Why this chapter matters for UPSC: This chapter is the gateway to India's mining and minerals policy. Every question about steel (SAIL, Tata Steel, India's 2nd-largest producer status), aluminium (Niyamgiri Hills controversy, NALCO, tribal rights under PESA and FRA), copper (Khetri mines, HCL), and the emerging critical minerals agenda (lithium, REEs for EVs and clean energy) traces directly to the metallurgical chemistry here. The reactivity series explains why some metals must be extracted by electrolysis (aluminium — energy-intensive), why gold is found natively, and why corrosion is selective.

PART 1 — Quick Reference Tables

Metals vs Non-metals: Key Property Comparison

Property Metals Non-metals
Physical state (at room temp) Mostly solids (exception: Hg is liquid) Solids, liquids (Br), or gases
Lustre Shiny metallic lustre Dull (exception: iodine has slight lustre)
Hardness Generally hard (exception: Na, K are soft — cut with knife) Generally brittle (exception: diamond is hardest natural substance)
Malleability Malleable (beaten into sheets) — gold is most malleable Brittle; break or crumble when hammered
Ductility Ductile (drawn into wires) — silver is most ductile Not ductile
Conductivity Good conductors of heat and electricity — silver is best; copper most used Poor conductors (exception: graphite conducts electricity)
Melting/Boiling points Generally high (exception: Ga melts at 29.7°C; Hg liquid at RT) Generally low (exception: carbon/diamond — ~3550°C)
Density Generally high Generally low
Sonority Sonorous — rings when struck (bells = bell metal Cu+Sn) Not sonorous

Reactivity Series (Electrochemical Series)

Group Metals (Most → Least Reactive) Key Behaviour Extraction Method
Very high K, Na, Ca, Mg React violently with cold water; can't exist free in nature Electrolysis (very energy-intensive)
High Al Reacts with steam; self-passivating (Al₂O₃ layer) Electrolysis of molten Al₂O₃ (Hall-Héroult process)
Moderate Zn, Fe, Ni, Sn, Pb React with dilute acids; iron reacts slowly with steam Carbon/CO reduction (blast furnace)
Below H Cu, Hg Don't react with dilute acids; can be displaced by H₂ Reduction (mild heating of ore); displacement
Least Ag, Au, Pt Found as native metals; extremely stable Simple physical separation; panning for gold

India's Key Metal Ores, Locations, and Companies

Metal Main Ore Key Indian Locations Public Sector Company Private Sector
Iron Haematite (Fe₂O₃), Magnetite Jharkhand, Odisha, Chhattisgarh, Goa SAIL, RINL (Vizag) Tata Steel, JSW Steel, Essar
Aluminium Bauxite (Al₂O₃·nH₂O) Odisha (largest), Jharkhand, Gujarat, Maharashtra NALCO, BALCO (now Vedanta) Hindalco (Aditya Birla)
Copper Chalcopyrite (CuFeS₂) Rajasthan (Khetri), Jharkhand (Singhbhum), MP Hindustan Copper Ltd (HCL) —
Zinc Sphalerite (ZnS) Rajasthan (Zawar, Rampura-Agucha — world's 2nd largest zinc mine) HZL (Hindustan Zinc Ltd, now Vedanta) Vedanta
Gold Native gold; gold-bearing quartz Karnataka (Kolar Gold Fields — depleted; Hutti mines active) Hutti Gold Mines Ltd —
Rare Earths Monazite (beach/river sands) Kerala, Tamil Nadu, Odisha coasts Indian Rare Earths Ltd (IREL) —

PART 2 — Detailed Notes

1. Properties of Metals

Physical properties: Metals are generally solids at room temperature — the notable exception being mercury (Hg), which is liquid. Gallium (Ga) melts at just 29.7°C (it literally melts on your palm). All other metals are solid.

Gold is the most malleable metal — a single gram of gold can be beaten into a sheet of approximately 1 square metre (used in gold leaf art, gilding, and gold leaf in Ayurvedic formulations). Silver is the most ductile metal — 1 gram can be drawn into 2 km of wire.

Conductivity: Silver is the best conductor of both heat and electricity, but copper is used most widely in electrical wiring because silver is too expensive. Aluminium is used in high-tension power transmission lines (lighter than copper despite slightly lower conductivity — a critical engineering trade-off).

Chemical properties: Metals form basic oxides (e.g., CuO, Fe₂O₃) and react with acids to produce hydrogen gas (except Cu, Hg, Ag, Au, Pt which are below hydrogen in the reactivity series). The more reactive the metal, the more vigorously it reacts with air, water, and acids.

