A process for extracting gold from Carlin-type gold ore

Abstract

The present invention discloses a process for extracting gold from Carlin-type gold ore, which relates to the technical field of precious metal metallurgy. The process includes: a flotation step: crushing and grinding the Carlin-type gold ore and then performing a flotation operation to obtain a flotation concentrate and a flotation tailing; an oxidation step: acidifying the pulp of the flotation concentrate and then oxidizing the acidified pulp; a step of mixing the concentrate and the tailing: mixing the pulp of the flotation tailing and the pulp of the flotation concentrate after oxidation treatment, and adding an organic carbon shielding agent to the pulp mixture; a leaching step: adding an anion exchange resin and sodium cyanide to the pulp mixture added with the organic carbon shielding agent to obtain leached gold. The present invention can greatly improve the total gold recovery rate of Carlin-type gold ore.

Description

Technical Field

[0001] The present invention relates to the technology of precious metal metallurgy, and particularly to a process for extracting gold from Carlin-type gold ore. Background Art

[0002] Carlin-type gold ore is a kind of double refractory metallurgical ore. One reason is that most of the gold exists in pyrite and arsenopyrite in the form of invisible gold, and it is necessary to destroy the crystal structure of these sulfides to release the gold for further extraction. At the same time, the organic carbon content in Carlin-type gold ore is very high, and these organic carbons have high chemical activity and strong adsorption ability for the dissolved gold complex ions during the leaching process, which leads to the inability to recover or loss of gold.

[0003] The prior art often extracts gold from Carlin-type gold ore through the following processes, but the gold recovery rate is generally not high:

[0004] 1. Direct cyanidation leaching - activated carbon adsorption process. The gold recovery rate of this process is usually below 30%.

[0005] 2. Roasting - carbon leaching process. This process usually includes direct fuel roasting of ore and roasting of concentrate produced by first crushing, grinding and then flotation of ore. However, due to the large amount of arsenic and mercury in the ore, the roasting dust contains arsenic and mercury, which is harmful to the health of production personnel and the environment.

[0006] 3. Flotation - oxidation - carbon leaching process. After the ore is crushed and ground, flotation technology is used to enrich gold and remove the components unfavorable to downstream operations. The sulfide ore in the flotation concentrate is decomposed to release the encapsulated gold, and then the carbon leaching method is used to recover gold from the oxidized slag. However, the organic carbon in the ore during the carbon leaching process 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 the carbon leaching gold extraction process, resulting in a low leaching recovery rate.

[0007] 4. Sodium thiosulfate leaching process. Sodium thiosulfate is used to replace sodium cyanide as the leaching agent for gold. However, this process has a large consumption of sodium thiosulfate, high production cost, and also has the disadvantage of low recovery rate.

[0008] Therefore, the present invention expects 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

[0009] 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 oxidation of flotation concentrate, shielding of organic carbon from robbing gold, merging of flotation oxidized slag and flotation tailings, and anion exchange resin adsorption. The present invention can greatly improve the total gold recovery rate of Carlin-type gold ore.

[0010] One aspect of the present invention provides a process for extracting gold from Carlin-type gold ore, comprising:

[0011] Flotation step: The Carlin-type gold ore is crushed and ground and then subjected to a flotation operation to obtain a flotation concentrate and a flotation tailing;

[0012] Oxidation step: After acidifying the pulp of the flotation concentrate, the acidified pulp is then subjected to an oxidation treatment;

[0013] Concentrate and tailing mixing step: Mix the pulp of the flotation tailing and the pulp of the flotation concentrate after oxidation treatment, and add an organic carbon shielding agent to the pulp mixture;

[0014] Leaching step: Anion exchange resin and sodium cyanide are added to the pulp mixture with the organic carbon shielding agent added to obtain leached gold;

[0015] Wherein, the anion exchange resin meets the following index requirements:

[0016] The exchange capacity is greater than 2.8 mmol / g;

[0017] The wet apparent density is 0.6 - 0.75 g / mL;

[0018] The resin content with a particle size less than 0.85 mm is less than 0.5% of the total weight;

[0019] The average particle size is 0.9 - 1.3 mm;

[0020] The resin particle size range is 0.7 - 1.6 mm;

[0021] The true specific gravity is 1.04 - 1.08 g / mL;

[0022] It has a divinylbenzene copolymer backbone;

[0023] And, it has at least one of a tertiary amine functional group and a quaternary amine functional group.

