Bauxite mining

Abstract

Disclosed is a process of utilising ferruginous laterite (14) in bauxite mining. The process may include providing a laterite source and a bauxite source (16) from a bauxite mine (12), and separating the laterite source into a first laterite fraction (24) that is enriched with a non-magnetic bauxite-like material and a second laterite fraction (22) that is iron enriched laterite. The second laterite fraction (22) may be directed to an iron refinery (44). A bauxite mine (12), Bayer plant (26), and iron refinery (44) configured to implement the process are also disclosed.

Description

[0001] Bauxite Mining

[0002] Technical Field

[0003] The present disclosure relates to the field of mineral processing and resource extraction, such as bauxite mining.

[0004] Background

[0005] Bauxite mining operations face significant challenges in efficiently utilizing all extracted materials from mining sites. Traditionally, the ferruginous laterite layer overlying bauxite deposits has been treated as overburden or waste material, requiring removal to access the valuable bauxite ore beneath. This practice results in large volumes of potentially useful material being discarded or stockpiled, leading to increased environmental impact and reduced resource efficiency.

[0006] Conventional bauxite mining processes focus primarily on extracting and processing the bauxite ore for alumina production through the Bayer process. The laterite layer, despite containing valuable minerals such as iron oxides, is often neglected due to its complex composition and the lack of economically viable methods for its utilisation.

[0007] Summary

[0008] An embodiment provides a process of utilising ferruginous laterite in bauxite mining, the process comprising: providing a laterite source and a bauxite source from a bauxite mine; and separating the laterite source into a first laterite fraction that is enriched with a nonmagnetic bauxite-like material and a second laterite fraction that is iron enriched laterite.

[0009] The process may further comprise combining at least a portion of the first laterite fraction with bauxite to form a combined feed that is fed to a Bayer process. The process may further comprise washing bauxite from the bauxite source to produce a washed bauxite stream, and combining the first laterite fraction with the washed bauxite stream to form the combined feed. The process may further comprise determining a composition of the first laterite fraction and blending the first laterite fraction with bauxite from the bauxite source based on the determined composition such that the combined feed has a target alumina-to-silica ratio.

[0010] Separating the laterite source may comprise dry magnetic separation. Separating the laterite source may comprise air classification to separate fine particles from coarser particles. The process may further comprise crushing the laterite source to a maximum size below a threshold value, such as about 150 mm, prior to separating. The process may further comprise grinding the laterite source to a maximum size below a threshold value. Grinding may comprise using a dry milling system.

[0011] The process may further comprise drying the laterite source prior to separating, such as to have a moisture content less than about 5 wt%. The process may further comprise directing at least a portion of the second laterite fraction to an iron refinery. Drying the laterite source may include using excess heat from the iron refinery. The process may further comprise performing dry separation on ground laterite ore to further increase iron content.

[0012] The process may further comprise removing silicon-containing material from the laterite source to form a silicon fraction. Air classification may remove silicon-containing material from the laterite source. The silicon-containing material may comprise kaolinite. Removing silicon- containing material may occur prior to separating the laterite source into the first laterite fraction and the second laterite fraction. Alternatively, removing silicon-containing material may occur after separating the laterite source into the first laterite fraction and the second laterite fraction. Forming the silicon fraction may include grinding the laterite source to a target particle size and removing particles below a threshold size to reduce silicon content in the first laterite fraction and the second laterite fraction.

[0013] The process may further comprise milling the laterite source, separating milled laterite based on size, and returning oversized material to milling for further size reduction. The process may further comprise performing magnetic separation on the oversized material prior to returning the oversized material to milling. The oversized material may comprise unliberated particles containing iron-bearing minerals.

[0014] An embodiment provides a bauxite mine, comprising: a laterite source; a bauxite source; a separator configured to process laterite from the laterite source to produce a first fraction enriched with a non-magnetic bauxite-like material and a second fraction enriched with a laterite material.

[0015] The bauxite mine may further comprise a mixing unit configured to combine at least a portion of the first fraction with bauxite from the bauxite source to form a combined feed that can be fed to a Bayer plant. An embodiment provides a Bayer plant, comprising a feedstock that includes the first fraction from the bauxite mine as set forth above.

[0016] An embodiment provides a Bayer plant, comprising: a feed stock that includes the bauxite source from the bauxite mine as set forth above; and a mixing unit configured to combine at least a portion of the first fraction from the bauxite mine as set forth above with bauxite from the bauxite source to form a combined feed that can be utilised by the Bayer plant.

[0017] An embodiment provides an iron refinery comprising a feedstock that includes the second fraction from the bauxite mine as set forth above.

[0018] An embodiment provides a process of providing a laterite feedstock to an iron refinery, comprising: performing the process as set forth above and directing the second fraction enriched with a laterite material to the iron refinery.

[0019] An embodiment provides a process of preparing a low silicon, high iron laterite fraction, the process comprising: providing a laterite source from a bauxite mine; separating the laterite source to produce a laterite fraction that is iron enriched; separating the laterite fraction into an ultrafine stream and a low silicon, high iron laterite fraction; and directing the ultrafine stream to a magnetic separator to recover iron-containing material.

