A method and system for recovering valuable metals from white smoke dust.

Abstract

This invention belongs to the field of valuable metal extraction and environmental remediation, specifically relating to a method and system for recovering valuable metals from white smoke dust. The method includes slurrying the white smoke dust, the slurry containing water and sulfuric acid; leaching the white smoke dust slurry, with the leaching temperature being higher when the chlorinated leaching agent contains the recovered liquid than when it does not; performing solid-liquid separation to obtain a leachate and a lead-bismuth-containing leaching residue; chlorinating the lead-bismuth-containing leaching residue to obtain a chlorinated leaching solution, performing solid-liquid separation to obtain a leachate and a lead sulfate-containing leaching residue; neutralizing the chlorinated leaching solution with sodium hydroxide and sodium carbonate, performing solid-liquid separation to obtain a neutralization residue and a neutralization solution containing bismuth oxychloride; and performing sodium salt recovery treatment on the neutralization solution to obtain a recovered solution and sodium sulfate, with the recovered solution being returned as a chlorinated leaching agent. This invention can reduce the production of acidic solutions and improve the purity of lead sulfate and bismuth oxychloride.

Description

Technical Field

[0001] This invention belongs to the field of valuable metal extraction and environmental governance, specifically relating to a method and system for recovering valuable metals from white smoke dust. Background Technology

[0002] The solid waste generated by copper smelting enterprises mainly consists of three types: arsenic filter cake, white smoke dust, and black copper sludge. Among them, white smoke dust is particulate dust collected by the electrostatic precipitator at the end of the side-blown furnace process in the smelting plant, and mainly contains elements such as copper, arsenic, zinc, lead, antimony, bismuth, gold, and silver.

[0003] To save costs, most companies store white dust in order to save on costs. However, they overlook the fact that prolonged storage can easily lead to fires and poses a significant safety hazard. When the amount of white dust is large, in order to reduce the content of valuable elements in the white dust, they directly return it to the smelting system for processing. However, they fail to consider that prolonged storage can deteriorate furnace conditions, shorten its lifespan, affect copper quality, and reduce production capacity. In order to make efficient use of existing resources, it is necessary to separate and extract valuable elements through reasonable processes.

[0004] Currently, there are two main methods for separating and harmlessly extracting valuable elements from white dust: pyrometallurgical treatment and hydrometallurgical treatment. However, pyrometallurgical treatment has high energy consumption, low recovery rate, and produces sulfur dioxide and other gases that severely pollute the environment. Hydrometallurgical treatment mainly involves acid leaching of the white dust to obtain leaching residue containing metals such as bismuth and lead. This leaching residue is then further processed to obtain bismuth-rich slag and lead-rich slag for sale, as well as a large amount of acid-containing liquid. However, the acid-containing liquid has a high acid concentration and contains multiple metals, making its harmless treatment very difficult. Therefore, there is an urgent need in this field for a method to recover valuable metals from white dust that can reduce the production of acid-containing liquids containing multiple metals. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing wet treatment of white dust, which produces a large amount of acid-containing liquid, and to provide a method and system for recovering valuable metals from white dust. This method effectively reduces the amount of acid-containing liquid produced and recovers valuable elements.

[0006] To achieve the above objectives, in a first aspect, the present invention provides a method for recovering valuable metals from white smoke dust, comprising:

[0007] The white smoke dust is mixed with a slurry and slurry is slurried to obtain a white smoke dust slurry. The slurry contains water and sulfuric acid, and the acidity of the white smoke dust slurry is 80 g / L to 100 g / L.

[0008] The white smoke slurry is leached to obtain a leached liquid. When the chlorinated leaching agent does not contain the recovered liquid, the leaching temperature is 80℃~85℃. When the chlorinated leaching agent contains the recovered liquid, the leaching temperature is 90℃~100℃. The leached liquid is then subjected to a first solid-liquid separation to obtain a first leaching solution and a leaching residue containing lead and bismuth.

[0009] The lead-bismuth-containing leaching residue is mixed evenly with the chlorination leaching agent in the chlorination leaching module and then subjected to chlorination leaching to obtain a chlorinated leaching solution. The chlorination leaching agent includes sodium chloride and sulfuric acid. The chlorination leaching agent may or may not contain the recovered solution. The chlorinated leaching solution is then subjected to a second solid-liquid separation to obtain a second leaching solution and a lead sulfate-containing leaching residue.

[0010] The second leachate is mixed evenly with a neutralizing agent and then neutralized to obtain a neutralized liquid. The neutralizing agent includes sodium hydroxide and sodium carbonate. The neutralized liquid is then subjected to a third solid-liquid separation to obtain a neutralized residue and a neutralized liquid containing bismuth oxychloride.

