Method for improving recovery rate of ultra-micro-fine particle disseminated gold ore through multi-process cooperation

Abstract

The invention discloses a method for improving the recovery rate of ultra-micro-fine particle disseminated gold ore through multi-process cooperation, and belongs to the field of wet gold leaching. According to different occurrence states of the ultra-fine particle gold ore, staged and targeted recovery is sequentially carried out according to flotation, magnetic separation, alkaline leaching pretreatment and cyanidation leaching. Or sequentially performing staged and targeted recovery according to alkaline leaching pretreatment, cyanidation leaching, cyanide breaking, flotation and magnetic separation. According to the method, by means of a multi-process collaborative process, staged accurate recovery of gold in different occurrence states in the ultra-fine particle gold ore is achieved, the total recovery rate of gold is remarkably increased, the process is mild, the cost is controllable, the environmental protection property is good, a new technical scheme is provided for efficient recovery of the ultra-fine particle gold ore difficult to treat, and the method has wide industrial application prospects.

Description

Technical Field

[0001] This invention belongs to the field of wet gold leaching technology in gold ore beneficiation, specifically involving a multi-process synergistic recovery method for difficult-to-process gold ores with extremely fine-grained dissemination and complex occurrence states. Background Technology

[0002] Extremely fine-grained gold deposits are characterized by their fine gold mineral distribution (mostly below 5μm, with some being submicroscopic or ultramicroscopic gold below 0.5μm) and complex occurrence states, often encapsulated by sulfide minerals, quartz, and other minerals, making effective recovery difficult with conventional single-process methods. In existing technologies, the whole-sludge cyanidation leaching process achieves a gold leaching rate of only about 52.96%, while flotation processes struggle to exceed 40% recovery due to the weak association between gold and sulfide minerals. Furthermore, enhanced processes such as high-temperature, high-pressure oxidation present challenges due to high equipment investment, high operating costs, and significant environmental impact.

[0003] In existing technologies, although there have been attempts at combined flotation and cyanide leaching processes, the gold in different occurrence states has not been precisely recovered in stages. The recovery of gold encapsulated on weakly magnetic carriers is lacking, and the alkaline leaching pretreatment is insufficient, resulting in poor dissociation of gold encapsulated in quartz. The overall recovery rate still needs to be improved.

[0004] For example, Chinese invention patent application CN104694764A discloses "an enhanced leaching method for fine-grained gold encapsulation." This method involves adding gold-bearing materials such as cyanide slag, pyrite cinder, pyrite sulfate slag, or gold-bearing sulfide ore roasted sand to a water-based solvent along with gold leaching agents, pH adjusters, oxidants, and dispersants for ball milling and leaching. This yields an ultrafine leaching slurry, which is then transferred to a high-pressure reactor. Gold leaching agents, oxidants, and a water-based solvent are added, followed by the introduction of air or oxygen-enriched air for pressurized leaching. The leaching is then filtered to obtain a gold-bearing solution and leaching residue. This method is simple, easy to operate, and can achieve efficient leaching of fine-grained gold-encapsulated materials. However, it uses a pressurized leaching method in a high-pressure reactor. Furthermore, this method does not incorporate flotation, which is detrimental to improving the gold recovery rate of fine-grained gold ore.

[0005] Therefore, it is of great significance to develop a phased, targeted recovery method for ultra-fine-grained gold ore that is highly synergistic in process and cost-controllable. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method for improving the recovery rate of ultrafine-grained gold ore through multi-process synergy. By optimizing the process and combining processes, the total gold recovery rate is significantly improved.

