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Questions tagged [metallurgy]

Chemical and physical characteristics of metals and alloys.

Metallurgy, in a highly simplified manner, has several crucial steps. These are:

  1. Crushing of the ore by powdering or grinding to increase its surface area
  2. Concentration/Benefaction/Dressing (removal of impurities) by froth floatation/levigation/magnetic separation/etc.
  3. Roasting or calcination (where appropriate) to form a metal oxide
  4. Reduction of the pure metal oxide to metal: electrolytically, by reducing agent, self-reduction, or by heating
  5. Purification of the metal obtained in step 4

Several metals like iron or copper also involve formation and removal of "matrix" (infusible impurities) removed as fusible "slag" by addition of acidic or basic "flux".

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How do manufacturer remove oxygen from metal during melting?

How do manufacturers remove oxygen from metal during melting? I melt aluminium with nichrome wires and during melting it, it forms lots of slag (aluminium oxide) and I have to remove it manually.
tattoo556
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What is required to achieve 999.9999 or finer gold?

After doing some research on gold purity, I found that the current record of gold fineness is at an astounding 999.999 fine achieved by the Perth Mint, Australia 1957. However, I could not find any other attempts to break this record. I have also…
Sonny6155
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Why doesn't the Bessemer process oxidize the iron?

The Bessemer process for making steel involves blowing air or oxygen thru hot iron. Impurities and carbon oxidize away. Why does the iron itself not oxidize?
Willk
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Contactless non-ferrous metals hardening?

Is it possible to work-harden non-ferrous metals without direct contact? I know induction hardening is used on ferrous metals, but would like to know if a technique exists for non-ferrous metals.
cannotcompute
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Obtaining 100% pure metal

While reading my book everywhere I found that 99.9% pure metal is obtained. Is it possible by any process that we get 100% pure metal on industrial level?
Vidit Kulshreshtha
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Why aren't soldering tips coated with platinum?

The tips in a soldering iron tend to oxidize quite quickly (therefore becoming unuseable) if left heated and unused for more than a few seconds. Why aren't they coated with platinum or some other material that sticks to solder and doesn't dissolve…
genealogyxie
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What does it mean to 'fuse' ores and why do we use alkali metals in the process?

For the extraction of chromium, fusion of chromite ore with sodium or potassium carbonate in excess of air is done. What exactly happens in this 'fusion' process? According to my textbook (class XII chemistry, NCERT): d- and f-block element,…
tryst with freedom
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Recovering and casting indium

I bought some scrap indium online, and I melted it down into an ingot on my kitchen stove, but my losses were very high as molten indium has a surprising ability to stick to things. I have a lot of indium stuck to a stainless steel pot, and,…
desromic
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Froth floatation process - Use of stabilizers in froth floatation method

How exactly do the stabilizers affect the process of Froth floatation method? I mean how do they stabilize the froth in the process?
Uday
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What is the shiny structure under a metal coating?

I performed a hot dip aluminizing on steel for 15 seconds. Then, after I bent the steel to remove the coating easier, the steel under was rough, shiny, and metallic, and was different from the original steel.The layer seems to be random and has…
Acid
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Can you undo 'blackening' from Chromium after exposure to bleach?

I accidentally used toilet cleaner (instead of bathroom cleaner) containing bleach on a Chromed tap/faucet which has resulted in an black clouding over the surface of the chrome. It doesn't seem to polish out or clean off even with metal polish. …
NickG
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Why are Pd and Pt completely soluble in Cu, but Ag only partly in Cu when forming a substitutional solid solution?

Why are Pd and Pt completely soluble in Cu, but Ag only partly in Cu when forming a substitutional solid solution? If we look at the Hume-Rothery rules, they all are within the 15% atomic radius factor with respect to Cu and all have the same…
strateeg32
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Calcination in metallurgical process?

In calcination why is the ore heated in the absence of air in a reverberatory furnace, does the presence of oxygen affect any thing?
user63762453
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How is decarburisation achieved during Electric Arc Furnace steelmaking?

In the basic oxygen process, steel is made from pig iron (having a high carbon content) by oxidising the carbon with a high-pressure oxygen lance. In an EAF, steel is made mostly from scrap, but it can also be made from raw materials such as Pig…
Boris Mulder
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Does chromium oxide form on Stainless-steel in 'deoxygenated' water?

Will a passive layer form on stainless-steel in pure (0.055 μS/cm) water with an oxygen concentration < 50 ppb. If so, why is this type of water generally called 'deoxygenated'? If a passive layer (chromium oxide) does not form with such low oxygen…
Shiz
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