Method for flotation and enrichment of titanium / iron impurities in coal series kaolinite

Abstract

The invention discloses a method for flotation enrichment of titanium / iron impurities in coal series kaolinite, and relates to the technical field of purification / flotation separation of coal series kaolinite. According to the invention, a density functional theory is used as a guide, and molecular simulation software is used for screening a solid-loving group with a targeted adsorption effect on titanium / iron impurities; constructing a lattice type Ti / Fe doped kaolinite active site model, calculating and comparing the adsorption energy difference of a solid affinity group on a Ti / Fe site and an undoped kaolinite surface, screening a targeted functional group, and selecting a commercially available collecting agent according to the targeted functional group; according to the method, screening and magnetic separation pretreatment are combined to reduce interference, then reverse flotation is carried out, so that a kaolinite component with a high titanium / iron impurity ratio selectively floats in a hydrophobic mode under the action of a collecting agent, the kaolinite component which does not contain or only contains a small amount of Ti / Fe keeps hydrophilic and is left in a groove, and impurity removal and whitening of coal series kaolinite are achieved.

Description

Technical Field

[0001] This invention relates to the field of coal-based kaolinite purification / flotation separation technology, and more specifically to a method for flotation enrichment of titanium / iron impurities in coal-based kaolinite. Background Technology

[0002] Coal gangue, a major solid waste generated during coal mining in my country, possesses abundant resource potential, with coal-series kaolinite accounting for approximately 50%. However, my country currently remains highly dependent on imports for high-quality kaolinite. The core issue is the difficulty in effectively removing lattice-type titanium, iron, and other impurities from coal-series kaolinite using conventional single physical separation methods. Furthermore, existing technologies have revealed a series of pressing problems in practical applications:

[0003] First, the selection of flotation reagents lacks a scientific and systematic theoretical guidance, relying excessively on empirical trial and error. This traditional approach not only results in extremely low screening efficiency but also poor selectivity of the selected reagents, making the entire development process lengthy and consuming a large amount of manpower, material resources, and time.

[0004] Secondly, there are significant bottlenecks in the technology for removing lattice impurities. Existing physical methods are difficult to effectively separate lattice-type impurities such as titanium and iron in coal-based kaolinite, failing to meet the requirements for high-quality kaolinite purification and severely restricting the in-depth development and utilization of coal-based kaolinite.

[0005] Third, while chemical purification methods (such as acid leaching and roasting) can remove impurities to a certain extent, they also cause serious environmental pollution problems. These methods easily generate a large number of harmful substances during operation, causing secondary pollution, which runs counter to the current strict environmental protection requirements, thus greatly limiting the feasibility of their industrial application.

[0006] Therefore, developing a coal-based kaolinite purification technology that is mild, efficient, and environmentally friendly has become the key to breaking through the current industrial development bottleneck and realizing the high-value utilization of coal-based kaolinite resources in my country, and has broad application prospects. Summary of the Invention

[0007] In view of this, the present invention provides a method for flotation enrichment of titanium / iron impurities in coal-based kaolinite, in order to solve the problem that lattice-type impurities such as titanium and iron in coal-based kaolinite are difficult to remove gently, affecting the whiteness and utilization value of the product.

