Ore

Ore is a type of minerals, a natural mineral formation, containing compounds of useful components (minerals and metals) in concentrations that make extraction of these minerals economically viable. Economic feasibility is determined by ore resource estimation parameters. Along with native metals, metal ores exist (iron, tin, copper, zinc, nickel ore, etc.) representing basic forms of the natural occurrence of these minerals suitable for industrial and commercial use. Metallic and non-metallic ore minerals are differentiated, the latter include, for example, piezoquartz, fluorite, etc. Possibility of ore processing is determined by ore reserves. The concept of ore changes as technology advances, and a range of usable ores and minerals expands with time.

In nature, most metals are in the form of chemical compounds (oxides, silicates, carbonates, sulfur compounds) that enter into the composition of various rock-forming minerals.

Industrial ore is a type of rock, the extraction of metals or their compounds from which is feasible at a given level of technology. This level is determined by content of extractable metal in ore, e. g. it corresponds to 30– 50 % min for iron, 3–5 % for copper and 0.005–0.02 % for molybdenum.

Ore consists of minerals that contain metal or its compounds, as well as waste rock which consists of various contaminants. For example, iron ore contains iron oxides or carbonates Fe3O4, Fe2O3, FeCO3, Fe2O3•H2O and waste rock consisting mainly of SiO2, Al2O3, CaO and MgO. Ore's name is usually derived from one or more metals it contains, e. g. iron, copper, aluminium, manganese, copper-nickel, iron-manganese ores, etc.

Depending on the content of extractable substance, ores are subdivided into rich and poor ores. High-grade iron ores contain 45–50 % iron min. Special treatment, benefication, is provided for low-grade ores (with a low content of extractable metal). Benefication involves partial removal of waste rock. As a result of it, concentrate, a product with a higher content of extractable metal as compared to ore, is obtained. Use of concentrate can improve technical and economic performance of metallurgical furnaces.

Iron ores contain iron in the form of different compounds.

Chromium ores are used for production of ferrochrome, metallic chromium and refractory materials – chrome-magnesites. Chromium ores contain complex compounds of chromium: chromite (FeO•Cr2O3), magnochromite (Mg,Fe)Cr2O4,etc. Ores usually contain about 40 % Cr2O3. The former USSR had the world's largest reserves of chromium ores.

Multimetal ores are used to produce naturally alloyed pig iron. These ores include iron-manganese ores containing besides iron up to 20 % Mn (Atasui deposit), chromium-nickel ores containing 37–47 % Fe, 2 % Cr max, 1 % Ni max (Khalilovo deposit), iron-vanadium ore containing 0.17-0.35 % V max.

Manufacture of ferroalloys

To produce ferroalloys, ores and concentrates containing alloying components, mainly in the form of oxides, are used. When processed, they are reduced by carbon, silicon or aluminium. The most common method is carbon-thermal reduction by coal coke and petroleum coke fines. This method is applied in cases where there are no special requirements for carbon content in alloys. Carbon ferromanganese, ferrochromium and ferrosilicon are produced by carbon-thermal reduction.

Manganese ores are used to produce ferroalloys containing 10–82 % Mn, as well as conversion pig iron containing up to 1 % Mn. Manganese is present in its ores in the form of oxides and carbonates: MnO2, Mn2O3, Mn3O4, MnCO3, etc. Ores usually contain 22–45 % Mn max. The largest deposits of manganese ore in the former USSR are Chiatura and Nikopol. The former USSR ranked first in the world by deposits of manganese ores.