Converter and secondary refining: critical measurements in extreme conditions

After the Sinter plant and coking plant the hot metal is further processed in a converter.

Converter

This can be an oxygen converter, where oxygen is blown into the hot metal to initiate a chemical reaction that removes some of the carbon.

Secondary refining

An alternative method is to use an electric arc furnace (EAF): These are widely used in scrap metal recycling. This takes all kinds of steel and iron scrap - old bicycles, car parts or scrap from demolition projects - and melts it down into steel.

That is then further refined in a secondary furnace, where the appropriate alloying elements are added and care is taken to ensure that all impurities are removed in both steps.

It is a highly volatile environment, with temperatures around 1615°C in the metal. Exhaust ducts are also present.

There may also be hydraulic pumps moving certain parts, and the temperature of the furnace wall may be interesting to monitor. Hot spots may develop around the furnace. In that case, they would like an early warning, before the metal breaks through something.

Recommended IoT sensors for converter and secondary refining:

1. Infrared temperature sensors are important for control and safety in converter and secondary refining:

Chemical process control

During the converter process, oxygen is blown into the hot metal to remove carbon. This reaction is temperature sensitive: too low and the reaction proceeds incompletely, too high and unwanted byproducts are created.

Adding alloying elements also requires a stable temperature to ensure the desired material properties.

Hot spot detection and furnace integrity

The furnace wall is subject to thermal stress. Local hot spots can lead to burnout, causing severe damage and downtime. IoT temperature sensors detect these hot spots early so operators can intervene before structural damage occurs.

Energy efficiency and cost savings

By accurately monitoring the temperature, energy consumption can be optimized. Overheating is prevented, leading to lower energy costs and longer life of furnace components.

Safety and reliability

In a volatile environment with molten metal and high pressure, process safety is paramount. Temperature sensors contribute to stable and controlled production, minimizing risks to personnel and equipment.

2. Ampere/consumption sensors: insight into energy consumption and machine load
Converter plants and electric arc furnaces (EAF) are major energy consumers within steel production. Monitoring power consumption is therefore essential for both operational efficiency and cost control.

Monitoring of electric arc furnaces

Arc furnaces melt scrap using powerful electric current. Amp/consumption sensors continuously measure the furnace's amperage and load.

Deviations in consumption may indicate:

• Imbalance in the melting process
• Problems with electrodes
• Loss of efficiency due to wear or contamination

Control of motors and pumps

In addition to furnaces, motors and hydraulic pumps are also controlled by electrical systems. Consumption sensors help detect overload, wear or inefficient operation of these components.

Energy management and cost savings

Through near-real-time visibility into power consumption, operators can:

• Avoiding peaks in consumption
• Optimizing installations
• Preventing energy waste

This directly contributes to lower energy costs and sustainability goals.

Maintenance and predictive maintenance

Changes in power consumption can indicate mechanical problems. Early detection enables predictive maintenance, which prevents costly downtime.

3. Vibration sensors: for monitoring hydraulic pumps and mechanical reliability

Hydraulic pumps play a key role in the converter process, for example in moving valves, positioning furnace components or controlling extraction systems. These pumps are mechanically heavily loaded and susceptible to wear, imbalance and cavitation.

Detection of mechanical anomalies

Vibration sensors continuously measure vibration patterns in pumps and pipes.

Abnormalities in these patterns may indicate:

• Wear and tear of bearings
• Imbalance in rotating parts
• Loose components
• Cavitation (air bubbles in fluid flows that cause damage)

Preventive maintenance and failure prevention

By detecting anomalies early, small repairs can be made before they grow into major failures.

This prevents unplanned downtime of critical systems, which in a converter environment can lead to lost production and security risks.

Cost savings and uptime

Vibration sensors help reduce maintenance costs through targeted and timely maintenance.

They help increase plant uptime, which is essential in a process where every downtime can cost thousands of dollars per hour.

Smart integration into maintenance planning

By linking vibration data to maintenance systems, companies can apply predictive maintenance.

This makes it possible to schedule maintenance based on actual wear, rather than fixed intervals.

4. Pressure/vacuum sensors: essential for emission control and process safety

In converter and secondary refining, various gases are released at high temperatures, including fumes from alloying elements, dust particles and residual gases from the smelting process. These must be disposed of safely and efficiently through extraction ducts and filter systems.

Emission control and environmental regulations

Industrial steel processes are subject to strict EU emission standards.

Pressure and vacuum sensors monitor the effectiveness of suction and filtration.

They help document air flows and emissions, which is necessary for environmental compliance.

Detection of blockages and leaks

Sensors detect deviations in pressure, which may indicate:

• Clogged filters
• Leaking pipes
• Insufficient extraction

Early detection prevents pollutants from entering the workspace or overloading the system.

Energy Efficiency

Unnecessary pressure loss means fans have to work harder. By optimizing air flows, energy consumption and wear and tear on fans and pumps can be reduced.

Safety and process stability

Poor extraction can lead to accumulation of gases, posing explosion hazards or health risks.

Sensors provide a stable and safe working environment, especially in areas of high thermal and chemical stress.

Together, these four sensor types provide a critical foundation for the safe, efficient, and sustainable operation of converter and secondary refining. They provide process optimization, cost savings, and prevent downtime - all essential in an environment with high temperatures, complex chemistry, and heavy mechanical loads.