A method for screening of functional groups of flotation regulator molecules based on anisotropy of mineral crystal faces

Abstract

The application discloses a flotation regulator screening method based on mineral crystal face anisotropy, and the method controls the infeed and outfeed of a gold sheet substrate modified by a single regulator molecular functional group and a coating surface adsorption substrate exposing a single mineral crystal face through a piezoelectric driver of an SFA (surface force apparatus), and studies the nanoscale interaction force between the regulator molecular functional group and the mineral crystal face in combination with an EDLVO theoretical model, realizes the visualization of absolute distance, greatly reduces the theoretical fitting error, screens the regulator molecular functional group with the strongest adhesion and the strongest selectivity to the mineral with crystal face anisotropy, and can accurately analyze the interaction force between the regulator functional group and the mineral crystal face and reveal the microscopic mechanical mechanism in the regulator adsorption process, and scientifically guides the optimization of the regulator molecular structure.

Description

TECHNICAL FIELD

[0001] The present application relates to a flotation regulator molecule functional group screening method based on the anisotropy of mineral crystal faces, belonging to the field of mineral processing flotation reagent design. BACKGROUND

[0002] Foam flotation is a widely used high-efficiency beneficiation technology in the field of mineral processing. In the flotation process, regulators, as an important class of flotation reagents, control the surface physicochemical properties of minerals by selectively adsorbing on specific crystal faces, thereby optimizing the final beneficiation effect. However, for some minerals, the addition of regulators often results in the opposite of the expected flotation behavior. The fundamental reason is that the surface properties of mineral crystals have significant anisotropy on different crystal faces, which leads to anisotropic adsorption between the regulator and the mineral. Therefore, the anisotropic interface interaction between the regulator and the specific crystal face of the mineral is a key factor in determining the efficiency of flotation separation. However, the accurate and reliable characterization of the anisotropy of the mineral surface still faces challenges. In addition, the current development of regulators mainly relies on experience and qualitative analysis, and the interaction mechanism between the molecular structure of the regulator and the specific crystal face is not clear. This further leads to the unclear influence of the molecular structure of the regulator on the floatability of the specific crystal face of the mineral, making it difficult to scientifically guide the design and development of new regulators and limiting the optimization of the flotation process and the efficient separation of complex ores.

[0003] In common ore pulp environments, the interaction between regulator molecules and mineral crystal faces mainly includes van der Waals force, electrostatic force, hydrophobic force, and coordination action, etc. Currently, there is a lack of experimental methods that can directly quantify the interaction force between the functional groups of the regulator and the mineral crystal face, and related technologies need to be developed. Atomic force microscopy (AFM) and surface force apparatus (SFA) are high-precision mechanical tools that can provide mechanical information at the micro-nano scale.

[0004] Although AFM has been used to design coal slime flotation collectors (such as Chinese patent application CN114577716A), it cannot simultaneously monitor the absolute distance between the collector and the mineral surface, resulting in larger errors in theoretical fitting, and the force measurement range is limited to pico-Newton to nano-Newton, making it difficult to identify stronger interactions. In contrast, SFA can visualize absolute distance, and the force measurement range is from nano-Newton to micro-Newton, which has an advantage in measuring stronger interactions. By chemically modifying the functional group molecules of the target regulator and the mineral crystal face on the corresponding substrate and fixing them on the cylinder disc of the SFA system, the interaction force between the functional group and the mineral crystal face can be accurately measured, revealing its micro-mechanical action mechanism. This will help to develop regulator molecules with selective adsorption properties on specific mineral crystal faces, providing important theoretical support for achieving efficient flotation separation of minerals. And there is a lack of selective guidance method for the functional groups of the flotation regulator molecules of the mineral with anisotropic crystal face in the prior art. Summary of the Invention

[0005] To address the limitations of existing screening methods, such as large theoretical fitting errors and a lack of guidance for selectivity based on crystal face anisotropy, the present invention aims to provide a method for screening the functional groups of flotation modifier molecules based on the anisotropy of mineral crystal faces. By leveraging SFA, which precisely measures the interaction forces between modifier molecular functional groups and mineral crystal faces, this method not only directly designs modifier molecules with optimal adhesion and high selectivity for anisotropic crystal faces, but also accurately analyzes the interaction forces between modifier functional groups and mineral crystal faces and reveals the micromechanical mechanisms of modifier adsorption, providing scientific guidance for optimizing modifier molecular structures.

[0006] In order to achieve the above technical objectives, the present invention provides a method for screening functional groups of flotation modifier molecules based on mineral crystal anisotropy, comprising the following steps:

[0007] 1) placing the gold sheet substrate in a solution containing a functional group of a modifier molecule for immersion modification to obtain a gold sheet substrate modified with a single functional group of the modifier molecule;

[0008] 2) After depositing the mineral suspensions with crystal face anisotropy on the corresponding substrates, loosely adsorbed mineral particles are removed by water washing to obtain different coating surfaces with exposed single mineral crystal faces;

[0009] 3) Adhere an unmodified gold substrate and an adsorbed substrate to two cylindrical silica disks with a nominal curvature radius R in the SFA chamber using UV-curable adhesive. The unmodified gold substrate is located above the adsorbed substrate, and the two cylindrical silica disks are arranged in a cross-shaped pattern on a vertical projection plane, corresponding to a plane close to the Derjaguin approximation of a sphere with a radius of R.