[0024] Furthermore, the flotation step further includes:

[0025] Crushing operation: The Carlin-type gold ore is crushed and ground into particles, wherein the weight ratio of particles with a particle size below 75 microns is 60 - 90%;

[0026] Rougher flotation operation: In the pulp of the crushed Carlin-type gold ore, copper sulfate is added at a dosage of 400 - 800 g / ton of feed, higher xanthate is added at a dosage of 600 - 1500 g / ton of feed, MBT is added at a dosage of 300 - 500 g / ton of feed, and a foaming agent is added at a dosage of 60 - 200 g / ton of feed to obtain a rougher flotation concentrate and a rougher flotation tailing;

[0027] First scavenging operation: Add high-grade xanthate at a dosage of 200 - 600 g / ton of feed, MBT at a dosage of 50 - 200 g / ton of feed, and a foaming agent at a dosage of 10 - 30 g / ton of feed to the pulp of the rougher tailings, and conduct the first scavenging on the rougher tailings to obtain the concentrate and tailings after the first scavenging;

[0028] Concentration operation for the concentrate after the first scavenging: Add high-grade xanthate at a dosage of 50 - 300 g / ton of feed, MBT at a dosage of 20 - 100 g / ton of feed, and a foaming agent at a dosage of 10 - 30 g / ton of feed to the pulp of the concentrate after the first scavenging to obtain the concentrated concentrate and concentrated tailings;

[0029] Second scavenging operation: Combine the tailings after the first scavenging and the concentrated tailings, and add high-grade xanthate at a dosage of 100 - 300 g / ton of feed, MBT at a dosage of 20 - 100 g / ton of feed, and a foaming agent at a dosage of 10 - 30 g / ton of feed to the pulp of the combined minerals to obtain the concentrate and tailings after the second scavenging;

[0030] Combine the concentrate after the second scavenging and the rougher tailings, and use the combined minerals as the feed for the first scavenging operation of the next round of flotation;

[0031] Combine the rougher concentrate and the concentrated concentrate as the flotation concentrate of this round of flotation, and use the tailings after the second scavenging as the flotation tailings of this round of flotation.

[0032] Furthermore, the oxidation step further includes:

[0033] Add sulfuric acid to the pulp of the flotation concentrate until the pulp is acidified to a pH value of 0.5 - 1.5 and maintained for 2 - 4 hours;

[0034] Add the acidified pulp to a high-pressure oxidation autoclave, heat it to 190 - 225 °C, maintain the pressure at 2900 - 3500 kPa, and introduce oxygen for high-pressure oxidation reaction;

[0035] Remove the pulp after high-pressure oxidation from the high-pressure oxidation autoclave, maintain the pulp temperature at 70 - 95 °C, stir for 6 - 8 hours, and then cool it to the ambient temperature.

[0036] Furthermore, the step of mixing the concentrate and tailings further includes:

[0037] Add the flotation tailings pulp to the flotation concentrate pulp after oxidation treatment, where the solid weight in the flotation tailings pulp accounts for 45 - 65% of the pulp weight, and the solid weight in the flotation concentrate pulp accounts for 35 - 45% of the pulp weight;

[0038] An organic carbon shielding agent is added to the mixed pulp of flotation concentrate and flotation tailings, and the organic carbon shielding agent is evenly mixed with the pulp.

[0039] Further, the leaching step further includes:

[0040] Lime is added to the mixed pulp with the organic carbon shielding agent added, and the pH value is adjusted to above 10.2;

[0041] Anion exchange resin is added to the alkalized mixed pulp at a dosage of 20 - 60 g / L and stirred evenly;

[0042] Sodium cyanide is added as a leaching agent to the mixed pulp with the anion exchange resin added at a dosage of 0.2 - 2.5 kg / L, and the leaching time is 18 - 72 hours.

[0043] Further, the heating temperature in the high-pressure oxidation autoclave is maintained at 215 °C and the pressure is maintained at 3300 kPa.

[0044] Further, the oxidation step further includes:

[0045] Sulfuric acid is added to the pulp of the flotation concentrate until the pulp is acidified to a pH value of 1.0 - 2.0;

[0046] Pyrite-oxidizing bacterial strains are added to the acidified pulp, the oxidation temperature is maintained at 30 - 55 °C, and the oxidation time is 7 - 18 days.

[0047] Further, the step of adding the organic carbon shielding agent to the pulp mixture includes:

[0048] Oily hydrocarbons or colloidal hydrocarbons are added to the pulp mixture as an organic carbon shielding agent at a dosage of 500 - 3000 g / ton of feed;

[0049] Alternatively, MBT is added to the pulp mixture as an organic carbon shielding agent at a dosage of 100 - 500 g / ton of feed.

