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~~ <br /> <br />subjected to 330°F water a fall of SO pounds was indicated (profs a al., 1976). In Australia <br />aRificial weathering studies wen undertaken on Green River oil shales, assaying 9.33% oil, that <br />were crushed to <0.2 mm, After 60 weeks of weathering in glass jan open to air at a temperature <br />of 22°C the oi] shale assayed 8.47% oil, and after 60 weeks in glass jars in as air oven az 100°C <br />the oil shale essayed 2.13% oi] (Saxby, et al., 198. Low temperature retorting experimems <br />was wnducted on 63 gallon per tam Green River oil shale at the U. S. Hureaa of Mines facility in <br />Laramie, Wyoming. Beating times ranged from 90 to 360 days and temperatures ranged from <br />130°C to 33D°C (Gtirmmias and Robinson, 1972). After heating the oil shale at 130°C far 90 days <br />the sample assayed 61.3 gallons pa ton sad after 360 days 43.3 gallons pa too. The thermal <br />product from the Kerogea is mostly bitumen or bitumen plus oil. The report states "from these <br />data the implirstioas are that preheating of oil shale at 130°C-201PC has a detrimental effect upon <br />subsequent sorting yields." <br />Little infomration is available on the effect of moderately high temperature on daweonite <br />bearing oil shale. However, Dyni, a al., state-although thermal decomposition of Kerogen is <br />negligible az L03°C appreciable decomposition occurs az 220°C and interferes with the weight loss <br />products of dawsamite and further state. '~treliminary data indicate that dawsonita partly <br />decomposes at temperatures as low as 220°C when heated for 14 hours." <br />li is estimated is the Yankee Gulch Environmental Impact Statement that some time after <br />solution mining is wrrtpleted as much a, 1 to 3 feet of surface subsidence may oavr. These is <br />some evidence that eohrtioa of mahcolite and halite beds in what is now the leached zone may <br />have teased increased Fracturing and possibly subsidence in the area ovvlyimg fhe Iwchcd zone <br />in the geologic past. There sre anmaow solution breccibs of considerable areal extent in the <br />leached woe. Dyni (1974) shows several of these breecias oa his 9gutrs 2 and 3, and postulates <br />that soluton of the original saline minerals led to subsequent collapse and fracturing ofthe <br />surface rocks in the nrea. The lowermost solution breccin shown on figure 3 ie about 10 inet thick <br />