Professor Christina Cogdell
T.A. Amelia Munson
DES040A, Section A03
1 December 2016
More than Pure Silica: the Materials of Corning Gorilla Glass
Glass is a naturally-occurring material in nature, as well as something that has become highly manufactured and mass-produced. Most types of glass found naturally in the world are distinctly different, due to the fact that the chemical composition of glass can vary and does not have to have the same composition. The composition of glass can be chemically altered by special formulation processes to produce specific benefits. Glass, ceramics, and materials manufacturer Corning Incorporated has developed their own type of glass, mainly intended for use on cellular devices, with a stronger structural composition to resist breakage and shatters. As of 2013, Corning’s glass could be found on more than 1.5 billion devices worldwide (“Gorilla Glass Success”). Since Corning Gorilla Glass is so widely-used around the world, it’s imperative to understand where and how the raw materials used for its manufacture are acquired, since they are the basis of the rest of the product’s life cycle, formulation, and recycling processes.
One of the many names for Corning’s Gorilla Glass is “fusion-drawn ion-exchanged sodium aluminosilicate glass” (Xiang et al.). The scientific name for regular or standard glass is called silicon dioxide; the word “glass” is just the common terminology. Gorilla Glass is also referred to as an alkali-aluminosilicate composition (Helmenstine). The compositions of glass vary widely. Glass (generally) is composed of silica, soda or potash, lime, and other trace minerals. On the other hand, Gorilla Glass is composed of silicon dioxide, aluminum, magnesium, and sodium. The essential ingredient of silicon appears in both regular glass and Gorilla Glass, but the special way that Gorilla Glass is treated (to become more damage resistant) is what distinguishes it from the simpler or regular versions of glass. However, the raw sand that makes up both regular glass and then Gorilla Glass is sourced in the same way.
Gorilla Glass, which is a thin sheet of alkali-aluminosilicate, contains silicon dioxide, aluminum, magnesium, and sodium (Gardiner). Aluminum is present in Gorilla Glass, and it is added later in the formulation process to help strengthen the product. Magnesium is simply a common impurity in glass. And finally, sodium plays an important role in the manufacturing of Corning’s Gorilla Glass. Later in the formulation process, after sand has been mined and turned into glass, the sodium ions in the glass will be forcibly replaced with potassium ions. This is necessary to create a new type of glass that is stronger than before, more durable, and more resilient.
Glass cannot exist without one of its key ingredients, sand. The sand used in most manufactured glass is typically sourced from sand dunes, since it tends to be of a higher purity. For sandmaking, the sand must be over 98% pure silica, or over 99.5% pure silica for most glass companies (Lewis). In addition, the sand must contain practically no impurities such as metallic oxides. Only less than 0.001% of the glass composition can be metallic oxides, and its purpose is for coloring the glass (Lewis). A higher concentration of silica leads to purer glass and higher quality products.
Different methods of mining are used to gather the sand from the environment. The most common method is surface mining, but sometimes dredging or hydraulic mining is used (Lewis). A front-end loader or crane with a clam shell is used to lift the sand from the Earth. The materials of these machines would include various metals for construction of the vehicles, as well as fuel for operating them. Next in the mining sequence involves a hopper, where sand is loaded, then rough screened for sifting out large debris. After this, conveyor belts or trucks transport the sand to large stockpiles. The mining process takes place mostly in the United States; in fact, the U.S. is the world leader in industrial sand mining, and the world’s lead exporter (“Industrial Sand and Gravel”). The top states for sand mining are Wisconsin, Texas, and Illinois, with Wisconsin being the world leader (Dolley). Most of the world’s glass products will originate from sand sourced in the U.S. The sourced sand will be delivered mostly by trucks to manufacturing plants. Since this method of transportation is (relatively) short-distance, trucks are used, but it is quite an expensive process. Because the weight of sand is so heavy, lots of fuel is required. For longer distances, rails can be used for transporting sand. For international travel, ships are used. The only other materials used in transportation are shipping or packing materials for the sand, but these do not affect the sand.
