Silver in copper

Pauwels j, De Angelis L, Peeteemans F, Ingelerecht C (1990) Determination of traces of silver in copper by direct Zeeman graphite furnace atomic absorption spectrometry. Fresenius J Anal Chem 337 290-293. 

Traces of silver in copper amalgam [32] and in tellurium [66] have been determined by the method involving 1,10-phenanthroline and Bromopyrogallol Red. 

It might at this stage be mentioned that when the atomic diameter of the solute atom happens to fall just inside the favourable range of the solvent atom the deductions tend to be somewhat unreliable. However, when we deal with the question of the solid solubilities of silver in copper, and of copper in silver, we find that each metal falls only just within the favourable range of the other we are not, therefore, surprised to find the copper-silver equilibrium diagram showing that somewhat restricted solid solubility does occur in each instance. 

Weng Z, Lee R, Jia W, Yuan Y, Wang W, Feng X, Huang KW. Cooperative effect of silver in copper-catalyzed trifluoromethylation of aryl iodides using MesSiCFs. Organometal-... 

Sundquist [35], studying small crystals of metals, noted a great tendency for rather rounded shapes and concluded that for such metals as silver, gold, copper, and iron there was not more than about 15% variation in surface tension between different crystal... 

Copper is reddish and takes on a bright metallic luster. It is malleable, ductile, and a good conductor of heat and electricity (second only to silver in electrical conductivity). 

Gobalt occurs in the minerals cobaltite, smaltite, and erythrite, and is often associated with nickel, silver, lead, copper, and iron ores, from which it is most frequently obtained as a by-product. It is also present in meteorites. 

On the other hand, Pritchard, more recently, has found that on the (111) plane of both silver and copper, the value of u (Xe) is close to 17-0 A (17-7 for Ag, 16-9 A for Cu) and this corresponds to the spacings in solid xenon rather than in the metal adsorbents. ... 

The lead buUion, ready to be shipped to the refinery, contains in solution impurities such as silver, gold, copper, antimony, arsenic, bismuth, nickel, 2inc, cadmium, tin, tellurium, and platinum metals. 

Pemoval of Other Impurities. After softening, the impurities that may stiU remain in the lead are silver, gold, copper, tellurium, platinum metals, and bismuth. Whereas concentrations may be tolerable for some lead appHcations, the market values encourage separation and recovery. The Parkes process is used for removing noble metals and any residual copper, and the KroU-Betterton process for debismuthizing. 

Copper and silver combined with refractory metals, such as tungsten, tungsten carbide, and molybdenum, are the principal materials for electrical contacts. A mixture of the powders is pressed and sintered, or a previously pressed and sintered refractory matrix is infiltrated with molten copper or silver in a separate heating operation. The composition is controlled by the porosity of the refractory matrix. Copper—tungsten contacts are used primarily in power-circuit breakers and transformer-tap charges. They are confined to an oil bath because of the rapid oxidation of copper in air. Copper—tungsten carbide compositions are used where greater mechanical wear resistance is necessary. 

A third group includes silver—nickel, silver—cadmium oxide, and silver—graphite combinations. These materials are characterized by low contact resistance, some resistance to arc erosion, and excellent non sticking characteristics. They can be considered intermediate in overall properties between silver alloys and silver or copper—refractory compositions. Silver—cadmium oxide compositions, the most popular of this class, have wide appHcation in aircraft relays, motor controllers, and line starters and controls. 

For many electronic and electrical appHcations, electrically conductive resias are required. Most polymeric resias exhibit high levels of electrical resistivity. Conductivity can be improved, however, by the judicious use of fillers eg, in epoxy, silver (in either flake or powdered form) is used as a filler. Sometimes other fillers such as copper are also used, but result in reduced efficiency. The popularity of silver is due to the absence of the oxide layer formation, which imparts electrical insulating characteristics. Consequently, metallic fibers such as aluminum are rarely considered for this appHcation. 

Resources. World resources of silver are estimated to be about half a million tons. However, only about 250,000 metric tons are considered economically recoverable reserves. These are associated with ores of copper, gold, lead, and 2inc, and extraction depends on the economic recovery of those metals. Canada and the CIS vie for the greatest reserves of silver in the ground. 

