JPS62120436A - Wet recovery of lead contained in paste of waste battery - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a wet processing method for electrolytically extracting lead from desulfurization paste of waste batteries.

[Conventional technology]

According to various desulfurization methods of pastes, waste battery sludge is treated with alkali metal or ammonium carbonates to remove not only the mixture of insoluble lead compounds but also all the sulfur into soluble alkali metal or ammonium sulfates. A solution containing it as a salt is obtained. This mixture of lead compounds was separated from the solution described in 1. by washing thoroughly with water.

Sulfur components are substantially removed.

The above mixture is easily reduced using coal at relatively low temperatures (800-900 DEG C.) without substantial release of sulfur dioxide and without producing lead glue.

Therefore, at present, the method for reducing the above-mentioned products by pyrometallurgy is most frequently used. This method also has high production rates, long life of the reduction furnace and.

It has advantages such as high yield of extracted lead.

However, pyrometallurgy of lead-containing materials requires special care during transportation or charging into the furnace.

Additionally, similar furnaces have the potential to emit smoke and volatile dust.

2 Extensive and expensive systems for monitoring lead contaminants on the work premises or around the factory;

It becomes necessary to provide a large effective filtration plant. For this reason, pyrometallurgical processing should be replaced as a method for recovering lead in paste as metal.

Particularly important are processing methods which operate in a completely hydrometallurgical manner, such as extraction processing methods by electrolysis or electrowinning.

The average composition of the desulfurization paste is as follows.

Lead carbonate (Pbco3) 50-52 Lead sulfate (PbSO4) 2.5-4 Lead peroxide (P
bO2) 14-16 Lead thioxide (PbO) 11-12% Lead metal (
As is known, the practical problem with the hydrometallurgical treatment of paste from 5-7% worn-out waste batteries is that all of the compositional components in the mixture, especially lead peroxide (Pb02), which is present in a large proportion. ) in the solution selected for electrolysis.

actually.

The residue of acid dissolution of the mixture must not constitute an unacceptable lead loss.

On the other hand, as is well known, lead peroxide is insoluble in ordinary acids suitable for electrolysis processes, so if no pretreatment is carried out to reduce the lead peroxide, the acid dissolution of the mixture will be difficult. The residue is highly lead-rich and must be returned to dry recovery.

According to the prior art, dissolving all the constituents of the paste in four different electrolytes is carried out by one different method.

The prior art documents are listed below in chronological order.

US Patent IJ 48,062 to C.E. Tucker shows heating battery sludge to convert PbO2 to soluble PbO and Pb2O.

U.S. Patent 1,752,356 by W.C.Sm1th
From the viewpoint of alkali treatment, the paste is heated in a reducing atmosphere (to generate lead oxide) in order to solubilize PbO2.

U.S. Patent No. 1,911,6 by J. H. Calbeck
04 is for leaching the battery paste with a sodium acetate solution. In electrolytic solutions, lead oxide and sulfate are soluble, whereas lead peroxide is usually insoluble.

However, in the presence of lead metal and in the above-mentioned electrolytic solution, two local cyni bonds are formed, so that lead peroxide and an equivalent amount of lead metal are dissolved.

U.S. Patent 4,107 by A.F. Gyumann
, 007, the paste is leached with a concentrated solution of alkali metal hydroxide to which sugar honey or raw sugar is added.

According to this method, lead oxide and lead sulfate are dissolved and can be subjected to electrolysis. The behavior of pbo2 is not described in detail.

U.S. Pat. No. 4,229 to R.D. Pregman,
271 is a method a for erasing lead peroxide from paste;
Customary acids in the electrowinning process
Two methods are proposed: one method for completely dissolving 2-st in acids).

Here, method a means that after drying the paste at 100°C,
It is roasting in a reducing atmosphere at a temperature range of 0 to 325°C.

The method consists in treating the R-st suspension water with sulfur dioxide or with alkali metal or ammonium sulfites or bisulfates.

U. I) U.S. Patent No. 4,460 by caceLt7,
422 has the property of completely dissolving in a thermally concentrated solution of fluoroboric acid or fluorosilicate. Reacting the paste.

A, Y, Lee and E, R, Cole of the Minerals Bureau are R,
No. 1,8857 suggests two methods for the reduction of lead peroxide contained in pastes.

One is by adding lead powder during the leaching process of the silicon fluoride, which has already been desulfurized with ammonium carbonate.

