Method for extracting silver from complex lead bullion

Abstract

A method for extracting silver from complex lead bullion. The method comprises: extracting silver by means of condensation-crystallization-volatilization, and condensing the complex lead bullion to remove copper and some of other impurities, such as tin, arsenic and antimony, thereby obtaining low-copper lead and copper scum; crystallizing the low-copper lead to mainly enrich silver and bismuth and some of other impurities such as antimony and arsenic, thereby obtaining low-silver lead and high-silver lead; and subjecting the high-silver lead to vacuum volatilization to obtain silver bullion and lead bullion. In the method, silver is extracted by means of condensation-crystallization-volatilization, enriched by means of crystallization, and separated from lead for refining, such that the recovery period of silver is shortened by 30-50% compared with a traditional method, and the energy consumption is reduced by 10-40%.

Description

A complex method for extracting silver from crude lead Technical Field

[0001] The invention relates to a method for extracting silver from complex crude lead, belonging to the technical field of non-ferrous metal metallurgy, and specifically to the technical field of a method for extracting silver from complex crude lead. Background Art

[0002] In modern lead metallurgy, lead concentrate is directly smelted to produce crude lead. Precious metals such as silver are concentrated in the crude lead, and valuable metals are recovered during the crude lead refining process. Depending on the crude lead refining method, silver can be extracted from crude lead during both pyrorefining and electrolytic refining.

[0003] During the pyrometallurgical refining of crude lead, six processes are involved: smelting to remove copper, adding sulfur to remove copper, adding alkali to remove tin, arsenic, and antimony, adding zinc to remove silver, and finally removing zinc and bismuth. The silver-zinc shell contains 6-11% silver, 25-30% zinc, and 60-70% lead. Adding zinc to extract silver introduces zinc impurities, which increases the subsequent silver recovery cycle. Furthermore, in industrial production, the increased zinc consumption increases smelting costs. Currently, the main methods for treating silver-zinc shells are smelting-distillation-ash blowing, acidic oxygen pressure leaching, and smelting-electrolysis. The smelting-distillation-ash blowing method involves smelting the silver-zinc shells, after squeezing out excess lead, under a salt layer. The zinc is then removed by low-pressure, low-temperature distillation. After oxidation and ash blowing, a gold-silver alloy is produced. The "acidic oxygen pressure leaching" process for silver-zinc shells involves crushing the shells, ball-milling, and screening them for pretreatment. Sulfuric acid solution and an oxidant are then added for leaching. The leachate and leaching residue are then processed to recover valuable metallic silver. The "smelting-electrolysis" process for silver-zinc shells involves removing most of the lead from the shells through smelting. The resulting high-silver zinc shells are then crushed, zinc removed using an alkaline method, and then melted into anode plates for electrolysis. The resulting electrolytic anode mud is then treated with aminosulfonic acid to remove copper and saltpeter is added for smelting to produce crude silver. These silver-zinc shell treatment processes for silver recovery suffer from complex process flows, long production cycles, high energy consumption, large metal backlogs, and severe environmental pollution.

