A method and system for recovering gold from low-grade gold-bearing carbonaceous sludge

Abstract

The present invention relates to a method and system for recovering gold from low-grade gold-bearing carbonaceous sludge. The method includes: conventional cyanidation leaching in the first stage; ultrasonic enhanced-ozone / oxygen-enriched synergistic leaching in the second stage; circulating adsorption of the leaching solution in the second stage; desorbing and electro-winning gold from the gold-loaded activated carbon. The system includes a first-stage leaching tank. The discharge port of the first-stage leaching tank is connected to the feed port of the second-stage leaching tank through a transfer pump and a pipeline. A filter screen is vertically arranged in the second-stage leaching tank, and the filter screen divides one side of the second-stage leaching tank into a filtrate tank; a stirring device and at least two ultrasonic devices are arranged in the second-stage leaching tank. The ultrasonic devices are electrically connected to an ultrasonic controller, and the ultrasonic devices are connected to an air compressor and an ozone storage tank through air pipes; the discharge port of the filtrate tank is connected to the feed port of a multi-stage series adsorption tower through a transfer pump and a pipeline, and the liquid outlet of the multi-stage series adsorption tower is communicated with the feed port of the filtrate tank. The present invention can efficiently recover gold and silver from low-grade gold-bearing carbonaceous sludge, and the gold and silver leaching rates reach 80% - 92% and 70% - 85% respectively.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrometallurgy of resources, and particularly relates to a method and a system for recovering gold from low-grade gold-bearing carbonaceous sludge. Background Art

[0002] In recent years, with the continuous development of gold ore resources, the surface oxidized ore gold resources that are easy to process have gradually decreased. The refractory oxygen-sulfur mixed ores and laterite ores in the middle and deep parts have gradually become the main ore resources. These refractory gold ore resources contain more argillaceous and are often associated with various elements such as silver, iron, copper, lead, zinc, calcium, and sulfur.

[0003] In the process of gold extraction by cyanidation-carbon slurry method, these impurity elements will react with cyanide to form related cyanide complexes, which are adsorbed by activated carbon, forming complex refractory gold-loaded carbon with high impurity elements and heavy argillaceous. During the hydraulic transportation of this complex refractory gold-loaded carbon to the desorption workshop and the process of re-cleaning the gold-loaded carbon before desorption, most of the argillaceous will settle in the return water tank of the desorption workshop. In addition, during the hydraulic transportation of these gold-loaded carbons in each process of the desorption workshop, powder carbon will also be generated due to friction; when the pressure is released at the end of desorption, the gold-free carbon is cooled with the return water, and powder carbon will also be generated due to thermal expansion and contraction; these powder carbons are deposited in the return water tank with the return water and settle with the argillaceous, finally forming low-grade gold-bearing carbonaceous sludge.

[0004] At present, there are mainly two treatment methods for this kind of low-grade gold-bearing carbonaceous sludge: one is to obtain filter residue by pressing with a small filter press, and when the filter residue reaches a certain amount, it is sold. However, the carbonaceous sludge obtained by this simple pressing contains cyanide and belongs to hazardous waste, which needs to be sold to enterprises with hazardous waste treatment qualifications, and there are problems such as poor sampling representativeness and low discount coefficient in the sales process, and the maximum benefit cannot be achieved. The other is to use a slurry pump to pump the carbonaceous sludge in the return water tank back to the cyanidation system for leaching and recovery. However, this treatment method has a low recovery rate, and most of the powder carbon is lost with the cyanidation tail liquid, and the recovery purpose cannot be achieved.

[0005] Therefore, it is necessary to find a more effective method and system for recovering low-grade gold-bearing carbonaceous sludge to improve the recovery rate of gold and silver, and at the same time reduce the pressure of safety and environmental protection. Summary of the Invention

[0006] In view of the above problems, the present invention provides a method and a system for recovering gold from low-grade gold-bearing carbonaceous sludge.

