A method for pyrite flotation recovery in raw ore

Abstract

This invention relates to the field of pyrite flotation technology, and discloses a method for the flotation recovery of pyrite from raw ore. The method involves adding water to pyrite powder to form a slurry, then sequentially adding lime, a field collector, a small-molecule carboxylic acid activator, and a frother for flotation to obtain pyrite concentrate. The small-molecule carboxylic acid activator achieves synergistic activation of the pyrite through carboxylate ions, hydrocarbon chains, and polar functional groups, thereby improving activation efficiency. The invention also discloses the application of a small-molecule carboxylic acid activator in promoting the flotation recovery of pyrite from raw ore. The invention proposes an activator that can replace sulfuric acid in activating high-sulfur ores inhibited by lime, and can participate in the flotation process of high-sulfur ores after lime treatment. More importantly, it pioneers a refined application model for small-molecule carboxylic acid compounds in pyrite flotation, resolving the contradiction between efficiency, selectivity, and environmental compatibility that is difficult to balance with traditional activators such as sulfuric acid.

Description

Technical Field

[0001] This invention relates to the field of pyrite flotation technology, and more specifically to a method for recovering pyrite by flotation in raw ore. Background Technology

[0002] In sulfide ore flotation, copper-sulfur separation is a crucial process. Currently, the industry commonly employs a high-alkali process, which uses large amounts of lime to create a strongly alkaline environment to suppress pyrite, thereby achieving efficient copper flotation. While this effectively separates copper and sulfide minerals, it also presents significant technical challenges: in subsequent sulfur beneficiation operations, the strongly suppressed pyrite surface forms a dense hydrophilic film composed of CaO, CaSO4, Ca(OH)2, and iron hydroxyl compounds, severely deteriorating its floatability and significantly impacting the overall recovery efficiency of sulfur resources.

[0003] To reactivate inhibited pyrite, sulfuric acid is currently the primary industrial activator. Its mechanism of action involves dissolving the calcium-containing hydrophilic film on the pyrite surface in a strong acid environment, exposing fresh sulfide surfaces and restoring its floatability. However, sulfuric acid has significant limitations: its strong corrosiveness causes serious damage to flotation equipment and piping systems, increasing equipment maintenance costs; it poses significant safety risks during operation, threatening the health of production personnel; and the subsequent treatment of acidic wastewater increases the environmental burden. These factors have prompted mineral processing workers to continuously seek milder, safer, and more efficient alternative activation methods. Summary of the Invention

[0004] The purpose of this invention is to provide a method for recovering pyrite by flotation in raw ore, so as to solve the technical problem that existing activators have many limitations in the prior art.

[0005] To solve the above-mentioned technical problems, the present invention specifically provides the following technical solution: This invention relates to a method for recovering pyrite by flotation in raw ore, comprising the following steps: The structural formula of the small molecule carboxylic acid activator is shown in Formula 1: Formula 1 In Formula 1, there is a group R attached to a carboxyl group and a group X attached to the R group; The R represents the carbon chain molecular skeleton of C1~C5; X represents a methyl or carboxyl group, or X represents a group having hydroxyl or polycarboxyl substitutions; During the flotation process, the carboxylate ions in the small molecule carboxylic acid activator are directionally adsorbed onto the calcium ion sites on the surface of the raw ore to form a stable five-membered ring chelate structure, effectively stripping the calcium covering film on the raw ore. At the same time, the hydrocarbon chains of the small molecule carboxylic acid activator construct hydrophobic regions on the mineral surface, improving the adhesion between the mineral and bubbles. Furthermore, the polar functional groups in the small molecule carboxylic acid activator give the mineral good solubility and reactivity over a wide pH range. The small molecule carboxylic acid activator achieves synergistic activation of pyrite through carboxylate ions, hydrocarbon chains, and polar functional groups, thereby improving activation efficiency.

[0006] As a preferred embodiment of the present invention, the small molecule carboxylic acid activator is any one or more of citric acid, tartaric acid, lactic acid, and oxalic acid.

