FIELD OF THE INVENTION

This invention relates to a method for beneficiating Pyrochlore mineralisation. More specifically, it relates to a process for beneficiating Pyrochlore where magnetic separation is used to substantively remove gangue mineralisation from Pyrochlore mineralisation, thereby yielding an upgraded product.

BACKGROUND TO THE INVENTION

The following discussion of the background art is intended to facilitate an understanding of the present invention only. The discussion is not an acknowledgement or admission that any of the material referred to is or was part of the common general knowledge as at the priority date of the application.

The majority of global niobium production is derived from Pyrochlore mineralisation (-99%), with a minority (-1 %) being derived as a co-product from the refining of minerals such as Tantalite, Cassiterite and Columbite. Pyrochlore is an oxide mineral with general chemical formula of (Na,Ca)2Nb2O6(OH,F). In this Application, Pyrochlore is referred to as niobium-bearing mineral variants of the Pyrochlore supergroup as defined by the International Mineralogical Association.

Three niobium-producing operations of which the Applicant is aware are Araxa (Brazil), Catalao (Brazil) and Niobec (Canada), all of which beneficiate Pyrochlore as the niobium-bearing mineral. These operations make up approximately 85%, 8%, and 6% of global niobium production respectively. Additionally, there are a handful of prospective projects under study and development including the Panda Hill Project (Tanzania), Elk Creek Project (USA), Aley Project (Canada) and the Kanyika Project (Malawi).

The general processing scheme adapted by all three niobium-producing operations, as well as those adopted by all projects of which the Applicant is aware is depicted in Figure 1 and, generally, consists of the following steps:

1. Comminution (crushing and milling) (1 and 2) to liberate Pyrochlore mineralisation from gangue minerals; 2. Classification (3) and desliming (5), to remove oversize particles for further grinding (4), as well as fine (slime, <10 pm) particles that would otherwise hinder ensuing beneficiation steps;

3. Low intensity magnetic separation (6), to remove gangue magnetite, with gangue sent to a tailings storage facility (7);

4. Beneficiation by way of various flotation schemes, typically undertaken in two flotation steps (8 and 9), with the first step removing gangue minerals and the second step recovering Pyrochlore, including a Pyrochlore conditioning flotation step (10);

5. Impurity removal (12), typically consisting of leaching, to remove phosphate, and flotation (13) to remove sulphide minerals such as Pyrite; and

6. Drying (13) and packaging, where the beneficiated concentrate is dried to remove moisture and packaged for transport to a converter plant where saleable niobium products - typically ferroniobium or niobium salts - are produced.

In instances where niobium is recovered as a by-product, such as in the processing and recovery of minerals such as Tantalite ((Fe,Mn)(Ta,Nb)2O6), Columbite ((Fe,Mn)(Nb,Ta)2O6), and NbTa-bearing Cassiterite ((Fe,Nb,Ta)SnO2), the tantalum/niobium/tin mineral concentrate is produced primarily using gravity beneficiation techniques, although in some select instances magnetic and electrostatic separation techniques are used. For example, Tantalite is recovered as a by-product in some Spodumene (lithium mineral) beneficiation plants, where magnetic separation is used to remove iron-bearing gangue minerals that would otherwise contaminate the Spodumene product.

Returning to the processing of Pyrochlore mineralisation, the general flowsheet (Fig. 1 ) currently used for Pyrochlore recovery was implemented in the 1960s, and has been under continual optimisation to improve process efficiency and economics. Nonetheless, and despite substantive improvements in process efficiency, there have been no substantive structural changes to the general Pyrochlore mineralisation processing scheme of which the Applicant is aware. The most substantive hindrances in processing that persist may be summarised as follows:

1. Low niobium recovery, typically below 60%, which is largely attributed to Pyrochlore losses in the desliming step and inefficiencies in the primary beneficiation (flotation) process;

2. The beneficiation (flotation) process scheme being complex, requiring intensive and extensive use of expensive reagents; and 3. Careful management of processing water, with the recycling of reagents requiring due care to prevent process imbalance and impeded performance.

There have been efforts to improve the efficiency of flotation processes by optimising existing flotation schemes, developing new flotation schemes and also modifying flotation schemes used for the beneficiation of minerals that do not bear niobium. These efforts are known in the art, which include:

1. Steffens, M. et al. (2016), Recovery of Pyrochlore. ARIPO Patent Application AP/P/2016/009440.

2. Rotzinger, R. and Meriam, K. (2018) System and Method for Concentrating Niobium Ore. International Patent Application WO 2018/184094 A1.

3. Gibson et al (2015), Niobium Oxide Mineral Flotation: A Review of Relevant Literature and the Current State of Industrial Operations, International Journal of Mineral Processing 137, pp 82-97.

4. Bulatovic (2010) Handbook of Flotation Reagents - Vol 2 - Flotation of Gold, PGM and Oxide Minerals, Elsevier Publishing, The Netherlands.

The Applicant is aware of one published mineralogical study on Pyrochlore that aimed to provide metallurgical insights. Chehreh-Celgani et al. (Chehreh-Celgani, S, 2013. Study on the surface chemistry behaviour of Pyrochlore during froth flotation. UWS PhD Thesis) undertook a detailed mineralogical study of Pyrochlore mineralisation from the Niobec mine and, after observing that Pyrochlore from the Niobec deposit occurs as high and low iron bearing varieties, found that their existing process favours the recovery of varieties of Pyrochlore with a lower Fe content.

WHIMS (Wet High Intensity Magnetic Separation) is an established mineral processing technology and has been demonstrated to be commercially effective for the recovery of iron bearing minerals such as Manganese ores (Pyrolusite and others), Titanium ores (Ilmenite), Tungsten ores (Wolframite), Iron ores (Hematite) as well as some Tantalum and Niobium minerals such as Tantalite and Colombite which contain a substantive amount of iron in the mineral matrix. The Applicant is not aware of studies that have been able to successfully demonstrate a substantive enrichment and recovery of Pyrochlore using WHIMS; instead, literature found by the Applicants is limited to several studies focused on the recovery of rare earth minerals where there has been minor Nb (Pyrochlore) recovered:

• Satur et al. (Satur et. al. 2014. Recovery of REE-bearing minerals from granite ore by dry magnetic separation and WHIMS settling methods, IMPC 2014 Conference) investigated the recovery of rare earths using wet high intensity magnetic separation. Pyrochlore was present in their test sample as a co-mineral and their reported data showed that, using a WHIMS at extreme magnetic field conditions of 2.15 T and with multiple (4x) passes through the WHIMS, allowed a low -30% recovery of the contained niobium (presumably present as Pyrochlore) with a Nb?O5 grade of the “magnetic fraction” product being 375 ppm. Given the commercial impracticality of this result, the investigators concluded that the most practical method of recovering Pyrochlore was by a slimes decantation procedure undertaken on the non-magnetic WHIMS product, where WHIMS was instead targeting REE minerals.

• The same group of investigators (Yang et al. 2015. Beneficiation studies of a complex REE ore. Minerals Engineering 71 , 55-64), undertook beneficiation studies on a REE- bearing ore, with scant mention of niobium recovery. They compared the recovery of rare earth minerals where flotation using a sodium oleate collector was used and a WHIMS machine using magnetic field strengths of 0.05 and 0.3 T. With regard to Pyrochlore, the investigators concluded that WHIMS may be more selective than flotation for Pyrochlore, Zircon and Elpidite minerals, but WHIMS is not capable of replacing flotation as the primary beneficiation stage.

It is an object of the invention to address certain of the shortcomings of processing conditions for beneficiating Pyrochlore mineral of which the Applicant is aware containing, especially, Nb, but also other constituents that may have economic value.

