Leila Adatto

DES 40A Professor Cogdell

December 2nd, 2021

 Raw Materials of Glazed Ceramic Tiles

Glazed ceramic tiles are a versatile and popular material commonly used in interior and exterior design for homes, restaurants, buildings, and more. Common applications of glazed ceramic tiles include kitchen backsplashes, shower/bathroom walls, and kitchen and bathroom floors. The largest producers of tile are Europe, Latin America, and the Far East (“Ceramic Tile”). Glazed ceramic tiles are made of clay, which is “an abundant, naturally occurring, fine-grained material composed predominantly of hydrous aluminum silicates” (“Clays”). There are six categories of clay, but floor and wall tiles are made of ball clays (“Clays”). Clays are mined from open-pit mines that are located near the processing plants (“Clays”). Once the clay tiles have been formed, they are finished with a layer of glaze and installed using waterproof tile adhesive and grout. This paper will cover the materials and production section of the life cycle of glazed ceramic tiles, including raw materials for clay, glaze, grout, and adhesive. This includes processes such as open-pit mining, manufacturing, and installation. 

Clay and glaze used for glazed ceramic tiles are secondary raw materials. This means the raw materials extracted from the earth have been processed into a new substance to be used as a basic material in another production process. Clay is the main material used in ceramics (Ceramic Research Company). Clay mainly consists of hydrous aluminum silicate, and it possesses a plastic quality, which is what allows it to be easily worked and molded into different shapes and forms (Gingras and Sneed). The category of clay used in ceramic tiles is known as ball clay. Ball clay is clay that has “been moved from their place of formation by the actions of water” (Gingras and Sneed). According to the US EPA,  “ball clay is a plastic, white-firing clay that is composed primarily of kaolinite and is used mainly for bonding in ceramic ware.” Other materials used in ceramics include feldspar (a flux agent), silica (mostly in the form of quartz), and talc (Ceramic Research Company). Next, glaze is a substance “composed of any materials that will melt and fuse permanently onto the surface of clay” (Burleson). Glaze is applied to the surface of clay to achieve certain effects such as “color, texture, opacity, and glossiness” (Burleson). Silica is the fundamental material found in glaze and is used to facilitate the fusion (Burleson). Flux agents are also added to glaze to lower the melting temperature of silica, such as “sodium, lead, feldspar, magnesium, lithium, and others (Burleson). In addition, alumina is added to glaze as a stabilizing agent to increase the viscosity of the glaze, as well as opacity and durability (Burleson). There are also other materials included in glaze, but silica, alumina, and a flux agent are the main ingredients. 

The main method used for acquisition and extraction of the raw materials found in clay and glaze is open-pit mining. Open-pit mining is a “surface mining technique that extracts minerals from an open pit in the ground” and this “technique is used when mineral or ore deposits are found relatively close to the surface of the earth” (“Mining Explained”). Open-pit mining involves several steps: ripping and dozing, drilling, blasting, loading, and hauling (Altiti et al.). The machinery involved in open-pit mining includes bulldozers, wheel dozers, motor graders, hydraulic shovels, and haul trucks (Altiti et al.). The mines have a negative impact on the environment, including air, water, and soil pollution as well as habitat destruction, but steps are taken to try to reclaim the land once the excavation is completed (Altiti et al.). The waste dump sites are contoured and flattened to stabilize them, and if the ore contains sulfides, it gets “covered with a layer of clay to prevent access of rain and oxygen from the air” to prevent it from transforming into acid and causing acid mine drainage (Lumen Learning). Then, the mine site is usually covered with soil and vegetation and fenced off to prevent livestock access (Lumen Learning). In the US, clay mines are located in Pennsylvania, Ohio, and West Virginia (US EPA). Once the clay has been mined, it is transported via truck to the processing plants. Most of the processing plants are located near the mines (US EPA) to minimize the production costs. From there, the manufacturing of the ceramic tiles begins. 

