Bauxite - What is Bauxite?, Important Uses, Practice Problems & Frequently Asked Questions (FAQs)

We are surrounded by minerals all around us. From toothpaste to the paint in our rooms, there are countless uses of these substances.

In cosmetics, there is a wide variety of minerals used. Did you know that the friendly calamine solution actually features the ore of Zinc. And here you thought the ores needed to be converted into metals to be utilised. Oh well, that is indeed not the case. A lot of ores are useful right from the moment they leave the womb of the planet.

Let us explore one such important ore and its uses-Bauxite!

Table of Contents

• Introduction to Bauxite
• Important uses
• Practice problems
• Frequently asked questions(FAQs)

Introduction to Bauxite:

A sedimentary rock having a comparatively high aluminium concentration is called bauxite ().

It is the principal producer of gallium and aluminium in the world. Thealuminium minerals named asgibbsite, boehmite, and diaspore(,mono hydrated aluminium oxide is diaspore) make up the majority of bauxite, which also contains trace amounts of anatase and ilmenite as well as the having iron oxides in the form of goethite and haematite. Bauxite() is reddish-brown, whitish, or tan in colour and has a dull lustre. Chemical formula of bauxite is . It is an important ore of aluminium.

Bauxite ore, which is commonly infected with ferric oxide and silica, is used to extract aluminium. Because it is hard to remove Fe and Si from aluminium metal, the removal of ferric oxide and silica from bauxite ore before electrolysisis required. The presence of these elements renders the aluminium metal brittle and prone to corrosion. The three main procedures are used to extract aluminium from bauxite ore.

i)Bauxite ore purification, i.e. elimination of ferric oxide and silica.

ii) electrolytic reduction

iii) Aluminium purification via electrolysis.

Baeyer’s processis mostly used on bauxite ore with ferric oxide as the major contaminant. Because the ore is usually red in colour, it is known as red bauxite. To convert any ferrous oxide present in the powdered ore into ferric oxide, it is first roasted at a low temperature. It is subsequently digested in an autoclave at 150C for many hours with a concentrated sodium hydroxide solution (density 1.45 ). While aluminium oxide dissolves in caustic soda to generate soluble sodium meta aluminate (), ferric oxide and silica remain insoluble and settle to the bottom. Filtration is used to eliminate them.When sodium meta- aluminate undergoes hydrolysis with the generation of precipitate, the solution is stirred with freshly precipitated for 36 hours.The precipitate is washed and dried before being used. The solution can be concentrated and used once more.

Important Uses:

• Aluminium ore: Bauxite is primarily used to obtain the metal aluminium from its mineral sources. It is widely used in daily life and in the manufacturing of appliances, doors and windows, furniture, cosmetics, paints and varnishes, aluminium hydroxide pharmaceuticals, and other items. Manufacturing processes yield 92–99 percent pure aluminium, which is used to make aluminium foil and beverage cans. Due to its low density, it is mostly used to construct transportation-related vehicles, including as planes, cars, trucks, trains, and spaceships. It has been utilised in the production of cans for the storage and packaging of food and beverages due to qualities including corrosion resistance and non-toxicity. Due to its excellent mechanical strength and conductivity, it is used to create motors, generators, transformers, capacitors, and aluminium wires, among other things.

• Gallium ore: One of the primary sources of the rare metal gallium is bauxite.

Gallium builds up in the sodium hydroxide liquid during the Bayer process' conversion of bauxite to alumina. There are numerous ways to extract it from this. Ion-exchange resin use is the most recent. The original concentration in the input bauxite has a significant impact on the achievable extraction efficiency. A typical feed concentration of 50 ppm has an extractable gallium content of roughly 15%.

• As a catalyst: After extraction and purification, alumina (Al2O3) is used as a catalyst in a variety of chemical processes. A significant use for activated alumina is as a catalyst and adsorbent in the synthesis of polyethylene and hydrogen peroxide. Sulphur, arsenic, and fluoride can be removed using it as a selective adsorbent. It serves as a desiccant because it draws moisture from the air around it, keeping items like pharmaceuticals dry. Certain fluorides can also be filtered using activated alumina filters. Lye (pure NaOH) in solution form can always be used to renew or revive activated alumina.

