REPROCESSING & RETREATMENT
Vale recently began reusing iron ore tailings deposited in the Gelado dam by extracting highgrade resources with the help of four Cutter Suction Dredges from Royal IHC
Tails of value generation
The industry is redefining what it previously considered to be waste and tailings on rising commodity demand and sustainability considerations tied to recycling spent resources . Dan Gleeson looks at some of the leading companies in this space
The industry ’ s approach to tailings and other areas often considered waste has changed dramatically in the last half decade . A series of fatal tailings dam disasters and resultant re-evaluation of dam construction has been behind much of this .
Dwindling high-grade and easy-to-access ore deposits , plus increasing demand for the metals needed to electrify the world , have also had a part to play . Stakeholder expectations around sustainable metal and mineral sourcing , too , has influenced proceedings .
This is leading more companies to look again at what they have on their books with a bank of new and innovative reprocessing and retreatment options at their disposal .
Vale ’ s ‘ triple-win ’
The last 12 months has seen an acceleration of collaborative industry efforts to tackle tailings and waste , with many of the world ’ s leading miners taking on the challenge .
Vale , Rio Tinto , BHP , OZ Minerals and Boliden have all pledged investment and resources to various projects looking to find alternative ways to deal with tailings , with many of the ideas having an economic value-generation angle to them .
At the recent Prospectors & Developers Association of Canada 2023 Convention , in Toronto , Canada , Vale Energy Transition Metals , a global supplier of nickel , copper , cobalt and platinum group metals , announced it was looking to accelerate commercial recovery of critical minerals from mine waste in partnership with the
Mining Innovation , Rehabilitation and Applied Research Corporation ( MIRARCO ) at Laurentian University , in Canada .
As part of efforts to reduce mine waste and capture additional value from mined material , Vale committed C $ 875,000 ($ 637,320 ) over five years to MIRARCO to support a new industrial research chair program in biomining and bioremediation .
The industrial research chair program , led by Dr Nadia Mykytczuk , will develop , pilot and work towards commercialising bioleaching and bioremediation processes including efforts to recover nickel and cobalt from low-grade pyrrhotite tailings and other waste .
Luke Mahony , Chief Technical Officer at Vale Energy Transition Metals , said : “ This builds on our extensive R & D history and proven track record of lab-to-plant process development and represents a significant opportunity for wastestream reprocessing here in Ontario . We see this as a triple-win , with potential to reduce liabilities , accelerate commercial recovery of critical minerals and capture additional value from mined material .”
The Government of Ontario is also contributing C $ 750,000 through the Northern Ontario Heritage Fund Corp to support this industrial research chair program .
In iron ore re-processing efforts , Vale has invested more than BRL50 million ($ 9.7 million ) and established partnerships with more than 40 organisations , including universities , research centres and domestic and foreign companies tied to potential applications . The objective is to
make Vale ’ s operations safer and more sustainable , promoting the circular economy and benefiting society .
This led to the development of its Sustainable Sand operations in Brazil , which has already successfully produced more than 800,000 t of product that can replace natural sand , extracted from riverbeds , with wide applications in the civil construction market .
Obtained from the treatment of iron ore tailings , Sustainable Sand is one of the company ’ s initiatives to reduce the use of dams in its operations in Minas Gerais , Brazil .
After adding its first mine – Brucutu mine , in São Gonçalo do Rio Abaixo – to this initiative in 2021 , the company has now added a second operation , Viga mine , to the Sustainable Sand mix .
In the state of Pará , Brazil , meanwhile , the company recently began commissioning the Gelado project to produce high-quality pellet feed by reusing iron ore tailings deposited in the Gelado dam since 1985 , when Vale began operating in the region .
The initial production capacity will be 5 Mt / y and the investment is $ 485 million .
The commissioning phase , in which performance and capacity tests with loading are being carried out , should last until the end of the first half of the year , when operations will begin on a continuous basis , according to Vale . After the conversion of Carajás Plant 1 to natural humidity processing , planned for the next few years , the Gelado project will reach its capacity of 10 Mt / y .
Over the last 37 years , Vale has been producing iron ore at Carajás and depositing the tailings in the Gelado dam . This material is composed of iron ore particles that could not be used in the original beneficiation process , alongside impurities such as silica and alumina . Using dredges , the tailings will be removed from the dam and sent back for processing at the plant .
The grade of the material extracted from the dam is already 63 % Fe . At the plant , the ore will undergo a magnetic concentration process in which a powerful magnet separates the ferrous particles from the silica and alumina , further increasing its quality . This is the first time magnetic concentration has been used in Pará ’ s operations , according to the Vale .
The end product is a pellet feed for the company ’ s plant in São Luís , in the state of Maranhão .
The sustainable character of the project is reinforced with the use of electric dredges , as
60 International Mining | APRIL 2023