Method for comprehensive recovery of gold, sulfur and iron from cyanide gold extraction tailings

Abstract

The present application belongs to the technical field of gold smelting, and relates to a method for comprehensively recovering gold, sulfur and iron from cyanide gold extraction tailings, comprising the following steps: (1) mixing and blending ores; (2) adding an activator; (3) reduction and magnetization roasting; (4) flotation to recover gold and silver; and (5) magnetic separation to recover iron concentrate. The cyanide gold extraction tailings are efficiently treated through a four-stage treatment process, and the process is simple and easy to implement, so that the gold, sulfur and iron in the cyanide gold extraction tailings are efficiently recovered, the comprehensive utilization and clean production of the cyanide gold extraction tailings are realized, the harm of the cyanide gold extraction tailings to the environment is eliminated, the process flow is smooth, the operability is strong, the environment is excellent, and the method has significant economic, social and environmental benefits.

Description

Technical Field

[0001] This invention belongs to the field of gold smelting technology and relates to a method for the comprehensive recovery of gold, sulfur and iron from cyanide gold extraction tailings. Background Technology

[0002] Gold and silver generally occur as elemental minerals, primarily in the form of pyrite and arsenopyrite, followed by galena, sphalerite, pyrrhotite, and arsenopyrite, while non-metallic minerals include quartz, feldspar, and carbonate minerals. Gold and silver are closely related to pyrite and arsenopyrite, often forming associated minerals. The main components of arsenopyrite are FeAsS, SiO2, and trace elements such as gold and silver.

[0003] Currently, in the field of gold smelting technology, direct cyanidation is generally used for easily processed gold concentrates, while three pretreatment processes are generally employed for difficult-to-process arsenic and carbon-containing gold concentrates: roasting, hot pressing, and bio-oxidation. Roasting is currently the primary method for processing gold concentrates, and after roasting pretreatment, cyanidation is still used for gold extraction. However, both the tailings from direct cyanidation and pretreatment are difficult to dispose of effectively. In 2016, cyanidation tailings were included in the "National Hazardous Waste List." Furthermore, the tailings from gold concentrate cyanidation contain a certain amount of sulfur, gold, and iron that are not effectively recovered, resulting in resource waste. How to achieve comprehensive recovery and utilization of cyanidation tailings has become a focus of attention in the industry. Summary of the Invention

[0004] To address the shortcomings of the existing technology, this invention provides a method for the comprehensive recovery of gold, sulfur, and iron from cyanide gold extraction tailings. The specific technical solution is as follows:

[0005] A method for the comprehensive recovery of gold, sulfur, and iron from cyanide gold extraction tailings includes the following steps:

[0006] (1) Mixing and blending: Direct cyanide tailings and roasted cyanide tailings are mixed at a mass ratio of 1:1 to 3 to obtain mixed cyanide tailings material.

[0007] (2) Additive activation: Additives are added to the mixed cyanide tailings material, including lead-containing substances, sodium hydroxide, sodium sulfate, sodium sulfide and sodium carbonate; then water is added to adjust the slurry concentration to 60wt% to 70wt% (based on dry ore percentage), the temperature is 60 to 70℃, and the slurry is activated by stirring under normal pressure for more than 4 hours to obtain activated slurry.

[0008] (3) Reduction magnetization roasting: The activated slurry is continuously fed into the fluidized bed furnace for reduction magnetization roasting to obtain reduced magnetized roasted sand and flue gas; the temperature of the reduction magnetization roasting is 850-900℃, the furnace bottom pressure is 12000-16000Pa, and the excess air coefficient is controlled at 0.8-1.0.

[0009] (4) Flotation recovery of gold and silver: After grinding the reduced magnetized roasted sand, sodium sulfide, sodium carbonate and copper sulfate are added. Butyl xanthate and butyl ammonium black powder are used as collectors. The pulp concentration is adjusted to 20-30 wt%. After one roughing, two scavenging and two cleaning processes, gold concentrate and flotation tailings are produced.