[0007] The technical solution of the present invention is as follows: A method for improving the recovery rate of extremely fine-grained disseminated gold ore through multi-process synergy, characterized by proceeding according to either scheme (I) or scheme (II): Scheme (1): Raw ore flotation is used to recover gold encapsulated in sulfide minerals and exposed / semi-exposed gold; magnetic separation of flotation tailings is used to recover gold encapsulated in weakly magnetic carriers; oxidative alkaline leaching pretreatment of magnetic separation tailings is used to break quartz encapsulation, oxidize sulfide minerals, and convert encapsulated gold into exposed gold; the pH of the slurry after alkaline leaching pretreatment is adjusted to 11-12, and sodium cyanide leaching is used for 60-72 hours to recover quartz encapsulated gold and the remaining exposed gold; the above steps are carried out in sequence. Option (II): The raw ore undergoes oxidative alkaline leaching pretreatment to break up quartz inclusions and oxidize sulfide minerals, converting the included gold into exposed gold; the pH of the slurry after alkaline leaching pretreatment is adjusted to 11-12, and sodium cyanide is used for leaching for 60-72 hours to recover the liberated gold; cyanide residue is treated to break down cyanide to recover unleached gold inclusions and intercalated gold in the cyanide residue; flotation; magnetic separation of flotation tailings is used to recover residual magnetic carrier gold inclusions; the above steps are carried out sequentially.

[0008] Preferably, the raw ore flotation steps of Scheme (I) are as follows: the raw ore is ground to -200 mesh to account for 75~80%, and a "one rougher, three cleaners, three scavengers" flotation process is adopted, with copper sulfate as the activator and isoamyl xanthate and JD-3 in a mass ratio of (1.5~2.5):1 as collectors; the amount of copper sulfate added is 500~700g / t; the raw ore flotation steps of Scheme (II) are as follows: "one rougher, three cleaners, three scavengers" flotation is carried out.

[0009] Preferably, in the magnetic separation step of flotation tailings in both Scheme (I) and Scheme (II), the magnetic field strength is 2800~3200 Oe.

[0010] Preferably, in the oxidative alkali leaching pretreatment of scheme (I) or scheme (II), the magnetic separation tailings slurry concentration is 35-40%, the initial NaOH concentration is 1.2-1.5%, an oxidant and a catalyst are added, and air is introduced for oxidation treatment; the reaction endpoint of the oxidative alkali leaching pretreatment is determined by the change in oxidation-reduction potential; the oxidant is sodium percarbonate with a concentration of 0.08-0.12 g / L slurry; the catalyst is a composite catalyst composed of copper sulfate pentahydrate and nickel sulfate, wherein the initial concentration of copper sulfate pentahydrate is 0.02-0.03 g / L slurry, and the initial concentration of nickel sulfate is 0.001-0.003 g / L slurry; the aeration rate is 0.16 m³ / h.

[0011] Preferably, in the cyanide residue cyanide removal process of scheme (II), the Inco process is used for cyanide removal treatment, and the cyanide removal agents are sodium metabisulfite and copper sulfate.

[0012] Preferably, the flotation and leaching properties of the extremely fine-grained gold ore are determined by process mineralogical analysis or experimental methods to determine a suitable scheme; if the ore is determined to have good flotation properties, it is processed according to scheme one; if the ore is determined to have good leaching properties, it is processed according to scheme two.

[0013] More preferably, the scheme selection step adopts experimental methods, and the experimental steps are as follows: A roughing test is conducted according to conventional gold ore flotation conditions: pulp concentration 30%~35%, pH value 7~9, xanthate dosage 50~100g / t, and pine oil dosage 20~30g / t, and the gold flotation recovery rate is calculated; if the flotation recovery rate > the upper limit of the flotation recovery rate FH MAX If the flotation recovery rate is less than the lower limit of the flotation recovery rate FH, then choose option one; MIN If the flotation recovery rate is within the range of FH, then option two is selected; MAX With FH MIN Between these points, the following steps are taken: grinding the raw ore to -200 mesh (75%~85%), slurry concentration (30%~35%), sodium cyanide dosage (500~800g / t ore), slurry pH (10~11), and leaching time (24h) to conduct an alkaline leaching pretreatment + cyanidation test, and calculate the cyanide leaching rate. If the cyanide leaching rate ≥ K, then select Scheme 2; if the cyanide leaching rate < K, then select Scheme 1.

