A method for enriching gold iron by adopting carbonaceous gold ore and cyanide tailings collaborative roasting-magnetic separation

Abstract

The application discloses a method for cooperatively roasting and magnetically separating and enriching gold and iron by using carbonaceous gold ore and cyanidation tailings, fully utilizes the mineralogical characteristics of the carbonaceous gold ore and the cyanidation tailings, and roasts the carbonaceous gold ore and the cyanidation tailings after cold-pressing and forming in an air-tight manner, so that the hematite in the cyanidation tailings is controllably reduced into magnetite by carbonaceous substances and pyrite in the carbonaceous gold ore, iron concentrate is obtained through roasting, grinding, screening and magnetic separation, and gold is maximally enriched in the tailings of the magnetic separation and is recovered through a subsequent leaching process. In the roasting process, the hematite in the cyanidation tailings and the pyrite in the minerals have redox reactions with carbon monoxide, elemental carbon and the pyrite generated by pyrolysis of the organic carbon, which not only eliminates the gold-killing effect of the organic carbon, but also destroys the pyrite and hematite inclusions of gold, and simultaneously realizes the efficient separation and comprehensive utilization of gold and iron in the carbonaceous gold ore and the cyanidation tailings.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical engineering technology, specifically relating to a method for enriching gold and iron by co-roasting carbonaceous gold ore and cyanide tailings with magnetic separation. Background Technology

[0002] Carbonaceous gold ore is one of the most difficult-to-process gold resources. Estimated reserves of carbonaceous gold ore in the gold industry exceed 4000 tons, accounting for approximately 8% of total gold resources and over 20% of proven gold reserves. Carbonaceous gold ore typically contains high levels of carbonaceous matter, sulfides, and quartz. Its difficulty in processing stems primarily from the fact that carbonaceous matter adsorbs gold-cyanide complex ions generated during cyanide leaching, leading to a significant reduction in leaching efficiency—a phenomenon known as "gold robbery." Additionally, some fine gold particles are heavily encapsulated by pyrite and other minerals, making contact with the leaching agent difficult, further contributing to low leaching rates. Therefore, carbonaceous gold ore is considered one of the most challenging types of gold ore to process.

[0003] For this type of gold ore, direct cyanide leaching results in a low leaching rate. Therefore, researchers both domestically and internationally have proposed a pretreatment-cyanide combined process to improve leaching efficiency. This process mainly focuses on eliminating carbonaceous matter and suppressing its negative impact on gold leaching, specifically including roasting oxidation, hot-pressing oxidation, microwave oxidation, and biological oxidation methods. Oxidative roasting can effectively improve the leaching rate of carbonaceous gold ores and is simple to operate. However, this method consumes a large amount of energy, and the cost of removing SO2 and As from the flue gas is also high; at the same time, iron mainly exists in the form of hematite during oxidative roasting, and the cyanide tailings (cyanide red slag) formed after cyanide leaching also need further harmless treatment and resource utilization.

[0004] In addition, gold extraction currently mainly uses the cyanidation method. Currently, roasted cyanide tailings formed after oxidative roasting and cyanidation leaching of carbonaceous gold ores and refractory gold ores containing arsenic or sulfur account for more than half of the existing cyanidation tailings. The iron content in these tailings generally reaches over 30%, significantly higher than the average grade of mined iron ore. However, the iron in these tailings is mostly fine-grained hematite, characterized by small particle size, large specific surface area, complex intergrowth, and poor selectivity. It is not suitable for direct blast furnace smelting of iron and requires pretreatment such as reduction roasting and magnetic separation enrichment before comprehensive utilization.

[0005] CN201910927888.6 describes a pretreatment method for carbonaceous gold ore, its preparation method, and a gold extraction method. The method involves first pressing carbonaceous gold concentrate powder into lumps, then subjecting the lumps to a vacuum pressure not exceeding 20 Pa and a temperature of 1000 °C. 1200℃, roasting time is 50 minutes At 90 minutes, the pretreated carbonaceous gold concentrate is finally subjected to cyanide leaching. This method can effectively pretreat carbonaceous gold concentrate, but it suffers from problems such as excessively high roasting temperature, incomplete carbon utilization, and high cost. CN113564371A introduces a method for comprehensive resource recovery and utilization of roasted cyanide tailings. The roasted cyanide tailings are mixed with composite additives and then roasted and reduced in a closed furnace. After cooling, roasted slag is obtained. After grinding and non-cyanide gold extraction, the gold-extracting tailings are then separated and enriched with iron and silicon using magnetic separation. The composite additive selected in this patent is a mixture of carbon and FeS2. Additional additives will increase production costs and cause unnecessary resource waste. Summary of the Invention