[0010] (5) Magnetic separation to recover iron concentrate: Adjust the concentration of flotation tailings slurry to 18-28 wt%, and feed it into a magnetic separator with a high magnetic induction intensity of 1200-1500 Gauss. Use a one-stage roughing and two-stage cleaning magnetic separation process to produce iron concentrate and magnetically separated tailings.

[0011] The direct cyanidation tailings of this invention contain 0.8–1.60 g / t of gold, 5–15 g / t of silver, 20–30 wt% of sulfur, and 15–25 wt% of iron; the roasted cyanidation tailings contain 1.5–5.5 g / t of gold, 20–50 g / t of silver, 0.5–1.5 wt% of sulfur, and 25–40 wt% of iron. Step (3) involves reduction magnetization roasting in a fluidized bed furnace, maintaining an oxygen-deficient roasting process, so that most of the sulfur is oxidized into sulfur dioxide (SO2) and enters the flue gas in gaseous form, while a small amount enters the slag and dust in the form of sulfate; at the same time, the iron in the cyanidation gold extraction tailings is converted into magnetic iron (Fe3O4), and the mineral particles become porous and loose; the gold-encapsulating compounds such as sulfides, metal oxides, and silicon dioxide are effectively decomposed, and the mineral structure is accurately transformed. The reduced magnetized roasted sand obtained in step (3) contains 2.5–4.5 g / t of gold, 20–40 g / t of silver, 0.2–0.5 wt% of sulfur, and 25–35 wt% of iron. Step (4) yields gold concentrate containing 30–50 g / t of gold and 230–380 g / t of silver, which is returned to the gold extraction system; and flotation tailings containing 0.5 g / t of gold, 10 g / t of silver, and 35–40 wt% of iron. Step (5) produces iron concentrate containing 60–63 wt% iron, with an iron recovery rate of 92–94%. The tailings after magnetic separation are used as raw materials for building materials production.

[0012] This invention provides a four-stage efficient treatment process for cyanide gold extraction tailings. The first stage involves precise mixing and blending of direct cyanide tailings and roasted cyanide tailings. The second stage involves activation with additives. The third stage is reduction-magnetic roasting, with the roasting flue gas used to produce acid and recover sulfur. The fourth stage utilizes roasted sand grinding and flotation technology to recover gold and silver. The fifth stage involves magnetic separation of the flotation tailings to recover iron concentrate. The magnetically separated tailings, which are also high-silica slag, can be used as raw material in building materials production. This invention enables the efficient recovery of gold, sulfur, and iron from cyanide gold extraction tailings, achieving comprehensive utilization and clean production of these tailings. It eliminates the environmental hazards posed by cyanide gold extraction tailings, features a smooth process flow, strong operability, and excellent environmental performance, resulting in significant economic, social, and environmental benefits.

[0013] Furthermore, in step (1), the stirring speed is 20-40 r / min and the mixing time is 1-3 h.

[0014] Furthermore, in step (2), the lead-containing substance is a lead-containing mineral and / or lead copper nitrate, and the lead-containing substance serves as an activator.

[0015] Further, in step (2), the amount of additive added is 30-50 kg / t, the lead content in the additive accounts for 0.2-0.4 wt% of the mixed cyanide tailings material, and the weight ratio of sodium hydroxide, sodium sulfate, sodium sulfide and sodium carbonate is 1:1:1:3.

[0016] Furthermore, the flue gas obtained in step (3) is processed through dry dust removal, wet dust removal, electrostatic precipitator, conversion, and dry absorption processes to produce industrial sulfuric acid.

[0017] Furthermore, in step (4), the grinding time is 10 to 15 minutes, and the grinding fineness is -0.074 mm, accounting for 90 to 95%.

[0018] Further, in step (4), the amount of sodium sulfide added is 200-400 g / t, the amount of sodium carbonate is 200-400 g / t, the amount of copper sulfate is 300-500 g / t, the amount of butyl xanthate is 80-120 g / t, and the amount of butyl ammonium black powder is 40-60 g / t.

