COMUNICAÇÃO TÉCNICA ______________________________________________________________________________________________________________________________________________________________________________________________________

Nº 174931.1

Mining tailings: a perspective of the brazilian scenario - part 2: Technological development and new uses Sandra Lúcia de Moraes Flávia Gutierrez Motta Camila Peres Massola Eduardo Maziero Saccoccio Marsis Cabral Júnior

Apresentação no SIMPÓSIO DE

MINERAÇÃO, 18., 2017, São Paulo. Palestra... 18 slides. ABM WEEK 2017, Rio de Janeiro

A série “Comunicação Técnica” compreende trabalhos elaborados por técnicos do IPT, apresentados em eventos, publicados em revistas especializadas ou quando seu conteúdo apresentar relevância pública. ___________________________________________________________________________________________________

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MINING TAILINGS: A PERSPECTIVE OF THE BRAZILIAN SCENARIO - PART II: TECHNOLOGICAL DEVELOPMENT AND

NEW USES Sandra Lúcia de Moraes Chemical Engineer, Doctor, Head of Laboratory of Metallugical Process, Instituto de Pesquisas Tecnológicas, State of Estado de São Paulo - IPT

Flávia Gutierrez Motta Production Engineer, Doctor, IPT´s Planning and Business Manager, Instituto de Pesquisas Tecnológicas, State of São Paulo - IPT

Camila Peres Massola Mining Engineer, Doctor, Research, Instituto de Pesquisas Tecnológicas, State of São Paulo - IPT

Eduardo Maziero Saccoccio Chemical Engineer, Research, Instituto de Pesquisas Tecnológicas, State of São Paulo - IPT

Marsis Cabral Júnior Geologist, Doctor, Research, Instituto de Pesquisas Tecnológicas, State of São Paulo - IPT

October 4, 2017

Introduction

It is consensus that minerals are natural finite resources and that the quality of ore deposits has deteriorated worldwide.

• current techniques should be modified to be possible to work with fine and ultrafine particles, specifically flotation.

To process and to 'reconcentrate' the useful mineral contained in the tailings

• reduction of tailings dams.

Fundamental point to explore the environmental and economic potential of mineral tailings

• opportunities to develop the industrial competitiveness.

The reuse and disposal of mineral waste in an efficient, environmentally and socially responsible way

• Increasing investments should be made in research and development of technologies to minimize damage to the environment, and to adapt production processes to international standards of ecological efficiency.

According to the National Confederation of Industry [1] Knowledge and innovation are engines of the economy, projected for the period from 2013 to 2022.

Introduction

Our work “Mining tailings: a perspective of the Brazilian scenario” is structured in two parts. The first part highlighted the economic and social relevance of the mining activity to the country.

The second one, presented in this work, approaches the level of the technological development available for recovery tailings, and the new use that has been proposed for them. In this document, the authors also conclude the analysis and propose the creation of a new business in the mining value chain, so as to stimulate the sustainable development of this activity.

• Technologies used in mineral processing and their relationship with process efficiency; • Technologies evaluated and used for the use of tailings and their uses.

The content presented in this document is based on the following aspects:

• The survey carried out aimed to identify how the mining tailings theme has been approached in the scientific and business environment, to identify the innovations proposed and in which scale of processing have been evaluated. In addition, we tried to verify the new uses suggested for the tailings of the processed mineral substances.

In order to carry out the surveys, a number of secondary databases (article database and patent database) were consulted and primary data were also collected through interviews with professionals working in the field and specialists in the sector.

Materials and Method

After mining the ore it is necessary to separate the wanted mineral from the other minerals present in the ore, denominated gangue minerals.

Results and Discussion Rarely there are pure mineral species in nature

The step called ore treatment or mineral processing, aims to obtain the maximum value of a wanted mineral present in a mixture of mineral species. These operations are applied to mineral that aim to modify their particle size or their form, the relative concentration of the mineral species present, without chemical alterations.