[0007] The specific technical solution is as follows: A method for recovering gold from low-grade gold-bearing carbonaceous sludge, comprising the following steps:

[0008] (1) Stage I conventional cyanidation leaching: Mix the carbonaceous sludge in the return water tank of the desorption workshop with production return water in proportion, add lime milk solution to adjust the pH value > 12, and then add sodium cyanide solution, stir for cyanidation leaching to obtain stage I leaching residue and stage I leaching solution;

[0009] (2) Secondary ultrasonic enhanced - ozone / oxygen - enriched synergistic leaching: Mix the primary leaching residue and leaching solution obtained in step (1) and transfer them into a leaching tank, add sodium cyanide solution for cyanidation leaching, start the stirring device and ultrasonic device simultaneously, open the ozone and oxygen supply equipment for aeration, and enhance leaching under the synergistic action of the ultrasonic device, ozone, and oxygen. The secondary leaching residue and secondary leaching solution are obtained by leaching. The secondary leaching solution enters the filtrate tank through the filter screen in the leaching tank;

[0010] (3) Recycling adsorption of the secondary leaching solution: After 1 hour of secondary ultrasonic enhanced leaching - ozone / oxygen - enriched synergistic leaching, transfer the secondary leaching solution to a multi - stage series - connected adsorption tower for recycling adsorption. The lean solution after being adsorbed by activated carbon in the adsorption tower returns to the filtrate tank, and this cycle is repeated until the gold concentration in the secondary leaching solution in the filtrate tank is lower than 0.02 g / m 3 and the silver concentration is lower than 1.40 g / m 3 at which point the cycle stops. The gold and silver in the leaching solution are adsorbed by activated carbon to obtain gold - loaded activated carbon and lean solution; at this time, the secondary leaching residue is filtered and stacked in the tailings pond, and the filtrate and lean solution filtered from the secondary leaching residue return to the recovery system;

[0011] (4) Desorption and electrowinning of gold - loaded activated carbon: Transfer the gold - loaded activated carbon in the adsorption tower to a desorption column for desorption and electrowinning to recover and extract gold and silver. The specific desorption and electrowinning process is a conventional process and will not be elaborated here.

[0012] Further, in step (1), the solid - liquid ratio of carbon sludge to production return water is 1:2 - 4.

[0013] Further, in step (1), the concentration of the sodium cyanide solution is 0.03% - 0.05%, the cyanidation leaching temperature is 45 - 65 °C, and the leaching time is 1 - 1.5 h.

[0014] Further, in step (2), the pH value of cyanidation leaching > 12, the sodium cyanide concentration is 0.03% - 0.05%, the leaching temperature is 60 - 80 °C, and the leaching time is 2 - 3 h.

[0015] Further, in step (2), the rotation speed of the stirring device is 50 - 90 rpm; the frequency of the ultrasonic device is 10 - 30 kHz; the delivery pressure of oxygen is 0.7 - 0.9 MPa and the flow rate is 70 - 100 L / min; the delivery flow rate of ozone is 5 - 15 L / min.

[0016] The present invention also provides a system for the method of recovering gold from low-grade gold-containing carbonaceous sludge as described above. The system includes a first-stage leaching tank. The discharge port of the first-stage leaching tank is connected to the feed port of the second-stage leaching tank through a transfer pump and a pipeline. A filter screen is vertically arranged in the second-stage leaching tank, and the filter screen divides one side of the second-stage leaching tank into a filtrate tank. A stirring device and at least two ultrasonic devices are also arranged in the second-stage leaching tank. The ultrasonic devices are electrically connected to an ultrasonic controller, and the ultrasonic devices are also connected to an air compressor and an ozone storage tank through air pipes. The discharge port of the filtrate tank is connected to the feed port of a multi-stage series adsorption tower through a transfer pump and a pipeline, and the liquid outlet of the multi-stage series adsorption tower is communicated with the feed port of the filtrate tank through a pipeline.

[0017] Further, the ultrasonic device includes a housing, a first-stage amplitude transformer and a second-stage amplitude transformer connected to it in sequence. An ultrasonic tool head is connected below the second-stage amplitude transformer. A amplitude transformer housing is sleeved outside the ultrasonic tool head. The top of the amplitude transformer housing is connected to the second-stage amplitude transformer. Two air inlets are opened on the side wall of the second-stage amplitude transformer, and the air inlets lead from the side wall of the second-stage amplitude transformer to the inner cavity of the amplitude transformer housing. One of the air inlets is connected to the air compressor through an air pipe, and the other air inlet is connected to the ozone storage tank through an air pipe. A plurality of air outlet holes are opened on the circumferential wall of the amplitude transformer housing.

