the coarse material discharge. Improving the classification efficiency of individual hydrocyclones will improve the overall classification efficiency of a hydrocyclone cluster. This leads to less variation in the particle size distribution and slurry density in the flotation feed, which will in turn improve overall mineral recovery. The reduction of unwanted coarse material in the flotation feed reduces the accumulation of that material in flotation cells. This can lead to equipment damage, and unplanned shutdowns due to events such as blocked dart valves.

Aug 16, 2017

By Daniel Hajduk

Efficiency of back up rolls depends mostly on two parameters – length of campaign and dressing amount after the campaign. The longer the campaign (in terms of rolled tones) is, the higher the dressing amount. To solve this task properly it is necessary to know the distribution of accumulated damage in the working layer of the roll caused by previous campaigns and by loads (separating force and bending) during present campaign respecting changing conditions of material properties (hardness) through radius of the roll. To find an optimum dressing amount an algorithm has been developed and specialized computer program will be presented, that takes real measured loads during the backup roll campaign, calculates fatigue damage in the roll and suggests relevant dressing amount. This can help to prolong service life of rolls, minimize the risk of spalls and reach maximum efficiency in terms of rolled tones/km per roll.

Jul 30, 2018

By Ian James McDonald

Each year, approximately 400 million tons of blast furnace slag is produced worldwide with a tapping temperature of around 1,500°C. It is normally used as a substitute for cement clinker or as an aggregate material in road construction. Currently, the slag is granulated in wet-granulation plants using large volumes of water and to date, it has not been possible to utilise the remnant heat energy of the molten slag, which amounts to approximately 1.8 GJ of energy per ton. However, in an R&D project currently underway led by Primetals Technolgies and industrial partners, a new dry atomising technology is being investigated to use air to cool molten slag and recover the lost heat energy. The resultant pelletised slag fulfils the same criteria as wet-granulated slag for use in the cement industry. Phase 1 of the project has now been completed where a technical plant was set up at the University of Leoben in 2012. A series of dry-slag granulation campaigns were carried out using remelted blast furnace slag. The elevated offgas temperatures and the quality of the slag product as verified by the FEhS Building Material Institute have shown the process suitability as an industrial application and the decision was taken to escalate the project from large laboratory scale to a full size pilot plant. The phase 2 development of this plant is now underway and is scheduled for installation at the site of an industrial partner in early 2016 where full slag flow will be fed directly to the plant from Blast Furnace ‘slag runners. This paper will show the development path taken to date and the planned route to our goal in 2016 of being the first to industrialise the ‘game changing’ process of dry Slag Granulation with Heat Recovery from the slag.

Aug 16, 2017

By Richard Harvey, Robert Paul Mawer

In recent times there has been an increase in the demand from Steel plants for a technology that offers the most economical environmentally sustainable solution. In terms of blast furnace off gas cleaning this has seen a drive towards Cyclone technology replacing the older Dustcatchers. Cyclone technology can achieve dust removal efficiencies as high as 95% increasing the dust yield at the primary stage of gas cleaning. The dry dust (rich in Fe and C) can then be recycled to the Sinter Plant or Blast Furnace. Capture of dust at this stage also has the benefit that sludge generation from the secondary stage is also reduced meaning less waste to landfill and / or recovery of some of the by-products for further use. Primetals Technologies already offer a state of the art Tri-Axial Cyclone installed on many sites world-wide, however, this paper focuses on a hybrid of this technology, the DustClone. The DustClone is a low CAPEX unit that is essentially a Cyclone housed inside the Dustcatcher. This unit is aimed at operators who may be carrying out smaller scaled shutdowns / repairs that normally have a reduced CAPEX. This paper describes the technology that Primetals Technologies have developed.

Oct 1, 2019

By Edo Engel

Whereas only a handful of decades ago, typical blast furnace working volumes were below 1000 m³, such furnaces are currently designated compact or even mini blast furnaces. For certain business cases, however, small furnace sizes remain an attractive option. Decades ago, this size blast furnace would have produced a maximum of 0.3 Mtpa with its 600 m³ working volume over a campaign of up to four years. The current state of technology and operational know–how will allow a similarly sized furnace to produce over 0.7 Mtpa while achieving the multiple decade campaigns that have become familiar to steel producers in full sized operations. This level of productivity, but especially the reliability and supply security associated with mature technology, allows for integration into minimills or taking a first step towards a full scale BF–BOF integrated mill. Steel producers considering such scenarios, which are typically attractive for emerging economies, are confronted with fundamental decisions, one of which is for the technological basis for the compact or mini blast furnace to be included in the plant. This article addresses some of these decisions from an operations–based perspective. A small number of case studies is included.

Aug 16, 2017

By George Schipper, Peter Gelten, Pepijn Adriaen, Hugo Uijtdebroeks

Tata Steel IJmuiden Hot Strip Mill 2 (HSM2, 5.5 Mtonnes/yr) is currently being upgraded, resulting in an increased rolling force and motor power capacity. With the current conventional work roll spray cooling, a deterioration in work roll & strip surface quality performance is expected as a result of the increased mill capacities. In order to improve strip surface quality, HSM2 decided to do a full-scale production trial with High Turbulence Roll Cooling (HTRC) at stand FM2. HTRC is a novel way of roll cooling using a high turbulent flow regime. HTRC is positioned very close to the roll surface and gap exit, which is beneficial for the roll surface quality. It is operated at a high flow rate but at a low pressure. HTRC not only significantly improves the roll surface quality, in addition, it makes high pressure pumps, needed for the conventional spray cooling, redundant, leading to substantial savings on electricity costs and thus CO2 emissions. HTRC is in trial operation since 7 August 2018. Results show no operational issues, an excellent roll surface quality and an increased cooling efficiency. In summer 2020 stands FM1-FM2-FM3-FM4 of HSM2 will be equipped with HTRC.

Oct 1, 2019

By Steven G. Jansto

Carbon content and continuous casting parameters affecting solidification behavior, such as super heat, mold level fluctuation, heat transfer, fine grain chill zone depth and other process solidification parameters directly influence the surface and internal quality of the steel strand. The carbon content, resultant fine grain chill zone depth, the equiaxed-columnar transition zone and the strain energy are the primary drivers that govern hot ductility behavior. These factors influence the propensity for crack formation during the unbending section in the continuous casting process. Elements such as microalloys exhibit secondary or tertiary root causes for crack formation and are not the primary crack formation root cause. This solidification research identifies that the traditional hot ductility as measured via the percent reduction in area (%RA) at elevated temperature grossly overstates the minimum ductility required to assure crack-free casting of microalloyed steels. The strain at the ultimate tensile strength exhibits a very high correlation coefficient with strain energy while an extremely low correlation coefficient is exhibited with %RA.

Oct 30, 2017