A device and method for recycling cyanide lean liquor permeate after membrane treatment

Abstract

This invention discloses a membrane treatment device and method for recycling permeate from cyanide lean liquor. The device includes a membrane system, a secondary scrubbing tower, a primary scrubbing tower, a secondary leaching tank, and a precious liquor tank. Both the secondary and primary scrubbing towers are used to scrub the permeate. The inlet of the secondary scrubbing tower is connected to the permeate outlet of the membrane system, and the inlet of the primary scrubbing tower is connected to the supernatant outlet of the secondary scrubbing tower. The precious liquor tank is used to replace the precious liquor flowing out of the primary scrubbing tower and to transport the resulting lean liquor to the membrane system. The inlet of the precious liquor tank is connected to the supernatant outlet of the primary scrubbing tower, and the outlet of the precious liquor tank is connected to the inlet of the membrane system. The secondary leaching tank is used to perform secondary leaching on the slurry flowing out of the primary scrubbing tower and to transport the slurry after secondary leaching to the secondary scrubbing tower. The inlet of the secondary leaching tank is connected to the underflow outlet of the primary scrubbing tower, and the outlet of the secondary leaching tank is connected to the inlet of the secondary scrubbing tower.

Description

Technical Field

[0001] This invention relates to the field of resources and environmental technology, specifically to a device and method for recycling cyanide lean liquor produced through membrane treatment. Background Technology

[0002] There are domestic examples of cyanide plants using membrane separation technology to treat lean liquor and reuse it in gold cyanide leaching systems. Gold cyanide lean liquor typically has a low concentration, generally between 500 and 1000 mg / L. After membrane treatment, the permeate containing some free cyanide can be used in the gold leaching system. Its application in silver mine cyanide plants is not described. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide a device and method for recycling water produced by membrane treatment of cyanide lean liquor, which solves the problem of how to dispose of water produced after membrane treatment of silver concentrate cyanide lean liquor and significantly reduces the amount of lean liquor produced by the silver concentrate cyanide system to be degraded and treated.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a membrane treatment and permeate recycling device for cyanide lean liquor, comprising a membrane system for treating silver concentrate cyanide lean liquor to separate concentrated water and permeate; further comprising a secondary washing tower, a primary washing tower, a secondary leaching tank, and a precious liquor tank; the secondary washing tower and the primary washing tower are both used for washing the permeate, wherein the inlet of the secondary washing tower is connected to the permeate outlet of the membrane system, and the inlet of the primary washing tower is connected to the supernatant outlet of the secondary washing tower; the precious liquor tank is used for replacing the precious liquor flowing out of the primary washing tower and transporting the resulting lean liquor to the membrane system, wherein the inlet of the precious liquor tank is connected to the supernatant outlet of the primary washing tower, and the outlet of the precious liquor tank is connected to the inlet of the membrane system; the secondary leaching tank is used for secondary leaching of the slurry flowing out of the primary washing tower and transporting the slurry after secondary leaching to the secondary washing tower; wherein the inlet of the secondary leaching tank is connected to the underflow outlet of the primary washing tower, and the outlet of the secondary leaching tank is connected to the inlet of the secondary washing tower.

[0005] Based on the above technical solution, a decomposition device is also included, which is connected to the concentrate outlet of the membrane system and is used to decompose the separated concentrate.

[0006] Based on the above technical solution, a waste residue recovery device is also included, which is connected to the underflow outlet of the secondary washing tower and is used to collect leaching residue.

[0007] Based on the above technical solution, the membrane system is an RO reverse osmosis membrane.

[0008] This invention also provides a method for recycling cyanide lean liquor after membrane treatment, comprising the following steps:

[0009] Step S1. The lean liquor displaced by the silver concentrate cyanide leaching system enters the membrane system. The concentrated water separated after membrane treatment is decomposed and the permeate enters the secondary washing tower.

[0010] Step S2. The permeate enters the washing operation from the bottom of the secondary washing tower, undergoes three countercurrent washings, and reaches the top of the secondary washing tower. The washed permeate overflows from the top and enters the primary washing tower. The leaching residue at the bottom of the secondary washing tower enters the waste residue recovery device.

[0011] Step S3. The washed product water enters the washing operation from the bottom of the primary washing tower, and after three countercurrent washings, it enters the top of the primary washing tower. The precious solution overflows from the top of the primary washing tower to the precious solution pool. The slurry flowing from the bottom of the primary washing tower enters the secondary leaching operation. After leaching is completed, it enters the secondary washing tower again.

