JP2006073445A - Processing method of dump liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of eliminating the problem of environmental pollution caused by disposal of dump liquid which is electrolyte liquid containing free sulfuric acid exhausted after chemical treatment at manufacturing process of a lead-acid storage battery, by re-using the dump liquid as electrolyte liquid for chemical reaction or by processing it so as to be used as an electrolyte liquid for manufacturing a battery. <P>SOLUTION: The processing method of the dump liquid is to apply a heat treatment such as boiling treatment or/and steam blowing treatment by an electric heater or the like on the dump liquid exhausted after applying chemical treatment on non-treated positive and negative electrode plates during a manufacturing process of the lead-acid battery, and evaporating and removing almost all of acetic acid and formic acid dissolved and dispersed in the dump liquid after the chemical treatment. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for treating a dump solution for utilizing a dump solution that is eliminated after a chemical conversion treatment in the production process of a lead storage battery.

Conventionally, chemical conversion treatment of unformed positive and negative electrode plates is performed in the manufacturing process of sealed or liquid lead-acid batteries, but the free sulfuric acid electrolyte solution, that is, the dump solution that has been eliminated after the chemical conversion treatment, is discarded. However, not only because of its strong acidity but also because it contains lead and carbon, in view of the problem of environmental pollution caused by discarded dump liquid, in order to prevent this, for example, JP-A-2003 The invention of JP-7330 is proposed.
In the present invention, since lead and carbon contained in a dumping solution that has been disposed of in the past are originally contained in a lead storage battery, even if such dumping solution is reused as a sulfuric acid electrolyte for chemical conversion, lead is used. From the standpoint that it does not have any adverse effect on the storage battery, in performing battery case formation, the dump liquid removed after battery case formation of other batteries is used as the electrolyte for battery case formation of the battery. Thus, the invention has been proposed in which the environmental pollution problem due to the disposal of the dump solution is solved and at the same time the dump solution can be reused as the electrolytic solution for forming a battery case.
JP 2003-7330 A

However, according to the invention proposed in the above-mentioned Patent Document 1, by reusing the dump liquid as described above, the problem of environmental pollution is solved. When reusing, the liquid lead-acid battery manufactured by injecting a new regular sulfuric acid electrolyte by the return liquid method after reuse was found to cause corrosion in the positive electrode terminal portion during use. When the cause was investigated, acetic acid and formic acid equivalent to the chemical conversion treatment sulfuric acid were generated during the chemical conversion treatment, and these organic acids are contained in the dump liquid discharged after the chemical conversion treatment. Even if it is discharged after being reused as an electrolyte, a part of the electrolyte for chemical conversion treatment containing these organic acids adheres to the electrode plate group and remains in the battery. When a liquid lead-acid battery is manufactured by injecting a normal sulfuric acid electrolyte, these organic acids corrode the positive electrode terminal part during its use, impeding the operation of the battery, shortening the service life, etc. It was found to bring about evils.
Further, when the reuse of the dump solution is repeated as described above, the content of these organic acids in the dump solution increases with an increase in the number of repetitions, and thus the above-described adverse effects may become more prominent. found.
In view of the above, an object of the present invention is to eliminate the problem of environmental pollution without discarding the dump solution, and to solve the above problem, and at the same time, reuse it as an electrolytic solution for chemical conversion treatment. Or providing a method for treating a dump solution that can be used as an electrolyte of a battery to be manufactured.

  The present invention relates to a dump liquid characterized in that after the chemical conversion treatment in the production process of the lead storage battery, after the chemical conversion treatment of the lead storage battery, the dump liquid discharged from the lead storage battery is boiled or / and steam injected. It exists in the processing method.

  By the above treatment according to claim 1, most of acetic acid and formic acid contained in the dump solution can be removed by evaporation, and the obtained treated dump solution can be reused for the chemical conversion treatment. Can be used in place of the newly injected electrolyte in conventional lead-acid batteries, eliminating the conventional problems that have caused corrosion of the positive electrode terminal by these organic acids, and converting the lead-acid battery The lead storage battery can be manufactured stably and satisfactorily.

Next, an embodiment of the present invention will be described in detail.
According to the present invention, the chemical conversion treatment of the unformed positive and negative electrode plates may be either tank formation or battery case formation. In the chemical conversion treatment, battery case chemical conversion which is generally preferably used is performed, and this will be described in detail as an example.