[0006] To address the problems of gold robbery and gold encapsulation in existing carbonaceous gold ores, as well as the low resource utilization rate of cyanide tailings, the present invention aims to provide a method for the co-roasting and magnetic separation and enrichment of gold and iron from carbonaceous gold ores and cyanide tailings. This invention can fully utilize the mineralogical characteristics of carbonaceous gold ores and cyanide tailings, effectively eliminating the gold robbery effect of organic carbon in carbonaceous gold ores while reducing hematite in cyanide tailings, thus achieving efficient separation and comprehensive utilization of gold and iron from carbonaceous gold ores and cyanide tailings.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for enriching gold and iron by co-roasting carbonaceous gold ore and cyanide tailings followed by magnetic separation includes the following steps: Carbonaceous gold ore powder, cyanide tailings powder and additive powder are thoroughly mixed, then cold-pressed and dried to obtain a blocky solid; the additive is at least one of calcium carbonate powder and lime powder; the mass ratio of carbonaceous gold ore powder, cyanide tailings powder and additive powder is (10-27):(10-24):(1-5). The blocky solid is roasted, ground, and sieved to obtain powder. The powder is mixed with water to form a mineral slurry solution; The slurry solution is subjected to magnetic separation to obtain iron concentrate and magnetic separation tailings slurry; The magnetic separation tailings slurry is then leached for gold.

[0008] Preferably, the carbonaceous gold ore powder has a particle size of -0.074 mm and a mass percentage of particles of 90% or more.

[0009] Preferably, when the block solid is roasted, the roasting process is carried out in the absence of air, the roasting temperature is 600℃~900℃, and the roasting time is 30min~90min.

[0010] Preferably, the powder has a particle size of -0.074 mm and a mass percentage of particles of 90% or more.

[0011] Preferably, when the powder and water are used to make a slurry solution, the solid-liquid ratio of the powder to the water is 1:(1.5~2).

[0012] Preferably, when performing magnetic separation on the slurry solution, the magnetic field strength is 0.1 T to 0.3 T.

[0013] Preferably, when leaching gold from the magnetic separation tailings slurry, lime is used to adjust the pH value of the magnetic separation tailings slurry to 10-13, cyanide or environmentally friendly reagents are used to leach gold, and air is continuously circulated and stirred during the leaching process.

[0014] Preferably, 2.5-25g of cyanide or environmentally friendly reagent is added to each kilogram of magnetic separation tailings slurry, and the leaching time is 12-24 hours.

[0015] Preferably, in the above scheme, the carbonaceous gold ore powder is raw ore powder and / or flotation gold concentrate powder, and the total carbon content in the carbonaceous gold ore powder is 5% to 15% of the mass of the carbonaceous gold ore powder.

[0016] Preferably, in the above scheme, the iron minerals in the cyanide tailings powder exist in the form of hematite, and the hematite content is 20% to 50% of the mass of the cyanide tailings powder; The cyanide tailings powder is obtained by cyanide leaching after pretreatment of at least one of sulfur-containing gold concentrate, carbonaceous gold ore and Carlin-type gold ore through oxidative roasting. Alternatively, the cyanide tailings powder may be any one of the following forms of cyanide tailings or a mixture of two or more forms of cyanide tailings: The first form: cyanide tailings obtained from sulfur-containing gold concentrate after oxidative roasting pretreatment and cyanide leaching. The second form: cyanide tailings powder is obtained by cyanide leaching of carbonaceous gold ore after oxidative roasting pretreatment. The third form: cyanide tailings powder is obtained by cyanide leaching of Carlin-type gold ore after oxidative roasting pretreatment.

