Additional high‐energy milling to enhance the performance of porcelain stoneware manufacturing

Abstract

Porcelain stoneware tile is the best class of ceramic tiles regarding technical performance. Low porosity and high glass content are some of its highlighted characteristics. The manufacturing cost is highly dependent on the feldspar content and the processing flow rate. Certain technical bottlenecks in the manufacturing steps, such as milling, forming, and firing, are intrinsically associated with limitations in the processing properties, such as the dry strength, bulk density, and pyroplastic deformation. In this work, improvements in these properties were achieved using high‐energy milling (HEM) after conventional milling (CM). This study was carried out on a pilot industrial scale in the milling stage. Six experimental runs were evaluated. Slurries were spray‐dried. The powders were humidified with 6.5% moisture. Specimens were conformed under a specific pressure of 45 MPa. The firing was performed using temperature ranging from 1150 to 1230°C. The use of HEM, in comparison to traditional milling for the similar particle‐size distributions, has increased the dry density, +0.2 g.cm−3, dry bending strength, +1.0 MPa, and decreased the pyroplastic deformation index, −1.10−5 cm−1. These results allow an estimated thickness reduction of 10%.

Optimizing the Energy Consumption of the Porcelain Tile Manufacturing Process using Flowsheet Simulations

“…Consequently, longer milling times can be beneficial for the reduction of fuel consumption. The same conclusion has been drawn by Darolt et al [6] and Beltrán et al [41]. The size of reactant particles governs the kinetics of sintering [47].…”

“…The sintering stage of the firing process was assumed to be isothermal, and the porosity was modeled according to the approach developed by Gómez et al [31]. The final total porosity of the tiles was fixed at nearly 5%, and the bulk density ( ) was 2.35 g/cm 3 [6,32,33]. At this level, the water absorption is assumed to be less than 0.5%, and the product rises to the standard level to be considered a porcelain tile.…”

“…Inadequate milling can increase water absorption of fired tiles and lead to staining problems in products that undergo polishing. In contrast, excessive grinding can compromise the shaping stage, resulting in parts with decreased apparent density and dry mechanical strength, as well as increased linear shrinkage of the tiles after firing [6,7].…”

“…The productivity of a ceramic tile plant is inversely proportional to the total firing cycle time [6]. The firing stage is responsible for the most significant thermal energy consumption and is often assumed as the main production bottleneck [4][11-13].…”

“…It can be observed an increase of CO2 emission per m 2 of tile with increasing production rate, as seen in However, longer milling times lead to higher erosion of the gridding balls used during the process, which will result in higher expenses not accounted for here. Additionally, longer milling times result in smaller pores size after conformation, lower bulk density and dry strength [6,20]. Smaller particles originating from excessive milling have a higher tendency to adhesion and agglomeration that compromise the fluidity into the conformation die.…”