By Pedro Gagliardi

[24 min read]

SUMMARY

This paper examines the costs and benefits of dry processing and/or dry stacking as alternative production methods for the current mining operations in Brazil. Both methods prevent the formation of tailings dams, which are created as a result of the extraction of iron ore. This paper carries out a cost-benefit analysis which tries – firstly – to quantify the benefits for society of avoiding tailings dam collapses like Marina in 2015 and Brumadinho, in 2019, and – secondly – estimate the cost related to investing in dry processing methods for mining; the changes in production costs; and the cost of decommissioning current tailing dams.

A comparison of the costs and benefits show a vast net benefit for investment on these two alternative methods. Reaching a maximum net present values of R$ 5.5 billion and R$1.9 billion the study, therefore, concludes that the modernization of the mining operations and the switch to either dry processing or dry stacking in Brazil would be economically feasible. Both present values were estimated to avoid future tragedies and were based on in case Mariana and Brumadinho`s tragedies could be prevented, respectively. Additionally, considering that Vale is the largest company in the sector – responsible for almost 80% of the entire production of iron ore in Brazil, this paper urges Vale to decommission its 10 remaining upstream tailings dams (ANM report, 2019) – as well as other tailing dams types – in order to avoid another disaster and also to incentivize the whole sector to modernize its operations promptly. The following table represents the present values for the costs and benefits, which will be discussed on this report.

The costs shown above are related to the initial investment in dry processing technology; the cost of the decommissioning of dams; and changes in production cost due to the use of a different mining method.

On the other hand, the benefits are both the avoided costs that mining companies like Samarco and Vale would achieve through the adoption of alternative mining approaches and the prevention of future dam collapses like those in Mariana and Brumadinho.  Benefits would also include the cost savings associated with not having to deal with the aftermath of these kinds of disasters such as removal of the sludge and reforesting of the areas impacted by the collapse; the aversion of the costs incurred by other private business in the affected areas; the emergency funds saved by the government;  and, last, but not least, the lives saved in the absence of these disasters;

Finally, this paper will address two different scenarios which correlate with the incidents in both cities. Because the main objective is to illustrate different possibilities to avoid similar accidents such as those in 2015 and 2019, this paper will use two scenarios –  “high volume” and “low volume” dams, respectively – representing dams such as Fundão Dam (Mariana) and Córrego do Feijão dam (Brumadinho) considering the volume of sludge in those dams.

Introduction

Four years after one of the worst environmental and humanitarian incidents in the country, Brazil  has once again witnessed a similar event within its territory. The most recent dam collapse, in Brumadinho, repeats the tragedy of Mariana in November 2015. The similarities of the two incidents only reinforces the discussion about the perils of upstream tailing dams and how much damage millions of cubic meters of sludge can cause to the environment and society.

Spreading approximately 55 million of cubic meters of sludge downstream through the Doce River, the collapse of the Fundão dam, owned by Samarco, in Mariana, has contaminated more than 74% of the river extension – around 650 km – as well as 1500 hectares of land (ANA’s Report, 2016). The collapse not only killed 19 people, but also directly and indirectly impacted more than 30% of the population – around 300 thousand citizens – living in the affected cities (Minas Gerais State’s Report, 2016).

If the gravity of Fundão’s failure was not enough, in January 2019, Córrego do Feijão’s dam – owned by Vale S.A – collapsed in Brumadinho, leaking more than 12 million of cubic meters of sludge into 310 km of the Pareopeba river and killing approximately 330 people (CNDH’s Report, 2019). While Mariana’s tragedy could be considered one of the worst environmental disasters in the country, Brumadinho’s is also certainly a humanitarian one.

Likewise, the credibility of one of the most valuable companies in Brazil – Vale S.A. – has been critically damaged due to its involvement in both incidents. With the risks of upstream tailing dams well-known, Samarco and Vale should have been aware of the possible consequences of dam failures and taken precautions to guarantee the safety of thousands of citizens and the environment. Instead, the damage cause by these two-dam collapses led to immense financial losses (Samarco, FR2018; Samarco FR2016) and dramatically impacted the lives of workers from these mining companies and other business (Minas Gerais State’s Report, 2016).

