Gold Separation and Extraction Methods

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What is the main difference between haematite and magnetite?

Haematite is more easily reduced than magnetite (correct)
Magnetite is more abundant in nature than haematite
Haematite is more magnetic than magnetite
Magnetite contains more pure metal than haematite

What is the purpose of sintering the ore into lumps?

To prepare the ore for use in the blast furnace (correct)
To increase the iron content of the ore
To make the ore easier to transport
To remove impurities like silica and alumina

What is the role of limestone in the blast furnace?

It reacts with silica and alumina to form slag (correct)
It removes sulphur and phosphorus from the iron
It reduces the consumption of fuel
It increases the iron content of the ore

What is the purpose of ore dressing operations?

To remove impurities like silica and alumina (A) Signup and view all the answers

How can sulphur and phosphorus be removed from the iron?

By removing the slag from the blast furnace (C) Signup and view all the answers

What is the maximum allowable amount of sulphur and phosphorus in steel?

0.05% each (D) Signup and view all the answers

What is the primary benefit of preheating in steel production?

Enhancing the economy of steel production (C) Signup and view all the answers

What happens to the slag layer in the steel production process?

It floats over the heavier iron and is collected as waste (B) Signup and view all the answers

Which reaction occurs during the production of cast iron?

2Fe + SiO2 → 2FeO + Si (A) Signup and view all the answers

What is the primary source of aluminium for commercial extraction?

Bauxite ores (A) Signup and view all the answers

Where does most of the sulphur end up during steel production?

Mixed with calcium to form CaS and MnS (C) Signup and view all the answers

What is the function of preheating in steel production?

To increase the efficiency and reduce costs (C) Signup and view all the answers

What is the primary purpose of the ore dressing stage in aluminum extraction?

To separate the aluminum-containing mineral from waste materials (B) Signup and view all the answers

What is the chemical reaction that occurs during the chemical treatment of bauxite?

2NaOH + Al2O3 → Na2Al2O3 + H2O (A) Signup and view all the answers

What is the primary component of bauxite?

One or more aluminum hydroxide minerals (B) Signup and view all the answers

What is the role of cryolite in aluminum extraction?

It is used as a solvent for bauxite in the extraction process (C) Signup and view all the answers

What happens when cryolite is immersed in water?

It becomes invisible but does not dissolve (A) Signup and view all the answers

Which stage of aluminum extraction involves the electrolytic process?

Reduction of aluminum from aluminum oxide (C) Signup and view all the answers

What is the primary purpose of the flotation process in gold extraction?

To separate gold particles from other materials (C) Signup and view all the answers

In the cyanidation leaching process, what is the role of zinc dust?

To precipitate gold from the cyanide solution (C) Signup and view all the answers

Why is deaeration of the gold cyanide solution necessary before adding zinc at cold temperatures?

To remove dissolved oxygen, which can interfere with the precipitation reaction (D) Signup and view all the answers

Which of the following impurities can cause issues during cyanidation by consuming cyanide and oxygen unnecessarily?

Metal sulfides (D) Signup and view all the answers

How is the effect of iron sulfides, which can form problematic iron cyanide complexes, reduced during cyanidation?

By adding lead nitrate (D) Signup and view all the answers

What is the purpose of adding excess cyanide during the cyanidation process when copper is present?

To ensure sufficient cyanide is available for the dissolution of gold (C) Signup and view all the answers

What is the primary purpose of the concentration step in copper extraction?

To separate the copper mineral from the gangue (C) Signup and view all the answers

What is the purpose of the roasting step in copper extraction?

To remove excess sulfur from the ore (D) Signup and view all the answers

Which of the following is true about the copper ore used in commercial extraction?

It contains between 1.5-5% copper (A) Signup and view all the answers

Which step in the copper extraction process is used to convert copper sulfides to copper oxides?

Roasting (A) Signup and view all the answers

What is the approximate copper content (in percentage) after the smelting and matte conversion step?

98% (B) Signup and view all the answers

Which step in the copper extraction process is used to achieve a copper purity of 99.9%?

Electrolytic conversion (A) Signup and view all the answers