Once the high quality dune sand reaches the manufacturing plants, this is where the regular glass becomes strengthened Gorilla Glass. This is the transformation from a primary (or “raw”) material to a secondary material. Corning manufacturing plants are located in Kentucky, South Korea, Taiwan, and Japan. Once the sand is transported to the plants, the sand must undergo the special formulation process to become Gorilla Glass. This process is called fusion draw, and is one of the two main ways of melting down sand on a large scale to become glass (the other process is called float glass). Compared to the float method, “fusion-formed glass can forgo costly surface polishing and many other post-production steps,” resulting in fewer materials used and a simpler and faster production cycle (“How It Works…”). Before the process begins, since the melting point of silicon dioxide is so high at 1,600 to 1700 degrees Celsius, other chemicals are added to lower the melting temperature (“Silica…”). Corning “discovered that adding aluminum oxide to a given glass composition before the [fusion draw process] would result in remarkable strength and durability” (Gardiner). Sodium oxide is a raw material that makes the glass composition easier to work with, and also makes the product cheaper to produce (Gardiner). In fact, many chemicals could be added to the base silica composition to apply special properties to the final product. However, since the final product must maintain a very high percentage of silica, the smallest changes to the composition can potentially lead to significant alterations. For instance, adding a denser element like barium or lanthanum can also lower the melting temperature like aluminum oxide, but makes the mixture non-homogeneous (Gardiner). In addition, adding too many chemicals or making the glass too strong could risk strong fractures if breaks in the final glass product occurred. This would pose an obvious danger to the consumer. Thus, the exact composition of Gorilla Glass is not available to the public; we can assume it has been tweaked excessively in order to produce in a favorable glass product which has taken time to configure. However, the exact types of chemicals added, and the amount of those chemicals added, are not easily discoverable.
During the fusion draw process, the aluminum-oxide treated glass is strengthened by a chemical process. Specifically, the glass is submerged in a 400°C molten potassium salt bath. The glass already contains small sodium ions in its structure, but the potassium salt bath forces the sodium ions out. The replacement of sodium ions with potassium ions strengthens the glass significantly (“The Fusion Draw Process”). The glass must be kept in the ion exchange process for 4-120 hours. This is an energy-intensive process which is mainly how Corning achieves its strong, processed glass. The result is a more resilient secondary material, which they’ve entitled Gorilla Glass. Then, before packaging and shipment to distribution centers, the glass will be cut to the appropriate sizes to be assembled on products of choice. Materials for the glass cutting machinery, packaging materials, shipping boxes, etc. are required at this step.
The finished product is then shipped from the Corning manufacturing plant to national and international distribution centers, which will end up on products in the hands of consumers. Once again, trucks, trains, ships, and barges are required for transporting the Gorilla Glass. Once in the hand of the consumer in the form of a cell phone, television, or other device, not many materials are used in this stage of the life cycle. The only materials what would be involved in the use, re-use, and maintenance of the Gorilla Glass would potentially be cleaning solutions for maintaining the clarity of the glass. In addition, adhesives or joining materials would be used to connect the glass to the device they lay on, but there are so many different types of products that use Gorilla Glass. The types of materials used vary widely and are numerous in scope and scale.
Towards the end of the life cycle of Gorilla Glass lies the issue of responsible recycling. Regular glass can be broken down into what is known as “cullet,” the industry term for furnace-ready recycled glass (“Glass Recycling Facts”). Cullet can be melted down, and 100% of the glass can be re-used. However, strengthened glass such as Gorilla Glass cannot be re-cut. It can be recycled using industry-standard recycling processes, and melted down close to the original state. Less glass is lost in this way. The pieces of glass are first sorted by color and then washed. The only materials used in this life cycle stage are water and cleaning solutions for sanitizing and washing the glass, as well as the materials used in construction of the machinery used in recycling the glass. The furnace to melt the glass requires fuel as well, since the furnace must be heated to about 1,500 degrees Celsius (“Glass Making”).
Next in the life cycle is waste management, which is an unfortunate end for glass. Glass is not meant to end up at dumpsters or landfills, but it happens every day. If glass were to be retrieved from dumpsters and recycled, precautions would need to be taken to avoid cuts from broken glass, and sterilizing materials would be needed for carefully washing and sanitizing the glass. Besides this, no new materials are introduced at this stage in the life cycle. Once glass is at a dumpster, it lies there without the introduction of new substances. The only exception is if the glass was retrieved and brought to a recycling facility. This would require fuel for transportation, then cleaning solutions, materials for the machinery, and materials for the rest of the life cycle described previously, since the life cycle would begin again.
