Could the Carajás Mineral Province be a future global center for production of strategic minerals?

Does the Carajás mineral province, in the northern Brazilian state of Pará, have the potential to become a world hub to produce strategic minerals? According to some experts on the region, it does.

David Strang, the CEO of Ero Copper, currently engaged in setting up a new copper project in the area, points that Carajás is already one of the world's largest mining districts, outperforming widely cited areas such as Sudbury (in Canada), Norilsk (in Russia), and the Witwatersrand Basin (in South Africa).

"Carajás is potentially the world's most prolific production area for iron ore, copper, and nickel," Strang says, "although to this day it remains underexplored, mainly because one company, Vale, has been there from the outset."

Breno Augusto dos Santos, a geologist who has been in the forefront of discoveries at Carajás since the beginning and who has dedicated decades of work to surveying the region, says the potential for copper is very great. Salobo, now being worked by Vale, is a world-class deposit, he says, while there are at least five other known medium-sized deposits holding somewhere between 200 million and 400 million tons of ore with a copper grade of approximately 0.8 percent. The Brazil Geological Survey, still officially known by the extended acronym SGB-CPRM, has published a report under the title Assessment of the Geoeconomic Potential of the Carajás Mineral Province, in which the current figure for copper resources plus reserves in the Carajás area adds up to 23 million tons of metal content. Reserves (proven and probable) are stated as 2.55 billion tons, with a copper content ranging from 0.6 percent up to 2.1 percent. Of the thirteen deposits that have been identified, nine are held by Vale: Alemão, Cristalino, Furnas, Paulo Afonso, Pojuca, Salobo, Sequeirinho, Sossego, and 118. The other four are Antas and Pedra Branca (both held by Oz Minerals), Jaguar (Centaurus), and Tucumã, formerly known as Boa Esperança (Ero Copper). In all thirteen, the copper is found in association with gold, with grade ranging from 0.30 to 0.86 grams per ton, the latter figure being observed at Alemão. In the same report, the Brazil Geological Survey notes that mining has now begun at four of those deposits, namely Salobo, Sequeirinho, Sossego, and Pedra Branca.

Salobo is now Brazil's top copper mine

Salobo is currently the star performer in Brazilian copper mining, with 1.11 billion tons of reserves having a 0.62 percent copper grade, in addition to 0.35 grams of gold per ton. Resources are stated as 529.8 million tons with 0.46 percent Cu and a gold content of 0.23 grams per ton. Its installed capacity is 200,000 tons per year of copper contained in concentrate, in addition to 200,000 ounces of gold per year — though gold output is now declining, having dropped from 331,000 ounces in 2020 to 215,000 ounces in 2022. The mine has been in operation since 2012 and has been through several expansion programs. The most recent of these, now in the rampup stage, raised capacity at the processing plant to 30 million tons of ore per year.

Thirty-eight years elapsed between the first discoveries at Salobo and startup of the mining operation. Mineralization of copper was discovered in 1974 in the vicinity of the Salobo River, and detailed exploration began in 1977. In the words of a Vale report, "A conceptual study was concluded in 1981, followed by pilot studies from

1985 to 1987, culminating in the award of a mining concession. A pre-feasibility study was concluded in 1988, the initial feasibility study was presented in 1998, followed by updates in 2001 and 2002. A final study was concluded in 2004. Operations at Salobo began with pre-stripping in 2009, and the first concentrate was produced in 2012.

For a time, the project was operated as a joint venture between the then state owned Companhia Vale do Rio Doce and Anglo American. The partnership was subsequently discontinued, leaving Vale in sole control of Salobo.

