In the exploitation of metal and mineral mines, the raw material is usually in the form of sand. These sands contain valuable minerals that are important minerals in the production of many products around the world. These mineral sand deposits can be of high quality but small in size or of considerable size but of low quality and located in hard to reach areas. In the exploitation of these raw materials, large amounts of water are used for rinsing from impurities. Large quantities of water and electricity usually need to be brought to the mine, and new access roads are needed. The water used to separate useful raw materials from waste is drained into artificial lakes, or discharged into natural streams, all of which create major social and environmental problems.
To reduce water use, it is easiest to replace water with air. High pressure and high velocity air can be used as a medium to separate ore particles by size and weight. Excavators for digging and crushing ore would have to have powerful fans that would separate the excavated and crushed ore by weight.
Such an excavator with an air separator would most resemble a large grain harvester. At the front end of this excavator is a rotary roller (1) with lots of small knives that cut the rock in front of it and turn it into tiny particles. This rotary roller (1) is located on the backhoe bucket (2) which accepts small particles from below and flattens the ground in front of it. The rotary roller (1) throws the excavated fine particles into the upper part of the backhoe bucket (2) where the rotary crusher (3) further grinds the excavated particles into material of approximately equal size. The shredded material is transferred to the upper rear of the backhoe by the inner conveyor belt (4). Below this inner conveyor belt (4) there is a powerful fan (5) which creates a strong air current under the upper part of the inner conveyor belt (4). From this inner conveyor belt (4) the excavated particles of material fall downwards towards the three conveyor belts which accept different fractions of material. In this way, air separation of the material according to weight is performed.
The heaviest particles of material through the air stream fall down onto the lower conveyor belt (6).
Slightly lighter particles fall obliquely downwards to the middle conveyor belt (7).
The lightest particles fall on the upper conveyor belt (8).
Too small particles of ore in the form of dust could also be found among the lightest particles, so it is necessary to ensure the smallest possible difference in particle size. Therefore, it is necessary to break the material into as small particles as possible so that the differences in particle size are as small as possible. This is most easily achieved by placing as many cutting blades as possible on the rotary roller (1) to create particles of the same size.
The type of particle that has useful ore is transported by trucks for processing.
Those types of particles that do not have useful ore are deposited at the excavation site. This would significantly reduce the amount of material to be transported to the ore processing plants. In addition, clean and dry ore is much lighter than wet, so transport costs are easier.
Costs would also be reduced because barriers for tailings separation and deposition would not have to be built.
The layout of the space would be less altered.
Watercourses into which polluted, muddy water flows would not be polluted.
This would significantly reduce the resistance of the public and environmental associations, investments in environmental protection would be significantly reduced, and thus production costs would be reduced.