[0019] The beneficial effects of this invention are as follows:

[0020] The process of this invention is simple and easy to implement, and is suitable for both direct cyanidation tailings and roasted cyanidation tailings of gold concentrate. Precise blending of direct cyanidation tailings and roasted cyanidation tailings helps ensure sufficient combustion heat for subsequent reduction roasting, resulting in balanced and orderly production. Lead-containing minerals or lead salts increase the particle size and enrichment of gold and silver in the cyanidation tailings during roasting, facilitating their entry into the concentrate during subsequent flotation and significantly improving the gold and silver flotation recovery rate. Reduction magnetization roasting efficiently converts iron in the cyanidation tailings into magnetic iron. After gold and silver are recovered by flotation, the tailings are further recovered using a high-efficiency magnetic separation process.

[0021] This invention enables the efficient recovery of gold, sulfur, and iron from cyanide gold extraction tailings, achieving comprehensive utilization and clean production of cyanide gold extraction tailings, eliminating the environmental hazards of cyanide gold extraction tailings, with a smooth process flow, strong operability, and excellent environmental performance, resulting in significant economic, social, and environmental benefits. Detailed Implementation

[0022] The principles and features of the present invention are described below with reference to embodiments. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0023] Example 1:

[0024] A method for the comprehensive recovery of gold, sulfur, and iron from cyanide gold extraction tailings includes the following steps:

[0025] (1) Precise mixing and blending of ore: According to the composition and characteristics of cyanide tailings, direct cyanide tailings contain 0.8 g / t of gold, 5 g / t of silver, 20 wt% of sulfur, and 15 wt% of iron; roasted cyanide tailings contain 1.5 g / t of gold, 20 g / t of silver, 0.5 wt% of sulfur, and 25 wt% of iron; direct cyanide tailings and roasted cyanide tailings are mixed at a mass ratio of 1:1, with a stirring speed of 20 r / min and a mixing time of 1 h. The mixed cyanide tailings material is then introduced into the next stage of the process.

[0026] (2) Additive activation: Additives are added to the mixed cyanide tailings material at a rate of 30 kg / t. The additives are lead nitrate, sodium hydroxide, sodium sulfate, sodium sulfide, and sodium carbonate compounds. The lead content accounts for 0.2 wt% of the mixed minerals. The weight ratio of sodium hydroxide, sodium sulfate, sodium sulfide, and sodium carbonate is 1:1:1:3. Water is added to adjust the slurry concentration to 60 wt% (based on dry ore percentage). The temperature is 60℃, and the slurry is stirred and activated at normal pressure for more than 4 hours to obtain activated slurry. After stirring, the slurry enters the next stage process.

[0027] (3) Reduction magnetization roasting: The activated slurry is continuously fed into the fluidized bed furnace, the reduction temperature is controlled at 850℃, the furnace bottom pressure is controlled at 12000Pa, the blower is controlled to maintain stable air flow, the excess air coefficient is controlled at 0.8, and oxygen-deficient roasting is maintained, so that most of the sulfur is oxidized into sulfur dioxide SO2 and enters the flue gas in the form of gas. After dry dust removal, wet dust removal, electrostatic dust removal, conversion and dry absorption processes, industrial sulfuric acid is produced, and a small amount enters the slag and flue dust in the form of sulfate. At the same time, the iron in the cyanide gold extraction tailings is converted into magnetic iron Fe3O4, and the mineral particles become porous and loose. The gold-encapsulating compounds such as sulfides, metal oxides, and silicon dioxide are effectively decomposed, and the mineral structure is accurately transformed. The reduced magnetized roasted sand contains 2.5g / t of gold, 20g / t of silver, 0.2wt% of sulfur, and 25wt% of iron, and enters the next stage process.

