Method for determining the gold content of brown iron ore in heavy floatation tailings

Abstract

The application discloses a method for determining the gold-carrying amount of brown iron ore in heavy floatation tailings, which comprises the following steps: mixing the tailing sample with a composite reducing agent composed of flour, activated carbon, anhydrous sodium carbonate and ammonium sulfate; performing closed reduction roasting by subsection heating, constructing a loose porous structure and converting the gangue phase by the pore-forming effect of the ammonium sulfate and the fluxing modification of the sodium carbonate; obtaining the magnetic product by grinding and ultrasonic-assisted magnetic separation, and then performing oxidation roasting and acid dissolution treatment, removing the modified gangue by mass difference subtraction, calculating the net mass of the brown iron ore, and combining with the liquid phase gold content determination to obtain the gold-carrying amount; and the application effectively solves the problems of serious micro-fine particle brown iron ore wrapping, easy roasting and large gangue interference, and realizes the accurate determination of the gold-carrying amount.

Description

Technical Field

[0001] This invention relates to the field of mineral analysis technology, specifically to a method for determining the gold content of limonite in gravity flotation tailings. Background Technology

[0002] Gold resources, as an important precious metal resource, hold a strategic position in global economic development. With the gradual depletion of easily beneficiated rich ores, the development and utilization of difficult-to-process gold ores has become an inevitable trend in the mining industry. Among them, pyrite vein-type gold ores with a high degree of limonite mineralization often produce large amounts of gold-bearing tailings during the beneficiation process due to their complex mineralogical characteristics, resulting in a serious waste of gold resources.

[0003] The tailings of gold ore with a high degree of limonite mineralization, after being processed by a combined gravity separation-flotation process, have the following characteristics: (1) High mudification characteristics: Limonite is very prone to mudification during the grinding process, forming a large amount of fine mud particles smaller than 0.054 mm. Due to their excessively fine particle size, these fine mineral particles cannot meet the density difference separation conditions required by the gravity separation process, resulting in a low gravity separation recovery rate.

[0004] (2) Poor flotation adaptability: The surface of limonite after mudification is significantly more hydrophilic, making it difficult for conventional flotation reagents to be effectively adsorbed. In addition, the fine mud will coat the surface of other minerals, deteriorating the flotation separation environment, resulting in a limonite flotation recovery rate that is usually less than 60%.

[0005] (3) Complex gold-carrying properties: As a product of pyrite oxidation, limonite inherits the gold-carrying properties of primary pyrite. Due to the porous structure and strong adsorption properties of limonite, gold particles can exist in the form of mechanical encapsulation inside the limonite lattice or be distributed on the surface of limonite in the form of ion adsorption, forming a complex gold-limonite symbiotic relationship.

[0006] Due to the aforementioned technical challenges, a large amount of gold-bearing limonite enters the tailings, resulting in generally high gold grades in these tailings. This not only causes a serious loss of gold resources but also brings additional pressure to the environmental disposal of tailings.

[0007] Existing techniques for determining the gold content of limonite in gravity flotation tailings have the following shortcomings: (1) Limitations of traditional chemical phase analysis: The current chemical phase analysis method for gold in "Rock and Mineral Analysis" can only determine the content of "encased gold" in limonite, and cannot comprehensively determine the total gold content (encased gold + semi-exposed gold + fine-grained gold) of limonite. For gravity flotation tailings with a high degree of oxidation, this method often underestimates the actual gold content of limonite.

[0008] (2) Manual sorting is not feasible: In theory, the most accurate method for gold determination is to directly select single limonite minerals in the 0.01~0.001mm particle size range under a microscope. However, due to the high degree of mud formation of limonite and its close association with gangue minerals, manual sorting is technically almost impossible and extremely costly, and has no industrial application value.

[0009] (3) Technical defects of existing enrichment methods: Although traditional magnetic separation enrichment methods can recover some limonite, the recovery effect is limited for fine-grained, weakly magnetic limonite. At the same time, existing reduction roasting technology often uses a single reducing agent (such as charcoal or coke), and the control of the reducing atmosphere is unstable, which can easily lead to material caking or insufficient reduction, affecting the subsequent magnetic separation effect and measurement accuracy.

