Method for increasing recovery rate of roughed silver in zinc leaching residues

Abstract

The invention discloses a method for increasing the recovery rate of roughed silver in zinc leaching residues. Zinc leaching residues are guided into a thickener to be treated, treated ore pulp is pumped into a raw ore tank, and heavy calcium powder is added to adjust the pH value of the ore pulp; then sequentially conveying to a lifting tank, a mixing tank and a liquid separation tank for treatment, and leading out raw ore; the method comprises the following steps: distributing raw ore into two rows of rough flotation tanks, and adding black powder for flotation treatment to obtain concentrate foam; the silver content in the obtained concentrate foam is greater than 3000g / t, and the concentrate foam is sent to a concentrate tank; and when the silver content is smaller than 3000g / t, the silver concentrate is sequentially conveyed to a second fine flotation tank and a third fine flotation tank to be treated, silver concentrate is obtained after flotation, and a silver concentrate product is obtained after treatment. According to the method, rough single-row flotation is changed into double-row parallel flotation, the rough flotation capacity is improved, meanwhile, qualified silver concentrate produced by a rough flotation tank is rapidly recycled, useless circulation of the rough flotation concentrate in the system is reduced, the amount of silver metal entering fine flotation is reduced, then the fine flotation load is reduced, and the fine flotation capacity and the silver concentrate yield are improved.

Description

Technical Field

[0001] This invention belongs to the field of froth flotation, and specifically relates to a method for improving the recovery rate of rough silver in zinc leaching residue. This method is used to improve the recovery rate of rough silver, thereby increasing the overall silver metal yield. Background Technology

[0002] In zinc smelting, the raw zinc concentrate contains a certain amount of silver. In conventional hydrometallurgical zinc smelting, the zinc concentrate is roasted in a roasting furnace to obtain zinc calcinate, which contains 100-200 g / t of silver. After neutral and acidic leaching, the zinc, copper, cadmium, and some valuable metals are leached out, resulting in a slag yield of 48-49%. The associated silver metal enters the leaching slag, which contains 200-700 g / t of silver, indicating a high silver content and significant recovery value. Therefore, to avoid resource waste, the silver in this leaching slag needs further recovery.

[0003] Analysis of the physical composition of silver in leaching residue from conventional hydrometallurgical zinc production revealed a complex morphology and occurrence of silver. Most silver minerals exist in the residue as silver sulfide, silver chloride, and metallic silver, primarily in the form of silver sulfide, and its natural particles are within the floatable range. Therefore, silver in zinc leaching residue is generally recovered using froth flotation.

[0004] The theoretical basis of flotation processes is largely the same: due to the hydrophobic properties of the mineral particles themselves or those acquired through the action of flotation reagents, silver-bearing froth can aggregate at the liquid-gas interface. The silver-bearing concentrate froth on the surface is then separated from the slurry using physical methods. In the hydrometallurgical industry, the main process flow for silver flotation in zinc leaching residue generally consists of roughing, cleaning, and scavenging. However, the process varies depending on the raw materials used in each smelter. The flotation process used in this application involves two roughing stages, three cleaning stages, and three scavenging stages, ultimately yielding a silver concentrate with a silver content of over 3000 g / t.

[0005] In the hydrometallurgical industry, the flotation yield of silver in the froth flotation process is 70-79%, with the rougher yield reaching 65-70%, and the first rougher yield reaching 60-65%. Therefore, the first rougher flotation process is crucial. However, as the composition of raw materials becomes increasingly complex and the silver content rises, the overall rougher yield drops below 65%, with the first rougher yield falling below 60%. Therefore, further improving the first rougher yield is essential to increasing the silver flotation yield in the froth flotation process. Summary of the Invention

[0006] The technical problem this invention aims to solve is that, due to increased production in current systems leading to increased flotation slag volume and higher silver content in raw materials, the existing flotation process no longer meets production demands. This invention provides a method to improve the silver recovery rate in zinc leaching slag during roughing. This invention improves roughing capacity by replacing the single-row roughing flotation with a double-row parallel flotation. Simultaneously, it rapidly recovers qualified silver concentrate from the roughing cells, reducing useless circulation of the roughing concentrate within the system, lowering the amount of silver metal entering the cleaning process, thereby reducing the cleaning load and increasing cleaning capacity and silver concentrate yield.

