METHOD FOR RECOVERING LEAD OXIDE FROM WASTE LEAD PASTE

Abstract

A method for recovering lead oxide from a pre-desalted lead paste, comprising the following steps: a. dissolving the pre-desalted lead plaster by using a complexing agent solution, and making all of PbO therein react with the complexing agent to generate lead complexing ions, obtaining a lead-containing solution and a filter residue; b. adding a precipitant to the lead-containing solution, and then the precipitant reacting with the lead complexing ions to generate a lead salt precipitate and the regenerated complexing agent; c. calcining the lead salt precipitate to obtain lead oxide and regenerate the precipitant. The final recovery rate of lead oxide of the method can reach 99% or more.

Claims

1. A method for recovering lead oxide from pre-desalted lead paste, comprising the following steps: a. dissolving pre-desalted lead paste by using a complexing agent solution, so that all PbO in the pre-desalted lead paste reacts with the complexing agent to generate lead complexing ions and thereby obtain a lead-containing solution and a filter residue, wherein, the PbO is from the original PbO in the pre-desalted lead paste and PbO generated in a reaction between the original Pb and PbO.sub.2 from the pre-desalted lead paste in the complexing agent solution, and further includes PbO obtained from oxidation of the original Pb in the pre-desalted lead paste or reduction of the original PbO.sub.2, wherein, the complexing agent is selected from compound with amino and carboxyl groups, organic amine, alcohol amine, or salts of them; b. adding a precipitant into the lead-containing solution, so that the precipitant reacts with the lead complexing ions to generate a lead salt precipitate and a regenerated complexing agent, wherein, the precipitant is selected from CO.sub.2, SO.sub.2 or SO.sub.3. or a water solution of them; c. calcining the lead salt precipitate to obtain lead oxide and regenerate the precipitant.

2. The method according to claim 1, wherein, the pre-desalted lead paste refers to a product obtained through a reaction between the lead paste and an alkaline liquor in which the lead salts included in the lead paste are removed, the lead salt is PbSO.sub.4, PbSO.sub.3, Pb(CH.sub.3COO).sub.2, Pb(NO.sub.3).sub.2, Pb(ClO.sub.4).sub.2 or PbCO.sub.3, the alkaline liquor is selected from a water solution of NaOH, KOH, ammonia, or Ba(OH).sub.2 in which the concentration in weight percentage is 0.5-40%, and the desalting time is 0.5-60 min.

3. (canceled)

4. (canceled)

5. The method according to claim 1, wherein, the compound with amino and carboxyl groups is selected from a-amino acid, ethylene diammine diacetate, ethylenediamine tetraacetic acid, propanediamine diacetic acid, iminodiacetic acid, glucosaminic acid, or alginic acid; wherein, the organic amine is selected from methyl amine, ethylene diamine, propylene diamine, diethylene triamine, or triethylene tetramine; wherein, the alcohol amine is selected from ethanolamine, di-ethanolamine, or tri-ethanolamine.

6. The method according to claim 1, wherein, in the step a, a catalyst is added into the complexing agent solution to accelerate the oxidation-reduction reaction between Pb and PbO.sub.2 that generates PbO, wherein, the catalyst is selected from metal powder of Cu, Co, Ni, or Ag, or chlorides, oxides or nitrates of the aforesaid metal.

7. The method according to claim 1, wherein, if the content of Pb in the pre-desalted lead paste is lower than the content of PbO.sub.2, additional lead is added in the step a, so as to fully reduce PbO.sub.2 to PbO; or if the content of Pb in the pre-desalted lead paste is greater than the content of PbO.sub.2, oxygen is blasted into the complexing agent solution in the step a, so as to fully convert Pb into PbO; or regardless of the content of Pb and the content of PbO.sub.2 in the pre-desalted lead paste, the pre-desalted lead paste is treated with adequate H.sub.2O.sub.2 solution, so as to fully oxidize Pb to PbO, or fully reduce PbO.sub.2 to PbO.

