Method for low-grade bauxite mineral phase separation and enrichment and co-production of ceramic proppant

Abstract

The present application relates to a kind of low-grade bauxite ore phase separation enrichment and parallel production ceramsite proppant method, the method comprises the following steps: bauxite is sequentially crushed, first grinding and grading, respectively obtain tailings, middlings and first concentrate;The first concentrate is classified after second grinding, and tailings, middlings and second concentrate are obtained, and the tailings and middlings obtained after the first grinding and the second grinding are respectively combined, to obtain combined tailings and combined middlings;Mix calcium source, lye and the combined middlings, to obtain mixed slurry;The mixed slurry is hydrothermally reacted, and second concentrate and calcium-containing tailings are obtained after separation;Mix water, the combined tailings and the calcium-containing tailings, sequentially granulating, drying and calcining, to obtain ceramsite proppant.The obtained middlings can be converted into concentrate after reaction, and the obtained concentrate is high in grade and high in recovery rate, and tailings can be used to prepare ceramsite proppant, to realize the full-component utilization of low-grade bauxite.

Description

Technical Field

[0001] This invention belongs to the technical fields of bauxite beneficiation, resource utilization of industrial solid waste and new ceramsite materials, and relates to a method for the phase separation and enrichment of low-grade bauxite and the co-production of ceramsite proppant. Background Technology

[0002] Bauxite resources are mainly monohydrate gibbsite-type bauxite, characterized by high aluminum and high silicon content, with the vast majority being medium- to low-grade bauxite with an aluminum-to-silicon 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 bauxite resources.

[0003] CN102755925A discloses a sorting method suitable for medium and low grade bauxite, which can process raw ore with an aluminum-silicon ratio of 4 or higher; CN101439317A and CN102806146A both disclose a pre-desiliconization method for bauxite beneficiation. This method has a relatively simple process, but it also has the problem of difficult utilization of tailings, and the raw ore that can be processed has an aluminum-silicon ratio of 3.5 or higher.

[0004] CN102294304A discloses a method for bauxite flotation, which involves concentrating a finely ground slurry or a low-concentration flotation slurry, followed by flotation. However, this patent can only process raw ore with an aluminum-silicon ratio (A / S) as low as 4. 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 μm, a process with extremely high energy consumption, and the resulting concentrate has an A / S ratio not exceeding 4, while the tailings have an A / S ratio as high as 1.7.

[0005] With the rapid development of the alumina industry, the grade of bauxite ore being processed is decreasing, from A / S > 5 in the early days to below 3.5. This grade is expected to continue to decline in the coming years. Therefore, flotation desilication of low A / S ratio bauxite is becoming increasingly difficult, resulting in worse performance indicators and higher production costs.

[0006] Furthermore, existing bauxite desilication methods rarely address the issue of tailings treatment. Kaolin is a major component of bauxite tailings and an important raw material for ceramsite preparation.

[0007] Therefore, it is of great significance to develop new methods for the separation and enrichment of low-grade bauxite and the co-production of ceramsite. Summary of the Invention

[0008] To solve the above-mentioned technical problems, the present invention provides a method for phase separation and enrichment of low-grade bauxite and co-production of ceramsite proppant. The obtained middlings can be converted into concentrate after reaction. The obtained concentrate has high grade and high recovery rate. At the same time, the tailings can be used to prepare ceramsite proppant, realizing the full utilization of low-grade bauxite components.

[0009] To achieve the above-mentioned technical effects, the present invention adopts the following technical solution:

[0010] This invention provides a method for the phase separation, enrichment, and co-production of ceramsite proppant in low-grade bauxite, the method comprising the following steps:

[0011] (1) The bauxite is crushed, first-stage milled and classified in sequence to obtain tailings, middlings and first concentrate respectively;

[0012] (2) After the first concentrate in step (1) is subjected to a second grinding and classified, tailings, middlings and second concentrate are obtained. The tailings and middlings obtained after the first grinding and the second grinding are combined to obtain combined tailings and combined middlings.

[0013] (3) Mix the calcium source, alkali solution and the combined middlings described in step (2) to obtain a mixed slurry;

[0014] (4) The mixture slurry described in step (3) is subjected to hydrothermal reaction, and after separation, a second concentrate and calcium-containing tailings are obtained;

[0015] (5) Mix water, the combined tailings from step (2) and the calcium-containing tailings from step (4), and granulate, dry and calcinate them in sequence to obtain ceramsite proppant.

[0016] The method described in this invention involves first grinding and classifying medium- and low-grade bauxite particles to obtain a first concentrate, middlings, and tailings. Then, the first concentrate is subjected to several second grinding processes until the alumina-silicon ratio (A / S) of the concentrate is ≥5.5. The combination of the first and second grinding processes yields a second concentrate with an alumina-silicon ratio ≥5.5. Finally, the middlings and tailings obtained from each grinding process are combined to obtain combined middlings and combined tailings.

[0017] The method described in this invention involves mixing middlings ore with calcium-rich raw materials, primarily composed of calcium oxide, in a specific ratio, then adding the mixture to an alkaline solution. A selective directional reaction is then achieved through hydrothermal reaction, transforming the silicon-containing phase in the bauxite into a lower-density calcium-containing tailings. The density of the calcium-containing tailings, the product of this directional transformation, is significantly lower than that of the diaspore phase in the middlings. Furthermore, by controlling specific hydrothermal reaction conditions, there is no obvious mutual encapsulation between the calcium-containing tailings and the diaspore. Therefore, the density difference can be used to separate the silicon-containing product from the diaspore ore, resulting in a high-alumina-silicon ratio diaspore concentrate (second concentrate).

