rrb - identifikacija rizika u projektovanju rudnika, eksploataciji i sagorevanju uljnih škr

7/31/2019 RRB - Identifikacija rizika u projektovanju rudnika, eksploataciji i sagorevanju uljnih kr

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Broj 1,2010. RUDARSKI RADOVI135

KOMITET ZA PODZEMNU EKSPLOATACIJU YU ISSN: 1451-0162MINERALNIH SIROVINA UDK: 622

UDK: 622.337:504.06(045)=861

Dejan Sokolovi*

IDENTIFIKACIJA RIZIKA U PROJEKTOVANJU RUDNIKA,EKSPLOATACIJI I SAGOREVANJU ULJNIH KRILJACA

Izvod

Zatita ivotne sredine na dananjem stepenu razvoja, kako u razvijenim, tako i u zemljama u

razvoju, postala je neophodna, jer su zbog intenzivnog razvoja energetike uticaji na nju svesloeniji. Problem je posebno sloen zbog toga to se izmeu energetske politike i politike zatite

ivotne sredine mora postii kompromis jer praktino svi energetski izvori i postrojenja imaju veiili manji uticaj na okolinu.

Razvoj proizvodnje primarne i sekundarne energije doprinosi sve veem zagaenju ivotnesredine. Zbog toga u svim zemljama zakonodavne i druge norme tretiraju zatitu vazduha, voda,zemljita, zatitu od buke i dr. od uticaja, pored ostalog i energetskih postrojenja. Najvei uticaj

na ivotnu sredinu ima proizvodnja sekundarne energije, posebno elektrine energije utermoelektranama. Svi problemi zagaenja okoline su prisutni i kod izgradnje termoelektrana nauljne kriljce, sa moda i veim intenzitetom zagaenja zbog sastava i kvaliteta uljnih kriljaca. U

ovom radu se bavimo tetnim uticajem eksploatacije i sagorevanja uljnih kriljaca na ivotnusredinu kao i identifikacijom rizika u ukupnom iskorienju uljnih kriljaca.

Kljune rei: uljni kriljci, zatita ivotne sredine, eksploatacija, sagorevanje, gasifikacija

*Ministarstvo rudarstva i energetike

UVOD

Uljni kriljci predstavljaju slojeve stena,koje sadre materijal, koji je praktino

pretea nafte. Kada se pregreva, ovajmaterijal, uglavnom kerogen, moe bitidestilisan iz stene u naftu. Obogaivanjem irafinisanjem ovog tenog destilovanogmaterijala mogu se dobiti razliite vrstekorisnog goriva. Uljni kriljci se mogueksploatisati povrinskim i podzemnim

putem i savremenim metodama podzemnegasifikacije.U zavisnosti koja se tehnologija koristi,

eksploatacija i sagorevanje uljnih kriljaca jepovezana sa velikim poremeajima i

rizicima u prirodnom stanitu, podzemnim ipovrinskim izvorima, kvalitetu vazduha iklimi. Oekivani su trajni uticaji na topogra-fiju na floru i faunu, kao rezultat komercij-alne eksploatacije i prerade uljnih kriljaca.

U sluaju povrinske eksploatacije,iskorieni tj. preraeni uljni kriljci (otpad)imaju veliki uticaj na kontaminaciju podze-mnih voda (imaju drastino veu koncentra-

ciju soli nego ruda kriljca, a mogu da sa-dre i druge toksine supstance). U sluaju

podzemne In-situ eksploatacije, procespodrazumeva veliki rizik od kontaminacijepodzemnih voda.[3]


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ZATITA KOD PROJEKTOVANJARUDNIKA

U svakom poslovanju proces projekto-vanja treba paljivo rasmotriti sa stanovitazatite ivotne sredine. Kod projektovanjarudnika za eksploataciju uljnih kriljaca uobzir se moraju uzeti nekoliko stavki:

izvriti dodatka istraivanja na zatitiivotne sredine koja e uveritilokalno stanovnitvo da tolerieuticaj eksploatacije na istu,

rudnik treba biti lociran, po mogu-stvu, to dalje od naseljenog mesta,

u blizini naseljenih mesta, minerskeradove netreba koristiti,

rudarski radovi nesmeju otetitiodreene izdani, kako bi se spreilakontaminacija voda,

zalihe uljnih kriljaca, lomljenje itransportnu jedinicu treba pomogustvu locirati u umi kako bi sespreila buka i irenje praine,

barijere za buku i prainu treba ta-koe locirati izmeu naseljenihmesta i postojenja rudnika. Za takve

svrhe potrebno je ak i zasaditidrvee

Vani zahtevi koje treba uvaiti prili-kom projektovanja su sledei:

- kako negativni uticaj na ivotnusredinu svesti na minimum?