[0014] More preferably, wherein FH MAX =30%, FH MIN =20%, K=50%.

[0015] Preferably, the gold minerals in the ultrafine-grained gold ore have a particle size ≤5μm, and the gold minerals are mainly hosted in sulfide minerals, quartz and weakly magnetic minerals; the main gold-bearing minerals are pyrite and quartz.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: First, this invention breaks away from the traditional mindset of single or simple combined processes, creating a multi-process synergistic recovery system that "tailors strategies to gold types and tackles problems step by step." This system is not a simple accumulation of processes, but rather an organic integration based on a deep understanding of the complex occurrence states of extremely fine-grained gold ore, precisely liberating and recovering gold with different inclusion characteristics. Two schemes can be flexibly selected according to the ore properties, offering broad adaptability. Specifically, this invention, targeting different occurrence states of extremely fine-grained gold ore, first uses process mineralogical analysis or experimental methods to determine the flotation and leaching performance of the gold ore, thus determining the appropriate scheme. If the ore is determined to have good flotation properties, then a phased and targeted recovery is carried out sequentially: flotation, magnetic separation, alkaline leaching pretreatment, and cyanide leaching (Scheme 1). If the ore is determined to have good leaching properties, then a phased and targeted recovery is carried out sequentially: alkaline leaching pretreatment, cyanide leaching, cyanide removal, flotation, and magnetic separation (Scheme 2). This approach effectively overcomes the recovery blind spots of single processes. Experiments have shown that by selecting a processing scheme using the method of this invention, and implementing the corresponding processing scheme for different ores, the recovery rate can be significantly improved. Scheme 1 (flotation priority) is suitable for ores with good flotation properties and can obtain some gold concentrate in advance; Scheme 2 (leaching priority) is suitable for ores with relatively good leaching properties and has a simpler process. This flexibility greatly enhances the versatility of the process.

[0017] Secondly, this invention achieves precise, staged recovery of gold in different occurrence states from extremely fine-grained gold ores through a multi-process synergistic flow, significantly improving the total gold recovery rate. Furthermore, the process is mild, cost-controllable, and environmentally friendly, providing a new technical solution for the efficient recovery of extremely fine-grained, difficult-to-process gold ores, and has broad industrial application prospects. In Scheme 1 of this invention, the gold recovery rate of flotation is ≥38%, the recovery rate of gold encapsulated in magnetic carriers from the original ore is ≥0.6%, and the gold leaching rate of room temperature and pressure oxidation-alkali leaching pretreatment + cyanidation is ≥71%. In Scheme 2, the gold leaching rate of alkali leaching-cyanidation is ≥72%, the gold recovery rate of the original ore from cyanide slag flotation is ≥10.8%, and the recovery rate of the original ore from the tailings magnetic separation is ≥0.56%.

[0018] Third, in the optimized technical solution of this invention, an appropriate amount of sodium percarbonate is added as an oxidant during the alkaline leaching pretreatment process, and a Cu²⁺-Ni²⁺ composite catalytic system is adopted. The synergistic effect of Cu²⁺ and Ni²⁺ ions can more fully and effectively break the quartz inclusions, significantly improving the gold dissociation degree and creating more favorable conditions for cyanide leaching. Not only is the gold leaching rate significantly improved, but the alkaline leaching pretreatment time is also significantly shortened. In addition, since room temperature and pressure oxidative alkaline leaching is used, high-temperature and high-pressure equipment is not required, and the investment and operating costs are far lower than those of calcination, oxygen pressure leaching, and other enhanced processes. Detailed Implementation

[0019] The present invention will be further illustrated below with reference to embodiments and experimental data.

[0020] The core of this invention includes two main parts: a method for determining the conditions for switching between schemes and a method for processing schemes one and two.

