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Kerogen—Mineral bonding and beneficiation studies with a carbonate oil shale, using carbonic acid attack and a novel explosive disintegration technique
Fuel Processing Technology, 10 (1985) 163--168
163
Elsevier Science Publishers B.V., Amsterdam -- Printed in The Netherlands
KEROGEN--MINERAL BONDING AND BENEFICIATION STUDIES WITH A CARBONATE OIL SHALE, USING CARBONIC ACID ATTACK AND A NOVEL EXPLOSIVE DISINTEGRATION TECHNIQUE
KEITH G. McLAREN
CSIRO, Division of Energy Chemistry, Private Mail Bag 7, Sutherland, NSW 2232 (Australia) (Received August 15th, 1984; accepted September 25th, 1984)
ABSTRACT CO2 and water under pressures up to 5.2 MPa and temperatures up to 200°C have been used to attack the mineral matrix of a carbonate oil shale from Julia Creek, Australia. In most experiments the chemical attack was coupled with an explosive depressurisation process (Siropulper) which produced considerable comminution of the shale. Changes in kerogen--mineral bonding and potential for beneficiation were assessed by float--sink separations. No kerogen was liberated, and only small amounts of kerogen-enriched material were freed by these treatments, even where all the carbonate minerals had been dissolved. Carbonate minerals do not appear to play any special role in bonding kerogen in this shale, and these disintegration techniques show no promise for gravity beneficiation processes with it.
INTRODUCTION
Results from various beneficiation studies suggest that carbonate minerals may play an important role in the bonding of kerogen to the mineral matrix of some oil shales. Thomas and Lorenz [1] reported that pretreatment of Colorado shale to remove carbonates was necessary to get good separations of enriched material by a centrifugal method. In liquid--liquid pelletization experiments with Dow-Colony shale [2], the kerogen-enriched pellets were found to retain or concentrate the calcium and magnesium carbonates. Froth-flotation studies with Anvil Points shale [3] showed the calcite and dolomite accompanied the kerogen. Chemical bonding between carbonate minerals and organic matter in oil shales has been postulated by other workers [4--7 ]. This communication presents experiments in which kerogen--mineral bonding in a carbonate off shale was studied using carbonic acid attack and explosive disintegration techniques.
0378-3820/85/$03.30
© 1985 Elsevier Science Publishers B.V.
164 EXPERIMENTAL
Oil shale The oil shale was from the Julia Creek deposits, part of the vast Toolebuc Formation in Queensland, which is considered to be of marine origin. The main minerals are calcite and quartz; the dolomite c o n t e n t is less than 3%. In general, Julia Creek shale is characterized by a high vanadium content (up to 0.5%, partly in the form of porphyrins), and by kerogens with high sulphur (5--8%) and nitrogen (2--3%) contents, and low H/C atomic ratios (around 1.3), indicating aromaticity around 60% [8--9]. The organic matter occurs mainly as bands and lenses of low-reflectance vitrinite-like material, interbedded and closely associated with calcite [10]. Analytical data for Julia Creek oil shales and for the particular sample used in this work, are given in Table 1. TABLE1 Data on Julia Creek oil shale
SiO 2
CaCO3 Mg (total) Pyrite Organic carbon Bitumen a Kerogen content (approx.) Oil yieldb Density (dry)
Typical range of values for raw shales [16 ], wt.% (dry basis)
Data for sample used in this work, wt.% (dry basis)
25--40 30--60 0.2--0.4 1--2 12--16
N.D. 33.2 1.1 (MgCO3) N.D. 13.3 1.2 20.8 74 dms tonne-1 2.26 gem -s
50--90 dm3 tonne-1
aExtractable with mixture benzene: methanol 60:40. bModified Fischer assay.
