## 3 Problem Description
### Defining Alternative Solutions  
The physical and chemical characteristics of bulk materials are the critical factors in forming a set of alternative solutions for their handling. In practice, ready-made solutions are mostly used for handling bulk materials, that is, those already used for similar or the same tasks with similar or the same materials. In the analyzed literature, in the handling of bulk materials, different types of conveyor systems are used most often. An analysis of research in the field of selecting material handling equipment reveals that authors commonly examine three or four alternatives [48; 49; 50; 51; 52]. Consequently, for loading containers based on the requirements in the analyzed case study, this research will consider a pneumatic conveyor (PC), a robotic conveyor (RC), an elevator (EC), and a belt conveyor (BC).  
The PC (A1) includes a safe, reliable, economical, and environmentally friendly way of handling bulk material [48]. The vital function of this technology is the handling of materials, but in addition, it can facilitate mixing, heat exchange, drying, and chemical reactions [49]. A unique feature of pneumatic conveyors is that, with their use, materials can be handled in closed systems from one location to another without any risk of environmental pollution. Additional advantages include the fact that they facilitate the easier and more cost-effective handling of materials, their quick and easy installation, and the fact that they require little space for operation. their disadvantages include the fact that they necessitate high investment costs, their significant energy consumption, the jamming of material(s), and the fact that they cannot be used for coarse material granulation [48; 49].  
The RC (A2) involves the integration of robots and conveyor systems (in this case, belt conveyors). These advanced systems are fully automated and can control the amount of loaded or unloaded materials without the presence of a human (i.e., they can dose the required amount of material themselves) [50]. Their advantages include their automation of activities, low energy consumption, and the fact that their use can reduce errors [51]. Their disadvantages include the requirement for continuous employee training, advanced computer systems, and relatively high investments [50; 51].  
An EC (A3) is a technology for material handling that is primarily used for overcoming height differences. In practice, ECs are most often used when handling bulk materials, but they are also used for unit-load goods of smaller dimensions [52]. Depending on their technical and operating characteristics, elevators can achieve high productivity. Their advantages include the fact that they facilitate closed construction that protects the working environment from dust, the fact that the management of this conveyor is usually not complicated, the fact that elevators are not big consumers of energy, etc. [53]. Their disadvantages include the need for relatively high investments and changes in the transport path, their low flexibility, and the frequent failures caused by the inadequate maintenance of elevators. ECs also emit a lot of noise due to the fact that they are constructed from metal [53; 54].  
The BC (A4) is the most commonly used technology in this field, and it has continual action for material handling. The core element of this conveyor is its belt, which is the most expensive part, used for material handling. Regarding the deployment of BCs, the belt conveyor is universal and suitable for handling bulk and unit-load goods [55]. Its simple assembly, capacity to be combined with other technologies, and low-level noise emission [56] are its main advantages. The disadvantages of BCs include the fact that the belt of the belt conveyor can be subjected to mechanical damage, BCs' sensitivity to chemical influences and temperature fluctuations, their high maintenance costs, and the problems with complex transport paths that arise with their use [53; 54].