Many devices on the world feature Corning Gorilla Glass. Gorilla Glass is used for the construction of many cell phones, TVs, tablets, etc. and is such an important—yet overlooked—piece of material. More complex than standard glass for drinking cups, while so widely used in many products for work, life, and entertainment, Gorilla Glass is an important product to be aware of. Since this type of glass is so ubiquitous in countries around the world, considering the significance of the materials that comprise the formulation of such an important product is crucial information.
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Embodied Energy of Corning Gorilla Glass
Glass making first started in 2000 B.C in Mesopotamia (Corning Mu. 1). 3,500 years later, humans have improved glass making techniques as glass now numerous functions in today’s society (Corning Mu. 2). Nowadays, it is rare to live without the assistance from glass products, especially in the world of technology. One important aspect of technology is its durability and this is extremely important in cell phone production. A glass manufacturing company called Corning has developed their own signature glass screen called “Gorilla Glass” which chemically changes the composition of a regular sheet of glass into one that is much more durable. Despite Gorilla Glass being on millions of consumer phones, there is a lack of understanding of how Corning develops and improves ordinary glass into becoming Gorilla Glass. Through researching the embodied energy of the life cycle of Corning Gorilla Glass, we find that most of the product’s embodied energy comes from the first stages of raw materials acquisition and transportation. This research examines the different types of energies used to acquire the raw materials, manufacture and process the glass, and recycle the product so that users of technology with Gorilla Glass may see the energy intensive process it must go through.
Mining and transporting the raw materials consumes the most energy in the life cycle of Gorilla Glass. Glass is made up of three main materials: silica sand, limestone, and soda ash (Level 1). Corning does not reveal where they import their raw materials, but by researching where are the main producers of these materials around the world gives us an idea of where and how these raw materials are mined. The general steps for each mining starts with mine exploration, then the design of the excavation, site preparation, extraction, crushing/grinding/separation, and then finally processing (Silica 1). The process is powered by these main energy sources: coal, natural gas, gasoline, and electricity (Mining Ind. 1). SHREPA “Mine Cost Estimating Model” estimates that handling the raw materials consumes about 42% of the overall energy during mining, while the mining machinery consumes 87% of the 42%’s energy usage (Mining Ind. 2). Overall, the information found on mining shows that the extraction and transportation aspect of each raw materials consumes a large portion of energy within the lifecycle.
Corning most likely imports their silica within the United States because the United States is the world’s largest producer of silica; however, no information was found on where Corning specifically imports their silica (Top 1). Each equipment relies on crude oil as their main source of energy, showing that nonrenewable energy is the main fuel that powers the mining industry. First, excavators are used in surface mining to load the trucks with silica (Silica Sand 1). A general idea of the energy consumption of an excavator and a loader is a large sized CAT excavated used commonly at mining sites, which has about 524 horsepower compared to a loader which uses about 1,656,897 Btu/hour (approx. 651 horsepower). Then the raw silica is sent to a conveyor which uses 0.14-0.25 kilowatts (about 448-853 Btu/hour) (Mining Ind. 2). After being extracted, the raw silica is sent on rails as a means of transportation so it's ready for shipping. The lengthy process in mining silica, shows how energy intensive it is to acquire one-third of the raw materials necessary to create glass, thus making this the most energy consuming part of the life cycle.
Next limestone needs to be mined. The United States and China are the largest producers of limestone, meaning Corning is either importing from one of these two regions (ITLabs 1). Either way, it still takes large amounts of fossil fuels to transport these materials to Corning production factories. The first step in limestone extraction is the use of machinery to cut the limestone from its natural state into blocks. Another option is using mining explosives called ANFO (ammonium nitrate fuel oil) to create an open pit for extracting limestone. The approximate energy released from the ANFO is 3.90 x 106 Btu/ton (Mining Ind. 3). Bulldozers are then used to collect and transport the limestone to crushing plants where the material is crushed more finely. A standard CAT bulldozer uses about 5,115,421 Btu/hr for surface mining and is ran on crude oil (Mining Ind 4). The export of limestone is similar to the rest of the raw materials and Corning imports limestone through means of railways or boat. Both methods of transportation require even more fossil fuels, further supporting the point that raw material acquisition consumes the most energy.
