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The article gives the expert assessment data on the selection of the best ways of low-moisture peat harvesting by a milling method. They are essential to reducing the energy expenditure for the artificial drying of peat and ensuring the quality characteristics of raw material required for further thermochemical processing. The R&D efforts towards stimulation of the field drying of crumb peat are analyzed. The method of prioritization is applied in expert assessment. An appropriate significance rank value is assigned to each method. Mathematical estimate of the expert information reliability is made by the range and the variance of total ranks. The consistency of experts’ decisions on the assessment of the milled peat drying stimulation methods was checked by the relative range of significance values as well as the actual and the estimated strength of an expert group. Preference is given to two options: peat drying to harvesting humidity of 35% in thick layers and that on the slopes of pre-formed swaths of raw peat crumb.

The article presents two options of organizing the technological process of milled peat extraction with due consideration of weather conditions for peat drying. The first option of the technological process is the extraction based on cycle peat harvesting differentiation. The developed technological process of milled peat drying in thick layers based on pneumatic peat harvesting allows us to organize a technology of peat extraction with a constant cycle time, avoiding the necessity for drying rate prediction. This is due to the fact that under good weather conditions the spreading thickness of 45-50 mm is sufficient to maximize the number of harvesting cycles. Milling at roughly equal depths forms the basis for the second option of technological process. The article presents the methodology of calculating such technological parameters as cycle and seasonal harvesting, number of cycles and seasonal productivity of a harvesting machine. Seasonal harvesting and seasonal productivity of a harvesting machine are calculated by technological design standards. The analysis of calculations revealed that in the process of milled peat extraction based on cycle harvesting differentiation, it is necessary to apply coefficient 0.9 that takes into account the organization of harvesting machines operation.

The article presents a milled peat production practice based on deep bed drying up to a harvesting moisture content of 35%. The task of the developed technology is to minimize and stabilize the harvesting humidity in the field drying of peat, thereby reducing the time and thermal impact on the peat organic matter during a forced finish drying. The applied method of peat extraction provides for variable milling depth and differentiation of cycle harvesting to increase the number of cycles and the harvester seasonal output. An economic feasibility study has been carried out by the method of determining the operating costs per ton of a marketable product for each technological operation. It consists in a comparative assessment of two technological processes: the production practice based on intensification of milled peat drying up to a harvesting moisture content of 35% and the conventional harvesting of milled peat with moisture content of 45%. The developed technology of milled peat extraction makes it possible to ensure the required quality parameters in terms of humidity (≤ 35%) and to preserve natural bituminous components. Based on the economic assessment results, it has been found that there is a slight increase in operating costs per ton of a marketable product in comparison with the conventional practice.

The paper investigates the effect of self-heating, wetting and freezing of different milled peat types on field storage losses. It has been found that the loss of organic matter in peat due to self-heating depends on peat decay degree, type of product obtained, heating temperature (storage duration), preventive measures taken and the technological scheme of peat extraction. When such preventive measures as moving stacks, internal sealing and compaction of peat are taken, a decrease in self-heating and spontaneous combustion losses is observed. In two-stage harvesting, these losses are lower because of peat compaction in stacking operations. It has been established that there is a dependence of peat losses on its wetting and freezing, storage duration, and the total amount of precipitation accumulated over a certain period. With an increase in peat decay degree, the maximum wetting and freezing losses are several times lower than self-heating losses. These losses are 20% higher for upland peat than for lowland peat.