[0018] The combined tailings obtained by the method of the present invention have an aluminum-silicon ratio of ≤1.7 and the main component is kaolin, which is one of the main raw materials for calcining ceramsite. The calcium-containing tailings obtained by hydrothermal reaction can be transformed into a liquid phase during the calcination of ceramsite, thereby reducing the sintering temperature and providing a liquid phase environment for crystal growth. Therefore, after the combined tailings and calcium-containing tailings are mixed and granulated, ceramsite proppant can be calcined at a lower temperature, and the full utilization of medium and low grade bauxite can be achieved.

[0019] It is worth noting that the method is simple in process and low in cost, reduces the use of natural raw materials, saves resources, and "turns harm into benefit and waste into treasure".

[0020] As a preferred technical solution of the present invention, the bauxite particles are obtained after crushing in step (1).

[0021] Preferably, the mass percentage of bauxite particles with a diameter of 0.5 to 2 cm is 20% to 100%, for example, it can be 30%, 40%, 50%, 60%, 70%, 80% or 90%, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0022] It is worth noting that pre-crushing bauxite to a particle size range of 0.5~2cm helps with subsequent selective grinding. If it is ground directly, the silica-rich phase and the alumina-rich phase will be intertwined and difficult to separate, and the ball mill energy consumption will increase and the efficiency will decrease.

[0023] It is worth noting that this invention is based on the differences in particle size, dispersal pattern, and hardness between silicon-bearing and aluminum-bearing minerals in low-grade bauxite. By grinding and classifying medium- and low-grade bauxite particles, a first concentrate, middlings, and tailings particles are obtained. The selective grinding and classification method is simple yet efficient, significantly reducing the feed amount for subsequent hydrothermal reactions and effectively lowering energy consumption and raw material requirements. The tailings obtained through the first and second grinding processes and classification have a low aluminum-silicon ratio; although they cannot be used as aluminum extraction resources, they are excellent raw materials for ceramsite. Therefore, the first and second grinding processes are one of the key points in this invention for achieving full utilization of resource components.

[0024] Preferably, step (1) the first grinding includes dry grinding or wet grinding.

[0025] Preferably, in step (1), the grinding media filling rate of the first grinding process is 5% to 60%, for example, it can be 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50% or 55%, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0026] Preferably, the grinding time in step (1) is 1 to 30 minutes, for example, it can be 2 minutes, 5 minutes, 7 minutes, 10 minutes, 12 minutes, 15 minutes, 17 minutes, 20 minutes, 22 minutes, 25 minutes, 27 minutes or 29 minutes, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0027] It is worth noting that if the first grinding time is too short, the minerals will not be separated sufficiently; if the first grinding time is too long, the mineral particles will be too small, making separation difficult and resulting in higher energy consumption.

[0028] Preferably, the mill speed of the first grinding mill in step (1) is 5~300 r / min, for example, it can be 10 r / min, 30 r / min, 50 r / min, 70 r / min, 100 r / min, 120 r / min, 150 r / min, 170 r / min, 200 r / min, 220 r / min, 250 r / min, 270 r / min or 290 r / min, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0029] Preferably, in step (1), the mill filling rate of the first grinding mill is 20% to 50%, for example, it can be 22%, 25%, 27%, 30%, 32%, 35%, 37%, 40%, 42%, 45%, 47% or 49%, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0030] In this invention, the selection of grinding media filling rate, mill speed and mill filling rate are the result of comprehensive consideration of cost and separation efficiency. Too high or too low a ratio will affect the effect of the first grinding.

[0031] Preferably, the grading in step (1) includes dry grading or wet grading.

[0032] In this invention, the grading method includes any one or a combination of at least two of the following: wind grading, hydrocyclone grading, chute grading, or vibrating screen grading.

[0033] Preferably, the tailings in step (1) have a particle size of <150μm, for example, 140μm, 130μm, 120μm, 110μm, 100μm or 90μm, but are not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0034] Preferably, the particle size of the middlings in step (1) is 150~250μm, for example, it can be 160μm, 170μm, 180μm, 190μm, 200μm, 210μm, 220μm, 230μm or 240μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0035] Preferably, in step (1), the particle size of the first concentrate is >250μm, for example, it can be 260μm, 270μm, 280μm, 290μm, 300μm or 310μm, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0036] As a preferred technical solution of the present invention, step (2) the second grinding includes dry grinding or wet grinding.

[0037] Preferably, the number of grinding cycles in step (2) is 1 to 10 times, for example, 2, 3, 4, 5, 6, 7, 8 or 9 times, but not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 2 to 5 times.

[0038] In this invention, the number of repetitions of the second grinding helps to improve the separation efficiency of minerals. If the number of repetitions of the second grinding is too low, the difference in grade between tailings, middlings and concentrate is too small. If the number of repetitions of the second grinding is too high, the energy consumption is too high and the process is too long.

[0039] Preferably, in step (2), the grinding media filling rate of the second grinding process is 10% to 50%, for example, it can be 15%, 20%, 25%, 30%, 35%, 40%, 45% or 49%, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0040] Preferably, the second grinding time in step (2) is 5 to 20 minutes, for example, it can be 7 minutes, 10 minutes, 12 minutes, 14 minutes, 15 minutes, 16 minutes, 18 minutes or 19 minutes, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0041] Preferably, the mill speed of the second grinding in step (2) is 5~300 r / min, for example, it can be 10 r / min, 30 r / min, 50 r / min, 70 r / min, 100 r / min, 120 r / min, 150 r / min, 170 r / min, 200 r / min, 220 r / min, 250 r / min, 270 r / min or 290 r / min, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0042] Preferably, the mill filling rate of the second grinding mill in step (2) is 20% to 50%, for example, it can be 22%, 25%, 27%, 30%, 32%, 35%, 37%, 40%, 42%, 45%, 47% or 49%, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0043] Preferably, in step (2), the aluminum-silicon ratio of the second concentrate is ≥5.5, for example, it can be 5.6, 5.7, 5.8, 5.9, 6.0, 6.2 or 6.5, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably ≥6.0.

