Background and Customer Requirements

For more than 50 years, Tolsa Group has been extracting, researching, developing, manufacturing and marketing a wide range of products for domestic and industrial use. Today, the company is focused on providing innovative solutions that help improve the competitiveness of its customers worldwide through products designed to integrate into their value chain.

History

More than half a century has passed since the inauguration of its first mineral processing plant, dedicated to bleaching earths used for the clarification of wines and oils.

From that moment onward, and in support of product development, Tolsa Group acquired significant natural reserves in Europe, Africa and South America, including the world's largest sepiolite deposit, major attapulgite deposits and high-quality bentonite reserves.

Today, Tolsa Group has gone far beyond simple mineral extraction. In addition to a solid natural resource base exceeding 100 million tonnes of reserves, the company incorporates all types of raw materials to provide solutions adapted to the current and future needs of its customers.

Products

1. Nature

• Attapulgite (Palygorskite).
• Sepiolite.
• Smectite.
• Bentonite.
• Amorphous Precipitated Silica.

2. Applications

• Environment and filtration (filtration and waste treatment), construction, civil engineering and slurries, industrial absorbents, pharmaceuticals and agriculture.
• Environment and filtration (filtration and waste treatment), construction, civil engineering and slurries, paints and coatings, asphalt and bitumen, industrial absorbents, agriculture and animal feed (E-562).
• Environment and filtration (filtration, water and effluent treatment) and animal feed (E-558).
• Environment and filtration (water and effluent treatment), civil engineering and slurries, paints and coatings and foundry applications.
• Animal feed.

Solutions, Equipment and Installations

The work carried out by SOTECMA consisted of taking in situ measurements of the silos, including overall dimensions and plate thicknesses. All measurements were performed from the outside of the silos and without drilling, using an ultrasonic thickness gauge. Samples of the stored material were also taken in order to determine its bulk density.

The two silo types were modelled using SolidWorks Simulation by ARAWORKS to perform finite element analysis, which allowed:

• Modelling both silos using beam elements for the support columns, solid elements for the reinforcement gussets, and shell elements for the cylindrical shell and cone plates.
• Applying horizontal and vertical pressure loads to both the cylindrical shell and the cone according to the pressure equations used for filling, discharge and buckling studies. Point loads from platforms and other elements supported by the silos were also included.
• Calculating principal stresses and Von Mises equivalent stresses.
• Calculating structural displacements.
• Performing buckling analysis for the first four buckling modes.

Following the study, several corrective measures were evaluated. Due to the difficulties involved in carrying out structural reinforcements within the limited available space, the selected solution was to reduce the storage capacity of the silos, thereby ensuring a safety factor of 2.