[0028] (4) Flotation recovery of gold and silver: Reduced magnetized roasted sand enters a wet overflow mill, grinding time is 10 min, grinding fineness is -0.074 mm accounting for 90%, sodium sulfide 200 g / t, sodium carbonate 200 g / t, copper sulfate 300 g / t are added, butyl xanthate and butyl ammonium black are used as collectors, the dosage is 80 g / t and 40 g / t respectively, the pulp concentration is adjusted to 20 wt%, after one roughing, two scavenging and two cleaning process, gold concentrate with 30 g / t gold and 230 g / t silver is produced, gold concentrate is returned to the gold extraction system; flotation tailings with 0.5 g / t gold, 10 g / t silver and 35 wt% iron are sent to the next stage process;

[0029] (5) Magnetic separation to recover iron concentrate: Adjust the concentration of flotation tailings slurry to 18wt%, and enter the CTB1024 magnetic separator with a high magnetic induction intensity of 1200 Gauss. The magnetic separation process of one roughing and two cleaning is adopted to produce iron concentrate with 60wt% iron content. The iron recovery rate reaches 92%. The tailings after magnetic separation are used as raw materials for building materials production.

[0030] Example 2:

[0031] A method for the comprehensive recovery of gold, sulfur, and iron from cyanide gold extraction tailings includes the following steps:

[0032] (1) Precise mixing and blending of ore: According to the composition and characteristics of cyanide tailings, direct cyanide tailings contain 1.15 g / t of gold, 10 g / t of silver, 25 wt% of sulfur, and 20 wt% of iron; roasted cyanide tailings contain 3.5 g / t of gold, 35 g / t of silver, 1.0 wt% of sulfur, and 32.5 wt% of iron. Direct cyanide tailings and roasted cyanide tailings are mixed at a mass ratio of 1:2, with a stirring speed of 30 r / min and a mixing time of 2 h. The mixed cyanide tailings material is then introduced into the next stage of the process.

[0033] (2) Additive activation: Additives are added to the mixed cyanide tailings material at a rate of 40 kg / t. The additives are lead nitrate, sodium hydroxide, sodium sulfate, sodium sulfide, and sodium carbonate compounds. The lead content accounts for 0.3 wt% of the mixed minerals. The weight ratio of sodium hydroxide, sodium sulfate, sodium sulfide, and sodium carbonate is 1:1:1:3. Water is added to adjust the slurry concentration to 65 wt% (based on dry ore percentage). The temperature is 65℃, and the slurry is stirred and activated at normal pressure for more than 4 hours to obtain activated slurry. After stirring, the slurry enters the next stage process.

[0034] (3) Reduction magnetization roasting: The activated slurry is continuously fed into the fluidized bed furnace, the reduction temperature is controlled at 875℃, the furnace bottom pressure is 14000Pa, the blower is controlled to maintain stable air flow, the excess air coefficient is controlled at 0.9, and oxygen-deficient roasting is maintained so that most of the sulfur is oxidized into sulfur dioxide SO2 and enters the flue gas in the form of gas. After dry dust removal, wet dust removal, electrostatic dust removal, conversion and dry absorption processes, industrial sulfuric acid is produced, and a small amount enters the slag and flue dust in the form of sulfate. At the same time, the iron in the cyanide gold extraction tailings is converted into magnetic iron Fe3O4, and the mineral particles become porous and loose. The gold-encapsulating compounds such as sulfides, metal oxides, and silicon dioxide are effectively decomposed, and the mineral structure is accurately transformed. The reduced magnetized roasted sand contains 3.5g / t of gold, 30g / t of silver, 0.35wt% of sulfur, and 20wt% of iron, and enters the next stage process.