  After assembling the electrode plate group with unformed positive and negative electrode plates and storing it in the battery case, a predetermined amount of sulfuric acid electrolyte solution having a specific gravity of 1.15 to 1.25 (20 ° C.) is injected into the battery case. Then, the battery case chemical conversion treatment is performed by energizing with a predetermined current for a predetermined time according to a conventional method. After the battery case formation is completed, the lead storage battery is turned upside down to discharge (dump) the free electrolyte, and the dump solution is collected in a glass or metal container suitable for heat treatment.

  During the chemical conversion treatment, a penetrant contained in the polyethylene separator constituting the electrode group of the lead storage battery, for example, a dialkylsulfosuccinic acid-based surfactant diffuses into the electrolytic solution and undergoes anodization to produce acetic acid. Alternatively, acetic acid and formic acid contained in lignin, which is an additive for the negative electrode, are dissolved in the sulfuric acid electrolyte. Therefore, acetic acid and formic acid are contained in the collected dump solution. On the other hand, at the same time, a part of the electrolyte containing these organic acids remains in the electrode plate group in the dumping operation.

Thus, when such dump solution is reused as an electrolytic solution for chemical conversion treatment, the solubility of lead is increased by these organic acids contained, and in the positive electrode, the dense lead dioxide protective film on the surface is destroyed. It was recognized that this would cause inconvenience.
If the dump solution containing such organic acid is repeatedly reused as an electrolyte for chemical conversion treatment of other batteries, the concentration of these organic acids in the dump solution increases with the increase in the number of times, and the above disadvantages are caused. To be promoted.
In addition, since the electrolyte solution containing a large amount of organic acid that is not discharged remains attached to the electrode plate group of the battery after the chemical conversion treatment is completed with the dump liquid that has been repeatedly reused, this battery is a sealed lead-acid battery. In some cases, the operation of the battery is inconvenient. In addition, when a new regular electrolyte solution is injected into this battery to form a liquid lead battery, residual organic acids are collected particularly on the electrolyte surface, and especially the lower part of the positive electrode terminal is overcharged during use. Corrosion is caused by the oxygen gas generated from time to time, and further corrosion progresses, causing inconvenience of breaking.
Such an inconvenience is more likely to occur as the dump liquid is repeated more frequently.

  In order to solve such a problem, the dump liquid was passed through the activated carbon layer to adsorb and remove these organic acids. However, the working efficiency was poor and troublesome, and a part of useful sulfuric acid was also adsorbed and removed. It was accompanied by inconvenience such as.

  Thus, the inventors of the present application have made extensive studies on means suitable for reusing the dump solution as an electrolytic solution for chemical conversion treatment at high efficiency and at a low cost, or using it instead of a regular sulfuric acid electrolytic solution. However, by heating the dump solution, these organic acids can be efficiently evaporated and removed in a short time, and the organic acid suitable for the above-mentioned purpose of use is almost removed. It was found that it can be.

  Acetic acid and formic acid dissolved and dispersed in the dump solution after the chemical conversion is a lower fatty acid and is a weak acid that is very weak compared to dilute sulfuric acid, so that protons are not ionized in the dump solution, so-called free state. is there. Moreover, since these organic acids have a lower vapor pressure than water and sulfuric acid, they easily evaporate if the dump liquid is boiled. In addition, by blowing water vapor generated by boiling water into the dump liquid, it is possible to promote efficient evaporation particularly for the organic acid dispersed in the liquid, and at the same time, water that evaporates simultaneously by blowing water vapor. In order to prevent the concentration of the dump liquid due to water evaporation, the dump liquid can be processed without a large change in the concentration of sulfuric acid in the dump liquid. It is possible to save the labor of adjusting the amount of water so that the sulfuric acid concentration can be reused.

As the heat treatment means for the dump liquid, boiling treatment alone, steam blowing treatment alone, or combined use of boiling treatment and steam blowing treatment can be considered. As the heater, an electric heater, a gas heater or the like is used to heat the container containing the dump liquid. Heating by blowing water vapor, for example, water vapor generated by boiling water in the kettle is performed with the end of the conduit inserted into the dump liquid in a container containing the dump liquid.
The heat treatment of the dump liquid may be performed for each dump liquid discharged after completion of the chemical conversion treatment, but if it is performed at once by collecting it in a heat treatment container that can store a plurality of dump liquids. It is preferable in terms of efficiency. Of course, in order to recycle a large amount of the treated dump liquid from which the organic acid has been removed, it can be reused in several batches.