Siropulper process The Siropulper explosive depressurisation technique was developed by Manners [11--12] for woodpulping, and gives good disintegration effects with short reaction times. It had n o t previously been tried with oil shale. The pilot plant (at CSIRO Division of Chemical and Wood Technology, Clayton, Victoria) has a digester with a m a x i m u m internal diameter of 115 ram, an overall length of 1000 mm and a working volume of 6 dm 3. The digester is heated by injection of steam (1.72 MPa), and pressurized by gas from cylinders. It features fast pressure release via a ball valve which is opened pneumatically in less than 0.1 s, explosively discharging the contents
165 at near sonic velocities through a specially designed nozzle (18 mm i.d., fitted with eight 4.8-mm diameter bars spaced 12.5 mm on centres), against a metal striker plate in a collecting tank which retains all solids and liquor, but permits the escape of gas and steam. In hot runs the charge was 1 kg shale (2380--710/~m) and 1.5 dm 3 water, and the reaction was carried out at 200°C for 10 rain after a heat-up time of 3--5 rain. Operating gas pressures were 13.8 MPa (N2) or 5.2 MPa (CO2). Some Siropulper runs were carried out using CO2 at ambient temperature (16--21°C) with the aim of dissolving as much carbonate mineral as possible. Because of solubility limitations, in these runs 66 g shale and 6 dm 3 water were used. It was n o t possible to stir the reactor, so the digestions were continued for 16--21 h. After discharge from the reactor, all of the insoluble material was recovered by decantation and filtration through a fine filter. Float--sink tests were carried out using carbon tetrachloride--tetrabromoethane mixtures, and 20 g shale in 100 cm a stoppered cylinders. Float fractions were analysed for carbon c o n t e n t after removal of all extractable organic material and mineral carbonates, so that only insoluble kerogen was being assayed. RESULTS AND DISCUSSION
Effects of Siropulper treatment (i) Comminution In the h o t treatments about 54% of the shale was reduced below 710 pm. " F i n e s " (< 150 ~m) were about 15%. In cold runs the corresponding amounts were 27% and 5%.
(ii) Leaching effects Raw shale contained 1.2% of solvent-extractable organic material. In h o t runs 28--35% of this organic material was lost by being rendered soluble or possibly by being volatilized in the discharge process. There was no such loss in ambient temperature runs. Only 13.4% of the mineral carbonates was removed in the 16--21 h runs with CO2 at ambient temperature, due to the lack of stirring. In the 10 min run with CO2 at 200°C, 4.7% of the carbonates was removed. Most of the small calcium sulphate c o n t e n t (1.18% total) was removed in the various runs.
(iii) Separation of kerogen-enriched material The flotation results are summarised in Table 2, where the ratio of percentage recovery of kerogen to weight percentage of shale is shown as an arbitrary "beneficiation f a c t o r " (BF). With control samples BF values were very low (1.16--1.19). Siropulping treatments did n o t liberate any kerogen, and produced only small amounts of moderately enriched material (BF = 2.4--1.65, with kerogen recoveries up to 10.3%). At kerogen recovery levels
166 TABLE 2 Sink--float tests on Julia Creek oil shale given various treatments Sample treatment
Specific gravity of float medium