Interestingly, the solutions that could have averted these tragedies are well known in the mining industry. Requiring some initial investment, “dry processing” and “dry stacking” are two methods that could prevent accidents such as those in Mariana and Brumadinho, while still enabling the companies to run a profit. In other words, the costs of investing in these technologies are considerably lower than the potential damage caused by the collapse of dam to the companies, government and society as a whole.

Iron ore extraction uses so-called “beneficiation”, a process that improves the economic value of the ore by removing certain minerals (impurities), resulting in a higher-grade product.  The tailings, the watery sludge left over after the beneficiation process, is then traditionally stored in so-called tailing dams.

“Dry processing” is iron ore extraction without the use of water. In other words, the ore is simply crushed and sieved and then classified by its granulometry (the size of the ore) and, therefore, there is no need to use dams since the sludge is essentially dry. However, the method can only be applied in mines with high natural iron concentration. Vale’s S11D Eliezer Batista Complex, in Pará state, for instance, utilizes this technique because the iron content there is relatively high – 64% – when extracted (Vale, 2019). Minas Gerais state, on the other hand, has lower quality iron ore – 40% -, which makes the use of dry processing harder to apply.

“Dry stacking,”, on the other hand, reuses water during the extraction process instead of dumping it with impurities and thus, avoiding the formation of watery sludge. That is, when reusing the water in dry stacking, the extraction process creates dry waste that can be stored in piles in which avoids the need to build dams.

The purpose of this paper, therefore, is to present a cost-benefit analysis for alternative mining methods that could supplant the need for tailing dams. The recommendation of this paper is based on several factors that could outweigh the expenses of investing in the new technologies. Considering the difficulty to monetize some of the benefits and costs as well as the limited access of crucial information, the results presented are essentially an attempt to further the discussion of alternative mining methods, especially given the importance of this sector in Brazil’s economy.

Stakeholders

The incident in Mariana and Brumadinho has, directly and indirectly, impacted every member of Brazilian society. Although the costs of investing in new production methods presented in this paper are mainly borne by the mining companies, the benefits will flow not only to these companies, but also to the Brazilian government, other local businesses, citizens, and the environment.

It is important to restate that the mining sector imposes risks onto the population and the environment and that mining companies should be responsible not only for protecting their own workers, but all members of society. This paper highlights the need for better public policies that can regulate and serve as a guideline for the mining sector in Brazil.

This study only encompasses the situation within the Brazilian territory. Other stakeholders such as foreign companies and clients affected by the changes in iron ore prices and its delivery because of these tragedies were not considered in this paper. Likewise, most data were collected from reports referring to Brazil`s mining conditions and geography and, thus, the recommendation from this report may vary if analyzed in a different region.

Costs

     I.         Estimated Investment

Both incidents have put more pressure on mining companies to modernize their mining methods and remove tailing dams. Based on different announcements made by the mining companies, this paper used the value of R$11 billion presented by Vale (Vale, 2019) as the cost of investing into dry iron ore processing over the next 5 years to increase. This report estimated that mining companies would invest per dam owned. Today, Vale has announced that 60% of its total production worldwide is dry in which is performed exclusively through dry processing (Vale, 2019). Likewise, the company has also declared that it intends to increase its dry production to 70% by 2023.  Considering Vale`s 111 existed iron ore dams (ANM report, 2019), this report considered these sites representing 40% of the company`s traditional iron extraction method production. Moreover, these sites include not only upstream tailing dams, but also downstream tailing, centerline tailing and Single Stage dams. Hence, since Vale aims to increase 10% of its total production as dry, this report would consider Vale`s investment over 27 existed dams.