[0020] The process may further comprise combining the iron-containing material recovered from the magnetic separator with the low silicon, high iron laterite fraction. The magnetic separator may produce a silicon fraction from the ultrafine stream. The process may further comprise directing the low silicon, high iron laterite fraction to an iron refinery.

[0021] Brief Description of the Drawings

[0022] Embodiments will now be described, by way of example only, with reference to the accompanying non-limiting drawings, in which:

[0023] Figure 1 is a schematic diagram of an embodiment of a system for processing materials from a bauxite mine. Figure 2 is a flowchart of an embodiment of a process for utilizing ferruginous laterite in bauxite mining.

[0024] Figure 3 is a schematic diagram of an embodiment of a mining system for processing materials from a bauxite mine.

[0025] Figure 4 is a schematic diagram of an embodiment of a mining system for processing materials from a bauxite mine.

[0026] Figure 5 is a schematic diagram of an embodiment of a separation system.

[0027] Figure 6 is a schematic diagram of another embodiment of a separation a system.

[0028] Figure 7 is a schematic diagram of an embodiment of a mining system for processing materials from a bauxite mine.

[0029] Detailed Description

[0030] The present disclosure relates to a process for utilizing ferruginous laterite in bauxite mining operations. This process provides an approach to extracting value from laterite layers that are typically considered waste material in bauxite mining. By separating the laterite into different fractions, the process may allow for more efficient use of resources and potentially improve the overall economics of mining operations.

[0031] The process begins with providing a laterite source and a bauxite source from a bauxite mine. The laterite source refers generally to the raw, unprocessed ferruginous laterite material as it is extracted from the bauxite mine. The laterite source, which is often found above the bauxite source (also referred to as bauxite layer), may be enriched with respect to iron oxide in some cases. This enrichment may enhance the economics of the process and improve the iron oxide grade or mineralogy of the extracted materials. To access the bauxite, the laterite source typically needs to be removed, so there may be no additional cost per se in providing the laterite source.

[0032] The process involves separating the laterite source into two distinct laterite fractions. In this way, the laterite fractions are derived from the laterite source. The first laterite fraction is enriched with a non-magnetic bauxite-like material. This fraction may have a composition similar to bauxite, potentially making it suitable for alumina production, and can be referred to as the bauxite-like fraction. The second laterite fraction is of an iron enriched laterite. -The second laterite fraction typically contains magnetic material, such as iron oxide. However, it should be appreciated that the magnetic behaviour or properties of this laterite material can be affected by a size of the particles that make up the second laterite fraction. As used herein, the term "bauxite-like material" refers to a material that has compositional or mineralogical characteristics similar to bauxite, particularly with respect to its alumina content and potential suitability for alumina production. This material may have an alumina-to-silica ratio approaching that of typical bauxite, although this ratio may vary within a broader range. In some cases, a bauxite-like material may have a higher iron content compared to conventional bauxite. The term "bauxite-like material" may encompass materials that, while not classified as bauxite in a strict geological sense, may be processed using methods similar to those used for bauxite in alumina production.

[0033] As used herein, the term "iron enriched laterite" refers to a material derived from laterite that has an increased concentration of iron-bearing minerals compared to the original laterite source. This material may contain iron oxides such as hematite, goethite, or magnetite in elevated proportions. The enrichment may be achieved through separation processes that concentrate iron-bearing components whilst reducing the relative proportion of other minerals such as aluminium-bearing or silicon-bearing species. In some cases, iron enriched laterite may exhibit magnetic properties due to the presence of magnetic iron oxide minerals. The degree of iron enrichment may vary depending on the separation techniques employed and the mineralogical characteristics of the source material. Iron enriched laterite may be suitable for use as a feedstock in iron production processes, such as those employed in iron refineries.

[0034] As used herein, the term "enriched" when describing the first fraction and second fraction refers to a material that has a higher concentration or proportion of a particular component or mineral compared to its original state or source material. For example, a fraction enriched with respect to iron oxide may contain a greater percentage of iron oxide by weight or volume than the original laterite source from which it was derived. Enriching can also include removing nontarget species. For example, removal of silicon-containing material can enrich the first and / or second fractions. The degree of enrichment may vary depending on the specific separation or processing techniques employed. The term "enriched" does not preclude the presence of other components in the enriched fraction. For example, the first fraction is enriched with a non-magnetic bauxite-like material but may include one or more components of the second fraction like those from ferruginous laterite.

[0035] As used herein, the term "layer" may be used interchangeably with the terms such as "source" when referring to the different phases or components of the ferruginous laterite. For example, references to a "laterite layer" may encompass the laterite source as extracted from the mine, as well as the various fractions derived from processing the laterite source. Similarly, the term "bauxite layer" may be used interchangeably with "bauxite source" to refer to the bauxite ore body within the mine. The use of these terms is intended to provide flexibility in describing the materials at different stages of extraction and processing, and should not be construed as limiting the scope of the disclosure.