[0018] Further, the first-stage amplitude transformer and the second-stage amplitude transformer are connected by a flange.

[0019] Further, the feed port of the first adsorption tower of the multi-stage series adsorption tower is connected to the discharge port of the filtrate tank, the liquid outlet of the last adsorption tower is connected to the feed port of the filtrate tank, and the liquid outlet of the previous adsorption tower is connected to the feed port of the next adsorption tower, and so on until the last adsorption tower.

[0020] The beneficial effects of the present invention: The present invention can efficiently recover gold and silver in low-grade gold-containing carbonaceous sludge, and the leaching rates of gold and silver can reach 80% - 92% for gold and 70% - 85% for silver. The specific technical benefits are reflected in the following aspects:

[0021] (1) According to the actual situation of the carbonaceous sludge generated in the desorption workshop, the present invention realizes the deep leaching of gold and silver in the carbonaceous sludge under the condition of low energy consumption through two-stage leaching (the first-stage conventional cyanide leaching and the second-stage ultrasonic enhanced-ozone / oxygen-enriched synergistic leaching), and by setting a stirring device, ultrasonic devices and an ozone / oxygen-enriched aeration supply device in the second-stage leaching tank and through the synergistic action of multiple means. Compared with the traditional treatment methods, the resource recovery and utilization effect is remarkable.

[0022] (2) The ultrasonic device added in the second-stage leaching of the present invention will generate mechanical vibration and cavitation effect, strengthen the agitation and stirring of the materials, and strip the coating layer of the materials, realizing the deep leaching of the unreacted nuclei inside the materials and greatly improving the leaching rate of gold and silver. Moreover, when the ultrasonic device is working, supplemented by the gas introduced by the ozone / enriched oxygen aeration supply equipment, and based on the design of several air outlets on the horn housing, the Venturi tube effect will be generated to form a strong jet airflow, which can not only play a stirring role but also further strengthen the cavitation effect, impact the outer coating of the product, expose the unreacted inner core of the materials, and further achieve deep leaching.

[0023] (3) The oxygen introduced in the second-stage leaching of the present invention can also increase the dissolved oxygen content, accelerate the leaching speed, improve the leaching rate and treatment capacity of gold; low-concentration ozone can not only accelerate the dissolution of gold but also avoid the formation of an oxide film on the surface of gold, which affects leaching. Under the dual effects of ozone / enriched oxygen, the leaching of gold continuously and rapidly progresses in the forward reaction, and the leaching effect and efficiency of gold and silver are both improved.

[0024] (4) The integrated design of the second-stage leaching tank and the filtrate tank of the present invention realizes the production mode of "leaching while sucking", accelerates the forward progress of the reaction, and greatly improves the leaching efficiency. Description of the Drawings

[0025] Figure 1 is the equipment connection diagram of Example 4;

[0026] Figure 2 is Figure 1 the structural schematic diagram of the ultrasonic device in

[0027] In the figure: 1 - the first-stage leaching tank; 2 - the second-stage leaching tank; 3 - the filtrate tank; 4 - the filter screen; 5 - the ultrasonic device, 501 - the housing, 502 - the first-stage horn, 503 - the flange, 504 - the air inlet, 505 - the second-stage horn, 506 - the ultrasonic tool head, 507 - the horn housing, 508 - the air outlet; 6 - the stirring device; 7 - the ultrasonic controller; 8 - the air compressor; 9 - the ozone storage tank; 10 - the multi-stage series adsorption tower. Detailed Embodiments

[0028] In order to make the technical problems and technical solutions solved by the present invention clearer, the following further elaborates on the present invention in conjunction with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Example 1

[0029] The carbonaceous sludge to be treated in the return water tank of a desorption workshop, with the gold grade of 126.05 g / t and the silver grade of 1407.58 g / t.

