Gold extraction method of low-gold pyrite

Abstract

The invention discloses a method for extracting gold from low-gold pyrite, which comprises the following steps of: independently carrying out oxidation smelting on low-grade gold-containing pyrite, enriching valuable elements such as gold in ore in a molten ferrous sulfide phase through selective slagging and slag-sulfonium balance control, and extracting gold from the gold-containing pyrite in a mode of cyanide leaching of the ferrous sulfide phase and flotation and discarding of gold leaching slag. Preferential extraction of gold easy to dissociate and secondary enrichment of gold difficult to dissociate in the ferrous sulfide phase are achieved; the gold leaching slag flotation concentrate is treated in a microwave roasting and superfine grinding cyaniding mode, the selective heating characteristic of microwaves is utilized, efficient desulfurization is achieved, meanwhile, microcracks of oxidized calcine are increased, the dissociation degree of gold in ore is improved, secondary wrapping of roasted oxide on gold is overcome, in addition, the superfine grinding cost can be remarkably reduced, and the process benefits are improved. And the high-iron-grade leaching slag 1 and the high-iron-grade leaching slag 2 are sent to a steel smelting plant to be used as ironmaking raw materials, so that the economic benefits of the process are further improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metallurgy, in particular to a gold extraction method for low-gold pyrite. BACKGROUND

[0002] With the continuous expansion of gold mining scale, high-quality and easy-to-treat gold mines are becoming increasingly exhausted, and refractory gold mines have become one of the main raw materials for gold production enterprises. Cyanidation method has become one of the mainstream gold extraction processes due to its high efficiency, economy and wide applicability, especially in the treatment of low-grade and fine-grained disseminated gold mines. However, for sulfide-encapsulated refractory ores, cyanidation method still has certain limitations, and roasting method is often used for oxidation pretreatment.

[0003] In a fluidized roasting method for sulfide gold ore disclosed by Chinese patent application CN102127635A, the harmful elements such as arsenic and sulfur in the gold ore are removed by suspension roasting; in a method for strengthening gold leaching rate of carbon-containing gold ore suspension roasting disclosed by Chinese patent application CN111485100A, the harmful elements such as carbon in the gold ore are removed by suspension oxidation roasting to improve gold recovery rate; in a method for recovering gold from gold ore roasting ash disclosed by Chinese patent application CN106048247A, the effective recovery of gold in the gold concentrate oxidation roasting ash is realized by the method of granulation oxidation roasting; in a method for two-stage roasting-transformation treatment-cyanide leaching of high-arsenic gold ore disclosed by Chinese patent application CN107541607A, the problem of secondary encapsulation of hematite in the roasting sand is overcome by the method of gold ore oxidation roasting-alkaline leaching; in a method for gold extraction by roasting pretreatment of sulfur-arsenic-containing and carbon-containing gold ore disclosed by Chinese patent application CN105838901A, the problem of secondary encapsulation of arsenate is solved by the method of mixed roasting of "gold ore + sodium salt".

[0004] However, for low-gold pyrite, it is difficult to effectively control the roasting temperature due to its low gold and high sulfur properties, and the roasting-cyanidation process is difficult to dispose economically and effectively. In modern industrial production, it is often smelted with copper, lead and other heavy metal smelting systems, but for high-yield low-gold pyrite in remote areas, the existing gold extraction process is still difficult to dispose. SUMMARY

[0005] In view of the shortcomings of the prior art, the present application aims to provide a gold extraction method for low-gold pyrite.

[0006] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0007] A gold extraction method for low-gold pyrite, comprising the following steps:

[0008] Step 1, oxidation smelting of low-gold pyrite:

[0009] The low gold pyrite, flux and reducing agent are sent into a smelting furnace for oxidation smelting, and the mixed melt obtained by the oxidation smelting is subjected to electric furnace depletion to obtain depleted slag and gold-rich ferrous sulfide phase;

[0010] Step 2, gold extraction by cyanidation of gold-rich ferrous sulfide:

[0011] The gold-rich ferrous sulfide phase obtained in step 1 is sent into a carbon slurry cyanidation system after fine grinding to obtain gold-loaded carbon 1 and leaching residue 1.

