Question

Which of the following process is used in the extractive metallurgy of magnesium? (a) Self reduction (b) Fused salt electrolysis (c) Thermite reduction (d) Aqueous solution electrolysis

Short answer

Fused salt electrolysis is used in the extractive metallurgy of magnesium.

Step-by-step solution

Understand the Question

The question asks us to identify the process used in the extractive metallurgy of magnesium from a list of four options. Extractive metallurgy of an element involves obtaining it in its metal form.

Analyze the Options

Evaluate each method listed: - Self reduction is a method where the ore is reduced without any external reducing agent. - Fused salt electrolysis involves electrolyzing a molten salt. - Thermite reduction uses aluminum powder or another reducing agent to extract metals from their oxides. - Aqueous solution electrolysis involves dissolving salts in water and then electrolyzing them.

Identify the Correct Method for Magnesium

Magnesium is typically extracted by electrolysis of molten magnesium chloride, known as fused salt electrolysis. This is because magnesium has a very high melting point, making other methods less feasible for large-scale production.

Choose the Correct Answer

From the analysis, we identify that 'fused salt electrolysis' (option b) is the method used in the extractive metallurgy of magnesium.

Key concepts

Fused Salt Electrolysis

Fused salt electrolysis is a crucial technique in the extractive metallurgy of metals like magnesium. This method involves passing an electric current through a molten salt, such as magnesium chloride, which is in a liquid state due to high temperatures. This process facilitates the deposition of metal ions from the electrolyte into pure metal at the cathode.
This method is particularly suitable for magnesium because magnesium has a remarkably high melting point, making it challenging to extract using other techniques. Fused salt electrolysis is advantageous as it can efficiently decompose highly stable compounds without the need for additional reducing agents. The resulting magnesium is collected as a high-purity metal.

• High efficiency in decomposing metal chlorides
• No need for external reducing agents
• Yields high-purity metal

Upon electrolysis, the magnesium ions are reduced at the cathode to form magnesium metal while chlorine is released at the anode, simplifying the separation process. This step is energy-intensive but essential for producing metallic magnesium.

Metal Extraction Methods

Various methods are employed in metal extraction, each tailored to specific types of metals and their compounds. Understanding these methods helps in choosing the correct one for each metal.
A key metal extraction method includes:

• Fused Salt Electrolysis: Used for metals with high melting points, like magnesium and aluminum.
  
• Self Reduction: Also known as Autoreduction, this method involves the reduction of ores using their internal reductant capabilities.
• Thermite Reduction: It involves using a thermic mixture, often aluminum powder, to extract metals from their oxides in an exothermic reaction. It's usually used for metals like iron.
• Aqueous Solution Electrolysis: This involves dissolving metal salts in water and then electrolyzing to extract metals, suitable for metals that do not easily melt or decompose as salts.

Each method has its merits and limitations depending on the nature of the metal raw material and the desired outcome for purity and scale.

Magnesium Production Techniques

The production of magnesium is typically accomplished through methods designed to handle its high reactivity and thermal properties. Understanding these techniques informs better decision-making in metallurgical processes.
Two primary techniques dominate magnesium production:

• Fused Salt Electrolysis: The predominant method, which involves electrolysis of magnesium chloride in a molten state, leading to high-purity magnesium production.
• Thermal Reduction: Also known as the Pidgeon process, which involves reducing magnesium oxide with ferrosilicon under high temperature in an inert atmosphere. This method is more energy-intensive but effective depending on the economic and environmental factors.

Fused salt electrolysis is preferred for producing large quantities of high-purity magnesium, primarily due to its efficiency and direct nature. However, each technique is chosen based on the particular requirements, such as energy costs, scale, and purity necessity, vital for industries such as aerospace and automotive.