“Supplier of felspathic silica sand to the regions quality glass manufacturers”
Uses of KSS Silica Sand
Silica Sand Products
Silica Sand Facts
Characteristics
The History of Glass
Float Glass
Products
MSDS
Quality Control
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Uses of KSS Silica Sand
Silica Sand Products
The silica sand produced by Kemerton Silica Sand is used predominately by manufacturers of glass containers, computer monitors and TV screens. Silica Sand is also used for the following;
Silica Sand Facts
Silica sand is an essential mineral commodity for the manufacture of glass, chemicals, and is used in the construction and foundry industries.
The bulk of the Western Australia’s production is exported and most of the developed resources generally occur along coastal regions of Australia, near transport infrastructures.
Characteristics
Silica, or silicon dioxide (SiO2), is one of the most common minerals, approximately 20% of the earth’s crust is made up of silicon dioxide, beach sand dunes are a good example of naturally occurring silica.
In nature, silica occurs as crystalline mineral in many and varied forms. The most common is quartz, commonly clear or white.
The History of Glass
Humans have been using glass for about 5,000 years. The earliest use of glass is thought to have been in ancient Egypt where glass items were found in the tombs of priests and royalty.
Glass vessels were originally made by covering a clay core with molten glass, then removing the core when the glass cooled. The blowpipe was invented about 100 B.C., enabling glass-makers to create larger glass containers in a shorter length of time. This became a widespread art within the Roman Empire then later throughout Europe.
Sand, Soda, and lime have been the basic ingredients for glass for centuries but variations exist. Adding potash and lead improves the quality of the glass, while introducing different minerals produce different colours. Broken glass, known as cullet, is added to the mixture of raw materials to accelerate the melting process. The ingredients are melted in special large pots heated to high temperatures by a furnace.
To blow glass, end of a hollow blowpipe is dipped through the “glory-hole” into molten glass in the furnace. The blow pipe is then rotated as the right amount gathers as a gob on the end then is withdrawn. The glass-blower then blows through the blow pipe and creates a free-blown bottle. The glass can then be attached to the pontil iron and cut from the blowpipe. The glass is shaped by using a tool and wooden handle. When the final shape is achieved, the object is placed in an annealing oven to slowly cool and harden.
In the early 1900s the automatic bottle machine meant the blowpipe method was no longer necessary. Commercial glass is now manufactured using bottle-blowing machinery.
Float Glass
Float glass or Sheet glass is the name given to high quality flat glass that is produced using a method first developed in 1959 by Sir Alastair Pilkington. Sir Alastair was an engineer who spent ten years developing this process when he saw an urgent need for a more efficient way of making high quality flat glass.
Stage 1: Melting and Refining
High quality sand, soda ash, limestone, saltcake and dolomite are mixed to make a batch which flows as a blanket onto molten tin at 1,500oC in the smelter.
2,000 tonnes of molten glass in the furnace undergo several processes simultaneously - melting, refining, and homogenising. They occur in separate zones in a complex glass flow driven by high temperatures. This continuous melting process can last for up to 50 hours and delivers glass at 1,100oC, free from inclusions and bubbles, smoothly and continuously to the float bath. The melting process is the key to glass quality and compositions can be modified to change the properties of the finished product.
Stage 2: Float Bath
The next stage in the process sees the glass from the smelter flow gently over a refractory spout and on to the mirror-like surface of molten tin, starting at 1,100oC and leaving the float bath as a solid ribbon at 600oC.
Although the principle of float glass in unchanged since the 1950s, the product has gone from a single thickness of 6.8mm to a range from sub-millimetre to 25mm, from a ribbon often marred by inclusions, bubbles and striations to almost optical perfection.
Stage 3: Coating
The application of coatings using advanced high temperature technology to the cooling ribbon of glass, make profound changes in optical properties.
On-line chemical vapour deposition (CVD) of coatings is a significant advancement in the float process. CVD can be used to lay down a variety of coatings, less than a micron thick, for example, to reflect visible and infrared wavelengths. Multiple coatings can be deposited in the few seconds available as the glass ribbon flows beneath coaters.
Stage 4: Annealing
Considerable stresses are developed in the ribbon as it cools. Too much stress and the glass may break when it goes under the cutter. To relieve these stresses the ribbon undergoes heat-treatment in a long furnace known as a lehr. Temperatures are controlled both along and across the ribbon. Technology monitors stress levels in the glass and controls the temperatures in the lehr
Stage 5: Inspection
Inspection takes place at every stage to ensure the highest quality possible. Imperfections may be detected where a bubble is not removed during refining, or a sand grain has refused to melt, or a tremor in the tin has put a ripple into the glass ribbon. Inspection technology allows more than 100 million measurements a second to be made across the ribbon of glass, locating flaws that the unaided eye would be unable to see. The data about the imperfections is used to drive the cutters around the flaws, therefore improving product quality.
Stage 6: Cutting the Glass
Cutters use diamond wheels to trim off stressed edges and cut the ribbon to size.
Computers apply required sizes into patterns of cuts designed to minimise wastage.