SUMMARY OF THE INVENTION

Broadly, the invention relates to a process for beneficiating Pyrochlore mineralisation containing Nb and other constituents that may have economic value, by a process including at least one step comprising magnetic separation and at least one step comprising pulsing, performed on prepared mineralisation.

According to one aspect of the invention, there is provided a method for beneficiating Pyrochlore mineralisation, the method comprising the steps of: providing Pyrochlore mineralisation; preparing the Pyrochlore mineralisation to liberate Pyrochlore particles, thereby rendering a milled Pyrochlore mineralisation including Pyrochlore and gangue mineralisation; subjecting the milled Pyrochlore mineralisation to at least one magnetic separation stage to separate the Pyrochlore from the gangue mineralisation, thereby rendering an upgraded Pyrochlore process stream; and subjecting either or both of the milled Pyrochlore mineralisation and upgraded Pyrochlore process stream to at least one pulsing step.

The at least one magnetic separation step may comprise applying high intensity magnetic separation (HIMS) having a background magnetic field strength in the range of 0.5 T to 3.0 T, preferably in the range of 1 .0 T to 2.4 T, most preferably in the range of 1 .2 T to 1.8 T. The HIMS may be performed in a WHIMS machine, i.e., a wet high intensity magnetic separator).

The method may comprise the further step of subjecting the milled Pyrochlore mineralisation to LIMS (Low Intensity Magnetic Separation) in a LIMS step. The LIMS step may be undertaken to remove impurities with a high magnetic susceptibility such as magnetite from the upgraded Pyrochlore process stream. The LIMS step may be performed by using a conventional LIMS machine known in the art, such as a wet drum magnetic separator. The LIMS step may be performed by using a magnetic separator having a drum, where the surface magnetic field strength on the drum is in the range of 0.05 T to 0.5 T, preferably 0.08 T to 0.4 T, most preferably 0.1 T - 0.3 T.

The LIMS step may be performed prior to HIMS. Alternatively, or additionally, the LIMS step may be performed following HIMS.

A further magnetic separation step may be performed to remove further gangue minerals that are less magnetically susceptible than those recovered in LIMS, by subjecting the milled Pyrochlore mineralisation to MIMS (Medium Intensity Magnetic Separation). The MIMS step may be performed using a magnetic separator having a drum, where the drum surface magnetic field strength is in the range of 0.15 T - 0.7 T, preferably 0.18 T - 0.6 T, most preferably 0.3 T - 0.5 T, thereby to selectively remove iron-bearing silicates such as mica. The MIMS step may be performed before or following LIMS, or before or following HIMS. The MIMS step may be performed using a conventional MIMS machine such as a wet drum magnetic separator or in another embodiment, a WHIMS machine with a corresponding magnetic field strength.

The at least one magnetic separation step may take several forms, ranging from performing the at least one magnetic separation step in one wet high intensity magnetic separator for the entire process, to a plurality of wet drum and wet high intensity magnetic separators, to maximise efficacy of the entire process and increase the beneficiation and recovery of Pyrochlore. As such, the at least one magnetic separation step may be included in a method of the present invention comprising at least one conditioning stage, at least one Low-Intensity Magnetic Separation (LIMS), at least one Medium-Intensity Magnetic Separation (MIMS) stage, at least one Rougher WHIMS stage, and/or at least one Scavenger WHIMS stage.

In one embodiment, the WHIMS stage may comprise two or more Rougher WHIMS stages; these may be referred to as Rougher #1 stage and Rougher #2 stage, and so forth. In another embodiment, the WHIMS stage may comprise two or more Scavenger WHIMS stages; these may be referred to as Scavenger #1 stage and Scavenger #2 stage, and so forth. In one embodiment, at least one magnetic separation step is included in a Cleaner WHIMS stage. In another embodiment, the WHIMS stage may comprise two or more Cleaner WHIMS stages. These may be termed Cleaner #1 stage and Cleaner #2 stage, and so forth. The WHIMS step may be performed by passing the milled mineralisation, as a slurry or mineral pulp, through a Rougher WHIMS stage, after which the non-magnetic fraction may be directed to and passed through a Scavenger WHIMS stage to allow recovery of magnetic or weakly magnetic minerals that were not captured in the magnetic fraction in the Rougher WHIMS stage. Prior to passing the milled mineralisation, as a slurry or mineral pulp through the Rougher WHIMS stage, it may have been passed through a preceding LIMS and/or MIMS step. When performing the WHIMS step, there may be multiple Scavenger stages. The number of Scavenger WHIMS stages is dependent on process efficiency, machine efficiency and cost considerations.

Typically, for the Rougher and Scavenger stages, the background magnetic field strength is in the range of 0.5 T to 3.0 T, preferably in the range of 1.0 T to 2.4 T, most preferably between 1.2 T and 1.8 T. Additionally, or alternatively, the Pyrochlore-bearing magnetic fraction from the Rougher and Scavenger stages may be further beneficiated, either separately or collectively, in a Cleaner WHIMS stage to allow further removal of non-magnetic minerals entrained in the magnetic fraction from the Rougher and/or Scavenger WHIMS stages. There may be multiple Cleaner WHIMS stages where the magnetic fraction is re-processed sequentially in subsequent cleaner stages. The number of Cleaner WHIMS stages may be selected based on process efficiency, machine efficiency and cost considerations. For the Cleaner WHIMS stages, the background magnetic field strength may be in the range of 0.5 T to 3.0 T, preferably in the range of 1.0 T to 2.4 T, most preferably between 1.2 T and 1.8 T. Application of the magnetic field to the milled Pyrochlore mineralisation or upgraded Pyrochlore process stream may be performed by passing the milled Pyrochlore mineralisation or upgraded Pyrochlore process stream through a matrix located within the high intensity magnetic separator. The matrix may consist of various arrangements known in the art, including steel mesh, steel wool, steel balls, grooved plates, expanded metal and metal horizontal rods/wires; these are generally fabricated of a suitable steel or metal known in the art. A matrix consisting of a horizontal metal rod arrangement is a preferred commercial matrix design common in the art. A matrix with horizontal rods having an average inter-rod spacing of between 0.3 mm and 20 mm from each other, preferably between 0.5 mm and 10 mm, from each other, most preferably 2 mm from each other.

When more than one Cleaner WHIMS stages are applied, the magnetic field strength may be varied along a cleaner train to optimise separation of Pyrochlore from other gangue minerals. This may be achieved by either altering the background magnetic field strength or by altering the induced magnetic field strength by selection of an alternative matrix of different design or specification. In addition to selecting the appropriate background magnetic field strength for Rougher, Scavenger or Cleaner WHIMS stages, the induced magnetic field strength may be altered, primarily by selection of an appropriate matrix design. Generally, matrix designs with a tighter spacing allow a greater induced magnetic field strength (magnetic field gradient) and thereby allow greater recovery of Pyrochlore. The process may include at least one additional step comprising subjecting the upgraded Pyrochlore process stream to mineral dressing techniques to produce and recover a further upgraded Pyrochlore as a concentrate. The mineral dressing techniques may be selected from gravity concentration, flotation concentration, or both.

The step of preparing the Pyrochlore mineralisation to liberate Pyrochlore particles may comprise milling, crushing, or comminution. The milling, crushing, or comminution may be performed to render particles having a size of Pwo = 10 pm to 500 pm, more preferably Pwo = 100 pm to 300 pm, most preferably Pwo = 150 pm. Preparing the Pyrochlore mineralisation (i.e., comminution) may be performed by crushing mined rocks followed by milling using SAG and/or Ball mills. The Ball mill may be operated in closed circuit with a classifier such as a screen or hydrocyclone to allow removal of particles that have been milled below the desired size. The step of subjecting the milled Pyrochlore mineralisation to at least one magnetic separation stage, may comprise pulsing the contents within the magnetic separator by application of a pulsing action, thereby to assist in separating Pyrochlore from gangue mineralisation, rendering an upgraded Pyrochlore process stream.