Additionally, the same application was executed by other mining companies that are investing – or pledged to invest – in dry stacking such as: CSN Mineração investment of R$ 250 million/year (Estadão, 2019) for its 3 existed dams sites (ANM report, 2019), Usiminas investment of R$140 million (Usiminas` Financial Report, 2019) for its 4 dams sites (ANM report, 2019); and Gerdau investment of R$300 million (Reuters, 2019) for its 6 dams sites (ANM reports, 2019). Due to much smaller number of dam sites, this report considered the investments made these companies for all their dams proportionately.

  II.         Change in Production Costs Compared to Traditional Extraction Method

In order to estimate the total production costs of iron ore, firstly, it was estimated how much iron ore the Fundão and Córrego do Feijão’s dams produced during their lifetime based on how much sludge dumped during this time period. According to Brazil’s National Mining Agency (ANM, 2018), in 2017, Minas Gerais state produced approximately 406 million of tons of iron ore. The State Foundation for Environment in Minas Gerais (FEAM, 2018), concluded that mining companies dumped 290 million of tons of sludge into their dams in the same year. This paper thus uses an estimated ratio of 0.7: 1 sludge to iron ore produced.

Considering that the density of sludge is approximately 3.5 ton/m3 (SEMAD, 2018) based on information provided for another Vale-owned dam – Forquilha V dam -, it was possible to estimate how many tons of waste (watery sludge) was dumped in Fundão and Córrego do Feijão’s dams – 192 million and 42 million of tons, respectively. Using the above 0.7:1 ratio – this report estimated that the operations during the life-time of these two dams have managed to produce around 270 million of tons of iron ore in Mariana and 59 million of tons of iron ore in Brumadinho.

Assuming that the expenses related to the extraction of high-quality iron ore may change after the investment in and implementation of dry processing or stacking, this paper assumed a range of values – change in production and freight cost – for tons of iron ore. That is, the paper assumes a range where the production cost for dry processing (or stacking) could be cheaper than the traditional method and vice-versa. Thus, the minimum value for production cost would start from -R$31/ton^[1] (Vale`s investor report, 2018) meaning that dry processing (or stacking) would be more affordable.

Indeed, considering that 80% of Vale`s dry processing production locates in Pará state (Vale, 2019) the company has estimated a value of R$30/ton using this technique in one of its main sites S11D complex (Vale`s investor report 2018). Vale’s production costs using traditional extraction is approximately R$61/ton (Vale`s investor report, 2017), making dry processing costs per ton R$31 more affordable.

For dry stacking, this paper used an average production cost of R$115/ton[2] (Yilmaz and Fall, 2017) , compared to production costs of at least R$ 82.4/ton using traditional extraction methods (CSN`s Investor Tour, 2018) based on the fact that CSN has invested in this technology on Casa de Pedra`s site (Estadão, 2019) and has a somewhat higher than regular production cost than Vale’s R$61/ton. This means an increase in production cost for the dry stacking alternative method of around R$ 30/ton. Finally, this report considered a maximum change in production cost of R$62/ton for high volume type of dam, and R$130/ton for low volume type of dam, since both values are closer to the break-even point where the investment on dry technology would still be cost-effective as shown on the sensitive analysis of this report.

     III.         Cost per tailing dam decommissioned

Finally, mining companies would also need to decommission their current tailings dams, since they would no longer be necessary after the implementation of these alternative technologies; and they also present a threat to the environment.

The cost incurred to decommission one dam was based on Vale`s quarterly report (Vale, Q1 2019), in which the company announced spending of around R$7 billion to decommission 10 of its existing upstream tailing dams in the next 3 years; in other words, around R$ 700M per dam.

