Tag Archives: mine water management

Tronox boosts mineral sands dredging process with help of IPR-supplied SlurrySucker

Following a successful one-week trial, heavy minerals company Tronox Mineral Sands has taken delivery of a SlurrySucker dredging unit from Integrated Pump Rental.

The SlurrySucker will remove sand from the process dams near the Tronox mining operation on South Africa’s West Coast. This installation enhances the safety and efficiency of the dredging process, which previously had to be carried out manually by a team of underwater divers, IPR said.

“The pumping capacity of the dredging unit will ensure optimal operation of Tronox’s dams which need to be kept at the required storage volumes at all times,” Ruaan Venter, Rental Development Manager at Integrated Pump Rental, said.

The dredging unit will assist Tronox in regularly cleaning sediment from its process dams, reducing the risk of pump blockage or failure. This solution aims to provide rapid results on a cost-effective basis, while the remote operation raises safety levels, the company added.

To withstand the corrosive effects of salt water, the SlurrySucker has been equipped with a stainless steel casing as well as stainless steel components including wear plates and impellers. The units were manufactured at Integrated Pump Rental’s facility in Jet Park, Johannesburg, South Africa.

The SlurrySucker dredging unit comprises a floating barge with an electric hoist operated from the side of the dam. This ensures a high level of safety with the barge being operated remotely, including the lifting and lowering of the pump. At Tronox, the SlurrySucker is designed to pump 150 cu.m/h of sediment – with a solids content of 50% – back to the thickener in the plant.

“The electrically-driven unit also makes sure that there is no risk of contaminating the water in the dams with diesel or oil leakage,” Venter says. The compact unit is easy to transport between the dams requiring dredging, making for optimal usage of the equipment.

With its local manufacturing capability and technical support offering, Integrated Pump Rental says it is well equipped to maintain the SlurrySucker out of its Johannesburg facility.

Weir Minerals continues to go with the Multiflo in barge applications

Even with 40 years of custom barge solution expertise under its belt, Weir Minerals says it is continuing to innovate with new designs for applications in oil sands, tailings management and tropical and cold climates.

Developed over the decades, the Weir Minerals range of Multiflo® barges provides a solution for numerous applications, according to the company.

Water reclamation for oil sands market

Reclaim water barges are an integral part of tailings management solutions in oil sands applications, where tailings contain high percentages of water that can be recycled back through the process plant.

Upon identifying the need for reliable systems which were easy to manage and maintain, Weir Minerals developed its mega-barge exclusively for the oil sands market. This all in one package includes pumps, valves, hoses, and piping.

“This is where our turnkey value proposition really took off,” Kris Kielar, Product Manager for engineered-to-order dewatering products at Weir Minerals Canada, explains. “Our largest barge system includes a fully integrated electrical control houses that powers 9,000 hp (6,711 kW) worth of pumps, overhead cranes, remote monitoring and control, and the longest floated walkway we’ve ever provided, with ‘warm-up’ stations every 150 m for one kilometre.”

Mega-barges are the ideal solution for unique applications, such as the scale of water reclaim needed at some of the world’s largest oil sands operations, according to Weir Minerals.

“A typical oil sands operation requires nine barrels of water per barrel of bitumen produced,” continues Kielar, “so the more water that can be reclaimed, the better. The larger the operation, the bigger the water saving potential.”

In addition to the mega-barges for the oil sands market, Weir Minerals also developed modular barge packages as a fully customisable solution for ease of shipment, and a reduction in both capital costs and onsite installation costs. The introduction of both static and mobile, land-based, booster stations and pumphouses further expands the Multiflo barge solution capability while maintaining a single point of contact for customers, the company says.

Tailings management

The need for custom barge solutions for tailings management has increased in recent years. Where previously dewatering pumps in tailings applications were “set-and-forget”, the increased focus on tailings dam safety has shined a new spotlight on barge solutions that can provide heavy-duty, reliable pumping, Weir Minerals said.

Not only must sites revisit current arrangements to consider how their tailings will be handled in the future, they also need to empty the old dams decommissioned by environmental and mining authorities, the company said.

Ricardo Menezes, Barge Systems Specialist at Weir Minerals Brazil, said: “We are equipped to provide the entire solution. From initial consultation and design, to manufacturing, commission, and training and supervision of site operators. We work hard to bring our customers the best possible solution for their site, and we do it all under one roof.”

These all-in-one Multiflo packages eliminate the headache of integrating civil construction, electrical control rooms, control systems, pipes, cables, and mechanical and electrical works, according to the company. Weir Minerals engineer these dewatering barges in-house and employ naval engineering consultants to create tailored solutions for its customers.

Menezes continues: “Sites are being asked to transport tailings on a larger scale than before. An off-the-shelf solution might not work with their existing site infrastructure and that is where our fluid transport expertise comes in.”

Reliability in any situation

Applications in tropical environments, which experience heavy and sometimes unexpected rainfall, often require barge-mounted dewatering pumps to handle the rapidly rising water levels.

Multiflo land-based barges are built to float, protecting the pump unit from being flooded as often happens with a traditional skid pump unit, Weir Minerals says.