The pulsing step may occur during the magnetic separation step. As such, the milled mineralisation may be provided as a pulp or slurry, and the pulsing may occur within the WHIMS machine (i.e. , within the wet magnetic separator). Accordingly, the pulsing is imparted on the milled mineralisation in the form of the slurry or pulp while it is passing through the matrix within the HIMS. The pulsing may be performed in at least one magnetic separator such as a WHIMS machine. The pulsing may occur at a pulse amplitude of 1 mm to 50 mm, preferably 1.5 mm to 20 mm, more preferably 2 mm to 16 mm, most preferably 6 mm. The pulsing may be performed at a pulse frequency for a given pulse amplitude of 1 pulses/min to 500 pulses/min, preferably 10 pulses/min to 400 pulses/min, more preferably 20 pulses/min to 300 pulses/min, most preferably 150 pulses/min. The pulsing may be done at a set number of pulses for the duration of the pulsing step, or the pulse frequency may be varied continuously. The pulsing may be performed until desired mineral values exit the WHIMS machine under gravity. The slurry may be subjected to pulsing for 0.01 minutes to 120 minutes, preferably 0.1 minutes to 10 minutes, most preferably 0.2 minutes to 5 minutes.

The frequency and amplitude of the pulsing in the Cleaner stages may be amended from conditions used in Rougher and Scavenger stages. In particular, higher pulse amplitudes may be applied to promote cleaning of the concentrate and lower pulse amplitudes may be applied to promote recovery of Pyrochlore. It may also be beneficial to segregate material according to size prior to Cleaner magnetic separation, and process different sized particles in different magnetic separators. The magnetic fraction produced from the high intensity magnetic separation, either directly from Rougher or Scavenger stages, or from subsequent Cleaner stages, which shall herein be referred to as the “final magnetic product” are then transferred to finishing or further processing stages, depending on criteria such as the grade and gangue constituency of the final magnetic product.

One or more conditioning reagents may be added to the conditioning stage to assist with dispersion of particles or coagulation of selected particles. The one or more conditioning reagents are typically dispersing reagents such as caustic or sodium hexametaphosphate, or other suitable dispersing reagents which are commonly used in the field of the invention. In one embodiment where further processing of the final magnetic product may be required, the final magnetic product may be further beneficiated using mineral dressing techniques such as gravity concentration or flotation concentration techniques that are known in the field of the invention. In one embodiment it may be desirable to use a combination of gravity concentration and flotation concentration techniques. In one embodiment where the niobium grade and quantity of gangue constituents are suitable, the final magnetic product is dewatered by conventional means such as thickening and filtration, and then dried to yield a final concentrate product, using established techniques known in the field of the invention, for ensuing downstream smelting or refining.

Various types of WHIMS design are commercially available. Preferably, a WHIMS machine having a vertical ring separator design is used which has facility for applying pulsing to the slurry or pulp being processed within the machine. It is preferable for mineralisation to be homogenised or blended prior to processing to allow a steadier operation of the WHIMS processing scheme. The mineralisation may be pulped or slurried in a range of 5% to 40% solids (w/w in water), preferably 10% to 30%, most preferably 20% solids (w/w) in water.

It is also preferable to mine selectively to minimise high concentrations of impurity such as micaceous material. As such, an ore sorter may be used after crushing and prior to milling to remove micaceous material.

The method may include the step of beneficiating the Pyrochlore mineralisation using at least one gravity or flotation technique, prior to being beneficiated by high intensity magnetic separation. The Pyrochlore mineralisation may be beneficiated using WHIMS within a broader beneficiation scheme that entails one or more gravity and/or flotation techniques, and wherein high intensity magnetic separation is used to recover Pyrochlore from one or more process streams.

The invention extends to include beneficiated Pyrochlore produced by the method of the invention. The invention further extends to include Niobium produced by the method of the invention.

The invention extends to a mine or mineral processing site that includes the method of the invention.

BRIEF DESCRIPTION OF DRAWINGS AND TABLES Further features of the present invention are more fully described in the following description of several non-limiting embodiments thereof. This description is included solely for the purposes of exemplifying the present invention. It should not be understood as a restriction on the broad summary, disclosure or description of the invention as set out above. The description will be made with reference to the accompanying drawings and Tables in which:

• Figure 1 shows a block flow diagram of prior processes illustrating a general high- level beneficiation process scheme currently in commercial practice for production of Pyrochlore (Nb) mineral concentrate;

• Figure 2 shows a block flow diagram illustrating a general high-level mineral processing scheme for production of a Pyrochlore concentrate using high intensity magnetic separation, in accordance with one aspect of the invention;

• Figure 3 shows a block flow diagram illustrating a likely configuration and key process streams of a magnetic separation circuit in accordance with one aspect of the present invention, to allow effective beneficiation of Pyrochlore;

• Figure 4 shows the effect of background magnetic field strength on Nb, Ta, Fe and mass yield from the initial test, in accordance with one aspect of the invention;

• Figure 5 shows the effect of background magnetic field strength on Nb and mass yield for two pulse stroke lengths, in accordance with one aspect of the invention;

• Figure 6 shows the effect of background magnetic field strength on Nb yield for two grind sizes, in accordance with one aspect of the invention.

• Figure 7 shows the effect of matrix rod spacing on yield, in accordance with one aspect of the invention;

• Figure 8 shows the effect of pulse amplitude on niobium and mass yield in a WHIMS cleaner application, in accordance with one aspect of the invention;

• Figure 9a and Figure 9b show results from initial variability testing (Top (Fig 9a): The effect of background magnetic field strength on Nb yield. Bottom (Fig 9b): Corresponding mass yield to magnetic fraction, in accordance with one aspect of the invention;

• Figure 10 shows the relationship between Nb head grade on Nb yield and mass yield to the magnetic fraction, in accordance with one aspect of the invention.

• Figure 11 a and Figure 11 b show the effect of pulse frequency on yield and grade for various pulse amplitudes, in accordance with one aspect of the invention; and Figure 12a and Figure 12b show the effect of pulse amplitude on yield and grade for various pulse frequencies (same data as Figures 13a and 13b, but with a different X-axis variable), in accordance with one aspect of the invention

Tables 1-7 present key data on samples examined, testing conditions and testing results unable to be presented graphically in Figures.

DETAILED DESCRIPTION OF THE INVENTION

The following embodiments, given by way of non-limiting example only, are described in order to provide a more precise understanding of the subject matter of a preferred embodiment or embodiments. In the figures, like reference numerals are used to identify like parts or process steps throughout the figures.

In one aspect, it is an object of the invention to demonstrate that WHIMS can be used as a primary beneficiation technique for recovery of Pyrochlore. The following steps discuss methodologies that the Applicant has found to assist with the recovery of Pyrochlore from Pyrochlore-bearing mineralisation. All magnetic separation steps were performed in a WHIMS machine, i.e., a wet high intensity magnetic separator capable of performing Wet High Intensity Magnetic Separation with the capacity to apply pulsing to the contents of the magnetic separator, except where stated otherwise, as exemplified further herein. Application of the magnetic field to a slurry or pulp in the form of a milled Pyrochlore mineralisation or upgraded Pyrochlore process stream is performed by passing the milled Pyrochlore mineralisation or upgraded Pyrochlore process stream through a matrix located within the high intensity magnetic separator. The matrix consists, in the embodiments described herein, of a horizontal metal rod arrangement is a preferred commercial matrix design common in the art. A matrix with horizontal rods having an average inter-rod spacing of 2 mm from each other was found to be particularly beneficial, although various arrangements known in the art may be utilised effectively, including steel mesh, steel wool, steel balls, grooved plates, expanded metal and metal horizontal rods/wires; these are generally fabricated of a suitable steel or metal known in the art.

