TECHNICAL FIELD

[001] The present disclosure relates to a mining system and method, and, in particular, a system and method for processing magnetite ore.

BACKGROUND

[002] Mining iron ore has a long, traditional history. Iron ore plays a key part in our society but there are various challenges presented in mining iron ore, including obtaining a higher quality concentrate with less energy consumption.

[003] Magnetite is a relative abundant iron oxide mineral. However, in comparison to hematite ores, for example, magnetite ores have lower ore grade (generally 25-40% Fe) due to the presence of impurities. Further processing is therefore required to reject the impurities in magnetite ores, making it costly to produce a suitable concentrate for steel smelters. On the other hand, magnetite concentrate requires less energy and releases less carbon emissions in the production of premium-quality steel when compared with hematite ores. With more concerns on the climate change, it is expected that high purity magnetite concentrate will become a new leader in the steel making industry. On this basis, magnetite ores can be cost competitive compared to hematite ores, offsetting the higher costs of production.

[004] For most magnetite ores, the magnetite particles are fine, uneven grains. Therefore, the application of conventional mining techniques requires higher energy and operational costs. Materials have to be further processed via additional grinding stages so that adequate liberation of magnetite particles can be achieved. Traditional magnetic separation techniques are also less effective when fine, uneven grains of magnetite are processed. That is, they fail to cope with fine, uneven grains due to the inherent entrainment of slimes and poorly interlocked particles during separation. Accordingly, compared to traditional techniques, there is a need to increase the magnetite concentrate grade during processing, whilst ideally also reducing energy consumption and/or operational costs.

[005] Bearing this in mind, the present inventor(s) have developed an improved system and method for processing magnetite concentrate. [006] Any reference to or discussion of any document, act or item of knowledge in this specification is included solely for the purpose of providing a context for the present invention. It is not suggested or represented that any of these matters or any combination thereof formed at the priority date part of the common general knowledge, or was known to be relevant to an attempt to solve any problem with which this specification is concerned.

SUMMARY OF THE INVENTION

[007] In a first aspect, the present disclosure provides a mining system including: a separating device configured to assist with processing magnetite ore; and a column magnetic separator in communication with the separating device, the column magnetic separator configured to separate magnetite from the magnetite ore as the magnetite ore moves along a column body, wherein the separating device and column magnetic separator work in combination to improve one or more process parameters in extracting the magnetite.

[008] In an embodiment, the column magnetic separator is in the form of a desliming elutriation column.

[009] In an embodiment, the column magnetic separator is configured to allow magnetite concentrate to flow circumferentially around the column body whilst tailings flow centrally upwards.

[010] In an embodiment, a water flow inside the column body is directed upwards in a manner that is in an opposite radial direction to incoming magnetite ore.

[011] In an embodiment, the water flow in the column body can be adjusted to assist with separating the magnetite from the incoming magnetite ore.

[012] In an embodiment, incoming magnetite ore into the column body can be adjusted on a volume basis.

[013] In an embodiment, the separating device includes a magnetic separator. [014] In an embodiment, the magnetic separator is a low intensity magnetic separator.

[015] In an embodiment, the magnetic separator includes a drum and a magnet.

[016] In an embodiment, the drum rotates about the magnet.

[017] In an embodiment, the drum is configured to lift magnetite particles to a position that directs them to a concentrate area.

[018] In an embodiment, the drum extends substantially in a lateral direction.

[019] In an embodiment, the magnetic separator includes a fluid flow. In an embodiment, the fluid flow assists with directing tailings towards a tailings area.

[020] In an embodiment, the column magnetic separator is introduced after the magnetic separator.

[021] In an embodiment, the separating device includes a further column magnetic separator. In an embodiment the magnetic separators are arranged in series.

[022] In an embodiment, the further column magnetic separator assists with inefficiencies such as surging in the column magnetic separator.

[023] In an embodiment, the column magnetic separator and/or the further column magnetic separator is configured to: i) process 30-50 tonne of magnetite ore per hour; and/or ii) use approximately 80-120 cubic metres of water per hour.