[0036] In some embodiments, at least a portion of the bauxite-like fraction may be combined with bauxite from the bauxite source. This combined feed may then be directed to a Bayer process for alumina production. By incorporating the bauxite-like fraction from the laterite into the Bayer process feed, the overall yield of alumina from the mine may be increased and / or the amount of bauxite required may be reduced in some cases.

[0037] This process may offer several advantages in one or more embodiments. It may allow for the utilisation of laterite material that would otherwise be considered waste, potentially increasing the overall resource efficiency of the mining operation. The separation of the laterite into different fractions may also provide flexibility in how these materials are used, potentially opening up new revenue streams or improving existing ones. Additionally, by enriching the laterite with respect to iron oxide, the process may enhance the value of the magnetic fraction for iron production.

[0038] The bauxite-like fraction, bauxite source, and second laterite fraction may be utilised by a Bayer plant or iron refinery in various ways. For example, the bauxite-like fraction could potentially be sold to refineries with low-iron bauxite feedstocks. The process of utilising ferruginous laterite in bauxite mining may provide options for blending different fractions to optimise feeds for both alumina and iron production.

[0039] In some embodiments, a bauxite mine may include a separator configured to process laterite from the laterite layer to produce a laterite product comprising a first bauxite-like fraction having non-magnetic material and a second laterite fraction having magnetic material. This configuration may allow for efficient separation and utilisation of the laterite material.

[0040] The bauxite mine may also include a mixing unit configured to combine at least a portion of the first bauxite-like fraction with bauxite from the bauxite source to form a combined feed. This combined feed may then be directed to a Bayer plant for processing. By incorporating the bauxite-like fraction into the feed, the Bayer plant may potentially increase its overall alumina yield or reduce the amount of bauxite required for processing in some cases.

[0041] In some embodiments, a Bayer plant may be designed to specifically accommodate a feedstock that includes the first bauxite-like fraction from the bauxite mine. This configuration may allow the plant to efficiently process the combined feed of bauxite and bauxite-like fraction, potentially optimizing alumina production.

[0042] Alternatively, a Bayer plant may be equipped with a mixing unit configured to combine at least a portion of the first bauxite-like fraction with bauxite from the bauxite source to form a combined feed. This arrangement may provide flexibility in feed composition and potentially improve the overall efficiency of the alumina production process.

[0043] The laterite source may be upgraded by removing non-target species or minerals. For example, fine silicon species, such as kaolinite, may be removed as part of the separation process. This upgrading can occur before or after separation into the first and second fractions. Removing fine silicon species will increase the iron content of the second fraction enriched with laterite material and improve downstream processes like iron smelting. The removed silicon-rich fraction may itself be a valuable product and / or returned to the mine as part of rehabilitation. The specific method used may depend on factors such as the mineralogy of the laterite, desired product specifications, and economic considerations.

[0044] For the second laterite fraction, which contains magnetic material, an iron refinery may be configured to use this fraction as part of its feedstock. This utilisation may allow for the extraction of iron from material that would otherwise be considered waste in traditional bauxite mining operations. In an embodiment, non-iron containing material, such as silicon-containing material, may be removed from the second laterite fraction before being utilised in an iron refinery.

[0045] Embodiments will now be described with reference to the Figures.

[0046] Figure 1 illustrates a system diagram 10 that provides an overview of the main components and material flows in the system.

[0047] A bauxite mine 12 includes ore having multiple layers of material, including a ferruginous laterite 14 and a bauxite 16. In some cases, the ore may also include a transition layer 18 between the ferruginous laterite 14 and the bauxite 16. The bauxite mine 12 also includes overburden and other layers, but these are not shown in the Figures for clarity only. The mining process may involve removing the ferruginous laterite 14 and transition layer to expose the bauxite 16, with the transition layer 18 being handled according to its composition and economic value. The system diagram 10 includes a separator 20 that receives material from the ferruginous laterite 14. The separator 20 is configured to divide the input material into two distinct fractions: a laterite fraction 22 and a bauxite-like fraction 24. The separator may also generate a third fraction having predominately silicon-containing material. In some embodiments, the separator 20 is also configured to divide the input material into a third fraction. The third fraction may include silicon-containing materials such as kaolinite.

[0048] The separator 20 may be located at various points within the mining operation, depending on factors such as site layout, logistics, and operational requirements. In some implementations, the separator 20 may be positioned near the mining area to minimise transportation of raw laterite material. This proximity to the extraction site may allow for immediate processing of the laterite, potentially reducing handling costs and improving overall efficiency.

[0049] Alternatively, the separator 20 may be situated at a centralised processing facility within the mine complex. This arrangement may facilitate integration with other processing equipment and allow for more efficient use of utilities and infrastructure. In some cases, the separator 20 may be co-located with crushing and grinding equipment to streamline the material preparation process. In certain aspects, the separator 20 may be a mobile or semi-mobile unit that can be repositioned as mining progresses through different areas of the deposit. This flexibility may allow for optimisation of material handling and transportation routes over the life of the mine. The specific location of the separator 20 may also be influenced by factors such as available space, topography, and environmental considerations. In some implementations, it may be advantageous to position the separator 20 in a way that minimises dust emissions or noise impacts on surrounding areas.

