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Alaska's High-Rank Coals Information Circular 33 1993
me es a ‘ ee » 2s . A = NE le A ae Ee Crm ge of Alaska ALASKA'S HIGH-RANK COALS A summary of high-rank coal resources in Alaska and their potential for mining and development. First Edition 1990 Revised Edition 1993 Department of Natural Resources DIVISION OF GEOLOGICAL & GEOPHYSICAL SURVEYS Fairbanks, Alaska Cover photo: North limb of Wishbone Hill syncline, Matanuska Valley. (See fig. 8, p. 7.) STATE OF ALASKA Walter J. Hickel, Governor DEPARTMENT OF NATURAL RESOURCES Glenn A. Olds, Commissioner DIVISION OF GEOLOGICAL & GEOPHYSICAL SURVEYS Thomas E. Smith, State Geologist Address mail orders to the Fairbanks office. DGGS publications may be inspected at the following locations. Alaska Division of Geological & Geophysical Surveys 794 University Avenue, Suite 200 Fairbanks, Alaska 99709-3645 Department of Natural Resources Public Information Center 3601 C Street, Suite 200 Anchorage, Alaska 99510 This publication, produced and released by the Division of Geological & Geophysical Surveys, and printed in Delta Junction, Alaska, by Dragon Press at a cost of $2.66 per copy. Publication is required by Alaska Statute 41, "to determine the potential of Alaskan land for production of metals, minerals, fuels, and geothermal resources; the location and supplies of groundwater and construction materials; the potential geologic hazards to buildings, roads, bridges, and other installations and structures; and shall conduct such other surveys and investigations as will advance knowledge of the geology of Alaska.” ii FOREWORD Although current coal production is limited to subbituminous coals, Alaska produced high rank coals from the Matanuska field until 1968. Plans are again under way for production from the Matanuska field. Deadfall syncline coal, being in close proximity to the Bering Sea, is another candidate for development and is receiving renewed attention. For example, seam K3 of this field is of high volatile A bituminous rank and has a maximum thickness of 17 feet, with an average ash content of 9 percent and over 10 feet of this seam averages less than 4 percent ash. Other exposures along Kukpowruk, Kokolik, and Utukok rivers are of similar high quality. The low volatile bituminous coal of the Bering River field has been well explored. Some seams of this field have unusually low ash content and could be washed to produce clean coal containing less than 0.5 percent ash for special utilization purpose. Coals of the Alaska Peninsula, near Chignik, have been mined in the past for use in fish canneries. Alaska has extensive high rank coal deposits which await development. P.D. Rao Associate Director Mineral Industry Research Laboratory iii STATE AGENCIES INVOLVED IN COAL EXPLORATION, DEVELOPMENT AND MARKETING * OFFICE OF INTERNATIONAL TRADE (OIT) Frontier Building 3601 C St., 7th Floor Anchorage, Alaska 99503 (907) 562-2728 Robert Poe, Director DEPARTMENT OF NATURAL RESOURCES (DNR) 400 Willoughby Avenue, Sth Floor Juneau, Alaska 99801 (907) 465-2400 Rod Swope, Commissioner Division of Mining (DOM) Frontier Building 3601 C St., Suite 800 P.O. Box 107016 Anchorage, Alaska 99510 (907) 762-2163 Gerald L. Gallagher, Director Division of Geological and Geophysical Surveys (DGGs) 3700 Airport Way Fairbanks, Alaska 99709 (907) 451-2760 Robert B. Forbes, Director and State Geologist DEPARTMENT OF COMMERCE AND ECONOMIC DEVELOPMENT (DCED) State Office Building, 9th Floor P.O. Box D Juneau, Alaska 99811 (907) 465-2500 Larry Merculieff, Commissioner Division of Business Development (DBD) State Office Building, 9th Floor P.O. Box D Juneau, Alaska 99811 (907) 465-2094 James M. Parsons, Director Tom Lawson, Deputy Director UNIVERSITY OF ALASKA Mineral Industry Research Laboratory (MIRL) 210 O’Neill Resources Building Fairbanks, Alaska 99775 (907) 474-7135 or 474-7136 Russell Ostermann, Acting Director P.D. Rao, Associate Director Promotes trade and export of Alaska products, including mineral and fuel resources, to worldwide markets. Chief agency that manages and administers Alaska’s state lands. Chief agency for regulation and management of coal mining on State land in Alaska. Leases coal land and issues coal-prospecting and coal-exploration permits. Administers the Alaska Surface Mining Control and Reclamation Act (ASMCRA), which includes permitting and inspection of coal-mining activity and reclamation of abandoned mines. Chief agency conducting field investigations, exploration, and research relating to Alaska’s coals. Determines the coal resources and development potential of Alaska’s lands. Provides information used to determine state land designations (AAC 85.010) for coal-lease purposes in areas of high to moderate coal- development potential. Serves as liaison with industry, Native corporations, and other state and federal agencies, and lends technical advice in matters pertaining to Alaska’s coal. Serves as repository for information on Alaska’s coal. Publishes a wide range of reports containing results of coal investigations. Promotes economic development in Alaska. Chief advocacy agency in state government for the mining industry. Provides liaison between state government and the private sector. Researches and publishes economic data on Alaska’s mining industry. Conducts applied and basic research on the location, development, and use of Alaska’s coal resources. Specializes in the mineralogical, chemical, and petrographic characterization of Alaska’s coals and their preparation. Publishes reports and general information concerning coal mining and utilization in Alaska. iv CONTENTS Page Introduction 1 Acknowledgments. 2 Matanuska coalfield 5 Bering River coalfield ..........ssosssssssssssnssssssccssossossssssesssesessonesessneccannseansscnnecssnsessnsesennscesnscssssecsunesessocoesvsoesssossvscessossosscssscsens 12 Herendeen Bay coalfield... = 17 Chignik coalfield ..........ssssssssssssssssssseessssesssssesssesssecssssecssssecsssnecssnnccssneccsnsccssuscssusessuscsssnsessnessnsssssscasssessssssssnscssssecanecsanecsaeessnes 21 Western Arctic coalfields.. 25 Outlook for coal development in Alaska.. 32 References... 53 Glossary of terms. 34 FIGURES Figure 1. Pie chart showing Alaska’s coal resources by rank 1 2. Map showing the general distribution of Alaska’s high-rank coal deposits 3 3. Histogram showing estimated measured resources of Alaskan high-rank coals 3 4. Map showing major districts of the Matanuska coalfield, Matanuska Valley, south-central Alaska... 5 5. Generalized stratigraphic section of the upper Chickaloon Formation, western Wishbone Ail district; Matanuska field sscscscsscccecvssvecsscescssssczscasvssusstveseecescecnscessesncnecoscessesavsessscossaccusesaucasecsosensesaneosesses 6 6. Longitudinal cross section of the Wishbone Hill syncline... ae 7. Diagram of coal production in Matanuska field, 1915-1970 7 8. Photograph of highwall face at Evan Jones surface mine, north limb of Wishbone Hill syncline, Matanuska Valley 7 9. Photograph of drilling for coal at the Wishbone Hill project of Union Pacific Resources. 8 10. Photograph of drill core from the Wishbone Hill project of Union Pacific Resources 8 11. Map showing generalized outcrop extent of the Kushtaka Formation of Bering River coalfield showing eastward gradation in coal rank. 12 12. Stratigraphy of the Kushtaka Formation 13 13. Cross section of the Carbon Ridge area 14 14. Photograph of the ‘Queen Vein,’ a 28-foot thick coal seam of the Bering River field 14 15. Photograph showing folding in coal beds in the Carbon Mountain area, Bering River field 15) 16. Photograph of coal core from Bering Development Corporation’s drilling project in the Bering mm nrc ee ee TTL 15 17. Index map of southern Alaska Peninsula showing locations of the Herendeen Bay and Chignik coalfields 17 18. Generalized geologic map of the Herendeen Bay coalfield, Alaska Peninsula. . 18 19. Generalized stratigraphy in the Herendeen Bay coalfield , 20. Detailed correlation sections of Herendeen Bay coalfield 19 21. Photograph of one of the thicker coal seams at Mine Harbor, Herendeen Bay field.. 19 22. Generalized geologic map of the Chignik coalfield, Alaska Peninsula 23. Generalized stratigraphy in the Chignik coalfield. 24. Detailed correlation sections of Chignik coalfield... 25. Photograph of lower coal horizon at Thompson Valley, Chignik field, Alaska Peninsula. a 26. Map showing the distribution of bituminous coal deposits in northern Alaska.........scssseesseesseeseeseesseeese 25 27. Map showing important bituminous coal-bearing areas and structural features of the Western RS EI enna ETA 28. Generalized stratigraphy of the Western Arctic region 29. Geologic map and cross section of the Deadfall syncline, Western Arctic region 30. Typical cross sections in the Kukpowruk River area of the Western Arctic yi Contents — Continued 31. Photograph of 20-ft thick coal seam at Kukpowruk River, Western Arctic region.... 32. Sampling a thick coal bed north of Cape Beaufort, Western Arctic region, 1981 TABLES Table 1. Estimate of identified and hypothetical resources of Alaska’s high-rank coals.. 