Tag Archives: apron feeders

Weir’s ore characterisation work shifts gears to value generation loop

Chris Carpenter, VP of Technology for Weir ESCO®, is on a crusade to educate the mining industry on the importance of orebody knowledge.

As an executive with more than 35 years of experience and 40 patents to his name, he has heard numerous stories about “sub-optimal operational decisions” being made at mine sites due to a lack of information.

Through an ore characterisation project under development within several teams at Weir, Carpenter shared the company is focused on developing cost-effective solutions to provide this information in real time.

He is, however, aware that the mining sector, as a whole, needs convincing.

“I can tell you that many of our customers do not yet acknowledge the full value of what we are looking to provide the sector,” he told IM.

This is changing, with industry studies on the correlation between poor orebody knowledge and negative financial impacts and risks in the mine development process coming to light – IMDEX, the Mineral Deposit Research Unit and the Bradshaw Research Institute for Minerals and Mining at the University of British Columbia and Ideon Technologies are, for instance, currently engaged on such a study.

In announcing the study, IMDEX Chief Geoscientist, Dave Lawie, hit on a similar theme to Carpenter: “For the mining industry to adopt this technology, it must have clear evidence of the financial impacts and risks of poor or no orebody knowledge and a way of assessing the most efficient methods of collecting, analysing and optimising it.”

What “this technology” is remains open to debate, with many pre-concentration and ore sorting technologies continuing to sprout up among fertile innovation soil in the mining sector.

ESCO and Carpenter believe this technology – at least in a base metals and iron ore application context – has roots in Sustainable Development Technology Canada (SDTC), an arm’s-length foundation created by the Government of Canada to fund new clean technologies. Motion Metrics International Corp received SDTC funding back in 2020 for a project using the core innovations of hyperspectral imagery (HSI) sensors, 3D particle size distribution (PSD) analysis and machine-learning algorithms to control energy-intensive mining equipment, an SDTC backgrounder from 2020 explained.

Chris Carpenter, VP of Technology for Weir ESCO

Motion Metrics, in a separate announcement, said the 3.5-year project would lead to the design, development and deployment of a commercial mine-to-mill energy efficiency solution.

“Upon successful completion, mines worldwide will be able to order and deploy this solution, without changing their daily operations, to meet their sustainability targets while reducing their comminution costs,” it said.

University of British Columbia’s Norman B. Keevil Mining Engineering Department and several other organisations partnered with Motion Metrics for this project.

A lot has changed in the four years since this announcement, with Weir Group having acquired Motion Metrics International Corp and been incorporated into ESCO.

IM initially reported on developments of what Carpenter referred to as an “ore characterisation” project in 2022. At that time, this consisted of a BeltMetrics™ trial installation using a MOTION METRICS™ advanced imaging sensor for PSD analysis and a commercial, HSI sensor positioned above a conveyor that was directly after the crusher in a mine’s flowsheet.

When IM caught up with Carpenter in late July, he could report on not only progress with the BeltMetrics installation, but also a fixed-term trial of “ore characterisation” in a TruckMetrics™ installation.

“We have now run two different applications for the technology,” he said. “The belt monitoring trial continues to operate and has demonstrated the ability to predict SAG mill throughput based on the input ore characteristics. We also ran a very successful trial of bulk sorting using similar technology looking at the content of haul trucks. The trial monitored and analysed around 1,000 trucks and several were identified as low grade. Extensive lab testing continues as we evaluate mine ore samples to understand the capabilities of our approach. Based on our lab and field evaluations we are convinced the technology will allow us to quickly and accurately monitor grade, alteration, deportment and deleterious minerals.”

The BeltMetrics trial installation uses a MOTION METRICS advanced imaging sensor for PSD analysis and a commercial, HSI sensor positioned above a conveyor that is directly after the crusher in the mine’s flowsheet

“I would say our proof of concept work has really allowed us to now pick up the pace of investment and search for more development partners to further this technology.”

The TruckMetrics ore monitoring trial – carried out on 100-232 t-payload trucks – may pique interest here, but Carpenter says the initial product development path lies in the processing plant and on the conveyor.

