WO2024255007A1 - Method for extracting silver from complex lead bullion - Google Patents

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

The invention relates to a method for extracting silver from complex crude lead, belonging to the technical field of nonferrous metal metallurgy, and specifically to the technical field of a method for extracting silver from complex crude lead.

Background Art

In modern lead metallurgy, lead concentrate is directly smelted to obtain crude lead, and precious metals such as silver are enriched in crude lead. Valuable metals are recovered during the crude lead refining process. Depending on the crude lead refining method, silver can be extracted during crude lead pyrorefining and electrolytic refining.

In the pyrometallurgical refining of crude lead, six processes, namely, smelting to remove copper, adding sulfur to remove copper, adding alkali to remove tin, arsenic and antimony, adding zinc to remove silver, removing zinc and removing bismuth, finally obtain refined lead, and silver is enriched in the silver-zinc shell. The silver-zinc shell contains 6-11% silver, 25-30% zinc and 60-70% lead. The introduction of impurity zinc by adding zinc to extract silver increases the subsequent silver recovery cycle, and the zinc consumption will increase the smelting cost during industrial production. At present, the treatment of silver-zinc shell is mainly "melting-distillation-ash blowing", "acidic oxygen pressure leaching method" and "melting-electrolysis". The "melting-distillation-ash blowing" method is to first melt the silver-zinc shell that has been squeezed to remove excess lead under the cover of the salt layer, and then distill at low pressure and low temperature to remove zinc, and produce gold-silver alloy through oxidation ash blowing. The "acidic oxygen pressure leaching method" for silver-zinc shell treatment process first crushes the silver-zinc shell, ball-mills and sieves it for pretreatment, then adds sulfuric acid solution and oxidant to leach it, treats the leachate and leaching residue, and recovers valuable metallic silver. The "melting-electrolysis" treatment process for silver-zinc shell first uses the melting method to remove most of the lead in the silver-zinc shell. The high-silver zinc shell is crushed and then zinc is removed by alkaline method, then melted into anode plates for electrolysis. The electrolytic anode mud is removed copper by aminosulfonic acid and then saltpeter is added to smelt to produce crude silver. The above-mentioned silver-zinc shell treatment process for recovering silver has problems such as complex process flow, long production cycle, high energy consumption, large metal backlog, and serious environmental pollution.

In electrolytic refining, crude lead is initially refined by pyrometallurgy to remove copper and tin. When the anode copper is high, the anode mud will become hard and dense, which will hinder the dissolution of lead. Tin and lead have similar potentials and will dissolve together with lead and precipitate at the cathode, so copper and tin need to be removed. The crude lead with copper and tin removed is cast into anode plates, which are electrolyzed in electrolyte to obtain cathode lead and anode mud. The cathode lead is cast into lead ingots. The precious metal silver is enriched in the anode mud. The recovery of silver needs to be accompanied by the entire lead refining process and finally recovered from the lead anode mud. The electrolytic refining time of crude lead is about one week, which makes the precious metal recovery cycle long and also produces a large amount of waste acid. At present, the main methods for recovering silver from lead anode mud include the "reduction smelting-ash blowing-electrolysis" combined method, the "reduction smelting-leaching" combined method and the "full wet method". The combined method of "reduction smelting-ash blowing-electrolysis" is to reduce and smelt the lead anode mud to obtain precious lead, and then oxidize and ash blow the precious lead to obtain a gold-silver alloy. The gold-silver alloy is refined and then melted into a gold-silver alloy plate for electrolysis to obtain silver. The combined method of "reduction smelting-leaching" is to reduce and smelt the anode mud to obtain precious lead, and then the precious lead is subjected to wet silver extraction, using nitric acid leaching to separate antimony, chloride precipitation of silver-ammonia complexation liquid-hydrazine hydrate reduction extraction of silver, and neutralization and hydrolysis precipitation of bismuth, and finally obtain silver powder, basic bismuth nitrate and copper nitrate solution or sponge copper. The combined method of "reduction smelting-vacuum distillation-electrolysis" is to pre-treat the precious lead obtained by reduction smelting of anode mud with vacuum distillation, vacuum distillation of precious lead to obtain crude silver, and electrolysis of crude silver to obtain refined silver. The wet method of "full wet method" to recover silver from lead anode mud is leaching through strong oxidants. The acid leaching process of lead anode mud includes chloride salt leaching, ferric chloride leaching, chlorination-drying and other methods. The leaching process can be divided into alkaline leaching and acid leaching to obtain leaching residue and leaching liquid. The leaching residue is treated by chlorination and hydrazine hydrate reduction, and then filtered, washed and dried to finally obtain silver powder. The above-mentioned anode mud recovery of silver generally has the problems of high comprehensive processing cost, long precious metal extrusion time, long process, high pollution, poor processing capacity, etc. At present, there is a lack of clean and short-process methods for extracting silver from crude lead.