The discovery of aqua regia by the Arab alchemist Jabir Ibn Hayyan (ad 720—813) provided a new extraction technology. Amalgamation of silver in ores with mercury was extensively used during the late fifteenth century by the Spaniards in Mexico and BoLvia. In 1861 the complex ores of the Comstock Lode, Nevada, were ground together with mercury, salt, copper sulfate, and sulfuric acid, and then steam-heated to recover the silver. 

The chlorination process, introduced in Europe in 1843, roasted ore with chlorides, followed by a hot brine leach and subsequent precipitation of the silver on copper. In 1887 it was discovered that gold and silver can be recovered by sodium cyanide, and this process displaced the dangerous chlorination process. By 1907 the cyanide process, where a cyanide solution is mixed with 2inc dust to precipitate the silver, was universally in use. 

Solvent for Electrolytic Reactions. Dimethyl sulfoxide has been widely used as a solvent for polarographic studies and a more negative cathode potential can be used in it than in water. In DMSO, cations can be successfully reduced to metals that react with water. Thus, the following metals have been electrodeposited from their salts in DMSO cerium, actinides, iron, nickel, cobalt, and manganese as amorphous deposits zinc, cadmium, tin, and bismuth as crystalline deposits and chromium, silver, lead, copper, and titanium (96—103). Generally, no metal less noble than zinc can be deposited from DMSO. 

In the Parkes desilvering process, 1—2% zinc is added to molten lead where it reacts with any gold, silver, and copper to form intermetaUic compounds which float as cmsts or dross that is skimmed (see Lead and lead alloys). 

Silver [7440-22-4] Ag, as an active material in electrodes was first used by Volta, but the first intensive study using silver as a storage battery electrode was reported in 1889 (5) using silver oxide—iron and silver oxide—copper combinations. Work on silver oxide—cadmium followed. In the 1940s, the use of a semipermeable membrane combined with limited electrolyte was introduced by Andrir in the silver oxide—2inc storage battery. 

Electrodes. AH of the finished silver electrodes have certain common characteristics the grids or substrates used in the electrodes are exclusively made of silver, although in some particular cases silver-plated copper is used. Material can be in the form of expanded silver sheet, silver wire mesh, or perforated silver sheet. In any case, the intent is to provide electronic contact of the external circuit of the battery or cell and the active material of the positive plate. Silver is necessary to avoid any possible oxidation at this junction and the increased resistance that would result. 

Cobalt is the thirtieth most abundant element on earth and comprises approximately 0.0025% of the earth s cmst (3). It occurs in mineral form as arsenides, sulfides, and oxides trace amounts are also found in other minerals of nickel and iron as substitute ions (4). Cobalt minerals are commonly associated with ores of nickel, iron, silver, bismuth, copper, manganese, antimony, and 2iac. Table 1 Hsts the principal cobalt minerals and some corresponding properties. A complete listing of cobalt minerals is given ia Reference 4. 

The higher ionisation energy and smaller ionic radius of copper contribute to its forming oxides much less polar, less stable, and less basic than those of the alkah metals (13). Because of the relative instabiUty of its oxides, copper joins silver in occurring in nature in the metallic state. 

Although some changes occur in the melting furnace, cathode impurities are usually reflected directly in the final quaUty of electrorefined copper. It is commonly accepted that armealabiUty of copper is unfavorably affected by teUurium, selenium, bismuth, antimony, and arsenic, in decreasing order of adverse effect. Silver in cathodes represents a nonrecoverable loss of silver to the refiner. If the copper content of electrolyte is maintained at the normal level of 40—50 g/L, and the appropriate ratio of arsenic to antimony and bismuth (29) is present, these elements do not codeposit on the cathode. 

Copper has a high electrical conductivity that is second only to that of silver. The conductivity of silver in % lACS units is 108 gold, 73 aluminum, 64 and iron, 18. Wrought copper having a conductivity near 102% lACS is not uncommon because of improvements in refining practices since the standard was first estabUshed. 

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