[0010] 4) In a protective atmosphere, the piezoelectric actuator of the SFA is controlled to drive the unmodified gold substrate into contact with the adsorption substrate, and the contact reference D = 0 is determined using a multi-beam interferometry method based on isochromatic fringes;

[0011] 5) replace the unmodified gold sheet substrate with a single modifier molecule functional group modified gold sheet substrate, and adhere the coating surface exposing a single mineral crystal plane to the adsorption substrate, inject the test solution into the chamber of the SFA, control the in-line and off-line of the single modifier molecule functional group modified gold sheet substrate and the coating surface exposing a single mineral crystal plane adsorption substrate by controlling the piezoelectric driver, monitor the deflection of the double cantilever spring in real time, and convert it into the function F(D) of the interaction force F and the separation distance D, and determine the real-time separation distance D by FECO fringe observation of the interaction area; wherein, the in-line represents the process of the single modifier molecule functional group modified gold sheet substrate and the coating surface exposing a single mineral crystal plane adsorption substrate approaching each other, and the off-line represents the process of the single modifier molecule functional group modified gold sheet substrate and the coating surface exposing a single mineral crystal plane adsorption substrate moving away from each other;

[0012] 6) convert the force signal F measured in the in-line and off-line processes into the unit area interaction energy between the two planes using the Derjaguin approximation method, and generate the in-line force curve and the off-line force curve; the negative value of F / R in the in-line indicates that there is an attractive force between the flotation modifier molecule functional group and the mineral crystal plane that promotes adsorption, and the positive value represents a repulsive force that hinders the adsorption of the functional group, and the negative value of F / R in the off-line indicates that there is an adhesive force when the two separate, and no negative force is detected, which indicates that there is no adhesive force;

[0013] 7) replace the different coating surfaces exposing a single mineral crystal plane and adhere them to the adsorption substrate, repeat steps 5-6, and obtain the in-line force curve and the off-line force curve of the modifier molecule functional group and the different crystal planes of the mineral; analyze the adsorption of the flotation modifier molecule functional group on the mineral crystal plane and the interaction mechanism by comparing the unit area interaction energy of the in-line and off-line;

[0014] 8) replace the type of flotation modifier molecule functional group, repeat steps 5-7, obtain the in-line force curve and the off-line force curve of different modifier molecule functional groups and different coating surfaces exposing a single mineral crystal plane, compare all in-line curve values, and the greater the negative value of F / R in the off-line indicates the greater the adhesive force between the two, and the greater the adhesive force indicates the better the adsorption effect of the modifier molecule functional group.

[0015] The core of this technical solution is to control the adsorption and withdrawal of a gold substrate modified with a single modifier molecule functional group and a coating surface exposing a single mineral crystal face by controlling the piezoelectric actuator of an SFA (surface force instrument). This allows for the investigation of nanoscale interactions between the flotation modifier molecule functional group and the mineral crystal face, visualizing absolute distances and significantly reducing theoretical fitting errors. This allows for the selection of modifier molecule functional groups with the strongest adhesion and the highest selectivity for minerals with crystal face anisotropy. The detailed principle is as follows: First, a gold substrate is surface-modified with a single functional group by immersing it in a solution containing the modifier molecule functional group. Simultaneously, a mineral suspension with crystal face anisotropy is deposited onto the substrate, exposing a single mineral crystal face. The SFA is then used to measure the interaction force between the modified gold substrate and the mineral crystal face. By controlling the piezoelectric actuator to bring the two closer or further apart, the deflection of the supporting dual cantilever spring is monitored in real time and converted into a function of interaction force versus separation distance. The measured force signal is then converted to interaction energy per unit area using the Derjaguin approximation, generating the adsorption and withdrawal force curves. The feed-in force curve reflects the adsorption between the modifier's molecular functional groups and the mineral crystal surface, while the back-out force curve reflects the adhesion force during separation. Finally, by changing the mineral crystal surface and modifier's molecular functional groups, repeatedly measuring and comparing the feed-in and back-out force curves, the modifier's molecular functional groups with the best adsorption performance can be screened.

[0016] In the present invention, the two cylindrical silicon dioxide disks are cross-distributed on the vertical projection plane and are arranged to correspond to a sphere with a radius R close to the Derjaguin approximation plane. This arrangement is also critical, as it can minimize the fitting error.

[0017] As a preferred solution, the selectivity of the adjuster molecular functional group for the mineral crystal face can be determined by comparing the difference between the delinear force curves of the adjuster molecular functional group and different crystal faces of the mineral in step 7. The greater the difference in the delinear force curves of different crystal faces of the mineral, the better the selectivity of the adjuster molecular functional group for the mineral crystal face.

[0018] As a preferred solution, the adsorption condition and interaction mechanism of the flotation adjuster molecule functional groups on the mineral crystal surface are judged as follows: the larger the negative value of F / R in the line force curve, the stronger the attraction between the flotation adjuster molecule functional groups and the mineral surface, and the easier it is for the two to adsorb; the larger the positive value, the stronger the repulsion between the two, and the greater the difficulty of adsorption; the larger the negative value in the line force curve, the greater the adhesion between the two, and the more firmly the flotation adjuster molecule functional groups are adsorbed on the mineral crystal surface.

