Method for enhancing micro-nano bubble flotation minerals based on surface pretreatment

Abstract

The invention discloses a method for enhancing micro-nano bubble flotation minerals based on surface pretreatment. The method comprises the following steps: soaking a rubidium and cesium-containing mineral raw material in a strong alkali solution or a strong acid solution, and carrying out micro-nano bubble flotation on the obtained pretreated mineral to obtain rubidium and cesium-containing lepidolite concentrate or silicate gangue concentrate. According to the method, the surface roughness difference of the rubidium-cesium-containing lepidolite mineral and the albite mineral in the raw ore is improved through pretreatment with the strong alkali or the strong acid, then the flotation separation effect is remarkably improved, the recovery rate difference of the two minerals in a conventional fatty amine collecting agent reaches 14% or above, and the recovery rate and the grade of flotation concentrate can be improved.

Description

Technical Field

[0001] This invention relates to a flotation method, specifically a method for flotating minerals based on surface pretreatment to enhance micro-nano bubble flotation, belonging to the field of mineral processing technology. Background Technology

[0002] Lithium, as a core resource driving energy transformation, is experiencing explosive growth in demand for new energy vehicles, energy storage, and other fields. Rubidium and cesium, on the other hand, have important applications in traditional fields such as atomic clocks, frequency standards, satellite navigation, and aerospace measurement and control, as well as in cutting-edge technologies such as quantum computing and ion thrusters. Due to their highly reactive chemical properties, high-grade independent rubidium and cesium minerals are rare in nature. Lithium, as a member of the same group as rubidium and cesium, is often replaced by rubidium and cesium lattices, making lithium resources the main carrier minerals of these elements. Lithium resources are mainly found in three types of mineral deposits: salt lake brines, pegmatite-type lithium deposits, and clay-type lithium deposits. With the increasing demand for lithium and the continuous exploitation of spodumene, hard-rock lepidolite, due to its abundant reserves and associated rare elements such as rubidium and cesium, has gradually become another key mineral resource for development after salt lakes and spodumene. However, the flotation separation of lepidolite still faces severe challenges. Because lepidolite and silicate gangue minerals have highly similar surface electrical properties, wettability, and floatability, it is difficult to selectively recover only lepidolite without floating silicate gangue minerals in traditional amine-based cationic collector systems. While the emerging micro / nanobubble (MNB) flotation technology has proven to have better separation performance than conventional flotation in lepidolite mineral flotation applications, its instability and indiscriminate adhesion during the flotation process result in less than ideal flotation results.

[0003] Chinese patent document CN120900803A discloses a method for enhancing the flotation recovery of fine-particle rubidium-cesium associated lepidolite, but it does not solve the problem of non-selectivity of micro / nano bubbles. Therefore, developing a flotation method to improve the separation efficiency of rubidium-cesium associated lepidolite and silicate gangue minerals, thereby increasing the recovery rate and grade of rubidium-cesium associated lepidolite or improving the recovery rate of silicate gangue minerals, is of great significance. Summary of the Invention

[0004] To address the problems existing in the prior art, the purpose of this invention is to provide a method for mineral flotation based on surface pretreatment-enhanced micro / nanobubbles. This method can significantly improve the floatability of rubidium-cesium-containing lepidolite or silicate gangue minerals, increase the separation and recovery efficiency of lepidolite or silicate gangue minerals, and is simple, low-cost, and suitable for industrial production.

[0005] To achieve the above-mentioned technical objectives, the present invention provides a method for flotation of rubidium-cesium-containing lepidolite based on surface pretreatment-enhanced micro-nano bubble flotation. The method is as follows: the rubidium-cesium-containing mineral raw material is first soaked in a strong alkaline solution or a strong acid solution, and the pretreated mineral is then subjected to micro-nano bubble flotation to obtain rubidium-cesium-containing lepidolite concentrate. The concentration of the strong alkaline solution or strong acid solution is 500~2200 mg / L.

[0006] The rubidium-cesium-containing mineral raw material in this invention mainly consists of rubidium-cesium-containing lepidolite and albite. The rubidium-cesium-containing lepidolite is a layered aluminosilicate mineral, while albite is a framework aluminosilicate mineral. The two have significantly different crystal structures. Through pretreatment with high concentrations of strong acid or strong alkali, the surface roughness of the two minerals can evolve in opposite directions, resulting in completely different surface roughnesses. Since micro- and nano-bubbles tend to form stable physical anchors on rough surfaces, while they are difficult to adhere stably on smooth surfaces, the pretreatment amplifies the surface roughness differences between minerals, making the effect of micro- and nano-bubbles selective. This significantly expands the differences in floatability between different minerals, achieving efficient separation.