Benefits

Benefits of investments in alternative iron ore extraction methodologies are based on averted future catastrophic dam failings.   Based on the estimated annual probability of a tailing dam collapsing of  1 in 700 (Burritt and Christ, 2018) and the fact that Brazil has currently 336 dams of this type – plus other dams which were not classified – (ANM report, 2019), it was estimated that, on average, 0.49 dams collapses will occur in Brazil every year. This estimate is validated by the finding that in Minas Gerais state one dam collapses every two years as revealed by Milanez et al (2017). This same study illustrated the accidents in Nova Lima/2001 – Mineração Rio Verde; in Miraí/2006 – Mineradora Rio Pomba/Cataguases; Miraí/2007 – Mineradora Rio Pomba/Cataguases; in Congonhas/2008 – Companhia Siderúrgica Nacional; in Itabirito/2014 – Herculano Mineração; in Mariana/2015 – Samarco; and now in 2019/Brumadinho – Vale S.A.

     I.         Deaths Averted

To monetize the value of the lives that would be saved, this study used a Value of Statistical Life (VSL). According to a wage-risk study by the Brazilian Association of Graduate Programs in Economics (ANPEC), Brazil`s VSL per individual ranges from R$ 3.75 to R$ 4.69 million (Pereira et al, 2018).

Based on the assumption that the switch to dry stacking would avoid future dam collapses and related fatalities, it was used the average number of deaths in the last two collapses (19 people during the Fundao`s dam collapse and 333 people in Córrego do Feijão) and multiplied these fatalities with the above VSL, yielding a potential benefit of between R$ 43 to R$767 million in deaths averted. The reflect the wide range of fatalities that could be seen in future disasters, this report used the average of the above two values (176 fatalities and R$ 405 million).

** It was multiplied by 0.49 to consider the potential damage

     II.         Cost Averted – Sludge Removal and Cleanup

The expenses incurred to clean up and reforest the areas impacted by the dam collapses are definitely the hardest to be measured, considering that the damages inflicted by these disasters will last years, and that the total amount disbursed by the mining companies and the government might not be enough to reverse all the damage caused in the affected areas.  It is still uncertain how much Samarco/Vale as well as the government and society as a whole will pay for Mariana and Brumadinho`s tragedies.

In order to estimate the expenses that could be avoided for future sludge removal reforesting, this paper used a contingent valuation study, which measured the willingness to pay to recover and preserve a portion of land in Minas Gerais and formed the basis of so-called “Payment for Environmental Services (PSA[1])”, which are used by public institutions in Brazil to encourage farmers and landowners to protect the environment. In Minas Gerais State, one PSA initiative was the “Bolsa Verde[2]”, which paid farmers an amount of R$200 per year for each hectare of land they preserved.

After the incident in Mariana, Samarco created a foundation (“Fundação Renova”) to remedy the damages caused by the dam collapse. According to the foundation’s website (Fundação Renova, 2018), the institution used the above PSA concept and determined that it would take R$252/ha per year to incentive farmers and landowners to help in the clean-up in the areas contaminated and destroyed by the sludge. Hence, this paper utilized this information from Samarco and assumed that number to estimate the value of cleaning up and reforesting one hectare (or 0.01 km²) of land.

According to the ANA report (2016), 650 km of Doce river, covering an area of 61 thousand km² (or more than 6 million of hectare[3]), and 1,500 hectares of land were contaminated by the sludge. The same report states that the decontamination and reforestation would take at least 15 years. Thus, knowing the total area impacted; the time to clean up; and the cost per hectare, this paper concluded that Fundão’s dam collapse will require expenditures of R$20 billion to reforest and recover the area.

Assuming the same clean-up period, Córrego do Feijão’s dam collapse is estimated to cost R$2.5 billion. This amount was based on the contamination of 310 km of the Parapeoba River (ANA, 2019), which represents 56% of the whole extension of the river and encompasses an area of 6.8 thousand km². Additionally, around 112 hectares of land was affected by the dam collapse (SOS Mata Atlântica, 2019)

Estimations below represent the potential total clean-up and recovery costs for other dams with similar sludge volumes to the two involved in the previous disasters. In other words, for high volume dams the potential cost would be around R$ 11 billion (R$20 billion*0.49) and for low volume dam around R$1.2 billion (R$2.5 billion*0.49).

