Method for recovering lead from lead-containing slag and preparing high-activity lead oxide

Abstract

The invention provides a method for recovering lead from lead-containing slag and preparing high-activity lead oxide, and belongs to the technical field of resource utilization. The method specifically comprises the following steps: 1, treating the lead-containing waste residues by using an acid solution to remove impurities such as copper and zinc in the lead-containing waste residues, and then carrying out solid-liquid separation to obtain lead-containing solids; 2, dissolving lead in the lead-containing solid by using an alkali solution to obtain a lead-containing solution; 3, adding a precipitant into the lead-containing solution to obtain a lead precipitate; and 4, roasting the precipitated solid to obtain the high-activity lead oxide. The method is simple in technological process, low in equipment requirement, economical and free of pollution, meanwhile, high-activity lead oxide can be prepared, and the lead recovery rate can reach 95% or above.

Description

Technical Field

[0001] The invention relates to the technical field of resource utilization, and in particular to a method for recovering lead from lead-containing slag and preparing highly active lead oxide. Background Art

[0002] my country is the world's largest consumer of refined lead. Despite having the world's second largest lead mineral resource reserves and the largest lead concentrate resource reserves, it still needs to import a large amount of lead ore raw materials from abroad every year. At present, there are two main types of refined lead used in industrial production: one is naturally formed lead minerals (galena, cerussite, etc.), and the other is lead resources recovered from secondary lead sources (lead smelting slag, waste lead-acid batteries, etc.). However, the recycling process of secondary lead sources often generates pollutants such as SO2, SO3, and lead dust, which will pollute the environment. In serious cases, it will enter the ecosystem and affect people's normal production activities. Therefore, developing an efficient and pollution-free waste lead slag recycling process is one of the problems that the secondary lead industry urgently needs to solve.

[0003] At present, the main methods for recycling waste lead resources are: pyrometallurgical process, hydrometallurgical recovery process and pyrometallurgical and hydrometallurgical combined recovery process. The pyrometallurgical process refers to the direct reduction of waste lead slag and the recovery of lead therein by high-temperature melting. Chinese patent CN 112981119 A discloses a lead recovery process for lead chloride slag, which mixes lead chloride slag and desulfurized gypsum in a certain proportion, then adds a reducing agent and smelts at 1200-1300℃ oxygen-enriched for 4-5h to obtain crude lead with a lead taste of 93%. This method has a simple process and a large processing capacity, but it will inevitably produce secondary pollution, and the lead dust content is large, and the lead resource recovery rate is not high. The wet recovery process is to first use a medium such as a strong acid or a strong alkali to dissolve the waste lead slag, and then use an electrolytic deposition method to reduce the lead therein to elemental Pb or PbO for recovery. Chinese patent CN 112877543 A discloses a method for recovering lead from lead slag, which uses a methanesulfonic acid solution to leach waste lead slag, uses the leachate as the cathode electrolyte, and recovers lead after electrolysis using an electrolysis device. This method can achieve selective leaching of lead from waste lead slag, and can obtain refined lead containing 95% lead, but the process has high equipment requirements, high energy consumption and high cost. The combined process of wet and pyrometallurgy is to first treat waste lead paste by wet leaching technology to obtain a precursor, and then use a low-temperature calcination method to convert the precursor into PbO. Chinese patent CN 107134602 A discloses a method for synthesizing highly active ultrafine lead oxide powder from waste lead paste, which uses ammonium bicarbonate and ammonia water to treat lead paste for desulfurization, then adds acetic acid and hydrogen peroxide to obtain a lead acetate solution, and finally adds sodium benzoate to prepare a lead benzoate precursor, and finally calcines the lead benzoate at 300-330°C for 2-4h to obtain ultrafine lead oxide powder. However, the process is relatively complicated, the desulfurization effect is poor, the price of the leaching agent is high, the economic benefits are low, and it is difficult to industrialize production.

[0004] In summary, the existing waste lead slag treatment process has the following problems: 1. The temperature of the pyrometallurgical direct smelting reduction process is mostly above 1000°C, with high energy consumption, serious waste of resources, and secondary pollution; 2. The wet treatment process has poor leaching effect. The waste lead slag must be pretreated before leaching to remove impurities, otherwise it will affect the electrolysis efficiency and product purity, and the cost is high and the equipment requirements are high. 3. It is difficult to find an efficient and low-cost desulfurizer for the pyrometallurgical and wet combined process. The acetic acid, citric acid and sodium citrate used for leaching are expensive, with low economic benefits, and are not suitable for large-scale industrial production. Based on this, the present invention provides a method for recovering lead from lead-containing slag and preparing highly active lead oxide, so as to achieve efficient and low-cost lead resource recovery and utilization. Summary of the invention

[0005] The purpose of the present invention is to provide a method for recovering lead from lead-containing slag and preparing high-activity lead oxide, which is low in price, simple in process, low in equipment requirements, does not use electrolysis technology, has low energy consumption, and the roasting temperature is 300-600°C, does not generate polluting gases such as SO2 and SO3, and the residual acid and residual alkali generated in the process can be returned to the system for recycling, does not require additional purification equipment, and does not generate secondary pollution. At the same time, PbO products with high economic value can be prepared, which makes up for the shortcomings of the existing technology for treating waste lead slag.

