... grain filters are made of refined pottery clays added with certain modifiers, and processed of grinding, mixing, ... , its filtering velocity is 15-20m3/h, with small head loss,it lowers filtering tank’s height and ... area and pore volume; strong decontamination capacity, generally with 9~10kg/m3, it is as 1.2 ~ ... times as quartz sand filtering.4.High strength,small abrasion,usage life is over 15 years.5. ...