| 摘要 |
A carbohydrate is added to sand, which has been used to make foundry moulds or cores, and which has been bonded using an alkaline resol phenol-formaldehyde resin, prior to reclamation of the sand by a therm al reclamation. The thermal reclamation may be done in other equipment, for example a rotary thermal reclamation unit, but is preferably done in a fluidised bed reclamation unit. The carbohydrate is preferably water soluble and is added to the used sand as an aqueous solutio n. The carbohydrate may be for example a monosaccharide, such as glucose, mannose, galactose or fructose, or a disaccharide such as sucrose, maltose or lactose. The carbohydrate may also be a carbohydrate derivative such as a polyhydric alcohol (e.g. ethylene glycol, glycerol, pentaerythritol, xylitol, mannitol or sorbitol), a sugar acid (e.g. gluconic acid), or a polysaccharide derivative (e.g. a starch hydrolysate, i.e. a glucose syrup or a dextrin). The amount of carbohydrate used in the reclamation process is usually of the order of 0.25 % to 5.0 % by weight based on the weight of used sand.
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