2. Current high-rank coal development projects in Alaska .. 3. Generalized stratigraphy in the Bering River coalfield. CONVERSION FACTORS To convert to multiply by acres hectares 0.4047 feet meters 0.3048 meters feet 3.281 miles kilometers 1.609 kilometers miles 0.6214 square miles square kilometers 2.590 tons* metric tons 0.9072 Btu/Ib Kceal/Kg 0.5556 *All tonnages reported here are in short tons (2,000 Ib). ALASKA’S HIGH-RANK COALS INTRODUCTION It is estimated that as much as 55 percent of Alaska’s abundant coal resources--approximately 3 trillion tons--is high-rank (bituminous) coal (fig. 1). Bituminous coal deposits are found not only on Alaska’s North Slope, but also in the Matanuska, Bering River, Chignik, and Herendeen Bay coalfields (fig. 2). Measured resources are summarized in figure 3; identified and hypothetical resources are listed in table 1. Significant potential exists for large, yet- undiscovered deposits of high-rank coal. <1% Anthracite Lignite Figure 1. Alaska’s coal resources di- vided by rank. Early studies of Alaska’s high-rank coals were directed at determining suitability for blacksmithing use or for steamship fuel. Investigations now are directed toward developing a market for Alaska coals in Pacific Rim nations, as well as for local heat and power generation (table 2). Bituminous coals formed in Alaska during the Cretaceous Period (65- 140 million years ago) from heat and pressure created by _ structural deformation of coal-bearing rocks. Most bituminous Alaska coals have a low sulfur content (less than 1 percent) and exhibit coking characteristics that range from poor to excellent. Potential coking and metallurgical- grade coals are found in the Chickaloon district, Matanuska coalfield; Western Arctic region, especially at Kukpowruk River; Bering River coalfield; Chignik and Herendeen Bay coalfields, Alaska Peninsula; Lisburne coalfield; and the Lower Yukon basin-Nulato coalfield. More than 7 million tons of bitumi- nous coal has been mined in Alaska, most of it from the Matanuska coal- field before 1968. Some of Alaska’s coal resources (less than 1 percent) are anthracitic coals--semianthracite, anthracite, and meta-anthracite. Deposits of Tertiary age are found in eastern parts of the Matanuska and Bering River coalfields, and Mississippian-age de- posits are found in northern Alaska. High-rank coal has long been known to exist in Mississippian rocks, but mineable resources are small and therefore not discussed here. Table 1. Estimate of identified and hypothetical resources of Alaska’s high- rank coals (in millions of tons). Identified Hypothetical Deadfall syncline 500 5,000 Cape Beaufort 390 1,700 Kukpowruk River 275 1,200 Chignik 230 1,500 Bering River 160 3,500 Herendeen Bay 130 1,500 Wishbone Hill 120 350 Chickaloon 25 100 Anthracite Ridge 4.5 50 TOTALS 1,834.5 14,900 Table 2. Current high-rank coal development projects in Alaska. Company Union Pacific Resources/ Idemitsu Kosan Arctic Slope Regional Corporation Morgan Coal Company Chugach Alaska Corporation Bristol Bay Native Corporation Project and location Wishbone Hill, Matanuska Field Western Arctic Coal Project Kukpowruk River Korea-Alaska Development Corporation Project, Bering River Field Chignik Field, Alaska Peninsula 2 Alaska's High-Rank Coals ACKNOWLEDGMENTS The Alaska Division of Geological & Geophysical Surveys (DGGS) thanks the Office of International Trade for funding, which initiated this study. The information was collected by R.D. Merritt, formerly of |DGGS. Coalfield tables include data compiled by P.D. Rao and published by the University of Alaska Fairbanks, Mineral Industry Research Laboratory (1986). The design and production was by G.M. Laird (DGGS). The agency also wishes to thank the following individuals whose efforts made this brochure possible. We acknowledge technical reviews by John F.M. Sims, Usibelli Coal Mine, Inc., and Gilbert R. Eakins, geologist (retired) DGGS. The report was edited by C.L. Daniels and A.F. Seward (DGGS). Cartography by Nori Bowman and Teresa Imm. Type- setting by Roberta Mann, and paste- up by A-L. Schell. 165° Barrow 155° 145° 135° aRcTIC Lop WESTERN ARCTIC FIELDS (See fig. 26, p. 25) SZ*®eeG \ - Sea g 4 \ Chukchi 5 ARCTI \ » Lisburne SUBPROVINCE \ ' "Field c\ | aig ! West Kobuk East Kobuk % \ z i Kotzebue at Tramway Bar y \8 | ‘ Field 2, \> J Basin e Upper B\ S: YUKON-KOYUKUK Koyukuk \ : PROVINCE Basin \ Soyo a Keyacel Si OyuKU! Nome Bein °° yuror a Nude @ @ Fairbanks \ poe 3 Field © \ \ Y \ . RANGE \ skh e a aL \ ° os MATANUSKA | Cheeneetnuk River FIELD \ ees Kusk kw im, ee es (See fig. 5, p. 8) \ @ 8 A GULF OF ALASKA Bethel ~~ eee US ASS Anchorage PROVINCE \ fe Cordova \ ae ° 0 cP ks af YN Bering Kuskokwim Y , oy ae Bay eward BERING RIVER ° 7 FIELD C (See fig. 11, p. 12) o ae : ‘g> Gulf of Alaska prst? ow ean eo Kodiak ee e RS uh r ow B C Oo so ne ACIFI CEAN ze peste sh cHIGNIK 7 e . FIELD (See fig. 22, p. 21) G2: y® O%5 HERENDEEN BAY Xo on : FIELD (see fig. 17, p. 17) 155° 145° EXPLANATION KNOWN SOURCES OF ALASKA'S HIGH-RANK COALS INDEFINITE SOURCES OF ALASKA'S HIGH-RANK COALS |= areas of higher potential indicated by dark shading; small circles indicate location of coal occurrences. RANKS A= Anthracitic coal B= Bituminous coal 0 150 mi ee 0 250 km - A a fa Bais , » 4 S juneau Angoon District Admiralty District 0 135° Oo Ketchikan 65° 60° 4 < a’ =] is iY / Figure 2. Map showing the general distribution of Alaska’s high-rank coal deposits (modified from Merritt and Hawley, 1986). MILLIONS OF SHORT TONS Figure 3. Estimated measured re- sources of Alaskan high-rank coals. MATANUSKA COALFIELD DESCRIPTION LOCATION The Matanuska coalfield in south- central Alaska is an eastern extension of the Cook Inlet-Susitna coal province and underlies most of the Matanuska Valley (fig. 2). Its western margin is 45 mi northeast of Anchorage. The Matanuska field contains five coal districts (fig. 4). The Wishbone Hill district is located about 10 mi northeast of Palmer; its chief coal- bearing feature is the Wishbone Hill syncline. The Young Creek, Castle Mountain, and Chickaloon districts underlie the central Matanuska Valley. The Chickaloon district is centered around the old mining camp at Chickaloon, about 30 mi northeast of Sites of past mining: Premier Mine Buffalo Mine Evan Jones Mine Eska Mine Castle Mountain Mine Chickaloon Mine NOP WN Hecky Mine 149°00, ee 61°40) Palmer ® ° 5 10 mi HK 0 5 10 km Palmer. The Anthracite Ridge district is situated at the east end of the Matanuska Valley about 12 mi east of Chickaloon. AREA The Wishbone Hill district occu- pies about 20 mi2 between Moose and Granite Creeks. The Chickaloon dis- trict covers a 10-mi2 area on lower Chickaloon River and Coal Creek. The Anthracite Ridge district includes a 20-mi2 area that extends south from Anthracite Ridge to the Matanuska River. CREEK DISTRICT High-volatile bituminous 2 CHICKALOON DISTRICT Medium-and low-volatile bituminous 3 ANTHRACITE RIDGE DISTRICT Semianthracite/anthracite 1) WisHBONE HILL DISTRICT GEOLOGY Tertiary coal deposits of the Matanuska field occur within Paleocene-lower Eocene rocks of the Chickaloon Formation. The upper 1,400 ft of this unit contains several series (or groups) of coal beds within layers of claystone, siltstone, sand- stone, and conglomerate (fig. 5). De- position occurred predominantly in a meandering fluvial to paludal paleo- environment. Stratigraphic structure varies from moderately complex at the west margin of the Matanuska field to complex at its east margin. Beds range in dip from 7° to overturned; typically they dip from 20° to 65°. 148°00 es Coal district Mountainous terrains —--— Fault- showing relative movement; dashed where approximately located ae Coal rank lines Figure 4. Major districts of the Matanuska coalfield, Matanuska Valley, south-central Alaska (modified from Merritt, 1986). 