[0019] As a preferred solution, when changing the type of functional group of the flotation adjuster molecule in step 8, only the functional group of the adjuster is changed, and the rest of the molecular structure (such as molecular chain length) should remain consistent to avoid these factors interfering with the force measurement experiment and subsequent fitting analysis.

[0020] As a preferred solution, the solution containing the functional groups of the regulator molecules is an ethanol solution of a thiol compound blocked with the functional groups of the regulator molecules, and the functional groups of the regulator molecules include but are not limited to carboxyl, hydroxyl or phosphoric acid.

[0021] As a preferred solution, in step 5, the test solution is a NaCl solution with a pH of 5.5 or 8.5. The test solution used in the present invention primarily simulates a common ore pulp ionic strength environment to reduce the impact of small amounts of impurity ions in the solution. When different minerals are selected, the pH value of the test solution can be adjusted according to the actual flotation conditions.

[0022] As a preferred solution, each time the gold sheet substrate modified with a single adjuster molecule functional group and the coating surface adsorption substrate exposing a single mineral crystal face are replaced, the test solution needs to be re-injected into the chamber, and the concentration and pH value of the test solution should be kept consistent before and after, and the test solution needs to be filtered with a 0.22 μm filter head before injection.

[0023] As a preferred embodiment, in step 2, the mineral suspension having crystal face anisotropy is prepared by crushing and screening the mineral, grinding the mineral to obtain a mineral powder, dissolving the powder in a solvent, and subjecting the powder to ultrasonic treatment. The preparation process of the present invention can fully expose the different crystal faces in the mineral.

[0024] As a preferred embodiment, the mineral comprises one of serpentine, rutile, anatase, pyrrhotite, chalcopyrite, galena, sphalerite, stibnite, quartz, calcite, fluorite, wolframite, dolomite, and spodumene; and the adsorption substrate comprises one of mica flakes, glass flake substrates, graphite substrates, polydimethylsiloxane, polyethylene, and polypropylene. The serpentine comprises one of antigorite, chrysotile, orthoserpentine, and lizardite nanosheets. The adsorption substrate used in the present invention may also comprise conventional non-metallic substrates or polymeric material substrates known in the art.

[0025] As a preferred solution, the shapes of the surface in the interaction zone and the thin liquid film trapped between the surfaces are observed in real time through FECO stripes during the force measurement process, and the difficulty of adsorption between the functional groups of the adjuster molecules and the mineral crystal surfaces is analyzed in combination with the EDLVO theoretical model.

[0026] As a preferred scheme, the incoming line force curve data is fitted based on the EDLVO theory model to determine the contribution rate of van der Waals force, electrostatic force and hydrophobic force to the interaction; the outgoing line force curve data is normally distributed to obtain the typical adhesion force between the functional groups and the mineral crystal surface, and the mechanical mechanism of the adsorption process of the functional groups of the flotation regulator molecules on the mineral crystal surface is analyzed.

[0027] As a preferred scheme, all SFA force measurement experiments are carried out in a constant temperature clean room. Further, the temperature is 23-25°C.

[0028] As a preferred scheme, when the adsorption substrate used is mica sheet, the freshly peeled mica sheet is manually cut to provide an area of 5-10 cm 2 and a uniform thickness of 2-5 μm, and it is immediately stuck on a cylindrical silica disc for force measurement to prevent surface contamination.

[0029] Compared with the prior art, the present application has the following beneficial technical effects:

[0030] 1) The present application can directly study the interaction between the regulator and the mineral crystal surface at the molecular level by modifying a single functional group, avoiding the interference of a complex system.

[0031] 2) Compared with the traditional method of designing regulator molecules depending on experience, the flotation regulator molecule functional group screening method provided by the present application can directly screen the regulator with the best adhesion force by comparing the interaction forces between different regulator molecules and the mineral crystal surface, quickly evaluate the performance of different functional groups, reduce the loss of raw materials caused by blind reliance on experience design tests, and improve the design efficiency.

[0032] 3) The flotation regulator molecule functional group screening method provided by the present application uses a cross-cylinder geometry (approximately a sphere-plane model) for the two substrates, which ensures the large-scale uniformity of the contact area and the high precision of the force measurement, avoiding the errors caused by the surface non-uniformity and the local effect of the AFM needle tip in the traditional method.

[0033] 4) Compared with the AFM which indirectly estimates the relative separation distance by relying on displacement sensors, the flotation regulator molecule functional group design method provided by the present application directly measures the absolute separation distance D by using the multi-beam interference technology (FECO), with a resolution of sub-nanometer (<0.1 nm), and can also provide additional information such as surface topography and thickness variation, which can provide higher precision force-distance curves to ensure the accuracy of the screening results.

[0034] 5) Compared with traditional characterization methods limited to vacuum or dry conditions, the present invention provides a method for screening functional groups of flotation modifier molecules that can directly control solution composition, temperature, pH, etc. in the liquid phase, simulating actual slurry conditions and quantifying the interaction forces between modifier molecules and mineral crystal surfaces in situ, ensuring that the selected modifiers have greater practical application value.