[0021] To determine which of the two schemes of this invention, Scheme 1 and Scheme 2, the applicable conditions of the raw ore are met, the following small-scale experimental verification method is used, and the steps are as follows: A roughing test was conducted under conventional gold ore flotation conditions (pulp concentration 30%~35%, pH 7~9, xanthate dosage 50~100 g / t, pine oil dosage 20~30 g / t), and the gold flotation recovery rate was calculated. If the flotation recovery rate is >30% (30% is the upper limit of the flotation recovery rate FH), the gold recovery rate is considered higher. MAX If the ore has good flotation properties, then Scheme 1 should be selected; if the flotation recovery rate is <20% (20% is the lower limit of flotation recovery rate FH), then the ore is considered to have good flotation properties. MIN If the ore is deemed to have relatively good leaching properties, then option two should be selected.

[0022] If the flotation recovery rate is within (FH) MAX With FH MIN For ore with a content between 20% and 30%, conduct a supplementary test under conventional alkaline leaching pretreatment + cyanidation conditions (raw ore ground to -200 mesh, 75% to 85% content; slurry concentration 30% to 35%; sodium cyanide dosage 500 to 800 g / t ore; slurry pH 10 to 11; leaching time 24 h), and calculate the cyanide leaching rate. If the cyanide leaching rate is ≥50% (50% is the leaching rate judgment value K), then select Scheme 2; if the cyanide leaching rate is <50% (50% is the leaching rate judgment value K), then select Scheme 1.

[0023] The selection of the two process schemes is mainly based on three factors: the occurrence state of gold in the raw ore, the flotation performance of the carrier minerals, and the leaching compatibility of gold. Based on extensive process mineralogical analysis, this invention has determined that FH... MAX =20%, FH MIN =30%, K=50%.

[0024] The mineralogy analysis methods used in the process mainly include: (i) Analysis of the occurrence state of gold: Chemical phase analysis is used to determine the proportion of free gold, gold encapsulated in sulfide minerals, gold encapsulated in oxides, and gold encapsulated in silicates in the raw ore. Specifically, free gold is leached sequentially with neutral sodium chloride solution, gold encapsulated in sulfide minerals is leached with bromine water, and gold encapsulated in silicates is leached with a mixture of hydrochloric acid and hydrofluoric acid. The gold content and proportion of each phase are determined by atomic absorption spectrometry. (ii) Analysis of the characteristics of carrier minerals: The types, particle sizes, and degrees of liberation of sulfide minerals, as well as the intercalation relationship between gold and carrier minerals, are observed using optical microscopy and scanning electron microscopy (SEM-EDS). (iii) Quantitative analysis of the content of sulfide minerals, magnetic minerals, and gangue minerals in the ore is performed using X-ray diffraction (XRD). Example 1: Determination of Scheme Switching Conditions

[0025] This embodiment includes a test case for determining the switching conditions between two batches of ore raw materials.

[0026] Experimental Example (1) Ore raw materials: A batch of extremely fine-grained silicified breccia-type gold ore raw materials purchased in October 2025. The gold grade of the raw ore is 2.70 g / t, the gold mineral sputtering particle size is ≤5 μm, of which the proportion of submicroscopic gold ≤0.5 μm is 22.04%, the mercury content is 0.00968%, and the arsenic content is 0.08%.

[0027] First, conduct the following small-scale experiment: A roughing test was conducted under conventional gold ore flotation conditions (pulp concentration 32%, pH 8, xanthate dosage 80 g / t ore, pine oil dosage 20-30 g / t ore), and the gold flotation recovery rate was calculated. The test results showed a flotation recovery rate of 33.20%, indicating good ore flotation properties. The following treatment scheme was selected as Scheme One. The treatment method corresponds to Example Two.

