This experimental work aims to study the viability of making use of agricultural and forest residues as an alternative to produce biofuels for commercial devices. It focuses on the feasibility of three non-commercial biomass fuels in an underfed biomass pilot combustor with a power range of 7–12 kW_th (500–800 kW/m²). To carry out the investigation, the repeatability of the facility was studied using fuel with a high ash content. The relative deviations in the main parameters considered (combustion rate, gaseous emissions and particulate matter emissions) were below 10%. A feasibility analysis was performed by comparing the result obtained with a barley and leaf pellet with that obtained with a commercial wood pellet as a reference. The parameters used in this study were the operational parameters of the plant as well as the particle concentration and distribution, fouling and slagging. Comparing the results of the different fuels, it was determined that 25% leaf + 75% wood pellet (lp25) could be used as a commercial pellet with the incorporation of an additive. However, the two other fuels presented undesirable behavior characterized by high particle concentrations and notable amounts of slag.

This paper describes optimisation of a conveyor from an underground hopper intended for a coal transfer station. The original solution was designed with a chain conveyor encountered operational problems that have limited its continuous operation. The Discrete Element Modeling (DEM) was chosen to...

Friction parameters such as the angle of internal friction and the external friction of soils (bulk materials) show the possibilities of further material use. These are, for example, possibilities for soil processing, handling, and storage. The determination of friction parameters is usually carried out under laboratory conditions. For the possibility of determining the properties of soils outside the laboratory in terms of immediate material response, a laboratory prototype was developed. The main objective for its development was to determine the effect of the shape of the friction surface when “sliding” on the soil. This was achieved with the help of validation equipment designed to measure, test, and validate the processes of raking, material piling, material transfer and removal, and tool movement or sliding on or in a material. It was found that by using an appropriate speed and normal load, the Jenike method can be applied to determine the angle of external friction over a shorter distance with an error of about 6–7.5% from the values measured on a calibrated shear machine. The results also showed that the method can be applied to detect the shear stresses that arise when a tool is plunged into a material, and thus predict the possible increase in energy loss during the process.

Crushing is one of the important technological operations in the reduction of oversized pieces of utility material. It is of great importance in mineral processing, where the excavated material is processed into a final product or for the purpose of further treatment. There are several different types of industrial crushers. In practice, it is usually not possible to process the raw material into the desired product using only one machine; it is usually necessary to use several crushers, often in combination of two or more construction types. When the material is crushed, its grain composition and flow properties change. The change in these properties affects the way the material is handled, in particular its transport and storage. A systematic approach to the influence of crusher parameter settings on the flowability and granulometry of the resulting product has not yet been published. In this study, the effect of laboratory jaw crusher parameter settings on the granulometry and static angle of repose of different types of crushed aggregates was investigated. It was observed that changing the setting of the crusher gap width changes the ratio of dust and coarser particles of the crushed material, and this ratio has a significant effect on the changes in the static angle of repose of this material. Keywords: Angle of repose; Comminution; Crushing; Granulometry; Jaw crusher.

The article presents the results of simulation of the Discreet Elements Method (DEM) applied to the chain conveyor model with regard to optimisation of its carriers´ geometry. The work is focused on the impact pulses of carriers in the first part of the chain conveyor´s transport cycle and the influence of a change in the carrier element´s geometry on vector motion of particles and velocity differences of motion of the transported material. The issue is solved by the DEM method, where a 3D model of the tested equipment and a sim- ulation of material transportation in the transport system is created. Virtual 3D models of equipment can be easily adjusted such as changes in the structure dimensions. In the text, it is the approach to testing the influence of the chain conveyors carrier´s geometry on the character of motion of particles. The results show that the carrier´s geometry changes the trajectory of motion and velocity of the transported material particles during their transport on the chain conveyors.