- da li je mogue koristiti selektivan ilineselektivan metod eksploatacije?

- koja metoda eksploatacije garantujeodreenje izlazne rezultate?

- kako reducirati upotrebu odree-nim maina?

- da li kupiti ili iznajmiti maine? [2]ZAGAENJE ZEMLJITA PRIEKSPLOATACIJI

Povrinska eksploatacija prouzrokujemnoga povrinske poremeaje zemljita iima veliki uticaj na povrinske vode, pripo-vrinske vode, na floru i faunu. Iskustva kodeksplatacije uglja i drugih sirovina ukazuju

na to uticaj na okruenje je veoma veliko aliuz minimalni dugoroni efekat.

Podzemna eksploatacije prouzrokujemnogo manje povrinske poremeaje.Povrinksi poremeaji su limitirani aliukljuuju emisiju praine prouzrokovanotransportnom i skladitenje.

In-situ eksploatacija ukljuujemanje rudarskih radova, koja suograniena na buenje tzv. toplotnih

buotina i proizvodnih buotina na malomrastojanju. Uticaj na ivotnu sredinu ebiti slian kao i kod proizvodnje gasa inafte. Buotine kod ove vrste eksploatacijezahtevaju obezbeenje i plombiranje.

Drugi povrinski uticaji u najveemsluaju zavise od konstrukcije povri-nskog postrojenja, ukljuujui postrojenjeza retortovanje, nadogradnju, depono-vanje i transport. Novi cevovodi, putevi i

pratei objekti, mogu takoe imati uticajana povrinsku kontaminaciju.

Iskorieni kriljac: povrinske retorte

proizvode velike koliine obra

enog iliiskorienog uljnog kriljca. Tehnologija

retortovanja nastoji da reducira zaostaliugljenik, inei obraeni kriljac bezbe-dnijim za okruenje. Neki iskorienikriljac se moe koristiti kao komercijalnimaterijal za izgradnju ili kao materijal zarekultivaciju zemljita.

ZAGAIVAI VODE

Na veem rastojanju od rudarskih akti-vnosti ili postrojenja za retortovanje dolazido kontaminacije zemljita i podzemnih

voda. In-situ eksploatacija veoma utie nakvalitet podzemnih voda. U ovimsluajevima se zahteva kontrola i zatita

povrinskih i podzemnih voda. Efikasnetehnologije i upravljenje proce-sima su vedemonstrirane i pokazane u drugim slinimsluajevima komercija-lnog rudarenje. In-situ eksploatacija praktino ve trpi izazove


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da zatiti podzemne vode od kontami-nacije od kerogenskog ulja i drugihproizvedenih gasova i sedimenata.Obeavajua tzv. freeze-walltehnologija je testirana da izoluje

podzemne vode od pripovrinskogpodruja na kome se vri In-situ proces,sve dok se postproizvodne aktivnosti irekultivazija zemljita ne zavri. [7]

ZAGAIVAI VAZDUHA PRISAGOREVANJU ULJNIHKRILJACA

Glavni zagaivai vazduha tokomsagorevanja uljnih kriljaca su oksidi azota,sumpor dioksid, hlorovodonik i vrsteestice. Najtetniji gas koji se emituje jeCO2 . Koncentracija zagaivaa vazduhu uizduvnim gasovima, prvenstveno zavisi odtehnologije sagorevanja i reimasagorevanja, dok je emisija vrstih esticaodreena efikasnou ureaja za hvatanje

pepela u letu. to se tie emisijezagaivaa vazduha, uljni kriljac sekarakterie niskim sadrajem azota uorganskoj materiji (0,3%), velika

koncentracija organskog sumpora (1,6-1,8% u delu koji se prihvata kao gorivo),visok Ca/S odnos (8-10) i obilje mineralakarbonata (16-19% minerala CO2 u delukoji se prihvata kao gorivo).

Tokom sagorevanja goriva NOx moebiti formiran na sledee naine: u reakcijiizmeu azota i kiseonika iz vazduha(toplotni NOx), u reakciji izmeu radikalaugljovodonika i molekula azota (momen-talni ili brzi NOx) i azota iz goriva. Najva-niji parametar koji utie na koliinu oksidaazota u izduvnim gasovima je koncentaciju

kiseonika (veliki vazduni faktor).Glavna sumporna komponenta u

uljnom kriljcu je kalcijum. S toga, da bi seokarakterisao potencijal u procesu hvatanjasumpora, koristi se odnos Ca/S. Iz razlogato uljni kriljci sadre alkalne metale, deosumpora je vezan sa ovim komponentama,najee u obliku sulfata. Meutim, nisusvi alkalni metali koji su prisutni u gorivu

konvertovani u sulfate; jedan deo preven-stveno zavisi od isparljivosti alkalnihmetala iz mineralne materije u procesusagorevanja. Emisija sumpor-dioksida iobim pretvaranja u paru od dela sagorljivogsumpora, tokom sagorevanja uljnihkriljaca, zavisi od mnogo faktora.

