Sossego

Overview

The Sossego copper mine is located in the state of Para, Brazil. Access is by an 85 km road that links the mine site with the city of Carajas.

Sossego mine opened in 2004 and is owned by Vale S.A. The copper ore is mined by open-pit method, and the run-of-mine is processed by means of flotation.  Concentrate is shipped to the Ponta de Madeira maritime terminal in Sao Luis, Maranhao. 

Vale built a prototype plant (UHC) at Sossego to test a new medium pressure oxidation technology that allows them to treat concentrate from different mining operations. It was designed to process 35,000 tonnes of Sossego concentrate per year.

In 2011, the mine produced 109,000 tonnes copper and 90,000 ounces of gold.

Location

Sossego mine is located in the state of Para, Brazil. Access is by an 85 km road that links the mine site with the city of Carajas.

Brazil is the South America’s largest country.  It is also the world’s fifth largest country and has the world’s largest Portuguese speaking population. The country is one of the world’s fastest growing major economies.

Para is a state in northern Brazil most famous for the Amazon River and the namesake tropical forest. It enjoys an equatorial climate. Mining accounts for 14% of the state’s revenue.

Geology & Mineralization

Sossego is an iron oxide copper-gold deposit located in the southern part of the Carajas basin, Brazil, about 50 km south of the township of Parauapebas. Sossego is one of several iron oxide copper-gold deposits, which form an approximately 60 km west-east trending belt of discontinuous copper-gold mineralization.

Sossego has two main copper ore bodies, Sossego and Sequeirinho. It is hosted in intensely sodium metasomatized Archean volcanic and intrusive rocks. The ore is constituted by chalcopyrite, magnetite, minor pyrite, and trace molybdenite. Alteration minerals closely associated with chalcopyrite include amphibole, epidote, apatite, calcite, quartz, and locally biotite. Stable isotope data suggest that both non-magmatic and magmatic fluids participated in the Sossego hydrothermal system.

Mineralization at Sossego is epigenetic and of hydrothermal origin. The copper-gold ore is hosted in igneous rocks with volcanic arc affinity. Mixing of a magmatic fluid with a non-magmatic fluid is responsible for the ore formation.

As of December 31, 2011, proven and probable reserves totaled 154.1 million tonnes grading 0.81% copper.

Mining & Operation

Sossego is a conventional truck and shovel open pit mining operation.

Run-of-mine ore is hauled to the crusher and then conveyed to the mill for processing.

Processing

The run-of-mine is processed by means of standard primary crushing and conveying, SAG milling (a semi-autogenous mill that uses a large rotating drum filled with ore, water and steel grinding balls to transform the ore into a fine slurry), ball milling, copper concentrate flotation, tailings disposal, concentrate thickening, filtration and load out. Vale trucks the concentrate to a storage terminal in Parauapebas and then transport it via the EFC railroad to the Ponta da Madeira maritime terminal in Sao Luıs, in the state of Maranhao.

Vale constructed an 85-kilometer road to link Sossego to the Carajas air and rail facilities and a power line that allows us to purchase electrical power at market prices. The mine has a long-term energy supply contract with Eletronorte.

Vale has also built a prototype plant using the CESL medium pressure oxidation process, known as Usina Hidrometalurgica Carajas (UHC). The CESL process consists of copper mineral pressure oxidation in autoclaves, copper leaching from the oxidation residue, solvent extraction to produce a high purity electrolyte, and electrowinning to produce copper cathode. 

UHC was designed to process 35,000 tonnes per year Sossego concentrate, producing 10,000 tonnes per year of LME Grade A copper cathode.

In 2011, the mine produced 109,000 tonnes copper and 90,000 ounces of gold.

Environment & Community

As of May 2012, Sossego mining operation faced an investigation of two Amazon copper mines after allegations that it improperly used Indian lands and failed to replace forest cut to build a power line.

Vale replied by saying that while unaware of the investigation their mining operations are at least 50 km away from local Indian reservations.