[0030] The method of the present invention is used for gold and silver recovery, and the specific process and effects are as follows:

[0031] (1) Conventional cyanidation leaching in the first stage: Mix the carbonaceous sludge in the return water tank of the desorption workshop and the production return water at a solid-liquid ratio of 1:2, add lime milk solution to adjust the pH value to 12, then add 0.05% sodium cyanide solution, stir for cyanidation leaching, control the leaching temperature at about 45 °C during the leaching process, and obtain the first-stage leaching residue and the first-stage leaching solution after 1 hour of leaching; sample and detect that the gold and silver grades in the first-stage leaching residue are 58.90 g / t and 850.32 g / t respectively, and the leaching rates of gold and silver are 53.27% and 39.59% respectively.

[0032] (2) Ultrasonic intensification - ozone / oxygen-enriched synergistic leaching in the second stage: Mix the first-stage leaching residue and the leaching solution obtained in step (1) and transfer them into the leaching tank, add lime milk solution to adjust the pH value to 12, and then add 0.05% sodium cyanide solution for cyanidation leaching. At the same time, start the stirring device and the ultrasonic device, open the ozone and oxygen supply equipment for aeration, and intensify the leaching under the synergistic action of the ultrasonic device, ozone and oxygen. Control the temperature at about 60 °C during the leaching process. After 2 hours of leaching, obtain the second-stage leaching residue and the second-stage leaching solution. The second-stage leaching solution enters the filtrate tank through the filter screen in the leaching tank; sample and detect that the gold and silver grades in the second-stage leaching residue are 24.90 g / t and 427.37 g / t respectively, and the leaching rates of gold and silver are 80.25% and 69.64% respectively.

[0033] In addition, during the leaching process, the rotation speed of the stirring device is 90 rpm, the frequency of the ultrasonic device is 30 kHz, the ozone flow rate is 15 L / min, the pressure of the compressed air is 0.90 Mpa, and the flow rate is 100 L / min.

[0034] (3) Recycling adsorption of the second-stage leaching solution: After 1 hour of ultrasonic intensification leaching - ozone / oxygen-enriched synergistic leaching in the second stage, transfer the second-stage leaching solution to a multi-stage series-connected adsorption tower for recycling adsorption. The lean liquid after adsorption by activated carbon in the adsorption tower returns to the filtrate tank, and this cycle is repeated until the gold concentration in the second-stage leaching solution in the filtrate tank is lower than 0.02 g / m 3 and the silver concentration is lower than 1.40 g / m 3 Then stop the cycle. Adsorb gold and silver in the leaching solution by activated carbon to obtain gold-loaded activated carbon and lean liquid; at this time, the second-stage leaching residue is filtered and stacked in the tailings pond, and the filtrate and lean liquid filtered out from the second-stage leaching residue return to the recovery system;

[0035] (4) Desorption and electrowinning of gold-loaded activated carbon: Finally, transfer the gold-loaded activated carbon in the adsorption tower to the desorption column for desorption and electrowinning to recover and extract gold and silver. The specific desorption and electrowinning process is a conventional process and will not be elaborated here. Example 2

[0036] The carbonaceous sludge to be processed is the carbonaceous sludge of Example 1, and the gold and silver are recovered by the method described in the present invention. The specific process and effects are as follows:

[0037] (1)I-stage conventional cyanidation leaching: Mix the carbonaceous sludge in the return water tank of the desorption workshop with the production return water at a solid-liquid ratio of 1:3, add lime milk solution to adjust the pH value to 12, then add 0.05% sodium cyanide solution, stir for cyanidation leaching, and control the leaching temperature at about 55 °C during the leaching process. After leaching for 1 h, obtain the I-stage leaching residue and the I-stage leaching solution; sample and detect that the gold and silver grades in the I-stage leaching residue are 37.40 g / t and 748.17 g / t respectively, and the leaching rates of gold and silver are 70.33% and 46.85% respectively.

[0038] (2)II-stage ultrasonic intensification-ozone / oxygen-enriched synergistic leaching: Mix the I-stage leaching residue and leaching solution obtained in step (1) and transfer them into the leaching tank, add lime milk solution to adjust the pH value to 12, and then add 0.05% sodium cyanide solution for cyanidation leaching. At the same time, start the stirring device and the ultrasonic device, open the ozone and oxygen supply equipment for aeration, and intensify the leaching under the synergistic action of the ultrasonic device, ozone and oxygen. Control the temperature at about 70 °C during the leaching process. After leaching for 2.5 h, obtain the II-stage leaching residue and the II-stage leaching solution. The II-stage leaching solution enters the filtrate tank through the filter screen in the leaching tank; sample and detect that the gold and silver grades in the II-stage leaching residue are 16.10 g / t and 359.25 g / t respectively, and the leaching rates of gold and silver are 87.23% and 74.48% respectively.

