Production of Metals

Question 1

1

Q: What are the three main ingredients required for the production of cast iron and steel?

Objective 1: Describe the production processes for iron and steel

Answer 1

A: The three main ingredients are iron ore, coke, and limestone.

Question 2

2

Q: What are the two most common types of iron ore?

Objective 1: Describe the production processes for iron and steel

Answer 2

A: The two most common types are hematite (Fe₂O₃) and magnetite (Fe₃O₄), which are rich in iron content.

Question 3

3

Q: What is coke, and how is it produced?

Objective 1: Describe the production processes for iron and steel

Answer 3

A: Coke is a fuel with a high carbon content (98%). It is produced by heating coal to remove moisture and volatile compounds in a process called coking.

Question 4

4

Q: What is the role of limestone in iron and steel production?

Objective 1: Describe the production processes for iron and steel

Answer 4

A: Limestone acts as a flux in the blast furnace, helping to remove impurities by forming slag, which is skimmed off during the process.

Question 5

5

Q: Describe the blast furnace process for producing iron.

Objective 1: Describe the production processes for iron and steel

Answer 5

A: In a blast furnace, iron ore, coke, and limestone are added at the top, and hot air is blown through tuyeres at the bottom. The coke burns to form carbon monoxide, which reduces iron oxide to iron. Limestone helps remove impurities, forming slag.

Question 6

6

Q: What is pig iron, and what is its carbon content?

Objective 1: Describe the production processes for iron and steel

Answer 6

A: Pig iron is the product of the blast furnace, containing about 4% to 5% carbon. It is an intermediate product that must be refined further to make steel or cast iron.

Question 7

7

Q: What happens to pig iron after it leaves the blast furnace?

Objective 1: Describe the production processes for iron and steel

Answer 7

A: Pig iron can either be refined into cast iron in a cupola furnace or induction furnace, or it can be further processed into steel in a basic oxygen furnace or electric arc furnace.

Question 8

8

Q: How is cast iron produced from pig iron?

Objective 1: Describe the production processes for iron and steel

Answer 8

A: Cast iron is produced by melting pig iron and oxidizing it in a cupola furnace or induction furnace. The carbon content is adjusted, and impurities are removed to produce different types of cast iron.

Question 9

9

Q: What is the basic oxygen steel-making process (BOS)?

Objective 1: Describe the production processes for iron and steel

Answer 9

A: In the BOS process, a vessel is charged with molten pig iron and scrap steel. Oxygen is blown through a lance into the molten mixture, oxidizing carbon and other impurities. Lime-based fluxes are added to form slag, which removes impurities.

Question 10

10

Q: What is the electric arc furnace (EAF) process used for?

Objective 1: Describe the production processes for iron and steel

Answer 10

A: The EAF process is used to produce steel by melting scrap steel with electric arcs. This method is ideal for producing high-quality alloy steels and tool steels.

Question 11

11

Q: What is continuous casting in steel production?

Objective 1: Describe the production processes for iron and steel

Answer 11

A: Continuous casting is a process where molten steel is poured into a mold and solidified into billets, blooms, rounds, or slabs. This process is more efficient and produces higher-quality products than traditional ingot casting.

Question 12

12

Q: What are the key advantages of continuous casting over traditional casting methods?

Objective 1: Describe the production processes for iron and steel

Answer 12

A: Continuous casting improves yield, productivity, and cost efficiency. It also produces better-quality steel with fewer defects due to the continuous, automated process.

Question 13

1

Q: What is pig iron?

Objective 2: Describe the types of iron and steel

Answer 13

A: Pig iron is the product of the blast furnace with a carbon content of 4% to 5%. It must be refined further to make cast iron or steel.

Question 14

2

Q: What is cast iron, and what is its carbon content?

Objective 2: Describe the types of iron and steel

Answer 14

A: Cast iron is produced by refining pig iron and contains a carbon content ranging from 2% to 4.5%. It is commonly used for engine blocks, machinery frames, and flywheels.

Question 15

3

Q: What are the four general categories of cast iron?