[0010] To accurately evaluate the gold resource value in gravity flotation tailings and guide the design of subsequent limonite recovery processes (such as fine-grained flotation and combined magnetic separation-flocculation processes), it is urgently necessary to establish a specific method for determining the gold loading of limonite, applicable to the characteristics of such tailings. This method should meet the following technical requirements: (1) High selectivity: It can effectively separate goethite from major gangue minerals such as quartz, feldspar, calcite, and dolomite; (2) High recovery rate: It has a good enrichment capacity for fine-grained, highly muddy limonite; (3) High precision: The measurement results should be able to fully reflect the total gold content of limonite, including gold in various occurrence states; (4) Strong applicability: The method should have good reproducibility and be applicable to different types of gravity flotation tailings.

[0011] Based on the above technical requirements, this invention proposes a method for determining the gold content of limonite in gravity flotation tailings based on the synergistic effect of composite reducing agents. By optimizing the reduction roasting process, magnetic separation enrichment conditions, and chemical analysis process, the method achieves accurate determination of the gold content of limonite in such tailings, providing important technical support for the resource utilization of refractory gold mine tailings. Summary of the Invention

[0012] To address the shortcomings of existing technologies, this invention aims to provide a method for determining the gold loading of limonite in gravity flotation tailings. This invention overcomes the technical bottleneck of "difficult dissociation and easy sintering" of fine-grained limonite by introducing the synergistic effect of a microporous induced composite reducing agent and a segmented magnetization roasting process. It achieves dual regulation of mineral structure loosening and gangue solubility modification. Combined with ultrasonic-assisted magnetic separation and chemical difference correction, it eliminates the interference of physical inclusions and gangue impurities on the measurement results, significantly improving the accuracy and stability of gold loading determination. This provides reliable technical support for the accurate evaluation and secondary development of tailings resources.

[0013] To achieve the above objectives, the present invention adopts the following technical solution: A method for determining the gold content of limonite in gravity flotation tailings includes the following steps: Step S1: Take a gravity flotation tailings sample and add a composite reducing agent at a mass ratio of 1.5 to 3:1. The composite reducing agent is composed of flour, activated carbon, anhydrous sodium carbonate and ammonium sulfate, with a preferred mass ratio of 1:0.5 to 2:0.05 to 0.15:0.05 to 0.1.

[0014] At this ratio, flour acts as a binder and provides basic reduction, activated carbon serves as a framework to prevent collapse, sodium carbonate modifies silicate, and ammonium sulfate foams and creates pores.

[0015] Step S2: Place the mixture in a sealed container (such as an Erlenmeyer flask), invert a porcelain evaporating dish over the mouth of the flask, and fill it with a 5-20 mm thick layer of -1 mm particle size activated carbon powder or graphite powder as a carbon powder sealing layer to maintain a reducing atmosphere.

[0016] The heating process is carried out in stages: first, the temperature is increased to 200-400℃ at a rate of 5-10℃ / min and held for 20-60min (to decompose ammonium sulfate and create pores); then the temperature is increased to 650-810℃ and held for 1-3h (to complete magnetization roasting and gangue modification).

[0017] Step S3: Grind the roasted product to a particle size of -0.074 mm or more (over 85%); add water to form a slurry at a solid-liquid ratio of 1:3~5 g / mL, add 0.1~0.5% sodium hexametaphosphate by weight of the roasted product, and perform magnetic separation using a magnetic field strength of 100~160 mT; add water to form a slurry again at a solid-liquid ratio of 1:3~5 g / mL, treat with 40 kHz ultrasonic cavitation for 5 min, and then refine under the same magnetic field conditions to obtain the final magnetic product; Step S4: Oxidize at 600~800℃ for 1~2 hours to remove residual carbon and organic matter, and oxidize magnetite to hematite to facilitate subsequent acid dissolution; Step S5: Add 10-20wt% nitric acid aqueous solution at a liquid-to-solid ratio of 20-40mL / g, heat in a boiling water bath for 15-30min to dissolve the sodium carbonate-modified silicate gangue, and obtain primary slag weight W1; add mixed acid (concentrated hydrochloric acid to concentrated nitric acid volume ratio 3:1) to dissolve the residue, and separate the solid and liquid to obtain secondary slag weight W2; calculate the net mass of limonite according to the formula mFe=W1-W2.

