Beneficiation method of medium-low grade bauxite and application thereof

Abstract

The present application relates to a beneficiation method of medium and low grade bauxite and application thereof, the beneficiation method comprises: (1) sequentially heating, heat preservation and quenching of the medium and low grade bauxite, and obtaining the activated medium and low grade bauxite after solid-liquid separation; (2) sequentially crushing, grinding and grading of the activated medium and low grade bauxite, and obtaining the bauxite concentrate and tailings. The beneficiation method can simply and efficiently process the medium and low grade bauxite, obtain the bauxite concentrate with high aluminum-silicon ratio, effectively improve the recovery rate of medium and low grade bauxite resources, and reduce the production cost.

Description

Technical Field

[0001] This invention relates to the field of metallurgical technology, and in particular to a beneficiation method for medium- and low-grade bauxite and its application. Background Technology

[0002] my country's bauxite resources are mainly monohydrate gibbsite-type bauxite, characterized by high aluminum and high silica content, with the vast majority being medium- to low-grade bauxite with an aluminum-to-silica ratio (A / S) of less than 4. Extensive research and practice have aimed to improve bauxite grade through flotation desilication, followed by the economical Bayer process for alumina production. This method has indeed effectively improved the utilization rate of my country's bauxite resources. However, with the rapid development of my country's alumina industry, the grade of raw bauxite being processed is decreasing, from an A / S ratio > 5 in the early days to below 3.5, and this is expected to continue to decline in the coming years. Therefore, flotation desilication of low-A / S bauxite is becoming increasingly difficult, resulting in worse performance indicators and higher production costs. Developing new separation and enrichment methods suitable for low-grade bauxite with an A / S ratio below 3.5 is of great significance.

[0003] Many patents relate to bauxite beneficiation. For example, CN101927215B discloses a bauxite direct flotation method, whose flotation process includes grinding, classification, and at least one scavenging step; CN102755925A discloses a separation method suitable for medium- and low-grade bauxite, which can process raw ore with an aluminum-silicon ratio of 4 or higher; CN102294304A discloses a bauxite flotation method, characterized by concentrating the raw ore pulp (after grinding to a suitable fineness) or the flotation pulp (with a low concentration) before flotation. The above beneficiation patents can only process raw ore with an aluminum-silicon ratio as low as 4, which no longer meets actual production needs.

[0004] CN108554594A discloses a method for beneficiating low-grade bauxite. This method involves controlled grinding to crush or ball mill monohydrate gibbsite-type bauxite with an A / S ratio less than 3 to obtain bauxite powder. Then, through classification, some fine particles are separated out; these separated fine particles are the low A / S ratio product, with an A / S ratio less than 1.7. The remaining bauxite powder has an A / S ratio greater than 3. While this method can process bauxite with a low A / S ratio, it requires grinding the raw ore to below 10 micrometers. This process is extremely energy-intensive, and the concentrate produced has an A / S ratio not exceeding 4, while the tailings have an A / S ratio as high as 1.7. CN101391237A discloses a novel bauxite direct flotation desilication process, including grinding, classification, flotation, and rougher underflow classification and regrinding. This process is complex, involves redundant auxiliary materials, and the addition of flotation reagents makes the tailings difficult to utilize, leading to long-term accumulation and environmental problems. CN101439317A and CN102806146A both disclose a method for pre-desiliconization in bauxite beneficiation. This method is relatively simple, but it also has the problem of difficult utilization of tailings, and the aluminum-silicon ratio of the raw ore it can process is above 3.5.

[0005] Furthermore, kaolin is one of the important raw materials for the preparation of ceramsite. The tailings produced by the mineral processing method of this invention are rich in kaolin, and the addition of calcium-containing tailings produced by the hydrothermal method can regulate the amount of liquid phase generated during the sintering process of ceramsite, greatly improving the strength of the ceramsite product. Currently, there are many patents for the preparation of ceramsite using kaolin, but methods for preparing ceramsite using kaolin mineral processing tailings and calcium-containing tailings are particularly rare.