Although it was the first to be discovered, Salobo was not the first copper mine to be brought on stream in the Carajás mineral province. That was Sossego, a much smaller deposit, holding reserves of 86.2 million tons of ore having a 0.58 percent copper content and 0.19 grams of gold per ton, and resources of 322.6 million tons with a 0.80 percent copper content and 0.19 grams of gold per ton. Installed capacity is 100,000 tons per year of copper contained in concentrates, drawing on the output of the Sequeirinho deposit, where mining is fully integrated with the Sossego operation. The project became operational in 2004. Sossego and Sequeirinho are both open-pit mines, sharing a single processing plant. There are further satellite deposits in the region — Cristalino, 118, Bacaba, and Mata II, which may be mined in the future, once again with the ore being processed at the Sossego unit.

The Antas Norte project, belonging to Oz Minerals/BHP, is a processing plant that used to be supplied with ore from the Antas deposit, declared exhausted in 2021. Now it takes its ore from Pedra Branca, the first underground mine to have been opened in the Carajás mineral province, located in the municipality of Água Azul do Norte. The production plan for the Pedra Branca mine calls for mining a total 16.2 million tons of ore over a period of thirteen years, yielding 1.026 million tons of copper concentrate having an average 30 percent content, in addition to 216,600 ounces of gold and 31,000 ounces of silver.

Alemão will be Vale's next copper deposit to be brought into production. This will be the second underground mine in the Carajás region, since the top of the deposit lies at a depth of about 200 metres from the surface, according to geologist Breno dos Santos. Vale's figures show resources at Alemão amounting to 115.4 million tons of ore with a 1.49 percent copper content and gold assessed at 1.11 grams per ton. The Alemão deposit lies beneath the now exhausted Igarapé Bahia mine, from which Vale used to produce an average 10 tons of gold per year.

The Cristalino deposit, holding reserves of 379 million tons, with a 0.66 percent copper content, may possibly be the next on Vale's list, after Alemão, to be brought into production, says Breno dos Santos, in view of the nearby Rabo da Serra Sul iron ore deposit, where the company is already planning to start mining. There are other possibilities as well. With the single exception of Alemão, where the top of the deposit lies 200 metres below the surface, all the other copper deposits at Carajás are outcropping. In Santos' words, "There is no other copper-bearing district in the world, where the deposits are of hydrothermal origin, in which all the deposits are outcropping." At the same time, he is careful to point out that, "With more advanced research methods and using the appropriate geophysical prospection technologies, there remains the possibility that major copper-gold deposits may be detected at lower levels."

Even earlier than Alemão, however, Ero Copper's Tucumã project (previously named Boa Esperança) is due to come on stream before the end of 2024, implementation having started in the second quarter of 2022. With a useful lifetime estimated at 12 years, the venture is expected to yield 326,000 tons of copper, for a budgeted investment of US$ 305 million. The company says it expects that the potential for copper recovery, identified within an underexplored area at the edge of the pit, will improve the project by confirming that further mineralization is to be found between the high-content areas close to the surface and the areas adjoining the edges of the pit.

In the light of the large number of discoveries, the Carajás mineral province has attracted a rush of applications for mining rights. The same report from the Brazil Geological Survey notes that "a high density of mining rights, numbering almost 3,000, most of them still at the exploration stage, almost 700 now entitled to apply for a mining licence, 180 holding a mining licence, and 259 on a waiting list for availability. São Félix do Xingu is the municipality with the greatest number of mining rights, followed by Marabá and Parauapebas. More than half of the mineral deposits have now been licensed." Out of a total 2,992 mining licence in the region, 1,173 (39 percent) are for gold (including silver and minerals in the platinum group), 866 (29 percent) for copper, 217 (7 percent) for tin, 176 (6 percent) for manganese ore, and 137 (5 percent) for iron ore. Out of the 180 mines for which mining rights have already been awarded, seven are for iron ore, two for manganese ore, seventeen for copper, five for nickel, and 51 for gold.