[0028] Experimental Example (II) Ore raw materials: Another batch of extremely fine-grained silicified breccia-type gold ore raw materials purchased in September 2025, with a gold grade of 2.75 g / t, gold mineral sputtering particle size ≤5 μm, of which submicroscopic gold ≤0.5 μm accounted for 23.15%, mercury content 0.010%, and arsenic content 0.09%.

[0029] First, conduct the following small-scale experiment: A roughing test was conducted under conventional gold ore flotation conditions (32% pulp concentration, pH 8, xanthate dosage 80 g / t ore, pine oil dosage 20-30 g / t ore), and the gold flotation recovery rate was calculated. The test result was a flotation recovery rate of 26.20%. A supplementary test was conducted under conventional alkaline leaching pretreatment + cyanidation conditions: the raw ore was ground to approximately -200 mesh (80% concentration), pulp concentration 32%, sodium cyanide dosage 600 g / t ore, pulp pH 10.5, and leaching time 24 hours, and the cyanide leaching rate was calculated. The supplementary test result was a cyanide leaching rate of 52.60%, indicating good ore leaching properties. The following treatment scheme, corresponding to Example 3, was selected as Scheme 2. Example 2, Scheme (I) Example

[0030] Ore raw material: A batch of extremely fine-grained silicified breccia-type gold ore raw material purchased in October 2025. The gold grade of the raw ore is 2.70 g / t, the gold mineral distribution particle size is ≤5μm, of which submicroscopic gold with a particle size ≤0.5μm accounts for 22.04%, mercury content is 0.00968%, and arsenic content is 0.08%. Grinding to -200 mesh results in a purity of 80%.

[0031] 1. Flotation: Adjust pulp concentration to 40%, add 600g / t copper sulfate, 100g / t combined collector (isoamyl xanthate: JD-3=2:1), and 30g / t2 # Oil is subjected to flotation ("one roughing, three cleaning, and three scavenging") to obtain flotation concentrate (yield 7.41%, gold grade 13.51 g / t, recovery 38.18%) and flotation tailings.

[0032] 2. Magnetic separation: The flotation tailings are magnetically separated under a magnetic field of 3000 Oe to obtain magnetic concentrate (0.62% recovery rate relative to the original ore) and magnetic tailings (gold grade 1.73 g / t).

[0033] 3. Alkali leaching pretreatment: The magnetic separation tailings were slurry concentrated to 40%, and NaOH was added to a mass concentration of 1.33%. The aeration rate was 0.16 m³ / h. The alkali leaching pretreatment was carried out at room temperature and pressure for 36 hours. The oxidation potential dropped sharply from +540 mV to +480 mV, indicating that the sulfides were depleted and the pretreatment endpoint was reached.

[0034] 4. Cyanide leaching: After pretreatment, the slurry was filtered by pressure, the slurry concentration was adjusted to 40%, pH=11.5, sodium cyanide was added to a mass concentration of 0.05%, and leaching was carried out for 72 hours. The gold leaching rate was 71.10%.

[0035] The final gold recovery rate across all operations was 82.31%, an improvement of 29.35 percentage points compared to the conventional whole-sludge cyanidation process (gold recovery rate of 52.96%). Example 3, Scheme (II) Example

[0036] Ore raw materials: Another batch of extremely fine-grained silicified breccia-type gold ore raw materials purchased in September 2025, with a gold grade of 2.75 g / t, gold mineral sputtering particle size ≤5 μm, of which submicroscopic gold ≤0.5 μm accounts for 232.15%, mercury content 0.010%, and arsenic content 0.09%. Grinding to -200 mesh 80%.

[0037] 1. Alkali leaching pretreatment: The alkali leaching pretreatment operation is the same as the corresponding steps in Example 2. Alkali leaching pretreatment at room temperature and pressure for 35 hours resulted in a sharp drop in oxidation potential from +530mV to +475mV, indicating that the sulfides were depleted and the pretreatment endpoint was reached.

