The invention discloses novel
stemming at a tap hole. The
stemming comprises the components in parts by weight as follows: 5-25 parts of
corundum, 5-25 parts of
high aluminum aggregate, 10-30 parts of
silicon nitride combined with
silicon carbide, 2-3 parts of
silicon nitride iron, 5-15 parts of
coke powder, 8-20 parts of clay, 1-5 parts of crystalline
flake graphite, 5-10 parts of
pyrophyllite, 4-7 parts of
sericite, 5-10 parts of
magnesium-aluminum spinelle, 2-4 parts of active
alumina micro
powder, 1-3 parts of
metal powder and 15-20 parts of external composite binding agent. The composite binding agent comprises
tar, modified phenolic resin and an
organic solvent. The volume ratio of
tar, modified phenolic resin to the
organic solvent in the composite binding agent is 1:3:1. According to the invention, with the adoption of the composite binding agent formed by mixing
tar and modified phenolic resin,
smoke generated is less, the same
plasticity to be combined with tar is met, the opening performance is good, the pressure resisting
thermal shock resistance is good, and the
adhesion strength is high. The depth of the tap hole can be prolonged and the furnace cylinder can be protected, the tapping time is prolonged, and the number of casts every day is reduced.