Bauxite Mining Processing
Bauxite is the principal ore of alumina (Al2O3), which is used to produce aluminum. Bauxite is one of the most abundant elements on earth and contains nearly 25-30% of alumina. Its typically found near the equator in tropical and subtropical regions, in the form of horizontal layers beneath a few meters of overburden. It’s composed of a mixture of aluminum hydroxides, clay minerals, hydrous aluminum oxides and insoluble materials, namely magnetite, quartz, hematite, etc.
Guinea, West Africa, where MineralVest holds its concessions, is the world’s leader in known bauxite reserves at 7,400 million tons quickly followed by Australia which has 6,000 MT.
Bauxite mostly occurs close to the surface, with only 1 or 2 m of overburden. Typical deposits range in thickness from 3 to 15 meters. However, there have been some deposits that can reach 200 to 300 meters in depth.
The typical processes involved in the mining bauxite are as follows:
Clearing of vegetation and timber using scrapers and bulldozers. Simultaneously, seedlings and saplings may be collected to rehabilitate the land post mining.
Removal of overburden which is the top soil that averages 2 meters thick.
Breaking up of the bauxite by drilling and using large bulldozers.
Once the bauxite is loosened and in manageable sizes it is crushed and washed.
The clay is then deposited into tailing ponds. After its use, these tailing ponds are replanted using local species to re-establish natural vegetation.
Bauxite is then placed into stockpiles before being transported to a nearby port via rail or truck.
Once the bauxite reaches the port, it is placed on ships and delivered to alumina refineries.
The land is rehabilitated back to the existing land use in collaboration with the local people and government.
Unlike the base metal ores, bauxite does not require complex processing because it’s usually mined at an acceptable grade. Ore quality can be improved relatively easily and cost-effectively by removing clay, known as “beneficiation” which includes washing, wet screening and mechanical or manual sorting.