5 cop ?>o STATE OF ILLINOIS DEPARTMENT OF REGISTRATION AND EDUCATION DIVISION OF THE STATE GEOLOGICAL SURVEY M. M. LEIGHTON. Chief Cooperative Mining Series BULLETIN 30 GOAL LOSSES IN ILLINOIS BY C. A. ALLEN ILLINOIS MINING INVESTIGATIONS Prepared by the U. S. Bureau of Mines, with the collaboration of the Illinois Geological Survey and the Engineering Experiment Station of the University of Illinois PRINTED BY AUTHORITY OF THE STATE OF ILLINOIS URBANA, ILLINOIS 1925 The Forty-seventh General Assembly of the State of Illinois, with a view of conserving the lives of the mine workers and the mineral resources of the State, authorized an investigation of the coal resources and mining practices of Illinois by the Department of Mining Engi- neering of the University of Illinois and the State Geological Survey Division in cooperation with the United States Bureau of Mines. A cooperative agreement was approved by the Secretary of the Interior and by representatives of the State of Illinois. The direction of this investigation is vested in the Director of the United States Bureau of Mines, the Chief of the State Geological Survey Division, and the Director, Engineering Experiment Station, University of Illinois, who jointly determined the methods to be employed in the conduct of the work and exercise general editorial supervision over the publication of the results, but each party to the agreement directs the work of its agents in carrying on the investiga- tion thus mutually agreed on. The reports of the investigation are issued in the form of bulle- tins, either by the State Geological Survey Division, the Engineering Experiment Station, University of Illinois, or the United States Bureau of Mines. For copies of the bulletins issued by the State Geological Survey Division, address State Geological Survey Division, Urbana, Illinois ; for those issued by the Engineering Station, address Engineering Station, University of Illinois, Urbana, Illinois; and for those issued by the U. S. Bureau of Mines, address Director, U. S. Bureau of Mines, Washington, D. C. (See list at end of book.) ILLINOIS STATE GEOLOGIC^ SURVEY HUH? 3 3051 00006 3895 STATE OF ILLINOIS DEPARTMENT OF REGISTRATION AND EDUCATION DIVISION OF THE STATE GEOLOGICAL SURVEY M. M. LEIGHTON, Chief Cooperative Mining Series BULLETIN 30 COAL LOSSES IN ILLINOIS BY C. A. ALLEN ILLINOIS MINING INVESTIGATIONS Prepared by the U. S. Bureau of Mines, with the collaboration of the Illinois Geological Survey and the Engineering Experiment Station of the University of Illinois IMJINTKI) 15V A1TIIOKIIY OF THE STATE OK ILLINOIS DRBANA, ILLINOIS 11)25 STATE OF ILLINOIS DEPARTMENT OF REGISTRATION AND EDUCATION DIVISION OF THE STATE GEOLOGICAL SURVEY M. M. LEIGHTON, Chief Committee of the Board of Natural Resources and Conservation A. M. Sheltox. Chairman Director of Registration and Education Kendric C. Babcock Representing the President of the Uni- versity of Illinois Edson S. Bastin Geologist Schnepp & Barnes, Printers Springfield, III. 1925 32714—2500 PREFACE In the course of the inquiry conducted by the Bureau of Mines, Depart- ment of the Interior, for the United States Coal Commission, into losses in- curred in mining bituminous coal in the eastern part of the United States, a study was made of the principal coal-mining districts of Illinois by the late C. A. Allen. Coal losses in the Illinois field have received unfavorable comment from mining engineers for at least a decade, and the present period of depression is serving to awaken the interest of the more progressive operators in the problem. It is believed that the presentation of the detailed data obtained by Mr. Allen, not involving mine labor and surface subsidence problems, will be of value to those concerned with the coal industry. The chief merit of the report lies in the fact that it is the result of a comprehensive and systematic, though rapid, survey of the more important coal mining districts of the State by an especially competent and impartial observer. The coal-mine operators of Illinois cordially cooperated in supplying data requested, assisted in preparing records and estimates, and courteously facilitated examination of mines and records. Advice and assistance were also cordially given Mr. Allen in his studies by the various officials of the State mining, geological, and educational branches. The work was conducted through C. E. Lesher of the Engineering divi- sion of the Commission, and his assistant, W. M. Drake, Jr., and was under the supervision of H. Foster Bain, Director of the U. S. Bureau of Mines, and George S. Rice, chief mining engineer of the Bureau of Mines, and during his absence in Europe, of J. W. Paul, chief of coal-mining investigations of the Bureau. M. M. LEIGHTON, Chief, Illinois Geological Survey. CONTENTS PAGE General summary 7 Coal losses in the Northern Illinois coal field 7 Introduction 7 Losses in overlying coal 9 Coal losses in the Peoria and Fulton county fields 9 Introduction 9 Losses of coal 10 Avoidable losses 11 Coal losses in the Central and Belleville districts 12 Introduction 12 Description of coal seam 12 Character of roof and floor 13 Method of mining 14 Calculation of coal losses 15 Actual figures on extraction 15 Belleville field 15 Central Illinois field 15 Avoidable losses 16 Coal losses in the Springfield district 18 Introduction 18 Coal reserves 18 Beds being worked 18 Nature of roof and floor 19 Method of mining 19 Surface value of land 20 Calculation of losses 20 Avoidable losses 24 Actual extraction 21 Conclusion 22 Coal losses in the Southern Illinois field 23 Introduction 23 Character of roof and floor 23 Method of mining 24 Calculation of coal losses 25 Actual extraction 26 Conditions in Jackson County 27 Average coal losses 28 Avoidable loss 29 Coal losses in Saline County 29 Introduction 29 Characteristics of the seam 29 Dimensions of working places 29 Losses of coal 30 Avoidable loss 30 Loss in overlying seam 31 Coal losses in the Danville district 31 Introduction 31 Method of mining 33 Losses of coal 34 Avoidable loss 34 GO ILLUSTRATIONS FIGURE PAGE 1. Section of mine workings in Greene County, showing coal lost by caved roof due to thin pillars 13 2. Section of mine workings in St. Clair County, showing pillars not extracted 16 3. Coal lost by protection of surface improvements. Section of mine workings in Randolph County 17 4. Section of mine workings in Sangamon County, showing pillars not extracted 22 5. Section of mine workings in Jackson County, showing pillars not extracted 27 6. Section of mine workings in Saline County, showing pillars not extracted and coal lost because of irregular workings and due to displacement faults 30 7. Section of mine workings in Vermilion County, showing coal lost because of irregular spacing and direction of rooms 33 TABLES PAGE 1. Coal production of mines in northern Illinois 7 2. Summary of coal losses in northern Illinois 8 3. Summary of coal losses in Peoria-Fulton county fields 11 4. Coal production of the Belleville and Central fields 12 5. Summary of coal losses in the Belleville and Central fields 17 6. Summary of coal losses in the Springfield district 21 7. Summary of coal losses in southern Illinois 28 8. Summary of coal losses in Saline County 31 9. Summary of coal losses in the Danville district 34 (-•) Digitized by the Internet Archive in 2012 with funding from University of Illinois Urbana-Champaign http://archive.org/details/coallossesinilli30alle GOAL LOSSES IN ILLINOIS By C. A. Allen GENERAL SUMMARY Eleven fields in twenty-seven counties are discussed in this report, and represent nearly the whole of the coal output of Illinois, which amounts to between 60 and 88 million tons annually. In 1921 the out- put was almost 70 million tons. Twenty mines were examined and data were procured from 131 mines, accounting for half of the coal mined. Omitting the Northern Illinois field, in which the longwall system of mining is employed, and where the extraction is 95 per cent, the losses in the other fields are much the same, and vary between 43 and 53 per cent, and average 4!.). 7 per cent. This means that, in the mining of 69,785,000 tons, as in 1921, an amount almost equal to this total, namely 67,045,000 tons, was lost. Pillars account for most of this loss, the average being 39 per cent ; but the investigation showed that 32 per cent of this loss is avoidable. Therefore, instead of the extraction being 50 per cent, it should be 82 per cent. In south- ern Illinois there is a rather large loss of roof coal — namely, 7 per cent; while in Peoria and Fulton counties there is a heavy loss of 15 per cent due to coal being left under water-bearing strata and wet and tender roof. COAL LOSSES IN THE NORTHERN ILLINOIS COAT. FIELD Introduction This report covers that part of northern Illinois where mining is carried on by the longwall method, and includes the following: Table 1. — Coal production of mines in northern Illinois County Mines Tons in 1921 La Salle l 2 384,813 556,671 229,907 202,926 Bureau Marshall Grundy Total . . . 