[0050] Regardless of its precise location, the separator 20 may be integrated into the overall material flow of the mining operation, with appropriate conveying systems or transport mechanisms to receive input from the ferruginous laterite 14 and distribute the resulting fractions to their respective destinations.

[0051] The laterite fraction 22 is generally rich in iron oxide species and may be suitable for use as an iron source, such as that used in an iron refinery to produce iron. The iron refinery for processing the laterite fraction 22 may be located at or in close proximity to the bauxite mine 12. In other cases, the iron refinery for processing the laterite fraction 22 may be different from an iron refinery that processes bauxite residue. In some embodiments, the separator 20 is located at or near an iron refinery. The bauxite-like fraction 24 may have properties similar to bauxite, potentially making it suitable for alumina production. As used herein, the term "bauxite-like" may refer to a material that has compositional or mineralogical characteristics similar to bauxite, particularly with respect to its alumina content and potential suitability for alumina production. This material may have an alumina-to-silica ratio approaching that of typical bauxite, although this ratio may vary within a broader range. In some cases, a bauxite-like material may have a higher iron content compared to conventional bauxite. The term "bauxite-like" may encompass materials that, while not classified as bauxite in a strict geological sense, may be processed using methods similar to those used for bauxite in alumina production.

[0052] The system diagram 10 also includes a Bayer plant 26. In some cases, the bauxite-like fraction 24 may be combined with the bauxite 16 to form a combined feed that is used in the Bayer plant 26. This combination may allow for more efficient utilisation of the mined materials and potentially improve the overall yield of alumina from the bauxite mine 12.

[0053] The bauxite-like fraction may be combined with the bauxite for several reasons. For example, blending the bauxite-like fraction with bauxite may allow for the feed composition to meet requirements of the Bayer process, the bauxite-like fraction may contain recoverable alumina so combining it with bauxite may help to improve the overall alumina yield from the mining operation or may reduce the amount of bauxite required from the primary ore body. The bauxite-like fraction may have a different impurity profile compared to the bauxite, so blending the two may help balance certain impurities, potentially leading to improved overall feed quality for the Bayer process. Combining the bauxite-like fraction with bauxite may also simplify material handling and transportation processes since it may reduce the number of feed streams. Utilising the bauxite-like fraction, which may otherwise be considered waste material, may help to improve the overall economics of the mining operation by extracting value from a larger portion of the mined material.

[0054] The system and process illustrated in the system diagram 10 may provide a means to utilise material from the ferruginous laterite 14 that might otherwise be considered waste in traditional bauxite mining operations. By separating the ferruginous laterite 14 into different fractions and finding uses for each fraction, the system may improve the overall resource efficiency and potentially enhance the economics of the mining operation.

[0055] Figure 2 illustrates a process 100 that provides a detailed flow of operations for the system diagram 10 introduced in Figure 1. The process 100 outlines the steps involved in utilizing ferruginous laterite in bauxite mining. The process 100 begins with a step 110 of providing a laterite source and a bauxite source from the bauxite mine 12. In this step, the ferruginous laterite 14 and the bauxite 16 are extracted from their respective layers within the bauxite mine 12. The extraction may involve conventional mining techniques such as drilling, blasting, or excavation, depending on the specific characteristics of the deposit.

[0056] Following the extraction, the process 100 proceeds to a step 112, where the laterite source is separated into two distinct fractions. Step 112 may also separate the laterite source into a third fraction containing e.g. silicon-containing materials. This separation step corresponds to the function of the separator 20 shown in Figure 1. The separator 20 may employ various techniques and processes to divide the ferruginous laterite 14 into the first bauxite-like fraction 24 and the second laterite fraction 22.

[0057] The separation techniques used in step 112 may include crushing to reduce the gross size of the ferruginous laterite, milling to reduce particle sizes of the ferruginous laterite, and then separation which may include dry magnetic separation. Milling may also help to liberate minerals within larger particulate matter. For example, a particle that is half gibbsite and half hematite can broken into one gibbsite particle and one hematite particle.

[0058] Magnetic separation may be particularly effective to separate iron-containing minerals or material from non-iron-containing minerals or material. In some cases, the laterite source may be subjected to crushing and grinding operations, and optionally classification to remove e.g. silicon-containing materials, prior to separation to achieve a desired particle size distribution that facilitates efficient separation. A particle size post-milling may be determined by the end use of the second fraction, for example requirements from an iron refinery. The various separation techniques and processes may have feedback loops, such as sending oversized material in beneficiation back to milling. In an embodiment, a magnetic separator or performing magnetic separation is used on these feedback loop(s). In an embodiment, grinding reduced a size of the particulate matter to about 180pm. Particulate matter with a size <180 pm can be separated off. Due to it natural grain size, the silicon-containing material quickly reports to the finer <180 pm size fraction and is joined by the larger particles that have been milled to this smaller size. The resulting coarse fraction can be recycled back to the mill.

[0059] The process 100 then moves to a step 114, which involves combining at least a portion of the first bauxite-like fraction 24 with the bauxite 16 to form a combined feed. This step is optional, as indicated in Figure 2, and may depend on factors such as the composition of the bauxitelike fraction 24 and the specific requirements of the downstream processing.

