Search Documents

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 J. N. Stevens, M. Tulwin, P. J. Lawlor

All metals producers are on an unending search for a competitive advantage. They need to produce in the most cost effective way. Sometimes a new mill might be considered but in this paper we present examples of how this might not always be necessary. A detailed investigation by an equipment vendor who can consider the mill and or plant as a complete entity: mechanics, automation and process control can often find solutions that are both lower cost and can be implemented in shorter time frames.

Oct 1, 2019

By Fernando Henrique Gomes de Souza

Techniques which use a spring to supply the bias force to actuator are well adopted since they are inexpensive and simple to construct. In this work it was design an actuator concept using bias-type device technique, which comprises two coils that mutually push against each other to supply the stroke. For the coils springs, it was used a wire of NiTi shape memory alloys (SMA) and a wire of 400 grade maraging steel as construction materials.

Aug 8, 2018

By Álvaro Lúcio

This paper outlines the DPC process as na economic and environment friendly option for the use of cultivated forest as a source of raw material for metallurgical charcoal.The DPC process was specially developed to bring logistic, environmental, technical, economic and global energy efficiency when compared to termal1 the existing biomass carbonization process. The DPC process utilizes the volatile materials (condensable and non condensable) as a source of the energy required by the carbonization process guarantying its complete combustion. As result the DPC process avoids the burning of termal1 the loaded wood, obtaining a higher charcoal to biomass yield, and avoids the emission to the atmosphere of polluting gases. Gases emitted by the carbonizing wood have na energy termal1e enough to dry the wood soon after its harvesting. By avoiding the storage in the field during na average of 150 days, the resulting economy is quite significant. As a termal1e1 the higher charcoal to biomass yield na termal1e1e economy is obtained through the reduction of the cultivated forest term. This paper emphasizes the economic advantages of the DPC process.

Aug 16, 2017

By Lesli Peterson

Spraying Systems Co® has continued to develop and evolve descale nozzles through the years. The most recent addition to the descale nozzle line, the DescaleJet® Pro, provides more impact and a more uniform distribution than previous descale nozzles. The improved performance has been achieved through multiple design changes such as a smoother approach, updated vane design and improved carbide orifice. In addition to providing improved spray performance the nozzle also lasts longer than previous versions. The new technology has been thoroughly tested in the lab using impact measurements and accelerated wear testing. In addition to lab testing the nozzle has provided improved performance and longer wear life for those that have made the change to the new technology. The new nozzle technology and the benefits to the rolling mill will be discussed.

Jul 30, 2018

By José Fagundes Jr., Juliano Braz Possatti, Bruno Câmara Vieira, Gabriel Godinho Alves, Bruno Bastos da Silva Murad, Cristina Maria de Oliveira Roque

Driven by market trends, increasing environmental accountability, government regulations and fostered by the Company’s strategic plan, ArcelorMittal Tubarão has developed new steel products to deliver better solutions to fit each customer’s needs. This often translates in higher strength, more complex and dimensionally challenging (thinner and wider) steels to attend a broad array of goals, such as reduction of vehicles fuel consumption and carbon emissions, increase in fatigue performance of heat treated parts, higher load capacity per net weight in vessels or wagons and lower supplying lead time as ArcelorMittal Tubarão establishes itself as a domestic option for so far imported grades. Based on the annual Product Development Plan, a structured workflow involves technical discussions from an operational point of view about safety issues, metallurgical project, steel grade family definitions, offline simulations prior to field trials, deformation resistance and process parameters adjustments and scheduling strategy. As a result of the increasing synergy between the areas, the share of new materials developed in recent years has been sustainably increased up to 15% in 2018, adding value to the final product without impact on hot rolled coil output and with a low cobble index.

Oct 1, 2019

By Dagoberto Brandão Santos, Kairo de Barros Guimarães, Túlio Magno Füzessy de Melo

The effect of the cooling conditions on the microstructure and hardness of a Dual Phase hot-rolled steel 800 MPa strength was investigated. Simulations of the cooling conditions using a dilatometer were carried out from samples of a hot rolled coil with variations of the intermediary temperature from 620 to 740°C, isothermal holding time between 1 and 10 s and coiling temperature between 50 and 400°C. In addition, two CCT (Continuous Cooling Transformation) diagrams were developed to evaluate the effect of the isothermal holding time on the phase transformations of the remaining austenite. It was observed that the intermediary temperature has a strong influence on the kinetics of the phase transformation, as well as the isothermal holding time influences the amount of ferrite formed and, consequently, the final microstructure and hardness of the material. The coiling temperature did not cause significant changes in the amount and morphology of the ferrite, but a gradual replacement of martensite with bainite was observed, which, in addition to the self-tempering effect, contributed to the hardness reduction.