16 1,374,317 ' One trip was made underground in this field, and five operators were interviewed. (7) 8 ILLINOIS COAL LOSSES In addition to the longwall mines which are working No. 2 bed, or the so-called "Third Vein", there is one room-and-pillar mine in No. 5 bed. This mine produces about 170,0$Q tons per year, and re- covers approximately 50 per cent of the coal. To include this with the longwall mines would tend only to confuse, and as it has not suf- ficient tonnage to be reported alone, it would seem better to neglect this mine altogether. In the longwall mines, the only effort made was to determine if any appreciable amount of coal was left under buildings, railroads, or streams ; and after studying this factor, and discussing the matter with three companies, it was found that the coal left thereunder amounts to only a fraction of one per cent. The only other loss possible is in the coal thrown back with the impurities. The seam is about 31/, feet thick, and there are occasion- ally sulphur bands through it, but they occur with no regularity. Also, occasionally the roof coal sticks to the overlying rock. George S. Rice, chief mining engineer for the Bureau of Mines, Department of the Interior, states that careful figures kept over a period of five years showed that 95 per cent of the coal was recovered at one mine; and the late H. H. Stoek of the University of Illinois stated that at another mine the loss from coal thrown back with impurities amounted to 7 per cent. Inasmuch as figures from some other longwall districts have shown a loss of only 4 per cent, it is assumed that the loss in this field is approximately 5 per cent. Table 2. — 8um,?nary of coal losses in northern Illinois Reason for loss Coal left as roof and bottom coal Coal lost in room, entry, and panel pillars Coal lost in oil or gas-well pillars Coal lost under buildings, railroads and boundaries Coal lost in handling and preparation, underground and surface Coal lost due to rolls, thin or dirty areas, or streams Total loss, per cent Percentage of market- able coal lost in area worked Avoidable Total loss loss Fraction of 1 None None Fraction of 1 5 None ILLINOIS COAL LOSSES Losses in Overlying Coal Inasmuch as the lower seam being worked is only Sy 2 feet thick, and is 80 feet below No. 5 bed, the writer would not expect the No. 5 bed to be seriously affected. At one mine, where No. 5 is being worked, it is reported that the roof is cracked a little, but otherwise it gives them no trouble, and the recovery of the coal is not influenced by the work underneath. COAL LOSSES IN THE PEORIA AND FULTON COUNTY FIELDS Introduction This district comprises the counties of Peoria, which has 11 ship- ping mines with a production of 1,102,002 tons in 1921; Fulton, with 28 mines, producing 1,471,137 tons; and Tazewell, with 7 mines, pro- ducing 691,359 tons. The total production of the district in 1921 was 3,264,498 tons. This district comprises part of District IV of the Illinois Coal Mining Investigations, 1 and in University of Illinois Bulletin 100 2 , the following description is given : "In District IV the No. 5 coal is mined. The average thickness of this coal is 4 feet 8 inches, according to data taken at 240 mines and given in the Thirty-first Annual Coal Report of Illinois. The No. 5 bed outcrops in Peoria, Fulton, and Knox counties, but is found at greater depths toward the east. "The roof is of black sheety shale varying in thickness from a few inches to 35 feet, and containing occasionally "nigger-heads" of pyrite. In many mines there is, in places, a layer of pyrite 2 or 3 inches thick between the coal and the shale. Where this layer is present, the shale is protected from the air and stays up; where it is not present, the shale falls badly, and some- times caves to a height of 35 feet. A limestone occurs above the shale in most mines, though in a few places a fine grained micaceous sandstone is found. In some cases the shale is absent, and the cap-rock becomes the roof. "A great many clay veins extend through the coal and the roof shale; there are also small faults, slips, and rolls, and places where the coal has been eroded and the space has been filled with drift. It is difficult, therefore, to calculate the total tonnage and to project any plan of operation. In many places the coal adheres to the roof and separates from it with difficulty. In one mine about an inch of coal is left to protect the roof shale from the air. In most mines the floor consists of a dark gray clay which heaves badly when wet." The coal hed in the area covered by this report is from 1 to 5 feet thick, averaging about 1 feet 1 inches. The principal impurity consists of clay veins, which are very irregular both in size and distri- 1 Cady, G. H., Coal resources of District IV (Peoria-Springfleld) : 111. Coal Mining Investigations Bull. 26, 1921. 2 Young, C. M., Percentage of extraction of bituminous coal with special reference to Illinois conditions: Engineering Experiment Station Hull. 100, p. 36, 1917. 10 ILLINOIS COAL LOSSES bution. Two mines were examined in the district, and data were secured from mining engineers of 3 other mines. The method of min- ing is room-and-pillar, and the workings are usually laid out in panels. Rooms are driven 30 to 35 feet on center, and are from 22 to 30 feet wide. Barrier pillars, 30 to 35 feet wide, are left along the main and cross entries. Losses of Coal Coal is not left to support valuable surface as in the Springfield district of Illinois. Some of it is good farming land, but most of the country is rough and hilly. The only place pillars are left is along railroads and streams. In some parts of the field there are water-bearing formations lying above the coal, so that when the roof is cracked a large quantity of water comes into the mine. Just how this water occurs is not known, but it apparently does not affect much of the area being mined. No attempt is made to recover any pillars either under water-bearing strata or elsewhere. In addition to the coal left in the pillars in the regular work, considerable areas are left where the roof is very tender and wet. Theoretically, the area of the bed lost is from 24 to 35 per cent, but the superintendent of one of the mines visited reported that he had made a careful estimate, and found that they were getting only between 45 and 50 per cent, which would mean a loss of between 55 and 50 per cent. The chief engineer of another company stated that in 1921 he planimetered a map of the workings, and checked it against the tonnage hoisted, and found they had saved only about 40 per cent of the area worked over. From figures on the same mine for a number of years past the coal saved amounted to slightly less than 37 per cent. Of the GO per cent lost in 1921, about 10 per cent was lost in areas abandoned owing to a wet and tender roof. If these figures had not been secured, the writer would have placed the extraction at well over 50 per cent, but at the mine where they had carefully estimated between 45 and 50 per cent recovery this was believed to be a very good average of the district, so the figure 47 per cent has been accepted. In this field some solid coal is left under streams, and at the mines examined the coal so left amounted to approximately 3 per cent. In- asmuch as the railroad ran along the stream, the same coal serves to support it. The depth of the cover is not great, ranging from a few feet up to about 150 feet, so that any caving of the roof would be readily transmitted to the surface. The coal lost in handling and preparation is probably not as high as in the Springfield district, be- cause the clay veins are less frequent in most mines, and consequently less coal is wasted in throwing out the clay. ILLINOIS COAL LOSSES 11 On the basis of present information the writer would therefore put the loss as follows : Cause of loss In room, entry, and panel pillars Under streams and tender roof In handling and preparation Per cent 35 15 3 Total loss 53 AVOIDABLE LOSSES The coal lost under streams and railroads and that lost in handling and preparation are unavoidable. Of the coal left as pillars, unquestion- ably some is necessary on account of the water conditions overhead. However, the pillars which are now being left are not sufficient to hold the roof up for any great length of time. Some of the operators claim that a sandstone not far above the coal will prevent any surface cracks, which may be the case over part of the field, and of course where this is so, the condition would be changed by a systematic pillar drawing, because the sandstone would have to break. From the writer's observations, taking into consideration the fact that certain parts of the field have no trouble with water, and a high percentage of the coal could be extracted, it is believed that ii would be reasonable to assume that 75 per cent could be saved in the entire field, which would be 28 per cent more than they are saving at the present time — that is, the avoidable loss is 28 per cent. Table 3. — Summary of coal losses in PeortOrFulton county fields Reason for loss Percentage of total market- able coal lost in area worked Total loss None 35 None Included in above and last item 3 15 Avoidable loss Coal left as roof and bottom coal ... Coal lost in room, entry, and panel pillars. . . Coal lost in oil or gas-well pillars Coal lost under buildings, railroads and boundaries . 