The manufacturing process for glazed ceramic tiles contains several steps. First, the minerals being used for the ceramic tiles need to be refined, beneficiated, and pulverized into smaller particles (“Ceramic Tile”). Once the minerals have been processed, the next step is batching. Batching involves the proportioning of the raw materials into correct amounts, usually by mass, and then mixed together, to form the body composition of the clay (Ceramic Research Company). Then, the following step is grinding, which aims to grind the ingredients into a finer particle size, and the ingredients are “added together into a shell mixer, ribbon mixer, or intensive mixer” (“Ceramic Tile”). Following the grinding is spray drying, which is a “process that converts the body slip obtained from the mill to a granulate with a size distribution and moisture content suitable for pressing” (Ceramic Research Company). This step involves atomising the mixture, which allows the water to evaporate using a flow of heated air (Ceramic Research Company). At this point, once the spray drying is completed and the powder is ready, it is time to actually form the tiles. 

After the processing of the ceramic mixture is complete, the tiles are ready to be formed, glazed, and fired. The next stage in the manufacturing process is the forming/pressing stage, during which the ceramic is shaped into the tile form. Pressing is when the powder material gets compacted and shaped in a rigid die or flexible mold (Ceramic Research Company). There are different methods to form the tile, but the most common one is using a hydraulic press, because they offer consistent high pressure that is easily controlled (Ceramic Research Company). The next step, drying, takes place over several days, and it “removes the water at a slow enough rate to prevent shrinkage cracks” (“Ceramic Tile”). This stage is important because it increases the strength of the unfired tiles, and it helps reduce the risk of losing any tiles due to cracks or other deformations (Ceramic Research Company). This helps prepare the tiles for the firing process. After the tiles are finished drying, the glazing process begins. The process for preparing the glaze is very similar to the ceramic preparation process (“Ceramic Tile”). Once the glaze has been prepared, there are several different methods for applying the glaze to the tiles. The glaze can be thrown/flung onto the tile by a rotating disc, a stream of glaze can fall onto the tiles as the tiles move on a conveyor belt in a waterfall method, or the glaze can just be sprayed onto the tile (“Ceramic Tile”). These are just a few out of several methods of applying the glaze. Finally, the last stage in the manufacturing process is the firing. The firing is what transforms the ceramic tile into a strong, sturdy, and durable product. During the firing, the tiles are heated in a kiln (a special type of oven) at a firing temperature of around 2,372 degrees Fahrenheit for 2-3 days (“Ceramic Tile”). At this point, the manufacturing process of the ceramic tile is complete and the tiles are ready to be packaged, shipped, and installed. 

Once the tiles have been manufactured, they are transported, distributed, and installed. 

According to a life cycle assessment on ceramic tiles, 50% of ceramic tile production is exported, and transport distances from the processing plant to the location where it is being installed are up to 40 km (Ibáñez-Forés et al). After the tiles have been transported and they are at the location where they will be installed, there is a process for the installation. First, the space, whether it is a wall or a floor, needs to be prepped before installing the tile. For example, a water-resistant backer board needs to be installed first on any surface where the tiles are likely to get wet, such as a shower wall or bathroom floor (Provey and Vila). Next, the installer will need to measure the space and cut the tiles to fit the dimensions using a tile cutter machine (Provey and Vila). Once the space and the tiles are prepped, it is time to adhere the tile with a waterproof tile adhesive (Provey and Vila). The waterproof tile adhesive is what helps stick the ceramic tiles to the surface and ensure that it will be long-lasting and not fall off. According to the patent for waterproof tile adhesive, there are several materials in the mixture, but the main ones (by weight) are cement, grading aggregate, and mineral filling permeable material (Patent CN103613347A). After the tiles are adhered to the surface, the installer needs to add grout in the spaces between each of the tiles. Grout is a material that “is used as a filler for the joints between tiles once the tile you are installing has been set” (Tile Outlets of America). The materials that compose grout consist of “a powdered mix of cement, lime, color pigment and sometimes sand that hardens when mixed with water and left to cure” (Tile Outlets of America). The grout is important for several reasons. It gives the tile a more clean and finished appearance, prevents dirt and debris from getting in between the tiles, and ensures that the tile installation is strong and firm (Tile Outlets of America). Once the grouting is completed, the last step is to clean and seal the tiles (Provey and Vila). In this stage, it is important to clean off the grout residue on the tiles before it has a chance to dry, because after it dries, it will be nearly impossible to remove (Provey and Vila). After cleaning the tiles, it is important to seal the grout because this prevents absorption of moisture, as well as the growth of mold or mildew on the tiles (Grout Magnificent). Sealing will help increase the longevity of the tiles and reduce the need for upkeep or even replacement of the tiles. After the installation has been completed, the tiles are ready to be enjoyed by the consumer. 

