Breaking Into Steel

Minimizing tap-to-tap times is key to producing the greatest amount of steel possible in a given timeframe. The less time spent resetting the casthouse, the more steel an operation can produce.

This is especially important when refractory needs to be replaced in furnaces, transfer ladles and torpedo cars, because it requires removing process components and blowing out furnaces. The replacement process is time consuming, so mill service contractors need equipment that is fast, accurate and, above all, safe to operate.

Brokk machines are the next generation of equipment that mill service companies use to remove worn refractory bricks from the blown-out furnaces and pulled torpedo cars and ladles. Contractors have generally relied on machines with Soviet-era designs and large excavators that are difficult to maneuver, and they have used undersized breakers to clean out refractory linings. Until now, that is.

Brokk’s remote-controlled units are the next generation of refractory-busting machinery in both integrated mills and mini-mills because of their compact size, high power-to-weight ratios and, of course, safety.

Mill service workers can access hot ladles and torpedo cars sooner with the Brokk machines than the older equipment because of advanced heat protection. For example, Brokk’s largest unit, the B800, boasts a heat shield that protects the hydraulic systems on its 31-1/2-foot-long, three-part arm from high heat and cuts down on wait times for vessels to cool off.

Brokk breaker attachments are also key to quickly removing refractory from blast furnaces, ladles and torpedo cars at integrated steel mills. For example, the Brokk 800’s hydraulic breaker impacts the bricks 12 times each second to quickly break off metal slag and refractory bricks. And the 800’s nearly 12-1/2-ton mass holds the breaker attachment securely to concentrate the right amount of pressure into the worn refractory.

In addition to breaking out refractory, Brokk machines also simplify blast furnace maintenance. Tuyeres are a hassle to remove from their bustle pipes and often require several workers to remove them and install new ones. This can lead to strained backs and other injuries. Instead, with a Brokk 260, a single operator can grab and remove the tuyeres with a specially designed attachment. This takes the weight off of service crews, speeds up maintenance and minimizes the potential for workers’ compensation claims.

To remove refractory bricks from inside electric arc furnaces (EAF), crews normally put an excavator on a platform above the deactivated furnace to reach in, break them apart and pull them out. This creates a hazy atmosphere of slag and refractory dust. Instead, crews can lower a Brokk machine onto the furnace floor to break out the refractory while the operator stands outside the furnace at a safe vantage point.

To clear the eccentric bottom tapping (EBT) inside an EAF, service crews traditionally lowered a mini-excavator and operator into the powered-off furnace to manipulate the hammer and long chisel point, while another worker outside guided the operator. Now, mill service companies can simply lower in a Brokk machine and the operator, while standing from a viewpoint above the furnace, guides the breaker attachment’s long moil point precisely and quickly to the EBT. This can add as much as 50 hours per year of steel production for the mini-mill.

The Brokk machine’s precision also prevents damage to expensive furnaces and other vessels. With a remote-control box, the operator guides the machine’s hammer and moil point easily through narrow furnace and vessel openings to remove refractory bricks without damaging the machine or the vessel.

Once the castable refractory is replaced and tapholes are cleared, steel production resumes. Using the Brokk machine safely and efficiently reduces long tap-to-tap times that are caused by refractory maintenance. This results in high production rates and minimized labor costs while promoting a safe work environment.