[0035] (4) Flotation recovery of gold and silver: Reduced magnetized roasted sand enters a wet overflow mill, grinding time is 12.5 min, grinding fineness is -0.074 mm accounting for 92.5%, sodium sulfide 300 g / t, sodium carbonate 300 g / t, copper sulfate 400 g / t are added, butyl xanthate and butyl ammonium black powder are used as collectors, the dosage is 100 g / t and 50 g / t respectively, the pulp concentration is adjusted to 25 wt%, after one roughing, two scavenging and two cleaning process, gold concentrate with gold content of 40 g / t and silver content of 310 g / t is produced, gold concentrate is returned to the gold extraction system; flotation tailings with gold content of 0.5 g / t, silver content of 10 g / t and iron content of 37.5 wt% enter the next stage process;

[0036] (5) Magnetic separation to recover iron concentrate: Adjust the concentration of flotation tailings slurry to 23wt%, and enter the CTB1024 magnetic separator with a high magnetic induction intensity of 1350 Gauss. The process of one roughing and two cleaning magnetic separations is adopted to produce iron concentrate with 61.5wt% iron content. The iron recovery rate reaches 93%. The tailings after magnetic separation are used as raw materials for building materials production.

[0037] Example 3:

[0038] A method for the comprehensive recovery of gold, sulfur, and iron from cyanide gold extraction tailings includes the following steps:

[0039] (1) Precise mixing and blending of ore: According to the composition and characteristics of cyanide tailings, direct cyanide tailings contain 1.60 g / t of gold, 15 g / t of silver, 30 wt% of sulfur, and 25 wt% of iron; roasted cyanide tailings contain 5.5 g / t of gold, 50 g / t of silver, 1.5 wt% of sulfur, and 40 wt% of iron; direct cyanide tailings and roasted cyanide tailings are mixed at a mass ratio of 1:3, with a stirring speed of 40 r / min and a mixing time of 3 h. The mixed cyanide tailings material is then introduced into the next stage of the process.

[0040] (2) Additive activation: Additives are added to the mixed cyanide tailings material at a rate of 50 kg / t. The additives are lead nitrate, sodium hydroxide, sodium sulfate, sodium sulfide, and sodium carbonate compounds. The lead content accounts for 0.4 wt% of the mixed minerals. The weight ratio of sodium hydroxide, sodium sulfate, sodium sulfide, and sodium carbonate is 1:1:1:3. Water is added to adjust the slurry concentration to 70 wt% (based on dry ore percentage). The temperature is 70℃, and the slurry is stirred and activated at normal pressure for more than 4 hours to obtain activated slurry. After stirring, the slurry enters the next stage process.

[0041] (3) Reduction magnetization roasting: The activated slurry is continuously fed into the fluidized bed furnace, the reduction temperature is controlled at 900℃, the furnace bottom pressure is controlled at 16000Pa, the blower is controlled to maintain stable air flow, the excess air coefficient is controlled at 1.0, and oxygen-deficient roasting is maintained so that most of the sulfur is oxidized into sulfur dioxide SO2 and enters the flue gas in the form of gas. After dry dust removal, wet dust removal, electrostatic dust removal, conversion and dry absorption processes, industrial sulfuric acid is produced, and a small amount enters the slag and flue dust in the form of sulfate. At the same time, the iron in the cyanide gold extraction tailings is converted into magnetic iron Fe3O4, and the mineral particles become porous and loose. The gold-encapsulating compounds such as sulfides, metal oxides, and silicon dioxide are effectively decomposed, and the mineral structure is accurately transformed. The reduced magnetized roasted sand contains 4.5g / t of gold, 40g / t of silver, 0.5wt% of sulfur, and 35wt% of iron, and enters the next stage process.

[0042] (4) Flotation recovery of gold and silver: Reduced magnetized roasted sand is fed into a wet overflow mill for 15 minutes. The grinding fineness is -0.074 mm, accounting for 95%. Sodium sulfide 400 g / t, sodium carbonate 400 g / t, and copper sulfate 500 g / t are added. Butyl xanthate and butyl ammonium black are used as collectors at dosages of 120 g / t and 60 g / t, respectively. The pulp concentration is adjusted to 30 wt%. After one roughing, two scavenging, and two cleaning processes, a gold concentrate containing 50 g / t of gold and 380 g / t of silver is produced. The gold concentrate is returned to the gold extraction system. The flotation tailings containing 0.5 g / t of gold, 10 g / t of silver, and 40 wt% of iron are sent to the next stage.