ANSAC (American Natural Soda Ash Corporation) is the world leader in soda ash exports, so it’s reasonable to assume Corning receives their soda ash from ANSAC (Member 1). Their main operation facility is in Green River, Wyoming while Corning’s main headquarter and production site is in New York. This means transportation is most likely through railway or plane. If planes were used in the transportation method, it takes approximately 5 gallons of oil per mile, making the process even more reliant on nonrenewable energies (HowStuffWorks 1). Despite similar mining methods, the difference between soda ash and the other raw materials is that soda ash yields a higher energy use at 7.2 x 106 Btu/ton (Gaines 1). Overall the mining of soda ash contributes to the total energy consumption in the life cycle of Gorilla Glass and further supports the importance of fossil fuels in the process of creating the glass.
The exact energy use when acquiring the raw materials is difficult to calculate due to the lack of knowledge in the locations where Corning receives their raw materials from and what methods of mining these companies use. But, after researching on the energy use throughout its life cycle, it is by far the most energy intensive and most reliant on non-renewable energy sources, making the energy usage in the raw materials of Gorilla Glass the highest.
By examining the two main processes, we reveal what energies are required in making Gorilla Glass. Corning creates their glass in four steps: transferred, prepared, melted, and formed (Corning Man. 1). The raw materials needed to make the glass are transported by means of fossil fuel reliant vehicles to the manufacturing plant. Then the materials are prepared by first checking the quality of it and weighing it in order to ensure the glass mixture is to their preference (Corning Man. 2). An industrial mixer powered by electricity is used and after it’s completed the batch is sent over to the furnace. Cullet (recycled glass) is mixed in with the bath, but it must have a similar composition to the raw materials in order to ensure the purity of the glass. By using cullet, less energy is required during the melting process because cullet has a lower melting point than the raw materials (Gaines 2). When using natural gas to melt cullet, it requires 3.74 x 106 Btu/ton glass whereas using 100% raw materials is 5.17 x 106 Btu/ton glass (Gaines 3). Once the batch is ready, the furnace must be around 1,100-1,500℃ for the materials to melt (Corning Man. 3). This melting process requires the most energy and fuels due to the need of raising the temperature to melting point (Gaines 4). It can be assumed that Corning factories use natural gas, electricity, and coal as their main sources of energy because a typical factory runs on these types of power and Corning did not state whether they preferred a different source of energy besides those. Corning uses a method called “Fusion Process” for making their glass sheets. What makes this special compared to other glass manufacturers is that the molten glass is poured into a trough with a V-shaped bottom called an isopipe. The isopipe is then heated to about 1,100℃ while molten glass is poured into the trough and flows over the edges of the trough. This creates two sheets eventually meeting at the bottom point of the isopipe to create one sheet, which is shown in Figure 1 (How It Works 1). The sheet of glass is cooled midair and ready to be cut using Corning’s cutting machine. It’s final step into becoming Gorilla Glass is through a process called ion exchange.
Corning chemically strengthens their glass using a process called ion exchange. Ion exchange involves dunking a glass sheet into a hot potassium salt bath so that sodium ions in the glass diffuse out and potassium ions diffuse in (Gy 1). A typical ion exchange process can take 4-120 hours. Corning does not state the time they submerge their glass in the salt bath, but it is reasonable to state that their length is within that range. The bath must be 400-500℃ so maintaining that temperature for long periods of time will consume more electrical energy (Sglavo 1). At this heat, the ionic bonds of the sodium are able to be broken down and diffuse out while the heavier potassium ions diffuse in, as shown in Figure 2. Overall, the ion exchange process is reliant on electrical energy to power the furnace to melt the potassium salt bath, but due to the lengthy submersion of the glass in the bath much of the electrical energy in the life cycle is mostly consumed within this manufacturing process while the gathering of the raw materials and transportation is comprised of crude oils and natural gas. However, it is uncertain to determine the exact energy output in making Gorilla Glass due to the lack of public information on the exact processes and energies that goes into Corning manufacturing. Once the Gorilla Glass is complete and cut, Corning is ready to ship the glass to companies that use Gorilla Glass in their products and then it will be ready for consumer us.
