Tag Archives: dry processing

Vale adapts iron ore processing route to make sand product for construction sector

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After seven years of research and investment of about BRL50 million ($8.9 million), Vale says it has developed a process for producing sand from its production processes with applications in the construction market.

After adaptation in the state of Minas Gerais’ iron ore operations, the sandy material, previously disposed in piles and dams, is now being processed and transformed into a product, following the same quality controls used in the production of iron ore. This year, around 250,000 t of sand has been processed and destined for sale or donation to be used in concrete, mortar, cement and road pavement.

According to Marcello Spinelli, Vale’s Executive Vice President for Iron Ore, the development of this product is the result of more sustainable operating practices.

“This action promotes a circular economy within our units and reduces the impact of tailings disposal for the environment and the society, in addition to being a reliable alternative for the construction industry, where the demand for sand is high,” he said.

Sustainable sand stock yard at Brucutu

Vale’s Sustainable Sand is considered a co-product of the iron ore production process. The material extracted in the form of rocks undergoes several physical processes in the plant, such as crushing, classification, grinding and concentration, until iron ore is obtained.

The innovation introduced by Vale lies in the concentration stage where the by-product of the iron ore processing is once more processed until it reaches the necessary quality to become sand for commercial use. In the traditional method, this material would become tailings and be destined to dams or piles. Every tonne of sand produced represents one less tonne of tailings being generated.

The sand resulting from the iron ore treatment is a 100% certified product, with high silica content and very low iron content, in addition to high chemical and granulometric uniformity.

According to Jefferson Corraide, Executive Manager of the Brucutu and Água Limpa Complex, the sand does not have hazardous characteristics in its composition.

“The mineral processing to obtain the sand is essentially physical, not altering the composition of the materials, so the product is not toxic,” Corraide said.

Recently, Vale’s sand had its application in concrete and mortar certified by three specialised laboratories in Brazil: Instituto de Pesquisas Tecnológicas, Falcão Bauer and ConsultareLabCon.

The properties of Vale sand are also being analysed by an independent study conducted by researchers from the University of Queensland’s Sustainable Minerals Institute (Australia) and the University of Geneva (Switzerland), who are investigating whether alternative construction materials produced from mineral ores could become a sustainable source of sand while significantly reducing the volume of waste produced by mining. These researchers introduced the term “ore sand” to refer to this type of processed sand sourced as a co-product or by-product of mineral ores.

Precast concrete produced with Vale’s Sustainable Sand

Production scale

Vale has already committed to allocating more than 1 Mt of sand for sale or donation in 2022. Buyers are companies operating in four different regions in Brazil: Minas Gerais, Espírito Santo, São Paulo and Brasília. It is estimated that, in 2023, production will reach 2 Mt.

Rogério Nogueira, Director of Ferrous Marketing, explained: “We are getting ready to scale up the sand destination even more from 2023. For this purpose, we have a team of professionals dedicated to this new business and adapting our operations to meet the market needs.”

Currently, Vale is producing sand for sale and donation at the Brucutu Mine, in São Gonçalo do Rio Abaixo (Minas Gerais).

Other mines of the company, also located in Minas Gerais, are in the process of obtaining environmental and mining approvals for sand production.

André Vilhena, Manager of New Businesses at Vale, said: “Our mines provide a sandy material that is rich in silica, which can be used in different industries. We are working with several institutions, including universities, research centres and Brazilian and foreign companies, to develop new solutions to give new destinations to iron ore tailings.”

In addition to using the existing infrastructure in the iron ore mines, Vale also has a railway and road network to transport the sand to markets in several Brazilian states. “With this activity, our main focus is on the sustainability of our iron ore operations, minimising the environmental liabilities, in addition to seeking to promote employment and income by means of new businesses,” Vilhena said.

Eco products

Vale has been carrying out tailings application studies since 2014. Last year, the company inaugurated the Pico Block Factory, the first pilot plant for construction products whose main raw material is tailings from mining activity. Installed at the Pico Mine, in the municipality of Itabirito (Minas Gerais), the factory promotes a circular economy in iron ore processing operation.