[0012] Step 3, flotation of leaching residue to remove impurities:

[0013] The leaching residue 1 obtained in step 2 is sent into a total sulfur flotation system after washing and slurry preparation to obtain flotation concentrate and flotation tailings.

[0014] Step 4, microwave oxidation roasting of flotation concentrate:

[0015] The flotation concentrate obtained in step 3 is sent into a microwave oxidation roasting system after preheating to obtain oxidized roasting sand.

[0016] Step 5, ultra-fine grinding and cyanidation of oxidized roasting sand:

[0017] The oxidized roasting sand obtained in step 4 is sent into a carbon slurry cyanidation system after ultra-fine grinding to obtain gold-loaded carbon 2 and leaching residue 2; gold-loaded carbon 1 and gold-loaded carbon 2 are combined and sent into a gold smelting system, and the flotation tailings and leaching residue 2 are combined and sent into a steel smelting system.

[0018] Further, in step 1, the flux includes one or more of CaO, CaCO3, CaSO4, calcium borate, and quartz; the reducing agent includes one or more of coke powder, coal powder, biomass, and pig iron; and the reducing agent is in a ratio of 0-5% of the mass of the low gold pyrite.

[0019] Further, in the oxidation smelting process of the low gold pyrite in step 1, the smelting temperature is 1300-1350°C, the mass ratio of the depleted slag to the gold-rich ferrous sulfide phase is 2.5-6:1, the mass ratio of Fe to SiO2 in the depleted slag is 1-1.3:1, the mass ratio of CaO to SiO2 is 0.2-0.3:1, and the Al2O3 content is less than 12%.

[0020] Further, in step 1, 0-3% of the reducing agent of the mass of the mixed melt is added during the electric furnace depletion of the mixed melt.

[0021] Further, in step 1, the electric furnace depletion is performed at 1300°C-1350°C for 1-2h.

[0022] Further, in step 2, the fine grinding particle size of the gold-rich ferrous sulfide phase is 50-80% of -200 mesh.

[0023] Further, in step 4, the flotation concentrate is preheated to 200-300 DEG C by using the waste heat of the sulfur-containing flue gas generated in the oxidative smelting in step 1, and then sent into the microwave oxidative roasting system; in the microwave oxidative roasting system, the microwave frequency is 2450 Hz, and the microwave power density is 7-12 kW / kg.

[0024] Further, in step 5, the fine grinding particle size of the oxidized calcine is 50-80% of-400 mesh.

[0025] The present application has the following advantages:

[0026] (1) The present application utilizes the metallic properties of molten ferrous sulfide to separately perform oxidative smelting on low-grade gold-bearing pyrite, and through the method of "selective slagging + slag-slug balance control", the valuable elements such as gold in the ore are enriched in the molten ferrous sulfide phase, which is not limited by other auxiliary materials such as copper, lead and antimony, and can be processed in large quantities, thus solving the problem of difficult disposal of large quantities of low-gold pyrite in remote areas;

[0027] (2) According to the composition characteristics of the ferrous sulfide phase, through the method of "cyanide leaching of ferrous sulfide phase + flotation of leaching gold residue", the preferential extraction of easily dissociated gold and the secondary enrichment of difficult dissociated gold in the ferrous sulfide phase are realized;

[0028] (3) The flotation concentrate is treated by the method of "microwave roasting + superfine grinding", and the energy consumption of the microwave roasting reaction is significantly reduced by the preheating of the flotation concentrate, thereby reducing the process cost. In the process of microwave roasting, the flotation concentrate is efficiently desulfurized, and at the same time, the selective heating characteristics of the microwave are utilized to increase the micro-cracks of the oxidized calcine, improve the dissociation degree of gold in the ore, overcome the secondary wrapping of gold by the roasted oxide, and significantly reduce the superfine grinding cost, thereby improving the process benefit;

[0029] (4) The leaching residue 1 and the leaching residue 2 with high iron grade are sent to a steel smelting plant as ironmaking raw materials, thereby further improving the economic benefit of the process. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The method flowcharts of embodiments 1-6 of the present application are shown. DETAILED DESCRIPTION

[0031] The present application will be further described below with reference to the accompanying drawings, and it should be noted that the present embodiment is based on the technical solution, and detailed implementation and specific operation processes are given, but the protection scope of the present application is not limited to the present embodiment.