[0007] As a preferred embodiment of the present invention, the following steps are included: After grinding the raw ore, pyrite powder is obtained. The pyrite powder is sequentially added to water, lime, on-site collector, and small molecule carboxylic acid activator for a roughing process to obtain concentrate K1 and middlings. Small molecule carboxylic acid activators and on-site collectors were added to the middlings in sequence for secondary roughing to obtain concentrate K2 and tailings.

[0008] As a preferred embodiment of the present invention, during the grinding process, 40.5-85.5% of the pyrite ore powder is ground to a fineness of 100-200 mesh.

[0009] As a preferred embodiment of the present invention, the field collector is one or more of butyl xanthate, isobutyl xanthate, etc. The foaming agent is at least one of alcohol-based foaming agents, ether-based foaming agents, and phenol-based foaming agents.

[0010] In a preferred embodiment of the present invention, the concentration of the xanthate is 1×10⁻⁶. -4 ~5×10 -2 mol / L; The concentration of the small molecule carboxylic acid activator is 1×10⁻⁶. -4 ~5×10 -2 mol / L; The concentration of the foaming agent is 1×10⁻⁶. -4~2 ×10 -4 mol / L.

[0011] As a preferred embodiment of the present invention, the dosage of the on-site harvesting agent is 20~150g / t, and the operation time is 4~6 minutes; The dosage of the small molecule carboxylic acid activator is 4000~8000 g / t, and the reaction time is 3~4 minutes.

[0012] This invention further provides the application of a small molecule carboxylic acid activator in promoting the flotation recovery of pyrite in raw ore.

[0013] In a preferred embodiment of the present invention, the activator contains carboxylate ions, which are directionally adsorbed onto calcium ion sites on the surface of the ore to form a stable five-membered ring chelate structure, effectively stripping away the calcium coating film on the ore caused by lime, thereby activating the pyrite efficiently.

[0014] Compared with the prior art, the present invention has the following advantages: This invention provides a method for flotation recovery of pyrite based on a small-molecule carboxylic acid activator. This activator uses a C3-C6 hydrocarbon carboxylic acid as its basic framework, and optimizes its molecular structure by introducing functional groups such as hydroxyl and carboxyl groups. The carboxylic acid ions form a stable five-membered ring chelate structure with the calcium ion sites adsorbed on the pyrite surface. This directional adsorption effectively removes the calcium coating film. The appropriately long hydrocarbon chain constructs hydrophobic regions on the mineral surface, enhancing its adhesion to air bubbles. The polar functional groups in the molecule ensure solubility and reactivity over a wide pH range. While maintaining the high permeability of the small-molecule compound, it significantly improves its interaction strength with the pyrite surface, thus replacing sulfuric acid and increasing the pyrite recovery rate to over 96%. It has no impact on the flotation of associated sulfide minerals, combining high efficiency, selectivity, and environmental compatibility, making it suitable for the clean separation of pyrite resources. This invention not only proposes an activator that can replace sulfuric acid in activating high-sulfur ores inhibited by lime and can participate in the flotation process of high-sulfur ores after lime treatment, but also pioneers a refined application model for small molecule carboxylic acid compounds in pyrite flotation. Through the rational selection of molecular structure, an optimized balance between chelating ability and hydrophobic properties is achieved, solving the contradiction that traditional activators cannot balance between efficiency, selectivity and environmental compatibility. Attached Figure Description

[0015] To more clearly illustrate the embodiments of the present invention or the technical solutions in 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 merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the process for promoting the flotation recovery of pyrite inhibited by lime, provided by the small molecule carboxylic acid activator in Example 1 of the present invention.

[0017] Figure 2 The graph shows the effect of lime concentration on the single mineral flotation recovery rate of pyrite, as provided in Example 1 of this invention.

[0018] Figure 3 The curves showing the effect of the dosage of lactic acid and tartaric acid on the single mineral flotation recovery rate of pyrite provided in Example 1 of the present invention.

[0019] Figure 4 The graph shows the effect of oxalic acid and citric acid dosages on the single mineral flotation recovery rate of pyrite, as provided in Example 1 of this invention.

