Process for extracting gold from Carlin type gold ore

Abstract

The invention discloses a process for extracting gold from Carlin type gold ore, and relates to the technical field of precious metal metallurgy, the process comprises the following steps: a flotation step: crushing and grinding the Carlin type gold ore, and then carrying out flotation operation to obtain flotation concentrate and flotation tailings; an oxidation step: acidizing the ore pulp of the flotation concentrate, and oxidizing the acidized ore pulp; concentrate and tailings are mixed, specifically, ore pulp of the flotation tailings and ore pulp of the flotation concentrate obtained after oxidation treatment are mixed, and an organic carbon screening agent is added into the ore pulp mixture; and a leaching step: adding anion exchange resin and sodium cyanide into the ore pulp mixture added with the organic carbon screening agent to obtain leached gold. According to the method, the total gold recovery rate of the carlin type gold ore can be greatly increased.

Description

Technical Field

[0001] The invention relates to precious metal metallurgy technology, in particular to a process for extracting gold from Carlin-type gold ore. Background Art

[0002] Carlin-type gold deposits are a kind of doubly difficult-to-carry gold deposits. First, because gold is mostly in the form of invisible gold in pyrite and arsenopyrite, it is necessary to destroy the crystal structure of these sulfides to release gold for further extraction. At the same time, the organic carbon content of Carlin-type gold deposits is very high. These organic carbons are highly chemically active and have a strong adsorption capacity for gold complex ions dissolved during the leaching process, which leads to the inability to recover or loss of gold.

[0003] Existing technologies often use the following processes to extract gold from Carlin-type gold deposits, but the gold recovery rate is generally not high: 1. Direct cyanide leaching-activated carbon adsorption process. The gold recovery rate of this process is usually below 30%.

[0004] 2. Roasting-carbon leaching process. This process usually includes direct fuel roasting of ore and roasting of concentrate produced by crushing and grinding the ore and then flotation. However, since the ore contains a large amount of arsenic and mercury, the roasting fume contains arsenic and mercury, which is harmful to the health of production personnel and the environment.

[0005] 3. Flotation-oxidation-carbon leaching process. After ore crushing and grinding, flotation technology is used to enrich gold and remove components that are unfavorable to downstream operations. The flotation concentrate decomposes the sulfide ore to release the encapsulated gold, and then carbon leaching is used to recover the gold from the oxidation slag. However, the organic carbon of the ore during carbon leaching will also enter the flotation concentrate, and the organic carbon is usually not destroyed during the wet oxidation process. Therefore, these organic carbons will still adsorb ionic gold during carbon leaching of gold, resulting in a low leaching recovery rate.

[0006] 4. Sodium thiosulfate leaching process. Sodium thiosulfate is used instead of sodium cyanide as the leaching agent for gold. However, this process has the disadvantages of large consumption of sodium thiosulfate, high production cost and low recovery rate.

[0007] Therefore, the present invention is expected to provide a new process for extracting gold from Carlin-type gold ore, which can significantly improve the gold recovery rate. Summary of the invention

[0008] In view of the above defects or deficiencies in the prior art, the present invention provides a process for extracting gold from Carlin-type gold ore, including comprehensive process steps such as flotation concentrate oxidation, organic carbon shielding gold robbing, flotation oxidized slag and flotation tailings merging, anion exchange resin adsorption, etc. The present invention can greatly improve the total gold recovery rate of Carlin-type gold ore.

[0009] One aspect of the present invention provides a process for extracting gold from Carlin-type gold ore, comprising: Flotation step: crush and grind the Carlin-type gold ore and then perform flotation operation to obtain flotation concentrate and flotation tailings; Oxidation step: after acidifying the pulp of the flotation concentrate, the pulp after acidification is oxidized; The step of mixing the concentrate and tailings: mixing the pulp of the flotation tailings with the pulp of the flotation concentrate after oxidation treatment, and adding an organic carbon shielding agent to the pulp mixture; Leaching step: adding anion exchange resin and sodium cyanide to the ore pulp mixture to which the organic carbon shielding agent is added to obtain leached gold; Among them, the anion exchange resin meets the following index requirements: The exchange capacity is greater than 2.8 mmol / g; Wet apparent density is 0.6-0.75 g / ml; The content of resin with particle size less than 0.85 mm is less than 0.5% of the total weight; The average particle size is 0.9-1.3 mm; The resin particle size range is 0.7-1.6 mm; True specific gravity is 1.04-1.08 g / ml; Having a divinylbenzene copolymer backbone; And, having at least one of a tertiary ammonium functional group and a quaternary ammonium functional group.

[0010] Furthermore, the flotation step further comprises: Crushing: The Carlin-type gold ore is crushed and ground into particles, of which particles with a size of less than 75 microns account for 60-90% by weight; Roughing operation: copper sulfate is added to the pulverized Carlin-type gold ore at a dosage of 400-800 g / t of feed ore, high-grade xanthate is added at a dosage of 600-1500 g / t of feed ore, MBT is added at a dosage of 300-500 g / t of feed ore, and frother is added at a dosage of 60-200 g / t of feed ore to obtain roughing concentrate and roughing tailings; First scavenging operation: Add high-grade xanthate at a dosage of 200-600 g / t of feed ore, MBT at a dosage of 50-200 g / t of feed ore, and frother at a dosage of 10-30 g / t of feed ore to the pulp of the rougher tailings, and perform the first scavenging on the rougher tailings to obtain the concentrate and tailings after the first scavenging; Concentration of concentrate after the first scavenging: Add high-grade xanthate at a dosage of 50-300 g / t of feed ore, MBT at a dosage of 20-100 g / t of feed ore, and frother at a dosage of 10-30 g / t of feed ore to the concentrate slurry after the first scavenging to obtain concentrated ore and concentrated tailings; Second scavenging operation: combining the tailings after the first scavenging with the selected tailings, adding high-grade xanthate at a dosage of 100-300 g / ton of feed ore, adding MBT at a dosage of 20-100 g / ton of feed ore, and adding a frother at a dosage of 10-30 g / ton of feed ore to the combined mineral slurry, to obtain the concentrate and tailings after the second scavenging; Combining the concentrate after the second scavenging and the rougher tailings, and using the combined minerals as feed for the first scavenging operation of the next round of flotation; The rougher concentrate and the concentrated concentrate are combined into the flotation concentrate of this round of flotation, and the tailings after the second scavenging are used as the flotation tailings of this round of flotation.