[0039] In addition, during the leaching process, the rotation speed of the stirring device is 75 rpm, the frequency of the ultrasonic device is 20 kHz, the ozone flow rate is 10 L / min, the pressure of the compressed air is 0.80 Mpa, and the flow rate is 85 L / min.

[0040] (3)Circulating adsorption of the II-stage leaching solution: After 1 h of II-stage ultrasonic intensification leaching-ozone / oxygen-enriched synergistic leaching, transfer the II-stage leaching solution to a multi-stage series adsorption tower for circulating adsorption. The lean solution after being adsorbed by the activated carbon in the adsorption tower returns to the filtrate tank, and this cycle is repeated until the gold concentration in the II-stage leaching solution in the filtrate tank is lower than 0.02 g / m 3 、the silver concentration is lower than 1.40 g / m 3 When it reaches this level, stop the cycle, adsorb gold and silver in the leaching solution through activated carbon to obtain gold-loaded activated carbon and lean solution; at this time, the II-stage leaching residue is filtered and stacked in the tailings pond, and the filtrate and lean solution filtered from the II-stage leaching residue are returned to the recovery system;

[0041] (4)Desorption and electrowinning of gold-loaded activated carbon: Finally, transfer the gold-loaded activated carbon in the adsorption tower to the desorption column for desorption and electrowinning to recover and extract gold and silver. The specific desorption and electrowinning process is a conventional process and will not be elaborated here. Example 3

[0042] The carbonaceous sludge to be processed is the carbonaceous sludge of Example 1, and the method described in the present invention is used for gold and silver recovery. The specific process and effects are as follows:

[0043] (1) Conventional cyanidation leaching in the first stage: The carbonaceous sludge in the return water tank of the desorption workshop is mixed with production return water at a solid-liquid ratio of 1:4, and lime milk solution is added to adjust the pH value to 12. Subsequently, a 0.05% sodium cyanide solution is added, and stirring cyanidation leaching is carried out. During the leaching process, the leaching temperature is controlled at about 65°C. After leaching for 1.5 h, the first-stage leaching residue and the first-stage leaching solution are obtained; samples are taken to detect that the gold and silver grades in the first-stage leaching residue are 20.50 g / t and 426.85 g / t respectively, and the leaching rates of gold and silver are 83.74% and 69.67% respectively.

[0044] (2) Ultrasonic intensification-ozone / oxygen-enriched synergistic leaching in the second stage: The first-stage leaching residue and leaching solution obtained in step (1) are mixed and transferred into the leaching tank. Lime milk solution is added to adjust the pH value to 12, and then a 0.05% sodium cyanide solution is added for cyanidation leaching. At the same time, the stirring device and the ultrasonic device are started, and the ozone and oxygen supply equipment are opened for aeration. Under the synergistic action of the ultrasonic device, ozone and oxygen, the leaching is intensified. During the leaching process, the temperature is controlled at about 80°C. After leaching for 2.5 h, the second-stage leaching residue and the second-stage leaching solution are obtained. The second-stage leaching solution enters the filtrate tank through the filter screen in the leaching tank; samples are taken to detect that the gold and silver grades in the second-stage leaching residue are 9.80 g / t and 212.11 g / t respectively, and the leaching rates of gold and silver are 92.23% and 84.93% respectively.

[0045] In addition, during the leaching process, the rotation speed of the stirring device is 50 rpm, the frequency of the ultrasonic device is 10 kHz, the ozone flow rate is 5 L / min, the pressure of the compressed air is 0.70 Mpa, and the flow rate is 70 L / min.