[0020] Figure 5 This is a schematic diagram of the process for promoting the flotation recovery of pyrite in raw ore using small molecule carboxylic acid activators provided in Example 2 of the present invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] This invention provides a small molecule carboxylic acid activator, the structural formula of which is shown in Formula 1: Formula 1 In Formula 1, R represents the carbon chain molecular skeleton of C1 to C5, and X represents a methyl or carboxyl group, or a group with hydroxyl or polycarboxyl substitution.

[0023] Small molecule carboxylic acid activators can be any one or more of small molecule carboxylic acids such as citric acid, tartaric acid, lactic acid, and oxalic acid.

[0024] The structural formula of citric acid is shown in Formula 2: Formula 2 The structural formula of tartaric acid is shown in Formula 3: Formula 3 The structural formula of lactic acid is shown in Formula 4: Formula 4 The structural formula of oxalic acid is shown in Formula 5: Formula 5 Small molecule carboxylic acids can be prepared by hydrolysis of acid anhydrides. The preparation reaction formula for small molecule carboxylic acids is shown in Formula 6: R1-C(O)-OC(O)-R2 + H2O → R1COOH + R2COOH Formula 6 Formula 6 contains groups R1 and R2 attached to the acid anhydride. 2， R1 represents the carbon chain molecular skeleton of C1~C5, and R2 represents the carbon chain molecular skeleton of C1~C5.

[0025] Among them, symmetrical or asymmetrical acid anhydrides undergo hydrolysis under certain conditions, breaking the ester-oxygen bonds in the acid anhydride and ultimately generating two small molecule carboxylic acids: R1COOH and R2COOH.

[0026] The present invention also provides the application of the above-mentioned activator in the activation of inhibited pyrite. Specifically, this activator can replace activators such as sulfuric acid. This activator uses C3-C6 hydrocarbon carboxylic acid as the basic skeleton and optimizes the molecular structure by introducing functional groups such as hydroxyl and carboxyl groups. While maintaining the high permeability of small molecule compounds, it significantly improves the interaction strength with the surface of pyrite.

[0027] Its activation mechanism is mainly reflected in three synergistic levels: carboxylate ions form a stable five-membered ring chelate structure with the calcium ion sites adsorbed on the pyrite surface. This directional adsorption can effectively strip away the calcium coating film; the appropriate length of hydrocarbon chain constructs a hydrophobic region on the mineral surface, enhancing its adhesion to bubbles; and the polar functional groups in the molecule ensure solubility and reactivity over a wide pH range.

[0028] This multi-mechanism synergistic effect enables the activator to solve the activation problem of oxidized pyrite and effectively address the challenges of lime inhibition systems.

[0029] Compared to sulfuric acid activators, this activator has a similar effect to sulfuric acid, but is more inert and will not cause serious damage to flotation equipment and pipeline systems. It is less harmful to the human body during use, easy to recover, and has little impact on the environment, making it environmentally friendly.

[0030] Furthermore, such as Figure 1 As shown, the application method of this highly efficient pyrite activator based on small molecule carboxylic acids in activating inhibited pyrite is as follows, including the following steps: After mixing pyrite powder with water to form a slurry, lime, collector, small molecule carboxylic acid activator and frother are added in sequence for flotation to obtain pyrite concentrate.

[0031] Preferably, the foaming agent is at least one of alcohol-based foaming agents, ether-based foaming agents, and phenol-based foaming agents.

[0032] Preferably, the collector is xanthate.

[0033] Preferably, the flotation reagent formulation is as follows: lime concentration of 30-50 mg / L and xanthate concentration of 1×10⁻⁶ mg / L. -4 ~5×10 -2 mol / L, the concentration of small molecule carboxylic acid activator is 1×10 -4 ~5×10 -2 mol / L, foaming agent concentration is 1×10 -4~2 ×10 -4 mol / L.