Where mention is made of magnetic field strength this is to be understood as background magnetic field strength unless specified otherwise, as applied to the wet high intensity magnetic separator or WHIMS machine. The LIMS step is performed using a wet drum magnetic separator where the surface magnetic field strength is typically of 0.1 T to 0.3 T. The MIMS step is performed using a wet drum magnetic separator where the surface magnetic field strength is typically of 0.3 T to 0.5 T, thereby to selectively remove some iron-bearing silicates such as mica. The WHIMS/HIMS step is performed using a background magnetic field strength typically of 0.5 T to 1 .8 T. The results from initial WHIMS testing achieved by the Applicant showed, surprisingly, that using high strength and high gradient magnetic fields in accordance with the invention, together with pulsing, allowed for a substantive separation of Pyrochlore minerals from the predominantly Feldspar group host minerals of the test sample, with high niobium recovery (circa 75%) and substantive intermediate niobium concentrate grades (exceeding 2.5% niobium) achieved that indicate that magnetic separation with pulsing can be used as a primary beneficiation stage where a substantive amount of the gangue mass is rejected. Further experimentation was undertaken to better establish optimal processing conditions and the veracity of using WHIMS to recover Pyrochlore by testing further samples. In certain embodiments, the magnetic separation step takes several forms, ranging from one magnetic separator machine for the entire process, to a processing scheme of numerous magnetic separator machines to maximise efficacy of the entire process; the most appropriate configuration will be determined primarily by process economic considerations and the mineralisation being processed.

As discussed in the background section, Figure 1 shows a high-level block flow diagram depicting a generalised process route for the prior widely adapted commercial process for beneficiating Pyrochlore. This is to provide context and has been summarised in the preceding Background section. Details of these schemes are known in the art and available in documents already cited. Figure 2 shows a high-level block flow diagram of one embodiment in accordance with the present invention depicting a process route using WHIMS for recovering Pyrochlore as an enriched mineral concentrate from a Pyrochlorebearing mineralisation. The mineralisation is mined using established mining techniques and transported to a process plant - as run-of-mine mineralisation - for processing. The term mineralisation as used in this document refers to any single mineral or combination of minerals occurring in a mass, or deposit, of economic or commercial interests. The term is intended to cover all forms in which mineralisation might occur, whether by class of deposit, mode of occurrence genesis or composition (JORC Code, 2012, p36).

The mineralisation is initially broken, crushed or comminuted using techniques known in the art, from a size of ~0.5 m diameter, using a crusher (20) such that the mineralisation is appropriately sized for semi-autogenous grinding (SAG) or milling (22), where the mineralisation is further reduced in size. The material exiting the SAG mill is classified (typically by screen or hydrocyclone)(24), typically at Pwo = 150 pm, with the oversize material being milled further using a ball mill (26). The milled material is returned to the screen (24) where undersize material progresses to the next process step and the oversize is recycled to the sag mill for milling (22, not shown). The Applicant has found that approximately minus 150 pm material is sufficiently milled for Pyrochlore liberation (Figure 7), although the appropriate particle size may be appropriately adjusted by those skilled in the field of the invention. Returning to Figure 2, the undersize material from the classifier (24) can then be directed to a low intensity magnetic separator or mediumintensity magnetic separator (28) for removal of highly magnetic constituents such as magnetite. Such highly magnetic constituents are directed to a tailings storage facility (30) or alternately, the undersize material from the classifier (24) may be transferred directly to high intensity magnetic separator (32). In certain embodiments it is favourable to add reagents such as dispersants to the stream to aid magnetic separation. Typical dispersing reagents include caustic or sodium hexametaphosphate, which are commonly known in the field of the invention.

Mineralisation that enters high intensity magnetic separation (32) is split into magnetic and non-magnetic fractions, with the Pyrochlore-depleted non-magnetic fraction being directed to a tailings storage facility (30). The resulting Pyrochlore-enriched magnetic fraction may, if sufficiently upgraded and with sufficiently low impurities, be directed to dewatering (38) for production of a final Pyrochlore concentrate, or alternately if further beneficiation is necessary, directed to a gravity beneficiation (34) and/or a flotation beneficiation (36) step. The waste streams from gravity beneficiation (34) and flotation beneficiation (36) are directed to the tailings storage facility (30) and the Pyrochlore-enriched process stream directed to dewatering (38), from which a final Pyrochlore concentrate product is produced. In certain embodiments it is more appropriate for the Pyrochlore-enriched magnetic fraction to be beneficiated sequentially through gravity beneficiation (34) and also flotation beneficiation (36). In certain embodiments it is beneficial, depending on process economic considerations, that flotation beneficiation precedes gravity beneficiation.

Figure 3 refers to one embodiment of a WHIMS separation flowsheet of the present invention for Pyrochlore recovery. It shows a more detailed processing flowsheet of the magnetic separation aspect of the present invention for treating Pyrochlore mineralisation. The milled mineralisation, which is presented as a slurry/pulp stream of water and solids is first conditioned (26) by addition of a dispersing reagent, if necessary, to disperse particles and allow improved performance of the ensuing magnetic separation steps or a coagulant to allow selective coagulation of some mineral particles. Typical dispersing reagents include caustic and/or sodium hexametaphosphate, which are commonly known in the art. The dispersant may be added in a dedicated mixing tank in preceding processing equipment, or in-line to a pipe or launder between process equipment (not shown).

The milled mineral/Pyrochlore pulp, either with or without dispersant or coagulant (caustic, hexametaphosphate (HMP) and the like) added, is then directed to LIMS or MIMS (28), where a low- or medium-intensity magnetic field is applied to allow removal of mill scale and highly magnetic minerals - such as magnetite - that would otherwise contaminate ensuing intermediate products and potentially hinder ensuing WHIMS steps. This is typically undertaken using a wet drum magnetic separator, of which various designs and arrangements exist in the Art. The appropriate magnetic field strength is dependent on the type and specification of separator used, but is preferably undertaken in the range of 0.05 - 0.5 T.

The milled pulp, that may have been subjected to low- or medium-intensity magnetic separation to remove highly magnetic constituents of the pulp, is directed to a Rougher WHIMS stage (40), where a high intensity and high gradient magnetic field is applied to the mineral pulp being directed through the machine, which effects a separation of magnetic and feebly magnetic minerals from non-magnetic minerals.

In one embodiment the magnetic product stream is then directed to a WHIMS cleaning stage (44). The non-magnetic stream from the Rougher WHIMS stage is directed to a Scavenger WHIMS stage (42) to allow recovery of feebly magnetic minerals such as Pyrochlore that were not recovered in the Rougher stage.

The non-magnetic stream exiting the Scavenger WHIMS stage is directed to the tailings storage facility (30), and the magnetic stream is, in one embodiment, preferably combined with the magnetic product stream from the Rougher WHIMS stage (40) and directed to WHIMS cleaning stage (46).

Initial experimental investigations (Table 1 and Figure 4) indicated that the optimal background magnetic field strength is above 0.5 T, preferably above 1.2 T, and more preferably above 1 .7 T. Table 1. Test Conditions for Initial WHIMS Tests.

Initial investigations (Table 2) also suggest that it is favourable to apply high background magnetic field strengths of 1 .7 T or up to 3.0 T for both Rougher (40) and Scavenger (42) stages. In one embodiment, the Rougher (40) and Scavenger (42) WHIMS stages comprise a plurality of WHIMS machines connected in a series arrangement to increase efficiency. In another embodiment, the Rougher (40) and Scavenger (42) WHIMS stages are connected in a parallel arrangement to allow appropriate control of the pulp flow-rate through each WHIMS machine, should machine sizing be insufficient for optimal recovery of Pyrochlore.