[0006] In summary, there is an urgent need to develop a new method for the separation and enrichment of low-grade bauxite with an aluminum-silicon ratio of less than 3.5, so that the separated tailings can be used to prepare ceramsite, and the resulting concentrate fully meets the technical requirements of my country's Bayer process alumina industry. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a beneficiation method for medium- and low-grade bauxite and its application. The beneficiation method of this invention can process medium- and low-grade bauxite with an aluminum-silicon ratio of less than 4, obtaining bauxite concentrate with a high aluminum-silicon ratio. It also effectively improves the resource recovery rate of medium- and low-grade bauxite, reduces production costs, solves potential environmental problems, and creates significant economic value.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a method for beneficiating low- to medium-grade bauxite, the method comprising the following steps:

[0010] (1) The medium and low grade bauxite is heated, kept warm and rapidly cooled in sequence, and then the solid and liquid are separated to obtain activated medium and low grade bauxite.

[0011] (2) The activated low-grade bauxite is crushed, ground and classified in sequence to obtain bauxite concentrate and tailings.

[0012] It should be noted that the low-to-medium grade bauxite of this invention refers to bauxite with an aluminum-to-silicon ratio of <4, such as 3.5, 3.2, 3.0, 2.8, 2.5, 2.3, 2.0, or 1.5, but is not limited to the listed values; other unlisted values ​​within this range are also applicable. The beneficiation method of this invention is applicable to all types of low-to-medium grade bauxite, especially to gibbsite-type bauxite.

[0013] This invention activates the grain boundaries of the silicon-rich and aluminum-rich phases through heating and rapid cooling. Then, through crushing, grinding, and classification, the silicon-rich and aluminum-rich phases in low- to medium-grade bauxite are initially separated, achieving pre-desiliconization. The resulting ore particles are the pre-desiliconized product. Pre-crushing the low- to medium-grade bauxite facilitates subsequent grinding and promotes the separation of the silicon-rich and aluminum-rich phases. Direct grinding of the bauxite would cause the silicon-rich and aluminum-rich phases to become intertwined and difficult to separate, while also increasing energy consumption and reducing efficiency.

[0014] The mineral processing method of this invention separates the aluminum-rich phase and the silicon-rich phase during the hydrothermal reaction, thereby opening up the structure of the raw ore. The aluminum-rich phase is deagglomerated, refined, and activated in situ, increasing the surface energy and thus reducing energy consumption during subsequent Bayer leaching. For example, when the low-grade bauxite is gibbsite-type bauxite, the separation of the aluminum-rich phase and the silicon-rich phase during the hydrothermal reaction opens up the interbedded structure of gibbsite and kaolinite in the raw ore, and the aluminum-rich phase is deagglomerated, refined, and activated in situ.

[0015] The mineral processing method of the present invention is simple, low-cost, does not introduce impurity phases or harmful chemical agents, and reduces the use of natural raw materials, thus saving resources.

[0016] As a preferred technical solution of the present invention, the heating rate in step (1) is 5 to 30°C / min, for example 5°C / min, 10°C / min, 15°C / min, 20°C / min, 22°C / min, 24°C / min, 28°C / min or 30°C / min, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, and it is further preferred to be 10 to 20°C / min.

[0017] As a preferred technical solution of the present invention, the temperature of the heat preservation in step (1) is 200 to 800°C, such as 200°C, 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C or 800°C, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable. More preferably, it is 300 to 500°C.

[0018] Preferably, the heat preservation time is 0.5 to 5 hours, such as 0.5 hours, 1.5 hours, 1.5 hours, 1.8 hours, 2.0 hours, 2.5 hours, 3.5 hours, 4.0 hours, 4.5 hours or 5 hours, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable. More preferably, it is 1 to 3 hours.

[0019] As a preferred technical solution of the present invention, the cooling rate of the rapid cooling in step (1) is 50 to 300℃ / s, for example, 50℃ / s, 60℃ / s, 70℃ / s, 80℃ / s, 90℃ / s, 100℃ / s, 110℃ / s, 120℃ / s, 150℃ / s, 200℃ / s, 250℃ / s or 300℃ / s, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, and it is further preferred to be 100 to 150℃ / s.