  A predetermined amount of sulfuric acid electrolyte adjusted to a specific gravity suitable for battery case formation is poured into the battery case of a lead storage battery containing unformed positive and negative electrode plates to be formed into a battery case. After the formation of the battery case, the free electrolyte is recovered in a heat treatment container of an appropriate size by dumping, and this is immediately heated by the heating means described above, and the organic acid is removed by evaporation. A treated dump solution consisting of a good quality sulfuric acid electrolyte, which is almost the same as a new regular sulfuric acid electrolyte, with almost no acid removed, is obtained. Thus, it can be reused for forming a battery case, or can be used as it is, or after adjusting the specific gravity as needed, instead of the sulfuric acid electrolyte for producing a liquid lead-acid battery. When the treated dump solution is reused for battery case formation, the specific gravity is adjusted to a specific gravity suitable for the conversion electrolyte as necessary.

Next, more detailed examples will be described in detail.
Example 1
Prepare 9 lead acid batteries each containing an electrode plate group consisting of unformed positive and negative electrode plates with sulfuric acid electrolyte with a specific gravity of 1.190 (20 ° C). After injecting a predetermined amount and carrying out a battery case chemical conversion treatment by a conventional method, each of the batteries is turned upside down to discharge the released electrolyte solution into each beaker, and a specific gravity of 1.230 (20 ° C.) is placed in each beaker. 500 cc of the dump liquid was recovered.
Next, out of the 9 beakers with 500 cc of dump liquid, the dump liquid in one beaker is left as it is, and the remaining 8 dump liquid beakers are blown with 100 ° C. water vapor. In this case, as shown in Table 1 below, the evaporation time of the organic acid was removed by changing the treatment time for each beaker. Thus, nine types of dump liquid samples A to I were obtained.
In order to analyze the amount of organic acid for each of the nine types of dump liquid samples A to I thus obtained, 50 g of each dump liquid was steam distilled, 100 cc of each distillate was sampled, and these were made hydrophobic. The concentration of formic acid and acetic acid was measured by ion chromatography using a neutral anion exchange column. The measurement results were as shown in Table 1. In Table 1, the reference electrolytic solution means a normal electrolytic solution for forming a battery case prepared by diluting concentrated sulfuric acid with water to a specific gravity of 1.230 (20 ° C.). Also for this control electrolyte, the contents of acetic acid and formic acid were measured for 100 cc of the distilled liquid by the above quantitative method. The results were as shown in Table 1. That is, it is shown that a normal chemical electrolyte contains about 0.458 ppm of acetic acid and about 0.406 ppm of formic acid.
Moreover, specific gravity was measured about these nine types of samples AI. The results are shown in Table 1. From this, it can be seen that the specific gravity of the samples B to I subjected to the steam blowing treatment is not different from the specific gravity of the sample A that is not treated, and the dump liquid is not concentrated by the steam blowing treatment.

  As apparent from Table 1 above, as shown in the dump liquid sample A that is not subjected to the steam blowing treatment, acetic acid is contained in 130.5 ppm and formic acid is contained in 143.6 ppm. As the treatment time elapses, these organic acids decrease, and in the treatment time of 30 minutes, the acetic acid content is 0.570 ppm or less and the formic acid content is 0.398 ppm or less. In the treatment time of 40 minutes or more, the acetic acid content is 0.298 ppm or less and the formic acid content is 0.232 ppm or less, which is less than the respective contents of acetic acid and formic acid in the reference electrolyte. As a result, it was confirmed that the dump solution could be reused as a battery case forming electrolyte by steam blowing treatment.

Example 2
500 cc of a dump liquid having a specific gravity of 1.230 (20 ° C.) obtained in the same manner as in Example 1 was collected in a flask having nine reflux devices, One of them is left untreated, and the remaining eight 500 cc dump liquid flasks are placed on each electric heater and boiled. The boiling point of the dump liquid was 107 ° C. It processed by changing the processing time by boiling as shown in Table 2 below from the boiling start point. Thus, eight types of dump liquid samples A ′ to I ′ were obtained in which the boiling treatment time was different at 10 minute intervals up to 120 minutes.
The contents of acetic acid and formic acid were measured in the same manner as described in Example 1 for the above nine types of dump liquid samples A ′ to I ′, and each of the dump liquid samples A ′ to I ′ was measured. The specific gravity was measured by a conventional method. The results are shown in Table 2 below.