[0017] The present invention has the following beneficial effects: In this invention, a method for co-roasting and magnetic separation of gold and iron using carbonaceous gold ore and cyanide tailings is employed. The lumpy solid is roasted, and during this process, a pyrolysis reaction occurs between the carbonaceous material in the carbonaceous gold ore and the pyrite in the cyanide tailings. Additionally, the pyrolysis products carbon, carbon monoxide, and pyrite undergo redox reactions with hematite. Under the synergistic effect of the carbonaceous gold ore and the cyanide tailings, Fe2O3 in the cyanide tailings is reduced to magnetic Fe3O4. Subsequently, magnetic separation can be used to enrich and recover the iron concentrate. Furthermore, leaching methods (such as cyanidation or environmentally friendly reagent leaching) are used to recover gold from the magnetic tailings. This invention combines the removal of carbonaceous matter from carbonaceous gold ore and cyanide tailings, the destruction of minerals encapsulated in pyrite and hematite, and the dissociation and enrichment of gold. The process is short, simple, and controllable, making full use of the reducing effect of carbon and pyrite, and simultaneously achieving the rational matching and resource utilization of multiple valuable components in carbonaceous gold ore and cyanide tailings.

[0018] The present invention has the following characteristics: (1) During the co-roasting process, the hematite in the cyanide tailings undergoes a redox reaction with the carbon and pyrite in the carbonaceous gold ore, thus solving the "gold robbery effect" of carbon and the problem of gold being encapsulated by hematite and pyrite. (2) Magnetic separation yields iron concentrate mainly composed of magnetite, which can be directly used as raw material in the blast furnace ironmaking system. (3) The co-roasting process fully utilizes the reducing effect of carbon and pyrite in the carbonaceous gold ore, and does not produce flue gas containing sulfur dioxide. Attached Figure Description

[0019] Figure 1 This is a diagram showing the complete equipment connection of the method for co-roasting and magnetic separation to enrich gold and iron using carbonaceous gold ore and cyanide tailings in this invention. Figure 2(a) shows the XRD analysis results of the carbonaceous gold ore used in the embodiments of the present invention; Figure 2(b) shows the XRD analysis results of the cyanide tailings used in the embodiments of the present invention.

[0020] In the diagram, 1-feeding system, 2-sluice box, 3-roasting furnace, 4-magnetic separator, 5-leaching tank, 6-filtration system, 7-slurry pump. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0022] Based on the mineralogical characteristics of carbonaceous gold ore and cyanide tailings, this invention innovatively proposes a method for the co-roasting and magnetic separation of gold and iron from carbonaceous gold ore and cyanide tailings. This invention can fully utilize the carbonaceous matter in carbonaceous gold ore and the pyrite sulfide minerals to reduce and roast the hematite in the cyanide tailings, while consuming the "gold-robbing" carbonaceous matter in the carbonaceous gold ore and exposing the gold encased in the sulfide minerals, thus achieving efficient separation and comprehensive utilization of gold and iron from carbonaceous gold ore and cyanide tailings.

[0023] The complete process equipment diagram for the co-roasting-magnetic separation enrichment of gold and iron using carbonaceous gold ore and cyanide tailings in this invention is attached. Figure 1 As shown.

[0024] This invention employs a method for co-roasting and magnetic separation of carbonaceous gold ore and cyanide tailings to enrich gold and iron, comprising the following steps: Step one: After thoroughly mixing the carbonaceous gold ore powder, cyanide tailings powder, and additives in a certain proportion, use FYD... 40 A type A benchtop powder press is used to press a cylindrical sample 1 with a size of Ф2cm×1cm at 1MPa~1.2MPa (sample 1 can also be other forms of block structure; the following embodiments of the present invention use a cylinder as an example for illustration), and the sample 1 is dried in a forced-air drying oven. The additives are at least one of calcium carbonate powder and lime powder; the mass ratio of carbonaceous gold ore powder, cyanide tailings powder, and additive powder is (10-27):(10-24):(1-5); the carbonaceous gold ore powder is raw ore powder and / or flotation gold concentrate powder, and the total carbon content in the carbonaceous gold ore powder is 5%~15% of the mass of the carbonaceous gold ore powder; the cyanide tailings powder contains at least one of sulfur gold concentrate, carbonaceous gold ore, and Carlin-type gold ore, which undergoes oxidative roasting pretreatment, followed by cyanide leaching to obtain... The cyanide tailings powder is obtained from cyanide tailings; or, the cyanide tailings powder is any one of the following forms of cyanide tailings or a mixture of two or more forms of cyanide tailings: First form: cyanide tailings obtained by oxidative roasting pretreatment of sulfur-containing gold concentrate followed by cyanide leaching; Second form: cyanide tailings powder obtained by oxidative roasting pretreatment of carbonaceous gold ore followed by cyanide leaching; Third form: cyanide tailings powder obtained by oxidative roasting pretreatment of Carlin-type gold ore followed by cyanide leaching. The iron minerals in the cyanide tailings powder exist in the form of hematite, with a hematite content of 20%–50% of the cyanide tailings powder mass; before cold pressing, the particle size of both the carbonaceous gold ore powder and the cyanide tailings powder is -0.074 mm, accounting for more than 90%; Step two: Place the dried sample 1 in a corundum ceramic boat, put it into the quartz tube of a vacuum tube furnace, turn on the rotary vane vacuum pump, and heat and calcine. When the temperature reaches 600℃~900℃, hold it at that temperature for 30~90 minutes, then let it cool naturally to room temperature, turn off the vacuum pump, and complete the calcination pretreatment to obtain sample 2 of the present invention.

