Pre-heating of Scrap is usually used only at the edge of the crucible and in the spout area. One also refers to patch compounds, which are applied in accordance with the usage instructions. Since these compounds contain at least 5% water, they can also be sprayed on with the aid of suitable equipment. After an air-drying period, they must also be dried with a gas flame, in order to prevent such compounds flaking off on contact with the molten mass.
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