[0012] Step S4. The precious solution in the precious solution tank is replaced to produce lean solution, which then enters the membrane treatment system.

[0013] Based on the above technical solution, in step S1, the silver concentrate cyanide leaching system includes grinding, pre-oxidation, slurry preparation, leaching, washing, and displacement processes.

[0014] Based on the above technical solution, in step S2, the grade of the leaching residue is 180 g / t.

[0015] Based on the above technical solution, in step S3, the concentration of the bottom slurry discharged from the primary washing tower is 55% to 65%, and the total amount of free cyanide in the slurry is 300 mg / L.

[0016] Based on the above technical solution, in step S3, after the bottom slurry of the primary washing tower enters the secondary leaching and is readjusted, the pH value is adjusted to 11, and sodium cyanide is added for secondary leaching.

[0017] The beneficial effects of this invention are as follows:

[0018] 1. In this invention, when the cyanide lean liquor enters the silver concentrate cyanidation system after membrane treatment, in accordance with the principle of maximizing advantages and avoiding disadvantages, the membrane permeate contains some free cyanide (about 500 mg / L) which can be reused. However, because it still contains a lot of base metal ions such as copper and zinc, this type of membrane permeate enters from the washing operation when it is returned to the silver concentrate cyanidation system for reuse.

[0019] 2. In this invention, the product water is used instead of the clean water as the washing water, which increases the total amount of free cyanide in the slurry discharged from the first wash bottom stream from 50 mg / L to 300 mg / L, and reduces the amount of sodium cyanide added during the second leaching by 20%.

[0020] 3. In the washing tower, this invention plays an auxiliary leaching role, reducing the silver grade of the cyanide leaching residue from about 200 g / t to 180 g / t.

[0021] 4. This invention can reduce the amount of wastewater to be treated by about 60%, and the wastewater treatment cost will decrease by about 40% accordingly. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a membrane treatment and water recycling device for cyanide lean liquor in an embodiment of the present invention.

[0023] Figure label:

[0024] 1- Membrane system; 2- Secondary scrubbing tower; 3- Primary scrubbing tower; 4- Preservative solution tank; 5- Secondary leaching tank; 6- Decomposition device; 7- Waste residue recovery device. Detailed Implementation

[0025] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout.

[0026] The following description, in conjunction with the accompanying drawings, further illustrates specific embodiments of the present invention, making the technical solution and its beneficial effects clearer and more explicit. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, but should not be construed as limiting the invention.

[0027] See Figure 1 As shown, this embodiment of the invention provides a membrane-treated permeate recycling device for cyanide lean liquor, including a membrane system 1. This membrane system 1 is used to treat silver concentrate cyanide lean liquor, separating concentrated water and permeate; specifically, the membrane system 1 is an RO reverse osmosis membrane. The membrane-treated permeate recycling device for cyanide lean liquor also includes a secondary washing tower 2, a primary washing tower 3, a secondary leaching tank 5, and a precious liquor tank 4;

[0028] Both the secondary scrubbing tower 2 and the primary scrubbing tower 3 are used to wash the product water. The inlet of the secondary scrubbing tower 2 is connected to the product water outlet of the membrane system 1, and the inlet of the primary scrubbing tower 3 is connected to the supernatant outlet of the secondary scrubbing tower 2.

[0029] The precious liquid tank 4 is used to replace the precious liquid flowing out of the primary scrubbing tower 3 and to transport the resulting lean liquid to the membrane system 1. The inlet of the precious liquid tank 4 is connected to the supernatant outlet of the primary scrubbing tower 3, and the outlet of the precious liquid tank 4 is connected to the inlet of the membrane system 1.

[0030] The secondary leaching tank 5 is used to perform secondary leaching on the slurry flowing out of the primary washing tower 3, and to transport the slurry that has completed the secondary leaching to the secondary washing tower 2; wherein, the inlet of the secondary leaching tank 5 is connected to the underflow outlet flowing out of the primary washing tower 3, and the outlet of the secondary leaching tank 5 is connected to the inlet of the secondary washing tower 2.

[0031] The cyanide lean liquor membrane treatment product water recycling device also includes a decomposition device 6, which is connected to the concentrate outlet of the membrane system 1 and is used to decompose the separated concentrate.

[0032] The cyanide lean liquor membrane treatment water recycling device also includes a waste residue recovery device 7, which is connected to the underflow outlet of the secondary washing tower 2 and is used to collect leaching residue.