 * Values in Millions of R$ | ** It was multiplied by 0.49 to consider the potential damage

     III.         Losses Averted – Mining tailing dam owners

The estimations for Samarco and Vale`s losses were directly based on their financial reports. Initially, according to Samarco reports (Samarco, FR2018; Samarco FR2016), the Mariana`s tragedy caused a total of R$14 billion in expenses for the company between the years of 2015 and 2018 (including its cost of sludge removal). These numbers were based on the “Statement of Operations” table, which describes payments related to the Fundação Renova; fines and contingency fees; social, environmental and socio-economic remediations; and loss in property plant and capital/equipment destroyed or damaged by the sludge. Considering the probability of 0.49 for a potential damage, it was estimated, on average, a cost of R$6.9 billion for a mining company with dam of high volume referring to the damages caused by Fundao`s dam for Samarco.

Similarly, after the incident in Brumadinho, Vale has estimated losses around R$10 billion just for the first quarter of 2019 (Vale, Q1-2019). However, this paper is considering that Vale`s expenses will keep growing in the next few years. Thus, it is estimated that this value (R$10 billion) only represents an initial cost for Vale after the incident. This estimate, although open to revision, is based on figures in the Mariana case where the company disbursed more than R$7 billion (Samarco FR2016) only in the first three months after the collapse of the Fundão`s dam to remediate damages, which only represents 54% of the total cost of R$14 billion reached until the end of 2018.

Thus, assuming the same proportion made for Samarco, this paper considered a possibility of Vale having a total cost of $15 billion with Brumadinho`s tragedy for next three years. In that sense, the potential expenses for a mining company with a dam of low volume, similar to Corrego do Feijao`s Dam, would account, on average, for R$ 9 billion.

  IV.         Losses Averted – Private Sector (Others) and Public Sector

Following the logic of the previous benefit, the damages incurred to other business and the public sector were also estimated using data from the Mariana`s tragedy.

Mariana Tragedy

Minas Gerais State`s report (2016) categorized and analyzed the impacts from the collapse of the Fundão dam at the micro and macro-region level. The so-called micro-region considered in the report encompassed four cities, which were directly affected by the accident – Mariana, Rio Doce, Barra Longa and Santa Cruz do Escalvado, while the macro-region included approximately 28 cities within Minas Gerais State.

Illustrating the damages caused to the private sector, the report describes losses for agriculture, livestock farming, industry, commerce and service business across these regions. While the costs were estimated to be around R$38 million in the four cities making up the micro region, the larger macro-region saw losses of around R$287 million, adding up to more than R$325 million in expenses for the private sector in total.

Furthermore, the Minas Gerais State Report (2016) reveals that the emergency expenditures that the counties and the State incurred when the Fundão dam collapsed was around R$ 12.6 million. These expenses included medical cost to attend victims, transport around the area, staff and other urgent remediations.  For damages on infrastructure, the report assumed an estimated cost of R$ 513.7M after the disaster. Additionally, Samarco (2017) has issued a report in which estimated an indirectly lost more than R$1 billion in taxes during the years of 2016 and 2018 for the public sector because of the suspension of the company’s operations in the region.

Brumadinho Tragedy

This paper estimated the cost of this dam disaster based on numbers available from the Mariana incident due to insufficient data. Using a cost per cubic meter of sludge leaked of $1.59 and $7.50 per m³ of sludge, respectively, for the potential costs incurred to the private and public sectors. Hence, the total costs added up to total of R$90 million (Government) and R$19 million (Other private business) for Brumadinho.

** It was multiplied by 0.49 to consider the potential damage

Sensitivity Analysis

The analysis was based on the present values of benefits and costs related to the investment in dry processing or dry stacking. The analysis was run for 50 years.  It was assumed that the conversion to the new technology would take around 5 years (and the decommissioning of upstream tailing dams at least 3 years). This estimate was based on Vale`s investment announcement in the following years on dry processing (Vale, 2019).