The energy required to recycle Gorilla Glass is similar to other glass products due to its ability to be processed through the standard glass recycling program. Once the consumer is done with the product, they are able to recycle the product through their neighborhood recycling company (Gaines 5). The whole collection process consumes around 15% of the energy used for glass recycling (Gaines 6). Once the glass is taken to the recycling plant, the glass goes through a series of machines that will eventually create new recycled glass.
At the plant, the glass is sorted by material type and by color to ensure the reusability by companies (Glass 1). Then the assorted glass goes into a crusher where the glass gets crushed so the cullet mill has an easier job to turn the glass into fine cullet powder. The cullet powder is sent to the sifter to remove any foreign objects within the powder and the mixture is then preheated to about 700-920℃. The cullet powder is finally ready for companies to reuse into their own products so these recycling plants ship the cullet to companies, and in this case Corning (Waste 1). In regards to energy use, most of these machines relies on natural gases as their main source of energy, as it consumes about 60% of the total energy during recycling (Gaines 7). Energy is saved when the percent of glass recycled increases (about 13%) because less raw materials would be needed to be extracted and as stated before, the acquisition portion consumes the most energy (Gaines 8). However, Corning does not state what percent of Gorilla Glass is made of cullet, but regardless of the lack of information, it is reasonable to assume Corning uses recycled glass because it is less costly than using raw materials.
Even though using recycled glass in products seems like a way for companies to save resources, the reality is that the cullet may lack the quality, resulting in higher rejection rates of using recycled glass. So as the percent of recycled glass increases, the quality of cullet decreases, meaning that companies must spend the time and energy to determine if the glass has the quality to be reused. If the company decides not to use it, valuable time and energy is wasted (Gaines 9). There are a number of different variables for saving energy during the life cycle of Gorilla Glass, such as factory location, location of landfills, and process efficiencies, but one thing remains constant throughout the process: the use of nonrenewable energy sources (Gaines 10).
Through my research on the embodied energy during the life cycle of Corning Gorilla Glass, I’ve realized that making a simple glass screen for any typical smartphone is an energy intensive process that requires the use of lots of nonrenewable energies. Though Corning may have made attempts to use less nonrenewable energies and be more environmentally friendly, I can’t see them making drastic improvements due to the increasing consumer demand of new technologies with Gorilla Glass on them, especially in a world like today’s where our lives depend on the technology we use. The big picture coming from this research is how can Corning utilize their energy more effectively and efficiently while catering to the large demand of Gorilla Glass. Overall this research has revealed to me that a simple product like Gorilla Glass consumes more energy than we realize and if can they sustain the high production levels while relying on the power that comes from nonrenewable energy sources.
Figure 1 Source: https://www.glassonweb.com/sites/default/files/UserFiles/11(496).jpg
Figure 2 Source: http://www.neg.co.jp/glass_en/image/02/img04_b_l.jpg
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1st December 2016
Wastes and Emissions in the Production of Corning Gorilla Glass
In the modern information age, the smartphone has become a crucial device for keeping the interconnected globe only an arm's reach away. While manufacturers differentiate their devices to compete for the ever-growing market for smartphones, a common design element prevails: the large glass panel that faces the phone. Hence, Corning Incorporated developed Gorilla Glass, a chemically strengthened glass that equips devices for everyday use. While similar in composition to regular glass, the aluminosilicate glass used for Gorilla Glass contains compounds such as alumina and magnesium to increase its strength and durability. The use of such compounds drastically increases the amount of processing and waste produced in making a sheet of glass. Corning produces Gorilla Glass in the United States, Taiwan, South Korea, and Japan to fulfil worldwide demand, however this extensive global fabrication creates a colossal impact in terms of the wastes produced for manufacturing. A lifecycle assessment of wastes generated throughout the production stages of Corning Gorilla Glass highlights the adverse environmental and health impacts caused by large scale production as a result of rising global demand for smartphones.
