Steelmakers know that one of the greatest threats to steel production quality is slag carryover from the ladle to the tundish. Traditionally, operators would physically sense the change in vibration at the handles of the ladle shroud manipulator and manually close the ladle slide gate. While this method does work, increasing demands for high-quality steel production and exceptional efficiency have required steelmakers to turn to more precise detection methods.

On the market today, there are two prominent types of ladle slag detection systems — acoustic and electromagnetic. If you’re looking to increase the efficiency of your continuous casting process, and improve the quality of the steel you’re casting, it’s helpful to understand how both of these ladle slag detections work. This article aims to define both types of ladle slag detection systems and identify the differences between the two.

How do Acoustic Ladle Slag Detection Systems Work?

Acoustic ladle slag detection systems make use of a high-accuracy acoustic sensor that is attached directly to the ladle shroud. These sensors can detect even the slightest change in the vibration of the ladle shroud manipulator, and are able to sense the start of vortex formation, which means they are successful in preventing any slag carry over from the ladle to the tundish. Easily adjusted for low, mid, and high sensitivity, acoustic systems offer custom detection levels depending on the desired steel grade.

Unlike many other ladle slag detection systems available on the market today, including electromagnetic systems, acoustic systems are easy to install and maintain. Acoustic ladle slag detection sensors feature a 5+ year lifespan and can be changed even during casting, ensuring your operations are never impacted by ladle slag carryover again.

How do Electromagnetic Ladle Slag Detection Systems Work?

Electromagnetic ladle slag detection systems make use of a pair of electromagnetic coils, which are typically installed around the ladle nozzle. An alternating current is fed into these coils, which induces eddy currents in the steel melt as it flows into the tundish. The presence of slag in the melt changes melt conductivity, causing the electromagnetic field to increase, which is measured by a secondary coil system. When electromagnetic ladle slag detection systems sense slag in the melt, they signal for automatic ladle slide gate closure.

In general, the greatest drawbacks of an electromagnetic ladle slag detection system are the significant installation efforts, as well as the fact that electromagnetic systems can only really detect slag once it has begun to flow into steel melt. While these systems do provide quick, accurate identification of the presence of slag, they are not effective preventative solutions.

Acoustic vs. Electromagnetic Ladle Slag Detection Systems: The Pros & Cons

With a clear understanding of how both systems work — how do you determine whether an electromagnetic or acoustic ladle slag detection system is right for you? Here’s a comparison of both systems on important considerations like installation, maintenance, system sensitivity, and overall investment cost.


Acoustic ladle slag detection systems are easy to install. Sensors are plug and play —  they are either welded or magnetically attached to the ladle shroud, where they are immediately functional. Because acoustic ladle slag detection systems require minimal installation, they are also available faster than electromagnetic systems, with delivery and installation in less than four weeks.

Electromagnetic ladle slag detection systems require a more in-depth installation process. Every ladle must be modified to incorporate the electromagnetic coils, work that is often tailored to fit unique components, leading to a time-consuming and costly process.


Acoustic ladle slag detection systems employ sophisticated acoustic sensors, which have an average lifespan of 5+ years. Maintenance requirements are low. Should an acoustic sensor have an issue, it is easily serviced or changed even during casting.

Electromagnetic ladle slag detection systems can be serviced, but the process is much more involved. In the event of sensor or coil failure, the ladle must be temporarily taken out of service which is usually not immediately possible for logistical reasons. In this case, the affected ladle must be used without slag detection.


Acoustic ladle slag detection systems are one of the few available options that can completely and accurately prevent any slag carryover. Because acoustic sensors are developed to detect vortex formation — which generally starts before ladle slag is poured — they can effectively prevent ladle slag carryover. For applications that do not require such stringent sensitivity, acoustic sensors can be adjusted for both low and medium sensitivity levels according to the required steel grade.

Electromagnetic ladle slag detection systems are also highly sensitive, but they cannot entirely prevent ladle slag carryover. At their highest sensitivity sensing, electromagnetic systems can detect slag droplets and automatically close the slide gate, but it’s important to remember that this still allows for some degree of ladle slag carryover.


Acoustic ladle slag detection systems are available at an attractive investment cost, especially considering the 5+ year lifespan of acoustic sensors, low installation costs, and minimal maintenance requirements. Acoustic systems are one of the most cost-effective, highly-sensitive options on the market.

Electromagnetic ladle slag detection systems require a higher investment cost than acoustic systems. Because each ladle must be equipped with a sensor/coil system, installation fees are high, which combines with complicated maintenance requirements to drive up the total investment cost.

Acoustic vs. Electromagnetic Ladle Slag Detection Systems: Which Option Is Best For My Application?

Having reviewed the features associated with each ladle slag detection system, it’s clear that acoustic systems are the best choice for more continuous casting applications, and especially for those looking for a long-term investment that can prevent ladle slag carryover completely. Requiring just one sensor per manipulator arm, virtually no maintenance costs, and a simple installation process, acoustic ladle slag detection systems can provide significant economic benefits over their electromagnetic counterparts.

If you’re interested in learning more about acoustic ladle slag detection systems, the KISS Technologies team is here to help. Learn more about the KT2000 LadleSlag System, or contact us online today to speak directly with an expert.


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