[0050] Further, the higher xanthate includes one or more of butyl xanthate, amyl xanthate, and isobutyl xanthate.

[0051] Further, it also includes:

[0052] Diesel oil is added to the pulp mixture as an organic carbon shielding agent at a dosage of 1500 g / ton of feed;

[0053] Alternatively, MBT is added to the pulp mixture as an organic carbon shielding agent at a dosage of 200 g / ton of feed.

[0054] The gold extraction process from Carlin-type gold ore provided by the present invention has the following beneficial effects:

[0055] (1) The present invention uses an anion exchange resin with optimized parameters to replace activated carbon as the adsorbent for gold cyanide complex ions, greatly reducing the adsorption rate of the adsorbent to organic carbon shielding agents and flotation organic reagents, ensuring that the adsorption capacity of the adsorbent for gold cyanide complex ions is not affected, and thus improving the leaching recovery rate of gold;

[0056] (2) The remaining flotation organic reagents 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 the flotation tailings containing a large amount of flotation organic reagents unable to be leached for gold together with the oxidized slag of the flotation concentrate. This results in the unutilized flotation tailings, that is, the mineral utilization rate is not 100%, and the total recovery rate of gold cannot be further improved. The present invention uses an anion exchange resin with optimized parameters to replace activated carbon as the adsorbent for gold cyanide complex ions. Since the anion exchange resin with optimized parameters does not adsorb flotation organic reagents and organic carbon shielding agents, the adsorption capacity of the adsorbent for gold cyanide complex ions will not decrease. Therefore, the present invention can combine the flotation tailings containing flotation organic reagents 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 wash the carbonate in the flotation tailings, so that the flotation tailings are fully utilized, thereby greatly improving the total recovery rate of gold;

[0057] (3) The present invention improves the flotation process of Carlin-type gold ore. Under the condition of the same weight of the feed ore, the new flotation process can obtain more flotation concentrate than the traditional flotation process, that is, the flotation recovery rate is improved, and the increase in the proportion of the flotation concentrate further drives the increase in the leaching recovery rate.

[0058] (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

[0059] Other features, objects, and advantages of the present application will become more apparent by reading the detailed description of the non-limiting embodiments with reference to the following drawings:

[0060] Figure 1 is the process flow diagram of the gold extraction process from Carlin-type gold ore provided by the present invention;

[0061] Figure 2 is the process flow of the flotation process provided by the present invention Figure 1 ;

[0062] Figure 3 is the process flow of the flotation process provided by the present invention Figure 2 . DETAILED DESCRIPTION OF THE INVENTION

[0063] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0064] 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 the plural forms unless the context clearly indicates otherwise.

[0065] It should be understood that although the terms first, second, third, etc. may be used in the embodiments of the present invention to describe the acquisition modules, these acquisition modules should not be limited to these terms. These terms are only used to distinguish the acquisition modules from each other.

[0066] Depending on the context, the word "if" as used herein can be interpreted as "when" or "while" or "in response to determining" or "in response to detecting". Similarly, depending on the context, the phrase "if determined" or "if detecting (stated condition or event)" can be interpreted as "when determined" or "in response to determining" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)".

[0067] It should be noted that the orientation terms such as "upper", "lower", "left" and "right" described in the embodiments of the present invention are described from the angles shown in the accompanying drawings and should not be construed 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 directly formed "on" or "under" another element, but also be indirectly formed "on" or "under" another element through an intermediate element.

[0068] Carlin-type gold ore is a double refractory metallurgical ore. Table 1 shows the analysis results of the chemical components in the Carlin-type gold ore in a certain area. Most of the gold exists in the form of invisible gold in pyrite and arsenopyrite, and it is necessary to break the crystal structure of these sulfides to release the gold for further extraction. In addition, the Carlin-type gold ore contains a high content of organic carbon, and these organic carbons have high chemical activity and have a strong adsorption capacity for the dissolved gold cyanide complex ions during the leaching process, which in turn leads to the inability to recover gold or a large loss of gold.

[0069] Table 1

[0070] 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

[0071] In the prior art, processes such as direct cyanidation leaching - activated carbon adsorption process, roasting - carbon in pulp process, flotation - oxidation - carbon in pulp process, and sodium thiosulfate leaching process are adopted for the above - mentioned technical problems. However, in addition to defects such as high production cost and serious pollution, the gold recovery rate of these gold extraction processes is controlled at about 50% - 65%.