[0008] This invention, guided by density functional theory, utilizes molecular simulation software (Materials Studio) to screen for fixative groups that target the adsorption of titanium / iron impurities. A lattice-type Ti / Fe-doped kaolinite active site model is constructed, and the adsorption energy difference between the fixative groups at the "Ti / Fe site" and the "pure slab" is calculated and compared. Target functional groups are screened, and commercially available collectors are selected accordingly. Pre-treatment with sieving and magnetic separation is combined to reduce interference, followed by reverse flotation. This allows kaolinite components with a high proportion of titanium / iron impurities to selectively float hydrophobically under the action of the collector, while kaolinite components containing little or no Ti / Fe remain hydrophilic and in the tank, achieving the deimpurification and whitening of coal-based kaolinite.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: A method for the flotation enrichment of titanium / iron impurities in coal-series kaolinite is proposed. This method optimizes the selection of a suitable targeted collector based on the difference between the active sites of Ti / Fe impurities and the surface activity of kaolinite. The collector targets the active sites of Ti / Fe impurities for "site-to-site" adsorption, thereby enhancing the hydrophobicity of the Ti / Fe impurity particle surface. Finally, flotation is used to effectively remove Ti / Fe impurities from coal-series kaolinite. The method follows a route of "target site modeling—DFT screening of functional groups—collector mapping—process verification," specifically comprising the following three steps: S1. Preprocessing Coal-series kaolinite ore was screened and magnetically separated to remove gangue-type Ti / Fe minerals; S2. Molecular Simulation Screening (1) Construction of Kaolinite and Doping Model: Import kaolinite cells into Materials Studio to construct a surface model. A 2×2×1 supercell is used, and a vacuum layer is introduced to eliminate interlayer interactions. The following models are constructed respectively: A. Perfect bulk kaolinite surface model, i.e., undoped kaolinite surface model (pure slab); B. Lattice-type Ti / Fe doping model; (2) Construction of a library of sessile groups: Based on the functional groups of common collectors in mineral flotation, a library of sessile group fragments was constructed. Each sessile group was first subjected to individual geometric optimization to obtain the lowest energy configuration. (3) Adsorption configuration setting: The fixative group (2) is placed near the undoped kaolinite surface model and the Ti / Fe doped model site (1) respectively, and multiple initial adsorption orientations are set to avoid getting trapped in local minima; (4) CASTEP parameters and calculations: Geometric optimization and energy calculations are performed in the CASTEP Calculation module; (5) Adsorption energy and selectivity criterion: Calculate the adsorption energy; E ads =E surface adsorbate E surface E adsorbate in E surface adsorbate The total energy of the surface and reagent adsorption system. E surface The energy on the surface of kaolinite, E adsorbate The energy of the fixative group. E ads For adsorption energy, E ads The more negative the value, the stronger the adsorption. Define Selectivity Indicators E=E ads (doped) E ads (pure) when E<0 This indicates that the adsorption of this group at the Ti / Fe doping site is stronger than that on the undoped kaolinite surface; The more negative E (the larger the absolute value), the stronger the targeting. During screening, priority should be given to those with significantly negative E values. E adspure However, strong candidate groups were not selected, thus screening for targeted fixative groups that met the criteria of "stronger adsorption on the surface of Ti / Fe-doped kaolinite and weaker adsorption on the bulk kaolinite", and then... E and E ads (doped) Sort candidate fixophilic groups; (6) Collector mapping: Based on the screened target affinity groups, commercially available collectors or combinations thereof containing such functional groups are preferentially selected to form a reagent scheme that can be directly used for reverse flotation, providing a clear basis for reagent selection for subsequent experiments; S3. Flotation test Commercially available collectors with site selectivity were screened based on adsorption energy differences. Reverse flotation tests were conducted, and the collectors preferentially adsorbed onto lattice-type Ti / Fe substitution sites, enhancing the surface hydrophobicity of this type of kaolinite component. This allowed kaolinite components with a high proportion of titanium / iron impurities to selectively float hydrophobically, while kaolinite components without or containing only a small amount of Ti / Fe remained hydrophilic and stayed in the tank. The composition was analyzed by XRF and ICP-MS to evaluate the impurity removal rate and product whiteness.

[0010] Preferably, in step S1, the sieving process removes coarse particles >0.5 mm; the magnetic separation involves cycling 5 times under a magnetic field strength of 0.25 T to remove strongly magnetic iron minerals.

[0011] Preferably, the doping method of the B. lattice-type Ti / Fe doping model is: using Ti 4+ / Fe 2+ / Fe 3+ Al as an alternative to aluminum oxide surfaces 3+ and Si on the silicon-oxygen surface 4+ (Using the Modify Element tool); For the net charge imbalance caused by heterovalent substitution, by introducing Na + / H + / Cl - Charge compensation can be achieved by setting oxygen vacancies or ortho-substitution (preferably by introducing Na). + / Cl - To achieve electrical neutrality, a stable surface structure that represents the active sites of lattice-type impurities is obtained.