The combined magnetic product streams from the Rougher (40) and Scavenger (42) WHIMS stages are then directed to a WHIMS Cleaner stage (46), which consist of either a single cleaner step or multiple cleaner steps with WHIMS units installed in a series arrangement with the magnetic fraction from Cleaner stage #1 (44) directed to Cleaner Stage #2 (46) for further removal of non-magnetic constituents. In one embodiment, two Cleaner stages are utilised, although other embodiments may have fewer or additional cleaner stages. The non-magnetic stream from Cleaner Stage #1 (44) is directed to the WHIMS Rougher stage, and the non-magnetic stream from Cleaner Stage #2 (46) is recycled to Cleaner Stage 1 feed stream. Table 2. Test Conditions and Results for Sequential WHIMS Tests with Variable Background Magnetic Field Intensity

The magnetic fraction from Cleaner Stage #2 (46), bearing a substantive portion of Pyrochlore, is directed to further beneficiation which is typically either or both gravity or flotation beneficiation, concentrate finishing which is typically drying and packaging, or to another impurity removal process. The ensuing product is then prepared for downstream smelting or refining. Initial experimental investigations (56, Table 1 ) showed that pulsing conditions - of the pulse applied to the slurry or pulp while it is in the WHIMS bath and passing through the matrix - have a substantive effect on the recovery to, and grade of, Pyrochlore in the magnetic fraction, when performed in accordance with the method of the present invention. For clarity, the pulse is quantified by its frequency (pulses per minute) and amplitude (slurry or pulp level displacement within the WHIMS bath at the matrix).

Surprisingly, the Applicant has found that a lower pulse amplitude allows greater recovery of Pyrochlore than a higher pulse amplitude. As an example, in one embodiment, it was found that a pulse amplitude of 4.8 mm allowed greater recovery of Pyrochlore than a pulse amplitude of 11.4 mm, albeit with a larger mass yield; the balance of Pyrochlore recovery and mass yield to the magnetic fraction with the lower pulse amplitude is a more favourable result in regard to process economics. This is exemplified further hereinafter. The Applicant understands that the pulsing affects recovery by affecting the hydrodynamic flow of particles within the WHIMS machine and specifically Pyrochlore recovery principally by (a) presenting Pyrochlore particles to the matrix surface to facilitate magnetic attachment, and (b) intensity to allow the breaking of magnetic agglomerates to allow the removal of entrained gangue particles.

The Applicant also has found that the matrix design has a bearing on WHIMS performance and, in particular, The Applicant has found that where a horizontal steel rod matrix design is used, the spacing of the rods has a substantive effect on the performance of WHIMS and yields to the magnetic product. In one embodiment, the WHIMS machine included a horizontal steel rod matrix with a spacing of 2 mm between rods.

In one embodiment, the magnetic product steam is classified into discrete size fractions prior to WHIMS. This is undertaken prior to Rougher (40) or prior to Cleaner (44 & 46) WHIMS stages. This allows enhanced metallurgical performance by allowing optimisation of WHIMS machine conditions - such as background and induced magnetic field intensity and pulsing conditions - to better suit the particle sizes of minerals being processed. In certain embodiments it is favourable to reconfigure the WHIMS cleaner circuit to maximise recovery of Pyrochlore and allow better utilisation of capital equipment.

In one embodiment, it is beneficial to have a Cleaner-Scavenger Stage to recover Pyrochlore remaining in the Cleaner #1 (44) non-magnetic stream. In the same, or another, embodiment it is beneficial to recycle Cleaner #2 (46) non-magnetic stream to WHIMS Rougher feed (40) or WHIMS Scavenger (42) feed instead of WHIMS Cleaner #1 (44) feed.

The high intensity magnetic separators used in either a part or whole of magnetic separation circuit, is, in certain embodiments, undertaken on either a wet pulp/slurry sample or a dry “sand” sample using separators that are known in the field of the invention. Preferably, wet high intensity magnetic separators (WHIMS) are used as these allow greater operational flexibility, greater recovery of target minerals at finer particle sizes and also facilitate a more effective application of pulsing.

The type of WHIMS machine used in either a part or whole of the magnetic separation circuit is selected from one of various types, including a horizontal ring “carousel” or “Jones” type separator, or a vertical ring separator that is partly submerged in a bath of slurry that is adjoined to a pulsing mechanism to provide a pulsing action to the bath contents. In a preferred embodiment, a vertical ring separator design is used.

Ideally, it is preferable for mineralisation mined from different areas of the mineralised zone, or mineralisation obtained from elsewhere, to be blended before processing to allow steady operation of the process scheme.

It is also preferable for mining to be undertaken in a selective manner where sections of mineralisation enriched in gangue elements such as micaceous material are rejected. It is also preferable to incorporate an ore sorting stage to aid in rejecting gangue minerals.

TEST SAMPLES

Mineral (Core) Samples

The mineral samples used to exemplify the present invention were derived from drilling core samples collected from the Study Project Site 1 mineral resource. Sections of the sample were composited and crushed to -3.35 mm, after which sub-samples were homogenised and sub-samples split using a rotary splitter. The samples were milled to the desired grind size by wet grinding using a rod mill.

Concentrate Test Sample

A portion of Study Project Site 1 mineral concentrate sample - produced previously - was examined in the present invention. This sample was produced in the pilot plant flotation program undertaken by GZRINM (Guangzhou, China) (GZRINM Metallurgical Testing Report, October 2014. Pilot Plant Test Report for Study Project Site 1 Pyrochlore Mineralisation. Guangzhou Research Institute of Non-ferrous Metals).

Analysis of Test Samples

A head assay of the samples tested in this work is provided in Table 3. Table 3. Head assay of the samples tested.

MINERALOGY

A high-level and general mineralogical breakdown of minerals in the Study Project Site 1 mineral resource area is summarised in Table 4.

The primary mineral of interest, Pyrochlore, is generally liberated at -150 pm. This has been determined as approximately appropriate from historical metallurgical work where Pyrochlore was recovered by flotation, and validated by microscopic examination undertaken on select sections of the core. The Pyrochlore mineral is the sole host of niobium (Nb), and therefore Nb assay is used as a proxy for Pyrochlore. The Applicant is of the opinion that the majority of the tantalum (Ta) is also hosted in the Pyrochlore, although there are suggestions that a minor amount (-2%) may be hosted within a secondary mineral such as Microlite. Table 4. General mineralogical breakdown of minerals in the Study Project Site 1 mineral resource area.

TEST EQUIPMENT

The test equipment used in exemplifying the present invention are summarised in the following sub-sections.

GZRINM WHIMS (WHGMS) 145

The GZRINM WHIMS 145 machine is a batch test machine composed of an electrical control panel (where background magnetic field strength and pulse frequency are set), and a test unit consisting of an electromagnet with a central open core where the test matrix is placed, and a hutch pulse mechanism (bottom) to effect pulsing of the slurry within the hutch and core. This machine can accommodate a background magnetic field strength of approximately 1.7 T and pulsing frequency of 0 - 300 pulses/min and pulse amplitude of 0 - 12 mm.

Machine operation consists of the following:

1. Selection of desired magnetic field strength and pulsing conditions and adjusting machine variables accordingly.

2. Fill the hutch and test chamber with water and the desired matrix (to attract magnetic material). 3. Prepare sample into a slurry/pulp. For these tests, the samples were pulped to 20% solids (w/w) in water.