Likewise, while the present values for the benefit in avoiding the expenses necessary for reforestation and cleaning-up in would be accounted for a time period of 15 years (ANA report, 2016), this paper had estimated a much longer period of 50 years in which it would take into account 45 years for the payment of reforestation and cleaning-up. The purpose to extend the period on this analysis was to simulate the longer positive scenario when investing on dry technology. Additionally, this same time extension was attributed to the other benefits as well the change in production cost from this report. Lastly, the analysis used a discount rate of 7%.

     I.         Investments & Cost of production

Considering the wide range of initial investment costs required to convert to these alternative technologies and the change in production costs, both of these variables were assumed to be significantly sensitive. Likewise, it was also considered the minimum starting points for dry processing (-R$31/ton) and dry stacking (R$30/ton) as discussed before.

The values were limited to Fundão and Córrego do Feijão `s scenarios. The positive present value could reach R$ 2 billion – Maximum in a dam with high volume of sludge – for dry stacking technology, whereas R$5.5 million for the dry processing technology. Additionally, the highest present value for dam with low volume of sludge was R$ 1.9 billion for dry processing and R$ 1.4 billion for dry stacking.

The values for investment were based on announcements previously mentioned and proportionately divided by the companied existed dams. In this sense, it is obtained: Usiminas → R$ 7M/year (Usiminas, 2018); Gerdau → R$10M/year (Reuters, 2019); CSN Mineração → R$17M/year (Estadão, 2019); Vale → R$21M/year (Vale, 2019).

Recommendation

This paper illustrated several outcomes when investing in alternative technologies that could supplant the use of tailing dams. Indeed, the results show not only how a change in the extraction process of iron ore affects investment and production costs, but also how much damage could be avoided by averting dam collapses.

The Mariana`s tragedy has caused more damage to society when compared to Brumadinho, but this is, of course, related to the dam size and how much sludge leaked from the tailings. For instance, Usiminas has two existing upstream dams – the Central dam and the Mina Oeste dam – that could have potential damages similar to those of the Brumadinho tragedy, since they have a similar volume of sludge (ANM report, 2019) to Córrego do Feijão `s dam. Indeed, according to the same report, 93% of upstream dams in Brazil have a volume similar or lower to Córrego do Feijão’s. Likewise, the results also demonstrate that for low volume dams dry stacking seems to be the best option of investment, when the benchmark was performed to determine the amount of money companies are willing to pay for this technology. 

Moreover, the net present values illustrate a wide range of possibilities – for both initial investment and future production cost – especially for Vale to invest in safer mining techniques. As Vale produces almost 80% of all iron ore produced in Brazil (ANM` Mineral production report, 2018) it is crucial that the company modernizes its operations and avoid other tragedies. Rather, by analyzing the sensitive analysis table and the range for change in production cost, Vale could still have large margin of earnings if investing on dry method for both dams with high or low volume. Indeed, the mining company could increase its production cost considerably in both scenarios, and still have financial space for profits.

Additionally, the sensitive analysis considered different levels of investment for dry stacking because Minas Gerais region has a lower percentage of iron content when extracted from mines. In other words, companies must use water and other chemicals to have a better iron quality before bringing to the market.

This report strongly recommends the implementation of the dry processing and/or dry stacking technique to supplant current mining technologies and the need for tailing dams. The net present value could reach R$5.5 billion for high volume dams and R$1.9 billion for low volume dam. Costs incurred for technology updates; future production costs; and the decommissioning of tailing dams are still significantly smaller than the benefits – or costs averted – if similar incidents to Mariana or Brumadinho could be prevented. Lastly, the costs as well as the benefits were estimations based on different reports and, therefore, they are open to revision and discussion.

[1] Vale officially reported a value of US$7.7/ton. This paper considered an exchange rate of R$ 4.12 Reais.