[0032] Embodiment 1

[0033] This embodiment provides a method for gold extraction from low-gold pyrite. The main mass percentage contents of the low-gold pyrite used are: Fe 45.63%, S 38.1%, Cu 0.19%, SiO2 9.2%, Al2O3 6.33%, CaO 0.08%, Au 4.6g / t.

[0034] like Figure 1 As shown, the gold extraction method in this embodiment includes the following steps:

[0035] (1) Smelting of low-gold pyrite: The above-mentioned low-gold pyrite, along with 7.2% CaO and 19.8% quartz by weight of the low-gold pyrite, are fed into a smelting furnace. Oxidative smelting is carried out at 1300℃ using oxygen-enriched gas with an oxygen concentration of 75%. In terms of slag shape control, the mass ratio of Fe to SiO2 in the depleted slag is 1:1, the mass ratio of CaO to SiO2 is 0.25:1, and the alumina content in the slag is about 10%. After the oxidative smelting is completed, the mixed melt is sent to the electric furnace depletion process. Under the depletion condition of holding at 1300℃ for 1 hour, the two-phase separation of the depleted slag and the gold-rich ferrous sulfide phase is achieved. The mass ratio of the depleted slag and the gold-rich ferrous sulfide phase is about 2.5. The gold grade in the gold-rich ferrous sulfide phase is about 17.3 g / t, and the gold grade in the depleted slag is about 0.28 g / t. The direct gold recovery rate of the smelting is about 95.8%.

[0036] (2) Fine grinding and cyanidation of gold-rich ferrous sulfide phase: After the gold-rich ferrous sulfide phase is finely ground to -200 mesh with a content of 80%, it is sent to the carbon-in-pulp cyanidation gold extraction system. Under the conditions of sodium cyanide concentration of 1g / L and leaching at room temperature for 32h, the carbon-in-pulp cyanidation process is carried out to obtain gold-loaded carbon 1 and leaching residue 1. The leaching residue 1 contains about 4g / t of gold and the gold leaching rate is about 75%.

[0037] (3) Leaching residue flotation + microwave oxidation roasting: Leaching residue 1, after washing and slurry conditioning, is sent to a full-sulfur flotation system to obtain flotation tailings and flotation concentrate. The gold grade of the flotation concentrate is approximately 8.8 g / t. The flotation concentrate is preheated to 200°C using the residual heat from the sulfur-containing flue gas generated by oxidation smelting, and then subjected to microwave oxidation roasting at a microwave frequency of 2450 Hz, a microwave power of 10 kW / kg, and a roasting temperature of 550°C to obtain oxidized roasted sand with a gold grade of approximately 8.1 g / t. The sulfur-containing flue gas, after participating in the preheating, is sent to the acid production system to prepare sulfuric acid.

[0038] (4) Oxide calcined sand ultrafine grinding and cyanidation: The oxide calcined sand is finely ground to -400 mesh with a content of 70% and then fed into the carbon-in-pulp cyanidation gold extraction system. Carbon leaching cyanidation is carried out under the conditions of sodium cyanide concentration of 1g / L and leaching at room temperature for 32h to obtain gold-loaded carbon 2 and leaching residue 2. The gold grade of leaching residue 2 is about 0.14g / t, and the gold leaching rate is about 98.3%.

[0039] (5) Liquid-solid separation: the gold leaching residue 2 and the flotation tailings are sent to a steel smelting plant, and the gold-loaded carbon 1 and the gold-loaded carbon 2 are combined and sent to a gold smelting plant.

[0040] Example 2

[0041] The present embodiment provides a gold extraction method for low-gold pyrite, and the main mass percentage of the low-gold pyrite used is as follows: Fe 45.63%, S 38.1%, Cu 0.19%, SiO2 9.2%, Al2O3 6.33%, CaO 0.08%, and Au 4.6 g / t.