[0011] Furthermore, the oxidation step further comprises: Adding sulfuric acid to the pulp of the flotation concentrate until the pulp is acidified to a pH value of 0.5-1.5 and maintaining the pH value for 2-4 hours; The acidified slurry is added to the high-pressure oxidation kettle, heated to 190-225°C, and the pressure is maintained at 2900-3500kPa, and oxygen is introduced for high-pressure oxidation reaction; The slurry after high-pressure oxidation is removed from the high-pressure oxidation autoclave, the slurry temperature is maintained at 70-95° C., stirred for 6-8 hours, and then cooled to ambient temperature.

[0012] Furthermore, the step of mixing the concentrate and tailings further comprises: Adding flotation tailings slurry to the flotation concentrate slurry after oxidation treatment, wherein the solid weight in the flotation tailings slurry accounts for 45-65% of the slurry weight, and the solid weight in the flotation concentrate slurry accounts for 35-45% of the slurry weight; An organic carbon shielding agent is added to the mixed slurry of flotation concentrate and flotation tailings, and the organic carbon shielding agent and the slurry are mixed evenly.

[0013] Furthermore, the leaching step further comprises: Add lime to the mixed slurry with organic carbon shielding agent to adjust the pH value to above 10.2; Add anion exchange resin to the alkalized mixed slurry at a dosage of 20-60 g / L and stir evenly; Sodium cyanide is added as a leaching agent in a dosage of 0.2-2.5 kg / L to the mixed slurry to which anion exchange resin is added, and the leaching time is 18-72 hours.

[0014] Furthermore, the heating temperature in the high-pressure oxidation autoclave is maintained at 215° C., and the pressure is maintained at 3300 kPa.

[0015] Furthermore, the oxidation step further comprises: Adding sulfuric acid to the pulp of the flotation concentrate until the pulp is acidified to a pH value of 1.0-2.0; Pyrite oxidizing bacteria are added to the acidified slurry, the oxidation temperature is maintained at 30-55°C, and the oxidation time is 7-18 days.

[0016] Further, the step of adding an organic carbon shielding agent to the slurry mixture comprises: Adding oily hydrocarbons or colloidal hydrocarbons as organic carbon shielding agents to the ore pulp mixture at a dosage of 500-3000 g / t of ore; Alternatively, MBT is added to the slurry mixture at a dosage of 100-500 g / t of feed ore as an organic carbon shielding agent.

[0017] Furthermore, the advanced xanthate includes one or more of butyl xanthate, amyl xanthate and isobutyl xanthate.

[0018] Furthermore, it also includes: Diesel fuel was added to the slurry mixture at a dosage of 1500 g / t of ore as an organic carbon shielding agent; Alternatively, MBT was added as an organic carbon shielding agent in the slurry mixture at a dosage of 200 g / t of feed ore.

[0019] The process for extracting gold from Carlin-type gold ore provided by the present invention has the following beneficial effects: (1) The present invention uses anion exchange resin with optimal parameters to replace activated carbon as a gold cyanide complex ion adsorbent, which greatly reduces the adsorption rate of the adsorbent to the organic carbon shielding agent and the flotation organic reagent, ensures that the adsorption capacity of the adsorbent to the gold cyanide complex ion is not affected, and thus improves the leaching recovery rate of gold; (2) The residual flotation organic reagent in the flotation tailings in the prior art will affect the adsorption capacity of the activated carbon adsorbent for gold cyanide complex ions, which makes it impossible for the flotation tailings containing a large amount of flotation organic reagents to be used together with the oxidized slag of the flotation concentrate for gold leaching. This causes the flotation tailings to be unutilized, that is, the mineral utilization rate is not 100%, resulting in the inability to further improve the total recovery rate of gold. The present invention uses an anion exchange resin with preferred parameters to replace activated carbon as a gold cyanide complex ion adsorbent. Since the anion exchange resin with preferred parameters will not adsorb the flotation organic reagent and the organic carbon shielding agent, the adsorption capacity of the adsorbent for gold cyanide complex ions will not decrease. Therefore, the present invention can combine the flotation tailings containing the flotation organic reagent with the acidic oxidized slag of the flotation concentrate for treatment, and use the acid in the acidic oxidized slag of the flotation concentrate to clean the carbonate in the flotation tailings. The flotation tailings are fully utilized, thereby greatly improving the total recovery rate of gold; (3) The present invention improves the flotation process of Carlin-type gold ore. Under the condition of the same weight of feed ore, the new flotation process can obtain more flotation concentrate than the traditional flotation process, that is, the flotation recovery rate is improved. The increase in the proportion of flotation concentrate further drives the improvement of leaching recovery rate.

[0020] (4) The overall process of the present invention increases the total recovery rate of Carlin-type gold ore from the traditional 50%-65% to more than 80%, that is, the total recovery rate is increased by nearly 15%. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings: Figure 1 It is a flow chart of the process for extracting gold from Carlin-type gold ore provided by the present invention; Figure 2 The flotation process provided by the present invention is Figure 1 ; Figure 3 The flotation process provided by the present invention is Figure 2 . DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0024] It should be understood that although the terms first, second, third, etc. may be used to describe the acquisition modules in the embodiments of the present invention, the acquisition modules should not be limited to these terms. These terms are only used to distinguish the acquisition modules from each other.

[0025] The word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to determining" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)", depending on the context.

