Flotation regulator molecular functional group screening method based on mineral crystal face anisotropy

Abstract

The invention discloses a flotation regulator screening method based on anisotropy of a mineral crystal face, which comprises the following steps of: controlling a piezoelectric driver of an SFA (surface force instrument) to control a gold sheet substrate modified by a single regulator molecule functional group and a coating surface adsorption substrate exposing a single mineral crystal face to enter and exit a line; the method combines an EDLVO theoretical model to research the nano-scale interaction force between the molecular functional group of the flotation regulator and the crystal face of the mineral, realizes the visualization of the absolute distance, greatly reduces the theoretical fitting error, screens out the molecular functional group of the regulator with the strongest adhesive force and the strongest selectivity for the mineral with the anisotropy of the crystal face, and improves the accuracy of the flotation regulator. And the interaction force between the functional group of the regulator and the mineral crystal face can be accurately analyzed, the micromechanical mechanism in the adsorption process of the regulator is disclosed, and the optimization of the molecular structure of the regulator is scientifically guided.

Description

Technical Field

[0001] The invention relates to a method for screening molecular functional groups of a flotation regulator based on mineral crystal face anisotropy, and belongs to the field of mineral processing flotation reagent design. Background Art

[0002] Froth flotation is an efficient mineral processing technology widely used in the field of mineral processing. In the flotation process, modifiers, as an important type of flotation reagents, selectively adsorb on specific crystal faces of minerals to regulate their surface physical and chemical properties, thereby optimizing the final mineral processing effect. However, for some minerals, the addition of modifiers usually 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 modifiers and minerals. It can be seen that the anisotropic interfacial interaction between modifiers and specific crystal faces of minerals is a key factor in determining the flotation separation efficiency. However, it is still challenging to accurately and reliably characterize the anisotropy of mineral surfaces. In addition, the development of existing modifiers mainly relies on experience and qualitative analysis, and the interaction mechanism between their molecular structure and specific crystal faces is still unclear. This further leads to the unclear effect of the molecular structure of modifiers on the floatability of specific crystal faces of minerals, making it difficult to scientifically guide the design and development of new modifiers, limiting the optimization of flotation processes and the efficient separation of complex ores.

[0003] In common ore slurry environments, the interactions between modifier molecules and mineral crystal faces mainly include van der Waals forces, electrostatic forces, hydrophobic forces, and coordination effects. Currently, there is a lack of experimental methods that can directly quantify the interaction forces between modifier functional groups and mineral crystal faces, and the development of relevant technologies is urgent. Atomic force microscopy (AFM) and surface force instrument (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 is unable to simultaneously monitor the absolute distance between the collector and the mineral surface, resulting in large errors in theoretical fitting, and the force measurement range is limited to piconewtons to nanonewtons, making it difficult to identify strong interactions. In contrast, SFA can visualize absolute distances, with a force measurement range from nanonewtons to micronewtons, and has more advantages in measuring stronger interactions. By chemically modifying the functional group molecules and mineral crystal faces of the target modifier to the corresponding matrix and fixing them on the cylindrical disk of the SFA system respectively, the interaction force between the functional group and the mineral crystal face can be accurately measured, revealing its micromechanical mechanism of action. This will help to develop modifier molecules with selective adsorption characteristics on specific mineral crystal faces, and provide important theoretical support for achieving efficient flotation separation of minerals. And the prior art lacks a method for selectively guiding the crystal faces of the functional groups of flotation modifier molecules for minerals with anisotropic crystal faces. Summary of the invention

[0005] In view of the limitations of existing screening methods such as large errors in theoretical fitting and lack of guidance on the selectivity of crystal face anisotropy, the purpose of the present invention is to provide a method for screening the functional groups of flotation modifier molecules based on the anisotropy of mineral crystal faces. Starting from the essence of molecular interface interaction, using SFA to accurately measure the interaction force relationship between the functional groups of modifier molecules and mineral crystal faces, not only can the modifier molecules with the best adhesion and high selectivity for anisotropic crystal faces be directly designed, but also the interaction force between the functional groups of modifiers and mineral crystal faces can be accurately analyzed and the micromechanical mechanism of the modifier adsorption process can be revealed, so as to scientifically guide the optimization of the modifier molecular structure.

