Stage 1 Chemistry
Science as a Human EndeavourTask: Metals and Mining
Investigate an environmental disaster caused by mining of a particular metal. Consider both the positive and negative impacts of this mining, such as economic, social, political, and environmental on the country involved. Consider new technologies that are being designed to prevent such disasters from occurring in the future or new materials with suitable properties that could replace this metal for some uses.
9 February 2018 (Draft)
Question: What has been learnt from the aftermath of the Bento Rodriguez tailing dam disaster about the use of tailing dams? Has this disaster indicated to discontinue the use of tailing dams and look for other viable options to replace such dams?
4063602978402 Fig 1 : The Doce River, flooded with toxic mud after the collapse, flows into the Atlantic Ocean.00 HYPERLINK “http://www.abc.net.au/news/2015-12-01/000_ts-mvd6731006.jpg/7206418” Fig 1 : The Doce River, flooded with toxic mud after the collapse, flows into the Atlantic Ocean.
The mining of iron is multi-billion-dollar industry but has anyone stopped to consider other impacts of this industry. The major concern surrounding the mining of this ore is the disposal/storage of the by-products of processing this ore, Tailing Dams. Such dams have a risk of failing and sadly this was the case on the 5th of November in a Brazilian subdistrict of Mariana, Bento Rodriguez. This report will explore the properties of iron and detail why it is valued by society. It will also detail the positive and negatives impacts of the mining industry in Brazil and suggest alternatives to using traditional wet tailing dams.
“Nineteen people were killed, villages were swept away, hundreds were left homeless and rivers were polluted” ABC News business reporter Sue Lannin wrote about the BHP and Vale owned Samarco mine. The failure resulted in a release of up to 60 million cubic meters of lethal iron mud into all the surrounding environment which included the Doce river, which directly flows to the Atlantic Ocean. The extensive damage made to the affected areas is undeniable with scientists saying that the sediment, may contain harsh chemicals, which could alter the course of streams as they harden and reduce oxygen levels in the water and diminish the fertility of riverbanks and farmland where floodwater passed” (ABC News S Murden November 17, 2015).
Occurring abundantly, Iron (Fe) ore is an indispensable metal commonly found in the form of magnetite (Fe3O4), hematite (Fe2O3),goethite (FeO(OH)) and limonite (FeO(OH)·n(H2O))(Geoscience Australia 2015) . Iron in its pure form is a brittle and soft substance but when fused with small amounts of other elements e.g. carbon, the material becomes different alloys, which are significantly harder and stronger materials. Even so, pure iron has many specific uses for example in the production of pipes, fittings, engine blocks but it’s most common use is in the production of steel (Australian Mines Atlas 2015) . In fact, about 98% of the world’s iron is used to make steel. Steel is an extremely versatile material that is strong and durable, these desirable properties with its relatively low cost, applications of Steel are extensive ranging from food containers to paper staples to structural metal in engineering and building projects (Lenntech). It has even been argued that iron ore is “more integral to the global economy than any other commodity, except perhaps oil (Blackhawk partners 2013).
The mining iron results in a positive impact on the economy of Brazil. Due to the demand of iron, the abundance of the raw material in Brazil and low currency conversion rates against American dollars, Brazil’s metal industry thrives (InvestinBrazil 2013). Another positive outcome of these mining sites is it provides jobs for the people in the area and generates revenue for the community but at the cost of their health.
As for the negative social impacts of mining iron, communities residing near the mining sites have to endure extensive noise, air, land, and even water pollution but also live with fear that the tailing dam could suffer a failure.
As for the negative environment impacts created as a result of mining iron. The first negative environmental impact of iron mining is the drastic affect it has on the area’s air quality. The construction and operation of iron mining emits high levels of fugitive dust and products of combustion such as Nitrous Oxide (N2O), Carbon Dioxide(CO2) , Carbon Monoxide(CO), and Sulfur Dioxide(SO2) (Wikipedia December 2017). The next negatives are the noise pollution and physical damage to the area mining creates, these disturbances cause stress on the natural habitat of wildlife and dramatically alters the behaviour of megafauna naturally occurring in the area even causing many species to be uprooted. (Greener Ideal Staff June 17, 2017). 3872230259080Fig 2: Mine tailings on the banks of a tributary to the Rio Doce in Brazil after the collapse of the Samarco iron ore tailings dam(ABC News: Greg Nelson)
00Fig 2: Mine tailings on the banks of a tributary to the Rio Doce in Brazil after the collapse of the Samarco iron ore tailings dam(ABC News: Greg Nelson)
As for new technologies for prevention, many experts have suggested to ditch traditional wet tailing dams and start using the alternative “dry stacking”. The ‘dry stack’ process removes water from spent ore using vacuum or pressure filters, allowing tailings to be stacked and better controlled (Reuters 2015). Partially due to the increased cost, this method of engineering is rarely considered for use, with thousands of wet tailing dams being built and many more planned (Reuters 2015). As for replacements for iron there is no urgency in finding one as stated before society views iron as an indispensable metal that cannot be replaced by an alternative but it has been suggested that people recycle iron to decrease the mining of this ore.
To conclude, the Bento Rodrigues dam failure is just one example of a series of dam failures that further support a change in how mining companies dispose of their by-products. Also, at the end of the day cleaning up the disaster cost more on the company and environment than just preventing it in the first place. If not in investing in dry stacking, then more extensive safety checks need to executed and more safety protocols need to be put into action for tailing dams to prevent disasters like the Bento Rodrigues from occurring again.
Geoscience Australia 2015, Iron Fact Sheet, Australian Government, accessed 19 February 2018, <http://www.australianminesatlas.gov.au/education/fact_sheets/iron.html>.
Brazil Mining Industry 2013, InvestinBrazil, accessed 16 February 2018, <http://investinbrazil.biz/industry/metallurgy/brazil-mining-industry>.
Greener Ideal Staff, 2017, The Impact of Metal Extraction to the Environment, Economy, and Society, accessed 16 February 2018, <https://greenerideal.com/news/business/0617-metal-extraction/>.
Knight, B 2016, BHP’s deadly dam collapse linked to ramping up production, accessed 16 February 2018, ;http://www.abc.net.au/news/2016-02-29/bhp-samarco-dam-collapse-brazil-linked-to-ramping-up-production/7201022;.