Key Term

Amphoteric metals: Aluminium and zinc react with both acids and strong bases — they are amphoteric. This means Al dissolves in dilute HCl (acid) AND in NaOH solution (base), producing hydrogen in both cases. This property is important in chemical analysis and in the aluminium recycling process.

2. Non-metals

Non-metals occupy the upper-right of the periodic table (with the exception of hydrogen). Most are gases at room temperature (O₂, N₂, Cl₂, F₂, noble gases). The non-metallic solid forms of carbon — diamond and graphite — have dramatically contrasting properties:

  • Diamond: Covalent network solid, each carbon bonded to 4 others — hardest natural substance (10 on Mohs scale), electrical insulator, used in cutting tools, drill bits, abrasives
  • Graphite: Layered structure, each carbon bonded to 3 others in flat sheets — slippery (layers slide), good electrical conductor (delocalised π electrons), used in pencil "leads," electrodes, and high-temperature lubricants

Phosphorus exists in multiple allotropic forms: white phosphorus (highly reactive, toxic, spontaneously inflammable in air — used in chemical weapons, prohibited under CWC) and red phosphorus (stable, used in match boxes — the striking surface).

Sulphur occurs naturally near volcanic vents and in crude oil/natural gas (as H₂S). The Claus process converts H₂S from petroleum refining into elemental sulphur, which is then used to make H₂SO₄.

3. Occurrence and Extraction of Metals

Terminology:

  • Mineral: Any naturally occurring substance in the earth's crust (may or may not contain a useful metal)
  • Ore: A mineral from which a metal can be profitably extracted; ores are minerals, not all minerals are ores
  • Gangue: Impurities mixed with the ore; must be removed during extraction

Extraction flow:

  1. Concentration/Enrichment — Remove gangue from ore: froth flotation (sulphide ores; gangue wets with water, ore floats with oil froth), gravity separation (denser ore sinks; e.g., tin ore), magnetic separation (magnetite Fe₃O₄ separated from non-magnetic gangue)

  2. Conversion to oxide — Roasting (heat sulphide ore in air → metal oxide: 2ZnS + 3O₂ → 2ZnO + 2SO₂); Calcination (heat carbonate ore: ZnCO₃ → ZnO + CO₂)

  3. Reduction to metal — Method depends on position in reactivity series:

    • Moderate/low reactivity: carbon/CO reduction in blast furnace (Fe₂O₃ + 3CO → 2Fe + 3CO₂)
    • High reactivity (Al, Mg, Na, K): electrolytic reduction of molten oxide/chloride

  4. Refining — Electrolytic refining gives highest purity metal (99.9%+ copper): crude copper (impure) is anode; pure copper sheet is cathode; CuSO₄ solution is electrolyte — copper dissolves from anode and deposits on cathode; impurities (silver, gold, platinum) sink as "anode mud" and are separately recovered

UPSC Connect

UPSC GS3 — Niyamgiri Hills and Aluminium Extraction: The Niyamgiri Hills in Odisha contain one of India's largest bauxite deposits (~73 MT), overlying a sacred hill of the Kondh tribal community who call it "Niyam Raja" (their god). Vedanta Resources sought to mine it for its aluminium refinery at Lanjigarh. The Supreme Court in 2013 (Orissa Mining Corporation vs MoEF) directed gram sabhas of the affected villages to decide — in a landmark exercise of democratic consent, all 12 gram sabhas rejected the mining. This case established the importance of Free, Prior, and Informed Consent (FPIC) of tribal communities under FRA 2006 and PESA 1996 for mining on forest/tribal land.

4. Alloys

Alloys are homogeneous mixtures of metals (or metals with non-metals) designed to improve properties. Pure metals are often too soft, too reactive, or too low-melting for engineering applications.

Alloy Composition Key Properties Applications
Stainless steel Fe + 10–18% Cr + 8% Ni Corrosion-resistant; hard; non-magnetic variants Cutlery, surgical instruments, food industry, architecture
Brass Cu + 20–45% Zn More malleable than Cu; corrosion-resistant Musical instruments, fittings, coins (old 5-paisa)
Bronze Cu + 10% Sn (+ sometimes Al, Mn) Harder than Cu; resists saltwater corrosion Bells (bell metal), statues, coins, bearings
Duralumin Al + 4% Cu + Mg + Mn Strong, light (density ~2.8 g/cm³), corrosion-resistant Aircraft bodies, spacecraft, military vehicles
Solder Pb (37%) + Sn (63%) — traditional Low melting point; bonds metals Traditional electronics soldering (being replaced by Pb-free solder: Sn-Ag-Cu)
Amalgam Hg + Ag/Sn/Cu/Zn Soft when mixed, hardens in minutes Dental fillings (being phased out due to Hg toxicity; Minamata Convention)
UPSC Connect

UPSC GS3 — Critical Minerals and Clean Energy Transition: The shift to clean energy (EVs, wind turbines, solar panels) has created a new category of strategic resources: critical minerals. Unlike iron or copper, many of these are rare, geographically concentrated, and lack developed supply chains.