• Industrial: Bauxite that has been calcined is utilised as an corrosive in industry. After being crushed and heated to an extremely high temperature, sintered bauxite (also known as calcined bauxite) is used to create fine corrosive beads for use in sandblasting equipment when friction is needed to either smooth or roughen a surface. Additionally, it functions as an corrosive in polishing powder, polishing solutions, and sintered bauxite particle sandpapers. Bauxites are very frequently used in the production of paper. Alumina serves as an absorbent in water purification facilities where it is also used.

Practice Problems:

Q1.__________ is a poor conductor of electricity in its purest form.

A. AluminaB. SilicaC. AluminiumD. Cryolite

Answer: A

Solution:Alumina is a poor conductor of electricity in its purest form.The challenges are overcome by combining alumina, cryolite (), and fluorspar ( in a 20: 40: 20 ratio. This mixture has a fusion temperature of 900°C and is a good conductor of electricity.Q2._____________ process is used for purification of bauxite ore.

A. Froth flotationB. Blast furnace

C. Baeyer's Process

D.Thermite

Answer: C

Solution: Baeyer's Process is mostly used on bauxite ore with ferric oxide as the major contaminant. Because the ore is usually red in colour, it is known as red bauxite.

Q3. Bauxite is commonly found in India as ____________.

A. Gibbsite

B. Kaolinite

C. Shieldite

D. Karinite

Answer: A

Solution:The main form of bauxite found in India is gibbsite (), which accounts for between 40 and 60 percent of the total material and contains titania, silica, and iron oxides as significant auxiliary components.

Q4. What is the chemical formula of bauxite?

A.

B.

C.

D.

Answer: A

Solution:Chemical formula of bauxite is . It is an important ore of aluminium.

Frequently Asked Question-FAQs:

Q1: Are all kinds of bauxite the same?

Answer:Based on their source, bauxites' physical features vary from area to area. While few are pisolite or gems-like granular rocks that are dense and unyielding, others are soft and easy to crumble. Some even have a multilayer porous or pseudomorphic nature.

Q2: What are the different properties of bauxite?

Answer:The majority of the laterite rock varieties are pisolite, which can range in colour from grey to brown to pink to cream to yellow, etc. Laterites have a patterned and rough exposed surface. The laterite bauxites are changed into the karstic bauxites.

Q3: List the physical properties of Bauxite.

Answer:Bauxite typically has a Mohs hardness range of 1-3, making it a soft substance. It has an earthy shine, a specific gravity between 2.0 - 2.5, and exists in white , grey and reddish brown colours. These traits are essential for distinguishing bauxite, but they show little influence on how valuable or helpful it is. This is because of the reason that bauxite is operated to yield a substance with entirely distinct physical characteristics.

Q4: Can Bauxite be used as an abrasive?

Answer:In some forms, yes. A particularly tough variety of synthetic corundum is calcined alumina (9 on the Mohs Hardness Scale). Crushed and divided into various sizes, calcined alumina is then used as abrasive. Aluminium oxide sandpaper and polishing solutions are all manufactured from calcined alumina.

Q5: What are the alternatives to Bauxite?

Answer: At present production rates, there will be enough bauxite for centuries of supply. Bauxite may not be the only material utilised to manufacture alumina. Alumina can be produced from power plant waste, and oil shale, however doing so is more expensive due to the different processes needed. There are times when synthetic mullite and magnesium oxide made from magnesite are used to replace refractories made of bauxite.

Q6: Where can Bauxite be found?

Answer: The mineral bauxite is widespread throughout the world. The top producers of bauxite in 2017 were Kazakhstan, Australia, China, Brazil and the United States. Each of these countries possesses sufficient reserves to continue production for an extremely long time.Some people have sufficient supplies to endure for almost a century. Bauxite is only occasionally mined in the U.S, and nearly 99 percent of the country's consumption is imported.

Q7: What are the other applications of bauxite?

Answer:Despite having few applications, bauxite is frequently utilised in the production of paper, the purification of water, and the refinement of petroleum. Bauxite is used in a variety of different sectors besides those that make rubber, plastic, paint, and cosmetics.

Q8: Is Bauxite used in the manufacture of dental cement?

Answer: It is indeed used in the manufacture of dental cement. Alumina and bauxite are both used in the manufacturing of aluminium compounds, including alumina. Refractories utilise the raw material to create a wide range of products.

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