## 2 Design and Characteristics of Bucket Conveyor Operation  
Bucket conveyors are devices designed to transport bulk materials at large slope angles, such as coal, ores, aggregates, as well as crops and agricultural products such as cereal grains, sugar, etc. In the mining industry, they are used in preparation plants for transporting and dewatering materials in the beneficiation process in water pulsation jigs.  
They are classified as multi-member cable conveyors. The members are buckets that are attached to cables, i.e., tapes or chains. Due to high loads in the mining industry, chain conveyors are mainly used. An example of a \"KOMAG\"-type bucket conveyor is shown in Figures 1 and A1.  
The conveyor drive consists of an electric motor and a mechanical transmission gear mounted on a sliding frame relative to the supporting structure installed on the upper end member. The drive shaft and chain stars are installed on bearings on the supporting structure, and are coupled with a mechanical gear via a chain transmission.  
The tensioning device consists of tensioning screws and a worm gear driven by an electric motor. In addition, the device is equipped with a manual or automatic driving system, which allows controlling the chain tension within the return end station in the case of a motor failure.  
During operation of the jig node (Figure 2), there are frequent changes in the flow rate of the material directed to the beneficiation process, and in the gravimetric composition of the beneficiated material changes; this, in turn, causes changes in load to the bucket conveyor. The speed of the conveyor should be adapted to the current load, and must be controlled in such a way as to prevent excessive accumulation of material in the loading zone of the conveyor, which may lead to conveyor stoppage, and thus stopping the entire jig node [5]. Since the beneficiation process in pulsation jigs takes place in a water environment (bucket conveyors are flooded with water to approximately half of their height), it is difficult to identify the degree of filling of the buckets within the conveyor return station (bucket loading zone), which complicates the automatic control process [6].  
The output of the bucket conveyor can be controlled by changing its speed. A change in the motor speed translates into a change in the linear speed of the buckets transporting the material, which contributes to the amount of material transported at a given moment. The lower the speed, the greater the load to the conveyor buckets. When controlling the speed, the aim is to achieve a situation in which the nominal filling of the buckets is constant and, therefore, the instantaneous weight of the material on the conveyor is constant.  
Changes in the intensity of the bottom product stream from the jig directed to the conveyor are the basic disturbances that affect the load to the conveyor, i.e., the mass of the material transported on the conveyor [7,8]. These changes result from the controlling action securing the constant height of the waste product layer in the jig compartment. These disturbances are identified by measuring the opening degree of the jig's discharge flap. The control system must take into account delays resulting from the need to transport material from the jig to the feeding area of the conveyor.  
Figure 1: Diagram of the “Komag” bucket conveyor: 1—drive, 2—loading zone, 3—chain with buckets, 4—dumping zone, 5—tension station, 6—prop.