[0026] It should be noted that the directional words such as "upper", "lower", "left", and "right" described in the embodiments of the present invention are described at the angles shown in the drawings and should not be understood as limiting the embodiments of the present invention. In addition, in the context, it should also be understood that when it is mentioned that an element is formed "on" or "under" another element, it can not only be formed directly "on" or "under" another element, but also be formed "on" or "under" another element indirectly through an intermediate element.

[0027] Carlin-type gold ore is a doubly refractory gold ore. Table 1 shows the analysis results of the chemical components of Carlin-type gold ore in a certain region. Gold is mostly in the form of invisible gold in pyrite and arsenopyrite. It is necessary to destroy the crystal structure of these sulfides to release gold for further extraction. In addition, Carlin-type gold ore contains a high content of organic carbon, which has high chemical activity and has a strong adsorption capacity for dissolved gold cyanide complex ions during the leaching process, which leads to the inability to recover gold or a large loss.

[0028] Table 1 Au Ag S2- As Organic Carbon Au_LW PRI Hg Cu g / t g / t % ppm % g / t g / t ppm ppm 5.96 11.40 1.42 287 0.60 <0.2 4.2 6.50 0.04 To address the above technical problems, the prior art has adopted direct cyanide leaching-activated carbon adsorption process, roasting-carbon leaching process, flotation-oxidation-carbon leaching process, sodium thiosulfate leaching process, etc. However, these gold extraction processes have defects such as high production cost and serious pollution, and the gold recovery rate is controlled at about 50%-65%.

[0029] In one embodiment of the present invention, in view of the problem of low gold recovery rate of Carlin-type gold mines in the prior art, a new process for extracting gold from Carlin-type gold ore is proposed, by adopting a new flotation process, replacing activated carbon with an anion exchange resin with optimal parameters as a gold cyanide complex ion adsorbent, and combining the flotation tailings containing flotation organic reagents with the acidic oxidized slag of the flotation concentrate for treatment, the total gold recovery rate is further improved.

[0030] See also Figure 1 The process of extracting gold from Carlin-type gold ore in this embodiment includes a flotation step S101, an oxidation step S102, a concentrate and tailings mixing step S103, and a leaching step S104. The specific process flow is as follows: In the flotation step S101, the Carlin-type gold ore is crushed and ground and then subjected to flotation operation to obtain flotation concentrate and flotation tailings.

[0031] See also Figure 2 and Figure 3 This embodiment improves the traditional flotation process. On the one hand, it improves the flotation recovery rate of gold. The increase in the proportion of flotation concentrate further drives the improvement of leaching recovery rate.

[0032] The flotation process of this embodiment specifically includes: Crushing step S1011: crushing and grinding the Carlin-type gold ore into granular mineral powder, wherein the weight of particles with a particle size of less than 75 microns accounts for 60-90%, preferably more than 80%. The present invention has found through experiments that the grinding fineness has a direct impact on the flotation recovery rate and leaching recovery rate of the final gold ore. When the weight of particles with a particle size of less than 75 microns accounts for more than 80%, the flotation recovery rate and leaching recovery rate will be significantly improved.

[0033] Roughing step S1012: copper sulfate is added to the slurry of the crushed Carlin-type gold ore at a dosage of 400-800 g / ton of feed ore, high-grade xanthate is added at a dosage of 600-1500 g / ton of feed ore, MBT is added at a dosage of 300-500 g / ton of feed ore, and a frother is added at a dosage of 60-200 g / ton of feed ore to obtain a roughing concentrate and a roughing tailings.

[0034] Specifically, the crushed ore powder is put into a flotation machine for flotation, and copper sulfate is added to the formed slurry at a dosage of 400-800 g / ton of feed ore (preferably 600 g / ton of feed ore), isobutyl xanthate is added at a dosage of 600-1500 g / ton of feed ore (preferably 1200 g / ton of feed ore), MBT is added at a dosage of 300-500 g / ton of feed ore (preferably 400 g / ton of feed ore), and No. 2 oil (R-alkane group) is added at a dosage of 60-200 g / ton of feed ore (preferably 100 g / ton of feed ore) as a frother to obtain a rougher concentrate and a rougher tailings.

[0035] It should be pointed out that the roughing operation is to recover most of the gold-bearing minerals. The roughing operation replaces the iron ions on the surface of the gold-bearing pyrite with copper ions through copper sulfate, which makes it easier to bond with high-grade xanthate. High-grade xanthate is more easily adsorbed on the surface of the mineral, making the mineral hydrophobic, thereby floating the gold. The frother can better selectively float the mineral particles. MBT (i.e., 2-mercaptobenzothiazole) is used as a collector to enhance the flotation of metallic gold. In addition, the amount of the above-mentioned reagents is added in units of "grams / ton of feed ore". The feed here refers to the material that has not been flotated and entered the flotation operation. Therefore, the weight of the feed is the weight of the untreated fixed mineral in each step, not the weight of the pulp. The above-mentioned high-grade xanthate refers to a xanthate with a carbon chain length / carbon atom number greater than or equal to 4, such as a mixture of any one or more of butyl xanthate, amyl xanthate and isobutyl xanthate.

[0036] The first scavenging step S1013: adding high-grade xanthate at a dosage of 200-600 g / ton of feed ore, adding MBT at a dosage of 50-200 g / ton of feed ore, and adding a frother at a dosage of 10-30 g / ton of feed ore to the pulp of the roughing tailings, and performing the first scavenging on the roughing tailings to obtain the concentrate and tailings after the first scavenging.