“We are looking to, first, put more minimum viable products (MVPs) out in the market for belt-based solutions,” he said. “While our initial entry into this space was to look at bulk sorting – and we recognise this is still the ‘big target’ – [the] voice of [the] customer research has identified a huge need to provide plant-based systems for applications in managing stockpiles and feed grades.”

These MVPs are likely to be deployed on “development partner” sites with existing separation mechanisms downstream of the crusher – ie apron feeders – where diversions can be made based on the HSI and PSD data.

This same voice of the customer research highlighted the need for an in-pit system that could boost productivity, throughput and recovery ahead of the plant, yet the financial amount estimated for a commercial system based on the HSI and PSD sensor combination did not find favour.

“This has led to our own research into what we feel is a new-to-the-world application or modification of standard HSI,” Carpenter said. “We believe this will give us a competitive edge in the market.”

Illumination restrictions and uses have often been touted as the potential drawbacks of using spectral imaging in the ore sorting space, which IM understands is one of the areas of focus for Weir’s own R&D and lab-based testing.

But there are also other factors to consider ahead of a commercial Weir proposition – whether that is in the pit or plant – landing on the market.

“We don’t just want to be sensor salespeople,” Carpenter says. “The complexity and variety of applications will require a shift to specific solutions for our customers and the need to back that up with the aftermarket service our customers expect becoming their productivity partner.

“What we are proposing is more than just technology; it needs to be a solution that validates the value on a regular basis in a continuous loop.”

That same loop comes back to Carpenter’s and Lawie’s assessment of the industry need to acknowledge the value of such data ahead of adopting the technology.

“Fortunately, our ‘Mining technology for a sustainable future’ focus at Weir is allowing us to invest the money the industry needs to provide both the value generation and value acknowledgement to make such solutions viable and effective,” Carpenter concluded. “This type of work – and orebody knowledge more widely – is critical for the future of mining.”

MMD to deliver prime sizing station to gold-copper mine in Southeast Asia

MMD says it has signed a contract to deliver a 1150 Series Fixed Sizer Station to an open-pit gold and copper mining operation in Southeast Asia in 2023.

Once installed, the sizer station will provide increased processing at 2,600 t/h and extend the mine’s life, according to the company.

The open-pit mine is situated in a remote and tropical region of Southeast Asia. Run-of-mine ore delivered by trucks to the fixed sizer station is abrasive and the seasonal heavy rainfall can make it very sticky. Like most sizer stations, it is a turnkey tailored design featuring: apron feeder, grizzly, 1150 Series Sizer and discharge conveyor. Additionally, MMD will be providing the supporting steelwork and electrical package, it said.

The modular design, together with the compact nature of the sizer station’s components, suits the logistical and accessibility challenges faced with getting the machine assembled at this remote mine location, according to the company. The sizer station’s flexibility, together with high energy efficiency, minimal maintenance and low installation costs, delivers a low total cost of ownership, it added.

The scope of supply includes both engineering and manufacture. This encompasses consultancy and design work, and will include training, installation, commissioning and supervision as the project is delivered.

Mark McVey, Lead Director at MMD Australia, said: “We are pleased to have been chosen as the supplier for the gold and copper ore processing project. Our technology will provide an energy-efficient sizing solution that will process the variable material conditions at consistently high tonnages, supporting the customer’s future objectives.”

MMD has already manufactured some of the major components and is working with the customer to deliver all the components for completion of the project in 2023.

Metso Outotec to deliver bauxite grinding package to NALCO alumina refinery

Metso Outotec has been awarded a contract for the engineering and delivery of a bauxite grinding package to National Aluminium Company’s (NALCO) Damanjodi Alumina Refinery as part of NALCO’s fifth stream expansion project in Odisha, India.

Typically, the value of this type of an order is in the range of €12-15 million ($14.2-17.8 million). The order has been booked in the company’s Minerals June quarter orders received.

Metso Outotec’s delivery includes basic design of bauxite silos and engineering and supply of two ball mills with a capacity of 434 t/heach, apron feeders, agitators, slurry pumps, instrumentation, as well as site advisory services.