As can be seen from Table 2, the removal effect of acetic acid and formic acid by boiling treatment is substantially the same as that of the control electrolyte, with the contents of acetic acid and formic acid being significantly reduced after 30 minutes of treatment, as in the case of steam blowing treatment. Similarly, when the treatment time is 40 minutes or more, it can be seen that acetic acid is 0.257 ppm or less and formic acid is 0.215 ppm or less, which can be significantly lower than the content of these organic acids in the control electrolyte. The dumping solution was confirmed to be suitable for reuse as a chemical electrolyte for chemical conversion.
In addition, although the specific gravity of the dump liquor is slightly changed by the boiling treatment, it can be reused as it is because it is within the range of the specific gravity of 1.150 to 1.250 which is allowed as the electrolytic solution for chemical conversion. When a reflux apparatus is not attached to the treatment, the evaporation of water increases, so that work for adjusting the specific gravity is required for reuse. In view of this point, the steam blowing treatment is preferable and advantageous.

  In addition, as another example, the steam blowing process and the boiling process may be used in combination, and as a result, as shown in Tables 1 and 2, it was confirmed that the same organic acid removal effect was brought about.

Example 3
Next, when the dump solution is reused as the chemical electrolyte and then discharged, the influence of the organic acid contained in the electrolyte remaining in the electrode plate group in the battery on the positive electrode terminal of the battery is as follows. The comparison test was conducted.
That is, each of the 40 B 19 type automobiles using the dump solution of the samples A, B, and D and the control electrolyte as the chemical electrolytes for the water vapor blowing time shown in Table 1 for 0 minutes, 10 minutes, and 30 minutes. A fixed amount of liquid was poured into the battery for chemicals, and the chemical conversion treatment was performed on these four types of batteries by a conventional method. Thereafter, the free electrolyte was discharged from each battery, and then a predetermined amount of sulfuric acid electrolyte having a normal specific gravity was poured into each battery to produce liquid lead-acid batteries A, B, D and a control battery. .
For these batteries A, B, D and the control battery, as an accelerated test for confirming the presence or absence of corrosion of the lower part of the positive electrode terminal due to the organic acid in the electrolyte, each battery was subjected to a 75 ° C. lamp discharge for 2 weeks. After discharge, a constant voltage of 14.4 V was applied at 75 ° C. for one month, and then disassembled, and the corrosion state of the lower portion of the positive electrode terminal was observed. The results are shown in Table 3.

As is clear from Table 3, the dump solution of sample A, that is, the battery A that reused the untreated dump solution, and the dump solution of sample B, that is, the battery B that reused the dump solution of water vapor treatment time 10 minutes. Then, corrosion occurred in the lower part of the positive electrode terminal, and the terminal was on the verge of breaking. On the other hand, the positive electrode terminal of the battery D in which the dump liquid of the sample D, that is, the dump liquid having a processing time of 30 minutes is reused, does not show any corrosion as in the positive electrode terminal of the control battery using the control electrolyte. It was.
The following was found from the results of the above corrosion tests.
That is, the amount of acetic acid and formic acid in the dump solution is removed by evaporation to a level substantially equal to or less than the content of acetic acid and formic acid normally contained in the control electrolyte used as a new chemical electrolyte by treatment of the present invention If treated so that it contains almost no acid, the treated dump solution can be reused as an electrolytic solution for chemical conversion. Furthermore, conventionally, after the chemical conversion treatment is completed, it has a new normal specific gravity after being discharged. It is clear that instead of injecting a specified amount of electrolytic solution, the treated dump solution is used as it is, or after adjusting the specific gravity as necessary, and then used to produce a liquid lead-acid battery. It became.
Furthermore, after the treated dump liquid is reused for the chemical conversion treatment, the dump liquid discharged after the chemical conversion treatment is completed is treated according to the present invention and reused for the chemical conversion treatment, or for the production of a liquid battery. Needless to say, it can be used.

Claims (1)

  A method for treating a dump liquid, comprising performing a boiling process and / or a steam blowing process on the dump liquid discharged from the lead battery after chemical conversion treatment of the lead acid battery.