[0012] Preferably, the mineral in step (2) includes kaolinite; the fixative fragment library includes at least one or more of the following groups: carboxylates, hydroxamic acid salts, phosphates (phosphine) salts, and sulfonates.

[0013] Preferably, the parameters for geometric optimization in step (4) include: the exchange-correlation functional is the PBE functional in GGA; the pseudopotential is an ultrasoft pseudopotential; the plane wave cutoff energy is set to Fine accuracy; the k-point is a 1×1×1 Gamma point; and the SCF convergence threshold is approximately 1.8-2.2×10⁻⁶. -6 eV / atom; energy / force / displacement convergence values ​​are 0.8-1.2×10⁻⁶ respectively. -5 eV / atom, 0.02-0.04 eV / Å, 0.001 Å; for Fe-doped models, spin polarization calculations can be used; DFT-D dispersion corrections such as TS can be introduced if necessary. Specific parameters are set as preferred in the table below:

[0014] Preferably, the collector mapping rule in step (6) includes: ① Among commercially available drugs, priority should be given to selecting series with "same target functional group + different hydrophobic chain length / branching degree" as candidates in order to construct structure-activity comparison; ② When multiple candidates exist, the one with the most priority is selected. E is more negative and E ads (pure) The weaker ones; ③ If a single collector cannot achieve both selectivity and foaming performance, it can be combined with conventional foaming agents or inhibitors, and the final reagent system can be determined by flotation indicators, including Ti / Fe recovery rate and enrichment ratio.

[0015] As can be seen from the above technical solution, compared with the prior art, the present invention has the following technical effects: (1) A deep whitening technology for coal-series kaolinite was developed to improve the whiteness of the product.

[0016] (2) Realize the cascade utilization of coal-series kaolinite resources and reduce the waste of coal-series solid waste resources.

[0017] (3) It alleviates the environmental problems caused by coal mining and processing, and promotes the resource utilization of bulk solid waste such as coal gangue, which is conducive to the sustainable development of mineral resource utilization in my country. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0019] Figure 1 Schematic diagrams of different kaolinite models; Figure 2 Schematic diagram of the fixophilic group; Figure 3 A schematic diagram of the optimized fixophilic group; Figure 4 This is a schematic diagram of the pretreatment + reverse flotation process; Figure 5 The adsorption energies of different fixophilic groups on the (001) surface of Fe-doped kaolinite in a lattice; Figure 6 The adsorption energies of different fixophilic groups on the (001) surface of Fe-doped kaolinite in a lattice; Figure 7 The Fe2O3 content of the floating matter is given under four different collector conditions. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] In a specific embodiment of the present invention, the following method is followed: This embodiment is used to verify that: coal-series kaolinite ore usually contains a small amount of independent gangue minerals (such as hematite, ilmenite, rutile, etc.). This invention pre-treats the ore before reverse flotation by screening and weak magnetic separation to preferentially remove visible independent mineral particles. The reverse flotation stage targets lattice-type titanium / iron impurities that remain tightly bound to kaolinite after magnetic separation. The process involves allowing the kaolinite component with a high proportion of titanium / iron impurities to selectively float hydrophobically under the action of a collector, while the kaolinite containing no or only a small amount of titanium / iron impurities remains hydrophilic in the tank, thus obtaining a low-impurity, high-quality kaolinite product.

[0022] Technical route: Raw ore (<0.5 mm) → 0.25T magnetic separation (5 cycles) → Obtain “magnetic pretreatment sample + magnetic tailings (strong magnetic products)” → Perform reverse flotation on “magnetic pretreatment sample” → froth product (enriching impurities) & tailings in the tank (enriching kaolinite) → XRF / ICP-MS composition analysis → Calculate recovery rate / enrichment ratio → Optimize the dosage of collector and frother.

[0023] Specifically, the following steps are included: Preprocessing: 1. Pass the raw ore through a 0.5 mm sieve to remove large particles; record the yield. The experimental sample is further crushed and ground to -0.074 mm (200 mesh) and mixed thoroughly.