[0011] The neutralized solution is subjected to sodium salt recovery treatment to obtain the recovered solution and sodium sulfate. The recovered solution is then returned to the chlorination leaching module as the chlorination leaching agent.

[0012] In some preferred embodiments, the pulping conditions include a liquid-to-solid ratio of 3 to 5:1 for the white smoke slurry.

[0013] In some preferred embodiments, the chlorination leaching conditions include: the chloride ion concentration of the chlorination leaching agent is 100 g / L to 140 g / L, the acidity is 100 g / L to 140 g / L, and the liquid-to-solid ratio of the chlorination leaching is 4 to 6:1.

[0014] Preferably, the chlorination leaching conditions further include: a leaching temperature of 70℃~90℃ and a leaching time of 2h~6h.

[0015] In some preferred embodiments, the conditions for the neutralization treatment include: the pH of the system after the second leachate and the neutralizing agent are mixed evenly is 4 to 6.

[0016] Preferably, the neutralization treatment conditions also include a neutralization temperature of 70℃~90℃ and a neutralization time of 2h~6h.

[0017] In some preferred embodiments, the sodium salt recovery process includes evaporating and concentrating the neutralized liquid, cooling and crystallizing it, and filtering the crystals to obtain a recovered liquid and sodium sulfate.

[0018] Preferably, the conditions for evaporation and concentration include: adjusting the pH of the neutralized solution to 3-4 and the evaporation and concentration temperature to 95℃-115℃ before evaporation and concentration.

[0019] In a second aspect, the present invention provides a recycling system for the recycling method described in the first aspect, the system comprising: a pulping module having a white dust inlet, a pulping liquid inlet and a white dust slurry outlet, wherein the pulping liquid inlet introduces water and sulfuric acid into the pulping module;

[0020] The leaching module is provided with a white smoke slurry inlet and a leached liquid outlet, wherein the white smoke slurry inlet and the white smoke slurry outlet are connected;

[0021] The first solid-liquid separation module is provided with a leaching liquid inlet, a first leaching liquid outlet and a lead-bismuth-containing leaching residue outlet, wherein the leaching liquid inlet and the leaching liquid outlet are connected.

[0022] A chlorination leaching module is provided with a lead-bismuth-containing leaching residue inlet, a chlorination leaching agent inlet, and a chlorination leaching liquid outlet. The lead-bismuth-containing leaching residue inlet is connected to the lead-bismuth-containing leaching residue outlet. The chlorination leaching agent inlet introduces chlorination leaching agent into the chlorination leaching module. The chlorination leaching agent includes sodium chloride and sulfuric acid. The chlorination leaching agent may or may not contain the recovered liquid.

[0023] The second solid-liquid separation module is provided with a chlorinated leaching liquid inlet, a second leaching liquid outlet and a lead sulfate-containing leaching residue outlet, wherein the chlorinated leaching liquid inlet and the chlorinated leaching liquid outlet are connected.

[0024] The neutralization treatment module is provided with a second leachate inlet, a neutralizing agent inlet, and a neutralized liquid outlet. The second leachate inlet is connected to the second leachate outlet, and the neutralizing agent inlet introduces sodium hydroxide and sodium carbonate into the neutralization treatment module.

[0025] The third solid-liquid separation module is provided with a neutralized liquid inlet, a neutralized liquid outlet and a neutralized residue outlet containing bismuth oxychloride, wherein the neutralized liquid inlet and the neutralized liquid outlet are connected.

[0026] The sodium salt recovery and treatment module recovers sodium salt from the neutralized solution. It is equipped with a neutralized solution inlet, a recovered solution outlet, and a sodium sulfate outlet. The neutralized solution inlet is connected to the neutralized solution outlet, and the recovered solution outlet is connected to the chlorination leaching agent inlet.

[0027] In some preferred embodiments, the sodium salt recovery and processing module includes:

[0028] An evaporation and concentration unit is provided with a neutralized liquid inlet and an evaporated and concentrated liquid outlet;

[0029] A cooling crystallization unit is provided with an inlet for the evaporated and concentrated liquid and an outlet for the cooled and crystallized liquid, wherein the inlet for the evaporated and concentrated liquid is connected to the outlet for the evaporated and concentrated liquid.

[0030] The crystallization filtration unit is provided with a cooling crystallization liquid inlet, a recovery liquid outlet and a sodium sulfate outlet, wherein the cooling crystallization liquid inlet and the cooling crystallization liquid outlet are connected.