4. Turn on electromagnet to desired setting, turn on mechanical pulsing mechanism. Open the hutch discharge valve slightly, and start feeding the slurry into the core of the machine (with machine feed and discharge rates matched). Towards the end of the run when all slurry is fed, maintain fluid level by addition of water.

5. Once all material has been fed into the machine and discharge (water) runs clear, remove the non-magnetic material capture bucket, and replace with a magnetic material capture bucket.

6. Turn off the electromagnet and pulsing mechanism, thereby allowing magnetic material fastened to the matrix to dislodge and fall into the magnetics bucket. Wash the matrix and core and hutch to ensure all magnetic material is rinsed and captured.

7. Filter the magnetic and non-magnetic portions, dry, weigh and then assay.

Longi 500

The Longi 500 machine is a pilot-scale vertical-ring WHIMS test unit, and is a scaledown version of Longi’s industrial units. The Longi 500 machine can achieve a background magnetic field intensity of 1 .8 T, pulsation stroke of 16 - 50 mm and pulse frequency of 0 - 300 pulses/min.

Sion 100

The Sion 100 test unit is comparable to the GZRINM WHIMS 145 unit in function and operation, except the actual testing chamber is smaller and the maximum background magnetic field strength is 1 .3 T.

EXAMPLES

Mining and Processing

A mineral processing plant may be established where Pyrochlore mineralisation is mined, crushed and milled to liberate Pyrochlore mineralisation. The resulting mineral pulp (milled solids in a water slurry) is then processed using a high intensity and high gradient magnetic separation plant/circuit to beneficiate Pyrochlore minerals. The resulting Pyrochlore mineral concentrate - which may be an intermediate concentrate - can be further beneficiated using gravity and/or flotation beneficiation techniques to further upgrade the Pyrochlore content and reject gangue minerals. The resulting Pyrochlore depleted process stream from WHIMS may be further processed using other techniques known in the field of the invention to recover additional Pyrochlore that would otherwise be directed to a tailings storage facility. This approach addresses some of the shortcomings of currently adapted techniques of which the Applicant is aware, including the elimination or, at least, substantive reduction in the size of flotation plant, which in-turn allows for a substantive reduction in flotation plant capital and operating costs and water requirements. It also makes gravity treatment options such as centrifugal concentration more viable.

Integration into Existing Processes

An existing processing facility that beneficiates Pyrochlore may have a WHIMS process step integrated to increase process efficiency and/or provide a capital effective route to increase processing capacity. This is done in various ways in accordance with the present invention, including but not limited to:

• Installing a WHIMS step on a tailings stream to act as a scavenger to recover Pyrochlore mineralisation that would otherwise be directed to a tailings facility or backfill. This captured Pyrochlore is then further beneficiated using techniques known in the field of the invention to produce a concentrate product that is saleable or suitable for further downstream processing.

• Installing a WHIMS step after milling to allow production of an intermediate Pyrochlore concentrate that is then either: (a) directed to the existing downstream beneficiation circuit for further beneficiation, (b) treated separately in a separate plant that is more suitable for the further beneficiation of Pyrochlore recovered by WHIMS, or (c) already of a quality that is suitable for downstream processing such as hydrometallurgical or pyrometallurgical routes.

• Installing a WHIMS process step in accordance with the present invention on an existing process stream in an existing plant to further concentrate Pyrochlore.

Processing of Tailings

A processing scheme containing a WHIMS step finds application in recovery of Pyrochlore mineralisation from a residue contained within a tailings storage facility, such as those produced in historical mining activities. In such an example, the residue is mined using conventional mechanical or hydro-mining techniques, and the pulped mineralisation (slurry) then processed by WHIMS in accordance with the present invention to recover a Pyrochlore concentrate and generate a Pyrochlore-depleted tailing. The Pyrochlore concentrate produced by this method is then subjected to downstream hydrometallurgy or pyrometallurgy, processing or for further beneficiation using techniques known in the field of the invention.

METALLURGICAL TESTWORK

Example #1 - Initial siqhter test work

Initial sighter investigations were undertaken to establish approximate effects of key variables in WHIMS processing and thereby provide a sounder foundation for ensuing detailed investigation. The test conditions of the initial sighter tests are summarised in Table 1.

Effect of Magnetic Field Strength

An initial WHIMS sighter test was undertaken to provide an indication of the possibility of beneficiating Pyrochlore (Nb-bearing) and also provide a baseline for ensuing testing. A summary of the results is provided in Figure 4.

The results from this initial test demonstrate that discrete increases in background magnetic field strength from 0 T up to 1 .7 T result in increases in the recovery of niobium. At a background magnetic field strength of 1.7 T, a niobium recovery of -58% was obtained, with an associated mass recovery of -11 %. This encouraging result justified further investigation of WHIMS beneficiation. Other observations include:

• The Ta recovery is slightly lower than Nb recovery. The cause for this is unclear, but suspected to be a portion of the Ta being associated with another mineral.

• With a background magnetic field strength of 0.2 T, the proportion of Nb reporting to the magnetic fraction is higher than with LIMS tests that were undertaken historically in the project. While there is no direct comparison to provide conclusive data, this difference is considered to be owing to the larger magnetic field gradient (induced magnetic field strength) that is intrinsic to WHIMS machines.

Cursory Evaluation into the Effect of Pulsing

Following the results of the initial WHIMS sighter test, it was postulated that the pulse conditions were too aggressive for some of the Pyrochlore, which was presumed to be feebly magnetic, to remain attached to the WHIMS matrix. At this stage of the program, and in lieu of a more expansive pulse optimisation test scheme, a repeat test was undertaken with all conditions comparable, except with the hutch water pulse stroke length reduced from 11.4 mm to 4.8 mm. A summary of the results provided in Figure 5. From the results it is evident that decreasing the stroke length allowed a substantial increase in recovery of niobium to the magnetic fraction from -58% to -69%. The corresponding mass yield increased from 10.5% to 17.5%, which is attributed to a decrease in the cleaning effect imparted by a large pulse amplitude. For ensuing tests - prior to a more detailed pulse optimisation - a pulse amplitude of 4.8 mm was adapted.

Effect of Grind Size on Pyrochlore Recovery

A comparative test was undertaken to determine if the particle grind size was limiting the recovery of Pyrochlore (Nb). One sample was milled to a Pwo = 75 pm, and a comparison of Nb recovery to magnetic fraction with an earlier sample (P o = 150 pm) was made; this is provided in Figure 6. The Pwo size is the screen aperture size where 100% of the particles in the sample are smaller. The results show that the recovery of niobium is virtually unchanged for the two grind sizes, with the exception of a -2% difference in recovery at a background magnetic field strength of 1.7 T; this may be attributed to better liberation of Pyrochlore from previously coarse composite particles. This indicates that the selected grind size is not greatly limiting recovery of Pyrochlore and is a suitable particle size.

Effect of Matrix Size on Pyrochlore Recovery

The matrix size (packing density) in a WHIMS has an established effect on the induced magnetic field strength, with increasing non-uniformity of the matrix resulting in increases in the induced magnetic field strength (i.e., magnetic field gradient). Manufacturers of magnetic separation equipment generally quote a “Background Magnetic Field Strength”, which is the magnetic field strength generated by the machine without a matrix. The “Induced Magnetic Field Strength” is how much the magnetic field is intensified by effect of a particular matrix design/arrangement. Various types of matrix material are used in WHIMS including expanded metal, steel wool, steel mesh, grooved steel plates and steel rod arrangements. Vertical ring WHIMS designs commonly use horizontal steel rod arrangements and therefore in this study various horizontal steel rod arrangements were investigated. To quantify the effect of matrix size on Pyrochlore (niobium) recovery/yield, a series of tests with comparable conditions were undertaken, but with the test matrix changed between 1 mm, 2 mm and 3 mm spacing. The results are shown in Figure 7. Decreasing the matrix size from 3 mm to 2 mm and 1 mm resulted in an increase in Nb yield to the magnetic fraction from -68% (3 mm) to 71 % (2 mm) and 79% (1 mm). Accompanying this 11 % increase in Nb yield is a small increase in mass yield from -25% (3 mm) to -29% (1 mm). This trend is attributed to the higher induced magnetic field strength (higher gradient) capturing additional material of lesser magnetic susceptibility. The increase in mass yield is largely attributed to co-recovery of additional gangue. These results indicate that matrixes with a lower spacing are preferable for higher recovery of Nb. Practically, there exists a trade-off between recovery and operability considerations, with lower spacing matrixes being more prone to hindered particle passage through the matrix and greater potential for blockage. For further tests described herein, a matrix with horizontal rod spacing of 2 mm was used.