The patent with the publication number CN87104574 discloses a new technology for pyrometallurgical refining of crude lead involving a method for extracting silver. The crude lead is subjected to smelting-adding sulfur to remove copper, alkaline compressed air and oxygen to remove arsenic, antimony and tin, and then crystallized to remove silver and bismuth to obtain refined lead and silver-rich lead. The silver-rich lead is vacuum distilled to obtain crude silver and refined lead or lead alloy. The crude silver is electrolyzed to obtain electrosilver and anode mud, and gold is recovered from the anode mud. The method designed in this patent requires the addition of a large amount of sulfur, sodium hydroxide and other reagents to remove copper, tin, arsenic and antimony, which increases the smelting cost. In addition, before crystallization to remove silver and bismuth, three steps of smelting-adding sulfur to remove copper, and alkaline compressed air and oxygen to remove arsenic, antimony and tin are required. The impurity silver content in the crude lead is required to be less than 1%, and the bismuth content is required to be between 0.02-0.2%. In recent years, my country's lead ore products have been faced with the characteristics of many types of impurities and high content. The content of silver, bismuth, copper, tin, arsenic and antimony in the crude lead obtained after smelting far exceeds the impurity content of crude lead in the patent with publication number CN87104574. Refining using this method will add more reagents and produce more slag, so the technical solution recorded in the patent application has not been industrialized. At present, my country generally adopts the method of electrolytic refining of crude lead to avoid adding a large amount of reagents to remove impurities. In the electrolytic refining of crude lead, silver must be accompanied by the lead refining process, resulting in the accumulation of precious metal silver and a long cycle. The recovery process of silver by treating anode mud is complicated, which brings many difficulties to the refining of silver and a series of problems such as poor economic benefits.

The present invention adopts the method of condensation-crystallization-volatilization 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 period.

Summary of the invention

In view of the problems and shortcomings of the above-mentioned prior art, the present invention provides a method for extracting silver from complex crude lead. The method has simple process, convenient operation, simple required equipment, mature process, high suitability of raw materials, and safe and controllable process. The present invention is implemented by the following technical solutions.

A method for extracting silver from complex crude lead, which adopts condensation-crystallization-volatilization. The complex crude lead is mainly used to remove copper through condensation, and other impurities such as tin, arsenic, antimony, etc. are also partially removed to obtain low-copper lead and copper scum; the low-copper lead is mainly enriched with 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 lead refining. The specific steps include:

Step 1, condensing the complex crude lead to obtain copper scum and low-copper lead, wherein the 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 scum, which are removed by scooping out the scum, and low-copper lead is obtained under the scum;

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, volatilizing the high-silver lead obtained in step 2 to obtain crude silver and crude lead;

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

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%, and the sum of the above metal contents is 100%.

In the step 1, the condensation process is to first heat up to 500-950°C, then cool down to 330-450°C at a cooling rate of 2-10°C/min for condensation for 1-5h, and 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.

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.

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.

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).

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

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

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 being combined, the impurity content requirements in electrolytic refining are met.

In the above step 2, the direct recovery rate of silver in the high-silver lead is greater than 92%.

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

The silver and bismuth contents in the low-silver lead in the above step 2 are 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%.

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

Involved in CN113999992A.

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

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

The recovery rate of the above lead is above 99.95%.

The beneficial effects of the present invention are:

(1) The present invention adopts the condensation method to replace the smelting copper removal and sulfur addition copper removal, has no additives, has small slag volume, short process and low smelting cost.

(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, thereby shortening the silver production cycle and achieving a high direct silver recovery rate.