[0060] The process 100 illustrated in Figure 2 demonstrates how the ferruginous laterite 14, which may traditionally be considered waste material in bauxite mining operations, can be effectively utilised. By separating the laterite into different fractions and finding uses for each fraction, the process 100 may improve the overall resource efficiency of the mining operation.

[0061] In some cases, the laterite fraction 22 obtained from the separation step 112 may be directed to an iron refinery for iron production. This utilisation of the laterite fraction 22 may provide an additional value stream from material that would otherwise be discarded.

[0062] Figure 3 illustrates a mining system 10a for processing materials from a bauxite mine 12. The mining system 10a is similar to the system diagram 10 shown in Figure 1 , with additional components and details provided. Like features are described with reference to like numerals.

[0063] The bauxite mine 12 in Figure 3 is the same as Figure 1 , having the ferruginous laterite 14, the bauxite 16, and a transition layer 18 between the ferruginous laterite 14 and the bauxite 16. The separator 20 in the mining system 10a includes several components for processing the ferruginous laterite 14. A crusher 32 is first used to reduce the size of the ferruginous laterite 14. In some cases, the crusher 32 may reduce the ferruginous laterite 14 to a maximum size below a threshold value, such as about 150 mm. After crushing, the crushed material is fed into a mill 34. The mill 34 may include a vertical roller mill, a ball mill, or a rod mill. The mill 34 further reduces the size of the material and may include air classification to separate fine particles. For example, air classification or similar may be used to remove silicon-containing material prior to magnetic separation to form the bauxite-like fraction 24 and the laterite fraction 22. Air classification may also help to remove silicon component(s) that is naturally fine and soft from the aluminium-containing component(s) that are harder and of larger grain sizes.

[0064] The crushing and milling operations may be conducted using dry processing techniques to maintain a low moisture content in the processed material. The use of dry crushing and milling may help downstream processing, particularly if the ferruginous laterite 14 is intended for use in an iron refinery. Excessive moisture in the feed material may negatively impact the efficiency of certain iron refining processes. Alternative to dry milling, the ferruginous laterite 14 may be slurried, milled and then filtered, to form a filter cake of higher moisture than the original ore. Dry milling typically involves the use of air classification systems within the mill 34 to separate fine particles. This process may utilise heated air to simultaneously dry the material while it is being ground. In some implementations, the heat for drying may be sourced from waste heat from other processes, such as an iron refinery, potentially improving overall energy efficiency.

[0065] In some cases, if the raw laterite material has a high initial moisture content, a separate drying step may be implemented prior to crushing and milling. This pre-drying step may utilise various methods such as rotary dryers, flash dryers, or fluid bed dryers, depending on the specific requirements of the operation and the characteristics of the material. Heat from the iron refinery 44 may be by the separator 20 to help reduce a moisture content of the ferruginous laterite 14.

[0066] In some embodiments, the dried laterite source may have a moisture content below about 5% by weight. The moisture content may be measured using standard techniques such as loss on drying, or other suitable methods known in the art.

[0067] The use of dry processing may extend to the conveying systems used to transport the material between different stages of the process. In some implementations, pneumatic conveying systems or enclosed belt conveyors may be used to minimise moisture uptake and dust generation during material transfer.

[0068] In some embodiments, following crushing in the crusher 32 and milling in the mill 34, the ferruginous laterite 14 is then processed in a beneficiation unit 36. The beneficiation unit 36 performs dry size and magnetic separation on the material to form the laterite fraction 22 and bauxite-like fraction 24. Dry magnetic separation is performed on the oversize (grits) from the mill classification system. Following beneficiation in the beneficiation unit 36, the resulting laterite fraction 22 can then be directed to an iron refinery 44 for use in iron production. Although Figure 3 show a series arrangement of the crusher 32, mill 34 and beneficiation unit 36 in system 10a, the disclosure is not limited to such an arrangement and may include feedback loops and the like.

[0069] Prior to beneficiation, the ferruginous laterite 14 may also be subjected to the removal of nontarget minerals or materials. In some embodiments, the mining system 10a can include a silicon removal unit 48 that removes silicon-containing material after the ferruginous laterite 14 has been milled in the mill 34 and upstream of the beneficiation unit 36 to form a silicon fraction (i.e. a third fraction). Typically, the silicon containing material are fines liberated in the mill 34. It should be noted that the silicon removal unit 48 is not required in all embodiments, which is why it is shown in a dashed box, and that silicon-containing material may be removed as the third fraction elsewhere, for example in the beneficiation unit 36 as stream 40 or on the laterite fraction 22.

[0070] A return line 46 extends from beneficiation unit 36 to the mill 34 to return oversized magnetic material from the beneficiation unit 36 to the mill 34 for further processing. The return line 46 helps to separate the coarser material, such as gibbsite, and fine material, such as kaolinite. In an embodiment, the formation of return line 46 is from air classification to remove the particles that are sufficiently fine and the rest are returned to the mill 34. Magnetic separation can be performed on this material. The return line 46 can be considered as forming a mill discharge after size separation to remove fine silicon-containing material and iron-containing and magnetic separation to isolate coarser aluminium-containing material. In effect, return line 46 can form a hematite stream with coarser unliberated particles that are returned to the mill 34 for size reduction.