[0035] 6) The present invention can accurately analyze the interaction force between the modifier functional groups and the mineral crystal faces and reveal the micromechanical mechanism of the modifier adsorption process, scientifically guiding the optimization of the modifier molecular structure. Moreover, for minerals with crystal face anisotropy, the modifier molecular functional groups with the highest selectivity for the mineral crystal faces can be screened out by comparing the differences in the linear force curves and linear force curves of different mineral crystal faces. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The cross-cylinder geometry in the figure represents a schematic diagram of two cylindrical silicon dioxide disks arranged crosswise on a vertical projection plane.

[0037] Figure 2 This is a typical force-distance curve measured during the interaction between undecanoic acid and the MgOH and SiO basal planes of serpentine in a liquid environment according to Example 1 of the present invention.

[0038] Figure 3 This is a typical force-distance curve measured during the interaction between undecanoic acid away from the MgOH and SiO basal planes of serpentine in a liquid environment in Example 1 of the present invention.

[0039] Figure 4 This is a typical force-distance curve measured during the interaction between undecanol and the basal plane of serpentine MgOH and SiO in a liquid environment in Example 2 of the present invention.

[0040] Figure 5 This is a typical force-distance curve measured during the interaction between undecanol away from the serpentine MgOH and SiO basal plane in the liquid environment of Example 2 of the present invention.

[0041] Figure 6 This is a typical force-distance curve measured during the interaction between undecylphosphoric acid and serpentine MgOH and SiO basal plane in a liquid environment in Example 3 of the present invention.

[0042] Figure 7 This is a typical force-distance curve measured during the interaction between undecylphosphoric acid away from the serpentine MgOH and SiO basal plane in a liquid environment in Example 3 of the present invention.

[0043] Figure 8This is a typical force-distance curve measured during the interaction between undecanoic acid and the MgOH and SiO basal planes of serpentine in a liquid environment in Example 4 of the present invention.

[0044] Figure 9 This is a typical force-distance curve measured during the interaction between undecanoic acid away from the serpentine MgOH and SiO basal plane in a liquid environment in Example 4 of the present invention.

[0045] Figure 10 This is a typical force-distance curve measured during the interaction between undecanol and the basal plane of serpentine MgOH and SiO in a liquid environment in Example 5 of the present invention.

[0046] Figure 11 This is a typical force-distance curve measured during the interaction between undecanol away from the serpentine MgOH and SiO basal plane in a liquid environment in Example 5 of the present invention.

[0047] Figure 12 This is a typical force-distance curve measured during the interaction between undecylphosphoric acid and serpentine MgOH and SiO basal plane in a liquid environment in Example 6 of the present invention.

[0048] Figure 13 This is a typical force-distance curve measured during the interaction between undecylphosphoric acid away from the serpentine MgOH and SiO basal plane in a liquid environment in Example 6 of the present invention.

[0049] Figure 14 This is a typical force-distance curve measured during the interaction between undecylphosphoric acid and rutile 110 and 011 crystal planes in a liquid environment according to Example 7 of the present invention.

[0050] Figure 15 This is a typical force-distance curve measured during the interaction of undecylphosphoric acid away from the 110 and 011 crystal planes of rutile in a liquid environment in Example 7 of the present invention.

[0051] Figure 16 This is a typical force-distance curve measured during the interaction between undecanoic acid and the MgOH and SiO basal planes of serpentine in a liquid environment in Comparative Example 1 of the present invention.

[0052] Figure 17 This is a typical force-distance curve measured during the interaction between undecanoic acid away from the serpentine MgOH and SiO basal plane in the liquid environment of Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0053] To further understand the present invention, the interaction between different crystal planes of serpentine and reagent molecules during the flotation process is taken as an example, and the present invention is described in detail through specific embodiments to help technical workers in related fields better understand the concept and technical solution of the present invention, but is not limited to the following embodiments.

[0054] The serpentine nanosheet suspensions of Examples 1 to 6 of the present invention were prepared by the following preparation method: lizardite was crushed, sieved (passing 600 mesh), and ground to obtain lizardite powder with a particle size of -3 μm; 0.15 g of serpentine powder was dissolved in 50 mL of isopropanol and then treated in an ultrasonic cleaner with a power of 480 W for 2 h.

[0055] Example 1

[0056] Interactions between carboxyl groups and different crystal faces of serpentine

[0057] (1) Cut into 8cm pieces 2 After UV cleaning for 30 minutes to remove surface contaminants, the gold substrates were immersed in a 3 mM 11-mercaptoundecanoic acid ethanol solution for 12 hours, then rinsed three times with ethanol and deionized water, and dried with nitrogen gas to obtain the carboxyl-modified gold substrates, which were immediately used for interaction force measurements.

[0058] (2) About 10 μL of serpentine nanosheet suspension was added dropwise at 75°C and deposited on brucite and mica substrates, respectively. The functional groups on the substrates were combined with different crystal faces of the serpentine nanosheets to expose a single crystal face. The nanosheets were dried within 5 min and then rinsed with deionized water at pH ≈ 6.5 and ultrasonically treated for 2 min to remove loosely adsorbed serpentine particles. Serpentine MgOH face and SiO face were prepared, respectively.

