Tag Archives: sand

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

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.

Cedric Minería selects CDE EvoWash wet processing tech for Buin sand, gravel ops

Chilean mining and aggregates company, Cedric Minería, has announced a major overhaul of its aggregates business following a significant investment in advanced wet processing technology from CDE, the Belfast-based company says.

The family business, which expanded into aggregates production in 2003, has revealed plans for a new wet processing solution at its Buin operation.

Established in 1981, Cedric Minería specialised in the production of calcium carbonate and sulphur products before diversifying its interests and launching its silica operation, Mina Nancy, near the city of Calama in Antofagasta Region.

It soon secured listing as a strategic supplier of silica to state-owned copper mining company Codelco for its copper smelting plant in Chuquicamata, northern Chile.

Following the success of its silica business, Cedric Minería soon after commissioned its first aggregates processing plant in Buin which supplies the local market with a range of washed sand and gravel products for pre-cast concrete, asphalt, pipe bedding and more.

This summer, CDE will commission the EvoWash™ sand wash plant and an AquaCycle™ water management system at the company’s Buin site, replacing their existing washing screws.

Using CDE cyclone technology, the new plant will enable Cedric Minería to produce two grades of high quality, in-spec fine sands: 0-5 mm and 0-8 mm.

A compact, modular sand washing system, CDE’s EvoWash screens and separates the smaller sand and gravel fractions through an integrated high-frequency dewatering screen, sump and hydrocyclones which provide control of silt cut points and eliminates the loss of quality fines with significant commercial value.

An alternative to water extraction and the costly process of pumping water to the plant, CDE’s AquaCycle significantly reduces costly water consumption by ensuring up to 90% of process water is recycled for immediate recirculation, the company says. It helps to accelerate return on investment by maximising production efficiency, minimising the loss of valuable fines and reducing water and energy costs. A single, compact and user-friendly unit, it can be applied to high and low tonnages across many market sectors.

Cedric Minería owner, Cedric Fernández, says the investment in CDE technology is a significant step forward for the company.

“We’re making a huge technological leap forward with this new plant. Cedric Minería branched into the aggregates business almost two decades ago and throughout that time we have operated a traditional system,” Fernández said. “The existing plant has served us well, but we need a modern solution that is future-ready. Our latest investment in CDE wet processing technology represents the beginning of a new chapter for our company.”

Fernández says the COVID-19 pandemic had a significant impact on the construction industry but anticipates strong future demand for sand and aggregates to support the country’s public works investments.

CDE Business Development Executive, Gustavo Brasil, says older technology is very much under the spotlight for materials processors as they work to remedy inefficiencies.

“Recognising the limitations of the existing setup, the team at Cedric Minería are setting out on an ambitious transformation project to replace a traditional processing plant with a much more advanced and efficient technological solution,” he said.

The CDE solution engineered for Cedric Minería will revolutionise its current process, he added.

“CDE’s Evowash solution will enable Cedric Minería to produce superior fine sands with less moisture content while the AquaCycle water management system will deliver massive efficiency gains by recycling process water and driving down operational costs,” he said.

CDE wet processing solution allows SOVEVAM to access new markets

CDE has helped SOMEVAM, a subsidiary of the Sebri group, diversify into a new market by providing a tailor-made wet processing solution that eliminated contaminants and increased the quality of its end products.

SOMEVAM has operated sand quarries in Oueslatia, Tunisia, serving the national construction market since 2001.

Following testing of material, SOMEVAM saw the opportunity to diversify into the glass industry in North Africa and Europe, and produce a range of supplementary products, including industrial sand and silica flour. The company also wanted to produce a 30-150 micron fraction that would make its offer unique in the region.

SOMEVAM sought an effective wet processing solution that would eliminate contaminants and offer variable cut points to increase the quality and commercial value of the end products, CDE said.

Each day, SOMEVAM extracts 3,000 t of sand. To handle such quantities efficiently while also adhering to stringent quality standards requires the most advanced, durable and sustainable processing equipment, the company added.

“Together, the Tunisian company and CDE have developed a tailor-made wet processing solution to support SOMEVAM to achieve its commercial growth aspirations,” CDE said.

The design process, underpinned by CDE’s co-creation approach, allowed CDE engineers to work directly with the SOMEVAM team to develop a modular wet processing installation suited to the feed material (including a silica content of 99%) and the company’s production targets.

