21.1.1 Metallurgical Processes

Question 1

Metallurgical Processes

Answer 1

• Metals are malleable, ductile, display electrical conductivity, and thermal conductivity.
• Metallurgy is the study of metals and their extraction from their naturally occurring states.
• Metals are purified from ores through preliminary treatment, reduction, and refining.

Question 2

note

Answer 2

• Metals are malleable—they can be pounded into thin sheets.
• Metals are ductile—they can be pulled into wires.
• Metals conduct electricity and heat.
• Metallurgy is the study of metals and their extraction from their naturally occurring states. Except for a very few exceptions, metals are not found in their elemental state in nature but rather in the form of minerals.
• The elemental metals must be purified from these mineral ores.
• Alloys are mixtures made from two or more different metals.
• Metals are purified from ores through preliminary treatment, reduction and purification.
• Three types of preliminary treatments are flotation, roasting, and the Bayer process.
• In flotation, the ore is mixed with water and a surfactant. Air is bubbled through this mixture to separate the ore from dirt and rock (gangue).
• In roasting, sulfate ores are heated with oxygen gas, producing a metal oxide and sulfur dioxide gas.
• The Bayer process is part of the extraction of aluminum from bauxite. Bauxite reacts with hydroxide ion, facilitating the separation of aluminum from iron and silicon impurities.

Question 3

note 2

Answer 3

• In the reduction step, metal oxides are reduced by reaction with carbon monoxide, carbon, or hydrogen.
• This step is performed at relatively high temperatures (the illustration shows a “blast furnace”), and yields the metals in their elemental forms.
• The final step is the refining of the remaining mixtures of metals. In general, the impurities remaining after the
  reduction step are metals from the same group on the periodic table as the reduced metal.
• These impurities can be removed by distillation or
  electrolysis.

Question 4

Which of the following would be a “difficult to remove” impurity if found mixed with molybdenum?

Answer 4

Chromium

Question 5

What is a man-made mixture of two different metals called?

Answer 5

alloy

Question 6

Which of these impurities would be difficult to remove from nickel?

Answer 6

platinum

Question 7

Which metal is obtained from the ore bauxite?

Answer 7

Aluminum

Question 8

Which of the following is not an alloy?

Answer 8

iron

Question 9

Which of the following represents the reduction step in processing?

Answer 9

ZnO + C → Zn + CO

Question 10

Which of the following is a physical method for separating ore?

Answer 10

flotation

Question 11

Which of the following is not a refining method?

Answer 11

Distilling

Question 12

Which of the following is NOT a property of a metal?

Answer 12

Solid at standard temperature

Question 13

Which of the following is not one of the original seven metals known to the ancients?

Answer 13

Aluminum