[0031] In this invention, white smoke dust is leached under an acidic environment to obtain a lead-bismuth-containing leaching residue. The lead-bismuth-containing leaching residue is then subjected to chlorination leaching to obtain a lead sulfate-containing leaching residue. The chlorinated leaching solution is then neutralized to obtain a neutralized residue and a neutralized solution containing bismuth oxychloride. The neutralized solution is then subjected to sodium salt recovery treatment to obtain a recovered solution with a high acid concentration and sodium sulfate, which is then returned to be used for chlorination leaching. While extracting valuable metals such as lead and bismuth, the recycling of the recovered liquid can reduce the production of acidic solutions and provide acidity for chlorination leaching. The inventors discovered that when the recovered liquid is returned for chlorination leaching, the purity of lead sulfate in the leaching residue containing lead sulfate and the purity of bismuth oxychloride in the neutralized residue containing bismuth oxychloride are limited, and the zinc content in the leaching residue containing lead sulfate and the neutralized residue containing bismuth oxychloride is high. In this invention, when the recovered liquid is returned for chlorination leaching, compared with the leaching temperature of 80°C to 85°C of white smoke slurry without the recovered liquid in the chlorination leaching agent, increasing the leaching temperature to 90°C to 100°C can significantly reduce the zinc content in the leaching residue containing lead sulfate and the neutralized residue containing bismuth oxychloride, and improve the purity of lead sulfate and bismuth oxychloride. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a process flow diagram of the method for recovering valuable metals from white smoke dust according to Embodiment 1 of this application. Detailed Implementation

[0034] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0035] The inventors of this invention discovered that wet treatment of white smoke dust produces a large amount of acidic liquid, which is very difficult to render harmless.

[0036] In this regard, firstly, the present invention provides a method for recovering valuable metals from white smoke dust, comprising:

[0037] The white smoke dust is mixed with a slurry and slurry is slurried to obtain a white smoke dust slurry. The slurry contains water and sulfuric acid, and the acidity of the white smoke dust slurry is 80 g / L to 100 g / L.

[0038] The white smoke slurry is leached to obtain a leached liquid. When the chlorinated leaching agent does not contain the recovered liquid, the leaching temperature is 80℃~85℃. When the chlorinated leaching agent contains the recovered liquid, the leaching temperature is 90℃~100℃. The leached liquid is then subjected to a first solid-liquid separation to obtain a first leaching solution and a leaching residue containing lead and bismuth.

[0039] The lead-bismuth-containing leaching residue is mixed evenly with the chlorination leaching agent in the chlorination leaching module and then subjected to chlorination leaching to obtain a chlorinated leaching solution. The chlorination leaching agent includes sodium chloride and sulfuric acid. The chlorination leaching agent may or may not contain the recovered solution. The chlorinated leaching solution is then subjected to a second solid-liquid separation to obtain a second leaching solution and a lead sulfate-containing leaching residue.

[0040] The second leachate is mixed evenly with a neutralizing agent and then neutralized to obtain a neutralized liquid. The neutralizing agent includes sodium hydroxide and sodium carbonate. The neutralized liquid is then subjected to a third solid-liquid separation to obtain a neutralized residue and a neutralized liquid containing bismuth oxychloride.

[0041] The neutralized solution is subjected to sodium salt recovery treatment to obtain the recovered solution and sodium sulfate. The recovered solution is then returned to the chlorination leaching module as the chlorination leaching agent.

