Physical Properties of Mineral Fibers Depending on the Mineralogical Composition

A developed methodology for determining the physical properties of mineral fibers prepared from different input mixtures under the same spinning wheel conditions is described and discussed. Energy dispersive X-ray fluorescence spectroscopy was combined with simultaneous thermal analysis and thermogravimetry to study the mineralogical composition and typical melting and crystallization temperatures. The mechanical properties measured with nanoindentation were related to the mineralogical properties and the results obtained are in agreement with the literature. The developed methodology shows reliable performance and demonstrates the ability to study the mechanical properties of mineral fibers, their mineralogical composition, and thermal properties. The presented experimental methodology opens up the possibility of researching the mechanical properties of mineral fibers for the purpose of defining production recipes in the field of mineral thermal insulation materials.

POTENTIAL SOURCES OF AIR POLLUTION BY INDUSTRIAL FIBERS

Resume. Currently almost no attention is paid to the potential possibility of air pollution of premises for various purposes by industrial fibers (natural (asbestos) and man-made mineral fibers) in the Russian Federation while there is increasing use of materials containing such fibers in industrial and civil construction. Purpose. To conduct a survey of premises for various purposes to identify materials containing industrial fibers and assess the potential possibility of releasing fibers from them using research methods adopted in modern world practice. Materials and methods. A visual and instrumental survey of premises was carried out; 169 materials samples, 57 dust samples and 45 air samples were sampled and analyzed. Results. The numerical fiber concentrations in air samples did not exceed the standarts for working area air (0.2 f/ml for man-made mineral fibers (MMMF) and 0.01 f/ml for asbestos fibers), used in modern world practice. MMMF were detected in half of the dust samples, chrysotile asbestos fibers (CAF) were detected in 3 dust samples, MMMF together with CAF were detected in 9 dust samples. CAF were presented in 85 of 169 materials samples, MMVF were presented in 34 materials samples, organic fiber were presented in 18 materials samples, no fibers were presented in 32 materials samples. When using the algorithm for estimating the probability of fiber releasing, 43 materials containing CAF had a very low chance of fiber releasing, 18 – low, 21 – medium, and 3 – high chance, and 15 materials containing MMVF had a very low chance of fiber releasing, 11 – low, 7 – medium, 1 – high. Conclusion. Materials containing industrial fibers are widely used in premises for various purposes. Visual and instrumental survey allows detecting such materials and assessing their condition for the development of measures set to control working area air pollution. The detection of fibers in dust samples makes it possible to establish the presence of sources of air pollution, as well as to identify them in most cases.

Comprehensive hygienic assessment of the dust factor in the manufacturing heat-insulating building products from man-made mineral fibers

Introduction. Air pollution with aerosols of mineral fibers in the manufacturing heat-insulating building products is the primary harmful production factor that can increase the risks of developing several diseases of various organs and systems. It determines the relevance of conducting comprehensive studies of the dust factor in such industries, assessing the relationship between mass measurements and fibre counts, the development of targeted preventive measures, considering the features of the technological process. The study aims to conduct comprehensive hygienic studies of the dust factor in the manufacturing heat-insulating building products from basalt fiber and determine the morphological features of dust at different stages of the technological process, the presence of a relationship between mass measurements and fibre counts. Materials and methods. The studies were carried out based on manufacturing heat-insulating building products from basalt fiber. To assess the dust factor, the authors carried out the analysis of mass measurements of dust and fibre counts using phase-contrast light microscopy. The authors used linear regression analysis to study the dependence of the mass measurements and fibre counts. Results. The mass measurements of dust in the working area don't exceed hygienic standards and ranges from 0.51 mg/m3 to 1.19 mg/m3, and the fibre counts are from 0.45 f/cm3 to 1.23 f/cm3. The morphological analysis of the dust samples' preparations collected on filters from the air of the working area made it possible to reveal the characteristic features of the composition of the dust at various stages of the technological process. The study confirmed a positive correlation of weak strength between fibre counts and the mass measurements. The resulting dependence model is statistically significant, but the coefficient of determination of this model (R2) is 0.043. Fibre counts in the first phase of the production cycle are significantly higher than in the second. Simultaneously, the mass measurements do not have significant differences in different phases of the production cycle. Conclusions. There is a positive correlation of weak strength between fibre counts and mass measurements, but the resulting linear regression model can explain only 4.3% of the variation of fibre counts based on the mass measurements, which does not allow using this model for converting of the results of measurements of several particles. Microscopy of dust preparations makes it possible to determine the morphological picture characteristic of various stages of the technological process. Fibre counts depend on the phase of the production cycle. The data obtained can be used to design air purification systems and operating modes at various stages of the technological process.