Optimistic forecast

In the opinion of geologist Roberto Perez Xavier, the executive director of Adimb, the Brazilian Mining Industry Development and Innovation Agency, the outlook for Carajás voiced by David Strang, the CEO of Ero Copper, who sees the prospect of the area becoming a world hub for production of strategic minerals, is "rather optimistic, particularly if one is thinking in terms of a ten-year horizon." At the same time, he says, it is beyond doubt that Carajás has the potential to become, at some future date, "a world-class productive province, ranking among the ten most productive in the world." In terms of its geological age, he adds, the Carajás mineral province is the oldest of all those within the geological nucleus named the Amazonian craton, with large number of copper deposits, running east and west, within the so-called South Copper Sector and North Copper Sector.

Xavier estimates that, adding all the copper deposits together, the province holds approximately 4 billion tons of ore having an average 0.9 percent copper content by weight, plus 0.2 grams of gold per ton. The Carajás mineral province, he stresses, does not hold copper alone. It is a polymetallic province in which iron ore predominates, but it also holds manganese, nickel, copper, and gold, among other metals. From east to west, the province measures about 300 kilometers; from north to south, at its widest point, it measures about 100 kilometers.

Xavier recalls a further hindrance in the way of the full realization of the province's potential: the infrastructure question for bringing the more distant deposits into production, given that most of the deposits rank as medium or small and are consequently unlikely to attract any of the major mining companies.

He notes that the projects now in operation in Carajás, such as Sossego, Salobo, Pedra Branca, and Pantera, are of the polymetallic IOCG type. In addition to copper, they may also contain gold, silver, or anomalong grades of nickel, cobalt, rare earths, or uranium. Approaching the question from the geological side, he says, there are many questions that remain unanswered, including the evolution of the province itself. "We still have to identify the main controls that

have impacted these deposits over time and trace the evolution of the province over the course of geological time."

A comment often heard at mining industry events, Xavier says, is that the worldwide trend is toward deposits having a lower and lower metal content. The result is a growing awareness that a deeper understanding is needed about low-content deposits of that kind. Another frequent observation is that it is becoming harder and harder to find deposits reaching all the way up to the surface or at least to a depth of no more than 100 meters. While that may be true on a worldwide scale, Xavier says, it is not the case in Brazil, and that includes Carajás, where it is possible that a surface survey may still yield signs of an ore deposit. "In my view," he says, "there is still room for that in Carajás, despite the great intensity of exploration work that Vale has conducted there. It is my belief that, in Brazil, there is still a good chance of finding deposits that are up near the surface."

Unrealized potential

Marcos André Gonçalves, the chairman of Adimb, is another geologist who worked many years on the Carajás geological environment. He says he understands perfectly Strang's remark about the potential for energy transition minerals in the region. The Tucumã project is a case in point, he says. The discovery in 2006 of the copper deposit then known as Boa Esperança came as a surprise. He asks rhetorically, "How could somebody discover a copper deposit, holding 80 million to 100 million tons, right there in Vale's backyard?"

He agrees that Carajás still has great potential. "We have the star deposits, Furnas, Salobo, Sossego-Sequeirinho, and Igarapé do Gelado, but there is also a series of deposits that are already known though not in detail. They hold considerable volumes, in addition to other deposits such as Tucano, G34, and Pantera." He points out that, in a mineral province that Brazilians consider to be well-known, discoveries are still being made. The work that Centaurus is now doing at the Jaguar deposit, for instance, "brings a new dynamic in which good research interacts with entities such as Adimb itself, in the form of a joint project."

It is a long road, Gonçalves warns. It can sometimes take ten or twelve years, or even longer, to bring a deposit into operation. In his view, however, things are happening. "How many geologists working at Carajás can there be, he asks, "who don't know of deposits or smaller areas, holding maybe 60 million tons with a 0.8 percent metal content? There is the Pantera deposit, with a content of around 2.3 percent, of a size that might be too small for Vale, but not for some other company. So, I believe that Carajás still has potential, not only in copper but in nickel, too."

Like Roberto Xavier, Gonçalves too warns of the obstacles in the way of bringing the potential to full realization, in particular the infrastructure required, such as a second railway to ship out the ore — the existing railway is almost fully occupied by Vale alone — good roads and persuading the public of the benefits that realizing the potential will bring.