Oct 1, 2019

By Alessandra Spaghetti

Rolling small-diameter hot wire rods at high speeds with conventional laying head pipes can wear the pipe out frequently and affect quality and consistency in the final product. Laying head upgrades using Sandvik SAF2507LHP™ (UNS S32750) tubes make possible to achieve optimal metallurgical properties, smooth coil formation and easier coil handling. Operators can also avoid unwelcome shutdowns due to frequent worn pipe changes and turndowns. Sandvik have been developing different customers and understand their process needs. The suitable selection materials that are able to withstand high levels of wear better than low alloy and carbon steel grades that are commonly used in industry is very important to improve the quality and increase productivity. UNS S32750 tubes were demonstrably superior to low alloy and carbon steels when used in Laying Head Pipe system regarding tubes lifetime, reducing replacement, production interruptions and increasing reliability.

Aug 17, 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 Ernst Lindemann

The SMS group has developed the ultrasound technology “HD scan” for inspection of the internal quality of as-cast products. This method of sample analysis requires less preparation work and is safer than the current, most common technique of etching and/or sulphur printing. Furthermore, this technology offers a three-dimensional view into the sample of the cast product and thus more representative information for a better quality evaluation. The internal quality evaluation can be performed automatically and objectively by software based on clear statistical methods. A quantitative centerline segregation rating can be assigned to each sample, based on the size and distribution of segregates detected by the unit. Internal crack statistic (length, position, orientation, etc.) and narrow side profile can also be measured. Grain macrostructure can also be visualized which allows for a potential optimization of casting parameters like strand cooling, soft reduction or electromagnetic stirring. The accuracy of the new method was proven by parallel metallographic investigations of more than 100 samples of different steel grades and sample shapes. Automatic defect evaluation and classification was compared against macroetching results. It was found that HD scan identified more defects and the visualization of the macro structure could be performed in more cases than with macro etching. All tests, comparisons, further developments and analyses for various steel producers and steel treatment companies have been conducted at the HD scan unit, located at the SMS group headquarters in Düsseldorf, Germany (Figure 1). Based on the results, SMS group has designed a unit which can be used in industrial scale.

Aug 17, 2017

By Wolfgang Oberaigner

Primetals Technologies has always been a driver of innovation in steelmaking, especially by providing sophisticated process expert models for continuous casting machines. This capability is demonstrated by recent advancements in automation solutions that include: DynaPhase, Dynacs 3D, and DynaGap. This state-of-the-art suite of dynamic secondary cooling and soft-reduction packages take into account thermodynamic effects such as shrinkage and phase transitions, and thereby significantly contribute to direct quality improvements during the solidification phase in the continuous casting process. Speed Expert calculates an optimum casting speed for every casting situation, and additionally recommends a strand speed so that the point of final solidification is positioned at the end of a segment for optimum soft reduction. In the case of steel grade changes, the Intermix Expert precisely calculates the chemical properties of the mixed steel, thereby minimizing losses due to deviations from required specifications. The Nozzle Expert is a new model that detects clogged nozzles and broken hoses in secondary cooling systems. The first installations were highly successful and customers are pleased with impressive reductions in maintenance costs and improved steel quality. This paper describes these innovative process automation solutions and gives an overview about the successful results achieved within the first installations.

Aug 16, 2017

By Alessandro Marques

Based on a short overview regarding steel defects in the final product, several refractory approaches to maintain or increase steel cleanliness are reviewed in this publication. By applying a ladle to mold approach, one potential to maintain cleanliness is to reduce the probability of air ingress by selection of a suitable slide gate system. Following this path, also the influence of a special configured impact pot is presented to maintain steel quality. Finally, higher productivity as well as cleanliness can be provided by selection of PROIL as a revolutionary product at the casting machine.