[0007] To solve the above problems, the technical solution adopted by the present invention is as follows: This invention provides a method for improving the recovery rate of rough silver in zinc leaching residue, the method comprising the following steps: a. The zinc leaching residue is fed into the original ore thickener for processing, and the processed residue is used to obtain ore slurry; b. Pump the slurry obtained in step a into the original ore tank, add heavy calcium carbonate powder to adjust the pH value of the slurry in the tank from 1.5-2.5 to 4.5-5.0; c. Pump the slurry obtained after adjustment in step b to the lifting tank, mixing tank and separating tank for treatment in sequence, and export the raw ore from the separating tank. d. Distribute the raw ore exported in step c into two columns of roughing flotation cells. Each column of roughing flotation cells consists of three flotation cells connected in series. Add reagents to pulp the ore and then perform flotation treatment with butylamine black reagent (the reagents are added to the roughing flotation cell). After treatment, concentrate froth is obtained. e. Take samples of the concentrate foam obtained in step d for silver content analysis. The silver content in the concentrate foam is >3000g / t, which meets the silver concentrate grade requirements. Then, transport it to the concentrate tank. When the silver content in the obtained concentrate froth is <3000g / t, the concentrate froth after roughing flotation is sent through a pipeline to three series-connected cleaning flotation cells for flotation treatment. In the cleaning head cell, butylamine black reagent after reagent pulping is added at a rate of 500-1000ml / min. f. The concentrate froth after flotation in three series-connected secondary flotation cells enters the last tertiary flotation cell for further flotation treatment. After secondary flotation, silver concentrate is obtained and enters the concentrate cell. The slurry in the concentrate cell is subjected to liquid-solid separation by pressure filtration. The liquid is returned to the system, and the resulting filter residue is the silver concentrate product.

[0008] According to the above method for improving the recovery rate of silver in the roughing stage of zinc leaching residue, the density of the slurry obtained in step a is 1.45–1.65 g / cm³. 3 .

[0009] According to the above method for improving the recovery rate of silver in the roughing process of zinc leaching residue, the silver content in the slurry obtained in step a is 300-600 g / t.

[0010] According to the above method for improving the recovery rate of silver in the roughing process of zinc leaching residue, the slurry obtained in step c is sequentially pumped to the booster tank, mixing tank, and separating tank for processing, with the flow rate controlled at 35-55 m³ / h. 3 / h.

[0011] According to the above method for improving the recovery rate of rough silver in zinc leaching residue, the butylamine black powder after pulping in step d is made from 5m 3 The product is prepared by mixing 120 kg of butylamine black powder with production water and slurrying for 30 minutes; the amount of butylamine black powder added after slurrying is 2000-8000 mL / min.

[0012] According to the above method for improving the recovery rate of rough silver in zinc leaching residue, the butylamine black powder after pulping in step e is made from 5m 3 It is produced by mixing water with 120 kg of butylamine black powder and slurrying for 30 minutes.

[0013] The positive and beneficial effects of this invention are: 1. In response to the increasingly complex raw materials and the inability of existing equipment to meet production needs, the technical solution of this invention changes the single-process production of the roughing stage to a dual-process production. The amount of slurry entering the two roughing stages is controlled according to the difference in silver content and processing capacity of the raw materials, thereby improving the overall flotation capacity of the roughing stage and extending the flotation time of the roughing stage from (0.3~0.48)h to (0.6~0.94)h, reducing the impact of raw material fluctuations on flotation.

[0014] 2. After the technical solution of the present invention is improved, the silver content of the froth in the No. 1 coarse flotation cell is higher than 3000g / t, which meets the silver concentrate grade index of ≥2800g / t. The direction of the concentrate froth in the No. 1 coarse flotation cell is changed from entering the No. 2 fine flotation cell to directly entering the concentrate cell, so as to realize the rapid recovery of silver in the coarse part, that is, to reduce the impact of raw material fluctuations on flotation and meet the system's production increase requirements.

[0015] 3. This invention provides corresponding adjustment measures under different raw material silver content conditions, which improves the silver recovery rate in roughing while increasing the silver metal output.