Kerogen recovery in float, %
Float yield, % w/w
Beneficiation factor
(A)
(S)
(A/B)
2.007 2.060 2.105 2.156
16.7 57.0 64.0 77.3
14.4 48.3 54.6 66.8
1.16 1.19 1.17 1.16
2.007 2.060 2.103 2.193
1.2 3.1 3.7 27.2
0.5 1.7 2.3 20.0
2.40 1.82 1.61 1.36
b 200°C, 10 rain, C O 2 - - 5.2 MPa
2.007 2.060 2.193
3.1 10.3 41.8
1.5 6.0 32.1
2.07 1.72 1.30
c 16--21°C, 16--21 h, CO~ -- 5.2 MPa (13.4% of carbonate dissolved)
2.007 2.060 2.103 2.193
4.2 6.2 8.4 81.0
2.0 3.5 5.1 63.7
2.10 1.77 1.65 1.27
All carbonates removed 1.80 by acid leaching 1.90 2.007 2.105
3.6 21.8 38.7 82.6
2.0 14.4 28.0 70.9
1.80 1.51 1.38 1.17
Nil
Siropulped" a 200°C, 10 min, N 2 - - 13.8 MPa
All initially - 8 +22 mesh (2380--710 urn). o f m o r e practical i n t e r e s t ( 4 2 - - 8 1 % ) BF was 1 . 3 0 - - 1 . 2 7 , m a r g i n a l l y b e t t e r t h a n f o r u n t r e a t e d shale. T h e small i m p r o v e m e n t in b e n e f i c i a t i o n a p p e a r s t o be due t o p h y s i c a l c o m m i n u t i o n r a t h e r t h a n t h e r m a l e f f e c t s , f o r a m b i e n t t e m p e r a t u r e runs gave results similar to t h o s e at 200°C. I n c r e a s i n g t h e pressure f r o m 5.2 MPa (CO2) t o 13.8 MPa (N2) h a d n o discernible effect. T h e S i r o p u l p e r t e c h n i q u e s h o w s n o p r o m i s e as a m e a n s o f i m p r o v i n g g r a v i t y - t y p e b e n e f i c i a t i o n yields w i t h this shale, especially as in its p r e s e n t f o r m , t h e shale has first to be r e d u c e d t o a relatively small size. While strict c o m p a r i s o n s c a n n o t be m a d e , it is i n t e r e s t i n g to c o m p a r e these results w i t h s o m e r e p o r t e d r e c e n t l y f o r h e a v y m e d i u m s e p a r a t i o n s (HMS) w i t h c o a r s e r material. T h u s , L a r s o n ' s d a t a [13] f o r l a b o r a t o r y - s c a l e HMS w i t h G r e e n River shale indicate BF values a r o u n d 1.36 at 65% k e r o g e n r e c o v e r y ( - 3 in + 1 / 4 in shale), a n d 1.24 at 84% r e c o v e r y ( - 3 / 4 in + 1 / 4 in shale). R e e v e s ' large-scale tests [14] w i t h C o l o r a d o shale ( < 1 . 8 in), using t h e D u t c h S t a t e Mines h e a v y m e d i u m c y c l o n e process, indicate BF values o f 2.06 at 65% k e r o g e n r e c o v e r y , a n d 1.36 at 82% k e r o g e n r e c o v e r y .
167
Kerogen--carbonate mineral bonding In the Siropulper runs the addition of carbon dioxide to attack carbonate minerals had no discernible effect on the liberation of kerogen-enriched material, nor did the prolonged carbonic acid attack in which 13.4% of the carbonates was dissolved. Furthermore, parallel tests were run with shale from which all carbonates had been leached, using a small stirred pressure vessel similar to that used by Thomas [15]. BF values were much the same as those with shales given Siropulper treatment. These results indicate that mineral carbonates do n o t play any special role in the bonding of kerogen to the matrix of this Julia Creek shale. ACKNOWLEDGEMENTS
The author wishes to thank Dr H. Mamers and Mr D.J. Menz (CSIRO, Division of Chemical and Wood Technology, Clayton, Victoria) who carried out the Siropulper runs and made me welcome in their laboratory. Thanks are also due to C.S.R. Ltd, who provided a bulk sample of Julia Creek shale, and Mr G.C. Wall, CSIRO, Division of Energy Chemistry, for Fischer Assays.