[0038] 2. Cyanide leaching: Adjust the slurry concentration to 40%, pH=11.5, add sodium cyanide to a mass concentration of 0.05%, and leach for 72 hours. Gold leaching rate: 72.59%.

[0039] 3. Cyanide residue cyanide removal: The inco process (2 kg / t of pyroxene, 0.2 kg / t of copper sulfate, reaction time 2 h) is used to remove cyanide.

[0040] 4. Flotation: After cyanide crushing, flotation is carried out ("one roughing, three cleaning, and three scavenging"). Cyanide slag flotation concentrate is obtained (gold recovery rate of 10.82% from the original ore).

[0041] 5. Magnetic separation: The magnetic field strength of the flotation tailings is 3000 Oe. Magnetic concentrate is obtained (gold recovery rate of 0.56% from the original ore).

[0042] Ultimately, the sum of the recovery rates for all operations was 83.97%. Example 4: Comparative Examples of Applicable Schemes for Different Ores

[0043] The ore raw material from Example 2 was processed using the method of Example 3. The final sum of gold recovery rates for all operations was 70.40%, significantly lower than the corresponding indicators for Example 2. Using the method of Example 2 to process the ore raw material from Example 3, the final sum of gold recovery rates for all operations was 73.85%, significantly lower than the corresponding indicators for Example 3.

[0044] It is evident that by selecting a processing scheme through the method of the present invention, and implementing the corresponding processing scheme for different ores, the recovery rate can be significantly improved. Example 5: Comparative Example of Optimization of Alkali Leakage Pretreatment Step Parameters

[0045] Alkali leaching pretreatment: The magnetic separation tailings slurry concentration was adjusted to 40%, and NaOH was added to a mass concentration of 1.33%. Sodium percarbonate was added as an oxidant (concentration of 0.10 g / L slurry), and copper sulfate pentahydrate and nickel sulfate were added as catalysts. The initial concentration of copper sulfate pentahydrate was 0.02 g / L slurry, and the initial concentration of nickel sulfate was 0.002 g / L slurry. The aeration rate was 0.16 m³ / h. Alkali leaching pretreatment was carried out at room temperature and pressure for 24 hours. The oxidation potential dropped sharply from +525 mV to +472 mV, indicating that the sulfides were depleted and the pretreatment endpoint was reached. Using the alkali leaching pretreatment method of this comparative example, the gold leaching rate was increased to 88.92%. Using the alkali leaching pretreatment method of this comparative example, the pretreatment time was shortened by about 32%.

Claims

1. A method for improving the recovery rate of ultrafine disseminated gold ore by multi-process synergy, characterized in that According to scheme (I) or scheme (II): Scheme (I): raw ore flotation is used for recovering gold in sulfide inclusions and bare / semi-bare gold; magnetic separation of flotation tailings is used for recovering gold in weakly magnetic carrier inclusions; oxidation and alkali leaching pretreatment of magnetic separation tailings is used for breaking quartz inclusions and oxidizing sulfide minerals, so that the gold inclusions are converted into bare gold; the ore slurry after alkali leaching pretreatment is adjusted to pH 11-12, and sodium cyanide leaching is used for 60-72 hours to recover gold in quartz inclusions and remaining bare gold; the above steps are sequentially performed; Scheme (II): raw ore oxidation and alkali leaching pretreatment is used for breaking quartz inclusions and oxidizing sulfide minerals, so that the gold inclusions are converted into bare gold; the ore slurry after alkali leaching pretreatment is adjusted to pH 11-12, and sodium cyanide leaching is used for 60-72 hours to recover the dissociated gold; cyanide residue is treated to recover the gold inclusions and intergrown gold in the cyanide residue which has not been leached; flotation; magnetic separation of flotation tailings is used for recovering residual gold in magnetic carrier inclusions; the above steps are sequentially performed.