Ugljen-dioksid spada u grupu gasovastaklene bate. Formira se u reakcijamasagorevanja organskog ugljenika i mine-rala prisutnih u gorivu kao karbonati. Punakonverzija organskog ugljenika u CO2 jemogua samo kod kompletnog

sagorevanja. Osloba

enje ugljen dioksidaiz minerala karbonata, odreena je pona-anjem minerala goriva, tokom procesasagorevanja. Tehnologija sagorevanja kojase koristi za gorenje goriva, ne utieznaajno na efekte i koliinu formiranjaCO2 od organskog ugljenika. Svakakotehnologija sagorevanja ima veliki uticajna emisiju minerala CO2. Koncentracijaminerala CO2, formirana od karbonatnih

jedinjenja, odreena je uslovima termikerazgradnje minerala i takoe direktnimsagorevanjem gasovitih komponenti

prisutnim u izduvnim gasovima i mineralakoji sadre CO2. [4]

UTICAJ PODZEMNEGASIFIKACIJE

Briga o ivotnoj sredini je jedan odvanijih inilaca koju treba uzeti u obzirkada se pristupa procesu podzemnegasifikacije (PG) i ako je njen uticaj naivotnu sredinu jedva primetan i veomanizak. Glavni proizvod gasifikacije je gas,iako izvesni nusproizvodi ostaju pod

zemljom, ili se koriste od stranekonvencionalnih procesa ili injektuju nazadu sloj. U isto vreme imamo jo uveknekoliko znaajnih uticaja koji se morajuuzeti u obzir, naroito, podzemni i nadzemniuticaj. U osnovi hidroloka, geoloka ihidrogeoloka istraivanja i njihova ocena semoraju obaviti prvenstveno u skladu saoperacijama podzemne gasifikacije.


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PG na ivotnu sredinu moe imatiuticaja na:Radno mesto,buku,emisija gasova u atmosferu,kontaminaciju podzemnih voda,sleganje terena.Prednosti uticaja PG a na tretiranje

sloja su:Izostanak praine na povrini,proizvodnja istog gasa,visoka efektivnost koja se ostvaruje

u gasnim turbinama,odsustvo gasifikatora na povrini.Mane uticaja PG a na tretiranje sloja

su:Podzemna kontaminacija,povrinska kontaminacija,procesni zagaivai.

Pripovrinska kontaminacija

Kontaminacija podzemnih voda

Imamo nekoliko komponenti koja supovezana sa kontaminacijom podzemnih

voda. Znaaj tih komponenti suposmatrani i istraivani u cilju mini-miziranja i/ili eliminisanje rizika i

poveanje znaaja faktora koji supovezani sa kontaminacijom. Ispitivanjasu pokazala da je mali procenat fenola i

benzena nastao kao produkt procesapodzemne gasifikacije. Vei procenatzajedno sa proizvedenim gasom dolazi do

povrine gde se eliminie u procesupreiavanja. Svakako, ostatak prolazikroz okolno slojeve ili biva absorbovan odstrane neporemeenih slojeva, a preostalose zadrava u takozvanim izduvanimupljinama.

Propustljivost, hidrogeoloka igeoloka struktura sloja uljnih kriljaca eimati najvei uticaj na rasejavanjekontaminacije. Od velike vanosti je da jehidrologija potpuno poznata, a samastruktura e pokazati gde je mogunostkontaminacije najmanja.

Sam projekat mora potpuno da iscrpinajobimnije istrane radove koji su vezaniza dubinu ugljenog sloja i monitoring pre i

posle procesa gasifikacije na odreenompodruju.

Na hidrologiju i kvalitet podzemnihvoda, mogu imati uticaj produkti procesakao rezultat sagorevanja uljnih kriljaca.

Neki od njih su: praina, katran, umur,fenoli, benzen, metilbenzol, ksilen, bor,cijanid i ugljovodonici.