[0034] Due to the formation of Ca(OH) in lime slurry + It can adsorb onto the surface of pyrite, thereby significantly increasing the hydrophilicity of the pyrite surface and forming a water film on the pyrite surface, which affects the function of the collector. The small molecule carboxylic acid activator forms a stable five-membered ring chelate structure with the calcium ion sites adsorbed on the pyrite surface through the carboxylate ion, thereby stripping away the calcium-covered water film, and constructing hydrophobic regions on the mineral surface through the hydrocarbon chain of appropriate length, enhancing its adhesion to bubbles, thereby improving the contact efficiency between the ore and the collector; at the same time, the polar functional groups in the activator can ensure the solubility and reactivity of the ore in a wide pH range.

[0035] Furthermore, such as Figure 4 As shown, the application of this highly efficient pyrite activator based on small molecule carboxylic acids in the flotation of sulfur-containing ores includes the following steps: After grinding the raw ore minerals, small molecule carboxylic acid activators and on-site collectors are added to the raw ore minerals in sequence for a roughing process to obtain concentrate K1 and middlings. Small molecule carboxylic acid activators and on-site collectors were added to the middlings in sequence for secondary roughing to obtain concentrate K2 and tailings X.

[0036] The fineness of the raw ore after grinding is 100-200 mesh, or 40.5-85.5%.

[0037] Preferably, the on-site collector is one or more of butyl xanthate, isobutyl xanthate (SIBX), etc., with a dosage of 20~150g / t and an operation time of 4~6 minutes; the small molecule carboxylic acid activator has a dosage of 4000~8000g / t and an action time of 3~4 minutes.

[0038] This invention not only proposes an activator that can replace sulfuric acid in activating high-sulfur ores inhibited by lime, enabling it to participate in the flotation process of high-sulfur ores after lime treatment, but also pioneers a refined application model for small-molecule carboxylic acid compounds in pyrite flotation. Through rational selection of molecular structure, an optimized balance between chelating ability and hydrophobic properties is achieved, resolving the contradiction between efficiency, selectivity, and environmental compatibility that is difficult to balance in traditional reagents.

[0039] Furthermore, this invention is applicable to scenarios such as sulfide ore recovery in high-calcium and high-alkali environments and clean separation of complex polymetallic sulfide ores, providing new technical support for improving the comprehensive utilization level of mineral resources. With increasingly stringent environmental protection requirements and the gradual deterioration of resource endowments, this efficient and environmentally friendly activation technology is expected to play an increasingly important role in the field of mineral processing.

[0040] The following examples further illustrate the activator: Example 1:

[0041] Preparation of small molecule acids using different acid anhydrides: Take 100g (0.69mol) of industrial-grade lactic anhydride (lactide) and add 300g (16.67mol) of deionized water. Control the reaction temperature at 80℃ and stir at a rate of 270r / min for 3h under normal pressure. After the reaction is complete, an aqueous lactic acid solution is obtained. Add 0.3g of activated carbon to the aqueous solution and decolorize at 70℃ for 30min. Filter to remove the activated carbon and then concentrate under reduced pressure to a lactic acid mass fraction of 80% to obtain the industrial-grade lactic acid product. The product purity is ≥98.0% and the yield is >93%.

[0042] Take 100g (0.48mol) of industrial-grade tartaric anhydride and add 400g (22.22mol) of deionized water. Control the reaction temperature at 75℃ and stir at 230r / min for 3h under normal pressure. After the reaction is complete, add 0.5g of activated carbon to the system and decolorize at 75℃ for 1h. Filter to remove activated carbon, concentrate the filtrate under reduced pressure until a large amount of crystals precipitate, cool to room temperature, crystallize, filter, and dry to obtain tartaric acid product. The product purity is ≥99.0% and the yield is >92%. Example 2:

[0043] Activator A, Activator B, Activator C, and Activator D were prepared separately. Activator A contained only citric acid, Activator B contained only tartaric acid, Activator C contained only lactic acid, and Activator D contained only oxalic acid.

[0044] The raw mineral was put into a pulverizer for grinding, and the particle size of the grinding product was controlled between -200 and +400 mesh. 2 g of the obtained sample was placed in a beaker with 220 mL of deionized water and stirred for 1 min at 500 rpm. Add 30 mg / L lime, adjust the slurry for 3 min, and measure the pH value to be 11.5~11.8; add 1×10 g xanthate to the slurry sequentially. -3 mol / L, activator, and foaming agent (MIBC dosage is 1.5 × 10⁻⁶). -4 (mol / L), and the slurry preparation times were 3 min, 3 min, and 1 min, respectively; The obtained slurry was transferred to a single bubble tube, rotated at 400 rpm, and nitrogen was introduced for froth flotation for 3 minutes. Finally, the concentrate and tailings obtained from flotation were filtered, dried, weighed, and the recovery rate was calculated.

[0045] Comparative Example 2: The other steps are the same as in Example 2, except that no activator is used.

[0046] The curve showing the effect of lime concentration on the single mineral flotation recovery of pyrite is shown below. Figure 2 As shown in the figure, the effects of lactic acid and tartaric acid dosages on the single-mineral flotation recovery rate of pyrite are illustrated in the graph. Figure 3 As shown in the figure, the effects of oxalic acid and citric acid dosage on the single mineral pyrite flotation recovery rate are as follows: Figure 4 As shown.

[0047] Depend on Figure 2 It can be seen that in the pyrite flotation system, as the amount of lime increases, the collecting effect of xanthate on pyrite is gradually suppressed; when the amount of lime increases to 30 mg / L, the pyrite recovery rate drops to below 10%, and the floatability is basically lost. It can be seen that lime does indeed greatly affect the comprehensive recovery efficiency of sulfur resources.

[0048] Based on this, the following analysis further explores the activation performance of different small molecule carboxylic acid activators on "lime-inhibited pyrite".

[0049] from Figure 3 , Figure 4 The experimental results show that, under specific concentration conditions, all small molecule carboxylic acid activators exhibit significant activation effects on pyrite: only 2×10⁻⁶ ppm was added. -3 When lactic acid or tartaric acid is added at concentrations of mol / L, the recovery rate of pyrite can reach 82.31% and 72.50%, respectively; with the addition of 5×10 mol / L lactic acid or tartaric acid, the recovery rate of pyrite can reach 82.31% and 72.50%, respectively. -4 When the concentrations are citric acid or oxalic acid, the pyrite recovery rates are 71.01% and 52.71%, respectively.

[0050] It is worth noting that when the oxalic acid concentration is increased to 2×10 -3 At a concentration of mol / L, its activation effect on pyrite is further enhanced, and the recovery rate can exceed 80%.

[0051] The above results indicate that small molecule carboxylic acids are highly effective in relieving the inhibition of pyrite by lime and restoring its floatability, and have the potential to be used as pyrite activators.

[0052] Example 3: Actual ore experiment - The effect of activator type on flotation parameters of high-sulfur ore samples. Prepare activator A, which contains only citric acid.

[0053] The high-sulfur ore sample (0424) was taken on the afternoon of April 24, 2024. After grinding for 7 minutes, with a fineness of -200 mesh accounting for 67.6%, citric acid activator and butyl xanthate (BX) in-situ collector were used for 3 minutes and 3 minutes respectively for slurry conditioning. A roughing process was carried out for 5 minutes at a speed of 1750 r / min to obtain concentrate K1 and middlings.

[0054] Next, the middlings were scavenged once (~1750r / min, 5min), and citric acid activator and on-site collector were added in sequence, and the pulp was adjusted for 3min and 3min respectively to obtain K2.

[0055] Comparative Example 3: The other steps are the same as in Example 3, except that activator E is prepared, and activator E contains sulfuric acid.

[0056] Comparative Example 4: The other steps are the same as in Example 3, except that no activator is used.

[0057] Table 1 shows the results of two roughing flotation tests on high-sulfur ore samples with different activators: Table 1 As shown in Table 1, the sulfur (S) recovery rates under different reagent regimes in the flotation process test of high-sulfur ore samples are as follows: when only xanthate collectors are added, the S recovery rate is 95.08%; when sulfuric acid is introduced as an activator, the S recovery rate increases to 97.83%, which is 2.75 percentage points higher than the condition without activator.