[0044] As a preferred technical solution of the present invention, the calcium source in step (3) includes industrial raw materials and / or waste residue containing calcium oxide, preferably any one or a combination of at least two of calcium hydroxide, lime or phosphogypsum.

[0045] In this invention, the calcium source can be a single industrial raw material or waste residue with calcium oxide as the main component, or it can be a mixture of at least two industrial raw materials or waste residues with calcium oxide as the main component. For example, it can be any one of calcium hydroxide, lime, or phosphogypsum. Typical but non-limiting combinations include combinations of calcium hydroxide and lime, combinations of calcium hydroxide and phosphogypsum, combinations of lime and phosphogypsum, combinations of calcium hydroxide, lime, and phosphogypsum, etc.

[0046] Preferably, the alkaline solution in step (3) includes NaOH solution and / or KOH solution.

[0047] Preferably, the concentration of the alkaline solution in step (3) is 0.05-2.5 mol / L, for example, it can be 0.07 mol / L, 0.1 mol / L, 0.3 mol / L, 0.5 mol / L, 1 mol / L, 1.3 mol / L, 1.5 mol / L, 1.8 mol / L, 2 mol / L, 2.2 mol / L or 2.4 mol / L, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 0.1-1 mol / L.

[0048] It is worth noting that controlling the concentration of the alkaline solution within the range of 0.05-2.5 mol / L can better promote the dissolution reaction. When the concentration of the alkaline solution is too low, the subsequent reaction is difficult to complete; when the concentration of the alkaline solution is too high, other products will be generated during the reaction, reducing the aluminum recovery rate.

[0049] As a preferred technical solution of the present invention, the molar ratio of CaO in the calcium source and SiO2 in the combined middlings in step (3) is (0.4-1.5):1, for example, it can be 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 13:1 or 1.4:1, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably (0.8-1.2):1;

[0050] It is worth noting that by controlling the molar ratio range of CaO in the calcium source and SiO2 in the combined middlings, the silicon component can be utilized more effectively. When the molar ratio of CaO to SiO2 is too low or too high, it will affect the reaction effect of the silicon-rich mineral phase.

[0051] Preferably, the ratio of the total mass of the calcium source and the combined intermediate minerals to the volume of the alkali solution in step (3) is 1:(2.5-40)g / mL. For example, it can be 1:3g / mL, 1:5g / mL, 1:10g / mL, 1:15g / mL, 1:20g / mL, 1:25g / mL, 1:30g / mL, 1:35g / mL or 1:38g / mL, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable. Preferably, it is 1:(5-20)g / mL.

[0052] It is worth noting that the total mass ratio of calcium source and combined intermediate minerals to the volume of alkali solution is a key factor in selective leaching. When the mass-to-volume ratio is too high, the mixture of the aggregate and alkali solution is difficult to mix evenly, and the volume of the reaction products will expand rapidly, making the reaction difficult to proceed. When the mass-to-volume ratio is too low, it will cause unnecessary energy consumption.

[0053] As a preferred technical solution of the present invention, the temperature of the hydrothermal reaction in step (4) is 100-250℃, for example, it can be 110℃, 120℃, 140℃, 150℃, 160℃, 180℃, 200℃, 220℃, 230℃ or 240℃, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 140-220℃.

[0054] Preferably, the hydrothermal reaction time in step (4) is 1-30h, for example, it can be 3h, 5h, 8h, 10h, 12h, 15h, 18h, 20h, 23h, 25h, 27h or 29h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 2-10h.

[0055] It is worth noting that when the hydrothermal reaction temperature is too low, the reaction kinetics are insufficient, reducing the conversion rate of silicon dioxide; when the hydrothermal reaction temperature is too high, additional energy consumption is increased, raising costs. When the hydrothermal reaction time is too short, the reaction is incomplete, and much of the raw material cannot be converted, resulting in waste; when the hydrothermal reaction time is too long, energy consumption increases, raising mineral processing costs. Therefore, this invention controls the temperature and time of the hydrothermal reaction within the aforementioned ranges, which can improve the utilization rate of raw materials, efficiently achieve the directional conversion of silicon in bauxite, and simultaneously reduce resource waste and energy consumption.

[0056] As a preferred technical solution of the present invention, the separation in step (4) includes: performing solid-solid separation on the hydrothermal reaction products to obtain a second concentrate and a slurry, and then performing solid-liquid separation on the slurry to obtain calcium-containing tailings.

[0057] It is worth noting that the tailings produced by the method are rich in kaolin, which is one of the important raw materials for the preparation of ceramsite. Meanwhile, the calcium-containing tailings produced by the hydrothermal method can be added to the ceramsite green body to regulate the amount of liquid phase during ceramsite sintering, greatly improving the strength of the ceramsite product. Therefore, this invention proposes to prepare ceramsite by mixing the combined tailings and calcium-containing tailings, achieving comprehensive utilization of both.

[0058] Preferably, the solid-solid separation method includes sedimentation separation or centrifugal separation.