2. The method for improving the recovery rate of ultrafine gold ore according to claim 1, characterized in that: The raw ore flotation step of scheme (I) is: the raw ore is ground to 75-80% of -200 mesh, and a "one roughing, three cleaning and three scavenging" flotation process is used, with copper sulfate as the activator and isopentyl xanthate and JD-3 as the collectors at a mass ratio of (1.5-2.5):1; the copper sulfate addition amount is 500-700 g / t; the raw ore flotation step of scheme (II) is: "one roughing, three cleaning and three scavenging" flotation is performed.

3. The method for improving the recovery rate of ultrafine gold ore according to claim 1, characterized in that: In the magnetic separation step of the flotation tailings of scheme (I) and scheme (II), the magnetic field strength is 2800-3200 Oe.

4. The method for improving the recovery rate of ultrafine gold ore according to claim 1, characterized in that: In the oxidation and alkali leaching pretreatment of scheme (I) or scheme (II), the slurry concentration of the magnetic separation tailings is 35-40%, the initial concentration of NaOH is 1.2-1.5%, an oxidizing agent and a catalyst are added, and air is introduced for oxidation treatment; the reaction endpoint of the oxidation and alkali leaching pretreatment is determined by the change of the oxidation-reduction potential; the oxidizing agent is sodium percarbonate with a concentration of 0.08-0.12 g / L of ore slurry; the catalyst is a composite catalyst composed of copper sulfate pentahydrate and nickel sulfate, wherein the initial concentration of copper sulfate pentahydrate is 0.02-0.03 g / L of ore slurry, and the initial concentration of nickel sulfate is 0.001-0.003 g / L of ore slurry; the air charge is 0.16 m³ / h.

5. The method for synergistically improving the recovery rate of ultrafine gold particles according to claim 1, characterized in that: In the cyanide residue breaking of scheme (II), inco method is used for cyanide breaking treatment, and sodium pyrosulfite and copper sulfate are used as cyanide breaking reagents.

6. The method for improving the recovery rate of ultrafine gold particles according to any one of claims 1 to 5, characterized in that: Through process mineralogy analysis or experimental means, the flotation and leaching properties of the extremely fine-grained gold ore are determined to determine the appropriate scheme; if the ore flotation is determined to be good, scheme I is used for treatment; If the ore leaching is determined to be good, scheme II is used for treatment.

7. The method for improving the recovery rate of ultrafine gold ore according to claim 6, characterized in that: The scheme selection step adopts a test method, and the test step is as follows: according to the conventional gold mine flotation conditions, the pulp concentration is 30%-35%, the pH value is 7-9, the dosage of xanthate is 50-100 g / t, and the dosage of pine oil is 20-30 g / t, a roughing test is carried out, and the gold flotation recovery rate is calculated; if the flotation recovery rate > the upper limit value FH MAX of the flotation recovery rate, scheme one is selected; if the flotation recovery rate < the lower limit value FH MIN of the flotation recovery rate, scheme two is selected; if the flotation recovery rate is between FH MAX and FH MIN , according to the following: the raw ore is ground to 75%-85% of-200 mesh, the pulp concentration is 30%-35%, the dosage of sodium cyanide is 500-800 g / t of ore, the pulp pH value is 10-11, and the leaching time is 24 h, a one-time alkali leaching pretreatment + cyanidation test is carried out, and the cyanide leaching rate is calculated; if the cyanide leaching rate is greater than or equal to K, scheme two is selected; if the cyanide leaching rate is less than K, scheme one is selected.

8. The method for improving the recovery rate of ultrafine gold ore according to claim 7, characterized in that: where FH MAX = 30%, FH MIN = 20%, K = 50%.

9. The method for improving the recovery rate of ultrafine disseminated gold ore according to claim 1, characterized in that: The extremely fine-grained gold ore has gold mineral inclusions with a particle size of ≤5 μm, and the gold minerals mainly occur in sulfide minerals, quartz and weakly magnetic minerals; the main gold-bearing minerals are pyrite and quartz.