[0024] 2. Magnetic Separation Process: Five cycles of magnetic separation are performed under a magnetic field strength of 0.25 T. The feed is added slowly and evenly, maintaining a thin layer. Each magnetic separation cycle collects magnetic products (magnetic tailings, enriched with strongly magnetic Fe minerals) and non-magnetic products (pre-treated samples, mainly kaolinite, which proceed to subsequent flotation). After each cycle, the non-magnetic products are fed into the next magnetic separation cycle until five cycles are completed. The products from each cycle are dried, weighed, and numbered. The yield and cumulative demagnetization rate for each cycle are calculated; one sample of magnetic products is retained for comparative analysis (XRF). Objective: To remove the strongly magnetic Fe phase as early as possible to reduce subsequent flotation reagent consumption and interfacial interference.

[0025] Flotation test (reverse flotation strategy) Method: Accurately weigh 10 g of coal-series kaolinite sample, add 100 ml of deionized water, and stir at 500 rpm for 5 min. Place it in the flotation cell of an XFG-35I suspended flotation machine, stir for 3 min, add different volumes of collector, and add frother after 1 min. Stir at a speed of 0.25 m... 3 / (m 2 Air was charged at a rate of 10 s for 1 min, followed by bubble scraping for 3 min. Each experimental sequence was repeated three times.

[0026] Experimental evaluation indicators: (1) Composition analysis: XRF: rapid determination of iron content in concentrate and tailings ICP-MS: Rapid determination of titanium and iron concentrations (quantitative analysis) Ti / Fe content in floating matter (to observe the enrichment effect; the Ti / Fe content in sediment can also be calculated based on the yield). (2) Flotation impurity recovery rate: Impurity recovery rate = mass of impurities in froth product / mass of impurities in raw ore × 100%.

[0027] Example 1: Screening for iron impurity targeting fixophilic groups using MS-based DFT adsorption energy calculations The specific steps are as described in the invention, specifically the molecular simulation screening steps. For the calculation of the adsorption energy of the 001 surface (aluminum oxide surface), please refer to [link / reference]. Figure 5 and 6 , Figure 5 , 6 The following are given: different functional groups on the pureslab surface (perfect bulk kaolinite surface), Fe 2+ -Al 3+ Substituted surface and Fe 3+ -Al 3+ The adsorption energy on the replacement surface (iron-doped kaolinite surface) is considered. According to the adsorption energy criterion, the more negative the adsorption energy, the greater the energy reduction of the system, the more stable the adsorption structure, and the stronger the interaction. Overall, all three models show the following trends: 1) The adsorption energy of Fe-doped surfaces is generally more negative than that of pure slab surfaces; 2) Fe 2+ -Al 3+ The model has the largest absolute value of adsorption energy.

[0028] This indicates that the Fe sites significantly enhance the surface's ability to chemisorb polar functional groups.

[0029] In Fe 3+ -Al 3+ In the substitution model, the adsorption energies of different fixophilic groups follow the following pattern: Sulfur-containing oxygen groups > carboxylates > nitrogen-containing groups. Among them, -SO3H and -SO3... - -SO4 2- The adsorption energies of sulfur-containing groups on the Fe-doped model are the largest in absolute value, exhibiting the strongest site selectivity; carboxylates are next; and nitrogen-containing groups have relatively smaller adsorption energies. This indicates that Fe doping sites preferentially bind to strongly coordinated, multi-oxygen structural groups.

[0030] The pattern of adsorption energy magnitudes is used to screen for collector functional groups with site-targeting properties.

[0031] DFT adsorption energy results indicate that Fe 3+ The sites exhibit the strongest chemisorption capacity for sulfur-containing oxygen polydentate coordination groups, followed by carboxylates, while nitrogen-containing quaternary ammonium salts show weaker adsorption.

[0032] Based on this theoretical result, the following collectors were screened: NaOl (sodium oleate), CTAB (hexadecyltrimethylammonium bromide), OTAB (octadecyltrimethylammonium bromide), and SDS (sodium dodecyl sulfate).

