Raw Meal
Silos

A raw meal silo is an industrial storage structure that plays a key role in cement production, sitting between raw material preparation and the kiln line. Raw meal, produced by grinding limestone, clay, iron ore and other raw materials according to the raw mix design, is stored under defined process conditions before being fed to the rotary kiln, and is homogenised where required. For this reason, what matters is not only the silo's storage capacity but also its alignment with the plant's continuous production programme.

Because raw meal is a fine-grained material, the silo's reinforced-concrete geometry, discharge arrangement, aeration or fluidisation systems and process connections must be evaluated together at the design stage. Conical sections, outlet openings and equipment supports beneath or inside the silo are directly linked to the reinforced-concrete structure. To ensure that subsequent process installations proceed smoothly, anchorages and embedded items must be formed at the correct levels during concreting.

On tall raw meal silos, slipform construction can be used to raise the reinforced-concrete shell continuously. Once the formwork system has been assembled at the starting level, concrete pouring, reinforcement fixing and the hydraulic movement of the system are carried out in coordination. For the slipform method to work correctly, the concrete setting time and the climbing rate must be monitored continuously.

The trueness of the reinforced-concrete shell is particularly important in raw meal silo construction. As the structure rises, small dimensional deviations can turn into larger geometric problems at the upper levels, so verticality and centre checks must continue throughout the work. Even though the formwork is moved hydraulically, the operation still requires continuous surveying and site control.

On raw meal silo projects, Rayf Teknik draws up the work programme with the structure's role in the cement production line in mind. The positions of raw meal feed systems from the raw mill, silo top equipment, filter connections, elevators or conveying lines and bottom discharge equipment are all assessed in coordination with the structural works.

A slipform system establishes a steady production process, particularly for raw meal silo walls whose cross-section remains largely constant. However, beams, openings or special geometries at different levels within the silo must be included in the work programme in advance, so that reinforced-concrete details can be completed at the correct levels as the system climbs.

The successful completion of a raw meal silo is not measured simply by placing concrete. The structure must accommodate the process equipment correctly, suit the operating conditions of the stored material and allow subsequent mechanical installation to proceed without difficulty. Rayf Teknik's experience in raw meal silos and slipforming offers an approach that addresses reinforced-concrete construction and the cement plant's process requirements within a single project.