Kamal Pahuja, President, Middle East and India at Metso Outotec, said: “We are extremely happy to continue our co-operation with NALCO. This is the third order we have received for their current expansion project in Odisha. The other two orders include two energy-efficient flash evaporation plants and two alumina calciners along with a hydrate filtration plant.”

Apron feeders: the material handling workhorses

Following the publication of the International Mining October issue and, more specifically, the annual in-pit crushing and conveying feature, we have taken a closer look at one of the core elements that makes up these systems, apron feeders.

In mining, apron feeders play a major role in ensuring smooth operations and increasing uptime. They are very diverse in their application within a mineral processing circuit; however, their full capabilities are not widely known throughout the industry leading to many raised questions.

Martin Yester, Global Product Support of Bulk Products at Metso, has answered some of the more important ones.

What is an apron feeder and when should it be used?

In simple terms, an apron feeder (also known as a pan feeder) is a mechanical type of feeder used in material handing operations to transfer (feed) material to other equipment or extract material (ore/rock) from storage stockpiles, bins or hoppers at a controlled rate of speed.

These feeders can be used in a variety of applications in primary, secondary and tertiary (reclaiming) operations.

Apron feeders are the preferred feeder for several reasons. Some of these are:

  • Aprons provide better feed control to prevent material feeding in downstream equipment from choking;
  • They can absorb the shock of loading material directly onto the feeder with a shallow bed (the impact coming down on the feeder when the material is dumped is great); and
  • Apron feeders can reclaim a variety of dry or wet materials of various sizes at a uniform rate, with this flexibility applied in many applications.

What are the advantages of using a tractor chain style apron feeder?

A tractor chain style apron feeder refers to the undercarriage chain, rollers and tail wheels that are also used in bulldozers and excavators. This style of feeder dominates the market in industries where users require a feeder that can extract materials of varying characteristics. Polyurethane seals in the chain prevent abrasive materials from entering the internal pin and bushing, which reduces wear and extends equipment life in comparison with a dry chain style. Tractor chain style apron feeders also create less noise pollution for quieter operation. The links of the chain are heat treated, which results in an increased service life.

Overall, the benefits include increased reliability, fewer spare parts, less maintenance and better feed control. In return, these benefits lead to more productivity with minimal bottlenecks within any mineral processing circuit.

Can apron feeders be installed on an incline?

The common belief about apron feeders is that they must be installed horizontally. Well, contrary to popular belief they can be installed on an incline! There are many added benefits and capabilities that come from this. Less space is needed overall when installing an apron feeder on an incline – not only does the inclination limit floor space, the height of the receiving hopper can also be reduced. Inclined apron feeders are more forgiving when it comes to larger lumps of material and, overall, will increase volume in the hopper and reduce the cycle time of the haul trucks.

Keep in mind there are some factors to pay attention to when installing a pan feeder on an incline to optimise the process. A properly designed hopper, the angle of inclination, the design of the support structure and the access and stair system around the feeder are all key factors.

Apron feeder optimal speed – faster is always better, right?

The common misconception around operating any equipment is: “faster is better.” In the case of apron feeders, nothing could be further from the truth. Optimal speed comes from finding that balance where efficiency meets transportation speed. They do operate at slower speeds than belt feeders, but for a good reason.

Normally, the optimal speed of an apron feeder is 0.05-0.40 m/s. If the ores are non-abrasive, the speed can increase to above 0.30 m/s due to the likely reduced wear.

Higher speeds would hurt an operation: if your speed is too high, you run the risk of accelerated wear of components. Energy efficiency, too, decreases due to the increase in energy demand.

Another concern to keep in mind when running an apron feeder at high speeds is the increased possibility of fines being generated. There can be a grinding effect between the material and the pans. Not only would the generation of fines create more issues because of possible fugitive dust in the air, but this also creates a more hazardous work environment for employees overall. So, finding an optimal speed is more important for the productivity and operational safety of the plant.

What are the limitations on size and type of ore?