[0006] In order to achieve the above technical objectives, the present invention provides a method for screening molecular functional groups of flotation regulators 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 regulator molecule for immersion modification to obtain a gold sheet substrate modified with a single functional group of the regulator 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 the unmodified gold substrate and the adsorption substrate to two cylindrical silica disks with a nominal curvature radius of R in the SFA chamber using UV-curable glue, respectively; wherein the unmodified gold substrate is located above the adsorption substrate, and the two cylindrical silica disks are cross-distributed on the vertical projection plane, and correspond to a plane close to the Derjaguin approximation of a sphere with a radius of R;

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

[0011] 5) replacing the unmodified gold substrate with a gold substrate modified with a single adjusting agent molecule functional group, and adhering the coating surface exposing a single mineral crystal face to the adsorption substrate, injecting the test solution into the chamber of the SFA, controlling the entry and exit of the gold substrate modified with a single adjusting agent molecule functional group and the coating surface adsorption substrate exposing a single mineral crystal face by controlling the piezoelectric actuator, monitoring the deflection of the supporting double cantilever spring in real time, and converting it into a function F(D) of the interaction force F and the separation distance D, and the real-time separation distance D is determined by observing the interaction area through FECO fringes; wherein, the entry line represents the process of the gold substrate modified with a single adjusting agent molecule functional group and the coating surface adsorption substrate exposing a single mineral crystal face approaching each other, and the exit line represents the process of the gold substrate modified with a single adjusting agent molecule functional group and the coating surface adsorption substrate exposing a single mineral crystal face moving away from each other;

[0012] 6) The force signal F measured during the process of feeding and withdrawing is converted into the unit area interaction energy between two planes using the Derjaguin approximation method to generate the feeding force curve and the withdrawing force curve; a negative value of the force F / R in the feeding process indicates that there is an attractive force between the functional groups of the flotation adjuster molecules and the mineral crystal planes that promotes adsorption, and 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 in the withdrawing process indicates that there is an adhesion force when the two are separated, and no negative force is detected, indicating that there is no adhesion force;

[0013] 7) Replace the coating surface with different exposed single mineral crystal faces and adhere it to the adsorption substrate, repeat steps 5 to 6, and obtain the line-in force curve and the line-out force curve of the molecular functional group of the adjuster and the different crystal faces of the mineral; analyze the adsorption of the molecular functional group of the flotation adjuster on the mineral crystal face and the interaction mechanism by comparing the unit area interaction energy of the line-in and the line-out;

[0014] 8) Change the type of flotation adjuster molecular functional group, repeat steps 5 to 7, obtain the in-line force curves and out-line force curves of the coating surface with different adjuster molecular functional groups and different exposed single mineral crystal faces, and compare all the in-line curve values. The larger the negative value of F / R in the out-line, the greater the adhesion between the two, and the greater the adhesion, the better the adsorption effect of the adjuster molecular functional group.

[0015] The core of the technical solution of the present invention is to control the gold sheet substrate modified with a single modifier molecule functional group and the coating surface adsorbing the substrate exposed with a single mineral crystal face by controlling the piezoelectric driver of the SFA (surface force instrument), study the nano-level interaction force between the flotation modifier molecule functional group and the mineral crystal face, realize the visualization of the absolute distance, greatly reduce the theoretical fitting error, and screen out the modifier molecule functional group with the strongest adhesion and the strongest selectivity for minerals with crystal face anisotropy. The specific principle is as follows: first, the gold sheet substrate is immersed in a solution containing the modifier molecule functional group to modify the surface with a single functional group. At the same time, a mineral suspension with crystal face anisotropy is deposited on the substrate to expose a single mineral crystal face; then the interaction force between the modified gold sheet substrate and the mineral crystal face is measured by SFA. By controlling the piezoelectric driver, the two are brought close or far away, the deflection of the supporting double cantilever spring is monitored in real time, and it is converted into a function of the interaction force and the separation distance. The measured force signal is then converted into the interaction energy per unit area using the Derjaguin approximation method to generate the line of approach and line of retreat force curves. The in-line force curve reflects the adsorption between the functional groups of the regulator molecule and the mineral crystal surface, and the out-line force curve reflects the adhesion force during separation. Finally, by changing different mineral crystal surfaces and functional groups of regulator molecules, repeatedly measuring and comparing the in-line and out-line force curves, the functional groups of regulator molecules with the best adsorption effect can be screened out.

[0016] In the present invention, the two cylindrical silicon dioxide disks are cross-distributed on the vertical projection plane and the setting corresponding to a sphere with a radius R close to the Derjaguin approximate plane is also critical. This setting can maximize the reduction of the fitting error.

[0017] As a preferred scheme, 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 molecular functional groups of the flotation adjusting agent on the mineral crystal surface are judged based on the following: the larger the negative value of F / R in the in-line force curve, the stronger the attraction between the molecular functional groups of the flotation adjusting agent 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 back-line force curve, the greater the adhesion between the two, and the more firmly the molecular functional groups of the flotation adjusting agent are adsorbed on the mineral crystal surface.

[0019] As a preferred solution, 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 (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 capped 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 mainly simulates a common ore pulp ion strength environment to weaken the influence of a small amount of impurity ions in the solution. When the selected minerals are different, the pH value of the test solution can be adjusted according to the actual flotation situation.

[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, and the test solution needs to be filtered with a 0.22μm filter head before injection.

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

[0024] As a preferred solution, the mineral includes one of serpentine, rutile, anatase, pyrrhotite, chalcopyrite, galena, sphalerite, stibnite, quartz, calcite, fluorite, wolframite, dolomite and spodumene; the adsorption substrate includes one of mica flakes, glass flake substrates, graphite substrates, polydimethylsiloxane, polyethylene and polypropylene. Among them, serpentine includes one of antigorite, chrysotile, orthoserpentine and lizardite nanosheets. The adsorption substrate used in the present invention can also include conventional non-metallic substrates or polymer material substrates in the prior 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 by FECO fringes during the force measurement process, and the ease of adsorption between the molecular functional groups of the regulator and the mineral crystal faces is analyzed in combination with the EDLVO theoretical model.

[0026] As a preferred solution, the in-line force curve data is fitted based on the EDLVO theoretical model to determine the contribution of van der Waals force, electrostatic force and hydrophobic force to the interaction; the back-line force curve data is fitted with a normal distribution to obtain the typical adhesion force between the functional group and the mineral crystal surface, and to analyze the mechanical mechanism of the adsorption process of the functional group of the flotation modifier molecule on the mineral crystal surface. The above operation can provide guidance for the optimal design of the functional group of the flotation modifier molecule.

[0027] As a preferred solution, 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 solution, when the adsorption substrate used is a mica sheet, the freshly peeled mica sheet is manually cut to provide a 5-10 cm 2 The samples were prepared with an area of ​​100 μm and a uniform thickness of 2 to 5 μm and immediately glued onto a cylindrical silica disk for force measurement to prevent surface contamination.

[0029] Compared with the prior art, the beneficial technical effects brought by the present invention are as follows:

[0030] 1) The present invention 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 adjuster molecules based on experience, the method for screening functional groups of flotation adjuster molecules provided by the present invention can directly screen out the adjuster with the best adhesion by comparing the interaction forces between different adjuster molecules and mineral crystal surfaces, quickly evaluate the performance of different functional groups, reduce blind reliance on experience-based design experiments and corresponding raw material losses, and improve design efficiency.

[0032] 3) The two substrates of the method for screening the functional groups of flotation adjuster molecules provided by the present invention adopt a cross-cylindrical geometric structure (approximately a sphere-plane model), which ensures the large-scale uniformity of the contact area and the high precision of the force measurement, and avoids the errors caused by the surface non-uniformity and the local effect of the AFM tip in the traditional method.

[0033] 4) Compared with AFM which relies on displacement sensors to indirectly estimate the relative separation distance, the molecular functional group design method of the flotation adjuster provided by the present invention directly measures the absolute separation distance D through multi-beam interferometry technology (FECO), with a resolution of sub-nanometer level (<0.1nm), and can also provide additional information such as surface morphology and thickness change, and can provide a more accurate force-distance curve to ensure the accuracy of the screening results.

[0034] 5) Compared with the traditional characterization limited to vacuum or dry conditions, the molecular functional group screening method of the flotation adjuster provided by the present invention can directly regulate the solution composition, temperature, pH value, etc. in the liquid phase, simulate the actual slurry conditions, and quantify the interaction force between the adjuster molecules and the mineral crystal surface in situ, so as to ensure that the screened adjuster has more practical application value.

