Documents for "Metallurgy and Mining: Terms and Concepts":

• adit in mining, underground passage excavated nearly horizontally, with one end open to the earth's surface, usually used to service a mine. The adit end is the furthermost end from the surface, i.e.,...

• afterdamp see damp.

• alloy [O. Fr.,=combine], substance with metallic properties that consists of a metal fused with one or more metals or nonmetals. Alloys may be a homogeneous solid solution, a heterogeneous mixture of...

• amalgam alloy containing mercury. The alloy may be liquid or solid, depending on the proportion of mercury, although all naturally occurring amalgams, i.e., those of gold and silver, are solid. Amalgams are widely used. Silver,...

• amalgamation process in particular, a method to extract gold and silver from ores. The ore is crushed and treated with mercury , in which the metal dissolves. The amalgam is heated and the mercury evaporates, leaving pure gold or silver. The process has been criticized as an environmental and occupational threat due to the...

• Anderton shearer see coal mining.

• annealing process in which glass, metals, and other materials are treated to render them less brittle and more workable. Annealing consists of heating the material and then cooling it very slowly and...

• assaying in metallurgy, process of determining the specific metallic content of an ore, alloy, or other substance, especially one containing precious metals. It consists, in some cases, of subjecting the...

• Babbitt metal an antifriction metal first produced by Isaac Babbitt in 1839. In present-day usage the term is applied to a whole class of silver-white bearing metals, or "white metals." These alloys usually consist of relatively hard crystals embedded in a softer matrix, a structure important for machine bearings. They are composed primarily of tin, copper, and antimony, with...

• basic oxygen process method of producing steel from a charge consisting mostly of pig iron. The charge is placed in a furnace similar to the one used in the Bessemer process of steelmaking except that pure oxygen instead of air is blown into the charge to oxidize the impurities present. One desirable feature of this process is that it takes less than an hour, and is...

• bauxite mixture of hydrated aluminum oxides usually containing oxides of iron and silicon in varying quantities. A noncrystalline substance formerly thought to be a mineral, bauxite is claylike and earthy...

• Bayer process procedure for obtaining alumina from the aluminum ore bauxite. The alumina can then be used for various industrial purposes or smelted to provide aluminum. The first step in the process is the...

• bell metal see bronze.

• Bessemer process bĕs´emer [for Sir Henry Bessemer ], industrial process for the manufacture of steel from molten pig iron. The principle involved is that of oxidation of the impurities in the iron by the oxygen of air that is blown through the...

• blast furnace structure used chiefly in smelting. The principle involved in this means of extracting metals is that of the reduction of the ores by the action of carbon monoxide, i.e., the removal of oxygen from the metal oxide in order to obtain...

• brass alloy having copper (55%-90%) and zinc (10%-45%) as its essential components. The properties of brass vary with the proportion of copper and zinc and with the addition of small amounts of other elements,...

• brazing method of joining metal parts using nonferrous filler metals with high melting points such as copper, silver, and aluminum alloys. Brazing differs from soldering (see solder ) by using a higher temperature;...

• britannia metal silvery-white alloy of tin with antimony, copper, and sometimes bismuth and zinc. It is very similar in appearance to pewter, but is harder. It is used widely for the manufacture of tableware.

• broaching see quarrying.

• bronze in metallurgy, alloy of copper, tin, zinc, phosphorus, and sometimes small amounts of other elements. Bronzes are harder than brasses. Most are produced by melting the copper and adding the desired amounts of tin, zinc, and other substances. The properties of the alloy depend on the proportions of its components. Aluminum bronze...

• caisson sinking see shaft sinking.

• calcination in metallurgy , process of heating solid material to drive off volatile chemically combined components, e.g., carbon dioxide. It is sometimes a step in the extraction of metals from ores. Calcination is...

• carboloy [portmanteau word from carbon and alloy], an alloy containing cobalt, tungsten, and carbon. This alloy is extremely hard, harder than steel; it is used to cut steel, porcelain, quartz, and other materials. Its hardness is little affected by heat,...

• casehardening see hardening.

• cast iron see iron.

• casting or founding, shaping of metal by melting and pouring into a mold. Most castings, especially large ones, are made in sand molds. Sand, mixed with a binder to hold it together, is pressed around a wooden pattern...

• casting, plaster see plaster casting.

• channeling see quarrying.

• chill hardening see hardening.

• chokedamp see damp.

• coal mining physical extraction of coal resources to yield coal; also, the business of exploring for, developing, mining, and transporting coal in any form. Strip mining is the process in which the overburden...