6 GROUP OR AVERAGE SEAM THICKNESS (FT) WISHBONE OR TSADAKA FM Unnamed seam Jonesville Group nin Unnamed seams Premier Group Midway seam a 1 75-12 Eska Gram | 45-60 Burning Bed Group Unnamed Seams Figure 5. Generalized stratigraphic section of the upper Chickaloon Formation, western Wishbone Hill district, Matanuska field (after Hawley and others, 1984). Alaska’s High-Rank Coals The main structural feature of the Wishbone Hill district is the northeast- trending Wishbone Hill syncline, which has moderately dipping limbs and is cut by several transverse faults (fig. 6). The structure of the Chickaloon district is dominantly synclinal, but complicated by faulting and intrusion of dikes and sills. The Anthracite Ridge district also encompasses a synclinal basin that has been sharply folded and faulted and intruded by igneous dikes and sills. Coal rank and structural complexity increase progressively to the east. MINING HISTORY Coal was mined in the Matanuska field from 1914 to 1968 (fig. 7). When the Alaska Railroad was completed to the Matanuska field in 1916, mining expanded to the Moose Creek area of the Wishbone Hill district. Early ex- ploration and development in the Matanuska Valley was carried out by the US. Government; the Navy searched for steaming coal, and the Alaska Engineering Commission sought coal supplies for railroad fuel. Figure 4 locates historical mining operations in the Matanuska field: the Premier Mine, which operated from 1925 to 1971; the Buffalo Mine, 1942- 45; the Evan Jones Mine, 1920-65; the Eska Mine, 1917-46; the Castle Mountain Mine, 1958-60; the Chick- aloon Mine, 1917-22; and Hecky or Coal Creek Mine, 1925-30. Total past production was about 7.5 million tons, mostly from stripping and underground workings of the Evan Jones Mine at Wishbone Hill (fig. 8). Mining ceased in the Matanuska field in 1968 when Cook Inlet natural gas supplanted coal use in the Anchorage area. Minor production at the Premier Mine continued to provide coal for local needs until 1982. Recent exploration and mine-feasibility studies have been completed by Union Pacific Resources (figs. 9 and 10). ACCESS The Matanuska field is favorably located with respect to rail and road links, and hence is not a ‘green-field’ energy development. The Glenn Highway passes along its southern edge, and the western part of the field is served by the Alaska Railroad. No major construction of transportation facilities would be required to resume coal-mining operations in the Matanuska field. COAL RESOURCES Wishbone Hill district Bituminous coal beds to 23 ft thick occur in the upper 1,400 ft of the Chickaloon Formation. Most beds are greater than 3.5 ft thick. Total esti- mated resources (to a depth of 2,000 ft) are: Measured 40 million tons Identified 120 million tons Hypothetical 350 million tons Chickaloon district Bituminous coal beds up to 14 ft thick yield two main deposits: at Chickaloon north of the Matanuska River and at Coal Creek south of the Matanuska River. Total estimated re- sources (to a depth of 2,000 ft) are: Measured 3 million tons Identified 25 million tons Hypothetical 100 million tons Anthracite Ridge district A 20-acre tract in the Purinton Creek area contains an estimated 1 million tons of anthracite and semi- anthracite. Although coal beds are usually less than 5 to 10 ft thick, beds 24 and 34 ft thick have been measured at two exposures. Total estimated re- sources (to a depth of 2,000 ft) are: Measured 1 million tons Identified 4.5 million tons Hypothetical 50 million tons Matanuska Coalfield 7 SOUTHWEST NORTHEAST D Tsadaka Formation Burning Bed Group Premier Group Matanuska Formation D Feet | Meters 2000 Tsadaka Wishbone Formation Eska Groupy Jonesville Group Eska S500 1000 250 o o 1000 250 Premier Fault Northeast Fault Fault —— Contact Figure 6. Longitudinal cross section of the Wishbone Hill syncline (from Germer, 1987). THOUSANDS OF SHORT TONS Figure 7. Coal production in Matanuska field, 1915-1970 (from Merritt and Belowich, 1984). LAND STATUS Land in the Matanuska coalfield is state-owned. Figure 8. Highwall face at Evan Jones surface mine, north limb of Wishbone Hill syncline, Matanuska Valley. (Photo by G.R. Eakins, 1981.) Alaska’s High-Rank Coals Figure 9. Drilling for coal at the Wishbone Hill project of Union Pacific Resources. (Photo by R.D. Merritt, 1983.) Figure 10. Drill core from the Wishbone Hill project of Union Pacific Resources. (Photo by R.D. Merritt, 1983.) Matanuska Coalfield Data WISHBONE HILL COAL QUALITY Rank: hvBb Heating content: Range Proximate analysis (range in %): Moisture 3-9 Volatile matter 32-45 Ultimate analysis (range in %): Carbon 50-70 Hydrogen 45-55 Nitrogen 1.0-1.4 Major-oxide composition of ash (avg. in %): Si 56.81 ALO; 28.94 Fe03 297 Ca 2.36 K,0 1.86 TiO 156 Mg6 1.12 Trace elements in coal ash (avg. in ppm): Antimony 2 Arsenic 8 Beryllium 0S Boron 7 Bromine 2 Cadmium az Cerium 19 Cesium 3 Chlorine 8 Chromium 14 Cobalt 16 Copper 2a Europium 0S Fluorine 230 Gallium 22 Germanium ad lodine 2 Lanthanum 19 Lead 6 Fusibility of ash (°F): Initial deformation Softening temperature (H = W) Hemispherical temperature (H= W) Fluid temperature Free-swelling index: 0-2 Hardgrove grindability index: 47 10,400-13,200 Btu/Ib Matanuska Coalfield 9 COAL PETROLOGY Avg. composition, volume, mineral-matter-free basis, in %: Vitrinite 78.0 Pseudovitrinite 0.1 Gelinite 11 Corpocollinite 0.2 Fixed carbon 38-51 Vitrodetrinite 128 Ash 4-24 Total vitrinite 92.2 Fusinite 0.3 Semifusinite 0.2 Oxygen 10-17 Sclerotinite 0.5 Sulfur 0.2-0.6 Macrinite 0.1 Ash 4-24 Inertodetrinite 12 Total inertinite 23 Cutinite 0.5 SO. 1.11 Sporinite 0.1 P. 0.79 Resinite 3.2 ia. 3} 0.70 Suberinite 0.1 Si 0.18 Liptodetrinite 16 BaO 0.18 Total liptinite SiS MnO 0.02 Undet. 1.40 Mean-maximum vitrinite reflectance (Ro,,,5 %): 0.5-0.6 Lithium 334 Molybdenum 3 Neodymium 4 Nickel 8 Niobium 7 Praseodymium 4 Rubidium 9 Samarium 4 Scandium 19 Selenium 2 Tellurium ql Thorium 6 Tin 3 Uranium 4 Vanadium 90 Yttrium 22 Zine 14 Zirconium 4 2380 2600 2640 2700 Coking potential: Poor to fair strongly coking; possible metallurgical. 10 Alaska’s High-Rank Coals CHICKALOON COAL QUALITY COAL PETROLOGY Rank: mvb-lvb Avg. composition, volume, mineral-matter-free basis, in %: Heating content: Range 11,960-14,400 Btu/Ib Vitrinite 80.5 Pseudovitrinite 05 Proximate analysis (range in %): Gelinite 0.0 Corpocollinite 0.3 Moisture 1-5 Fixed carbon 60-72 Vitrodetrinite 15.8 Volatile matter 14-24 Ash 5-18 Total vitrinite oye Ultimate analysis (range in %): Fusinite 0.3 Semifusinite 0.3 Carbon 65-77 Oxygen 6-10 Sclerotinite 0.2 Hydrogen 4.2-5.2 Sulfur 0.2-0.7 Macrinite 01 Nitrogen 13-1.7 Ash 5-18 Inertodetrinite 0.4 Total inertinite aE} Major-oxide composition of ash (avg. in %): Cutinite 0.0 SiO2 53.92 S03 1.13 Sporinite 0.0 AkO3 29.73 P205 1.46 Resinite 04 Fe203 434 Na20, 0.68 Suberinite 0.5 CaO 2.63 SrO 0.22 Liptodetrinite 0.7 K20 1.72 BaO 0.21 Total liptinite 1.6 TiO2 1,32 MnO 0.04 MgO ioe Undet. 1.08 Mean-maximum vitrinite reflectance (Romax, %): 1.1-2.1 Trace elements in coal ash (avg. in ppm): Antimony 1 Lithium 222 Arsenic 4 Molybdenum 8 Beryllium 0.9 Neodymium 7 Boron 66 Nickel 9 Bromine 4 Niobium ll Cadmium 2 Praseodymium 4 Cerium 36 Rubidium 28 Cesium 4 Samarium = Chlorine 32 Scandium 22 Chromium 18 Selenium 5 Cobalt 6 Tellurium 1 Copper 40 Thorium 10 Europium 0.9 Tin 8 Fluorine 425 Uranium 5 Gallium 18 Vanadium 85 Germanium ae Yttrium 18 Todine 5 Zine 30 Lanthanum 27 Zirconium 80 Lead 14 Fusibility of ash (°F): Initial deformation 2360 Softening temperature (H = W) 2430 Hemispherical temperature (H= W) 2510 Fluid temperature 2560 Free-swelling index: 0-8 Hardgrove grindability index: 72 Coking potential: Noncoking to strongly coking; possible metallurgical. ANTHRACITE RIDGE COAL QUALITY Rank: sa-an Heating content: Range Proximate analysis (range in %): Moisture 3-9 Volatile matter 7-11 Ultimate analysis (range in %): Carbon 66-75 Hydrogen 2.8-5.6 Nitrogen 1.2-1.7 Major-oxide composition of ash (avg. in %): sio 49.26 AlO3 29.95 cio? 475 K,0 153 TiO 153 M 1.54 Trace elements in coal ash (avg. in ppm): Antimony 1 Arsenic 7 Beryllium 1.0 Boron 85 Bromine 52 Cadmium 2 Cerium 35 Cesium 4 Chlorine 66 Chromium 9 Cobalt 10 Copper 22 Evropium 05 Fluorine 361 Gallium 17 Germanium 11 Todine 3 Lanthanum 22 Lead 7 Fusibility of ash (°F): Initial deformation Softening temperature (H = W) Hemispherical temperature (H= W) Fluid temperature Free-swelling index: 0-2 Hardgrove grindability index: -- 10,720-14,000 Btu/Ib Matanuska Coalfield Fixed carbon Ash Oxygen Sulfur Ash SO. P. a0 S BaO MnO Undet. Lithium Molybdenum Neodymium Nickel Niobium Praseodymium Rubidium Samarium Scandium Selenium Tellurium Thorium Tin Uranium Vanadium Yttrium Zine Zirconium 2490 2560 2570 2590 Coking potential: Some coking properties in bituminous coals only. 65-81 6-17 6-15 0.2-0.7 6-17 0.97 3.24 0.71 0.31 0.42 0.02 1.31 BanunnBwbarck#lak COAL PETROLOGY Avg. composition, volume, mineral-matter-free basis, in %: Vitrinite Pseudovitrinite Gelinite Corpocollinite Vitrodetrinite Total vitrinite Fusinite Semifusinite Sclerotinite Macrinite Inertodetrinite Total inertinite Cutinite Sporinite Resinite Suberinite Liptodetrinite Total liptinite Mean-maximum vitrinite reflectance (Ro,,4x5 %): 2.0-5.0 84.5 0.0 0.0 0.2 11.8 96.5 0.2 0.1 0.4 0.0 0.2 0.9 0.1 0.0 0.8 0.4 13 2.6 11 12 BERING RIVER COALFIELD *_ DESCRIPTION __ ee LOCATION AREA The Bering River coalfield is lo- cated in south-central Alaska and con- stitutes the most important resource of the Gulf of Alaska coal province (fig. 11). The field is 12 mi northeast of Katalla, 50 mi east of Cordova, and 200 mi east of Anchorage. The belt of coal-bearing rocks ex- tends 20 mi northeast from the eastern shore of Bering Lake and disappears under ice fields in the Chugach Range. The Bering River coalfield width varies from 2 to 6 mi and covers an estimated area of 80 mi? (fig. 11). GEOLOGY The coalfield is defined by the out- crop of the Kushtaka Formation, a 2,000-ft-thick arkosic Tertiary (Eocene-early Miocene) sequence that also includes feldspathic sandstones, siltstones, shales, and coal beds (fig. 12; table 3). Its geologic structure + 60°30' Gandil a A Medium volatile bituminous coal Mountain Oo < i L 60! . & F 5 A 15 2 3 Low volatile bituminous coal 60°15'-| 33 8 3 