[0016] To improve system processing capacity, this invention makes the following two key improvements based on differences in silver content and throughput of raw materials: ① The single-process production of the roughing stage is changed to a dual-process production, i.e., a new roughing flotation cell is added and connected in parallel with the existing roughing cell. The amount of slurry entering the two roughing cells is controlled according to the differences in silver content and throughput of the raw materials, thus diverting the raw ore slurry, improving the overall flotation capacity of the roughing stage, and reducing the impact of raw material fluctuations on flotation. ② The direction of the concentrate froth in the roughing stage #1 flotation is changed. The froth scraped from the three roughing cells is mixed and then enters the cleaning stage flotation cell. After the roughing stage modification, the silver content of the concentrate froth in the roughing stage #1 cell is above 3000 g / t. The concentrate froth in the roughing stage #1 cell is changed from entering the cleaning stage flotation cell to directly entering the concentrate cell. The silver content of the froth in the other two cells is below 3000 g / t, so it enters the cleaning stage flotation cell for flotation treatment, realizing rapid silver recovery in the roughing process, thereby increasing the roughing yield to over 70%. Detailed implementation method: The present invention will be further illustrated below with reference to the embodiments, but this does not limit the scope of protection of the technical solution of the present invention.

[0017] Example 1: The present invention provides a method for improving the recovery rate of rough silver in zinc leaching residue, the detailed steps of which are as follows: a. The roasted ore (containing 170 g / t of silver) is fed into a thickener in the raw ore bin for processing, resulting in a density of 1.50–1.55 g / cm³. 3 The slurry, after testing, contained 558 g / t of silver. b. Pump the slurry obtained in step a into the original ore tank, add heavy calcium carbonate powder to adjust the pH value of the slurry in the tank to 5.0; c. The slurry obtained after adjustment in step b is sequentially pumped to the booster tank, mixing tank, and separating tank for treatment, controlling the flow rate of the raw ore to 50 m³ / s. 3 / h, after passing through the separator, the raw ore is discharged from the separating tank; d. Take 2 / 5 of the ore slurry from step c and send it into the new roughing flotation cell (the new roughing flotation cell consists of three flotation cells connected in series). Take 3 / 5 of the ore slurry and send it into the old roughing flotation cell (the old roughing flotation cell consists of three flotation cells connected in series). Add reagent to the booster at a rate of 1500 mL / min, add reagent to the mixing cell at a rate of 4500 mL / min, and add reagent to cell #1 of both the new roughing flotation cell and the old roughing flotation cell at a rate of 500 mL / min. After adding the reagent, perform flotation treatment to obtain concentrate froth. The black powder mentioned is butylamine black powder after pulping, and the butylamine black powder after pulping is made from 5m 3 It is produced by mixing water with 120 kg of butylamine black powder and slurrying for 30 minutes; e. Take samples of the concentrate froth scraped from cell #1 after flotation treatment in the new and old rough flotation cells in step d and test for silver content. The silver content is 4978g / t and 4361g / t respectively. The concentrate froth is directly transported to the concentrate cell through pipeline. Samples of the concentrate froth scraped from the new and old coarse flotation cells #2 and #3 were taken for testing, and the silver content was 1521 g / t and 1416 g / t, respectively. The froth was then transported via pipeline to the head cells of three series-connected clean flotation cells for further flotation. Butylamine black reagent (made from 5m³ of slurry-processed reagent) was added to the head cells at a rate of 700 ml / min. 3 (It is produced by mixing water with 120 kg of butylamine black powder and slurrying for 30 minutes); the silver content of the new and old coarse tailings is 93 g / t and 100 g / t, respectively, with yields of 83.33% and 82.08%, respectively. f. After flotation in three series-connected clean flotation cells, a concentrate froth containing 2891 g / t of silver is produced. This concentrate froth is then piped into the last clean flotation cell for further flotation. After clean flotation, a concentrate froth containing 4561 g / t of silver is obtained. This concentrate froth is then piped to the concentrate cell, and the concentrate froth is pumped to the filter press to obtain silver concentrate.