[0042] The present invention discloses a method for recovering valuable metals from white smoke dust. The method involves pulping and leaching the white smoke dust with sulfuric acid, followed by solid-liquid separation to obtain a lead-bismuth-containing leaching residue. This residue is then mixed with sodium chloride and sulfuric acid for chlorination leaching. After solid-liquid separation, a lead sulfate-containing leaching residue and a second leaching solution are obtained. The second leaching solution is neutralized with sodium hydroxide and sodium carbonate. After solid-liquid separation, a neutralization residue and a neutralization solution containing bismuth oxychloride are obtained. The neutralization solution undergoes sodium salt recovery treatment to obtain a recovered liquid and sodium sulfate. The recovered liquid is then returned to the chlorination leaching process as a chlorination leaching agent. The recovered liquid has a high acid concentration. Returning the recovered liquid as a chlorination leaching agent reduces the production of acidic liquid and provides acidity for chlorination leaching. The chlorination leaching, neutralization treatment, and sodium salt recovery treatment simultaneously yield marketable lead sulfate (leaching residue containing lead sulfate), bismuth oxychloride (neutralization residue containing bismuth oxychloride), and sodium sulfate. This allows for the simultaneous recovery of lead and bismuth from white dust and the recovery of sodium salts. The acidity of the white dust slurry of this invention is 80 g / L to 100 g / L, with an acidity not lower than 80 g / L. This provides sufficient acidity for the oxides in the white dust, facilitating the entry of elements such as copper and zinc into the liquid phase and lead and bismuth into the slag phase, thus improving element recovery rates. The acidity is not higher than 100 g / L, firstly to avoid significant corrosion of equipment and pipelines, posing a safety hazard, and secondly to reduce production costs. The inventors of this invention discovered that when the recycled liquid is reused as a chlorination leaching agent, the purity of lead sulfate in the lead sulfate-containing leaching residue used for sale and the purity of bismuth oxychloride in the bismuth oxychloride-containing neutralization residue used for sale are limited. The zinc content in both the lead sulfate-containing leaching residue and the bismuth oxychloride-containing neutralization residue is high. The inventors further discovered that the zinc content in the lead bismuth-containing leaching residue is high, and some of the zinc from the lead bismuth-containing leaching residue enters the recycled liquid. When the recycled liquid is reused as a chlorination leaching agent, it contains zinc, and the white smoke dust also contains zinc. Zinc continuously accumulates in the recycling system, leading to the degradation of the lead sulfate-containing leaching residue. The neutralization residue containing bismuth oxychloride has a high zinc content. The inventors propose that when the recovered liquid is not produced for reuse and the chlorination leaching agent does not contain the recovered liquid, the leaching temperature of the white smoke slurry is 80℃~85℃. When the recovered liquid is produced for reuse and the chlorination leaching agent contains the recovered liquid, the leaching temperature of the white smoke slurry is 90℃~100℃. This can significantly reduce the zinc content of the lead-bismuth-containing leaching residue, significantly reduce the zinc content of the recovered liquid, inhibit the accumulation of zinc in the recovery system, significantly reduce the zinc content of the lead sulfate-containing leaching residue and the neutralization residue containing bismuth oxychloride, and improve the purity of lead sulfate and bismuth oxychloride.When the chlorination leaching agent of this invention does not contain recycled liquid, the leaching temperature of the white smoke slurry is not lower than 80°C, which is more conducive to the full leaching of other metal elements besides lead and bismuth. The leaching temperature is not higher than 85°C, which is more conducive to safety and prevents the reaction from being too violent, causing personal injury and environmental accidents. When the chlorination leaching agent of this invention contains recycled liquid, the leaching temperature of the white smoke slurry is not lower than 90°C, which is more conducive to the full leaching of other metal elements besides lead and bismuth, and prevents more zinc from entering the lead-bismuth-containing leaching residue and entering the recycled liquid. The leaching temperature is not higher than 100°C, which helps to save steam costs. Preferably, the leaching time is 2-3 hours, which is more conducive to the full leaching of other metal elements besides lead and bismuth. Too long a time is inefficient and wasteful of energy.

[0043] In some preferred embodiments, the pulping conditions include a liquid-to-solid ratio of 3 to 5:1 for the white dust slurry. In this preferred embodiment, a liquid-to-solid ratio of not less than 3:1 is more conducive to improving the leaching effect, while a liquid-to-solid ratio of not more than 5:1 is to improve the element leaching rate while meeting the throughput requirements. Preferably, the pulping time is 1 to 2 hours, which is more conducive to the dissolution of solid white dust particles and promotes more complete and thorough pulping.

[0044] In some preferred embodiments, the chlorination leaching conditions include: a chloride ion concentration of 100 g / L to 140 g / L in the chlorination leaching agent, an acidity of 100 g / L to 140 g / L, and a liquid-to-solid ratio of 4 to 6:1. In this preferred embodiment, a chloride ion concentration of not less than 100 g / L facilitates the transformation of bismuth-containing materials from bismuth oxysulfate to bismuth chloride, which is more conducive to subsequent neutralization and transformation. A chloride ion concentration of not more than 140 g / L saves the cost of sodium chloride while achieving the transformation effect. An acidity of not less than 100 g / L provides sufficient sulfate ions in the solution to generate sodium sulfate, which is more conducive to the subsequent extraction of sodium sulfate salt. A liquid-to-solid ratio of not less than 4:1 in the chlorination leaching process will clog the pipes and increase the frequency of manual maintenance. A liquid-to-solid ratio of not more than 6:1 in the chlorination leaching process is conducive to the transformation of bismuth elements; a ratio higher than this results in poor operational efficiency. Preferably, the leaching temperature is 70℃~90℃, and the leaching temperature is not lower than 70℃, which can promote the separation of sulfate and bismuth ions in bismuth oxysulfate, and the separation of sodium ions and chloride ions in sodium chloride, which is more conducive to the combination of bismuth ions and chloride ions, and the combination of sodium ions and sulfate ions. The chlorination leaching time is 2h~6h, which is more conducive to the transformation of bismuth oxysulfate to bismuth chloride, and the formation of sodium sulfate is more conducive to the forward reaction.

