... is of great amount of pollutant entrapment, up to 9-10 kg/m3, about 1.2 or 1.5 ... times that quartz sand filter of 7.8-9 kg/m3;4. Great mechanical strength, less abrasion loss, and ... MgO ≤0.7% CaO ≤0.5 K2O+Na2O ≤4 Rare Elements Micro component 3. Technical Indexes of Ceramic Sand ... Compressive strength, N30-150- Water permeability,t/m2.h2-4- Gas permeability,m3/m2h.h1500-2000- Thermal resistance,≥1000- ...