A
s metal recyclers, metal- casting facilties have long considered themselves a
part of the green movement. In real- ity, the industry has only scratched the surface and has yet to achieve the higher level of sustainability that the future will demand. Metalcasting is energy intensive, handles massive quantities of processed waste materi- als often destined for landfills and has the potential to emit a large quantity of carbon dioxide and other pollutants into the atmosphere. Energy reductions in the manu-
facturing process pose significant potential improvements in total energy usage and the reduction of carbon emissions resulting from the combustion of fossil fuels. To become greener, one must find ways to increase the efficient use of energy in the complete manufacturing process and not merely shift enery use up or down the manufacturing stream. Significant capital spending is not
the only way to realize savings and improvements. Metalcasters can work within their own model to achieve results. Much of the technology to become greener exists now, and met- alcasters have the resources to become increasingly sustainable in the future. Following are specific areas in metal- casting operations that yield savings.
Reuse of Waste Heat Te reuse of waste heat can
net energy savings of 15-25% or more. While technologies exist for converting waste heat energy to electric power, a simple and less costly approach is to directly recover captured waste heat for use in an area that requires heat. Te simplest approach to reusing baghouse heat energy is the direct re-introduction of the exhausted- filtered air back into the plant. Tis is feasible if no additional gaseous waste pollutants are present in the waste air stream. Modern baghouses and the advent of broken bag detection tech- nology have eliminated the concern of reintroduction of particulates back into the workplace. Well run dust col- lection equipment regularly contains a lower particulate count than what
may be experienced in the general work environment.
Air Handling Many metalcasting facilities’ air
capture and baghouse systems have not undergone significant redesign since their initial installation in the 1970s. Te average emissions sys- tem may consume 20 to 25% of the total energy usage in the plant. Many improvements in piping, engineering, components, baghouse design and bag materials can be incorporated into an updated system.
Lighting Plant and office lighting can be
a significant source of energy sav- ings, although some capital costs will be required. Today’s lighting fixture designs drive light deeper into the plant and provide truer colors for better employee comfort. Proper engineered lighting fixture layout can improve effi- ciency. Motion sensing and centralized automated control also offer oppor- tunities for significant improvements in energy savings and maintaining consistent levels of light. Because lighting is easily measured,
many government agencies and power providers offer significant available rebates and tax incentives.
FROM THE AUTHOR
Many of these ideas are not new, and we have all talked about implementing them. However, time passes, and maybe we have not pursued these ideas due to other current concerns or we have done so only in an inconsistent man- ner. Reaching the point of determined action and embracing the possibilities of sustainability may prove to be one of the industry’s greatest challenges. With a focus on thinking green in all aspects of the process and the pragmatic applica- tion of existing technology, the metal- casting industry will be recognized as a sustainability leader.
Gary Gigante is president of ThyssenKrupp Waupaca, Waupaca, Wis., a gray, ductile and compacted graphite iron casting producer and one of the largest metalcasters in the world.
April 2011 MODERN CASTING | 39
Compressed Air Te generation and delivery of
compressed air is inefficient, with one-third of all compressed air horsepower lost in the process. A supply and demand side audit, as well as a system leak evaluation, can yield tremendous benefits. Savings are typically realized in low-capital activities, such as leak repairs, piping changes, air storage sizing and proper compressor sequencing.
Melt Savings Buying the right scrap can net
energy savings before melting materi- als are received at the metalcasting facility. Ferrous casting facilities have been comfortable receiving post- consumer steel scrap that contains surface rust, paint, adhering non- metallics and other non-steel attach- ments. Sheared scrap can contain 5-8% by weight of tramp non-metal- lic materials. It takes 1.7 to two times the energy to melt slag than iron. By purchasing clean scrap created by shredding rather than shearing, a metalcaster can reduce energy con- sumption by 15-20%. Further melt savings can be
achieved by cleaning gates and risers of sand by passing them through a rotary
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68