Presentation

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
Solvent
extraction
Eletrolise
Autoclave
POND 02
POND 03
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.
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.
MAIN CONCLUSIONS
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.
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