Curenje gasa iz upljina okolnih slojevamoe biti problem kod procesa PGa u

plitkim slojevima tj. pri povrinskimslojevima. U isto vreme ak i u uslovimagasifikacije na veim dubinama, zagaivaimogu da dopru do povrine putem

podzemnih voda, du podzemnih frakturasamog terena. Veoma je vano da targetno

podruje bude to dalje od postojeihrudnika i birati rudnike na veoj dubini. Ucilju minimiziranja curenje ili beanja gasa,veoma je vano birati podruja sa niskom

propustljivou slojeva i kontrolisatipritisak tokom samog procesa, da budekoliko je mogue priblian hidrostatikom

pritisku.Sleganje terena

Sleganje terena se obino javlja kadase narui stabilnost tla, usled procesa PGa u pripovrinskim slojevima. Ovo se presvega odnosi na slojeve koji se nalaze

blie povrini, dok su kod dubljih slojevaefekti minimalni. injenica je da se sadubinom smanjuju efekti sleganja terena.

Povrinska kontaminacija

Postrojenje za gasifikaciju koje se

nalazi na povrini ukljuuje: glavebuotina, opremu za buenje, odgovara-jue cevovode, postrojenje za preradu iinjektovanje/proizvodnju gasa, itd. Uticajna ivotnu sredinu mogu imati:

Otpadne vode koje nastaju tokomgasifikacije,

otpadne vode koja nastaje tokompodzemne filtracije,


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Otpadne vode od samogpostrojenja za proizvodnju gasa

emisija gasova koja nastaje tokomproizvodnje/sagorevanjem,

izlivanje ulja, mogue otpadne vode kao

posledica izlivanja, izlivanja saspojeva i hlaenja,

mogue zagaenje od vrstogostatka sa deponija.

Osim toga, mora se voditi rauna ospreavanju emisija CO2 koje nastaje kaorazultat procesa, uticaju na povrinskevode, uticaju na podzemne vode, zvucima(buka) koji nastaju tokom procesa i ostalihefekata i negativnih uticaja na oveka iokolinu.

Emisija gasova

Imamo dva glavna inilaca koja utiuna emisiju gasova koju izazivaju i

povrinski i pripovrinski procesi. Najveaemisija tetnih materija nastala tokom

procesa gasifikacije ukljuuje:Gasovite materije:-hidrogen, karbon dioksid, karbon -

monoksid, sumpor, kiseonik

Organske materije:

-Eterine ugljovodonike: metan, etan,etilen, propan

-Aromatini ugljovodonici: benzoli,metil benzol, benzeni, naftaleni

-Organske kiseline: fenoli, alkil fenoli, naftol, alkil naftol

-Organske baze: piridin, metil piri-din, anilin, indolin, kinolin, isokinolin

-Zasieni/Ciklini ugljnovodonici: N alkali, ciklini alkali

-Nezasieni ugljovodonici: olefini

Neorganske materije:Bor, fluorid, bromid, hlorid, selika,

litijum, sulfat, mangan, amonijak,sodijum, sulfid, gvoe, kalcijum, cijanid,

barijum, kalij, magnezijum.Uticaj na:-Kvalitet vazduha,-ozonski omota,-staklena bata.Veina zagaivaa nastala tokom

procesa anuliraju se tokom samogprocesa. Tokom rada samog generatora,tragovi SO2 i NOx, bivaju otputeni uatmosferu, a CO2 ostaje zaplenjen.Zaplena CO2 ukljuuje izdvajanje CO2 idelom injektovanje nazad pod velikim

pritiskom.Glavni problem kod zagaenja

povrinskih voda tokom procesa PGa jeispumpavanje bez odgovarajueg filtra-cionog procesa u reni sistem, prirodneizvore i izlivanje tokom procesa i buenja.U susret kontroli otpadnih voda, odgova-rajue mere moraju biti sprovedene,takoe i tokom samog procesa.

Uticaj procesa podzemne gasifikacijena oveka je minimalan. Glavni faktori su

poveanje buke, praina i zagaenje pijaevode. [1]

ZAKLJUAK

Zatita ivotne sredine na dananjemstepenu razvoja, kako u razvijenim, tako iu zemljama u razvoju, postala jeneophodna, jer su zbog intenzivnograzvoja energetike uticaji na nju svesloeniji. Problem je posebno sloen zbogtoga to se izmeu energetske politike i

politike zatite ivotne sredine morapostii kompromis jer praktino svienergetski izvori i postrojenja imaju veiili manji uticaj na okolinu.


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Iz svega navedenog moe se izvuisledee:

-Proizvodnja energije od uljnih kriljacaje veoma intenzivan proces. Po nekimprocenama ulaganje energije uproizvodnju ulja od uljnih kriljaca jeskoro isto toliko velika kao i prinos.