[0037] Specifically, the first scavenging step is for roughing tailings, and the purpose is to recover gold-bearing particles with slow flotation speed. In order to make full use of the residual reagents in the roughing tailings pulp, the amount of reagents in this step can be selected to be lower than the amount of reagents in the roughing step, wherein if sufficient copper sulfate is added in the roughing operation, copper sulfate can be no longer added in this step. Preferably, isobutyl xanthate or other high-grade xanthate is added in a dosage of 200-600 g / ton of feed (more preferably 400 g / ton of feed), MBT is added in a dosage of 50-200 g / ton of feed (more preferably 100 g / ton of feed), and No. 2 oil (R-alkane group) is added in a dosage of 10-30 g / ton of feed (more preferably 20 g / ton of feed) as a foaming agent in the pulp of the roughing tailings, and the roughing tailings are scavenged for the first time to obtain concentrates and tailings after the first scavenging. After the first scavenging step, the rougher tailings can be further flotated to extract a concentrate with a higher gold content from the rougher waste tailings.

[0038] Step S1014 of beneficiating the concentrate after the first scavenging: adding high-grade xanthate at a dosage of 50-300 g / t of feed ore, adding MBT at a dosage of 20-100 g / t of feed ore, and adding a frother at a dosage of 10-30 g / t of feed ore to the concentrate slurry after the first scavenging to obtain beneficiated concentrate and beneficiated tailings; Specifically, the concentrate after the first scavenging is a concentrate floated from the roughing tailings, not a concentrate floated from the original gold ore, so the gold content of the concentrate after the first scavenging is still lower than that of the roughing concentrate. In order to increase the gold content in the concentrate as much as possible, the concentrate after the first scavenging is again concentrated in this step. Preferably, isobutyl xanthate or other high-grade xanthate is added to the concentrate slurry after the first scavenging at a dosage of 50-300 g / ton of feed (more preferably 200 g / ton of feed), MBT is added at a dosage of 20-100 g / ton of feed (more preferably 50 g / ton of feed), and a frother is added at a dosage of 10-30 g / ton of feed (more preferably 20 g / ton of feed) to obtain a concentrated concentrate and a concentrated tailing. It should be pointed out that if sufficient copper sulfate is added in the roughing operation, copper sulfate may no longer be added in this step.

[0039] Second scavenging step S1015: Combine the tailings after the first scavenging and the selected tailings, add high-grade xanthate at a dosage of 100-300 g / ton of feed ore, add MBT at a dosage of 20-100 g / ton of feed ore, and add a frother at a dosage of 10-30 g / ton of feed ore to the combined mineral slurry to obtain the concentrate and tailings after the second scavenging.

[0040] Specifically, in order to further increase the gold content in the tailings, the tailings after the first scavenging and the concentrated tailings are combined, and then the combined tailings are subjected to a second scavenging operation. Because there are residual reagents in the roughing and the first scavenging, in order to make full use of the residual reagents, the amount of reagents added in the second scavenging operation can be equal to or lower than the amount of reagents in the first scavenging. Preferably, isobutyl xanthate or other high-grade xanthate is added to the slurry of the combined minerals at a dosage of 100-300 g / ton of feed (more preferably 200 g / ton of feed), MBT is added at a dosage of 20-100 g / ton of feed (more preferably 50 g / ton of feed), and No. 2 oil (R-alkane group) is added at a dosage of 10-30 g / ton of feed (more preferably 20 g / ton of feed) as a foaming agent to obtain the concentrate and tailings after the second scavenging.

[0041] Step S1016, combining the concentrate after the second scavenging and the rougher tailings, and using the combined minerals as feed for the first scavenging operation of the next round of flotation.

[0042] Specifically, since the concentrate after the second scavenging is obtained based on the tailings and the selected tailings after the first scavenging, the gold content of these tailings is lower than that of the original gold ore, so the gold content in the concentrate after the second scavenging is roughly similar to the gold content of the rougher tailings, so in this step, the concentrate after the second scavenging and the rougher tailings are combined as the feed for the first scavenging operation of the next round of flotation. In this way, the under-extracted tailings can be more fully utilized, and through multiple rounds of scavenging extraction, the proportion of the final flotation concentrate is much higher than that of the existing flotation process, laying a foundation for improving the leaching recovery rate and total recovery rate of gold.

[0043] Step S1017, combining the rougher concentrate and the concentrated concentrate into the flotation concentrate of this round of flotation, and using the tailings after the second scavenging as the flotation tailings of this round of flotation.

[0044] Specifically, since the gold content of the concentrated concentrate is close to that of the rougher concentrate, the rougher concentrate and the concentrated concentrate are combined as the final flotation concentrate of this round of flotation, and the flotation concentrate is used in the subsequent oxidation step. In addition, since the tailings after the second scavenging are tailings obtained after multiple rounds of scavenging operations, the gold content in the tailings is low, and it is difficult to float the gold-containing materials again through the scavenging process, so the tailings after the second scavenging are used as the final flotation tailings of this round of flotation.

[0045] The improved flotation process of this embodiment can greatly increase the proportion of flotation concentrate, improve the flotation recovery rate, achieve full flotation and effective utilization of original minerals, and lay a foundation for improving subsequent leaching recovery rate and total recovery rate.

[0046] In the oxidation step S102, the pulp of the flotation concentrate is subjected to an acidification treatment, and then the pulp after the acidification treatment is subjected to an oxidation treatment.

[0047] Specifically, in order to oxidize the sulfide minerals in the flotation concentrate, the flotation concentrate needs to be oxidized, but there are a large number of carbonate minerals in the flotation concentrate, which will decompose into a large amount of carbon dioxide during the oxidation process, thereby affecting the oxidation treatment. In order to solve this technical problem, the present invention performs acidification treatment before oxidation treatment, and then performs high-pressure oxidation or bacterial oxidation, including:

[0048] Step S1021, adding sulfuric acid to the pulp of the flotation concentrate and stirring evenly until the pulp is acidified to a pH value of 0.5-1.5, preferably a pH value of 1, and maintaining it for 2-4 hours, at which time the carbonate minerals will be dissolved, so that a large amount of carbon dioxide will not be formed in the subsequent oxidation process; Step S1022, adding the acidified slurry to a high-pressure oxidation autoclave, heating to 190-225°C, preferably 215°C, and maintaining the pressure at 2900-3500 kPa, preferably 3300 kPa, and introducing oxygen for high-pressure oxidation reaction for about 1 hour; Step S1023, remove the slurry after high-pressure oxidation from the high-pressure oxidation autoclave, maintain the slurry temperature at 70-95°C, preferably 80°C, stir for 6-8 hours, and then cool to ambient temperature.