[024] In an embodiment, concentrate from the column magnetic separator reports directly to the further column magnetic separator.

[025] In an embodiment, tailings from the column magnetic separator and/or the further column magnetic separator are processed through a regrinding circuit.

[026] In an embodiment, the tailings processed through the regrinding circuit return to the column magnetic separator and/or the further column magnetic separator.

[027] In an embodiment, the separating device includes a screen. [028] In an embodiment, the screen assists with rejecting coarse particles to a tailings area.

[029] In an embodiment, the screen includes apertures with a size of 50pm to 150pm.

[030] In an embodiment, the screen is in the form of a vibrating screen.

[031] In an embodiment, the vibrating screen is a stack sizer vibrating screen. In an embodiment, the stack sizer vibrating screen includes a plurality of screen decks positioned one above the other.

[032] In an embodiment, tailings from the screen report to a tailings area when the magnetic iron loss caused by the rejection is below approximately 1.5%. In another embodiment, the rejection is below approximately 1%.

[033] In a further embodiment, tailings form the screen return to a grinding circuit for regrinding.

[034] In an embodiment, the separating device includes a thickening magnetic separator.

[035] In an embodiment, the thickening magnetic separator is configured to adjust the magnetic mineral slurry density of the magnetite ore.

[036] In an embodiment, the thickening magnetic separator is configured to dewater the magnetite ore to obtain a predetermined density.

[037] In an embodiment, the predetermined density assists with the performance of the column magnetic separator.

[038] In an embodiment, regrinding of the magnetite ore includes using a vertical stirred mill and/or a cyclone cluster.

[039] In an embodiment, the system includes multiple separating devices.

[040] In a second aspect, the present disclosure provides a method for mining, the method including the steps of: processing magnetite ore with a separating device; and separating magnetite from the magnetite ore as the magnetite ore moves along a body of a column magnetic separator, wherein the separating device and column magnetic separator work in combination to improve one or more process parameters in extracting magnetite.

[041] In an embodiment, the separating device includes any combination of one or more of the magnetic separator, further column magnetic separator, screen or the thickening magnetic separator.

[042] In an embodiment, the magnetite ore enters the magnetic separator, fine screen or thickening magnetic separator before entering the column magnetic separator and/or the further column magnetic separator.

[043] In an embodiment, the method further includes the step of regrinding the magnetite ore.

[044] In an embodiment, the step of regrinding the magnetite ore takes place after tailings from the screen, the column magnetic separator and/or the further column magnetic separator are directed towards regrinding.

[045] In an embodiment, the step of regrinding includes using a vertical stirred mill and/or cyclone to further liberate interlocked particles.

[046] In an embodiment, the magnetite ore has a degree of liberation of above 90% when entering the separating device.

[047] In an embodiment, in response to the magnetite ore having a degree of magnetite liberation of approximately 85%, the method includes processing the magnetite ore through the separating device followed by the column magnetic separator and the further column magnetic separator.

[048] In an embodiment, in response to the magnetite ore having a degree of magnetite liberation of approximately 80%, the screen is used to reject coarse particles before entering the column magnetic separator.

[049] In one or more embodiments, the use of the separating device in conjunction with the column magnetic separator may improve one or more process parameters, such as improved concentrate grade, a higher feed throughput at a coarser grind size or reduced operational costs through the improvement of separation efficiency and the reduction of milling energy consumption.

[050] Further features and advantages of the present disclosure will become apparent from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

[051] Various preferred embodiments of the present disclosure will now be described, by way of examples only, with reference to the accompanying figures, in which:

Figure 1 illustrates a flow diagram relating to a mining system, according to an embodiment of the invention;

Figure 2 illustrates a section view of a drum separator, as depicted in Figure 1 , according to an embodiment of the invention;

Figure 3 illustrates a section view of a magnetic column separator, as depicted in Figure 1 , according to an embodiment of the invention;

Figure 4 illustrates a flow diagram relating to a further mining system, according to an embodiment of the invention;

Figure 5 illustrates a further flow diagram relating to a mining system, according to an embodiment of the invention;