[0045] In some preferred embodiments, the neutralization treatment conditions include: the pH of the system after the second leachate and the neutralizing agent are mixed evenly is 4-6. In this preferred embodiment, the pH of the system after the second leachate and the neutralizing agent are mixed evenly is not lower than 4, which enables the conversion of bismuth chloride to bismuth oxychloride, facilitating the recovery and extraction of bismuth. The pH is not higher than 6; if too much neutralizing agent is added, side reactions will occur, affecting the bismuth conversion and generating excessive gas, easily causing overflow and impacting actual production. Preferably, the neutralization temperature is 70℃-90℃. A neutralization temperature not lower than 70℃ promotes the reaction and accelerates the reaction rate. If the temperature is lower than 70℃, the reaction rate is slow, the reaction time is long, and the efficiency is low. If the temperature is higher than 90℃, the reaction is too vigorous, which is not conducive to a sustained and stable reaction rate. The neutralization time is 2h-6h, which maintains both high conversion efficiency and a certain reaction efficiency. Beyond this range, the efficiency remains basically the same, but more energy is wasted.

[0046] In some preferred embodiments, the sodium salt recovery process includes evaporating and concentrating the neutralized liquid, cooling and crystallizing it, and then filtering the crystals to obtain a recovered liquid and sodium sulfate. The sodium sulfate is sold as a finished product. In this preferred embodiment, the evaporation, concentration, cooling, crystallization, and filtration processes enable the recovery of sodium sulfate for external sale. Optimizing the specific process parameters for evaporation, concentration, and crystallization further improves the recovery rate of sodium sulfate.

[0047] Preferably, the evaporation and concentration conditions include: adjusting the pH of the neutralizing solution to 3-4 before evaporation and concentration, and setting the evaporation and concentration temperature to 95℃-115℃. Under this preferred scheme, given that the neutralizing solution contains chloride ions, sodium ions, and sulfate ions, adjusting the pH of the neutralizing solution to be no lower than 3 and no higher than 4 is more conducive to the precipitation of sodium sulfate solid for sale during the cooling crystallization process. The evaporation and concentration temperature is no lower than 95℃ and no higher than 115℃. Since sodium sulfate and sodium chloride have different solubilities, the solubility of sodium sulfate decreases with increasing temperature, while the solubility of sodium chloride increases. Therefore, as the temperature increases, the precipitation of sodium chloride is inhibited, while the precipitation of sodium sulfate crystallizes. Preferably, the evaporation and concentration time is 2h-6h. Increasing the reaction time can increase the product yield and is more conducive to the full recovery of the product.

[0048] In a second aspect, the present invention provides a recycling system for the recycling method described in the first aspect, the system comprising:

[0049] The pulping module is provided with a white dust inlet, a pulping liquid inlet, and a white dust slurry outlet. The pulping liquid inlet introduces water and sulfuric acid into the pulping module.

[0050] The leaching module is provided with a white smoke slurry inlet and a leached liquid outlet, wherein the white smoke slurry inlet and the white smoke slurry outlet are connected;

[0051] The first solid-liquid separation module is provided with a leaching liquid inlet, a first leaching liquid outlet and a lead-bismuth-containing leaching residue outlet, wherein the leaching liquid inlet and the leaching liquid outlet are connected.

[0052] A chlorination leaching module is provided with a lead-bismuth-containing leaching residue inlet, a chlorination leaching agent inlet, and a chlorination leaching liquid outlet. The lead-bismuth-containing leaching residue inlet is connected to the lead-bismuth-containing leaching residue outlet. The chlorination leaching agent inlet introduces chlorination leaching agent into the chlorination leaching module. The chlorination leaching agent includes sodium chloride and sulfuric acid. The chlorination leaching agent may or may not contain the recovered liquid.

[0053] The second solid-liquid separation module is provided with a chlorinated leaching liquid inlet, a second leaching liquid outlet and a lead sulfate-containing leaching residue outlet, wherein the chlorinated leaching liquid inlet and the chlorinated leaching liquid outlet are connected.

[0054] The neutralization treatment module is provided with a second leachate inlet, a neutralizing agent inlet, and a neutralized liquid outlet. The second leachate inlet is connected to the second leachate outlet, and the neutralizing agent inlet introduces sodium hydroxide and sodium carbonate into the neutralization treatment module.

