STUDY OF ALTERNATIVES FOR INDUSTRIAL RESIDUES GENERATED IN

THE PROCESS OF HYDROMETALLURGICAL PLANT OF CARAJÁS

Vale S.A.

Arcadis Tetraplan S.A.

HYDROMETALLURGICAL PLANT OF CARAJÁS

POND 01

POND 02POND 03

Autoclave

Solvent

extraction

Hydrometallurgical plant of Carajás (UHC) was design to produce 10.000 tpy of

LME grade A electrolytic copper.

•The process route was developed by CESL, a Canadian company.

Eletrolise

CHRONOLOGY

Event Period

Operation license April, 2008

Cold commissioning May, 2008

Autoclave start up September, 2008

First cathode November, 2008

Shutdown for maintenance June, 2009

Plant restart December, 2009

Plant shutdown for data treatment July, 2010

OVERVIEW

ENVIRONMENTAL ASPECTS

1. Liquid Effluents

No wastewater (totally recirculated);

Oil / Water separator (effluents from boiler);

2 compact sewage treatment.

ENVIRONMENTAL ASPECTS

2. Solid waste

Waste from maintenance and human activities;

Process of wastes.

3. Air Emissions

No significant gases, only vapor from the autoclave and evaporator.

Vents from the autoclave and steam generated in the

depressurization tank are scrubbed. The gases are washed in a

column for acid and particles absorption. After this process the

clean non-condensable gases are released through a stack;

There are acid vapours at ellectrowinning stage. Polyolefin beads

are used to control and minimize the mist.

ENVIRONMENTAL ASPECTS

4. Monitoring

Groundwater: 8 wells distributed upstream and downstream of ponds.

Identified metal concentration: iron, manganese, lead and nickel.

ENVIRONMENTAL ASPECTS

5 Work in progress: Characterization of the sub products generated

during the hydrometallurgical process and definition of theirs correct

disposal.Gypsum Pond Leach residue Pond

ENVIRONMENTAL ASPECTS

Gypsum Pond

Follow up and supervision of the sampling and characterization services

ENVIRONMENTAL ASPECTS

Leach residue Pond

Follow up and supervision of the sampling and characterization services

ENVIRONMENTAL ASPECTS

Characterization

. Analyzed parameters: Copper, gold, silver, iron, sulfur, silica (as

SiO2), calcium, magnesium, molybdenum, aluminum, nickel, cobalt,

arsenic, antimony, selenium, bismuth, fluor, chloride, lead, zinc,

cadmium, sulfate and acidity, NBR 10004, oils and greases.

Samples for geotechnical tests.

ENVIRONMENTAL ASPECTS

Gypsum Pond

Results: The estimated content of CaSO4 2H2O is 57%.

Classification: according to NBR 10004 residues contained in the

Gypsum Pond are Class II, not dangerous, but not inert.

Calcium sulfate can be used as raw material for sulphuric acid

production; flux material in the ceramic industry or in Portland cement

industries.

ENVIRONMENTAL ASPECTS

Leach residue Pond: contains noble metals like gold (average

concentration around 10g/ton) and silver. This material is being

analyzed by a Mineral Liberation Analyser (MLA) in order to find out the

most feasible process route.

Work in progress

Results consolidation and critical analysis (statistical analysis);

Evaluation and technical discussion of the considered alternatives;

Definition of the conceptual model and/or eventual pilot study to be

implemented for the considered alternative.

Safe operation: No accident linked to chemical plant characteristics;

CESL route can produce HIGH GRADE cathodes and it is technically feasible;

Staff is now able to operate similar plants in the world;

UHC residues are valuable (10 ppm gold, 33% sulphur), plus clean gypsum

is generated and can be utilized by construction.

MAIN CONCLUSIONS

SPECIAL THANKS

Pamella Alhucema / Omar Gaete – Arcadis S/A Chile

Fabiola Bustamante / Jesús Casas – Gecamin Hydrocooper

CESL – Canada

Gleuza Jesue / Eugenio Victorasso – Vale S/A