Des40A, Fall 2016
December 1, 2016
Cast Iron Pan Life Cycle
Regarded as a staple in American homes, cast iron pans have a reputation for being timeless. Actually, cast iron cookware dates back as far as the sixth century in China (Wagner 335). This timeless piece of design has actually lived through centuries and cultures. Lodge, a leading brand of cast iron pans, boasts on their website that they have been manufacturing since 1896 (Lodge). As they have been around us to the extent they have become a part daily life, how much do we really know about the production cast iron pans? Through the research and analysis of the cast iron pan’s life cycle, especially in the aspect of materials, we can see the modern way of creation and consumption of a product has been around for centuries.
First, the raw components must be gathered for processing. The main components of the cast iron pan are pig iron, scrap steel, and recycled cast iron pans. Essentially, these elements are melted down in a hot furnace to become one vat of molten metal that will get casted in molds. As metals, most of them are sourced from pre-existing forms or as new materials from the earth.
Though the component that is most “new”, or closest to the state when it was first manufactured, pig iron is as still easily obtained, making it a perfect base for this cookware. Pig iron is a crude form of iron with a high carbon content that comes directly from blast furnaces (IIMA). It is usually produced and consumed within the steel mills themselves through the processing of raw ore, pellets, limestone, and coke in a blast furnace (Bieda 1). However, merchant pig iron, or pig iron that is sold as supply to mostly metal-casting companies, is created as cold iron in ingot molds, which creates the oblong shape reminiscent to piglets and the reason why it is called pig iron, by merchant plants or by steel mills who produce excess (IIMA). Thus, pig iron is highly accessible and is produced in many places around the world, including Poland, South Africa, India, and Germany (Bieda 1). One of the companies that manufacture and supply pig iron is Miller and Company LLC; they claim to be the leading supplier of pig iron. Their production is based in Canada and South Africa, and their sources also come from Germany (Miller and Co LLC). The high carbon content the metal mixture used in cast iron pans is the reason for its black color and high heat retention. Thus, as an accessible material, pig iron help make up the cookware’s essential traits.
As an economical material, scrap steel is a facet of cast iron cookware that makes the cookware to be surprisingly sustainable. Known as ferrous metal recycling, discarded metal, such as steel in the form of appliances, cars, and other waste, can collected by scrap management centers to be recast. Some of scrap steel is generated as a byproduct in the steel mills themselves and is known as home or mill scrap; in this case, the scrap can quickly recycled, usually within the mill (Fenton 3). Old scrap is steel that has served a purpose and is also known as post-consumer scrap. In this case, the scrap must go through sorting, de-tinning, and de-zincing before it gets recycled (Fenton 3). Finally, there is new scrap. New scrap is scrap that is a byproduct of manufacturing plants and is a result of industrial activity (Fenton 3). It is excess that gets cut or otherwise physically altered during manufacturing, and it usually quickly gets recycled or transported to a recycling center due to storage reasons. Ironically, the world is producing too much steel, and as a result scrap steel is inexpensive and widely accessible. As the demand for scrap steel competes with new produced iron and steel, scrap is an economical answer to cast materials. Also, as much as it can be found around the globe, it can be found in recycling plants locally. In 2011, Recycling Today put out a report that says Sims Metal Management in New York was one of the largest ferrous scrap processors in the United States, processing about 8.7 million gross tons (Taylor). However, there are many recycling centers in each state. As a reliable and inexpensive material, scrap steel proves itself to be a thrifty and sustainable material for cast iron cookware.
Much like scrap steel, recycled cast iron is an oddly sustainable solution to the over-production of iron. Recycled cast iron is the cookware that may have already been cast and pulled out of production for imperfections or elsewise (Lodge). Then, they are sent to the front of production to be remelted and cast again (Fenton 3). In other words, recycled cast iron is new scrap. Because it is generated in the production line, it is the most accessible because it is already there. Not only that, it is also cheap because it is essentially free, if the cost of the original pig iron is not counted. Using the defected material as supply helps eliminate waste and maximize iron usage. As an existing form of material that is used in production, recycled cast iron is a valuable asset to cast iron cookware as an economical and sensible solution.