[0042] As shown in Figure 1 , the gold extraction method of the present embodiment includes the following steps:

[0043] (1) Low-gold pyrite smelting: the low-gold pyrite is sent into a smelting furnace together with CaO accounting for 7.2% of the mass of the low-gold pyrite, quartz accounting for 19.8% of the mass of the low-gold pyrite, and coal powder accounting for 2% of the mass of the low-gold pyrite, and is subjected to oxidative smelting at 1350°C with oxygen-enriched gas with an oxygen concentration of 75%. In terms of slag type control, the mass ratio of Fe to SiO2 in the lean slag is 1:1, the mass ratio of CaO to SiO2 is 0.25:1, and the Al2O3 content in the slag is about 9.4%. After oxidative smelting, the mixed melt is sent into an electric furnace for a lean-up process under lean-up conditions of holding at 1300°C for 2 hours, so as to realize two-phase separation of the lean slag and the gold-rich ferrous sulfide phase, and the mass ratio of the lean slag to the gold-rich ferrous sulfide phase is about 2.5, the gold grade in the gold-rich ferrous sulfide phase is about 17.2 g / t, the gold grade in the lean slag is about 0.22 g / t, and the direct recovery rate of smelting gold is about 96.7%.

[0044] (2) Fine grinding and cyanidation of gold-rich ferrous sulfide phase: the gold-rich ferrous sulfide phase is finely ground to a-200 mesh content of 50% and then sent into a carbon-in-pulp cyanidation system, and a carbon-in-pulp cyanidation process is performed under conditions of a sodium cyanide concentration of 1 g / L and a room temperature leaching time of 32 hours, so as to obtain gold-loaded carbon 1 and leaching residue 1, the leaching residue 1 containing about 4.7 g / t of gold, and a gold leaching rate of about 70%.

[0045] (3) Leaching residue flotation + microwave oxidation roasting: the leaching residue 1 is washed and slurried and then sent into a total sulfur flotation system, so as to obtain flotation tailings and flotation concentrate, the gold grade of the flotation concentrate being about 10.4 g / t. The flotation concentrate is preheated to 300°C using the waste heat of sulfur-containing flue gas generated by oxidative smelting and then sent into a microwave oxidation roasting system, and a microwave oxidation roasting process is performed under conditions of a microwave frequency of 2450 Hz, a microwave power of 7 Kw / Kg, and a roasting temperature of 550°C, so as to obtain oxidized roasting sand with a gold grade of about 9.4 g / t. The sulfur-containing flue gas after preheating is sent into an acid-making system to prepare sulfuric acid.

[0046] (4) Oxidized calcine superfine grinding cyanidation: the oxidized calcine is sent to the carbon slurry cyanidation gold extraction system after being finely ground to 80% of -400 mesh, and carbon-in-pulp cyanidation is carried out under the conditions of a sodium cyanide concentration of 1 g / L and room temperature leaching for 32 h to obtain gold-loaded carbon 2 and leaching residue 2, the gold grade of the leaching residue 2 is about 0.15 g / t, and the gold leaching rate is about 98.4%.

[0047] (5) Liquid-solid separation: the flotation tailings and the gold leaching residue 2 are combined and sent to a steel smelting plant, and the gold-loaded carbon 1 and the gold-loaded carbon 2 are combined and sent to a gold smelting plant.

[0048] Example 3

[0049] The present embodiment provides a method for extracting gold from low-gold pyrite, the main mass percentage of the low-gold pyrite used is: Fe 45.63%, S 38.1%, Cu 0.19%, SiO2 9.2%, Al2O3 6.33%, CaO 0.08%, and Au 4.6 g / t.

[0050] As shown in Figure 1 , the gold extraction method of the present embodiment includes the following steps:

[0051] (1) Low-gold pyrite smelting: the above low-gold pyrite, CaO with a mass percentage of 5.8% of the low-gold pyrite, quartz with a mass percentage of 19.8% of the low-gold pyrite, and coal powder with a mass percentage of 1% of the low-gold pyrite are jointly sent to a smelting furnace, and oxygen concentration is 75% of the oxygen-rich gas for oxidation smelting under the condition of 1350°C. As for the slag type control, the mass ratio of Fe to SiO2 is 1:1, and the mass ratio of CaO to SiO2 is 0.2:1, and the Al2O3 content in the slag is about 10%. Subsequently, the mixed melt obtained by oxidation smelting and coal powder with a mass percentage of 1% of the mixed melt are jointly sent to an electric furnace for the leaner process, and the leaner slag and the gold-rich ferrous sulfide phase are separated under the leaner conditions of 1300°C and 2 hours of holding, the mass ratio of the leaner slag to the gold-rich ferrous sulfide phase is about 2.5, the gold grade in the gold-rich ferrous sulfide phase produced is about 17.7 g / t, the gold grade in the leaner slag is about 0.14 g / t, and the direct smelting gold recovery rate is about 97.9%.

