Preval - leader in industrial production

Mineral extraction, Crushing Plants, Hammer Crushers and Washing Systems for sand production

Preval offers the best supply service in crushed aggregate and is one of the largest producers of such minerals in different grain sizes, with a monthly production capacity of up to 85,000 cubic metres from both quarries. Our most prominent customers express their complete satisfaction with our products, thanks to the excellent quality of Basalt extracted from the two quarries we currently operate.

 

References.

Our quality and service speak for themselves. Our aggregates have been used in major projects across the country, such as the construction of the Panama City Subway Line 1, the construction of the third bridge over the Panama Canal, the Pacific access channel for the Panama Canal- PAC-4, the City of Health hospital complex, the building of the Coastal Highway, Tocumen Airport road construction and expansion, among others.

We are pioneers in sand production, which is the end product of the same mineral after crushing.

Process:

The first stage is extraction of the mineral in the quarry..

To do that, a Drilling Grid is designed:

• In the design of the Drilling Grid, certain matters need to be taken into consideration such as the direction of noise and vibration when blasting the rock.
• The drilling mesh is sized on the basis of the amount of mineral to be crushed
• The drilling grid is planned on the basis of how often the rock needs to be blasted and the programmed production volumes.

Blasting:

• By law, blasting has to be carried out by an external operator.
• The company in charge of laying blast charges is also responsible for the removal, transportation and filling of drill holes in the grid.
• The company that provides the blasting service is inspected by the Head of Mining Production and Development while the blasting program is being run.

A shovel truck then places the blasted rock on articulated or off-road trucks for transport to the crushing plant.

• The articulated or off-road trucks carry the mineral to the crushing plant, where it is dumped into the primary hopper.

Crushing::

Primary crushing:

• The primary unit has a hopper into which all the blasted rock from the extraction area of the mine is poured.
• The rock passes from the hopper through a stone grinder that produces an intermediate size grain, which has a system under it to remove waste material from the crushed aggregate.

Secondary crushing:

• The rock ground in the primary stage is transported by belt conveyors to a cone silo, where it is re-ground to reduce the size of the grain.
• The stones are transported again by belt conveyors to the screen, which has meshes or sieves that sort it and remove the required size from the system.

Tertiary crushing:

• Belt conveyors carry oversized stones to a second cone grinder, where they are further ground to the required size.
• The stone runs through the screen, which sorts the required grain size from the oversized material, which is returned and fed through the system again (closed circuit).
• The sorting area always produces an amount of material known as ‘dust’ and another called “Coarse Aggregate for Concrete”.
• • The ‘dust’ is conveyed on belts to the washing wheel, which separates any soiled material to produce washed sand, which is then stored in the stockyard.
• The material known as Coarse Aggregate for Concrete is run through the Vertical Hammer Crusher (VHC). This reduces the size of the grain, and takes it through a screen where it is sorted and conveyed by belt for storage in the stockyard. The second level of the screen receives the fine dust, which is fed into a screw washer to separate fouls, while the resulting washed sand is stored on stock piles in the yard./li>

Storage and/or sale::

• Aggregates need to be produced and stored in time to enable all quality control (sampling, laboratory and shipping) operations to be performed.
• The aggregate stockpile needs to stand on an area free of roots, grass and/or weeds to prevent any contamination.
• Aggregates should be stored in such a way as to keep grain sizes well separated in order to prevent any impact on the quality of the required product.
• The bottom six inches of the stockpile that are in contact with the earth should not be used unless the pile has been built up on tarpaulins to prevent any contamination.
• Aggregates are stockpiled and labelled according to their name and/or nominal grain size.
• It is important to avoid building very high stockpiles, which should not exceed twice the height of the shovel truck.
• The stockpile is unloaded and an amount of aggregate corresponding to three truck loads is stored separately.
• Stockpiles should be made to remain stable and firm by adding to them in horizontal layers.
• Before the product is sold, it must be validated by the quality control lab staff.