Substrate preteatment technique sand blasting exists two big problems recently:(1) sand material not being able utilized cyclically, technological cost being high, resources waste being serious;

针对基体前处理技术中的喷砂存在的两大问题：1）砂料不能循环利用，工艺成本高，资源浪费严重；

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Sediment as you know, is material like sand, gravel, fossil fragments that is transported by natural processes like wind, water flow or the movement of glaciers.

如你所知，沉积物是通过风、水流或冰川运动等自然过程输送的物质，如沙子、砾石、化石碎片等。

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Sand is an important building material.

沙子是重要的建筑材料。

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They drill down to the shale, then go sideways and inject high-pressure water, sand or other material into the rock.

VOA: special.2009.10.23

Obsidian is a kind of black glass formed when the heat of a volcano melts the silica material in sand.

VOA: special.2009.09.16

The soil should be full of loam, a mixture of sand, silt,clay and organic material.

VOA: special.2009.04.07

And in the chamber, the respiration and the metabolic properties of the surface sand material were measured and we added nutrients and measured the gases that were produced.

NPR: Revisiting the Viking Missions to Mars

The mine was shut down by the U.S. Mine Safety and Health Administration due to the unsafe buildup of sand and concrete material in the main shaft of the mine.

FORBES: Hecla's Lucky Friday Mine Rehabilitation Slightly Ahead Of Schedule, Restart In Early 2013

No production from the mine is expected this year after the federal Mine Safety and Health Administration ordered the Silver Shaft to be closed for removal of built-up sand and concrete material.

FORBES: Hecla Officials Anticipate Clean-Up Of Mine Shaft Can Begin In Few Weeks