In the manufacturing and processing of these materials, vermiculite is introduced. The pig iron, scrap steel, and recycled cast iron, are heated to create a molten metal mixture. As the impurities rise in the heated slough, the impurities are removed in a process called slagging. Then vermiculite, a bonding agent, is added to the mix right before when the solution ready to be cast (Lodge). Vermiculite is a hydrated magnesium aluminum silicate mineral. There was not a lot of information available on the purpose of vermiculite except for its bonding properties and its ability to expand in heat. There are mines all over the world, including Brazil, Zimbabwe, South Africa, Russia, China, and the United States (The Vermiculite Association). Vermiculite seems to be an accessible resource.
Even in the most important steps of manufacturing, as in the casting of the cookware, cast iron cookware continues to use locally accessible materials. Also known as sand casting, sand molding is a casting technique where the iron is poured into a pattern made from foundry sand. As the Federal Highway Administration Research and Technology puts it, foundry sand is “clean, uniformly sized, high-quality silica sand or lake sand that is bonded to form molds for ferrous (iron and steel) and nonferrous (copper, aluminum, brass) metal castings”. In the United States, foundry sand is usually obtained in the foundry themselves, which are located in many midwestern states (Federal Highway Administration Research and Technology). After the pans are casted, the sand is shaken off. Fine steel is blasted to remove more sand. Then the pans are cleaned with water, soap, and packed. It is interesting to see that another material used in the production of cast iron cookware is a locally-sourced material.
In the distribution and transportation, cardboard and fossil fuels are introduced. In the packing stages, the cookware is shipped in a cardboard box, often along with a paper label. Lodge says that they recycle the cardboard but does not say if they use recycled cardboard. Finally, the cookware is shipped, usually in a vehicle that uses fossil fuels that are extracted from the earth.
In the use, re-use, and maintenance of cast iron cookware, only re-seasoning is necessary. Seasoning is treating the cookware with oil so that it will become non-stick through fat polymerization. Commonly, vegetable oils are used; they are readily accessible for consumers at markets. At Lodge, the pre-seasoning the comes on the pans are from soybean oil.
In the recycling and waste management of cast iron pans, no new materials are introduced. Typically, with proper storage and maintenance, a cast iron cookware can last a long time. This cookware is even passed down to ongoing generations, and people even find delight in collecting vintage or older models of cast iron cookware. In addition, at the end of its lifetime, the cookware can be recycled as scrap metal to be melted and recast to serve another function. Perhaps even, it will serve as another cast iron pan.
To conclude, throughout the research and analysis of the cast iron pan’s life cycle, especially in the aspect of materials, cast iron cookware, a technology that has been around for centuries, withstands even in modern consumption. The cast iron cookware is now industrialized and perfected for mass consumption through the use and reuse of materials. The majority of the raw materials are either an excess material or recyclable waste; these options are both inexpensive and accessible and have the potential to continually be so. The vermiculite and sand molds are also from the earth and can be locally sourced. At the end of its lifetime, it optimizes irons properties to be melted, and the cookware can be recycled and reused. Of course, cast iron pans are a staple in American homes because of its heat retention properties (caused by the high carbon content) are perfect for creating a steak sear. However, perhaps the ingenuity of the cradle-to-cradle technology is the reason the cast iron cookware has lasted centuries and is a model for sustainable products for the future.
Bieda, Bogusław. "Life Cycle Inventory Processes of the Mittal Steel Poland (MSP) S.A. in Krakow, Poland—blast Furnace Pig Iron Production—a Case Study." The International Journal of Life Cycle Assessment 17.6 (2012): 787-94. Web.
The Editors of Encyclopedia Britannica. "cast iron". Encyclopædia Britannica. Encyclopædia Britannica Online. Encyclopædia Britannica Inc., 2016. Web. 26 Oct. 2016 <https://www.britannica.com/technology/cast-iron>.
Fenton, Michael D. "IRON AND STEEL RECYCLING IN THE UNITED STATES IN 1998." (n.d.): 1-11. Web. 10 Oct. 2016. <http://infohouse.p2ric.org/ref/45/44144.pdf>.