[0006] The technical solution of the present invention is achieved in this way: The present invention provides a method for recovering lead from lead-containing slag and preparing high-activity lead oxide, comprising the following steps: (1) taking a certain amount of lead-containing waste slag, using an acid solution to dissolve the lead-containing slag, adding an oxidant during the dissolution process, the dissolution time is 1-3 hours, and solid-liquid separation to obtain lead-containing solid and residual acid; (2) The lead-containing solid obtained in step (1) is dissolved in an alkaline solution to obtain an alkaline-soluble solid and a lead-containing liquid after solid-liquid separation. The alkaline dissolution process is maintained at 70-90° C. for 1-3 h. (3) adding a precipitant to the lead-containing liquid obtained in step (2), stirring at room temperature for 12-24 hours, and separating the solid and liquid to obtain lead carbonate; (4) The lead carbonate precipitate obtained in step (3) is washed and then roasted for 3-5 hours to obtain highly active lead oxide.

[0007] As a further improvement of the present invention, the acid solution used in step (1) is a sulfuric acid solution or a hydrochloric acid solution, the concentration of the acid solution used is 1-4 mol / L, and the liquid-to-solid ratio is maintained at 3-7:1 during the dissolution process; the oxidant used is one or more of ozone, hydrogen peroxide, chlorine, calcium hypochlorite, sodium hypochlorite, and chlorine dioxide, and the amount of the oxidant added is 1-10%; the obtained lead-containing solid enters the next process, and the residual acid is used to prepare the acid solution to continue step (1).

[0008] As a further improvement of the present invention, the solution used in step (2) is one or more of sodium hydroxide solution, potassium hydroxide solution or ammonia solution, the concentration of the alkaline solution used is 5-10 mol / L, and the liquid-to-solid ratio is maintained at 6-9:1 during dissolution. The resulting lead-containing liquid enters the next process, and the lead-containing solid returns to step (1) for dissolution.

[0009] As a further improvement of the present invention, the precipitant used in step (3) is one or more of carbon dioxide, sodium carbonate, sodium bicarbonate, and sodium hydroxide.

[0010] As a further improvement of the present invention, the lead carbonate in step (4) is washed 2-3 times with distilled water and the calcination temperature is 300-600°C.

[0011] As a further improvement of the present invention, the precipitant used in step (3) is a mixture of carbon dioxide and sodium hydroxide.

[0012] As a further improvement of the present invention, the ventilation rate of the carbon dioxide is 10-15 mL / min, and the addition amount of the sodium hydroxide is a final concentration of 100-200 g / L.

[0013] As a further improvement of the present invention, the oxidant used in step (1) is a mixture of ozone and chlorine.

[0014] As a further improvement of the present invention, the ventilation volume of the mixed gas is 20-30 mL / min.

[0015] As a further improvement of the present invention, the volume ratio of ozone to chlorine is 10:2-5.

[0016] The present invention has the following beneficial effects: The invention uses a pyrometallurgical and hydrometallurgical combined process to treat waste lead slag, uses alkaline solution to dissolve lead-containing solids, and has a lead recovery rate of 95%. The invention has low price, simple process, low equipment requirements, no electrolysis technology, low energy consumption, and a roasting temperature of 300-600°C. Pollution gases such as SO2 and SO3 will not be generated. The residual acid and residual alkali generated in the process can be returned to the system for recycling, without the need for additional purification equipment, and no secondary pollution will be generated. Meanwhile, a PbO product with high economic value can be prepared, thereby making up for the shortcomings of the prior art in treating waste lead slag. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0018] Figure 1 The present invention is a flow chart of a method for recovering lead from lead-containing slag and preparing highly active lead oxide. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example 1

[0020] The composition of lead-containing slag after treatment in a steel plant is shown in Table 1: Table 1 Composition of lead-containing slag after treatment in a steel plant

[0021] As shown in the table above, 1 mol / L sulfuric acid is used to dissolve the lead-containing slag. The dissolution time is 1 hour, the dissolution temperature is room temperature, and the liquid-solid ratio is maintained at 3:1 during the dissolution process. At the same time, an oxidant is added. The oxidant used is a mixed gas of ozone and chlorine. The ventilation volume is 20 mL / min, and the volume ratio of ozone and chlorine is 10:2. After the reaction is completed, solid-liquid separation is performed to obtain lead-containing solids and residual acid. The lead-containing solid enters the next step, and the residual acid is used to prepare sulfuric acid solution to continue to dissolve the lead-containing slag. The composition of the lead-containing solid is shown in Table 2 below.

