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By J. J. Forbes

Gentlemen : It is a pleasure to come to Glen- wood Springs to participate in this meeting of the Rocky Mountain Coal Mining Institute an organization created to handle chiefly the economic questions dealing with the coal industry of the Rocky Mountain District. I am not unmindful of the many and varied problems confronting the mining industry of this country which is so general at the present time throughout the United States. By reason of the difficulties experienced in marketing the product of your mines, there is all the more reason for greater economy and efficiency in production. No industry can be efficiently operated without giving due consideration to the safety of the employees. Safety and efficiency are inseparable for the success of any industrial enterprise. While the Bituminous coal companies of the United States are doing splendid work in the promotion of safety, yet our fatality rate is exceedingly higher compared with that of foreign countries, and with greater cooperative organized effort on the part of mine owners, mine officials, mine workers, and state and federal governmental agencies having jurisdiction, much more substantial progress can be made in the future and a greater economic saving .to the industry effected, not taking into consideration the greatest and most important phase of safety, which is the conservation of life and health of all those who are engaged in the occupation of mining. You are concerned with freight rates, marketing of coal and similar operating problems. Yet have you earnestly considered the vital question that plays so important a part toward the success of any mill-

Jan 1, 1926

By J. J. Craron

MR. J. J. CRARON: If Ross Weber rings that bell of his, I think I have a few secrets on him that I will tell. It is not such a long time ago when the sales and executive departments of the coal industry were constantly urging the operating department to increase their output, and this cry for increased production resulted in vast development work and increased capacity to the point where the operating departments are today in position to produce coal upon sudden demand far in excess of the ability of their sales departments to dispose of it. So today our ability to produce coal is away ahead of our ability to market it. There are many reasons, of course, for this condition. First, the present economic situation, which has prevented even a normal consumption of coal. Secondly, the over-development and production of every commodity and industry as the result of war time and post-war time prosperity. Thirdly, the inroads made by competitive fields, particularly oil and gas, because of the desire of the public for automatic heat.

Jan 1, 1934

forated, allowing the completion of the removal of wash water. When discharged into the washed nut bin, the coal is moist but carries so little water as to not be objectionable to the trade, nor to give any difficulty from freezing during the coldest weather. The rock and bone from the primary jigs is elevated to a 15-ton bin by means of a single strand scraper conveyor 40 feet center to center operating on a 45 degree incline, carrying 12" x 5" scrapers every two feet. This conveyor travels at a speed of 100 feet per minute and has a capacity of 17 tons per hour. From this bin, this material falls into the third or rewash jig similar in all respects to the first two, which discharges the rock waste directly into a 15-ton refuse bin below and the bone into a short dewatering conveyor which delivers into a similar 15-ton bin from which the bone is taken to the powerhouse. The oversize and water from the shaker screen, the water from the dewatering conveyor for both the washed nut and bone, and the sludge and wash water from the three jigs, are delivered by launders to the first compartment of a three-compartment settling tank. Most of the coarser broken coal is deposited in this tank, from which is it continually removed by a bucket elevator carrying 8" x 5" perforated buckets operated on a 60 degree incline at 200 feet per minute, capable of delivering 25 tons per hour to the 50-ton washed coarse slack bin. The water passes successively through the three compartments of the settling tank and from thence through a six-inch pipe to a centrifugal pump, circulating 900 gallons per minute against a 32-foot head. A four-mesh screen 30" x 72" in the third compartment of the settling tank removes the chips of wood, paper, and the other trash, which otherwise would accumulate in the water. Water is provided from the camp water system, deriving water from the well located in an arroyo bed. During the summer months just passed, the water used, has been 108 gallons per ton of raw nut, or 146 gallons per ton of washed nut. The water meter had not been installed last winter, but it is estimated that operating at capacity, the washery will be found to require only about 75 to 100 gallons per ton of raw nut. It has not been found necessary, nor advisable, to attempt to dry the sludge from the settling tank, nor to save the water from leakage of the tanks and bins. The sludge from the jigs is washed into the settling tank and the sludge from the settling tank is washed through a tile drain to the arroyo. The jigs, shaker screen, circulating pump, washed slack elevator, and the rock handling conveyor, are all driven from line shafts driven by one 40 H. P. motor, each jig driven through a clutch. The belt conveyor and the washed nut conveyor, have separate motor drives of five and seven and a half H. P. respectively. The washer is housed in a corrugated iron building, which is partially heated by steam coils. One attendant is required for operation, regulating the feed of the jigs, the supply of water, removal of the rock, and oiling and maintaining the machinery. The rewash jig is operated only intermittently. About eleven per cent by weight of raw nut is removed as waste and four per cent goes to the washed slack bin. No control analyses of the products have been made; the efficiency of the plant being determined only by the physical appearance of the products; but the washery has been a source of pride and satisfaction to all those connected with it. As mentioned before, it has caused no interruption of operation and it has assisted materially in creating an unprecedented demand for ALAMO nut. MR. CHARLES: If there are any questions, I shall be pleased to endeavor to answer them. MR. LITTLEJOHN: Mr. Charles, do I understand it is the nut only that is washed there? MR. CHARLES: Yes, sir. MR. LITTLEJOHN: What did you say the size was? MR. CHARLES: Through three inch round perforations, retained on