IIMA. "Pig Iron." International Iron Metallics Association IIMA. N.p., n.d. Web. 01 Oct. 2016. <http://metallics.org.uk/pigiron/>.
Lodge. “The Offcial Lodge Foundry Tour-Extended”. YouTube. YouTube, 29 Apr. 2015. Web. 17 Nov. 2016. <https://www.youtube.com/watch?v=oj2qCi-ruoY>.
Miller and Co LLC. "Pig Iron." Miller and Company. N.p., n.d. Web. 01 Oct. 2016. <http://www.millerandco.com/products/pig-iron/>.
Office of Research, Development, and Technology "User Guidelines for Waste and Byproduct Materials in Pavement Construction." Foundry Sand - Material Description - User Guidelines for Waste and Byproduct Materials in Pavement Construction - FHWA-RD-97-148. Federal Highway Administration and Technology, 8 Mar. 2016. Web. 20 Nov. 2016.
Taylor, Brian. "20 Largest Ferrous Scrap Processors." Recycling Today. Recycling Today, 22 Apr. 2011. Web. 10 Nov. 2016.
Tracy, Erika. “How lodge cast iron Skillets are made in Tennessee — maker tour”. The Kitchn, 12 Aug. 2014. Web. 26 Oct. 2016. <thekitchn.com/how-lodge-cast-iron-skillets-are-made-in-tennessee-maker-tour-206834#>.
The Vermiculite Association. "Properties - The Vermiculite Association." The Vermiculite Association. N.p., n.d. Web. 01 Nov. 2016.
Wagner, Donald. Iron and Steel in Ancient China. Leiden 1996: Brill Publishers
DES 40a 01
9 November 2016
The Casting Iron Life Cycle: Energy
Casting iron is something that has been using for thousand years. It was originally invented for salt evaporation and used as early as the Han Dynasty in China (206 BC – 220 AD) (Archive). Cast iron skillet become one of the most of basic cooking tools for every family, allowing people to fry and stir non-stickily, and it is cheap, affordable, and long-lasting. The modern cast iron is not the same as the original one any more, either in material, energy, or the waste that is used through the whole life-cycle of cast iron skillet. The process to make cast iron has been changed. Through examining the energy used in all aspects of the lifecycle of the modern cast iron skillet, we can see the energy input generated that is associated with one of the world's most versatile cooking equipment.
Casting iron seems like very simple. Not too many raw materials to make casting iron skillet. The raw materials are pig iron, scrap iron, silicon, limestone, and carbon. Different proportion of those raw materials that were put into the process would change the construction of cast iron as well. There is barely pure iron exist in nature form in the world, iron mostly exist as iron ores, which is also known as iron oxides. Iron ores is the combination of iron and other trace metal elements. In order to get pig iron, iron ores need to be burned in blast furnace, and blast furnace will also be used in the process to make cast iron. Pig iron contents more carbon than other kinds of irons. Pig iron has a very high carbon content, typically 3.5–4.5% (Camp and Francis). In the Blast furnace, pig iron is produced by melting iron ores. During this process, blast furnace is fueled by coke, coal or charcoal, burning with oxygen to produce heat makes the chemical energy change into thermal energy. The heat removes the oxygen out of iron ores and leave pig iron and scrap iron behind. Silicon is a chemical element, which also does not exist in nature form. Silicon usually extracts from sand, quartz, or ground flint. Similarly, silica is converted to pure silicon by heating it with coke in a furnace. It is again a process of chemical energy converted into thermal energy. Limestone is calcium carbonate from marine fauna skeletons, and it is added into the furnace and used as a fluxing material that forms a slag on top of the liquid metal.