[0071] For the avoidance of doubt, the term "liberated" when used in the context of milling refers to particles that have been sufficiently reduced in size such that individual mineral components are separated from one another. A liberated particle may contain predominantly a single mineral species, such as gibbsite or hematite, rather than a composite of multiple minerals. Conversely, the term "unliberated" refers to particles that contain two or more mineral species that remain physically joined together. An unliberated particle may require further size reduction to separate the constituent minerals into individual liberated particles. For example, an unliberated particle may comprise both iron-bearing minerals and aluminium-bearing minerals that have not yet been separated through the milling process.

[0072] The mining system 10a may also include a washing plant 28 for washing the bauxite 16 to produce a washed bauxite stream 30. The washing plant 28 may be used when the bauxite 16 contains washable silica. Accordingly, the washing plant 28 is not required when the bauxite 16 contains non-washable silica. The washing plant 28 generates wash tailings 38, which are directed to a residue storage 42. Ultra fines 40 from the separator 20 may also be directed to the residue storage 42. The ultra fines 40 may have a size of about 10 pm. In some cases, material from the residue storage 42 may be returned to the bauxite mine 12. If the silicon removal unit 48 is used or not, silicon-containing material is typically present in the ultra fines 40. Although the silicon removal unit 48 is shown as being upstream and separate from the beneficiation unit 36 in Figure 3, in some embodiments the silicon removal unit 48 forms part of the beneficiation unit 36 or is positioned downstream of the beneficiation unit with its output forming the laterite fraction 22. The bauxite-like fraction 26 (i.e. non-magnetic oversize fraction) from the beneficiation unit 36 may be directed to the Bayer plant 26, sold independently, or blended with other materials for sale. For example, and as shown in Figure 3, the washing plant 28 can be combined with the bauxite-like fraction 24 before being fed into the Bayer plant 26. However, if the washing plant 28 is not used, the bauxite-like fraction 24 can be combined with bauxite 16. The reasons for combining the bauxite-like fraction 24 with the washed bauxite stream 30 (or bauxite 16 when the bauxite 16 is not washed) are described above.

[0073] Figure 4 illustrates another embodiment of a mining system 10b that presents an alternative arrangement for processing ferruginous laterite 14. In this configuration, the separator 20a includes a crusher 32, a beneficiation unit 36, and a mill 34 arranged in a different sequence compared to the system 10a shown in Figure 3. However, the crusher 32 is not required in all embodiments of separator 20a. Further, although the silicon fraction 25 is shown as being separate from ultra fines 40, in some instances the silicon fraction 25 and the ultra fines 40 are the same feed material.

[0074] In the mining system 10b, the ferruginous laterite 14 is first processed by the crusher 32. The crushed material is then directed to the beneficiation unit 36 rather than the mill 34. This arrangement may allow for initial separation of the material before fine grinding occurs. The beneficiation unit 36 in this configuration may perform an initial separation of the crushed laterite into different fractions. Oversized material from the beneficiation unit 36 is sent to the mill 34 for further size reduction. After milling, the material may be returned to the beneficiation unit 36 via a recycle line for additional processing. The output from the separator 20a in this configuration includes the laterite fraction 22, the bauxite-like fraction 24, and potentially a silicon fraction 25, similar to the output of system 10a. However, the internal processing steps to achieve this separation differ due to the rearranged components.

[0075] By performing initial beneficiation on coarser material, it may be possible to separate some fractions more efficiently and reduce the amount of fines generated in the mill 34. The recycle loop between the beneficiation unit 36 and the mill 34 may allow for more precise control over particle size distribution and may help prevent over-grinding of certain fractions.

[0076] Figure 5 illustrates a block diagram of a processing system 10c having separator 20b for separating ferruginous laterite 14 into different fractions. The separator 20b includes a crusher 32, mill size separator 36b, magnetic separator 36a and mill 34. The mill size separator 36b forms part of or defines the beneficiation unit 36. The ferruginous laterite 14 is first fed into a crusher 32, which reduces the size of the input material. The crushed material then enters a mill size separator 36b, which separates the material based on size. Appropriately sized material is extracted as a laterite fraction 22. The mill size separator 36b directs oversized material to a magnetic separator 36a.

[0077] The magnetic separator 36a separates out a bauxite-like fraction 24 from the oversized material. The bauxite-like fraction 24 may contains predominantly non-magnetic material, while the remaining material typically contains magnetic material. Magnetic material that was classified as coarse in the mill size separator 36b is directed to a mill 34 for further size reduction. The mill 34 processes this oversized material and sends it back to the mill size separator 36b via return line 46. This recycle process may help ensure that all material is properly sized with minimal overgrinding and minimal power consumption.

[0078] In some embodiments, the configuration shown in Figure 5 may allow for more efficient separation of the ferruginous laterite 14 into distinct fractions based on both size and magnetic properties. The use of the mill size separator 36b before magnetic separation may help optimize the separation process by ensuring that only appropriately sized material undergoes magnetic separation. This arrangement may also allow for continuous processing and refinement of oversized material through the recycle loop, potentially improving overall efficiency and yield.