Apron feeders do have limitations when it comes to the size and type of ore. The limitations will vary, but there should never be senseless dumping of material onto the feeder. You will need to not only factor in the application you will be using the feeder for, but also where in the process this feeder will be placed.

Generally, an industry rule to follow for your apron feeder dimensions is that the width of the pans (inside skirts) should be twice the maximum lump size of the material. Other factors, like a properly designed open hopper incorporating the use of “rock turning plates”, can affect the pan size, but that’s only relevant in certain circumstances.

It is not unusual for 1,500 mm of material to be extracted if a 3,000 mm wide feeder is used. Material of minus-300 mm from crusher ore stockpiles or storage/blending bins is typically extracted with apron feeders to feed secondary crushers.

What information is required when sizing an apron feeder?

When sizing an apron feeder and respective drive system (motor), as with a lot of equipment in the mining industry, experience and knowledge of the entire process is valuable. Apron feeder sizing requires basic knowledge of plant data to be able to accurately fill in the criteria needed for a vendor’s “application data sheet” (or however the vendor receives their information).

Basic criteria that should go into this includes feed rate (peak and normal), material characteristics (such as moisture, gradation and shape), maximum lump size of the ore/rock, bulk density of the ore/rock (maximum and minimum) and feed and discharge conditions.

However, occasionally there can be added variables to the apron feeder sizing process that should be included. A primary additional variable that vendors should be asking about is the hopper configuration. Specifically, the hopper shear length opening (L2) directly above the apron feeder. When applicable, this is not only a key parameter in properly sizing the apron feeder, but also the drive system as well.

How does “bulk” density affect the sizing of an apron feeder?

As stated above, bulk density of the ore/rock is one of the basic criteria requirements that should be included for effective apron feeder sizing. Density is the weight of material in a given volume and usually bulk density is measured as tonnes/cubic meter (t/m³), or pounds/cubic foot (lbs/ft³). One specific note to remember is that bulk density is used for apron feeders and not solid density like in other mineral processing equipment.

So why is bulk density so important? Apron feeders are volumetric-type feeders, which means bulk density is used to determine the speed and power needed to extract a certain tonnage per hour of the material. The minimum bulk density is used to determine the speed, and the maximum bulk density establishes the power (torque) needed for the feeder.

To conclude, it is important the correct “bulk” density and not “solid” density is used for sizing apron feeders. If these calculations are incorrect, this could jeopardise the resulting feed rate for the downstream process.

How do you determine the hopper shear length of the apron feeder?

Identifying the hopper shear length is a key component for correctly sizing and selecting an apron feeder and drive system (motor). But, how can this be determined? The hopper shear length is the dimension from the back plate of the hopper at the skirt line to the shear bar located at the exit end of the hopper. It sounds very simple, but it is key to note that this should not be confused with the dimension at the top of the hopper where material is loaded.

The goal of finding this measurement of the hopper shear length is to establish the actual shear plane line of material and where material inside the skirts is separated (sheared) from the material inside the hopper (L2). The resistance to shear the material is typically estimated to be between 50-70% of the total force/power. This calculation of the shear length will result in either insufficient power (lost production) or excessive power (rising operating expenses (opex)).

How do I find the optimal length of my apron feeder?

Spacing of equipment is essential to any plant. As mentioned before, apron feeders can be installed on an incline to save space. Selecting the correct length of an apron feeder will not only reduce capital expenditure (capex), it will also reduce power consumption and opex.

But how is the optimal length determined? The optimum length of an apron feeder is one that can fulfil the required duty in the shortest length possible. However, in some cases for an operation, the choice of feeder might want to be a little longer to “convey” materials to reach downstream equipment and eliminate a transfer point (and unnecessary costs).

To determine the shortest and optimal feeder possible requires flexibility in the layout of positioning the apron feeder under the hopper (L2). After determining the shear length and bed depth, the overall length can then be minimised just enough to prevent what is referred to as “self-flushing” over the discharge end when the feeder is idle.

I properly selected my apron feeder, but what about my drive system?

