Changing Hydraulic Conductivity After Rupturing Native Structure of Peat Under Limited Evaporation Conditions

Abstract

The qualitative characteristics of peat raw materials in the processes of its mining and field enrichment fully depend on the nature of the biogenic-abiogenic interactions in the peat system, which is a capillary-porous body with a heterogeneous structure and water-peat binding energy changing in a wide range. Energy costs for dehydration of peat capillary-porous bodies of different sizes and configurations are crucial for technologies of peat extraction and processing in terms of ensuring economic efficiency of production. The present paper considers the issue of calculating the characteristics of dehydration of wet peat raw materials with moisture 84–90% under the influence of gravitational and capillary-osmotic forces, as well as through evaporation. As a result of the research, the characteristics of moisture transfer intensity in the biogenic-abiogenic peat system with varying water binding energy are described. For the high-moor peat deposits, the intensity of moisture transfer is described by a linear dependence, for the transitional and low-moor types of peat, the dependence has a minimum at the degree of peat decomposition of 30–32%. The minimum has the role of a generalised point at the decomposition degree of 31%. With the increasing decomposition degree for the high-moor type, the intensity of moisture transfer tends to zero due to the manifestation of the rheological properties of water, i.e. an increase in the limit shear stress and the density of the bound water, as well as the decreasing pore sizes. For transitional and low-moor types, the intensity of moisture transport tends to a constant with an implicit manifestation of the border due to the increase of the resistance factor of moisture transport. It is found that when the filtration equilibrium is reached, the amount of remaining moisture in the technogenic-disturbed biogenic-abiogenic peat system and the critical height of the bulk of peat raw materials will correlate with the moisture conductivity factors, porosity, pore size and height of a bulk. This feature of the changing moisture conductivity is confirmed by the experimental data obtained by the authors to assess the precipitation, the critical thickness of the bulk depending on the initial thickness of the peat layer of the disturbed structure and the change in the critical height in the pore radius function, which corresponds to the theoretical data obtained in the work.