[0049] Optionally, high pressure oxidation is replaced by bacterial oxidation, using commercial pyrite oxidizing bacterial strains, adding sulfuric acid to the flotation concentrate slurry until the environmental pH value is 1.0-2.0 to obtain the best bacterial oxidation environment, the oxidation temperature is set at 30-55°C, and the oxidation time is 7-18 days.

[0050] In the step S103 of mixing the concentrate and the tailings, the pulp of the flotation tailings and the pulp of the flotation concentrate after oxidation treatment are mixed, and an organic carbon shielding agent is added to the pulp mixture.

[0051] Specifically, in theory, if the total recovery rate of gold is to be improved, the flotation tailings must be fully utilized. However, in reality, it is impossible to leach the flotation tailings and the oxide slag of the flotation concentrate together, because there are a large number of flotation organic agents in the flotation tailings. These flotation organic agents will be adsorbed by the activated carbon adsorbent in large quantities, thereby reducing the adsorption capacity of the activated carbon adsorbent for gold cyanide complex ions, resulting in a decrease in the gold leaching rate. In the subsequent leaching step S104, the present invention adopts anion exchange resin with preferred parameters instead of activated carbon as an adsorbent. The anion exchange resin with preferred parameters will not adsorb the flotation organic reagent, and thus will not affect the adsorption of the anion exchange resin with preferred parameters on gold cyanide complex ions. In this way, the present invention can combine the flotation tailings containing the flotation organic reagent with the acidic oxidized slag of the flotation concentrate for treatment, and use the residual acidic substances in the acidic oxidized slag of the flotation concentrate to clean the carbonate in the flotation tailings. Since the gold in the flotation tailings does not exist in large quantities in sulfides but in large quantities in quartz, the flotation tailings in the present invention do not need to be oxidized, and are preferably leached together with the oxidized slag of the flotation concentrate, so that the flotation tailings are fully utilized, further improving the total recovery rate of gold.

[0052] The mixing process of flotation concentrate and flotation tailings includes: Step S1031, cooling the flotation concentrate slurry after oxidation treatment to ambient temperature; Step S1032, adding flotation tailings slurry to the flotation concentrate slurry after oxidation treatment, wherein the solid weight in the flotation tailings slurry accounts for 45-65% of the slurry weight, and the solid weight in the flotation concentrate slurry accounts for 35-45% of the slurry weight. It should be pointed out that the slurry concentration should not only ensure that it is not too viscous to facilitate pumping, but also ensure that the amount of water when the mixed slurry enters the leaching step S104 later is moderate. The slurry concentration will also directly affect the diffusion rate of the components, and then affect the leaching rate and leaching rate of gold. If the slurry concentration is too high, the leaching rate and leaching rate of gold are low. Although the leaching rate and leaching rate are increased by too low slurry concentration, the equipment volume needs to be made very large, and the amount of cyanide reagents must also be invested a lot, and the equipment investment cost and reagent cost are significantly increased. The present invention has learned through experiments that the solid-liquid ratio of the above-mentioned slurry can fully meet the requirements of various aspects.

[0053] Furthermore, in order to avoid gold robbing by organic carbon in the slurry mixture, an organic carbon shielding agent is added to the slurry mixture and stirred evenly to shield the gold robbing effect of organic carbon. Wherein, the step of adding an organic carbon shielding agent specifically includes: adding oily hydrocarbons or colloidal hydrocarbons as an organic carbon shielding agent in the slurry mixture at a dosage of 500-3000 g / ton of ore; or, adding MBT as an organic carbon shielding agent in the slurry mixture at a dosage of 100-500 g / ton of ore. More preferably, diesel is added as an organic carbon shielding agent in the slurry mixture at a dosage of 1500 g / ton of ore; or, MBT is added as an organic carbon shielding agent in the slurry mixture at a dosage of 200 g / ton of ore.

[0054] In the leaching step S104, an anion exchange resin and a sodium cyanide leaching agent are added to the ore pulp mixture to which the organic carbon shielding agent is added, so as to obtain leached gold.

[0055] Specifically, the activated carbon adsorbent in the prior art will not only adsorb the gold cyanide complex ions in the ore pulp mixture, but also adsorb the organic carbon shielding agent and the residual flotation organic reagent, which will reduce the adsorption capacity of the activated carbon adsorbent for the gold cyanide complex ions, thereby reducing the total recovery rate of gold. In order to solve this technical problem, the present invention uses an anion exchange resin with preferred parameters to replace the activated carbon as an adsorbent. The anion exchange resin with preferred parameters will not adsorb the flotation reagent and the shielding agent in the mixture, so it will not affect the adsorption capacity of the adsorbent for the gold cyanide complex ions, thereby improving the total recovery rate of gold.

[0056] The anion exchange resin with the preferred parameters in this embodiment must meet the following index requirements at the same time: (1) Exchange capacity greater than 2.8 mmol / g; (2) Wet apparent density is 0.6-0.75 g / ml; (3) The content of resin with particle size less than 0.85 mm is less than 0.5% of the total weight; (4) Average particle size is 0.9-1.3 mm; (5) The resin particle size range is 0.7-1.6 mm; (6) True specific gravity is 1.04-1.08 g / ml; (7) Having a divinylbenzene copolymer skeleton; (8) Having at least one of a tertiary ammonium functional group and a quaternary ammonium functional group.

[0057] Experimental tests have shown that the anion exchange resin that meets the above-mentioned index requirements can not only ensure sufficient adsorption capacity for gold cyanide complex ions, but also will not produce excessive adsorption effect on flotation organic agents, leaching agents, organic carbon shielding agents, etc., and can ensure that after the flotation tailings and flotation concentrates are combined, there will not be too much adverse effect on the adsorption performance of the anion exchange resin for gold cyanide complex ions.

