When engineers in the early 1950s were looking for alternatives to the Siemens-Martin and Thomas steelmaking processes, they could not have imagined that they would initiate a revolution in steel manufacturing with the development of the Linz-Donawitz (LD) converter – also known as the Basic Oxygen Furnace (BOF). Today, around 70% of global steel production is based on this technology. More than 200 LD (BOF) plants – including numerous turnkey projects – have been planned, built, and commissioned by Primetals Technologies.
In 1952 the Linz-Donawitz (LD) process – also known as BOF process - was developed in Austria and soon became the standard for iron ore based steelmaking. Starting from its invention the process was continuously optimized and improved regarding consumption figures, productivity as well as maintenance and is nowadays used successfully in steel plants all over the world.
Significant share of the developments and improvements for the LD process have been made by Primetals Technologies and its former companies. Nowadays Primetals Technologies is one of the leading solution providers for converter steelmaking with vast experience and wide reference base for completely new plants as well as for highly specialized and customized revamping and modernization projects.
Although the LD process is already a very mature process Primetals Technologies is continuously investing in developments for further improvements of the process and the equipment. Modern numerical simulation methods, process models, logistic simulations and full 3D modelling are some of the powerful tools used for this purpose.
Most recent trends in development are more accurate process control and process optimization by numerical models, increased level of automation to reduce manual workforce in hazardous areas and equipment optimization to increase lifetime. All these small steps together with our long term experience allow Primetals Technologies to be one step ahead of competitors and offer trendsetting solutions to our customers.
Fig.1- LD (BOF) converter | Fig.2- Converter tilting drive | Fig.3- LiquiRob for probe handling
While for normal carbon steel production LD process is used in almost all integrated steel plants all over the world, special converters are used for high alloyed steels, processing of high rates of scrap and Direct-Reduced-Iron or processing of hot metal very high in Silicon content. Primetals Technologies has a wide portfolio of special converters; most important are bottom blowing converters that allow also for lime and coal injection as well as combined blowing converters. Characteristic for these converters is the bottom blowing with natural gas cooled tuyeres in the converter bottom and equipment for lime and coal injection. The bottom blowing leads to excellent mixing of the liquid bath, hence, all metallurgical reactions are close to their equilibrium. As a consequence yield of the process is higher compared to pure top blowing converter and process control is easier.
Primetals Technologies is the leading supplier for special converters and realized several references in the last years. Especially equipment and automation for the bottom blowing has been improved and optimized within the last years to fully comply with actual standards. One of the latest developments for special converters is the Jet Process. It combines a bottom blowing converter with a hot blast system. The hot blast blown from top ensures that the coal injected is fully combusted and almost all the heat is transferred to the liquid bath. As a result an overall efficiency of more than 50% is reached and a wide range of scrap rates can be processed in highly productive manner. A first reference for the Jet Process was realized recently with a customer in Asia.
Fig.1 - Charging of a special steel converter | Fig.2- Bottom injection system | Fig.3- Tapping of exchangeable LD converter
Intelligent automation for steelmaking
State-of-the-art production of high-quality steel requires standardized and reproducible processes. Primetals Technologies process automation implements these requirements, consequently leading to improved hitting rates for carbon and temperature, lower flux material consumptions, higher Fe yields and optimized production times. Dynamic production control is assured by application of Steel Expert, a comprehensive suite of metallurgical process models.
Our process models optimize and control the steelmaking process during the entire treatment in BOF converter plants, based on flexible production schemes depending on the target steel grade.
The precalculation model - Steel Expert Prediction – simulates the whole BOF process before and after scrap and hot metal are charged. It determines the optimum blowing and stirring strategy, as well as the addition of flux and tapping alloying materials. During the blowing process Steel Expert Supervision cyclically calculates the ongoing reactions in the steel bath and in the slag. If a sublance is available, the Inblow model determines corrective actions based on the measured values, in order to achieve the required carbon and steel bath temperature. If a continuous offgas measurement (e.g. Lomas) is available, the Dynacon model is applied for dynamic blow end detection. Based on the actual offgas data Dynacon calculates the carbon content of the steel bath and suggests the optimum time for blowing stop.
Further highlighted technological packages:
- Lomas – Fully automated continuous offgas measurement and analyzing
- AutoTap – Automatic, reproducible, standardized and safe steel tapping
- Advanced Tracking System – Automatic electronic tracking of metallurgical vessels at treatment stations
- Acoustic Expert – Acoustic plant monitoring and maintenance assistance
Fig.1- HMI Steel Expert Supervision | Fig.2- State-of-the-art BOF operation | Fig.3- Acoustic Expert on mobile devices
- Dry Dedusting System (DDS)
- Wet Dedusting Sytem (WDS)
- Secondary Dedusting System (SDS)
- Gas Recovery
- Cooling Stack – Highly efficient energy recovery
- GasFerm - Generation of added value for offgases
- BSSF Technology for Slag Processing
- Re-Cooling systems
Fig.1- Highly efficient gas cleaning | Fig.2- Energy recovery | Fig.3- Briquette product