Dross is a

mass Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different elementar ...

solid Solid is one of the State of matter#Four fundamental states, four fundamental states of matter (the others being liquid, gas, and Plasma (physics), plasma). The molecules in a solid are closely packed together and contain the least amount o ...

impurities floating on a

molten metal Melting, or fusion, is a physical process that results in the phase transition of a substance from a solid to a liquid. This occurs when the internal energy of the solid increases, typically by the application of heat or pressure, which inc ...

or dispersed in the metal, such as in wrought iron. It forms on the surface of low- melting-point metals such as

tin Tin is a chemical element with the symbol Sn (from la, stannum) and atomic number 50. Tin is a silvery-coloured metal. Tin is soft enough to be cut with little force and a bar of tin can be bent by hand with little effort. When bent, t ...

lead Lead is a chemical element with the symbol Pb (from the Latin ) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cu ...

zinc Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodi ...

aluminium Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. I ...

alloy An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductility, ...

s by

oxidation Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a d ...

of the metal. For higher melting point metals and alloys such as

steel Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistant ty ...

and

silver Silver is a chemical element with the Symbol (chemistry), symbol Ag (from the Latin ', derived from the Proto-Indo-European wikt:Reconstruction:Proto-Indo-European/h₂erǵ-, ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, whi ...

, oxidized impurities melt and float making them easy to pour off. With

wrought iron Wrought iron is an iron alloy with a very low carbon content (less than 0.08%) in contrast to that of cast iron (2.1% to 4%). It is a semi-fused mass of iron with fibrous slag Inclusion (mineral), inclusions (up to 2% by weight), which give it a ...

, hammering and later

rolling Rolling is a type of motion that combines rotation (commonly, of an axially symmetric object) and translation of that object with respect to a surface (either one or the other moves), such that, if ideal conditions exist, the two are in contact ...

remove some dross. With tin and lead the dross can be removed by adding

sodium hydroxide Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly caustic base and alkali ...

pellets, which dissolve the oxides and form a

slag Slag is a by-product of smelting (pyrometallurgical) ores and used metals. Broadly, it can be classified as ferrous (by-products of processing iron and steel), ferroalloy (by-product of ferroalloy production) or non-ferrous/base metals (by-prod ...

. If floating, dross can also be skimmed off. Dross, as a solid, is distinguished from

, which is a liquid. Dross product is not entirely waste material; for example, aluminium dross can be recycled and is also used in secondary

steelmaking Steelmaking is the process of producing steel from iron ore and carbon/or scrap. In steelmaking, impurities such as nitrogen, silicon, phosphorus, sulfur and excess carbon (the most important impurity) are removed from the sourced iron, and all ...

for slag deoxidation.

Etymology and usage

The term ''dross'' derives from the

Old English Old English (, ), or Anglo-Saxon, is the earliest recorded form of the English language, spoken in England and southern and eastern Scotland in the early Middle Ages. It was brought to Great Britain by Anglo-Saxon settlement of Britain, Anglo ...

word ''dros'', meaning the scum produced when smelting metals (extracting them from their ores). By the 15th century it had come to refer to rubbish in general. ''Dregs'', and the geological term ''druse'' are also thought to be etymologically related. Popular non-

metalworking Metalworking is the process of shaping and reshaping metals to create useful objects, parts, assemblies, and large scale structures. As a term it covers a wide and diverse range of processes, skills, and tools for producing objects on every scale ...

uses of the word are derogatory: *poorly written or plagiarized journalism - "a dross article"; "utter/complete/terrible dross" (adjective/noun), a stronger term than '' filler'' *undesirable, unprofitable work - "let's home in on the

lion's share The lion's share is an idiomatic expression which now refers to the major share of something. The phrase derives from the plot of a number of fables ascribed to Aesop and is used here as their generic title. There are two main types of story, wh ...

and outsource the dross"; synonyms:

corvée Corvée () is a form of unpaid, forced labour, that is intermittent in nature lasting for limited periods of time: typically for only a certain number of days' work each year. Statute labour is a corvée imposed by a state for the purposes of ...

, hiding-to-nothing, and

drudgery A laborer (or labourer) is a person who works in manual labor types in the construction industry workforce. Laborers are in a working class of wage-earners in which their only possession of significant material value is their labor. Industries e ...

which are growing

archaism In language, an archaism (from the grc, ἀρχαϊκός, ''archaïkós'', 'old-fashioned, antiquated', ultimately , ''archaîos'', 'from the beginning, ancient') is a word, a sense of a word, or a style of speech or writing that belongs to a hi ...

s in business "dross" ''en.wiktionary.org'' (noun); as strong a term as ''

dogsbody A dogsbody, dog's body, or less commonly dog robber is someone who does menial or drudge work.''Oxford English Dictionary'', 3rd edition, 2010''s.v.''/ref> Originally, in the British Royal Navy, a dogsbody was a semi-sarcastic colloquialism for a ...

work''

References

External links

AZoM.com – Aluminium Dross Recycling
* Herbert F. Lund
The McGraw-Hill recycling handbook
Chapter 37.23:

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and North ...

European Union The European Union (EU) is a supranational political and economic union of member states that are located primarily in Europe. The union has a total area of and an estimated total population of about 447million. The EU has often been des ...

Directive Precipitates

Aluminum Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It has ...

"Dross"

Recycling Recycling is the process of converting waste materials into new materials and objects. The recovery of energy from waste materials is often included in this concept. The recyclability of a material depends on its ability to reacquire the p ...

. {{Metalworking navbox, castopen Casting (manufacturing) Metallurgy Deoxidizers

Etymology and usage

See also

References

External links