EN
Ore recovery
Ore recovery is a set of methods and processes aimed at the recovery of chemical elements, or more precisely, at obtaining elements that do not consist of any chemical compounds, such as oxides, sulfides, etc. The range of techniques and methods in this industry is very extensive and includes a number of specifications depending on the element being recovered and its required purity.
Usually, elements in ore are in chemical compounds, that is, in chemical states characteristic of a given compound. These are mainly oxides and sulfides.
For reduction from oxide states , chemical reactions based on interaction with hydrogen are usually used, for example:
CuO + H2 --- > Cu + H20
3Fe 2 O 2 + H 2 ---> 2Fe 3 O 4 + H 2 O
Also, the reduction from oxides can be used by reactions with interaction with carbon monoxide:
Fe3O4 + 4CO = 3Fe + 4CO2
Such reactions usually occur at high temperatures, below the melting point of the metals being reduced.
Similar methods are used to reduce metals in sulfide compounds, but depending on the metal being reduced, namely its properties, it is necessary to select a suitable reducing agent. However, the basic scheme of all reduction processes is identical.
MoS2 + 2H2 --- > Mo + 2H2S
Ag2S + O2 --- > 2Ag + SO2
Therefore, to understand the basic concept, let's consider the process of reducing one element - iron. The bulk of iron used by mankind goes through the reduction stage from iron ore. The main and most economical way to reduce iron is the method of carbothermic reduction of iron from ore, the main reaction of which is:
Fe X O Y + C ---> Fe + CO 2
The main method of obtaining iron using this method is the blast furnace method of obtaining iron (cast iron), in which iron ore enters into a chemical reaction with coke carbon. The product of this process is cast iron, which contains up to 3% carbon. However, cast iron is very brittle, and further purification from carbon is a very labor-intensive process. One of the varieties of the carbothermic process is the process of iron recovery from ore with natural gas. The following reactions occur:
CH4+H2O=CO+H2 (natural gas conversion)
FeХOY +CO=Fe+CO2
FeХOY +H2=Fe+H2O
As a result of this process, direct reduction iron is obtained, which is not contaminated with carbon, the carbon content does not exceed 1%. However, this product is also not suitable for the manufacture of metal parts from it and can only be used as a raw material in the steel production process. Therefore, the production of structural and other steel requires further enrichment of the obtained iron. Various gases are also used in the world to reduce iron, but the main and most common is natural gas.