[0059] In this invention, the solid-solid separation equipment includes any one or a combination of at least two of the following: settling tank, hydrocyclone, sluice, or centrifuge. In addition to the above-mentioned equipment, other equipment that uses density difference for separation can also be used for the separation of bauxite concentrate and slurry.

[0060] It is worth noting that the solid-solid separation is based on the density difference between the second concentrate and the calcium-containing tailings. The material with higher density is the second concentrate, and the material with lower density is the calcium-containing tailings.

[0061] It should be noted that the solid-liquid separation is carried out using conventional methods in the art, as long as the calcium-containing tailings can be separated from the solution, and no special limitations are imposed.

[0062] As a preferred technical solution of the present invention, the mass ratio of the total mass of the combined tailings and calcium-containing tailings to the mass of water in step (5) is 1:(0.06-0.4), for example, it can be 1:0.08, 1:0.1, 1:0.15, 1:0.2, 1:0.25, 1:0.3 or 1:0.35, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0063] It is worth noting that the present invention requires strict control of the amount of water added during the granulation process to ensure the sphericity and particle size of the final ceramsite proppant. The optimal technical effect can be achieved by controlling the moisture content in the reaction mixture after adding water during the granulation process.

[0064] Preferably, the mixing time in step (5) is 1 to 30 minutes, for example, it can be 5 minutes, 7 minutes, 10 minutes, 12 minutes, 15 minutes, 17 minutes, 20 minutes, 22 minutes, 25 minutes, 27 minutes or 29 minutes, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0065] Preferably, the mixing in step (5) includes one-step mixing or multi-step mixing, preferably multi-step mixing.

[0066] Preferably, the stepwise mixing includes: first adding water at a mass fraction of 5wt% to 15wt% of the combined tailings and calcium-containing tailings and mixing with the combined tailings and calcium-containing tailings for 0.5 to 20 minutes, and then adding the remaining water and mixing for 0.5 to 20 minutes.

[0067] Preferably, the granulation time in step (5) is 1 to 40 minutes, for example, it can be 5 minutes, 7 minutes, 10 minutes, 12 minutes, 15 minutes, 17 minutes, 20 minutes, 22 minutes, 25 minutes, 27 minutes, 30 minutes, 32 minutes, 35 minutes, 37 minutes or 39 minutes, preferably 5 to 30 minutes.

[0068] In this invention, the mixing of water and mixed powder can be carried out in a granulation device, that is, water and mixed powder are mixed in the granulation device first, and then granulation is carried out.

[0069] Preferably, the granulation equipment in step (5) includes any one of an inclined high-intensity mixer, a sugar-coating pan granulator, or a disc granulator, with an inclined high-intensity mixer being the preferred option.

[0070] Preferably, the drum rotation speed of the inclined high-intensity mixer is 10~1500 r / min, for example, it can be 20 r / min, 50 r / min, 60 r / min, 100 r / min, 50 r / min, 60 r / min, 100 r / min, 200 r / min, 300 r / min, 500 r / min, 700 r / min, 1000 r / min, 1200 r / min or 1400 r / min, etc., preferably 20~80 r / min.

[0071] Preferably, the rotor speed of the inclined high-power mixer is 300~6000 r / min, for example, it can be 400 r / min, 500 r / min, 700 r / min, 1000 r / min, 1500 r / min, 2000 r / min, 2500 r / min, 3000 r / min, 3500 r / min, 4000 r / min, 4500 r / min, 5000 r / min or 5500 r / min, etc., preferably 500~4000 r / min.

[0072] As a preferred technical solution of the present invention, the heating rate of calcination in step (5) is 1~15℃ / min, such as 3℃ / min, 5℃ / min, 7℃ / min, 9℃ / min, 10℃ / min, 12℃ / min, 13℃ / min or 14℃ / min, etc., but not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 5~10℃ / min.

[0073] Preferably, the heating endpoint of the calcination in step (5) is 1000~1700℃, such as 1050℃, 1100℃, 1150℃, 1200℃, 1250℃, 1300℃, 1350℃, 1400℃, 1450℃, 1500℃, 1550℃, 1600℃, 1650℃ or 1690℃, etc., but not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 1200~1500℃.

[0074] Preferably, the calcination holding time in step (5) is 0.1~12h, for example 0.5h, 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h or 11h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 0.5~8h.

[0075] Preferably, step (5) includes furnace cooling after calcination.

[0076] In this invention, the calcination equipment includes any one of an electric furnace, a gas furnace, or a pulverized coal heating furnace.

[0077] As a preferred technical solution of the present invention, the method includes the following steps:

[0078] (1) The bauxite is crushed, first-stage milled and classified in sequence to obtain tailings, middlings and first concentrate respectively;

[0079] The crushing process yields bauxite particles; the mass percentage of bauxite particles with a diameter of 0.5~2cm is 20%~100%.

[0080] The grinding media filling rate of the first grinding mill is 5%~60%, the time is 1~30 min, the mill speed is 5~300 r / min, and the mill filling rate is 20%~50%.

[0081] The tailings have a particle size <150μm; the middlings have a particle size of 150~250μm; and the first concentrate has a particle size >250μm.

[0082] (2) After the first concentrate in step (1) is subjected to a second grinding and classified, tailings, middlings and second concentrate are obtained. The tailings and middlings obtained after the first grinding and the second grinding are combined to obtain combined tailings and combined middlings.

[0083] The second grinding process involves 1 to 10 grinding cycles, with a grinding media filling rate of 10% to 50%, a grinding time of 5 to 20 minutes, a mill speed of 5 to 300 r / min, and a mill filling rate of 20% to 50%.