8. (canceled)

9. The method according to claim 1, wherein, the regenerated complexing agent obtained in the step b is returned to the step a and reused; and/or the regenerated precipitant obtained in the step c is returned to the step b and reused; wherein, both the step a and the step b are executed within a water solution temperature range of 5-110° C.

10. The method according to claim 5, wherein, the α-amino acid is selected from aspartic acid, methionine, valine, lysine, isoleucine, phenylalanine, tryptophane, threonine, glycine, proline, histidine, glutamic acid, serine, arginine, sarcosine or citrulline.

Description

DESCRIPTION OF THE DRAWINGS

[0053] FIG. 1 is a schematic process flow chart of PbO recovered from waste lead paste with the atom-economic method according to the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0054] Hereunder the present invention will be detailed in embodiments with reference to the accompanying drawings, to make the above-mentioned advantages of the present invention understood more clearly. The accompanying drawings are provided only to describe the present invention, but do not constitute any limitation to the present invention.

Embodiment 1

[0055] Lead paste obtained by crashing and separating waste commercial 12V, 7 Ah valve-regulated sealed lead-acid batteries with a conventional method is used. After the total amount of PbSO.sub.4 in the lead paste is ascertained through conventional chemical titrimetric analysis, 10% NaOH is added at a stoichiometric ratio as alkaline liquor, the processing temperature is controlled at 35° C., the processing time is 10 min., and the stirring rate is 100 rpm. After the lead paste is treated with the alkaline liquor, solid-liquid separation is carried out, to obtain pre-desalted lead paste and desalting mother liquid that mainly contains Na.sub.2SO.sub.4. The treating process is as follows: [0056] a. 1 kg pre-desalted lead paste is added into a first reactor (10 L), 0.6 kg lead powder obtained by crashing lead-containing plate grating with a conventional method is added in an excessive amount into the reactor, 8 g CoO is added as a catalyst, 0.5 mol/L arginine water solution is added in an adequate amount as a complexing agent, and the mixture is stirred for 1.5 h at 60° C. constant temperature. The mixture obtained through the reaction is filtered and separated, to obtain lead-containing solution and filter residue. The lead-containing solution is laid aside to treat in the follow-up step b. Through analysis, it is found that the filter residue is essentially a solid mixture that contains some residual lead powder and impurities, wherein, the lead powder can be returned to the step a and reused, or can be separated with a conventional gravity separation method to obtain lead powder. [0057] b. The lead-containing solution obtained in the step a is transferred into a second reactor (25 L), CO.sub.2 is charged in an adequate amount continuously while stirring at 50° C. constant temperature, till no precipitate is generated anymore. The mixture after the reaction is filtered and separated, to obtain PbCO.sub.3 precipitate and filtrate that contains regenerated arginine, wherein, the filtrate is returned to the step a and reused. [0058] c. The obtained PbCO.sub.3 precipitate is transferred into a calcinator, and is calcined for 2 h at 390° C., to obtain PbO product and CO.sub.2, wherein, the CO.sub.2 is returned to the step b and reused.

[0059] Through calculation, it is ascertained that 1.48 kg PbO product is obtained finally through the above-mentioned overall circulation process, the purity of the PbO product is 99.98%, and the comprehensive recovery rate of Pb is 99.4%.

Embodiment 2

[0060] 12% KOH solution is used as the pre-desalting alkaline liquor, and the desalting temperature is 40° C. In the step a, 0.75 mol/L ethylene diamine water solution is used as the complexing agent, and 13 g CuO is used as the catalyst; in the step b, SO.sub.2 is used in replacement of CO.sub.2. The rest conditions are the same as those in the embodiment 1. The purity of the PbO obtained finally is 99.97%, and the comprehensive recovery rate of Pb is 99.6%.

