Hundreds feared dead after collapse of mine tailings dam in Minas Gerais State, Brazil.

Ten people have now been confirmed dead and over 200 more are missing, following the collapse of a tailings dam at a Vale mining operated iron mine in Minas Gerais State, Brazil, on Friday 25 January 2019. The incident happened close to the Alegria Mine site where a similar tailings dam collapse in November 2015, resulting in 19 deaths and a major environmental catastrophe which is still causing problems today. The dam that collapsed this week is only about a fifth of the size of that dam, and is not thought likely to cause environmental problems on the same scale, but it is feared that the number of deaths will be much greater, as the dam was uphill of an encampment used by workers at the mine.

The remains of a mine camp in Minas Gerais State, Brazil, where it is feared over 200 people died when the camp was hit by a wave of slurry following the collapse of a tailings dam on 25 January 2019. Leo Drumond/Nitro/AP.

Tailings ponds are used to store sediment-laden waters from mines; such waters typically contain a high proportion of fine silt and clay particles, which take time to settle out of the water. The resulting water may be fairly clean, or may contain other pollutants (typically acids, either generated by the local geology or used in the mining process), and need further treatment. In some instances acid is added to such pools in order to dissolve the product, which is then released from the resultant chemical slurry by further treatment, however this is not a typical procedure at iron ore mines.

See also...

Follow Sciency Thoughts on Facebook.

Investigating the ancient iron-works of Meroe.

The ancient city of Meroe was located on the east bank of the River Nile, about 200 km to the north of Khartoum in modern Sudan. It was the capitol of the Kingdom of Kush from about 300 BC onwards, and excavations at the site have revealed an extensive network of highly decorated temples and palaces. The wealth of Meroe was built upon the production of iron, which began during the Napatan period of Kushite history (i.e. the period during which Kush was ruled from Napata, before rule of the kingdom was moved to wealthier Meroe). The geology of the area around Meroe is dominated by iron-rich sandstones, which are presumed to have been the source of the iron produced in the city, although this industry has not previously been the subject of archaeological investigations.

In a paper published in the journal Azania: Archaeological Research in Africa on 3 October 2018, Jane Humphris of UCL Qatar and Hamad ibn Khalifa University, Robert Bussert of the Institut für Angewandte Geowissenschaften at Technischen Universität Berlin, Fareed Alshishani of the American Center of Oriental Research, and Thomas Scheibner of Archaeological Research and Service, describe the initial results of an investigation into the ancient iron-works of Meroe that began in 2012.

The area to the east of Meroe is dominated by a tableland of plateaux where the Late Cretaceous Shendi Formation is exposed. This formation comprises cross-bedded or ripple cross-stratified, fine-to-medium-grained quartz sandstones and kaolinitic mudstones, laid down in alluvial to shallow marine environments of a low-gradient coastal plain. These deposits tend to accumulate iron in their upper layers, which take on a dark-brown to black colour.

A plateau area to the east of Meroe, with a seasonal wadi bed marked by small outcrops of vegetation. Humphis et al. (2018).

Humphis et al. carried out investigations at a site identified as MMA 1, to the northeast of Meroe, where several in-filled depressions were found, which superficially resemble similar depressions at Timna in southern Israel, where archaeologists discovered ancient mine-shafts dug by copper miners. The people of Meroe are known to have had the technology to dig deep pit mines, as they dug deep wells, tunnel systems beneath their temple-complexes, and excavated gallery-mines to obtain stone for building. However investigation of the depressions found that they were in fact shallow pits, with material excavated from the digging work piled around their edges, which had then acted as sediment traps for wind-blown material.

Overview photograph of trench at MMA 1, with sediment traps visible in the background and the trench running through sediment traps of differing depths in the foreground. Humphis et al. (2018). 

A variety of artefacts were found at the site, including bricks and brick fragments, iron slag, pottery and a fragment of a stone statue. Some of the bricks had traces of plaster upon them, which suggests that the mine-workings included permanent structures used by people of some status. The pottery fragments were extremely limited compared to the other material, suggesting that pottery was not the main material used for carrying; Humphris et al. suggest that, given the environment, and the need to ship goods to and from the city of Meroe, baskets or animal-skins would have been more suited to this purpose anyway. The statue fragment appears to be part of a figurine wearing clothing resembling that worn by kings, queens and gods in statues seen in Meroe, and may be indicative worship being carried out on the plateau.

The stone fragment of a statue found at MMA 1. Bogumil Pilarski in Humphis et al. (2018).

A variety of iron-rich sediments were found on the plateau, though the highest concentrations of iron were found in the black duricrust at the surface, where iron is concentrated by the weathering of other minerals, which may explain why the ancient miners produced only shallow excavations. A variety of iron-ores were present, including goethite and haematite, as well as ferricretes and oolitic ironstones. Oolitic ironstones mainly consist of goethite and minor haematite and are surrounded by a fine-grained matrix of finely crystalline iron minerals, predominantly goethite. Such sediments form in wave-dominated inshore environments where the minerals are being precipitated out of the water onto grains beings moved constantly by the currents rather than settling on the seafloor where they would fuse together. At the MMA 1 site these oolites are often concentrated in lenses in depressions thought to be ancient sinkholes, formed by the collapse of caves beneath the surface, which are then topped by ferricretes, which could be used as an indicator of a source of high-grade ore. Experimental smelting of these oolitic ironstones by two experienced smelters, Lee Sauder of the Germinal Ironworks in Virginia, USA, and Jake Keen of the Ancient Technology Centre in Cranborne, UK, yielded better results than any other ore in the vicinity, work that is ongoing as the team attempt to reconstruct the methods used in ancient Meroe.

Thin section photomicrograph under plane polarised light of an oolitic ironstone sample from MMA 1 showing spherical, ellipsoidal and partly broken iron ooids in a fine-grained goethitic matrix. Humphis et al. (2018).

See also...

Follow Sciency Thoughts on Facebook.

Contractor killed at Tasmanian mine.

A contractor at an iron-ore mine on the west coast of Tasmania, Australia, on Friday 17 March 2017. The worker, identified as Nathan Beesley, 32, from Devon in England is understood to have been scaling (removing small fragments of rock by hand) on a rock face at the Grange Resources-owned Savage River Mine, when he was struck by a piece of falling rock and fell to his death. He is survived by a wife and two young sons.

Nathan Beesley, left, killed at a mine on the west coast of Tasmania on 17 March 2017. Katie Beesley/BBC.

Mr Beesley, a former Sergeant in the Royal Marines, had moved to Australia in the hope of joining the Australian Defence Force, however the process had taken longer than he anticipated, and he had taken alternative work whole waiting for an interview. His wife has expressed concern as to the future of the family, as they are not yet permanent residents of Australia and may be obliged to leave in the absence of a breadwinner.

The incident is under investigation by WorkSafe Tasmania. This is the fourth fatality at a mine on the west coast of Tasmania since 2013.

See also...

Follow Sciency Thoughts on Facebook.

Dozens feared dead following mining disaster in Minas Gerais State, Brazil.

Seventeen people have been confirmed dead and dozens more are still missing following the collapse of two waste dams at an open pit iron mine in Minas Gerais State, Brazil. The incident happened at Samarco Mineracão's Alegria Mine, which is jointly owned by Brazilian mining company BHP Bilton and Australian multinational Vale, happened on Thursday 5 November 2015, releasing a wall of water 15-20 m high which engulfed the village of Bento Rodrigues, which has a population of about 600 people, and reached about 7 km from the mine, sparking fears of pollution reaching the Gualaxo do Norte river.

 Devastation in the Brazilian village of Bento Rodrigues after it was hit by a flash flood following the collapse of two retention dams at a mine on 5 November 2015. TV Globo/ AFP./Getty Images.

Tailings ponds are used to store sediment-laden waters from mines; such waters typically contain a high proportion of fine silt and clay particles, which take time to settle out of the water. The resulting water may be fairly clean, or may contain other pollutants (typically acids, either generated by the local geology or used in the mining process), and need further treatment. In some instances acid is added to such pools in order to dissolve the product, which is then released from the resultant chemical slurry by further treatment, however this is not a typical procedure at iron ore mines, and was not employed at the Alegria Mine. However while the pollution caused by the breach of the ponds is likely to be less severe than caused by the breach of an acidified pond, deposits producing metal ores still often produce a variety of toxic chemicals in themselves, and the cleanup costs of such a spill are likely to be considerable.

 Damage caused by the 5 November 2015 mine dam collapse in Minias Gerais State, Brazil. Felipe Dana/AP.

The cause of the incident is not immediately clear. Both dams had passed inspections by local environmental officials in July this year. Seismologists at the University of Sao Paulo reported four minor Earth tremors in the region in the hour before the collapse, but a visual inspection of the dams carried out immediately had failed to reveal any problems, so it is unclear if the two events were collected. The mine will remain closed indefinitely while the incident is investigated, and the mine operators are likely to face calls for high levels of compensation and probably several law suits following the incident.

See also...

Fifteen missing after inrush at Colombian gold mine.                                                    Fifteen workers are missing following an inrush of gas and water at a gold mine at Riosucio in Caldas Province in the northwest of Colombia on Wednesday 13 May 2015. The incident reportedly happened during...

The role of gold mining in deforestation in tropical South America.                                   The rate of deforestation in South America has risen sharply since the 1990s, driven largely by economic growth in nations such as China, particularly the greater market for meat this has created, which has led to forests being felled both directly to create new pasture and to grow cattle-feed crops such as Soybeans. An increased disposable income in countries such...

Columbia gold mine collapse kills at least three.                                                               Three people are known to have died and about thirty more are missing following a cave-in at an unlicensed gold mine near Santander de Quilichao in the...