[0072] In one embodiment of the present invention, aiming at the problem of low gold recovery rate of Carlin - type gold ore 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 optimized parameters as the adsorbent for gold - cyanide complex ions, and jointly treating the flotation tailings containing flotation organic reagents and the acidic oxidation slag of flotation concentrate, the total gold recovery rate is further improved.

[0073] See Figure 1 , the process for extracting gold from Carlin - type gold ore in this embodiment includes a flotation step S101, an oxidation step S102, a concentrate - tailing mixing step S103, and a leaching step S104. The specific process flow is as follows:

[0074] Flotation step S101: The Carlin - type gold ore is crushed and ground, and then a flotation operation is carried out to obtain flotation concentrate and flotation tailings.

[0075] See Figure 2 and Figure 3 , this embodiment improves the traditional flotation process. On the one hand, it improves the flotation recovery rate of gold, and the increase in the proportion of flotation concentrate further drives the improvement of the leaching recovery rate.

[0076] The flotation process of this embodiment specifically includes:

[0077] Crushing step S1011: The Carlin - type gold ore is crushed and ground into granular ore powder, and the weight proportion of particles with a particle size below 75 microns is 60% - 90%, preferably more than 80%. Through experiments, the present invention finds that the grinding fineness has a direct impact on the final flotation recovery rate and leaching recovery rate of gold ore. When the weight proportion of particles with a particle size below 75 microns is more than 80%, the flotation recovery rate and leaching recovery rate will increase significantly.

[0078] Rougher flotation step S1012: In the pulp of the crushed Carlin - type gold ore, copper sulfate is added at a dosage of 400 - 800 g / t of ore feed, higher - grade xanthate is added at a dosage of 600 - 1500 g / t of ore feed, MBT is added at a dosage of 300 - 500 g / t of ore feed, and a foaming agent is added at a dosage of 60 - 200 g / t of ore feed to obtain rougher flotation concentrate and rougher flotation tailings.

[0079] Specifically, the crushed ore powder is put into a flotation machine for flotation. In the formed pulp, copper sulfate is added at a dosage of 400 - 800 g / ton of feed (preferably 600 g / ton of feed), isobutyl xanthate is added at a dosage of 600 - 1500 g / ton of feed (preferably 1200 g / ton of feed), MBT is added at a dosage of 300 - 500 g / ton of feed (preferably 400 g / ton of feed), and No. 2 oil (R-alkyl) is added as a foaming agent at a dosage of 60 - 200 g / ton (preferably 100 g / ton of feed) of feed to obtain rougher concentrate and rougher tailings.

[0080] It should be noted that the rougher operation is to recover most of the gold-bearing minerals. In the rougher operation, copper sulfate replaces the iron ions on the surface of pyrite bearing gold with copper ions, making it easier to bond with higher xanthates. Higher xanthates are more likely to adsorb on the mineral surface, hydrophobize the minerals, and thus float the gold. The foaming agent 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 above reagent addition amounts are added in the unit of "g / ton of feed". Here, the feed refers to the untreated material entering the flotation operation. Therefore, the weight of the feed is the weight of the untreated fixed minerals in each step, rather than the weight of the pulp. The above higher xanthates refer to xanthates with a carbon chain length / carbon atom number greater than or equal to 4, such as any one or a mixture of butyl xanthate, amyl xanthate, and isobutyl xanthate.

[0081] The first scavenging step S1013: In the pulp of the rougher tailings, higher xanthate is added at a dosage of 200 - 600 g / ton of feed, MBT is added at a dosage of 50 - 200 g / ton of feed, and a foaming agent is added at a dosage of 10 - 30 g / ton of feed to conduct the first scavenging on the rougher tailings to obtain the concentrate and tailings after the first scavenging.

[0082] 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.

[0083] 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;

[0084] 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.

[0085] 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.

[0086] 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 second scavenging operation is performed on all the combined tailings. Since there are residues of the reagents used in the roughing and the first scavenging, in order to make full use of the residual reagents, the dosage of the reagents added in the second scavenging operation can be equal to or lower than that of the first scavenging. Preferably, isobutyl xanthate or other higher xanthates are added to the pulp of the combined minerals at a dosage of 100 - 300 g / t of the feed (more preferably 200 g / t of the feed), MBT is added at a dosage of 20 - 100 g / t of the feed (more preferably 50 g / t of the feed), and No. 2 oil (R-alkyl) is added as a foaming agent at a dosage of 10 - 30 g / t of the feed (more preferably 20 g / t of the feed) to obtain the concentrate and tailings after the second scavenging.