[0007] The surface roughness evolution law of rubidium-cesium mineral raw materials pretreated with high-concentration strong acid or strong alkali is as follows:

[0008] When a high concentration of strong alkali is used for pretreatment, OH - Etching has limited effect on the layered structure of rubidium-cesium lepidolite, mainly affecting bond breakage at layer edges and surface defects, resulting in surface fragmentation and roughening. However, it effectively dissolves Si-O-Al bonds in the framework structure of albite, making the surface more uniform and smooth. Therefore, after strong alkali pretreatment, the surface of rubidium-cesium lepidolite is rough, while the surface of albite is smooth. When micro / nano bubbles are subsequently introduced, the bubbles will selectively float the rubidium-cesium lepidolite.

[0009] When mineral raw materials are pretreated with high-concentration strong acids, rubidium-, cesium-, and lithium-containing mica will be affected by H. + Easy to enter interlayer displacement K + This leads to "exfoliation" dissolution on the surface, reducing surface roughness and making it smoother; while the stable framework structure of albite makes it resistant to strong acid corrosion, but it preferentially dissolves surface defects and Na in the crystal lattice. + This process makes the original cleavage profile more prominent and increases the surface roughness. Therefore, after strong acid pretreatment, the surface of rubidium-cesium-lithium mica is smooth, while the surface of albite is rough. During subsequent micro-nano bubble flotation, the micro-nano bubbles will selectively float albite.

[0010] As a preferred embodiment, the concentration of the strong alkali solution or strong acid solution is 1000~2000 mg / L, more preferably 1500~2000 mg / L.

[0011] As a preferred embodiment, the concentration of the rubidium-cesium-containing mineral raw material in a strong alkaline solution or a strong acid solution is 40~50 g / L.

[0012] As a preferred embodiment, the strong alkaline solution includes at least one of sodium hydroxide solution and potassium hydroxide solution.

[0013] As a preferred embodiment, the strong acid solution includes at least one of hydrochloric acid, sulfuric acid, and nitric acid.

[0014] As a preferred embodiment, the soaking conditions are: temperature of 20~30℃, time of 1~13min, more preferably 9~13min; and stirring speed of 1000~1500r / min.

[0015] As a preferred embodiment, the rubidium-cesium-bearing mineral raw material contains rubidium-cesium-bearing lepidolite and albite. The rubidium-cesium-bearing lepidolite, as the first mineral, has a Li grade of 2.00%-3.00%, a Rb grade of 0.50%-0.60%, and a Cs grade of 0.12%-0.15%; the albite, as the second mineral, has a Na content of 8.00%-9.00%.

[0016] As a preferred embodiment, the rubidium-cesium-containing mineral raw material has a particle size of -0.074 mm.

[0017] As a preferred approach, after the soaking treatment, the pretreated minerals are washed with water until the pH of the washing solution is neutral.

[0018] As a preferred embodiment, the rubidium-cesium-containing mineral raw material is treated by soaking in a strong alkaline solution or a strong acid solution, followed by solid-liquid separation to obtain pretreated minerals.

[0019] As a preferred embodiment, the micro-nano bubble flotation process is as follows: pretreated minerals are mixed with micro-nano bubble water to obtain flotation slurry, and then the flotation slurry is placed in a flotation machine and a pH adjuster and a collector are added in sequence for stirring and reaction, followed by bubble scraping.

[0020] As a preferred embodiment, the micro-nano bubbles are generated by means of hydraulic cavitation, acoustic cavitation, pressurized gas dissolution, etc., and the average particle size of the micro-nano bubbles is preferably 200~500nm.

[0021] As a preferred embodiment, the concentration of the flotation pulp is 40-80 g / L, the pH value of the pulp is adjusted to 2-6, and the collector is a fatty amine.

[0022] As a preferred embodiment, the amount of collector added is 10~80 mg / L of slurry.

[0023] As a preferred embodiment, the fatty amine is dodecylamine.