The Federal Center for Technological Education of Minas Gerais (CEFET-MG) provides technical cooperation with the Block Factory. Ten researchers from the institution are working on site during this period, including professors, laboratory technicians and graduates, undergraduates and technical course students. During the R&D period, the products will not be sold.

Another research initiative aims to develop the use of sand in pavement solutions in partnership with Itabira’s campus of the Federal University of Itajubá (Unifei). The focus is on the donation of sand for the pavement of local roads.

More sustainable mining

In addition to the Eco products line, Vale has other initiatives to make its mining more sustainable and reduce the generation of tailings. The company has been developing technology to increase the dry processing of its ores, which does not require the use of water. Currently, around 70% of Vale’s production is dry processed and this shall remain at this level when the production capacity of 400 Mt/y is reached and after the start-up of new projects. In 2015, this figure was 40%.

In Carajás, as the iron content is already high (above 65% Fe), the material is only crushed and screened to be classified by size (granulometry).

In Minas Gerais, in some mines, the average content is 40% Fe. By the conventional method, the ore is concentrated by means of processing with water to increase the iron content, with most of the tailings deposited in dams or pits. This is where another technology under implementation at Vale stands out: FDMS (Fines Dry Magnetic Separation). This technology sees the magnetic concentration of ores of low iron grade with no use of water, and therefore, with no need for dams.

Developed in Brazil by New Steel, a company acquired by Vale in 2018, this technology is already in use in a pilot plant in Minas Gerais. In 2023, the first commercial plant will start up in Vargem Grande, with a production capacity of 1.5 Mt/y and investment of up to $150 million.

Another technology which reduces the need of dams is tailings filtration and subsequent dry piling. Once the capacity of 400 Mt/y is reached, more than 60 Mt/y (or 15% of this total) will be processed in plants, where most of the tailings will be filtered and piled this way.

Vale has already opened a filtration plant in Vargem Grande and three more will be commissioned in the March quarter of 2022: one in Brucutu and two in Itabira. Only 15% of the production will continue to be processed by the conventional method, with wet concentration and disposal in dams or deactivated mine pits.

Vale starts dry iron ore concentration pilot with New Steel technology

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Vale has inaugurated its new dry pilot plant for processing iron ore in Minas Gerais, Brazil, as it continues to reduce its use of water in ore and waste processing.

The Brazilian technology, known as FDMS (Fines Dry Magnetic Separation), is unique and has been developed by New Steel – a company Vale acquired in late 2018.

The pilot plant, which cost $3 million, is the first step towards the construction of an industrial plant that will have a production capacity of 1.5 Mt/y. The investment in this project is near $100 million, with the commercial plant start-up scheduled for 2022, as the company announced back in February.

Vale estimates that, in 2024, 1% of all the company’s production will use this technology, whose patent is already recognised in 59 countries.

President of New Steel, Ivan Montenegro, said: “NS-03 is a semi-industrial plant to carry out tests on a pilot scale with different types of ore, allowing the definition of operational parameters for commercial-scale projects.”

Installed at Vale’s Ferrous Technology Center, in Nova Lima, the pilot plant is the second to start operating. Between 2015 and 2017, a unit operated at the Fábrica mine, also in Minas Gerais. The results allowed Vale to see the potential of the FDMS technology, it said, ultimately leading to Vale taking over New Steel.

The new pilot unit will be able to concentrate 30 t/h of ore using dry magnetic separation technology equipped with rare earth magnets.

Vale’s Executive Director of Ferrous, Marcello Spinelli, said New Steel puts the company at the “forefront” of investments in ore processing technology.

“We will continue to seek solutions that increase the safety of our operations,” he added.

With New Steel and its dry process technology, Vale estimates that, in 2024, 70% of production will come from dry or natural moisture processing, without adding water to the process and without using tailings dams. Today, the company produces 60% of iron ore using natural moisture processing.

By 2024, from the production using wet processing (30%), 16% will have filtered and dry-stacked tailings, with only 14% continuing to use the conventional method with wet concentration and tailings disposal in dams or deactivated extraction sites.

