... Dry magnesite ramming mix is used between the fins. The hearth is also lined with this material.
There is another design which uses conductive refractories, either brick or monolithic, which are a combination of C and magnesite, for carrying the electrical current from the bath to the copper electrical connections at the bottom of the furnace. Conductive refractories consist of a complicated blend of high purity magnesite, graphite, and metal powders for achieving the needed combination of high temperature refractoriness and electrical conductivity for holding the liquid steel as well as to conduct the electrical current.
The important points to consider during installation of the refractories in the DC EAFs are the zoning pattern, hearth contour, slag line location, furnace steel capacity, taphole location, taphole size and angle, roof/delta orientation, expansion allowances, burner port location, slag door construction, bottom stirring elements, and DC furnace bottom electrode.
Procedure for installing new lining in EAF
Typical procedure for the installation of a complete new lining of the EAF is described below.
The furnace is brought to the level position and the shell is cleaned from all debris prior to starting the lining of the furnace. It helps to locate the exact centre of the furnace and to punch a mark in the bottom centre of the shell. The preferred construction is rectangular magnesite brick laid flat using a basic granular material as fill to provide a flat surface against the rounded steel shell. After locating the EBT taphole seating blocks, any bottom stirring elements and allowing for the furnace bottom electrode in case of DC EAF, the first course of sub-hearth brick is laid dry, tight and level, and a dry magnesite mortar is swept into the brick joints. Additional fill material is placed around the perimeter of this first course and leveled out. The second course is laid at a 45 degree angle to the first course and again the dry magnesite mortar is swept into the joints. This process is repeated for three or four flat courses. (There is an alternate, less preferable, safety lining design which lays two to four flat courses which follow the curved contour of the steel shell. This can be used in EAFs where the shell has a small spherical radius and gives more uniform thickness in the monolithic hearth material). At the proper elevation, key shaped brick are used to begin the first stadium course. It is preferable to start with the largest ring 25 mm from the shell and work towards the centre. To close the ring, a key brick is cut on a brick saw to the exact dimensions required to close the ring. If the cut shape is less than a half brick, two cut shapes are to be used. The void at the end of the course up to the shell is filled with granular magnesite material. The next stadium ring is installed in similar fashion. The contour of the stadium ......(To be followed).#UHP #graphiteelectrode # الک illa _ _ _ _ _ _ _ _ #uhp #graphiteelectrode #الکترود گرافیت #Grafitelektrot #Графитовыйэлектрод www.shitucarbon.com www.linkedin.com/company/77167535#www.linkedin.com/groups/14123387/