Jan 1, 1926

By William Perry Pendley

Let us go back in time, back to when a Navy veteran from the South was President of the United States, a man from the Rocky Mountain West was Secretary of the Interior and a leading environmentalist was head of the EPA; and there followed what many perceived of as a war on the West-on our water, on our timber, on our oil and gas and mineral exploration, and on our small communities. It's easy to think that I'm talking about the administration of James Earl Carter, III of Georgia, but I'm not. I'm talking about this administration, the administration of George Herman Walker Bush of Texas. I say that as a life-long Republican who never voted for a Democrat and who worked hard to put George Bush in the Oval Office. Many of us wondered, in 1988, what Vice President George Bush meant when he said; "I am an environmentalist." Well, now we know. In his State of the Union address, which was otherwise lacking in specific detail, George Bush said two very specific

Jan 1, 1990

ARTICLE I - General Section 1. Name. The name of the corporation shall be The Rocky Mountain Coal Mining Institute. Section 2. Objects and Purposes. The objects and purposes of The Rocky Mountain Coal Mining Institute and the nature of the business to be carried on by it are as follows: (a) To sponsor educational programs pertaining to coal mining technologies and production techniques, mining management and safety, federal, state, and local laws, rules and regulations pertaining to coal mining, and other energy related issues. (b) To disseminate to the public and to educational and scientific institutions knowledge, and the results of study and research into recent developments in coal mining technologies and production techniques, mining management and safety, federal, state, and local laws, rules, and regulations pertaining to coal mining, and other energy related issues. (c) To do and engage in all lawful activities that further or are consistent with the preceding objects and purposes of the corporation. Section 3. Nonprofit Corporation. This corporation shall operate as a nonprofit corporation under the laws of the State of Colorado. ARTICLE 11- Principal Office and Corporate Seal Section. 1. Principal Office. The principal office and place of business of the corporation in the State of Colorado shall be in the County of Jefferson, Colorado, or at such other location as the Board of Directors may from time to time determine. Other offices and places of business may be established from time to time by resolution of the Board of Directors. Section 2. Corporate Seal. The seal of the corporation shall be inscribed with the name of the corporation, the year of its incorporation, and the words "Colorado" and "Seal," and shall be in a form approved by the Board of Directors, which may alter the same at pleasure. ARTICLE III - Members Section 1. Classes. The membership of the corporation shall be divided into three classes, consisting of active members, life members, and senior members, who shall have such rights, privileges, and qualifications as these bylaws may provide. Section 2. Qualifications. The members of the corporation shall have the following qualifications: (a) Any individual interested in the goals and purposes of the corporation may become an active member of the corporation upon payment of such annual dues as the Board of Directors may determine from time to time by resolution. (b) An individual who has devoted long and dedicated service to the corporation and to its goals and purposes may become a life member of the corporation upon being elected to that status by the Board of Directors, and such individual shall retain such status for life. (c) An individual who has been at any time an active member of the corporation and who has reached 70 years of age may become a senior member upon payment of such annual dues as the Board of