There are so many steps and processes that go into making one single product that one would not even think of. This includes the moments the raw materials are extracted from the earth all the way until the finished product is in the hands of the consumers. For glazed ceramic tiles, the process begins with extracting the raw materials for clay, glaze, grout, and waterproof tile adhesive, mainly through open-pit mining. Next, the clay and glaze go through several steps in the manufacturing process in order for the ceramic tiles to be formed and glazed. Finally, there are several steps in the installation process of the ceramic tiles, which include the grout and waterproof tile adhesive. There are wide scale environmental issues throughout every step of the lifecycle of glazed ceramic tiles, including fossil fuel use for energy consumption that emit greenhouse gases, as well as water, soil, and air pollution and other waste byproducts. As a result, consumers need to be more mindful when purchasing and using even the smallest product in order to reduce their impact on the environment and the planet. 

Bibliography

Burleson, Mark. The Ceramic Glaze Handbook: Materials, Techniques, Formulas. United States, Lark Books, 2003.

Ceramic Research Company. “ Roles and Functions of Ceramic Raw Materials in the Ceramic Tile Body.” Ceramic Research Company, 2012, http://www.ceramic-research.com/articles_02.html.

“Ceramic Tile.” How Products Are Made, How Products Are Made, 2021, http://www.madehow.com/Volume-1/Ceramic-Tile.html.

“Clays.” Minerals Education Coalition, 17 June 2019, https://mineralseducationcoalition.org/minerals-database/clays/. 

Environmental Protection Agency, US EPA. AP-42 Chapter 11 Clay Processing, pp. 11.25–1-11.25–2. https://www3.epa.gov/ttn/chief/ap42/ch11/final/c11s25.pdf 

Gingras, Jeff, and Debby Sneed. “Clay.” Department of Classics, CU Boulder, 14 June 2018, www.colorado.edu/classics/2018/06/14/clay. 

​​Ibáñez-Forés, V., Bovea, MD. & Simó, A. Life cycle assessment of ceramic tiles. Environmental and statistical analysis. Int J Life Cycle Assess 16, 916 (2011). https://doi.org/10.1007/s11367-011-0322-6

“Open-Pit Mining Definition.” Anglo American, 10 Dec. 2021, www.angloamerican.com/futuresmart/stories/our-industry/mining-explained/mining-terms-explained-a-to-z/open-pit-mining-definition. 

Provey, Joe, and Bob Vila. “How to: Install Ceramic Tile.” Bob Vila, 18 Oct. 2020, https://www.bobvila.com/articles/2327-how-to-install-ceramic-tile/. 

“Reading: Open-Pit Mining.” Lumen, Lumen, https://courses.lumenlearning.com/geology/chapter/reading-open-pit-mining/. 

TOA's Blog Team. “Why You Need Grout When You Install Tile and Stone.” Tile Outlets of America, 21 Oct. 2021, www.tileoutlets.com/blog/why-you-need-grout-when-you-install-tile-and-stone/. 

“What Happens If You Don't Seal Grout.” Grout Magnificent, 1 Mar. 2021, groutmagnificent.com/what-happens-if-you-dont-seal-grout/. 

辉宝琨 卢文书. Waterproof Ceramic Tile Adhesive Material. 18 Nov. 2015. 

https://patents.google.com/patent/CN103613347A/en

Madison Fung

DES40A 

Professor Cogdell

3 December 2021

The Endless Waste of Ceramic Tile

Used both to line the back walls of kitchens and bathrooms as well as pave the floors of both public and domestic spaces alike, ceramic tiles are believed to date all the way back to 1000 BC fired by the Egyptians. Ceramic tile is also known as subway tile, often made from clay that is crushed, fired, and glazes. As building construction and innovation continues to progress, so must the processing of ceramic tiles as more walls and floors need to be constructed and covered. This paper entails the waste created by the production of ceramic tiles. It will discuss the byproducts of the processes that manufacture ceramic tiles, such as manufacturing and deconstruction from the production of clay that emits high volumes of particulate matter to the gas emissions created from the firing the glazing process. The process of creating ceramic tiles which is constantly being improved upon for efficiency and quality of product will continue to harm the environment’s atmosphere by continuing to release harmful gaseous and solid toxins throughout production.