On the other hand, during the desulfurization treatment with ammonium carbonate.

This method involves the addition of ammonium bisulfate.

[Problems with conventional technology]

The method of thermal reduction of 13b02 in the above reducing atmosphere is as follows.

It has the disadvantage that it requires a two-step cycle of drying and reduction roasting. These processing steps not only require tight control of the operating conditions, but also require the use of equipment (furnaces or torrefaction furnaces) with suitable dust evacuation equipment. However, even if the temperature is low, the diffusion of dry substances will cause pollution. What is the reduction method during high temperature melting?

Add lead powder, but include transfer to convert some of the lead produced into powder. As a result, this method...

It becomes expensive.

Sulfur dioxide, sulfite or before carbonation.

The bisulfate reduction method is quite costly due to the two reactants, but more importantly it increases the consumption of carbonate for desulfurization by about 25 tons. The expenditure corresponding to the consumption of this carbonate is not negligible2, and today the expenditure on carbonate is the most expensive item among the individual expenditures in the entire process.

An object of the present invention is to solve the above-mentioned problems regarding the wet treatment process by electrolytic extraction of desulfurization paste of waste batteries.

[Means for solving problems]

In order to achieve the objects of the present invention, the present invention uses lead in a waste battery paste, that is, a desulfurization paste, as a pure metal,
The method of extraction by electrolysis is characterized by the following steps.

a) A leaching step in which the paste is leached with an aqueous solution of an acid selected from those suitable for electrowinning.

b) Treatment of the leached waste with hydrogen peroxide, with the following reaction, so that all of the lead peroxide contained in the leached waste reaches quantitative reduction: Process.

(1) pb 11I202 ++-> Pb
10o2+2r(2) Pb +Pb --->
2Pb''C) A separation step in which the solid residue is separated from the obtained lead solution by 9 to directly provide it to electrolytic extraction of lead.

The process steps of the present invention will now be substantially defined and the foregoing will be explained in more detail.

The starting material in this process is a paste separated from used waste batteries. The paste has already been subjected to υ desulfurization treatment by known means.

This material is preferably fluoroboric acid or.

A lead compound suitable for subsequent electrowinning, such as fluorosilicic acid, and specifically just enough hydrogen peroxide to achieve maximum solubilization of the lead peroxide and lead metal is added.

During acid treatment of the desulfurized paste, hydrogen peroxide undergoes a chemical reaction (1).

Pb 10H2o2−->pb + 02+ 2H
(1) Therefore, all of the lead peroxide is reduced to lead oxide.

It is then dissolved in acid.

A large amount of oxygen (02) is liberated during the chemical reaction (1).

It physically activates the lead metal molecules present in K-st to easily cause the following chemical reaction (2).

Pb + Pb ---> 2Pb2+ (2) and the proper particle size (rightgrain) while saving hydrogen peroxide corresponding to the lead ions (Pb'') to be reduced.
All of the lead metal with ul ome try is dissolved.

After acid leaching with the addition of hydrogen peroxide, the organic matter of the desulfurized paste (separator flakes and nitride) is removed.

fibers, etc.) and lead sulfate that was not converted in the desulfurization stage remain undissolved.

After the reaction, the melt and solids are separated by filtration. The solid residue after filtration contains only 50% of the lead present in the starting material, and after roasting to destroy organic matter,
It can be returned to the desulfurization stage.

The filtered solution contains lead in ionic form and generally does not require any purification. This is because it is identical to the lead powder and is activated by the oxygen generated in the chemical reaction (1) and dissolved during acid leaching with a small amount of impurities. This is because a substitution reaction (so-called ``cementesicone'') takes place.

This self-purified solution can then be directly subjected to electrowinning of lead. This electrolytic extraction.

It is carried out in a conventional battery having an anode made of insoluble graphite and a cathode made of a thin lead plate.

By operating under suitable conditions, very high quality and pure cathodic deposits can be obtained, with pBO at the anode
Precipitation of 2 is almost prevented.

In rare cases, a small amount of PbO2 is formed unavoidably.

It must be returned to the acid leaching process with hydrogen peroxide. The cathode material is refined into crude lead and sold commercially as electrolytic lead. The solution that was electrolyzed.

The paste is returned to the acid leaching process.