These land-based barges are fitted with integrated skid runners that allow them to be towed around mine sites and launched or retrieved with the use of dozers or excavators. The integrated skid runners also provide the added benefit of using the barge as a skid pump operating at the pond edge with easy land access for operators and servicing, the company says.

Marnus Koorts, Product Manager for dewatering pumps at Weir Minerals South Africa, says the company gets very specific requests for these land-based barges.

“We recently completed a project for a customer experiencing regular high wind speeds and tropical storms,” he said. “We needed to account for wave action and wind loading to ensure our solution would minimise risk of structural damage during these storms.”

Other considerations such as water quality, where pH can range from very low through to high, and water content, such as high percentages of suspended solids and floating debris, are also key to maintaining dewatering equipment on site, according to the company.

“Multiflo barges maximise reliability through innovative protection systems chosen specifically for the environment that the barge will operate in,” Weir Minerals says.

For one customer in South Africa, the Weir Minerals team needed to account for more than just water, according to Koorts.

“One of the design requirements for this particular installation was for the handrails and other structures to be engineered to prevent crocodiles from gaining access to the deck space.”

Dewatering in cold climates

In the last year, Weir Minerals barge specialists from Canada have been working with teams in Russia and Finland, to establish a European centre of expertise specifically for dewatering barges in cold-climate applications. Key environmental factors such as wind, snow and seismic loading can affect the buoyancy and stability of the barges, which they looked to address.

“We’re building on the work of the North and South American teams,” Artem Filippov, Dewatering Product Manager at Weir Minerals Russia, said. “Working together and using insights gained from their years of experience have allowed us to create unique barge dewatering systems for our European customers.”

Weir Minerals’ cold-climate expertise comes from experience in floating barge systems at temperatures below -45°C, de-icing systems and winter barge access systems. In addition, Multiflo barge systems are fully marine naval certified under all weather conditions and are marine architect certified, the company says.

Black & Veatch helps the water balance at Escondida

With BHP recently celebrating the completion of the Escondida Water Supply Expansion (EWSE) project at its majority-owned Minera Escondida mine in Chile, the designer and engineer of record, Black & Veatch, has taken the time to review its work on the more than two year project.

The expansion increases the mine’s desalination capacity to the point where 100% of its needs can be self-supplied with desalinated water, according to the company, helping to protect local groundwater resources while ensuring a more sustainable, resilient and reliable water future.

Black & Veatch served as designer and engineer of record on not only the EWSE project, but also the original Escondida Water Supply (EWS) project, heralded as one of the largest, most complex desalination infrastructure projects in South America, it said.

“Completion of the EWSE project comes amid mining’s growing focus on sustainability and resilience,” it said. “Minera Escondida is in the Antofagasta region in northern Chile, one of the driest regions in the world and water is at a premium. With the Monturaqui Aquifer closing in late 2019, BHP, the mine’s majority owner and operator, realised the need to bolster desalination capabilities.”

The project builds upon Black & Veatch’s history of providing water production, water conveyance and desalination services to BHP. In 2013, the company was selected to lead the engineering design, procurement, field inspection and pre-commissioning for the marine and desalination elements of the EWS project, which was completed in 2017.

When it came time to expand the Escondida desalination facilities, BHP again turned to Black & Veatch, hiring the engineering company to serve as engineer of record for the water production, water conveyance and high-voltage components of the project; providing engineering, procurement, construction management services, pre-commissioning and commissioning services.

The EWSE project involved multiple components to increase desalinated water production capacity by 833 l/s while expanding water conveyance capacity by 1,438 l/s. The project began in June 2017 and was commissioned one week ahead of schedule, on December 25, 2019, according to Black & Veatch.

“The project was executed on a tight timeline, but Black & Veatch was well-positioned to deliver on this work, given our knowledge of the original EWS project and the client,” Jim Spenceley, Senior Vice President of Black & Veatch’s Mining business, said. “This knowledge allowed us to identify efficiencies, reducing the amount of time to construct and commission and allowing us to safely deliver EWSE ahead of schedule.”

The original EWS infrastructure was developed with expansion in mind, and Black & Veatch’s design allowed BHP to adopt an optimised solution that used the existing EWS footprint, helping to lower capital costs, it said. Replicating equipment used in the EWS project also helped standardise and simplify operations and maintenance, according to the company.

Iain Humphreys, Business Line Director and Head of the company’s regional office in Santiago, Chile, said: “Black & Veatch provided the in-depth knowledge and experience to undertake this strategic project on behalf of BHP and to successfully complete EWSE. Having worked on both projects really pays testament to the high skill level and deep experience of all our professionals.”

Between the two projects – the original EWS desalination plant and the EWSE – Black & Veatch worked more than 3 million worker-hours without a recordable safety incident, it said.

To complete the project safely, ahead of schedule and with the highest quality standards, Black & Veatch placed significant resources behind the project. A diverse international team contributed – the core team of local professionals located in Santiago was supported by Black & Veatch professionals from multiple US states, plus the UK, India, Chile, El Salvador, Cuba and Colombia. The project also had a 25% female participation rate, supporting BHP’s corporate goal of gender diversity.

Vale exploring dry stacking/magnetic separation to eradicate tailings dams

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.”