[0043] (5) Magnetic separation to recover iron concentrate: Adjust the concentration of flotation tailings slurry to 28wt%, and enter the CTB1024 magnetic separator with a high magnetic induction intensity of 1500 Gauss. The magnetic separation process of one roughing and two cleaning is adopted to produce iron concentrate with 63wt% iron content. The iron recovery rate reaches 94%. The tailings after magnetic separation are used as raw materials for building materials production.

[0044] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for the comprehensive recovery of gold, sulfur, and iron from cyanide gold extraction tailings, characterized in that, Includes the following steps: (1) Mixing and blending: Direct cyanide tailings and roasted cyanide tailings are mixed at a mass ratio of 1:1~3 to obtain mixed cyanide tailings material. (2) Additive activation: Additives are added to the mixed cyanide tailings material, including lead-containing substances, sodium hydroxide, sodium sulfate, sodium sulfide and sodium carbonate; then water is added to adjust the slurry concentration to 60wt%~70wt% of dry ore, the temperature is 60~70℃, and the slurry is activated by stirring at normal pressure for more than 4 hours to obtain activated slurry. (3) Reduction magnetization roasting: The activated slurry is continuously fed into the fluidized bed furnace for reduction magnetization roasting to obtain reduced magnetized roasted sand and flue gas; The reduction magnetization calcination temperature is 850~900℃, the furnace bottom pressure is 12000~16000Pa, and the excess air coefficient is controlled at 0.8~1.0; (4) Flotation recovery of gold and silver: After grinding the reduced magnetized roasted sand, sodium sulfide, sodium carbonate and copper sulfate are added. Butyl xanthate and butyl ammonium black powder are used as collectors. The pulp concentration is adjusted to 20~30wt%. After one roughing, two scavenging and two cleaning processes, gold concentrate and flotation tailings are produced. (5) Magnetic separation to recover iron concentrate: Adjust the concentration of flotation tailings slurry to 18~28wt%, and enter the magnetic separator with a high magnetic induction intensity of 1200~1500 Gauss. Use a one-stage roughing and two-stage cleaning magnetic separation process to produce iron concentrate and magnetically separated tailings.

2. The method for comprehensive recovery of gold, sulfur, and iron from cyanide gold extraction tailings according to claim 1, characterized in that, In step (1), the stirring speed is 20~40 r / min and the mixing time is 1~3 h.

3. The method for comprehensive recovery of gold, sulfur, and iron from cyanide gold extraction tailings according to claim 1, characterized in that, In step (2), the lead-containing substance is lead-containing mineral and / or lead nitrate.

4. The method for comprehensive recovery of gold, sulfur, and iron from cyanide gold extraction tailings according to claim 1, characterized in that, In step (2), the amount of additive added is 30~50kg / t, the lead content in the additive accounts for 0.2~0.4wt% of the mixed cyanide tailings material, and the weight ratio of sodium hydroxide, sodium sulfate, sodium sulfide and sodium carbonate is 1:1:1:

3.

5. The method for comprehensive recovery of gold, sulfur, and iron from cyanide gold extraction tailings according to claim 1, characterized in that, The flue gas obtained in step (3) is processed through dry dust removal, wet dust removal, electrostatic precipitator, conversion, and dry absorption processes to produce industrial sulfuric acid.

6. The method for comprehensive recovery of gold, sulfur, and iron from cyanide gold extraction tailings according to claim 1, characterized in that, In step (4), the grinding time is 10-15 minutes, and the grinding fineness is -0.074 mm, accounting for 90-95%.

7. The method for comprehensive recovery of gold, sulfur, and iron from cyanide gold extraction tailings according to claim 1, characterized in that, In step (4), the amount of sodium sulfide added is 200~400g / t, the amount of sodium carbonate is 200~400g / t, the amount of copper sulfate is 300~500g / t, the amount of butyl xanthate is 80~120g / t, and the amount of butyl ammonium black powder is 40~60g / t.