Glaze Production Process in Ceramic Manufacturing

Glaze Production Process in Ceramic Manufacturing

The process of glaze preparation in a ceramics factory involves several stages: batching, milling, sieving, iron removal, quality testing, and binder addition.

Batching

Raw materials are weighed based on their required percentages and added to the ball mill. This loading process can be done either manually or automatically. In manual methods, raw materials are taken to the top platform of the ball mill and charged manually, or they are unloaded onto a belt conveyor at surface level, moved to the ball mill, and loaded. Both methods can be automated by PLC. The same applies to the addition of water to the ball mill, which can either be done manually using a water meter in the pipeline or automatically using PLC-controlled systems.

A few manufacturers often add small amounts of binders and deflocculants during the ball mill process to enhance efficiency. Binders help keep the raw materials in suspension, preventing them from settling and ensuring a consistent mixture. Deflocculants, on the other hand, improve the fluidity of the slurry, making it easier to unload from the ball mill. These additives optimize the milling process, save time, and improve the handling of materials.

Milling

For glaze preparation, milling is done in an alumina-lined ball mill with alumina balls. The milling time is controlled by either a timer or a meter. Once the set milling time is reached, a sample is taken from the ball mill and tested for residue levels. If the residue meets the specifications, the milling process is stopped; otherwise, milling continues for a bit longer and samples are tested until the residue falls within the standard specification.

Unloading can be done using compressed air for faster and more efficient removal. Since binder addition reduces glaze density, unloading is done at a higher density of around 1.82 gm/cc to reach the supply density of around 1.74 gm/cc.

Sieving

The unloaded glaze is then passed through a vibratory sieve. Initially, the glaze is passed through a 200# size sieve. The sieve size may vary from factory to factory.

Iron Removal

Magnetic separation is conducted at various stages during glaze preparation to ensure the complete removal of iron particles. The first magnetic separation occurs while unloading the glaze from the ball mill. The second separation takes place after sieving the glaze. Some factories also perform glaze circulation to ensure iron removal. Magnetic separation is done using magnetic bars with a minimum strength of 10,000 gauss. Some factories use electromagnets for iron separation.

Quality Testing

Once the glaze passes through magnetic separation, each batch is stored separately, and sample glazing and testing are done to check the batch quality. Basic tests include:

• Glaze flow

• Iron contamination

• Glaze colour

Once the quality is tested and approved, the glaze is allowed to be used in production.

Binder Addition

Approved glaze is mixed with reclaim glaze, and the required amount of binder is added based on the desired drying & flow properties before being supplied to the glazing section.