[0033] This invention also provides a method for recycling cyanide lean liquor treated by membrane treatment, comprising the following steps:

[0034] Step S1. The lean liquor displaced by the silver concentrate cyanide leaching system enters the membrane system 1. The concentrated water separated after membrane treatment is decomposed and the product water enters the secondary washing tower 2. Specifically, the silver concentrate cyanide leaching system includes grinding, pre-oxidation, slurry preparation, leaching, washing and displacement processes.

[0035] Step S2. The permeate enters the washing operation from the bottom of the secondary washing tower 2, and after three countercurrent washings, it reaches the top of the secondary washing tower 2. The washed permeate overflows from the top and enters the primary washing tower 3. The leaching residue at the bottom of the secondary washing tower 2 enters the waste residue recovery device 7. Specifically, the grade of the leaching residue is 180g / t.

[0036] Step S3. The washed permeate enters the washing operation from the bottom of the primary washing tower 3, undergoes three countercurrent washes, and then enters the top of the primary washing tower 3. The precious solution overflows from the top of the primary washing tower 3 to the precious solution tank 4. The slurry from the bottom of the primary washing tower 3 enters the secondary leaching operation. After leaching is completed, it enters the secondary washing tower 2 again. Specifically, the concentration of the slurry discharged from the bottom of the primary washing tower 3 is 55%–65%, and the total free cyanide in the slurry is 300 mg / L. After the slurry from the bottom of the primary washing tower 3 enters the secondary leaching process and is readjusted, the pH value is adjusted to 11, and sodium cyanide is added for secondary leaching.

[0037] Step S4. The precious liquor in the precious liquor tank 4 is replaced to produce lean liquor, which then enters the membrane treatment system.

[0038] The lean liquor from the cyanidation process of complex silver concentrate contains a large amount of cyanide complex ions and free cyanide, with a total cyanide content of approximately 3500 mg / L. After treatment by an RO reverse osmosis membrane, it produces two products: concentrate and permeate. The concentrate accounts for 40% of the total lean liquor volume and contains over 8000 mg / L of total cyanide, which is then used for degradation. The permeate accounts for 60% of the total lean liquor volume and contains approximately 500 mg / L of total cyanide, of which approximately 400 mg / L is free cyanide. This permeate is reused in the silver concentrate cyanidation treatment system.

[0039] The entire silver concentrate cyanide leaching system includes processes such as grinding, pre-oxidation, slurry preparation, leaching, washing, and displacement. When the permeate enters the system, in accordance with the principle of maximizing advantages and avoiding disadvantages, the permeate enters the system from the washing operation.

[0040] As washing water, it separates high-concentration complex ions such as gold and silver from the leaching pulp, forming a precious solution; a small portion enters the cyanide leaching operation with the primary washing underflow. The concentration of the primary washing underflow pulp discharged is 60%, and the product water is used instead of the clear water as washing water, increasing the total free cyanide content in the primary washing underflow pulp discharged from 50 mg / L to 300 mg / L.

[0041] After the bottom runoff slurry from the first washing stage is re-mixed for secondary leaching, the pH is adjusted to 11, and sodium cyanide is added for secondary leaching. The free cyanide ions introduced by the permeate can assist in the leaching of target metals such as silver and gold, and the amount of sodium cyanide added during secondary leaching is reduced by 20%.

[0042] Using the product water as wash water, the free cyanide levels in the primary and secondary washing towers are relatively high. After the slurry that has completed the leaching operation enters the washing tower, the concentration of complexed cyanide ions decreases significantly after washing. The silver that was not leached in the leaching residue begins to leach slowly again under the action of free cyanide, causing the grade of the leaching residue to decrease throughout the washing process. The average level is: the leaching residue of 200g / t is reduced to 180g / t after the washing operation.

[0043] During implementation, the lean liquor displaced by the silver concentrate cyanide leaching system enters the membrane system, the separated concentrated water undergoes decomposition treatment, and the permeate is returned to the silver concentrate cyanide leaching system. Specifically, the flow path is as follows: membrane permeate enters the washing operation from the bottom of the secondary scrubbing tower, undergoes three countercurrent scrubbing cycles, reaches the top of the secondary scrubbing tower, and a portion overflows from the top into the bottom of the primary scrubbing tower. After three more countercurrent scrubbing cycles, it enters the top of the primary scrubbing tower and overflows from the top of the primary scrubbing tower into the precious liquor tank. The precious liquor undergoes a displacement operation to produce lean liquor, which enters the membrane treatment system. A portion flows from the bottom of the primary scrubbing tower into the secondary leaching operation. After leaching is complete, it re-enters the secondary scrubbing tower.