Especially during raw material acquisition and manufacturing, ceramic tile production creates a large amount of waste that directly affects the state of the air that cannot be filtered because there is gaseous toxic as well as particulate matter. Ceramic tile uses the main raw material of clay, which is extracted through open-pit mining (“AP-42 Chapter 11 Clay Processing” 1). The process of the mining tills the soil and disrupts the soil nutrient life cycle throughout the surrounding area. It also decreases biodiversity of the surrounding ecosystem by uprooting plant specimens and ridding animals of their homes (Scurtis). Additionally, the loosened earth can spill into potential water sources, polluting and rendering them unusable (Addae 121). Areas affected by open-pit mining cannot be restored despite attempted efforts (Scurtis). Open-pit mining is the preferred method of clay extraction due to its use of machinery that expedites the process. In an industry that needs a constant influx of materials to continue producing and improving upon its product, switching back to man-powered extraction would seem undesirable and impractical. Most basic mechanical processes (crushing, grinding) undergo material losses as the coarse grit is removed to smoothen out the material. This particulate matter is less than 10 micrometers (“AP-42 Chapter 11 Clay Processing” 2). Acidic compounds are also found to be byproducts of the combustion processes that take place during manufacturing (Celades 2). Wet processes such as washing and sizing can also cause material loss of up to 40%. Emissions from dryers and calciners compose of products of combustion such as nitrogen and sulfur oxides, as well as volatile organic compounds (“AP-42 Chapter 11 Clay Processing” 2). Every single process of ceramic tile development emits some kind of particulate or gas, from the open-pit mining and extruding to obtain raw clay to the drying process that releases atmospheric particulates that pollute the air. Each process would need to be treated in order to reduce emissions while keeping up with innovations that speed up the manufacturing process and create new or more emissions. China was reported to account for maximal proportions of global emissions of carbon dioxide from fuel use and power generation for ceramic tile production alone (Peng 467). The fact that China’s maximal carbon dioxide emissions originated from a single stage of ceramic tile production emphasizes how much of a carbon footprint the industry has. It brings to light that each stage of manufacturing needs to go under drastic changes in order to make a dent in creating a cleaner process. It is not just one stage that is at fault. Although the majority, the firing process only emits 57% of the total calculated carbon emissions of the process, the other 43% made up of other processes such as spray drying and polishing (Peng 474). 

Attempts being made to mitigate the waste emissions from production are not enough. The continual consumerism and need for improvement creates more waste emissions that cannot be constantly maintained when the product is constantly being improved upon. The process has always been to make the best possible product as soon as possible and then create solutions to minimize emissions afterwards when there is already a problem (DeFalco). The reduction of lead compounds was due to the creation of low-lead or no-lead glazes (“Ceramic Tile”). Low-lead glazes still produce toxic lead compounds. No-lead glazes are often dry glazes that produce particulate matter because they are made up of ceramic frits and crushed glass (Tozzi). Ceramic frits themselves already produce high amounts of nitrous oxides (Scurtis).  Spray-on glazes also produce fluorine emissions. Fluorine emissions have been mitigated with devices that spray water to remove harmful pollutants from gas emissions and fabric filters coated with lime (“Ceramic Tile”). Such attempts to lessen the toxicity of emissions are trying to lessen the problem rather than eliminate the root altogether. The more environmentally sound solution would be to find another type of glaze, but the constant progression in the market requires fast paced processes like spray-on glazes in order to maximize production output (Tozzi). Putting resources into finding alternatives is unlikely because of the likelihood that alternatives will not be as efficient. Cyclones and wet scrubbers that are said to be used to reduce particulate matter emissions are mostly used for product recovery and are not considered to be an air pollution control device (“AP-42 Chapter 11 Clay Processing” 12). However, the approximated percentages for how much these filters actually reduce waste are too broad and too little. These processes are constantly being improved upon for the sake of speed and efficiency and not minimizing emissions. Such remedial actions take effect after the new processes are installed and even newer ones are being developed.Studies suggest reducing carbon emissions in the drying process of ceramic manufacturing by using microwave technology to dry ceramic (Peng 474). There have been developments that encourage reusing hot air and thermal energy controlling the flow rate in dryers (Ferrer 3). However, the fast-paced industry would not allow for such laborious efforts and research because the goals of the market are more oriented towards speed and efficiency over environmental matters (DeFalco). The amount of labor that it would take to contain used hot air and reuse it effectively would not be seen as a productive use of resources. Additionally, other suggestions have mentioned exporting blank and glazed tiles that have not undergone the polishing process in order to reduce waste emissions from polishing, which include carbon dioxide and other harmful aerobic toxins (Peng 474). Such proposals also contradict the current goals of the ceramic industry. Although avoiding the polishing process altogether would save time, the reduction of quality that the public is already used to would be undesirable. The modern world that is constantly innovating would not want to regress progress made on manufacturing allegedly perfected products. It would be considered a poor business practice to produce a product that is below normal standards in order to reduce a small percentage of harmful emissions, so it is not likely that manufactures would ever agree with the notion unless the entire market was willing to do so, which is also unlikely. At the end of its life cycle, wasted pieces of ceramic tile that have been cut are often used to make a harder cement. Using ceramic wastes to create cement only prolongs the process and still circles back around to the problem because of wastes created when producing cement (Ay 497). Waste tile can be added into cement up to 35% ratio because they increase the strength of the cement, but it is not composed of the emissions from the manufacturing process but rather the clay and quartz that comprise them that have already created waste (Ay 498). Emissions can be produced in making the cement and installing it, and more energy must be put into breaking down cement upon removal because of the increased hardness, which results in increased emissions. The industry is more focused on inventing new types of tiles or new processes that can expedite their creation (DeFalco). With every new process that is created to speed up production, reports of new or increased byproducts are reported that add onto the carbon footprint the industry produces (Celades). By treating environmental practices and emission reduction as an afterthought, they will continue to exacerbate the atmosphere with pollution, only thinking of ways to make minimal improvements after the efficiency of their practice is satisfactory.