28 Coal lost in handling and preparation, under- ground and surface Coal lost due to rolls, thin or dirty areas, and streams" Total loss, per cent 53 28 • Includes coal left under wet and tender roof. 12 ILLINOIS COAL LOSSES COAL LOSSES IN THE CENTRAL AND BELLEVILLE DISTRICTS Introduction The Central and Belleville districts have been combined in this report as all the general conditions are similar in both ; but separate summaries have been made for each district as there is a difference in the percentage of coal extracted. The Belleville field includes what is frequently known as the Centralia field. Some details of produc- tion are given in the following table : Table 4. — Goal production of the Belleville and Central fields Belleville district Central district County Mines Tons, 1921 County Mines Tons, 1921 St. Clair Randolph Clinton Marion Perry (part) . . . Madison. . 55 10 5 3 9 20 6,281,000 1,894,000 1,165,000 842,000 822,000 4,216,000 Macoupin Montgomery Christian Sangamon (southern part) 17 9 11 4 7,516,000 322,000 3,216,000 1,845,000 Four trips were made underground in the two fields, and definite data were secured on 47 mines producing a total of 14,000,000 tons annually. Description of Coal Seam The coal being mined in these fields comes from the No. 6 bed of the Illinois Geological Survey, and in general, the conditions are similar to the No. 6 bed where it had previously been studied in other districts. The thickness of the seam varies from 4^2 to 9 feet, and probably averages 7^4 Ie et. It is a little thicker in the western part of the Belleville field than it is in the eastern part, and apparently attains its greatest average thickness in Macoupin and Christian coun- ties. The only persistent impurity in the bed is the "blue band", which occurs about 18 inches from the floor. The other impurities contained are mother coal and sulphur bands. The latter occur to a greater extent in the northern part of the Central field than in the Belleville field. The thickness of cover ranges from 16 to 232 feet in St. Clair County, from 45 to 330 feet in Randolph County, from 318 to 410 feet in Clinton County, from 600 to 714 feet in Marion County, and from ILLINOIS COAL LOSSES 13 86 to 287 feet in Madison County— all in the Belleville field. In the Central Illinois field, the coal in Macoupin County has a cover of 268 to 380 feet ; in Montgomery County, 380 to 640 feet ; in Christian County, 360 to 735 feet; and in Sangamon County, from 270 to 328 feet. These are the depths of the working shafts, and due to the generally flat surface of the country, give the approximate thickness of cover. Character of Roof and Floor The roof and floor of No. 6 bed in these districts are, generally speaking, the same as in southern Illinois — that is, there is the usual WMII 1 Virgin Coal L— J Coal thatwill be extracted in parr or in whole Coal Lost Fig. 1. Section of mine workings in Greene County showing coal lost by caved roof due to thin pillars. cap-rock of limestone, lying from a few inches to 30 feet above the coal, and between this limestone and the top of the coal there are bands of material grading from a soft clay to a hard "slate". Wher- ever the limestone lies within a few inches of the coal it makes a good roof, but wherever it is high above the coal, and the material between is soft, there is a very bad roof (fig. 1). Sometimes in one mine, an entry will have these extremes of roof within 2,000 feet. Gener- 14 ILLINOIS COAL LOSSES ally the roof is better in the Belleville field, which means that over more of that area the cap-rock comes close to the coal. Because Madison County has a good roof over much of the area it has been included in the Belleville field. Some roof coal is left up in the Central field, on account of the greater area of tender roof and the tendency of the bed to attain a thicker average. The floor is fire clay, varying in thickness, with a harder stratum of rock below it. Method of Mining Room-and-pillar methods of mining are used exclusively, with the exception of one longwall mine in Christian County, which is in the No. 2 bed, and has not been considered. In the southern part of the Belleville field there are more mines using straight room-and- pillar system than there are mines using the panel system ; but the op- posite is the case in the Central district. The widths of rooms and pillars vary considerably, and there is apparently no relation between the thickness of cover and the dimensions of the workings, except where the cover is very shallow. In the Belleville field one mine with a 150-foot cover and a good roof has 30-foot rooms on 60-foot cent- ers ; the room-necks, crosscuts, and room entries are all 21 feet wide. At another mine close by where the roof is bad the entries are narrowed, but the dimensions of the rooms are not changed, and reliance is placed upon the timber to hold up the bad roof. Another mine in the Belleville district has 30-foot rooms on 54-foot centers, with wide entries and crosscuts. The cover is 307 feet. Another mine with a cover of 380 feet has 40-foot rooms on 80-foot centers. Where the roof is bad the entries but not the rooms are narrowed. Another mine with 220 feet of cover has 35-foot rooms on 70-foot centers; the entries are from 14 to 21 feet wide, and room-necks and crosscuts are 21 feet wide. Nearly all the rooms are approxi- mately 250 feet in length. At one mine in the southern part of the Central Illinois field, rooms 280 feet long are driven 40 feet wide on 80-foot centers. At several other mines near the southern part, rooms are 30 feet wide on 60-foot centers ; the room-necks and entry crosscuts are all 21 feet wide; also entries are 21 feet wide. The room crosscuts are 30 feet wide. The cover is 309 to 342 feet. At one mine in the northern part of this district, rooms are 26 feet wide on 45-foot centers. The depth of cover is about 250 feet. At another mine rooms are 24 feet wide on 40- foot centers, with room-necks 12 feet wide. The entries are also narrow, the cover being 352 feet. At one mine in the northeastern part of the Central field, rooms are ILLINOIS COAL LOSSES 15 30 feet wide on 55-foot centers ; the cover is 450 feet, but room- necks and entries are narrowed to 10 or 12 feet. In nearly all mines where the panel system is used the barrier pillars are about 70 feet wide, and the fire pillars between the ends of the rooms are 10 to 20 feet wide. Calculation of Coal Losses Despite the fact that the same formation occurs over the entire area, there is a great variation in the immediate roof conditions, and considerable time was spent trying to determine how much of the area was affected by the roof conditions. The State mine inspectors fur- nished considerable information, also some mine superintendents and surveyors were met who were familiar with many different mines. A number of calculations were made, taking the actual dimensions of the working places as a basis, and showing a loss in the pillars of from 37 to 45 per cent in the Belleville field, and from 40 to 48 per cent in the Central Illinois field. In the panel work, the barrier pillars amount to from 5 to 10 per cent of the total loss ; and in the straight room-and-pillar work they amount to less than 2 per cent. In top coal the loss is negligible in the Belleville field, but in the Cen- tral field a number of mines leave roof coal in a certain number of the rooms. After much inquiry, it is believed that the figure of 1J/2 per cent represents the average over the entire Central field. ACTUAL FIGURES ON EXTRACTION I'.KI LEVILLE FIELD Four coal-mining engineers in this district report that their