Selecting the proper drive system for your apron feeder will depend on the operation and goals of the feeder. Apron feeders are designed to be ran at variable speeds to extract from storage and feed downstream at a controlled rate of speed for maximum efficiency. The material could vary depending on factors such as the season of the year, orebody, or blasting and blending patterns.

The two types of drives suited for variable speeds are a mechanical drive using a gear reducer, inverter duty motor and variable frequency drive (VFD), or hydraulic motor and power unit with a variable pump. Today, variable speed mechanical drives have been proven as the preferred drive system due to the advancements in technology and capex benefits.

Hydraulic drive systems do have their place but are not seen as the ideal option between the two variable drives.

This Q&A was taken from a series of Metso blogs on apron feeders. For more information, please follow these links:

https://www.metso.com/blog-hub/mining-minds/feeding-the-facts-part-1-apron-feeder-basics/

https://www.metso.com/blog-hub/mining-minds/feeding-the-facts-23-proper-sizing-and-selection-of-your-apron-feeder/

NRW’s new RCR Mining Technologies business captures Rio Tinto Koodaideri contract

RCR Mining Technologies has continued its strong start under the guidance of new owner NRW Holdings, winning a “significant” original equipment manufacturer (OEM) equipment package from Rio Tinto for the miner’s Koodaideri iron ore project in the Pilbara of Western Australia.

The new order is for the supply of three large apron feeders, 11 slide gates and two belt feeders, to a combined value in excess of A$18 million ($12.2 million), NRW said.

NRW signed a deal with RCR Tomlinson’s administrators, back in January, to acquire the mining and heat treatment businesses of RCR for A$10 million in cash. Back then, NRW said the purchase of the international OEM and innovative materials handling designer would allow the company to provide incremental services, in line with its strategic objectives, to several core clients common to both NRW and the RCR businesses.

Ian Gibbs, Executive General Manager of RCRMT, said: “RCRMT has a long and proud history of supplying major equipment to Rio Tinto and the WA mining industry.

“Since transitioning to NRW ownership, we have been able to secure orders for all the current major iron ore projects to retain our status as the market leader in the design and manufacture of apron and belt feeders, which is an exciting achievement against a highly regarded multinational supply market.”

NRW CEO and Managing Director, Jules Pemberton, said: “The award represents further validation of our acquisition approach to provide clients with a broader service offering. I’d also like to acknowledge Ian Gibbs and his team who have worked hard to secure this work which will further support activity at both the Bunbury and Welshpool sites.”

NRW’s businesses have already won two contracts on the Koodaideri project – one for rail formation work and another for bulk earthworks.

TAKRAF helps CBG’s bauxite expansion project hit first ore goal

TAKRAF has reported on the recent start-up of Compagnie des Bauxites de Guinée (CBG)’s Bauxite Production Expansion project in Kamsar, Guinea.

The first ore milestone at the project, which sought to increase production from 13.5 to 18.5 Mt/y, was reached on schedule, on budget and, most importantly, safely, at the end of last year.

TAKRAF, in late 2016, was awarded an engineering, procurement and construction contract worth around €100 million ($113 million) for a greenfield railcar unloading and primary crushing station, as well as a secondary crushing station and a brownfield conveyor system. The railcar unloading system was designed in collaboration with Ashton Bulk.

The scope of supply included three TAKRAF sizers, with a primary sizer in the pit beneath the tippler and two secondary sizers. These sizers, as well as the apron feeders, were designed and fabricated at Tenova TAKRAF’s Lauchhammer fabrication facility in Germany.

An important safety milestone of 1.5 million lost-time-injury-free hours was achieved on site in December 2018, according to TAKRAF.

Frank Hubrich, TAKRAF CEO, said: “We are extremely proud to be a part of this important project and of our milestone achievements. These only serve to underline the competence and commitment to our clients of our global TAKRAF organisation.

“Whether it be a greenfield or an existing brownfield operation, we work with our clients to ensure that their requirements are met on time, within budget and most importantly, safely.”

Fluor Corp acted as the engineering, procurement and construction management (EPCM) services contractor on the project, responsible for the expansion of the mine infrastructure, rail system, port facility and processing plant infrastructure and utilities.