[0059] (3) Use a surgical blade to cut the 3 μm thick PVD back-coated silver mica substrate into 8 cm 2 Then, UV-curable glue was used to glue the gold sheet and the cylindrical silicon disk with a nominal curvature radius of R = 2 cm. The two cylindrical silicon dioxide disks were installed in the SFA clean room in a cross-distribution on the vertical projection plane, corresponding to the plane of the sphere with a radius of R close to the Derjaguin approximation.

[0060] (4) In a dry argon environment, the unmodified gold substrate is driven to contact the surface of the mica substrate by a piezoelectric actuator, and the contact reference D = 0 is determined by the multi-beam interferometry method based on equal color fringe (FECO);

[0061] (5) The unmodified gold substrate was replaced with a carboxyl-modified gold substrate, and the serpentine MgOH surface was adhered to the mica substrate. The SFA chamber was filled with a 10 mM NaCl test solution with a pH of 8.5 (filtered with a 0.22 μm filter before injection). The carboxyl-modified gold substrate and the serpentine MgOH surface were driven to approach and move away from each other. The deflection of the supporting double cantilever spring was monitored in real time and converted into a function F(D) of the interaction force F and the separation distance D. The real-time separation distance D was determined by observing the interaction area through FECO fringes.

[0062] (6) Use the Derjaguin approximation method to convert the force signal F measured during the advance and retreat process into the unit area interaction energy between two planes to generate the advance force curve and the retreat force curve; Figure 2 and Figure 3 As shown, a negative value of the force F / R in the incoming line indicates that there is an attractive force between the carboxyl group and the serpentine MgOH surface that promotes adsorption, a positive value indicates that there is a repulsive force that hinders adsorption, a negative value of the force F / R in the outgoing line indicates that there is an adhesive force when the two are separated, and no negative force is detected indicating that there is no adhesive force;

[0063] (7) Tear off the serpentine MgOH surface from the cylindrical silicon disk, replace it with the serpentine SiO surface, refill it with 10 mM NaCl test solution with a pH value of 8.5, repeat steps 5 to 6, and obtain the interaction curves between carboxyl groups and the serpentine MgOH surface and SiO surface, as shown in Figure 2 and Figure 3 As shown in the figure, by comparing the interaction energy per unit area of ​​the incoming and outgoing lines, the adsorption of carboxyl groups on the serpentine MgOH and SiO surfaces and the interaction mechanism are analyzed. The more negative the F / R value in the incoming line, the stronger the attraction between the carboxyl group and the serpentine MgOH or SiO surface, and the easier it is to adsorb the two. The more positive the value, the stronger the repulsion between the two, and the greater the difficulty of adsorption. The more negative the value in the outgoing line, the greater the adhesion between the two, and the more firmly the carboxyl group adsorbed on the serpentine MgOH or SiO surface. At the same time, the significant difference in the outgoing line force curves of minerals with serpentine MgOH and serpentine SiO crystal faces indicates that the carboxyl functional group has good selectivity for serpentine SiO.

[0064] Example 2

[0065] Interactions between hydroxyl groups and different crystal planes of serpentine

[0066] (1) Cut into 8cm pieces 2 After UV cleaning for 30 minutes to remove surface contaminants, the gold sheets were immersed in a 3 mM 11-mercapto-1-undecanol ethanol solution for 12 hours, then rinsed three times with ethanol and deionized water, and dried with nitrogen gas to obtain the hydroxyl-modified gold sheet substrate, which was immediately used for interaction force measurement.

[0067] (2) About 10 μL of serpentine nanosheet suspension was added dropwise at 75°C and deposited on brucite and mica substrates, respectively. The functional groups on the substrates were combined with different crystal faces of the serpentine nanosheets to expose a single crystal face. The nanosheets were dried within 5 min and then rinsed with deionized water at pH ≈ 6.5 and ultrasonically treated for 2 min to remove loosely adsorbed serpentine particles. Serpentine MgOH face and SiO face were prepared, respectively.

[0068] (3) Use a surgical blade to cut the 3 μm thick PVD back-coated silver mica sheet into 8 cm 2 Then, UV-curable glue was used to glue the gold sheet and the cylindrical silicon disk with a nominal curvature radius of R = 2 cm. The two cylindrical silicon dioxide disks were installed in the SFA clean room in a cross-distribution on the vertical projection plane, corresponding to the plane of the sphere with a radius of R close to the Derjaguin approximation.

[0069] (4) In a dry argon environment, the unmodified gold substrate is driven to contact the surface of the mica substrate by a piezoelectric actuator, and the contact reference D = 0 is determined by the multi-beam interferometry method based on equal color fringe (FECO);

[0070] (5) The unmodified gold substrate was replaced with a hydroxyl-modified gold substrate, and the serpentine MgOH surface was adhered to the mica sheet. The SFA chamber was filled with a 10 mM NaCl test solution with a pH of 8.5 (filtered with a 0.22 μm filter before injection). The hydroxyl-modified gold substrate and the serpentine MgOH surface were driven to approach and move away from each other. The deflection of the supporting double cantilever spring was monitored in real time and converted into a function F(D) of the interaction force F and the separation distance D. The real-time separation distance D was determined by observing the interaction area through FECO fringes.