[0004] During electrolytic refining, crude lead undergoes initial pyrometallurgical refining to remove copper and tin. High anode copper concentrations can lead to hardening and densification of the anode slime, hindering lead dissolution. Tin, having a similar electrical potential to lead, dissolves along with the lead and precipitates at the cathode, necessitating the removal of copper and tin. The crude lead, after being de-coppered, is then cast into anode plates, which are then electrolyzed in an electrolyte to produce cathode lead and anode slime. This cathode lead is then cast into lead ingots. Precious metal silver accumulates in the anode slime. Silver recovery requires the entire lead refining process and is ultimately recovered from the lead anode slime. Electrolytic refining of crude lead takes approximately one week, prolonging the precious metal recovery cycle and generating significant amounts of waste acid. Currently, the main methods for recovering silver from lead anode slime include a combined reduction smelting-ash blowing-electrolysis process, a combined reduction smelting-leaching process, and a full wet process. The combined "reduction smelting-ash blowing-electrolysis" process reduces and smelts lead anode mud to produce precious lead. The precious lead is then oxidized and ash blown to produce a gold-silver alloy. The gold-silver alloy is refined and then melted into gold-silver alloy plates and electrolyzed to produce silver. The combined "reduction smelting-leaching" process reduces and smelts anode mud to produce precious lead. The precious lead is then subjected to hydrometallurgical silver extraction, using nitric acid leaching to separate antimony, followed by silver precipitation with chloride, ammonia complexation, hydrazine hydrate reduction to extract silver, and neutralization and hydrolysis to precipitate bismuth. The final products are silver powder, bismuth basic nitrate, and copper nitrate solution or sponge copper, respectively. The combined "reduction smelting-vacuum distillation-electrolysis" process pre-treats the precious lead obtained from anode mud reduction smelting with vacuum distillation. Crude silver is then electrolyzed to produce refined silver. The "all-wet" method for recovering silver from lead anode mud involves leaching with strong oxidants. Acidic leaching processes for lead anode mud include chloride salt leaching, ferric chloride leaching, and chlorination-drying distillation. These processes can be categorized as alkaline or acidic, producing a leached residue and a leachate. The leached residue is then treated with chlorination and reduced with hydrazine hydrate, then filtered, washed, and dried to yield silver powder. These methods for recovering silver from anode mud generally suffer from high overall processing costs, prolonged precious metal extrusion times, lengthy processes, significant pollution, and poor processing capacity. Currently, there is a lack of clean, short-term methods for extracting silver from crude lead.

[0005] Patent publication number CN87104574 discloses a new pyrometallurgical refining technology for crude lead, involving a silver extraction process. The crude lead undergoes smelting and sulfur removal, followed by alkaline compressed air and oxygen removal of arsenic, antimony, and tin. Silver and bismuth are then crystallized to produce refined lead and silver-enriched lead. The silver-enriched lead is then vacuum distilled to produce crude silver and refined lead or a lead alloy. The crude silver is then electrolyzed to produce electrosilver and anode mud, from which gold is recovered. This patented method requires the addition of large amounts of sulfur, sodium hydroxide, and other reagents to remove copper, tin, arsenic, and antimony, increasing smelting costs. Furthermore, prior to crystallization, three steps are required: smelting and sulfur removal of copper, followed by alkaline compressed air and oxygen removal of arsenic, antimony, and tin. The crude lead is required to contain less than 1% impurity silver and a bismuth content between 0.02 and 0.2%. In recent years, lead ore in my country has been plagued by a wide variety of impurities and high concentrations. The silver, bismuth, copper, tin, arsenic, and antimony content of the crude lead obtained after smelting far exceeds the impurity content of the crude lead disclosed in Patent Publication No. CN87104574. Using this refining method would require the addition of additional reagents and produce more slag, resulting in the technical solution described in this patent application ultimately failing to achieve industrial application. Currently, electrolytic refining of crude lead is widely used in my country to avoid the addition of large amounts of reagents for impurity removal. During electrolytic refining of crude lead, silver must be present during the lead refining process, resulting in the accumulation of precious silver and a long cycle. Recovering silver through anode mud treatment is a complex process, which presents numerous difficulties in silver refining and results in poor economic returns.

[0006] The present invention adopts the condensation-crystallization-volatilization method to extract silver from complex crude lead in an efficient manner, thereby solving the problems of multiple impurity types and high content in crude lead and long silver recovery cycle. Summary of the Invention

[0007] To address the above-mentioned problems and shortcomings of the prior art, the present invention provides a method for extracting silver from complex crude lead. This method features simple process, convenient operation, simple equipment, mature technology, high raw material suitability, and a safe and controllable process. The present invention is achieved through the following technical solutions.

[0008] A method for extracting silver from complex crude lead adopts condensation-crystallization-volatilization. The complex crude lead is mainly condensed to remove copper, and tin, arsenic, antimony and other impurities are also partially removed to obtain low-copper lead and copper slag; the low-copper lead is mainly enriched in silver and bismuth through continuous crystallization, and antimony, arsenic and other impurities are also partially enriched to obtain low-silver lead and high-silver lead; the high-silver lead is subjected to vacuum volatilization to obtain crude silver and crude lead, and the crude lead is incorporated into the low-silver lead for lead refining. The specific steps include:

[0009] Step 1: Coagulate the complex crude lead to obtain copper slag and low-copper lead. Copper condenses and precipitates and forms high-melting-point compounds with arsenic, antimony, and tin, which float on the lead liquid. These high-melting-point compounds are copper slag, which is removed by slag slag to obtain low-copper lead under the slag.