[0018] Step S6: Collect the filtrate from S5, heat the filtrate at low temperature (100~120℃) to a volume of about 5mL, add 10mL of aqua regia to continue digestion; then evaporate to near dryness, add 5mL of concentrated hydrochloric acid and evaporate to near dryness, repeat the hydrochloric acid addition and denitrification operation 2~3 times until no reddish-brown gas is present, and finally make up to volume with 5~10% dilute hydrochloric acid; adsorb the solution after volume adjustment through polyurethane foam (or activated carbon), and then desorb it with acidic thiourea solution (10g / L thiourea + 1% sulfuric acid), use atomic absorption spectrometry (AAS) to determine the gold concentration c in the desorbed solution, and calculate the gold mass mAu; the formula for calculating the gold loading grade G of limonite in the gravity flotation tailings is: G=mAu / mFe.

[0019] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention creatively introduces a binary combination of ammonium sulfate and anhydrous sodium carbonate into the reducing agent. Utilizing the gas-generating properties of ammonium sulfate during low-temperature decomposition, a large number of microporous channels are pre-constructed within the material. This not only offsets the risk of material caking that may result from the high-temperature fluxing of sodium carbonate, making the roasted product loose and porous, and easily ground and dissociated, but more importantly, these microporous channels promote the penetration of subsequent acid-dissolving reagents, ensuring that the encapsulated gold can be completely dissolved and measured.

[0020] 2. Anhydrous sodium carbonate can undergo a solid-phase reaction with the insoluble quartz and silicate gangue associated with the surface of limonite at high temperatures, transforming them into soluble sodium silicate and other phases. This modification process allows gangue impurities that are originally impossible to remove by physical magnetic separation and insoluble in conventional acid dissolution to be preferentially dissolved and removed by dilute nitric acid in step S52. This makes the final calculated net mass mFe of limonite closer to the true value, eliminating the denominator overestimation error caused by gangue contamination and significantly improving the accuracy of gold loading determination.

[0021] 3. In conjunction with the aforementioned composite reducing agent, this invention employs a specific staged heating process. The first stage of low-temperature holding ensures the full action of the micropore activator, constructing a pore framework; the second stage of high-temperature roasting, under the action of a reducing atmosphere and alkaline additives, achieves the efficient conversion of limonite to magnetite.

[0022] 4. In combination with the microcrack structure generated by roasting, this invention introduces ultrasound and sodium hexametaphosphate dispersant. Through ultrasonic cavitation, fine gangue particles are further exfoliated, which greatly improves the purity of magnetite and lays the foundation for subsequent high-precision determination. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. Of course, the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention.

[0024] Unless otherwise specified, all chemical reagents and materials in this invention are purchased from the market or synthesized from raw materials purchased from the market.