[0084] The aluminum-silicon ratio of the second concentrate is ≥5.5;

[0085] (3) Mix the calcium source, alkali solution and the combined middlings described in step (2) to obtain a mixed slurry;

[0086] The calcium source includes industrial raw materials and / or waste containing calcium oxide; the alkaline solution includes NaOH solution and / or KOH solution; the concentration of the alkaline solution is 0.05-2.5 mol / L;

[0087] The molar ratio of CaO in the calcium source to SiO2 in the combined middlings is (0.4-1.5):1; the ratio of the total mass of the calcium source and the combined middlings to the volume of the alkali solution is 1:(2.5-40) g / mL.

[0088] (4) The mixture slurry described in step (3) is subjected to hydrothermal reaction at a temperature of 100-250℃ for 1-30h. The hydrothermal reaction products are separated into solid and solid to obtain the second concentrate and slurry. Then the slurry is separated into solid and liquid to obtain calcium-containing tailings.

[0089] (5) Mix water, the combined tailings from step (2) and the calcium-containing tailings from step (4), and granulate, dry and calcinate them in sequence to obtain ceramsite proppant;

[0090] The total mass ratio of the combined tailings and calcium-containing tailings to water is 1:(0.06-0.4); the mixing time is 1~30 min;

[0091] The granulation time is 1~40 min;

[0092] The calcination heating rate is 1~15℃ / min, the heating endpoint is 1000~1700℃, and the holding time is 0.1~12h.

[0093] Compared with the prior art, the present invention has the following beneficial effects:

[0094] (1) The method described in this invention has very low requirements for the aluminum-silicon ratio of the raw ore. The aluminum-silicon ratio of the raw ore with an aluminum-silicon ratio of less than 3.0 can reach more than 5.5 after aluminum-silicon separation, which fully meets the technical requirements of my country's Bayer process alumina industry production.

[0095] (2) The method described in this invention can not only obtain bauxite concentrate through selective grinding, but also reduce the amount of subsequent hydrothermal treatment and reduce the process cost. After the aluminum-rich phase and silicon-rich phase are separated during the reaction process of reusing the middlings, the original ore in which diaspore and kaolinite are inter-embedded is opened up, the aluminum-rich phase is activated in situ, and the surface energy is increased, which can reduce the energy consumption during the subsequent Bayer process leaching. Then, the tailings and calcium-containing tailings generated by mineral processing are combined and calcined to produce ceramsite proppant, realizing 100% utilization of raw materials.

[0096] (3) The method described in this invention is simple, low-cost and reduces the use of natural raw materials, saving resources and turning harm into benefit and waste into treasure. Detailed Implementation

[0097] 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.

[0098] Unless otherwise specified in the following examples and comparative examples, the techniques or conditions described in the literature in this field, or in accordance with the product instructions, shall be followed. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels.

[0099] Example 1

[0100] This embodiment provides a method for the phase separation, enrichment, and co-production of ceramsite proppant in low-grade bauxite ore, the method comprising the following steps:

[0101] (1) Bauxite with an aluminum-silicon ratio of 2.5 is crushed, first-stage ground and classified in sequence to obtain tailings, middlings and first concentrate respectively;

[0102] The crushing process yields bauxite particles; the mass percentage of the bauxite particles with a diameter of 0.5~2cm is 80%.

[0103] The first grinding mill has a grinding media filling rate of 30%, a grinding time of 30 minutes, a mill speed of 150 r / min, and a mill filling rate of 35%.

[0104] The tailings have a particle size <150μm; the middlings have a particle size of 150~250μm; and the first concentrate has a particle size >250μm.

[0105] (2) After the first concentrate in step (1) is subjected to two second grinding processes, it is classified to obtain tailings, middlings and second concentrate. The tailings and middlings obtained after the first grinding and the second grinding are combined to obtain combined tailings and combined middlings.

[0106] The second grinding mill has a grinding media filling rate of 30%, a grinding time of 5 minutes, a mill speed of 150 r / min, and a mill filling rate of 35%.

[0107] (3) Mix calcium hydroxide, a 0.5 mol / L NaOH solution and the combined middlings described in step (2) to obtain a mixed slurry;

[0108] The molar ratio of CaO in the calcium hydroxide to SiO2 in the combined middlings is 1.0:1; the ratio of the total mass of the calcium hydroxide and the combined middlings to the volume of the NaOH solution is 1:5 g / mL.

[0109] (4) The mixture slurry described in step (3) is subjected to hydrothermal reaction at 180°C for 2 hours. The hydrothermal reaction product is separated into solid and solid by sedimentation. After washing, the second concentrate and slurry are obtained. The slurry is then separated into solid and liquid by filtration to obtain calcium-containing tailings.

[0110] (5) The combined tailings described in step (2) and the calcium-containing tailings described in step (4) are mixed and ball-milled for 10 minutes, then water is added and mixed for 4 minutes. After that, granulation, drying and calcination are carried out in sequence, and the ceramic proppant is obtained after cooling in the furnace.

[0111] The total mass ratio of the combined tailings and calcium-containing tailings to water is 1:0.25; the mixing time is 1~30 min; the mixing is a step-by-step mixing, first adding water accounting for 15wt% of the combined tailings and calcium-containing tailings and mixing with the combined tailings and calcium-containing tailings for 1 min, and then adding the remaining water to mix.

[0112] The granulation time is 30 minutes; the granulation equipment is an inclined high-intensity mixer, the drum speed of the inclined high-intensity mixer is 50 r / min, and the rotor speed is 4000 r / min;

[0113] The calcination heating rate is 5℃ / min, the heating endpoint is 1300℃, and the holding time is 2h.