[0024] As a preferred embodiment, the pH adjuster is dilute hydrochloric acid.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] (1) High concentration of strong alkali or strong acid is used to corrode the surface of rubidium-cesium-containing mineral raw materials, which increases the difference in surface roughness between rubidium-cesium-containing lepidolite minerals and albite minerals in the mineral raw materials, transforming the non-selectivity of micro-nano bubbles into selectivity, thereby improving the difference in recovery rate between the two minerals in micro-nano bubble flotation (the difference in recovery rate in aliphatic amine flotation reaches more than 14%). The flotation effect is significantly better than that of traditional flotation methods (the difference in recovery rate in traditional aliphatic amine flotation is only 4-6%), and it is especially suitable for the selective separation of silicate minerals with similar surface properties (such as rubidium-cesium-containing lepidolite and albite).

[0027] (2) The method is simple, the flotation separation effect is good, the cost is low, and it is suitable for industrial production. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0029] Figure 1 is an electron microscope image of the original appearance of the mineral raw materials containing rubidium, cesium, lepidolite and albite in the embodiment of the present invention.

[0030] Figure 2 is an electron microscope image of rubidium-cesium-containing lepidolite and albite after alkali pretreatment in Example 1 of the present invention.

[0031] Figure 3 is an electron microscope image of rubidium-cesium-containing lepidolite and albite after acid pretreatment in Example 2 of the present invention. Detailed Implementation

[0032] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] In this embodiment of the invention, a mixed ore containing rubidium-cesium lepidolite and albite with a mass ratio of 1:1 was used as the ore sample to be floated. The chemical elemental compositions of the rubidium-cesium lepidolite and albite are shown in Table 1, and the original surface morphology of the two minerals is shown in Table 2. Figure 1 .

[0034]

[0035] After crushing and sieving, the particle size range of the sample is -0.074 mm, which meets the flotation particle size requirements.

[0036] Example 1

[0037] (1) Take particles with a diameter of -74 mm respectively Two g of rubidium-cesium lepidolite and two g of albite were added to 40 mL of a 2000 mg / L sodium hydroxide solution. The mixture was pretreated with alkali for 9 min at 1200 rpm and 25 °C, and allowed to stand for 5 min. The supernatant was then discarded, and the sample was rinsed five times with deionized water to ensure the pH of the supernatant was neutral. Finally, the pretreated sample was used directly for micro-flotation experiments.

[0038] (2) Nanobubble water was prepared by cavitation circulation treatment of deionized water using a micro-nano bubble generator. The air intake rate was 0.2 L / min, the cavitation pressure was 0.5 MPa, the cavitation time was 8 min, and the settling time was 10 min. 1000 mL of deionized water was used for each cavitation test and the preparation was carried out in a 1000 mL beaker.

[0039] (3) The mixed mineral sample obtained in step (1) is mixed with 50 ml of micro-nano bubble water to prepare a slurry with a mass concentration of 80 g / L. After ultrasonic dispersion for 2 min, the slurry is transferred to a flotation machine and stirred for 2 min. Dilute hydrochloric acid is added to adjust the pH of the slurry to 2. After maintaining for 2 min, 0.7 mg of collector dodecylamine is added. After reacting for 2 min, the foam is manually scraped for 2 min (scraped once every 10 s). The foam and tailings products are collected, filtered, dried and weighed respectively.

[0040] Under the conditions of this embodiment, the recovery rate of rubidium-cesium lepidolite in the flotation foam product was 92.46%, the recovery rates of Rb and Cs were 90.92% and 89.06%, respectively, with grades of 0.90% and 0.15%, respectively; the recovery rate of albite was 77.92%. The floatability of rubidium-cesium lepidolite was significantly higher than that of albite, with a recovery rate difference of 14.54%.

[0041] from Figure 2As can be seen, after soaking in a high-concentration sodium hydroxide solution, the surface roughness of rubidium-cesium lepidolite increased significantly, while the surface of albite became smoother. This means that pretreatment with a high-concentration sodium hydroxide solution also improved the surface roughness difference between the target mineral (rubidium-cesium lepidolite) and the gangue mineral (albite), thereby increasing the selective adhesion of micro- and nano-bubbles to the surface of rubidium-cesium lepidolite and improving the flotation separation efficiency of micro- and nano-bubbles.