[0046] (3) Recycling and adsorption of the second-stage leaching solution: After 1 h of ultrasonic intensification leaching-ozone / oxygen-enriched synergistic leaching in the second stage, the second-stage leaching solution is transferred to a multi-stage series adsorption tower for recycling and adsorption. The lean solution after adsorption by activated carbon in the adsorption tower is returned to the filtrate tank, and this is repeated until the gold concentration in the second-stage leaching solution in the filtrate tank is lower than 0.02 g / m 3 and the silver concentration is lower than 1.40 g / m 3 at which time the circulation is stopped. The gold and silver in the leaching solution are adsorbed by activated carbon to obtain gold-loaded activated carbon and lean solution; at this time, the second-stage leaching residue is filtered and stacked in the tailings pond, and the filtrate and lean solution filtered out from the second-stage leaching residue are returned to the recovery system;

[0047] (4) Desorption and electrowinning of gold-loaded activated carbon to extract gold: Finally, the gold-loaded activated carbon in the adsorption tower is transferred to the desorption column for desorption and electrowinning to recover and extract gold and silver. The specific desorption and electrowinning process is a conventional process and will not be elaborated here. Example 4

[0048] This embodiment provides a system for recovering gold from low-grade gold-containing carbonaceous sludge, including a first-stage leaching tank 1. The discharge port of the first-stage leaching tank 1 is connected to the feed port of a second-stage leaching tank 2 through a delivery pump and a pipeline. A filter screen 4 is vertically arranged in the second-stage leaching tank 2, and the filter screen 4 divides one side of the second-stage leaching tank 2 into a filtrate tank 3. A stirring device 6 and at least two ultrasonic devices 5 are also arranged in the second-stage leaching tank 2. The ultrasonic devices 5 are electrically connected to an ultrasonic controller 7, and the ultrasonic devices 5 are also connected to an air compressor 8 and an ozone storage tank 9 through air pipes. The discharge port of the filtrate tank 3 is connected to the feed port of a multi-stage series adsorption tower 10 through a delivery pump and a pipeline, and the liquid outlet of the multi-stage series adsorption tower 10 is communicated with the feed port of the filtrate tank 3 through a pipeline. In addition, valves are installed on the air pipes of the air compressor and the ozone storage tank near their air outlets, and valves are also installed at the discharge ports of the first-stage leaching tank 1 and the filtrate tank 3.

[0049] Preferably, the ultrasonic device 5 includes a housing 501, a first-stage horn 502 and a second-stage horn 505 connected to it in sequence. The first-stage horn 502 and the second-stage horn 505 are connected by a flange 503. An ultrasonic tool head 506 is connected below the second-stage horn 505. A horn housing 507 is sleeved outside the ultrasonic tool head 506. The top of the horn housing 507 is connected to the second-stage horn 505. Two air inlets 504 are arranged on the side wall of the second-stage horn 505. The air inlets 504 lead from the side wall of the second-stage horn 505 to the inner cavity of the horn housing 507. One of the air inlets 504 is connected to the air compressor 8 through an air pipe, and the other air inlet 504 is connected to the ozone storage tank 9 through an air pipe. A plurality of air outlet holes 508 are arranged on the circumferential wall of the horn housing 507.

[0050] When the ultrasonic device is working, the ultrasonic device 5 is started through the ultrasonic controller 7. The first horn 502 and the second horn 505 start to vibrate, thereby driving the ultrasonic tool head 506 to vibrate, generating mechanical vibration and cavitation effect. The mechanical vibration can drive the stirring of the first-stage leaching residue and the first-stage leaching solution in the second-stage leaching tank 2. The cavitation effect can penetrate the leaching residue and strip the coating layer of the material, realizing the deep leaching of the unreacted core inside the material and greatly improving the leaching rate of gold and silver. At the same time, the air compressor 8, the ozone storage tank 9 and the valves on the air pipe are opened to introduce oxygen and ozone into the ultrasonic device. After the gas enters the inner cavity of the horn housing 507 through the air inlet 504, it jets out from the air outlet 508 along with the vibration of the ultrasonic tool head 506. The design of the air outlet 508 will produce the Venturi tube effect and form a strong jet airflow. This airflow can not only play a stirring role, but also further strengthen the cavitation effect, impact the outer coating of the product, expose the unreacted inner core of the material, and further carry out deep leaching. In addition, the introduced oxygen can increase the dissolved oxygen content, accelerate the leaching speed, and improve the leaching rate and treatment capacity of gold. Low-concentration ozone can not only accelerate the dissolution of gold, but also avoid the formation of an oxide film on the surface of gold, which affects leaching. Under the dual effects of ozone / oxygen enrichment, the leaching of gold continuously advances rapidly in the forward reaction (the reaction formula is 4Au + 8CN - + O2 + 2H2O → 4Au(CN)2 - + 4OH - ), and the leaching effect and efficiency of gold and silver are both improved.