Like other geologists, Gonçalves has no doubt that, geologically, the province is bound to yield many further discoveries, although "discovery" does not necessarily imply "economic feasibility." "The discoveries already exist," he says. "What may still be lacking, either as the result of internal company policy or current market conditions or poor logistics, is the development of all these deposits. Many of them have, in fact, been known for quite some time. Some of the smaller ones, holding 50 million or 60 million tons, might have become operational by now if they were in a different state, such as Minas Gerais, especially in the context of present-day market conditions, with the energy transition and everything else."

One important difference is that the IOCG-type copper deposits in Carajás come with the bonus that they include recoverable quantities of gold. Some studies indicate a gold content of around 0.41 grams per ton, which in terms of feasibility can help to make up for a relatively low copper content, Gonçalves says. He also believes the region holds yet undiscovered copper deposits at greater depths.

Rodrigo Martins, another experienced geologist with a good knowledge of the Carajás geological environments, notes that

Brazil in general, and the Carajás mineral province in particular, still has abundant potential for new copper discoveries. He argues that Brazil's current output of around 400,000 tons a year represents no more than 3 to 4 percent of world copper production, and that 80 percent of Brazil's copper output comes from Carajás, mainly from two mines, Salobo and Sossego. That means there is the potential for expanding output.

"Vale has its growth strategy," Martins says, "and, once all the projects are in place, I believe Carajás has the possibility of reaching 500,000 to 600,000 tons of copper a year. It would have the potential for even greater growth, if it were not for the questions of economics, logistics, and project feasibility. There are many deposits there, but there is no way that they can all be explored at the same time."

Martins recalls a time when he was still working for Vale and an assessment of the general potential of the area concluded that it was very great. "But it's a long way," he says, "from that point on to the feasibility of every project. Vale is now readying Alemão, which is a new project, the Paulo Afonso group of deposits, and others. Supposing that the company achieves a copper output of 500,000 tons a year during a certain period, there are other projects, such as a small to medium-scale Ero Copper project, with an expected average output of 30,000 tons a year, among other small projects. In my view, we are going to hit a ceiling of 600,000 tons. That would be a good tonnage, but it is a long way from turning Carajás into a major player. It will be an important mining area, but there are now several porphyry mines in Chile and Peru with an output of half that size, between 300,000 and 400,000 tons of copper."

There remains the challenge, he says, of bringing more projects to fruition, because all the major discoveries have now been made. "What there is in Carajás today is extensions at greater depth, that may possibly become underground mines. Alemão will be Vale's first underground mine at Carajás, and that is highly important, with a potential of around 60,000 tons of copper, but the other deposits, in the eastern and western sectors alike, face the challenge of feasibility. One way to balance this would be increasing copper output in the area."

One possible route to boosting copper output, Martins says, would be placing the development of these small deposits in the hands of junior companies, following the lead given by Oz Minerals and Vale. "There are a number of small deposits that may be of no interest to the major companies," he says, "but they might attract small companies. However, that still does not open a realistic prospect of Carajás reaching a copper output of 800,000 or 1 million tons a year. In conclusion, there is potential, but realizing that potential is going to be a challenge."

In the case of nickel sulphide for transition materials, Martins names Jaguar as an important deposit, which he expects Centaurus — the company now holding the rights — to bring into operation in due course, either on its own or in association with another company. He estimates Jaguar's future output at around 30,000 tons per year.

In the case of lateritic nickel, the Brazil Geological Survey has identified three main deposits in the western sector of the Carajás mineral province: Onça Puma (assigned to Vale), Vermelho (formerly Vale but now Horizonte Minerals), and Jacaré (Anglo American). The three deposits together hold total resources more than 562.5 million tons of ore, with a nickel content ranging from 1.0 to 1.6 percent in addition to a cobalt content of 0.05 to 0.15 percent. "Additional resources are known in the Jacarezinho, Itapitanga, and Mundial Carapanã deposits. Sulphide ore reserves have been found in the Luanga deposit, now undergoing reassessment," the report states, adding that currently known resources and reserves in the Carajás mineral province are estimated at 7.17 million tons of nickel content.