[0055] The third solid-liquid separation module is provided with a neutralized liquid inlet, a neutralized liquid outlet and a neutralized residue outlet containing bismuth oxychloride, wherein the neutralized liquid inlet and the neutralized liquid outlet are connected.

[0056] The sodium salt recovery and treatment module recovers sodium salt from the neutralized solution. It is equipped with a neutralized solution inlet, a recovered solution outlet, and a sodium sulfate outlet. The neutralized solution inlet is connected to the neutralized solution outlet, and the recovered solution outlet is connected to the chlorination leaching agent inlet.

[0057] In some preferred embodiments, the sodium salt recovery and processing module includes:

[0058] An evaporation and concentration unit is provided with a neutralized liquid inlet and an evaporated and concentrated liquid outlet;

[0059] A cooling crystallization unit is provided with an inlet for the evaporated and concentrated liquid and an outlet for the cooled and crystallized liquid, wherein the inlet for the evaporated and concentrated liquid is connected to the outlet for the evaporated and concentrated liquid.

[0060] The crystallization filtration unit is provided with a cooling crystallization liquid inlet, a recovery liquid outlet and a sodium sulfate outlet, wherein the cooling crystallization liquid inlet and the cooling crystallization liquid outlet are connected.

[0061] The present invention will be further described in detail below with reference to specific embodiments.

[0062] Example 1

[0063] The composition of the white smoke dust is Cu: 3.51 wt%, As: 4.84 wt%, Pb: 10.63 wt%, Bi: 2.94 wt%, Sb: 0.14 wt%, Zn: 16.74 wt%, Au: 0.42 g / t, and Ag: 114.41 g / t. The method for recovering valuable metals from the white smoke dust of this invention is described in reference [reference needed]. Figure 1 ,include:

[0064] Step 1: The white smoke dust and slurry are thoroughly mixed and homogeneously mixed in the slurry module to obtain a white smoke dust slurry. The liquid-to-solid ratio of the white smoke dust slurry is 4:1, the acidity of the white smoke dust slurry is 95 g / L, and the slurrying time is 1.5 h. The white smoke dust slurry is then leached in the leaching module under normal pressure, and a certain amount of steam is introduced for heating to obtain the leached liquid. The leaching temperature is 80℃, and the leaching time is 2.5 h. The leached liquid is then passed into the first solid-liquid separation module for filtration to obtain the first leaching solution and the leaching residue containing lead and bismuth.

[0065] Step 2: The lead-bismuth-containing leaching residue is mixed evenly with a chlorination leaching agent including sodium chloride and sulfuric acid in the chlorination leaching module and then subjected to chlorination leaching. A certain amount of steam is introduced for heating to obtain the chlorinated leaching solution. The chloride ion concentration of the chlorination leaching agent is 110 g / L, the acidity is 110 g / L, the liquid-to-solid ratio of chlorination leaching is 5:1, the leaching temperature is 80℃, and the leaching time is 3 hours. The chlorinated leaching solution is then passed into the second solid-liquid separation module for filtration to obtain the second leaching solution and the lead sulfate-containing leaching residue.

[0066] Step 3: The second leachate is mixed evenly with a neutralizing agent including sodium hydroxide and sodium carbonate in the neutralization treatment module and then neutralized to obtain a neutralized liquid. The pH of the system after the second leachate and the neutralizing agent are mixed evenly is 5, the neutralization temperature is 80℃, and the neutralization time is 3h. The neutralized liquid is then passed into the third solid-liquid separation module for filtration to obtain a neutralized residue and a neutralized liquid containing bismuth oxychloride.

[0067] Step 4: Add sulfuric acid to the neutralization solution to adjust the pH of the neutralization solution to 3. Pass the neutralization solution with adjusted pH into the evaporation and concentration unit for evaporation and concentration to obtain the concentrated liquid. The evaporation and concentration temperature is 110℃ and the time is 2h. Pass the concentrated liquid into the cooling and crystallization unit for cooling and crystallization to obtain the cooled and crystallized liquid. The cooling temperature is 20℃ and the cooling time is 1h. Pass the cooled and crystallized liquid into the crystallization and filtration unit for crystallization and filtration to obtain the recovered liquid and sodium sulfate. Return the recovered liquid to the chlorination leaching module as the chlorination leaching agent.