-Proizvodnja energije od uljnih kriljacauzrokuje vie gasova staklene batenego proizvodnja konvencionalnog

gasa. Ovi zagaivai vazduha, kao tosu sumpor dioksid, oksidi azota i fineestice su povezane sa veomuestalou respiratornih oboljenja,ukljuujui astmu, emfizemu ismanjenje kapaciteta plua.

-Ovaj vid proizvodnje koristi izmeu 3 i5 barela vode, za svaki barel

proizvedene nafte. Analiza koliinavode koje su potrebne za tretiranjeuljnih kriljaca moraju uzeti u obzirtrenutre i oekivane potrebe za vodom.

-Nedovoljno se zna o tome kakospreiti kontaminaciju voda sa

povrinskih i in-situ operacija.-Ekstrakcija moe imati dugotrajan

ekoloki uticaj, ukljuujui pore-meenu oblast na kojoj su se vrilirudarski radovi i oblast deponijaiskorienog uljnog kriljca. [5]

Moderni projekti iskorienja uljnihkriljaca, obuhvatae kontrolu i razliitesaglasnosti na idejno reenje projekta iekonomsku projekciju. Ekoloke kara-kteristike specifinih tehnologija e se

morati ocenjivati na osnovu regulativezatite ivotne sredine za svaku zemlju.

LITERATURA

[1] D. Sokolovi, Istraivanje redosleda idinamike istovremenog podzemnogotkopavanja leita uglja i uljnihkriljaca u funkciji optimalnogiskorienja energetskog potencijala,Magistarska teza, Beograd, 2009.

[2] T. Kattel, Design of a new oil shalesurface mine, Oil Shale, Vol. 20, No4, pp. 511-514, Estonian AcademyPublishers, Talin, Estonia, 2003.

[3] Oil Shale in the West: 14 UnansweredQuestions, Headwaters Economics,Bozeman, Montana, USA, 2009.www.headwaterseconomics.org//energy

[4] A. Ots, Estonian oil shale propertiesand utilization in power plants,Energetika, Vol. 53. No. 2. pp. 818,Tallinn University of Technology,Tallinn, 2007.

[5] Pew Environment Group, Dirty FuelsFactsheet Series: Oil Shale, 2009.

[6] John W. Shages and Anton R.

Dammer, U. S. Department of Energy,Americas Oil Shale A Roadmap forFederal Decision Making, 2004, p. 16,www.fossil.energy.gov/programs/reserves/npr/publications/oil_shale_roadma

p.pdf.[7] Department of Energy Office of

Petroleum Reserves. Fact Sheet: OilShale and the Environment, p. 2,www.unconventionalfuels.org/publications/factsheets/Oil_Shale_Environmental_Fact_Sheet.pdf.


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No 1,2010. MINING ENGINEERING141

COMMITTEE OF UNDERGROUND EXPLOITATION OF YU ISSN: 1451-0162

THE MINERAL DEPOSITS UDK: 622

UDK: 622.337:504.045(045)=20

Dejan Sokolovi*

RISK IDENTIFICATION IN THE MINE DESIGN, EXPLOITATION

AND COMBUSTION OF OIL SHALE

Abstract

Environmental protection at the recent level of development, both in developed and developingcountries, has became necessary, due to more intensive energy development, the impacts on it are

much more complex. The problem is particularly complex because a compromise between theenergy policy and environmental policy has to be achieved. Practically, all energy sources andplants have more or less impact on the environment.

Development in production of primary and secondary energy contributes to the increased envi-ronment pollution. Therefore, in all countries the legislative and other norms treat the protection

of air, water, soil, noise protection, etc., among other things, and power plants. The biggest impacton the environment is the production of secondary energy, especially electricity in the powerplants. All problems of environment pollution are also present in the construction of thermal

power plants on oil shale, with perhaps greater intensity of pollution due to the quality and com-position of oil shale. This paper deals with harmful effect of exploitation and combustion of oil

shale on the environment and risk identification of risk in overall utilization of oil shale.Key words: oil shale, environmental protection, exploitation, combustion, gasification

*Ministry of Mining and Energy

INTRODUCTION

Oil shales are the rock layers, which con-tain the material that is practically the fore-runner of oil. When this material is over-heated, mainly kerogen, it could be distilledfrom rocks in the oil. By enrichment andrefining of this distilled liquid material, vari-

ous kinds of useful fuel could be obtained.Oil shale could be exploited by surface, un-derground and using the modern methods of

underground gasification.Depending on which technology is inuse, the exploitation and combustion of oilshale is associated with large disturbancesand risks in the natural habitat, underground

and surface sources, air quality and climate.

The permanent impacts on topography andflora and fauna are expected as the result ofcommercial exploitation and processing ofoil shale.