[0052] (2) Fine grinding cyanidation of gold-rich ferrous sulfide phase: the gold-rich ferrous sulfide phase is finely ground to 70% of -200 mesh and then sent to the carbon slurry cyanidation gold extraction system, and the carbon-in-pulp cyanidation process is carried out under the conditions of a sodium cyanide concentration of 1 g / L and room temperature leaching for 32 h to obtain gold-loaded carbon 1 and leaching residue 1, the gold content of the leaching residue 1 is about 3.8 g / t, and the gold leaching rate is about 76%.

[0053] (3) Leaching residue flotation + microwave oxidation roasting: The leaching residue 1 is washed and slurried, and then sent to a total sulfur flotation system for total sulfur flotation to obtain flotation tailings and flotation concentrate, and the gold grade of the flotation concentrate is about 8.3 g / t. The flotation concentrate is preheated to 300°C using the waste heat of sulfur-containing flue gas generated by the oxidation smelting, and then sent to a microwave oxidation roasting system for microwave oxidation roasting under the conditions of a microwave frequency of 2450 Hz, a microwave power of 12 Kw / Kg, and a roasting temperature of 550°C to obtain oxidized roasting sand with a gold grade of about 7.5 g / t. The sulfur-containing flue gas after preheating is sent to an acid making system to make sulfuric acid.

[0054] (4) Ultrafine grinding of oxidized roasting sand and cyanidation: The oxidized roasting sand is finely ground to 50% of -400 mesh, and carbon-in-pulp cyanidation is carried out under the conditions of a sodium cyanide concentration of 1 g / L and a room temperature leaching time of 32 h to obtain gold-loaded carbon 2 and leaching residue 2, and the gold grade of the leaching residue 2 is about 0.17 g / t, and the gold leaching rate is about 97.8%.

[0055] (5) Liquid-solid separation: The gold leaching residue 2 and the flotation tailings are combined and sent to a steel smelting plant, and the gold-loaded carbon 1 and the gold-loaded carbon 2 are combined and sent to a gold smelting plant.

[0056] Example 4

[0057] The present embodiment provides a gold extraction method for low-gold pyrite, and the main mass percentage of the low-gold pyrite used is as follows: Fe 45.63%, S 38.1%, Cu 0.19%, SiO2 9.2%, Al2O3 6.33%, CaO 0.08%, and Au 4.6 g / t.

[0058] As shown in Figure 1 , the gold extraction method of the present embodiment includes the following steps:

[0059] (1) Low-gold pyrite smelting: The above low-gold pyrite, CaO with a mass of 5.8% of the low-gold pyrite, quartz with a mass of 19.8% of the low-gold pyrite, and coal powder with a mass of 2% of the low-gold pyrite are jointly sent to a smelting furnace, and oxygen concentration of 75% of the oxygen-enriched gas is used for oxidation smelting at 1350°C. In terms of slag type control, the mass ratio of Fe to SiO2 in the slag is 1:1, the mass ratio of CaO to SiO2 is 0.2:1, and the content of alumina in the slag is about 9%. Subsequently, the mixed melt obtained by oxidation smelting and coal powder with a mass of 2% of the mixed melt are jointly sent to an electric furnace for a depletion process, and the depletion is carried out under the conditions of 1350°C and a holding time of 2 hours to realize two-phase separation of the depleted slag and the gold-rich ferrous sulfide phase, and the mass ratio of the depleted slag to the gold-rich ferrous sulfide phase is about 2.5, the gold grade of the gold-rich ferrous sulfide phase is about 17.7 g / t, the gold grade of the depleted slag is about 0.1 g / t, and the direct recovery rate of smelting gold is about 98.6%.