[0018] Example 2: The present invention provides a method for improving the recovery rate of rough silver in zinc leaching residue, the detailed steps of which are as follows: a. The roasted ore (containing 195 g / t of silver) is fed into a thickener in the raw ore bin for processing, resulting in a density of 1.55–1.60 g / cm³. 3 The slurry, after testing, contained 586 g / t of silver. b. Pump the slurry obtained in step a into the original ore tank, add heavy calcium carbonate powder to adjust the pH value of the slurry in the tank to 5.0; c. The slurry obtained after adjustment in step b is sequentially pumped to the booster tank, mixing tank, and separating tank for treatment, controlling the flow rate of the raw ore to 50 m³ / s. 3 / h, after passing through the separator, the raw ore is discharged from the separating tank; d. Half of the ore slurry from step c is transferred to the new roughing flotation cell (which consists of three flotation cells connected in series), and the remaining half of the ore slurry is transferred to the old roughing flotation cell (which consists of three flotation cells connected in series). Add reagent to the booster at a rate of 1800 mL / min, to the mixing cell at a rate of 5000 mL / min, and to cell #1 of both the new and old roughing flotation cells at a rate of 800 mL / min. After adding the reagent, flotation is performed to obtain concentrate froth. The black powder mentioned is butylamine black powder after pulping, and the butylamine black powder after pulping is made from 5m 3 It is produced by mixing water with 120 kg of butylamine black powder and slurrying for 30 minutes; e. Take samples of the concentrate froth scraped from cell #1 after flotation treatment in the new and old rough flotation cells in step d and test for silver content. The silver content is 5763g / t and 5221g / t respectively. The concentrate froth is directly transported to the concentrate cell through pipeline. Samples of the concentrate froth scraped from the new and old coarse flotation cells #2 and #3 were taken for testing, and the silver content was 1671 g / t and 1553 g / t, respectively. The froth was then transported via pipeline to the head cells of three series-connected clean flotation cells for further flotation. Butylamine black reagent (made from 5m³ of slurry-processed reagent) was added to the head cells at a rate of 700 ml / min. 3 (It is produced by mixing water with 120 kg of butylamine black powder and slurrying for 30 minutes); the silver content of the new and old coarse tailings is 89 g / t and 103 g / t, respectively, with yields of 84.05% and 81.37%, respectively. f. After flotation in three series-connected clean flotation cells, a concentrate froth containing 3118 g / t of silver is produced. This concentrate froth is then piped into the last clean flotation cell for further flotation. After clean flotation, a concentrate froth containing 5311 g / t of silver is obtained. This concentrate froth is then piped to the concentrate cell, and the concentrate froth is pumped to the filter press to obtain silver concentrate.

Claims

1. A method of improving the recovery of silver in a roughing stage from zinc leach residue, characterized by, The method comprises the following steps: a. introducing zinc leaching residue into a raw ore tank thickener for treatment, and obtaining ore slurry after treatment; b. pumping the ore slurry obtained in step a into a raw ore tank, and adding heavy calcium powder to adjust the pH value of the ore slurry in the tank from 1.5-2.5 to 4.5-5.0; c. sequentially pumping the ore slurry obtained after adjustment in step b into a lifting tank, a mixing tank and a liquid separation tank for treatment, and leading raw ore out of the liquid separation tank; d. distributing the raw ore led out in step c into two columns of rough-first flotation tanks, each column of rough-first flotation tank being formed by three flotation tanks connected in series; adding medicament slurry after butylamine black medicine to perform flotation treatment, and obtaining concentrate froth after treatment; e. sampling and testing the silver content of the concentrate froth obtained in step d, and when the silver content in the concentrate froth is >3000g / t, the concentrate froth reaches the silver concentrate grade requirement, and is conveyed to a concentrate tank; when the silver content in the obtained concentrate froth is <3000g / t, the concentrate froth after rough-first flotation treatment is sent to three series of second flotation tanks through a pipeline for flotation treatment, and medicament slurry after butylamine black medicine is added in the second head tank at an addition amount of 500-1000ml / min; f. the concentrate froth after flotation in the three series of second flotation tanks is further subjected to flotation treatment in the last third flotation tank, and silver concentrate is obtained after third flotation, and is conveyed to a concentrate tank; the ore slurry in the concentrate tank is subjected to liquid-solid separation through pressure filtration, the liquid is returned to the system, and the obtained pressure filtration residue is silver concentrate product.

2. The method of enhancing the recovery of silver during roughing of zinc leach residue according to claim 1, characterized in that: The density of the slurry obtained in step a is 1.45 to 1.65 g / cm 3 .

3. The method of enhancing the recovery of silver during roughing of zinc leach residue according to claim 1, characterized in that: The silver content in the ore slurry obtained in step a is 300-600g / t.

4. The method for improving the recovery of silver in roughing according to claim 1, characterized in that: The slurry obtained in step c is pumped into the lifting tank, mixing tank and liquid separation tank in sequence, and the flow rate is controlled at 35-55 m 3 / h.

5. The method of enhancing the recovery of silver during roughing of zinc leach residue according to claim 1, characterized in that: The slurry of step d is prepared by mixing 5 m 3 Water is produced by mixing 120 kg of the slurry of step d for 30 minutes; the slurry is added at a rate of 2000-8000 mL / min.

6. The method of enhancing the recovery of silver during rougher flotation according to claim 1, wherein: The slurry of step e is made by mixing 5 m 3 Water is produced by mixing 120 kg of butylamine cyanide with 30 minutes of slurry.