[en] The aim of this series of studies has been to develop methods to reduce the environmental impacts of peat mining, that function when the pollution load is high and that are economically viable for all peat mines. Sediment transport and nutrient leaving were studied with the purpose of establishing more efficient treatment alternatives. A controlled experiment was set up to measure the erosion of peat from the soil surface and from ditch beds during heavy rainfall and runoff events and to measure the settling characteristics of base soil peat and peat deposited in channels. The study demonstrates the importance of channel bed erosion as the main source of sediment during peak runoff. Sediment transport and nutrient leaching were further observed in the field during 1995 and 1996. The study showed that suspended solids (SS) is mainly generated during extreme events, such as flooding. These high flow events erode the material deposited on the channel bed during low flows. The leaching of nitrogen occurs after large rain events, while high phosphorous concentrations occur when the water table is low. Treatment alternatives were developed to improve removal of SS and nutrients. Different types of ponds were tested in a laboratory study. The study showed that the main factor affecting the settling of small peat particles is the depth of the settling basin. A mathematical model showed that in the case of bare soil erosion, the best treatment alternative would be to store the water in the large drainage network rather than in the sedimentation basin. Different structures suitable for peak runoff control were tested under laboratory and field conditions 54 refs, 11 figs

[en] Numerical investigation of the combustion processes of high ash coals in furnaces of steam boilers was conducted by the method of mathematical simulation. Three-dimensional equations of thermal and mass transfer, simulating turbulent flows with chemical reactions were solved which describe the combustion. (author)

[en] This project which deals with the demonstration of a full size commercial coking retort using Calderon's proprietary technology for making metallurgical coke ran into a commercialization problem by virtue that the designed retort for two (2) tons of coke/hour necessitates thirty-two (32) retorts to produce the 500,000 tons of coke per year for a commercial plant. Bechtel Mining and Metals prepared a cost estimate of the commercial plant which indicated the commercial plant would not be economically feasible. The activity during this reporting period was directed to making changes to the design of the coking retort in order to reduce the number of retorts required for a 500,000 ton/year commercial coke facility. The result of this activity resulted in the drastic reduction of the number of retorts to eight (8) with each retort projected to produce 8.17 tons of coke/hour. Such decrease in number of retorts makes the Calderon technology quite competitive and therefore commercially feasible

[en] Computation experiment on combustion of solid radiation-treated fuel in burning chamber of boiler at Pavlodar thermal electric plant is carried out. Velocity, temperature distribution and concentration of combustion products by height of chamber are received. Analysis of received results shows that radiation treatment of fuels exerts substantial effect on egress parameters of thermal electric plant. It is shown, that radiation treatment allows to improve effectiveness of boiler device and reduce of harmful substances discharge in atmosphere. Results of conducted numerical experiments allow to create complete methods of solid fuel combustion with high moisture and ashiness

[en] Peatlands act as a major sink of carbon dioxide and a source of methane. Fluxes of methane were measured by a static chamber technique at hummock, hollow, and lawn microtopographic locations in 12 peatland sites near Cochrane, northern Ontario, from May to October 1991. Average fluxes (mg/m²/d) were 2.3 at hummocks, 44.4 at hollows, and 15.6 at lawns. Methane flux was negatively correlated with average water table position based on the 36 locations, with hummocks having a smaller flux than hollows or lawns, where the water table depth was <25 cm. Peat samples from a bog hummock and hollow failed to produce methane during anaerobic incubations in the laboratory; samples from a poor fen hollow produced <1.4 μg/g/d. The production decreased with depth but was greater than the rates observed during incubation of samples from an adjacent hummock. Rates of methane consumption during aerobic incubations ranged from 1 to 55 μg/g/d and were greatest in the surface layers and decreased with depth. Differences in methane emissions between hummocks and hollows appear to be controlled primarily by greater methane production rates in hollows compared with hummocks. Of secondary importance are the capacity of the peat profiles to consume methane during its transport to the peat surface and warmer temperatures at the water table beneath hollows compared with hummocks. 29 refs., 4 figs., 2 tabs