[0035] 6) The present invention can accurately analyze the interaction force between the functional groups of the regulator and the mineral crystal faces and reveal the micromechanical mechanism in the regulator adsorption process, scientifically guide the optimization of the molecular structure of the regulator, and for minerals with crystal face anisotropy, it can also screen out the regulator molecular functional groups with the highest selectivity for the mineral crystal faces by comparing the differences in the incoming force curves and the outgoing 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 being cross-distributed on a vertical projection plane.

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

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

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

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

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

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

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

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

[0049] Fig.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 in Example 7 of the present invention.

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

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

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

[0053] In order to further understand the present invention, the interaction between different crystal faces of serpentine and reagent molecules during flotation is taken as an example to explain the present invention in detail through specific implementation methods, so as to help technical workers in related fields better understand the concept and technical solution of the present invention, but it is not limited to the following embodiments.

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

[0055] Example 1

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

[0057] (1) Cut into 8 cm pieces 2 The gold substrates of different sizes were UV-cleaned for 30 min to remove surface contaminants, then immersed in a 3 mM 11-mercaptoundecanoic acid ethanol solution for 12 h, then rinsed three times with ethanol and deionized water, and dried with nitrogen to obtain the carboxyl-modified gold substrates, which were immediately used for interaction force measurement.

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

[0059] (3) Use a surgical blade to cut the 3 μm thick PVD back-silvered mica substrate into 8 cm 2 The small pieces were then glued to the cylindrical silicon disk with a nominal radius of curvature R = 2 cm with a UV-curing glue and the gold sheet substrate, and 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 by a piezoelectric actuator to contact the surface of the mica substrate, and the contact reference D=0 is determined by a multi-beam interferometry method based on equal color fringe (FECO);

[0061] (5) Replace the unmodified gold substrate with a carboxyl-modified gold substrate, stick the serpentine MgOH surface on the mica substrate, fill the SFA chamber with a 10 mM NaCl test solution with a pH value of 8.5 (filtered with a 0.22 μm filter before injection), drive the carboxyl-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 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 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 the 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 the carboxyl group and the serpentine MgOH surface and SiO surface, as shown in Figure 2 and Figure 3 As shown in the figure, by comparing the unit area interaction energy of the incoming line and the outgoing line, the adsorption of carboxyl on the serpentine MgOH surface and SiO surface and the interaction mechanism are analyzed. The larger the negative value of F / R in the incoming line, the stronger the attraction between the carboxyl and the serpentine MgOH surface or SiO 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 outgoing line, the greater the adhesion between the two, and the more firmly the carboxyl is adsorbed on the serpentine MgOH surface or SiO surface. At the same time, due to the large difference in the outgoing line force curves of the serpentine MgOH surface and the serpentine SiO surface crystal surface minerals, it shows that the carboxyl functional group has good selectivity for the serpentine SiO surface.

[0064] Example 2

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

[0066] (1) Cut into 8 cm pieces 2 After the gold sheets of different sizes were UV-cleaned for 30 min to remove surface contaminants, they were immersed in a 3 mM 11-mercapto-1-undecanol ethanol solution for 12 h, 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, and a single crystal face was exposed by combining the functional groups on the substrate with different crystal faces of the serpentine nanosheets. The serpentine nanosheets were dried within 5 min, and then rinsed with deionized water at pH ≈ 6.5 and ultrasonically treated for 2 min to remove the loosely adsorbed serpentine particles, thereby preparing serpentine MgOH face and SiO face, respectively.

[0068] (3) Use a surgical blade to cut the 3 μm thick PVD back-silvered mica sheet into 8 cm 2 The small pieces were then glued to the cylindrical silicon disk with a nominal radius of curvature R = 2 cm with a UV-curing glue and the gold sheet substrate, and 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 by a piezoelectric actuator to contact the surface of the mica substrate, and the contact reference D=0 is determined by a multi-beam interferometry method based on equal color fringe (FECO);

[0070] (5) Replace the unmodified gold substrate with a hydroxyl-modified gold substrate, stick the serpentine MgOH surface on the mica sheet, fill the SFA chamber with a 10 mM NaCl test solution with a pH value of 8.5 (filtered with a 0.22 μm filter before injection), drive the hydroxyl-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 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 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 the 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, 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, by comparing the unit area interaction energy of the incoming line and the outgoing line, the adsorption of hydroxyl on the serpentine MgOH surface and SiO surface and the interaction mechanism are analyzed. The larger the negative value of F / R in the incoming line, the stronger the attraction between hydroxyl and the serpentine MgOH surface or SiO 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 outgoing line, the greater the adhesion between the two, and the more firmly the hydroxyl is adsorbed on the serpentine MgOH surface or SiO surface. At the same time, since the difference in the outgoing line force curves of the serpentine MgOH surface and the serpentine SiO surface crystal surface minerals is small, it shows that the hydroxyl functional group has poor selectivity for the serpentine crystal surface.

