Search

The level of occupational respiratory diseases among workers in the mining, machine-building and metallurgical industries remains high. The most common occupational respiratory disease is pneumoconiosis, which is the result of the long-term inhalation of dust. It is possible to minimize the impact of dust on the workers and eliminate such diseases in the future due to the use of filtering mask respirators designed to reduce dust infiltration into the space under the mask. For this purpose, the choice of the type of elastic bands of filtering mask respirators has been substantiated by the geometric shape and tension forces that can ensure a permissible level of leakage of contaminated air into the breathing zone of the respirator during its use. A mathematical model has been developed to describe the influence of parameters of elastomeric headgear on the protective properties of the respirator. The dependence of the change in the residual tensile strength of the elastic bands of the headband has been established, and the dependence of the volume of air suction on the area of the elastic straps at the corresponding tension force has been determined. Using the model, the dependence of the volume of polluted air inflow on the area of the elastic straps at the corresponding tension force has been estimated. The design of the innovative inserts has been offered, which makes it possible to control the tension of the elastomeric head straps of the respirator to visualize the weakening of the pressure forces responsible for maintaining a tight fit.

To increase the insulating properties of elastomeric half-masks, it is suggested to perforate the obturator in the area of the nasal bridge, chin and cheeks, which allows for adjustment in its size, thus preventing the occurrence of wrinkles on the user’s face in the areas which are the individual features of a particular user’s face. Three versions of the perforated filter respirator obturator have been proposed: in the first, the holes are made along the entire perimeter of the obturator; in the second, the holes are only in the area of the cheeks and nasal bridge; in the third, incisions with a diameter of 5 mm are made in the area of the nasal bridge and cheeks. The result of modelling a set of alternative solutions taking into account the coefficient of protection of filter respirator half-masks, the distribution of compressive forces, which are determined in the environment of the packages “ANSYS” and “Solid works”, has been obtained on the basis of main indicators of the proposed models. To make a decision on choosing the best model, the mass of the elastomeric half mask, its dimensions and the complexity of the design were additionally considered. On the basis of expert evaluation, according to the described procedure for determining the utility function of the factors from their values, it has been defined that the second model of the half-mask is characterized by the best parameters. Conducted laboratory studies to determine the aerosol absorption coefficient by the obturation line showed the lowest indicator in the second option.

The conditions of coal seam mining in the mines of Ukraine have been considered. The problem of conducting coal mining by longwalls in the conditions of soft adjoining rocks, which concerns the protection of mine roadways located near the face, has been revealed. In such conditions, the existing protective constructions are ineffective due to the fact that they yield and get pressed into the soft rocks of the footwall. This indicated the need for research into the geomechanical state of soft rocks of the footwall. According to the results of known studies on the mechanism of rock mass failure around roadways and the data of physical and mechanical properties of the coal mass, which is represented by soft rocks, the correlation dependence has been obtained, the use of which allowed for the determination of the parameters of the rock deformation diagram and the establishment of the stability criterion of footwall rocks under the protection means and stability conditions of the geotechnical system “protective construction – adjoining rocks.” They are the basis of a new approach to ensure the stability of the roadways, which are supported behind the faces, by controlling the stress state in the system “protective construction – adjoining rocks.” This may be the basis for the development of new methods of protecting roadways in conditions of soft adjoining rocks.