Figures 6A to 6C illustrate flow diagrams relating to variations of a mining system, according to embodiments of the invention; and

Figures 7 to 9 separately illustrate schematics of different mining systems, according to embodiments of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

[052] Figure 1 illustrates a flow diagram relating to use of a mining system 10a. In this regard, the use of a reference numeral followed by a lower case letter typically indicates alternative embodiments of a general element identified by the reference numeral in this specification. Thus for example mining system 10a is similar to but not identical to the mining system 10b. Further, references to an element identified only by the numeral refer to all embodiments of that element. Thus for example a reference to mining system 10 is intended to include both the mining system 10a and the mining system 10b.

[053] The mining system 10a includes a first separating device in the form of a (low intensity) magnetic separator 100a. The magnetic separator 100a is a drum magnetic separator. The magnetic separator 100a is shown further in Figure 2 as magnetic separator 100. The magnetic separator 100 includes a drum 110 and a magnet 120. The drum 110 is elongate and extends in a lateral direction. The drum 110 is configured to rotate. The drum 110 rotates over the magnet 120 to form a magnetic drum. The magnet 120 is located in a lower half of the drum 110. That is, the magnet 120 is located near where the drum 110 interacts with the magnetite ore. The position of the magnet 120 is biased to one side of the drum 110, where magnetite concentrate is intended to be collected. The magnet 120 is a permanent magnet. The magnetic separator 100 also includes a manifold 130. The manifold 130 is configured to assist in evenly distributing the magnetite ore over the drum.

[054] As magnetite ore enters the manifold 130, it makes its way towards a lower end of the drum 110. In this embodiment, a flow of water also passes the lower end of the drum 110. Magnetite particles cluster adjacent the rotating drum 110 due to the magnetic field. When the magnetite particles engage with the drum 110 they are rotated / lifted towards a position that allows them to drop into a concentrate collation area. Meanwhile, the flow of water assists in channelling tailings towards a tailings collation area. In this regard, the magnetic separator 100 assists in separating magnetite from other tailings.

[055] As indicated in Figure 1 , from the magnetic separator 100a, the magnetite concentrate is then passed to a column magnetic separator in the form of desliming elutriation column 200a. Accordingly, the magnetic separator 100a is in communication with the desliming elutriation column 200a. A simplified example of a desliming elutriation column 200a is shown in Figure 3 as desliming elutriation column 200. Other desliming elutriation columns may be implemented including that disclosed in Chinese Application No. 111632753 and Australian Patent No. 2018274955 (both herein incorporated by reference). The desliming elutriation column 200 includes a column body 205, a feed inlet 210, magnet(s) 220, a concentrate outlet 230, a tailings outlet 240 and a water input 250. The desliming elutriation column 200 forms an elongate body that extends in a vertical direction. [056] As magnetite ore enters the feed inlet 210 (from the magnetic separator 100), the ore enters a buffer chute which allows an ore slurry to be: i) distributed more uniformly along the circumference of the (elongate) column body 205; and ii) stabilised as the speed of the flow slurry is reduced. Water is introduced through the water input 250 and flows upwards in a manner that counterflows the incoming ore. This assists in flushing out the tailings which are directed towards the tailings outlet 240. The magnet(s) 220 assist in directing the magnetite towards the concentrate outlet 230. That is, with a combined magnetic and gravity force, together with the buoyancy in the elongate body 205, the: i) magnetic particles form magnetic chains and settle downwardly; ii) non-magnetic particles or poorly interlocked particles will move upwardly as the settling velocity of them is lower than the rising rate of water; and iii) non magnetic particles or poorly interlocked particles that are entrained in magnetic chains will be released from the chains and move upwardly as well. The magnetic field of the magnet(s) 220 can be modified to tune the collection of magnetite. Similarly, the water flow can be varied to (for example) assist in separating tailing from the ore. In the present embodiment, the desliming elutriation columns 200 are configured to process 30-50 t/hr of ore with a water consumption of 80-120 m ³ /hr.