[0051] Specifically, the feed inlet of the first adsorption tower of the multi-stage series adsorption tower 10 is connected to the discharge outlet of the filtrate tank 3, the liquid outlet of the last adsorption tower is connected to the feed inlet of the filtrate tank 3, and the liquid outlet of the previous adsorption tower is connected to the feed inlet of the next adsorption tower, and so on until the last adsorption tower.

[0052] When the system is working: the carbon mud in the return water tank of the desorption workshop is transferred into the first-stage leaching tank 1, and the production return water is added and mixed in proportion, then the lime milk solution is added for adjustment, and then the sodium cyanide solution is added, and stirred for cyanidation leaching to obtain the first-stage leaching residue and the first-stage leaching solution;

[0053] The first-stage leaching residue and the leaching solution are mixed and transferred into the second-stage leaching tank 2, and the sodium cyanide solution is added for cyanidation leaching. At the same time, the stirring device 6 and the ultrasonic device 5 are started, and the air compressor 8 and the ozone storage tank 9 are opened to introduce oxygen and ozone into the ultrasonic device 5 for aeration. Under the synergistic action of the vibration, cavitation of the ultrasonic device 5 and the aeration of oxygen and ozone, the gold and silver in the first-stage leaching residue are intensively leached, and the leaching rate and leaching efficiency are greatly improved. At the same time, the second-stage leaching residue and the second-stage leaching solution obtained by leaching are separated by the filter screen 4. The second-stage leaching residue is stored in the second-stage leaching tank, and the second-stage leaching solution is stored in the filtrate tank 3;

[0054] After the ultrasonic device 5 has been operating for 1 hour, open the valve at the discharge port of the filtrate tank 3 and start the transfer pump to pump the second-stage leaching solution into the multi-stage series adsorption tower 10 for activated carbon adsorption. The lean solution after being adsorbed by the activated carbon in the adsorption tower returns to the filtrate tank 3, and this cycle is repeated until the gold concentration in the second-stage leaching solution in the filtrate tank 3 is lower than 0.02 g / m 3 and the silver concentration is lower than 1.40 g / m 3 . Stop the cycle at this time to obtain gold-loaded activated carbon and lean solution; at this time, the second-stage leaching residue is pressure-filtered and stored in the tailings pond. The filtrate and lean solution filtered out from the second-stage leaching residue are returned to the recovery system, while the gold-loaded activated carbon is transferred to the desorption column for desorption and electrowinning to recover and extract gold and silver.