[0114] Example 2

[0115] This embodiment provides a method for the phase separation, enrichment and co-production of ceramsite proppant in low-grade bauxite. Except for step (1), in which the mass percentage of bauxite particles with a diameter of 0.5~2cm is 40%, all other conditions are the same as in Example 1.

[0116] Example 3

[0117] This embodiment provides a method for the phase separation, enrichment and co-production of ceramsite proppant in low-grade bauxite. Except for the time of 10 min for the first grinding in step (1) and the second grinding in step (2), all other conditions are the same as in embodiment 1.

[0118] Example 4

[0119] This embodiment provides a method for the phase separation, enrichment and co-production of ceramsite proppant in low-grade bauxite. Except for step (2) which involves six cycles of the second grinding, all other conditions are the same as in Example 1.

[0120] Example 5

[0121] This embodiment provides a method for the phase separation, enrichment and co-production of ceramsite proppant in low-grade bauxite. Except for the molar ratio of CaO in the calcium hydroxide and SiO2 in the combined middlings in step (3) being 0.6:1, all other conditions are the same as in Example 1.

[0122] Example 6

[0123] This embodiment provides a method for the phase separation, enrichment and co-production of ceramsite proppant in low-grade bauxite. Except for the concentration of NaOH solution in step (3) being 0.15 mol / L, all other conditions are the same as in Example 1.

[0124] Example 7

[0125] This embodiment provides a method for the phase separation, enrichment and co-production of ceramsite proppant in low-grade bauxite. Except for the ratio of the total mass of calcium hydroxide and the combined middlings to the volume of NaOH solution in step (3) being 1:10 g / mL, all other conditions are the same as in Example 1.

[0126] Example 8

[0127] This embodiment provides a method for the phase separation, enrichment and co-production of ceramsite proppant in low-grade bauxite. Except for the hydrothermal reaction temperature of 150°C in step (4), all other conditions are the same as in Example 1.

[0128] Example 9

[0129] This embodiment provides a method for the phase separation, enrichment and co-production of ceramsite proppant in low-grade bauxite. Except for the hydrothermal reaction time of 4 hours in step (4), all other conditions are the same as in Example 1.

[0130] Example 10

[0131] This embodiment provides a method for the phase separation, enrichment and co-production of ceramsite proppant from low-grade bauxite. Except for the aluminum-silicon ratio of the bauxite in step (1) being 3.4, all other conditions are the same as in Example 1.

[0132] Example 11

[0133] This embodiment provides a method for the phase separation, enrichment and co-production of ceramsite proppant in low-grade bauxite. Except for the mill speed of 50 r / min in the first grinding step (1) and the second grinding step (2), all other conditions are the same as in Embodiment 1.

[0134] Example 12

[0135] This embodiment provides a method for the phase separation, enrichment and co-production of ceramsite proppant in low-grade bauxite. Except that the grinding media filling rate in the first grinding step (1) and the second grinding step (2) is 20%, all other conditions are the same as in Embodiment 1.

[0136] Example 13

[0137] This embodiment provides a method for the phase separation, enrichment and co-production of ceramsite proppant in low-grade bauxite. Except that the mill filling rate in the first grinding step (1) and the second grinding step (2) is 30%, all other conditions are the same as in Embodiment 1.

[0138] Example 14

[0139] This embodiment provides a method for the phase separation, enrichment and co-production of ceramsite proppant in low-grade bauxite. Except for the mass ratio of the total mass of the combined tailings and calcium-containing tailings to water of 1:0.1 described in step (5), all other conditions are the same as in embodiment 1.

[0140] Example 15

[0141] This embodiment provides a method for the phase separation, enrichment and co-production of ceramsite proppant in low-grade bauxite. Except for the granulation time of 40 min in step (5), all other conditions are the same as in Example 1.

[0142] Example 16

[0143] This embodiment provides a method for the phase separation, enrichment and co-production of ceramsite proppant in low-grade bauxite. Except for the barrel speed of the inclined high-intensity mixer in step (5) being 30 r / min, all other conditions are the same as in embodiment 1.

[0144] Example 17

[0145] This embodiment provides a method for the phase separation, enrichment and co-production of ceramsite proppant from low-grade bauxite. Except for the calcination temperature endpoint of 1500℃ in step (5), all other conditions are the same as in Example 1.

[0146] Example 18

[0147] This embodiment provides a method for the phase separation, enrichment and co-production of ceramsite proppant from low-grade bauxite. Except for the heating rate of calcination in step (5) being 10℃ / min, all other conditions are the same as in Example 1.

[0148] Example 19

[0149] This embodiment provides a method for the phase separation, enrichment and co-production of ceramsite proppant from low-grade bauxite. Except for the calcination holding time of 6 hours in step (5), all other conditions are the same as in embodiment 1.

[0150] Example 20

[0151] This embodiment provides a method for the phase separation, enrichment and co-production of ceramsite proppant in low-grade bauxite. Except for step (1), in which the mass percentage of bauxite particles with a diameter of 150~250μm is 80%, all other conditions are the same as in Example 1.

[0152] Example 21

[0153] This embodiment provides a method for the phase separation, enrichment and co-production of ceramsite proppant in low-grade bauxite. Except for the second grinding time of 3 minutes in step (2), all other conditions are the same as in embodiment 1.

[0154] Example 22

[0155] This embodiment provides a method for the phase separation, enrichment and co-production of ceramsite proppant in low-grade bauxite. Except for the mass ratio of the total mass of the combined tailings and calcium-containing tailings to water of 1:0.05 as described in step (5), all other conditions are the same as in embodiment 1.

