Electric arc furnace pre-baked carbon bricks are built with seamless or wide joints?

The pre-baked carbon bricks used for the bottom of the electric arc furnace can be divided into two types of masonry, namely the traditional wide-seam masonry and the seamless masonry borrowed from self-baking carbon bricks. In practical applications, is it better to use seamless masonry or wide-seam masonry?

First of all, from the definition of the two masonry methods:

Seamless masonry: The definition of seamless masonry given in "HG/T 20542-2006 Technical Conditions for Masonry of electric arc furnace" refers to the use of fine seam paste as masonry material when building self-baking carbon bricks. The jack is tight so that the brick joint between the self-baking carbon bricks is less than or equal to 1mm, and the ring joint is less than 1.5mm.

Wide joint masonry: Wide joint masonry is a traditional process of pre-baked carbon bricks, which means that there are gaps of more than 50mm between pre-baked carbon bricks for ramming and cold ramming. Baked charcoal bricks are fired into one.

The seamless masonry process of pre-baked carbon bricks refers to the self-baked carbon bricks, and the pre-doubled carbon bricks are finished. Purpose.

Secondly, from the actual use effect

The seamless masonry process of pre-baked carbon bricks did not reduce the occurrence of bottom penetration accidents but increased them to a certain extent.

The main difference between the seamless masonry of pre-baked carbon bricks and self-baked carbon bricks is that self-baked carbon bricks and seam paste are fired at the same time, while the bottom of pre-baked carbon bricks is only seam paste baked.

When the self-baking carbon bricks and the fine seam paste are heated up and fired in the submerged arc furnace, they undergo a softening and sintering process at the same time, which can well fill the seam and sinter into a whole; The shrinkage coefficient is different, and it is not easy to sinter into a whole.

The wide joint masonry and seamless masonry of pre-baked carbon bricks are also not easy to sinter into a whole, but why is the performance of wide joints better than seamless ones?

There are two reasons for this. One is that there is too little seam paste in the 1mm seam body in seamless masonry, which cannot make up for the expansion of the brick seam due to the deformation of the furnace bottom, resulting in holes, and the side seam is much better. Second, because of the difference in the material between the two kinds of joint paste, the volatile content of carbon fine joint paste used in seamless masonry is as high as 42%, and the residual carbon after roasting is less, while the cold joint used in wide joint masonry is used. The bulk density of the rammed paste should reach 1.60g/cm3, and the plastic deformation during the firing process can compensate for the effect of the expansion of the brick joints.