Embodiment 3

[0061] In the step a, 1 mol/L ethylene diammine diacetate water solution is used as the complexing agent, and 5 g silver nitrate is used as the catalyst; in the step b, SO.sub.3 is used in replacement of CO.sub.2. The rest conditions are the same as those in the embodiment 1. The purity of the PbO obtained finally is 99.96%, and the comprehensive recovery rate of Pb is 99.5%.

Embodiment 4

[0062] In the step a, 0.5 mol/L ethanolamine, di-ethanolamine, tri-ethanolamine, ethylenediamine tetraacetic acid, propanediamine diacetic acid or a sodium salt of it, iminodiacetic acid or a sodium salt of it, and alginic acid or a sodium salt water solution of it are used as the complexing agent in turns; independently, Ni or Ag metal powder, or a chloride of the metal powder is used as the catalyst in the step a. The rest conditions are the same as those in the embodiment 1. The purity of PbO obtained finally is always 99.96% or higher, and the comprehensive recovery rate of Pb is always not lower than 99.5%.

Embodiment 5

[0063] Lead paste obtained by crashing and separating waste commercial 12V, 100 Ah valve-regulated sealed lead-acid batteries with a conventional method and desalted with alkaline liquor is used. The treating process is as follows: [0064] a. 1 kg desalted lead paste is added into a first reactor (10 L), lead powder is added in an excessive amount into the reactor, 40-50 g nickel chloride and 1 mol/L lysine solution are added, and the mixture is stirred for 1 h at 50° C. constant temperature. The mixture obtained through the reaction is filtered and separated, to obtain lead-containing solution and filter residue. [0065] b. The lead-containing solution obtained in the step a is transferred into a second reactor (10 L), SO.sub.2 gas is charged in an adequate amount continuously while stirring at 50° C. constant temperature, till no precipitate is generated anymore. The solution is filtered, to obtain PbSO.sub.3 precipitate and filtrate that contains regenerated lysine, wherein, the filtrate is returned to the step a and reused. [0066] c. The obtained PbSO.sub.3 precipitate is transferred into a calcinator, and is calcined for 1 h at 350° C., to obtain PbO product and SO.sub.2, wherein, the SO.sub.2 is returned to the step b and reused.

[0067] Through calculation, it is ascertained that 1.49 kg PbO product is obtained finally through the above-mentioned overall process, the purity of the PbO product is 99.97%, and the comprehensive recovery rate of Pb is 99.3%.

Embodiment 6

[0068] Lead paste obtained by crashing and separating waste commercial 12V, 55 Ah valve-regulated sealed lead-acid batteries with a conventional method and desalted with alkaline liquor is used. The treating process is as follows: [0069] a. 1 kg desalted lead paste is added into a first reactor (10 L), lead powder obtained by crashing lead-containing plate grating with a conventional method is added in an excessive amount into the reactor, and then 13 g CuO and 2.5 mol/L propylene diacetic acid −0.3 mol/L histidine solution are added, and the mixture is stirred for 50 min. at 50° C. constant temperature. The mixture obtained through the reaction is filtered and separated, to obtain lead-containing solution and filter residue. [0070] b. The lead-containing solution obtained in the step a is transferred into a second reactor (10 L), CO.sub.2 gas is charged while stirring at 50° C. constant temperature, till no precipitate is generated anymore. The solution is filtered, to obtain PbCO.sub.3 precipitate and filtrate that contains regenerated propylene diacetic acid and regenerated histidine, wherein, the filtrate is returned to the step a and reused. [0071] c. The obtained PbCO.sub.3 precipitate is transferred into a calcinator, and is calcined for 1 h at 400° C., to obtain PbO product and CO.sub.2, wherein, the CO.sub.2 is returned to the step b and reused.

[0072] Through calculation, it is ascertained that 1.48 kg PbO product is obtained finally through the above-mentioned overall process, the purity of the PbO product is 99.98%, and the comprehensive recovery rate of Pb is 99.93%.

