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Cob Saving Attachment
Corn cob harvesters designed to fit self-propelled combines have been developed by Purdue University Ag Engineers and, at least one private company that plans to introduce the new add-on soon.
According to Ag Engineer Clarence Richey, the Purdue-designed corn cob harvesters sort the cobs from the stalks and husks to use as fuel, or for sale to further processors. Purdue engineers, in conjunction with the USDA, have developed a corn cob gasification burner for grain drying and they use their cob harvester to obtain clean fuel for that unit.
"One acre of cobs out of every three is enough to dry an entire corn crop. In 100 bu. per acre corn, you'll get about 1/2 ton of cobs," says Richey, noting that for their cob-fired burner they need clean cobs. Some of the funding for the project came from companies, such as Quaker Oats and the Andersons, which need corn cobs for further processing.
The Purdue cob-saver bolts to the rear of the combine and uses a combination of air and mechanical separation. It involves some modification of the rear body of the combine and is powered off the combine itself. A fan blows across the cobs as they drop off the combine straw walkers and into a straw chopper. The chopper flails the partly cleaned cobs to further break them and cut loose as many of the attached husks as possible. The cleaned cobs drop into a cross auger feeding into a forage blower which throws them into a trailing wagon.
The unit saves about 80% of the cobs by weight and cobs make up 86 to 94% of the material salvaged. Most of the extra trash is husks attached to the cob. Power consumption of the cob saver is around 9 to 10 hp. and pulling the wagon behind requires an additional 7 hp. Researchers figure the cob-salvaging operation reduces total corn harvesting capacity roughly 5%.
If a farmer doesn't plan to burn cobs himself, there are other markets for cobs. Quaker Oats, for example, is interested in cobs to extract a material called "furfural" which they sell to companies for the manufacture of plastics. The Andersons, located in Maumee, Ohio, use cobs for a variety of products, including facial powders and sandblasting. Some 500,000 tons of crushed cobs go to Pennsylvania each year for use in the mushroom growing industry. Richey says that "in season" corn cobs sell for about $6 a ton but off season prices range as high as $90 a ton.

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1983 - Volume #7, Issue #5