[0071] (6) Use the Derjaguin approximation method to convert the force signal F measured during the advance and retreat process into the unit area interaction energy between two planes to generate the advance force curve and the retreat force curve; Figure 4 and Figure 5 As shown, a negative value of the force F / R in the incoming line indicates that there is an attractive force between the hydroxyl group and the serpentine MgOH surface that promotes adsorption, a positive value indicates that there is a repulsive force that hinders the adsorption of functional groups, and a negative value of the force F / R in the outgoing line indicates that there is an adhesive force when the two are separated, and no negative force is detected, indicating that there is no adhesive force;

[0072] (7) Tear off the serpentine MgOH surface from the cylindrical silicon disk, replace it with the serpentine SiO surface, refill it with 10 mM NaCl test solution with a pH value of 8.5, repeat steps 5 to 6, and obtain the interaction curves between hydroxyl groups and the serpentine MgOH surface and SiO surface, as shown in Figure 4 and Figure 5As shown in the figure, the adsorption of hydroxyl groups on the MgOH surface and SiO surface of serpentine and the interaction mechanism were analyzed by comparing the unit area interaction energy of the incoming line and the outgoing line. The larger the negative value of F / R in the incoming line, the stronger the attraction between hydroxyl groups and the MgOH surface or SiO surface of serpentine, and the easier it is to adsorb the two. The larger the positive value, the stronger the repulsion between the two and the greater the difficulty of adsorption. The larger the negative value in the outgoing line, the greater the adhesion between the two and the more firmly hydroxyl groups are adsorbed on the MgOH surface or SiO surface of serpentine. At the same time, since the difference in the outgoing line force curves of minerals with serpentine MgOH surface and serpentine SiO surface crystal faces is small, it shows that the hydroxyl functional group has poor selectivity for serpentine crystal faces.

[0073] Example 3

[0074] Interactions between phosphate groups and different crystal faces of serpentine

[0075] (1) Cut into 8cm pieces 2 After UV cleaning for 30 minutes to remove surface contaminants, the gold sheets were immersed in a 3 mM 11-mercaptoundecylphosphoric acid ethanol solution for 12 hours. Subsequently, they were rinsed three times with ethanol and deionized water and dried with nitrogen gas to obtain the phosphate-modified gold sheet substrate, which was immediately used for interaction force measurement.

[0076] (2) About 10 μL of serpentine nanosheet suspension was added dropwise at 75°C and deposited on brucite and mica substrates, respectively. The functional groups on the substrates were combined with different crystal faces of the serpentine nanosheets to expose a single crystal face. The nanosheets were dried within 5 min and then rinsed with deionized water at pH ≈ 6.5 and ultrasonically treated for 2 min to remove loosely adsorbed serpentine particles. Serpentine MgOH face and SiO face were prepared, respectively.

[0077] (3) Use a surgical blade to cut the 3 μm thick PVD back-coated silver mica sheet into 8 cm 2 Then, UV-curable glue was used to glue the gold sheet and the cylindrical silicon disk with a nominal curvature radius of R = 2 cm. The two cylindrical silicon dioxide disks were installed in the SFA clean room in a cross-distribution on the vertical projection plane, corresponding to the plane of the sphere with a radius of R close to the Derjaguin approximation.

[0078] (4) In a dry argon environment, the unmodified gold substrate is driven to contact the surface of the mica substrate by a piezoelectric actuator, and the contact reference D = 0 is determined by the multi-beam interferometry method based on equal color fringe (FECO);

[0079] (5) Replace the unmodified gold substrate with a phosphate-modified gold substrate, adhere the serpentine MgOH surface to the mica sheet, and fill the SFA chamber with a 10 mM NaCl test solution with a pH of 8.5 (filtered with a 0.22 μm filter before injection). Drive the phosphate-modified gold substrate and the serpentine MgOH surface to approach and move away from each other, monitor the deflection of the supporting double cantilever spring in real time, and convert it into a function of the interaction force F and the separation distance D (F(D)). The real-time separation distance D is determined by observing the interaction area through FECO fringes.

[0080] (6) Use the Derjaguin approximation method to convert the force signal F measured during the advance and retreat process into the unit area interaction energy between two planes to generate the advance force curve and the retreat force curve; Figure 6 and Figure 7 As shown, a negative value of the force F / R in the incoming line indicates that there is an attractive force between the phosphate group and the serpentine MgOH surface that promotes adsorption, a positive value indicates that there is a repulsive force that hinders the adsorption of the functional group, and a negative value of the force F / R in the outgoing line indicates that there is an adhesive force when the two are separated, and no negative force is detected, indicating that there is no adhesive force;