[0058] Furthermore, the leaching agent of this embodiment is preferably sodium cyanide, which is used to react with metallic gold in the ore pulp to generate liquid-phase gold-cyanide complex ions.

[0059] More specifically, the implementation process of the leaching step S104 includes: Step S1041, adding lime to the mixed slurry with the organic carbon shielding agent to adjust the pH The pH value is adjusted to above 10.2 to prevent the subsequent addition of sodium cyanide leaching agent from generating hydrocyanic acid in an environment with too low a pH value and volatilizing into toxic hydrogen cyanide gas. In addition, the volatilization of hydrocyanic acid will also lead to the loss of cyanide, thereby reducing the leaching rate of gold; Step S1042, adding the above anion exchange resin to the alkalized mixed slurry at a dosage of 20-60 g / L (preferably 40 g / L) and stirring evenly; Step S1043, sodium cyanide is added as a leaching agent at a dosage of 0.2-2.5 kg / L (preferably 1.5 kg / L) to the mixed slurry to which anion exchange resin has been added, and the leaching time is 18-72 hours, preferably 24 hours. If the leaching time is longer than 24 hours, the leaching rate will no longer change significantly.

[0060] The present invention continues to provide the following examples to illustrate the gold extraction process of the present invention.

[0061] Example 1 Step 1: Crush and grind the Carlin-type gold ore into granular mineral powder, with particles with a particle size of 53 microns accounting for 80% by weight; Step 2: Put the crushed ore powder into the flotation machine, perform roughing operation first, add copper sulfate at a dosage of 600 g / ton of feed ore, add isobutyl xanthate at a dosage of 1200 g / ton of feed ore, add MBT at a dosage of 400 g / ton of feed ore, and add No. 2 oil at a dosage of 100 g / ton of feed ore as a frother in the formed ore pulp to obtain the floating roughing concentrate and roughing tailings slurry; Step 3: adding isobutyl xanthate at a dosage of 400 g / t of feed ore, MBT at a dosage of 100 g / t of feed ore, and No. 2 oil at a dosage of 20 g / t of feed ore as a frother to the slurry of the rougher tailings, and performing a first scavenging on the rougher tailings to obtain concentrates and tailings after the first scavenging; Step 4: adding isobutyl xanthate at a dosage of 200 g / ton of feed ore, MBT at a dosage of 50 g / ton of feed ore, and frother at a dosage of 20 g / ton of feed ore to the concentrate slurry after the first scavenging to obtain concentrated ore and concentrated tailings; Step 5: Combine the tailings after the first scavenging and the selected tailings, add isobutyl xanthate at a dosage of 200 g / ton of feed, MBT at a dosage of 50 g / ton of feed, and No. 2 oil at a dosage of 20 g / ton of feed as a frother in the slurry of the combined minerals to obtain the concentrate and tailings after the second scavenging; Step 6: combining the rougher concentrate and the concentrated concentrate into the flotation concentrate of this round of flotation, and using the tailings after the second scavenging as the flotation tailings of this round of flotation; Step 7: Combine the concentrate after the second scavenging and the rougher tailings, and use the combined minerals as feed for the first scavenging operation of the next round of flotation; Step 8: Add sulfuric acid to the pulp of the flotation concentrate and stir evenly until the pulp is acidified to a pH value of 1 and maintained for 3 hours; add the acidified pulp to a high-pressure oxidation autoclave, heat to 215°C, and maintain the pressure at 300kPa, and introduce oxygen for high-pressure oxidation reaction for about 1 hour; remove the high-pressure oxidized pulp from the high-pressure oxidation autoclave, maintain the pulp temperature at 80°C, stir for 8 hours, and then cool to ambient temperature. Among them, the solid weight in the flotation concentrate pulp after oxidation accounts for 40% of the pulp weight.

[0062] Step 9: Add flotation tailings slurry to the cooled slurry, wherein the solid weight in the flotation tailings slurry accounts for 50% of the slurry weight, and the solid weight in the flotation concentrate slurry accounts for 40% of the slurry weight; add diesel as an organic carbon shielding agent to the slurry mixture at a dosage of 1500 g / ton of ore; add lime to the mixed slurry with the organic carbon shielding agent added, and adjust the pH value to 10.5; add anion exchange resin to the alkalized mixed slurry at a dosage of 40 g / L and stir evenly. The invention relates to a method for preparing a leaching agent for a mixed ore pulp containing an anion exchange resin having an exchange capacity of 4 mmol / g, a wet apparent density of 0.7 g / ml, a resin content of 0.6 mm particle size of 0.3% of the total weight, an average particle size of 1.2 mm, a resin particle size of 1.3 mm, a true specific gravity of 1.06 g / ml, a divinylbenzene copolymer skeleton, and a tertiary ammonium functional group; sodium cyanide is added as a leaching agent at a dosage of 1.5 kg / L to the mixed ore pulp to which the anion exchange resin is added, and the leaching time is 24 hours.

[0063] The flotation recovery rate, leaching recovery rate and total recovery rate of gold in the process described in Example 1 are shown in the following table.

[0064] Table 2 Serial number Process of the present invention Flotation recovery Leaching recovery rate Total recovery rate Example 1 Flotation - high pressure oxidation of concentrate - merging of concentrate oxidation slag and flotation tailings - resin 1 adsorption - sodium cyanide leaching 82.53% 80.87% 80.87% As can be seen from Table 2, since the present invention adopts anion exchange resin with preferred parameters instead of activated carbon to adsorb gold cyanide complex ions, the flotation organic agent will not be adsorbed on the anion exchange resin of the present invention, and the adsorption capacity of the resin to gold cyanide complex ions will not be reduced. Therefore, the present invention can realize the merging of the slag and flotation tailings of the flotation concentrate, which is equivalent to 100% utilization of the mineral, so the total recovery rate of gold is the leaching recovery rate multiplied by 100%, that is, the total recovery rate is equal to the leaching recovery rate. Since the adsorption capacity of the anion exchange resin with the preferred parameters of the present embodiment 1 to gold cyanide complex ions will not decrease, the leaching recovery rate is as high as 80.87%. Through the "flotation-concentrate high-pressure oxidation-concentrate slag and flotation tailings merge-resin adsorption-sodium cyanide leaching" process of the present embodiment, a total recovery rate of 80.87% can be achieved, which is much higher than the highest total recovery rate of 65% in the prior art.