[0055] The present invention has been described in detail through specific and preferred embodiments, but those skilled in the art should understand that the present invention is not limited to the above-described embodiments. Any modifications, equivalent replacements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for recovering gold from low-grade gold-containing carbon mud, characterized in that: The steps include: (1) Stage I conventional cyanide leaching: The carbon mud in the desorption workshop return water pool is mixed with the production return water in proportion, and the pH value is adjusted to >12 by adding lime milk solution, followed by adding sodium cyanide solution and stirring for cyanide leaching to obtain stage I leaching residue and stage I leaching liquid; (2) Stage II ultrasonic enhanced-ozone / oxygen-enriched synergistic leaching: The stage I leaching residue and the leaching liquid obtained in step (1) are mixed and transferred into a leaching tank, sodium cyanide solution is added for cyanide leaching, and a stirring device and an ultrasonic device are started at the same time, and ozone and oxygen supply equipment are turned on for aeration. Leaching is enhanced under the synergistic effect of the ultrasonic device and ozone and oxygen to obtain stage II leaching residue and stage II leaching liquid, and the stage II leaching liquid passes through the filter in the leaching tank and enters the filtrate tank; (3) Circulation adsorption of stage II leachate: After 1 hour of ultrasonic enhanced leaching-ozone / oxygen-enriched leaching in stage II, the stage II leachate is transferred to a multi-stage adsorption tower in series for circulation adsorption. The lean liquid adsorbed by activated carbon in the adsorption tower is returned to the filtrate tank. This cycle is repeated until the gold concentration of the stage II leachate in the filtrate tank is lower than 0.02 g / m 3 , silver concentration is less than 1.40g / m 3 The circulation is stopped at this time, and the gold and silver in the leaching solution are adsorbed by activated carbon to obtain gold-loaded activated carbon and barren solution. At this time, the leaching residue of stage II is filtered and stored in the tailings pond, and the filtrate and barren solution filtered from the leaching residue of stage II are returned to the recovery system. (4) Desorption and electrowinning of gold-loaded activated carbon: The gold-loaded activated carbon in the adsorption tower is transferred to the desorption column for desorption and electrowinning to recover gold and silver; The system used in the above method comprises a stage I leaching tank (1), wherein the discharge port of the stage I leaching tank (1) is connected to the feed port of the stage II leaching tank (2) through a delivery pump and a pipeline, and a filter screen (4) is vertically arranged in the stage II leaching tank (2), and the filter screen (4) separates one side of the stage II leaching tank (2) into a filtrate tank (3); a stirring device (6) and at least two ultrasonic devices (5) are also arranged in the stage II leaching tank (2), and the ultrasonic device (5) is electrically connected to an ultrasonic controller (7), and the ultrasonic device (5) is also connected to an air compressor (8) and an ozone storage tank (9) through an air pipe; the discharge port of the filtrate tank (3) is connected to the feed port of a multi-stage series adsorption tower (10) through a delivery pump and a pipeline, and the liquid discharge port of the multi-stage series adsorption tower (10) is connected to the feed port of the filtrate tank (3) through a pipeline; The ultrasonic device (5) comprises a housing (501) and a primary horn (502) and a secondary horn (505) connected thereto in sequence; an ultrasonic tool head (506) is connected below the secondary horn (505); a horn housing (507) is sleeved on the outside of the ultrasonic tool head (506); the top of the horn housing (507) is connected to the secondary horn (505); two air inlets (504) are provided on the side wall of the secondary horn (505); the air inlets (504) lead from the side wall of the secondary horn (505) to the inner cavity of the horn housing (507); one of the air inlets (504) is connected to an air compressor (8) via an air pipe, and the other air inlet (504) is connected to an ozone storage tank (9) via an air pipe; a plurality of air outlet holes (508) are provided on the circumferential wall of the horn housing (507).

2. A method for recovering gold from low-grade gold-containing carbon mud according to claim 1, characterized in that: In step (1), the solid-liquid ratio of carbon sludge to production return water is 1:2-4.

3. A method for recovering gold from low-grade gold-containing carbon mud according to claim 1 or 2, characterized in that: In step (1), the concentration of the sodium cyanide solution is 0.03% to 0.05%, the cyanide leaching temperature is 45 to 65° C., and the leaching time is 1 to 1.5 h.

4. A method for recovering gold from low-grade gold-containing carbon mud according to claim 1, characterized in that: In step (2), the pH value of cyanide leaching is greater than 12, the concentration of sodium cyanide is 0.03% to 0.05%, the leaching temperature is 60 to 80° C., and the leaching time is 2 to 3 hours.

5. A method for recovering gold from low-grade gold-containing carbon mud according to claim 1 or 4, characterized in that: In step (2), the rotation speed of the stirring device is 50 to 90 rpm; the frequency of the ultrasonic device is 10 to 30 kHz; the delivery pressure of oxygen is 0.7 to 0.9 MPa and the flow rate is 70 to 100 L / min; and the delivery flow rate of ozone is 5 to 15 L / min.

6. A method for recovering gold from low-grade gold-containing carbon mud according to claim 1, characterized in that: The primary horn (502) and the secondary horn (505) are connected via a flange (503).

7. The method for recovering gold from low-grade gold-containing carbon mud according to claim 1, characterized in that: The feed inlet of the first adsorption tower of the multi-stage series adsorption tower (10) is connected to the discharge port of the filtrate tank (3), the discharge port of the last adsorption tower is connected to the feed inlet of the filtrate tank (3), the discharge port of the previous adsorption tower is connected to the feed inlet of the next adsorption tower, and so on until the last adsorption tower.

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