[0073] Example 3

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

[0075] (1) Cut into 8 cm pieces 2 After the gold sheets of different sizes were UV-cleaned for 30 min to remove surface contaminants, they were immersed in a 3 mM 11-mercaptoundecylphosphoric acid ethanol solution for 12 h, then rinsed three times with ethanol and deionized water and dried with nitrogen gas to obtain a gold sheet substrate modified with phosphate groups, 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, and a single crystal face was exposed by combining the functional groups on the substrate with different crystal faces of the serpentine nanosheets. The serpentine nanosheets were dried within 5 min, and then rinsed with deionized water at pH ≈ 6.5 and ultrasonically treated for 2 min to remove the loosely adsorbed serpentine particles, thereby preparing serpentine MgOH face and SiO face, respectively.

[0077] (3) Use a surgical blade to cut the 3 μm thick PVD back-silvered mica sheet into 8 cm 2 The small pieces were then glued to the cylindrical silicon disk with a nominal radius of curvature R = 2 cm with a UV-curing glue and the gold sheet substrate, and 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 by a piezoelectric actuator to contact the surface of the mica substrate, and the contact reference D=0 is determined by a multi-beam interferometry method based on equal color fringe (FECO);

[0079] (5) Replace the unmodified gold substrate with a phosphate-modified gold substrate, stick the serpentine MgOH surface onto the mica sheet, fill the SFA chamber with a 10 mM NaCl test solution with a pH value 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 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 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 the 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, 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 serpentine MgOH surface and SiO surface 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 serpentine MgOH surface or SiO 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 outgoing line, the greater the adhesion between the two, and the more firmly the phosphate group is adsorbed on the serpentine MgOH surface or SiO surface. At the same time, due to the large difference in the outgoing line force curves of the serpentine MgOH surface and the serpentine SiO surface crystal surface minerals, it shows that the phosphate functional group has good selectivity for the 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 embodiment and embodiment 3 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.

[0088] Examples 4 to 6 illustrate that the method of the present invention is applicable to test solutions of different pH values ​​and can simulate and reveal the adsorption principle under different flotation environments.

[0089] Example 7

[0090] The present embodiment differs from the first embodiment in that the serpentine SiO and MgOH planes are respectively changed to the rutile 110 crystal plane and 011 crystal plane, and the other conditions and steps are the same.

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

[0092] 0.15 g of rutile powder was mixed with 60 mL of 0.5 M hydrofluoric acid and loaded into a hydrothermal reactor for hydrothermal reaction at 180°C for 12 h. The product was centrifuged at 3000 rpm for 15 min, washed with deionized water and ethanol and dried with mild nitrogen, and calcined at 500°C for 3 h to obtain the rutile 110 crystal face.

[0093] 0.15 g of rutile powder was mixed with 60 mL of 0.5 M nitric acid and loaded into a hydrothermal reactor for hydrothermal reaction at 180°C for 12 h; the product was centrifuged at 3000 rpm for 15 min, washed with deionized water and ethanol and dried with mild nitrogen, and calcined at 500°C for 3 h to obtain the rutile 011 crystal face.

[0094] Comparative Example 1

[0095] The difference between this comparative example and Example 1 is that the UV curing glue is changed to ordinary double-sided adhesive, and the other steps and conditions are the same.

[0096] Depend on Fig.16 and Fig.17 It can be seen that after the glue is replaced, the fluctuations of the incoming and outgoing lines are relatively large, and the fitting error becomes larger.

[0097] Among them, lizardite nanosheets and rutile can be replaced by the following minerals: antigorite, chrysotile, orthoserpentine, anatase, pyrrhotite, chalcopyrite, galena, sphalerite and stibnite, etc.; this method can be extended and applied to quartz, calcite, fluorite, wolframite, dolomite, spodumene, silicon substrate, gold sheet, glass sheet substrate, graphite substrate, polydimethylsiloxane, polyethylene and polypropylene, etc. Within the technical concept of the present invention, the technical scheme of the present invention can be subjected to a variety of simple modifications, and these simple modifications all belong to the protection scope of the present invention.