[0010] Step 2: Crystallize the low-copper lead obtained in step 1 to enrich silver and bismuth to obtain low-silver lead and high-silver lead;

[0011] Step 3, volatilizing the high-silver lead obtained in step 2 to obtain crude silver and crude lead;

[0012] Step 4: Combine the crude lead obtained in step 3 and the low-silver lead obtained in step 2 for refining.

[0013] The complex crude lead in step 1 contains lead, copper, tin, arsenic, antimony, silver, bismuth, zinc, iron, chromium and nickel, wherein the content of lead is 75.5-99.5wt%, copper is 0.06-5.5wt%, tin is 0.01-3.5wt%, arsenic is 0.1-6.5wt%, antimony is 0.1-6.8wt%, silver is 0.02-1.5wt%, bismuth is 0.01-0.6wt%, and nickel, iron, zinc and chromium are all less than 0.08wt%. The sum of the above metal contents is 100%.

[0014] In the step 1, the condensation process is to first heat the temperature to 500-950°C, then cool the temperature to 330-450°C at a cooling rate of 2-10°C / min and condense for 1-5 hours. The condensed copper slag is separated by centrifugation to obtain low-copper lead, which can reduce the slag production rate and improve the metal recovery rate.

[0015] In step 2, the crystallization enrichment adopts a crystallization enrichment device with an inclination angle of 5-12°, a rotation speed of 2-10 r / min, a temperature gradient of 305-335°C, and a temperature increment greater than 0.1°C.

[0016] In the step 2, the time interval for discharging the high silver lead is 10-50 minutes per time, the discharging time is 20-80 seconds, and the processing capacity is 1-30 tons per (unit / day).

[0017] In step 3, the volatilization is carried out in a vacuum furnace with a volatilization temperature of 800-1050° C., a volatilization time of 1-4 hours, a vacuum degree of 0-10 Pa, and a processing capacity of 50 tons / (unit·day).

[0018] The condensation process in step (1) is a process of transformation from liquid phase to solid phase in nonferrous metal metallurgy.

[0019] The copper slag obtained in step 1 is recovered and processed.

[0020] The low-silver lead obtained in step 2 is combined with the crude lead obtained in step 3 and sent to the lead refining process. After the combination, the impurity content requirements in electrolytic refining are met.

[0021] The direct recovery rate of silver in the high-silver lead in the above step 2 is greater than 92%.

[0022] In the above step 2, silver in the high-silver lead is enriched by more than 3 times.

[0023] The silver and bismuth content in the low-silver lead in the above step 2 is lower than the "Lead Ingot" GB / T469-2013 standard, wherein silver is not more than 0.008% and bismuth is not more than 0.06%.

[0024] The crystallization and enrichment device in the above step 2 is an existing crystallization and enrichment device, which is disclosed in application publication number:

[0025] As mentioned in CN113999992A.

[0026] The volatilization process in the above step 3 is carried out in a conventional vacuum furnace.

[0027] In the above step 3, the crude silver contains more than 90% silver, and contains less than 10% copper and tin.

[0028] The recovery rate of the above lead is above 99.95%.

[0029] The beneficial effects of the present invention are:

[0030] (1) The present invention adopts the condensation method to replace the smelting copper removal and sulfur addition copper removal, without additives, with small slag volume, short process and low smelting cost.

[0031] (2) The present invention uses low-copper lead crystallization (physical method) to enrich silver and bismuth, and quickly enriches silver and bismuth in high-silver lead. Silver can be recovered without accompanying the entire lead refining process, shortening the silver production cycle and achieving a high direct silver recovery rate.

[0032] (3) The raw materials selected in the present invention are highly adaptable and can be used to extract silver from various complex crude lead materials with high efficiency.