The production of any glass begins with the extraction of primary raw materials from the earth. Silica is the main material used in making Gorilla Glass, consisting of 62.3% of the product by weight (Sglavo et al. 100). The extraction of silica produces airborne particulate wastes and waterborne wastes that pose a health hazard to workers and nearby populations. Throughout the process of mining silica, airborne particles of crystalline silica is produced. The chemical hazards of crystalline silica to human health are well understood. Inhalation of crystalline silica can cause silicosis, a condition where small particles reach deep into the lungs and cause scarring and stiffening, resulting in difficulties breathing or excessive coughing. Extended exposure to crystalline silica can cause other adverse effects, such as accelerating rheumatoid arthritis and renal disease, and increasing the risks of developing lung cancer (American Lung Association). While the use of water-fed drills and proper ventilation has reduced the risk of silicosis in developed nations such as the United States or Australia (Minnesota Dept. of Health), miners in developing nations with less stringent regulations such as Vietnam or India still face health risks due to silica mining. While it is unclear which countries Corning sources silica from, it is likely that production in the Asia-Pacific region would utilize silica sand from such developing countries.
Additionally, Silica mining and processing produces waterborne wastes and hazards that jeopardize the water quality in areas surrounding a silica mine. The processes of removing sand also removes large amounts of groundwater, which in turn lowers water levels, causing wells to run dry. The removal of material from a mine also creates paths for pollutants and impurities to reach further into groundwater. Such impurities may include petroleum products leaked from mining equipment, bacteria, or wastes illegally dumped into the ground (Minnesota Environmental Quality Board). Furthermore, the processing of silica sand also requires large amounts of water and chemicals that exacerbate the issues of removing groundwater and introducing impurities. After extraction, the silica sand is washed in water to remove large, unwanted particulate, consuming 4500-6000 gallons of water per minute (Minnesota Environmental Quality Board). While most of this water is reused, a large amount of water is still removed from groundwater to continue production. During the processing stages, flocculants, chemicals that settle silt and clay from water, are added. Chemicals such as polyacrylamide and polydiallyldimethylammonium chloride are used (Minnesota Environmental Quality Board), and may be discharged into surrounding groundwater resources. In particular, acrylamide may be a carcinogen, and poses a health risk to surrounding populations who share the same groundwater resources.
Besides silica, alumina is the most used resource in the production of Gorilla Glass, comprising 16.4% of the product by weight (Sglavo et al. 100). The refining of alumina from the ore bauxite creates a range of ecological and health risks, including acid rain, exposure to radioactive materials and pollution of surrounding water and air. Firstly, bauxite ore contains small amounts of radioactive materials such as uranium-238, thorium-232 and potassium-40 (Donoghue et al.). While the amount of radiation produced by the ore alone is generally below the threshold of radiation hazard regulations, bauxite dust containing such radioactive materials is generated from the mining process and may have long term health impacts for workers and nearby populations. Additionally, bauxite ore contains small amounts of mercury, which is released in the form of mercury vapor in the refining process (Donoghue et al.). However, most refineries use condensers to remove mercury vapor from airborne emissions, which can be reused for other production purposes.
The mining and refining of bauxite ore to produce alumina also produces a range of by-products that are hazardous to human health. The chemical treatment of bauxite ore with water and sodium hydroxide produces a toxic waste known as “red sludge”; For every ton of aluminium oxide produced, two tons of red sludge is produced (Mai). This waste contains aluminium hydroxide, iron oxide, titanium oxide, reactive silica, and other organic compounds. This waste mostly consists of aluminium hydroxide, which in the short term can cause pain and reddening of the nose, coughing, and redness of skin. Eventually aluminium hydroxide can cause neurological problems such as anxiety, forgetfulness, Alzheimer’s disease, and Parkinson’s disease (Abdullah). If nearby water sources are contaminated with this waste, the large amounts of iron oxide will lead to an accumulation of iron in the liver tissue of those who consume the water. Iron oxide can also exacerbate the symptoms of those already affected by thalassemia and haemophilia (Donoghue et al.). Overall, it can be seen that the mining and refining of bauxite ore is ecologically damaging, and poses health risks to nearby populations.
Magnesium is another raw material consumed in the production of Gorilla Glass. The production of magnesium used in Gorilla Glass commonly involves the use of sulfur hexafluoride (SF6), a potent greenhouse gas. SF6 is used as a cover gas during the refining processes of magnesium production to prevent oxidation and combustion of molten magnesium when in contact with air (Bartos and Scott). While the volume of SF6 emissions produced by the magnesium industry is low compared to other greenhouse gases, SF6 has an extremely long atmospheric lifetime of 3200 years and has a global warming potential 23,900 times greater than CO2 (Bartos and Scott). While the United States Environmental Protection Agency has been cooperating with the magnesium industry to find alternatives to SF6 and reduce emissions, magnesium sources from countries, such as China, likely to be consumed in Corning’s Asia-Pacific manufacturing is likely to still utilize SF6 and negatively impact the atmosphere through such emissions.