In a case of surface exploitation, theused, i.e. processed oil shale (waste) has agreat impact on contamination of under-

ground water (have dramatically higher

concentration of mineral salt than slate,and may also contain other toxic sub-stances). In a case of underground (in-situ)the exploitation, the process involves arisk on groundwater contamination [3].


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PROTECTION IN THE MINEDESIGNING

In any business, the design processshould be carefully considered from thestandpoint of environmental protection. Inthe mine designing for exploitation the oilshale, several items have to be taken intoaccount:

to carry out the additional researchesto environmental protection that willconvince the local population to tol-erate the exploitation impact of the

same,the mine have to be located, if possi-ble, away from the settlements,

in the vicinity of settlements, theblasting works should not be used,

the mining works must not damagethe certain aquifers in order to pre-

vent the water contamination,

oil shale stocks, breaking and trans-port unit should preferably be locatedin the forest to prevent the spread ofnoise and dust,

barriers to noise and dust should alsobe located between the settlementsand existence of mine . For such pur-

poses it is even necessary to planttrees.

Important requirements that need to betaken into account during designing are:

- how negative environmental impactsbe minimized?

- is it possible to use selective or non-selective method of exploitation?

- which method of exploitation guaran-

tees determination of output results?

- how to reduce the use of certain ma-chines?- whether to buy or rent a machine? [2]

SOIL POLLUTION IN THE

EXPLOITATION

Surface exploitation causes a lot ofsurface disorders of land and has a high

impact on surface water, subsurface water,flora and fauna. Experiences in coal ex-

ploitation and other raw materials indicatethat the impact on environment is veryhigh but with minimum long-term effect.

Underground exploitation causesmuch less surface disorders. Surface dis-orders are limited but include dust emis-sions caused by transport and storage.

In-situ exploitation involves lessmining works that are limited to drilling ofso called thermal drill holes and produc-

tion drill holes at a small distance. Impacton the environment will be similar to theproduction of gas and oil. Drill holes ofthis type of exploitation require securityand sealing.

Other surface effects in most case de-

pend on construction of surface facilities,including equipment for retorting, upgrade,dumping and transportation. New pipelines,roads and related facilities, may also havean impact on surface contamination.

Spent shale: surface retorts producelarge quantities of processed or spent oil

shale. Technology of retorting seeks toreduce the residual carbon, making theprocessed shale safer for the environment.Some spent shale could be used as a com-mercial material for construction or as amaterial for re-cultivation of the land.

WATER POLLUTANTS

At larger distance from the mining op-

erations or facilities for retorting, the soil

and ground water contamination appears.In-situ exploitation has high effect on

the ground water quality. In these cases, a

control and protection of surface and

ground water sis required. The efficient

technologies and process management

have been demonstrated and shown in the

other similar cases of commercial mining.


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Practically, the in-situ exploitationsuffers the challenges to protect theground water on contamination by the

kerogene oil and other produced gases andsediments. Promising so called freeze-

wall technology has been tested to isolatethe groundwater from subsurface areawhere the in-situ process is carried outuntil the postproduction and remediationactivities of land is complete. [7]

AIR POLLUTANTS IN THE

OIL SHALE COMBUSTION

The main air pollutants in the oil shalecombustion are nitrogen oxides, sulfurdioxide, hydrogen chloride and solid par-

ticles. The most harmful gas that is emit-ted CO2. Air pollutant concentration in the

exhaust gases primarily depends on com-bustion technology and combustion re-gime, while the emission of solid particlesis determined by the efficiency of devicefor catching the fly ash. Regarding to theemission of air pollutant, oil shale is char-

acterized by low content of nitrogen inorganic matter (0.3%), high concentrationof organic sulfur (1.6 to 1.8% in a part thatis accepted as a fuel), high Ca /S ratio (8-10) and an abundance of carbonate miner-als (16-19% mineral CO2 in a part that isaccepted as a fuel).

NOx during fuel combustion can beformed in the following ways: in the reac-

tion between the nitrogen and oxygenfrom the air (thermal NOx), in the reactionbetween hydrocarbon radicals and mo-lecular nitrogen (immediate or rapid NOx)and nitrogen from fuels. The most impor-tant parameter that affects the amount of

nitrogen oxides in the exhaust gases isoxygen concentration (high air factor).

The main sulfur component in the oilshale is calcium. Therefore, in order tocharacterize the potential in the process ofsulfur capturing, the ratio Ca/S is used.Because oil shale contains the alkalinemetals, a part of sulfur is linked with this

component, usually in a form of sulfate.