After getting the raw materials ready, it gets into the process of manufacturing cast iron. Cast iron is basically made by re-melting pig iron in blast furnace. There is a special type of blast furnace which is called cupola. Cupolas are usually fitted with cooling jackets to keep the sides cool and with oxygen injection in order to make the coke fire burn hotter. The hotter the furnace is, the more thermal energy that can be used to make cast iron. Chemical energy converted into thermal energy one more time at this point. Melting pig iron always along with scrap iron and steel. Total theoratical energy required to melt the scrap and to superheat it to the typical tap temperatures requires around 350 – 370 kWh/t-steel. This energy can be provided by the electric arc, from fossil fuel injection or oxidation of the scrap feedstock (Industries Efficiency Technology Database). Actual electricity use in EAFs are reported to range between 300 – 550 kWh/t, and in 1999 reached an average level of 425 kWh/t. Based on 2005, IEA estimated that reducing the average electricity consumption from 425 kWh to 350 kWh for every ton of steel produced in EAFs worldwide, 0.1 EJ of energy can be saved annually (IEA, 207. pp. 130-131) (Industries Efficiency Technology Database). Most of the industries, they would add more steel into the furnace to boost the level of carbon as well. Because it needs more carbon to form cast iron. When the burned charcoal or coke offers enough heat, iron is in liquid form right now. Then, the next step is to cast. Pouring the liquid iron into the mold, which will give shape to the cast iron. Pouring the liquid iron is another essential technique in the process of making cast iron. It is further broken down by the mold material, such as sand or metal, and pouring method, such as gravity, vacuum, or low pressure (Degarmo, Black, and Kohser). To make cast iron skillet pan, industrially, sand mold and gravity-pouring method will be mostly used. While pouring the iron liquid into the mold, potential energy is converting into kinetic energy because of the gravity. The mold allowed release the thermal energy and let cast iron to cool done and solidify. During this time, the thermal energy is releasing. After the cast iron is completely solidified, it is time to remove the mold. The good feature about sand mold is easy to remove, because it is one-time mold and very soft to break.
When the cast iron pans are finished manufacturing, then, they need to be delivered to the store for selling. Transportation is used even before manufacturing. The raw materials needto be transport to the industries first. There is a image that demonstrate where are the iron ores mostly come from. As shown, mostly, the iron ores are from Brazil(18%), Australia(17%), and Russia(16%). The dark spots in the image (figure 10.1) are the iron and steel-producing areas in the world, east coast of North America, Europe, China, and Japan are the main iron and steel-producing areas. It becomes clear from the table that China is the leading producer of iron and steel in the world, which accounts for about 23.9 per cent production of pig iron and 17 per cent of crude steel of the world’s production (Chand). Modern cast iron skillet is all made by automated machines inthe industries. It even more proved that animate energy has changed to inanimate energy nowadays. The transportation developed so fast. There are multi-ways to deliver goods from one place to another, train, truck, ship, and airplane. Depends on the prices, time, and the weight of the goods, the company has to choose the best way to transfer the goods to all different places for people to purchase. The image below shows the iron market distribution. Cast iron eventually goes to Ukraine(29.07%), Poland(17.28%), Czech Rep.(13.55%), China(10.91%), and Slovak(10.90%). The United States uses 28% of its total energy each year to move people and goods from one place to another (The National Academics of S.E.M). Gasoline (including fuel ethanol) consumption for transportation averaged about 9 million barrels (379 million gallons) per day. (About 6 million gallons per day of gasoline were consumed for uses other than for transportation.) (U.S. Energy Information Administration).
Almost every family has cast iron pan. Cast iron pan can retain heat and defuse evenly. Cooking with cast iron pan, it usually starts heating at the bottom of the pan, and pour a certain amount of oil into the pan to prevent the food sticks on the pan, and then put food into the pan to cook. The energy activity happens in cooking process are basically two kinds, the chemical energy is converted to thermal energy first, and then, the thermal energy transfers through the pan to the food. Some of the thermal energy will be absorbed by the cast iron pan and some of them will go directly to heat the food. At the same time, the thermal energy that was absorbed by the food, the molecules of the food will heated. The energy use of a stove top varies, smaller units will use 1000 watts while a larger heating element will go up to 3000 watts (Energy Use Calculator). Moreover, depends on different cooking habits, every family would have different energy usage for cooking.