[057] The non-obvious benefit of using the desliming elutriation column 200, in combination with the magnetic separator 100, is that it allows for variation of the ore properties. That is, the desliming elutriation column 200 accommodates a varying grain size of magnetite ore, compared to the magnetic separator 100, and the two devices working together increase the amount of concentrate and reduce the tailings.

[058] Figure 4 illustrates a further flow diagram relating to use of a mining system 10b. In a similar manner to mining system 10a, product generated from (for instance) a previous stage grinding circuit with a higher degree of liberation for magnetite (eg, >90%) reports to the mining system 10b. The product then enters a first stage desliming elutriation column 200b where, in a similar manner to the mining system 10a, magnetite ore is separated into a magnetite concentrate and poorly interlocked magnetic particles and slimes are rejected as tailings. In comparison to the mining system 10a, in the mining system 10b, the magnetite concentrate is then passed to a second desliming elutriation column 200b' where the magnetite ore is again processed to further separate magnetite from other tailings.

[059] An advantage of utilising the two desliming elutriation columns 200b, 200b' together, in series, is that the second desliming elutriation column 200b' can compensate for inefficiencies, short-circuiting and surging in the first desliming elutriation column 200b, further improving the final concentrate grade. Accordingly, overall, a higher concentration grade can be obtained as the desliming elutriation columns 200b, 200b' work together, and can be individually tuned based on ore input flow, water flow and/or the magnetic field, to deliver a more ideal outcome.

[060] Figure 5 illustrates a flow diagram for further improving magnetic iron recovery when a lower degree of liberation magnetite (eg, >85%) is provided to a mining system 10c. In this system, magnetite ore is processed through one magnetic separator 100c, followed by two desliming elutriation columns 200c, 200c', and the tailings from the desliming elutriation columns 200c, 200c' are fed to a regrinding circuit 300c. The regrinding circuit 300c then returns a finer ground ore to the magnetic separator 100c. The finer ground ore is more easily separated, further benefiting the separation of magnetite from other (undesired) tailings. In other words, the regrinding circuit 300c assists in further improving concentrate grade and decreases magnetic iron loss.

[061 ] Figures 6A to 6C illustrate other additional mining system 10d, 10e, 10f for further improving the magnetite concentrate grade based on the ore received. The product generated from a grinding circuit 400 (including 400d, 400e and 400f), with at least a degree of liberation higher than 80%, reports to the magnetic separators 100d, 100e, 10Of in each of the systems 10d, 10e, 10f. Following this, the magnetic separators 100d, 100e, 10Of reject parts of non magnetic particles and slimes to tailings. The magnetic separators 100d, 100e, 10Of then separately feed concentrate to a separating device in the form of the screens 500d, 500e, 500f. The screen(s) 500 include a plurality of apertures to assist with separating and sorting the magnetite ore. Normally, the aperture sizes are approximately 100pm. The screen(s) 500 are usually also a stack sizer vibrating screens, which consists of up to five individual screen decks positioned one above the other and operating in parallel, providing high capacity and efficiency.

[062] In Figure 6A, oversize materials directed to the (fine) screen 500d will be rejected to a tailing pile, whilst the undersize material reports to a separating device in the form of thickening magnetic separator 600d. The thickening magnetic separator 600d is configured to adjust the mineral slurry density in upstream and downstream operations. Conventional dewatering tanks and thickening ponds, occupying large area, can be replaced by the thickening magnetic separators 600d in thickening operation of strong magnetic minerals. Thickening magnetic separator 600d is configured to adjust the water amount so as to assure suitable density of the concentrate. Concentrate is moved onto the desliming elutriation columns 200d after the thickening magnetic separator 600d. The thickening magnetic separator 600d is configured to unload magnetic particles by (for example) a scraper in a non-magnetic zone. Tailings (eg, non magnetic particles, slimes and poorly interlocked materials) are also unloaded through the thickening magnetic separator 600d to a tailings pile. In the final stage of mining system 10e, the desliming elutriation column 200d works in the same manner shown in Figures 1 and 3.