However, not all alkali metals present inthe fuel converted to sulfate, primarily onepart depends on the volatility of alkali

metals from mineral matter in the combus-tion process. Emission of sulfur dioxide

and volume of conversion into vapor fromthis part of combusted sulfur, during com-bustion of oil shale, depends on manyfactors.

Carbon dioxide is classified as a green-house gas. It is formed in the reactions of

combustion the organic carbon and miner-als present in the fuel as carbonates. Full

conversion of organic carbon in CO2 ispossible only in complete combustion. Re-lease of carbon dioxide from the carbonatemineral, is determined by the behavior offuel mineral in the combustion process.Combustion technology that is used for fuelburning does not affect significantly the

effects and quantity of CO2 formation fromorganic. Certainly, the combustion technol-ogy has a great impact on emission of CO2mineral. Concentration of CO2 mineral,formed by the carbonate compound, is de-termined by the conditions of thermal de-

composition of minerals and also by directcombustion of gaseous components present

in the exhaust gases and minerals that con-tain CO2. [4]

EFFECT OF UNDERGROUND

GASIFICATION

Care about the environment is one ofthe most important factors that have to betaken into account when it is accessed tothe process of underground gasification(UG) and if its impact on the environmentis barely noticeable and very low. The

main product of gasification is gas, al-though some by-products remain under

the earth, or used by the conventionalprocesses or injected back into the layer.At the same time there are still some sig-nificant impacts that must be taken intoaccount, in particular, the undergroundand above-ground impact. Basically, hy-

drological, geological and hydrogeologi-


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cal explorations and their evaluation mustbe primarily done in accordance with theoperations of underground gasification.

UG on the environment could have animpact on:

PositionNoiseEmissions of gases into atmosphereGroundwater contaminationGround subsidenceAdvantages of UG impact on a treat-

ment of layer are:

The lack of dust on the surfaceProduction of pure gasThe achieved high efficiency in the

gas turbines

The absence of gasifier on the sur-face

Disadvantages of UG impact on a

treatment of layer are:

Underground contaminationSurface contaminationProcess pollutants

Subsurface contamination

Groundwater contamination

There are several components linked tothe contamination of ground water, impor-tance of these components are monitoredand investigated in order to reduce and / oreliminate risks and increase the importance

of factors related to contamination. Testshave shown that a small percentage of phe-nol and benzene were formed as a productof underground gasification process.Higher percentage with produced gascomes to the surface where it is eliminatedin the process of purification. Certainly, the

rest passes through the surrounding layersor was absorbed by the undistributed lay-ers, and the remaining is retained in theso-called blown out cavities.

Permeability, hydrogeological andgeological structure of shale layer willhave the greatest impact on dispersingcontamination. It is of great importancethat the hydrology is completely known,

and structure itself will show where thesmallest possibility of contamination is.The project have to exhaust com-

pletely the most extensive exploratoryworks related to the depth of coal layer

and monitoring before and after the gasifi-cation process in a particular area.

The process products as the result ofoil shale combustion could have influenceon hydrology and groundwater quality.Some of them are: dust, tar, charcoal, phe-

nols, benzene, methyl benzene, xylene,boron, cyanide and hydrocarbons.

Leakage of gas from the cavities ofsurrounding layers may be a problem inthe process of UG in the shallow layers,i.e. subsurface layers. At the same time,even in the conditions of gasification atgreat depths, pollutants may reach thesurface by the ground water, along the

underground fractures of the ground. It isvey important that the target area is as faras possible from the existing mines and toselect mines at greater depth. In order tominimize leakage or escape of gas, it isvery important to select the areas with low

permeability of the layers and control thepressure during the process, to be as much

as possible close to the hydrostatic pres-sure.

Ground subsidence

Ground subsidence usually occurswhen you disturb the soil stability is dis-turbed due to the UP in subsurface layers.This primarily refers to the layers closer tothe surface, while in deeper layers the

effects are minimal. The fact is that thedepth reduces the effects of ground subsi-

dence.

Surface contamination

Gasification plant located on the sur-face includes: drilling heads, drillingequipment, appropriate piping, processing

and injection / gas production plant, etc.Impact on the environment may have the

following:


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Waste water created during the gasi-fication

Waste water created during the un-derground filtration

Waste water from the plant for thegas production

Gas emissions resulting from theproduction / combustion

Oil spillagePossible waste water as the result of

discharges, leakages from joints andcooling

Possible contamination of solid de-bris from landfills

In addition, a care must be taken toprevent emissions of CO2, formed as theresult of process, the effect on surfacewater, the effect on groundwater, sounds(noise) that occur during the process andother effects and adverse impacts to hu-mans and environment.