Jan 1, 1994

By D. Harrington

E. H. DENNY (United States Bureau of Mines, Denver, Colorado) In the absence of Mr. Harrington it is my privilege to read his paper, which is in his usual, forcible and sincere style, and it is within the province of this Institute, certainly, to go into it as it concerns safety and efficiency in mining. He brings out some points in his paper that, I think, are well worth the consideration of the Institute. The figures he uses were compiled by Mr. Adams, of the Bureau, and cover a five-year period. However, examination of similar Bureau figures for a ten-year period, or any other long period on other bases brings out similar results. The figures in this paper have been based on the million hours of exposure of accidents, and the figures based on three hundred working-man-day basis, or on tonnage, brings out similar results. This paper is entitled "Accident Record in Western Mines," and it is, in a way, an amplification of Mr. Harrington's letter which was read at the Glenwood Springs Meeting.

Jan 1, 1927

of our good friends and fellow members: James Dalrymple, Sr. R. M. Perry A. E. Oliver R. M. Harding C. L. Oliver Arthur S. White Arthur N. Fancher A. E. Lindrooth D. A. Stout Clayton Morrison Frank O'Ryan Charles Billington who left the world better for their having lived in it.

Jan 1, 1935

By Michael A. Berdine

Twentymile Coal Company?s first longwall face in the late 1980?s was oriented approximately 45 degrees to the major coal cleats and 45 degrees to the primary horizontal stresses. This combination of stress and coal cleating resulted in frequent violent bursts of coal along the longwall face. The bursts created particles of sufficient size and force with the potential of causing injury to employees and occasional damage to shield components. Partial web cutting was subsequently developed in an attempt to relieve the stress on the coal face and required the shearing machine to travel to the tailgate and back for a full 36 inch web. The partial web cutting pattern is focused on first cutting the lower 90% of the seam to relieve the stress as the shearer travels from the headgate to the tailgate. The web depth during the headgate to tailgate pass is typically in the range of 70% to 80% and varies with conditions to maximize production rates. The top and bottom of the seam in the remaining 20 to 30% of the web are then cut out to allow the shields and face conveyor to advance. 100% of the web is cut at each gate end for a distance of approximately 19 shields. This paper addresses some general mine geology and the procedures and benefits of partial web cutting with respect to safety, production and maintenance on a high production longwall face.

Jan 1, 2004

By Warren C. Bracewell

At your request, am submitting to you several suggestions for the amendment of our safety code which you felt should be kept up to date. These suggestions are the individual opinions of the several members of the Committee who have expressed (heir wishes to me in the form of letters. I am particularly indebted to Mr. Daniel Harrington, Mr. Wm. Littlejohn, Mr. Warren Bracewell, Mr. James Dalrymple and Mr. Hugh McLeod. Would recommend the following amendments Section 1. Wherever practical trolley wires should be securely hung to roof or timbers at a distance of not less than five feet and not more than six and one-half feet above rail and six inches to one side. Spacing of hangers should be from 20 to 25 feet apart. (Adopted.) Section 2. 500 volts D. C. should not be allowed in any installations. Trolley wires should not carry a voltage of more than 250 D. C. nominal voltage. (Referred back.) Pumps, mining machines and other small machinery units where A. C. power is used should not carry a voltage of more than 220. Large units, such as pumps, motor generator sets and hoists, may use a volt- age of 2,200. When power cables to operate same are of armored construction, cables should be securely buried at all crossings, on haulage-ways or where men travel. (Adopted.) Section. 4. Where power lines pass through door frames or stop- pings they should be properly insulated with porcelain compound or rubber tubing. Wherever men get on or off man-trips in vicinity of trolley wires same should be secure1y guarded and should also be protected with a cut- out switch, same to be pulled before men are allowed to get on or off trips. (Adopted.)

Jan 1, 1926

PRESIDENT WETZEL: The meeting will come to order. We are pleased to see a few of the more hardy survived last night's-ordeal and are present this morning. The Secretary has some correspondence which he will read. SECRETARY WHITESIDE: Gentlemen, I have a couple of telegrams and a letter which I would like to read to you at this time. First, a telegram addressed to Mr. Wetzel: "Regret greatly necessity canceling my plans to be present at meeting. Appreciate your conveying my best wishes to members for successful and profitable session.