[0033] (4) The present invention adopts the condensation-crystallization-volatilization method to extract silver. The silver recovery cycle is shortened by 30-50% compared with the traditional method, and the energy consumption is reduced by 10%-40%.

[0034] (5) The crude lead obtained by volatilization in the present invention can be combined with low-silver lead to meet the needs of pyrolysis and electrolysis. The present invention has obvious economic benefits and can be applied industrially. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Fig. 1 is a process flow chart of the present invention;

[0036] Figure 2 is a physical picture of the raw materials and some crude silver products of Example 1 of the present invention, wherein (a) is the complex crude lead raw material; (b) is the crude silver product. Implementation Method

[0037] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Example 1

[0038] As shown in FIG1 , the method for extracting silver from complex crude lead adopts condensation-crystallization-volatilization. The complex crude lead is mainly used to remove copper through condensation, and other impurities such as tin, arsenic, and antimony are also partially removed to obtain low-copper lead and copper slag; the low-copper lead is mainly enriched in silver and bismuth through continuous crystallization, and other impurities such as antimony, arsenic, etc. are also partially enriched to obtain low-silver lead and high-silver lead; the high-silver lead is subjected to vacuum volatilization to obtain crude silver and crude lead, and the crude lead is incorporated into the low-silver lead for refined lead. The specific steps include:

[0039] Step 1: 10 tons of complex crude lead (composition shown in Table 1) was condensed in a condensation pot with a diameter of 1.5 m and a depth of 0.7 m. The temperature was first raised to 950°C, then cooled to 335°C at a rate of 8°C / min with thorough stirring, and condensed for 2.5 hours to obtain copper slag and low-copper lead (composition shown in Table 1).

[0040] Step 2: The low-copper lead obtained in step 1 is crystallized to enrich silver to obtain low-silver lead and high-silver lead; the crystallization enrichment device is 3m long, 0.52m wide, and 0.31m deep; the device slope is adjusted to 12°, the rotation speed is 9r / min, the temperature gradient is 305℃-335℃, and the temperature gradient increases from the low point to the high point of the crystallization enrichment device as follows: 305℃, 312℃, 321℃, 325℃, 331℃, 333℃; the low-copper lead melt is placed in the crystallization enrichment device, and when the melt covers the screw shaft, the liquid inlet flow rate is slowed down, and crystals are precipitated by natural cooling. The crystals are transported by the spiral to high-temperature melting and purification to obtain low-silver lead, and the molten liquid is refluxed to the low-temperature section for further crystallization. After a period of time, the lead content in the low-temperature section decreases, and the silver, bismuth, arsenic, and antimony content increases to obtain high-silver lead. The high-silver lead discharge time interval is 32min, and the discharge time is 42s. The composition of low-silver lead and high-silver lead is shown in Table 1. The operation lasts 10 hours.

[0041] Step 3: Vacuum volatilize the high-silver lead obtained in step 2 to obtain crude silver and crude lead. The vacuum volatilization device is a vacuum furnace with a production capacity of 50t / furnace. The high-silver lead is placed in the vacuum furnace, and the vacuum pump is turned on. The pressure in the furnace is pumped to below 10Pa, the volatilization temperature is 900°C, and the volatilization time is 2h.

[0042] Step 4: The crude lead obtained in step 3 (composition see Table 1) is added to the low-silver lead.

[0043] The comprehensive energy consumption and economic and technical indicators of this operation are shown in Table 2, and the crude lead raw material sample and crude silver product physical pictures are shown in Figure 2.