[0042] Example 2

[0043] Alkali pretreatment and micro / nano bubble flotation were performed according to the method in Example 1, with the only difference being that the concentration of sodium hydroxide solution in step (1) was 1000 mg / L.

[0044] Under the conditions of this embodiment, the recovery rate of rubidium-cesium lepidolite in the flotation foam product was 89.17%, the recovery rates of Rb and Cs were 86.95% and 85.40%, respectively, with grades of 0.85% and 0.14%, respectively; the recovery rate of albite was 79.10%, and the floatability of rubidium-cesium lepidolite was also significantly higher than that of albite, with a recovery rate difference of 10.07%.

[0045] Example 3

[0046] (1) Take particles with a diameter of -74 mm respectively 2 g of rubidium-cesium lepidolite and 2 g of sodium feldspar were added to 40 mL of hydrochloric acid solution with a concentration of 2000 mg / L. The acid pretreatment was carried out for 9 min under the conditions of stirring speed of 1200 rpm and temperature of 25℃. After standing for 5 min, the supernatant was discarded and the sample was rinsed repeatedly with deionized water 5 times to ensure that the pH of the supernatant was neutral. Finally, the pretreated sample was directly used for micro-flotation test.

[0047] (2) Nanobubble water was prepared by cavitation circulation treatment of deionized water using a micro-nano bubble generator. The air intake rate was 0.2 L / min, the cavitation pressure was 0.5 MPa, the cavitation time was 8 min, and the settling time was 10 min. 1000 mL of deionized water was used for each cavitation test and the preparation was carried out in a 1000 mL beaker.

[0048] (3) The mixed mineral sample obtained by acid pretreatment in step (1) is mixed with 50 ml of micro-nano bubble water prepared in step (2) to prepare a slurry of 80 g / L. After ultrasonic dispersion treatment for 2 min, the slurry is transferred to a flotation machine and stirred for 2 min. Dilute hydrochloric acid is added to adjust the pH of the slurry to 2. After maintaining for 2 min, 0.7 mg of collector dodecylamine is added. After reacting for 2 min, the foam is manually scraped for 2 min (scraped once every 10 s). The foam and tailings products are collected, filtered, dried and weighed respectively.

[0049] Under the conditions of this embodiment, the recovery rate of rubidium-cesium lepidolite was 72.62%, the recovery rates of Rb and Cs were 63.48% and 64.46%, respectively, with grades of 0.61% and 0.12%, respectively; the recovery rate of albite was 91.32%, and the floatability of albite was significantly higher than that of rubidium-cesium lepidolite, with a recovery difference of 18.70%.

[0050] from Figure 3 It is evident that after soaking in high-concentration hydrochloric acid, the surface smoothness of rubidium-cesium lepidolite increases significantly, while the surface pits of albite increase and the roughness increases significantly. This means that the high-concentration hydrochloric acid pretreatment improves the surface roughness difference between the target mineral rubidium-cesium lepidolite and the gangue mineral albite, thereby improving the selective adhesion of micro-nano bubbles on the surface of albite minerals and thus improving the flotation separation efficiency of micro-nano bubbles.

[0051] Comparative Example 1

[0052] The method of Example 3 was used for micro-nano bubble flotation, the only difference being that the acid soaking pretreatment in step (1) was omitted.

[0053] Under these comparative conditions, the recovery rate of rubidium- and cesium-containing lepidolite was 88.99%, and the recovery rates of Rb and Cs were 75.86% and 75.40%, respectively, with grades of 0.81% and 0.14%, respectively. The recovery rate of albite was 84.90%. The recovery rates of rubidium- and cesium-containing lepidolite and albite were relatively close, with a difference of 4.09%.

[0054] Comparative Example 2

[0055] The flotation was carried out using the method of Example 3, the difference being that the acid soaking pretreatment in step (1) was omitted, and conventional deionized water was used instead of micro-nano bubble water.

[0056] Under these comparative conditions, the recovery rate of rubidium- and cesium-containing lepidolite was 84.79%, and the recovery rates of Rb and Cs were 71.70% and 72.74%, respectively, with grades of 0.78% and 0.14%, respectively. The recovery rate of albite was 79.18%. The recovery rates of rubidium- and cesium-containing lepidolite and albite were also very close, with a difference of 5.61%.

[0057] Comparative Example 3

[0058] Alkali pretreatment and micro / nano bubble flotation were performed using the method of Example 1, with the only difference being that the concentration of sodium hydroxide solution in step (1) was 200 mg / L.

