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The mineral processing uses mechanical and chemical processes to extract the desired mineral from generating in the process waste, known as tailings product. These wastes are stored in large piles of tailings and can be seen as clay or sand, because they contain finely ground rock that can easily produce dust. They are usually white, pale yellow or gray. Depending on the mined ore, tailings may contain various levels of pollutants such as arsenic in gold mining, which can pose serious health risks to local communities. In addition to human health, nearby vegetation can be affected too. Studies show that traces of toxic metals (Hg, Cd, Pb and As) and associated heavy metals (Cr, Ag, Ni, Au, Mo, Zn, Mn and Cu) can be found in soil near tailings gold mines. As a result, plants and soil can not be used for grazing or agriculture.
The processes of extraction of other minerals such as lead, copper, zinc also generate waste containing heavy metals, and deposits similar to the tailings piles, as in the case of coal mining, batteries can also cause problems through exposure to dust released from them. To address this problem, there must be efficient and effective systems to limit exposure to particulate matter generated by wind. An effective solution are biopolymers Dust Stop, which allow the formation of lasting and robust film on the surface of the tailings, with an ecological, economical and sustainable approach.
Polymers have always been a part of our natural world. In our body, our muscles and bones are made of polymers called proteins. Our genetic material, DNA and RNA are also polymers. The cellulose found in all plant material is a polymer, like the complex carbohydrates found in bread and masses. Rubber is a good example of a naturally occurring polymer. Some synthetic polymers include many fabrics such as rayon, nylon and polyester. Some natural polymers are effective binders of minerals found in the tailings, allowing a sustainable approach to minimize the threat of toxic emissions from the tailings.
To understand the effectiveness of polymers Dust Stop is important to understand the science behind the polymers and how we can use its features in our favor when applied to waste. Name polymer gives an indication of the structure of these materials. Poly means "many" and merely means "units". The polymers are formed when many similar molecules called monomers join as beads on a string. The "pearls" are the monomers and the "chain" is the polymer, which make up a macromolecule. Usually, the chain net has a skeleton or carbon with hydrogen (H) disposed therein and other elements, such as oxygen (O), nitrogen (N), fluorine (F), silicon (Si), and sulfur ( S). Thus, most polymers are organic materials. Copolymer is a combination of two different monomers.
One interesting polymer for agglomerating minerals in the tailings product is called Dust Stop Concentrate (DSC) supplied as a liquid solution or emulsion to facilitate dilution, mixing and application. Comprises an emulsion polymer droplets suspended in a solvent (water). The dispersion medium is water, which provides a low cost system, nonflammable, nontoxic and relatively odorless. Water is cheap, inert and ecological and has excellent heat transfer and low viscosity.
Generally, polymer dispersions containing 40-60% polymer solids and comprise a large population of polymer particles dispersed in the continuous aqueous phase (about 1015 particles per ml). The particles DSC of the polymer are within the size range of 10 nm to 1000 nm in diameter and are generally spherical. A typical particle 1-10000 include macromolecules, each macromolecule contains about 100 to 106 monomer units.
After application of the emulsion to the surface Dust Stop a slope or tailings pile, the water evaporates and the polymer particles are pressed closely together to form a continuous film. Thus, the application of Dust Stop leads to isolation of the polymer by removing water and Dust Stop becomes a polymer film.
Dust Stop ability to form a durable, water resistant film film allows you to encapsulate all particulate material prevents dust generation and dispersal in the air. The key to good entrapment of particulate material is the transition from the wet polymer, the dispersed polymer and the dry film. The application temperature should be above the minimum film formation temperature (MFT), which corresponds to the glass transition temperature (Tg) in the presence of water.
The polymer formulation Dust Stop Liquid Concentrate optimizes thermoplastic and thermosetting polymers behavior. It behaves mainly as a thermoset polymer, as it is permanently bonded by chemical reactions (coalescence) which occur when heated (evaporation) and results in a permanent irreversible change. These reactions result in a strong, heat resistant film that encapsulates the surface. The resulting film also has characteristics of a thermoplastic in which when heated softens allowing the film to bend and break during periods of warm weather. When tested at 55 ° C a sample of Dust Stop Liquid Concentrate, this becomes flexible and can bend and stretch (with effort), but returns to its original shape and size.
There are several methods for applying DSLC depending on the circumstances of a given scenario. Considerations include the required coverage, frequency of application, the rate of waste generation, storage duration necessary long-term plans remediation, climatic conditions, and the special site or material details. Application methods range from tank trucks sprinkler systems. The concentrated emulsion is mixed with water directly into the water tank of the truck and immediately sprayed onto the waste pile. This initiates the drying process as described above and once completed, a waterproof barrier and wind, be encapsulated waste, providing long-term dust and erosion control.
The best way to reduce the risk to human life and the environment from exposure to contaminants associated with mining waste and storage is physically and chemically immobilizing the tailings. Wind and water are the main vehicles for dispersing particles, both environmental factors difficult to control and which are not normally considered when installing dams, levees and other types of surface storage reservoirs. The increased complexity of the material stored in the tailings are the smallest particulate matter, which after prolonged periods of time are easily dispersed to surrounding areas. The polymer Dust Stop is easy to apply, and is a long-term solution that can help minimize this dispersion. The properties of the polymers used in the powder formulation allows the product can be applied to any waste with satisfactory results even in hydrophobic materials such as coal.
The concentrated polymer Dust Stop is a solution to reduce the impact of wind and water contaminant dispersion of the tailings piles. Dust Stop Liquid Concentrate ability to form an insoluble barrier on the surface of the trays, regardless of size, shape or material is the key to its applicability.