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List the raw material in glass manufacturing.
What is the function of each ingredient?
Sand (Silica) is the glass forming oxide
List the raw material in glass manufacturing.
What is the function of each ingredient?
Sand (Silica) is the glass forming oxide
Sand is Silicon Dioxide also known as Silica. Chemical formula is SiO2. Sandy areas such as beach, desserts and other sandy areas are a good resource of silicon dioxide.
Silicon dioxide has many uses. First of all it is used as a source of pure silicon in glass production. To extract the silicon large furnaces are used to heat the silicon dioxide, removing the oxygen and leaving pure silicon behind. High melting temperature and its chemical stability make Silica a perfect ingredient for Glass manufacture.
Limestone lime provides chemical stability
A very important property of lime in glass production
is its ability to form stable solutions with silicates. When lime is
heated with silica sand (SiO2)
a solution is formed that does not crystallize when it is cooled. Instead,
it hardens to an amorphous, clear, and nearly colourless solid glass.
Due to the presence of Limestone lime in the mixture to produce glass,
it does not have a distinct melting point. It gradually softens as it
is heated. Therefore, it can be moulded and blown into many useful shapes.
The production of container glass from lime is one of the ancient uses
of lime.
Soda ash acts as the fluxing agent.
It is known that the Egyptians made glass containers by a method that involved soda ash chemically known as sodium carbonate (Na2CO3),as early as 3500 B.C.
According to the U.S. Geological Survey, approximately 30 percent
of domestic soda ash shipments are for glass production, including flat
glass and mirrors, bottles for beverages, jars for food, insulation,
televisions, lighting, glassware, and labware.
Most glass manufactured is the soda-lime-silica type. Soda ash is an
essential constituent in that it reduces the furnace temperature necessary
to melt the silica, thus reducing the energy required to produce glass.
It is generally used to supply the bulk of the alkali element because
it is the most cost effective source of Na20. Dense soda
ash is generally preferred over light ash in glass manufacture because
the particles are of a similar size to silica sand. This enables a homogeneous
mixing of raw materials and results in a high quality end product.
Recycled glass (cullet)
Glass, especially glass food and beverage containers, can be recycled over and over again. Glass recycling has grown considerably in recent years as glass manufacturers' increased demand for recycled glass.
Most glass manufacturers rely on a steady supply of recycled crushed glass, known as “cullet,” to supplement raw materials. To make glass, manufacturers mix sand, soda ash, limestone, and cullet; heat the mixture to a temperature of 2,600 to 2,800 degrees F; and mould it into the desired shape.
Function of the cullet includes:
Different colours and types of glass are collected together. This glass is then sorted by colour due to different melting points and chemical incompatibility. Although all glass is made of silica and soda, the type and quantity vary slightly with different types of glass. Glass separated by color yield glass cullet of higher economic value.
2 Briefly explain how different shaped and coloured glass bottles are manufactured?
Traditional glass-blowing and blow-moulding methods are still used by artists and for custom applications. However, most bottle production is an automated process including the following stages:.
Bottle manufacturing takes place at a glass container factory in This process employs high amounts of heat (1675 degrees Fahrenheit) to produce and shape a glass bottle. A furnace is first used to mould molten glass, which fed to the furnace as glass feed stock. Soda-lime glass stock accounts for the majority (around 90 percent) of glass products, and is typically largely comprised of silica, with about 10 percent each of calcium oxide and lime. Small amounts of aluminum oxide, ferric oxide, barium oxide, sulfur trioxide, and magnesia also account for about 5 percent of soda-lime glass. Before melting, cullet (recycled glass) is added to the stock, accounting for anywhere between 15 and 50 percent of the final glass composition.
When the molten glass reaches its plastic stage this phase begins. A shearing blade is used to cut and shape the glass into a cylindrical shape, called a gob. The cut gob falls, and using gravitational force, rolls through the appropriate passage to reach the moulds. A metal plunger presses the gob into the blank mould, where it assumes the mould’s shape and is then termed a parison. Next, the parison is moved into a final mould, where it is blown into the mould to assume its final dimensions.
In blow-and-blow formation, the gob is forced into the blank mould using compressed air to push the gob into place. The gob is then flipped into a corresponding final mould where it is blown again, to form the interior side of the glass bottle. Glass bottles of varying neck thickness can be made using blow-and-blow formation.
After formation, bottles often undergo internal treatment, a process which makes the inside of the bottle more chemically-resistant, an important factor if the bottles are intended to hold alcohol or other degrading substances.
Once formation is complete, some bottles may suffer from stress as a result of unequal cooling rates. An annealing oven can be used to reheat and cool glass containers to rectify stress and make the bottle stronger.