[0044] Table 1 Chemical composition of complex crude lead raw materials and products

[0045]

[0046] Table 2 Economic indicators of crude lead refining

[0047]

[0048] Table 2 shows that the full process cycle of the present invention is one day, which is seven days shorter than the cycle for silver recovery through electrolytic refining and 30-50% shorter than the cycle for traditional lead refining. The direct recovery rate for silver reaches 99.37%, and the recovery rate for lead reaches 99.98%. This invention has significant economic benefits and can be industrially applied. Example 2

[0049] As shown in FIG1 , the method for extracting silver from complex crude lead adopts condensation-crystallization-volatilization. The complex crude lead is mainly used to remove copper through condensation, and other impurities such as tin, arsenic, and antimony are also partially removed to obtain low-copper lead and copper slag; the low-copper lead is mainly enriched in silver and bismuth through continuous crystallization, and other impurities such as antimony, arsenic, etc. are also partially enriched to obtain low-silver lead and high-silver lead; the high-silver lead is subjected to vacuum volatilization to obtain crude silver and crude lead, and the crude lead is incorporated into the low-silver lead for refined lead. The specific steps include:

[0050] Step 1: 10 tons of complex crude lead (composition shown in Table 3) was condensed in a condensation pot with a diameter of 1.5 m and a depth of 0.7 m. The temperature was first raised to 850°C, then cooled to 335°C at a rate of 6°C / min with thorough stirring, and condensed for 3 hours to obtain copper slag and low-copper lead (composition shown in Table 3);

[0051] Step 2: The low-copper lead obtained in step 1 is crystallized to enrich silver to obtain low-silver lead and high-silver lead; the crystallization enrichment device is 3m long, 0.52m wide, and 0.31m deep; the device slope is adjusted to 10°, the rotation speed is 6r / min, the temperature gradient is 305℃-335℃, and the temperature gradient increases from the low point to the high point of the crystallization enrichment device as follows: 305℃, 310℃, 318℃, 326℃, 330℃, 333℃; the low-copper lead melt is placed in the crystallization enrichment device, and when the melt covers the screw shaft, the liquid inlet flow rate is slowed down, and crystals are precipitated by natural cooling. The crystals are transported by the spiral to high-temperature melting and purification to obtain low-silver lead, and the molten liquid is refluxed to the low-temperature section for further crystallization. After a period of time, the lead content in the low-temperature section decreases, and the silver, bismuth, arsenic, and antimony content increases to obtain high-silver lead. The high-silver lead is discharged at a time interval of 20min and the discharge time is 30s. The composition of low-silver lead and high-silver lead is shown in Table 3. The operation lasts 12 hours.

[0052] Step 3: Vacuum volatilize the high-silver lead obtained in step 2 to obtain crude silver and crude lead. The vacuum volatilization device is a vacuum furnace with a production capacity of 50t / furnace. The high-silver lead is placed in the vacuum furnace, the vacuum pump is turned on, the pressure in the furnace is pumped to below 10Pa, the volatilization temperature is 850°C, and the volatilization time is 3h.

[0053] Step 4: The crude lead obtained in step 3 (composition see Table 3) is incorporated into the low-silver lead.

[0054] The comprehensive energy consumption and economic and technical indicators of this operation are shown in Table 4.

[0055] Table 3 Chemical composition of complex crude lead raw materials and products

[0056]

[0057] Table 4 Economic indicators of crude lead refining

[0058]

[0059] Table 4 shows that the full process cycle of the present invention is one day, which is seven days shorter than the cycle for silver recovery through electrolytic refining and 30-50% shorter than the cycle for traditional lead refining. The direct recovery rate for silver reaches 90.83%, and the recovery rate for lead reaches 99.97%. This invention has significant economic benefits and can be industrially applied. Example 3

[0060] As shown in FIG1 , the method for extracting silver from complex crude lead adopts condensation-crystallization-volatilization. The complex crude lead is mainly used to remove copper through condensation, and other impurities such as tin, arsenic, and antimony are also partially removed to obtain low-copper lead and copper slag; the low-copper lead is mainly enriched in silver and bismuth through continuous crystallization, and other impurities such as antimony, arsenic, etc. are also partially enriched to obtain low-silver lead and high-silver lead; the high-silver lead is subjected to vacuum volatilization to obtain crude silver and crude lead, and the crude lead is incorporated into the low-silver lead for refined lead. The specific steps include:

[0061] Step 1: 50 tons of complex crude lead (composition shown in Table 5) was condensed in a condensation pot with a diameter of 2.8 m and a depth of 1 m. The temperature was first raised to 950°C, then cooled to 335°C at a rate of 5°C / min with thorough stirring, and condensed for 2.5 hours to obtain copper slag and low-copper lead (composition shown in Table 5);

