In order to pursue the high efficiency and longevity of blast furnace ironmaking, the press-in slurry has been popularized and applied in the rapid repair technology of blast furnace body in my country. But at present, the most widely used is the press-in mud using organic resin and tar as binder. This kind of mud is difficult to solidify, and a large amount of harmful benzopyrene gas is generated when heated, and the material shrinks greatly and the volume stability is poor.
Therefore, in recent years, silica sol has been selected as the binder for the pressed material. It has been confirmed by experimental research that the shrinkage rate of the pressed-in mud bonded by silica sol after being treated at a high temperature of 1200℃*3h is much smaller than that of the pressed-in mud by resin bonding. Moreover, after nearly 100 times of 1100 ℃ water-cooling and thermal shock tests, the silica sol after drying at 110 ℃ and pressed into the mud sample basically did not appear cracks. At this time, the compressive strength exceeded 80 MPa, and the strength retention rate after thermal expansion exceeded 80%. This is mainly because the nano-SiO₂ in the silica sol produces a mullite reaction in the matrix pressed into the mud, which improves the thermal shock resistance of the material.
The resin-bonded indented mud sample was completely cracked after about 10 thermal shocks. This is because the matrix of this indented mud has not yet formed a ceramic bond at 1100 °C, and the resin that can produce bonding strength at low temperature is in the When heated to I100°C, it has been burned off, and gas is formed during the process of burning off, which makes the internal structure of the material loose, resulting in a decrease in the bonding strength of the material. When the material is subjected to rapid cooling and rapid heating changes, the thermal stress generated inside the material exceeds the material. Its own bonding strength, it produces cracking or peeling.
This confirms that the silica sol-bonded indents perform much better than the resin-bonded ones. Moreover, the press-in material combined with silica sol does not pollute the environment from production, construction to application, and does not harm the health of construction workers, so the press-in mud combined with silica sol is an environmentally friendly material. This kind of silica sol combined with pressed charge has been successfully used in the repair of blast furnace walls and blast furnace and hot blast stove surrounding pipes in steel mills. The practical application results show that the press-in material combined with silica sol not only has good construction performance and service performance, but also is a pollution-free environment-friendly press-in mud.