Embodiment 7

[0073] Lead paste obtained by crashing and separating waste commercial 12V, 12 Ah valve-regulated sealed lead-acid batteries with a conventional method is used. 1 kg lead paste is taken and desalted with the same alkaline liquor as that used in the embodiment 1, to obtain pre-desalted lead paste. Then, the following treating process is executed: [0074] a. The pre-desalted lead paste is added into a first reactor (30 L), lead powder obtained by crashing lead-containing plate grating with a conventional method is added in an excessive amount into the reactor, and then 5 g silver nitrate and 2.0 mol/L glucosaminicacid solution are added, and the mixture is stirred for 120 min. at 65° C. constant temperature. The mixture obtained through the reaction is filtered, to obtain lead-containing solution and filter residue. [0075] b. The lead-containing solution obtained in the step a is transferred into a second reactor (25 L), 6 mol/L dilute sulfuric acid is added in an stoichiometric amount while stirring at 65° C. constant temperature, till no precipitate is generated anymore. The solution is filtered, to obtain PbSO.sub.4 precipitate and filtrate that contains regenerated glucosaminicacid, wherein, the filtrate is returned to the step a and reused. [0076] c. The obtained PbSO.sub.4 precipitate is transferred into a calcinator, and is calcined for 1 h at 350° C., to obtain PbO product and SO.sub.3 gas, wherein, the SO.sub.3 gas is dissolved in water to obtain dilute sulfuric acid, which is then returned to the step b and reused.

[0077] Through calculation, it is ascertained that 1.49 kg PbO product is obtained finally through the above-mentioned overall process, the purity of the PbO product is 99.99%, and the comprehensive recovery rate of Pb is 99.94%.

Embodiment 8

[0078] Anode lead paste obtained by crashing and separating waste commercial 12V, 14 Ah valve-regulated sealed lead-acid batteries with a conventional method is used. 1 kg lead paste is taken and desalted with the same alkaline liquor as that used in the embodiment 1, to obtain pre-desalted lead paste. Then, the following treating process is executed: [0079] a. 1 kg desalted lead paste is added into a first reactor (30 L), 100 ml 10 wt % H.sub.2O.sub.2 solution is added into the reactor first, and then 350 g lead powder, 5 g copper sulfate and 2.2 mol/L glucosaminicacid solution are added, and the mixture is stirred for 120 min. at 70° C. constant temperature. The mixture obtained through the reaction is filtered, to obtain lead-containing solution and filter residue. [0080] b. The lead-containing solution obtained in the step a is transferred into a second reactor (25 L), CO.sub.2 gas is charged in an adequate amount while stirring at 65° C. constant temperature, till no precipitate is generated anymore. The solution is filtered, to obtain PbCO.sub.3 precipitate and filtrate that contains regenerated glucosaminicacid, wherein, the filtrate is returned to the step a and reused. [0081] c. The obtained PbCO.sub.3 precipitate is transferred into a calcinator, and is calcined for 1 h at 440° C. under a reduced pressure, to obtain PbO product and CO.sub.2 gas, wherein, the CO.sub.2 gas is returned to the step b and reused.

[0082] Through calculation, it is ascertained that 1.59 kg PbO product is obtained finally through the above-mentioned overall process, the purity of the PbO product is 99.99%, and the comprehensive recovery rate of Pb is 99.95%.

[0083] While the present invention is described above exemplarily in some preferred embodiments, apparently the present invention is not limited to the above-mentioned embodiments. Various equivalent modifications can be made to the technical scheme of the present invention within the scope of the technical concept of the present invention, and those equivalent modifications belong to the protection scope of the present invention. For example, though some complexing agents are described exemplarily with several ammonia carboxylic compounds, the object of the present invention can be attained with other ammonia carboxylic compounds equivalent to those ammonia carboxylic compounds, such as amino acid substances. Such examples are not described here exhaustively, to avoid unnecessary repetition.

[0084] In addition, it should be noted that the technical features described in the above embodiments can be combined separately, as long as they are within the scope of the technical ideal of the present invention.