a Anthracite/meta-anthracite g|0 8 2 0 5 10 15 km 6\3 ola 144°00' Figure 11. Generalized outcrop extent of the Kushtaka Formation of the Bering River coalfield showing the eastward gradation in coal rank (from Merritt, 1986). Bering River Coalfield 13 Table 3. Generalized stratigraphy in the Bering River coalfield (after Barnes, 1951). Quaternary Age Formation Lithology fresh-water, glacial, marine origin sediments Sedimentation fresh-water, glacial, marine Tertiary or Post-Tertiary diabase, basalt, dikes Tertiary Tokun Formation Kushtaka Formation Stillwater Formation Katalla Formation sandstone, sandy shale, shale arkose, sandstone, sandy shale, shale, coal, coaly shale shale, sandstone, sandy shale conglomerate, sandstone, shale, nodular shale, inter- bedded glauconitic sand marine origin fresh-water partial saline partial fresh-water marine origin Tertiary or Pre-Tertiary graywacke, slate, igneous rock is complex; average dip of beds is 40° (fig. 13). Coals occur in a highly com- FORMATION SECTION THICKNESS LITHOLOGY pressed series of isoclinal, chevron- wa like folds, incorporated into animbri- | = © Maou tor coarse-crained sandstone: cation or pinching-and-swelling sel- Shale clasts . Fine- t dium-grained idstone, vage along one of numerous bedding- upper esate i i plane faults. The beds are thinned by upper middie Siltstone, shale, coal ; i i gS tectonic lensing to form ‘schlieren,’ 3 and thickened at the axes of folds (figs. g : Medium- to coarse-grained sandstone, i 5 z lower middie thick coal 14 and 15). Coal rank increases with intensity of deformation to the east. lower MINING HISTORY Fine-grained sandstone with medium-grained sandstone The Bering River field was dis- covered in 1896. Extensive exploration | = _________ Stillwater and testing of the coals were con- ducted during the early 1900s. Despite the identification of numerous surface and underground prospects, no com- mercial mines have been developed. The total amount of coal produced to date is estimated at only a few thou- sand tons. In recent years, the Chugach Alaska Corporation, in association with the Korea-Alaska Development Corporation, has been studying the Figure 12. Stratigraphy of the Kushtaka Formation (after Smith and Rao, 1987). 14 feasibility of developing a coal mine in A the Bering River field to produce coal Feet for export. Thousands of feet of cor@o ~ drilling have been completed in the last few years (fig. 16). A tentative mine plan proposes a combination f° open-pit and underground mining methods. 200 ACCESS 4 Alaska’s High-Rank Coals 150 100 The Bering River field is about ° 25 mi from tidewater. It would be considered a ‘green-field’ energy . . * . 9 50°% project, since it has no infrastructure ie 9, XL Jquee™ 60" 24 or overland transportation access x er system. Such a system would likely ae consist of a conveyor or aerial tramway to transport coal from the mine to a storage facility at a marine terminal on the southeast tip of Kanak Island, where it would be loaded on ships for export. An access road would connect the mine-site facilities with the road to Cordova. COAL RESOURCES Coal resources are concentrated in four main areas: Carbon Creek, Trout Creek, Clear Creek/Cunningham Ridge, and Carbon Mountain. The Carbon Creek area is the most promising in size and physical condi- tion of beds. At least 20 coal beds ranging from 5 to 10 ft thick have been confirmed. Lenses 30 to 60 ft thick occur locally. Resources are summarized as fol- lows (with overburden depths of 0 to 3,000 ft): Measured 60 million tons Identified 160 million tons Hypothetical 3,500 million tons LAND STATUS Lands in the Bering River coalfield are owned by Chugach Alaska Corpo- ration. Tokun Formation Fault Contact Kushtaka Formation Shale clasts ~ Coal beds if Diamond drill hole 1987). Figure 14. The ‘Queen Vein,’ a 28-foot thick coal seam of the Bering River field. (Photo by R.B. Sanders, 1973.) Bering River Coalfield Figure 15. Folding in coal beds in the Carbon Mountain area, Bering River field. (Photo by R.B. Sanders, 1973.) Figure 16. Coal core from Bering Development Corporation’s drilling project in the Bering River field, 1984. (Photo courtesy of Bering Development Corporation.) 15 16 Bering River Coalfield Data Alaska’s High-Rank Coals COAL QUALITY Rank: Ranges from low-volatile bituminous in the western part of the field to semianthracite and anthracite in the eastern part. Heating content: Range Average Proximate analysis: Moisture Volatile matter Fixed carbon Ash Uitimate analysis: Carbon Hydrogen Nitrogen Oxygen Sulfur Ash 11,000-15,000 Btu/Ib 14,000 Btu/Ib Range (%) 0.01-1.80 2.67-16.15 63.51-85.03 1.14-22.46 68.02-89.14 0.76-4.49 0.81-1.66 1.40-4.17 0.21-4.49 1.14-22.46 Major-oxide composition of ash (avg. in %): SiOz AlO3 Fe203 CaO K20 TiO2 40.03 20.82 14.26 7.02 1.29 1.00 Trace elements in coal ash (avg. in ppm): Barium Beryllium Chromium Cobalt Copper Free-swelling index: 0-2.5 1,850 10.5 246 86 166 Average (%) 0.52 12.45 78.55 8.48 82.14 3.82 1.31 3.00 1.25 8.48 Mgo P205 Na2O MnO Undet. Nickel Strontium Vanadium Zine Zirconium 1.78 1.84 1.00 0.10 10.86 213 4,282 198 677 232 Coking potential: It is questionable whether the low-volatile bituminous coals possess coking properties, but it is expected that a good coke can be produced by blending the low- volatile bituminous coals with other high-volatile bituminous coals. Metallurgical potential: Possible source of high-grade metallurgical coal. COAL PETROLOGY Maceral Composition Because of the high rank of the coals of the Bering River field, maceral analyses are of little benefit (Smith and Rao, 1987). Although some samples retain remnant morphological structures of various macerals, the coals are overall petrologically similar and morphologically homogeneous. Mean-maximum vitrinite reflectance (ROmax, %): 1.63-2.66; locally to 9.46 HERENDEEN BAY COALFIELD = DESCRIPTION 17 LOCATION The Herendeen Bay coalfield is lo- cated clong the shore of the Bering Sea on the northern Alaska Peninsula, between Herendeen Bay and Port Moller, about 350 mi southwest of Kodiak and 100 mi southwest of the Chignik coalfield (fig. 17). AREA The belt of coal-bearing rocks is about 25 mi long and 5 mi wide. The field covers an area of 100 miz (fig. 18). GEOLOGY The high-rank coal deposits of the Herendeen Bay field occur mainly in the Coal Valley Member of the Upper Cretaceous — Chignik Formation (fig. 19), which is over 1,500 ft thick. Typical sections of coal-bearing strata are shown in figure 20, and a seam at Mine Harbor in figure 21. Beds are moderately folded and locally broken by small-scale faults. MINING HISTORY Between 1889 and 1904, the Herendeen Bay field was the site of local coal developments, small-scale mining, and underground exploration. Mine Harbor was the main focus of activity. However, very little commer- cial production occurred. The mining potential of the coal- field has not been thoroughly investi- gated, and it may hold considerable potential for development of small mines. ACCESS The Herendeen Bay field is acces- sible to tidewater, but Herendeen Bay is blocked by ice several months each 161° BERING SEA | ph oso” Hi | Pal Port Moller/ Herendeen | Bay \ y FIELD exig See | a oC V BAe as _ Balboa Bay J (§} Popof Ugna 44} Island Island ( _, y g8_ CHIGNIK FIELD 4 HERENDEEN BAY 158° Port Heiden T 158° Figure 17. Index map of the southern Alaska Peninsula showing the locations of the Herendeen Bay and Chignik coalfields (modified from Merritt and Hawley, 1986). year. The most likely scenario for coal shipment would require the construc- tion of an overland transportation system (road, rail, conveyor, aerial tramway, or slurry pipeline) 15 mi through a low pass to Balboa Bay, on the Pacific side of the Alaska Penin- sula (fig. 17). COAL RESOURCES Coal resources are concentrated in five main areas: Mine Creek/Mine Harbor, Coal Bluff, Coal Valley, Lawrence Valley, and Coal Point. A large number of closely-spaced coal beds up to 7 ft thick have been found within these areas; however, thickness of beds averages 2 to 4 ft. One 200-ft section contains an aggregate 26 ft of coal. Resources are summarized as fol- lows (overburden depth to 2,000 ft): Measured 10 million tons Identified 130 million tons Hypothetical 1,500 million tons LAND STATUS The Herendeen Bay coalfield occupies land owned by the state of Alaska and the Aleut Native Corpora- tion. 18 Alaska’s High-Rank Coals HERENDEEN BAY Coal Point Kee 55°45} — 7~Lawrence 1 ) Valley 55°45 N Derenoi Bay oO 5 mi Paar a ae oO 5 km 161°00 Geology modified from Burk, 1965 a Upper ** Fault-dotted where concealed. Cretaceous D U,, upthrown side; D, downthrown side. Tertiary Anticline-showing axial trace +. . Syncline-showing axial trace 160°30 Chignik Formation Coal Valley Member Bear Lake Formation, Unga Conglomerate Member. e Sample coal locality x Location of geologic section Figure 18. Generalized geologic map of the Herendeen Bay coalfield, Alaska Peninsula (from Merritt and McGee, 1986). Herendeen Bay Coalfield 19 FORMATIONAL NAMES _ [COMPOSITION [Teak rematen |__| ——— Quartzo- feldepathic Figure 19. Generalized stratigraphy in the Herendeen Bay coalfield (modified after Burk, 1965; Moore, 1974; and Mancini and others, 1978). Section 4 Herendeen Bay Ft 0-7 [Coverea) Soe Section } Herendeen Bay — 7 sonmanaay Erosion Ft 7 ES =| Suriace 30: Covered 350 ssod f | Fault 37541 |covered 375 300-| |Coverea Covered _ _ - Figure 21. One of the thicker coal seams at . ; - . Mine Harbor, Herendeen Bay field. Figure 20. Detailed corre orendee ) > igure etailed correlation sections of Herendeen Bay coalfield (from (Photo by R.D. Meritt, 1984.) Merritt and McGee, 1986). 