[0087] Step S1016: Combine the concentrate after the second scavenging and the roughing tailings, and use the combined minerals as the feed for the first scavenging operation of the next round of flotation.

[0088] Specifically, since the concentrate after the second scavenging is obtained based on the tailings after the first scavenging and the concentrated tailings, and the gold content of these tailings is lower than that of the original gold ore, the gold content in the concentrate after the second scavenging is generally similar to that of the roughing tailings. Therefore, in this step, the concentrate after the second scavenging and the roughing tailings are combined and used as the feed for the first scavenging operation of the next round of flotation. This can make more full use of the tailings that have not been fully extracted. 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 the total recovery rate of gold.

[0089] Step S1017: Combine the roughing concentrate and the concentrated concentrate into the flotation concentrate of this round of flotation, and use the tailings after the second scavenging as the flotation tailings of this round of flotation.

[0090] Specifically, since the gold content of the concentrated concentrate is close to that of the roughing concentrate, the roughing concentrate and the concentrated concentrate are combined as the final flotation concentrate of this round of flotation, and this flotation concentrate is used for the subsequent oxidation step. In addition, since the tailings after the second scavenging are the tailings obtained after multiple rounds of scavenging operations, and the gold content in this tailings is relatively low, it is very difficult to float the gold-containing substances again through the scavenging process. Therefore, the tailings after the second scavenging are used as the final flotation tailings of this round of flotation.

[0091] The improved flotation process in this embodiment can greatly increase the proportion of the flotation concentrate, improve the flotation recovery rate, achieve full flotation and effective utilization of the original minerals, and lay a foundation for improving the subsequent leaching recovery rate and the total recovery rate.

[0092] Oxidation step S102: After acidifying the pulp of the flotation concentrate, the acidified pulp is then subjected to an oxidation treatment.

[0093] Specifically, in order to oxidize the sulfide minerals in the flotation concentrate, the flotation concentrate needs to be oxidized. However, 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, thus affecting the oxidation treatment. To solve this technical problem, the present invention performs an acidification treatment before the oxidation treatment, and then performs high-pressure oxidation or bacterial oxidation, including:

[0094] Step S1021: Add sulfuric acid to the pulp of the flotation concentrate and stir evenly until the pulp is acidified to a pH value of 0.5 - 1.5, preferably a pH value of 1, and maintain it for 2 - 4 hours. At this time, the carbonate minerals will be dissolved, so that a large amount of carbon dioxide will not be formed during the subsequent oxidation process;

[0095] Step S1022: Add the acidified pulp to a high-pressure oxidation autoclave, heat it to 190 - 225 °C, preferably 215 °C, and maintain the pressure at 2900 - 3500 kPa, preferably a pressure value of 3300 kPa, and introduce oxygen to carry out a high-pressure oxidation reaction for about 1 hour;

[0096] Step S1023: Remove the pulp after high-pressure oxidation from the high-pressure oxidation autoclave, maintain the pulp temperature at 70 - 95 °C, preferably 80 °C, stir for 6 - 8 hours, and then cool it to the ambient temperature.

[0097] Optionally, replace high-pressure oxidation with bacterial oxidation. Use a commercial pyrite-oxidizing bacterial strain, add sulfuric acid to the flotation concentrate pulp to an environmental pH value of 1.0 - 2.0 to obtain the best bacterial oxidation environment, set the oxidation temperature at 30 - 55 °C, and the oxidation time at 7 - 18 days.

[0098] Step S103 of mixing concentrate and tailings: Mix the pulp of the flotation tailings and the pulp of the flotation concentrate after oxidation treatment, and add an organic carbon shielding agent to the pulp mixture.

[0099] Specifically, in theory, to improve the total recovery rate of gold, it is necessary to make full use of flotation tailings. However, in reality, it is impossible to leach the flotation tailings and the oxidized slag of flotation concentrate together because there are a large amount of flotation organic reagents in the flotation tailings. These flotation organic reagents will be adsorbed in large amounts by the activated carbon adsorbent, thereby reducing the adsorption capacity of the activated carbon adsorbent for gold cyanide complex ions and resulting in a decrease in the leaching rate of gold. In the subsequent leaching step S104 of the present invention, an anion exchange resin with optimized parameters is used instead of activated carbon as the adsorbent. The anion exchange resin with optimized parameters will not adsorb the flotation organic reagents, so it will not affect the adsorption of gold cyanide complex ions by the anion exchange resin with optimized parameters. In this way, the present invention can combine the flotation tailings containing flotation organic reagents with the acidic oxidized slag of flotation concentrate for treatment, and use the remaining acidic substances in the acidic oxidized slag of flotation concentrate to wash the carbonates in the flotation tailings. Since the gold in the flotation tailings does not exist in sulfides in large amounts but in quartz in large amounts, the flotation tailings in the present invention do not need to be oxidized, and preferably are leached together with the oxidized slag of flotation concentrate. In this way, the flotation tailings are also fully utilized, further improving the total recovery rate of gold.

