free silica

例句：

1. 1.The free silica sand is used in the production of glass.
   自由硅酸盐砂用于生产玻璃。
2. 2. Free silica sand is a natural resource that can be found in many places.
   自由硅酸盐砂是一种天然资源，可以在许多地方找到。
3. 3. The free silica sand has been used for centuries as a building material.
   自由硅酸盐砂自古以来就被用作建筑材料。