ex- traction is 54 per cent, 00 to (>5 per cent, 52 to 55 per cent, and 50 per cent, respectively. The writer examined a large number of maps in the Court House at Belleville, and found that the last mentioned company leaves a great deal of pillar coal, and its extraction could not average 50 per cent if the surveying were accurately done. How- ever, they were mostly small mines. Taking into account the relatively high percentage of unusually good roof in the Belleville field, the writer's estimation is that extrac- tion is almost 55 per cent. CENTRAL ILLINOIS FIELD Some of the figures of recovery from No. coal in the Central field covering the southern part of Sangamon County were given in the report on the coal losses in the Springfield District. The following figures were given by engineers for different companies: (1) 50 per cent; (2) 7 mines in Sangamon County including mines in No. 5 and 16 ILLINOIS COAL LOSSES 6 beds average 48.12 per cent; six mines in Christian County oper- ated by the same company average 49.94 per cent; (3) in northern Macoupin County, 51 y 2 and 52 per cent, and in Montgomery County, 43 per cent; (4) at Divernon in northern Macoupin County, 47 per cent, and at Mt. Olive in southern Macoupin County, 48.6 per cent ; (5) mines near Gillespie, 50 per cent, except in one mine where top coal is left owing to bad roof, and where the extraction is 54 per cent. Taking everything into consideration, the writer estimates that the extraction is 50 per cent, based on the assumption that no attempt is being made to recover barrier pillars on the retreat. J Coal fhatwill be extracted in part or in whole. Fig. 2. Section of mine workings in St. Clair County showing pillars not extracted. AVOIDABLE LOSSES The principal reason for leaving the pillars in this area is the high value of the surface land (fig. 2) ; this excuse, however, is not ap- plicable over the entire area. Around Belleville, and in the entire Belle- ville field, there is considerable rolling country where pulling pillars would do practically no damage. In Madison County, the country is rolling from Collinsville to Edwardsville ; from Edwardsville to Staunton it is very level, but from Staunton to Gillespie it is rough again. Around Hillsboro it is rough, and pillars could well be ex- ILLINOIS COAL LOSSES 17 tracted. It is of course impossible to state all the conflicts that would come up in an attempt to draw pillars, but it seems to the writer that 80 per cent extraction should be secured in the Belleville district as a I Virgin Coal £2-3 Coal that will be ext racted in part or in whole Coal Lost Fig. 3. Coal lost by protection of surface improve- ments. Section of mine workings in Randolph County. Table 5. — Summary of coal losses in the Belleville and Central fields Reason for loss Percentage of market- able coal lost in area worked Coal left on roof and bottom Coal lost in room, entry, and panel pillars (fig. 3) Coal lost in oil or gas-well pillars Coal lost under buildings, railroads, and boundaries Coal lost in handling and preparation, underground and surface Coal lost due to rolls, thin or dirty areas, and streams Total loss, per cent 18 ILLINOIS COAL LOSSES whole. In the Central field there is more level land, and as discussed in the report on the Springfield district, some coal should be left, so its possible extraction is 77 per cent. There is one thing that must be taken into consideration. In the Belleville field limestone forms the roof in probably one third of the area. This makes an excellent roof, and except where the limestone thins out it should stand almost indefinitely, which means that the workings could be re-entered at any time and the pillars extracted. If this should ever be done, it would increase the extraction in the Belleville field, taken as a whole, by approximately 10 per cent. COAL LOSSES IN THE SPRINGFIELD DISTRICT Introduction The district covered in this report includes the counties of Logan, Macon, Menard, and Sangamon. Logan County has 3 shipping mines, and produces approximately 345,000 tons ; Macon County has 3 ship- ping mines, and produces 227,000 tons ; Menard County — the number of mines unknown — produces 341,000 tons ; Sangamon County has about 29 mines, and produces 5,957,000 tons, of which 1,800,000 tons come from No. 6 bed. Practically all the other mines in the counties named are in No. 5 bed. In studying this district, two trips were made underground in No. 5 bed, and one in No. 6 bed, and eight different maps were studied. Coal Reserves The State Geological Survey of Illinois has recently made a care- ful survey to determine the coal resources of the different fields in the State, and its resource figures are therefore based on practical rather than on theoretical considerations. Beds Being Worked Both No. 5 and 6 beds, as defined by the Illinois Geological Sur- vey, are being worked in this district. The mining conditions are very similar, with the exception of the conditions brought about by the difference in the impurities which are found in the beds. No. 6 bed is mined in Sangamon County, south of Springfield, and is 6 to 7 feet thick. It has a very persistent band of dirt near the bottom called the "blue band", about y 2 inch thick. There are also usually two or three dirt bands through the bed, but they do not occur with the same regularity as the "blue band". This bed lies from 270 to 320 feet ILLINOIS COAL LOSSES 19 below the surface. The No. 5 coal is from 4i/o to 7 feet thick, and averages approximately 6 feet. Its impurities consist of clay veins or ''horsebacks" as they are locally known, and an occasional band of sulphur. The clay veins are the most difficult to overcome in mining because they are sometimes found every 15 or 20 feet throughout the bed, and have a thickness varying from a knife-blade up to several feet. Again, in other places, workings will be carried for 100 or 200 feet without encountering a single clay vein. The No. 5 coal lies from 160 to 600 feet below the surface, but throughout most of the field it is from 200 to 250 feet. Nature of Roof and Floor The immediate roof over No. 5 bed is either a black "slate" or a gray shale, either of which varies greatly in thickness. They are usually from 6 to 18 inches thick, and are overlain in places by a few thin strata of soapstone and sandy shale. Above these softer strata there is nearly everywhere a cap-rock of limestone or sandstone varying from a few inches to several feet thick. The condition of the roof de- pends upon the toughness of the immediate roof. As a rule, the black "slate" holds well unless broken by too many clay veins but the gray shale is usually tender. It might be said that 25 per cent of the roof is very good, 25 per cent is very bad, and the remainder medium. The roof over No. 6 bed is generally the same as over No. 5, and further study will be made regarding it in the field farther south. No roof coal is left up in No. 5 bed, but occasionally some is left in No. 6 bed, especially in the entries. Method of Mining All the mines are opened by shafts, and the room-and-pillar method of mining is employed exclusively. Practically all the operators are adopting the panel method with 10 to 50 rooms in each panel. Barrier pillars of 50 to 75 feet are left along the cross entries, which are usual- ly 12 feet wide on 42-foot centers. Room entries are 12 feet wide on 32-foot centers, and the rooms are driven 24 to 26 feet wide on 40 to 45-foot centers. Sometimes the rooms are holed through into the adjoining panel, but the tendency is to leave about a 10-foot fire pillar. No attempt is made to recover any room pillars, and probably a very small percentage of the barrier pillars will be recovered on the final retreat 20 illinois coal losses Surface Value of Land The reason given by the operators for not pulling any pillars is that they do not own the surface rights, and that the owner will de- mand a large compensation if any subsidence takes place. It not in- frequently happens that a squeeze comes on which causes a surface depression and forms a pond. The land is valued at from $200 to $400 an acre for agricultural purposes. In addition, it has a senti- mental value in many cases, from the fact that it has been owned by the same family for several generations. So far as time permitted, the writer carefully observed the topography of the surface, and it can be stated that a perfectly level piece of land a mile square is rare. Usually at intervals of less than a mile there are areas in which the surface has been cut by shallow washes. Practically all the level por- tions are tiled at costs ranging from $10 to $35 per acre. Owing to the fact that sufficient coal is left to