subject: Silica Sand Crushing, Screening, Washing Machine For Silica Sand Production Line [print this page] In the silica sand production line, silica sand is crushed and screened out by silica sand crushing, screening and washing machine.
Silica Sandthe most common ingredient in glass. Whether the glass is container glass, window glass, boro-silicate glass, fiberglass or water glass (sodium silicate), silica sand makes up approximately 60-70 percent of the glass batch and therefore has a significant affect on the glass quality.
The silica sand production line includes crushing, screening, and washing process.
Sizing for glass sand is extremely critical in order to make high quality glass product. Sizing must be discussed in two different areas. One is the ability to size the ore at near 0.5 mm the other is to prevent oversize grains (+1mm) from entering the product.
Sizing to provide a sand product that is less than 0.5 mm is typically conducted with a screen or hydrosizer. The allowable material above 0.5 mm has been greatly reduced in the last 10-15 years. It was not uncommon in the 1980s for the glass producers to allow 5wt percent +0.5 mm in the specifications for glass sands, Today, they are pushing the limit to 0 percent on +0.5 mm with specification now being proposed with limits on the 0.4 mm screen.
The lower amount of coarser grains allows the glass producers to operated lower furnace temperatures and maintain high production levels. The lower furnace temperature not only saves in fuel costs, but, due to lower furnace temperatures, additional savings are realized with longer furnace life.
The other sizing aspect is the amount of oversize grains. These are generally measured as +1 mm grains and are limited to a few grains per kg. These grains generally are too large to melt in the furnace and cause defects in the glass. Like the refractory minerals discussed above, a few grains per kg results in 1000s of defects per day, and can significantly impact the glass production cost.
Screens are generally sized to produce a good either undersize or oversize product. That is, if the goal is to have a product that is 100 percent -0.5 mm, the underflow of the screen will meet this goal. However, the oversize of the screen will contain some -0.5 mm
Washing is the simplest and lowest cost method of cleaning silica sand. In some of the very pure deposits that are void of heavy minerals, high amounts of clay and silt, and no surface staining, washing is sufficient to produce acceptable grade product.
In the process, water is added to the sand and is generally pumped to a cyclone for desliming. The movement of the slurry passing through the pump and pipeline is sufficient to loosen the small amount of fines or clay that are in the ore body. Once the minor amounts of fines or clay have been released from the silica sand they can be removed via a variety of methods.
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