20 Alaska’s High-Rank Coals Herendeen Bay Coalfield Data COAL QUALITY Rank: High volatile bituminous, typically hvBb. Heating content: = Range 8,400-12,900 Btu/Ib Average 11,060 Btu/Ib Proximate analysis: Range (%) Average (%) Moisture 1.80-10.09 4.29 Volatile matter 28.41-48.95 34.13 Fixed carbon 29.88-57.89 48.80 Ash 2.52-33.23 12.78 Ultimate analysis: Carbon 56.71-64.52 59.08 Hydrogen 4.38-5.09 4.64 Nitrogen 0.35-0.90 0.74 Oxygen 18.47-24.10 22.00 Sulfur 0.29-4.68 0.76 Ash 2.52-33.23 12.78 Major-oxide composition of ash (avg. in %): Re. 45.2 MgO ALO; 27.6 P20 Fe203 2.8 Nad Ca 5.4 MnO K,0 0.7 SO3 TiO 2.0 Undet. Trace elements in coal ash (avg. in ppm): Barium 860 Molybdenum Boron 168 Nickel Cadmium iz Scandium Chromium 226 Strontium Cobalt 282 Vanadium Copper 81 Ytterbium Gallium 27 Yttrium Lead 38 Zinc Lithium 88 Zirconium Manganese 269 Trace elements in coal (avg. in ppm): Antimony 0.9 Selenium Arsenic 48 Thorium Fluorine 143 Uranium Mercury 0.05 Fusibility of ash (°F): Initial deformation 2701 Softening temperature 2800+ Fluid temperature 2800+ Free-swelling index: 0-1.5 Hardgrove grindability index: 52 Coking potential: Poor caking and coking properties. 18 0.6 0S 01 1.7 11.6 43 23 154 51 138 250 0.7 1.6 COAL PETROLOGY Avg. composition, volume, mineral-matter-free basis, in %: Vitrinite Pseudovitrinite Gelinite Corpocollinite Vitrodetrinite Total vitrinite Fusinite Semifusinite Sclerotinite Macrinite Inertodetrinite Total inertinite Cutinite Sporinite Resinite Exsudatinite Suberinite Liptodeterinite Total liptinite Mean-maximum vitrinite reflectance (Ro, Range 0.55-0.90 Average 0.65 Locality (See figure 18) wee a PONKSCOCMIADAUEWNE 78.5 0.1 2.7 0.7 8.4 90.4 25 11 0.4 0.6 2.2 68 0.4 0.8 0.7 0.2 0.1 0.6 28 %) max’ Romax (%) 0.66 0.27 0.67 0.62 0.60 0.66 0.59 0.67 0.90 0.69 0.58 0.61 0.60 0.55 21 CHIGNIK COALFIELD . DESCRIPTION Tos LOCATION AREA The Chignik field, about 250 mi lies on the northwest shore of Chignik The belt of coal-bearing rocks is southwest of Kodiak and 100 mi Bay, which indents the south side of about 30 mi long and 1 to 6 mi wide, northeast of the Herendeen Bay field, the Alaska Peninsula (fig. 17). an estimated area of 100 mi (fig. 22). 158945) 158915) i Tertiary 56°30 | — Voleanics __],,03,) Tertiary Volcanics CHIGNIK BAY Pre-Chignik Fm. Rocks Chignik Lagoon Tertiary . 56°15 a Volcanics 5615 oO 5 mi oO 5 km | 158°45 158°15' Geology modified from Burk, 1965 Upper om Chignik Formation ——-- Fault-dashed where inferred Cretaceous Coal Valley Member 3 e Sampled coal locality +: = Syncline-showing axial trace 7 x Location of geologic section Figure 22. Generalized geologic map of the Chignik coalfield, Alaska Peninsula (from Merritt and McGee, 1986). 22 GEOLOGY Coal deposits of the Chignik field lie within the Coal Valley member of the Upper Cretaceous Chignik For- mation (fig. 23). This unit of cyclic nearshore marine and nonmarine sedimentation ranges in thickness to 1,500 ft and is composed of sandstone, pebble-cobble conglomerate, siltstone, shale, and numerous coal beds (fig. 24). Strata are moderately folded and locally faulted. Dips vary from 20° to 35°. matt FOrmation UPPER CRETACEOUS HIATUS LOWER CRETACEOUS Staniukovich Fm. UPPER JURASSIC Naknek Formation Figure 23. Generalized stratigraphy in the Chignik coalfield. Kec =Coal Valley Member, Chignik Formation (after Vorobik and others, 1981). MINING HISTORY Coal was first discovered on the banks of the Chignik River in 1885. In 1893, the Alaska Mining and Development Company opened a small coal mine on Anchorage Bay near Chignik Lagoon, and the Alaska Packer’s Association opened the Chig- nik River Mine to produce coal for the local fish cannery and for steamers. The Chignik River Mine operated un- til 1911. Several other small under- ground mines and prospects were opened in the early 1900s at Thomp- son Valley (fig. 25), Whaler’s Creek, Alaska’s High-Rank Coals ~ ‘Section 7 Thompson Canyon Meters 30. Section 6 10- Whalers Section § Ft Creek Chigrik 05 gemma eresion Ft “Wine surface 1754 25 hannel 50 100-4 |: 100 1254 R 125 1504 feacord 150 Lower Coal Measure Upper Coal Measure 2289) feed | 250-4 2754 300 Section 8 | Ft Hook Bay | 325-4 25 3504 FE 50: 3754 75 400 Figure 24. Detailed correlation sections of Chignik coalfield (from Merritt and McGee, 1986). and Hook Bay, but they accounted for very little production. There has been no mining activity since. Although some exploration has been conducted in recent years, the mineability of most areas has not been thoroughly investigated. During 1980- 81, Resource Associates of Alaska, Inc. (a subsidiary of NERCO Minerals Co.), explored several areas owned by the Bristol Bay Native Corporation in the Chignik field and outlined small potential mining blocks. ACCESS Although the Chignik field is ac- cessible to tidewater, Chignik Bay it- self has no suitable harbor facilities for large vessels. It would be necessary to construct coal shipment facilities, in- cluding overland transportation system (access road and conveyor or aerial tramway) through a low pass to the head of Kuiukta Bay, about 5 mi south of the coal belt. COAL RESOURCES Coal resources are concentrated in four main areas: Chignik River, Whaler’s Creek, Thompson Valley, and Hook Bay. Coal beds range in thickness to 7 ft, but are typically about 3 ft thick. Resources are summarized as fol- lows (depths of 0 to 2,000 ft): Measured 10 million tons Identified 230 million tons Hypothetical 1,500 million tons LAND STATUS The Chignik coalfield lies within lands owned by the Bristol Bay Native Corporation. Chignik Coalfield 23 Figure 25. Lower coal horizon at Thompson Valley, Chignik field, Alaska Peninsula. This seam previously supported a small mine. (Photo by R.D. Merritt, 1984.) 24 Alaska’s High-Rank Coals Chignik Coalfield Data COAL QUALITY Rank: High volatile bituminous, typically hvBb. Heating content: Range 8,800-13,750 Btu/Ib Average 11,800 Btu/Ib Proximate analysis: Range (%) Average (%) Moisture 1.09-6.97 4.40 Volatile matter 25.54-40.61 36.33 Fixed carbon 37.86-57.08 47.66 Ash 4.15-30.56 11.61 Ultimate analysis: Carbon 56.59-68.45S 64.15 Hydrogen 4.12-5.10 4.71 Nitrogen 0.68-0.78 0.71 Oxygen 14.14-24.65 17.46 Sulfur 0.28-4.79 1.36 Ash 4.15-30.56 11.61 Major-oxide composition of ash (avg. in %): Si 42.0 MgO AlO3 29.3 P,0 Fe,03 5.6 Nad CaO 4.0 MnO K,0 0.5 SO3 TiO, 1.7 Undet. Trace elements in coal ash (avg. in ppm): Barium 367 Molybdenum Boron 400 Nickel Cadmium 1 Scandium Chromium SS Strontium Cobalt 13 Vanadium Copper B Ytterbium Gallium 30 ‘Yttrium Lead 32 Zinc Lithium 192 Zirconium Manganese 455 Trace elements in coal (avg. in ppm): Antimony 0.3 Selenium Arsenic 3.7 Thorium Fluorine 65 Uranium Mercury 0.09 Fusibility of ash (°F): Initial deformation 2794 Softening temperature 2800+ Fluid temperature 2800+ Free-swelling index: 0-1.5 Hardgrove grindability index: 46 Coking potential: Poor caking and coking properties. 2.2 0.5 0.2 0.1 5.9 8.0 27 150 173 S7- 83 217 0.4 4.0 11 COAL PETROLOGY Avg. composition, volume, mineral-matter-free basis, in %: Vitrinite Gelinite Corpocollinite Vitrodetrinite Total vitrinite Fusinite Semifusinite Sclerotinite Macrinite Inertodetrinite Total inertinite Cutinite Sporinite Resinite Exsudatinite Suberinite Alginite Liptodeterinite Total liptinite 8.3 2.0 0.4 10.9 91.6 2.0 1.0 0.4 05 18 5.7 0.3 08 0.6 0.1 0.1 0.1 0.7 2.7 Mean-maximum vitrinite reflectance (Ro,,4,5 %): Range 0.S7-1.76 Average 0.73 Locality (See figure 22) 15 16 Ly 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 Bad 35: 36 37 38 39 40 Romax (%) 0.57 0.62 0.62 0.67 0.64 0.82 1.01 0.95 0.79 1.76 0.58 0.62 0.60 0.60 0.66 0.58 0.68 0.69 0.70 0.71 0.78 0.60 0.66 0.65 0.65 0.70 WESTERN ARCTIC COALFIELDS « DESCRIPTION 25 LOCATION The Western Arctic region forms a part of the Foothills subprovince in northern Alaska (fig. 26). Three spe- cific areas that show the highest potential for near-term development of bituminous coal deposits are Cape Beaufort (or Liz-A syncline), Deadfall syncline, and Kukpowruk River, west of Howard syncline (fig. 27). The Liz- A syncline is just inland from Cape Beaufort on the Chukchi Sea coast. The Deadfall syncline is 6 mi east of the Chukchi Sea, and the Kukpowruk River area is about 14 mi east of the Chukchi Sea and 25 mi upstream from the mouth of the Kukpowruk River. AREA The Cape Beaufort area covers about 30 mi2, The Deadfall syncline encompasses less than 100 mi?, and that portion of the Kukpowruk River area under consideration here--the western end of the Howard syncline-- has an area of 20 to 30 mi?. Within these broad areas, several specific mining blocks or units can be defined. GEOLOGY The geology of the Western Arctic region is dominated by a series of east- west-trending synclines and anticlines. The synclines contain bituminous coal beds in the Corwin Formation of the Cretaceous-age Nanushuk Group (figs. 28 and 29). In the Western Arctic region, the Corwin Formation varies in thickness from 7,000 to 10,000 ft. The type locality of the Corwin Formation is at Corwin Bluffs (fig. 26), 35 mi west of Cape Beaufort, where 80 or more coal beds over 1 ft thick are exposed. Interbedded with coal seams are sandstones, claystones, siltstones, and carbonaceous shales that formed in a prograding deltaic Pt. Barrow WESTERN ARCTIC REGION Cape Lisburne © 20 40 60.80 100 MILES ae Bituminous coal ST) KILOMETERS Figure 26. Distribution of bituminous coal deposits in northern Alaska (modified from Knutson, 1981). 