[0060] (2) Fine grinding of gold-rich ferrous sulfide phase cyanidation: The gold-rich ferrous sulfide phase is finely ground to 70% of -200 mesh, and then sent to a carbon slurry cyanidation system. Under the conditions of a sodium cyanide concentration of 1 g / L and a room temperature leaching time of 32 h, a carbon-in-pulp cyanidation process is performed to obtain loaded carbon 1 and leaching residue 1. The leaching residue 1 contains about 4.2 g / t of gold, and the gold leaching rate is about 74%.

[0061] (3) Leaching residue flotation + microwave oxidation roasting: The leaching residue 1 is washed and slurried, and then sent to a total sulfur flotation system for total sulfur flotation to obtain flotation concentrate and flotation tailings. The flotation concentrate has a gold grade of about 9.3 g / t. The flotation concentrate is preheated to 300°C using the waste heat of sulfur-containing flue gas generated in the oxidation smelting process, and then sent to a microwave oxidation roasting system. Under the conditions of a microwave frequency of 2450 Hz, a microwave power of 12 Kw / Kg, and a roasting temperature of 550°C, microwave oxidation roasting is performed to obtain oxidized roasting sand with a gold grade of about 8.5 g / t. The sulfur-containing flue gas after preheating is sent to an acid production system to produce sulfuric acid.

[0062] (4) Ultrafine grinding of oxidized roasting sand cyanidation: The microwave oxidized roasting sand is finely ground to 80% of -400 mesh, and then subjected to carbon-in-pulp cyanidation under the conditions of a sodium cyanide concentration of 1 g / L and a room temperature leaching time of 32 h to obtain loaded carbon 2 and leaching residue 2. The leaching residue 2 has a gold grade of about 0.1 g / t, and the gold leaching rate is about 98.5%.

[0063] (5) Liquid-solid separation: The gold leaching residue 2 is sent to a steel smelting plant, and the loaded carbon 1 and the loaded carbon 2 are combined and sent to a gold smelting plant.

[0064] Example 5

[0065] The present embodiment provides a gold extraction method for low-gold pyrite. The main mass percentage contents of the low-gold pyrite used are as follows: Fe 45.63%, S 38.1%, Cu 0.19%, SiO2 9.2%, Al2O3 6.33%, CaO 0.08%, and Au 4.6 g / t.

[0066] As shown in Figure 1 , the gold extraction method of the present embodiment includes the following steps:

[0067] (1) Low gold pyrite smelting: the above low gold pyrite and low gold pyrite mass 7.5% CaO, low gold pyrite mass 28.2% low gold pyrite quartz and low gold pyrite mass 5% coal powder are sent into the smelting furnace together, and the oxidation smelting is carried out at 1350℃ with oxygen concentration of 75% oxygen-enriched gas, the mass ratio of Fe and SiO2 in the slag is controlled to be 1:1, the mass ratio of CaO and SiO2 is 0.2:1, and the content of alumina in the slag is about 7.5%. After the oxidation smelting is completed, the mixed melt is sent into the electric furnace for the depletion process, and under the depletion conditions of 1300℃ for 2 hours, the two-phase separation of the depleted slag and the gold-rich ferrous sulfide phase is realized, the mass ratio of the depleted slag and the gold-rich ferrous sulfide phase is about 6, the gold grade in the gold-rich ferrous sulfide phase is about 31.4g / t, the gold grade in the depleted slag is about 0.25g / t, and the direct recovery rate of gold smelting is about 95.5%.

[0068] (2) Fine grinding cyanidation of gold-rich ferrous sulfide phase: the gold-rich ferrous sulfide phase is finely ground to 80% of-200 mesh, and then sent into the carbon-in-pulp cyanidation system, under the conditions of sodium cyanide concentration of 1g / L and leaching at room temperature for 32h, the carbon-in-pulp cyanidation process is carried out, to obtain gold-loaded carbon 1 and leaching residue 1, the leaching residue 1 contains about 6.8g / t of gold, and the gold leaching rate is about 75.9%.

[0069] (3) Leaching residue flotation + microwave oxidation roasting: the leaching residue 1 is washed and slurried, and then sent into the total sulfur flotation system to obtain flotation concentrate and flotation tailings, and the gold grade of the flotation concentrate is about 15.1g / t. The flotation concentrate is preheated to 300℃ using the waste heat of sulfur-containing flue gas generated in the oxidation smelting process, and then sent into the microwave oxidation roasting system, under the conditions of microwave frequency of 2450Hz, microwave power of 7Kw / Kg and roasting temperature of 550℃, the microwave oxidation roasting is carried out, to obtain oxidized roasting sand with a gold grade of about 13.9g / t. The sulfur-containing flue gas after preheating is sent into the acid making system to prepare sulfuric acid.

[0070] (4) Ultrafine grinding cyanidation of oxidized roasting sand: the microwave oxidized roasting sand is finely ground to 80% of-400 mesh, and then carbon-in-pulp cyanidation is carried out under the conditions of sodium cyanide concentration of 1g / L and leaching at room temperature for 32h, to obtain gold-loaded carbon 2 and leaching residue 2, the leaching residue 2 contains about 0.2g / t of gold, and the gold leaching rate is about 98.6%.

[0071] (5) Liquid-solid separation: the gold leaching residue 2 is sent into a steel smelting plant, and the gold-loaded carbon 1 and the gold-loaded carbon 2 are combined and sent into a gold smelting plant.

[0072] Example 6

[0073] The embodiment provides a gold extraction method for low gold pyrite, and the main mass percentage content of the low gold pyrite used is as follows: Fe 45.63%, S 38.1%, Cu 0.19%, SiO2 9.2%, Al2O3 6.33%, CaO 0.08%, and Au 4.6g / t.

[0074] As Figure 1 shown, the gold extraction method of the present embodiment includes the following steps:

[0075] (1) Low gold pyrite smelting: the above low gold pyrite, CaO with a mass fraction of 8.7% of the low gold pyrite, quartz with a mass fraction of 19.9% of the low gold pyrite, and 3% of coal powder are jointly fed into a smelting furnace, and oxidation smelting is carried out at 1300°C with oxygen-enriched gas with an oxygen concentration of 75%, the mass ratio of Fe and SiO2 in the slag is controlled to be 1.3:1, the mass ratio of CaO and SiO2 is controlled to be 0.3:1, and the alumina content in the slag is about 8.1%. After the oxidation smelting is completed, the mixed melt is fed into an electric furnace for a depletion process, and under the conditions of 1300°C for 2 hours and 3% of the mixed melt in terms of mass ratio of coal powder, the two-phase separation of the depleted slag and the gold-rich ferrous sulfide phase is realized, the mass ratio of the depleted slag and the gold-rich ferrous sulfide phase is about 6, the gold grade in the gold-rich ferrous sulfide phase is about 34.4g / t, the gold grade in the depleted slag is about 0.09g / t, and the direct recovery rate of gold smelting is about 98.6%.

[0076] (2) Fine grinding and cyanidation of gold-rich ferrous sulfide phase: after the gold-rich ferrous sulfide phase is finely ground to 80% of -200 mesh, it is fed into a carbon-in-pulp cyanidation system, and under the conditions of a sodium cyanide concentration of 1g / L and a leaching time of 32 hours at room temperature, a carbon-in-pulp cyanidation process is carried out to obtain gold-loaded carbon 1 and leaching residue 1, the leaching residue 1 contains about 7.5g / t of gold, and the gold leaching rate is about 75.9%.

[0077] (3) Leaching residue flotation + microwave oxidation roasting: after the leaching residue 1 is washed and slurried, it is fed into a total sulfur flotation system to obtain flotation concentrate and flotation tailings, and the gold grade of the flotation concentrate is about 17.2g / t. The flotation concentrate is preheated to 300°C using the waste heat of sulfur-containing flue gas generated in the oxidation smelting process, and then is fed into a microwave oxidation roasting system, and under the conditions of a microwave frequency of 2450Hz, a microwave power of 7Kw / Kg, and a roasting temperature of 550°C, microwave oxidation roasting is carried out to obtain oxidized roasting sand with a gold grade of about 15.3g / t. The sulfur-containing flue gas after preheating is sent to an acid making system to make sulfuric acid.