[2] Value of US$28/ton. This paper considered an exchange rate of R$ 4.12 Reais

[3] Access the “Instituto Estadual de Florestas” for more information: http://www.ief.mg.gov.br/florestas/pagamento-por-servicos-ambientais

[4] Access the “Instituto Estadual de Florestas” for more information: www.ief.mg.gov.br/bolsa-verde

[5] Access the “Instituto Mineiro de Gestão das Águas (IGAM)” for more information:   http://comites.igam.mg.gov.br/conheca-a-bacia-sf3

[6] The values were estimated based on their “expenses with social, environmental and socio-economic remediation” and “financial expenses provision for socio, environmental and socio-economic remediation”

[7] Estimations for 2019 and the following years

Bibliography

A study shows the impact of Samarco’s shutdown on the economy (2017). Samarco Mineração S.A. Retrieved from: https://www.samarco.com/en/noticia/estudo-mostra-impacto-da-paralisacao-da-samarco-na-economia/

Anuário Mineral Brasileiro: Principais substâncias metálicas, Ano base 2017 (2018). Agencia Nacional de Mineracao (ANM). Retrieved from: http://www.anm.gov.br/dnpm/publicacoes/serie-estatisticas-e-economia-mineral/anuario-mineral/anuario-mineral-brasileiro/amb_2018.pdf

Brandão, T. (2018). As ações e os desafios do Estado de Minas Gerais no incentivo ao Reaproveitamento de Rejeitos. Fundação Estadual do Meio Ambiente (FEAM). Retrieved from: http://www.feam.br/images/stories/2018/ASCOM_DIVERSOS/rejeitos-mineracao-economia-circular/Palestra__Renato_Brand%C3%A3o_-Feam.pptx

Brazil steelmaker Gerdau to invest in ‘dry stacking’ after Vale disaster. (2019, Feb 1). Reuters. Retrieved from: https://www.reuters.com/article/gerdau-drystacking/brazil-steelmaker-gerdau-to-invest-in-dry-stacking-after-vale-disaster-idUSE6N1WO02C

Burritt, R. & Christ, K. (2018). Water risk in mining: Analysis of the Samarco dam failure. Retrieved from: https://www.sciencedirect.com/science/article/pii/S0959652618300532

CSN Investor Tour: Casa de Pedra, 2018 (2018). Companhia siderurgica nacional. Retrieved from: http://ri.csn.mz-sites.com/wp-content/uploads/sites/102/2019/01/CSN-Investor-Tour_December2018_SEC_english.pdf

Desempenho da Vale no 1T19. (2019). Vale S.A. Retrieved from: http://www.vale.com/PT/investors/information-market/quarterly-results/ResultadosTrimestrais/vale_IFRs_BRL_1T19p.pdf

Encarte Especial sobre a Bacia do Rio Doce Rompimento da Barragem em Mariana/MG. (2016). Agencia Nacional de Aguas (ANA). Retrieved from: http://arquivos.ana.gov.br/RioDoce/EncarteRioDoce_22_03_2016v2.pdf

Especialistas discutem e informam sobre a evolução da qualidade das águas do rio Paraopeba e de Três Marias desde o rompimento da barragem em Brumadinho. (2019). Agencia Nacional de Aguas (ANA). Retrieved from: https://www.ana.gov.br/noticias/especialistas-informam-e-discutem-qualidade-das-aguas-do-rio-paraopeba-e-de-tres-marias-desde-o-rompimento-da-barragem-em-brumadinho

Extração SIGBM para classificação site – Atualizada 31jan2019. (2019, Jan 1) Agencia Nacional de Mineracao (ANM). Retrieved from: http://www.anm.gov.br/assuntos/barragens/pasta-cadastro-nacional-de-barragens-de-mineracao/extracao-sigbm-para-classificacao-site-atualizada-31jan2019/view

Financial Statements (2016). Samarco Mineração S.A. Retrivied from: https://www.samarco.com/wp-content/uploads/2017/09/Samarco_DFs-2016-versao-ingles-050917-final.pdf