The particulate matter and gaseous emissions created from producing ceramic tiles is so great that it would be extremely difficult to mitigate it at this point in time, especially since this age of innovation is constantly striving to make a product faster which means producing more waste. This can be said about any kind of production of any kind of product that is constantly being improved upon because the priority of manufacturers is not being environmentally ethical but rather producing as quickly as possible to make a maximal profit, which defines our age of consumerism. 

Works Cited

Addae, Alexander, and Kofi Assante-Kyei.  “The Economic and Environmental Impacts on Clay Harvesting at Abonko in the Mfantsiman West

District of Central Region, Ghana.” American Scientific Research Journal for Engineering, Technology and Science, vol. 18, 2017, pp.

130-132.

Ay, Nuran, and Mevlut Unal. “The use of waste ceramic tile in cement production.” Cement and Concrete Research, vol. 30, 2000, pp. 497-499. 

Celades, Irina, et. al. “Acid emissions monitoring needs in ceramic tile industry: challenges derived from new policy trends.” E3S Web

Conferences, vol. 22,2017. 

“Ceramic Tile.” How Products are Made, http://www.madehow.com/Volume-1/Ceramic-Tile.html. Accessed 22 October 2021. 

DeFalco, Ryane. “Tile industry paves the path for 2021.” Floor Covering Weekly. https://www.floorcoveringweekly.com/main/technology-

innovation/tile-industry-paves-the-path-for-2021-32568. Accessed 30 November 2021. 

Environmental Protection Agency, US EPA. AP-42 Chapter 11 Clay Processing, pp. 11.25–1-11.25–2. https://www3.epa.gov/ttn/chief/ap42/ch11/final

/c11s25.pdf

Ferrer, Salvador, et. al. “Reduction of CO2-Emissions in Ceramic Tiles Manufacture by Combining Energy-saving Measures.” Ceramic Forum

International, vol. 5, 2014. 

Peng, Junxia, et. al. “CO2 Emission Calculation and Reduction Options in Ceramic Tile Manufacture - The Foshan Case.” Energy Procedia, vol. 16.

2012, pp. 467-476.

Scurtis, Kelly. “Chaper 10: Raw Materials.” Field Guide for Ceramic Artisans. http://ceramicsfieldguide.org/chapter-10/raw-materials/. Accessed 30

November 2021. 

Tozzi, Nilo. “Glaze Types, Formulation, and Application in the Tile Industry.” Digital Fire. https://digitalfire.com/article

/glaze+types%2C+formulation+and+application+in+the+tile+industry. Accessed 25 October 2021.