[0078] (4) Ultrafine grinding and cyanidation of oxidized roasting sand: the microwave oxidized roasting sand is finely ground to 80% of -400 mesh, and under the conditions of a sodium cyanide concentration of 1g / L and a leaching time of 32 hours at room temperature, carbon-in-pulp cyanidation is carried out to obtain gold-loaded carbon 2 and leaching residue 2, the leaching residue 2 contains about 0.2g / t of gold, and the gold leaching rate is about 98.6%.

[0079] (5) Liquid-solid separation: the gold leaching residue 2 is sent to a steel smelting plant, and the gold-loaded carbon 1 and the gold-loaded carbon 2 are combined and sent to a gold smelting plant.

[0080] For those skilled in the art, various corresponding changes and modifications can be made to the above technical solutions and concepts, and all these changes and modifications should be included in the protection scope of the claims of the present application.

Claims

1. A method for extracting gold from low-gold pyrite, characterized in that, Includes the following steps: Step 1: Oxidation smelting of low-gold pyrite: Low-gold pyrite, flux and reducing agent are fed into a smelting furnace for oxidation smelting. The mixed melt obtained by oxidation smelting is then depleted in an electric furnace to obtain depleted slag and gold-rich ferrous sulfide phase. Step 2: Gold extraction via gold sulfide ferrocyanide: The gold-rich ferrous sulfide phase obtained in step 1 is finely ground and then fed into a carbon-in-pulp cyanidation gold extraction system to obtain gold-loaded carbon 1 and leaching residue 1. Step 3: Flotation and impurity removal of leaching residue: The leaching residue 1 obtained in step 2 is washed and slurry-adjusted before being sent to a full-sulfur flotation system to obtain flotation concentrate and flotation tailings; Step 4: Microwave oxidation roasting of flotation concentrate: The flotation concentrate obtained in step 3 is preheated and then fed into a microwave oxidation roasting system to obtain oxidized roasted sand; Step 5: Oxidized calcined sand ultrafine grinding and cyanidation: The oxidized roasted sand obtained in step 4 is then ultra-fine ground and fed into the carbon-in-pulp cyanide gold extraction system to obtain gold-loaded carbon 2 and leaching residue 2. Gold-loaded carbon 1 and gold-loaded carbon 2 are then combined and fed into the gold smelting system, while the flotation tailings and leaching residue 2 are combined and fed into the iron and steel smelting system.

2. The gold extraction method according to claim 1, characterized in that, In step 1, the flux includes one or more of CaO, CaCO3, CaSO4, calcium borate, and quartz; the reducing agent includes one or more of coke powder, coal powder, biomass, and pig iron; the reducing agent ratio is 0-5% of the mass of low gold pyrite.

3. The gold extraction method according to claim 1, characterized in that, In the oxidation smelting process of low-gold pyrite in step 1, the smelting temperature is 1300-1350℃, the mass ratio of depleted slag to gold-rich ferrous sulfide phase is 2.5-6:1; the mass ratio of Fe to SiO2 in the depleted slag is 1-1.3:1, the mass ratio of CaO to SiO2 is 0.2-0.3:1, and the Al2O3 content is less than 12%.

4. The gold extraction method according to claim 1, characterized in that, In step 1, 0-3% of the mass of the mixed melt is added as a reducing agent during the depletion process in the electric furnace.

5. The gold extraction method according to claim 1, characterized in that, In step 1, the conditions for depletion in the electric furnace are to maintain the temperature at 1300℃-1350℃ for 1-2 hours.

6. The gold extraction method according to claim 1, characterized in that, In step 2, the fine grinding particle size of the gold-rich ferrous sulfide phase is -200 mesh, accounting for 50-80%.

7. The gold extraction method according to claim 1, characterized in that, In step 4, the flotation concentrate is preheated to 200-300℃ using the residual heat from the sulfur-containing flue gas generated in step 1 before being sent to the microwave oxidation roasting system. In the microwave oxidation roasting system, the microwave frequency is 2450Hz and the microwave power density is 7-12Kw / kg.

8. The gold extraction method according to claim 1, characterized in that, In step 5, the fine grinding particle size of the oxidized calcined sand is -400 mesh, accounting for 50-80%.

Images