[0022] Table 2 Composition of lead-containing solids

[0023] As shown in the table above, the main component of the lead-containing solid is lead sulfate, which is dissolved using a 5 mol / L sodium hydroxide solution, with a liquid-solid ratio of 6:1 and a dissolution temperature of 70°C. After reacting for 1 hour, solid-liquid separation is performed to obtain an alkali-soluble solid and a lead-containing liquid. The lead-containing liquid enters the next step, and the alkali-soluble solid returns to the first step for dissolution. The composition of the lead-containing liquid is shown in Table 3 below.

[0024] Table 3 Composition of lead-containing liquid

[0025] As shown in the above table, the main component of the lead-containing liquid is lead ions. A precipitant is added to the lead-containing liquid. The precipitant used is a mixture of carbon dioxide and sodium hydroxide. The ventilation rate of the carbon dioxide is 10 mL / min, and the amount of sodium hydroxide added is a final concentration of 100 g / L. After stirring and precipitating for 12 hours, the solid-liquid separation is performed to obtain a lead carbonate product. The obtained lead carbonate product is washed twice with distilled water and then roasted at 300°C for 3 hours to obtain a high-activity lead oxide product. The comprehensive lead recovery rate is 95.6%. Example 2

[0026] The composition of lead-containing slag after treatment in a steel plant is shown in Table 4 below: Table 4 Composition of lead-containing slag after treatment in a steel plant

[0027] As shown in the table above, 3 mol / L sulfuric acid is used to dissolve the lead-containing slag. The dissolution time is 2 hours, the dissolution temperature is room temperature, and the liquid-solid ratio is maintained at 5:1 during the dissolution process. An oxidant is added at the same time. The oxidant used is a mixed gas of ozone and chlorine. The ventilation volume is 30 mL / min, and the volume ratio of ozone and chlorine is 10:5. After the reaction is completed, solid-liquid separation is performed to obtain lead-containing solids and residual acid. The lead-containing solid enters the next step, and the residual acid is used to prepare sulfuric acid solution to continue to dissolve the lead-containing slag. The composition of the lead-containing solid is shown in Table 5 below.

[0028] Table 5 Lead-containing solid components

[0029] As shown in the table above, the main component of the lead-containing solid is lead sulfate, which is dissolved using 7 mol / L sodium hydroxide solution, with a liquid-solid ratio of 8:1 and a dissolution temperature of 80°C. After reacting for 2 hours, solid-liquid separation is performed to obtain alkali-soluble solid and lead-containing liquid. The lead-containing liquid enters the next step, and the alkali-soluble solid returns to the first step for dissolution. The composition of the lead-containing liquid is shown in Table 6 below.

[0030] Table 6 Composition of lead-containing liquids

[0031] As shown in the above table, the main component of the lead-containing liquid is lead ions. A precipitant is added to the lead-containing liquid. The precipitant used is a mixture of carbon dioxide and sodium hydroxide. The ventilation rate of the carbon dioxide is 15 mL / min, and the amount of sodium hydroxide added is a final concentration of 200 g / L. After stirring and precipitating for 18 hours, the solid-liquid separation is performed to obtain a lead carbonate product. The obtained lead carbonate product is washed twice with distilled water and then roasted at 500°C for 4 hours to obtain a high-activity lead oxide product. The comprehensive lead recovery rate is 97.3%. Example 3

[0032] The composition of lead-containing slag after treatment in a steel plant is shown in Table 7 below: Table 7 Composition of lead-containing slag after treatment in a steel plant

[0033] As shown in the table above, 4 mol / L sulfuric acid is used to dissolve the lead-containing slag. The dissolution time is 3 hours, the dissolution temperature is room temperature, and the liquid-solid ratio is maintained at 7:1 during the dissolution process. At the same time, an oxidant is added. The oxidant used is a mixed gas of ozone and chlorine. The ventilation volume is 25 mL / min, and the volume ratio of ozone and chlorine is 10:3. After the reaction is completed, solid-liquid separation is performed to obtain lead-containing solids and residual acid. The lead-containing solid enters the next step, and the residual acid is used to prepare sulfuric acid solution to continue to dissolve the lead-containing slag. The composition of the lead-containing solid is shown in Table 8 below.