[0025] A method for determining the gold content of limonite in gravity flotation tailings includes the following steps: Step S1: Take a sample of gravity flotation tailings and add a composite reducing agent at a mass ratio of 1.5 to 3:1. The composite reducing agent is composed of flour, activated carbon, anhydrous sodium carbonate and ammonium sulfate, with a preferred mass ratio of 1:0.5 to 2:0.05 to 0.15:0.05 to 0.1. Step S2: Place the mixture in a sealed Erlenmeyer flask, invert a porcelain evaporating dish over the mouth of the flask, and fill it with a 5-20 mm thick layer of -1 mm particle size activated carbon powder or graphite powder as a carbon powder sealing layer to maintain a reducing atmosphere; first, raise the temperature to 200-400℃ at 5-10℃ / min and hold for 20-60 min; then raise the temperature to 650-810℃ and hold for 1-3 h. After the holding period, cool the mixture to room temperature with the furnace. Step S3: Grind the roasted product until the -0.074mm particle size accounts for more than 85% to ensure the monomer dissociation of fine gold particles; add water to make a slurry at a solid-liquid ratio of 1:3~5g / mL, add 0.1~0.5% sodium hexametaphosphate by weight of the roasted product, and perform magnetic separation for 3~10min using a magnetic field strength of 100~160mT; add water to make a slurry again at a solid-liquid ratio of 1:3~5g / mL, treat with 40kHz ultrasonic cavitation for 5min, and then finely separate for 3~10min under the same magnetic field conditions to obtain the final magnetic product; Step S4: Oxidize the magnetic product at 600~800℃ for 1~2h to obtain a concentrate sample; Step S5: Add 10-20wt% nitric acid aqueous solution to the concentrate sample at a liquid-to-solid ratio of 20-40 mL / g, heat in a boiling water bath for 15-30 min to obtain the primary slag weight W1; add mixed acid (concentrated hydrochloric acid to concentrated nitric acid volume ratio 3:1) to dissolve the residue, and separate the solid and liquid to obtain the secondary slag weight W2; calculate the net mass mFe of limonite according to the formula mFe=W1-W2; Step S6: Collect the filtrate from S5, heat the filtrate at low temperature (100~120℃) to a volume of about 5mL, add 10mL of aqua regia to continue digestion; then evaporate to near dryness, add 5mL of concentrated hydrochloric acid and evaporate to near dryness, repeat the hydrochloric acid addition to remove nitrate 2~3 times until no reddish-brown gas is present, finally make up to volume with 5~10% dilute hydrochloric acid; adsorb the solution after volume adjustment through polyurethane foam (or activated carbon), and then desorb with acidic thiourea solution (10g / L thiourea + 1% sulfuric acid), use atomic absorption spectrometry to determine the gold concentration c in the desorbed solution, and calculate the gold mass mAu; the formula for calculating the gold loading grade G of limonite in the gravity flotation tailings is: G=mAu / mFe.

[0026] The present invention will be further described below through specific embodiments.

[0027] Example 1 A method for determining the gold content of limonite in gravity flotation tailings includes the following steps: Step S1: Take a sample of gravity flotation tailings and add a composite reducing agent at a mass ratio of 3:1. The composite reducing agent is composed of flour, activated carbon, anhydrous sodium carbonate and ammonium sulfate, with a mass ratio of 1:2:0.15:0.1. Step S2: Place the mixture in a sealed Erlenmeyer flask, invert a porcelain evaporating dish over the mouth of the flask, and fill it with 15mm thick -1mm particle size activated carbon powder as a carbon powder sealing layer to maintain a reducing atmosphere; first, heat to 400℃ at 8℃ / min and hold for 20min; then heat to 810℃ and hold for 1h. After the holding period, cool to room temperature with the furnace. Step S3: Grind the roasted product to a particle size of -0.074 mm (95%) to ensure the liberation of fine gold particles; add water to form a slurry at a solid-liquid ratio of 1:5 g / mL, add 0.5% sodium hexametaphosphate by weight of the roasted product, and perform magnetic separation for 6 min using a magnetic field strength of 150 mT; add water to form a slurry again at a solid-liquid ratio of 1:5 g / mL, treat with ultrasonic cavitation at 40 kHz for 5 min, and then refine under the same magnetic field conditions for 6 min to obtain the final magnetic product; Step S4: Oxidize the magnetic product at 800℃ for 1 hour to obtain a concentrate sample; Step S5: Add 15wt% nitric acid aqueous solution to the concentrate sample at a liquid-to-solid ratio of 40mL / g, heat in a boiling water bath for 30min to obtain primary slag weight W1; add mixed acid (concentrated hydrochloric acid and concentrated nitric acid in a volume ratio of 3:1) to dissolve the residue, and separate the solid and liquid to obtain secondary slag weight W2; calculate the net mass mFe of limonite according to the formula mFe=W1-W2. Step S6: Collect the filtrate from S5, heat the filtrate at low temperature (120℃) to a volume of about 5mL, add 10mL of aqua regia to continue digestion; then evaporate to near dryness, add 5mL of concentrated hydrochloric acid and evaporate to near dryness, repeat the hydrochloric acid addition and denitrification operation 3 times until no reddish-brown gas is present, and finally make up to volume with 10% dilute hydrochloric acid; adsorb the solution after volume adjustment through polyurethane foam (or activated carbon), and then desorb it with acidic thiourea solution (10g / L thiourea + 1% sulfuric acid), use atomic absorption spectrometry to determine the gold concentration c in the desorbed solution, and calculate the gold mass mAu; the formula for calculating the gold loading grade G of limonite in the heavy flotation tailings is: G=mAu / mFe.