Follow Sciency Thoughts on Facebook.

Worker killed at mine in Pilbara Region, Western Australia.

A worker has been killed and a second injured in an incident at the Fortescue Metals Group's Christmas Creek Mine in the Pilbara Region of Western Australia. The incident happened in the mine's heavy vehicle workshop during maintenance work on a surface mining vehicle. Details of the incident have not yet been released, though it is understood the dead worker was a 23 year old contractor and the second is being treated for leg injuries.

 

The Christmas Creek Mine. Fortescue Metals Group.

The Christmas Creek Mine is an open pit mine located about 60 km South West of Nullagine and 1200 km northeast of Perth. As well as producing iron ore it also produces silica, aluminium and phosphorous minerals. The ore is processed on site then shipped by rail to Herb Elliott Port.

This is the second fatality at the Christmas Creek Mine this year, after a 26-year-old contractor from New Zealand was killed at the site on 14 August. The Department of Mines and Petroleum has ordered Fortescue Metals to tighten its safety procedures following this latest incident, and in particular to improve the supervision of outside contractors working at the site.

See also Two workers killed in accident at Tasmanian copper mine, Worker killed at Western Australia ore mine, Mining company fined for desecrating sacred site in Australia's Northern Territory, Acid spill from gold mine adds to Edith River's woes and Copper spill causes pollution alert on the Edith River in the Northern Territory, Australia.

Follow Sciency Thoughts on Facebook.

 

Magnitude 7.0 Earthquake off the coast of Peru.

The United States Geological Survey recorded a Magnitude 7.0 Earthquake at a depth of 40 km, roughly 17 km off the coast of southern Peru, slightly after 11.40 am local time (slightly after 4.40 pm GMT) on Wednesday 25 September 2013. This is a large quake with the potential to cause severe damage, and has reportedly triggered several landslides and caused partial or complete damage to at least seventy buildings in nearby areas, with adobe structures being particularly badly affected. The quake also caused damage at a number of copper and iron mines, with at least seven miners being injured, some severely, at different sites, though it appears that early reports of fatalities were inaccurate. Another ten people are thought to have been injured in Earthquake-related accidents outside of mines. The quake was felt as far away as Lima, 500 km to the north of the epicenter, and in northern Chile, 500 km to the southeast.

The approximate location of the 25 September 2013 Peru Earthquake. Google Maps.

Peru is on the west coast of South America and the western margin of the South American Plate, close to where the Nazca Plate, which underlies part of the east Pacific, is being subducted along the Peru-Chile Trench. The Nazca Plate passes under the South American Plate as it sinks into the Earth, this is not a smooth process and the plates repeatedly stick together then break apart as the pressure builds up, causing Earthquakes. As the Nazca Plate sinks further it is partially melted by the friction and the heat of the Earth's interior. Some of this melted material then rises through the overlying South American Plate, fueling the volcanoes of Peru and neighboring countries.

See also Magnitude 4.5 Earthquake in northeast Peru, Small eruptions on Mount Ubinas, Peru, Eruptive activity on Mount Sabancaya and Large Earthquake near Ica, Peru.

Follow Sciency Thoughts on Facebook.

Worker killed at Western Australia ore mine.

A worker was killed at the Christmas Creek Iron Ore Mine in the Pilbara Region of Western Australia, in an incident on Wednesday 14 August 2013. The man has been named as Kurt Williams, a 26-year-old electrician from Aukland, New Zealand, a contractor working for Crushing Services International at the mine, which is operated by the Fortescue Metals Group. The precise details of the incident are not yet clear, but it is reported that Williams was carrying out maintenance work on crushing machinery at night when he was killed. Operations at the mine have been suspended pending an enquiry into the incident, which is the first fatal accident at a mine in Western Australia in nearly two years, which will be carried out by the Department of Mines and Petroleum in Perth.

Areal photograph of the Christmas Creek Mine. Fortescue Metals Group.

The Christmas Creek Mine is an open pit mine located about 60 km South West of Nullagine and 1200 km northeast of Perth. As well as producing iron ore it also produces silica, aluminium and phosphorous minerals. The ore is processed on site then shipped by rail to Herb Elliott Port.

The Electrical Trades Union had previously raised concerns about practices employed by Crushing Services at mines in Western Australian, particularly the carrying out of maintenance work on live machinery at night by lone workers.

Kurt Williams with his girlfriend Peta Demeza. New Zealand Herald.

See also Mining company fined for desecrating sacred site in Australia's Northern Territory, Another worker killed in fresh Grasberg Mine cave in, 23 Miners still trapped after cave-in at gold and copper mine in Indonesian West Papua, Acid spill from gold mine adds to Edith River's woes and Copper spill causes pollution alert on the Edith River in the Northern Territory, Australia.

Follow Sciency Thoughts on Facebook.