User:Josh Parris/copper
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Froth flotation is a wet separation process that utilizes the difference in the surface physicochemical properties of various minerals to segregate the minerals in an ore into several products. In most ores, the particles of valuable minerals are closely associated with other minerals. To separate these minerals, the ore is first crushed and then wet ground to the sizes at which valuable minerals are liberated from the gangue or worthless minerals.
Fig. 1 illustrates the flotation process in a typical flotation cell. The aqueous ground ore suspension (flotation pulp) is stirred in a tank with an impeller. For desirable minerals to float, their surfaces must be rendered hydrophobic. For undesirable minerals, the surfaces should be rendered hydrophilic. To achieve this condition, various chemicals known as flotation reagents are added in the pulp and air or gas is sparged in the tank. The desired mineral particles attaches to the air or gas bubbles. Due to the buoyancy of the bubbles, these mineral particles rise to the surface to form a mineralized froth layer and are removed as the concentrate, and other mineral particles remain suspended in the pulp due to their hydrophilic surfaces and are termed the tailing of the separation process.
The flotation process is widely used for the recovery and concentration of nonferrous sulfide minerals, such as Cu, Pb, Zn, Ni, Mo, Sb, Co, etc., as well as nonsulfide minerals, such as SiO2, CaCO3, CaF2, NaCl, KCL, sulfur, alumina, ZrSiO4, TiO2, clays, etc., which are usually used as raw materials in chemical industry. Phosphate, coal, and iron ores are also commonly processed by flotation technology.
http://www.engr.pitt.edu/chemical/undergrad/lab_manuals/flotation.pdf
[edit] pyrometallurgical
temperature molten copper measured by IR wavelength
[edit] Smelting
This is accomplished by sending the anodes to a refinery where they are electrolytically refined into essentially pure copper.
Metal ores usually contain significant impurites which must be removed prior to smelting. The process is similar to that used in processing many minerals. The stone is crushed and mixed with water to form a slurry. The slurry is agitated and specialized surfactants (similar to soaps) may be used to float either the ore concentrate or the impurities to the surface. This procedure is called "froth flotation".
Leaching
The coarser ore goes to the heap leach, where the copper is subjected to a dilute sulfuric acid solution to dissolve the copper.
Then the leach solution containing the dissolved copper is subjected to a process called solvent extraction (SX). The SX process concentrates and purifies the copper leach solution so the copper can be recovered at a high electrical current efficiency by the electrowinning cells. It does this by adding a chemical reagent to the SX tanks which selectively binds with and extracts the copper, is easily separated from the copper (stripped), recovering as much of the reagent as possible for re-use. The concentrated copper solution is dissolved in sulfuric acid and sent to the electrolytic cells for recovery as copper plates (cathodes).
What chemical acts as the reagent?
The treatment of ores, concentrates and other metal-bearing materials by an acidic wet process that dissolves soluble minerals and recovers them into a pregnant leach solution.
hydrometallurgical
a solvent is flushed through the ore and binds to the copper in preference to the ore. The solvent is then retrieved from the slurry. Example solvents are water and the more effective hydrocloric acid. In the second stage the copper is extracted from the solvent in a process of cementation or precipitation. Solvent extraction. Electrowinning is used to extract the copper from the solvent. Cement copper is usually smelted to remove impurities. And electrorefined(?).
Copper is a very unreactive metal - it's below even hydrogen in the reactivity series. This means it won't even react with water. For this reason, copper is obtained very easily from its ore by reduction with carbon.
However, this copper isn't pure enough for use in electrical conductors. The purer the copper is, the better it will conduct. Electrolysis is used to obtain very pure copper.
Cathode |
| |------------- Anode
| | |
--- ------ | | | | | | Cu2+ | | | | | | | | | | | | | | --- |-----
------------
/ Sludge \
The cathode starts as a very thin piece of pure copper and more pure copper adds to it. The anode is just a big lump of impure copper which will dissolve. The "sludge" is all the impurities.
The reaction at the cathode - Cu2+(aq) + 2s- -> Cu(s)
The reaction at the anode - Cu(s) -> Cu2+ + 2e-
The electrical supply acts by pulling electrons off the copper atoms at the anode, causing them to become Cu2+ ions. It then offers the electrons at the cathode to nearby Cu2+ ions to turn them back into copper atoms. The impurities are dropped off, and pure copper bonds to the cathode.
This process can go on for weeks, with the cathode often twenty times bigger by the end.
References Title: Copper: Technology & Competitiveness (Summary) Chapter 6 Copper Production Technology Author: Office of Technology Assessment
caveman chemistry
