Main Transition Metals - Iron Ore and Alloys

Comprehensive practice flashcards covering iron extraction stages, ore properties, chemical reactions in reduction furnaces, and alloy classifications based on lecture notes.

What position does iron hold in elemental abundance within the Earth's crust, and which elements precede it?

Iron is the $4\text{th}$ most abundant element in the Earth's crust, following oxygen, silicon, and aluminum.

What percentage of the Earth's crust by mass is made of iron, and what is its density?

Iron forms $5.1\%$ of the Earth's crust by mass, and its density is $7.87\,\text{gm/cm}^3$.

In what form and concentration is pure iron found in meteorites?

Pure form of iron is found in meteorites at $90\%$.

What are the chemical formula, chemical name, iron percentage, and color of Siderite?

Chemical Formula: $\text{FeCO}_3$; Chemical Name: Iron II Carbonate; Iron Percentage: $30\text{--}42\%$; Color: Yellowish grey.

What are the chemical formula, chemical name, iron percentage, and color of Hematite?

Chemical Formula: $\text{Fe}_2\text{O}_3$; Chemical Name: Iron III Oxide; Iron Percentage: $50\text{--}60\%$; Color: Blood red.

What are the chemical formula, chemical name, iron percentage, and color of Limonite?

Chemical Formula: $2\text{Fe}_2\text{O}_3 \cdot 3\text{H}_2\text{O}$; Chemical Name: Hydrated Iron III Oxide; Iron Percentage: $20\text{--}60\%$; Color: Yellow.

What are the chemical formula, chemical name, iron percentage, and color of Magnetite?

Chemical Formula: $\text{Fe}_3\text{O}_4$; Chemical Name: Mixed iron Oxide; Iron Percentage: $45\text{--}70\%$; Color: Black.

What are the three main stages of Iron Extraction?

A. Ore Dressing, B. Reduction, C. Production.

What is Crushing in ore dressing, and how does it affect the mass and iron percentage of the ore?

Crushing is a physical and mechanical process that decreases the size of the ore without changing the percentage of iron or the mass of the ore (both remain constant).

What is Sintering in ore dressing, and what is its main objective?

Sintering is a physical and mechanical process that treats the huge amount of fine small particles resulting from crushing and furnace cleaning to obtain similar, homogeneous larger particles for use in the high furnace.

What is Concentration in ore dressing, what processes are used, and how are impurities removed?

Concentration is a physical process that increases the percentage of iron by removing impurities in solid form using Magnetic Separation, Electric Separation, or Surface Tension. Mass of the ore decreases while iron percentage increases.

What is Roasting in ore dressing, and how are impurities removed?

Roasting is a chemical process that aims to increase the percentage of iron by removing impurities in gas form through strong heating in air. It changes any iron ore into Hematite ore.

What equation represents the drying of Limonite during roasting?

$$2\text{Fe}_2\text{O}_3 \cdot 3\text{H}_2\text{O}_{(s)} \xrightarrow{\Delta} 2\text{Fe}_2\text{O}_3 + 3\text{H}_2\text{O}_{(v)}$$

What chemical equations describe the oxidation of sulfur and phosphorus impurities during roasting?

Sulfur: $\text{S}_{(s)} + \text{O}_2 \xrightarrow{\Delta} \text{SO}_{2(g)}$; Phosphorus: $4\text{P}_{(s)} + 5\text{O}_2 \xrightarrow{\Delta} 2\text{P}_2\text{O}_{5(g)}$

What is the reducing agent in a Blast Furnace, what is its source, and what is the reduction equation?

Reducing agent: Carbon Monoxide ($\text{CO}$); Source: Coke ($\text{C}$); Reduction equation: $\text{Fe}_2\text{O}_{3(s)} + 3\text{CO}_{(g)} \xrightarrow{> 700\,^\circ\text{C}} 2\text{Fe}_{(s)} + 3\text{CO}_{2(g)}$

What is the reducing agent in a Midrex Furnace, what is its source, and what is the reduction equation?

Reducing agent: Water Gas ($\text{CO} + \text{H}_2$); Source: Methane ($\text{CH}_4$); Reduction equation: $2\text{Fe}_2\text{O}_{3(s)} + 3\text{CO}_{(g)} + 3\text{H}_{2(g)} \xrightarrow{\Delta} 4\text{Fe}_{(s)} + 3\text{CO}_{2(g)} + 3\text{H}_2\text{O}_{(g)}$

Why does pure iron have no economic importance?

Pure iron has no economic importance because it is a soft metal, has a high density, and has a high melting/boiling point ($1538\,^\circ\text{C}$).

What three types of furnaces are used during the production stage to form alloys?

1. Open Hearth Furnace
2. Electric Furnace
3. Oxygen Convertor

What is an Interstitial alloy, and what physical properties does it change?

An alloy in which atoms of an element with a smaller size are introduced into the intermolecular spaces of the crystal lattice of the pure metal to increase its hardness and change properties like malleability, ductility, melting point, electric conductivity, and magnetic property (e.g., steel: iron and carbon).

What is a Substitutional alloy, and what are its requirements?

An alloy in which some atoms of pure metal are replaced by atoms of another metal of the same crystalline structure, almost similar radius, and identical chemical properties (e.g., Ferrochrome, ferromanganese, gold and copper, ferronickel, brass).

What are Inter-metallic alloys, and what rules do they follow regarding mixing and valency?

Alloys formed by chemical combination (reacting, not mixing) between elements from different groups to form a new compound with new properties. They disobey standard valency laws (e.g., Duralumin $\text{Ni}_3\text{Al}$, lead-gold $\text{Au}_2\text{Pb}$, Cementite $\text{Fe}_3\text{C}$).

Which two alloy types are depicted in this diagram?

The left structure represents a Substitutional Alloy (atoms of similar radius replacing host atoms), and the right structure represents an Interstitial Alloy (smaller radius atoms filling intermolecular spaces).