This transition will see Vale invest $1.8 billion in filtering and dry stacking in the coming years. The first units to use the technique will be Vargem Grande complex (in Nova Lima), Pico mine (in Itabirito), Cauê and Conceição mines (in Itabira), and Brucutu mine (in São Gonçalo do Rio Abaixo).

New Steel’s technology can deliver a concentrate with iron content up to 68% Fe from poor ore with content up to 40% Fe, depending on its chemical and mineralogical composition, according to Vale. Currently, this concentrate is produced by flotation, which uses water. In flotation, the tailings are usually disposed of in dams, but, with the dry concentration technology developed by New Steel, the tailings will be stacked.

Vale is studying methods to use these filtered cakes as raw materials for the civil construction industry, in addition to other initiatives, such as co-products.

Metso to help Gold Fields with dry tailings processing at Salares Norte

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Metso says Salares Norte, a Chile greenfield project owned by Gold Fields, has ordered three of its Vertical Plate Pressure Filters with all the ancillary equipment for dry tailings processing.

The order has been booked in Metso’s June quarter orders received, with the filters expected to be commissioned in October 2022.

Francois Swanepoel, Technical Manager at Salares Norte, said Gold Fields’ vision is to be the global leader in sustainable gold mining.

“The Salares Norte greenfield project is located 4,500 m above sea level in the Andean Mountains, where water is scarce and needs to be used wisely,” he said.

“To minimise the use of water and improve the physical and chemical stability of our tailings, we have decided to adopt filtered tailings for the project. Salares Norte will be a benchmark plant for dry tailings processing.”

Earlier this month, Outotec announced it would provide one 4 MW SAG mill and one 4 MW ball mill as well as five thickeners and one clarifier to be used in different process phases at the project.

Metso said Salares Norte was an exciting project for the company to work on as it considers dry tailings as the “most socially responsible and economically viable solution for tailings management”.

Patricio Mujica Dominguez, Senior Manager, Mining Equipment at Metso, said: “Besides the front-running tailings management solution, Salares Norte has challenged its partners to come up with other innovative solutions. The location of the plant at a height of almost 5 km above the sea level comes with its own unique challenges.

“For example, the design and transportation of the equipment, as well as commissioning, needs to be done with special care. To save manpower at such a high altitude, Metso will semi-assemble the filters in its service centres and deliver them in six specially designed easy-to-assemble modules to the site.”

A 2019 feasibility study on Salares Norte envisages an open-pit mining operation with an initial mine life of 11.5 years, producing 450,000 oz/y of gold-equivalent for the first seven years.

Vale to build New Steel plant and boost dry iron ore processing aims

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Vale says it plans to invest up to $100 million to build an industrial plant for dry magnetic concentration of low-grade iron ore, bolstering its efforts to eradicate wet tailings facilities at its mines.

The technology, known as FDMS (fines dry magnetic separation), is unique, Vale says, and has been developed by New Steel – a company it acquired in late 2018.

The capacity of the plant, which is expected to be installed in Minas Gerais, will be 1.5 Mt/y, with the project due to start up by 2022. Vale estimates that, in 2024, 1% of all the company’s production will use this technology, whose patent is already recognised in 59 countries.

With New Steel, Vale estimates that, in 2024, 70% of production will come from dry or natural moisture processing, without adding water to the process and without using tailings dams. Today, the company produces 60% of its iron ore using natural moisture processing. Of the remaining 30% of production using wet processing, 16% will have filtered and dry-stacked tailings, it said.

By this point, only 14% will continue using the conventional method, with wet concentration and tailings disposal in dams or deactivated extraction sites, compared with 40% of current production. The investment is all part of Vale’s $1.8 billion filtering and dry stacking plan, which it laid out in 2019.

The first units to use the FDMS technique will be the Vargem Grande complex (in Nova Lima), Pico, Cauê and Conceição mines (in Itabira), and Brucutu mine (in São Gonçalo do Rio Abaixo).
According to the President of New Steel, Ivan Montenegro, a pilot plant for FDMS will start operating at the Ferrous Metals Technology Center (CTF, Centro de Tecnologia de Ferrosos), in Nova Lima (Minas Gerais) in the June quarter, with the investment amounting to almost $3 million. The unit will be able to concentrate 30 t/h of dry ore, using magnetic separation technology with rare earth magnets.