[0020] Preferably, the rapid cooling method includes air cooling and / or liquid cooling, with liquid cooling being more preferred.

[0021] Preferably, the liquid used for cooling includes water or a fluorinated liquid, preferably water. Furthermore, the waste heat can be recovered and reused for preheating the ore.

[0022] It should be noted that the solid-liquid separation in step (1) is carried out using conventional methods in the art, as long as the activated low-grade bauxite can be separated from the solution, and no special limitations will be imposed on this. For example, the separation method can be filtration, centrifugation, etc., but is not limited to these.

[0023] As a preferred technical solution of the present invention, based on the total mass of the crushed product obtained by crushing in step (2), the mass fraction of particles with a particle size between 0.5 and 2 cm in the crushed product is 20% to 100%, such as 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100%, but not limited to the listed values. Other unlisted values ​​within this range are also applicable, and it is further preferred to be 30% to 90%.

[0024] It should be noted that the particle size between 0.5 and 2 cm refers to the particle size range of 0.5 cm to 2 cm, including the two endpoints of 0.5 cm and 2 cm.

[0025] In this invention, crushing low- to medium-grade bauxite to the aforementioned particle size range is more conducive to subsequent grinding.

[0026] As a preferred technical solution of the present invention, based on the total mass of the grinding product obtained by grinding in step (2), the mass fraction of particles with a particle size between 74 and 300 μm in the grinding product is 0 to 40%, such as 5%, 10%, 15%, 20%, 25%, 28%, 30%, 35%, or 40%, etc., but not limited to the listed values. Other unlisted values ​​within this range are also applicable, and it is further preferred to be 10 to 30%.

[0027] It should be noted that the particle size between 74 and 300 μm refers to a particle size range of 74 μm to 300 μm, including both 74 μm and 300 μm.

[0028] Preferably, the grinding method in step (2) includes dry grinding or wet grinding.

[0029] Preferably, the grinding method includes any one or a combination of at least two of ball milling, rod milling, pebble milling or autogenous milling. Typical but non-limiting examples of such combinations include ball milling and rod milling, ball milling and pebble milling, ball milling and autogenous milling, pebble milling and autogenous milling, etc., with ball milling being the preferred method.

[0030] Preferably, the grinding time is 1 to 60 minutes, such as 1 minute, 2 minutes, 5 minutes, 10 minutes, 20 minutes, 30 minutes, 40 minutes or 60 minutes, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable. More preferably, it is 5 to 30 minutes.

[0031] In this invention, when the grinding time is too short, the silicon-rich phase and aluminum-rich phase in the mineral are not sufficiently separated; when the grinding time is too long, the mineral particles are too small, making separation difficult, and the energy consumption is high.

[0032] Preferably, the mill speed of the grinding is 5 to 600 r / min, such as 5 r / min, 10 r / min, 15 r / min, 20 r / min, 25 r / min, 30 r / min, 35 r / min, 40 r / min, 45 r / min, 50 r / min, 60 r / min, 70 r / min, 80 r / min, 90 r / min, 100 r / min, 150 r / min, 200 r / min, 250 r / min, 300 r / min, 400 r / min, 500 r / min, 550 r / min, or 600 r / min, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable. More preferably, it is 50 to 300 r / min.

[0033] Preferably, the grinding media filling rate is 20% to 60%, such as 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, or 60%, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, and 30% to 50% is more preferred.

[0034] Preferably, the mill filling rate of the grinding is 30% to 70%, such as 30%, 35%, 38%, 40%, 42%, 45%, 47%, 50%, 55%, or 70%, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, and more preferably it is 40% to 60%.

[0035] In this invention, the selection range of mill speed, media filling rate, and mill filling rate are all the result of comprehensive consideration of cost and separation efficiency. Too high or too low a range will affect the grinding effect.

[0036] As a preferred technical solution of the present invention, the grading in step (2) includes grading particles with a particle size greater than or equal to 74 μm as concentrate and grading particles with a particle size less than 74 μm as tailings.

[0037] Preferably, the grading method includes dry grading or wet grading.

