Extraction of Tin, Lead and Silver-Introduction, Occurrence, Position in the Periodic Table, Methods of Extraction, Practice Problems, FAQs

Metals have a myriad of uses in our life. Of them, universally traded metals are gold and silver. Silver is often referred to as a sister metal of gold. Similar to its sibling metal, silver has been used as a coinage metal, in jewellery, and even utensils since ancient times. Silver has been exchanged in almost every corner of the inhabited planet and has been a part of all major societies' economic and monetary systems. Nowadays, due to the versatile nature of silver, it is used drastically in industries. Fuel cells are made from thin nano silver foil. There are multiple uses for this precious metal.

However, this metal is precious because of its low abundance in nature. It has an abundance of 0.08 ppm in the Earth’s crust making it rare to come by. Both North and South America, which together account for more than half of the global total, have produced significant amounts of the metal through the mining process. Silver is an important element having versatile uses. Its journey from the Earth’s crust to an ornament on your body is fascinating and the process of extraction and purification is of paramount importance. Let us study a few of the extraction processes of silver, and a few other metals, and learn how it can be used profitably.

Table of Contents:

Tin

• What is Tin?
• Occurrence of Tin
• Position of Tin in the Periodic Table
• Extraction of Tin

Lead

• What is Lead?
• Position of Lead in the Periodic Table
• Extraction of Lead

Silver

• What is Silver?
• Occurrence of Silver
• Position of Silver in the Periodic Table
• Extraction of Silver

• Practice Problems
• Frequently Asked Questions-FAQs

What is Tin?

Tin is a chemical element with the atomic number 50 and the symbol (from Latin: stannum). Tin is a silvery metal with a high melting point. Tin is soft enough to cut with little force, and a tin bar may be bent with minimal effort by hand.

Occurrence of tin:

Tin is not found in nature in its native state. Cassiterite (), often known as tin stone, is the most important ore. The ore is commonly found with siliceous debris, iron tungstates (), andmanganese (). It can also be found alongsidecopper, iron, and zinc pyrites.

Position of tin in the periodic table:

Carbon (C), silicon (Si), germanium (Ge), tin (Sn), lead (Pb), and ununquadium make up Group IV A or 14 of the long version of theperiodic table. A family known as the carbon family is made up of these-six components. Because the last differentiating electron is accommodated in the shell, these are p-block elements. These elements belong to the IVth group because their valence shell has four electrons. This family's fourth element is tin.

Extraction of Tin:

The following steps are involved in extracting tin from cassiterite ore:

Concentration:

• Ore is crushed and pulverised for concentration.
• It's rinsed under runningwater to get rid of the lighter siliceous particles. An electromagnetic separator removes the iron tungstate.
• Sulphur and arsenic as and are removed from the ore by roasting it in an air current.

Smelting:

• The roasted ore is mixed with about a fifth of its mass in powdered anthracite (carbon) and a little amount of limestone during the smelting process (flux).
• When the tin oxide is converted to tin metal, the mixture is heated in a reverberatory furnace. The liquid metal from the furnace is drained.There are several imperfections in crude tin metal. Liquation and poling are used to further purify it.
• The raw metal is gradually heated on a reverberatory furnace's sloping hearth.
• Iron, copper, tungsten, and other metals are left behind when the tin metal flows down.
• Impurities such as and are oxidised as the molten metal is agitated with a green wood pole, and any tin oxide generated is reduced by the hydrocarbons in the wood.

What is Lead?

Pb (from the Latin plumbum) is a chemical element with atomic number 82 and a symbol . It's a type of heavy metal that's denser than most other metals. Lead is both soft and pliable, and has a low melting point. Lead is silvery with a trace of blue when freshly cut; when exposed to air, it tarnishes to a drab grey tin.

Occurrence of Lead:

Sulphide ores are the most common form of lead. Galena () is the name of the ore. It's commonly found alongside zinc blende, iron pyrites, and silver traces (up to 0.1 percent ). The lead concentration of galena fluctuates between 6 and 8%. Anglesite (), Cerussite (), and Lanarkite () are the other less important lead ores.

Position of Lead in the Periodic Table:

Carbon (C), silicon (Si), germanium (Ge), tin (Sn), and lead (Pb) make up Group IV A or 14 of the long version of the periodic table. A family known as the carbon family is made up of these-six components. Because the last differentiating electron is accommodated in the shell, these are p-block elements. These elements belong to the IVth group because their valence shell has four electrons. This family's fifth element is lead.