Financial Statements (2018). Samarco Mineração S.A. Retrivied from: https://www.samarco.com/wp-content/uploads/2019/05/Samarco_Financial-Statements-2018-vf.pdf

Licenciamento Ambiental/ Barragem Forquilha V – Mina de Fábrica (2018). Secretaria de Estado de Meio Ambiente e Desenvolvimento Sustentável (SEMAD). Retrieved from: http://sistemas.meioambiente.mg.gov.br/licenciamento/uploads/8pvy_ZKUdWXpDotD9bp2BkG2ZNf0cQgU.pdf

Milanez, B. et al. (2016). Antes fosse mais leve a carga: Reflexões sobre o desastre da Samarco/ Vale / BHP Billiton. Retrieved from: https://br.boell.org/sites/default/files/a_questao_mineral-vol2_24out_3.pdf

Observando os Rios: O retrato da qualidade da água na bacia do rio Paraopeba após o rompimento da barragem Córrego do Feijão – Minas Gerais (2019). SOS Mata Atlântica. Retrieved from: https://drive.google.com/file/d/1kas2ZTBSfP2Xt35ezCWAFB2KY7_MuWvw/view

Payment for environmental services (PSA) will compensate rural landowners who promote environmental recovery actions. (2018) Fundação Renova. Retrieved from: https://www.fundacaorenova.org/en/news/payment-for-environmental-services-psa-will-compensate-rural-landowners-who-promote-environmental-recovery-actions/

Pereira, R. et al. (2018). O valor estatístico de uma vida: estimativas para o Brasil. Retrieved from: https://www.anpec.org.br/encontro/2018/submissao/files_I/i13-af55eb784dfed35cd3f24b230fe29216.pdf

Relatório da missão emergencial a Brumadinho/MG após rompimento da barragem da Vale S/A. (2019). Conselho Nacional Dos Direitos Humanos (CNDH). Retrieved from: https://www.mdh.gov.br/todas-as-noticias/2019/fevereiro/missao-emergencial-do-cndh-apresenta-relatorio-sobre-rompimento-de-barragem-da-vale/RelatrioMissoemergencialaBrumadinho.pdf

Relatório: Avaliação dos efeitos e desdobramentos do rompimento da Barragem de Fundão em Mariana-MG. (2016). Força Tarefa – Governo do Estado de Minas Gerais – Secretaria De Estado De Desenvolvimento Regional, Política Urbana E Gestão Metropolitana (Minas Gerais State’s Report). Retrieved from: http://www.agenciaminas.mg.gov.br/ckeditor_assets/attachments/770/relatorio_final_ft_03_02_2016_15h5min.pdf

Release of the 4Q18 and 2018 results (2019). Usiminas` Financial Report. Retrieved from: http://ri.usiminas.com/enu/5960/Release_4Q18_Final.pdf

Vale Day 2018 – Investor Relations. (2018). Vale Investor Report. Retrieved from: http://www.vale.com/EN/investors/information-market/presentations-webcast/PresentationsWebcastsDocs/Vale_Day_Transcript_2018.pdf

Vale planeja aumentar a parcela de produção a seco para 70% em 2023. (2019, Feb 6) Estadão. Retrieved from: https://economia.estadao.com.br/noticias/geral,vale-planeja-aumentar-a-parcela-de-producao-a-seco-para-70-em-2023,70002709986

Vale to invest 11 billion reais in dry iron ore processing over the next five years (2019, May 5). Vale S.A. Retrieved from: http://www.vale.com/EN/aboutvale/news/Pages/Vale-to-invest-11-billion-reais-in-dry-iron-ore-processing-over-the-next-five-years.aspx

XVII Analyst & Investor Tour: New paths for mining (2017). Vale Investor Report. Retrieved from: http://www.vale.com/EN/investors/information-market/presentations-webcast/PresentationsWebcastsDocs/InvestorTour2017_i%20vSite.pdf

Yilmaz, E. & Fall, M. (2017). Paste Tailings Management. Cham, Switzerland: Springer International Publishing AG.