[0062] Step 2: The low-copper lead obtained in step 1 is crystallized to enrich silver to obtain low-silver lead and high-silver lead; the crystallization enrichment device is 4m long, 0.61m wide, and 0.42m deep; the device slope is adjusted to 7°, the rotation speed is 4r / min, the temperature gradient is 305℃-335℃, and the temperature gradient increases from the low point to the high point of the crystallization enrichment device as follows: 305℃, 317℃, 321℃, 326℃, 331℃, 333℃; the low-copper lead melt is placed in the crystallization enrichment device, and when the melt covers the screw shaft, the liquid inlet flow rate is slowed down, and crystals are precipitated by natural cooling. The crystals are transported by the spiral to high-temperature melting and purification to obtain low-silver lead, and the molten liquid is refluxed to the low-temperature section for further crystallization. After a period of time, the lead content in the low-temperature section decreases, and the silver, bismuth, arsenic, and antimony content increases to obtain high-silver lead. The high-silver lead discharge time interval is 35min, and the discharge time is 30s. The quality and composition of low-silver lead and high-silver lead are shown in Table 5. The operation lasts 28 hours.

[0063] Step 3: Vacuum volatilize the high-silver lead obtained in step 2 to obtain crude silver and crude lead. The vacuum volatilization device is a vacuum furnace with a production capacity of 50t / furnace. The high-silver lead is placed in the vacuum furnace, the vacuum pump is turned on, the pressure in the furnace is evacuated to below 10Pa, the volatilization temperature is 1050°C, and the volatilization time is 2.5h.

[0064] Step 4: The crude lead obtained in step 3 (composition see Table 5) is added to the low-silver lead.

[0065] The comprehensive energy consumption and economic and technical indicators of this operation are shown in Table 6.

[0066] Table 5 Chemical composition of complex crude lead raw materials and products

[0067]

[0068] Table 6 Economic indicators of crude lead refining

[0069]

[0070] Table 6 shows that the full process cycle of the present invention is 2 days, which is 6 days shorter than the silver recovery cycle of electrolytic refining and 30-50% shorter than the recovery cycle of traditional silver refining. The direct recovery rate of silver reaches 92.05%, and the recovery rate of lead reaches 99.98%. The present invention has significant economic benefits and can be applied industrially. Example 4

[0071] As shown in FIG1 , the method for extracting silver from complex crude lead adopts condensation-crystallization-volatilization. The complex crude lead is mainly used to remove copper through condensation, and other impurities such as tin, arsenic, and antimony are also partially removed to obtain low-copper lead and copper slag; the low-copper lead is mainly enriched in silver and bismuth through continuous crystallization, and other impurities such as antimony, arsenic, etc. are also partially enriched to obtain low-silver lead and high-silver lead; the high-silver lead is subjected to vacuum volatilization to obtain crude silver and crude lead, and the crude lead is incorporated into the low-silver lead for refined lead. The specific steps include:

[0072] Step 1: 50 tons of complex crude lead (composition shown in Table 7) was condensed in a condensation pot with a diameter of 2.8 m and a depth of 1 m. The temperature was first raised to 580°C, then cooled to 345°C at a rate of 5°C / min with thorough stirring, and condensed for 3 hours to obtain copper slag and low-copper lead (composition shown in Table 7);

[0073] Step 2: The low-copper lead obtained in step 1 is crystallized to enrich silver to obtain low-silver lead and high-silver lead; the crystallization enrichment device is 4m long, 0.61m wide, and 0.42m deep; the device slope is adjusted to 10°, the rotation speed is 9r / min, the temperature gradient is 305℃-335℃, and the temperature gradient increases from the bottom to the top of the crystallization enrichment device as follows: 305℃, 310℃, 318℃, 326℃, 331℃, 333℃; the low-copper lead melt is placed in the crystallization enrichment device, and when the melt covers the screw shaft, the liquid inlet flow rate is slowed down, and crystals are precipitated by natural cooling. The crystals are transported by the spiral to high-temperature melting and purification to obtain low-silver lead, and the molten liquid is refluxed to the low-temperature section for further crystallization. After a period of time, the lead content in the low-temperature section decreases, and the silver, bismuth, arsenic, and antimony content increases to obtain high-silver lead. The high-silver lead discharge time interval is 50min, and the discharge time is 75s. The quality and composition of low-silver lead and high-silver lead are shown in Table 7. The operation lasts 26 hours.