Oct 30, 2017

By Jean Viana Bahia, Antônio Adel dos Santos, Vicente Tadeu Lopes Buono

During cold rolling of Cr-Mo alloyed DP steel, considerable oscillation of thickness may occur. The literature points out that such occurrence is due to non-uniform cooling of the coil after the hot rolling process. Since the austenite transformation in this steel continues after coiling, the microstructure and, consequently, mechanical properties are very susceptible to natural variations in cooling rates associated with distinct positions of the coil. The influence of coil cooling conditions on thickness oscillation during cold rolling was evaluated in this work by using both industrial experiments and dilatometer tests. It was verified that an industrial coil presented large variation of mechanical properties associated with its heterogeneous microstructure. Consequently, thickness oscillation occurred during cold rolling. Dilatometer tests simulating hot run-out table and coil cooling showed that the austenite transformation is very slow under small cooling rates that occur after coiling. Thus, the slow transformation rate makes the coil very susceptible to environmental conditions around it during its natural cooling and is responsible for variation in mechanical properties of the coil. To ensure the formation of a more homogeneous microstructure in the whole coil, it is necessary either to make use of technologies that improves the cooling uniformity or to adjust the steel alloy design. The latter alternative has been done with relative success by using conceptions with lower amounts of Cr and Mo.

Oct 1, 2019

By Wen Xuan

Oolitic iron ores have significant economical importance because of their extensive resources in the world. However, their utilisation is often quite limited due to the high content of phosphorus inside. The phosphorus is often finely disseminated in the oolite structure and generally not liberated in the form of free particles. The iron ore used in this work is a typical oolitic goethitic iron ore with high phosphorus. The process of phosphorus removal from this ore is difficult because the phosphorus is not present as distinct minerals. As a result, no physical beneficiation process is able to separate the phosphorus from the iron bearing phases. The current concentrate contains low iron grade (Fe ~49%) and high phosphorus content (P 0.7~0.8%). The acid leaching is a potential way to dissolve phosphorus. Previous studies have shown that the thermal treatment makes the phosphorus more accessible for the acids and enables more efficient phosphorus dissolution. Some chemical additives are reported to enhance this phenomenon. A series of tests have been carried out using roasting - grinding - magnetic separation - leaching technologies to remove the phosphorus from this current concentrate. In the first stage, several tests were performed at pilot scale under the same conditions as described in some publications. The achieved results were similar to those from previous tests at laboratory scale. In the second stage, new test conditions were investigated in laboratory scale in order to achieve better result and to reduce the operational cost.

Aug 1, 2018

By Rodrigo Fina Ferreira, Jacek Kolacz, Luciana Gois, Neymayer Pereira Lima

The recent developments on the sensor detectors together with the higher capacity of the machines, due the high-speed computing recent advances, have made possible extending the application in the mining industry. The use of x-ray fluorescence, x-ray transmission and radiometric sensor based sorting can selectively remove gangue minerals in different size fractions for different minerals. This paper summarizes the potential application of SBS for an iron ore in three size fractions aiming to increase the %Fe after the removal of particles with main gangue minerals associated. Pilot plant tests were carried out with samples of iron ore in different size fractions and different content of hematite and gangues. The use of x-ray transmission sensor showed the possibility to increase the %Fe from about 63% to above 68% for particles below 80mm and 45mm, after the removal of low density particles. The presence of fines on the feed affected the performance of the SBS X-rays transmission machine, especially for the fine fraction feed. The mineralogical determination, carried out to know the association between hematite and gangue minerals, and the density of the particles on the feed, can be used to preview the quality of products of the x-transmission sorting process.

Oct 3, 2019

By Florian Markus Penz

The increase in Basic Oxygen Furnace (BOF) plants in steelmaking has given rise to renewed interest in a dynamic simulation of the BOF process. Material and process costs can be saved with optimized process times and targeted charging of scrap and slag formers. Beside hot metal, scrap is the main source of iron in the BOF process. Furthermore, scrap is used as a coolant during the process due to exothermal chemical reactions occurring in the BOF. In this paper, the melting and dissolution behaviour of scrap in the BOF process is discussed. A new dynamic thermodynamic and kinetic Matlab® model used to simulate scrap melting behaviour as a function of various scrap surface parameters and particle size is presented, as well as the influence of scrap properties on liquid bath temperature and final crude steel composition after a defined blowing period.

