Question

Starting with rutile \(\left(\mathrm{TiO}_{2}\right)\), explain how you would obtain pure titanium metal. (Hint: First convert \(\mathrm{TiO}_{2}\) to \(\mathrm{TiCl}_{4} .\) Next, reduce \(\mathrm{TiCl}_{4}\) with \(\mathrm{Mg}\). Look up physical properties of \(\mathrm{TiCl}_{4}, \mathrm{Mg},\) and \(\mathrm{MgCl}_{2}\) in a chemistry handbook.)

Short answer

Convert TiO2 to TiCl4 by chlorination, then reduce TiCl4 with Mg to obtain titanium.

Step-by-step solution

Conversion of TiO2 to TiCl4

To obtain pure titanium from rutile (TiO2), we first need to convert it into titanium tetrachloride (TiCl4). This is accomplished by chlorination of TiO2 at high temperatures (around 900°C) in the presence of carbon. The chemical reaction is: \( \mathrm{TiO}_{2} + 2 \mathrm{Cl}_{2} + 2 \mathrm{C} \rightarrow \mathrm{TiCl}_{4} + 2 \mathrm{CO} \). This process generates titanium tetrachloride, a volatile compound that can be distilled to obtain high purity.

Reduction of TiCl4 with Magnesium

The titanium tetrachloride (TiCl4) obtained from the first step is then reduced using magnesium (Mg) to obtain titanium metal. This reduction is carried out in a closed system to prevent contamination and is conducted at a temperature of about 800°C. The reaction is as follows: \( \mathrm{TiCl}_{4} + 2 \mathrm{Mg} \rightarrow \mathrm{Ti} + 2 \mathrm{MgCl}_{2} \). The titanium is collected as a solid while the byproduct magnesium chloride (MgCl2) is removed.

Removal and Purification of Titanium

The solid titanium obtained from the reaction may still contain impurities or remaining magnesium and magnesium chloride. To purify it, the titanium metal can be washed to remove residual salts and impurities. Additionally, further purification might be done using methods such as vacuum distillation or electronic refining to ensure the highest purity of titanium metal.

Key concepts

Rutile

Rutile is a mineral composed primarily of titanium dioxide (\( \text{TiO}_2 \)). It is one of the major sources of titanium, a highly valuable metal known for its strength and corrosion resistance.Rutile occurs naturally and can have a reddish-brown coloration due to iron impurities.

• It is predominantly found in metamorphic and igneous rocks.
• Considered a primary titanium ore, it is also mined for its use in pigments and the production of titanium metal.
• The extraction of titanium from rutile requires several chemical processes due to the strong bond present in titanium dioxide.

Starting with rutile, the extraction of titanium involves first transforming it into titanium tetrachloride (\( \text{TiCl}_4 \)) using a chemical process.This is an essential step since titanium in its oxide form is difficult to reduce directly into the metal.

Titanium Tetrachloride

Titanium tetrachloride (\( \text{TiCl}_4 \)) is a key intermediate in the extraction of titanium metal from rutile.This compound is created through the chlorination of titanium dioxide (\( \text{TiO}_2 \)).
Unlike rutile, \( \text{TiCl}_4 \) is a liquid at room temperature and has certain unique properties:

• It is colorless and volatile, making it suitable for purification via distillation.
• It has a high boiling point and is susceptible to moisture, decomposing to form titanium dioxide and releasing fumes.
• \( \text{TiCl}_4 \) is also used in various industrial processes, including the manufacturing of pigments and organic synthesis.

Converting titanium dioxide to \( \text{TiCl}_4 \) is the first critical chemical transformation in the effort to produce pure titanium metal.

Chlorination Process

The chlorination process is the initial step in extracting titanium from rutile (\( \text{TiO}_2 \)).This chemical process involves introducing chlorine gas and carbon to react with the titanium dioxide.
The reaction can be represented by the equation:\[\text{TiO}_2 + 2 \text{Cl}_2 + 2 \text{C} \rightarrow \text{TiCl}_4 + 2 \text{CO}\]This reaction occurs at high temperatures around 900°C. The carbon (often in the form of coke) acts as a reducing agent, facilitating this intense transformation:

• Chlorine converts titanium into a volatile compound, \( \text{TiCl}_4 \), which is then easy to purify by distillation.
• The by-products of this process include carbon monoxide, a gas that is safely vented away.
• The chlorination must be carefully controlled to ensure optimal conversion efficiency and safety.

Chemical Reduction

Chemical reduction is the process used to extract metallic titanium from titanium tetrachloride (\( \text{TiCl}_4 \)).This is accomplished using a reducing agent; in this case, magnesium (\( \text{Mg} \)), in a closed environment to avoid contamination.
The main reaction is as follows:\[\text{TiCl}_4 + 2 \text{Mg} \rightarrow \text{Ti} + 2 \text{MgCl}_2\]In this reaction:

• Magnesium acts as the reducing agent, donating electrons to convert titanium ions into metallic titanium.
• Magnesium chloride (\( \text{MgCl}_2 \)) forms as a by-product that needs to be removed.
• The reaction is conducted at high temperatures, around 800°C, to facilitate the reduction.
• It is important to handle \( \text{TiCl}_4 \) with care to ensure successful reduction and obtain a high-purity titanium metal.

Following reduction, additional purification steps might be required to enhance titanium's purity by removing impurities and residual compounds.