164° 163° | _L KUKPOWRUK CHUKCHI SEA Howard Syncline | | DEADFALL Deadfall — SYNCLINE 4. S¥Mcling AREA CAPE Kukpowruk Syncline | Ss | Beaufort 4 Syncline \ | L69° wr Known coal a bearing areas Sly BEAUFORT AREA | Cape Beaufort Liz-A abs . 2 ¥ Syncline e 2 0 10 mi b Coke Basin Oo 10 km \ a re T 164° 163° Figure 27. Important bituminous coal-bearing areas and structural features of the Wester Arctic region (modified from Chapman and Sable, 1960). 26 system in swampy coastal lowlands. The strata are flat-lying to gently dipping (10° to 20°) and their structure is relatively simple (figs. 29 and 30). Rank of the coals increases with the complexity in structure from north to south in the foothills of the Brooks Range. MINING HISTORY The coals of the Western Arctic region were first reported by the Beechey expedition of 1826-27. In the late 1800s and early 1900s, coal from the Corwin Bluffs and Cape Beaufort areas was used to fuel whaling ships. A.J. Collier conducted the first geo- logic reconnaissance of coastal de- posits south of Cape Beaufort in 1904. Morgan Coal Company first ex- plored the coking coal deposit on the Kukpowruk River in 1954, by driving a 70-ft tunnel in the 20-ft-thick bed. The company still holds a U.S. Bureau of Mines preference-right coal lease on 5,000 acres in that area. Union Car- bide investigated the Kukpowruk River coking coal deposit from 1961 to 1963, Prince Creek (7?) Formation COLVILLE GP. CRETACEOUS NANUSHUK GP. Fortress Mountain Formation Figure 28. Generalized stratigraphy of the Westem Arctic _ region (modified from Ahlbrandt and others, 1979). Alaska’s High-Rank Coals Qai| Surficial deposits kn Corwin Fm.; 3 nonmarine 2 Corwin Fm.; transitional marine FB cet rowru Tae CHUKCHI SEA CROSS SECTION Figure 29. Geologic map and cross section of the Deadfall syncline, Western Arctic region (modified from Callahan and Eakins, 1987). SECTION ORIENTATION N 16° E Topography 300 m west of section Kukpowruk 7 River ,~ 75 cm coal seam Horizontal scale 610 cm coal seam oO 100 200 feet Oo 40 80 meters Figure 30. Typical cross sections in the Kukpowruk River area of the Western Arctic (from Knutson, 1981). and Kaiser Engineers performed de- tailed mining and economic evaluations from 1970 to 1977. From 1981 to 1986, the State of Alaska and the North Slope Borough conducted extensive exploration and predevelop- ment site investigations of coal de- posits at Cape Beaufort and in the Deadfall syncline area. ACCESS Access to the Deadfall syncline de- posits was thoroughly studied by the Western Arctic Coal Development Project (Arctic Slope Consulting Engineers, 1986). A 5.4-mi haul road would connect the mine site with a port facility and berthing area for barge traffic. A 2,800-ft lead-in chan- nel would be dredged to an operating depth of 13 ft. Coal would be stored at the barge loading facility for domestic shipment during the ice-free season. Coal for foreign export would be transported to a separate ice-free port facility with a large storage capacity and a harbor for berthing and loading of seagoing carriers. Large-volume shipments from either the Cape Beaufort or Kukpowruk River areas would probably follow a similar plan, unless a long-distance rail line were completed to the Western Arctic region. COAL RESOURCES The North Slope, including the National Petroleum Reserve of Alaska (NPRA) and bordering areas to the east and west of it, holds as much as 4 trillion tons of coal. The Western Arctic region west of NPRA may contain up to 1 trillion tons of coal. Approximately 60 percent of North Slope coal is estimated to be of bitu- minous rank. Ten percent or more of the stratigraphic section from some wells consists of coal. Between 150 and 200 coal beds, 60 percent of which are over 3.5 ft thick, have been corre- lated in the Corwin Formation of the Western Arctic Coalfields 27 Figure 31. Twenty-foot thick coal seam at Kukpowruk River, Western Arctic re- gion. (Photo by G.R. Eakins, 1982.) Western Arctic. The thickest identi- fied outcropping seam in the region is at Kukpowruk River (fig. 31). At Cape Beaufort, coal beds range in thickness to 9 ft in outcrops (fig. 32) and to 17 ft in drill holes; at Deadfall syncline, coal beds range in thickness from 4.5 to 13 ft. At a minimum, the Western Arctic region contains 125 million tons of strippable coal resources amenable to modern mechanized mining; further exploration will delineate other strip- pable resources. Plentiful additional resources can be developed by under- ground mining methods. Domestic uses of Western Arctic coal are heat and power generation for villages in northwest Alaska and power produc- tion for other large-scale mining such as the Red Dog zinc mine north of Kotzebue. 28 Coal resources at Cape Beaufort, Deadfall syncline, and Kukpowruk River are listed below in millions of tons (overburden depths from 0 to 3,000 ft): Cape Deadfall Kukpowruk Beaufort syncline River Measured 45 60 20 Identified 390 500 27S Hypothetical 1,700 5,000 1,200 LAND STATUS Lands in the Western Arctic coal- fields region are owned by Arctic Slope Regional Corporation, and leased by the Morgan Coal Company (U.S. Bureau of Mines preference- right lease to 5,000 acres in the Kukpowruk River area). Alaska’s High-Rank Coals Figure 32. Sampling a thick coal bed north of Cape Beaufort, Western Arctic re- gion, 1981. (Photo courtesy of P.D. Rao, University of Alaska MIRL.) Western Arctic Coalfields 29 Western Arctic Coalfields Data CAPE BEAUFORT COAL QUALITY COAL PETROLOGY Rank hvAb-hvCb Avg. composition, volume, mineral-matter-free basis, in %: Heating content: Range 9,100-12,700 Btu/Ib Vitrinite 62.2 Average 12,300 Btu/Ib ieee ne Phlobaphinite 0.4 Proximate analysis (range in %, mean in parentheses): Pseudophlobaphinite 1.0 Sporinite 1.2 Moisture 25-7 Fixed carbon 37-55 Resinite 0.8 (4.5) (46.8) Volatile matter 22-33 Ash 8-27 Cutinite 01 (29.7) (16.0) Alginite 0.0 Exsudatinite 01 Ultimate analysis (range in %, mean in parentheses): Thick cutinite 01 Suberinite 0.0 Carbon 46-71 Oxygen 13-25 Other liptinite 0.0 (58.3) (19.1) Hydrogen 35-5 Sulfur 0.2-0.4 Fusinite 08 (4.5) (0.3) Semifusinite 14.3 Nitrogen 0.7-1.5 Ash 8-27 Macrinite 1.7 (1.1) (16.7) Globular macrinite 13 Inertodetrinite 5.3 Major-oxide composition of ash (avg. in %): Sclerotinite 0.0 SiO2 49.7 MgO 2.7 Mean-maximum vitrinite AlkO3 25:1 S03 0.6 reflectance (Romax, %): 0.70 Fe203 32 P205 0.3 CaO 6.2 MnO 0.1 TiO2 11 Undet. 7S Trace elements in coal ash (avg. in ppm): Boron 440 Nickel 40 Chromium SS Silver 35, Cobalt 40 Tin 295 Copper 40 Vanadium 130 Gallium 30 Zinc 110 Lead 5S Zirconium 500 Molybdenum s Trace elements in raw coals (avg. in ppm): Boron 7S Nickel 8 Chromium 45: Silver 1 Cobalt 8 Tin 35 Copper 2 Vanadium 30 Gallium 6 Zinc 2s Lead 10 Zirconium 100 Molybdenum 1 Fusibility of ash (reducing temperature, : F): Initial deformation 2320 Softening temperature 2410 Fluid temperature 2520 Free-swelling index: 0-6 Hardgrove grindability index: 58 Coking potential: Increased with depth; coal from 200-ft shows pronounced coking characteristics. 30 Alaska’s High-Rank Coals DEADFALL SYNCLINE COAL QUALITY COAL PETROLOGY Rank hvAb-hvCb Avg. composition, volume, mineral-matter-free basis, in %: Heating content: Range 10,900-13,200 Btu/Ib Vitrinite 58.1 Pseudovitrinite 10.7 Average 12,900 Btu/Ib Gelinite 09 Phlobaphinite 0.1 Proximate analysis (range in %, mean in parentheses): Pseudophlobaphinite 11 Sporinite 17 Moisture 25-8 Fixed carbon 35-56 Resinite 1.0 (4.6) (53.9) Volatile matter 22-36 Ash 5.5-22 Cutinite 0.2 (33.9) (7.6) Alginite 0.0 Exsudatinite 0.0 Ultimate analysis (range in %, mean in parentheses): Thick cutinite 0.3 Suberinite 0.0 Carbon 451-65 Oxygen 17-27 Other liptinite 0.0 (59.4) (23.3) Hydrogen 3.7-5.1 Sulfur 0.2-0.3, Fusinite 2.0 (4.6) (0.2) Semifusinite 16.4 Nitrogen 0.8-1.4 Ash 55-22 Macrinite 24 (1.1) (11.4) Globular macrinite 0.3 Inertodetrinite 48 Major-oxide composition of ash (avg, in %): Sclerotinite 0.0 SiO. 30.9 MgO 6.7 Mean-maximum vitrinite Abd, 29.2 SO. pty reflectance (ROj,ay5 %): 0.70 Fe,03 48 P. 08 cad 17.5 Mad 0.0 TiO, 0.7 Undet. 