The use of curing chambers in lead battery plants became widespread with the transition from artisanal to industrial production.

But let’s take a step back.

What is the purpose of curing in a lead-acid battery plate?

The plate curing process has been studied for practical purposes, with the aim of improving the performance parameters of battery plates.

During the curing process, the paste particles interconnect to form a strong, uninterrupted porous mass (skeleton) which, in turn, is firmly bonded to the grid.

During plate curing, the following fundamental processes take place:

  1. The skeleton (hard porous mass) of the cured paste is built. The small crystals in the paste dissolve and the large ones grow in size. The water contained in the thin liquid films between the particles evaporates, consequently the 3BS or 4BS crystals and the PbO particles interconnect into a strong skeleton.

When curing is carried out at temperatures above 80°C, the 3BS paste is converted into a cured 4BS paste.

2. The residual free lead in the paste is oxidized. This is the lead in the lead oxide that remained unoxidized during the paste preparation process.

(iv) The grid alloy oxidizes and a corrosion layer (CL) forms on the grid surface, which is firmly bonded to the cured paste.

The plate curing processes are influenced by two types of parameters:

  • Internal, i.e. paste characteristics: phase composition, density and moisture content of the paste.

  • External, i.e. characteristics of the surrounding environment: air temperature, relative humidity (RH) and air flow rate; the plate curing processes depend on the atmosphere.

The above parameters determine the water (humidity) content of the paste.

The latter, in turn, determines the rate of the basic curing processes as described above. Depending on the amount of water contained in the paste (humidity), the curing process can be divided into two phases:

(a) curing with a paste moisture content of more than 5% and

(b) drying with a moisture content of less than 5%.

To summarize,

the purpose of the curing chamber is to minimize the content of unoxidized lead in the previous processes, and to minimize the residual moisture content.

But, of course,

the plates should be cured homogeneously, otherwise the battery performance is impaired. This is where the problems related to the ‘Green Spot‘ come from.

The green spot is a sulphation of the plate and is created because there is not enough moisture in the center of the plate. This is the reason.

How to solve this problem?

The main reason is because water is used. When the chamber is filled to the maximum, the water struggles to enter every interstice of the plate, and this creates a lack of humidity in the center of the plate creating the sulphation (green spot).

Solution:

Use of steam instead of water to generate humidity inside the chamber. Steam, compared to water, has a specific weight of 0.590 kg/m3 which is 100 times lower than water at 100 °C (958 kg/m3).

In addition to the use of steam, it is essential to create a horizontal laminar flow.

Practical solution.

This type of curing chamber has been on the market for many years and is called Steam Cure. There are over 200 Steam Cure installed worldwide.

How to work a Steam Cure

If you are looking for high-level and guaranteed curing, just click on the link below and book a free consultation with a CAM expert.

https://www.cam-srl.com/get-quote/

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