[0038] Preferably, the grading method includes any one or a combination of at least two of the following: screening, air grading, hydrocyclone grading, or chute grading, with screening being the preferred method.

[0039] As a preferred embodiment of the present invention, the aluminum-silicon ratio of the bauxite concentrate is ≥4.0.

[0040] Preferably, the aluminum-silicon ratio of the tailings is <1.5.

[0041] In a second aspect, the present invention provides a bauxite concentrate, which is prepared by the mineral processing method described in the first aspect.

[0042] It should be noted that the mineral processing method described in the first aspect of this invention can also yield tailings.

[0043] Thirdly, the present invention provides an application of bauxite concentrate as described in the second aspect, said bauxite concentrate being used in the Bayer process for the synthesis of alumina.

[0044] Preferably, the tailings can be used to prepare ceramsite.

[0045] Compared with the prior art, the present invention has at least the following beneficial effects:

[0046] (1) This invention uses heating, rapid cooling, crushing, grinding, and classification steps to initially separate the silica-rich phase and aluminum-rich phase in low- and medium-grade bauxite, achieving pre-desiliconization. The resulting ore particles are the pre-desiliconized product. Pre-crushing the low- and medium-grade bauxite facilitates subsequent grinding and promotes the separation of the silica-rich and aluminum-rich phases. Direct grinding of the bauxite would cause the silica-rich and aluminum-rich phases to become intertwined and difficult to separate, while also increasing energy consumption and reducing efficiency.

[0047] (2) In the mineral processing method of the present invention, the aluminum-rich phase and the silicon-rich phase are separated during the hydrothermal reaction, which opens up the structure of the raw ore, and the aluminum-rich phase is depolymerized, refined and activated in situ, thereby increasing the surface energy and reducing the energy consumption during the subsequent Bayer process leaching.

[0048] (3) The mineral processing method of the present invention is simple, low in cost, does not introduce impurity phases and harmful chemical agents, and reduces the use of natural raw materials, thus saving resources.

[0049] (4) The mineral processing method of the present invention has very low requirements for the aluminum-silicon ratio of the raw bauxite ore. For example, after the raw ore with an aluminum-silicon ratio of about 2.5 is processed by the mineral processing method, the aluminum-silicon ratio of the bauxite concentrate can reach more than 4.0, which fully meets the technical requirements of the Bayer process alumina industrial production.

[0050] (5) The bauxite concentrate produced by the mineral processing method of this invention has greatly reduced energy consumption and the amount of red mud produced has decreased sharply, thus truly achieving "turning harm into benefit and waste into treasure", which plays a huge role in promoting the development of green economy and circular economy, achieving the unity of environment, society and economy, and promoting the sustainable development of environment, society and economy. Detailed Implementation

[0051] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0052] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels.

[0053] Example 1

[0054] This embodiment provides a beneficiation method for medium- and low-grade bauxite, the beneficiation method comprising the following steps:

[0055] (1) Provide Luoyang monohydrate gibbsite type bauxite with an A / S ratio of about 2.5, heat it to 400℃ in a kiln at a heating rate of 10℃ / min, hold it for 1h, then water cool it at a rate of 100℃ / s, and then filter it to obtain activated bauxite.

[0056] (2) The activated bauxite is crushed to obtain bauxite particles. Based on the total mass of the bauxite particles, the mass fraction of particles with a particle size between 0.5 and 2 cm is 80%. The bauxite particles are put into a mill and ball-milled for 10 min at a mill speed of 300 r / min, a media filling rate of 30%, and a mill filling rate of 50% to obtain grinding products. Based on the total mass of the grinding products, the mass fraction of particles with a particle size between 74 and 300 μm is 20%. Then, the grinding products are classified using a sieve to obtain concentrate with a particle size between 74 and 300 μm and tailings with a particle size less than 74 μm.

[0057] Example 2

[0058] This embodiment provides a beneficiation method for medium- and low-grade bauxite. The only difference from Embodiment 1 is that it provides Luoyang monohydrate gibbsite-type bauxite with an A / S ratio of approximately 3.5, and the mass fraction of particles with a particle size between 0.5 and 2 cm in the bauxite particles is 40%. All other aspects are the same as in Embodiment 1.