Gas emission

There are two main factors that affectthe gas emissions caused by the surfaceand subsurface processes. The highestemission of harmful substances createdduring the gasification process includes:

Gaseous matters:

- Hydrogen, carbon dioxide, carbonmonoxide, sulfur, oxygen

Organic matters:- Essential hydrocarbons: Methane,

ethane, ethylene, propane- Aromatic hydrocarbons: Benzenes,

methyl benzene, benzenes, naphtha-lenes

- Organic acids: Phenols, alkyl phe-nols, naphthol, alkyl naphthol

- Organic bases: Pyridine, methyl pyri-dine, aniline, indolyne, kinolyne,isokinolyne

- Saturated / Cyclic hydrocarbons: N -Alkali, cyclic alkali

- Unsaturated hydrocarbons: Olefins

Inorganic matters:- Boron, fluoride, bromide, chloride,selika, lithium, sulfate, manganese,

ammonia, sodium, sulfide, iron, cal-cium, cyanide, barium, potassium,magnesium.

Influence on:

- Air quality- Ozone layer- Greenhouse

The majority of pollutants created dur-ing the process are annulated in the proc-ess. During generator operation, the traces

of SO2 and NOx, are discharged into theatmosphere, and CO2 remains sequestered.

Sequestration of CO2 includes the elimina-tion of CO2 and partly its injection backunder high pressure.

The main problem of pollution the sur-face water during the process of PG ispumping without proper filtering proc-

esses into the river system, natural re-sources and spilling during the processand drilling. Towards the control of wastewater, adequate measures must be imple-

mented, also in the process.The influence of the underground gasi-fication process to humans is minimal.

The main factors are the increase in noise,dust and pollution of drinking water. [1]

CONCLUSION

Environmental protection at todaylevel of development, both in developed

and in developing countries, has becomenecessary because, due to intensive energydevelopment, the impacts on it are moreand more complex. The problem is par-ticularly complex because a compromisemust be achieved between the energy pol-icy and environmental policy due to a fact

that practically all energy sources andsystems have a greater or less impact on

the environment.


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From all the above, the followingscould be made:

-Energy production from oil shale is avery intensive process. By some es-

timates, an investment of energy inthe production of oil from oil shale isalmost as large as the yield.

-Energy production from oil shalecauses more greenhouse gas thanconventional gas production. Theseair pollutants like sulfur dioxide, ni-

trogen oxides and fine particles areassociated with higher incidence ofrespiratory diseases, includingasthma, emphysema, and reduce lungcapacity.

-This type of production uses between3 and 5 barrels of water for everybarrel of produced oil. Analysis of

water amount needed for treatmentof oil shale must be taken into ac-count for currently and expectedneeds for water.

-Not enough is known about how toprevent contamination of water fromthe surface and in-situ operations.

-Extraction could have long-term eco-logical effects, including the im-paired area where the mining is car-ried out and the area of spent oilshale waste dumps. [5]

The modern projects of utilization theoil shale will include a variety of controland approvals of the project feasibilitystudy and economic evaluation. Environ-

mental characteristics of specific tech-

nologies will have to be evaluated on thebasis of environmental regulations foreach country.

REFERENCES

[1] D. Sokolovi, Research of Order andDynamics of Simultaneous

Underground Mining of Coal and OilShale Deposits in a Function ofOptimum Utilization the EnergyResources, Master Thesis, Belgrade,2009 (in Serbian)

[2] T. Kattel, Design of a New Oil Shale

Surface Mine, Oil Shale, Vol. 20, No4, pp. 511-514, Estonian AcademyPublishers, Tallinn, Estonia, 2003;

[3] Oil Shale in the West: 14 UnansweredQuestions, Headwaters Economics,Bozeman, Montana, USA, 2009:

www.headwaterseconomics.org/energy;

[4] A. Ots, Estonian Oil Shale Propertiesand Utilization in Power Plants,Energetika, Vol. 53. No. 2. pp. 818,

Tallinn University of Technology,Tallinn, 2007;

[5] Pew Environment Group, Dirty FuelsFactsheet Series: Oil Shale, 2009;

[6] John W. Shages and Anton R.Dammer, U. S. Department ofEnergy, Americas Oil Shale ARoadmap for Federal DecisionMaking, 2004, p. 16,www.fossil.energy.gov/programs/rese

rves/npr/publications/oil_shale_roadmap.pdf;

[7] Department of Energy Office ofPetroleum Reserves. Fact Sheet: OilShale and the Environment, p. 2,

www.unconventionalfuels.org/publica

tions/factsheets/Oil_Shale_Environmental_Fact_Sheet.pdf

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