One of the more common Rock types mined/quarried for use as concrete aggregates and road building material is Basalt, this material is found in many areas of Brasil. Basalt rock produces high quality aggregates and many large quarry operations have been established with this material and it has been used in construction for many years.
In recent years it has been found that the addition of Fine basalt material, Rock Dust, to agricultural lands and forestry areas, re-mineralizing the soil replacing vital minerals in the soil that have been leached out of the soil in high rainfall areas. This increases the quality of the soil and assists plants in accessing minerals and nutrients contained in the soil resulting in better plant growth and producing higher crop yields.
An additional benefit is that researchers have found that the addition of Rock Dust to the soil, enables the soil to draw more Carbon from the atmosphere trapping excessive Carbon within the soil which is a huge benefit to the environment. Other Rock types, such as Gabbro, Diabase, Gneiss, Andesite are also suitable for the production of Rock Dust providing the required minerals are present in the material.
The required Rock Dust Government specification size in Brasil is <2.00mm and 50% of the material must be finer that 0.3mm. This very fine Rock Dust enables Basalt, or other rock types, to weather relatively quickly so that the processes described above can occur in a short period of time.
Bluetec Brasil manufactures a complete range of Crushing and Screening equipment with our machines successfully operating in many mines and quarries across Brasil and internationally. Our equipment has been used to produce standard Concrete and Road Aggregate as well as specialized applications to produce a specific product.
One of the more exciting new developments is the production of Rock Dust using Bluetec’s Crushing and Screening equipment in various applications.
The most environment friendly applications are reprocessing previous ‘waste stockpiles; that have accumulated over the years and crushing and screening this product to produce valuable, salable, high quality products.
The material is fed into a Bluetec VSI Crusher and then transported to a suitably sized Bluetec Double Deck Screen. The Screen produces two products with the oversize being returned to the VSI for further reduction.
The success of this application is that we are producing two quality products from material previously viewed as waste, namely a high quality Concrete Sand as well as Rock Dust.
The top deck of the Screen is a 4 mm aperture and the bottom deck aperture is 1.2 mm. This produces a Sand fraction that, due to a small amount of carry over of fines from the bottom deck of the screen, has the right amount of ‘fines’ in the grading. Due to fact that the material has all passed through the VSI crusher, the particle shape is excellent. Initial test work on the Concrete Sand has been extremely positive with reports of a 10% reduction in cement content in concrete made with this sand.
The bottom deck is 1.2 mm and this produces Rock Dust that is well within the Government specification <2.00 mm and 0,3 mm fraction well in excess of 50%.
The material has been accepted by the market and a large tonnage of Rock Dust produced by Bluetec equipment has already found it way into agricultural fields of Brasil benefiting crop production and the Brasilian environment.
Scientists are busy developing a methods to quantify the amount of Carbon that is captured by the addition of Rock Dust into agricultural lands. Once this is done it will open up the opportunity for producers/farmers to generate Carbon Offset credits which will be a tradable asset which will produce a revenue stream into the system.