[0074] Step 3: Vacuum volatilize the high-silver lead obtained in step 2 to obtain crude silver and crude lead. The vacuum volatilization device is a vacuum furnace with a production capacity of 50t / furnace. The high-silver lead is placed in the vacuum furnace, the vacuum pump is turned on, the pressure in the furnace is pumped to below 10Pa, the volatilization temperature is 1000°C, and the volatilization time is 3h.

[0075] Step 4: The crude lead obtained in step 3 (composition see Table 7) is incorporated into the low-silver lead.

[0076] The comprehensive energy consumption and economic and technical indicators of this operation are shown in Table 8.

[0077] Table 7 Chemical composition of complex crude lead raw materials and products

[0078]

[0079] Table 8 Economic indicators of crude lead refining

[0080]

[0081] Table 8 shows that the full process cycle of the present invention is 2 days, which is 6 days shorter than the silver recovery cycle of electrolytic refining and 30-50% shorter than the recovery cycle of traditional silver refining. The direct recovery rate of silver reaches 98.14%, and the recovery rate of lead reaches 99.98%. The present invention has significant economic benefits and can be applied industrially.

[0082] The above describes the specific embodiments of the present invention in detail with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in this field without departing from the scope of the present invention.

Claims

1. A complex method for extracting silver from crude lead. Features: The condensation-crystallization-volatilization method is used to efficiently extract silver. The specific steps include: Step 1, condensing the complex crude lead to obtain copper slag and low-copper lead; Step 2, crystallizing the low-copper lead obtained in step 1 to enrich silver and bismuth to obtain low-silver lead and high-silver lead; Step 3: volatilize the high-silver lead obtained in step 2 to obtain crude silver and crude lead.

2. The method for extracting silver from complex crude lead according to claim 1, Features: The complex crude lead in step 1 contains lead, copper, tin, arsenic, antimony, silver, bismuth, zinc, iron, chromium and nickel, wherein the content of lead is 75.5-99.5wt%, copper is 0.06-5.5wt%, tin is 0.01-3.5wt%, arsenic is 0.1-6.5wt%, antimony is 0.1-6.8wt%, silver is 0.02-1.5wt%, bismuth is 0.01-0.6wt%, and nickel, iron, zinc and chromium are all less than 0.08wt%.

3. The method for extracting silver from complex crude lead according to claim 1, Features: In the step 1, the condensation process is to first heat up to 500-950° C., and then cool down to 330-450° C. at a cooling rate of 2-10° C. / min for condensation for 1-5 hours.

4. The method for extracting silver from complex crude lead according to claim 1, Features: In step 2, the crystallization enrichment adopts a crystallization enrichment device with an inclination angle of 5-12°, a rotation speed of 2-10 r / min, a temperature gradient of 305-335°C, and a temperature increment greater than 0.1°C.

5. The method for extracting silver from complex crude lead according to claim 4, Features: In the step 2, the time interval for discharging the high silver lead is 10-50 minutes per time, the duration of discharging is 20-80 seconds, and the processing capacity is 1-30 tons per day.

6. The method for extracting silver from complex crude lead according to claim 1, Features: In step 3, the volatilization is carried out in a vacuum furnace with a volatilization temperature of 800-1050° C., a volatilization time of 1-4 hours, and a vacuum degree of 0-10 Pa.

7. The method for extracting silver from complex crude lead according to claim 1, Features: The copper slag obtained in step 1 is recovered and processed.

8. The method for extracting silver from complex crude lead according to claim 1, Features: The low-silver lead obtained in step 2 and the crude lead obtained in step 3 are sent to a lead refining process.

9. The method for extracting silver from complex crude lead according to claim 1, Features: The crude silver obtained in step 3 is sent to an electrolysis process to produce refined silver.

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