[063] In Figure 6B, the system 10e is similar to 10d but the oversize material from the screen 500e is returned to the grinding circuit 400e. This assists in ensuring that the ore is properly grounded, and adds the potential to increase the amount of magnetite recovered, without a dramatic increase in energy consumption. It would be appreciated that the oversize material may be returned to the grinding circuit 400e via a pump or the alike. The thickening magnetic separator 600e and desliming elutriation column 200e work in the same manner as the thickening magnetic separator 600d and desliming elutriation column 200d.

[064] Figure 6C illustrates a system 10f, that is similar to system 10e, but the oversize material of fine screen 500f is fed to a separate regrinding circuit 300f (which is often closed with a vertical stirred mill and cyclone cluster (discussed further below)). Regrinding circuit products return to the previous stage associated with the magnetic separator 10Of. The undersize material of fine screen 500f reports to thickening magnetic separator 600f. The thickening magnetic separator 600f concentrate then reports to the desliming elutriation column 200f to obtain the desired concentrate. The tailings of desliming elutriation column 200f are fed to the regrinding circuit 300f for regrinding. With the additional fine grinding, a higher magnetic iron recovery can be secured.

[065] Figure 7 illustrates a mining system 10g, according to a further embodiment of the invention. In this embodiment, an autogenous (AG) mill grinding circuit reports to a first magnetic separator 100g. The first magnetic separator 100g rejects non-magnetic materials, approximately 48% of the total mass, to tailings. The concentrate from the first magnetic separator 100g is pumped to a ball mill circuit for classification and/or regrinding, and this circuit is closed by ball mill 900g and secondary cyclone cluster 800g. The ball mill circuit produces a fine secondary cyclone overflow with a particle size (P80) of around 35-50 pm (and the degree of liberation for magnetite is approximately >85%). The secondary cyclone overflow reports to secondary magnetic separator 100g'. The secondary magnetic separator 10Og' rejects around 17% of the total mass to tailings. Concentrate from the secondary magnetic separator 10Og' is then fed to desliming elutriation column 200g.

[066] To illustrate the effectiveness of the mining system 10g, compared to other traditional mining techniques, the following data has been populated in the table below. By using the desliming elutriation column 200g, in combination with the other separating devices, the amount of iron concentrate has been suitably increased whilst tailings have decreased compared to more traditional arrangements. That is, the concentrate grade is typically higher by 1.0%-2.0%, and the tailings grade is lower than by 3.0%-4.0%. Furthermore, the mining system 10g rejected more poorly interlocked particles compared to traditional processes, meaning the magnetic iron loss was also lower.

[067] In addition, market requirements dictate that the concentrate grade be maintained at around 65%. Hence, given the ability of system 10g to maintain a concentrate grade above 65%, the application of system 10g potentially releases the ability to process new, lower grade feed throughput. This opens up another -10% of feed throughput that could be processed (compared to traditional technologies). This is another non-obvious advantage of using the system 10g that is of economic importance. Moreover, system 10g can obtain the qualified concentrate at coarser grind sizes, which leads to reasonable energy savings due to less grinding requirements. It has been estimated that power consumption will decrease by approximately 10%, using the same number of processing steps, whilst the concentrate yield increases as outlined above. Again, this is a significant advantage.

[068] Figure 8 illustrates a mining system 10h, according to an embodiment of the invention. The mining system 10h is similar to mining system 10g in that a primary magnetic separator 100h, secondary cyclone cluster 800h and ball mill 900h are used. However, in comparison to mining system 10g, mining system 10h includes a first desliming elutriation column 200h and a second desliming elutriation column 200h'. The desliming elutriation columns 200h, 200h' would provide similar benefits to system 10b. That is, in comparison to using the magnetic separator 10Og', utilising the two desliming elutriation columns 200h, 200h' together, in series, can compensate for inefficiencies, short-circuiting and surging in the first desliming elutriation column 200h', further improving the final concentrate grade. These non-obvious advantages have been identified based on a significant amount of systems based work and analysis, in an environment where downtime is costly and traditional practices are preferred.