hold up the sur- face, no attempt is made to leave solid pillars under railroads, build- ings, or streams. Occasionally a farmer will have the coal reserved under his own buildings, and one or two cases were found where pillars had been left under power-plants. Also, where a railroad had purchased its right-of-way prior to acquisition of the coal by the coal company, that part of the bed which lies immediately under their right-of-way may not be mined. These conditions are mentioned because they must be taken intu account in deciding whether the coal loss is avoidable or unavoidable. Undoubtedly, under most tracts the coal could be taken out clean, and the surface let down practically as smooth as it was before, and the land would not be damaged to any appreciable extent for agri- cultural purposes. The pillar pulling, however, would have to be started with due consideration for the surface topography so that the subsidence would not create a large pond ; also, the coal would have to be taken very clean. If this were done, pillars would have to be left under the railroads and under the towns — at least, under all large buildings. Whether pillars would be necessary under the concrete roads is a debatable question. Calculation of Losses The coal left as roof coal in a few of the mines and distributed over the entire field amounts to only a fraction of 1 per cent, and can be neglected. The coal lost in the room, entry, and panel pillars depends a great deal upon the occurrence of the clay veins. At one mine in No. 5 bed where 24-foot rooms were used on 40-foot centers, ILLINOIS COAL LOSSES 21 it was found that where it was free from clay veins, rooms would be wider than 24 feet, but where the clay veins were frequent, the rooms would be sometimes narrowed down to 12 feet. One operating com- pany has six mines all developed with the same dimensions of work- ing places, and their theoretical loss in pillars is 44 per cent, making a recovery of 56 per cent, not including the loss in handling. The result of calculations at another mine where somewhat larger barrier pillars are left indicates a loss of 48 per cent in pillars. The coal loss resulting from handling and preparation is fairly high, due to the dirt seams in No. 6 bed and the clay veins in No. 5 bed. The writer believes that if the entire seam were mined, at least 8 per cent of the coal would be lost owing to impurities ; but as only half of the seam is being mined, it would mean only a 4 per cent loss on the total tonnage. The summary of the losses is given in Table 6. AVOIDABLE LOSSES Not over 50 per cent of the coal can be safely mined under the towns, and it would probably be advisable not to mine over 40 per cent. The towns probably do not occupy 5 per cent of the total area being mined, and if 60 per cent of the coal is lost under them, it would mean a loss of 3 per cent. Solid pillars of coal should be left under rail- roads and under hard-surfaced roads. If it is assumed that two rail- roads and a cement road cross each coal holding at an angle, and also that the coal holdings are four miles wide, solid coal 800 feet or more Table 6. — Summary of coal losses in the Springfield district Reason for loss Percentage of total marketable coal lost in area worked Coal left as roof and bottom coal Coal lost in room, entry and panel pillars (fig. 4) Coal lost in oil or gas-well pillars Coal lost under buildings, railroads, and boundaries Coal lost in handling and preparation, underground and surface Coal lost due to rolls, thin or dirty areas, and streams Total loss, per cent Total Avoidable loss loss Fraction of 1 44 26 None Included in above 4 3 51 26 22 ILLINOIS COAL LOSSES wide would be left. One thousand feet would be 5 per cent of four miles. Even if from a conservation standpoint the coal should be mined clean under agricultural land, there will undoubtedly be some places where this could not be done. For instance, where pillars are left under railroads and hard-surfaced roads, there might be left a three-cornered piece inside them which should be supported. Assum- ing that pillars could not be pulled under 20 per cent of the minable ffianur ■in rirHDntn &^ Coal that will be extracted ^■Coal Lost in part or in whole Fig. 4. Section of mine workings in Sangamon County- showing pillars not extracted. area, and assuming that the loss in preparation would be 7 per cent, there would still be possible an extraction of 75 per cent, which would be 26 per cent more than is at present being saved. ACTUAL EXTRACTION One company's general manager considers it questionable whether the district is getting 50 per cent of the coal. This operator has six mines in both seams. Another company states that at two of its mines in No. 6 bed they get 50.5 per cent and 55 per cent, respectively, and at one mine in No. 5 bed they get 53.3 per cent. ILLINOIS COAL LOSSES 23 At seven mines of another company in Sangamon County they get an average extraction of 48.12 per cent. Conclusion This district has been reported upon separately because the ques- tion of surface subsidence injuring very valuable agricultural land is the condition determining the method of mining. It is realized that from a practical standpoint it would be exceedingly difficult to get the farmer to permit all the coal to be taken out from under his land, but on the other hand, if an average of 5,000 tons of coal is left by the operator which he could mine by paying for the land at a cost of $300 per acre, it would be only 6 cents a ton for the coal that is lost, or 3 cents on his total tonnage. His saving in cost of operation would be several times this, and he would still have, in most cases, good land left. COAL LOSSES IN THE SOUTHERN ILLINOIS FIELD, IN- CLUDING DUQUOIN AND MURPHYSBORO FIELDS Introduction These fields include the counties of Williamson, with 50 shipping mines producing 10,784,752 tons ; Franklin, with 20 mines and 12,- 723,000 tons; Jackson, with 8 mines and 1,1(54, 154 tons; the east- ern part of Perry County with 11 mines and 1,740,000 tons, and the southeastern part of Washington County, with one mine produc- ing 25,300 tons. This tonnage is taken from the report of the Illinois Department of Mines and Minerals for the year ended June 30, 1921. Four trips were made underground in this field, and specific data were obtained on a total of 31 mines producing L3,500,000 tons. Gen- eral data were also secured on a number of other mines. The coal being mined in this district comes from No. 6 bed of the Illinois Geological Survey, with the exception of 440,000 tons in Jackson County, which comes from No. 2 bed, as will be more fully discussed later in this report. No. G bed varies from 4 to 14 feet in thickness, and averages 9 feet. It is a good grade of coal, and the only persistent impurity is the so-called "blue band", which varies from a fraction of an inch up to 2 inches, and occurs at approximately 18 inches from the floor. The other bands of impurities are not regu- lar, and consist of thin partings of sulphur or mother coal. The bed lies nearly level, with the exception of the western part along the Duquoin anticline, where it frequently dips (5 per cent or more. Also along the Duquoin anticline there is some faulting with displacements 24 ILLINOIS COAL LOSSES sometimes as high as 35 feet ; and in Williamson and Franklin coun- ties there is a little faulting with displacements of a few inches to a few feet. Character of Roof and Floor In most places in this area the immediate roof over the coal is shale or "slate", and varies in strength from very weak to firm, but as a rule is considered as a weak roof. In some places the shale grades into so-called soapstone, which is unusually difficult to hold up with timbers. In Williamson County and southern Franklin County the shale usually contains more sand, so that the roof is generally a little stronger than in the rest of Franklin County. Above the im- mediate roof there is the so-called "cap-rock", or limestone, which is a hard stratum of rock varying considerably in thickness. This cap- rock in some places lies close to the top of the coal bed, and at other places it is 25 feet above the coal, and in a few places it is thought to be absent altogether. Where the cap-rock directly overlies the coal it makes an excellent roof, but the known area of such occur- rences is so small that it is negligible. Owing to the fact that roof coal is left up over a large part of the workings, the exact nature of the roof is not so well known as would be the case otherwise. The floor below No. 6 bed is of fire clay from a few inches to many feet thick, probably averaging 4 to 6 feet. Below the fire clay there is usually a harder rock