[0081] (7) Tear off the serpentine MgOH surface from the cylindrical silicon disk, replace it with the serpentine SiO surface, refill it with 10 mM NaCl test solution with a pH value of 8.5, repeat steps 5 to 6, and obtain the interaction curves between the phosphate group and the serpentine MgOH surface and SiO surface, as shown in Figure 6 and Figure 7 As shown in the figure, by comparing the unit area interaction energy of the incoming line and the outgoing line, the adsorption of phosphate groups on the MgOH surface and SiO surface of serpentine and the interaction mechanism are analyzed. The larger the negative value of F / R in the incoming line, the stronger the attraction between the phosphate group and the MgOH surface or SiO surface of serpentine, and the easier it is to adsorb the two. The larger the positive value, the stronger the repulsion between the two and the greater the difficulty of adsorption. The larger the negative value in the outgoing line, the greater the adhesion between the two and the more firmly the phosphate group adsorbed on the MgOH surface or SiO surface of serpentine. At the same time, the large difference in the outgoing line force curves of minerals with serpentine MgOH surface and serpentine SiO surface crystal faces indicates that the phosphate functional group has good selectivity for serpentine SiO surface.

[0082] Example 4

[0083] The difference between this embodiment and embodiment 1 is that the pH value of the test solution injected into the SFA chamber is changed to 5.5, and the other conditions and steps are the same.

[0084] Example 5

[0085] The difference between this embodiment and embodiment 2 is that the pH value of the test solution injected into the SFA chamber is changed to 5.5, and the other conditions and steps are the same.

[0086] Example 6

[0087] The difference between this example and Example 3 is that the pH of the test solution injected into the SFA chamber is changed to 5.5, and the rest of the conditions and steps are consistent.

[0088] From Examples 4-6, it can be seen that the method of the present application can be applied to test solutions with different pH values, and can simulate the adsorption principle under different flotation environments.

[0089] Example 7

[0090] The difference between this example and Example 1 is that the serpentine SiO and MgOH faces are changed to rutile 110 and 011 faces, respectively, and the rest of the conditions and steps are consistent.

[0091] The rutile 110 and 011 faces of this example are obtained by the following preparation method: the rutile is crushed and sieved (through 600 mesh), and after grinding, rutile powder with a particle size of -3 μm is obtained;

[0092] Take 0.15 g of rutile powder and mix with 60 mL of 0.5 M hydrofluoric acid, then load into a hydrothermal reaction kettle, and hydrothermal reaction at 180°C for 12h; the product is centrifuged at a speed of 3000 rpm for 15 min, washed with deionized water and ethanol, and dried with gentle nitrogen blowing, and calcined at 500°C for 3h, to obtain rutile 110 face.

[0093] Take 0.15 g of rutile powder and mix with 60 mL of 0.5 M nitric acid, then load into a hydrothermal reaction kettle, and hydrothermal reaction at 180°C for 12h; the product is centrifuged at a speed of 3000 rpm for 15 min, washed with deionized water and ethanol, and dried with gentle nitrogen blowing, and calcined at 500°C for 3h, to obtain rutile 011 face.

[0094] Comparative Example 1

[0095] The difference between this example and Example 1 is only that the UV curing glue is changed to ordinary double-sided tape, and the rest of the steps and conditions are consistent.

[0096] From Figure 16 and Figure 17 It can be seen that when the glue is changed, the fluctuations of the incoming and outgoing lines are large, and the fitting error is large.

[0097] Lizardite nanosheets and rutile can be replaced by the following minerals: antigorite, chrysotile, orthoserpentine, anatase, pyrrhotite, chalcopyrite, galena, sphalerite, and stibnite; this method can be expanded and applied to quartz, calcite, fluorite, wolframite, dolomite, spodumene, silicon substrates, gold flakes, glass substrates, graphite substrates, polydimethylsiloxane, polyethylene, and polypropylene. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention can be made, and these simple variations all fall within the scope of protection of the present invention.