[0068] Step 5: The white smoke dust and slurry are thoroughly mixed and homogeneously in the slurry module to obtain a white smoke dust slurry. The liquid-to-solid ratio of the white smoke dust slurry is 4:1, the acidity of the white smoke dust slurry is 95 g / L, and the slurrying time is 1.5 h. The white smoke dust slurry is then leached at normal pressure in the leaching module, and a certain amount of steam is introduced for heating to obtain the leached liquid. The leaching temperature is 95℃, and the leaching time is 2.5 h. The leached liquid is then passed into the first solid-liquid separation module for filtration to obtain the first leaching liquid and the leaching residue containing lead and bismuth. Steps 2, 3, 4, and 5 are repeated, and the acidity of the chlorinated leaching agent is maintained at 110 g / L.

[0069] In this embodiment, the direct recovery rates of lead and bismuth are 90.54% and 91.28%, respectively. The sodium concentration in the product sodium sulfate is 28.55 wt%. After the recovered liquid is returned to the chlorination leaching module as a chlorination leaching agent, the zinc content of the leaching residue containing lead sulfate and the neutralization residue containing bismuth oxychloride is maintained below 3 wt% and 1.5 wt%, respectively.

[0070] Example 2

[0071] The procedure was carried out in accordance with Example 1, except that in step four, sulfuric acid was added to the neutralization solution to adjust the pH of the neutralization solution to 1. In this example, the direct recovery rates of lead and bismuth were 88.71% and 89.93%, respectively. The sodium concentration in the product sodium sulfate was 23.07 wt%. After returning the recovered liquid to the chlorination leaching module as a chlorination leaching agent, the zinc content in the lead sulfate-containing leaching residue and the bismuth oxychloride-containing neutralization residue remained below 3.1 wt% and 2 wt%, respectively.

[0072] Example 3

[0073] The process was carried out in accordance with Example 1, except that the evaporation and concentration temperature was 80°C. In this example, the direct recovery rates of lead and bismuth were 86.90% and 88.36%, respectively. The sodium concentration in the product sodium sulfate was 21.97 wt%. After returning the recovered liquid to the chlorination leaching module as a chlorination leaching agent, the zinc content in the lead sulfate-containing leaching residue and the bismuth oxychloride-containing neutralization residue remained below 3.2 wt% and 2.1 wt%, respectively.

[0074] Comparative Example 1

[0075] The process was carried out in accordance with Example 1, except that the leaching temperature in step five was 80°C under normal pressure. In this example, the direct recovery rates of lead and bismuth were 83.21% and 85.07%, respectively, and the sodium concentration in the product sodium sulfate was 20.19 wt%. The recovered liquid was returned to the chlorination leaching module as a chlorination leaching agent. After repeating steps two, three, four, and five for a period of time, the zinc content in the lead sulfate-containing leaching residue and the bismuth oxychloride-containing neutralization residue remained below 4.3 wt% and 2.4 wt%, respectively.

[0076] Compared with Examples 1-3, adjusting the pH of the neutralized liquid to 3-4 and the evaporation and concentration temperature to 95℃-115℃ before evaporation and concentration is more conducive to the precipitation of sodium sulfate solid during the cooling and crystallization process. Compared with Example 1 and Comparative Example 1, when the chlorinated leaching agent contains the recovered liquid, the leaching temperature of the white smoke dust slurry is not lower than 90℃, which is more conducive to reducing the zinc content of the leaching residue containing lead sulfate and the neutralized residue containing bismuth oxychloride.

[0077] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for recovering valuable metals from white smoke dust, characterized in that, include: The white smoke dust is mixed with a slurry and slurry is slurried to obtain a white smoke dust slurry. The slurry contains water and sulfuric acid, and the acidity of the white smoke dust slurry is 80 g / L to 100 g / L. The white smoke slurry is leached to obtain a leached liquid. When the chlorinated leaching agent does not contain the recovered liquid, the leaching temperature is 80℃~85℃. When the chlorinated leaching agent contains the recovered liquid, the leaching temperature is 90℃~100℃. The leached liquid is then subjected to a first solid-liquid separation to obtain a first leaching solution and a leaching residue containing lead and bismuth. The lead-bismuth-containing leaching residue is mixed evenly with the chlorination leaching agent in a chlorination leaching module and then subjected to chlorination leaching to obtain a post-chlorination leaching solution. The chlorination leaching agent includes sodium chloride and sulfuric acid, and the chlorination leaching agent may or may not contain the post-chlorination solution. The post-chlorination leaching solution is then subjected to a second solid-liquid separation to obtain a second leaching solution and a lead sulfate-containing leaching residue. The chlorination leaching conditions include: the acidity of the chlorination leaching agent is 100 g / L to 140 g / L, and the leaching temperature is 70℃ to 90℃. The second leachate is mixed evenly with a neutralizing agent and then neutralized to obtain a neutralized liquid. The neutralizing agent includes sodium hydroxide and sodium carbonate. The neutralized liquid is then subjected to a third solid-liquid separation to obtain a neutralized residue and a neutralized liquid containing bismuth oxychloride. The neutralized solution is subjected to sodium salt recovery treatment to obtain the recovered solution and sodium sulfate. The recovered solution is then returned to the chlorination leaching module as the chlorination leaching agent. The sodium salt recovery treatment includes evaporating and concentrating the neutralized solution, cooling and crystallizing, and filtering the crystals to obtain the recovered solution and sodium sulfate. The conditions for evaporation and concentration include adjusting the pH of the neutralized solution to 3-4 before evaporation and concentration.