stratum. The cover varies from a few feet near the outcrop in William- son County, to over 600 feet towards the north end of the field ; and it probably averages 300 feet. Method of Mining Most of the coal comes from mines using the room-and-pillar, panel system, but there are a large number of mines, especially in Williamson County, which use the straight room-and-pillar system. Two mines in this county were found to have the rooms 20 feet wide with 40-foot centers, with rooms 250 to 300 feet long. The entries were 12 feet wide on 37-foot centers. Another mine has rooms 21 feet wide on 40- foot centers, with entries 12 feet wide on 30-foot centers. Another mine has rooms 23 feet wide on 36-foot centers. In Franklin County, where the cover is greater, one mine 250 feet deep employs the panel system, with rooms 24 feet wide on 40-foot centers. Another mine 450 feet deep has 24-foot rooms on 45-foot centers, and the rooms are 250 feet long. This mine is operated on the panel system, and it has been found that the rooms can all be completed ILLINOIS COAL LOSSES 25 and the inside ends of many pillars extracted before a squeeze occurs. An adjoining mine uses 24-foot rooms on 40-foot centers, and seldom is able to get rooms driven up before a squeeze takes place. The panel system of mining, which is in most general use, con- sists of driving the panel centers towards each other, and leaving a 20-foot pillar between them. There are 30 rooms — that is, 15 on each side of each panel entry — which would make 60 rooms to the double panel. Barriers or side pillars along the cross entries are 100 feet or 110 feet. At several mines pillar pulling has been done, but usually only to a very small extent, because as a rule the pillars are too thin to be extracted. Calculation of Coal Losses Figures for a typical mine in Franklin County, when calculated according to the actual dimensions of the working places, gives a loss of 45^ per cent in the pillars, of which about 12 per cent is in the barrier pillars, and a little over 20 per cent in room pillars and room stumps. No attempt is made to save any of these pillars except the inside ends, which have been considered as saved in this calculation. The roof coal is all left up at this mine, and it amounts to 14 per cent of the thickness of the bed, or about 8 per cent of the total coal. To this there should be added about 3 per cent for loss in handling and preparation, giving a total loss of 56^ per cent. At a mine in Williamson County, where straight room-and-pillar mining is employed, the actual dimensions indicate a loss of 40 per cent in pillars ; but only about a third of the top coal is lost, the re- mainder being taken down after the rooms are completed. At this mine the loss in top coal is only 3 per cent, and if 3 per cent is added for loss in handling, the total loss will be 46 per cent. At one mine in Jackson County, which employs the straight panel system with 20 rooms to a panel, the rooms being 22 feet wide and the pillars 23 feet wide, the loss in pillars figures 57 per cent, and the loss in top coal, 10 per cent, which gives a total loss of 70 per cent, including 3 per cent for loss in handling. The loss of coal due to faults is nothing in the majority of the mines, but may be 5 per cent in others, although it probably does not average more than 1 per cent over the entire field. There are also very few reservations except near the outcrop, where the cover is shallow, though occasionally in other parts of the field, reserva- tions are left under certain farmhouses or cemeteries, but as near as the writer could determine, these would not average over 0.5 per cent. 26 illinois coal losses Actual Extraction Fortunately there are a number of actual calculations available, made by different engineers, which furnish good data on the recov- ery in this field. For instance: (1) the average of three mines in Williamson County is 56.59 per cent; (2) the actual extraction of another company from two mines in the same county is 61 per cent; (3) careful planimeter measurements made of three mine maps gave an average extraction of 45.4 per cent, of which 5^ per cent was due to top coal and 2^ per cent to coal left under ponds and as boundary pillars; and (4) three mines in this county gave 50 per cent. Giving each mine the same weight, the average extraction for the 11 mines is 52 J /> per cent. In Franklin County, two mines of one company give an average recovery of 49^2 per cent. The writer was also able to secure other information regarding three mines, one of which had an extraction of 42.7 per cent; another, 39^4 per cent; and another, 31.9 per cent. There are also some reliable data given in Bulletin 100 :: of the University of Illinois. This was the work in charge of the late H. H. Stoek, who had four engineers care- fully taking measurements under his direction. On account of the care with which this work was done, the following has been abstracted from the publication mentioned : "The coal mined is the No. 6 bed of the State Geological Survey classifi- cation. Measurement of 113 sections taken in twelve of the largest mines in the county gave an average thickness of 9.2 feet of coal, the average min- imum thickness for the same twelve mines being 8 feet, and the average max- imum thickness 10.64 feet. The blue band, which is characteristic of No. 6 bed, varied from % to 2 inches in thickness, and its average distance from the floor was 21.5 inches. Owing to the difficulty of keeping up the shaly material above the coal bed, the top coal is almost generally left as roof pro- tection, and up to the present time, very little of this top coal has been re- covered, although some operators are expecting to recover it at a later date in connection with pillar drawing. In one of the twelve mines from which the data were obtained, top coal was not left in the rooms. This, however, is exceptional practice, the average thickness of the top coal left in the twelve mines being iy 2 feet. The average thickness of coal mined was 7.46 feet, and the average tonnage per acre to January 1, 1916, was 6,627 tons. This is equivalent to 40.7 per cent extraction, if it is assumed that all the 9.2- foot bed is available for shipment, or to 41.6 per cent if it is assumed that the blue band and refuse discarded in the loading, or 0.2 foot, is deducted from the thickness of the bed. A very careful estimate for each of the twelve mines noted, made by dividing the total amount of coal in the area mined up to January 1, 1916, into the actual shipments since the mine began operating, 3 Young, C. M., Percentage of extraction of bituminous coal with special reference to Illinois conditions: Engineering Experiment Station Bull. 100, p. 46, 1917. ILLINOIS COAL LOSSES 2? gave percentages of extraction varying from 37.7 to 49.5, or an average of 41.4 per cent." Conditions in Jackson County, Including No. 2 Bed In Jackson County, 1,640,154 tons of coal was produced in 1921, of which approximately 440,000 tons came from four mines working No. 2 bed, these mines being situated in what is known as the Mur- physboro district. The remainder of the production came from No. r *M HHffi'f mi M i |IM|I| i HiiSiih !lfel|l|M MlJlflU lllhll>l i jJSliHIiLJl i i I! il ■ ■ n a _J Virgin Coal ESSCoal that will be extracted m part or m whole Coal lost Pll 5. Section of mine workings in Jackson County showing pillars not extracted. 6 bed. No. 2 bed is from 5 to 7 feet in thickness, and about half of the tonnage came from where the entire bed was being worked, but some top coal was left in the entries. The remainder of the tonnage came from a lower bench only of No. 2 bed, because the bed splits into two benches, the bottom of which is 2>y 2 to 4 feet thick and the top bench 2 feet thick. The band between the two benches varies from 28 ILLINOIS COAL LOSSES 6 inches to 26 feet. This means that where the lower bench only is worked, the top bench is lost, but of course it could not be saved where the parting is very thick. No mines were visited in this field, but this information is gathered from a bulletin of the Illinois Coal Mining Investigations, 4 by S. O. Andros, and from Frank Rossbottom, the State mine inspector in this district. It can be readily seen that because some top coal is lost, and there is very small tonnage, tc include the No. 2 bed in this report cannot appreciably affect the re- sults. One company states that it gets an extraction of 50 per cent from its mines in No. 2 bed in Jackson County. Average Coal Losses In Franklin County the recovery figures are all around 41 or 42 per cent, with the exception of one company ; and owing to the fact that the mines in this county are not very old, and the low figures given were very carefully taken, they are probably correct. In Wil- liamson County most of the figures are over 50 per cent, but at the small mines the extraction is almost as low as in Franklin County, and there are many small mines. Squeezes are also common in all of the counties. Taking everything into consideration, the average recovery for the area is about 47 per cent, including about one-fourth of the barrier-pillar coal on the retreat, which may be saved. Table 7. — Summary of coal losses in southern Illinois Reason for loss Coal left as roof and bottom coal Coal lost in room, entry, and panel pillars (fig. 5) Coal lost in oil or gas well pillars Coal lost under buildings, railroads, and boundaries Coal lost in handling and preparation, underground and surface Percentage of total marketable coal lost in area worked Coal lost due to rolls, thin or dirty areas, streams Total loss, per cent and 4 Andros, S. O., Coal mining: practice in District II : 111. Coal Mining Investi- gations Bull. 7. 