Environmentally Conscious Design & Manufacturing Class 18: Recycle Prof. S. M. Pandit

Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:1

Agenda

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Definition of recycling Hierarchy of recycling Design for recycling Recycling metals, plastics & forest products Economics Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:2

Definition of Recycling

American Automobile Manufacturers Association’s definition A series of activities, including collection, separation, and processing, by which products or other materials are recovered from or otherwise diverted from the solid waste stream for use in the form of raw materials in the manufacture of new products.

Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:3

Some Myths - 1

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Recycling should pay for itself

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Bias in data collected, and the inability to recognize large scale impact has led to reports of “expensive recycling” $200 of energy is saved per ton of material recycled Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:4

Some Myths - 2

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Environmental impacts of manufacturing are included in the products

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Cost = function of:

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supply & demand governmental policy problems with assigning cost Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:5

Life Cycle of a Product

Source: Bishop, “Pollution Prevention: Fundamentals and Practice” Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:6

Recycling World

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Categories:

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Portable high value (computers, auto parts)

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Metals Plastics Paper Chemicals & glass Food waste Used equipment Building material Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:7

Typical Value for Vehicles

Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:8

Hierarchy of Recycling Options

Source: Bishop, “Pollution Prevention: Fundamentals and Practice” Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:9

Steps of Recycling

For remanufacture and reuse:

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Disassembly Cleaning Sorting and inspection Part renewal Re-assembly Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:10

Steps of Recycling (cont.)

For material recycling:

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Separation Discrete subassemblies / joining techniques

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Sorting Group or classify

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Reprocessing technology Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:11

Possible Separation for Materials

Source: Bishop, “Pollution Prevention: Fundamentals and Practice” Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:12

Example: Polymer Recycling

Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:13

Design for Recycling

Multiple objectives

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Minimize variety of materials & components Avoid use of toxic materials Ease of disassembly of dissimilar materials Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:14

Disassembly

• Design for Disassembly (DFD) • Ease of Disassembly - Preferred design: snap-fit, pop-in, pop-out, bolted or screwed components - Difficult design: welded, adhesive, threaded connections Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:15

Disassembly (cont.)

• Simplified Design Reduce the number and types of parts Reduce product complexity

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Modularity Design • Material Selection Facilitate identification of materials (e.g. Marking plastics) Use fewer types of materials Use similar or compatible materials Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:16

Disassembly (cont.)

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Non-Destructive Disassembly (NDD) Minimize the destruction of the product Maximize the potential of material resource and sub-component reuse

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Destructive Disassembly (DD) Destroy one or more components so that the others can be disassembled Save more expensive components Recycle materials Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:17

Disassembly (cont.)

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Disassembly Strategy - Analyze feasibility of part reuse and materials recovery - Generate optimal disassembly sequence - Disassembly optimization (Lower disassembly cost, higher rate of component reuse, higher rate of material recycling, etc.) Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:18

Recycling Metals

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Mixed metals (plating) - expensive Pure metals - very inexpensive Separation techniques:

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Manual

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Automated magnetic separation Chemical separation

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Pyrometallurgy, hydrometallurgy, electrometallurgy Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:19

Recycling Plastics

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Thermoplastics - easy

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Polyethylene terepthalate, polyvinyl chloride, low density polyethylene, polypropylene

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Thermoset plastics

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Phenolics, polyesters, epoxides: crosslinking, need pyrolysis / hydrolysis to reduce mol. Wt. Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:20

Mechanical Recycling Feed Stock Recycling Energy Recovery

Recycling Rubber

Use as is (Retreaded tired, fishing banks, etc.) Powdered rubber (Block, road paving, etc.) Reclaimed rubber (Devulcanization by the PAN reclaiming Thermal decomposition, etc Recovery of heat energy Source: Otsuka et al., SAE 2000 world congress Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:21

Recycling Forest Products

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Paper

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Fibers get shorter with use & recycling

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White bond Colored bond newspaper grocery bags toilet paper Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:22

Economics

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Recycling must be profitable

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Revenue from recycling:

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High value, reusable subassembly and parts

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Recycled materials and energy

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Cost incurred by recycling:

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Investments in recycling equipment

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Labor cost

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Other cost such as transportation, equipment operating Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:23

Economics (cont.)

Disassembly cost Landfilling Cost Number of Disassembly Steps Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:24

References

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Graedel & Allenby, Industrial Ecology, 1995 http://minerals.usgs.gov/minerals/pubs/commodity/recycle/index.

html http://doemetalsrecycle.ornl.gov/ http://www.edf.org/pubs/reports/armythfin.html

http://www.recycle.net/recycle/ http://mime1.marc.gatech.edu/Courseware/autorecycling/MatRecy c.html

http://srl.marc.gatech.edu/education/Recycle/EnergRec.

html Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:25

Homework #6

1

How is the manufacturing economics affected by environmental considerations? (Illustrate your answer by using machining as an example)

2

What steps would you take in a quantitative decision making process? What are the different tools available in this process?

3

Compare and contrast traditional and ECDM guidelines for material selection.

Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:26

Homework #6

4

Why is recycling of plastics so important for the ECDM efforts? Give relevant statistics to support your answer.

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What are the major hurdles in recycling of plastics? How can they be overcome?

Environmentally Conscious Design & Manufacturing (ME592) Date: April 17, 2000 Slide:27