REFERENCES
1 Thomas, R.D. and Lorenz, P.B., 1970. Use of centrifugal separation to investigate h o w kerogen is bound to the minerals in oil shale. U.S. Bur. Mines, Rep. Invest.,7378. 2 Reisberg, J., 1981. Beneficiation of Green River oil shale by pelletization. A C S Symp. Set., 163: 155. 3 Krishnan, G.N., Farley, E.P. and Murray, R.G., 1983. Benficiation of U.S. oil shales by froth flotation. Sixteenth Oil Shale Symposium Proceedings, Colorado School of Mines Press, Golden, CO, p. 426. 4 Jones, D.G. and Dickert, Jr., J.J., 1962. Compositions and reactions of oil shale of the Green River formation. Papers to a Meeting of the AIChE, Denver, Colorado, August 1962. Cited by Gustafson, R.E., 1969. Kirk--Othmer Encyclopaedia of Chemical Technology. John Wiley, N e w York, 2nd edn., Vol. 18, p. 3. 5 Jeong, K.M. and Kobylinski, T.P., 1983. Organic--mineral interactions in Green River oil shale. A C S Div. Fuel Chem. Prepr., V. 28 (3): 209. Cited by Krishnan et al.,Ref. [3 ] above. 6 Vandegrift, G.F., Winans, R.E., Scott, R.G. and Horwitz, E.P., 1980. Fuel, 59: 627. 7 Vandegrift, G.F., Winans, R.E. and Horwitz, E.P., 1980. Fuel, 59: 634. 8 Riley, K.W. and Saxby, J.D., 1982. Chem. Geol., 37: 265. 9 Saxby, J.D., 1983. The distribution, properties and potential of Toolebuc oil shale. Proceedings of First Australian Workshop on Oil Shale, Lucas Heights, M a y 1983, C S I R O Division of Energy Chemistry, p. 43. 10 Glikson, M., 1983. The organic matter in oil shales; its nature and origin. Proceedings of First Australian Workshop on Oil Shale, Lucas Heights, M a y 1983, C S I R O Division of Energy Chemistry, p. 39. 11 Mamers, H., Yuritta, J.P. and Menz, D.J., 1981. The Siropulper --An explosive alternative for non-wood pulping. Reprinted from Conference on N o n - W o o d Plant Fibre Pulping, Progress Report No. 11, TAPPI Press, Atlanta, p. 261.
168 12 Mamers, H., Watson, A.J. and Grave, N.C., 1976. Appita, 29: 356. 13 Larson, O.A., Schultz, C.W. and Michaels, E.L., 1981. Benefication of Green River oil shale by density methods. ACS Syrup. Ser. 163: 139. 14 Reeves, P.C., 1981. Cited in "Cyclone whips up better shale feed", Chem. Eng., 88 (23): 41. 15 Thomas, R.D., 1969. Fuel, 48: 75. 16 Mandelson, J.J., 1982. Julia Creek project. Department of National Resources and Energy, National Energy Research Development and Demonstration Programme, Final Report -- Shale Oil Retorting Investigation, Reference Nos. 79/9064 and 80]0467.
163
Elsevier Science Publishers B.V., Amsterdam -- Printed in The Netherlands
KEROGEN--MINERAL BONDING AND BENEFICIATION STUDIES WITH A CARBONATE OIL SHALE, USING CARBONIC ACID ATTACK AND A NOVEL EXPLOSIVE DISINTEGRATION TECHNIQUE
KEITH G. McLAREN
CSIRO, Division of Energy Chemistry, Private Mail Bag 7, Sutherland, NSW 2232 (Australia) (Received August 15th, 1984; accepted September 25th, 1984)
ABSTRACT CO2 and water under pressures up to 5.2 MPa and temperatures up to 200°C have been used to attack the mineral matrix of a carbonate oil shale from Julia Creek, Australia. In most experiments the chemical attack was coupled with an explosive depressurisation process (Siropulper) which produced considerable comminution of the shale. Changes in kerogen--mineral bonding and potential for beneficiation were assessed by float--sink separations. No kerogen was liberated, and only small amounts of kerogen-enriched material were freed by these treatments, even where all the carbonate minerals had been dissolved. Carbonate minerals do not appear to play any special role in bonding kerogen in this shale, and these disintegration techniques show no promise for gravity beneficiation processes with it.
INTRODUCTION
Results from various beneficiation studies suggest that carbonate minerals may play an important role in the bonding of kerogen to the mineral matrix of some oil shales. Thomas and Lorenz [1] reported that pretreatment of Colorado shale to remove carbonates was necessary to get good separations of enriched material by a centrifugal method. In liquid--liquid pelletization experiments with Dow-Colony shale [2], the kerogen-enriched pellets were found to retain or concentrate the calcium and magnesium carbonates. Froth-flotation studies with Anvil Points shale [3] showed the calcite and dolomite accompanied the kerogen. Chemical bonding between carbonate minerals and organic matter in oil shales has been postulated by other workers [4--7 ]. This communication presents experiments in which kerogen--mineral bonding in a carbonate off shale was studied using carbonic acid attack and explosive disintegration techniques.