[0028] Example 2 A method for determining the gold content of limonite in gravity flotation tailings includes the following steps: Step S1: Take a sample of gravity flotation tailings and add a composite reducing agent at a mass ratio of 1.5:1. The composite reducing agent is composed of flour, activated carbon, anhydrous sodium carbonate and ammonium sulfate, with a mass ratio of 1:0.5:0.05:0.05. Step S2: Place the mixture in a sealed Erlenmeyer flask, invert a porcelain evaporating dish over the mouth of the flask, and fill it with 15mm thick -1mm particle size activated carbon powder as a carbon powder sealing layer to maintain a reducing atmosphere; first, heat to 200℃ at 8℃ / min and hold for 60min; then heat to 650℃ and hold for 3h. After the holding period, cool to room temperature with the furnace. Step S3: Grind the roasted product to a particle size of -0.074 mm (95%) to ensure the liberation of fine gold particles; add water to form a slurry at a solid-liquid ratio of 1:5 g / mL, add 0.1% sodium hexametaphosphate by weight of the roasted product, and perform magnetic separation for 6 min using a magnetic field strength of 150 mT; add water to form a slurry again at a solid-liquid ratio of 1:5 g / mL, treat with ultrasonic cavitation at 40 kHz for 5 min, and then refine under the same magnetic field conditions for 6 min to obtain the final magnetic product; Step S4: Oxidize the magnetic product at 600℃ for 2 hours to obtain a concentrate sample; Step S5: Add 15wt% nitric acid aqueous solution to the concentrate sample at a liquid-to-solid ratio of 20mL / g, heat in a boiling water bath for 30min to obtain primary slag weight W1; add mixed acid (concentrated hydrochloric acid to concentrated nitric acid volume ratio 3:1) to dissolve the residue, and separate the solid and liquid to obtain secondary slag weight W2; calculate the net mass mFe of limonite according to the formula mFe=W1-W2. Step S6: Collect the filtrate from S5, heat the filtrate at low temperature (100℃) to a volume of about 5mL, add 10mL of aqua regia to continue digestion; then evaporate to near dryness, add 5mL of concentrated hydrochloric acid and evaporate to near dryness, repeat the hydrochloric acid addition and denitrification operation 3 times until no reddish-brown gas is present, and finally make up to volume with 5% dilute hydrochloric acid; adsorb the solution after volume adjustment through polyurethane foam (or activated carbon), and then desorb it with acidic thiourea solution (10g / L thiourea + 1% sulfuric acid), use atomic absorption spectrometry to determine the gold concentration c in the desorbed solution, and calculate the gold mass mAu; the formula for calculating the gold loading grade G of limonite in the gravity flotation tailings is: G=mAu / mFe.

[0029] Comparative Example 1 A method for determining the gold content of limonite in gravity flotation tailings includes the following steps: Step S1: Take a sample of gravity flotation tailings and add a composite reducing agent at a mass ratio of 3:1. The composite reducing agent is composed of flour, activated carbon, and anhydrous sodium carbonate in a mass ratio of 1:2:0.15. Step S2: Place the mixture in a sealed Erlenmeyer flask, invert a porcelain evaporating dish over the mouth of the flask, and fill it with 15mm thick -1mm particle size activated carbon powder as a carbon powder sealing layer to maintain a reducing atmosphere; first, heat to 400℃ at 8℃ / min and hold for 20min; then heat to 810℃ and hold for 1h. After the holding period, cool to room temperature with the furnace. Step S3: Grind the roasted product to a particle size of -0.074 mm (95%) to ensure the liberation of fine gold particles; add water to form a slurry at a solid-liquid ratio of 1:5 g / mL, add 0.5% sodium hexametaphosphate by weight of the roasted product, and perform magnetic separation for 6 min using a magnetic field strength of 150 mT; add water to form a slurry again at a solid-liquid ratio of 1:5 g / mL, and perform fine separation for 6 min under the same magnetic field conditions to obtain the final magnetic product; Step S4: Oxidize the magnetic product at 800℃ for 1 hour to obtain a concentrate sample; Step S5: Add 15wt% nitric acid aqueous solution to the concentrate sample at a liquid-to-solid ratio of 40mL / g, heat in a boiling water bath for 30min to obtain primary slag weight W1; add mixed acid (concentrated hydrochloric acid and concentrated nitric acid in a volume ratio of 3:1) to dissolve the residue, and separate the solid and liquid to obtain secondary slag weight W2; calculate the net mass mFe of limonite according to the formula mFe=W1-W2. Step S6: Collect the filtrate from S5, heat the filtrate at low temperature (120℃) to a volume of about 5mL, add 10mL of aqua regia to continue digestion; then evaporate to near dryness, add 5mL of concentrated hydrochloric acid and evaporate to near dryness, repeat the hydrochloric acid addition and denitrification operation 3 times until no reddish-brown gas is present, and finally make up to volume with 10% dilute hydrochloric acid; adsorb the solution after volume adjustment through polyurethane foam (or activated carbon), and then desorb it with acidic thiourea solution (10g / L thiourea + 1% sulfuric acid), use atomic absorption spectrometry to determine the gold concentration c in the desorbed solution, and calculate the gold mass mAu; the formula for calculating the gold loading grade G of limonite in the heavy flotation tailings is: G=mAu / mFe.

[0030] Comparative Example 2 A method for determining the gold content of limonite in gravity flotation tailings includes the following steps: Step S1: Take a sample of gravity flotation tailings and add a composite reducing agent at a mass ratio of 3:1. The composite reducing agent is composed of flour, activated carbon and ammonium sulfate in a mass ratio of 1:2:0.1. Step S2: Place the mixture in a sealed Erlenmeyer flask, invert a porcelain evaporating dish over the mouth of the flask, and fill it with 15mm thick -1mm particle size activated carbon powder as a carbon powder sealing layer to maintain a reducing atmosphere; first, heat to 400℃ at 8℃ / min and hold for 20min; then heat to 810℃ and hold for 1h. After the holding period, cool to room temperature with the furnace. Step S3: Grind the roasted product to a particle size of -0.074 mm (95%) to ensure the liberation of fine gold particles; add water to form a slurry at a solid-liquid ratio of 1:5 g / mL, add 0.5% sodium hexametaphosphate by weight of the roasted product, and perform magnetic separation for 6 min using a magnetic field strength of 150 mT; add water to form a slurry again at a solid-liquid ratio of 1:5 g / mL, and perform fine separation for 6 min under the same magnetic field conditions to obtain the final magnetic product; Step S4: Oxidize the magnetic product at 800℃ for 1 hour to obtain a concentrate sample; Step S5: Add 15wt% nitric acid aqueous solution to the concentrate sample at a liquid-to-solid ratio of 40mL / g, heat in a boiling water bath for 30min to obtain primary slag weight W1; add mixed acid (concentrated hydrochloric acid and concentrated nitric acid in a volume ratio of 3:1) to dissolve the residue, and separate the solid and liquid to obtain secondary slag weight W2; calculate the net mass mFe of limonite according to the formula mFe=W1-W2. Step S6: Collect the filtrate from S5, heat the filtrate at low temperature (120℃) to a volume of about 5mL, add 10mL of aqua regia to continue digestion; then evaporate to near dryness, add 5mL of concentrated hydrochloric acid and evaporate to near dryness, repeat the hydrochloric acid addition and denitrification operation 3 times until no reddish-brown gas is present, and finally make up to volume with 10% dilute hydrochloric acid; adsorb the solution after volume adjustment through polyurethane foam (or activated carbon), and then desorb it with acidic thiourea solution (10g / L thiourea + 1% sulfuric acid), use atomic absorption spectrometry to determine the gold concentration c in the desorbed solution, and calculate the gold mass mAu; the formula for calculating the gold loading grade G of limonite in the heavy flotation tailings is: G=mAu / mFe.

[0031] To verify the beneficial effects of the technical solution of this invention, Examples 1 and 2 and Comparative Examples 1 and 2 were set up. It should be noted that the experimental raw materials used in each example and comparative example were all taken from the same batch of gravity flotation tailings from the same mine, and underwent thorough crushing, mixing, and fractionation to ensure that the raw material basis of each group of experiments was consistent. The theoretical total gold grade of this batch of raw ore samples was determined to be approximately 0.25 g / t.

[0032] To comprehensively verify the technical effects of this invention, a material balance analysis method was used to track and measure the experimental products of the examples and comparative examples throughout the entire process. The specific meanings and acquisition methods of each parameter are as follows: 1. Magnetic material (limonite phase) Weight (g): Meaning: It refers to the refined mineral (i.e., limonite) that is finally adsorbed and retained by a magnet after reduction roasting, grinding and two-stage magnetic separation.

[0033] Method of obtaining: After drying the magnetic product finally adsorbed by the magnetic separator, it is directly weighed using an electronic balance.

[0034] Yield (%): Meaning: The percentage of limonite in the total weight of the raw ore.

[0035] Calculation formula: Yield = (Weight of magnetic material / Total weight of raw ore 50g) × 100%.

[0036] Gold grade (g / t): Meaning: The mass of gold contained per unit mass in a limonite phase, i.e., the gold content.

[0037] Method of obtaining gold: The results obtained in steps S5-S6 of this invention. After acid dissolution, aqua regia digestion, and adsorption-desorption of the magnetic material, the mass of gold mAu is measured by atomic absorption spectrometry, and then divided by the net mass of limonite mFe to obtain the gold content.

[0038] Gold distribution rate (%): Meaning: The proportion of gold contained in limonite relative to the total gold content in the original ore. A higher value indicates a stronger ability of the method to capture gold and a more accurate measurement.

[0039] Calculation formula: Distribution rate = (weight of magnetic material × gold grade of magnetic material) / (total weight of raw ore × gold grade of raw ore) × 100%.

[0040] 2. Non-magnetic materials (gangue minerals) Weight (g): Meaning: Refers to the substances (mainly gangue such as quartz and silicates) that are not attracted by the magnet during the magnetic separation process and are discharged as tailings.

[0041] Acquisition method: Collect all tailings slurry discharged from magnetic separation, dry it and weigh it.

[0042] Gold grade (g / t): Meaning: The gold content remaining in gangue that was discarded as waste. The lower the value, the more completely the gold was separated from the gangue.

[0043] Acquisition method: The dried gangue samples were taken and analyzed separately using the standard fire assay method.

[0044] Gold distribution rate (%): Meaning: What percentage of the total gold contained in the original ore was lost in the gangue.

[0045] Calculation formula: Distribution rate = (weight of non-magnetic material × gold grade of non-magnetic material) / (total weight of raw ore × gold grade of raw ore) × 100%.

[0046] 3. Total Total weight (g): Meaning: The closed-loop verification of material quality before and after the experiment (magnetic material + non-magnetic material) should be close to the initial feed amount (50g).

[0047] Σ Gold grade (g / t): Meaning: The overall grade of the raw ore deduced from the magnetic and non-magnetic components.

[0048] Method of measurement: (Gold content in magnetic materials + Gold content in non-magnetic materials) / Total weight. This value should be highly consistent with the background value (0.25 g / t) of the raw ore direct analysis to prove the reliability of the experimental data.

[0049] The specific test results are shown in Table 1.

[0050] Table 1. Comparison of gold phase determination results and distribution rates in gravity flotation tailings The technical advantages of this invention can be clearly seen by comparing the gold distribution data in the table: Using the method of the present invention (Example 1), 94.1% of the gold was successfully enriched in the limonite phase, which accounts for only 7.24% of the total weight, and the grade was measured to be 3.25 g / t, with extremely low residual gold in the gangue.

[0051] In Comparative Example 1, which did not add ammonium sulfate, over 57% of the gold was lost along with the gangue due to material caking, resulting in severely distorted measurement results. In Comparative Example 2, which did not add sodium carbonate, although the gold recovery rate was acceptable, the measured grade was diluted to 2.35 g / t because the gangue impurities (inflated weight) were not effectively removed.

[0052] This fully demonstrates that the pore-forming effect of ammonium sulfate and the modifying effect of sodium carbonate are both indispensable for achieving accurate phase determination of fine-grained, refractory gold ores.

[0053] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for determining the gold content of limonite in gravity flotation tailings, characterized in that, Includes the following steps: Step S1: Take a sample of gravity flotation tailings, add a composite reducing agent and mix evenly to obtain a mixture; Step S2: Place the mixture in a sealed container for reduction calcination to obtain the calcined product; Step S3: Grind the roasted product, adjust the slurry, and then perform magnetic separation to obtain a magnetic product; Step S4: The magnetic product is subjected to oxidative roasting to obtain a concentrate sample; Step S5: The concentrate sample is subjected to acid dissolution treatment, and the net mass of limonite is calculated using the mass difference subtraction method; Step S6: Determine the gold content in the acid solution of the concentrate sample, and calculate the gold loading of limonite in the gravity flotation tailings based on the gold content and the net mass of the limonite.

2. The determination method as described in claim 1, characterized in that, In step S1, the composite reducing agent is composed of flour, activated carbon, anhydrous sodium carbonate and ammonium sulfate; the mass ratio of flour, activated carbon, anhydrous sodium carbonate and ammonium sulfate is 1:0.5~2:0.05~0.15:0.05~0.

1.

3. The determination method as described in claim 1, characterized in that, In step S1, the mass ratio of the gravity flotation tailings sample to the composite reducing agent is 1.5~3:

1.

4. The determination method as described in claim 1, characterized in that, In step S2, a carbon powder sealing layer is provided at the opening of the sealed container.

5. The determination method as described in claim 1, characterized in that, In step S2, the reduction calcination adopts a segmented heating method, specifically including: First stage: Increase the temperature to 200-400℃ at a rate of 5-10℃ / min, and hold for 20-60min; Second stage: Continue to raise the temperature to 650~810℃ and keep it warm for 1~3 hours; After the heat preservation period, the furnace is cooled to room temperature.

6. The determination method as described in claim 1, characterized in that, In step S3, the fineness of the grinding is controlled such that the particle size of -0.074mm accounts for more than 85%.

7. The determination method as described in claim 1, characterized in that, Step S3 specifically includes: adding water to the roasted product after grinding to form a slurry, adding sodium hexametaphosphate as a dispersant, and performing a primary magnetic separation; further slurrying the magnetic minerals obtained from the primary magnetic separation, and treating them with ultrasonic cavitation for a predetermined time, and then refining them under the same magnetic field conditions to obtain magnetic products; the magnetic field strength of the primary magnetic separation and the refining is 100~160mT.

8. The determination method as described in claim 1, characterized in that, In step S4, the oxidative calcination temperature is 600~800℃ and the time is 1~2h.

9. The determination method as described in claim 1, characterized in that, Step S5 specifically includes: S51: Weigh the concentrate sample with a mass of m0; S52: Dissolve the concentrate sample in dilute nitric acid, separate the solid and liquid, dry and weigh to obtain the primary slag weight W1; S53: Dissolve the residue obtained in step S52 by adding a mixed acid of concentrated hydrochloric acid and concentrated nitric acid, separate the solid and liquid, dry and weigh it to obtain the secondary residue weight W2. S54: Calculate the net mass of limonite using the formula mFe=W1-W2.

10. The determination method as described in claim 9, characterized in that, Step S6 specifically includes: The filtrate produced in step S53 is collected, concentrated by heating, and digested with aqua regia. It is then converted into hydrochloric acid medium by acid removal. The converted solution is enriched with gold through an adsorption medium, and then desorbed using thiourea. The gold content in the desorbed solution is determined. The adsorption medium is activated carbon or polyurethane foam.

Images