Jan 1, 1942

PRESIDENT BOTTOMLEY: Gentlemen, the next order of business, if you wish to discuss it is Mechanical Loading. We still have a little time left that could be devoted to that subject, and the meeting will be open now for that purpose. Where is Mr. Edge- worth? J. E. EDGEWORTH (Foreman, Union Pacific Coal Company, Rock Springs, Wyoming): Here. PRESIDENT BOTTOMLEY: Yon start the ball rolling. Tell us what you are doing in the Rock Springs District, on the mechanical loading. SECRETARY SHURART Mr. Edgeworth is the man at the face handling the coal. He never sees the light of day these late winter mornings.

Jan 1, 1927

MR. STOUT: The picture shows the plan of the "V"-system as worked at Berwind mine, in a small strip of coal adjacent to the 4th right entry. The dotted line (indicating) show the position of the break rows as set for each of the three consecutive breaks. In two cases the break rows failed to function properly and as a result, the roof caved along the points of the "V's" as well as back along the faces a short distance. This affected the ventilation to a certain extent, but was remedied immediately by cutting through the points near the cave and setting additional timbers. At the present time we are putting in the break row of heavy red spruce props, making the row straight instead of curved as is shown in the picture; in this way we believe we can better control the breaks. The three "V" entries were driven up 14 feet wide, for a distance of 260 feet without cross-cuts. A very neat and substantial line brattice was carried up each entry as the places advanced. The principal factors in determining the success of this system are ventilation, roof control, and transportation. We are well pleased with the results from these three "V" places and now have four other places, about 500 feet to the west of these, driving at the present time in which we hope to get still better results. A MEMBER: What centers did you use there? MR. STOUT: We used 70 feet. This may be increased or decreased according to local conditions. MR. F. W. WHITESIDE (Chief Engineer, Victor-American Fuel Co.) Will you please describe roughly how your cars are handled? MR. STOUT: Cars are brought from the parting and pushed up along the faces by a storage battery locomotive. The faces are about 70 feet long and we found that five or six cars can be loaded and transported very conveniently. It is important to get a quick exchange of cars, and in this way we were able to keep the shovelers busy at all times. A MEMBER: What is the grade in your "V" entries? MR. STOUT: Five per cent in favor of the loaded trip. A MEMBER: What is the angle of your "V" faces? MR. STOUT: The angle at the throat is 45 degrees. MR. SAMUEL ANDREWS: In what direction does the air travel? MR. STOUT: The air travels down the dip entries and is deflected up the first "V" entry, and travels along the points, and returns down the last entry. There is no more difficulty in ventilating "V" faces than in ventilating rooms, providing the points are kept open. A MEMBER: What amount of air do you have in that section? MR. KAISER (Superintendent, Berwind Mine): Eighteen thousand cubic feet per minute. MR. ANDREWS: It is necessary, Mr. Stout, to brattice these places?

Jan 1, 1925

By J. J. Welch

The thought and practices in the field of accounting in the past two or three years are undergoing far-reaching changes, but more important than this is the changing viewpoint of business managers toward accounting reports and statistics. Accounting is no longer considered a necessary burden of business, for progressive managers and operating officials everywhere look upon it as a service. A service of supplying operating men and executives with information on their affairs which enables closer and more effective supervision, to the end that business may be conducted more satisfactorily and more profitably. This service is the real function of accounting in business management. Of the many treatises on accounting published in recent years, the great majority deal with principles and procedures, and were written purely from the accountant's point of view, thus they appeal, and are of interest, chiefly to accountants. Recently, however, the interest displayed by the operating man, be he president, general manager, superintendent, mine foreman or potential mine executive, calls upon the accounting department to serve him in furnishing him with figures showing the financial position and economic progress daily. In order to effectively render this service the necessary co-operation between management, operating and accounting -forces must exist. Satisfactory services may be developed only on a basis of close contact and pulling together between these departments. It is not a one-man job, the responsibilities necessarily rest on all. This co-operation contemplates:

Jan 1, 1932

MR. HARRINGTON: I would like to ask Mr. Bottomley if they fire their shots while the men are in the mine? MR. BOTTOMLEY: No sir; the shot-firing law in our State requires the shots to be fired after the men are out of the mine. We fire more shots than we did under the hand method of loading. Where formerly four holes were drilled, now we drill eight, using the same amount of powder as we did formerly, perhaps a little more, but we use a slower grade of powder. CHAIRMAN LITTLEJOHN: Any further discussion, gentlemen? MR. GIBSON: Mr. Chairman, I would like to ask Mr. Bottomley, if, in his shot-firing system, as I understand it, he has a very high coal and is working something like eleven feet? MR. BOTTOMLEY: Something like that. MR. GIBSON: I read the article that you referred to. Did you use both the first and the second delay explo¬ders in shooting the coal? MR. BOTTOMLEY: We use the ordinary fuse. MR. GIBSON: That is what I wanted to find out; whether you use the delay exploders and the detonators. In Utah, we are getting away from the fuse altogether, because we do not think it is accomplishing anything to use the electric light on the cap, and' at the same time shooting with fuse. We are defeating the object we might gain in using the electric safety lamp. That is a point that might be discussed a little further. MR. E. H. JOHNSON, The Coloder Company: I would like-since it is a general opinion that mechanical loading breaks up the coal, to ask Mr. Bottomley, if he finds a larger percentage of small coal, or how much, through the use of the mechanical loaders? MR. BOTTOMLEY: We do not find any great difference. In fact, we have succeeded in improving our lump coal percentage, and that is important, because it is largely domestic. At first, when the machines were installed, the boys shot the coal too hard, and we fell down a little, about two or three per cent, the first month, in our lump percentage, and we tightened up a little and changed our methods in shooting and got on to the stunt of drilling more holes and getting a slower grade of powder. We could not load as much coal in one day as we could before, but we did succeed in in. creasing our lump coal percentage four and a half per cent over the hand method, and that is quite a factor-quite an important factor and since our domestic trade is over with, we loosened up on the shooting and we are running about the same as we did with the hand loading, maybe a half per cent more, or one per cent, but pretty much the same. MR. SHUBART: Your coal is very high? MR. BOTTOMLEY: Yes. MR. SHUBART: Have you tried sunbbing the coal before shooting? MR. BOTTOMLEY: No, we have not tried that. It is very hard coal to shoot; we have no defined cleavage in our coal. It is the worst coal I ever saw to shoot. We do not try to snub it. Formerly, as I said, the miners drilled four holes, pretty well up near the top, and then four holes down, within about three feet of the bottom. It is the same thing as a snub shot, and that we find is the best method for shooting the coal. We have not tried any mechanical device for snubbing as yet. SECRETARY SHUBART: At one mine I saw snubbing tried with a Jeffrey undercutter with a seven-foot Jeffrey bar. This mine, by the way, is very similar to Mr. Bottomley's condition. They have very high coal, so the snub cut is a small percentage. They cut a seven foot undercut and raise the machine on an eight inch tie and undercut five feet to give the effect of a snub cut, 14 inches at the front of the cut, and then six inches at the back of the cut. They made a very marked increase in lump. (The bug dust would be a small percentage of the total coal), and they increased the percentage of the slack at the same time. They found a decrease by reason of the easier shooting of about 15 per cent in their slack. In other words their nut and lump coal ran considerably higher and their slack decreased 5 per cent with the snubbing cut. Mr. Bottomley, I believe, understands those conditions.

