COMUNICAÇÃO TÉCNICA ______________________________________________________________________________________________________________________________________________________________________________________________________

Nº 175455

Mining tailings: the Brazilian mining industry and technological development for the tailings recovery Sandra Lúcia de Moraes

Palestra apresentado no ASISC Annual Meeting New Paradigms in Mineral Processing Technologies, 2018, Houghton.

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

The Brazilian Mining Industry and Technological Development for the Tailings Recovery

Sandra Lúcia de Moraes Chemical Engineer, Doctor

IPT - Laboratory of Metallurgical Process

August 9th, 2018

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Mining tailings

The Brazilian Mining Industry and Technological Development for the Tailings Recovery

Sandra Lúcia de Moraes Chemical Engineer, Doctor

IPT - Laboratory of Metallurgical Process

August 9th, 2018

The Mining Industry is a vital sector for the modern society, and has a broad impact on

both economy and population.

The Mining Industry is a vital sector for the modern society, and has a broad impact on

both economy and population.

Product Annual consumption

per inhabitant (kg)

Steel 116

Aluminum 8.3

Copper 1.9

Manganese 1.5

Gold 0.29

Zinc 1.29

Other metals 4.0

Fertilizer 27

Sand + gravel 3,700

Cement 320

Clay 1,220

Glass 8.75

Plaster 18

70 yr 328 ton 3,000 ton

life

expectancy

Consumed

Mineral

products

Generated

Mineral tailings

Each Brazilian consumes about

5.4 tons of mineral products / yr.

Each Brazilian consumes about

5.4 tons of mineral products / yr.

Source: Araújo, 2017.

Production of more than 50 mineral substances

Reaching US $ 40 billion in 2014, which corresponds to 5% of the country's industrial GDP.

In that same year, the sector was responsible for generating 214,000 direct jobs.

Despite its economic and social relevance, the mining activity also generates an huge amount of tailings.

The magnitude of the Brazilian mineral resources is translated into the: The magnitude of the Brazilian mineral resources is translated into the:

To discuss

strategies for

stimulate the

investment

and

development

in processes

for tailings recovery

• the generation of mining tailings in Brazil To quantify

• the actors involved in the mineral production chain

To identify

• the dynamics of the mining sector To understand

• the technical development level of the reuse of tailings To diagnose

This presentation provides a picture of the Brazilian mineral production chain,

its tailings generation as well as the level of technological development aimed

at the reuse of such tailings.

This presentation provides a picture of the Brazilian mineral production chain,

its tailings generation as well as the level of technological development aimed

at the reuse of such tailings.

82.5%

small and micro-sized

enterprises

The mineral industry in Brazil

Source: IBRAM [2017]

Brazilian mineral production (does not include oil and gas)

Brazilian Mineral Production - 2011, when it reached its

maximum value in US $ 53 billion, it was heavily

affected by the depreciation of mineral commodities,

mainly due to the sharp fall in the price of iron ore.

• The amount produced did not change

significantly.

Considerable volumes of solid materials not economically harnessed are generated from the mining activity,

constituting in waste, and classified as overburden and tailings.

The overburden is excavated without economic value,

individualized in the mining process, corresponding to the

layers overlying or interspersed with the ore

body.

The mining tailings result from the process of

beneficiation to which the ore is subjected, in which the impurities are removed

(gangue) to increase the quality or content of the mineral good, or when the product is sought to standardize separation of

crushed rock and sand by size).

One of the characteristics of the mineral industry is the significant volumes of masses of materials removed and moved from the mined areas. Of the amount extracted from the mines, only a portion results in the mineral product destined to the intermediary sectors (manufacturing industry) or final consumption (civil construction).

Mining and the generation of waste

Mining and the generation of waste

15 mineral substances • ~90% of the total gross mass production of

minerals, • the most important waste generators.

Source: IPT, from DNPM data 58 %

4,9 billion tons of tailings

accumulated in the period

(2000-2014)

Nine mineral substances individually, generate more

than 10 million tons of tailings annually: gold, iron,

copper, phosphate, titanium, tin, aluminum, zirconium

and niobium. Together, these substances are

responsible for the generation of 439.6 million tons of

tailings (85.3% of the total).