[0100] The mixing process of flotation concentrate and flotation tailings includes:

[0101] Step S1031, cooling the oxidized flotation concentrate pulp to ambient temperature;

[0102] Step S1032, adding flotation tailings pulp to the oxidized flotation concentrate pulp, wherein the solid weight in the flotation tailings pulp accounts for 45 - 65% of the pulp weight, and the solid weight in the oxidized flotation concentrate pulp accounts for 35 - 45% of the pulp weight. It should be noted that the pulp concentration should not only ensure that it is not too viscous for convenient pumping, but also ensure that the water volume is appropriate when the mixed pulp enters the subsequent leaching step S104. The pulp concentration will also directly affect the component diffusion rate, and thus affect the leaching rate and leaching speed of gold. If the pulp concentration is too high, the leaching rate and leaching speed of gold are relatively low. Although a lower pulp concentration increases the leaching rate and leaching speed, the equipment volume needs to be made very large, and a large amount of cyanide reagent also needs to be input, resulting in a significant increase in equipment investment cost and reagent cost. Through experiments, the present invention has learned that the solid-liquid ratio of the above pulp can fully meet various requirements.

[0103] Further, in order to avoid the gold-robbing effect of organic carbon in the pulp mixture, an organic carbon shielding agent is added to the pulp mixture and stirred evenly to shield the gold-robbing effect of organic carbon. Among them, the step of adding the organic carbon shielding agent specifically includes: adding an oily hydrocarbon or a colloidal hydrocarbon to the pulp mixture at a dosage of 500-3000 g / t of ore feed as the organic carbon shielding agent; or adding MBT to the pulp mixture at a dosage of 100-500 g / t of ore feed as the organic carbon shielding agent. More preferably, diesel is added to the pulp mixture at a dosage of 1500 g / t of ore feed as the organic carbon shielding agent; or MBT is added to the pulp mixture at a dosage of 200 g / t of ore feed as the organic carbon shielding agent.

[0104] Leaching step S104: Add an anion exchange resin and a sodium cyanide leaching agent to the pulp mixture with the organic carbon shielding agent added to obtain leached gold.

[0105] Specifically, the activated carbon adsorbent in the prior art not only adsorbs the gold cyanide complex ions in the pulp mixture, but also adsorbs the organic carbon shielding agent and the residual flotation organic agents, which will reduce the adsorption capacity of the activated carbon adsorbent for the gold cyanide complex ions, and thus reduce the total gold recovery rate. To solve this technical problem, the present invention uses an anion exchange resin with optimized parameters to replace the activated carbon as the adsorbent. The anion exchange resin with optimized parameters will not adsorb the flotation agents and shielding agents in the mixture, so it will not affect the adsorption capacity of the adsorbent for the gold cyanide complex ions, and thus improve the total gold recovery rate.

[0106] The anion exchange resin with optimized parameters in this embodiment needs to meet the following index requirements at the same time:

[0107] (1) The exchange capacity is greater than 2.8 mmol / g;

[0108] (2) The wet apparent density is 0.6-0.75 g / mL;

[0109] (3) The resin content with a particle size less than 0.85 mm is less than 0.5% of the total weight;

[0110] (4) The average particle size is 0.9-1.3 mm;

[0111] (5) The resin particle size range is 0.7-1.6 mm;

[0112] (6) The true specific gravity is 1.04-1.08 g / mL;

[0113] (7) It has a divinylbenzene copolymer backbone;

[0114] (8) It has at least one of a tertiary amine functional group and a quaternary amine functional group.

[0115] 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.

[0116] 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.

[0117] More specifically, the implementation process of the leaching step S104 includes:

[0118] Step S1041, adding lime to the mixed slurry with the organic carbon shielding agent, and adjusting the pH

[0119] 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;

[0120] 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;

[0121] 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.

[0122] The present invention continues to provide the following examples to illustrate the gold extraction process of the present invention.