Cleaning Magnetic Rougher/Scavenger Concentrate Using WHIMS

A series of tests were undertaken to examine the effect of pulse amplitude on the efficacy of a cleaner WHIMS stage. Previous test results indicate that there is an appreciable amount of non-magnetic minerals contained within the magnetic concentrate produced by rougher/scavenger tests. A sample of magnetic concentrate produced by processing sample 056 (22-36) at a background magnetic field strength of 1.7 T, with grade of Nb = 0.637% was used as a feed. The results are summarised in Error! Reference source not found. 8. The results show that, regardless of pulsing condition selected, the Nb recovery to the magnetic fraction does not exceed -91 %, which indicates that a variable affecting performance of the WHIMS, such as, for example, surface charge effects which may, in certain embodiments, require amendment of pulp conditions by addition of a dispersant reagent. With the limited Nb recovery aside, a pulse amplitude of -6 mm provided the optimal balance of Nb recovery and gangue rejection. Collectively, the results demonstrate that cleaner stages of WHIMS allow rejection of gangue minerals and upgrading of Pyrochlore.

Cleaning Magnetic Rougher/Scavenger Concentrate Using LIMS

A single LIMS cleaner test was undertaken to quantify the amount of material with high magnetic susceptibility (such as magnetite) that could be removed from the magnetic rougher/scavenger concentrate. It was found that 4.7% of the mass could be rejected to magnetics with -1.37% Nb loss, with the resulting magnetic fraction being largely magnetite. The LIMS drum separator used was a conventional drum-type with a magnetic field intensity of 0.12 T at the drum surface. The Nb loss reported is consistent with historical work undertaken on Study Project Site 1 mineralisation, although this historical work was undertaken on mineralisation instead of WHIMS magnetic concentrate. This further demonstrates that a LIMS step allows rejection of gangue and upgrading of Pyrochlore in the process of the invention.

Peripheral Tests and Observations

In investigating the primary aspects of Pyrochlore recovery by WHIMS, several experimental tests were undertaken where peripheral aspects were investigated. The results indicate:

• There is a small effect in the sequencing of background magnetic field intensity between rougher and scavenger passes in a WHIMS (Table 2). That is, there is a ~2% increased Nb recovery when passing a sample through a WHIMS with a background magnetic field strength of 1 .7 T for both rougher and scavenger steps, than passing a sample first through at 1.2 T for rougher, and then at 1.7 T for scavenger. This indicates that high background magnetic field strengths should be adopted for both Rougher and Scavenger stages of WHIMS.

• The samples were prepared by stage-grinding to prevent over-grinding of Pyrochlore minerals. It was found that micaceous material typically accumulated on the classifying screen, and analysis of this material confirmed there was low entrainment of Pyrochlore. Screening and disposal of micaceous material during classification may present a practical way of disposing mica and also increasing capacity of a milling circuit. o The micaceous portion that was recalcitrant to grind represented between 1.4% and 10.2% of the sample mass. Analysis indicated that the Nb loss associated with this was - on average - approximately 1 %. o This micaceous material largely reports to the magnetic concentrate fraction from WHIMS testing. Effectively removing the mica within the comminution circuit allows more effective performance.

• Assay x size chemical analysis (i.e., chemical analysis of size fractions) was undertaken on WHIMS magnetic and non-magnetic products. This showed that WHIMS recovers fine sized (-38 urn) Pyrochlore particles, albeit not as effectively as coarser Pyrochlore.

Testing of Existing Flotation Concentrate

A WHIMS test (using the WHIMS 145 unit) was undertaken on a sample of flotation concentrate produced from Study Project Site 1 mineralisation in the 2014 pilot plant work at Guangzhou Research Institute for Non-Ferrous Metals (GZRINM). Testing showed that 94.5% of the Pyrochlore reported to the magnetic concentrate; further increase in recovery is highly likely with further optimisation of test conditions. This benchmark is suggestive that using a WHIMS as a primary beneficiation step will not incur a substantive Nb recovery loss over directly using flotation as the primary step.

Benchmarking Tests Using Alternative Machine

A benchmarking test was undertaken to provide a comparison to another WHIMS testing unit. The unit tested was the Sion 100 batch unit and the sample tested was 056 (36-60), stage milled to Pwo = 150 pm. The Sion 100 unit was operated at a maximum background magnetic field strength of 1.2 T (3 passes @ 0.5 T, 1.2 T & 1.2 T) with a horizontal rod matrix with 2 mm spacing, and it was found, overall, to allow a Nb recovery of 54% with a corresponding mass yield of 16%. Interesting of note, the two 1.2 T runs were undertaken at different pulsation frequencies; the first run at 300 pulses/min allowed a Nb recovery of 2%, and the second run at 100 pulses/min allowed a Nb recovery of 50%. This provides further confirmation that pulsation conditions of the present invention have a substantive effect on Nb recovery, particularly at relatively low background magnetic field strengths. Testing of the same sample with the GZRINM WHIMS 145 unit, returned results of a Nb recovery of -85% with a corresponding mass yield of -29% (Figure 9a). This highlights the importance of using a high background magnetic field strength for high recovery of Nb, and also of selecting the optimal pulsing conditions, in accordance with the present invention.

Example #2 - Variability Tests

A series of tests were undertaken on various samples to better gauge the metallurgical response to beneficiation by WHIMS across the Study Project Site 1 mineralised zone. Cursory variability testing at an early stage of process evaluation is important because it provides a broader view on performance over the broader Study Project Site 1 mineralised zone and also, may identify fatal flaws.

Tests were undertaken on nine composite samples prepared from different sections of core. The tests were undertaken by passing a sample through a batch WHIMS machine at incrementally higher magnetic field strengths (0.2 or 0.5 T, and then 1 .2 T and 1 .7 T) to sequentially remove material of varying magnetic susceptibility to produce several magnetic concentrates and a final non-magnetic concentrate. A summary of the testing conditions used is presented in Table 5. The results of testing are summarised in Figure 9a and Figure 9b).

Table 5. Test Conditions for Variability Testing

The key findings from these tests are as follows:

• The range of Nb yield (recovery) to the magnetic fraction is 66 - 87%, with an average recovery of 75%. The corresponding range in mass yield to the magnetic fraction is 14 - 31%, with an average of 25%. o Variation in mass yield is significant, and appears to be owing to presence of Fe-bearing gangue minerals and entrainment of other minerals.

• Higher background magnetic field strengths allow greater Nb recovery, with 1 .7 T - the highest background magnetic field strength tested - consistently allowing higher recovery.

• No tests returned unusually low Nb recoveries, indicating that WHIMS processing is applicable for the greater Study Project Site 1 mineralised zone;

• Initial analysis of the dataset suggests there are no discernible correlations between Nb recovery and Nb grade, and between Nb recovery and mass yield (Figure 10).