0378-3820/85/$03.30
© 1985 Elsevier Science Publishers B.V.
164 EXPERIMENTAL
Oil shale The oil shale was from the Julia Creek deposits, part of the vast Toolebuc Formation in Queensland, which is considered to be of marine origin. The main minerals are calcite and quartz; the dolomite c o n t e n t is less than 3%. In general, Julia Creek shale is characterized by a high vanadium content (up to 0.5%, partly in the form of porphyrins), and by kerogens with high sulphur (5--8%) and nitrogen (2--3%) contents, and low H/C atomic ratios (around 1.3), indicating aromaticity around 60% [8--9]. The organic matter occurs mainly as bands and lenses of low-reflectance vitrinite-like material, interbedded and closely associated with calcite [10]. Analytical data for Julia Creek oil shales and for the particular sample used in this work, are given in Table 1. TABLE1 Data on Julia Creek oil shale
SiO 2
CaCO3 Mg (total) Pyrite Organic carbon Bitumen a Kerogen content (approx.) Oil yieldb Density (dry)
Typical range of values for raw shales [16 ], wt.% (dry basis)
Data for sample used in this work, wt.% (dry basis)
25--40 30--60 0.2--0.4 1--2 12--16
N.D. 33.2 1.1 (MgCO3) N.D. 13.3 1.2 20.8 74 dms tonne-1 2.26 gem -s
50--90 dm3 tonne-1
aExtractable with mixture benzene: methanol 60:40. bModified Fischer assay.
Siropulper process The Siropulper explosive depressurisation technique was developed by Manners [11--12] for woodpulping, and gives good disintegration effects with short reaction times. It had n o t previously been tried with oil shale. The pilot plant (at CSIRO Division of Chemical and Wood Technology, Clayton, Victoria) has a digester with a m a x i m u m internal diameter of 115 ram, an overall length of 1000 mm and a working volume of 6 dm 3. The digester is heated by injection of steam (1.72 MPa), and pressurized by gas from cylinders. It features fast pressure release via a ball valve which is opened pneumatically in less than 0.1 s, explosively discharging the contents
165 at near sonic velocities through a specially designed nozzle (18 mm i.d., fitted with eight 4.8-mm diameter bars spaced 12.5 mm on centres), against a metal striker plate in a collecting tank which retains all solids and liquor, but permits the escape of gas and steam. In hot runs the charge was 1 kg shale (2380--710/~m) and 1.5 dm 3 water, and the reaction was carried out at 200°C for 10 rain after a heat-up time of 3--5 rain. Operating gas pressures were 13.8 MPa (N2) or 5.2 MPa (CO2). Some Siropulper runs were carried out using CO2 at ambient temperature (16--21°C) with the aim of dissolving as much carbonate mineral as possible. Because of solubility limitations, in these runs 66 g shale and 6 dm 3 water were used. It was n o t possible to stir the reactor, so the digestions were continued for 16--21 h. After discharge from the reactor, all of the insoluble material was recovered by decantation and filtration through a fine filter. Float--sink tests were carried out using carbon tetrachloride--tetrabromoethane mixtures, and 20 g shale in 100 cm a stoppered cylinders. Float fractions were analysed for carbon c o n t e n t after removal of all extractable organic material and mineral carbonates, so that only insoluble kerogen was being assayed. RESULTS AND DISCUSSION
Effects of Siropulper treatment (i) Comminution In the h o t treatments about 54% of the shale was reduced below 710 pm. " F i n e s " (< 150 ~m) were about 15%. In cold runs the corresponding amounts were 27% and 5%.
(ii) Leaching effects Raw shale contained 1.2% of solvent-extractable organic material. In h o t runs 28--35% of this organic material was lost by being rendered soluble or possibly by being volatilized in the discharge process. There was no such loss in ambient temperature runs. Only 13.4% of the mineral carbonates was removed in the 16--21 h runs with CO2 at ambient temperature, due to the lack of stirring. In the 10 min run with CO2 at 200°C, 4.7% of the carbonates was removed. Most of the small calcium sulphate c o n t e n t (1.18% total) was removed in the various runs.
