Brief or casual exposure to low levels of crystallinesilica dust are said to not produce clinically significant lung disease.
短暂或偶然暴露水平较低的结晶矽尘表示，不会产生临床显着的肺部疾病。
2
The silica bricks of high refractoriness, high loading and heavy melting point made of large crystalline quartz have already increased the life to 5 times.
用大结晶脉石英制成高耐火度、高荷重软化点硅砖，使用寿命提高5倍以上。
3
The mineral crystalline morphology of foundry natural silica sands has been investigated, which can be divided into two groups:single crystal and polycrystalline gather.