At the end of the mineral processing, a concentrate of the wanted mineral is obtained. The tailings of the process are sent to the dams, which are geotechnical structures located in basins or valleys, destined to the retention of the mixture of solid residues and water resulting from the mineral processing.

Results and Discussion Mineral Processing Technologies

It is not possible to speak about tailings technologies without highlighting the technologies applied in mineral processing. In any particular case the method chosen will depend on the relative physical and surface chemical properties of the mineral and the gangue.

Results and Discussion Mineral Processing Technologies The challenges and needs of R & D & I integrate the various stages of mineral processing, from the mine to the products generated, seeking to increase efficiency, reduce energy consumption, increase the life of the mine and reduce the amount of tailings to be dispose. It is worth mentioning the need for the development of technologies to separate fine-grained minerals in the range of 20 μm to 5 μm and <5 μm.

Challenges and opportunities in the processing of finely disseminated complex ores and marginal ores. Source: Prepared by the authors.

Source: prepared by the authors with data from Wang et al. [8]; Marques [9]; Silva et al. [10].

Results and Discussion Technologies for ore recovery from tailings

Ideally the tailings should not contain the wanted mineral, but there is a high percentage of these minerals that are not recovered in the concentration process and go to this flow. In the case of iron ore, the iron content in the tailings can range from 10 to 60%.

According to Wolff [6], the mineral industry traditionally designates tailings as follows: coarse or granular tailings (greater than 50 μm); fine tailings (between 10 and 50 μm), and ultrafine slurry (particles smaller than 10 μm).

Proportions and world characteristics of tailings stored in dams.

Mineral processado

Proporção rejeito/tonelada processada de minério (kg/tonelada)

% sólidos (w/w)

Distribuição granulométrica

Carvão 75 -120 5-55 > 75 µm (19%) até < 4 µm (66%)

Bauxita 1 - 1,5 Lama vermelha/alumina produzida

20-80 2 – 100 µm < 5 µm (50%)

Cobre 128 -196 > 75 µm (66%) até < 1 µm (34%)

Fosfato 375 5-45 > 75 µm (66%) até <37 µm (57%)

Ferro 450-500 30-50 < 10 µm

Recovery by flotation as a function of particle size. Source: adapted from Fuerstenau [7].

Distribution of dams per unit of the federation (%). Source: Elaborated by the authors with DNPM data [2014]

The attempted of valorization of tailings generated by the mining industry has been widely evaluated in Brazil and in the world. There is an abundance of technical-scientific articles addressing the theme, both in the line of recovery of the wanted mineral contained in the tailings, and in its application in the most varied industrial segments

Results and Discussion Technologies for ore recovery from tailings

Patents evaluation on mining tailings issue The patents search on mining tailings: Carried out in November 2016 on the Orbit platform, using the following keywords: mineral processing, mineral processing, mineral

dressing, ore processing, each associated with the words tailings or waste, - Logical operator: (Mineral or Ore) And (Process + or Dressing) and (Tailings or Waste). - Performed on the title, subject and abstracts of the patents, considering only the active patents ("alive" = granted or

pending). The search result returned 11,028 patents: The object of these patents is related with two main technological domains: "Materials

and metallurgy" and "Chemical engineering".

Cooperative Patent Classification (CPC) of patents in mining tailings

Year of first claim of patents

Technical-scientific publications - mining tailings

The goal was to evaluate the state of the art of technologies used in mineral processing, either for ore processing or tailings

Results and Discussion

Assunto Periódico Substância mineral Mineral tailings

recovery Revista Escola de Minas -

REM Bauxit

e Kaolin

Fine particles recovery Minerals Engineering Coal Limestone

Mineral processing

International Journal of Mineral Processing

Copper Niobium

Mineral dressing Mineral Processing and Extractive Metallurgy Gold Phosphate

The Metals Society - TMS Annals Iron

Advanced Materials Research

Search criteria for scientific papers - last 30 years

485 publications - 280 (58%) last ten years

The publications are concentrated in the periods 2009-2013 (Fe, Au and Cu) and 2001-2003 (coal).