[0025] Step 3: Grind and sieve the sample 2 obtained in Step 2 to obtain sample 2 powder. The fineness of sample 2 powder is that the particle mass of -0.074 mm accounts for more than 90%. Mix sample 2 powder with water at a solid-liquid ratio of 1:(1.5~2) to prepare a slurry solution. Perform magnetic separation on the slurry solution under a magnetic field strength of 0.1~0.3T.

[0026] Step four: After magnetic separation, adjust the pH of the magnetic separation tailings slurry to 10-13 using lime. Then, add cyanide or an environmentally friendly leaching agent to the slurry. During the leaching process, continuously aerate and stir for 12-24 hours to leach gold. 2.5-25g of cyanide or environmentally friendly reagent should be added per kilogram of magnetic separation tailings slurry.

[0027] Specifically, in the technical solution of this invention, when carbonaceous gold concentrate powder and cyanide tailings powder are added to a certain amount of additives and pressed into sample 1, the sample needs to be thoroughly stirred and then cold-pressed to prepare a blocky solid with a certain compressive strength. This is because the main reaction that occurs during the co-roasting process is the solid-phase redox reaction between carbon and hematite. Cold-pressing the mixed sample can significantly improve the reaction efficiency between carbonaceous gold concentrate powder and cyanide tailings powder, which is conducive to the complete occurrence of the reaction.

[0028] Furthermore, the addition of additives such as calcium oxide and calcium carbonate during cold pressing can significantly reduce the roasting temperature, save energy, and prevent the formation of iron-gold alloys and Fe2SiO4-encapsulated minerals. Firstly, when sample 1 is roasted in an air-isolated environment, the main reactions are the dehydration of goethite, vanadium mica, kaolinite, and dolomite in the carbonaceous gold concentrate, as well as the thermal decomposition of pyrite and pyrrhotite and the reduction of hematite. Iron oxides are reduced in the order Fe2O3→Fe3O4→FeO→Fe. With increasing roasting temperature, the reduction reaction of hematite becomes more complete, and the greater the consumption of carbonaceous matter in the carbonaceous gold concentrate. However, when calcium oxide and calcium carbonate are added, the decomposition of the additives at roasting temperatures of 700℃ and 800℃ significantly increases the partial pressure of CO2 around the minerals, promoting the forward reaction CO2 + C = 2CO. This can consume some of the carbonaceous matter in carbonaceous gold ores. Furthermore, the gas released after the reaction of CO2 and C increases the porosity of the mineral surface, promoting the reduction of hematite. Secondly, at excessively high roasting temperatures, iron and gold easily form iron-gold alloys, and the reaction of FeO with SiO2 easily forms Fe2SiO4, which encapsulates the minerals. Additives such as calcium oxide and calcium carbonate can prevent the formation of iron-gold alloys and Fe2SiO4 encapsulation by lowering the roasting temperature. On the other hand, the additives also react with Fe2SiO4 to form calcium silicate, carbon monoxide, carbon dioxide, and elemental iron. Reducing the formation of iron-gold alloys and Fe2SiO4 can effectively prevent gold from entering the iron concentrate along with Fe2SiO4-encapsulated minerals during magnetic separation, thus facilitating the separation of gold and iron.