The mass ratio between the amount of tailings

generated and the amount of ore extracted is around

35.5%.

Amount of dams registered in the DNPM by processed mineral substance.

Source: Elaborated by the authors with DNPM data [2014]

Data from the Brazilian Register of Mining Dams [DNPM, 2014] were analyzed to contribute to the understanding of the distribution of tailings storage in the current Brazilian scenario involving mining tailings dams.

• The dams are located in 19 Federative units.

• The highlights are Minas Gerais (48%), São

Paulo (11%) and Pará (10%)

199 companies were identified responsible for 661 dams.

• 12 mineral substances have more than 10 dams each (92.4%)

• Most of the dams (42.3%) are associated with iron ore

production

Mining and the generation of waste

13 articles in the Constitution

44 decrees

22 laws

Other recommendations and technical notes

All related to the environment in the mineral

sector.

Mining tailings related:

Law No. 12,305 ( August 2, 2010) - National Solid

Waste Policy

Law No. 12,334 (September 20, 2010) - National

Security Policy of Dams.

LEGISLATION YEAR DESCRIPTION

Ordinance DNPM nº 70.389 2017

Creates the National Mining Dams Registry, the Integrated Management System for the Safety of Mining Dams and establishes the periodicity of execution or updating, the qualification of the technical managers, the minimum content and level of detail of the Dam Safety Plan, the Regular and Special Safety Inspections, the Periodic Safety Review of the Dam and the Emergency Action Plan for Mining Dams.

Ordinance DNPM nº 14 2016 Establishes deadline for presentation of proof of delivery of the physical copies of the Emergency Plan of Mining Dam (PAEBM)

Decree nº 46.933 2016 Institutes the Extraordinary Technical Audit of Dam Safety

Resolution SEMAD/FEAM nº 2372

2016 It establishes guidelines for conducting the extraordinary safety audit of tailings dams and for the issuance of the corresponding Extraordinary Stability Condition Statement.

Ordinance DNPM nº 526 2013

It establishes the periodicity of updating and revision, the qualification of the technical responsible, the minimum content and the level of detail of the Emergency Action Plan for Mining Dams (PAEBM) (Repealed by Portaria DNPM nº 70.389)

Resolution CNRH nº 143 2012 Establishes criteria for classification of dams (risk, potential damage and volume)

Resolution DNPM nº 144 2012 Guidelines for implementation of the National Dams Safety Policy

Ordinance DNPM Nº 416 2012 Creates the National Register of Mining Dams and provides for the Safety Plan, Periodic Safety Review and Regular and Special Safety Inspections for Mining Dams. (Repealed by Portaria DNPM nº 70.389)

Decree nº 7.404 2010 Creates the Interministerial Committee of the National Solid Waste Policy and the Steering Committee for the Implementation of Reverse Logistics Systems.

Normative Resolution COPAM no 124

2008 Complement the COPAM Normative Resolution no 87

Normative Resolution COPAM nº 87

2005 Changes and complements the COPAM Normative Resolution No. 62

Resolution CONAMA no 303 2002 It deals with parameters, definitions and limits of Permanent Preservation areas.

Normative Resolution COPAM nº 62

2002 Provides criteria for classification of retention dams

Ordinance DNPM nº 237 2001 Approves the Mining Regulatory Standards - NRM

Regulation of the sector

The accident occurred in Mariana – MG in 2015 promoted the discussion about the current legislation and encouraged companies and governments to adopt actions and publicize the efforts and results of innovation projects and minimization of tailings generation / recovery.

Companies actions on mineral waste

Government actions on mineral waste

Analysis of company and government actions in the mining tailings theme

Companies have announced projects to reduce energy consumption, reduce water use in processes and reduce waste disposal.

The dynamics of the mining sector is determined by economic aspects, legislation and by the knowledge and techniques dominated by the productive chain.

184 companies supplying equipment and inputs for

mining

• most are foreign capital,

• 80 have offices or representation in Brazil.

• São Paulo (53.3% of them),

• 37.2% are located in Minas Gerais.