[0059] Example 3

[0060] This embodiment provides a beneficiation method for medium and low grade bauxite. The only difference from Embodiment 1 is that in step (1), the heating rate is 5℃ / min, and the rest is the same as in Embodiment 1.

[0061] Example 4

[0062] This embodiment provides a beneficiation method for medium and low grade bauxite. The only difference from Embodiment 1 is that in step (1), the heating rate is 30℃ / min, and the rest is the same as in Embodiment 1.

[0063] Example 5

[0064] This embodiment provides a beneficiation method for medium and low grade bauxite. The only difference from Embodiment 1 is that in step (1), the heat preservation temperature is 200℃, and the rest is the same as in Embodiment 1.

[0065] Example 6

[0066] This embodiment provides a beneficiation method for medium and low grade bauxite. The only difference from Embodiment 1 is that in step (1), the heat preservation temperature is 800℃, and the rest is the same as in Embodiment 1.

[0067] Example 7

[0068] This embodiment provides a beneficiation method for medium and low grade bauxite. The only difference from Embodiment 1 is that in step (1), the heat preservation time is 0.5h, and the rest is the same as in Embodiment 1.

[0069] Example 8

[0070] This embodiment provides a beneficiation method for medium and low grade bauxite. The only difference from Embodiment 1 is that in step (1), the heat preservation time is 5 hours, and the rest is the same as in Embodiment 1.

[0071] Example 9

[0072] This embodiment provides a beneficiation method for medium- and low-grade bauxite. The only difference from Embodiment 1 is that in step (1), the cooling rate is 50°C / s, while the rest are the same as in Embodiment 1.

[0073] Example 10

[0074] This embodiment provides a beneficiation method for medium and low grade bauxite. The only difference from Embodiment 1 is that in step (1), the cooling rate is 300℃ / s, and the rest is the same as in Embodiment 1.

[0075] Example 11

[0076] This embodiment provides a beneficiation method for medium and low grade bauxite. The only difference from Embodiment 1 is that in step (2), the mass fraction of bauxite particles with a particle size between 0.5 and 2 cm is 100%, while the rest are the same as in Embodiment 1.

[0077] Example 12

[0078] This embodiment provides a beneficiation method for medium- and low-grade bauxite. The only difference from Embodiment 1 is that in step (2), the mass fraction of bauxite particles with a particle size between 0.5 and 2 cm is 20%, while the rest are the same as in Embodiment 1.

[0079] Example 13

[0080] This embodiment provides a beneficiation method for medium and low grade bauxite. The only difference from Embodiment 1 is that in step (2), the ball milling time is 3 minutes, and the rest is the same as in Embodiment 1.

[0081] Example 14

[0082] This embodiment provides a beneficiation method for medium and low grade bauxite. The only difference from Embodiment 1 is that in step (2), the ball milling time is 1 min, and the rest is the same as in Embodiment 1.

[0083] Example 15

[0084] This embodiment provides a beneficiation method for medium and low grade bauxite. The only difference from Embodiment 1 is that in step (2), the ball milling time is 60 min, and the rest is the same as in Embodiment 1.

[0085] Example 16

[0086] This embodiment provides a beneficiation method for medium and low grade bauxite. The only difference from Embodiment 1 is that in step (2), the mill speed is 600 r / min, and the rest are the same as in Embodiment 1.

[0087] Example 17

[0088] This embodiment provides a beneficiation method for medium and low grade bauxite. The only difference from Embodiment 1 is that in step (2), the mill speed is 5 r / min, and the rest are the same as in Embodiment 1.

[0089] Example 18

[0090] This embodiment provides a beneficiation method for medium and low grade bauxite. The only difference from Embodiment 1 is that in step (2), the medium filling rate is 40%, and the rest are the same as in Embodiment 1.

[0091] Example 19

[0092] This embodiment provides a beneficiation method for medium and low grade bauxite. The only difference from Embodiment 1 is that in step (2), the medium filling rate is 20%, and the rest are the same as in Embodiment 1.