[0079] Figure 6 illustrates an alternative configuration of a processing system 10d for separating ferruginous laterite 14 into different fractions. The system includes a separator 20c with components arranged in a different sequence compared to the configuration shown in Figure 5.

[0080] In this arrangement, the ferruginous laterite 14 is first processed by a crusher 32, which reduces the size of the input material. The crushed material is then directed to a mill 34 for further size reduction, rather than going to a mill size separator as in the previous configuration. After milling, the material enters a mill size separator 36b. This component separates the milled material based on size, directing oversized particles to a magnetic separator 36a. The magnetic separator 36a then separates the material into a coarse recycle feed that is sent to the mill 34 via return line 46 and a bauxite-like fraction 24 based on magnetic properties.

[0081] The configuration shown in Figure 6 may offer certain advantages in some implementations. By performing milling before size separation, this arrangement may allow for more controlled particle size reduction. The recycle loop may help optimise the overall particle size distribution of the material entering the magnetic separator, potentially improving the efficiency of the magnetic separation process for downstream processing. The ore drying time may also be improved prior to separation steps.

[0082] Figure 7 illustrates a block diagram of a processing system 10e for further separating and processing laterite and bauxite-like fractions. The components shown and described in processing system 10e can be applied to the processing systems 10-1 Od, and the separator 20 may include separator 20a and separator 20b.

[0083] The laterite fraction 22 is directed to a laterite ultrafine separator 60, which separates the laterite fraction 22 into an ultrafine stream 64 and the low silicon, high iron laterite fraction 22a. This may be simply referred to as high iron laterite fraction. The laterite ultrafine separator 60 helps to separate silicon-containing material from the high iron laterite fraction, and can be considered as forming a silicon-removal unit. The ultrafine stream 64 is sent to a magnetic separator 62 that separates the ultrafine stream 64 into a silicon fraction 25 and an iron- containing stream that is combined with the high iron laterite fraction 22a to recover fine iron particles.

[0084] The bauxite-like fraction 24 is processed through an open circuit mill 56 before being sent to a bauxite ultrafine separator 58. The bauxite ultrafine separator 58 produces a low silicon bauxite-like fraction 24a and ultrafine stream 66. The ultrafine stream 66 is sent for processing in the magnetic separator 62 similar to the ultrafine stream 64 for iron recovery.

[0085] The system 10e is designed to separate and process the input materials, producing various fractions with different compositions and properties. The use of additional multiple separation stages and the integration of magnetic separation may allow for the production of low silicon fractions from both the laterite and bauxite-like inputs. The processing system 10e may provide additional flexibility in handling different material compositions and may allow for more precise control over the properties of the output fractions. This configuration may be particularly useful in cases where reducing the silicon content of the laterite and bauxite-like fractions is desirable for downstream processing or end-use applications.

[0086] The mining system 10 and / or 10a-10e demonstrates how various components work together to process different fractions of the mined material, potentially improving overall resource utilisation and efficiency in the mining operation. The process and system described herein may provide several advantages and benefits for bauxite mining operations. By utilizing ferruginous laterite that is typically considered waste material, the process may improve overall resource efficiency and potentially enhance the economics of mining operations. In some cases, the separation of laterite into different fractions may allow for more comprehensive utilisation of mined materials. The bauxite-like fraction obtained from the laterite may be suitable for alumina production, potentially increasing the overall yield of alumina from the mine or reducing the amount of primary bauxite required. This may lead to more efficient use of the bauxite deposit and potentially extend the life of the mine.

[0087] The laterite fraction rich in iron oxide may provide an additional value stream for the mining operation. In some implementations, this fraction may be used as feed for iron production, potentially creating a new revenue source from material that would otherwise be discarded. This may improve the overall economics of the mining operation and provide a more comprehensive utilisation of the mined resources.

[0088] The process may offer flexibility in how the separated fractions are used. In some cases, the bauxite-like fraction may be combined with bauxite to form a combined feed for the Bayer process. This blending may allow for optimisation of feed composition, potentially improving the efficiency of alumina production. Alternatively, the bauxite-like fraction may be processed separately or sold to other refineries, providing additional options for resource utilisation. A dust suppressant, which may include run-of-mine bauxite, may be used during storage and / or transportation of the bauxite-like fraction.

[0089] In some implementations, the process may reduce the environmental impact of mining operations. By utilizing more of the mined material, the process may reduce the volume of waste requiring disposal. This may lead to smaller waste storage requirements and potentially minimise the environmental footprint of the mining operation.

[0090] The system and process may be adaptable to different mining operations and market conditions. The flexibility in how the separated fractions are used may allow mining operations to adjust their practices based on factors such as market demand, processing capabilities, and economic considerations.

[0091] In summary, the described process and system for utilising ferruginous laterite in bauxite mining may offer a range of potential benefits. These may include improved resource efficiency, enhanced economic viability, reduced environmental impact, and increased operational flexibility. By providing a means to extract value from material traditionally considered waste, the process may contribute to more sustainable and efficient mining practices. In the claims that follow and in the preceding description, except where the context requires otherwise due to express language or necessary implication, the word “comprise” or variations such as “comprises” or “comprising” is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the disclosure.