Establishing a correlation between friction performance and tribolayer formation using engineered mineral fibres

This paper relates the friction performance to the tribolayer formation when using engineered mineral fibers in the friction formulation. A non-asbestos organic non-steel copper-free passenger car-disc pad (NAO) non-steel Cu-free PC-DP) formulation is used to investigate the impact of the fibers on the third body formation and its influence on performance and wear. Full scale dynamometer performance (AK-Master) test results show the pronounced effect of the fiber length on the friction performance. While a similar overall coefficient of friction (CoF) of around 0.33 is observed in all 3 cases, more stable friction behavior is observed for the longer fibers , with less variation. This behaviour is even more observed in the fade and high temperature sections. Especially the use of fibre spheres shows quite some unique features over the other tested mineral fibers, especially with respect to pad / disc wear. To understand these differences in performance, the transfer layer and tribolayer on the disc and brake pad are investigated respectively by means of scanning electron microscopy (SEM). Formulations showing excellent performance results so far show the formation of a smooth transfer film on the disc. No grooves are visible and a continuous iron oxide layer is formed at the surface. The tribolayer of the corresponding brake pads nicely shows the formation of a compacted thin layer at the surface. In addition, the importance of mineral fibers in the formulation is highlighted, as they are at the core of the tribolayer formation. This work is a step forward towards understanding the role of mineral fibers in a friction formulation and shows its importance towards reducing non-exhaust emissions.

Identification of Asbestos Content in Bulk Materials Imported in Nepal

The bulk materials include the construction materials such as plaster sand gravel and cement as well as raw materials. Asbestos is the naturally occurring magnesium silicate mineral fibers which has high tensile strength, flexibility and resistance to chemicals, high temperature and stress; this is why it has been considered and used in bulk materials. These mineral fibers are needle shaped and can stick to lung tissue when inhaled and cause inflammation and serious health problems such as asbestosis, mesothelioma and lung cancer or internal fibrosis. It can be detected by simple microscopic method using mineral acid and heat treatment. The method would help in quality analysis of asbestos fiber and save from asbestos induced disease and to develop alternative materials of asbestos fiber material.

Influence of Characteristics of the Melted Basalt on the Process of Formation of Fibers

In any production of products based on mineral fibers, one of the main types of equipment included in the line for the production of fiber products is installations for forming a basalt carpet, or the so-called fiberizing chambers. The quality of finished products depends on their perfection. Currently, there are several widely used in industry methods for producing mineral fibers from melt, which determine the various types and designs of fiberization chambers. In all chambers, the formation of mineral wool carpet occurs under the influence of hydrodynamic forces. Therefore, the study of such hydrodynamic characteristics as the rate of fall of individual fibers and clumps of these fibers and the hydrodynamic resistance of the carpet are of paramount importance in the design of new and reconstruction of old chambers. In this paper, we study the relationship between the strain rate and the viscosity coefficient of basaltic melt during fiber formation using a blow head developed by the authors. The substantiation of the process of fiber formation using a blowing head is given. Relations are obtained that establish the dependence of the strain rate in the fiber stream on the viscosity of the melt. Experimental data have been obtained that can be used to evaluate the effect of a basalt deposit on the dependence of the strain rate on the viscosity of a basalt melt. It was found that high-speed deformation of the melt greatly affects the quality of the fibers and the amount of waste in the production of fibers.