[0093] Example 20

[0094] This embodiment provides a beneficiation method for medium and low grade bauxite. The only difference from Embodiment 1 is that in step (2), the medium filling rate is 60%, and the rest are the same as in Embodiment 1.

[0095] Example 21

[0096] This embodiment provides a beneficiation method for medium and low grade bauxite. The only difference from Embodiment 1 is that in step (2), the mill filling rate is 70%, and the rest are the same as in Embodiment 1.

[0097] Example 22

[0098] This embodiment provides a beneficiation method for medium and low grade bauxite. The only difference from Embodiment 1 is that in step (2), the mill filling rate is 30%, and the rest are the same as in Embodiment 1.

[0099] Example 23

[0100] This embodiment provides a beneficiation method for medium and low grade bauxite. The only difference from Embodiment 1 is that in step (2), the bauxite particles are ball-milled to obtain a grinding product. The mass fraction of particles with a particle size between 74 and 300 μm in the grinding product is 40%, and the rest are the same as in Embodiment 1.

[0101] Example 24

[0102] This embodiment provides a beneficiation method for medium and low grade bauxite. The only difference from Embodiment 1 is that in step (2), the bauxite particles are ball-milled to obtain a grinding product. The mass fraction of particles with a particle size between 74 and 300 μm in the grinding product is 0%, and the rest are the same as in Embodiment 1.

[0103] Comparative Example 1

[0104] This comparative example provides a beneficiation method for medium- and low-grade bauxite. The only difference from Example 1 is that the bauxite heating, heat preservation, and rapid cooling steps are omitted, and the crushing, grinding, and classification steps are performed directly. All other steps are the same as in Example 1.

[0105] Comparative Example 2

[0106] This comparative example provides a beneficiation method for medium- and low-grade bauxite. The only difference from Example 1 is that the rapid cooling step after heating the bauxite is omitted, and it is allowed to cool naturally. All other aspects are the same as in Example 1.

[0107] Comparative Example 3

[0108] This comparative example provides a beneficiation method for medium- and low-grade bauxite. The only difference from Example 1 is that in step (2), the mass fraction of bauxite particles with a particle size between 0.5 and 2 cm is 10%, while the rest are the same as in Example 1.

[0109] Performance testing

[0110] Inductively coupled plasma atomic emission spectrometry (ICP-OES) was used to test the raw gibbsite bauxite, bauxite concentrate, tailings, and calcium silicate tailings in the above examples and comparative examples. The mass content of SiO2 and Al2O3 in each sample was determined, and the aluminum-silicon ratio (A / S) of each sample was calculated. The aluminum-silicon ratio = mass content of Al2O3 / mass content of SiO2. Subsequently, the aluminum recovery rate of the concentrate was calculated. The aluminum recovery rate of the concentrate = total mass of Al2O3 in the bauxite concentrate / total mass of Al2O3 in the raw bauxite.

[0111] The sodium aluminate solutions provided in the above examples and comparative examples were tested using ICP-OES to determine the Al2O3 concentration in the sodium aluminate solutions and to calculate the alumina dissolution rate. The alumina dissolution rate is calculated as: total mass of Al2O3 in the sodium aluminate solution / total mass of Al2O3 in the bauxite concentrate. The test results are shown in Table 1.

[0112] Table 1

[0113]

[0114]

[0115]

[0116] As shown in Table 1, the aluminum-silicon ratio of the bauxite concentrates obtained in Examples 1-24 is greater than 4.5, the aluminum-silicon ratio of the tailings is less than 1.6, and the aluminum recovery rate of the concentrate is greater than 80%.

[0117] A comparison between Example 1 and Comparative Example 1 shows that Comparative Example 1 did not involve heating, heat preservation, or rapid cooling of the bauxite. As a result, the degree of dissociation between the harder monohydrate gibbsite phase and the softer silica-rich phase was insufficient during the subsequent grinding process, leading to poor separation and making it difficult to separate the two phases through grinding.