(3) The raw materials selected in the present invention have high adaptability and can be used for various complex crude lead and can efficiently extract silver.

(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%.

(5) The crude lead obtained by volatilization in the present invention can be combined with low-silver lead to meet the needs of pyrometallurgy and electrolysis. The present invention has obvious economic benefits and can be applied industrially.

BRIEF DESCRIPTION OF THE DRAWINGS

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

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 a complex crude lead raw material; and (b) is a crude silver product.

Implementation

The present invention will be further described below in conjunction with the accompanying drawings and specific implementation methods.

Example 1

As shown in FIG1 , the method for extracting silver from complex crude lead adopts condensation-crystallization-volatilization. The main function of the complex crude lead after condensation is to remove copper, and other impurities such as tin, arsenic, antimony, etc. are also partially removed to obtain low-copper lead and copper scum; the low-copper lead is mainly enriched with 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:

Step 1: 10t of complex crude lead (composition shown in Table 1) is condensed in a condensation pot with a diameter of 1.5m and a depth of 0.7m. The temperature is first raised to 950°C, then cooled to 335°C at a rate of 8°C/min and stirred thoroughly. The condensation is performed for 2.5h to obtain copper slag and low-copper lead (composition shown in Table 1);

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 the crystals are precipitated by natural cooling, and 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, and the operation lasts for 10 hours;

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. Put the high-silver lead into the vacuum furnace, turn on the vacuum pump, and evacuate the pressure in the furnace to below 10Pa. The volatilization temperature is 900°C and the volatilization time is 2h.

Step 4: Add the crude lead (composition see Table 1) obtained in step 3 into the low-silver lead.

The comprehensive energy consumption and economic and technical indicators of this operation are shown in Table 2, and the crude lead raw material sample picture and the actual picture of crude silver product are shown in Figure 2.

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

Table 2 Economic indicators of crude lead refining

It can be seen from Table 2 that the cycle of the whole process of the present invention is 1 day, which is 7 days shorter than the cycle of electrolytic refining to recover silver, and 30-50% shorter than the cycle of traditional lead refining. The direct recovery rate of silver reaches 99.37%, and the recovery rate of lead reaches 99.98%. The present invention has obvious economic benefits and can be industrialized.

Example 2

As shown in FIG1 , the method for extracting silver from complex crude lead adopts condensation-crystallization-volatilization. The main function of the complex crude lead after condensation is to remove copper, and other impurities such as tin, arsenic, antimony, etc. are also partially removed to obtain low-copper lead and copper scum; the low-copper lead is mainly enriched with 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:

Step 1: 10t of complex crude lead (composition shown in Table 3) is condensed in a condensation pot with a diameter of 1.5m and a depth of 0.7m. The temperature is first raised to 850°C, then cooled to 335°C at a rate of 6°C/min, stirred thoroughly, and condensed for 3h to obtain copper slag and low-copper lead (composition shown in Table 3);

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 the crystals are precipitated by natural cooling, and 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 20min, and the discharge time is 30s. The composition of low silver lead and high silver lead is shown in Table 3, and the operation lasts 12 hours;

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. Put the high-silver lead into the vacuum furnace, turn on the vacuum pump, and evacuate the pressure in the furnace to below 10Pa. The volatilization temperature is 850°C and the volatilization time is 3h.

Step 4: Add the crude lead (composition see Table 3) obtained in step 3 into the low-silver lead.

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

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

Table 4 Economic indicators of crude lead refining

It can be seen from Table 4 that the cycle of the whole process of the present invention is 1 day, which is 7 days shorter than the cycle of electrolytic refining to recover silver, and 30-50% shorter than the cycle of traditional lead refining. The direct recovery rate of silver reaches 90.83%, and the recovery rate of lead reaches 99.97%. The present invention has obvious economic benefits and can be industrialized.

