Extraction of Metals – Concentration, Reduction and Refining

Earth is a primary source of metals, most of which are available in the crust mainly. The nature in which the metals types are found depends upon the reactivity series. Low reactive metals are usually found in the Free State. Two examples of such metals are gold and platinum. 

Additionally, a few metal types occur in both combined and free states. Copper and silver are two types of such metal. From certain minerals, ores can be extracted; this process is known as the extraction of metals or metallurgy. Here, you will learn more about this process and everything involved. 

Metal extraction Process 

During metal extraction, many steps and factors are in play that determine the quality of the final product. These include the types of ore, its state of reactivity, climatic conditions, and the type of impurities present in the ore. The examination of these factors would help you decide which procedure and type would help to extract the metal. 

The type of soil found in the area where the minerals and ore are present may also have an effect on the complete process. Hence the extraction of the metals from ores does not only need a correct procedure but also requires friendly climatic and natural support. 

Steps involved in the process:

•  Enrichment:

 After mining, when the ore is found, it contains various types of impurities. Soil, sand, rocks, and various such impurities are fully removed during this process. These impurities are technically known as gangue. This is the first and most important step of this procedure. 

According to the area and the metal type, these impurities may be less or more. If the removal of the gangue in this stage occurs properly, it ensures good metal extraction from ore. The removal of impurities also primarily depends upon the physical and chemical properties of ore as well as the gangue. Some of the methods used in the concentration of ores are:

 Hand collection– Ores are primarily collected, and the extra mud and sand are removed. After this process, the water stream washes out the ore and cleans it. This produces completely gangue-free ore, which people can use. 

• Hydraulic wash- This process is also known as levigation. In this procedure, ores are categorically divided based on the specific gravities of the ores and the impurities.
• Separation by electromagnet: This process is one of the simplest and highly usable processes at present. This procedure is most commonly used to extract magnetic ore from impurities. Two moving rollers operate, on which operators place the crushed ore. Here, the magnetic ore remains, and the rest of the gangue passes away. This process is highly used in the extraction of iron ore and is one of the fastest procedure types for this. 

• Froth Flotation: Sulfide ores are the major part of this type of procedure. Some of the ores have high contamination of multiple chemical compounds. The above-mentioned procedure may result in adverse effects on humans. Plus, it can lower the quality of the ore. The Froth Flotation process, on the other hand, involves the wetting characteristics of the ore. Under this procedure, highly concentrated chemicals are used to clean the gangue. The pine oil, which acts as the frother, is mixed with metal sulfide and ethyl xanthate. In this mixture, powdered ore is also mixed. The ore particles combine with the froth and come up. This is later extracted, and the gangue is settled down underwater.

• Liquation- This procedure undergoes a certain type of ore that is compatible with high melting temperatures. Certain types of impurities neither can be washed nor can be dissolved. Hence this type of gangue needs to be melted and removed from the ore. In this procedure, easily fusible minerals are kept on a high melting point to remove the gangue.

• Leaching- This is also a chemical-based procedure used for the extraction of metals from ore. In this procedure, the chemical solution dissolves the ore, and the gangue remains insoluble. 

  Extraction:

After the removal of the impurities from the ore, now it’s time for the extraction of metals from the concentrated ore. The metal extraction is highly dependable on the nature of the ore. Different types of metals work differently with various processes to create a smooth final product. The metal and its ores need a different type of treatment with proper care based on their reacting properties. There are three kinds of reacting metals:

• Low reacting metals: These metals are free to state metals and less reactive than other options. The extraction of metals with such property is very easy and cost-effective. These low-reacting metals can be extracted just by heating. Through Heating their oxides are reduced, and the metals are extracted. Some examples of such metals are Gold(Au), Mercury(Hg), etc.

• Average reacting metals: These types of metals are found in the form of sulfide and carbonates. These metals react in the medium range and need some more attention as compared to the low reactive metals. The process includes two steps: heating oxides and heating carbonates. In this category, extraction of metals involves heating oxide ores and carbonate ores and conversion to oxide ores. The process of roasting is decided as per the requirement, nature, and capacity of ore. Some of the examples of such metals are Tin (Tn), Iron (Fe), Lead (Pb), etc. The extraction of iron ore is the most famous among all these metals and procedures.

• High reacting metals: Some metals react very highly throughout the extraction procedure. The properties of such metals and the area where it is found determine why they react a certain way. The process in which these types of metals are extracted involves the use of extreme temperatures. The electrolytes are one of the most common processes for extracting such high reacting metals. The extraction of metals from the ore in this type of procedure goes through the high electric current, which melts their oxides, and extraction is complete. 

  Refining:

 By all the above processes, the metal is now obtained. But the metal is a crude metal; hence a refining procedure is necessary to get pure metal. The extraction of metal also needs proper refining to remove the impurities which a metal absorbs through all the chemical-based procedures. An electronic refining apparatus is used for the refining procedure, which provides 99.9% pure metal.

Conclusion:

The extraction of metals is a long procedure that requires the study and knowledge of metals. Metals are natural products, and each type reacts in different manners. Hence, it is necessary to keep an eye on the reaction of each metal and how they react to each procedure. This way, you can choose the right procedure and safely conduct it. Plus, the extraction of metals from the ores gives the natural form of metals. However, the entire process is complex, so handle all steps with proper care and caution.