Agglomerated bulk solid materials often require a binder to achieve acceptable strength. Soluble silicates, including sodium silicate, potassium silicate, and lithium silicate, have been used as binders for many years in many bulk solid agglomerates. In fact, a 1949 paper in our company library lists 28 ores or fuels and 10 patents that used sodium silicate (SiO2/Na2O) as the binding agent. These “classic” silicate-based binder formulations either use a sodium silicate with a high ratio of silicon dioxide (SiO2) to sodium oxide (Na2O) or exploit sodium silicate’s setting reaction when combined with a common calcium salt or cementitious material. Iron ore, silica, detergents, and roofing granules are a few examples of materials that have used silicate-based binders and coatings for decades.
Recent developments in soluble silicate-based binders
Soluble silicate binders have been used effectively for decades in various agglomeration applications. Recent developments have improved their utility and provided more formulation options that broaden the range of materials that can be agglomerated with these binders.