This document discusses processing sand and silica sand into other materials. It begins by outlining examples of mineral processing including sand, silica sand, and heavy mineral sand. For processing sand and silica sand, it describes extracting, washing, classifying, and removing impurities from the sand through steps like screening, attrition scrubbing, hydrocyclones, and magnetic separation. The sand can then be further processed into silicon, silicon carbide, and silicone through reducing silica to ferrosilicon, purifying it through distillation of trichlorosilane, and using the Siemens process to deposit high purity silicon. Heavy mineral sands can also be separated into minerals like zircon, rut
32. Every sand deposit has small amounts heavy minerals (minerals that are more
than 2.8 times as heavy as an equal volume of water). Many heavy minerals are
resistant to physical weathering and erosion, can therefore withstand sediment
reworking.
Some heavy minerals also have variable properties that can accurately indicate
their ultimate source.
In the lab, heavy minerals are separated from light minerals in heavy liquids and
mounted on glass slides for examination.
Heavy minerals
33. The ratio of light to heavy
minerals was determined
and the heavy ones
examined more closely.
300 heavy mineral grains
were counted.
Heavy minerals included
hornblende, biotite, zircon,
epidote and opaque
minerals such as one
would expect in potting
soil from weathered
granite.
Example of diversity of heavy
mineral grains in sand
41. SiC is also known as Carborundum.
SiC is known under trade names Carborundum, Crystalon, and Carbolon,
including black and green silicon carbide both with a shape of hex crystal.
The black silicon carbide is classified into coke-made and coal-made black
silicon carbide depending on different raw materials. The material is extremely
hard and sharp, with excellent chemical properties. The hardness is between
Diamond and Fused Alumina, but the mechanism hardness is higher than
Fused Alumina. The micro hardness is in the range of 2840-3320kg/mm². Its
hardness is 13 Mohos
, scale.
Crystal Structure of
Silicon Carbide