Processing renewable resources containing lignocellulose

For years, the use of renewable resources outside the field of energy has been gaining more and more importance. Raw materials containing lignocellulose have conventionally been used to produce cellulose. However, the development of new and innovative processes means that these raw materials are now increasingly being used to produce platform chemicals for the chemical industry.

Apart from digestion, which refers to the separation of the three main components lignin, cellulose, and hemicellulose, one of the most important aspects when using renewable raw materials is comminution. In the comminution of renewable raw materials, the relationship between the energy used and the particle size of the product is considered one of the most important economic parameters. The comminution of wood-like raw materials is a very energy-intensive process due to the mechanical properties of these materials. They can be described as orthotropic materials, i.e. they have different and independent mechanical properties in the direction of the three main axes – longitudinal, radial, and tangential – which in turn depend on the type of raw material and the water content. These materials therefore represent a significant challenge when it comes to comminution.

In order to ensure that renewable raw materials are used efficiently and to make the platform chemicals obtained from them competitive with petrochemical products, raw material efficiency must be significantly increased, especially with regard to comminution. Detailed knowledge of the influence of the mill type and the associated operating parameters, as well as the influence of the type of renewable raw material, the water content and the mechanical properties on the comminution result, can significantly increase the efficiency of using these raw materials. The aim of the thesis is to investigate the influence of the water content, the type of wood, and the type of mill on the comminution process, the particulate properties, and the specific comminution energy and to transfer the data obtained into a model for predicting the comminution energy.