Extraction of Lead:

Galena ore is where most lead is extracted. Following are the steps in the extraction process:

(i) Concentration of ore
(ii) Reduction
(iii) Purification

(i) Concentration of ore:The ore is crushed and sieved before being used. For concentration, it is subjected to the froth flotation technique. The minerals are brought into a big tank of water that has been infused with pine oil. Compressed air is used to agitate the mixture. The froth is formed, which brings the particles to the surface with it, while the gangue settles at the bottom.

(ii) Reduction: There are two methods employed.

(a) For ores with high lead content, an air reduction process is used
(b) for ores with low lead content, a carbon reduction process is used

(a) Air reduction process:In the reverberatory furnace, the focused area is roasted. By regulating the air supply, the ore is partially oxidised.

The furnace's temperature is increased while the air supply is lowered. Galena ore with a higher concentration is added. forms lead metal by reacting with and .

As a result, roasting and smelting are carried out at separate temperatures in the same furnace. The lowest half of the furnace is drained of molten lead.

(b) Carbon reduction process:The ore is roasted in a sinter after being combined with lime. For charging and discharge, it is positioned on trunnions. A grating at the bottom and a hood at the top are included. The air is introduced via the grating and circulated throughout the charge using suction at the hood's top. Lead oxide is formed when is oxidised.

Lime has two functions:

1. It prevents the development of .
2. It prevents the formation of .

Crushed sintered coal is combined with coke and lime. It's fed into a tiny blast furnace (15-20 feet tall with a diameter of 3-5 feet). In the blast furnace, the following reactions take place:

The molten metal and slag are dragged out of the furnace.

(iii) Purification: Bi, Sb, Cu, Fe, Ag, and other impurities can be found in lead produced by either of the two procedures. The following procedures are used to remove these impurities:

• Softening process:The basic metals are removed during this procedure. A current of air is circulated as the impure metal is melted on the shallow hearth of the reverberatory furnace. The base metals oxidise and form scum on the molten mass's surface, which must be cleaned.
• Desilverisation: Parke's or Pattinson's processes are used to remove the impurities like silver from lead.
• Electrolytic refining:Bett's electrolytic process purifies desilverized lead further. It has an anode of impure lead and a cathode of pure lead, with an electrolyte of lead silico fluoride, . This comprises a small amount of gelatin and 8 to 12 % hydrofluosilicic acid (). Pure lead is deposited on the cathode by flowing current, while less electropositive impurities such as and others collect below the anode as anodic mud, while more electropositive impurities such as and others enter the solution.

What is Silver?

Silver is a chemical element with the atomic number 47 and the symbol (from the Latin Argentum, which means "bright" or "white"). It is a glossy, soft, white transition metal with the highest electrical conductivity, thermal conductivity, and reflectivity of any metal.

Occurrence of Silver:

• Silver is a rare element whose abundance in the crust is about 0.08ppm.
• It was, nevertheless, recognised in prehistoric times and utilised as a precious metal for its colour and beauty.
• Silver can be found in two different forms in nature: native state, and combined state.
• Its native state is a metallic state that is commonly associated with copper, gold, and platinum metals.
• Native silver has been discovered in a few locations across Canada, the United States, Mexico, and Peru.
• In a combined state, silver is mainly found in the form of ores.

Position of Silver in the Periodic Table:

On the periodic table, silver is the 47th element. It belongs to the fifth period and the eleventh group. Silver is classified as a transition metal because of its location. Even if you had no prior experience with silver, you could expect that it would act similarly to copper and gold. Silver, like other transition metals, has excellent thermal and electrical conductivity.

Extraction of Silver:

1. From argentite ore or cyanide process:The cyanide process is a modern method of silver extraction. The technique is also known as the MacArthur or Forrest Process. It is founded on two pillars.

• In the presence of air, silver compounds (or even free silver) dissolve in a sodium cyanide solution, generating the complex salt .
• By adding zinc to this complicated salt, silver is precipitated.

The steps in the procedure are as follows:

• Ore concentration: The ore is concentrated using the froth flotation technique. The ore is crushed and placed in a tank with water that has been mixed with pine oil and potassium ethyl xanthate. A powerful jet of air is used to stir the entire mixture. Ore particles and froth rise to the surface, while silicious impurities sink to the bottom.
• Cyanidation: In a ball mill, the concentrated ore is crushed to a very fine powder. The finely powdered ore is treated with a dilute solution of sodium cyanide (0.4 to 0.6 %) and a stream of air is blown through the entire mass. The silver in the ore progressively dissolves in the solution, forming sodium argentocyanide.The reaction described above is reversible. The blown-in air plays a critical role in eliminating sodium sulphide from the equilibrium mixture and causing the reaction to proceed in the appropriate direction.Filtration removes the soluble sodium argentocyanide. In a sodium cyanide solution, metallic silver and silver chloride (Horn silver) dissolve as well.