[en] The threat of global warming is sufficient to warrant ''least regrets'' measures to reduce emissions of greenhouse gases, in particular through increased efficiency in energy production and use. British Coal has set up a programme to contribute to the international responses to the threat. It is concentrating on investigating options for removing carbon dioxide from fossil-fuelled power plants in case expensive fallback options become necessary. Screening of the options commenced with flowsheeting studies which estimated the thermal efficiency of a number of process schemes. These screening studies concluded that carbon dioxide (CO₂) control could be retrofitted to existing coal-fired power stations, but that the new generation of gasification-based systems is more promising. CO₂ separation could be more easily integrated into advanced power plants as they operate at high pressure, resulting in increased CO₂ partial pressure which reduces the energy penalty associated with the separation. (Author)

[en] After reviewing clean coal technologies currently under study in the United States, Australia, and Japan, under the current climate of global warming concerns, one concludes that some of these technologies might well be commercialised soon, especially if some kind of 'emission trading' regime is encouraged after the 1992 United Nations Conference on Environmental and Development (UNCED, Rio de Janeiro, Brazil, June 1992). Some alternative financing possibilities under various emission trading regimes are studied for a 'sample' technology to illustrate the issues involved in clean-coal technology penetration. It is concluded that a financial 'carbon saving credit' alone might prove sufficient to stimulate such penetration. (author)

[en] The history of subsidence, fires, flooding and other kinds of environmental hazards related to shallow coal workings in India goes back to colonial times some 300 years ago. As coal production accelerated in modern times, so did the environmental and socio-economic drawbacks related to exploitation. In the mid-1980s, a hydropneumatic sand-stowing method was developed to fill in abandoned galleries but their exact location had to be known. Unfortunately, most of these old workings are uncharted and consequently large tracts of land cannot be stabilized. A research program making use of integrated surface, borehole and cross-hole geophysical methods was undertaken over a five-year span to try to solve this problem. Surface geophysical methods, being cheaper and faster than their cross- and downhole counterparts, were used to cover larger areas on an exploratory basis, while cross-hole methods were employed to locate more accurately one or a network of galleries to be perforated by drillhole(s) and used as a conduit for sand stowing. The authors report the results of one of the cross-hole geophysical methods: electrical resistivity tomography (ERT). A pole-dipole configuration is used and both cross-hole and surface-borehole methodologies are tested. Forward modelling and inversion of synthetic data making use of downhole and surface physical and geometrical parameters are presented first. This phase is followed by the inversion of real data. It is concluded that ERT is not applicable for the detection of dry voids, but is effective in a waterlogged environment which is estimated to represent 85--90% of the cases. In waterlogged galleries, ERT is applicable in both cross-hole and surface-downhole modes, the latter allowing a larger surface coverage at low cost. ERT is thus a reliable geophysical tool to image water-filled voids and an adequate technique to address environmental and geotechnical problems

[en] D-grade domestic coal is being widely used for household cooking and heating purposes by the poorer urban communities in South Africa. The smoke from the combustion of coal has had a severe impact on the health of communities living in the rural townships and cities. To alleviate this escalating problem, the Department of Minerals and Energy of South Africa evaluated low-smoke fuels as an alternative source of energy. The technical and social implications of such fuels were investigated in the course of the Qalabotjha Low-Smoke Fuels Macro-Scale Experiment. Three low-smoke fuels (Chartech, African Fine Carbon (AFC) and Flame Africa) were tested in Qalabotjha over a 10 to 20 day period. This paper presents results from a PM10 TEOM continuous monitor at the Clinic site in Qalabotjha over the mentioned monitoring period. Both the fuel-type and the wind were found to have an effect on the air particulate concentrations. An exponential model which incorporates both these variables is proposed. This model allows for all measured particulate concentrations to be re-calculated to zero wind values. From the analysis of variance (ANOVA) calculations on the zero wind concentrations, it is concluded that the combustion of low-smoke fuels did make a significant improvement to the air quality in Qalabotjha over the period when these were used

[en] The primary objectives of this document are to describe generic requirements and outline common errors, omissions, and constraints with regard to prevention or reduction of metal leaching and acid mine drainage (ML/ARD) at British Columbia mine sites. It begins with background on ML/ARD and guiding principles for the regulation of ML/ARD in the province. This is followed by guidance on ML/ARD prediction, measures to prevent or reduce ML/ARD, general considerations and information and design requirements for specific measures (underwater storage, blending of acid-generating wastes with materials having excess neutralization potential, covering the waste, drainage collection and treatment, and mitigation of specific mine components), and geotechnical and hydrological considerations. Finally, ML/ARD aspects of mine regulation and current ML/ARD research programs are reviewed