However, all the laterite nickel deposits are being tapped to supply the steel industry. Unless significant changes are made to the processing facility, these deposits will not be able to supply the nickel required for the energy transition. Among these deposits, the most substantial is Jacaré, which Martins describes as one of the largest known laterite nickel deposits anywhere in the world. Bravo Mining has also reported a new nickel discovery, still at the exploration stage, whose true potential remains unknown.

Martins is confident that Carajás has the potential for new nickel discoveries, given the geology and the hydrothermal nickel in Centaurus's Jaguar deposit. "But testing this potential is going to take time," he warns. "Sulfide nickel exploration is lagging. Copper, for instance, is much more advanced. And then, of course, nickel has less potential than copper, and the research work is a little more challenging. I believe Carajás may become an important nickel producer, though not on a large scale, unless metallurgical solutions can be found for processing the laterite nickel found in these deposits."

Although it is now fifty-three years since Carajás was discovered and it has been very closely surveyed during all that time, the exploration has been comparatively superficial or "shallow", in Martins' words. "When I was working for Vale," he recalls, "I did an analysis that showed 95 percent of the boreholes were less than 500 metres deep. We then did some deep drilling, which confirmed the continuity of the copper mineralization. There is still a lot of exploration work to be done at Carajás, mainly in the western sector of the province, because the eastern sector is beginning to get exhausted. There remains the question of economics: can these deep deposits be feasibly mined? Martins repeats that he has no doubt about the potential of deep reserves at Carajás, based on his experience with gold when he was working for Anglo Gold Ashanti in Minas Gerais. At that time, he oversaw the deepest drilling ever conducted in Brazil, at depths of up to 1,400 metres (4,600 feet).

"We detected the continuity of mineralization in the Cuiabá mine," he recalls, "bases on the same concept that was applied in the same company's Velha mine, which reached a depth of more than 2,000 metres. We thought, 'If there's one known deposit at a depth of over 2,000 metres, why can't there be a second one?' So, we did the drilling to find out."

The IOCG system, such as is found at Carajás, is known worldwide for being deep-rooted, Martins says, citing the example of Olympic Dam, in Australia. The continuity of mineralization at Carajás is now mapped and confirmed down to a depth of 1,500 meters (5,000 feet), showing a metal content that in every case is at least of some interest. "However," he warns, "this has been done at only three deposits, Salobo, Sossego, and Alemão. It hasn't been done in any other region. Now Centaurus is drilling boreholes between 700 and 1,000 meters deep, and I have no doubt they will bring results. We have covered only the upper layer at Carajás, down to 400 or 500 meters. The surface is relatively well mapped. That means nobody is going to stumble across a new Salobo or a new Sossego. At the same time, there are other interesting prospects, mainly in areas held by Vale. And there's the possibility that something that doesn't look interesting on the surface may yield better geological results lower down. It's something to be looked into."

Summarizing, Martins is confident that Carajás has potential, though not to the point of joining the list of the world's leading players. "But it may possibly make a substantial contribution to Brazil's copper and nickel output," he says.

In some of the deposits, the gold content will be sufficient to tip the scales and make a mining project viable, Martins says. "Suffice it to say that Alemão is going to produce 60,000 tons a year of copper and 120,000 ounces of gold. Vale has sometimes used advance sales of gold to fund a new project, in some instances raising practically the whole amount of the capex. Gold can be a useful counterweight in times of crisis. When other metals are going down in price, gold goes up. That means the presence of gold in the system is a factor to be considered. There can be no doubt that, in the case of these IOCG deposits, gold will help with feasibility. Even in places where the mineralization of copper is capped with a very thick layer of altered soil," he adds, "sometimes gold that has been enriched through the supergene process will improve the prospects of the investment."