[0059] Under these comparative conditions, the recovery rate of rubidium-cesium lepidolite in the flotation froth product was 88.84%, while the recoveries of Rb and Cs were 85.86% and 82.74%, respectively, with grades of 0.88% and 0.14%. The recovery rate of albite was 84.16%, indicating that the floatability of rubidium-cesium lepidolite was close to that of albite, with a recovery rate difference of 4.86%. This demonstrates that using a low-concentration strong alkaline solution cannot increase the surface roughness difference between the two minerals, and therefore cannot improve the flotation separation effect.

[0060] In summary, the flotation method of this invention enhances the floatability of rubidium-cesium-lepidolite minerals in micro-nano bubble water after high-concentration strong alkali pretreatment, thereby capturing more rubidium-cesium-lepidolite target minerals in the forward flotation process and improving the flotation recovery rate. Conversely, high-concentration strong acid pretreatment significantly inhibits the floatability of rubidium-cesium-lepidolite minerals in micro-nano bubble water and enhances the floatability of albite, thereby effectively inhibiting the floating of rubidium-cesium-lepidolite target minerals in the reverse flotation process and removing impurity silicate gangue minerals. Furthermore, the flotation separation effect of this invention is significantly better than that of MNBs flotation (Comparative Example 1) and DI flotation (Comparative Example 2).

[0061] Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for mineral flotation based on surface pretreatment-enhanced micro / nanobubble flotation, characterized in that: Rubidium- and cesium-containing mineral raw materials are first treated by soaking in a strong alkaline solution or a strong acid solution. The pretreated minerals are then subjected to micro- and nano-bubble flotation to obtain rubidium- and cesium-containing lepidolite concentrate or silicate gangue concentrate. The concentration of the strong alkaline solution or strong acid solution is 500~2200 mg / L.

2. The method for mineral flotation based on surface pretreatment-enhanced micro / nano bubble flotation according to claim 1, characterized in that: The concentration of the strong alkali solution or strong acid solution is 1000~2000 mg / L.

3. A method for mineral flotation based on surface pretreatment-enhanced micro / nano bubble flotation according to claim 1 or 2, characterized in that: The concentration of the rubidium-cesium-containing mineral raw material in a strong alkaline solution or a strong acid solution is 40~50 g / L.

4. A method for mineral flotation based on surface pretreatment-enhanced micro / nano bubble flotation according to claim 1 or 2, characterized in that: The strong alkaline solution includes at least one of sodium hydroxide solution and potassium hydroxide solution; The strong acid solution includes at least one of hydrochloric acid, sulfuric acid, and nitric acid.

5. The method for mineral flotation based on surface pretreatment-enhanced micro / nano bubble flotation according to claim 1, characterized in that: The soaking conditions are as follows: temperature 20~30℃, time 1~13min; stirring speed 1000~1500r / min.

6. The method for mineral flotation based on surface pretreatment-enhanced micro / nano bubble flotation according to claim 1, characterized in that: The rubidium-cesium-containing mineral raw material contains rubidium-cesium-containing lepidolite and albite.

7. The method for mineral flotation based on surface pretreatment-enhanced micro / nano bubble flotation according to claim 1, characterized in that: The rubidium- and cesium-containing mineral raw materials are treated by soaking in a strong alkaline solution or a strong acid solution, followed by solid-liquid separation to obtain pretreated minerals. The process of micro-nano bubble flotation is as follows: pretreated minerals are mixed with micro-nano bubble water to obtain flotation slurry, and then the flotation slurry is placed in a flotation machine and pH adjuster and collector are added in sequence for stirring and reaction, followed by bubble scraping.

8. The method for mineral flotation based on surface pretreatment-enhanced micro / nano bubble flotation according to claim 7, characterized in that: The concentration of the flotation pulp is 40-80 g / L, and the pH value of the pulp is adjusted to 2-6; the collector is a fatty amine.

9. A method for mineral flotation based on surface pretreatment-enhanced micro / nano bubble flotation according to claim 7 or 8, characterized in that: The amount of collector added is 10~80 mg / L of slurry.

10. The method for mineral flotation based on surface pretreatment-enhanced micro / nano bubble flotation according to claim 8, characterized in that: The fatty amine is dodecylamine.

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