[0118] The comparison between Example 1 and Comparative Example 2 shows that Comparative Example 2 did not use rapid cooling treatment, and the activation of the grain boundaries between the silicon-rich phase and the aluminum-rich phase was insufficient, resulting in a low aluminum-silicon ratio and low recovery rate in the obtained concentrate.

[0119] The comparison between Example 1 and Comparative Example 3 shows that Comparative Example 3 requires control over the particle size range of bauxite crushing; otherwise, it will lead to an excess of fine-grained silica-rich phase, resulting in mud formation and adhesion, which will affect the separation effect of silica-rich and alumina-rich phases.

[0120] In summary, this invention provides a beneficiation method for medium- and low-grade bauxite and its application. The beneficiation method can not only obtain concentrates with a high aluminum-silicon ratio, i.e., high-grade concentrates, but also has a high aluminum recovery rate. The method is simple, has strong applicability, and can further reduce energy consumption, alkali consumption, and red mud production during the alumina leaching process, thus having broad application prospects.

[0121] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A beneficiation method for medium- and low-grade bauxite, characterized in that, The mineral processing method includes the following steps: (1) The medium and low grade bauxite is heated, kept warm and rapidly cooled in sequence, and then the solid and liquid are separated to obtain activated medium and low grade bauxite. (2) The activated low-grade bauxite is crushed, ground and classified in sequence to obtain bauxite concentrate and tailings.

2. The mineral processing method according to claim 1, characterized in that, The heating rate in step (1) is 5 to 30 °C / min, preferably 10 to 20 °C / min.

3. The mineral processing method according to claim 1 or 2, characterized in that, The temperature for heat preservation in step (1) is 200-800℃, preferably 300-500℃; Preferably, the heat preservation time is 0.5 to 5 hours, and more preferably 1 to 3 hours.

4. The mineral processing method according to any one of claims 1-3, characterized in that, The cooling rate of the rapid cooling in step (1) is 50-300℃ / s, preferably 100-150℃ / s; Preferably, the rapid cooling method includes air cooling and / or liquid cooling, with liquid cooling being more preferred; Preferably, the liquid used for cooling includes water or a fluorinated liquid, with water being the preferred choice.

5. The mineral processing method according to any one of claims 1-4, characterized in that, Based on the total mass of the crushed product obtained in step (2), the mass fraction of particles with a particle size between 0.5 and 2 cm in the crushed product is 20% to 100%, preferably 30% to 90%.

6. The mineral processing method according to any one of claims 1-5, characterized in that, Based on the total mass of the grinding product obtained in step (2), the mass fraction of particles with a particle size between 74 and 300 μm in the grinding product is 0 to 40%, preferably 10 to 30%. Preferably, the grinding method in step (2) includes dry grinding or wet grinding; Preferably, the grinding method includes any one or a combination of at least two of ball milling, rod milling, pebble milling or autogenous milling, with ball milling being the preferred method; Preferably, the grinding time is 1 to 60 minutes, more preferably 5 to 30 minutes; Preferably, the mill speed for grinding is 5-600 r / min, more preferably 50-300 r / min; Preferably, the grinding media filling rate is 20-60%, more preferably 30-50%; Preferably, the mill filling rate of the grinding mill is 30-70%, more preferably 40-60%. 。 7. The mineral processing method according to any one of claims 1-6, characterized in that, The grading in step (2) includes grading particles with a particle size greater than or equal to 74 μm as concentrate and grading particles with a particle size less than 74 μm as tailings; Preferably, the grading method includes dry grading or wet grading; Preferably, the grading method includes any one or a combination of at least two of the following: screening, air grading, hydrocyclone grading, or chute grading, with screening being the preferred method.

8. The mineral processing method according to any one of claims 1-7, characterized in that, The alumina-silicon ratio of the bauxite concentrate is ≥4.0; Preferably, the aluminum-silicon ratio of the tailings is <1.

5.

9. A bauxite concentrate, characterized in that, The bauxite concentrate is prepared by the beneficiation method according to any one of claims 1-8.

10. An application of the bauxite concentrate as described in claim 9, characterized in that, The bauxite concentrate is used in the Bayer process for the synthesis of alumina.

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