0.5 Trace elements in coal ash (avg. in ppm): Boron 300 Nickel 25 Chromium 50 Silver 2 Cobalt 30 Tin 180 Copper 35 Vanadium 95 Gallium 30 Zine 100 Lead 50 Zirconium 220 Molybdenum a Trace elements in raw coals (avg. in ppm): Boron 5S Nickel 7] Chromium 12 Silver 1 Cobalt 8 Tin 25 Copper 10 Vanadium 20 Gallium > Zine 18 Lead 10 Zirconium 80 Molybdenum i Fusibility of ash (reducing temperature, °F): Initial deformation 2093 Softening temperature 2143 Fluid temperature 2189 Free-swelling index: 0-6 Hardgrove grindability index: 56 Coking potential: Similar to Cape Beaufort coals. Western Arctic Coalfields ll KUKPOWRUK RIVER COAL QUALITY COAL PETROLOGY Rank = hvAb-hvCb Avg. composition, volume, mineral-matter-free basis, in %: Heating content: Range 11,900-14,100 Btu/Ib Vitrinite 60.9 Pseudovitrinite 16.3 Average 13,800 Btu/Ib Gelinite 17 Phlobaphinite 0.3 Proximate analysis (range in %, mean in parentheses): Pseudophlobaphinite 1.0 Sporinite 19 Moisture 0.8-10 Fixed carbon 52-60 Resinite 0.7 (2.8) (58.5) Volatile matter 31-40 Ash 2.5-15 Cutinite 0.4 (35.2) (3.5) Alginite 0.1 Exsudatinite 0.0 Ultimate analysis (range in %, mean in parentheses): Thick cutinite 0.3 Suberinite 0.1 Carbon 57-77 Oxygen 12-18 Other liptinite 0.0 (70.0) (14.5) Hydrogen 45-5.6 Sulfur 0.2-0.5 Fusinite 0.6 (5.1) (0.3) Semifusinite 114 Nitrogen 1.0-1.6 Ash 2.5-15 Macrinite 11 (1.3) (8.8) Globular macrinite 0.3 Inertodetrinite 2.9 Major-oxide composition of ash (avg. in %): Sclerotinite 0.0 Si S15 MgO 3.0 Mean-maximum vitrinite AbO3 285 SO. 05 reflectance (Ro, %): 0.73 Fe,03 48 iE 0.6 a Ca 35 Mad 0.1 TiO, 1.0 Undet. 65 Trace elements in coal ash (avg. in ppm): Boron - Nickel 80 Chromium 40 Silver - Cobalt 35 Tin - Copper 150 Vanadium 65 Gallium 50 Zinc - Lead 150 Zirconium 190 Molybdenum - Trace elements in raw coals (avg. in ppm): Boron - Nickel 7 Chromium 4 Silver - Cobalt 4 Tin - Copper 12 Vanadium 9 Gallium 4 Zinc - Lead 14 Zirconium 19 Molybdenum - Fusibility of ash (reducing temperature, r F): Initial deformation 2040 Softening temperature 2110 Fluid temperature 2390 Free-swelling index: 0-6 Hardgrove grindability index: -- Coking potential: Significant coking, properties; generally soft-coking. 32 Alaska’s High-Rank Coals OUTLOOK FOR COAL DEVELOPMENT IN ALASKA As the chief energy resource of the world today, where escalating energy needs sap rapidly declining petroleum resources, coal will play an increasing part in the world energy supply. Coal is the primary source of fuel for electrical-power generation in the United States. Alaska’s total coal resources are estimated at between 5.5 and 6.0 tril- lion tons, over half of which are of bituminous rank. The total energy equivalent (in Btu) of all the coal in Alaska exceeds by several orders of magnitude that of all known oil re- serves in the State. The energy equivalent of Alaska’s bituminous coal resources alone is estimated to be more than 1,000 Prudhoe Bays (original recoverable reserves of about 10 billion barrels). Because of its vast coal resources, Alaska promises to become an important coal-mining and export center for the next decade and well into the next century. The potential for coal development in Alaska is un- limited, and Alaska’s strategic position on the northern Pacific Rim places it in the center of expanding trade routes. Alaska is, in fact, closer to Far East markets than Australia, Canada, or South Africa. The low sulfur content of Alaska’s coal (less than 0.5 percent) is a chief attraction for Pacific Rim industrial buyers. The environmental signifi- cance of low-sulfur coal will increase dramatically in the future; environ- mental problems encountered in min- ing, preparation, and use of high-sulfur coal can be avoided with low-sulfur Alaska coal. The sulfur content of Alaska coals, on average, is about half that of the lowest-sulfur coals of the contiguous U.S. Alaska’s coals are uniquely low in the acid-producing, pyritic form of sulfur that causes acid-mine drainage in other U.S. coal-producing regions, and lower mean annual temperatures and local relative aridity act to reduce oxidation effects on Alaska’s coals when exposed to the environment. Alaska coals produce low sulfur- oxide (SOx) emissions. Most Alaska coals meet the USEPA emission standards (1.2 lb SO7/MM Btu) for direct combustion. Because nitrogen content is also low, the low combined emission of SOx and NOx gases during combustion make Alaska’s coals among the most environmentally safe in the world. Alaska’s high-rank coals also. possess good _ash-fusion characteristics and low moisture and metallic trace-element content. Coal mining has taken place in Alaska for 130 yr. If this long history of coal development proves one thing, it is that coal mining can exist in har- mony with the unique Alaska environment. The Usibelli Coal Mine near Healy (in interior Alaska) pro- vides an example--from its longstand- ing commitment to land-restoration programs--that coal mining can be conducted in Alaska with both eco- nomic success and environmental re- straint. As coal mining activities increase in the state, Alaska has the opportunity to serve as a model for mining efficiency and prudent land- restoration practices in Arctic and Subarctic regions. REFERENCES 33 Ahlbrandt, T.S., Huffman, A.C., Jr., Fox, J.E., and Pasternak, Ira, 1979, Depositional framework and reservoir-quality studies of selected Nanushuk Group out- crops, North Slope, Alaska, in Ahlbrandt, T.S., ed., Preliminary geologic, petrologic, and paleon- tologic results of the study of Nanushuk Group rocks, North Slope, Alaska: U.S. Geological Survey Circular 794, p. 14-31. Arctic Slope Consulting Engineers, 1986, Western Arctic coal de- velopment project--village end use technology assessment; report pre- pared for the State Department of Community and Regional Affairs and Alaska Native Foundation, various paginations. Barnes, F.F., 1951, A review of the geology and coal resources of the Bering River field, Alaska: U.S. Geological Survey Circular 146, 11 p. Burk, C.A., 1965, Geology of the Alaska Peninsula--island are and continental margin: Geological Society of America Memoir 99, 250 p., scales 1:1,000,000 and 1:250,000, 3 sheets. Callahan, J.E., and Eakins, G.R., 1987, Coal investigations in the Deadfall Syncline, Western Arctic Alaska, in Rao, P.D., ed., Focus on Alaska's coal '86, Proceedings of the conference held at Anchor- age, Alaska, October 27-30, 1986: University of Alaska Min- eral Industry Research Laboratory Report 72, p. 1-5. Callahan, J.E., Rao, P.D., and Walsh, D.E., 1992, Deadfall Syncline coal: quality and re- serves: University of Alaska Fairbanks, Mineral Industry Re- search Laboratory Report No. 93, 119 p. Chapman, R.M., and Sable, E.G., 1960, Geology of the Utukok- Corwin region, northwestern Alaska--exploration of Naval Petroleum Reserve No. 4 and ad- jacent area, northern Alaska, 1944-53, pt. 3, areal geology: U.S. Geological Survey Profes- sional Paper 303-C, p. 47-167. Germer, D.E., 1987, Geology, mine plan, and potential utilization of coal from the Wishbone Hill dis- trict, Matanuska field, Alaska, in Rao, P.D., ed., Focus on Alaska's coal ~ 86, Proceedings of the conference held at Anchorage, Alaska, October 27-30, 1986: University of Alaska Mineral In- dustry Research _ Laboratory Report 72, p. 229-237. Hawley, C.C., Cox, Terry, and Germer, D.E., 1984, Matanuska coal field, in Clardy, B.I., and others, eds., Guide to the bedrock and glacial geology of the Glenn Highway, Anchorage to the Matanuska Glacier and _ the Matanuska coal-mining district: Alaska Geological Society Guide- book, p. 45-54. Knutson, H.A., 1981, Geologic and economic evaluation of bitumi- nous coal, Kukpowruk River re- gion, Northern coal field, Alaska, in Rao, P.D., and Wolff, E.N., eds., Focus on Alaska's coal ~ 80, Proceedings of the conference held at the University of Alaska, Fairbanks, October 21-23, 1980: University of Alaska Mineral In- dustry Research _— Laboratory Report 50, p. 62-78. Mancini, E.A., Deeter, T.M., and Wingate, F.H., 1978, Upper Cretaceous arc-trench gap sedi- mentation on the Alaska Peninsula: Geology, v. 6, no. 7, p. 437-439. Merritt, R.D., 1986, Paleoenvi- ronmental and tectonic controls in major coal basins of Alaska, in Lyons, P.C., and Rice, C.L., eds., Paleoenvironmental and tectonic controls in coal-forming basins in the United States: Geo- logical Society of America Special Paper 210, p. 173-200. Merritt, R.D., and Belowich, M.A., 1984, Coal geology and resources of the Matanuska Valley, Alaska: Alaska Division of Geological and Geophysical Surveys Report of Investigations 84-24, 64 p., scale 1:100,000, 3 sheets. Merritt, R.D., and Hawley, C.C., 1986, Map of Alaska's coal resources: Alaska Division of Geological and Geophysical Sur- veys Special Report 37, scale 1:2,500,000, 1 sheet. Merritt, R.D., and McGee, D.L., 1986, Depositional environments and resource potential of Creta- ceous coal-bearing strata at Chignik and Herendeen Bay, Alaska Peninsula: Sedimentary Geology, v. 49, p. 21-49. Moore, J.C., 1974, The ancient con- tinental margin of Alaska, in Burk, C.A., and Drake, C.L., eds., The geology of continental margins: New York, Springer- Verlag, p. 