Knowledge chain in the theme

• vacancies for undergraduate mining engineering

(292 in 2004, 2,505 current vacancies)

• research groups (68) - 41 Institutions of Science,

Technology and Innovation i(17 federative units).

• 95 research lines declared in the mining theme,

26% are directly related to wastes / wastes.

Knowledge/

Technology Economy Legislation

Dynamizers factors

Mining

Companies

Equipment

suppliers

Inputs

suppliers

User

Sectors

Productive chain

Government Financial

System

Others relevant actors

ICTs Fomentation

Innovation

Environmental

and regulatory

bodies

The Dynamics of the Mining Sector and Tailings

It is a consensus that

minerals are natural finite

resources and that the

quality of ore deposits has

deteriorated worldwide.

It is a 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

Technologies for ore recovery from tailings

• The liberation size of the

wanted mineral is generally of

the order of 100 μm. However,

due to the low-grade of the

deposits verified in the last

decades, finely disseminated

complex ores, whose liberation

is around 100 μm - 10 μm,

have been being processed.

• Gravity and magnetic

separation are by far the

oldest and mature mineral

separation technologies.

• Flotation is not fully

understood yet

The physical concentration are

and will still be the most used in

the industrial mineral

processing.

Equipment Technology Physical Property Concentration

process

Gravity

methods

Specific weight

(density)

Magnetic

methods

Magnetic

susceptibility Magnetic separation

Centrifugal

separation

Knelson Separator

Falcon Separator

Multigravity separator (MGS)

Kelsey centrifugal jig

Flotation Flotation, selective

dispersion Surface chemistry

Mechanical cells

Tank cells

Pneumatic cells

Canadian column

Hydrometallurgy

methods Hydrometallurgy Chemical reactivity

Electrostatic methods Electrical Conductivity Electrostatic separator Electrostatic separator

Jig

Tromps Vase

Tank leaching

Heap leaching

Bioleaching

Cross belt sorter

Permanent magnetic separator

(ETR)

Drum separator

Gill Separator

Jones magnetic separation

High-gradient separator

Eddy current separator

Ferrous Wheels separator

Slon Separator

Drum

Teska wheel

Dense medium cyclone

Dina Whirpool

Autogenous cyclone

Trough

Spiral

Reichert Cone

Shaking table

Jigging

Dense medium

separation

Separation in water

film

Mineral Processing Technologies

Prepared with information: Negeri T et al. Innovation, Research and development needs in mineral processing and extrative metallurgy. Canada Mining Innovation Council. 2008. NRC. Minerals, Critical Minerals and the U.S. Economy. National Research Council, Washington D.C., The National Academies Press, 2008.

Mineral Processing Technologies

Challenges and opportunities in the processing of finely disseminated complex ores and marginal ores.

Source: prepared by the authors with data from Wang et al.

(2014); Marques (2011); Silva et al. (2015)

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 (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.

Recovery by flotation as a function of particle size.

Source: adapted from Fuerstenau (1988).

Processed

mineral

Tailing /processed

ore (kg/ton)

% solids

(w/w)

Particle size

distribution

Coal 75 -120 5-55 > 75 µm (19%)

- < 4 µm

(66%)

Bauxite 1 – 1,5

Red mud/ produced

alumine

20-80 2 – 100 µm

< 5 µm (50%)

Copper 128 -196 > 75 µm (66%)

- < 1 µm

(34%)

Phosphate 375 5-45 > 75 µm (66%)

- <37 µm

(57%)

Iron 450-500 30-50 < 10 µm

Particles size (µm)

Re

cove

ry

Fines particles liberated Big superficial area . Need of much collector and little amount of depressor

Intermediate Fast Flotation.

Low use of collector, necessary to use

depressor

Coarse Particles Low liberation grade

Technologies for ore recovery from tailings

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

Mineral tailings recovery

Fine particles recovery

Mineral processing

Mineral dressing

Search criteria for scientific papers

Technical-scientific publications - mining tailings

Bauxite Kaolin

Coal Limestone

Copper Niobium

Gold Phosphate

Iron

Last 30 years Last 30 years

Number of papers by mineral substance (last thirty

and ten years)

Coal

Copper

Gold

Iron

Bauxite

Kaolin

Limestone

Phosfate

Niobium

Technical-scientific publications - mining tailings

32 %

17 % 12 %

485 publications

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.