Habib Sebri, CEO of SOMEVAM, explained: “Before we got into glass sand, we operated the Oueslatia site for the production of building materials. However, it was clear that the material on site presented an interesting commercial opportunity in the field of silica for flat glass applications such as windows, mirrors and flat glazing.”

Sebri says it was important to invest in the right sand treatment equipment to guarantee the success of the project.

“After exhaustive research of the various options at our disposal, we chose a modular wet processing solution from CDE. The expertise of the company’s engineers and sales team, its investment in innovation and new technologies, and the quality of the materials used during the manufacturing process were the key determining factors in our decision.”

The CDE solution

To guarantee precise control of sand cut points, SOMEVAM opted for a complete turnkey CDE solution. The CDE plant has the capacity to treat up to 200 t/h of sand, producing 100 t/h of silica glass sand for the glass industry, as well as a range of secondary products including fine silica sand for silica flour production, foundry sand, concrete sand and road base.

The installation features a combination of CDE equipment operating in synergy: an M4500 primary wash plant to classify materials, five high frequency Infinity Screens™, four attrition cells, spiral separators, CDE’s Counter Flow Classification Unit (CFCU), a nano-cyclone, magnet, four EvoWash™ sand washing units and an AquaCycle™ water management solution.

Combined, the system processes fine and coarse materials and eliminates contaminants to produce high-specification glass sand, according to CDE.

Cutting-edge technology

“Since its launch in 2014, CDE’s M4500 has quickly become popular and is installed in plants around the world,” CDE said. “This high-tech plant is compact, powerful, easy to use and economical.”

CDE’s cyclone technology uses centrifugal force for classifying materials rather than gravity, which retains every grain of viable sand in the system, according to the company. The design of the cyclone also makes it possible to establish multiple variable parameters to obtain unrivalled cut-point precision, CDE says.

Attrition, spirals and magnetic separation processes are used to remove contaminates from the product and maximise the silica content.

Bassem Idriss, Project Manager for the Europe and MENA region at CDE, explained: “The M4500 demonstrates the effectiveness of CDE’s cyclone technology and the flexibility of our process and engineering teams, who have designed the process to produce very high quality glass sand to meet SOMEVAM’s requirements.

“The hydrocyclones were built according to the specific needs of the client, based on analysis of the feed material carried out by CDE during the pre-project phase.

“The process water, loaded with undesirable fines, is removed at the level of the overflow of the cyclones while the treated sand enters the dewatering and stockpiling phase. With cutting points of incomparable precision, the products are treated according to the required standards and without risk of mixing.”

Efficient water management

To produce a clean sand product requires a good supply of clean water, with the new installation incorporating CDE’s water management system, the AquaCycle thickener with a capacity of 1,500 cu.m/h. Waste water from the plant is processed by the AquaCycle thickener which recovers up to 90% of the process water to be recirculated back into the washing plant, minimising the size and maintenance requirements of the settling ponds, which is particularly advantageous where the site is situated in Tunisia, CDE says.

Idriss continued: “In Tunisia, a hot and dry country, it is important to consider the difficulties of accessing fresh water. It is essential not to waste a drop of water. CDE’s AquaCycle allows SOMEVAM to recycle process water in a closed circuit for immediate reuse in the system.

“The wastewater, after passing through the deaeration chamber and after having been in contact with the flocculant injection, passes to the centre of the AquaCycle so that the flocculation process operates and acts on the sedimentation of the fines. The integrated flocculation unit allows precise dosing of premixed flocculant for effective decantation. A single motor drives the AquaCycle rake arms for optimal sludge treatment before disposal.”

The result

The CDE installation for SOMEVAM transforms the feed material into five high specification products with exceptional commercial value, according to CDE.

It produces glass sand (150-650 microns) and related products, including oversized (3 mm) ready to be used in water filtration systems, coarse sand (650 microns-3 mm) ready to be ground to make flour silica, ultrafine (30-150 microns) for ceramics or other industries, and iron-rich sand that can be used in sports fields. With a typical moisture content of 12%, the materials are market-ready straight from the belts, CDE says.

Sebri commented: “Our CDE solution has made a huge impact on the glass sand industry in Tunisia and in the North African market. It represents the most advanced technology available on the North African market and has enabled us to become ultra-competitive in an industry with extremely high-quality standards.

“Our glass sand is sold for the production of white glass, and the other fractions are sold for various industrial applications. Our quick return on investment was thanks to the power and efficiency of our CDE solution.”