Mining Sector
1- Introduction
1- Mines and quarries.
2- Crushing and grinding.
3- Concentration.
1- Introduction
Metals are involved in many industries we interact with daily, from electronics to precious jewelry.
There are several stages through which metals and precious materials pass, starting from extraction from the earth’s crust to their utilization in other industries:
1- Mines and quarries.
2- Crushing and grinding.
3- Concentration.
1- Mines and quarries
The life cycle of a mine typically consists of five stages:
1- Exploration and Surveying
Conducting an assessment of the area, studying the geology by geologists, evaluating the reserves of valuable materials, ultimately creating two-dimensional and three-dimensional mapping of the area, determining the grade of materials, and conducting a feasibility study of the area.
2- Planning
After studying the area and determining the material reserves, planning is done to exploit the mine. This planning may sometimes occur in stages over long periods extending up to 20 years or more. The methods used for material extraction, such as blasting materials, drilling equipment, or smelting, are determined.
3- Development
After planning, the implementation process begins, progressing in stages depending on the size of the mine (large or small) or whether it is a quarry. It can be either surface or underground.
4- Production
Subsequently, the rocks and materials containing minerals are transported to the next process for crushing. This is done either by dedicated transport trucks, conveyor belts, or pumps inside large pipes.
5- Closure
A mining or quarry project has an end, and at the end of the project, the extraction of materials becomes economically unviable, leading to closure. Equipment is then removed.
2- Crushing and grinding
The raw materials extracted from the mine contain ore along with impurities, and the aim of crushing them is to control the process of separating the ore from the impurities.
Typically, rocks are crushed using two methods: crushing and grinding.
1- Crushing
After extracting materials from underground, the rock sizes are large, and crushers are used to break them down. This can be done in one or two stages depending on the nature of the rock.
There are several types of crushers, the most common being jaw crushers, gyratory crushers, and cone crushers.
2- Grinding
After reducing the size of the rocks, they are ground using specialized mills to further crush them.
This also occurs in one or two stages depending on the nature of the rocks, and a specialized mill is used. The most common ones are rod mills, which rotate the rocks to collide with each other for further fragmentation, or ball mills, which use steel balls inside the mill to crush the mixture.
The materials from this process exit as a mixture in the form of small grains like sand, and water is added during this process to facilitate grinding.
3- Concentration
After the comminution process, the resulting mixture contains several elements, with the ore mixed with impurities. Therefore, the separation process occurs in this stage to increase the concentration of the desired element.
Typically, separation (depending on the nature of the ore in the mixture) occurs in stages and through two methods: physical separation and chemical separation.
1- Physical Separation
This is based on the physical properties of the element and is achieved using several methods, including:
– Magnetic Separation: Utilizing magnets to separate metallic materials such as iron.
– Optical Separation: Separating the ore from other materials based on their appearance.
– Electrical Conductivity-based Separation for metals.
– Density-based Separation between the ore and impurities.
– Froth Flotation Separation, considered one of the latest methods for separation.
2- Chemical Separation
This is used to increase the ore’s concentration and involves chemical reactions to remove impurities, typically used for metal extraction.
The two main processes in chemical separation are Pyrometallurgy and Hydrometallurgy.
1- Pyrometallurgy
Involves three methods: smelting, roasting, and calcination.
2- Hydrometallurgy
Involves three steps: leaching, purification, and concentration, followed by metal extraction.