FAQ

Bulk Ore Sorting & Magnetic Resonance Technology

Will Magnetic Resonance-based sorting work for my operation?

The two key factors are ore mineralogy and grade heterogeneity. NextOre’s initial assessment evaluates the target minerals for detection, the in-situ heterogeneity of the orebody, and the expected ore mixing through your operations prior to the sorting point.

What benefit do I get from bulk ore sorting?

Bulk ore sorting can fundamentally improve mine economics through several compounding effects: higher process plant feed grade and metal output per tonne; lower operating costs across comminution, flotation, and tailings; a lower cut-off grade that captures previously uneconomic material; improved grade control that recovers metal otherwise lost to waste; and a smaller environmental footprint (less energy, water, and tailings per tonne of product).

One published case study modelling a large copper open pit showed a 13% increase in annual copper production, a head grade improvement from 0.39% to 0.45% Cu, and a 23% reduction in copper lost to waste. All within fixed plant capacity.

How much can bulk ore sorting increase the grade of my copper ore?

This depends on in-situ grade variability and how well it is preserved to the sorting point. In a Metso case study of a large copper open pit, head grade rose from 0.39% to 0.45% Cu (a 15% relative improvement). Modelling at Phu Kham showed net metal production increases of 13–40% when cut-off optimisation is combined with sorting.

Headline grade is only part of the story. At the Cozamin underground trial conducted with NextOre, sorting delivered a net 6.3–7.8% improvement in copper metal delivered to the plant versus conventional truck assignment, because recovery of marginal tonnes more than offsets sorting losses.

How does a magnetic resonance analyser help with ore control?

The MRA replaces SMU-level grade estimates, which average over thousands of tonnes and conceal real variability, with real-time, pod-by-pod grade data.

At Candelaria, installation of the MRA helped the technical team identify the source of a persistent negative reconciliation discrepancy. End-of-year copper reconciliation improved from –4.1% to –1.8% in the first year, with 2023 and 2024 finishing at –1.8% and +2.1% respectively. The system also enables real-time block model validation, source-based material tracking, mill feed grade stabilisation, and continuous cut-off optimisation.

How do I estimate the benefit of bulk ore sorting for my project?

The starting point is a heterogeneity study: an assessment of in-situ grade variability at the intended sorting point. Using drill core data and comparable deposit analogues, NextOre produces sorting curves that show mass and metal recovery under varying degrees of operational mixing.

Published benchmarks give useful indications. For copper operations with suitable heterogeneity, 15–40% tonnage reductions retain 97–89% of feed metal. Spodumene deposits tend to be even more heterogeneous, retaining 99–93% of metal across the same tonnage range.

Beyond the sorting curves, economic assessment should model practical implementation scenarios: increasing head grade within fixed plant capacity, lowering the cut-off grade to recover marginal material, and reducing dilution and ore loss through improved grade control. NextOre delivers these heterogeneity studies using MR analyser data, providing the tonne-by-tonne measurements required to model outcomes accurately. Every orebody is unique and results must be evaluated case by case improvement of 6.3–7.8% versus conventional truck assignment. The headline grade improvement number alone risks understating the total value delivered.

Are any studies available that prove bulk ore sorting works?

Yes. NextOre believes transparent reporting is essential to industry adoption. Detailed case studies and technical papers, authored by mining companies and NextOre personnel, document the methodologies and results of bulk ore sorting implementations. These are available in the “Resources” section of our website.

What ore analysers do large copper operations use for sorting?

Large copper operations implemented bulk ore sorting using NextOre’s magnetic resonance analysers. Documented commercial cases include Kansanshi Mine (First Quantum Minerals, Zambia), operating at 2,800 TPH and the largest publicly reported sensor-based bulk ore sorting installation worldwide; Minera Candelaria (Lundin Mining, Chile), with the MRA installed on a 6,000 TPH primary crusher discharge belt; and Cozamin (Capstone Mining, Mexico), a full-scale underground trial demonstrating a 6–8% net improvement in copper metal delivered to the plant.

Together these span underground and open pit mining, multiple ore mineralogies, and throughputs from hundreds to thousands of tonnes per hour.

What are the dominant sensing technologies used for preconcentration?

Only fully penetrative sensors are suitable for bulk ore sorting on conveyors. Surface-only technologies (XRF, colour cameras, LIBS) cannot representatively measure a large, heterogeneous mass of rock. The three penetrative options are Magnetic Resonance (MR), PGNAA (Prompt Gamma Neutron Activation Analysis), and PFTNA (Pulsed Fast and Thermal Neutron Activation).

MR directly measures the target mineral at the atomic level using tuned radio frequency pulses — fast (seconds per measurement), highly accurate, and mineral-specific. PGNAA and PFTNA measure elemental composition with measurement cycles of minutes rather than seconds, making them too slow for pod-by-pod sorting decisions, and both are susceptible to calibration drift. They are better suited to ore characterisation than active sorting. NextOre’s MR analysers are the only commercially deployed technology delivering grade measurements fast and reliably enough for real-time bulk sorting at high throughput.