[0029] Furthermore, Sample 2 needs to be ground until the mass ratio of particles with a fineness of -0.074 mm is above 90%. Increasing the grinding fineness increases the dissociation of gold monomers or increases the surface area of ​​exposed gold, which is beneficial for more thorough separation of gangue minerals and magnetic materials during magnetic separation, and also increases the gold leaching rate. If the magnetic field strength is too low during magnetic separation, the magnetic products and gangue products will not separate, causing all minerals to concentrate in the tailings, resulting in low iron recovery. If the magnetic field strength is too high, gangue minerals may be separated from the magnetic products, resulting in a lower iron grade in the magnetic concentrate. Both of these are detrimental to the separation and recovery of gold and iron. Therefore, the magnetic field strength needs to be controlled at 0.1–0.3 T during the magnetic separation process.

[0030] In the following embodiments of the present invention, the carbonaceous gold concentrate is flotation gold concentrate from a carbonaceous gold mine in Shaanxi Province, and the cyanide tailings are gold extraction tailings from a gold smelting enterprise in Henan Province. The main elemental analysis and gold phase analysis results of the two raw materials are shown in Tables 1 and 2, and the XRD analysis results are shown in Figures 2(a) and 2(b). The Au grade of the carbonaceous gold concentrate is 16.77 g / t, and the gold is mainly encapsulated by sulfide minerals, with a total carbon mass percentage of 11.52%. The Fe2O3 mass percentage in the cyanide tailings is as high as 44.03%, and the gold grade is 1.60 g / t, mainly encapsulated by Fe2O3, with a very serious gold encapsulation phenomenon.

[0031] Table 1

[0032] Table 2

[0033] Tables 1 and 2 show that the high carbon content in carbonaceous gold concentrate leads to a strong "gold-stealing" effect and a high gold encapsulation rate, making direct gold leaching difficult. Cyanide tailings contain a large amount of hematite, which can be used to oxidize carbon and pyrite in carbonaceous gold ore, thereby reducing the "gold-stealing" effect of carbonaceous matter and the gold encapsulation by pyrite.

[0034] Example 1: This embodiment employs a method for co-roasting and magnetic separation of carbonaceous gold ore and cyanide tailings to enrich gold and iron, including the following steps: 1. Mix 20 g of carbonaceous gold concentrate powder, 20 g of cyanide tailings powder and 5 g of CaCO3 powder, press them into blocks and dry them to obtain sample 1; 2. Sample 1 was heated to 700℃ in a tube furnace for calcination. After the calcination temperature was maintained for 90 min, the sample was cooled to room temperature with the furnace. After calcination, the sample was cooled to obtain sample 2. 3. Sample 2 was ground and sieved, and then mixed with water at a solid-liquid ratio of 1:2 to prepare a slurry solution. The slurry solution was then subjected to magnetic separation under a magnetic field strength of 0.2 T to obtain iron concentrate and magnetic separation tailings slurry.

[0035] 4. Perform cyanide leaching on the magnetic separation tailings slurry for 24 hours, control the pH value of the magnetic separation tailings slurry to 13, and add cicadas at a rate of 25 g / kg (meaning 10 g of cicadas are added to every kilogram of magnetic separation tailings solution).

[0036] The iron grade in the magnetic separation concentrate obtained in this embodiment is 53.45%, and the iron recovery rate is 73.64%; the gold leaching rate after cyanidation leaching of the magnetic separation tailings is 64.90%.

[0037] Example 2: This embodiment employs a method for co-roasting and magnetic separation of carbonaceous gold ore and cyanide tailings to enrich gold and iron, including the following steps: 1. Mix 20 g of carbonaceous gold concentrate powder, 20 g of cyanide tailings powder and 5 g of CaCO3 powder, press them into blocks and dry them to obtain sample 1; 2. Sample 1 was heated to 800℃ in a tube furnace for calcination. After the calcination temperature was maintained for 60 min, the sample was cooled to room temperature with the furnace. After calcination, the sample was cooled to obtain sample 2. 3. Sample 2 was ground and sieved, and then mixed with water at a solid-liquid ratio of 1:2 to prepare a slurry solution. The slurry solution was then subjected to magnetic separation under a magnetic field strength of 0.2 T to obtain iron concentrate and magnetic separation tailings slurry.

[0038] 4. The magnetic separation tailings slurry was subjected to cyanide leaching for 24 hours, with the pH value of the slurry controlled at 13 and the amount of cicada added at 25 g / kg. In this example, the iron grade in the magnetic separation concentrate was 60.12%, and the iron recovery rate was 75.25%; the gold leaching rate after cyanide leaching of the magnetic separation tailings was 82.44%.

