Production Process of Slip in Ceramic Manufacturing

Production Process of Slip in Ceramic Manufacturing

The process of slip preparation involves milling and mixing of all the raw materials according to the required composition, achieving the desired particle size, rheological properties, sieving, magnetizing, and then sending the slip to storage.

A key step in ceramics slip production is to check the residue of the ball mill unloaded slurry and the residue of the slip, aside from evaluating its rheological properties. The residue can vary significantly based on the firing cycle time (16 to 46 hours of cycle), non-plastic materials percentage and the complexity of the product being produced.

Variations in Slip Production Process

There are multiple variations of the slip production process. The variation in slip preparation process comes based on the percentage of plastic and non-plastic materials used in the slip, required particle size distribution, cost of slip production and particle size of non-plastic material supply.

Method 1: Single Ball Mill Process

All raw materials, including ball clay, china clay, feldspar, quartz powder, & deflocculant, are charged into the ball mill. Then the slip is passed to the sieve and stored. This process is typically used when the quartz content is less than 7% in the body composition.

Method 2: Blunger and Ball Mill Separation

Ball clay is charged into a high-speed blunger and adjusted for rheological properties. This ball clay slip is stored separately. Simultaneously, the ball mill is charged with quartz and china clay, which are ground and stored separately. Then, the ball clay slip, and quartz slurry are pumped to a blunger, where feldspar powder and deflocculant are added to adjust the rheological properties.

This process is used when the ball clay has a high deflocculant demand, and feldspar powder is readily available. It offers greater control over the slip mix. Green scrap slip is prepared separately in a blunger and stored in a tank.

Method 3: Controlled Non-Plastic Material Addition

Feldspar and quartz are charged into the ball mill with ball clay/china clay and ground. The slurry is then pumped to a blunger, and the remaining clay content is added to the mix and adjusted to the required properties. Controlling the non-plastic materials provides greater control over the casting rate and particle size.

Sieving and Storage

Once the slip is prepared, it is passed through 80# and then 100# sieves. Before being sent to storage, the slip is passed through magnets to remove any iron impurities. A newly prepared slip is called a virgin slip.

Return slip from casting & green scrap slip is also sieved through an 80# sieve. Both slips are stored separately.

Aging and Blending

Virgin slip is allowed to age for a minimum of 2 to 3 days. After aging, it is mixed with scrap slip and return slip in proportions based on their averages to maintain consistent slip properties.