What analysers give mineralogy on a loaded conveyor belt?

Only magnetic resonance analysers. All other conveyor-belt analysers measure elemental composition (PGNAA, PFTNA) or surface properties, neither gives mineralogy directly. Converting elemental copper to a mineralogical breakdown (chalcopyrite vs chalcocite vs oxide minerals) requires assumptions or a separate study, and those relationships are rarely stable across a deposit.

NextOre’s MRA is tuned to the resonant frequency of a specific target mineral, delivering a direct measurement of that mineral’s concentration rather than an inference from elemental proxies. This makes it uniquely suited to operations where the relationship between elemental grade and mineralogy varies spatially.

What does the Magnetic Resonance Analyser “sense” in ore?

The MRA is a direct, quantitative measurement of the weight of the target mineral in the ore, not density, surface composition, colour, permittivity, or conductivity. Combined with weightometer or belt scale data, it delivers accurate grade measurement of the ore stream on a metre-by-metre basis.

What precision can Magnetic Resonance measurements achieve?

The MR sensor has delivered sensing resolutions (1-sigma standard deviation) of less than 0.025% copper, quoted for copper as chalcopyrite at full production rates.

Which minerals can magnetic resonance measure?

MR can measure a range of economically important minerals across copper, iron, arsenic, antimony, nickel, and other metal groups:

• Copper minerals: Chalcopyrite (high sensitivity), Cubanite (high), Covellite (medium), Chalcocite (medium), Cuprite and delafossites (high), Enargite (low), Tennantite (low), Tenorite (low).
• Iron minerals: Hematite (high), Magnetite (very high), Maghemite (high), Pyrrhotite (high).
• Others: Arsenopyrite (high), Orpiment (high), Realgar (high), Stibnite (high), Löllingite (high), Niccolite (medium), Cobaltite (high), Bismuthinite (medium), Zircon (low).

The most commercially important application to date is chalcopyrite — the dominant copper-bearing mineral in copper sulphide orebodies — where MR delivers its highest sensitivity and has been validated at multiple commercial operations globally.

If a mineral is not listed, what does that mean?

It means the mineral has not yet been proven to have a measurable MR response, or its response has not been characterised to a level sufficient for commercial application. Not all minerals produce a detectable MR signal — the technology works only for minerals with appropriate crystalline structures that respond at accessible radio frequencies.

Before MR-based sorting can be deployed, the dominant target minerals in the ore must be confirmed. Either the target mineral must account for substantially all of the valuable metal in the ore stream, or its relationship to total metal grade must be well understood and consistent across the deposit.

Which minerals can magnetic resonance measure?

MR can measure a range of economically important minerals across copper, iron, arsenic, antimony, nickel, and other metal groups. Minerals with proven applicability include:

Copper minerals: Chalcopyrite (high sensitivity), Cubanite (high), Covellite (medium), Chalcocite (medium), Cuprite and delafossites (high), Enargite (low), Tennantite (low), Tenorite (low).

Iron minerals: Hematite (high), Magnetite (very high), Maghemite (high), Pyrrhotite (high).

Others: Arsenopyrite (high), Orpiment (high), Realgar (high), Stibnite (high), Löllingite (high), Niccolite (medium), Cobaltite (high), Bismuthinite (medium), Zircon (low).

The most commercially important application to date is chalcopyrite — the dominant copper-bearing mineral in copper sulphide orebodies — where MR delivers its highest sensitivity and has been validated at multiple commercial operations globally.

How reliable are magnetic resonance analysers?

Extremely dependable. At Kansanshi (First Quantum Minerals, Zambia), the MRA operated continuously throughout a complete commercial trial at 2,800 TPH, the largest publicly documented sensor-based bulk ore sorting installation to date. At Lundin Candelaria in Chile, the MRA has been a key operational data source since commissioning in early 2023, running on a 6,000 TPH crusher discharge belt. Blind validation testing at Cozamin returned an R² of 0.96 against laboratory assays; at Kansanshi, static testing yielded R² of 0.98.

The MR signal responds only to the tuned mineral, with no interference from other rock matrix minerals, moisture, particle size variation, or changes in ore type, making it robust across the conditions of actual mining operations, where conventional sampling and inferential sensors are far more vulnerable to noise and drift.

What causes inefficiencies in conveyor belt ore sorting?

The main causes are: sensors that are too slow, averaging over volumes too large to capture grade heterogeneity; excessive ore mixing upstream of the sorting point, which homogenises the material; oversized pods that blend high- and low-grade material into a single diversion decision; unstable sensor calibration introducing systematic error; and imprecise synchronisation between sensor and diverter gate, causing misrouted material.

NextOre’s MRA addresses these directly: it measures every 4–10 seconds (approximately 3-tonne pods at 2,800 TPH), is insensitive to gangue mineralogy, requires no recalibration, and its integrated PLC communicates directly with the diverter gate, eliminating variable latency from external control systems.

What is the smallest quantity of material that can be selectively sensed and rejected?

