Recommendations for the assembly of the working lining Instalación

Dolomite is a refractory mineral containing lime oxide, and therefore tends to hydrate to form calcium hydroxide, a reaction which causes the brick to decompose.

To prevent this reaction a series of measures not usually applied in other types of lining must be adopted, such as:

1. Reinforce the packaging to avoid breakages during handling and to stop the bricks from picking up any moisture that might be present in the air. It can be vacuum-packed in a process known as ALUVAC PACKAGING.

2. Store the pallets in dry conditions, indoors.

3. Keep only the number of pallets needed to complete the lining, in the installation area and open them as needed.

4. Conduct the installation as quickly as possible to prevent the lining from picking up any moisture present in the air.

5. On completion, preheat the lining immediately and make at least one heat before it exits the rotation cycle.

a) Installation of the bottom
The bottom can be installed before or after the side-walls. Installing it afterwards enables repairs to be made to the bottom impact area, well block and plug housing block during the campaign.
Before installing the bricks it is advisable to level the bottom with a dry mass such as KELVEL10 or KELFILL. The bricks are installed dry. Solid brick-to-brick contact must be maintained to ensure no open joints exist.

A pneumatic hammer should be used to ram the KELARAM in two layers around the well block and plug housing block, as well as the peripheral area between the wall and the bottom. Once the assembly has been completed, the KELVEL5 can be swept over the bottom to close any minute vertical joints between the bricks.

If there are problems of high wear by the mechanical impact of the steel stream from the furnace during tapping, this area should be reinforced, either with thicker bricks or with a reinforced Dolomite-Magnesia-Carbon grade.

b) Installation of the wall and slag lines

The Dolomite brick has a heat expansion of 2% at 1600Cª. This means that a series of precautions to minimise the heat stresses that are generated must be taken during its installation. The most important precautions include:

1. Leaving a space between the safety and working lining to compensate for the radial expansion of the lining. The width of this space will depend on the geometry of the ladle and the amount and format of material applied in the working lining, traditionally between 1 and 2 cm is left. It is applied after each course is closed and is compacted suitably. In all cases, this gap must be packed with a mass that is compatible with both linings We recommend the use of our KELFILL dolomite based material or KF0RL magnesite based material with organic binders or the pitch bonded KF0TL mix.

2. Leaving enough space between the top of the last course of bricks and the metal retaining plate at the crown of the ladle to compensate for the vertical expansion. Make sure that there is good mechanical maintenance of this retaining plate, or it will facilitate the opening of the horizontal joints and the filtration of steel through them. The gap left must be filled with a plastic material such as KELPLAST and rammed with a pneumatic hammer.

Traditionally there are two types of format used in the construction of walls and slag lines of ladles, i.e. semi-universal and wedge.

The semi-universal formats permit a fast “spiral installation” where by the courses need not be closed, it needs only one format and adapts better to deformations in the ladle or safety lining. It also minimises metal penetration as the joints between bricks are not radial. On the other hand, it has a greater tendency to collapsing and reduces ladle capacity on detaching more from the safety lining. If the bottom is installed before the walls, then a special format called a starter set is required to install the “spiral installation” thus complicating logistics and assembly.

When the bottom is installed after the sidewalls, the starter sets can be replaced by KELPLAST or KELARAM rammable-type masses formed on the safety lining. The gap left between the top course of the sidewalls and the retaining plate must be filled with a plastic material such as KELPLAST and rammed with a pneumatic hammer.

To assemble the lining using wedge formats two formats must be combined to adapt to the circumference. The number of bricks of each format per course depends on the deformation of the ladle and the height of the course, in the case of conical ladle. The gap remaining between the first and last brick installed in each course must be filled, finding a combination of smaller bricks known as “closures” and taking the row towards the inside or outside of the ladle to make the last adjustment.

Once the row has been closed the space between the safety and working lining is filled in the same way as with the semi-universal.

Dolomite-Magnesia-carbon grades are used to assemble the slag lines in the Dolomite ladles, with different percentages of MgO or Carbon. Depending on working conditions it is also common to reinforce the area of the slag line directly above the stirring unit with grades with a higher content of MgO and Carbon. The combination of grades that make up a lining must permit an even wear at the end of the campaign.

Belen Industriagunea, 1 - 20150 Aduna (Guipúzcoa) - Tel: +34 943.69.60.99 - Fax: +34 943.69.17.77 - Email: refractarioskelsen@calcinor.com - Kelsen 2011

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