Cast iron skillet is not a consumable product, and it can last generations. However, cast iron still needs to be recycled, because it doesn't reduce the degree too much when it is being re-used. There are recycle stations are specifically set for matters like iron and steel. For example, we can re-use cast iron by cutting it directly, or we need high temperature to remelt it and pour the liquid into another mold to reshape it. Recycling cast iron needs transportation as well. Firstly, cast iron pans get to the recycle station by human themselves. It is human power. After the recycle station gathers all the used cast iron pans, the cast iron pans will be transported back to the industries to re-produce the cast iron. For example, making other iron products or making some other products that has iron component in it. Usually, recycle stations will sent those recycled cast iron pans to the industries which are near by. It would be cheaper on the cost of gas or human power. It reduces the cost of iron products, too.
When cast iron goes to the wast step, it is a process to re-remelting it again. It seems like cast iron can be used over and over again just by re-melting it. Thermal energy is more important than other kinds ofenergy through the whole life-cycle of cast iron. In the waste process, the main energy, thermal energy, that used is to re-melting cast iron. Iron is the main material to make steels. To make steel by melting the iron and adding tin into it. Steel is the most recycled material on the planet, more than all other materials combined. Steel retains an extremely high overall recycling rate, which in 2012, stood at 88 percent (Steel Recycling Institution). Instead of making steels, there are many other reasons to recycle cast iron. It doesn't reduce the degree too much when it is being re-used. Also, the consumption of iron is huge. In order to re-use iron, we need energy to reshape it, however, by using the recycled iron to make new products saves a lot of energy than making the products by the raw materials. I didn't find cast iron examples, but for steels, Recycling steel, for example, uses 75% less energy than making steel from raw materials (Business Recycling).
Cast iron skillet seems simple and insignificance. However, there is a huge amount of energy used in cast iron making. According to the statistics, the total energy consumption in iron and steel is approximately 1,158 trillion British thermal units (Annual Energy Outlook). It is not hard to see that iron is important in our lives, and we put a lot of energy to make it. Cast iron is not like the high technique products, which will be substituted quickly. It would take a long time to find another product to replace cast iron pan.
"Annual Energy Outlook 2016." U.S. Energy Information Administration (EIA). Annual Energy Outlook, 2016. Web. 01 Dec. 2016. <http://www.eia.gov/outlooks/aeo/steel_industry.cfm>
Chand, Smriti. "Distribution of Iron and Steel Industry in Major Countries of the World (with Maps)." YourArticleLibrary.com: The Next Generation Library. N.p., 07 Feb. 2014. Web. 01 Dec. 2016. <http://www.yourarticlelibrary.com/industries/distribution-of-iron-and-steel-industry-in-major-countries-of-the-world-with-maps/25405/>
"Electric Arc Furnace." Industrial Efficiency Technology & Measures. N.p., 29 July 2013. Web. 30 Nov. 2016. <http://ietd.iipnetwork.org/content/electric-arc-furnace>
"Electricity Usage of a Stove Top - Energy Use Calculator." Electricity Usage of a Stove Top - Energy Use Calculator. N.p., n.d. Web. 30 Nov. 2016. <http://energyusecalculator.com/electricity_stovetop.htm>
"Energy Use for Transportation." Energy Use for Transportation - Energy Explained, Your Guide To Understanding Energy - Energy Information Administration. U.S Energy Information Administration, n.d. Web. 01 Dec. 2016.
"Iron Ore." Iron Ore. N.p., n.d. Web. 30 Nov. 2016. <http://www.prominvestsa.com/en/iron_ore.html>
"Iron & Steel." Business Recycling. N.p., n.d. Web. 30 Nov. 2016. <http://businessrecycling.com.au/recycle/iron-steel>
The Coming of the Ages of Steel. N.p.: n.p., n.d. Google Books. Google. Web. <https://books.google.com/books?id=uMwUAAAAIAAJ&pg=PA47#v=onepage&q&f=false>
"The National Academies Presents: What You Need to Know About Energy." How We Use Energy, Transportation —. The National Academics of S.E.M, n.d. Web. 01 Dec. 2016. <http://needtoknow.nas.edu/energy/energy-use/transportation/>
"Robot Check." Robot Check. Google, n.d. Web. 01 Dec. 2016. <https://www.amazon.com/Making-Shaping-Treating-Steel-Vol/dp/0930767020>.
