EFFECT OF CONTINUOUS CASTING PROCESS PARAMETERS FOR STEEL BILLETS ON ROUND CROSS SECTION PRODUCTS

Eng. Hesham Saad^1*, Dr. Mohamed Gamal Khalifa², Dr.Abdelrhman Ibrahim Hassan² and Dr. Taha Mattar^2,3

¹Arabian steel Industries, Ain Sokhna, Suez, Egypt

²Tabbin Institute for Metallurgical Studies (TIMS), Tabbin, Cairo, Egypt

3Central Metallurgical Research and Development Institute (CMRDI), Cairo, Egypt

Eng. Hesham Saad

Key words: continuous casting, steel billet, billet casting, near net shape casting, standalone rolling mill

Background

Continuous casting is the vital step in the steel plant for converting liquid steel into solid slabs or billet/blooms. The success of continuous casting has significant impact on the economy and quality of steel product. Ney technologies have been actively developed in the process over last few decades to increase productivity and as a result lower operation cost.

Nowadays CCM also, could be considering as second turning point in transformation from standalone rolling mill to standalone mini mill or endless rolling moll. Where is rolling mill merged directly to steel melt shop, SMS, with major benefit which is no more need for steel billet reheating furnace unit, where is CCM merged directly to the rolling mill stands through induction heater.

The recent work investigates the developing of endless rolling mill will be studied as a CCM third turning point, based on major question, can we maximize the benefits, where is no more need for roughing stands stage of rolling mill, by studying of various factors impact on the casting minimum round – cross section of carbon steel billet by continuous casting machine to be feeding the intermediate stands stage directly.

The present work aims to investigate how much can mering of (BAT), utilize and optimize to serve well targeted transformation of standalone production and manufacture units’ concept and comply with sustainable development goals with focusing on the consumption and production and to ensure sustainable consumption and production patterns

Introduction

“Worldwide consumption and production — a driving force of the global economy — rest on the use of the natural environment and resources in a way that continues to have destructive impacts on the planet. Economic and social progress over the last century has been accompanied by environmental degradation that is endangering the very systems on which our future development — indeed, our very survival — depends.

Sustainability Matrix elements” that as per SDGs no 12 declare

And based on that we can define the main three elements of sustainability matrix which are environment, economic and social, Economic element care about transformation of linear economy to circular economy or green economy. Environment element care about transformation of social justice to environmental justice. Society element care about considering the social cost.

And the 4^th important element can be added is the “Technology “ … which can be defined “Technology is the application of scientific knowledge for practical purposes or applications “ and technology can be also classified into 6 main categories construction, transportation, communication , bio related, energy, and finally manufacturing. And we can exceed the main role of technology should be “to facilitate not to complicate”, and the transformation of technology from traditional technology to sustainable technology is the main responsibility of all researchers, I men RnD men

And traditional technology matrix elements could be defined as, product, production/manufacture and finally the Process, and we can exceed, the sustainable technology matrix element include, GLC technology, Green product which apply the 4 Rs (reuse, reduce, recycle and recovery) or zero waste role, Lean (production / manufacturing) which apply the role (make to order) and finally Clean process which apply zero emissions role

Methods

In 2010, One of the most of technological supplier introduce new technology under the title “Endless casting and rolling “which consider decisive change in the steel midstream, which include steel melting, steel casting and downstream stage which include steel hot rolling. i.e., those two stages are merged in one stage.

The merging stages of production unit continuous casting machine, CCM, which handling the transformation of liquid steel to semi product, slab bloom and billet, and this unit is working under the role (make-to-stock) and manufacturing unit, hot rolling, HR, which handling the transformation of the semi product to final product, re-bars and profiles and this unit is working under the role (make-to-order).

The most important result of this merging transformation is the ejecting of re-heating furnace unit from the hot rolling mill process. And that consider the new hot rolling as sustainable technology because of avoid the emission of the re-heating unit due to combustion of fuel, 30 cubic meters per each ton billet, and also avoid 2 percent due to the oxidation result of the heating process.

And we can exceed, the transformation finally effect on the Opex and Capex in the same time where , considering the Opex , avoid the losses due to the oxidation and avoid the emission result of fuel combustion , and finally avoid the storage cost of the semi product , and concerning the Capex, the transformation is avoid the rh-heating unit cost , the area assigned for construction it and finally the handling equipment required for the operation of the unit.In this research, the proposed of development will be considering the maximization of the benefit get from the transformation be studying the possibility of ejecting the roughing stage of the rolling mill. And exchange the regular electric energy .

with renewable energy sources

And finally transform the care of achieving production capacity capability to care of achieving product mix variety which consider on major element of the 4 Ps of marketing matrix, which include, (place, promotion, price final product). And that will be proposed submitting new vision of the CCM design which care about the capability of casting in two direction, 180^o, ATUM design.

Results

Concerning the time management (utilized time factor, UTF), The measuring of efficiency and effectiveness will be the main parameters of the value of the proposed solutions. “Efficiency and Effectiveness are not the same thing. Efficiency is defined as the ability to accomplish something with the least amount of wasted time, money, material and effort or competency in performance. Effectiveness is defined as the degree to which something is successful in producing a desired result, success”

The Overall Equipment Effectiveness (OEE) is a proven approach for measuring the overall performance of equipment. Focused on the time management and improvement and autonomous maintenance which are the two important activities to enhance equipment performance.