India's Critical Mineral Mission (2023) identified 30 critical minerals: lithium, cobalt, nickel, graphite, REEs, titanium, tungsten, vanadium, and others. Key concerns:

  • China's dominance: China controls ~60% of global REE production and ~85% of processing. China's 2023 export controls on gallium and germanium (semiconductor materials) demonstrated the geopolitical risk.
  • India's discoveries: A geological survey in 2023 identified lithium deposits in Reasi district, Jammu and Kashmir (~5.9 million tonnes — one of the world's largest deposits; confirmation and commercial viability studies ongoing). Lithium is critical for EV batteries (lithium-ion).
  • Khanij Bidesh India Ltd (KABIL): A joint venture of NALCO, HCL, and MECL to acquire critical mineral assets overseas (Australia, Argentina, Chile — the "Lithium Triangle" for Li, cobalt in DRC, REEs).
  • Deep sea mining: India has a pioneering deep sea programme. The Samudrayaan mission (launched 2023, 6,000 m depth in the Central Indian Ocean) explores polymetallic nodules (containing Mn, Fe, Ni, Co, Cu) and seafloor massive sulphides (containing Cu, Zn, Pb). India has exploration rights to a 75,000 sq km site in the Central Indian Ocean (ISBA allotment). Deep sea mining raises serious environmental concerns — disturbance of benthic ecosystems, sediment plumes, carbon release from deep-sea sediments.

5. Metal Recycling and E-waste

Urban mining — recovering metals from electronic waste — is increasingly important as primary ore grades decline. E-waste contains gold, silver, palladium, copper, and REEs at concentrations many times higher than primary ores. India is the world's 3rd largest e-waste generator (~3.2 million tonnes/year). The E-Waste Management Rules 2022 (revised from 2016) impose Extended Producer Responsibility (EPR) on manufacturers — they must take back and recycle their products at end-of-life. Formalising the informal e-waste recycling sector (which employs ~500,000 workers, mostly in unsafe conditions) is a key challenge.

Exam Strategy

Prelims traps:

  • Mercury is the only metal that is liquid at room temperature. Gallium melts at ~30°C (near room temperature) but is usually counted as a solid metal at standard room temperature (25°C).
  • Graphite is a non-metal that conducts electricity — a common exception question. It conducts because of delocalised electrons in the graphene layers.
  • Aluminium forms a protective oxide layer (Al₂O₃) that prevents further corrosion — this is why aluminium household items don't "rust" visibly despite being reactive.
  • Copper is below hydrogen in the reactivity series — it does NOT react with dilute H₂SO₄ or HCl. It reacts with hot concentrated H₂SO₄ and HNO₃.
  • In electrolytic refining, the impure metal is the anode (dissolves) and pure metal is the cathode (deposits) — frequently asked question.
  • The anode mud in copper refining contains silver, gold, and platinum — this is how those precious metals are recovered as by-products.

Mains frameworks:

  • Critical minerals → clean energy transition → China's supply chain dominance → India's Critical Mineral Mission → KABIL → strategic partnerships (Quad, I2U2)
  • Niyamgiri → FRA 2006 → gram sabha consent → FPIC → tribal rights vs development → SC jurisprudence
  • Deep sea mining → Samudrayaan → polymetallic nodules → ISA regulations → environmental concerns → blue economy

Previous Year Questions

Prelims:

  1. With reference to the "Critical Mineral Mission" of India, which of the following minerals is/are included?
    (a) Lithium and Cobalt only
    (b) Rare Earth Elements only
    (c) Lithium, Cobalt and Nickel only
    (d) Lithium, Cobalt, Nickel, Rare Earth Elements, and other strategic minerals

  2. The process of electrolytic refining is used to obtain very pure metals. In this process, the impure metal forms the:
    (a) Anode
    (b) Cathode
    (c) Electrolyte
    (d) Both anode and cathode alternately

Mains:

  1. What are critical minerals? Discuss the importance of critical minerals for India's energy transition and the steps taken to secure their supply. (CSE Mains 2023, GS Paper 3, 15 marks)

  2. Discuss the significance of deep-sea mining for India's mineral security. What are the environmental concerns and how is India approaching this frontier? (CSE Mains 2022, GS Paper 3, 10 marks)