Life Cycle Assessment of Cast Iron Pan Waste
Cast iron cookware has been in use for hundreds of years; some date back to the Han Dynasty in China. Even with the advent of newer cookware technology, such as the teflon coating, bare cast iron cookwares are still considered an essential part of every kitchen both in the restaurant industry and for home use due to its manufacturing simplicity, durability, excellent heat retention, non stick surface and ability to cook a multitude of different dishes. Although a modern cast iron skillet doesn’t contain as many materials as other more contemporary cookware, there are still many waste generated through it’s production, and transportation.
In order for foundries to start producing bare cast iron cookwares, such as pans and skillets, they must first import raw materials, such as pig iron, into their processing plants from other foundries or recycling plants; the process of smelting and transporting it contributes to the amount of waste generated in its lifecycle. Pig iron itself is an intermediate product of refining iron ore. “[It’s the] Product of smelting iron ore with a high-carbon fuel such as coke, usually with limestone as a flux.” Although most major cast iron cookware companies, for example Lodge, do not explicitly say what kind of pig iron they use in the casting process, the specific type used is known as haematite pig iron or foundry pig iron; “haematite pig iron are generally 92% iron, 3.5-4.5% carbon, 1.5-3.5% silicon, .5-1% manganese, <0.05% sulphur, and <.12% phosphorus."1 In addition to pig iron, companies also use recycled steel and recycled cast iron in the casting process. The production of pig iron releases the following greenhouse gases: carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride. The different conventional air pollutants released are carbon monoxide, ammonia, nitrogen oxide and sulfur dioxide. While not all of the pig iron produced is used in the casting of iron skillets, information about how many skillets companies like Lodge produces is not readily available to the public; it's safe to assume the amount of waste generated in this process is less than the amount the EIO-LCA tool states.
In the United States most foundries have switched to using a more effective process of melting metals for use in products; rather than using a traditional blast furnace, foundries use what is known as an electric arc furnace. While significantly more environmentally friendly than blast furnaces, they still generate waste. The process of melting metals for use in cast iron cookware with electric arc furnaces can be separated into the following operations: furnace charging, melting, de-slagging, tapping and furnace turn-around.4 During the furnace charging operation, the roof and electrodes are raised and moved to the side, while the metal is specially organized inside the furnace; foundries try and minimize the time it takes fill up the furnace because energy is lost every time the furnace roof is opened.4 “10-20 kWh/ton for each occurrence”4 Once it’s filled, the roof is lowered first and then the electrodes are lowered to create an arc on the scrap, which commences the melting operations. The melting process can be separated into two parts, the initial bore-in period and the long arc tap. In the initial bore-in period an intermediate voltage tap is used which melts approximately 15% of the metal. Once the electrodes have sufficiently penetrated the scrap mix so that the dangers of radiation damage to the roof subsides, then a long arc tap is applied to melt the rest of the metal. Only when enough scrap has been melted, will subsequent charging process will be performed. “Before the molten metal is poured into molds, workers add a mixture of unknown alloys to the mix to get the desired composition.” Information about said alloys was considered a trade secret and the amount varied per batch of molten metal. In addition to adding a mixture of alloys, vermiculite is also used to cause the slag to stick together and then extract it out.6 Once the the furnace has been emptied of molten metal, it is then inspected for damages; any damages spotted are repaired. This whole process mainly generates the following by-products: slag, carbon monoxide gas and electric arc furnace dust.