Claims

1. A method for screening molecular functional groups of flotation regulators based on mineral crystal anisotropy, characterized in that: The following steps are involved: 1) placing the gold sheet substrate in a solution containing a functional group of a regulator molecule for immersion modification to obtain a gold sheet substrate modified with a single functional group of the regulator 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 the unmodified gold substrate and the adsorption substrate to two cylindrical silica disks with a nominal curvature radius of R in the SFA chamber using UV-curable glue, respectively; wherein the unmodified gold substrate is located above the adsorption substrate, and the two cylindrical silica disks are cross-distributed on the vertical projection plane, and correspond to a plane close to the Derjaguin approximation of a sphere with a radius of R; 4) In a protective atmosphere, the piezoelectric driver of the SFA is controlled to drive the unmodified gold substrate to contact the adsorption substrate, and the contact reference D=0 is determined by a multi-beam interferometry method based on equal-color fringes; 5) replacing the unmodified gold substrate with a gold substrate modified with a single adjusting agent molecule functional group, and adhering the coating surface exposing a single mineral crystal face to the adsorption substrate, injecting the test solution into the chamber of the SFA, controlling the entry and exit of the gold substrate modified with a single adjusting agent molecule functional group and the coating surface adsorption substrate exposing a single mineral crystal face by controlling the piezoelectric actuator, monitoring the deflection of the supporting double cantilever spring in real time, and converting it into a function F(D) of the interaction force F and the separation distance D, and the real-time separation distance D is determined by observing the interaction area through FECO fringes; wherein, the entry line represents the process of the gold substrate modified with a single adjusting agent molecule functional group and the coating surface adsorption substrate exposing a single mineral crystal face approaching each other, and the exit line represents the process of the gold substrate modified with a single adjusting agent molecule functional group and the coating surface adsorption substrate exposing a single mineral crystal face moving away from each other; 6) The force signal F measured during the process of feeding and withdrawing is converted into the unit area interaction energy between two planes using the Derjaguin approximation method to generate the feeding force curve and the withdrawing force curve; a negative value of the force F / R in the feeding process indicates that there is an attractive force between the functional groups of the flotation adjuster molecules and the mineral crystal planes that promotes adsorption, and 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 in the withdrawing process indicates that there is an adhesion force when the two are separated, and no negative force is detected, indicating that there is no adhesion force; 7) Replace the coating surface with different exposed single mineral crystal faces and adhere it to the adsorption substrate, repeat steps 5 to 6, and obtain the line-in force curve and the line-out force curve of the molecular functional group of the adjuster and the different crystal faces of the mineral; analyze the adsorption of the molecular functional group of the flotation adjuster on the mineral crystal face and the interaction mechanism by comparing the unit area interaction energy of the line-in and the line-out; 8) Change the type of flotation adjuster molecular functional group, repeat steps 5 to 7, obtain the in-line force curves and out-line force curves of the coating surface with different adjuster molecular functional groups and different exposed single mineral crystal faces, and compare all the in-line curve values. The larger the negative value of F / R in the out-line, the greater the adhesion between the two, and the greater the adhesion, the better the adsorption effect of the adjuster molecular functional group.

2. The method for screening molecular functional groups of flotation regulators 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. A method for screening functional groups of flotation regulator 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 molecular functional groups of the flotation adjusting agent on the mineral crystal surface is as follows: the larger the negative value of F / R in the in-line force curve, the stronger the attraction between the molecular functional groups of the flotation adjusting agent and the mineral surface, and the easier it is for the two to adsorb; the larger the positive value, the stronger the repulsive force between the two, and the greater the difficulty of adsorption; the larger the negative value in the out-line force curve, the greater the adhesion force between the two, and the more firmly the molecular functional groups of the flotation adjusting agent are adsorbed on the mineral crystal surface.

4. The method for screening molecular functional groups of flotation regulators based on mineral crystal anisotropy according to claim 3, characterized in that: When the type of the functional group of the flotation adjuster molecule is changed 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 molecular functional groups of flotation regulators 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 molecular functional groups of flotation regulators 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 needs to 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 regulator 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: 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 regulator 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 molecular functional groups of flotation regulators based on mineral crystal anisotropy according to any one of claims 4 to 8, characterized in that: The data of the incoming force curve 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 data of the outgoing force curve 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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