Oct 30, 2017

By Ananda Moreira Vaz Ourique de Avila

Ferritic stainless steels have been used in the making of high and intermediate temperature operation solid oxide fuel cells (SOFC) interconnects, replacing the ceramic materials. However, at high temperatures, on the order of 700-850 0C, these steels can present significant oxidation and degradation processes, promoting increased electrical resistivity and corrosion losses that result in contamination of the electrodes and reducing the performance and the useful life of the SOFC. Thus, the knowledge on kinetics of oxidation/corrosion of these steels and their relationship with the microstructural transformations are of great importance. In this study, samples of ferritic stainless steels AISI 430, AISI 441 and Crofer22APU® were tested for oxidation at high temperature (800 0C) for long periods of time (up to 3,600 hours) and mass gains were monitored allowing the determination of the oxidation behaviors of these steels. Additionally, the microstructural characteristics of the samples before aging (corrosion-oxidation test) and after various oxidation times were evaluated by optical (OM) and scanning electron microscopy (SEM), as well as by micro chemical elemental analysis (EDS) and X-ray diffraction (XRD) phase analysis. Electrical characterization allowed determination of electrical area-specific resistances (ASR) characteristics of the systems studied, thus relating the electrical and oxidative behaviors of steels evaluated.

Aug 7, 2018

By Jörg Schwelberger

Government regulations around the world concerning environmental care are becoming more stringent, also including regulations and restrictions of depositing and use of dust, sludge and slag generated in the iron and steelmaking process. With this scenario, by-products such as iron containing dust, sludge, oxide fines, mill scales and slag, become a valuable resource and recycling may be a profitable activity within a plant. Up to ten percent in mass of the total steel output of dust, sludge and mill scale by-product materials and more than 40% of slag by product are generated within an integrated steel plant with an iron content ranging from 50% to 65% for fines and up to 25% for BOF-slag. Slags are being widely recycled and used in the cement industry, as is the case for BF slag, and in the construction industry in the case of BOF slags and EAF slags. However, value of BOF unmodified slag is typically low and environmental regulations limit the usage of the unmodified BOF slag. This paper describes innovative solutions for recycling of fines using cold briquetting technology and the modification and granulation of slag from steelmaking that increase the value of the by-product and yield a marketable product.

Aug 16, 2017

By Nelson SOUTO, Nicolas LEGRAND, Christian COUNHAYE, Don EARLEY

The work is motivated by the automotive customer requirements for a roughness with high peak density (RPc > 75 peaks/cm) on steel sheet surfaces to maintain a good strip surface finish after painting. For that purpose, a new approach is utilized to compute roughness transfer and predict final roughness on uncoated steel sheets (average roughness, skewness, peak density) as a function of temper rolling conditions. The approach is based on the Monte Carlo method combined with the Abott curves and an auto-correlation function to numerically generate roughness profiles for roll and strip respectively. To compute the roughness transfer due to the interaction between roll and strip surfaces during rolling, a composite Abott curve that combines roll and strip Abott curves is used with an asperity crushing model integrated with a rolling model. This enables simulating two roughness transfer mechanisms in the roll bite: the strip asperity crushing mechanism by roll roughness and the strip asperity ploughing mechanism due to roll-strip interfacial sliding speed. The model shows the importance of considering the two mechanisms to predict roughness transfer correctly when strip elongation is high, typically a few percent, and roll bite friction is low. In these conditions, the forward slip at the exit of the roll bite tends to erode strip roughness significantly and decrease considerably the peak density on the strip. For lower elongation levels (~1%) and high roll bite friction, the ploughing mechanism becomes negligible and roughness transfer is controlled by the crushing mechanism only. With these two mechanisms, the model reasonably predicts the evolution of average roughness and peak density over a wide range of temper rolling conditions (new/worn work rolls, hard/soft grades, various elongations), but skewness is more difficult to predict for some trials.

Oct 1, 2019

By Leonardo Camilo dos Reis, Edmilson Fernandes Dadomi, Claudio Silva de Paulo

In the hot strip mill production, one of the factors that may affect the productivity is the occurrence of failure due to the geometry of the strip at the exit of the rolling mill, because the tip of the strip can turn-down or turn-up. This study had the objective of evaluating the behavior of the strip when leaving the working rolls, through numerical simulation, aiming to know the influences of the main variables that govern the formation of the turn-down. The methodology consisted in performing the computational simulation of the strip mill and to vary the operational and geometric parameters that could influence the process. The results showed that the rolling of hot strips of HSLA material with final thickness varying between of 3 to 6 mm and a reduction of 6.6% to 11.0% in the last stand of a hot strip mill, tends to bend towards the roll with larger diameter, higher friction coefficient , higher temperature and lower limit of material flow. It was observed that the variation in diameter is the main factor that contributes to the formation of the curvature of the front-end of strip. Based on these results, several measures were implemented in the industrial line, with a significant reduction in the occurrence of turn-down.

Oct 2, 2019