Example 3

As shown in FIG1 , the method for extracting silver from complex crude lead adopts condensation-crystallization-volatilization. The main function of the complex crude lead after condensation is to remove copper, and other impurities such as tin, arsenic, antimony, etc. are also partially removed to obtain low-copper lead and copper scum; the low-copper lead is mainly enriched with 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:

Step 1: 50t of complex crude lead (composition shown in Table 5) is condensed in a condensation pot with a diameter of 2.8m and a depth of 1m. The temperature is first raised to 950°C, then cooled to 335°C at a rate of 5°C/min, stirred thoroughly, and condensed for 2.5h to obtain copper slag and low-copper lead (composition shown in Table 5);

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 to the high 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 the crystals are precipitated by natural cooling, and 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;

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. Put the high-silver lead into the vacuum furnace, turn on the vacuum pump, and evacuate the pressure in the furnace to below 10Pa. The volatilization temperature is 1050°C and the volatilization time is 2.5h.

Step 4: Add the crude lead (composition see Table 5) obtained in step 3 into the low-silver lead.

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

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

Table 6 Economic indicators of crude lead refining

It can be seen from Table 6 that the cycle of the whole process of the present invention is 2 days, which is 6 days shorter than the cycle of electrolytic refining and silver recovery, and 30-50% shorter than the recovery cycle of traditional refined silver. The direct recovery rate of silver reaches 92.05%, and the recovery rate of lead reaches 99.98%. The present invention has obvious economic benefits and can be industrialized.

Example 4

As shown in FIG1 , the method for extracting silver from complex crude lead adopts condensation-crystallization-volatilization. The main function of the complex crude lead after condensation is to remove copper, and other impurities such as tin, arsenic, antimony, etc. are also partially removed to obtain low-copper lead and copper scum; the low-copper lead is mainly enriched with 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:

Step 1: 50t of complex crude lead (composition shown in Table 7) is condensed in a condensation pot with a diameter of 2.8m and a depth of 1m. The temperature is first raised to 580°C, then cooled to 345°C at a rate of 5°C/min, stirred thoroughly, and condensed for 3h to obtain copper slag and low-copper lead (composition shown in Table 7);

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 low to the high 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 the crystals are precipitated by natural cooling, and 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;

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. Put the high-silver lead into the vacuum furnace, turn on the vacuum pump, and evacuate the pressure in the furnace to below 10Pa. The volatilization temperature is 1000°C and the volatilization time is 3h.

Step 4: Add the crude lead (composition see Table 7) obtained in step 3 into the low-silver lead.

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

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

Table 8 Economic indicators of crude lead refining

It can be seen from Table 8 that the cycle of the whole process of the present invention is 2 days, which is 6 days shorter than the cycle of electrolytic refining and silver recovery, and 30-50% shorter than the recovery cycle of traditional refined silver. The direct recovery rate of silver reaches 98.14%, and the recovery rate of lead reaches 99.98%. The present invention has obvious economic benefits and can be industrialized.

The specific implementation modes of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above implementation modes, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims (9)

A method for extracting silver from complex crude lead, characterized in that: condensation-crystallization-volatilization is used to efficiently extract silver, and 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. The method for extracting silver from complex crude lead according to claim 1 is characterized in that: 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 method for extracting silver from complex crude lead according to claim 1 is characterized in that the condensation process in step 1 is to first heat the temperature to 500-950°C, and then cool the temperature to 330-450°C at a cooling rate of 2-10°C/min for condensation for 1-5h. The method for extracting silver from complex crude lead according to claim 1 is characterized in that: the crystallization enrichment in step 2 adopts a crystallization enrichment device with a device inclination angle of 5-12°, a rotation speed of 2-10r/min, a temperature gradient of 305-335°C, and a temperature increment greater than 0.1°C. The method for extracting silver from complex crude lead according to claim 4 is characterized in that: the time interval for discharging the high-silver lead in step 2 is 10-50 min/time, the discharging time is 20-80 s, and the processing capacity is 1-30 tons/(unit·day). The method for extracting silver from complex crude lead according to claim 1 is characterized in that: in the step 3, the volatilization adopts a vacuum furnace, the volatilization temperature is 800-1050°C, the volatilization time is 1-4h, and the vacuum degree is 0-10Pa. The method for extracting silver from complex crude lead according to claim 1 is characterized in that the copper slag obtained in step 1 is recovered and processed. The method for extracting silver from complex crude lead according to claim 1 is characterized in that the low-silver lead obtained in step 2 and the crude lead obtained in step 3 are sent to a lead refining process. The method for extracting silver from complex crude lead according to claim 1 is characterized in that the crude silver obtained in step 3 is sent to an electrolysis process to produce refined silver.