[0033] Based on this theoretical result, after screening collectors, experiments revealed that reagents with different functional group structures exhibited significant differences in Fe2O3 distribution during reverse flotation, with all contents exceeding those of the original ore, demonstrating the enrichment effect of flotation reagents on Fe. Furthermore, the varying content of floated matter after the action of each flotation collector indicates a close correlation between flotation behavior and the coordination adsorption strength at the molecular scale. The theoretical calculation results are consistent with the experimental trends, verifying the selective adsorption mechanism of Fe sites.

[0034] Example 2: Based on the simulation screening results, the collector was determined and reverse flotation test was conducted to enrich iron impurities. 1) Purpose Based on the targeted affinity groups screened in Example 1, commercially available collectors (or equivalent collectors) containing the corresponding functional groups were selected for reverse flotation verification, which enabled iron impurities to selectively float and enrich, while kaolinite sank, thus achieving iron removal and whitening. The effect was evaluated by the Fe2O3 content and whiteness index of the floating matter.

[0035] 2) Collector determination (mapping rules) Map the fixative groups obtained in Example 1 to collectors: preferably select commercially available collectors containing the functional group as candidates; if there are multiple candidate agents, determine them according to the similarity of their functional group structures, availability and preliminary test results.

[0036] (Here, "collectors A, B, C, and D" correspond to NaOl, CTAB, OTAB, and SDS in the experiment.) 3) Flotation feed and test conditions Kaolinite samples pretreated by magnetic separation were used as flotation feed.

[0037] 4) Detection methods and evaluation indicators are shown in the table below:

[0038] The Fe2O3 content of the floating matter was determined by ICP, and the enrichment effect was calculated based on the Fe2O3 content of the feed ore.

[0039] 5) Test Results The Fe2O3 content in the feed ore was 0.94%. The Fe2O3 content (%) of the floating matter under four collector conditions is as follows (5 parallel studies): NaOl: 1.02, 1.09, 1.10, 1.08, 1.07 (average approximately 1.072); CTAB: 1.14, 1.10, 1.16, 1.12, 1.22 (average approximately 1.148); OTAB: 1.11, 1.10, 1.16, 1.07, 1.22 (average approximately 1.132); SDS: 1.15, 1.18, 1.05, 1.14, 1.10 (average approximately 1.124).

[0040] 6) Conclusion Statement Compared to the feed ore Fe2O3 content of 0.94%, the Fe2O3 content of the float was higher under all collector conditions, indicating that iron impurities were enriched by flotation. The Fe2O3 content was even higher and more stable under CTAB and OTAB conditions, indicating a more significant enrichment effect on iron impurities. This result is consistent with the screening conclusion in Example 1 that "targeted fixative groups have stronger adsorption on Fe doping sites," thus verifying the feasibility and effectiveness of the "simulation screening—collector mapping—process verification" method proposed in this invention.