Synthesis of the technologies applied to the tailings

recovery in the papers analyzed.

Emphasis is given on the use of established

techniques of mineral processing.

Source: prepared by the author

SIE

VIN

G

RO

TE

X S

IEV

E

Fe

DEW

ATE

RIN

G

Technical-scientific publications - mining tailings

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.

The papers were classified into:

• theoretical (23.5 %)

• market prospecting (3.0 %)

• experimental work (73.5 %).

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

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

1 2 3 4 5 6 7 8 9

Mining Industry

Filling for the mine pit

Agriculture

Soil Corrective

Civil Construction

Glazed coating

Walls

Decks

Mining Industry

Feasibility of

marginal deposits

Metallurgy/Siderurg

y

Metal recovery

Metallurgy/Siderurg

y

REEs Oxide

concentration

Metallurgy/Siderurg

y

Metal recovery

Metallurgy/Siderurg

y

REEs Oxide

concentration

Metallurgy/Siderurg

y

Bauxite concentration

Metallurgy/Siderurg

y

Dry processing

Metallurgy/Siderurg

y

REEs Oxide

concentration

Metallurgy/Siderurg

y

Iron ore

concentration

Agriculture

Artificial soil

Civil Construction

Cement artifacts

Civil Construction

Precast concrete blocks

Civil Construction

Geotechnical evaluation

Civil Construction

Geopolymer

Mining Industry

Disposal of tailings in

paste form

Mining Industry

Influency of washing

water

Mining Industry

Disposal of tailings in

paste form

Mining Industry

Sizing of the

dewatering system

Mining Industry

Maximization of

water recovery in the

pulp

Coal

Cupper

Gold

Iron

Bauxite

China Clay

Gravelstone

Phosfate

Manganese

REE

Technology development Exploratory development Real-scale development

Industrial production

Technical-scientific publications - mining tailings

The experimental works were

developed

64% on a bench scale

20% on an industrial scale and

4% on a physical model.

Importance of mining to the Brazilian economy

US$ 40 billion (2014)

Jobs

214,000 direct

And

2.7 million indirect

15 mineral substances (of 70 produced in Brazil, 2010),

correspond to about 90% of the national waste production, being also characterized as the most important

waste generators

9 mineral substances generated around 85% of

the total wastes.

Only 15 substances generated in 15 years about 4.86 billion tons of tailings

Iron, gold and phosphate production = 58% of the total

generated.

661 tailings dams

42.3% are associated with iron ore production

Conclusions

The context: Minerals are natural resources and are finite.

Low-grade of the deposits and submarginal ores - minerals whose 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 valuable minerals that has not been recovered and are discarded in piles or

tailings dams.

Documents written by researchers 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 2000s.

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 employed

conventional mineral processing techniques, not indicating any radical innovations in mineral processing.

China stand up in these studies, mainly in the development of high intensity magnetic separator.

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

development and exploratory of technological, i.e. 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

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

mineral chain allows inferring a provocation

The absence, in this chain, of 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 of to transform waste into

inputs for the production of new products

Universities Research

institutes

Metallurgy/

siderurgy

Civil construction

materials

Fertilizer industry

and agricultural

correctives

Technical textiles

industry

Intermediate

Mining

companies

detaining dams

Banks Foment

agencies Public funds

Development

banks

Chemical inputs

suppliers

Other inputs

suppliers

Mineral

processing

equipment

suppliers

Knowledge chain Financing sources

Public ministry Mining activities

regulatory agencies Environmental agencies

Dynamizer institutions of the chain

Conclusions

Opportunities and challenges of the new mining chain model.

• Research into new properties to separate materials

• Development new beneficiation technologies

• Creation of new fomentations dedicated to this subject

• Structuring projects based on business models

CH

ALL

ENG

ES

OP

PO

RTU

NITIES

• Knowledge and multidisciplinary teams in diverse CTIs

• CTIs partnership • Increase of sources of

specific funding in the sector • Partnerships between

mineral companies and users of raw material

Conclusions

Thank you!

sandralm@ipt.br

www.ipt.br/en