Jan 1, 1926

By Edward Bottomley

Mr. Chairman and Gentlemen: I tried to get Benedict Shubart to have some fellow-some big fellow with a big voice-to read this paper for me, but he said there was nothing doing; [ ] that I would have to read it myself. I will try and not take up too much of your time. It is a pretty big subject, Mechanical Loading, and it covers a good deal of ground. I have merely touched on the high spots, as it were. A great deal has been preached and written in the last year or so about mechanical loading, and I doubt if any other subject in the mining industry has been discussed so freely and as often in the last few years. It is not the intent of this paper to dwell on the merits or demerits of any [ ] particular type of loader, that is, to say what the writer thinks is the most efficient or most inefficient machine. There are several types of loaders on the market to-day that are proving very successful in many mining districts. Some of these, five or six years ago, seemed to be a miserable failure from every standpoint, mechanically

Jan 1, 1926

By Kirk Nobis

Develop a Risk Management Plan for Your Mine ? Why? ? Measuring ? Managing ? Conclusion

Jan 1, 2006

By Robert E. Hanes

Coal Perspectives We are the ?Saudi Arabia of Coal Reserves? (Billions of Short Tons) [ ] However, China & India have added approximately one half of the U.S. installed base capacity for electrical generation, in TWO YEARS ? and it took us some 50-60 years to install our coal fleet.

Jan 1, 2008

By H. F. Nash

Coal is the basic necessity of our present-day civilization, and those engaged in the industry, whether miner, day-man, pit boss, tipple boss, superintendent, salesman or operator, have a direct responsibility to the public at large. Our country is blessed with a great supply of Bituminous coal, upon which it must largely depend for its industrial prosperity. Anthracite coal, in its relation to our economic situation, is a small factor, as its ratio of production to Bituminous coal is only about one-sixth. However, within the last ten years, electricity and oil have largely displaced the use of coal in industry, so that the use of Bituminous coal is decreasing, relatively, and the potential production of Bituminous coal has largely increased since the war. High wage scales and high freight rates make the delivered price of coal to the consumer so out of proportion to the cost of electricity and oil -and strikes make the supply of coal so uncertain-that industry is rapidly turning to electricity and oil. The energy in a ton of coal can be transported, by electric current, a distance of 250 miles for 78% of what it costs to ship the coal in bulk, by rail, in the East-and, for about 60% of what it costs in our section of the country. The use of fuel oil, distillate and gasoline, in industry, has increased by leaps and bounds. Especially was this noticeable during the strike this year, as the large packing plants in Kansas City, Omaha and Sioux City (that formerly used nothing but coal) are now practically all using oil. This also supplies to other industrial plants throughout our territory in Texas, Oklahoma, Kansas and Nebraska. Many railroads are using oil, as are also the smelters, cement plants, etc., etc. Ten years ago, 100% of the threshing in the state of Kansas was done with coal-today not over 25% of it is done through that means-and so it goes all along the line. The use of our coal is being yearly more restricted in industry. In the case of domestic consumption, the circle is also ever decreasing.' In small towns and on farms, kerosene, gasoline and wood are largely utilized for cooking. For the past four years, along any country road, it is a common occurrence to hear a buzz-saw cutting old fence posts or timbers taken from creek bottoms. Many thousands of tons of coal are displaced each year through the use of corn and cobs. In larger towns, gas plants have been installed, and many housewives use gas-in communities contiguous to natural gas, that is used for industrial and domestic purposes. The time has gone when industrial and domestic consumers or dealers are satisfied to buy anything that is black-competition among the coal-producing states is keen, and will become more so. Eastern and southern fields are turning out splendidly prepared coals of high quality, and with their lower freight rates to competitive territory, will entirely nullify the use. of our Western coal unless-