[0058] Using citric acid instead of sulfuric acid as an activator, the sulfur recovery rate can still be stably maintained at over 97%, indicating that citric acid has comparable activation efficiency to sulfuric acid and has the potential to replace sulfuric acid in this high-sulfur ore flotation system.

[0059] The above embodiments are merely exemplary embodiments of this application and are not intended to limit this application. The scope of protection of this application is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to this application within its substance and scope of protection, and such modifications or equivalent substitutions should also be considered to fall within the scope of protection of this application.

Claims

1. A method for recovering pyrite by flotation in raw ore, characterized in that, Includes the following steps: After mixing pyrite powder with water to form a slurry, lime, on-site collector, small molecule carboxylic acid activator and frother are added in sequence for flotation to obtain pyrite concentrate; The structural formula of the small molecule carboxylic acid activator is shown in Formula 1: Formula 1 In Formula 1, there is a group R attached to a carboxyl group and a group X attached to the R group; The R represents the carbon chain molecular skeleton of C1~C5; X represents a methyl or carboxyl group, or X represents a group having hydroxyl or polycarboxyl substitutions; During the flotation process, the carboxylate ions in the small molecule carboxylic acid activator are directionally adsorbed onto the calcium ion sites on the surface of the raw ore to form a stable five-membered ring chelate structure, effectively stripping the calcium covering film on the raw ore. At the same time, the hydrocarbon chains of the small molecule carboxylic acid activator construct hydrophobic regions on the mineral surface, improving the adhesion between the mineral and bubbles. Furthermore, the polar functional groups in the small molecule carboxylic acid activator give the mineral good solubility and reactivity over a wide pH range. The small molecule carboxylic acid activator achieves synergistic activation of pyrite through carboxylate ions, hydrocarbon chains, and polar functional groups, thereby improving activation efficiency.

2. The method for recovering pyrite by flotation in raw ore according to claim 1, characterized in that, The small molecule carboxylic acid activator is any one or more of citric acid, tartaric acid, lactic acid, and oxalic acid.

3. The method for recovering pyrite by flotation in raw ore according to claim 1, characterized in that, Includes the following steps: After grinding the raw ore, pyrite powder is obtained. The pyrite powder is sequentially added to water, lime, on-site collector, and small molecule carboxylic acid activator for a roughing process to obtain concentrate K1 and middlings. Small molecule carboxylic acid activators and on-site collectors were added to the middlings in sequence for secondary roughing to obtain concentrate K2 and tailings.

4. The method for recovering pyrite by flotation in raw ore according to claim 3, characterized in that, During the grinding process, 40.5-85.5% of the pyrite ore powder is ground to a fineness of 100-200 mesh.

5. The method for recovering pyrite by flotation in raw ore according to claim 3, characterized in that, The field collector is one or more of butyl xanthate, isobutyl xanthate, etc. The foaming agent is at least one of alcohol-based foaming agents, ether-based foaming agents, and phenol-based foaming agents.

6. The method for recovering pyrite by flotation in raw ore according to claim 3, characterized in that, The concentration of the xanthate is 1×10 -4 ~5×10 -2 mol / L; The concentration of the small molecule carboxylic acid activator is 1×10⁻⁶. -4 ~5×10 -2 mol / L; The concentration of the foaming agent is 1×10⁻⁶. -4~2 ×10 -4 mol / L.

7. The method for recovering pyrite by flotation in raw ore according to claim 6, characterized in that, The dosage of the on-site collector is 20~150g / t, and the operation time is 4~6 minutes; The dosage of the small molecule carboxylic acid activator is 4000~8000 g / t, and the reaction time is 3~4 minutes.

8. The application of the small molecule carboxylic acid activator as described in claim 1 in promoting the flotation recovery of pyrite in raw ore.

9. The application according to claim 8, characterized in that, The activator contains carboxylate ions, which are directionally adsorbed onto calcium ion sites on the surface of the ore to form a stable five-membered ring chelate structure. This effectively removes the calcium coating film on the ore caused by lime, thereby activating the pyrite efficiently.

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