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<br />......... <br />m <br />~ <br />1\.:' <br /> <br />1.2 Conclusions - Surface Retortina of Oil Shale <br />Two different water management schemes have been identified for an oil <br />shale conversion complex in which surface retorting occurs. One scheme is <br />characteristic of that used for an oil shale process in which the spent shale <br />is disposed of in a manner similar to that proposed for Tosco II. The processed <br />shale is moisturized, transported to the disposal site and compacted. The <br />compacted shale has an in-place moisture content of about 13 percent after <br />compaction. The shale is moisturized with all of the wastewaters generated in <br />the plant and then SOme. This scheme obviously does not encourage reuse of <br />the wastewaters. The only treatment that would be required would be to remove <br />odorous, volatile substances, which is standard practice and is done as part <br />of the normal upgrading operation. The cost of disposal for this type of <br />management scheme is negligible. <br />The second scheme is characteristic of that used for ~~ oil shale process <br />in whi~~ the spent shale is disposed of in a manner si~ilar to that proposed <br />for Paraho. The Paraho design involves lining a valley wi~~ a thin impermeable <br />layer of compac~ed spent shale which is wetted down. The remainder of the <br />spent shale is deposited into the lined basin and is compacted, but not wetted <br />down except for controlling dust. Less than one percent of the spent shale <br />~ould be we~ted down. However, the revegetation water requirements are larger <br />for Paraho ~ecause of the higher residual carbon in the spent shale. The <br />retorting and upgrading wastewaters will have to be treated for recycle and <br />reuse within ~~e ~lant. It cannot be used directly for revegetation because <br />of its poor quality. With minimum treatment it could be disposed of in evaporation <br />ponds, but ~~is is wasteful of water. We will assume that ~he was~ewater will <br />be treatec for use in a cooling tower, in a manner similar ~o t~at fer a coal <br />gasification plant. The only costs that will be presented are for the paraho <br />process and are based upon the results presented in Section 3. The flow rates <br />and costs will be based on an oil shale complex designed to produce 50,000 <br />barrels/day of synthetic crude plus any by products not utilized as plant fuel. <br />They will. also be normalized with resp'ect to the heating value of the synthetic <br />crude, which is 2.9 ~ loll Btu/day for the 50,000 barrel/day synthetic crude <br />plant. A typical price for sha~oil is $15/barrel, or about $2.50/106 9tu. <br /> <br />7 <br />