[0065] Example 2 Example 2 is the same as Example 1, using the process of "flotation - high pressure oxidation of concentrate - merging of concentrate oxidation slag and flotation tailings - resin adsorption - sodium cyanide leaching" proposed by the present invention, the difference is: (1) An anion exchange resin having an exchange capacity of 3 mmol / g, a wet apparent density of 0.6 g / ml, a resin content of 0.8 mm particle size of 0.4% of the total weight, an average particle size of 1.3 mm, a resin particle size of 1.6 mm, a true specific gravity of 1.08 g / ml, a divinylbenzene copolymer skeleton, and a quaternary ammonium functional group; (2) Add anion exchange resin at a dosage of 30 g / L to the alkalized mixed slurry.

[0066] The flotation recovery rate, leaching recovery rate and total recovery rate of gold in the process of Example 2 are shown in the following table: Table 3 Serial number Process of the present invention Flotation recovery Leaching recovery rate Total recovery rate Example 2 Flotation - high pressure oxidation of concentrate - merging of concentrate oxidation slag and flotation tailings - resin 2 adsorption - sodium cyanide leaching 82.53% 80.33% 80.33% As can be seen from Table 3, the flotation recovery is the same as that in Example 1, because the flotation process has not changed. The leaching recovery is slightly lower than that in the preferred embodiment of Example 1, which can reach 80.33%, due to the use of different anion exchange resins, but is still much higher than the highest total recovery of 65% in the prior art.

[0067] Example 3 Example 3 adopts a concentrate bacterial oxidation process different from that of Example 1 and Example 2. The overall process is changed to "flotation-concentrate bacterial oxidation-concentrate oxidation slag and flotation tailings combined-resin adsorption-sodium cyanide leaching", and the parameter selection and dosage of the anion exchange resin are the same as those of Example 1. The flotation recovery rate, leaching recovery rate and total recovery rate of gold in Example 3 are shown in the following table:

[0068] Table 4 Serial number Process of the present invention Flotation recovery Leaching recovery rate Total recovery rate Example 3 Flotation - bacterial oxidation of concentrate - merging of concentrate oxidation slag and flotation tailings - resin 1 adsorption - sodium cyanide leaching 82.53% 80.17% 80.17% As can be seen from Table 4, the flotation recovery is the same as that of Examples 1 and 2, because the flotation process has not changed. The leaching recovery is 80.17%, which is slightly lower than that of Examples 1 and 2. This is because the oxidation treatment adopts a bacterial oxidation process, and the degree of mineral oxidation is slightly different from that of Examples 1 and 2, so the leaching recovery changes slightly, and the total recovery is still equal to the leaching recovery of 80.17%, which is much higher than the highest total recovery of 65% in the prior art.

[0069] Comparative Example 1 The comparative example adopts the "flotation-oxidation-carbon leaching" process in the prior art, that is, the Carlin-type gold ore is crushed and ground to float out the concentrate, the sulfide ore in the concentrate is oxidized and decomposed to release the encapsulated gold, and then the gold is recovered from the oxidation slag by carbon leaching. The flotation recovery rate, leaching recovery rate and total recovery rate of gold are shown in the following table:

[0070] Table 5 Serial number Existing technology process Flotation recovery Leaching recovery rate Total recovery rate Comparative Example 1 Flotation-Oxidation-Carbon Leaching 75.53% 72.17% 54.51% As can be seen from Table 5, the most commonly used "flotation-oxidation-carbon leaching" process in the prior art uses activated carbon as an adsorbent for gold cyanide complex ions, which causes the flotation organic reagent and the organic carbon shielding agent to be adsorbed into the activated carbon, reducing the adsorption capacity of the activated carbon for gold cyanide complex ions. Therefore, the prior art cannot combine the flotation concentrate and the flotation tailings, because there are a large number of flotation organic reagents in the flotation tailings, which will cause the adsorption capacity of the activated carbon for gold cyanide complex ions to decrease, resulting in: First, due to the adsorption of a large amount of organic flotation agents and organic carbon shielding agents, the adsorption capacity of activated carbon for gold cyanide complex ions decreased, and the leaching recovery rate dropped to 72.17%; Second, the flotation recovery rate of the traditional flotation process is only about 75.53%; Third, the flotation tailings cannot be utilized, so the total gold recovery rate is actually the flotation recovery rate multiplied by the leaching recovery rate. The total gold recovery rate is greatly reduced to only about 54.51%.

[0071] According to the three embodiments and one comparative example of the present invention, the Carlin-type gold ore of the present invention Compared with the existing technology, the gold extraction process can greatly improve the total recovery rate of gold.

[0072] The above description is only a preferred embodiment of the present invention. Those skilled in the art should understand that the scope of disclosure involved in the present invention is not limited to the technical solution formed by a specific combination of the above technical features, but also should cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above disclosed concept. For example, the above features are replaced with the technical features with similar functions disclosed in the present invention (but not limited to) to form a technical solution.