〔Example〕

980 g of well-washed desulphurization paste (in dry matter,
It consists of Pb 70.5chi, Sb 0.68chi, SO, 18chi. ) was leached with 5 tons of spent electrolyte from electrowinning. This electrolyte.

49.9/l Pb” 139 jl/l free HBF'4 Contains.

After stirring for 30 minutes at 50° C., hydrogen peroxide (35% solution) was added to a 4.6% amount of treated paste and allowed to react for more than 30 minutes.

The following substances were separated by filtration.

80 g of insoluble residue, its composition is.

Pb 34.2chi Sb 2.4chi 8 2.2 Section and 51. of lead-containing electrolytes. It has the following tena:

181.5. q/l Pb- 0.6jj/l Sb+0 25.19/l free HBF4 Extract 96o1 of lead Vt, t contained in the paste by leaching with fluoroboric acid and hydrogen peroxide. It was done. All of the sulfur remains in the residue.

For electrowinning in a battery having a graphite anode previously coated with pbo2 and a thin plate cathode of electrolytic lead, by using 5 tons of lead-containing electrolyte, 630 g of cathode lead,
9. to the anode. ! iI of PbO2 was produced.

What about batteries? 7A # operated at 2.5V for 24 hours.

Cathode current density is 28OA/m2, current efficiency >,
1. ! +7%.

The refined cathode lead had the following composition.

Sb < 0.001 As < 0.001 Sn < 0.001 Bi < 0.002 Cu = 0.0003 Ag < 0.0005 The spent electrolyte should be returned to the leaching process for new paste.

53g/l Pb++ 131 g/l free HBF4 Contains.

FIG. 1 is a block diagram showing one example of the processing steps of the present invention.

〔Effect of the invention〕

In general, according to the present invention, the use of hydrogen peroxide for the reduction of lead peroxide (Pb02), compared to other reducing agents used in conventional methods, provides the following effects: .

■ Shows no toxicity.

■ Foreign ions are not supplied to the solution to be subjected to electrolysis, and the solution can be continuously regenerated.

■ It is a reactant that can be easily obtained from the market.

The price is also not that high.

■ You can measure accurately without waste. This is because the reduction of lead peroxide (Pbo2) is stopped when the suspension is reddish brown (b
brown-rea to brown-gray
This is because knowledge can be gained from sudden changes in ). This color change.

It can be easily detected visually.

■ At least 95% in the extraction of lead (Pb) with the consumption of 4-5 liters of hydrogen peroxide (H2O2) in 35 liters of solution.
The following yields are achieved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the processing steps of the present invention.

Claims (1)

[Claims] 1. A wet recovery method for recovering lead from waste battery paste or desulfurization paste as a pure metal by electrolytic extraction, comprising: a) an acid selected from acids suitable for electrolytic extraction; a leaching step of leaching the paste with an aqueous solution, and b) until reaching the total quantitative reduction of lead dioxide contained in the leached paste: (1) Pb^4^++H_2O_2-- −→Pb^2^
+O_2+2H^+ (2) A treatment step of treating the leached paste with hydrogen peroxide with the reaction of Pb+Pb^4^+----→2Pb^2^+; and c) the resulting lead dissolution. 1. A wet recovery method for lead contained in waste battery paste, comprising a separation step of separating a solid residue from a liquid so that it can be directly subjected to electrolytic extraction of lead. 2. In the wet method for recovering lead contained in waste battery paste as set forth in claim 1, the above treatment step (b)
The above reaction (1) is caused by the oxygen generated from the above reaction (1).
2) A wet recovery method for lead contained in waste battery paste, characterized by activating. 3. In the wet recovery method for lead contained in the paste of waste batteries as set forth in claim 2, the cementation action for impurities is simultaneously carried out by the above reactions (1) and (2). A wet recovery method for lead contained in waste battery paste, characterized in that the process is caused by the metal lead (Pb) being physically activated by the generated O_2. 4. In the wet recovery method for lead contained in the paste of waste batteries as set forth in claim 1, the above-mentioned A waste battery paste characterized by adding a solution treatment step of treating the lead solution in the separation step, and e) a regeneration step of regenerating the waste electrolyte in the solution treatment step by returning it to the leaching step. Wet recovery method for lead contained in 5. The wet recovery method for lead contained in the paste of waste batteries as set forth in claim 1, characterized in that the acid in the leaching step is fluoroboric acid or fluorosilicic acid. A wet recovery method for lead contained in waste battery paste.