[0123] Example 1

[0124] 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;

[0125] 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;

[0126] Step 3: Add isobutyl xanthate at a dosage of 400 g / ton of feed, MBT at a dosage of 100 g / ton of feed, and No. 2 oil at a dosage of 20 g / ton of feed as a foaming agent to the pulp of the rougher tailings, and conduct the first scavenging on the rougher tailings to obtain the concentrate and tailings after the first scavenging;

[0127] Step 4: Add isobutyl xanthate at a dosage of 200 g / ton of feed, MBT at a dosage of 50 g / ton of feed, and a foaming agent at a dosage of 20 g / ton of feed to the concentrate pulp after the first scavenging to obtain the cleaned concentrate and the cleaned tailings;

[0128] Step 5: Combine the tailings after the first scavenging and the cleaned tailings, and 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 foaming agent to the pulp of the combined minerals to obtain the concentrate and tailings after the second scavenging;

[0129] Step 6: Combine the rougher concentrate and the cleaned concentrate into the flotation concentrate of this round of flotation, and use the tailings after the second scavenging as the flotation tailings of this round of flotation;

[0130] Step 7: Combine the concentrate after the second scavenging and the rougher tailings, and use the combined minerals as the feed for the first scavenging operation of the next round of flotation;

[0131] 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 it to 215°C, and maintain the pressure at 300 kPa, and introduce oxygen to conduct a high-pressure oxidation reaction for about 1 hour; remove the pulp after high-pressure oxidation from the high-pressure oxidation autoclave, maintain the pulp temperature at 80°C, stir for 8 hours, and then cool it to the ambient temperature. Among them, the solid weight in the pulp of the flotation concentrate after oxidation accounts for 40% of the pulp weight.

[0132] Step 9: Add flotation tailing pulp to the cooled pulp. The solid weight in the flotation tailing pulp accounts for 50% of the pulp weight, and the solid weight in the flotation concentrate pulp accounts for 40% of the pulp weight. Add diesel oil as an organic carbon shielding agent to the pulp mixture at a dosage of 1500 g / t of ore feed. Add lime to the mixed pulp with the organic carbon shielding agent added to adjust the pH value to 10.5. Add anionic exchange resin to the alkalized mixed pulp at a dosage of 40 g / L and stir evenly. The anionic exchange resin meets the requirements of an exchange capacity of 4 mmol / g, a wet apparent density of 0.7 g / mL, the resin content with a particle size of 0.6 mm accounting for 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 backbone, and having a tertiary ammonium functional group. Add sodium cyanide as a leaching agent to the mixed pulp with the anionic exchange resin added at a dosage of 1.5 kg / L, and the leaching time is 24 hours.

[0133] 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.

[0134] Table 2

[0135] Serial number The process of the present invention Flotation recovery rate Leaching recovery rate Total recovery rate Example 1 Flotation - High - pressure oxidation of concentrate - Merging of oxidized slag of concentrate and flotation tailings - Adsorption by Resin 1 - Leaching with sodium cyanide 82.53% 80.87% 80.87%

[0136] As can be seen from Table 2, since the present invention uses an anionic exchange resin with optimized parameters to replace activated carbon to adsorb gold cyanide complex ions, the flotation organic agents basically will not be adsorbed on the anionic exchange resin of the present invention, and the adsorption capacity of the resin for gold cyanide complex ions will not decrease. Therefore, the present invention can achieve the combination of the oxidized slag of the flotation concentrate and the flotation tailings, which is equivalent to 100% utilization of the minerals. Therefore, 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 anionic exchange resin with optimized parameters in this Example 1 for gold cyanide complex ions will never decrease, the leaching recovery rate is as high as 80.87%. Through the process of "flotation - high-pressure oxidation of concentrate - combination of oxidized slag of concentrate and flotation tailings - resin adsorption - sodium cyanide leaching" in this example, 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.

[0137] Example 2

[0138] Example 2 adopts the same process of "flotation - high-pressure oxidation of concentrate - combination of oxidized slag of concentrate and flotation tailings - resin adsorption - sodium cyanide leaching" proposed by the present invention as in Example 1. The difference is:

[0139] (1) The anion exchange resin meets the requirements: the exchange capacity is 3 mmol / g, the wet apparent density is 0.6 g / mL, the resin content with a particle size of 0.8 mm accounts for 0.4% of the total weight, the average particle size is 1.3 mm, the resin particle size is 1.6 mm, the true specific gravity is 1.08 g / mL, it has a divinylbenzene copolymer backbone, and has a quaternary ammonium functional group;

[0140] (2) Add the anion exchange resin to the alkalized mixed pulp at a dosage of 30 g / L.