[0039] Example 3: This embodiment employs a method for co-roasting and magnetic separation of carbonaceous gold ore and cyanide tailings to enrich gold and iron, including the following steps: 1. Mix 16 g of carbonaceous gold concentrate powder, 24 g of cyanide tailings powder and 4 g of CaCO3 powder, press them into blocks and dry them to obtain sample 1; 2. Sample 1 was heated to 800℃ in a tube furnace for calcination. After the calcination temperature was maintained for 60 min, the sample was cooled to room temperature with the furnace. After calcination, the sample was cooled to obtain sample 2. 3. Sample 2 was ground and sieved, and then mixed with water at a solid-liquid ratio of 1:2 to prepare a slurry solution. The slurry solution was then subjected to magnetic separation under a magnetic field strength of 0.2 T to obtain iron concentrate and magnetic separation tailings slurry.

[0040] 4. The magnetic separation tailings slurry was subjected to cyanide leaching for 12 hours, with the pH value of the slurry controlled at 11 and the amount of cicada added at 25 g / kg. In this example, the iron grade in the magnetic separation concentrate was 56.25%, and the iron recovery rate was 70.18%; the gold leaching rate after cyanide leaching of the magnetic separation tailings was 65.80%.

[0041] Example 4: This embodiment employs a method for co-roasting and magnetic separation of carbonaceous gold ore and cyanide tailings to enrich gold and iron, including the following steps: 1. Mix 27 g of carbonaceous gold concentrate powder, 13 g of cyanide tailings powder and 4 g of CaO powder, press them into blocks and dry them to obtain sample 1; 2. Sample 1 was heated to 900℃ in a tube furnace for calcination. After the calcination temperature was maintained for 30 min, the sample was cooled to room temperature with the furnace. After calcination, the sample was cooled to obtain sample 2. 3. Sample 2 was ground and sieved, and then mixed with water at a solid-liquid ratio of 1:2 to prepare a slurry solution. The slurry solution was then subjected to magnetic separation under a magnetic field strength of 0.3 T to obtain iron concentrate and magnetic tailings slurry.

[0042] 4. The magnetic separation tailings slurry was subjected to cyanide leaching for 16 h, the pH value of the magnetic separation tailings slurry was controlled at 13, and the amount of cicada added was 25 g / kg.

[0043] The iron grade in the magnetic separation concentrate obtained in this embodiment is 51.26%, and the iron recovery rate is 76.25%; the gold leaching rate after cyanidation leaching of the magnetic separation tailings is 71.49%.

[0044] Example 5: This embodiment employs a method for co-roasting and magnetic separation of carbonaceous gold ore and cyanide tailings to enrich gold and iron, including the following steps: 1. Mix 27g of carbonaceous gold concentrate powder, 13g of cyanide tailings powder and 4g of CaO powder, press them into blocks and dry them to obtain sample 1; 2. Sample 1 was heated to 900℃ in a tube furnace for calcination. After the calcination temperature was maintained for 30 min, the sample was cooled to room temperature with the furnace. After calcination, the sample was cooled to obtain sample 2. 3. Sample 2 was ground and sieved, and then mixed with water at a solid-liquid ratio of 1:2 to prepare a slurry solution. The slurry solution was then subjected to magnetic separation under a magnetic field strength of 0.2 T to obtain iron concentrate and magnetic separation tailings slurry.

[0045] 4. The magnetic separation tailings slurry was subjected to cyanide leaching for 12 hours, the pH value of the magnetic separation tailings slurry was controlled at 13, and the amount of cicada added was 25g / kg.

[0046] The iron grade in the magnetic concentrate obtained in this embodiment is 55.42%, and the iron recovery rate is 71.47%; the gold leaching rate after cyanidation leaching of the magnetic tailings is 73.21%.

[0047] Example 6: This embodiment employs a method for co-roasting and magnetic separation of carbonaceous gold ore and cyanide tailings to enrich gold and iron, including the following steps: 1. Mix 20 g of carbonaceous gold concentrate powder, 10 g of cyanide tailings powder and 1 g of CaCO3 powder, press them into blocks and dry them to obtain sample 1; 2. Sample 1 was heated to 600℃ in a tube furnace for calcination. After the calcination temperature was maintained for 90 minutes, the sample was cooled to room temperature with the furnace. After calcination, the sample was cooled to obtain sample 2. 3. Sample 2 was ground and sieved, and then mixed with water at a solid-liquid ratio of 1:1.8 to prepare a slurry solution. The slurry solution was then subjected to magnetic separation under a magnetic field strength of 0.1 T to obtain iron concentrate and magnetic separation tailings slurry.

