The greater the ratio of surface area to mass, the higher the melting loss. In the smelting of zinc and aluminum, the use of large pieces instead of small pieces of casting material can greatly reduce the amount of scum produced during the new round of metal blasting. As we all know, when smelting scrap or sawdust-like metal materials, the melting loss is very high, unless a neutral atmosphere can be used in the furnace or in an induction furnace that can obtain good stirring, but this is not cost-effective.
During storage, the degree of surface rust or oxidation cannot be ignored, especially when the alloy cannot form a protective oxide film, this metal must avoid outdoor storage. When calculating metal losses, factors such as oil, moisture, and foreign materials such as wood chips, steel chips, and copper, nickel, and chromium coatings on sheet metal castings should also be considered.
(2) Surface oxidation during heating
When the solid metal is heated to the melting point, the proportion of surface oxidation to the melting loss is quite large. From a theoretical point of view, heating a block of copper to the melting point, the metal loss is expected to be about 0.5%. The higher the heating temperature or the longer the time, the thicker the oxide film. This loss due to surface oxidation depends on the following factors Changes: the type of molten alloy, the length of the melting time of the casting, the level of the superheat temperature, the smelting atmosphere and the degree to which the oxide is reduced to metal. For copper oxide, the melt can be treated with a deoxidizer.
(3) Metals caught in scum
The scum or slag on the wide surface of the melt is a mixture of metal oxides, foreign materials and the metal involved. This scum must be removed to ensure that the holder is pure and free of scum. In the scum treatment and skimming, the use of solvents is the most effective, recyclable metal, in most cases, this is a very effective saving measure. When the zinc-aluminum alloy melt is treated with a slag remover, the metal content in the scum can be reduced by 80% to 90%.