(iii) Separation of kerogen-enriched material The flotation results are summarised in Table 2, where the ratio of percentage recovery of kerogen to weight percentage of shale is shown as an arbitrary "beneficiation f a c t o r " (BF). With control samples BF values were very low (1.16--1.19). Siropulping treatments did n o t liberate any kerogen, and produced only small amounts of moderately enriched material (BF = 2.4--1.65, with kerogen recoveries up to 10.3%). At kerogen recovery levels
166 TABLE 2 Sink--float tests on Julia Creek oil shale given various treatments Sample treatment
Specific gravity of float medium
Kerogen recovery in float, %
Float yield, % w/w
Beneficiation factor
(A)
(S)
(A/B)
2.007 2.060 2.105 2.156
16.7 57.0 64.0 77.3
14.4 48.3 54.6 66.8
1.16 1.19 1.17 1.16
2.007 2.060 2.103 2.193
1.2 3.1 3.7 27.2
0.5 1.7 2.3 20.0
2.40 1.82 1.61 1.36
b 200°C, 10 rain, C O 2 - - 5.2 MPa
2.007 2.060 2.193
3.1 10.3 41.8
1.5 6.0 32.1
2.07 1.72 1.30
c 16--21°C, 16--21 h, CO~ -- 5.2 MPa (13.4% of carbonate dissolved)
2.007 2.060 2.103 2.193
4.2 6.2 8.4 81.0
2.0 3.5 5.1 63.7
2.10 1.77 1.65 1.27
All carbonates removed 1.80 by acid leaching 1.90 2.007 2.105
3.6 21.8 38.7 82.6
2.0 14.4 28.0 70.9
1.80 1.51 1.38 1.17
Nil
Siropulped" a 200°C, 10 min, N 2 - - 13.8 MPa
All initially - 8 +22 mesh (2380--710 urn). o f m o r e practical i n t e r e s t ( 4 2 - - 8 1 % ) BF was 1 . 3 0 - - 1 . 2 7 , m a r g i n a l l y b e t t e r t h a n f o r u n t r e a t e d shale. T h e small i m p r o v e m e n t in b e n e f i c i a t i o n a p p e a r s t o be due t o p h y s i c a l c o m m i n u t i o n r a t h e r t h a n t h e r m a l e f f e c t s , f o r a m b i e n t t e m p e r a t u r e runs gave results similar to t h o s e at 200°C. I n c r e a s i n g t h e pressure f r o m 5.2 MPa (CO2) t o 13.8 MPa (N2) h a d n o discernible effect. T h e S i r o p u l p e r t e c h n i q u e s h o w s n o p r o m i s e as a m e a n s o f i m p r o v i n g g r a v i t y - t y p e b e n e f i c i a t i o n yields w i t h this shale, especially as in its p r e s e n t f o r m , t h e shale has first to be r e d u c e d t o a relatively small size. While strict c o m p a r i s o n s c a n n o t be m a d e , it is i n t e r e s t i n g to c o m p a r e these results w i t h s o m e r e p o r t e d r e c e n t l y f o r h e a v y m e d i u m s e p a r a t i o n s (HMS) w i t h c o a r s e r material. T h u s , L a r s o n ' s d a t a [13] f o r l a b o r a t o r y - s c a l e HMS w i t h G r e e n River shale indicate BF values a r o u n d 1.36 at 65% k e r o g e n r e c o v e r y ( - 3 in + 1 / 4 in shale), a n d 1.24 at 84% r e c o v e r y ( - 3 / 4 in + 1 / 4 in shale). R e e v e s ' large-scale tests [14] w i t h C o l o r a d o shale ( < 1 . 8 in), using t h e D u t c h S t a t e Mines h e a v y m e d i u m c y c l o n e process, indicate BF values o f 2.06 at 65% k e r o g e n r e c o v e r y , a n d 1.36 at 82% k e r o g e n r e c o v e r y .