Claims

1. A method for screening functional groups of flotation modifier molecules based on mineral crystal anisotropy, characterized by: The following steps are involved: 1) placing the gold sheet substrate in a solution containing a functional group of a modifier molecule for immersion modification to obtain a gold sheet substrate modified with a single functional group of the modifier molecule; 2) After depositing the mineral suspensions with crystal face anisotropy on the corresponding substrates, loosely adsorbed mineral particles are removed by water washing to obtain different coating surfaces with exposed single mineral crystal faces; 3) Adhere an unmodified gold substrate and an adsorbed substrate to two cylindrical silica disks with a nominal curvature radius R in the SFA chamber using UV-curable adhesive. The unmodified gold substrate is located above the adsorbed substrate, and the two cylindrical silica disks are arranged in a cross-shaped pattern on a vertical projection plane, corresponding to a plane close to the Derjaguin approximation of a sphere with a radius of R. 4) In a protective atmosphere, the piezoelectric actuator of the SFA is controlled to drive the unmodified gold substrate into contact with the adsorption substrate, and the contact reference D = 0 is determined using a multi-beam interferometry method based on isochromatic fringes; 5) The unmodified gold substrate is replaced with a gold substrate modified with a single modifier molecule functional group, and the coating surface exposing a single mineral crystal face is adhered to the adsorption substrate. The test solution is injected into the SFA chamber, and the piezoelectric actuator is controlled to control the advance and retreat of the gold substrate modified with a single modifier molecule functional group and the adsorption substrate of the coating surface exposing a single mineral crystal face. The deflection of the supporting dual cantilever spring is monitored in real time and converted into a function F(D) of the interaction force F and the separation distance D. The real-time separation distance D is determined by observing the interaction area using FECO fringes. The advance line represents the process of the gold substrate modified with a single modifier molecule functional group and the adsorption substrate of the coating surface exposing a single mineral crystal face approaching each other, and the retreat line represents the process of the gold substrate modified with a single modifier molecule functional group and the adsorption substrate of the coating surface exposing a single mineral crystal face moving away from each other. 6) The force signal F measured during the feeding and withdrawal process is converted into the unit area interaction energy between two planes using the Derjaguin approximation method to generate the feeding force curve and the withdrawal force curve; a negative value of the force F / R during the feeding process indicates that there is an attractive force between the functional groups of the flotation modifier molecules and the mineral crystal surface that promotes adsorption, while a positive value indicates that there is a repulsive force that hinders the adsorption of the functional groups. A negative value of the force F / R during the withdrawal process indicates that there is an adhesive force when the two are separated, and no negative force is detected, indicating that there is no adhesive force; 7) replacing a different coating surface with a single exposed mineral crystal face and adhering it to an adsorption substrate, repeating steps 5-6, and obtaining the line-entry force curves and the line-retraction force curves of the modifier molecular functional groups and different mineral crystal faces; analyzing the adsorption of the flotation modifier molecular functional groups on the mineral crystal faces and the interaction mechanism by comparing the unit area interaction energy of the line-entry and line-retraction; 8) Changing the type of flotation adjuster molecular functional group, repeating steps 5 to 7, obtaining the line-in force curves and line-out force curves of the coating surface with different adjuster molecular functional groups and different exposed single mineral crystal faces, and comparing the values ​​of all the line-in force curves. The larger the negative value of F / R in the line-out force, the greater the adhesion between the two. The greater the adhesion force, the better the adsorption effect of the adjuster molecular functional group.

2. The method for screening functional groups of flotation modifier molecules based on mineral crystal anisotropy according to claim 1, characterized in that: By comparing the difference between the delinear force curves of the regulator molecular functional group and different crystal faces of the mineral in step 7, the selectivity of the regulator molecular functional group for the mineral crystal face can be determined. The greater the difference in the delinear force curves of different crystal faces of the mineral, the better the selectivity of the regulator molecular functional group for the mineral crystal face.

3. The method for screening functional groups of flotation modifier molecules based on mineral crystal anisotropy according to claim 1 or 2, characterized in that: The basis for judging the adsorption condition and interaction mechanism of the flotation adjuster molecular functional groups on the mineral crystal surface is as follows: the larger the negative value of F / R in the line-in force curve, the stronger the attraction between the flotation adjuster molecular functional groups and the mineral surface, and the easier it is for the two to adsorb; the larger the positive value, the stronger the repulsion between the two, and the greater the difficulty of adsorption; the larger the negative value in the line-out force curve, the greater the adhesion between the two, and the more firmly the flotation adjuster molecular functional groups are adsorbed on the mineral crystal surface.

4. The method for screening functional groups of flotation modifier molecules based on mineral crystal anisotropy according to claim 3, characterized in that: When changing the type of the functional group of the flotation adjuster molecule in step 8, only the functional group of the adjuster is changed, and the rest of the molecular structure should remain the same.

5. The method for screening functional groups of flotation modifier molecules based on mineral crystal anisotropy according to claim 1, characterized in that: In step 5, the test solution is a NaCl solution with a pH of 5.5 or 8.

5.

6. The method for screening functional groups of flotation modifier molecules based on mineral crystal anisotropy according to claim 5, characterized in that: Each time the gold sheet substrate modified with a single adjuster molecule functional group and the coating surface adsorption substrate exposing a single mineral crystal face are replaced, the test solution must be re-injected into the chamber, and the concentration and pH value of the test solution should be kept consistent.

7. The method for screening functional groups of flotation modifier molecules based on mineral crystal anisotropy according to claim 1, characterized in that: In step 2, the preparation process of the mineral suspension with crystal face anisotropy is as follows: crushing and screening the mineral, grinding the mineral to obtain mineral powder, dissolving it in a solvent and subjecting it to ultrasonic treatment.

8. The method for screening functional groups of flotation modifier molecules based on mineral crystal anisotropy according to claim 7, characterized in that: The mineral comprises one of serpentine, rutile, anatase, pyrrhotite, chalcopyrite, galena, sphalerite, stibnite, quartz, calcite, fluorite, wolframite, dolomite and spodumene; The adsorption substrate includes one of a mica sheet, a glass sheet substrate, a graphite substrate, polydimethylsiloxane, polyethylene and polypropylene.

9. A method for screening functional groups of flotation modifier molecules based on mineral crystal anisotropy according to any one of claims 4 to 8, characterized in that: The incoming force curve data were fitted based on the EDLVO theoretical model to determine the contribution rates of van der Waals force, electrostatic force and hydrophobic force to the interaction; the outgoing force curve data were fitted with a normal distribution to obtain the typical adhesion force between the functional groups and the mineral crystal surfaces, and to analyze the mechanical mechanism of the adsorption process of the functional groups of the flotation adjuster molecules on the mineral crystal surfaces.

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