Impurities in the context of "Non-ferrous extractive metallurgy"

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⭐ Core Definition: Impurities

In chemistry and materials science, impurities are chemical substances inside a confined amount of liquid, gas, or solid. They differ from the chemical composition of the material or compound. Firstly, a pure chemical should appear in at least one chemical phase and can also be characterized by its phase diagram. Secondly, a pure chemical should prove to be homogeneous (i.e., a uniform substance that has the same composition throughout the material). The perfect pure chemical will pass all attempts to separate and purify it further. Thirdly, and here we focus on the common chemical definition, it should not contain any trace of any other kind of chemical species. In reality, there are no absolutely 100% pure chemical compounds, as there is always some small amount of contamination.

The levels of impurities in a material are generally defined in relative terms. Standards have been established by various organizations that attempt to define the permitted levels of various impurities in a manufactured product. Strictly speaking, a material's level of purity can only be stated as being more or less pure than some other material.

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👉 Impurities in the context of Non-ferrous extractive metallurgy

Non-ferrous extractive metallurgy is one of the two branches of extractive metallurgy which pertains to the processes of reducing valuable, non-iron metals from ores or raw material. Metals like zinc, copper, lead, aluminium as well as rare and noble metals are of particular interest in this field, while the more common metal, iron, is considered a major impurity. Like ferrous extraction, non-ferrous extraction primarily focuses on the economic optimization of extraction processes in separating qualitatively and quantitatively marketable metals from its impurities (gangue).

Any extraction process will include a sequence of steps or unit processes for separating highly pure metals from undesirables in an economically efficient system. Unit processes are usually broken down into three categories: pyrometallurgy, hydrometallurgy, and electrometallurgy. In pyrometallurgy, the metal ore is first oxidized through roasting or smelting. The target metal is further refined at high temperatures and reduced to its pure form. In hydrometallurgy, the object metal is first dissociated from other materials using a chemical reaction, which is then extracted in pure form using electrolysis or precipitation. Finally, electrometallurgy generally involves electrolytic or electrothermal processing. The metal ore is either distilled in an electrolyte or acid solution, then magnetically deposited onto a cathode plate (electrowinning); or smelted then melted using an electric arc or plasma arc furnace (electrothermic reactor).

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Impurities in the context of Rock salt

Halite (/ˈhælaɪt, ˈheɪlaɪt/ HAL-yte, HAY-lyte), commonly known as rock salt, is a type of salt, the mineral (natural) form of sodium chloride (NaCl). Halite forms isometric crystals. The mineral is typically colorless or white, but may also be light blue, dark blue, purple, pink, red, orange, yellow or gray depending on inclusion of other materials, impurities, and structural or isotopic abnormalities in the crystals. It commonly occurs with other evaporite deposit minerals such as several of the sulfates, halides, and borates. The name halite is derived from the Ancient Greek word for "salt", ἅλς (háls).

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Impurities in the context of Chemical purity

In chemistry, chemical purity is the measurement of the amount of impurities found in a sample. Several grades of purity are used by the scientific, pharmaceutical, and industrial communities. Some of the commonly used grades of purity include:

  • ACS grade is the highest level of purity, and meets the standards set by the American Chemical Society (ACS). The official descriptions of the ACS levels of purity is documented in the Reagent Chemicals publication, issued by the ACS. It is suitable for food and laboratory uses.
  • Reagent grade is almost as stringent as the ACS grade.
  • USP grade meets the purity levels set by the United States Pharmacopeia (USP). USP grade is equivalent to the ACS grade for many drugs.
  • NF grade is a purity grade set by the National Formulary (NF). NF grade is equivalent to the ACS grade for many drugs.
  • British Pharmacopoeia: Meets or exceeds requirements set by the British Pharmacopoeia (BP). Can be used for food, drug, and medical purposes, and also for most laboratory purposes.
  • Japanese Pharmacopeia: Meets or exceeds requirements set by the Japanese Pharmacopoeia (JP). Can be used for food, drug, and medical purposes, and also for most laboratory purposes.
  • Laboratory grade is suitable for use in educational settings, but is not acceptable for food or drug use.
  • Purified grade is not precisely defined, and it is not suitable for drug or food usage.
  • Technical grade is suitable for industrial applications, but is not acceptable for food or drug use.
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Impurities in the context of Flux (metallurgy)

In metallurgy, a flux is a chemical reducing agent, flowing agent, or purifying agent. Fluxes may have more than one function at a time. They are used in both extractive metallurgy and metal joining. They are named for the ability to make molten metals easier to flow during smelting.

Some of the earliest known fluxes were sodium carbonate, potash, charcoal, coke, borax, lime, lead sulfide and certain minerals containing phosphorus. Iron ore was also used as a flux in the smelting of copper. These agents served various functions, the simplest being a reducing agent, which prevented oxides from forming on the surface of the molten metal, while others absorbed impurities into slag, which could be scraped off molten metal.

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LINKED FROM (PARENTS)
← Rock salt ← Chemical purity ← Halite ← Flux (metallurgy) ← Mineral salt ← Non-ferrous extractive metallurgy
LINKS TO (CHILDREN)
Chemistry → Materials science → Chemical substance → Liquid → Gas → Solid → Chemical composition → Phase (matter) → Phase diagram → Homogeneous → Contamination → Standardization →