[0156] Example 23

[0157] This embodiment provides a method for the phase separation, enrichment and co-production of ceramsite proppant in low-grade bauxite. Except for the mass ratio of the total mass of the combined tailings and calcium-containing tailings to water of 1:0.5 as described in step (5), all other conditions are the same as in embodiment 1.

[0158] Example 24

[0159] This embodiment provides a method for the phase separation, enrichment and co-production of ceramsite proppant from low-grade bauxite. Except for the calcination temperature endpoint of 800°C in step (5), all other conditions are the same as in Example 1.

[0160] Example 25

[0161] This embodiment provides a method for the phase separation, enrichment and co-production of ceramsite proppant from low-grade bauxite. Except for the calcination temperature endpoint of 2000℃ in step (5), all other conditions are the same as in Example 1.

[0162] Comparative Example 1

[0163] This comparative example provides a method for the phase separation, enrichment, and co-production of ceramsite proppant in low-grade bauxite. Except for adjusting steps (1) and (2) to direct ball milling to obtain mineral particles with a particle size of 150~250μm and then classifying them, all other conditions are the same as in Example 1.

[0164] Comparative Example 2

[0165] This comparative example provides a method for the phase separation, enrichment and co-production of ceramsite proppant in low-grade bauxite. Except for step (2), all other conditions are the same as in Example 1.

[0166] The contents of bauxite, concentrate, and tailings in the above examples and comparative examples were determined by inductively coupled plasma mass spectrometry (ICP-OES), and the aluminum-silicon ratio was calculated. The results are shown in Table 1. The performance of the ceramsite proppant products prepared in the above examples and comparative examples was tested, and the results are shown in Table 1.

[0167] Table 1

[0168]

[0169] As shown in Table 1:

[0170] (1) The method provided in Examples 1-19 of this invention, the low-grade bauxite phase separation and enrichment method, not only ensures the grade of the second concentrate but also has a high recovery rate. The method is simple to operate, highly applicable, and easy to promote. The aluminum-silicon ratio of the obtained second concentrate is greater than 5.5, preferably greater than 6, and the aluminum-silicon ratio of the tailings is less than 1.7. The recovery rate of the second concentrate is greater than 50%. The crushing rate of the obtained ceramsite proppant at 35 MPa is less than 10%, the acid solubility is less than 1.5%, and the bulk density is between 1.1 and 1.5 g·cm³. -3 Within this range, it exhibits superior resistance to breakage and acid corrosion.

[0171] (2) Comparison of Example 1 and Example 20 shows that when the particle size of the crushed bauxite is too small, the difference in particle size between the silicon-rich phase and the aluminum-rich phase is too small to be distinguished by screening, resulting in a decrease in concentrate recovery rate.

[0172] (3) A comparison of Example 1 and Example 21 shows that when the time for the first grinding and the second grinding is too short, the mineral separation is insufficient, resulting in the grade of the second concentrate not reaching 5.5 or higher;

[0173] (4) A comparison of Examples 1 and 22-23 shows that when the amount of water added during the preparation of the ceramsite proppant is too small, the green body is difficult to form, resulting in a decrease in the fracture resistance of the ceramsite proppant; when the amount of water added is too large, the green body is difficult to form, resulting in a decrease in the fracture resistance of the ceramsite proppant. In addition, the energy consumption during calcination increases sharply, leading to an increase in cost. A comparison of Examples 1 and 24-25 shows that when the calcination temperature of the ceramsite proppant is too low, the sintering strength is insufficient and the strength decreases, resulting in a decrease in the performance of the ceramsite proppant; when the calcination temperature of the ceramsite proppant is too high, the required energy consumption increases and the economy deteriorates.

[0174] (5) Comparison of Example 1 and Comparative Example 1 shows that if selective grinding is not used for pretreatment and ball milling is performed directly, the grade of the concentrate obtained is low and the recovery rate is also reduced, which also affects the performance of the ceramic proppant.

[0175] (6) Comparison of Example 1 and Comparative Example 2 shows that if a second grinding is not performed, a high-grade concentrate cannot be obtained, the utilization rate of the concentrate decreases, and the performance of the ceramic proppant is also affected.

[0176] 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 method for the phase separation, enrichment, and co-production of ceramsite proppant in low-grade bauxite, characterized in that, The method includes the following steps: (1) The bauxite is crushed, first-stage milled and classified in sequence to obtain tailings, middlings and first concentrate respectively; (2) After the first concentrate in step (1) is subjected to a second grinding and classified, tailings, middlings and second concentrate are obtained. The tailings and middlings obtained after the first grinding and the second grinding are combined to obtain combined tailings and combined middlings. (3) Mix the calcium source, alkali solution and the combined middlings described in step (2) to obtain a mixed slurry; (4) The mixture slurry described in step (3) is subjected to hydrothermal reaction, and after separation, a second concentrate and calcium-containing tailings are obtained; (5) Mix water, the combined tailings from step (2) and the calcium-containing tailings from step (4), and granulate, dry and calcinate them in sequence to obtain ceramsite proppant; Step (1) involves crushing the material to obtain bauxite particles; The mass percentage of bauxite particles with a diameter of 0.5-2 cm is 20%-100%. The tailings in step (1) have a particle size of <150μm; The particle size of the middlings in step (1) is 150~250μm; Step (1) The particle size of the first concentrate is >250μm; Step (2) The aluminum-silicon ratio of the second concentrate is ≥5.5; The alkaline solution in step (3) includes NaOH solution and / or KOH solution; The concentration of the alkaline solution in step (3) is 0.05-2.5 mol / L; In step (3), the molar ratio of CaO in the calcium source to SiO2 in the merged intermediate ore is (0.4-1.5):1; The ratio of the total mass of the calcium source and the combined intermediate ore to the volume of the alkali solution in step (3) is 1:(2.5-40)g / mL; The temperature of the hydrothermal reaction in step (4) is 100-250℃; The hydrothermal reaction time in step (4) is 1-30 hours.