[0034] Table 8 Lead-containing solid components

[0035] As shown in the table above, the main component of the lead-containing solid is lead sulfate, which is dissolved using a 10 mol / L sodium hydroxide solution, maintaining a liquid-solid ratio of 9:1 during dissolution, and a dissolution temperature of 90°C. After reacting for 3 hours, solid-liquid separation is performed to obtain an alkali-soluble solid and a lead-containing liquid. The lead-containing liquid enters the next step, and the alkali-soluble solid returns to the first step for dissolution. The composition of the lead-containing liquid is shown in Table 9 below.

[0036] Table 9 Composition of lead-containing liquids

[0037] As shown in the above table, the main component of the lead-containing liquid is lead ions. A precipitant is added to the lead-containing liquid. The precipitant used is a mixture of carbon dioxide and sodium hydroxide. The ventilation rate of the carbon dioxide is 12 mL / min, and the amount of sodium hydroxide added is a final concentration of 150 g / L. After stirring and precipitating for 24 hours, the solid-liquid separation is performed to obtain a lead carbonate product. The obtained lead carbonate product is washed 3 times with distilled water and then roasted at 600°C for 5 hours to obtain a high-activity lead oxide product. The comprehensive lead recovery rate is 96.8%.

[0038] Compared with Example 3, Comparative Example 1 is different in that the precipitant is single carbon dioxide, the ventilation volume of the carbon dioxide is 12 mL / min, and the comprehensive calculated lead recovery rate is 91.5%.

[0039] Compared with Example 3, Comparative Example 2 is different in that the precipitant is a single sodium hydroxide, the amount of sodium hydroxide added is a final concentration of 150 g / L, and the comprehensive calculation of the lead recovery rate is 90.4%.

[0040] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for recovering lead from lead-containing slag and preparing highly active lead oxide, characterized in that: The following steps are involved: (1) taking a certain amount of lead-containing waste slag, using an acid solution to dissolve the lead-containing slag, adding an oxidant during the dissolution process, the dissolution time is 1-3 hours, and solid-liquid separation to obtain lead-containing solid and residual acid; (2) The lead-containing solid obtained in step (1) is dissolved in an alkaline solution to obtain an alkaline-soluble solid and a lead-containing liquid after solid-liquid separation. The alkaline dissolution process is maintained at 70-90° C. for 1-3 h. (3) adding a precipitant to the lead-containing liquid obtained in step (2), stirring at room temperature for 12-24 hours, and separating the solid and liquid to obtain lead carbonate; (4) The lead carbonate precipitate obtained in step (3) is washed and then roasted for 3-5 hours to obtain highly active lead oxide.

2. The method according to claim 1, characterized in that: The acid solution used in step (1) is a sulfuric acid solution or a hydrochloric acid solution, the concentration of the acid solution used is 1-4 mol / L, and the liquid-to-solid ratio is maintained at 3-7:1 during the dissolution process; the oxidant used is one or more of ozone, hydrogen peroxide, chlorine, calcium hypochlorite, sodium hypochlorite, and chlorine dioxide, and the amount of the oxidant added is 1-10%; the obtained lead-containing solid enters the next process, and the residual acid is used to prepare the acid solution to continue step (1).

3. The method according to claim 1, characterized in that The solution used in step (2) is one or more of sodium hydroxide solution, potassium hydroxide solution or ammonia solution. The concentration of the alkaline solution used is 5-10 mol / L. During dissolution, the liquid-to-solid ratio is maintained at 6-9:

1. The resulting lead-containing liquid enters the next process, and the lead-containing solid returns to step (1) for dissolution.

4. The method according to claim 1, characterized in that: The precipitant used in step (3) is one or more of carbon dioxide, sodium carbonate, sodium bicarbonate, and sodium hydroxide.

5. The method according to claim 1, characterized in that The lead carbonate in step (4) is washed 2-3 times with distilled water and the calcination temperature is 300-600°C.

6. The method according to claim 4, characterized in that The precipitant used in step (3) is a mixture of carbon dioxide and sodium hydroxide.

7. The method according to claim 6, characterized in that The ventilation rate of the carbon dioxide is 10-15 mL / min, and the addition amount of the sodium hydroxide is a final concentration of 100-200 g / L.

8. The method according to claim 2, characterized in that: The oxidant used in step (1) is a mixture of ozone and chlorine.

9. The method according to claim 8, characterized in that The ventilation volume of the mixed gas is 20-30 mL / min.

10. The method according to claim 8, characterized in that The volume ratio of ozone to chlorine is 10:2-5.

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