Jan 1, 1922

By Parley Potter

GENTLEMEN OF THE COAL MINTING INSTITUTE: I was requested to write an article on mining a short time ago; however, the time has been so short that I have not had time to prepare an article as I would like to have presented it to this body. In writing this article it has not been my intention in making comparison of various mines, to favor one or discredit the other. I hope it will be considered in that light. The coal mining industry as I have seen it in the past, at present and in the future. In years gone by large tracts of coal land could be obtained at a very small cost, and as yet coal land may be purchased at a reasonable price in this country, but I believe the time is near at hand when the methods of mining will have to be changed greatly in this country. Many changes have taken place-in the last few years, some of them have been forced by law, others by the coal operators themselves, after being convinced that the changes made were for their own benefit. During my 20 years in the mines I have seen thousands and thousands of tons of coal lost that could have been saved if proper methods of mining had been used. The Room and Pillar system of mining coal is none. too good at its best ; a certain per cent of the coal is always lost, yet it is about the only system that can be used under certain conditions, but where the Longwall system can be used I believe it is the best system yet introduced. If the Longwall system is used' there is no coal lost. You get it all as you advance with the workings. Some coal operators object to the Longwall system for several reasons, and most of the reasons they advance are not founded on facts. For instance some of them claim it is too expensive. I will admit that the cost per ton is a little higher in Longwall than it is in Room and Pillar as a rule for the amount of coal' mined, but after the Room and Pillar mine is finished as a rule there are thousands of tons of good coal lost, for the simple reason that it cannot be mined at a profit. In many cases if the same mine had been operated on the Longwall system every ton of saleable coal could have been mined at a fair profit, and in the long run would have netted the owner much more money than it did under the Room and Pillar system. The Longwall system has been in operation many years in Europe and especially Great Britain, and is the most approved of systems in many countries at the present time. Millions of tons of coal have been saved by its use in those countries. It is claimed that the Armour Packing Company loses nothing but the squeal of the hog when it is killed, and doesn't allow it to squeal much. Why lose coal if the Longwall system of mining will save it? The Longwall mine is far more easy to ventilate than the Room and Pillar mine; the air has a much less distance to travel for the same amount of working face in Longwall than it has in the Room and Pillar.

Jan 1, 1921

By F. T. Baker

The Primero mine, operated by the Colorado Fuel & Iron Company, is located 17 miles west of Trinidad, Colorado, in Las Animas County. Unusually bad roof conditions, along with heavy side pressure and other conditions causing rapid decay of timbers, all combine to create a very serious timbering problem. The height of the coal averages six feet six inches. It is a heavy coking coal and has a tendency to become easily crushed and broken down in the seam. The seam lies about 35 feet below the sandstone and the intervening formation is composed of loose shaly rock, and as the coal is extracted, the air slackens this rock to such an extent that within 24 hours, roof falls varying from five to fifteen feet in height are likely to occur. Under these conditions it is necessary to use cross bar sets in both rooms and entries, and they must be spaced no further apart than three and one-half foot centers, and be maintained within a distance of three feet of the face. Rooms are spaced on fifty footcenters, and cannot with safety be driven to exceed 14 feet in width, and 200 feet in length. The large pillar must be maintained to protect from side pressure, and the rooms must be driven up and retreated with as quickly as possible to avoid the squeeze caused by the intense side and roof pressure. Best results in extraction have been obtained by driving rooms for only a distance of 150 feet. Under these circumstances, it is readily seen that timbers of small diameters cannot be utilized in timbering any development work of a permanent nature. Entries are driven nine feet wide, and special peeled piling with an average diameter of 12 inches are most commonly used. It, is necessary to use lagging between each set of crossbars . Conditions such as these necessitated an immense expenditure for mine timber. In addition to ordinary seven and eight foot props, we used a yearly average of 65,000 feet of heavy peeled piling, averaging in diameter from 10 inches to 12 inches. Annual expenditures for timber of all classes was in excess of $60,000.00. Timber costs per ton averaged around 29 cents. In view of these exceptionally severe timber conditions at Primero, the company, in 1920, had a survey made with a view of providing some remedy to this problem. A comparison of the life of main entry timber at other bituminous mines was made, and an average life of four years was established. The actual data collected at Primero indicated an average of less than two years in the manway or "return" airways, and up to five years on the haulageways or "intake" airways. While some of this timber will stand up for a much longer period than this, a close inspection will reveal in most cases that its period of usefulness is spent. It is very essential when discussing the life of timber, especially that used on, main haulageways and aircourses, that a distinction be made between the point of service, that is, the point where it is sound, serviceable and able to carry weight, and the point of breakdown or failure, where it is no longer sound and able to carry weight. In figuring the life of timber, the point of service only should be considered as timber will frequently stand for a considerable length of time when it is entirely decayed and unserviceable. The larger part of the timber used for our permanent work was Alpine Fir, or what is locally termed Red Spruce, and the supply of this I is gradually becoming depleted and has to be obtained at a point so distant

Jan 1, 1926