How to extend the shelf life of refractory ramming mass?
Refractory ramming mass is constructed by ramming method (by hand or by machine) hardened under heating above normal temperature, it is made of a certain grade refractory aggregate, powder, binder and additive, mixed with water or other liquid. According to the material classification t can be divided into high alumina, fireclay, magnesia, dolomite, zirconium, zirconium silicon carbon based refractory ramming mass.
The length of shelf life of refractory ramming mass has a lot to do with the choice of binder when formulating the product, what kind of binder should we use when choosing the refractory ramming mass?
According to the use, the ramming mass is prepared from refractory aggregate and powder. At the same time, suitable binder is selected according to the refractory aggregate material and the use requirements. Some ramming mass do not use a binder and only add a small amount of flux to promote sintering.
1, Acid ramming mass commonly takes sodium silicate, ethyl silicate and silica gel as binders.
2, Basic ramming mass takes an aqueous solution of magnesium chloride and sulfate, and phosphate and a polymer thereof as binders, also often uses a binder with high carbon can form a carbon-containing organic substance and a temporary binder at a high temperature.
3, Chrome based refractory ramming mass commonly takes glauber as binder.
4, High alumina and corundum based ramming mass commonly takes aluminium phosphate, chloride, sulfate and other inorganic substances as binders.
When takes phosphoric acid as the binder, during the storage process, the phosphoric acid reacts with the activated alumina in the ramming material to form a precipitate of water-insoluble aluminum orthophosphate which solidifies and hardens, and it is difficult to construct due to loss of plasticity.
Therefore, in order to extend the shelf life of the refractory ramming mass, an appropriate preservative must be added to prevent or delay the occurrence of coagulation hardening, usually using oxalic acid as a preservative. The carbonaceous ramming material mainly uses a carbon-bonding binder, and the asphalt tar or the resin is used as a binder to form a carbon bond, which can prevent the molten metal from being wet, improve corrosion resistance and thermal shock resistance, and dope in dolomite. It can also play a role in preventing hydration of dolomite.