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<br />, <br /> <br />j',~ <br />" <br /> <br />The besl-knO\\n techniques ot oil.shale production <br />use above-ground plants to process the shale. lhu<, <br />oil-shale prOdUlCr<i must first mine the shale from the <br />ground, either in surfaCE' mines or in huge under- <br />ground caverns. Some oil.shale advocates have sug- <br />ge!'>led that the entire Piceance Creek Basin in Colora- <br />do could be suriano mined, "tafting .'lIthe (luter rim of <br />the basin and \\orking to the center. Besides the fact <br />that Colorado re",ideo!s would be horrified at this <br />surian- mining proposal, mo,>1 oil-company ('xperts <br />label it .'1<' impractical. <br />"The miners tel] me that thPre are ver\' f€'\\ deposits <br />of oil shale that \\Quld be suitable for surface mines," <br />explain<; Pforzheimer. "If the ratio of overburden to <br />shale i... over 1 10 1, it is probably cheaper to mine It <br />underground. Unlike the rock in coal field.., oil shale <br />provides a good roof, nN.dt'd for big rooms to permit <br />large-scal(' underground mining. So I don't think manv <br />sites will bt, strip-mined." <br />The underground mincs will generaHv be oi fht. <br />room and pillar variety. A series at rooms. limited 10 <br />about 60 teet in width and height bv present lechnolo- <br />gy, would be mined. leaving pill.us oi rock standing to <br />support the rooT. According 10 most industry sources, <br />anywhere from 60 to 75 percent of thE' availablE' oil <br />shale could be removed lrom these mines. <br />Once the ..hale has been mined. it must go through a <br />series oi crushers to grind it down inlo smaller piece... <br />The crushed shale can then be ied into oil.shale retorts <br />where the oil i.. separaTed irom its hmt rock. The <br />retorls are designed 10 heat the <;hdlp to high tempera- <br />tures, heat being the mi<,sing ingredient needed to <br />turn kerogen into a form oi crude oil. Oncf' the shale is <br />hot enough, the oil vaporize.. and can be removed <br />irom the rptort. The mining. cru..hing and retorting <br />operation.. all in(reiN,' the \'olume at the rock. Indus. <br />If>' e..timates the \'olum(' 01 processed shale will b(' <br />any\\h('r(' irom .20 10 50 percent larger than the "pare <br />irom \,hith it \\a.. mined. \\hile ..amI:" environmental- <br />i"ts haH' pUTthi.. figure much higher. <br /> <br />Developing underdeveloped oil <br />In the pu..l. retorts \\ere u<,uall\ large brid O\en<, <br />that produced. aT mo'-l. ;0 barrels oi oil per da,. For <br /> <br />8 D,Etl'Tln \\1.;1 III....nl\\...M~ E()ITIO" r..b,u.." I~~~ <br /> <br /> <br />Nearly 30 years 8g0, the Bureau of Mines rested one of <br />the first gas-combustion rerons (above) at the Anvil <br /> <br />the iuturt', somE' :o;cienti"ts h,lVe en\'i<,ioned microwave <br />hE'at and nuclE',lr {'nerg\' as '....av.. 01 unlocking ..hale oil. <br />But IOda\"s retorh, which are e:..p{"cled to product' <br />anv\\here irom 50,000 to 100.000 b.urels per dol\" <br />generall\' use more prosaic heating methods, such as <br />convenlional ht>aTer.. emplming either ga" or oil as <br />iuel... <br />Although man\' companies and group" are nO\\ in <br />the proce..~ 01 de\eloping and improving diiterent <br />retort t('(hnologie... the..e are the be..t knO\\n: <br />8ure.au of Mines relorl: In 19~~. the U.S. Bureau oi <br />,\line.. opent.'d un oil-shalE' development projecl at <br />Anvil POints nf'Jr Riile, Colo., where it tested one Of <br />thE' earlie'" ga..-combuqion retort... The relort i.. a <br />\ertieal n......"'1 through which crushed ..hale rnO\t'<' <br />do\\n b\ gra\ih and hot, rE'C\'c1ed ga<,e.. mOHO up from <br />