[0048] 4. The magnetic separation tailings were subjected to cyanide leaching for 12 hours, the pH value of the magnetic separation tailings slurry was controlled at 10, and the amount of cicada added was 10g / kg.

[0049] The iron grade in the magnetic separation concentrate obtained in this embodiment is 58.23%, and the iron recovery rate is 42.53%; the gold leaching rate after cyanidation leaching of the magnetic separation tailings is 18.85%.

[0050] Example 7: This embodiment employs a method for co-roasting and magnetic separation of carbonaceous gold ore and cyanide tailings to enrich gold and iron, including the following steps: 1. Mix 10 g of carbonaceous gold concentrate powder, 20 g of cyanide tailings powder and 4 g of CaO powder, press them into blocks and dry them to obtain sample 1; 2. Sample 1 was heated to 600℃ in a tube furnace for calcination. After the calcination temperature was maintained for 90 min, the sample was cooled to room temperature with the furnace. After calcination, the sample was cooled to obtain sample 2. 3. Sample 2 was ground and sieved, and then mixed with water at a solid-liquid ratio of 1:1.5 to prepare a slurry solution. The slurry solution was then subjected to magnetic separation under a magnetic field strength of 0.1 T to obtain iron concentrate and magnetic tailings slurry.

[0051] 4. The magnetic separation tailings slurry was subjected to cyanide leaching for 18 h, the pH value of the magnetic separation tailings slurry was controlled at 12, and the amount of cicada added was 10 g / kg.

[0052] The iron grade in the magnetic separation concentrate obtained in this embodiment is 52.18%, and the iron recovery rate is 54.37%; the gold leaching rate after cyanidation leaching of the magnetic separation tailings is 45.79%.

[0053] Comparative example: Carbonaceous gold ore was directly mixed with water at a solid-liquid ratio of 1:2 to prepare a slurry. Cyanide leaching was carried out for 24 hours. The pH value of the slurry was controlled to 13 using lime. The amount of cicada added was 25g / kg.

[0054] The comparative gold leaching rate was 2.39%.

[0055] Table 3 shows the analysis of sulfur content and total carbon content in carbonaceous gold concentrate under different embodiment conditions.

[0056] Table 3

[0057] As shown in Table 3, after reacting according to the conditions in the examples, the sulfur content in the co-roasted samples was significantly reduced, with a reduction rate of 99.96%–99.98% compared to untreated carbonaceous gold concentrate. Table 1 shows that sulfur in carbonaceous gold concentrate mainly exists in the form of FeS2. After roasting in a vacuum system, FeS2 mainly undergoes pyrolysis and redox reactions with Fe2O3 to generate Fe3O4. The structure of pyrite in the samples is almost completely destroyed, thus fully exposing the encapsulated fine gold particles, which is beneficial for subsequent cyanide leaching.

[0058] Compared to carbonaceous gold concentrate, the carbonaceous content is significantly reduced after the reaction, with a reduction rate of 99.98%–100%. The presence of carbonaceous content is the main reason for the extremely low direct cyanide gold leaching rate of carbonaceous gold concentrate. During roasting, organic carbon is converted into elemental carbon, which is consumed in the reduction of oxides. Therefore, the reduction of carbonaceous content is beneficial to subsequent cyanide leaching.

[0059] The carbonaceous gold concentrate and the treatment effects after each embodiment are shown in Table 4.

[0060] Table 4

[0061] As shown in Table 4, the gold leaching rate of carbonaceous gold concentrate directly cyanided without pretreatment was only 2.39%, which is extremely low. After the reactions in Examples 1-5, the gold leaching rate increased by 62.51% to 80.05%, demonstrating a very significant improvement effect. For iron concentrate with a grade between 51.26% and 60.12%, the recovery rate reached 70.18% to 76.25%, achieving a good recovery effect.