Claims

1. A process for extracting gold from Carlin-type gold ore, characterized in that: include: Flotation step: crush and grind the Carlin-type gold ore and then perform flotation operation to obtain flotation concentrate and flotation tailings; Oxidation step: after acidifying the pulp of the flotation concentrate, the pulp after acidification is oxidized; The step of mixing the concentrate and tailings: mixing the pulp of the flotation tailings with the pulp of the flotation concentrate after oxidation treatment, and adding an organic carbon shielding agent to the pulp mixture; Leaching step: adding anion exchange resin and sodium cyanide to the ore pulp mixture to which the organic carbon shielding agent is added to obtain leached gold; Among them, the anion exchange resin meets the following index requirements: The exchange capacity is greater than 2.8 mmol / g; Wet apparent density is 0.6-0.75 g / ml; The content of resin with particle size less than 0.85 mm is less than 0.5% of the total weight; The average particle size is 0.9-1.3 mm; The resin particle size range is 0.7-1.6 mm; True specific gravity is 1.04-1.08 g / ml; Having a divinylbenzene copolymer backbone; And, having at least one of a tertiary ammonium functional group and a quaternary ammonium functional group.

2. A process for extracting gold from Carlin-type gold ore according to claim 1, characterized in that: The flotation step further comprises: Crushing: The Carlin-type gold ore is crushed and ground into particles, of which particles with a size of less than 75 microns account for 60-90% by weight; Roughing operation: copper sulfate is added to the pulverized Carlin-type gold ore at a dosage of 400-800 g / t of feed ore, high-grade xanthate is added at a dosage of 600-1500 g / t of feed ore, MBT is added at a dosage of 300-500 g / t of feed ore, and frother is added at a dosage of 60-200 g / t of feed ore to obtain roughing concentrate and roughing tailings; First scavenging operation: Add high-grade xanthate at a dosage of 200-600 g / t of feed ore, MBT at a dosage of 50-200 g / t of feed ore, and frother at a dosage of 10-30 g / t of feed ore to the pulp of the rougher tailings, and perform the first scavenging on the rougher tailings to obtain the concentrate and tailings after the first scavenging; Concentration of concentrate after the first scavenging: Add high-grade xanthate at a dosage of 50-300 g / t of feed ore, MBT at a dosage of 20-100 g / t of feed ore, and frother at a dosage of 10-30 g / t of feed ore to the concentrate slurry after the first scavenging to obtain concentrated ore and concentrated tailings; Second scavenging operation: combining the tailings after the first scavenging with the selected tailings, adding high-grade xanthate at a dosage of 100-300 g / ton of feed ore, adding MBT at a dosage of 20-100 g / ton of feed ore, and adding a frother at a dosage of 10-30 g / ton of feed ore to the combined mineral slurry, to obtain the concentrate and tailings after the second scavenging; Combining the concentrate after the second scavenging and the rougher tailings, and using the combined minerals as feed for the first scavenging operation of the next round of flotation; The rougher concentrate and the concentrated concentrate are combined into the flotation concentrate of this round of flotation, and the tailings after the second scavenging are used as the flotation tailings of this round of flotation.

3. A process for extracting gold from Carlin-type gold ore according to claim 2, characterized in that: The oxidation step further comprises: Adding sulfuric acid to the pulp of the flotation concentrate until the pulp is acidified to a pH value of 0.5-1.5 and maintaining the pH value for 2-4 hours; The acidified slurry is added to the high-pressure oxidation kettle, heated to 190-225°C, and the pressure is maintained at 2900-3500kPa, and oxygen is introduced for high-pressure oxidation reaction; The slurry after high-pressure oxidation is removed from the high-pressure oxidation autoclave, the slurry temperature is maintained at 70-95° C., stirred for 6-8 hours, and then cooled to ambient temperature.

4. A process for extracting gold from Carlin-type gold ore according to claim 3, characterized in that: The step of mixing concentrate and tailings further comprises: Adding flotation tailings slurry to the flotation concentrate slurry after oxidation treatment, wherein the solid weight in the flotation tailings slurry accounts for 45-65% of the slurry weight, and the solid weight in the flotation concentrate slurry accounts for 35-45% of the slurry weight; An organic carbon shielding agent is added to the mixed slurry of flotation concentrate and flotation tailings, and the organic carbon shielding agent and the slurry are mixed evenly.

5. A process for extracting gold from Carlin-type gold ore according to claim 4, characterized in that: The leaching step further comprises: Add lime to the mixed slurry with organic carbon shielding agent to adjust the pH value to above 10.2; Add anion exchange resin to the alkalized mixed slurry at a dosage of 20-60 g / L and stir evenly; Sodium cyanide is added as a leaching agent in a dosage of 0.2-2.5 kg / L to the mixed slurry to which anion exchange resin is added, and the leaching time is 18-72 hours.

6. A process for extracting gold from Carlin-type gold ore according to claim 3, characterized in that: The heating temperature in the high-pressure oxidation autoclave was maintained at 215° C., and the pressure was maintained at 3300 kPa.

7. A process for extracting gold from Carlin-type gold ore according to claim 2, characterized in that: The oxidation step further comprises: Adding sulfuric acid to the pulp of the flotation concentrate until the pulp is acidified to a pH value of 1.0-2.0; Pyrite oxidizing bacteria are added to the acidified slurry, the oxidation temperature is maintained at 30-55°C, and the oxidation time is 7-18 days.

8. A process for extracting gold from Carlin-type gold ore according to any one of claims 1 to 7, characterized in that: The step of adding an organic carbon shielding agent to the slurry mixture comprises: Adding oily hydrocarbons or colloidal hydrocarbons as organic carbon shielding agents to the ore pulp mixture at a dosage of 500-3000 g / t of ore; Alternatively, MBT is added to the slurry mixture at a dosage of 100-500 g / t of ore as an organic carbon shielding agent.

9. A process for extracting gold from Carlin-type gold ore according to claim 8, characterized in that: Diesel fuel was added to the slurry mixture at a dosage of 1500 g / t of ore as an organic carbon shielding agent; Alternatively, MBT was added as an organic carbon shielding agent in the slurry mixture at a dosage of 200 g / t of feed ore.

10. A process for extracting gold from Carlin-type gold ore according to claim 2, characterized in that: The advanced xanthate includes one or more of butyl xanthate, amyl xanthate and isobutyl xanthate.

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