[0044] In the description of this specification, references to terms such as "an embodiment," "preferred," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. Illustrative expressions of the above terms in this specification do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0045] This invention is not limited to the embodiments described above. Those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications are also considered within the scope of protection of this invention. Contents not described in detail in this specification are prior art known to those skilled in the art.

Claims

1. A membrane treatment and permeate recycling device for lean cyanide liquor, comprising a membrane system (1) for treating lean silver concentrate cyanide liquor to separate concentrated water and permeate; characterized in that: It also includes a secondary washing tower (2), a primary washing tower (3), a secondary leaching tank (5), and a precious liquid tank (4); The secondary scrubbing tower (2) and the primary scrubbing tower (3) are both used to scrub the product water. The inlet of the secondary scrubbing tower (2) is connected to the product water outlet of the membrane system (1), and the inlet of the primary scrubbing tower (3) is connected to the supernatant outlet of the secondary scrubbing tower (2). The precious liquid tank (4) is used to replace the precious liquid flowing out of the primary scrubbing tower (3) and to transport the resulting lean liquid to the membrane system (1). The inlet of the precious liquid tank (4) is connected to the supernatant outlet of the primary scrubbing tower (3), and the outlet of the precious liquid tank (4) is connected to the inlet of the membrane system (1). The secondary leaching tank (5) is used to perform secondary leaching on the slurry flowing out of the primary washing tower (3) and to transport the slurry that has completed the secondary leaching to the secondary washing tower (2); wherein, the inlet of the secondary leaching tank (5) is connected to the underflow outlet of the primary washing tower (3), and the outlet of the secondary leaching tank (5) is connected to the inlet of the secondary washing tower (2).

2. The cyanide lean liquor membrane treatment and permeate recycling device as described in claim 1, characterized in that: It also includes a decomposition device (6), which is connected to the concentrate outlet of the membrane system (1) for decomposing the separated concentrate.

3. The cyanide lean liquor membrane treatment and permeate recycling device as described in claim 1, characterized in that: It also includes a waste residue recovery device (7), which is connected to the underflow outlet of the secondary washing tower (2) for collecting leaching residue.

4. The cyanide lean liquor membrane treatment and permeate recycling device as described in claim 1, characterized in that: The membrane system (1) is an RO reverse osmosis membrane.

5. A method for recycling cyanide lean liquor produced by membrane treatment, characterized in that, Includes the following steps: Step S1. The lean liquor displaced by the silver concentrate cyanide leaching system enters the membrane system (1). The concentrated water separated after membrane treatment is decomposed and the product water enters the secondary washing tower (2). Step S2. The permeate enters the washing operation from the bottom of the secondary washing tower (2), and after three countercurrent washings, it reaches the top of the secondary washing tower (2). The permeate after washing overflows from the top and enters the primary washing tower (3). The leaching residue from the bottom of the secondary washing tower (2) enters the waste residue recovery device (7). Step S3. The washed product water enters the washing operation from the bottom of the primary washing tower (3), and after three countercurrent washings, it enters the top of the primary washing tower (3). The precious liquid overflows from the top of the primary washing tower (3) to the precious liquid pool (4). The bottom slurry of the primary washing tower (3) enters the secondary leaching operation. After leaching is completed, it enters the secondary washing tower (2) again. Step S4. The precious liquid in the precious liquid tank (4) is replaced to produce lean liquid, which enters the membrane system (1).

6. The method for recycling cyanide lean liquor after membrane treatment as described in claim 5, characterized in that: In step S1, the silver concentrate cyanide leaching system includes grinding, pre-oxidation, slurry preparation, leaching, washing, and displacement processes.

7. The method for recycling cyanide lean liquor after membrane treatment as described in claim 5, characterized in that: In step S2, the grade of the leaching residue is 180 g / t.

8. The method for recycling cyanide lean liquor after membrane treatment as described in claim 5, characterized in that: In step S3, the concentration of the slurry discharged from the bottom of the primary washing tower (3) is 55%~65%, and the total amount of free cyanide in the slurry is 300 mg / l.

9. The method for recycling cyanide lean liquor after membrane treatment as described in claim 5, characterized in that: In step S3, after the bottom slurry of the primary washing tower (3) is re-adjusted for secondary leaching, the pH value is adjusted to 11, and sodium cyanide is added for secondary leaching.

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