• Recovery of silver: By adding zinc powder in a finely divided state to the solution, silver is precipitated. Zinc enters the complex as a dark amorphous mass, while silver precipitates as a dark amorphous mass. formed as the product is a water-soluble compound.Filtration removes the precipitated silver, which is then dried and fused with potassium nitrate in a furnace crucible. The contaminants oxidise and rise to the surface as scum. When liquid silver cools, it forms a compact mass.
• Refining:Lead, copper, and gold are the most common contaminants. The following methods are used to get rid of them.Cupellation process:
• Cupel is a large oval dish constructed of bone ash or porous cement with a shallow hearth.
• A powerful current of air is blown over the impure silver as it is fused on the hearth of the cupellation furnace.
• Lead oxidises to lead oxide (PbO), which is blown away by the wind. Other contaminants oxidise as well, rising to the top and being removed as scum.
• The oxides may also be absorbed by the Cupel's lining.
• The appearance of the bright sparkling surface of the molten silver signals the end of the procedure.

Electrolytic process:

• The impure silver is made as anode and pure silver plate as a cathode.
• The electrolytic solution contains silver nitrate and 10% nitric acid. On passing, electric current silver ions start depositing on the cathode and the equivalent amount from the anode comes into the solution.
• In this way silver is transferred from anode to cathode. Copper goes into solution as copper nitrate while gold collects below the anode as anodic mud.

1. Amalgamation process: This is the old extraction procedure. In some nations, it is still in use. The sulphide ore is crushed and mixed with a cupric chloride solution to make slime.The product is then laced with mercury. Silver is liberated when silver chloride interacts with mercury.

Video link:https://www.youtube.com/watch?v=i54zcRBaFJo (Time-1:45-24:02)

Practice Problems:

Q1. ________________ is also recognised as Horn silver.

A. Lead bromide
B. Silver chloride
C. Silver bromide
D. Lead chloride

Answer: B

Solution: Silver chloride is also recognised as Horn silver. The mineral form of silver chloride is chlorargyrite (AgCl). It's also known as cerargyrite and horn silver when weathered by desert air. The removal of the original silver oxide layer results in the formation of silver chloride.

Q2. MacArthur process is used for the extraction of __________

A. Zinc
B. Silver
C. Iron
D. Aluminium

Answer: B

Solution:The cyanide process is a modern method of silver extraction. The technique is also known as the MacArthur or Forest Process. A cyanide solution is sprayed on a massive outdoor pile of ore, which drips through the rock over time.

Q3. _________is the process of using heat to remove a base metal from ore.

A. Concentration
B. Smelting
C. Roasting
D. Refining

Answer: B

Solution:The process of applying heat to ore in order to remove a base metal is known as smelting. It's an extractive metallurgy technique. Many metals, including silver, iron, copper, and other base metals, are extracted from their ores using this method.

Q4. Pattinson's process is used to remove impurities like _______

A. Lead
B. Copper
C. Aluminium
D. Silver

Answer: D

Solution: Hugh Lee Pattinson discovered and patented Pattinson's Process, or Pattinsonisation, as a process for extracting silver from lead in 1829.

The procedure is based on the fact that the lead with the least amount of silver hardens first after liquefaction, leaving the remaining liquid with a higher concentration of silver.

Frequently asked questions-FAQ

Q1. What factors influence the metal extraction procedure?

Solution:The following are some of the factors that influenced the extraction process:

• Mining cost of the ore
• Nature of the ore-pure, sulphides, oxides. etc
• Position of the metal in the electrochemical series
• Nature of the impurities
• The purity of the metal needed

Q2. Describe the solvent extraction technique in detail.

Solution: Due to the difference in solubility or distribution coefficient between these two immiscible (or scarcely soluble) solvents, a component transfers from one to the other during solvent extraction. When compared to other separation processes, it has a larger separation impact than chemical precipitation, as well as a higher degree of selectivity and faster mass transfer than the ion exchange strategy.

Q3.What is the impact of tin mining on the environment?

Solution: In addition, radioactive materials were released into the environment during tin mining. Erosion produced soil deterioration, which resulted in the loss of soil nutrients and organic matter, as well as damage to soil and crop qualities.

Q4. In India, where was tin originally found?

Solution: Tin in the form of Cassiterite is extracted from sediments deposited in streams in the Govindpur-Tongpal area of Dantewada district, Chhattisgarh. The stream sediments are painstakingly dug up using traditional equipment. Following the panning of these sediments, the lighter gangue minerals are separated, while the heavier fraction is recovered as Cassiterite. Chhattisgarh is India's only tin-producing state.

Related topics: