Occurrence and Extraction of Metals

Metals are minerals or substances that occur naturally beneath the Earth’s surface. The majority of metals are lustrous or glossy. Metals are inorganic, which implies they were formed from non-living substances. Metals are typically found in the form of metal ores, which are linked to one another and to a variety of other elements. They are also found naturally in rocks washed by surface and groundwater, as well as in air dust.

Properties of metals

1. All metals are good heat and electrical conductors. Metals are used in cooking utensils and irons because they conduct heat well.
2. The capacity of a substance to be stretched into a wire is known as ductility. This ability enables metals to be pulled into wires, which, when combined with their resilience, find usage as cable wires and for soldering. Metals are said to be ductile because they can be pulled into wires.
3. The feature of substances that permits them to be beaten into flat sheets is known as malleability. Aluminium sheets are used in the production of airplanes because of their lightweight and strength. Other metal sheets are used in the motor industry, to make utensils, and so on. As a result, metals are malleable.
4. Metals are sonorous because when struck with another hard object, they generate a loud or ringing sound.
5. All metals have a shiny appearance by nature, however certain metals can also be polished to have a shiny appearance.

Occurrence of metals

The earth’s crust is rich in metals and contains metals. Metals are most usually found in their combined state in nature, however, they can also be found in their free state. A native metal is a metal that exists naturally in its pure form or as an alloy. Most metals are unable to withstand natural processes like oxidation and corrosion. As a result, only non-reactive metals like gold, silver, and platinum have been identified in their native or free state. Most metals are obtained as compounds, which must be filtered to remove contaminants before they can be used in various applications. The extraction of metals from ores is referred to as metallurgy, and these naturally occurring metal complexes are referred to as minerals. Mining is the most common way of extracting metals from the earth.

• Ores

Minerals are all ores, but not all ores are minerals. Ores are minerals that contain metals. Different metals are extracted using various processes. For example, common metals such as iron are smelted with carbon as a reducing agent. Few metals, such as aluminium and sodium, lack a commercially viable reducing agent and must be removed through electrolysis. Sulfide ores are not immediately converted to metal, but rather roasted in air to convert them to oxides.

• Gangue

The gangue or matrix is an undesired, commercially ineffective mixture of rocky, earthy, or sandy elements found with the ores. These are the contaminants that are removed at a later stage.

• Alloys

The term ‘alloy’ refers to a material created by the combining of two or more metals. Alloys can also be created by combining metals and other elements. Alloy qualities are frequently substantially different from the properties of their constituent components. When compared to pure metals, alloys frequently offer higher strength and hardness. Red gold is an example of an alloy, which is created by combining copper with gold. Another notable gold alloy is white gold, which is created by combining silver and gold.

Metallic bonding is common in alloys. The elements of an alloy are measured in terms of their mass percentage in practically all practical applications. However, the components of alloys are quantified in terms of their atomic fractions in some scientific research. It is vital to note that alloys are divided into two types based on the atomic arrangements in their respective lattices: substitutional alloys and interstitial alloys. Furthermore, alloys can be classed based on the total number of phases present. Homogeneous alloys, for example, have only one phase, whereas heterogeneous alloys have two or more phases.

Extraction of Metals

The presence of metals in nature is simply one aspect of the process; these metals must also be extracted. Metallurgy is the extraction of metals. The concentration of ores is the first step in the extraction of metals.

• Concentration of Ores

The ores include many contaminants that must be purified. Concentration is the process of removing contaminants from ores. Gravity separation, hydraulic washings, and froth flotation are all methods of concentration.

• Metals of high reactivity level

Metals at the top of the reactivity scale, such as sodium, magnesium, calcium, and so on, cannot be produced from their compounds by heating with carbon because they are too reactive. Such metals are obtained through electrolytic reduction.

• Metals of medium reactivity level

Metals in the center of the reactivity series, such as lead, zinc, copper, and so on, are moderately reactive and are commonly found as carbonates or sulfides. Heat is used to transform sulfide ores into oxides in the presence of abundant air. Roasting is the process by which sulfur impurities escape as gas. Carbonate ores are calcined to remove impurities such as carbonate and moisture. Calcination is a process that converts ore into oxides by rapidly heating it in the presence of excess air.

• Metals of low reactivity level

Metals with low reactivity are put at the bottom of the reactivity series. Heating alone can reduce these metals to metals. For example, heating is used to extract mercury from its mineral, cinnabar (HgS). Heating can also be used to extract copper from its sulfide ore (Cu₂S).

Sample Problems

Question 1: What’s are metals?

Solution:

In chemistry, a metal is an element that rapidly produces positive ions (cations) and has metallic connections. Metals are sometimes depicted as a lattice of positive ions by a cloud of delocalized electrons.

Question 2:  What is the hardest metal in the world?

Solution:

Tungsten has the highest tensile strength of any natural metal, but it is fragile and looks to shatter down on contact.

Question 3: What happens if you touch calcium metal?

Solution: 

Calcium will react with water or moisture that causes heat. When calcium metal comes into touch with moisture in the eyes, body, or respiratory tract, it can produce severe corrosive irritation.

Question 4: What is the softest metal?

Solution: 

Caesium is thought to be the softest metal, whereas lead is thought to be one of the softest metals. Mercury is a liquid at ambient temperature. At body temperature, gallium is a liquid, while at room temperature, it is a solid (if soft).

Question 5: What is gangue?

Solution:

The gangue or matrix is an undesired, commercially ineffective mixture of rocky, earthy, or sandy elements found with the ores. These are the contaminants that are removed at a later stage.