As well as transform to Sustainable Manufacturing Process Effectiveness (SMPE) methodology which add the measuring of how much the process is eco-friendly. In addition, implementation of the lean production and clean process to enhance process eco-performance. The OPE of the process are sufficient high for sustained capacity planning, furthermore, social cost as a framework is proposed for implementing the (SMPE) methodology to enhance overall process performance.

Concerning the material management (Yield %), the traditional technology and depending on semi product dimension, in our case billet length, the material yield % could be start from 91% and by applying the endless technology could be reach up to 88%.

Concerning the environment management the development care of two factor, 1^st one is avoid the emissions of fuel combustion , for example , in case of re-heating furnace , the one ton need for 28 cubic meter of natural gas in optimum operation condition , could be reach of 40 cubic meter of natural gas , 2^nd point is as per the best available technology update the process can be feed totally (melting, casting and rolling ) by renewable anergy by step up substation i.e. , can achieved totally the zero emissions target.

Discussion

Nowadays the most key innovated technologies are, induction heating, induction stirring, induction melting and EMS, electromagnetic stirring. And we will focus on induction heating furnace which consider the key technology based on it the merge of CCM and HR applied,

Normally CCM unit feed with liquid steel and cast semi product could be classified to steel slab, bloom and billet depending on the cross section. And the final product temperature after reaching the fully solidification stage at 900 C^o, at this point the process face energy waste due to the storing stage which reach to atmospheric temperature.

Normally the hot rolling manufacturing composed of re-heating unit, rolling stands units (roughing, intermediate and finishing) stands and finally cooling facility. And based on that the endless casting and rolling eject the traditional re-heating unit and replace it with induction heating unit. The traditional reheating unit was capable to be feed cold billet (cold charge) or hot billet (hot charge).

And as per traditional hot rolling basics and carbon percentage the steel billet, for example, need to be reheating up to 1100 C^o from atmospheric temperature to let the process able to complete the hot rolling stage.

In Endless technology, the induction heating raise the temperature just from 900 C^o up to 1100 C^o. therefore we can feed the steel square cross section billet directly to the 1^st stage of rolling stands, which is the roughing stands,

and in the research proposal the feeding billet will be as a round cross section to the intermediate stands directly.

And as per the initial calculation the process productivity could reach the 10 ton per hour, one strand of CCM, which can be duplicated up to 30 ton per hour, two strands of CCM, in two direction 180^odirections

Finally for getting clean product to minimize the billet defects the technology of electromagnetic stirring, EMS, could be applied for (Mold, Strand, and Finish) (M-EMS, S-EMS and F-EMS).

Last technology could be considered is the direct rolling and bundle, (DRB) technology, which transform the cooling bed from traditional to improved technology by ejecting of cold shear equipment and limited the cooling bed length in 24 meters only.

Conclusion

Technologies required for implement the targeted sustainability condition is available and could be considered as best available technology, BAT, including (induction heating, electromagnetic stirring and direct rolling and bundling) and also the proposed new design of the CCM will let endless concept comping of the performance effectiveness and operation efficiency.

And focusing on the present work concluded that, the increased casting productivity, especially with the introduction of high-speed billet casting (HSBC), re-emphasized the importance of high performing mold electromagnetic stirring (M-EMS) in attaining the targets productivity and product quality. To provide operating flexibility and enhance metallurgical performance adapting M-EMS design to requirements of casting practice with either the open stream pouring, and submerged entry nozzle (SEN) has become critical. in that context it is especially important to assess the effects of EMS design parameter that control is the key to EMS compatibility with the continuous casting. Practice and its high metallurgical performance.

Finally, the merge of continuous casting as a production unit as (make-to-stock) unit and hot rolling mill unit as manufacturing unit (make-to-order) unit will lead to the achieving a Lean production / manufacturing which is the 3^rd element of the technology matrix.

References

https://www.ispatguru.com/basics-of-continuous-casting-of-steel/

https://www.ispatguru.com/defects-in-continuous-cast-steels/

https://link.springer.com/content/pdf/10.3103%2FS0967091214120109.pdf

https://www.ispatguru.com/historical-aspects-of-the-continuous-casting-and-related-technologies- for-steel/

https://gajendrak.weebly.com/

https://link.springer.com/article/10.1007/BF03398119?noAccess=true

https://www.ispatguru.com/heat-transfer-during-continuous-casting-of-steel/

https://link.springer.com/article/10.1007/s11015-014-9818-1

https://www.sciencedirect.com/science/article/abs/pii/S0924013615001259 https://www.mdpi.com/2075-4701/11/9/1380/htm https://professor.luzerna.ifc.edu.br/charles-assuncao/wp-content/uploads/sites/33/2016/07/Improvement-in-secondary-cooling-of-continuous-casting-of-round-billets-through-analysis-of-heat-flux-distribution.pdf

https://www.researchgate.net/post/How-can-I-calculate-the-Metallurgical-length-of-a-continuous-casting-simulation-in-ANSYS-FLUENT

https://www.ispatguru.com/continuous-casting-mould/#:~:text=The%20most%20suitable%20length%20for,constant%20regardless%20of%20section%20size