[0092] It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country. Modifications and variations as would be apparent to a skilled addressee are deemed to be within the scope of the present disclosure.

Claims

Claims1 . A process of utilising ferruginous laterite in bauxite mining, the process comprising: providing a laterite source and a bauxite source from a bauxite mine; and separating the laterite source into a first laterite fraction that is enriched with a non-magnetic bauxite-like material and a second laterite fraction that is iron enriched laterite.

2. The process of claim 1 , further comprising combining at least a portion of the first laterite fraction with bauxite to form a combined feed that is fed to a Bayer process.

3. The process of claim 2, further comprising washing bauxite from the bauxite source to produce a washed bauxite stream, and combining the first laterite fraction with the washed bauxite stream to form the combined feed.

4. The process of claim 2 or 3, further comprising: determining a composition of the first laterite fraction; and blending the first laterite fraction with bauxite from the bauxite source based on the determined composition such that the combined feed has a target alumina-to-silica ratio.

5. The process of any one of claims 1 to 4, wherein separating the laterite source comprises dry magnetic separation.

6. The process of any one of claims 1 to 5, further comprising crushing the laterite source to a maximum size below a threshold value, such as about 150 mm.

7. The process of any one of claims 1 to 6, further comprising grinding the laterite source to a maximum size below a threshold value.

8. The process of claim 7, wherein grinding comprises using a dry milling system.

9. The process of any one of claims 1 to 8, further comprising drying the laterite source prior to separating, such as to have a moisture content less than about 5 wt%.

10. The process of any one of claims 1 to 9, further comprising directing at least a portion of the second laterite fraction to an iron refinery.

11. The process of claim 10 when dependent on claim 9, wherein drying the laterite source includes using excess heat from the iron refinery.

12. The process of any one of claims 1 to 11 , further comprising performing dry separation on ground laterite ore to increase iron content.

13. The process of any one of claims 1 to 12, wherein separating the laterite source comprises air classification to separate fine particles from coarser particles.

14. The process of any one of claims 1 to 13, further comprising removing silicon- containing material from the laterite source to form a silicon fraction.

15. The process of claim 14 when dependent on claim 13, wherein air classification removes silicon-containing material from the laterite source.

16. The process of claim 14, wherein the silicon-containing material comprises kaolinite. -17. The process of claim 14 or 16, wherein removing silicon-containing material occurs prior to separating the laterite source into the first laterite fraction and the second laterite fraction.

18. The process of claim 14 or 16, wherein removing silicon-containing material occurs after separating the laterite source into the first laterite fraction and the second laterite fraction.

19. The process of any one of claims 14 to 18, wherein forming the silicon fraction includes: grinding the laterite source to a target particle size; and removing particles below a threshold size to reduce silicon content in the first laterite fraction and the second laterite fraction.

20. The process of claim 1 , further comprising: milling the laterite source; separating milled laterite based on size; and returning oversized material to milling for further size reduction.

21. The process of claim 20, further comprising performing magnetic separation on the oversized material prior to returning the oversized material to milling.

22. The process of claim 20 or 21 , wherein the oversized material comprises unliberated particles containing iron-bearing minerals.

23. A bauxite mine, comprising: a laterite source; a bauxite source; a separator configured to process laterite from the laterite source to produce a first fraction enriched with a non-magnetic bauxite-like material and a second fraction enriched with a laterite material.

24. A bauxite mine of claim 23, further comprising a mixing unit configured to combine at least a portion of the first fraction with bauxite from the bauxite source to form a combined feed that can be fed to a Bayer plant.

25. A Bayer plant, comprising a feedstock that includes the first fraction from the bauxite mine of claim 23 or 24.

26. A Bayer plant, comprising: a feed stock that includes the bauxite source from the bauxite mine of claim 23; and a mixing unit configured to combine at least a portion of the first fraction from the bauxite mine of claim 23 with bauxite from the bauxite source to form a combined feed that can be utilised by the Bayer plant.

27. An iron refinery, comprising a feedstock that includes the second fraction from the bauxite mine of claim 23.

28. A process of providing a laterite feedstock to an iron refinery, comprising: performing the process of any one of claims 1 to 22 and directing the second fraction enriched with a laterite material to the iron refinery.

29. A process of preparing a low silicon, high iron laterite fraction, the process comprising: providing a laterite source from a bauxite mine; separating the laterite source to produce a laterite fraction that is iron enriched;separating the laterite fraction into an ultrafine stream and a low silicon, high iron laterite fraction; and directing the ultrafine stream to a magnetic separator to recover iron-containing material.

30. The process of claim 29, further comprising combining the iron-containing material recovered from the magnetic separator with the low silicon, high iron laterite fraction.

31. The process of claim 29 or 30, wherein the magnetic separator produces a silicon fraction from the ultrafine stream.

32. The process of any one of claims 29 to 31 , further comprising directing the low silicon, high iron laterite fraction to an iron refinery.

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