• damp in mining, any mixture of gases in an underground mine, especially oxygen-deficient or noxious gases. The term damp probably is derived from the German dampf, meaning fog or vapor. Several distinct types of damp are recognized. Firedamp is methane and other flammable gases, often mixed with air; it results from the decomposition of coal or other carbonaceous materials. Explosive mixtures of firedamp with air usually contain from 1% to 14%...

• die any of various devices used for drawing wire, and for blanking, bending, cutting, machine forging, and embossing. Dies used for striking, or stamping, coins and medals are cut in intaglio, one for...

• die-casting process by which molten metal is forced by a plunger or compressed air into a metallic die and the pressure maintained until the metal has solidified. Die castings are accurate, are sharply...

• divining rod or dowser, stick used in searching for underground water or minerals. This form of divination is still in common use in many parts of the world. The instrument is typically a forked twig. The operator holds...

• dowser see divining rod.

• drainage in mining, removal of water seeping into shafts and other underground mine workings from the surrounding ground. Unless seeping water is removed continually, it may endanger haulage and mining...

• ductility ability of a metal to plastically deform without breaking or fracturing, with the cohesion between the molecules remaining sufficient to hold them together (see adhesion and cohesion ). Ductility is important in wire drawing and sheet stamping. The metal must neither break nor be scraped off during these processes. Platinum, steel, copper, and tungsten have high ductility...

• duralumin alloy of aluminum (over 90%) with copper (about 4%), magnesium (0.5%-1%), and manganese (less than l%). Before a final heat treatment the alloy is ductile and malleable; after heat treatment a...

• Dutch metal see brass.

• electroplating see plating.

• fatigue in engineering, microscopic cracking of materials, especially metals, after repeated applications of stress. Fissures may be formed within pieces of metal during their manufacture when, while...

• firedamp see damp.

• Fischer-Tropsch process method for the synthesis of hydrocarbons and other aliphatic compounds. Synthesis gas, a mixture of hydrogen and carbon monoxide, is reacted in the presence of an iron or cobalt catalyst; much...

• flotation process in mineral treatment and mining, process for concentrating the metal-bearing mineral in an ore. Crude ore is ground to a fine powder and mixed with water, frothing reagents, and collecting reagents. When air is blown through the mixture, mineral particles cling to the bubbles, which rise to...

• forging shaping metal by heating it and then hammering or rolling it. Forging is the method by which metal was first worked when it came into use about 4000 BC in Egypt and Asia. Modern forging is done...

• founding see casting.

• Frasch process [for Herman Frasch, the German-American chemist who devised it], process for the extraction of sulfur from subsurface deposits. Three pipes, one inside another, are sunk to the bottom of the sulfur bed. Water heated under pressure to a temperature well above the melting point of the sulfur is...

• froth-flotation process see flotation process.

• gadding machine see quarrying.

• galvanizing process of coating a metal, usually iron or steel, with a protective covering of zinc. Galvanized iron is prepared either by dipping iron, from which rust has been removed by the action of sulfuric...

• German silver name for various alloys of copper, zinc, and nickel, sometimes also containing lead and tin. They were originally named for their silver-white color, but use of the term silver is now prohibited for alloys not containing that metal. German silver varies in composition, the percentage of the three elements ranging approximately as follows: copper, from 50% to 61.6%; zinc,...

• gunmetal a bronze , an alloy of copper, tin, and a small amount of zinc. Although originally used extensively for making guns (from which it received its name), it has been superseded by steel, and it is now chiefly...

• hardening in metallurgy, treatment of metals to increase their resistance to penetration. A metal is harder when it has small grains, which result when the metal is cooled rapidly. Sometimes small areas on...

• leaching method of extraction in which a solvent is passed through a mixture to remove some desired substance from it. A simple example is the passage of boiling water through ground coffee to dissolve and...

• lode deposit of ore.

• long-wall mining see coal mining.

• magnalium alloy of aluminum and about 5% magnesium. Although weak and soft in the elemental state, magnesium alloys with aluminum, manganese, zinc, tin, zirconium, and cerium to produce alloys useful in...

• malleability property of a metal describing the ease with which it can be hammered, forged, pressed, or rolled into thin sheets. Metals vary in this respect; pure gold is the most malleable. Silver, copper,...

• metallurgy science and technology of metals and their alloys. Modern metallurgical research is concerned with the preparation of radioactive metals, with obtaining metals economically from low-grade ores, with obtaining and refining rare metals hitherto not...

• mine in industry: see mining.