[0062] In summary, this invention can effectively recover gold from carbonaceous gold ore. The roasting pretreatment process features low roasting temperature and low emissions of arsenic and sulfur oxides, exhibiting low energy consumption and high environmental friendliness. During roasting, the carbonaceous material that "robs" gold, as well as the sulfide minerals that are the main gold-encapsulating minerals, undergo thermal decomposition. Furthermore, they and their decomposition products are consumed as raw materials for redox reactions, fully utilizing both the carbonaceous material and the sulfide minerals while resolving the "gold-robbing" effect of the carbonaceous material and the encapsulation effect of the sulfide minerals on gold, thus improving gold leaching efficiency. In addition, by utilizing the reduction effect of carbonaceous material and sulfide minerals in the carbonaceous gold ore, Fe2O3 in the cyanide tailings is reduced to strongly magnetic Fe3O4. Fe3O4 can then be efficiently recovered through weak magnetic separation, simultaneously achieving resource utilization of the cyanide tailings and significantly reducing the cost of iron recovery from the cyanide tailings.

Claims

1. A method for enriching gold and iron through co-roasting and magnetic separation of carbonaceous gold ore and cyanide tailings, characterized in that, The process includes the following: Carbonaceous gold ore powder, cyanide tailings powder and additive powder are thoroughly mixed, then cold-pressed and dried to obtain a blocky solid; the additive is at least one of calcium carbonate powder and lime powder; the mass ratio of carbonaceous gold ore powder, cyanide tailings powder and additive powder is (10-27):(10-24):(1-5). The blocky solid is roasted, ground, and sieved to obtain powder. The roasting process is conducted in an air-isolated manner; The powder is mixed with water to form a mineral slurry solution; The slurry solution is subjected to magnetic separation to obtain iron concentrate and magnetic separation tailings slurry; The magnetic separation tailings slurry is then leached for gold.

2. The method for enriching gold and iron by co-roasting and magnetic separation of carbonaceous gold ore and cyanide tailings according to claim 1, characterized in that, The carbonaceous gold ore powder has a particle size of -0.074 mm, and the mass percentage of such particles is over 90%.

3. The method for enriching gold and iron by co-roasting and magnetic separation of carbonaceous gold ore and cyanide tailings according to claim 1, characterized in that, When the block solid is roasted, the roasting temperature is 600℃~900℃ and the roasting time is 30min~90min.

4. The method for enriching gold and iron by co-roasting and magnetic separation of carbonaceous gold ore and cyanide tailings according to claim 1, characterized in that, The powder has a fineness of -0.074 mm and the mass percentage of particles is over 90%.

5. The method for enriching gold and iron by co-roasting and magnetic separation of carbonaceous gold ore and cyanide tailings according to claim 1, characterized in that, When the powder is mixed with water to form a slurry solution, the solid-liquid ratio of the powder to the water is 1:(1.5~2).

6. The method for enriching gold and iron by co-roasting and magnetic separation of carbonaceous gold ore and cyanide tailings according to claim 1, characterized in that, When the slurry solution is subjected to magnetic separation, the magnetic field strength is 0.1 to 0.3 T.

7. The method for enriching gold and iron by co-roasting and magnetic separation of carbonaceous gold ore and cyanide tailings according to claim 1, characterized in that, When leaching gold from the magnetic separation tailings slurry, lime is used to adjust the pH value of the slurry to 10-13, and cyanide or environmentally friendly reagents are used to leach the gold. During the leaching process, air is continuously circulated and the slurry is stirred.

8. A method for enriching gold and iron by co-roasting and magnetic separation of carbonaceous gold ore and cyanide tailings according to claim 7, characterized in that, Add 2.5-25g of cyanide or environmentally friendly reagent to each kilogram of magnetic separation tailings slurry, and leaching time is 12-24 hours.

9. A method for enriching gold and iron by co-roasting and magnetic separation of carbonaceous gold ore and cyanide tailings according to any one of claims 1-8, characterized in that, The carbonaceous gold ore powder is made from raw ore powder and / or flotation gold concentrate powder, and the total carbon content in the carbonaceous gold ore powder is 5% to 15% of the mass of the carbonaceous gold ore powder.

10. A method for enriching gold and iron by co-roasting and magnetic separation of carbonaceous gold ore and cyanide tailings according to any one of claims 1-8, characterized in that, The iron minerals in the cyanide tailings powder exist in the form of hematite, and the hematite content is 20% to 50% of the mass of the cyanide tailings powder. The cyanide tailings powder is obtained by cyaniding leaching after pretreatment of at least one of sulfur-containing gold concentrate, carbonaceous gold ore and Carlin-type gold ore through oxidative roasting.

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