The design of a closed coal warehouse usually consists of a line of twin reinforced concrete silos with a metal cone part, in each group of which the bulk material of various characteristics is stored. Dosing conveyors or feeders supply the material to the collecting conveyor. In this case, the exact dosing of each component and their layered mixing must be observed, that enables obtaining the mixtures of a given composition.
Violation of the timely supply of any of the components onto the assembly line leads to a forced stop of the line. The possible reasons for arching and hanging of materials are:
- the design features of silos and funnels,
- low temperatures for high-moisture material,
- significant compaction of the material when falling during loading of silos,
- adhesion properties and instability of other physical and mechanical characteristics.
To solve these problems, manual labor is often engaged using the sledgehammers or more powerful percussion tools, that leads to such consequences as:
- deformation of the walls, where even more complex hangings of materials are formed,
- destruction of welded joints and bases of fastenings of the entire structure of the hopper,
- frequent injuries to service personnel.
In addition to the low efficiency of this method of arches collapsing, one has to put up with the frequent shutdowns of prosessing lines for unscheduled repairs.
Until recent times, the electric vibrators and pneumatic impulse systems were considered as the traditional mechanical systems for elimination of hanging.
- The electric vibrators are short-lived, often lead to the destruction of the walls of hoppers, to the compaction of the material in the hopper.
- The pneumatic systems require the generation and preparation (drying) of high pressure air, and are inefficient in case of material freezing.
Since the beginning of the 90s, in order to eliminate the hang-ups of bulk materials, electric vibrators and pneumatic systems have been replaced by efficient and economical in operation the magnetic-impulse installations IM manufactured by RPE “MITEK” LLC. They have a number of advantages compared to their predecessors, namely:
- possibility of prompt adjustment of the amplitude, shape and repetition rate of the acting impulses;
- possibility of not only collapsing the suspended material, but also cleaning the surface (hopper wall) from adhering material;
- work in energy-saving mode with minimal operating costs;
- preservation of the integrity of the cleaned walls of hoppers and other surfaces;
- ease of operation, maintainability, durability. The service life of IM installations before the overhaul is at least 10 years.
As an example, below is a diagram of equipping 28 silos of a closed coal warehouse of the coal preparation workshop of CP: