Downtime costs money and its minimization is at the forefront of every plant maintenance manager's mind. Similarly, greater regard for the safety of maintenance operatives means that the traditional method of kiln lining removal-a group of workers with pneumatic or hydraulic hammers-is rapidly being replaced by automated techniques.

Swedish company Holmhead Systems AB has produced an operational guide outlining how the Brokk, remote-controlled workhorse can be most effectively used to replace a kiln lining.

Figure 1 >From a safety viewpoint, and to verify the brick condition, it is advisable to first break loose the crust that has formed on the lining. Remove the crust from, say, 11 to 1 o'clock, starting at the opening of the kiln and finishing at a point where the operator is safe.

Figure 2 Remove three or four rings of bricks directly ahead of where the break-out zone is due to end. The longitudinal tension of the bricks shouldthen ease off, but be aware of any metallic sound as you work. Subtle control, parallel arm movement, and variable hammer impact and frequency will allow the brick to be broken away without damage to the shell.

Figure 3 Break out the remaining brick lining from 9 to 3 o'clock, or 10 to 2 o'clock, gradually reversing the workhorse out of the kiln. If the kiln is between 5 to 6 meters diam, it is sufficient to only break out the brickwork from 2 to 3 o'clock.

Figure 4 Rotate the entire kiln half a turn. The remaining refractory lining of the break-out zone should then collapse. Estimated stripping time for each 20 meters of kiln lining is around 5 hours.

Figure 5 If there is a manhole within the kiln structure, the remote-controlled workhorse can be used for the mucking out.

Figure 6 Using a skid-steer loader, preferably with a bucket shaped to the inner radius of the kiln, will accelerate the removal process further allowing the new lining to be installed in a shorter time and the kiln to be back in operation quickly.

This type of machine has rapidly made a mark in the cement industry, and its compact design means it can enter kilns with diameters as small as 2 meters. Controlled via cable or radio from a remote station, the operator can select the safest overlook point while not being exposed to falling rubble.