JPH02205249A - Production of grid body for lead storage battery - Google Patents

Abstract

PURPOSE:To safely, surely and inexpensively produce the defectless grid body for lead storage batteries by adding a mixture contg. lead selenide, etc., formed on the surface of a molten metal mixture composed of lead and selenium and casting the grid body while holding the mixture on the surface of the molten metal. CONSTITUTION:The lead or lead alloy and the selenium alone or the selenide are mixed ana melted. The mixture consisting of the lead selenide, lead oxide, metal lead, etc., formed on the surface of the molten metal at this time is charged into water and is ground and crushed. This mixture is then added to the lead alloy consisting of a lead/antimony alloy for casting the grid. The mixture is so floated on the surface of the above mentioned molten lead alloy so as to cover the entire surface and is held for a required period of time. The required amt. of the selenium is thereby incorporated into the above- mentioned lead alloy without generating harmful gases. The grid body for lead storage batteries is cast by using this molten metal without generating cracks, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an improvement in a method for manufacturing a grid for lead-acid batteries, particularly for lead-acid batteries.
This invention relates to a method for preventing lattice cracking during casting by adding selenium to an antimony-based alloy.

Conventional technology and its challenges Traditionally, grids for lead-acid batteries contain about 3 to 6% by weight of antimony.
A lead-antimony alloy containing (hereinafter expressed in %) is used. Although batteries using such alloys have excellent performance during deep charge/discharge cycles, they have the disadvantage that antimony precipitates on the negative electrode plate, lowering the hydrogen overvoltage and increasing self-discharge and liquid loss. .

In recent years, there has been a strong demand for maintenance-free lead-acid batteries, and to this end, it has become necessary to reduce or eliminate the amount of antimony in the lattice. However, when a lead-calcium alloy is used for the positive electrode grid, problems such as poor ability to perform deep charge/discharge cycles or use at high temperatures tend to occur. Therefore, so-called low-antimony alloys containing a reduced amount of antimony have been proposed. However, when the amount of antimony in the lattice is reduced, especially when the amount of antimony becomes 3% or less, cracks are likely to occur in the girder during casting. This not only significantly reduces the productivity during grid casting, but also causes the parts to be easily cut off due to vibration and corrosion, causing deterioration of the battery. Therefore, for example, in Japanese Patent Application Laid-Open No. 48-49621,
It has been proposed to add selenium to prevent such cracking.

In addition to low antimony alloys, we also offer antimony 4-6
%, cracks may occur depending on the shape of the lattice, casting conditions, etc. However, one culm of the general lattice currently used is
After melting lead metal or waste lead, etc., and further melting antimony and arsenic metal, etc. to form a predetermined alloy composition, -
A method is adopted in which the lattice is deposited in an ingot and the ingot is melted again as necessary to cast a lattice.

Therefore, there is no problem if selenium is added to all antimony alloys at the time of formulation, but selenium is expensive.
When the antimony content is 4 to 6%, cracks and the like often do not occur, so selenium is added to not only low-antimony alloys but also antimony alloys with relatively high antimony content during formulation. It is extremely uneconomical to do so.

Means for Solving the Problems The present invention involves mixing and melting lead or lead alloy and selenium alone or a selenium compound, and then melting the mixture of selenized buttons, button oxides, metallic lead, etc. produced on the surface of the molten metal into a lattice. This is a method for manufacturing a grid for lead-acid batteries, characterized in that the mixture is added to a lead alloy for casting, and the grid is cast while holding the mixture on the surface of the molten lead alloy for grid casting, and the method is characterized in that it prevents cracks in the S-made grid. It is an object of the present invention to provide a method for adding selenium in an amount sufficient to prevent the above problems when necessary, reliably and inexpensively during lattice casting.

Example Hereinafter, the present invention will be explained in detail with reference to Examples.

First, a mixture of lead selenide, lead oxide, metallic lead, etc. was manufactured by the following method.

The molten lead or molten lead alloy was maintained at 400°C, and heselen (purity 99.999%) was gradually added thereto. After that, stir it thoroughly and selenium button and lead oxide will be formed.

A mixture of metallic lead and other substances was generated on the surface of the molten lead. melt
Table 1 shows the analysis results of the selenium content in the mixture and in the molten lead when pure lead, antimony alloy, and dead lead were used as the molten lead alloy in the lead pot.

Table 1 Because harmful gases are generated when adding selenium, a furnace with sufficient exhaust equipment was used.

This time, the molten metal temperature was kept at 400°C, but any temperature that melts the lead is fine. However, if the temperature is too high, the oxidation of the lead itself will be accelerated, more selenium dioxide will be generated, and the yield will be poor. In reality, there are problems such as 35
0 to 450°C is preferred. Although high purity selenium was used in this test, unrefined selenium may be used if high purity is not required and mass production is performed.

As can be seen from the analysis results in Table 1, the selenium content in the molten metal was 0.011 to 0.033%, while that in the mixture was 4.9 to 1.3%. Approximately 2 in the molten metal
It was more than 00 times.

Next, in order to facilitate handling, the high-temperature mixture formed on the molten metal was gradually poured into a groove filled with water to crush it. The method of crushing is not limited to the above-mentioned water crushing, but may also include mechanical crushing or other crushing methods.

Next, using the above mixture, selenium was added to the lattice by the method shown below.

The mixture produced in No. 3 of Table 1 (Pb-7
, 3% Se) in a casting furnace.
%Sb).

B (Pb-2,2% 5b-0,25%As-0,1
%5n-0,03%Cu-0,005%S) was floated on the surface so as to cover the entire surface, and after about 20 minutes, a lattice was cast. The furnace temperature at this time was maintained at 400°C. Table 2 shows the selenium content and failure rate in the lattice at this time, comparing those with selenium added at the time of ingot preparation and those with no selenium added.

As is clear from Table 2, the selenium content in the woven lattice according to the present invention was comparable to that obtained by the conventional method, and the defective rate was almost the same as that obtained by the conventional method.

Further, when adding the mixture, no harmful gas was generated and there were no sanitary problems.

In Table 2, in addition to these, selenium master alloy (usually selenium 0.5~
A conceivable method is to add selenium during ingot casting or lattice casting. When producing a selenium master alloy, selenium alone or selenium compounds are directly added to molten lead or molten lead alloy, but the solubility of selenium in the button is low, so it is necessary to raise the temperature of the molten metal considerably in order to add the required amount. Therefore, oxidation of the molten metal and oxidation dissipation of selenium are significant, resulting in not only a poor yield but also a considerable increase in energy costs. For these reasons, the method using a selenium master alloy has the disadvantage of being too costly.

It goes without saying that the method according to the present invention can also be applied to casting lead alloy parts such as balls and bushings.

Effects of the Invention As detailed above, according to the present invention, it is possible to safely, reliably, and inexpensively contain selenium in a fishing lattice as required, and it is possible to manufacture a sound cast lattice. The value is enormous.

Claims (1)

[Claims] 1. In the production of grids for lead-acid batteries using lead-antimony alloys, lead or lead alloys and selenium alone or selenium compounds are mixed and melted, and lead selenide and lead oxide are produced on the surface of the molten metal. A method for producing a lattice body for a lead-acid battery, characterized in that a mixture of metal lead or the like is added to a lead alloy for lattice casting, and the lattice body is cast while holding the mixture on the surface of the molten lead alloy for lattice casting.