L25Recycling145s09-1

L25Recycling145s09-1 - Lecture 25: Recycling Reading...

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Lecture 25, spring 2009 ENGR 145, Chemistry of Materials Case Western Reserve University Reading assignment : C&R §4.9, Ch. 20; these slides Learning objectives: Understand the concept of the materials cycle Recognize that production of engineering materials consumes … raw materials … energy … and produces byproducts Learn some of the motivations and the challenges for recycling of: Glass Aluminum Thermoplastics Lecture 25: Recycling 1
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Lecture 25, spring 2009 ENGR 145, Chemistry of Materials Case Western Reserve University Materials Cycle Raw materials Synthesis Engineered materials Product design Applications Waste Recycle / reuse Solid waste / landfill If biodegradable: a new natural resource Earth’s materials are a closed system , not an infinite reservoir 2
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Lecture 25, spring 2009 ENGR 145, Chemistry of Materials Case Western Reserve University Life Cycle Assessment of a Product 3
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Lecture 25, spring 2009 ENGR 145, Chemistry of Materials Case Western Reserve University Materials Cycle: Environmental Considerations Each step in the materials cycle — even recycling — In order of increasing energy consumption: Reduce amount of material used Reuse existing material Recycle existing material Combustion with energy recovery Produce new material from natural resources these options also conserve raw materials scrap recovery http://www.epa.gov/garbage/faq.htm 4
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Lecture 25, spring 2009 ENGR 145, Chemistry of Materials Case Western Reserve University Benefits Reduces energy consumption Reduces pollution from less energy use from less incineration Saves landfill space Conserves natural resources Can save money, long-term Creates jobs 5 Costs Energy Transportation Labor Time Storage Tradeoff: Maintaining materials’ performance vs. Flexibility of feedstock In-plant recycling: internal scrap from manufacturing process Post-consumer recycling: collected after product has been used
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Lecture 25, spring 2009 ENGR 145, Chemistry of Materials Case Western Reserve University U.S. Community Recycling Rates, 2006 http://www.epa.gov/garbage/faq.htm 6
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Lecture 25, spring 2009 ENGR 145, Chemistry of Materials Case Western Reserve University Glass Recycling Benefits unique to glass: Saves energy (and time ) during melting — major mfg. cost Recycled glass is already: Pre- reacted (SiO 2 + NaCO 3 + CaCO 3 window or container glass) Pre- homogenized and “fined” (i.e. rid of bubbles) Container glass: consistent in composition Glass is nonbiodegradable Sources of recycled glass (a.k.a. “cullet” ): In-plant: scrap, breakage — has been used for decades Post-consumer: collected from recycling centers Disincentives: must sort glass by color; glass is heavy and prone to breakage; raw materials are cheap 7
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L25Recycling145s09-1 - Lecture 25: Recycling Reading...

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