Example #3 - Scale-up Test

A scale-up test was undertaken on two samples using a Longi 500 pilot WHIMS test unit. The intention of this test was to provide a sample for downstream metallurgical (flotation and gravity) testing, and therefore the metallurgical data collected here is for sake of establishing a baseline and gauging potential to scale-up the process. The test conditions were not optimised. The results, compared with batch test results, are summarised in Table 6.

Table 6. Comparison of Results of Batch Testing with Initial Pilot-Scale Testing.

The results show an approximately 12% lower Nb recovery in the pilot scale test than in the batch test. This is attributed to the conditions not being optimised for the pilot scale unit or batch testing conditions not being accurately translated to the pilot-scale unit. Nonetheless, the result demonstrates commercial practicality.

Example #4 - Hutch Water Pulsing Optimisation Tests

A series of pulsing optimisation tests were undertaken to determine the appropriate operating envelope of pulsing conditions - pulse frequency and pulse amplitude - that allow optimal process performance.

These tests were undertaken by undertaking a series of batch WHIMS tests where the pulse frequency and amplitude was systematically varied, and associated mass yield and elemental recovery measured.

The test conditions are summarised in Table 7 and results summarised in Figures 11 a and 11 b (yield as a function of frequency for various amplitudes) and Figures 12a and 12b (yield as a function of amplitude for various frequencies). (Note: Figure 1a and 11 b and Figure 12a and 12b present the same data but with a different variable on the x-axis). Table 7. Test Conditions for Hutch Pulse Optimisation Testing.

The key findings from these experiments are as follows:

Referring firstly to Figure 11a and 11 b with a focus on pulse frequency;

• Decreasing the pulse frequency - for a given pulse amplitude - from 300 pulses/min to 50 pulses/min broadly allows for an increase in Nb recovery. Concurrently, this also allows for an increase in mass yield and associated decrease in Nb grade of the magnetic fraction. o It is apparent, only for the two lower pulse amplitude conditions (2.5 and 3.0 mm) tested, there appears to be a drop (local minima) in Nb yield at a pulse frequency of 100 pulses/min. The reason for this is unclear, but may possibly be owing to the pulse frequency being near harmonic with a component of the system or with particles in the slurry.

• Concurrently with decreasing the pulse frequency, the mass yield (fraction of feed mass reporting to the magnetic fraction) also increases. o There appear two zones where the mass yield increases at different rates. o Initially, decreases in frequency from 300 pulses/min to 150 pulses/min allows a steady increase in mass yield, o Subsequently, decreases in frequency from 150 pulses/min and downward result in a more pronounced increase in mass yield.

• Given WHIMS is envisaged to be use as a primary beneficiation stage, Nb recovery is more important than Nb grade, although maximal gangue mineral rejection is desired to reduce the size of downstream process plant. Therefore, a hutch water pulse frequency of circa 150 pulses/min appears to provide an appropriate balance of Nb recovery and gangue rejection. Referring now to Figures 12a and 12b, with a focus on pulse amplitude;

• Decreasing the pulse amplitude- for a given pulse frequency - from 10.7 mm to

2.5 mm broadly allows for an increase in Nb recovery. Concurrently, this also allows for an increase in mass yield and associated decrease in Nb grade of the magnetic fraction. o From a solely Nb recovery perspective, broadly, a lower stroke length is favourable.

• As the stroke length is decreased below ~6 mm, the mass yield to the magnetic fraction rises at a steeper rate owing to the decreased “cleaning” action associated with the reduced amplitude. o Balancing Nb recovery and gangue mass rejection, a stroke length of circa 6 mm appears optimal.

It is envisaged that pre-existing process schemes in which minerals other than Pyrochlore are beneficiated may incorporate the present invention to allow production of a Pyrochlore concentrate suitable for either further beneficiation using techniques known in the field of the invention or for downstream processing. In one embodiment (not shown), the Pyrochlore mineralisation is beneficiated using at least one gravity or flotation technique, prior to being beneficiated by high intensity magnetic separation. As such, the Pyrochlore mineralisation is beneficiated using WHIMS within a broader beneficiation scheme (i.e., Pyrochlore beneficiation process) that entails one or more gravity and/or flotation techniques, and high intensity magnetic separation is used to recover Pyrochlore from one or more process streams.

The Applicant is of the opinion that they have invented a useful method of concentrating Pyrochlore mineralisation, as well as recovering Niobium values, by high intensity and high gradient magnetic separators and pulsing, as presented herein. Optional embodiments of the present invention may also be said to broadly consist in the parts, elements and features referred to or indicated herein, individually or collectively, in any or all combinations of two or more of the parts, elements or features, and wherein specific integers are mentioned herein which have known equivalents in the art to which the invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth. It is to be appreciated that reference to "one example" or "an example" of the invention is not made in an exclusive sense. Accordingly, one example may exemplify certain aspects of the invention, whilst other aspects are exemplified in a different example. These examples are intended to assist the skilled person in performing the invention and are not intended to limit the overall scope of the invention in any way unless the context clearly indicates otherwise.

It is to be understood that the terminology employed above is for the purpose of description and should not be regarded as limiting. The described embodiment is intended to be illustrative of the invention, without limiting the scope thereof. The invention is capable of being practised with various modifications and additions as will readily occur to those skilled in the art. Various substantially and specifically practical and useful exemplary embodiments of the claimed subject matter are described herein, textually and/or graphically, including the best mode, if any, known to the inventors for carrying out the claimed subject matter. Variations (e.g., modifications and/or enhancements) of one or more embodiments described herein might become apparent to those of ordinary skill in the art upon reading this application. The inventor(s) expects skilled artisans to employ such variations as appropriate, and the inventor(s) intends for the claimed subject matter to be practiced other than as specifically described herein. Accordingly, as permitted by law, the claimed subject matter includes and covers all equivalents of the claimed subject matter and all improvements to the claimed subject matter. Moreover, every combination of the above described elements, activities, and all possible variations thereof are encompassed by the claimed subject matter unless otherwise clearly indicated herein, clearly and specifically disclaimed, or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., "such as") provided herein, is intended merely to better illuminate one or more embodiments and does not pose a limitation on the scope of any claimed subject matter unless otherwise stated. No language in the specification should be construed as indicating any non-claimed subject matter as essential to the practice of the claimed subject matter. The use of words that indicate orientation or direction of travel is not to be considered limiting. Thus, words such as "front", "back", "rear", "side", "up", down", "upper", "lower", "top", "bottom", "forwards", "backwards", "towards", "distal", "proximal", "in", "out" and synonyms, antonyms and derivatives thereof have been selected for convenience only, unless the context indicates otherwise. The inventor(s) envisage that various exemplary embodiments of the claimed subject matter can be supplied in any particular orientation and the claimed subject matter is intended to include such orientations. The use of the terms "a", "an", "said", "the", and/or similar referents in the context of describing various embodiments (especially in the context of the claimed subject matter) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms "including," "having," "including," and "containing" are to be construed as open-ended terms (i.e., meaning "including, but not limited to,") unless otherwise noted. Moreover, when any number or range is described herein, unless clearly stated otherwise, that number or range is approximate. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value and each separate sub-range defined by such separate values is incorporated into the specification as if it were individually recited herein. For example, if a range of 1 to 10 is described, that range includes all values there between, such as for example, 1.1 , 2.5, 3.335, 5, 6.179, 8.9999, etc., and includes all sub-ranges there between, such as for example, 1 to 3.65, 2.8 to 8.14, 1.93 to 9, etc. Accordingly, every portion (e.g., title, field, background, summary, description, abstract, drawing figure, etc.) of this application, other than the claims themselves, is to be regarded as illustrative in nature, and not as restrictive; and the scope of subject matter protected by any patent that issues based on this application is defined only by the claims of that patent.