[069] Figure 9 illustrates a further mining system 10i where the benefit of combining a desliming elutriation column 600i with a screen 500i, a thickening magnetic separator 600i and an alternative grinding circuit including a vertical mill 110Oi. In a similar manner to system 10g shown in Figure 7, primary cyclone overflow discharged from an AG mill circuit reports to the magnetic separator 10Oi, which rejects coarse non-magnetic materials (around 44% of the total mass in this embodiment) to tailings. Concentrate from the magnetic separator 10Oi is pumped to a ball mill circuit for regrinding and classification and, in the same manner as system 10g, this circuit is closed by ball mill 900g and secondary cyclone cluster 800g. The ball mill circuit produces fines from the secondary cyclone overflow with a particle size (P80) of around 45-53 pm (the degree of liberation for magnetite is approximately >80%). The secondary cyclone overflow reports to a secondary magnetic separator 100g which rejects around 17% of the total mass to tailings.

[070] Concentrate from the secondary magnetic separator 100g is then fed to fine screen 500i, and the oversize material (0.3% of the total mass) is rejected whilst the undersize material reports to the thickening magnetic separator 600i. For the oversize material, magnetic Fe recovery is optionally improved by sending the oversize material to vertical stirred mill 110Oi, which is closed with tertiary cyclone cluster 10OOi. Underflow from the tertiary cyclone cluster 1000Ϊ returns to the vertical stirred mill 110Oi and overflow reports to the secondary magnetic separator 10Oi' feed hopper. To this end, it has been discovered that when the oversize material of fine screen is ground to ~18 pm - 28 pm, concentrate with grade around 64% could be obtained, but the mass is recovered is relatively small (only 0.05% of the total mass). Compared with the input energy consumption to regrind, it may therefore be uneconomical and unnecessary to process the oversize material depending on the nature of the ore.

[071] With the above in mind, concentrate from the thickening magnetic separator 600i reports to desliming elutriation column 200i, and around 2.6% of the total mass is rejected to tailings and the desired concentrate is obtained. The following table illustrates indicative results for using the system 10i in comparison to other traditional processes.

[072] The trial results show that, when the new feed throughput reaches 1411 t/h, the traditional system could only obtain concentrate with grade of 62.6%. However, with the new system 10i (particularly using the combined application of the screen 500i and desliming elutriation column 200i) the final concentrate grade could achieve 66%. This is a significant improvement in the beneficiation of magnetite.

[073] The mining systems 10 improve one or more process parameters in extracting magnetite, including increasing the magnetite concentrate grade during production, reducing energy consumption and lowering operational costs. This makes the use of magnetite more commercially viable and can lead to, for example, less carbon emissions in the production of premium-quality steel. Accordingly, in addition to the economic benefits, the mining systems 10 have non-obvious associated environmental benefits. The mining systems 10 also render separation processes shorter by using less concentrate cleaning stages, allowing less use of separating equipment at lower maintenance demand.

[074] In this specification, adjectives such as left and right, top and bottom, hot and cold, first and second, and the like may be used to distinguish one element or action from another element or action without necessarily requiring or implying any actual such relationship or order. Where context permits, reference to a component, an integer or step (or the alike) is not to be construed as being limited to only one of that component, integer, or step, but rather could be one or more of that component, integer or step.

[075] In this specification, the terms ‘comprises’, ‘comprising’, ‘includes’, ‘including’, or similar terms are intended to mean a non-exclusive inclusion, such that a method, system or apparatus that comprises a list of elements does not include those elements solely, but may well include other elements not listed. [076] The above description relating to embodiments of the present disclosure is provided for purposes of description to one of ordinary skill in the related art. It is not intended to be exhaustive or to limit the disclosure to a single disclosed embodiment. As mentioned above, numerous alternatives and variations to the present disclosure will be apparent to those skilled in the art from the above teaching. Accordingly, while some alternative embodiments have been discussed specifically, other embodiments will be apparent or relatively easily developed by those of ordinary skill in the art. The present disclosure is intended to embrace all modifications, alternatives, and variations that have been discussed herein, and other embodiments that fall within the spirit and scope of the above description.