1914. ILLINOIS COAL LOSSES 29 AVOIDABLE LOSS The land in this district has little surface value, except where close to a growing town. Some of it is absolutely worthless, and very little of it is worth more than $50 an acre. There is little reason to suppose that pillars could not be pulled in this field and at least 83 per cent of the coal saved. This estimate does not involve removal of the top coal. COAL LOSSES IN SALINE COUNTY Introduction This report covers the mining of No. 5 coal bed in Saline County. There were 23 shipping mines listed in the report of the State Depart- ment of Mines and Minerals for the fiscal year ending June 30, 1921, their total production being 4,245,132 tons. One trip was made underground, and figures were obtained from operators representing the production of nearly 2,000,000 tons. The bed ranges in thickness from I to T feet, averaging a little less than 6 feet. All mining is done by room-and-pillar methods, and in most mines the panel system is employed. Most of the mines are opened by shafts, varying in depth from 65 to 505 feet, with an average of probably 235 feet. Characteristics of the Seam From observations in the mine visited, and from data secured from other operators, it is evident that the roof conditions over this coal bed are, as a rule, excellent. The roof is gray, sandy shale, and stands up remarkably well. The seam is clean, comparatively speak- ing. Occasionally a thin streak of "draw-slate" comes in between the coal and the good top. The floor is of fire claw which in places con- tains sand, and like most of the floor in the Illinois mines, heaves when wet. The floor is also very rolling, frequently making it neces- sary to have steep grades on the entries, or else run them around the high spots. Dimensions ok Working Places Some operators drive wide entries of 18 feet or more, leaving about 30 feet of pillar between, and others drive entries only 12 feet wide. Rooms are from 24 to 28 feet wide, and pillars are 12 to 18 feet thick. Sometimes room-necks are narrow, but more frequently the rooms are started about 20 feet wide, and gradually widened to their full width. Room crosscuts are 18 to 20 feet wide, 30 ILLINOIS COAL LOSSES Losses of Coal From calculations made at the mine visited, which was said to be an average of the district, the loss in pillars, including 75-foot barrier pillars, amounts to 38 per cent. Owing to the cleanliness of the seam, the coal thrown back into the gob does not amount to over 3 per cent. Unfortunately the beds are cut by numerous faults, with throws of from a few inches to over 100 feet. It is difficult to ar- range the plan of a mine to get all the coal along these faults, and also the roof is bad near them. One operator claimed that they had lost I Virgin Coal IM1 Coal that will be extracted in part or in whole. Coal Lost Fig. 6. Section of mine workings in Saline County showing pillars not extracted and coal lost be- cause of irregular workings and due to displace- ment faults. no coal on account of faults as yet, whereas the map of another mine showed a loss of about 10 per cent. Probably 5 per cent represents an average loss. Actual figures of extraction, as reported to the writer, were as follows: (1) 57.06 per cent; (2) 3 mines, 51 per cent, 51.5 per cent, and 53.3 per cent; (3) 51 per cent. AVOIDABLE LOSS The conditions in this field, as far as the coal bed is concerned, are ideal for pillar pulling. From the standpoint of surface condi- ILLINOIS COAL LOSSES 31 tions, the land is valuable for farming, but not so valuable as that in the Springfield district. Also it is more broken, and very little, if any, is tilled. There are fewer towns and fewer railroads. The land is occasionally flooded by high water in Ohio and Wabash rivers, but the mining companies could well afford to build levees as high as the ground would subside from pillar drawing, if such would be neces- sary. Taking everything into consideration, an extraction of 85 per cent ought to be secured in this field. LOSS IN OVERLYING SEAMS The No. 6 bed is about 70 feet above No. 5 in this area, and is of workable thickness. As mining is now carried on, No. 6 seam will not be affected except where squeezes occur, or where caves in rooms extend up to it, which is rare. On the whole, it is the writer's opinion that very little coal in No. 6 bed is at present being lost, but informa- tion either for or against this conclusion could not be obtained. Table 8. — Summary of coal losses in Saline County Reason for loss Coal left as roof and bottom coal Coal lost in room, entry, and panel pillars Coal lost in oil or gas-well pillars Coal lost under buildings, railroads, and boundaries Coal lost in handling and preparation, underground and surface Coal lost due to rolls, thin or dirty areas, and streams" (fig. 6 ) Percentage of total marketable coal lost in area worked Total Avoidable loss loss None 38 31 None Included in above 3 5 •• 46 31 Total loss, per cent a Includes coal along faults. COAL LOSSES IN THE DANVILLE DISTRICT Introduction The Danville district has 7 mines in No. 6 bed and 5 mines in No. 7 bed, but by far the largest production comes from the former. It includes Vermilion County only, and has a total production of slight- 32 ILLINOIS COAL LOSSES ly over 3,000,000 tons, of which about 450,000 tons come from strip or open-cut mines. No trips were made underground while studying this field, but operators were interviewed who mine over half of the total tonnage. The characteristics of the beds have been described by S. O. Andros in a bulletin of the Illinois Mining Investigations series, 5 as follows : "In this district all the large outputs are produced from the No. 6 bed of the Illinois State Geological Survey correlation. "The chief characteristic of the No. 6 bed, which averages 6 feet in thick- ness, is the presence of a blue band which divides it into upper and lower benches. This blue band varies from soft dust to hard gray shale, and occurs about 2 feet above the floor. In addition to this blue band there are several shale and sulphur bands of variable horizontal and vertical extent. "The roof over No. 6 coal is variable. Near Danville the immediate roof is a grayish black shale about G feet thick. This shale, lying between the coal and the cap-rock of dark-gray nodular limestone makes an easily sup- ported roof. In the vicinity of Westville and Georgetown the immediate roof is usually a gray shale, which shows no distinct bedding, has little cohesion, falls in conchoidal masses, and is extremely difficult to support. Further, stringers of coal extend from the bed proper into the roof material, and render the roof more difficult of support. In isolated cases there are 3 to 4 inches of black shale between the coal and the gray shale which forms the cap-rock. Whenever this black shale is broken, air and moisture disintegrate the gray shale cap-rock, and the roof becomes insupportable. "In all parts of the Danville district the floor is a soft fire clay. "The No. 7 bed varies in thickness from 2y 2 to 5% feet, and averages 5 feet. The coal has two benches separated by a clay band 1 inch thick, which persists through the bed from 6 to 8 inches above the floor. The two benches present no great difference in appearance or in physical character, except locally, where the top bench is harder and has a brighter luster. The No. 7 bed generally has slightly more impurities than the No. 6 bed, higher volatile matter, lower fixed carbon, and higher sulphur content as shown by analyses of 31 face samples in No. 6 and of 18 face samples in No. 7. The bands of pyrites occur persistently at a height of 20 to 26 inches above