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the scum formed, usually by oxidation, on the surfaces of molten metals



an intermediate product obtained from the liquation separation of heavy nonferrous metals with low melting points: lead, bismuth, and tin. As the metals are cooled during the refining process, impurities of low solubility, such as copper and iron, crystallize. Denser and possessed of a higher melting point than the metal being refined, the impurities (in the elemental state or in compounds) float to the surface of the bath as solids to form dross. Additives of sulfur or carbon are sometimes introduced into the metal being refined in order to remove a higher percentage of impurities. The deeper the cooled metal, the more complete the crystallization and purification; however, there is also an increase in dross yield and in the amount of refined metal found in the dross.

Dross is removed from the surface of the liquid bath with a skimmer. The liquid metal entrained mechanically with the dross drains into the bath. Dross is highly complex with respect to its chemical and phase composition; the refined metal constitutes its base. The dross obtained in the refining of lead is reprocessed by smelting in a reverberatory or electric furnace with the addition of a sulfidizing agent and fluxes. The smelted lead is returned to the primary production cycle, and the matte and speiss produced are sent to copper mills. The dross obtained in the refining of bismuth and tin is recycled.


Loskutov, F. M. Metallurgiia svintsa. [Moscow] 1965.



An impurity, usually an oxide, formed on the surface of a molten metal.
References in periodicals archive ?
We had the contract to process dross on-site and our contract was up for renewal on August 1.
Although aluminium dross is a type of waste, several useful usages have been discovered, such as filler in composite, being used in refractories industry, and also being used as adsorbent.
As a result, it can be said that the usage of the dross in concrete, decreases its detrimental environmental effect.
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As a result of decreasing waste via the dross filtering process, all Dross Boss customers have reported ROI in less than a year, according to Q.
We're pleased that Taha will provide us with a dross processing system that fits extremely well with OARC's sustainability goals," he added.
The plant produces aluminium oxide from dross under Taha's mechanical separation process at the site of the New Zealand Aluminium Smelters (NZAS) plant.
Working closely with Garmco over six years, we have developed a process for the efficient and environmentally friendly recovery of aluminium from dross, a by-product of the aluminium melting process," said Taha founder Frank Pollmann.
Laser cut quality is defined primarily by the condition of the laser cut surface and the presence of the re-solidified material occurring as dross at the lower cut edge.
Dross-B-Gone powder separates dross from molten solder.
But Dross said that depends on how or if the employer passes along any savings.
AM I the only one who was a tad disappointed by the dross served up by the TV stations over Christmas?