2. The recycling method according to claim 1, characterized in that, The conditions for pulping include: the liquid-to-solid ratio of the white smoke dust slurry is 3 to 5:

1.

3. The recycling method according to claim 1, characterized in that, The conditions for chlorination leaching include: the chloride ion concentration of the chlorination leaching agent is 100 g / L to 140 g / L, and the liquid-to-solid ratio of chlorination leaching is 4 to 6:

1.

4. The recycling method according to claim 3, characterized in that, The chlorination leaching conditions also include a leaching time of 2 to 6 hours.

5. The recycling method according to claim 1, characterized in that, The conditions for the neutralization treatment include: the pH of the system after the second leachate and the neutralizing agent are mixed evenly is 4 to 6.

6. The recycling method according to claim 5, characterized in that, The neutralization conditions also include: a neutralization temperature of 70℃~90℃ and a neutralization time of 2h~6h.

7. The recycling method according to claim 1, characterized in that, The conditions for evaporation and concentration include: an evaporation and concentration temperature of 95℃ to 115℃.

8. A recycling system for use in the recycling method according to any one of claims 1-7, characterized in that, The system includes: The pulping module is provided with a white dust inlet, a pulping liquid inlet, and a white dust slurry outlet. The pulping liquid inlet introduces water and sulfuric acid into the pulping module. The leaching module is provided with a white smoke slurry inlet and a leached liquid outlet, wherein the white smoke slurry inlet and the white smoke slurry outlet are connected; The first solid-liquid separation module is provided with a leaching liquid inlet, a first leaching liquid outlet and a lead-bismuth-containing leaching residue outlet, wherein the leaching liquid inlet and the leaching liquid outlet are connected. A chlorination leaching module is provided with a lead-bismuth-containing leaching residue inlet, a chlorination leaching agent inlet, and a chlorination leaching liquid outlet. The lead-bismuth-containing leaching residue inlet is connected to the lead-bismuth-containing leaching residue outlet. The chlorination leaching agent inlet introduces chlorination leaching agent into the chlorination leaching module. The chlorination leaching agent includes sodium chloride and sulfuric acid. The chlorination leaching agent may or may not contain the recovered liquid. The second solid-liquid separation module is provided with a chlorinated leaching liquid inlet, a second leaching liquid outlet and a lead sulfate-containing leaching residue outlet, wherein the chlorinated leaching liquid inlet and the chlorinated leaching liquid outlet are connected. The neutralization treatment module is provided with a second leachate inlet, a neutralizing agent inlet, and a neutralized liquid outlet. The second leachate inlet is connected to the second leachate outlet, and the neutralizing agent inlet introduces sodium hydroxide and sodium carbonate into the neutralization treatment module. The third solid-liquid separation module is provided with a neutralized liquid inlet, a neutralized liquid outlet and a neutralized residue outlet containing bismuth oxychloride, wherein the neutralized liquid inlet and the neutralized liquid outlet are connected. The sodium salt recovery and treatment module recovers sodium salt from the neutralized solution. It is equipped with a neutralized solution inlet, a recovered solution outlet, and a sodium sulfate outlet. The neutralized solution inlet is connected to the neutralized solution outlet, and the recovered solution outlet is connected to the chlorination leaching agent inlet.

9. The recycling system according to claim 8, characterized in that, The sodium salt recovery and processing module includes: An evaporation and concentration unit is provided with a neutralized liquid inlet and an evaporated and concentrated liquid outlet; A cooling crystallization unit is provided with an inlet for the evaporated and concentrated liquid and an outlet for the cooled and crystallized liquid, wherein the inlet for the evaporated and concentrated liquid is connected to the outlet for the evaporated and concentrated liquid. The crystallization filtration unit is provided with a cooling crystallization liquid inlet, a recovery liquid outlet and a sodium sulfate outlet, wherein the cooling crystallization liquid inlet and the cooling crystallization liquid outlet are connected.

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