“Through this process, New Steel can deliver a concentrate with iron content up to 68%, from poor ore with content up to 40%, depending on its chemical and mineralogical composition,” Vale said. “Currently, this concentration is produced by the method known as flotation, which uses water. In flotation, the tailings are usually disposed of in dams. With the dry concentration technology developed by New Steel, the tailings will be stacked.”

Vale said it is already studying methods to use these dry stack tailings as an input for the civil construction industry, in addition to other initiatives, such as co-products.

The pilot project at CTF is the second carried out by Vale. Between 2015 and 2017, a similar plant was successfully operated at Fábrica mine, in Minas Gerais, it said. These results were essential for Vale to see the potential of FDMS, according to Montenegro. “The technology, however, has been tested since 2013. At the time, the equipment allowed a concentration of 5 t/h, rising to 15 t/h in 2015 and up to 30 t/h in 2017,” it said.

To be aligned with Vale’s future projects, the company is working on the development of large-capacity magnetic separators of up to 100 t/h.

According to Technical Director of New Steel, Mauro Yamamoto, more than 10,000 test samples of ore from the Iron Quadrangle region of Minas Gerais have already been analysed by the company. Yamamoto points out that, today, with technology, 90% of the iron ore from a low-content deposit can be efficiently recovered.

Currently, New Steel seeks to reduce operating costs by using industrial microwaves to dry the product. It aims to replace natural gas dryers, thereby cutting energy costs in half. “It is a sustainable process, but we have the challenge of making it more competitive,” Montenegro said.

Vale’s Director of Ferrous Metals Value Chain, Vagner Loyola, said the company has been developing technology to increase dry processing for years. Over the last decade, Vale invested almost $17.8 billion to deploy and expand the dry – or natural moisture – processing of the iron ore produced in Brazil. Over the next five years, it estimates it will invest $3.1 billion in similar processing facilities to achieve the goal of 70% dry production.

In Pará, almost 80% of production already uses this technology in Vale’s North System. The main plant in Carajás, Plant 1, is being converted to use natural moisture processing; from its 17 processing lines, 11 already use dry processing and the remaining six wet processing lines will be converted by 2023.

The treatment plants at Serra Leste (in Curionópolis) and the S11D complex (in Canaã dos Carajás) do not use water to treat the ore. At the S11D complex, for example, the use of the natural moisture processing route allows water consumption to be reduced by 93% when compared with the conventional method of iron ore production.

In Minas Gerais, dry processing was expanded from 20% in 2016 to 32% in 2019. Today, this type of processing is used by several units, such as Brucutu, Alegria, Fábrica Nova, Fazendão, Abóboras, Mutuca, and Pico. “In Minas Gerais operations, all the units that could be converted to dry processing production are already in operation,” Loyola explains. “Then, we are using tailings filtering and stacking as well as the dry concentration technology from New Steel to reduce the use of dams.”

Dry processing is associated with the quality of the iron ore from the mine face. In Carajás, as the iron content is already high (above 65% Fe), the material is only crushed and screened to be classified by size (granulometry). In some mines of Minas Gerais, the average content is 40% Fe in itabirite. To increase its grade, the ore is concentrated through processing with water and the tailings are disposed of in dams. Then, the high-grade ore resulting from this process can be transformed into pellets at the pelletising plants to increase the added value of the product.

The plants that use dry processing in Minas Gerais depend on the availability of high-grade ore – around 60% – that can be found in some mines of the state. To achieve the required quality and be included in Vale’s product portfolio, this ore must be blended with the ore from Carajás – this blending is carried out at Vale’s Distribution Centers in China and Malaysia.

Vale exploring dry stacking/magnetic separation to eradicate tailings dams

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Vale has confirmed a Reuters news report from last week stating that it would spend an additional BRL11 billion ($2.5 billion) on dry iron ore processing over the next five years.