The minimum unit, the “pod”, is determined by measurement interval and belt throughput, not particle size. At 1–5 second intervals, pod sizes range from 30–150 kg for small operations (~1 Mtpa) up to 1.0–5.0 tonnes for large operations in the 10–40 Mtpa range. At Kansanshi (2,800 TPH, 4-second intervals), each pod was approximately 3.1 tonnes; at the Cozamin underground trial (~200 TPH), pods averaged 50–150 kg.

This is a step-change in selectivity. A geological block model may assign a single grade estimate to a 23,000-tonne SMU; grade control drilling might resolve it to 900-tonne pods; the MRA resolves the same block to pods under 3 tonnes, revealing the true grade distribution that averaging conceals, and enabling precise separation of waste that would otherwise report to the plant.

Does the presence of magnetic or paramagnetic material interfere with the measurement?

No. The measurement is tolerant of high levels of magnetic minerals such as pyrrhotite and magnetite.

What size material can be measured and sorted?

Primary crushed ore with top size below 350 mm is recommended

Does the feed material need to be washed or otherwise specially prepared?

No. The MRA requires no sample preparation. It measures 100% of the material on a loaded conveyor in its natural state, regardless of particle size, rock type, moisture content, or surface condition. The radiofrequency signal is fully penetrative and measures the entire ore volume within the sensor aperture, not just the surface.

This is a significant advantage over surface-based sensors (XRF, colour cameras, LIBS), which require clean, dry, often single-layer presentation. The MRA can be installed directly on a primary crushed ore conveyor and operate immediately, no washing, sizing, or drying circuits required.

Does conveyor belt material affect sensitivity or calibration?

Calibration is unaffected. Only the target mineral generates a response to the MR signal, so there is no coherent signal from belt material to interfere with or be adjusted for.

Sensitivity is affected only by steel cord belts, which can act as an antenna and transport electromagnetic noise from the environment into the sensor core. This may reduce the signal-to-noise ratio and result in a longer measurement interval. Standard rubber and fabric belts have no effect, regardless of thickness or wear. Belt characteristics are accounted for at initial commissioning and require no ongoing adjustment.

.

Can the MR sensor be installed on an existing belt?

Yes. One of the most practically important features of the technology. The sensor is designed to retrofit to existing conveyor infrastructure without cutting the belt or significantly modifying the structure. It is constructed in upper and lower halves that wrap around the belt and rest on the existing structure, with the aperture sized to accommodate the full ore load and largest expected particle sizes without contacting ore or belt.

The electronics container (a standard 10-foot air-conditioned shipping container) sits within 10 metres of the sensor, connected by cables, and requires only a suitable flat area nearby.

.

How much downtime is required for installation on an existing belt?

A well-planned 12-hour shutdown is the typical standard, demonstrated across multiple NextOre installations. At Kansanshi, the sensor was installed within a 12-hour shutdown by site personnel working under remote direction from NextOre’s Sydney team during COVID travel restrictions — showing that with proper preparation, installation can be completed reliably without NextOre personnel on-site.

Commissioning activities (sensor-to-diverter synchronisation, calibration confirmation, SCADA integration) follow installation and can typically be performed during normal operations or with no additional downtime.

How is the MR sensor calibrated, and why doesn’t it need recalibration?

The MRA is factory calibrated before delivery. Calibration consists of a single proportionality factor between the MR signal and the mass of the target mineral. At commissioning, this factor is confirmed on-site using a known standard of the target mine’s ore, shipped with the sensor. No routine or periodic recalibration is required for the full operational life of the system.

The reason is fundamental: MR measures a quantitative physical property, the resonant response of atoms in the target mineral, rather than inferring grade from a proxy. The signal-to-mass relationship is determined directly by the number of nuclei present in the target mineral phase.

In addition, the resonant frequencies for minerals span a wide range (1–100 MHz) and rarely overlap, so only the tuned mineral responds. This contrasts with spectroscopic methods such as XRF or PGNAA, where overlapping energy peaks require adjustments for the presence of other elements.

Can a program be designed to comprehensively validate measurement accuracy?d to comprehensively validate measurement accuracy?

Yes and this is one of the most important steps in implementing any grade measurement solution, regardless of sensor type. NextOre works with companies during the trial planning phase to set out methodologies and success thresholds for the validation program, including sampling, sample preparation, and assay protocols. Other technology suppliers who avoid such programs, or suggest they are unnecessary, should be treated with extreme caution.

How safe is the use of MR sensing?

Very safe. The MRA uses low-energy radio waves similar to those of a microwave oven or AM radio, well below the frequency of commercial two-way or FM radios, and easily shielded by thin metal sheets. It does not use ionising radiation, X-rays, gamma radiation, or neutron sources. As a result, it requires no radioactive source management, no radiation safety permits beyond standard workplace RF exposure compliance, and no exclusion zones or specialist radiation safety officers.

Radiofrequency field strength in all accessible areas adjacent to a working NextOre MRA is well below public exposure limits as defined by regulators including the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA). Interlocks are fitted to all high-voltage areas within the sensor assembly. Construction conforms to Australian electrical and mining standards. Safety data sheet available on request.