Objective 2: Describe the types of iron and steel

Answer 15

1. Grey cast iron
2. White cast iron
3. Malleable cast iron
4. Ductile (nodular) cast iron

Question 16

4

What is grey cast iron, and why is it used?

Objective 2: Describe the types of iron and steel

Answer 16

A: Grey cast iron contains 2.5% to 4.0% carbon and is easy to cast into intricate shapes. It is used for engine blocks, tooling, and machinery frames due to its excellent wear resistance and ability to absorb vibrations.

Question 17

5

Q: What distinguishes white cast iron from other forms of cast iron?

Objective 2: Describe the types of iron and steel

Answer 17

A: White cast iron is extremely hard due to rapid cooling, and fractures appear silvery white. It is used in applications where high wear resistance is needed, such as in crushing and grinding equipment, but it is generally too brittle for other uses.

Question 18

6

Q: What is malleable cast iron, and how is it produced?

Objective 2: Describe the types of iron and steel

Answer 18

A: Malleable cast iron is produced by annealing white cast iron at temperatures of 815°C to 900°C (1500°F to 1650°F) for several days. This process gives the iron ductility, allowing it to bend before breaking, making it suitable for products like pipe fittings and swather knife guards.

Question 19

7

Q: What is ductile (nodular) cast iron, and what are its applications?

Objective 2: Describe the types of iron and steel

Answer 19

A: Ductile cast iron has nodules of graphite rather than flakes, giving it higher strength and ductility similar to steel. It is used for crankshafts, valves, and other structural components that require both strength and ductility.

Question 20

8

Q: What is steel, and how is it categorized?

Objective 2: Describe the types of iron and steel

Answer 20

A: Steel is an alloy of iron and carbon, typically with other elements such as manganese, silicon, sulfur, and phosphorus. Steel is categorized based on its carbon content into low, medium, high, and very high carbon steels.

Question 21

9

Q: What are the carbon content ranges for low, medium, high, and very high carbon steels?

Objective 2: Describe the types of iron and steel

Answer 21

• Low carbon steel: 0.05% to 0.30% carbon
• Medium carbon steel: 0.30% to 0.45% carbon
• High carbon steel: 0.45% to 0.75% carbon
• Very high carbon steel: 0.75% to 1.50% carbon

Question 22

10

Q: What is cast steel, and how is it classified?

Objective 2: Describe the types of iron and steel

Answer 22

A: Cast steel is steel that is poured into molds during the steel-making process. It is classified by its chemical composition as:
1. Carbon steel
2. Low alloy steel
3. Alloy steel
4. Stainless steel

Question 23

11

Q: What are the four types of steel based on the deoxidization process?

Objective 2: Describe the types of iron and steel

Answer 23

A: The four types of steel based on the deoxidization process are:
1. Rimmed steel
2. Capped steel
3. Semi-killed steel
4. Killed steel

Question 24

12

Q: What is rimmed steel, and what are its characteristics?

Objective 2: Describe the types of iron and steel

Answer 24

A: Rimmed steel is produced without deoxidizers, resulting in a layer of pure iron on the surface and gases concentrated at the core. It is relatively soft and inexpensive, used for core wire electrodes, bar stock, and structural steels.

Question 25

13

Q: What is capped steel, and how does it differ from rimmed steel?

Objective 2: Describe the types of iron and steel

Answer 25

A: Capped steel is similar to rimmed steel but is cast in a bottle-top mold with a metal cap, which slows cooling and reduces gas voids. It has fewer impurities and is used for strip and sheet steel.

Question 26

14

Q: What is semi-killed steel?

Objective 2: Describe the types of iron and steel

Answer 26

A: Semi-killed steel is partially deoxidized with small amounts of deoxidizers, resulting in uniform impurity distribution. It is often used for plate materials that require forming.

Question 27

15

Q: What is killed steel, and why is it considered high quality?

Objective 2: Describe the types of iron and steel

Answer 27

A: Killed steel is fully deoxidized with no gas formation, resulting in a cleaner steel without gas voids. It is used for structural steels and forgings that require uniformity and strength.