The company said it has invested nearly BRL66 billion installing and expanding the use of dry processing, using natural moisture, in iron ore production in its operations in Brazil over the last 10 years and it would carry on this trend.

“By not using water in the process, no tailings are generated and, therefore, there is no need for dams,” the company said, added that about 60% of Vale’s production today is dry, and the goal is to reach 70% in the next five years.

Dry processing is used in the mines of Carajás, Serra Leste and the S11D Eliezer Batista Complex (pictured), in Pará, Brazil, and in several plants in Minas Gerais. In Pará, in the Northern System, about 80%, of the almost 200 Mt produced in 2018 was through dry processing. The main Carajás plant, Plant 1, is in the process of conversion to natural moisture: of the 17 plant processing lines, 11 are already dry and the remaining six wet lines will be converted by 2022.

Serra Leste’s treatment plants, in Curionópolis, and S11D, in Canaã dos Carajás, also do not use water in ore treatment, according to Vale. In S11D, for example, the use dry processing, using natural humidity, reduces water consumption by 93% when compared to conventional iron ore production.

In Minas Gerais, dry processing increased from 20%, in 2016, to 32%, in 2018. Today, this type of processing is present in several units, such as Brucutu, Alegria, Fábrica Nova, Fazendão, Abóboras, Mutuca, Pica and Fábrica. “Over the following years, the objective is to roll it out at other locations in Minas Gerais, such as the Apolo and Capanema projects, which are currently under environmental licensing,” the company said.

Vale said: “Dry processing is linked to the quality of the iron ore extracted from mining. In Carajás, as the iron content is already high (above 64% Fe), the ore is only crushed and sieved, so it can be classified by size (granulometry).

“In Minas Gerais, the average content is 40% iron, contained in rocks known as itabirites. To increase the content, the ore is concentrated by means of wet processing (with water). The tailings, composed basically of silica, are deposited with water in the dams. The high-grade ore resulting from the process can then be transformed into pellets at the pelletising plants, increasing the added value of the product.”

The mills that operate dry processing in Minas Gerais depend on the availability of ore with higher levels – about 60% Fe – still found in some mines in the state. “In order to achieve the necessary quality, and be incorporated into Vale’s product portfolio, it is necessary to blend with Carajás ores, carried out at Vale’s distribution centres in China and Malaysia. The process allows Vale to offer excellent quality ore which can be tailored to meet the needs of our clients,” the company said.

The blending of the product with natural moisture does not eliminate the need for humid concentration of the low-grade itabirite used in the production of pellets. However, to reduce the use of dams, Vale plans to invest approximately BRL 1.5 billion on dry stacking technology in Minas Gerais between 2020 and 2023. This technique filters and reuses waste water and allows the latter to be stored in piles, thus reducing the use of dams. The goal is to achieve up to 70% of the waste disposed in the coming years, but success depends on the improvement of technology and external issues, such as environmental licences, Vale said.

“Today, Vale doesn’t have a dry stacking operation that can deal with the production quantity especially in a region with high rainfall indices, such as the Ferriferous four-side, in Minas Gerais. The available dry stacking technology is used on a small scale around the world – up to 10,000 t/d of tailings produced – in desert regions or with low rainfall. In Minas Gerais, Vale’s tailings production quantity is, on average, 50,000 t/d per unit,” Vale said. In 2011, the company developed a pilot project on the Cianita stack in Vargem Grande, after an investment of BRL100 million.

The studies were completed in 2018 and the technicians evaluated the geotechnical behaviour of piles under rainy conditions. The next tests will be applied on an industrial scale at the Pico mine in the municipality of Itabirito, Vale said.

“Another solution that has been studied is the dry magnetic concentration of iron ore based on the innovative technology developed by New Steel, a company acquired by Vale at the end of 2018 for BRL1.9 billion,” Vale said. “The dry magnetic concentration eliminates the use of water in the concentration process of the low-grade ore, which disposes the waste generated in sterile piles, similar to what happens in dry stacking. This technology, however, is in the industrial development stage and is not yet ready to be applied on a large scale.”