167
Kerogen--carbonate mineral bonding In the Siropulper runs the addition of carbon dioxide to attack carbonate minerals had no discernible effect on the liberation of kerogen-enriched material, nor did the prolonged carbonic acid attack in which 13.4% of the carbonates was dissolved. Furthermore, parallel tests were run with shale from which all carbonates had been leached, using a small stirred pressure vessel similar to that used by Thomas [15]. BF values were much the same as those with shales given Siropulper treatment. These results indicate that mineral carbonates do n o t play any special role in the bonding of kerogen to the matrix of this Julia Creek shale. ACKNOWLEDGEMENTS
The author wishes to thank Dr H. Mamers and Mr D.J. Menz (CSIRO, Division of Chemical and Wood Technology, Clayton, Victoria) who carried out the Siropulper runs and made me welcome in their laboratory. Thanks are also due to C.S.R. Ltd, who provided a bulk sample of Julia Creek shale, and Mr G.C. Wall, CSIRO, Division of Energy Chemistry, for Fischer Assays.
REFERENCES
1 Thomas, R.D. and Lorenz, P.B., 1970. Use of centrifugal separation to investigate h o w kerogen is bound to the minerals in oil shale. U.S. Bur. Mines, Rep. Invest.,7378. 2 Reisberg, J., 1981. Beneficiation of Green River oil shale by pelletization. A C S Symp. Set., 163: 155. 3 Krishnan, G.N., Farley, E.P. and Murray, R.G., 1983. Benficiation of U.S. oil shales by froth flotation. Sixteenth Oil Shale Symposium Proceedings, Colorado School of Mines Press, Golden, CO, p. 426. 4 Jones, D.G. and Dickert, Jr., J.J., 1962. Compositions and reactions of oil shale of the Green River formation. Papers to a Meeting of the AIChE, Denver, Colorado, August 1962. Cited by Gustafson, R.E., 1969. Kirk--Othmer Encyclopaedia of Chemical Technology. John Wiley, N e w York, 2nd edn., Vol. 18, p. 3. 5 Jeong, K.M. and Kobylinski, T.P., 1983. Organic--mineral interactions in Green River oil shale. A C S Div. Fuel Chem. Prepr., V. 28 (3): 209. Cited by Krishnan et al.,Ref. [3 ] above. 6 Vandegrift, G.F., Winans, R.E., Scott, R.G. and Horwitz, E.P., 1980. Fuel, 59: 627. 7 Vandegrift, G.F., Winans, R.E. and Horwitz, E.P., 1980. Fuel, 59: 634. 8 Riley, K.W. and Saxby, J.D., 1982. Chem. Geol., 37: 265. 9 Saxby, J.D., 1983. The distribution, properties and potential of Toolebuc oil shale. Proceedings of First Australian Workshop on Oil Shale, Lucas Heights, M a y 1983, C S I R O Division of Energy Chemistry, p. 43. 10 Glikson, M., 1983. The organic matter in oil shales; its nature and origin. Proceedings of First Australian Workshop on Oil Shale, Lucas Heights, M a y 1983, C S I R O Division of Energy Chemistry, p. 39. 11 Mamers, H., Yuritta, J.P. and Menz, D.J., 1981. The Siropulper --An explosive alternative for non-wood pulping. Reprinted from Conference on N o n - W o o d Plant Fibre Pulping, Progress Report No. 11, TAPPI Press, Atlanta, p. 261.
168 12 Mamers, H., Watson, A.J. and Grave, N.C., 1976. Appita, 29: 356. 13 Larson, O.A., Schultz, C.W. and Michaels, E.L., 1981. Benefication of Green River oil shale by density methods. ACS Syrup. Ser. 163: 139. 14 Reeves, P.C., 1981. Cited in "Cyclone whips up better shale feed", Chem. Eng., 88 (23): 41. 15 Thomas, R.D., 1969. Fuel, 48: 75. 16 Mandelson, J.J., 1982. Julia Creek project. Department of National Resources and Energy, National Energy Research Development and Demonstration Programme, Final Report -- Shale Oil Retorting Investigation, Reference Nos. 79/9064 and 80]0467.