The extraction processes discussed above occur in mines and processing facilities across the globe, however these raw materials must first be transported to Corning factories before Gorilla Glass can be manufactured. Corning produces Gorilla Glass in four main locations: Kentucky, Taiwan, South Korea, and Japan (Corning, “Annual Report”). While it is unclear where Corning sources raw materials from, the transportation of materials by means of rail, truck, or barge from major raw material producing countries to factories incurs a great amount of greenhouse gas emissions. Within the United States, silica sand is produced mainly in Minnesota and Wisconsin. Most silica shipped outside of Minnesota is through 110-car trains, and approximately 150 trains per day carry silica (Minnesota Dept. of Transportation). In Wisconsin, on average twenty one trucks per mine per day carry silica (Minnesota Environmental Quality Board). Both trucks and trains are dominated by fossil fuel usage and thus emit hydrocarbons, carbon monoxide, and nitrous oxide into the atmosphere. Trucks in particular emit the most greenhouse gases for every ton transported one mile: 0.0063 pounds of hydrocarbons, 0.0190 pounds of carbon monoxide, and 0.1017 pounds of nitrous oxide. This is opposed to the emissions of a 110-car train emissions of 0.0046 pounds of hydrocarbons, 0.0064 pounds of carbon monoxide, and 0.0183 pounds of nitrous oxide (“Shipping Comparisons”). Although trains produce less emissions per ton-mile than trucks do, both forms of transportation emit heavily into the atmosphere to transport silica across states to Corning production facilities.
Within the Asia-Pacific region, raw materials must be transported internationally as manufacturing countries such as Taiwan and Japan lack the natural resources required to fulfill the demand for Gorilla Glass. Major silica sand producers in this area are Australia, Vietnam, Malaysia, and Indonesia, collectively transporting 55.3 million tons of silica worldwide (Lines and Echt). To supply the silica sand required for production, barges are used to transport large quantities of sand between countries. While barges have the highest efficiencies out of trucks and trains in terms of emissions, emitting 0.0009 pounds of hydrocarbons, 0.0020 pounds of carbon monoxide, and 0.0053 pounds of nitrous oxide per ton transported one mile (“Shipping Comparisons”), the farther distances between countries and larger number of production sites translates the overall higher emissions into the atmosphere.
Apart from extracting raw materials from the ground, processing and manufacturing is the most energy intensive stage of Gorilla Glass’s product lifecycle. While the fusion draw process used by Corning removes the needs for a molten tin bath, glass furnaces used to melt materials remain energy-demanding, and are mostly powered by greenhouse gas producing natural gas. To produce Gorilla Glass, raw materials are first added to a furnace and melted. In Corning’s 2015 Annual Report, it was stated that Corning utilizes a range of equipment that allows for flexibility in energy sources, and that the most energy intensive processes can be powered by natural gas, propane, oil, electricity, or a combination of multiple sources (Corning, “Annual Report”). Estimates in 2010 show that the glass industry uses 146 trillion British Thermal Units (Btu) of energy in total (U.S. EIA. “Glass Manufacturing”), contributing approximately 7.75 billion kilograms of CO2 emissions (U.S. EIA, “How Much Carbon Dioxide”), however more recently Corning has agreed to use 62.5% of the expected output of a solar power facility in North Carolina to power manufacturing, reducing the wastes and emissions that would traditionally be generated by the burning of fossil fuels (Corning, “Annual Report”). Apart from greenhouse gas emissions, glass furnaces also discharge dust, sulphur dioxide, chlorine, and fluorine into the atmosphere, potentially creating further environmental and health risks. Furthermore, the production of toughened glass such as Gorilla Glass requires additional production stages such as submerging the glass in a molten metal salt bath. Maintaining the high temperatures required for long durations of time incurs massive energy needs, resulting in a high estimated embodied energy of 27 MJ/kg of chemically strengthened glass, and a high embodied CO2 of 2450 g/kg of chemically strengthened glass (Alcorn). The actual embodied energy and embodied CO2 of Gorilla Glass may be lower than these estimates because Corning utilizes the fusion draw process rather than the more traditional float glass process, where molten glass is poured above molten tin to form a flat surface. Using the fusion draw processes removes the need for a molten tin bath and other surface polishing stages, reducing energy needs and emissions (Corning, “How It Works”). Waste is also produced in the process of trimming the glass to produce a flat pane. Approximately 18% of the glass produced is lost in the trimming process (Edge). While this waste can be shredded and used in further production, energy is still wasted in the unnecessary melting of material.