[0041] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0042] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for flotation enrichment of titanium / iron impurities in coal-series kaolinite, characterized in that, Includes the following steps: S1. Preprocessing The raw ore is screened and magnetically separated to remove gangue-type Ti / Fe minerals; S2. Molecular Simulation Screening (1) Construction of Kaolinite and Doping Model: Import kaolinite cells into Materials Studio to construct a surface model. A 2×2×1 supercell is used, and a vacuum layer is introduced to eliminate interlayer interactions. The following models are constructed respectively: A. Perfect bulk kaolinite surface model, i.e., undoped kaolinite surface model; B. Lattice-type Ti / Fe doping model; (2) Construction of a library of fixative groups: Based on the functional groups of common collectors in mineral flotation, a library of fixative group fragments was constructed. Each fixative group was first subjected to individual geometric optimization to obtain the lowest energy configuration. (3) Adsorption configuration setting: The fixative groups were placed near the undoped kaolinite surface model and the Ti / Fe doped model site, respectively, to set multiple initial adsorption orientations to avoid getting trapped in local minima; (4) CASTEP parameters and calculations: Geometric optimization and energy calculations are performed in the CASTEP Calculation module; (5) Adsorption energy and selectivity criteria: Calculate the adsorption energy: E ads =E surface adsorbate E surface E adsorbate in E surface adsorbate The total energy of the surface and reagent adsorption system. E surface The energy on the surface of kaolinite, E adsorbate The energy of the fixophilic group, E ads For adsorption energy, E ads The more negative the value, the stronger the adsorption. Define the selectivity index: E=E ads (doped) E ads (pure) when When E<0, it indicates that the adsorption of this group at the Ti / Fe doping site is stronger than that on the surface of undoped kaolinite; The more negative the E value, the stronger the targeting; therefore, during screening, priority should be given to candidates with significantly negative E values. E adspure However, strong candidate groups were not selected, thus screening for targeted fixative groups that met the requirements of stronger adsorption on the Ti / Fe doped kaolinite surface and weaker adsorption on perfect bulk kaolinite, and then according to... E and E ads (doped) Sort candidate fixophilic groups; (6) Collector mapping: Based on the screened target affinity groups, commercially available collectors or combinations thereof containing such functional groups are preferentially selected to form a reagent scheme that can be directly used for reverse flotation, providing a clear basis for reagent selection for subsequent experiments; S3. Flotation test Collectors with site selectivity are screened based on adsorption energy differences; A reverse flotation test was conducted, causing the kaolinite component with a high proportion of titanium / iron impurities to float to the top, while the kaolinite component with no or only a small amount of Ti / Fe remained hydrophilic and stayed in the tank. The composition was analyzed by XRF and ICP-MS to evaluate the impurity removal rate and product whiteness.

2. The method for flotation enrichment of titanium / iron impurities in coal-series kaolinite according to claim 1, characterized in that, In step S1, the sieving process removes coarse particles >0.5 mm; the magnetic separation involves cycling 5 times under a magnetic field strength of 0.25 T to remove strongly magnetic iron minerals.

3. The method for flotation enrichment of titanium / iron impurities in coal-series kaolinite according to claim 1, characterized in that, The doping method of the B. lattice-type Ti / Fe doping model is as follows: using Ti 4+ / Fe 2+ / Fe 3+ Al as an alternative to aluminum oxide surfaces 3+ and Si on the silicon-oxygen surface 4+ ; To address the net charge imbalance caused by heterovalent substitution, Na is introduced. + / H + / Cl - Charge compensation is achieved by setting oxygen vacancies or ortho-substitutions to obtain a stable surface structure that represents the active sites of lattice-type impurities.

4. The method for flotation enrichment of titanium / iron impurities in coal-series kaolinite according to claim 3, characterized in that, The minerals in step (2) include kaolinite; the library of fixative fragments includes at least one or more of the following groups: carboxylates, hydroxamic acid salts, phosphates (phosphine) salts, and sulfonates.

5. The method for flotation enrichment of titanium / iron impurities in coal-series kaolinite according to claim 4, characterized in that, The parameters for geometric optimization in step (4) include: the exchange-correlation functional is the PBE functional in GGA; the pseudopotential is an ultrasoft pseudopotential; the plane wave cutoff energy is set to Fine accuracy; the k-point is a 1×1×1 Gamma point; and the SCF convergence threshold is 1.8-2.2×10⁻⁶. - 6 eV / atom; energy / force / displacement convergence values ​​are 0.8-1.2×10⁻⁶ respectively. -5 eV / atom, 0.02-0.04 eV / Å, 0.001 Å; for Fe-doped models, spin polarization calculations are used; DFT-D dispersion corrections are introduced when necessary.

6. The method for flotation enrichment of titanium / iron impurities in coal-series kaolinite according to claim 5, characterized in that, The collector mapping rules in step (6) include: ① Among commercially available drugs, priority is given to selecting a series with the same target functional group and different hydrophobic chain lengths / branching degrees as candidates in order to construct a structure-activity comparison. ② When multiple candidates exist, the one with the most priority is selected. E More negative and E ads (pure) The weaker one; ③ If a single collector cannot achieve both selectivity and foaming performance, it should be combined with conventional foaming agents or inhibitors, and the final reagent system should be determined by flotation indicators, including Ti / Fe recovery rate and enrichment ratio.

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