2. The method according to claim 1, characterized in that, Step (1) The first grinding process includes dry grinding or wet grinding.

3. The method according to claim 1, characterized in that, Step (1) The grinding media filling rate of the first grinding mill is 5%~60%.

4. The method according to claim 1, characterized in that, Step (1) The first grinding time is 1~30 min.

5. The method according to claim 1, characterized in that, Step (1) The mill speed of the first grinding mill is 5~300r / min.

6. The method according to claim 1, characterized in that, Step (1) The mill filling rate of the first grinding mill is 20%~50%.

7. The method according to claim 1, characterized in that, The grading in step (1) includes dry grading or wet grading.

8. The method according to claim 1, characterized in that, Step (2) The second grinding process includes dry grinding or wet grinding.

9. The method according to claim 1, characterized in that, Step (2) The second grinding process is repeated 1 to 10 times.

10. The method according to claim 9, characterized in that, Step (2) The second grinding process is repeated 2 to 5 times.

11. The method according to claim 1, characterized in that, Step (2) The grinding media filling rate of the second grinding mill is 10%~50%.

12. The method according to claim 1, characterized in that, Step (2) The second grinding time is 5~20 min.

13. The method according to claim 1, characterized in that, Step (2) The mill speed of the second grinding mill is 5~300 r / min.

14. The method according to claim 1, characterized in that, Step (2) The mill filling rate of the second grinding mill is 20%~50%.

15. The method according to claim 1, characterized in that, Step (2) The aluminum-silicon ratio of the second concentrate is ≥6.

0.

16. The method according to claim 1, characterized in that, The calcium source in step (3) includes industrial raw materials and / or waste containing calcium oxide.

17. The method according to claim 1, characterized in that, The concentration of the alkaline solution in step (3) is 0.1-1 mol / L.

18. The method according to claim 1, characterized in that, In step (3), the molar ratio of CaO in the calcium source to SiO2 in the combined medium ore is (0.8-1.2):

1.

19. The method according to claim 1, characterized in that, In step (3), the ratio of the total mass of the calcium source and the combined intermediate minerals to the volume of the alkali solution is 1:(5-20)g / mL.

20. The method according to claim 1, characterized in that, The temperature of the hydrothermal reaction in step (4) is 140-220℃.

21. The method according to claim 1, characterized in that, The hydrothermal reaction time in step (4) is 2-10 hours.

22. The method according to claim 1, characterized in that, The separation in step (4) includes: solid-solid separation of the hydrothermal reaction products to obtain a second concentrate and slurry, and then solid-liquid separation of the slurry to obtain calcium-containing tailings.

23. The method according to claim 22, characterized in that, The solid-solid separation methods include sedimentation separation or centrifugal separation.

24. The method according to claim 1, characterized in that, The mass ratio of the combined tailings and calcium-containing tailings to water in step (5) is 1:(0.06-0.4).

25. The method according to claim 1, characterized in that, The mixing time in step (5) is 1 to 30 minutes.

26. The method according to claim 1, characterized in that, The mixing in step (5) includes one-step mixing or multi-step mixing.

27. The method according to claim 26, characterized in that, The mixing in step (5) is a step-by-step mixing.

28. The method according to claim 27, characterized in that, The stepwise mixing process includes: first adding water at a mass fraction of 5wt% to 15wt% of the combined tailings and calcium-containing tailings and mixing with the combined tailings and calcium-containing tailings for 0.5 to 20 minutes, and then adding the remaining water and mixing for 0.5 to 20 minutes.

29. The method according to claim 1, characterized in that, The granulation time in step (5) is 1~40 min.

30. The method according to claim 29, characterized in that, The granulation time in step (5) is 5~30 min.

31. The method according to claim 1, characterized in that, The granulation equipment mentioned in step (5) includes any one of an inclined high-intensity mixer, a sugar-coating pan granulator, or a disc granulator.

32. The method according to claim 31, characterized in that, The granulation equipment in step (5) is an inclined high-intensity mixer.

33. The method according to claim 32, characterized in that, The drum rotation speed of the inclined high-intensity mixer is 10~1500 r / min.

34. The method according to claim 33, characterized in that, The drum rotation speed of the inclined high-intensity mixer is 20~80 r / min.

35. The method according to claim 32, characterized in that, The rotor speed of the inclined high-intensity mixer is 300~6000 r / min.

36. The method according to claim 35, characterized in that, The rotor speed of the inclined high-intensity mixer is 500~4000 r / min.

37. The method according to claim 1, characterized in that, The heating rate of calcination in step (5) is 1~15℃ / min.

38. The method according to claim 37, characterized in that, The heating rate of calcination in step (5) is 5~10℃ / min.

39. The method according to claim 1, characterized in that, The heating endpoint of the calcination in step (5) is 1000~1700℃.

40. The method according to claim 39, characterized in that, The heating endpoint of the calcination in step (5) is 1200~1500℃.

41. The method according to claim 1, characterized in that, The calcination holding time in step (5) is 0.1~12h.

42. The method according to claim 41, characterized in that, The calcination holding time in step (5) is 0.5~8h.

43. The method according to claim 1, characterized in that, Step (5) includes furnace cooling after calcination.

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