• mining extraction of solid mineral resources from the earth. These resources include ores, which contain commercially valuable amounts of metals, such as iron and aluminum; precious stones, such as...

• Mond process see under Mond, Ludwig.

• Mother Lode belt of gold-bearing quartz veins, central Calif., along the western foothills of the Sierra Nevada. The term is sometimes limited to a strip c.70 mi (110 km) long and from 1 to 6 1/2 mi (1.6-10.5 km) wide, running NW from Mariposa. Popularly it is used to mean the gold-bearing area E of the Sacramento and San Joaquin rivers and W of the Sierra Nevada. The discovery of alluvial...

• open-hearth process see steel.

• ore metal-bearing mineral mass that can be profitably mined. Nearly all rock deposits contain some metallic minerals, but in many cases the concentration of metal is too low to justify mining the ore. Ores are usually found concentrated in deposits with a definite gradation of metal concentration from the ore to the surrounding rock. The ore often occurs in veins, which are ore-filled...

• Parkes process see silver.

• pig iron see iron.

• placer mining see mining.

• plating application of a plate, or coat, of metal to a surface for decoration, reflection of light, protection against corrosion, or increased wearing quality. The practice is of ancient origin: gilding was developed early; the Romans soldered silver plates to articles of baser metals; and in the 5th cent. a process was described where iron weapons were coated with copper by dipping them in a...

• platinite alloy that is 46% nickel and 54% iron. It is used in the manufacture of electric lightbulbs because its coefficient of expansion, i.e., the rate at which its volume increases with temperature, is...

• prospecting search for mineral deposits suitable for mining. Modern prospecting has replaced earlier methods based on chance or superstition (e.g., use of the divining rod) with others based on a scientific knowledge of modern geology and mineralogy...

• puddling see Henry Cort.

• quarrying open, or surface, excavation of rock used for various purposes, including construction, ornamentation, road building, and as an industrial raw material. Rock that has been quarried is commonly...

• refining any of various processes for separating impurities from crude or semifinished materials. It includes the finer processes of metallurgy, the fractional distillation of petroleum into its commercial...

• rolling mill see steel.

• safety lamp oil lamp designed for safe use in mines and other places where flammable gases such as firedamp (see damp ) may be present. Its invention (c.1816) is usually attributed to Sir Humphry Davy. The Davy lamp is based upon the principle that to be ignited a substance must first be heated to its kindling...

• shaft sinking excavation from the surface of an opening in the earth. Shafts, which are generally vertical, are usually distinguished from tunnels , which are horizontal. Little difficulty is experienced in shaft sinking through solid rock, which contains little water. When loose, water-bearing strata have to be contended with, careful shoring...

• shape memory property possessed by certain alloys that allows them to return, when heated, to their original shape after having been deformed. This effect results because, as the alloy is deformed, it undergoes a martensitic (or athermal)...

• sherardized iron see galvanizing.

• sintering process of forming objects from a metal powder by heating the powder at a temperature below its melting point. In the production of small metal objects it is often not practical to cast them...

• slag see metallurgy.

• smelting in metallurgy, any process of melting or fusion, especially to extract a metal from its ore. Smelting processes vary in detail depending on the nature of the ore and the metal involved, but they...

• smithing see forging.

• solder metal alloy used in the molten state as a metallic binder. The type of solder to be used is determined by the metals to be united. Soft solders are commonly composed of lead and tin and have low...

• stainless steel see steel.

• steel alloy of iron, carbon, and small proportions of other elements. Iron contains impurities in the form of silicon, phosphorus, sulfur, and manganese; steelmaking involves the removal of these...

• strip mining see coal mining.

• taconite low-grade iron ore, a flintlike rock usually containing less than 30% iron. Resistant to drilling and to the extraction of its contained metal, the rock was long considered worthless. Experiments...

• tempering process involving slow and moderate heating to increase the hardness and toughness of metals that have undergone previous heat treatment. Metals are usually hardened (see hardening ) by being heated to high temperatures and quenched rapidly. This treatment causes brittleness, which is reduced by tempering. Steel is notably responsive to tempering, and makers of tools, weapons,...

• type metal alloy of lead with antimony, tin, and sometimes copper, so named because of its one time extensive use for making printing type. Expanding upon solidification, the alloy takes a fine and clear...

• underground coal mining see coal mining.

• welding process for joining separate pieces of metal in a continuous metallic bond. Cold-pressure welding is accomplished by the application of high pressure at room temperature; forge welding (forging) is...

• white metal see Babbitt metal.

• wire saw see quarrying.