Ramming refractory mixes are composed of refractory aggregates with various fine, medium and coarse particles, which are available both in dry and wet forms. These mixes are rammed and compressed in place by using special hammers or pneumatic rammers and mostly form chemical bonds. In some classifications, plastic refractories are also categorized among ramming mixes, too, due to their ramming installation method. By using ramming refractories, a great area can be covered uniformly, which this may not happen for plastic ones.
Depending on the aggregate type, ramming refractories contain acidic and basic types and have a lower humidity in comparison to other refractory types. Among acidic ones are silica ramming mixes. The main composition of these refractories is SiO2, and the remaining compositions are other main natural compositions such as alumina (Al2O3), iron oxides (Fe3O4, Fe2O3 and FeO), magnesia (MgO), alkaline compositions and also refractories industry common binders and additives. These refractory materials are completely anticorrodal in corrosive acidic environments; but on the other hand, they’re weak against basic (alkaline) conditions and are corroded quickly and easily due to their chemical reaction with basic materials. For instance, alkaline slags are such harmful and corrosive elements to silica refractories.
Because of their less expensive raw materials, easy production and utilization, silica ramming mixes are more common in Iranian industry. When choosing and using these kinds of mixes, impurities amount (mix’s main aggregate purity), P.S.D. (particle size distribution) and L.O.I. (loss of ignition) are the factors that should be noticed. Mix color is also of high importance and should be white to milky-white. In general, silica refractory mixes are available as ramming type; but in some cases they also include mortars and plastic refractories.
Silica ramming mixes (masses) are divided into two main categories: dry and wet, which in the dry type, silica (SiO2), with various particle sizes, is mixed with boric acid (H3BO3) or boron oxide (B2O3) as a binder or sinter aid (flux). It’s mentionable that as the service temperature increases, the binder amount should be reduced (like for example using for steel or for cast iron). For melting steels, it’s preferred to use boron oxide. Wet mixes are not such common.
To use silica ramming masses, using correct ramming and then sintering principles and methods is vital and related service-providing companies should provide customers with all required information and necessary tips.
Our silica ramming mixes are presented as follow: