Mineral processingIn the field of extractive metallurgy, mineral processing is the process of separating commercially valuable minerals from their ores. Depending on the processes used in each instance, it is often also known as ore dressing or ore milling. Before the advent of heavy machinery the raw ore was broken up using hammers wielded by hand, a process called "spalling". Before long, mechanical means were found to achieve this. For instance, stamp mills were used in Samarkand as early as 973. They were also in use in medieval Persia.
ElectrowinningElectrowinning, also called electroextraction, is the electrodeposition of metals from their ores that have been put in solution via a process commonly referred to as leaching. Electrorefining uses a similar process to remove impurities from a metal. Both processes use electroplating on a large scale and are important techniques for the economical and straightforward purification of non-ferrous metals. The resulting metals are said to be electrowon.
Porphyry copper depositPorphyry copper deposits are copper ore bodies that are formed from hydrothermal fluids that originate from a voluminous magma chamber several kilometers below the deposit itself. Predating or associated with those fluids are vertical dikes of porphyritic intrusive rocks from which this deposit type derives its name. In later stages, circulating meteoric fluids may interact with the magmatic fluids. Successive envelopes of hydrothermal alteration typically enclose a core of disseminated ore minerals in often stockwork-forming hairline fractures and veins.
BorniteBornite, also known as peacock ore, is a sulfide mineral with chemical composition that crystallizes in the orthorhombic system (pseudo-cubic). Bornite has a brown to copper-red color on fresh surfaces that tarnishes to various iridescent shades of blue to purple in places. Its striking iridescence gives it the nickname peacock copper or peacock ore. Bornite is an important copper ore mineral and occurs widely in porphyry copper deposits along with the more common chalcopyrite.
CassiteriteCassiterite is a tin oxide mineral, SnO2. It is generally opaque, but it is translucent in thin crystals. Its luster and multiple crystal faces produce a desirable gem. Cassiterite was the chief tin ore throughout ancient history and remains the most important source of tin today. Most sources of cassiterite today are found in alluvial or placer deposits containing the weathering-resistant grains. The best sources of primary cassiterite are found in the tin mines of Bolivia, where it is found in crystallised hydrothermal veins.
CinnabarCinnabar (ˈsɪnəˌbɑr; ), or cinnabarite (ˌsɪnəˈbɑraɪt), is the bright scarlet to brick-red form of mercury(II) sulfide (HgS). It is the most common source ore for refining elemental mercury and is the historic source for the brilliant red or scarlet pigment termed vermilion and associated red mercury pigments. Cinnabar generally occurs as a vein-filling mineral associated with recent volcanic activity and alkaline hot springs. The mineral resembles quartz in symmetry and in its exhibiting birefringence.
PewterPewter (ˈpjuːtər) is a malleable metal alloy consisting of tin (85–99%), antimony (approximately 5–10%), copper (2%), bismuth, and sometimes silver. Copper and antimony (and in antiquity lead) act as hardeners, but lead may be used in lower grades of pewter, imparting a bluish tint. Pewter has a low melting point, around , depending on the exact mixture of metals. The word pewter is probably a variation of the word spelter, a term for zinc alloys (originally a colloquial name for zinc).
Underground hard-rock miningUnderground hard-rock mining refers to various underground mining techniques used to excavate "hard" minerals, usually those containing metals, such as ore containing gold, silver, iron, copper, zinc, nickel, tin, and lead. It also involves the same techniques used to excavate ores of gems, such as diamonds and rubies. Soft-rock mining refers to the excavation of softer minerals, such as salt, coal, and oil sands. Accessing underground ore can be achieved via a decline (ramp), inclined vertical shaft or adit.
Roasting (metallurgy)Roasting is a process of heating a sulfide ore to a high temperature in the presence of air. It is a step in the processing of certain ores. More specifically, roasting is often a metallurgical process involving gas–solid reactions at elevated temperatures with the goal of purifying the metal component(s). Often before roasting, the ore has already been partially purified, e.g. by froth flotation. The concentrate is mixed with other materials to facilitate the process.
Mill (grinding)A mill is a device, often a structure, machine or kitchen appliance, that breaks solid materials into smaller pieces by grinding, crushing, or cutting. Such comminution is an important unit operation in many processes. There are many different types of mills and many types of materials processed in them. Historically mills were powered by hand or by animals (e.g., via a hand crank), working animal (e.g., horse mill), wind (windmill) or water (watermill). In modern era, they are usually powered by electricity.