Colour
can distinguish a glass container, shield its contents from unwanted
ultraviolet rays or create variety within a brand category. Colour
can be obtained by simply adding small quantities of different oxides:
o Chromium (for green)
o Cobalt (for blue)
o Nickel (for violet/brown)
o Selenium metal (for red)
The raw materials used in commercial glass making contain iron oxide as an impurity, which imparts a yellow/green colour to the glass.
To offset the yellow/green when making flint (or “colourless”) glass, other colours are introduced by adding selenium (for red) and cobalt (for blue) in proper proportions to yield a gray glass that appears colourless.
3 What tests are done on glass bottles?
At final stage in glass production, the bottles are inspected and packaged. Inspection is often done by a combination of automated and mechanical inspection, to ensure the integrity of the final product. Common faults include checks (cracks in the glass) and stones (pieces of the furnace that melt off and are subsequently worked into the final container), which are important to catch because they can compromise the component.
4 How the smoothness on the surface of the glass bottle is achieved?
Surface Treating of Glass Bottles is done by flame polishing and then etching with an Aqueous Fluorine Compound Solution and Coating with Plastic
The outer surface of the bottle is treated with a 1-10% aqueous solution of ammonium fluoride, hydrogen fluoride or ammonium fluoride by immersing or spraying. After water washing, it is coated with polyurethane.
5 Briefly detail about Finished Products, markets, warehousing, OH&S and economics of glass packaging in relation to glass manufacturing at OI.
Glass is made from its raw materials listed in the beginning of the
assignment in a carefully controlled processes described above,
and is then moulded to form glass bottles as a Finished Product.
Australia's Glass and Glass Product Manufacturing industry services
two key markets: the glass container market and the flat glass market
The industry maintains a high concentration of ownership, with two-thirds
of revenue generated by the three dominant players: Owens-Illinois Australia,
Amcor and Viridian (CSR Limited). The domestic market is expected to
total $3.23 billion in 2012-13, with imports capturing about 22% ($710
million) of this and export earnings contributing $80 million of industry
revenue (3.1%). (http://www.ibisworld.com.au/
Many companies throughout Australia offer their warehousing services. O-I is a company that produces iconic glass containers. Their original design and manufacturing capabilities allowed them to become the world’s leader in glass packaging.
The most significant occupational health and safety hazards, which occur during the operational phase of glass manufacturing projects and primarily include the following:
· Exposure to heat
· Exposure to noise
· Exposure to respiratory hazards
· Physical hazards
· Electrical hazards
6 Research and write about glass container dimensions for food packaging
Glass container dimensions and shapes may vary. For instance, there are many different sizes for glass bottles and jars:
A:17X12X18CM
B:16X11X16.5CM
C:14.5X10X15CM
D:12X8X12.5CM
E:10X8X10CM
F:8X5.8X8CM
G:5.3X3.8X5.3CM
7 Research and write about various closures for glass containers in food packaging
Glass containers in food packaging may have different lids including screw lids. Material for closures can be plastic or metal. The metal lid prices are higher than for plastic lid.
8 List advantages and disadvantages in using glass as packaging material.
The use of glass as a packaging material has many advantages. The most important ones are that glass will not leach chemicals into foods when heated and it can also be recycled endlessly. Glass is used to package many things in our shops and supermarkets, including drinks, sauces, jams, spreads, oils, and spices. Glass, though, does have some disadvantages as a packaging material:
Weight
Glass is heavy compared to some packaging materials, which means more trips by road, rail, sea, or air are needed to transport items packaged in glass. This, in turn, means a greater environmental impact. Further, the extra transport costs are passed onto consumers. Not only is glass heavier to transport for the companies moving it from A to B, but it is also heavier for consumers carrying it from purchase point to home.
Fragility and Slipperiness
Glass smashes easily. Companies that use glass packaging have to take extra care at all stages of manufacturing and transportation. Further, glass is more slippery to the touch than some other packaging materials, which means it is more likely to be dropped more often than other packaging materials.
9 Discuss glass as packaging material for beer, wine, coke and fruit juices.
For the products mentioned above glass containers are the best way to package those food products. Although, glass containers are heavier than plastic ones and can easily break, they make those beverages safe for consumption as unlike plastic will not react with acids and other chemical elements in the mentioned drinks. Dark bottles will keep heat and sun away and keep the natural ingredients fresh and healthy throughout the storage period.
Bibliography:
http://www.alibaba.com/
http://gpi.org/glassresources/
http://www.bombonierebrisbane.
http://i-grafix.com/index.php/
http://www1.ifc.org/wps/wcm/
http://www.silklogistics.com.
http://www.o-i.com/About-O-I/
http://www.thomasnet.com/
http://www.epa.gov/osw/
http://www.graymont.com/
The Disadvantages of Glass Packaging | eHow.com http://www.ehow.com/list_
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