[0141] The flotation recovery rate, leaching recovery rate and total recovery rate of gold in the process described in Example 2 are shown in the following table:

[0142] Table 3

[0143] Serial number The process of the present invention Flotation recovery rate Leaching recovery rate Total recovery rate Example 2 Flotation - High - pressure oxidation of concentrate - Merging of oxidized slag of concentrate and flotation tailings - Adsorption by Resin 2 - Leaching with sodium cyanide 82.53% 80.33% 80.33%

[0144] It can be seen from Table 3 that the flotation recovery rate is the same as that in Example 1 because the flotation process has not changed. The leaching recovery rate decreases slightly compared with the preferred method in Example 1 due to the use of different anion exchange resins, but it can reach 80.33%, which is still much higher than the highest total recovery rate of 65% in the prior art.

[0145] Example 3

[0146] Example 3 adopts a concentrate bacterial oxidation process different from that in Example 1 and Example 2. The overall process is changed to "flotation - concentrate bacterial oxidation - combination of concentrate oxidized slag and flotation tailings - resin adsorption - sodium cyanide leaching". The parameter selection and dosage of the anion exchange resin are the same as those in Example 1. The flotation recovery rate, leaching recovery rate and total recovery rate of gold in Example 3 are shown in the following table:

[0147] Table 4

[0148] Serial number The process of the present invention Flotation recovery rate Leaching recovery rate Total recovery rate Example 3 Flotation - Bacterial oxidation of concentrate - Merging of oxidized slag of concentrate and flotation tailings - Adsorption by Resin 1 - Leaching with sodium cyanide 82.53% 80.17% 80.17%

[0149] It can be seen from Table 4 that the flotation recovery rate is the same as that in Example 1 and Example 2 because the flotation process has not changed. The leaching recovery rate is 80.17%, slightly lower than the levels in Example 1 and Example 2. This is because the bacterial oxidation process is used for oxidation treatment, and the degree of mineral oxidation is slightly different from that in Example 1 and Example 2, so the leaching recovery rate changes slightly. The total recovery rate is still equal to the leaching recovery rate of 80.17%, which is much higher than the highest total recovery rate of 65% in the prior art.

[0150] Comparative Example 1

[0151] The comparative example adopts the "flotation-oxidation-carbon-in-leach" process in the prior art, that is: after the Carlin-type gold ore is crushed and ground, the concentrate is floated, the sulfide ore in the concentrate is oxidized and decomposed to release the encapsulated gold, and then the carbon-in-leach method is used to recover gold from the oxidized slag. The flotation recovery rate, leaching recovery rate and total recovery rate of gold are shown in the following table:

[0152] Table 5

[0153] Serial number Process of the prior art Flotation recovery rate Leaching recovery rate Total recovery rate Comparative Example 1 Flotation - Oxidation - Carbon in pulp 75.53% 72.17% 54.51%

[0154] As can be seen from Table 5, in the most commonly used "flotation-oxidation-carbon-in-leach" process in the prior art, since activated carbon is used as the adsorbent for gold cyanide complex ions, the flotation organic reagents and organic carbon shielding agents will also be adsorbed into the activated carbon, reducing the adsorption capacity of the activated carbon for gold cyanide complex ions. Therefore, in the prior art, the flotation concentrate and flotation tailings cannot be combined because there are a large amount 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. The consequences are as follows:

[0155] First, due to the adsorption of a large amount of flotation organic reagents and organic carbon shielding agents, the adsorption capacity of the activated carbon for gold cyanide complex ions decreases, and the leaching recovery rate drops to 72.17%;

[0156] Second, the flotation recovery rate of the traditional flotation process is only about 75.53%;

[0157] Third, the flotation tailings cannot be utilized. Therefore, the total recovery rate of gold is actually the product of the flotation recovery rate and the leaching recovery rate, and the total recovery rate of gold drops significantly, only about 54.51%.

[0158] According to the 3 embodiments and 1 comparative example of the present invention, it can be seen that the gold extraction process of the Carlin-type gold ore of the present invention

[0159] can greatly improve the total recovery rate of gold compared with the prior art.

[0160] The above description is only the preferred embodiment of the present invention. Those skilled in the art should understand that the disclosed scope involved in the present invention is not limited to the technical solutions formed by the specific combination of the above technical features, and should also 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 technical solutions formed by mutually replacing the above features with the technical features (but not limited to) having similar functions disclosed in the present invention.

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 the 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; wherein the organic carbon shielding agent is oily hydrocarbons, colloidal hydrocarbons or MBT; 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 and adjust the pH to 10.2 above; 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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