Number of papers per year in the period 1986 - 2016.

Results and Discussion Technical-scientific publications - mining tailings

34 papers were randomly selected for reading (of he 485 papers located by the search) China stands out as the country that publishes the most scientific articles related to the subject of tailings (32%) of the analyzed publications. Canada is the second one (17%) and Brazil is in third place (12%) of publications.

Source of tailings, by mineral processed, described in the technical-scientific papers analyzed.

Number of papers by mineral substance (last thirty and ten years)

Regarding to the technologies discussed in the papers, there is a strong predominance (41.5%) of the use of gravity or magnetic separations (22.6% and 18.9%, respectively). The search has no found radical innovation in mineral processing technologies.

Results and Discussion Technical-scientific publications - mining tailings

Synthesis of the technologies applied to the tailings recovery in the papers analyzed. Emphasis is placed on the use of established techniques of mineral processing. Source: prepared with information from [11] - [43].

The selected papers were classified in theoretical (8 review papers), market prospecting (1 paper) or experimental works (25 papers). Of these, 64% were developed on a bench scale, 20% on an industrial scale and 4% on a physical model. Using the denomination of TRL (Technology Readiness Level) it is possible to affirm that the great majority of the articles present results of development of technology (TRL 1 to 4) and in the initial stage of exploratory development (TRL 5).

Results and Discussion Technical-scientific publications - mining tailings

Among the new uses given to the tailings, after processing, stand out those that have as target market the civil construction industry and the obtaining of concentrates for the metallurgical and steel industries.

Level of technological development presented in the papers, types of tailings and new uses proposed.

The context: Minerals are natural resources and are finite.

Low-grade of the deposits and submarginal ores - minerals who liberation size has gone from

about 100 μm to something in the order of 100 μm to 10 μm.

However, the mineral processing plants were projected to operate in particle size ranges

between 50 μm and 100 μm.

tailings brings a high percentage of wanted minerals that has not been recovered and are

discarded in piles or tailings dams.

Documents written by technicians of countries with mineral tradition point as a great challenge

to improvement of the efficiency of the processes, the need of development of

technologies to process finely disseminated materials has been discussed since the decade

of 2000.

Many technical-scientific studies have been carried out worldwide in the tailings

theme - iron ore tailings are the most investigated

The investigations aimed at concentrating minerals contained in the various types of tailings

have made use of conventional mineral processing techniques, not indicating any radical

innovations in mineral processing.

China stand up in these studies, mainly in the development of magnetic separation equipment

of high intensity.

The level of technological development of the routes proposed in these studies, most of them at the level of development and exploratory of

technological, ie theoretical or bench level.

Although the Brazil has a robust legal framework and the tragedy of the accident with the Samarco tailings dam has encouraged discussion on the problem of tailings disposal, the problem is far

from being solved.

Conclusions

Conclusions

The analysis of the situation and the actions of the actors that make up the

mineral chain allows inferring a provocation - inexistence in this chain a link aimed at the use of tailings. The

use of tailings does not figure explicitly in the mineral chain, as a

business, neither for the mining companies nor for a third actor in this

process.

The Circular Economy approach is extremely

adherent to this context

This concept covers the need to transform waste into inputs

for the production of new products

Conclusions There are opportunities and challenges

for the construction of such a model.

Opportunities and challenges of the new mining chain model.

• The authors would like to thank the Technological Research Institute of the State of São

Paulo, the Support Foundation of the Technological Research Institute of the State of São Paulo and the Secretariat of Economic Development, Science, Technology and Innovation for funding the project "Mapping of tailings production of mining companies and the maturity of the technologies applied for their valorization", which generated the results presented in this article.

Acknowledgments

Thank you!

sandralm@ipt.br