Project Amazonia: Solutions - Mining
Excessive unregulated mining is causing serious harm to the Amazon ecosystem.
A decrease in illegal mining, along with better practices for legal mining, would decrease negative impact on the environmental without significantly disrupting the product supply.
The mining industry is very closely tied to economics. Exports of mined products constitutes_____% of the economy, and is therefore significant to the country. Mining processes include many environmentally degrading activities, with effects including cyanide and mercury contamination, deforestation and general land degradation. Informal gold mining operations in the Amazon emit about 100 tons of mercury annually because of poor amalgamation practice. Approximately 1Kg of mercury is used for every Kg of gold produced.
Methods that mining operations can use to reduce their environmental impact:
Named after the developer, Norman Haber, the Haber Gold Process (HGP) is a solution aimed at minimizing the use of mercury and cyanide in the process of extracting gold. Details of the exact technique employed in this method are not indicated here, as the technique is proprietary and exclusively owned by Omai Gold Mines of USA. Basically, “the process operates by extracting the gold from its ores by dissolving the gold into water. It can then be recovered.”1 The process involves the use of non toxic chemicals that dissolve gold rapidly.
HGP offers a competitive advantage over the present techniques, because it extracts gold in bulk more quickly than would be possible using cyanide. It also has environmental advantages, because, unlike the cyanide method, it does not lead to the release of heavy metals such as mercury, cadmium and lead. It can be shown that the use of HGP “substantially reduces environmental hazards and a serious risk of contaminating ground water which has repeatedly occurred with conventional cyanide gold extraction.”1
The problem with HGP, however, is that it “is not a universal lixiviant. Every gold ore has different properties. Therefore, the lixiviant is preferably adjusted in order to optimize efficiency, recovery and extraction cost. A modified process can be used for extracting other precious metals.”1
It may be possible to apply this method to mines in the Amazon Rainforest. However, because the process is currently being patented and is not available for public perusal, it is difficult to determine whether it could be used practically. The only possible solution to this dilemma would be a joint venture between Orex and Brazil.
Solution to Acid Mine Drainage (AMD):
Acid mine drainage, results when the mineral pyrite (FeS2) is exposed to air and water, resulting in the formation of sulfuric acid and iron hydroxide
For chemists, the equation for AMD formation is:
FeS2 + 3.75 O2 + 3.5 H2O Û Fe(OH)3 + 2 H2SO4
Pyrite is commonly present in coal seams and in the rock layers overlying coal seams. AMD formation occurs during surface mining when the overlying rocks are broken and removed to get at the coal. It can also occur in deep mines which allow the entry of oxygen to pyrite-bearing coal seams
One leading method of reclamation that has been used in other parts of the world, and which could also be used in the Amazon, is the creation of special artificial wetlands. These wetlands can survive in acidic conditions, and they support microbes that can actually convert the acid into less toxic compounds.
Treatment of AMD could also involve chemical neutralization of the acidity, followed by precipitation of iron and other suspended solids. Such treatment systems include:
Many factors dictate the level of sophistication that the treatment system must have to ensure that effluent standards will be met. These factors include: the quantity of AMD to be treated, the chemical characteristics of the AMD, climate, terrain, sludge characteristics, and projected life of the mining plant. The chemicals which are usually used for AMD treatment include limestone, hydrated lime, soda ash, caustic soda, and ammonia.
This method uses plants to absorb contaminants such as mercury, pesticides, herbicides, explosives, solvents, radioactive cesium and strontium. Therefore, this is a solution that will be applied in areas where mercury is deposited by gold extraction such as along the Tapajos river basin. Scientists have developed a plant by building a synthetic gene, merApe9 that absorbs mercury using its roots. This new species can be modifies to suit the environment and climate of the Amazon Basin Rainforest.
This plant species absorbs highly toxic mercury ions from a growth medium and reduces them to less toxic and relatively inert metallic mercury. Once converted to its metallic state, the mercury is transferred into the atmosphere as a vapor.
Mercury pollution is particularly suited for cleanup using Phytoremediation because unlike with most chemicals, where the plants that grow on the contaminated medium accumulate large amounts of the toxic substance into their biomass, mercury’s volatility prevents it from accumulating in the plants. Metallic mercury vapor is emitted by the plants as they grow; outdoors, this vapor would diffuse into the atmosphere, quickly reaching nontoxic levels.
The problem with this is the consideration of the safety of releasing metallic mercury into the air. In particular, there is concern that mercury vapor in the air will precipitate into the Earth's waters, where it can enter aquatic food chains. Through the process of biomagnification, this mercury can reach toxic levels in the predatory fish that humans consume. There is some argument, however, that the mercury vapor released during a phytoremediation cleanup would be insignificant on a global scale. There is also a need to introduce these genes into high biomass plants and show that it works on soil. Though some phytoremediation schemes have been field-tested, mercury-removing plants have only been grown on agar under laboratory conditions. In addition, Arabidopsis, a common test plant, does not reduce enough mercury and lacks the field cultivation to make it a practical choice for phytoremediation cleanup.
This can be done by tailing washing where the tailing flows by gravity to a two-stage washing circuit to recover cyanide. The washed tailing is pumped to a reaction vessel for cyanide destruction. The Inco/S02 air process with two stages of washing is used in order to provide an effluent containing less than 5ppm cyanide for discharge to the tailings pond.
By using methods such as high density thickening as much as 90 % of the cyanide that is found in tailings can be recovered. These recovery methods will result in the following advantages:
Cyanide recovery will make the current cyanide concentration solution ponds unnecessary reducing the risk to wildlife and water.
Reduced cyanide in tailings will make it easier for quicker and cleaner mine closure and reclamation.
Recovery and recycling of cyanide makes it less necessary to import cyanide from abroad and this increase the profitability of the mines.
1) We would need the government’s support in this distribution of permits and in monitoring data analysis. If our data reveal that illegal mining operations are taking place or illegal levels of contaminants are coming from legitimate mining site, the government must be willing to take the necessary measures to stop these violations of our proposed regulations.
2) We would require funding for the development, creation, and distribution of our monitoring devices.
1) Using our data on the various level of pollution that different mines have caused, and information from the government on which mining site had their permits revoked, we would assess whether the miners who polluted the most were dealt with appropriately.
2) We would compare the quantity of exports of mined materials, as well as the global prices of these materials, both before and after the implementation of our plan. This would show us what sort of effect, if any, our strategy has on the economy.
3) We would assess the overall rainforest health, as outlined in the general monitoring techniques of Project Amazonia, and look for signs that our new policies had had some appreciable impact.
4) Finally, we could compare the rates of reforestation on mined lands before and after the adoption of our set of guidelines.
1) We expect that the amount of contamination due to mining in the Amazon will decrease. This will be a result of better controlled mining, better clean up methods and more environmentally sound behavior from large companies, because the companies will want to avoid large fines and other penalties.
2) We predict that the quantity of exports due to mining will decrease initially, causing a slight rise in price of the global market, but after a few years, miners will have adjusted their practices to comply with the new guidelines, so prices and output should stabilize at levels similar to the initial ones.
3) We predict that the overall health of the rainforest will improve, due to the reductions in contaminants and disruptions in the environment.
4) If all goes well, the rate of reforestation of abandoned mine sites should also improve, because our plan requires that the mining companies restore mined areas to some minimum level of health before abandoning them entirely.