811-815. Rao, P.D., 1986, Characterization and evaluation of washability of Alaskan coals: Fifty selected seams from various coal fields: University of Alaska Fairbanks, Mineral Industry Research Labo- ratory Report No. 75, 184 p. Rao, P.D., and Smith, J.E., 1983, Petrology of Cretaceous coals from northern Alaska: University of Alaska Fairbanks, Mineral In- dustry Research _—_ Laboratory Report No. 64, 14 p. Smith, J.E., and Rao, P.D., 1987, Geology and coal resources of the Bering River coal field, in Rao, P.D., ed., Focus on Alaska's coal "86, Proceedings of the confer- ence held at Anchorage, Alaska, October 27-30, 1986: University of Alaska Mineral Industry Re- search Laboratory Report 72, p. 266-299. Vorobik, J.L., Farnstrom, H.E., Cantrell, C.L., Jaworski, M.J., and Beeson, D.C., 1981, Explo- ration and evaluation of the coal potential of Bristol Bay Native Corporation lands in the Chignik area, Alaska: Anchorage, Re- source Associates of Alaska, Inc., unpublished industry report, 5 v. 34 GLOSSARY OF TERMS __ Ash Ash is determined during the proximate analysis, but also forms an integral part of the ultimate analysis. (See Ultimate analysis.) Ash content The ash content of a coal is the percentage of incombustible material in coal determined under standardized conditions by burning a sample and measuring the ash. (See Proximate analysis.) Carbon Carbon is determined by catalytic burning in oxygen and the subsequent measurement of the amount of carbon dioxide formed. Total organic carbon is equal to the total carbon content less the carbonate carbon. Total carbon in a sample is greater than the fixed carbon content. (See Ultimate analysis.) Coking and metallurgical potential Coking and metallurgical potentials refer to the degree to which coals swell, fuse, and run together to produce a strong coke substance under certain specified conditions. Coking or caking coals are the most important of the bituminous coals because of their suitability for the production of coke for metallurgical uses. Coking coals are typically low-ash, low-sulfur, and low- to medium-volatile bituminous rank. Fixed carbon content Fixed carbon is the solid combustible matter of coal remaining after the removal of moisture, volatile matter, and ash. It is determined by difference and is expressed as a percentage. (See Proximate analysis.) Fluid temperature The point indicated by the spreading out of the completely melted ash cone into a flat layer. (See Fusibility of ash.) Free-swelling index (FSI) FSI is a measurement obtained by the rapid heating of a coal sample in a non- restraining crucible. It ranges on a scale of 0 to 9, where noncaking and nonswelling coals are 0 on the scale. FSI gives an indication of the caking characteristics of a given coal. Fusibility of ash (F°) Ash-fusibility temperatures vary with the character of coals, particularly the ash content, and is less for low-rank coals. Among the types performed are either a 3-point or 4-point (reducing atmosphere only) ash fusibility or an 8-point (reducing and oxidizing atmospheres) ash fusibility. The melting temperature and deformational changes of an ash cone are measured at various stages. In the 3-point test, temperatures are measured at the point of initial deformation, softening point, and fluid stage. In the 4-point test, an additional measurement is taken at the hemispherical stage, as follows: Point of initial deformation The tip of the ash cone begins to deform. Softening point The point where the ash cone height is equal to one-half its width. Hemispherical stage The point where the ash cone height is equal to its width. Fluid temperature The point indicated by the spreading out of the completely melted ash cone into a flat layer. Hardgrove grindability index (HGI) HGI is a measurement that peaks in the bituminous ranks and is less for lignites and anthracites. Intermediate-rank coals are softer and easier to grind, whereas lower and higher rank coals are more difficult to grind and hence have lower grindability indices. The grindability index is calculated by measuring the quantity of -200 mesh fine coal produced at different moisture levels; that is, at two or three temperatures. The relative ease of pulverization is compared to a standard coal having an HGI of 100. Glossary—Continued 35 Heating content or heating value Heating content refers to the amount of heat obtainable from coal expressed in British thermal units (Btu) per pound. It is determined by the use of an adiabatic bomb calorimeter, which measures the temperature rise after combustion of a coal sample in an oxygen bomb. Hemispherical stage The point where the ash cone height is equal to its width. (See Fusibility of ash.) Hydrogen Hydrogen is determined by catalytic burning in oxygen and the subsequent measurement of the water formed and absorbed by a desiccant. (See Ultimate analysis.) Major-oxide composition of ash Major oxides include Si02, A1203, Fe203, Ti02, Ca0, Mg0, Na20, K20, P205, and S03. These compounds typically compose over 99 percent of coal ash. Moisture content Moisture content includes surface moisture that can be removed by natural drying, and inherent moisture that is contained structurally in the coal substance. Surficial water on coal is free or adherent. Inherent moisture is held physically by vapor pressure or other phenomena. The total moisture content also includes chemically bound water. The equilibrium or bed moisture (for classification by rank) is the inherent moisture-holding capacity of a given coal (in situ) measured at 30°C with a 97 percent relative humidity atmosphere. (See Proximate analysis.) Nitrogen Nitrogen is determined typically by a chemical digestion with the contained nitrogen converted to ammonia by the Kjeldahl-Gunning method. (See Ultimate analysis.) Oxygen Oxygen is estimated by difference; total carbon, hydrogen, sulfur, nitrogen, and ash are subtracted from 100 percent. (See Ultimate analysis.) Point of initial deformation The tip of the ash cone begins to deform. (See Fusibility of ash.) Proximate analysis A proximate analysis of coal includes determinations of the moisture, volatile matter, ash, and fixed carbon (by difference) content by prescribed methods. A complete proximate analysis is reported on as-received, moisture-free, and moisture- and ash-free bases and totals 100 percent. Sometimes, analyses are reported on an equilibrium-bed-moisture basis as well. Unless otherwise stated, analyses are assumed to be on an as-received basis. Rank Rank is the basis of coal classification in the natural series from lignite to anthracite and refers to the degree of metamorphism of coal. Higher rank indicates greater metamorphism. Bituminous coals and anthracites are considered to be high-rank; subbituminous coals and lignites, low-rank. Classes of high-rank coals are: ASTM* Rank abbreviation (in decreasing order) ma meta-anthracite an anthracite sa semianthracite lvb low volatile bituminous mvb medium volatile bituminous hvAb high volatile A bituminous hvBb high volatile B bituminous hvCb high volatile C bituminous * American Society for Testing and Materials. Softening point The point where the ash cone height is equal to one-half its width. (See Fusibility of ash.) 36 Alaska’s High-Rank Coals Sulfur Total sulfur is composed of pyritic (or sulfide), organic, and sulfate forms. Pyritic sulfur is combined with iron in the minerals pyrite and marcasite. Pyritic sulfur is usually the most abundant form in coals and is chiefly responsible for acid mine drainage. Organic sulfur, typically the most abundant form in Alaskan coals, is bonded to the carbon structure. Sulfates form mainly by weathering, into calcium and iron varieties. Three methods used for sulfur determinations are Eschka, high-temperature combustion, and bomb-washing. (See Ultimate analysis.) Trace elements in coal and coal ash Trace element analysis is important for environmental concerns attendant to coal mining and use. The most important trace elements are arsenic, beryllium, boron, cadmium, chromium, cobalt, copper, fluorine, gallium, germanium, indium, lanthanum, lead, mercury, molybdenum, nickel, selenium, thallium, titanium, uranium, vanadium, yttrium, and zinc. Trace-element analysis is performed by atomic absorption, spark-source mass spectrophotometry, X-ray fluorescence, and neutron activation. Ultimate analysis An ultimate analysis of coal determines the contents of the elements carbon, hydrogen, sulfur, nitrogen, oxygen (by difference), and ash. These quantities always total 100 percent. Vitrinite reflectance Vitrinite reflectance is a measurement of the extent to which light is reflected from the surface of a polished coal sample. The measurements are made on the vitrinitic maceral components of the coal substance and are used in the determination of rank and coking characteristics of coal. Maximum reflectances are measured in oil for at least 100 vitrinite particles. Volatile matter content Volatile matter includes substances in coal other than moisture that are given off as gas and vapor during combustion. (See Proximate analysis.) ALASKA'S