Robot Technology Makes Electric Arc Furnace Steelmaking Safer

Robot Technology Makes Electric Arc Furnace Steelmaking Safer

In the wave of transformation and upgrading in the steel industry, the integration of digital and intelligent technologies has injected new vitality into traditional electric arc furnace (EAF) steelmaking. With the use of advanced sensors, big data analytics, and artificial intelligence, EAF steelmaking has achieved precise monitoring, real-time optimization, and intelligent decision-making throughout the production process. This has not only significantly reduced energy consumption and improved production efficiency, but also enhanced product quality and stability. World Metal Report has launched a special feature titled "Digital and Intelligent Technologies Ignite New Engines for Electric Arc Furnace Steelmaking," which delves into the technological secrets and innovative practices behind the digital and intelligent transformation of EAF steelmaking, showcasing a new green development vision for the steel industry.

This article introduces a new approach using intelligent robots for steel sample collection, slag removal, and inspection to improve operational safety and efficiency in steel plants. Given the harsh environment of the electric arc furnace (EAF), the application of new robot technology has reduced personnel exposure risks, improved accuracy, and boosted productivity. High-speed, precision industrial robots with multi-tool capabilities ensure flexibility in both new and existing factories. These customized robotic solutions support digital transformation, align with Industry 4.0 principles, and shift operational roles from manual labor to supervision, thereby enhancing long-term competitiveness.

1. Introduction

Steel plants are upgrading their production technology with innovative and intelligent solutions aimed at enabling seamless collaboration across all aspects of the production chain, including machinery, tools, operators, and intelligent services. These services primarily include infrastructure that supports system integration across the manufacturing chain, as well as intelligent energy management to improve energy efficiency. This transformation is expected to have a positive impact on worker health and safety, one of the steel industry's primary objectives, while also improving production efficiency. 

Key goals include: 

1) protecting worker health and safety in both the short term (accident prevention) and long term; 

2) improving work environment and safety conditions; 

3) fostering a work culture that supports health and safety; 

4) reducing smelting cycles and improving overall efficiency.

One of the operation steps that has lacked the latest technological advancements is the sampling of molten steel and temperature measurement in the smelting and refining furnaces. This process occurs in the harshest environment in the industry, making it historically difficult to integrate industrial robots due to their incompatibility with such conditions. This article demonstrates how custom system designs and the latest robot technologies have broken this taboo, bringing the benefits that industrial robots have provided in other sectors to this challenging field.

Compared to traditional mechanical arms, the use of six-axis industrial robots increases the necessary flexibility, allowing a single robot arm to perform multiple tasks. These robots can be equipped with a tool-changing system that provides multiple spray guns for temperature measurement, sample collection, and refractory material inspections. OEM solutions for this equipment help develop and engineer systems that can be adapted to various plant layouts, from large EAFs to narrow spaces in secondary refining units (such as LFs or VODs).

Even the lower section of the eccentric bottom tapping (EBT) area can benefit from the integration of robotic systems, such as automating the cleaning of the EBT, using oxygen spray guns to open it when obstructed, and collecting steel samples directly from the steel ladle after casting.

All operations performed by the robots are controlled remotely from a control room, significantly enhancing operator safety.

2. EAF Sampling Robot

The first stage of the steelmaking process is the initial melting of scrap steel in the electric arc furnace. 

This process is divided into four main stages: 

1) charging and melting, 

2) refining, 

3) tapping, 

4) post-tapping inspection.

During the refining stage, the temperature of the molten steel must be accurately measured, and steel samples need to be collected for laboratory analysis to adjust the chemical composition before tapping. The traditional method involves inserting a thermocouple sensor (for temperature measurement) and a sample collection capsule into the molten steel for a few seconds. The operation of the measurement equipment can be done manually (which is the least safe method), or using basic mechanical arms (safer, but less efficient from a production standpoint) to move the equipment to a fixed position inside the furnace.

On the other hand, using a six-axis industrial robot allows for flexible integration into any electric arc furnace configuration. This process fully leverages the robot's high speed and precision, adding the possibility of additional features such as automatic loading and disposal of ignition rods (usually manually operated on traditional mechanical arms) and multi-tool management to enhance the process.

3. EAF Inspection Camera

The monitoring of the electric arc furnace can be carried out with a specialized tool developed and patented in collaboration with Ternon. The tool is equipped with a series of cameras capable of providing a 360° view of the furnace shell and refractory materials. This operation is critical for detecting potential damage and preventing catastrophic accidents.

The tool is operated by the same robot and consists of an extension arm with a camera, equipped with five cameras in total: four for side views and one for the furnace top and electrodes (Figure 1). Both components are equipped with dedicated water and air cooling systems, enabling them to stay in the furnace for the necessary time to complete a full scan.

After tapping, the robot can automatically prepare the camera system to minimize waiting time. Before or after the tapping (depending on the furnace angle), the camera system is brought into the furnace and provides a complete record in less than 30 seconds.

Furnace operators can monitor the five cameras in real time on a dedicated monitor and take any necessary actions promptly. The recorded data is stored and can be accessed at any time for further inspection of each view.

The flexibility of the robot arm allows it to work seamlessly with the camera arm for inspecting other parts of the furnace.

Future developments include video processing, automatic detection of specific defects and leaks in the refractory materials, and estimation of steel levels using images from the camera system. The latter can also be measured using specialized sensors mounted on the same camera, which can accurately measure the distance between the camera and the molten metal. By knowing the precise location of the camera tool and the high precision of the robot encoder, it becomes easy to accurately calculate the actual steel level relative to the furnace shell.

4. EBT Service Robot

Tapping operations can be assisted by a specific robot installed beside the EBT. The PolyEBT (or PolySPOUT for smelting furnaces) robot features a multifunctional tool system, equipped with multiple oxygen spray guns and an optional sample collection spray gun. The oxygen spray guns are used to open the EBT in the case of blockages or to clean it after multiple taps. The sample collection spray gun is used to collect samples from the steel ladle after tapping, improving the overall processing efficiency.

These oxygen spray guns can be equipped with a proprietary ignition rod, which allows for reliable and controlled ignition during the metal preheating process without requiring any external flames or oxygen flows. The ignition rod consists of a metal shell filled with a high-heat coal mixture, which ignites when exposed to an induction coil (taking approximately 5–10 seconds). Once ignited, the rod allows the spray gun to be ignited later in the process 

.

The ignition steps include: 

1) preparing the oxygen spray gun with the ignition rod attached; 

2) automatically pre-heating the ignition rod using induction heating; 

3) positioning the spray gun at the tapping point; 

4) igniting the gun with oxygen flow.

This system allows for precise, safe, and controllable positioning of the spray gun using the robot arm before introducing the oxygen flow, in contrast to traditional methods that require ignition rods filled with specific powder mixtures, which increase complexity, reduce reliability, and pose safety risks.

The typical operational time frame of an EBT opening robot when no tapping occurs and there is no steel flow. All preparation steps are automated and can be completed in the background without interrupting furnace operations. The total downtime can be reduced to less than 40 seconds.

5. Conclusion

Digital transformation is positioning steelmaking as a driver for enhancing operator safety and optimizing the value chain. By minimizing the time operators are exposed to harsh environments and reducing their proximity to molten steel, we see a shift in human roles—from manual tasks to supervisory roles that require higher skill levels.

Process innovation is essential to maintain competitiveness in a complex global market, as only efficient, resilient, and quality-certified production methods can address the challenges posed by unpredictability.