After the initial production of Gorilla Glass, it is incorporated into electronic devices and sold to end users. Throughout a consumer’s usage of Corning Gorilla Glass, no emissions or health hazards are produced due to the chemical stability of glass. However, past the usage lifecycle stage of Gorilla Glass, the glass is either discarded with the electronic device into landfills, or removed and recycled. Glass is inert, non-toxic, and non-organic (Level), therefore in a landfill Gorilla Glass does not react with other materials and release methane or additional wastes into the atmosphere and water systems. Emissions are only generated in the transportation of glass to landfills, and in the moving of waste within landfills.
Although Corning does not disclose information regarding the processes and volume of Gorilla Glass recycling, Gorilla Glass can be recycled using conventional recycling techniques, commonly involving a process of being shredded into a form known as cullet, and reintroduced into manufacturing of new glass. A useful property of glass is the ability to remelt and recycle the glass without losing quality (Gaines and Mintz). By shredding recycled glass into cullet, manufacturers can reduce the amount of raw materials needed to produce new glass, and hence reduce emissions into the environment. Cullet from either recycling or production wastes described above make up approximately 30% of material input for glass manufacturing (Gaines and Mintz). The use of cullet is advantageous because it requires less energy to melt than to melt virgin raw materials, less dust is created during the transport and processing of cullet, and less CO2 is generated from chemical reactions that take place during the melting process that would be produced with primary raw materials. As predicted by the United States Environmental Protection Agency, to produce a kilogram of glass from virgin raw material requires 7150 Btu of processing energy and 640 Btu of transport energy. In contrast, to produce a kilogram of glass from recycled materials requires 4760 Btu of processing energy and 420 Btu of transport energy (EPA, “Glass”), a reduction in energy needs of 34%. Cullet can also be used for numerous other processes, such as for manufacturing fiberglass or being used in road construction (Gaines and Mintz), providing additional end-of-life possibilities for Gorilla Glass.
Despite the various methods in which Gorilla Glass can be recycled, Gorilla Glass is only part of an electronic device, of which the volume recycled is small compared to the volume produced. While some corporations are attempting to increase recycling efforts, the overall amount of glass recycled remains small. For instance, in 2015 Samsung electronics collected 4,672 tons of displays, of which 1,430 tons of glass were reused (Samsung). Service providers such as Sprint have also been able to raise recycling rates to approximately 44%, recovering glass from phones too old or broken to be reused, with a total of 1,180 tons of electronic waste collected for recycling (Challen et al.). While the recycling efforts of such companies are reducing emissions, of the approximately 141 million electronic devices reaching the end-of-life stage annually, only 11.7 million devices or 12% were collected for recycling (Challen et al.). In all, to fully make use of the recycling potential of Gorilla Glass, a higher volume of devices must first be recycled rather than discarded into a landfill.
To conclude, the majority of waste and emissions produced in the lifecycle of Gorilla Glass occur prior to the production of the product itself. The extraction of raw materials damages ecosystems, pollutes water systems, emits potent greenhouse gasses, and pose severe health hazards to nearby populations. The global scale of Gorilla Glass production requires long distance transport using fossil fuel burning infrastructures, which further contribute potent greenhouse gasses into the atmosphere. Throughout the manufacturing stage, Corning has greater power to control wastes and emissions, such as through adopting new manufacturing technologies and using renewable sources of power. However glass manufacturing remains a high energy industry that continues to burn fossil fuels and release dust and other hazardous gases into the atmosphere. Finally, at the end of it’s lifecycle, Gorilla Glass has the potential to be recycled to manufacture new products, however low rates of electronic device recycling as a whole results in small quantities of glass recycled. As there is a global trend for rising demand of electronic devices, products such as Gorilla Glass become will become a larger contributor for the ever growing electronic waste problem, and as consumer demand grows, so will industrial demands for raw materials that are environmentally and medically costly.
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