Many of the waste generated from the creation of the cast iron skillet is used in other products. One of the waste that's generated is electric arc furnace dust; “EAF dust is a hazardous waste that is generated during the melting of scrap with electric arc furnaces.” Found in the Journal of Materials Research and Technology, volume 3, issue 3, EAF dust can be used in the steelmaking process. In addition, there are companies like Steel Dust Recycling that takes EAF dust and uses it in the production of zinc oxide and waelz iron product. Another waste that's generated is slag; a glass like material separated from metals during the melting process. While foundries have little to no use for slag, in other industries, such as the cement industries, slag is a valuable resource. “EAF slag... is highly versatile… ideally suited for use as an aggregate in many applications.” Slag is used in road building, cement, fertilizer, construction aggregates, and building insulation.10 Another byproduct generated from the use of an electric arc furnace is carbon monoxide gas, which comes from the process of injecting carbon into the mixture to reduce ferrous oxide into iron. “CO gas is produced in large qualities… both from oxygen lancing and slag foaming.” Rather than just simply releasing the carbon monoxide into the atmosphere, it’s combusted in the EAF. “Electric energy savings are about 0.1kWh/scf(kWh/Nm^3) of oxygen injected.”11 While a lot of the by-products generated by the electric arc furnace are used as raw materials for other items, there are also other by-products that are used to increase the efficiency of the system. All of this contributes to electric arc furnace being the more green alternative.
While expending energy to turn the metal from a solid to liquid state is a major contributor to how much waste is generated in the creation of a cast iron pan, there are also other waste contributors, such as the process of forming the sand molds. Most casting operations are done with sand molds due to its advantages when compared to other materials; such advantages include, being inexpensive and resistance to high temperatures. The main ingredient used in all sand casting is sand; however, the type of sand used and the binding agent used varies between manufacturers and the object they’re casting.11 Although most foundries don’t specify what type of sand casting process they use, it’s safe to assume most use green sand casting. Green sand castings are able to hold it’s shape for most casting applications, has good collapsibility to prevent cracking, good permeability so gases can escape during the pouring process, can be recycled for future use and is the least expensive. In order to create the molds, silica sand, water, clay and other unknown chemicals are compressed into shape; the mixture of clay and other chemicals helps the sand mold keep it’s shape after it’s released. After the metal has solidified and the sand mold is broken, the by products left are sand, and iron runners. “A majority of the sand can be reused for future casting; additional sand is added to replace the amount that could not be salvaged.”13The iron runners are reused as scrap in foundries. While not all of the by products generated can be reused a majority of it can, which helps cut down on waste and increase efficiency.
The amount of waste generated by the creation of cast iron skillets isn’t limited to the factory; more waste is generated from the act of transporting raw materials to the foundries and transporting the finished product around the world, to the end users. Most of foundries don’t make the information of where they ship readily available to the public. However, in the United States, Lodge is the only manufacturer of cast iron cookware in North America, so it’s safe to assume a majority of cast iron cookware made in the United States is shipped from the same foundry. According to the Carnegie Mellon tool, EIO-LCA, the amount of greenhouse gases released through truck transportation for $1 million dollars of economic activity is approximately “16.0 metric tons of carbon dioxide.” Other air pollutants include nitrogen oxide, sulfur dioxide, volatile organic compounds and particulate matter. Since the number generated includes all cutlery, utensils, pots and pans the amount of carbon dioxide released from the transportation of the cast iron cookware is less than 16.0 metric tons.
When taken care of well, cast iron cookware can last for many years; however, if not properly cared for, the cookware will either rust or crack and subsequently be thrown away. Rather than just letting these metal continue to rust in a landfill, many municipal waste management systems recover it for recycling due to it’s benefits. “Recovery of 1 metric ton of scrap conserves an estimated 1,030 kg of iron ore, 580 kg of coal and 50 kg of limestone.” Another reason why iron is recycled is because of the amount of energy it saves. “Recycling saves the energy equivalent required to electrically power about one-fifth of the households in the United States.”16 While the user may no longer have a use for their damaged cookware, even if they were to throw it away in a trash bin, the metal would still be recovered and remelted so that it can be used in the formation of new objects.
Production of metal objects have come a long way. The concept of heating up metal to form it into a usable object hasn’t changed much. What has changed is the waste generated and the how much of those waste are reused. Byproducts like slag are sent to be used as raw materials in other items, electric furnace dust is captured to be turned into new raw material, and other by-products such as sand and carbon monoxide gas are used to increase efficiency. While there’s always room for improvement, the process of creating cast iron cookware is surprisingly “Green”.
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