the floor, and sulphur balls or nodular concretions of pyrite are present in such quantity as to make profitable their separation from the coal by hand picking in the mine, and by a further separation on the surface in rotating cylinders. "In both beds in the district there are numerous rolls, called 'faults,' or 'horsebacks' by the miners. These rolls appear to have been due to un- equal settling of the coaly matter and the necessary readjustment of the roof materials, during the formation of the coal. In many cases the roll entirely displaces the coal. "The mines in District VIII are shallow, and the deepest mine does not exceed 300 feet." 5 Andros, S. O., Coal mining practice in District VIII (Danville); 111, Coal Mining Investigations Pull. 2, 1914, ILLINOIS COAL LOSSES 33 Method of Mining Room-and-pillar methods of mining are employed, with some ef- forts to divide the workings into panels. One of the largest com- panies uses 24- foot rooms driven on 30- foot centers. Some room pillars are drawn, but over the entire field the amount of coal thus re- covered amounts to very little. Some of the companies try to protect the surface where it is agricultural land, but others do not, rctnn I Coal that will be extracted m part or in whole ICo.il Loj Fig. 7. Section of mine workings in Vermilion County showing coal lost because of irregular spacing and direction of rooms. as they do not have to pay damages for surface subsidence. Under the towns and railroads the work is carried on according to the usual method, except that more care is taken to leave sufficient pillars to avoid squeezes. In the north end of the district, along Little Ver- million River, a great deal of coal has to be left under branch streams which flow into the river. However, this coal being of shallow depth, it can be recovered in a large part by stripping operations. u ILLINOIS COAL LOSSES Losses of Coal One company producing about 1,400,000 tons per year reported that its extraction is from 55 per cent at the smaller mines to 65 per cent at the larger mines, and that 15 per cent of the total loss is due to rolls and faulty conditions. Another company figures on an ex- traction of 53.43 per cent. Under ordinary conditions, with 24-foot rooms and 6-foot pillars, the loss in pillar coal would be 32 to 35 per cent, and judging from experience in the Panhandle and Belmont fields of West Virginia and Ohio, the writer does not believe that the mines in the Danville field can get 65 per cent of their coal when their faulty conditions are considered. Without further information the writer can not see how the extraction in this field can be over about 57 per cent in the underground mines, divided as shown in Table 9. Table 9. — Summa?-y of coal losses in the Danville district Reason for loss Percentage of market- able coal lost in area worked Total loss Avoidable loss Coal left on roof and bottom None 32 Included in above 4 7 Coal lost in room, entry, and panel pillars (fig. 7) Coal lost in oil or gas-well pillars 23 Coal lost under buildings, railroads, and boundaries Coal lost in handling and preparation, underground and surface Coal lost due to rolls, thin or dirty areas, and streams . ' Total loss, per cent 43 23 AVOIDABLE LOSS Owing to the fact that some of the companies have the surface rights, and also that the county has fewer towns and is more rolling in contour, they should get a higher extraction than is possible in the Springfield district. The question of possible recovery and the means of arriving at it have been discussed in the Springfield report, and based on the same reasoning possible recovery in the Danville district should be 80 per cent. 35 PUBLICATIONS ILLINOIS MINING INVESTIGATIONS ILLINOIS STATE GEOLOGICAL SURVEY DIVISION URBANA, ILLINOIS Bulletin Bulletin Bulletin Bulletin Bulletin 1. 3. 10. 11. 14. Bulletin Bulletin Bulletin 15. 16. 17. Bulletin 18. Bulletin 20. Bulletin 21. Bulletin 2° Bulletin 23. Bulletin 24. Bulletin 2 5. Bulletin Bulletin Bulletin 26. 2L 28. Bulletin Bulletin 2 9. 30. Preliminary report on organization and method of investigation, 1913. Chemical study of Illinois coals, bv S. W. Parr, 191 6. Coal Resources of District 1 (Longwall). by G. H. Cady, 1915. Coal resources of District VII, by Fred H. Kav, 1915. Coal Resources of District VIII (Danville), bv Fred H. Kav and K. D. White, 1915. Coal resources of District VI, by G. H. Cady, 1916. Coal resources of District II (Jackson Co.), bv G. H. Cady. 1917. Surface subsidence in Illinois resulting from coal mining, by Lewis E. Young, 1916. Tests on clav materials available in Illinois coal mines, bv It. T. Stull and R. K. Hursh, 1917. Carbonization of Illinois coals in inclined gas retorts, bv F. K. Ovitz, 1918. The manufacture of retort coal-gas in the central states, using low- sulphur coal from Illinois, Indiana, and western Kentucky, by W. A. Dunkley and W. W. Odell. 1918. Water-gas manufacture with central district bituminous coals as generator fuel, by W. W. Odell and W. A. Dunkley. 1918. Mines producing low-sulphur coal in the central district, by G. H. Cady, 1919. Water-gas operating methods with central district bituminous coals as generator fuel. A summary of experiments on a commercial scale, bv W. A. Dunkley and W. W. Odell. 1919. Gas purification in the medium-size gas plants of Illinois, by AY. A. Dunkley and C. E. Barnes, 1920. Coal resources of District IV, by G. H. Cady, 1921. Analyses of Illinois coal, compiled by G. W. Hawley. 1923. Preliminary report on coal stripping possibilities in Illinois, by Harold E. Culver, 19 25. Coal resources of District III. by Harold E. Culver, 1925. Coal losses in Illinois, by C. A. Allen, 1925. Bulletin 2. Bulletin 4. Bulletin 5. Bulletin 6. Bulletin 7 Bulletin s'. Bulletin 9. Bulletin 12. Bulletin 13. Bulletin 91. Bulletin 100. Bulletin 113. Bulletin 119. Bulletin 125. Bulletin 132. Bulletin 144. Bulletin 72. Bulletin 83. Bulletin 99. Bulletin 102. EN< 1 1 X EER [NG EX PER] M ENT STATION URBANA, ILLINOIS Coal mining practice in District VIM (Danville), by S. ( ). Andros, 1913. Coal mining practice in District VII, by S. O. Andros, 1911. Coal mining practice in District I (Longwall), by S. O. Andros, 1 91 4. Coal mining practice in District V, by S. (). Andros, 1911. Coal mining practice in District 11, by S. (). Andros. 1914. Coal mining practice in District VI. by S. O. Andros, 1914. Coal mining practice in District III, by S. (). Andros. 1915. Coal mining practice in District IV. by S. O". Andros, 1915. Coal mining in Illinois by S. (). Andros. 1915. (Complete resume ,,f all the district reports. ) Subsidence resulting from mining, by L. E. Young and II. II. Stock, 1916. Percentage of extraction of bituminous coal with special reference to Illinois' conditions, by C. M. Young - , 1917. Panel system of coal mining:, by C. M. Young;, 1919. Some conditions affecting; the usefulness of iron oxide for city gas purification, by W. A. Dunk lev, 1921. The distribution of the forms of sulphur in the coal bed, by II. F. Yancey and Thomas Fraser, 1921. A study of coal mine haulage in Illinois, by II. II. Stock, .1. It. Fleming; and A. .1. Hoskin, 1922. Power studies in Illinois coal mining, by A. .1. Hoskin and T. Fraser, 1924. U. S. BUREAU OF MINES WASHINGTON, D. C. Occurrence of explosive gases in coal mines, bv X. H. Darton, 1915. The humidity of mine air, by R. Y. Williams, 1914. Mine ventilation stoppings, by R. V. Williams, 1915. The Inflammability of Illinois 'coal dusts, bv J. K. Clement ami L. A. Scholl, Jr., 1916. ;*g Bulletin 138. Bulletin 203. Bulletin 234. Bulletin 137. Use of permissible explosives in the coal mines of Illinois, bv J. R. Fleming and J. W. Koster, 1917. Coking- of Illinois coals, by F. K. Ovitz, 1917. Central district bituminous coals as water-gas generator fuel, by W. W. Odell and W. A. Dunkley, 19 24. The screen sizing of coal, ores and other minerals, by E. A. Holbrook and Thomas Fraser, 192 4. Technical Paper 190. Methane accumulations from interrupted ventilation, with special reference to coal mines in Illinois and Indiana, bv H. I. Smith and Robert J. Hamon, 1918. Technical Paper 246. Water-gas apparatus and the use of central district coal as generator fuel, by William W. Odell, 1921. Technical Paper 268. Preparation and uses of tar and its simple crude derivatives, by W. W. Odell, 1922. Technical Paper 2S4. Coal and coke mixtures as water-gas generator fuel, by W. W. Odell, 1921. Technical Paper 304. Water-gas tar emulsions, by W. W. Odell, 1923. Technical Paper 330. Small hose streams for fighting mine fires, by L. D. Tracy and R. W. Hendricks, 1924. Technical Paper 361. Cleaning tests of central Illinois coal, by Thomas Fraser and H. F. Yancey. 1925.