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Jan 1, 1996

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Jan 1, 1997

By D. J. Griffiths

Beyond doubt it is practically impossible to eliminate all chances of accidents from falls. Mother Earth is not going to give up her treasures without some sacrificing on our part. This particular question ranks among the important subjects connected with coal-mining, and has been given less attention as a factor of life- and limb-destroyer than any other cause. The single fatalities which happen create very little attention; nevertheless, when counted up at the end of the year, they outnumber the unfortunate ones that are mowed down by the wholesale by mine explosions. Fire-damp and coal dust were often considered the greatest evils in coal-mining. All records, however, prove this conclusion to be wrong. The second annual report of the Bureau of Mines gives the loss of life caused by falls of coal and roof in 1910 as 1,310, and in 1911 as 1,321. The reports of Pennsylvania mine inspectors for a period of thirty-three years show that 59.38 per cent of all the accidents underground were caused by falls of roof and coal. Also, the Bureau of Mines shows in its last issue on fatalities that accidents from fall of roof and coal killed more men than any other two causes combined, and that they account for more than half of the deaths under- ground. It seems we are getting too accustomed, taking too many things for granted, running too many risks, trusting too much for the best, and preparing too little for the worst. We must remove the cause; then the effects will cease. However, I can see that a better day is here. The main damaging factors underground are falls of roof and sides. A bad roof is tender and lacks the adhesive qualities to sustain its own weight over comparatively small areas. A roof of any character which is frequently penetrated by well-defined slips and cleats, is characterized as a treacherous roof. The carelessness of men has been one of the main causes of most of the accidents in mining as well as in any other industries. Three Grades of Miners Miners can be classified into three distinct grades, to-wit: the experienced and careful, the experienced and reckless, and the inexperienced. The accidents which the first class usually meet with occur through the carelessness of their co-workers, as well as through accidents which are termed unforeseen, such as falling roof between timbers, and between the timbers and the face of the coal. This may have 'previously given evidence of being absolutely sound and safe, but be released by invisible slips or by sudden outburst of occluded gases in large quantities, as we term big blowers or feeders,

Jan 1, 1913

[Participating Scholarship Colleges and Universities 144 Andalex Resources, Inc 91 Behre Dolbear & Company, Inc 93 Canyon Fuel Company, LLC 92 Big Sky Coal Company 114 Commercial Testing & Engineering Company 96 Continental Conveyor & Equipment Co 97 Copper Mountain Resort 108 Cove Shoe Co., Inc 110, 111]

Jan 1, 1999

The ninth annual Mine Rescue Evaluation was held in conjunction with the RMCMI 2000 convention at the Sheraton Tamarron Resort, Durango, Colorado June 25 thru 27. The purpose of the mine rescue evaluation program is to provide an opportunity for mine rescue teams to learn new skills and improve their existing ones in a non-competitive environment. Several staged "disaster" scenarios were [ ] held where the teams are called upon to exhibit their life saving abilities. The evaluators meanwhile are offering suggestions, both verbal and written, to help the teams better understand the situations presented them. This non-competitive environment allows the teams to work together and share their knowledge with fellow mine rescue teams providing everyone with a positive learning experience. Mine Rescue Chairman Bill Balaz was in charge of coordinating the events. Seven teams consisting of seven to ten members each (totaling 63 members) participated in the two-day event. Each team was required to respond to three different real-life scenarios plus a written general knowledge test daily. This year's four professional evaluators included Art Saenz (Hazardous Materials) of Western Envi¬ronmental Associates; Guy Horton (Ropes), Guy Horton Rope Rescue; Mary Bailey (Medical), MBA Training and Ron Lauer (Confined Space) also lassos Western Environmental Associates. They cash prov- [ ] ided three different challenging mock situations per day per team. The teams had no prior knowledge of what the scenarios would be as details were provided only as they arrived. Ten volunteer victims added much drama and excitement to the event. Their realistic enactments, complete with false blood makeup and severed limbs, made for some very tense scenarios. The Mine Rescue Teams participating this year were BHP LaPlata, BHP Navajo, BHP San Juan, all from Farmington, New Mexico; Bridger Coal Co., Rock Springs, Wyoming; Sabine Mining, Longview, Texas; Solvay Minerals, Green River, Wyoming and Western Energy Co., Colstrip, Montana. Many new [ ] friendships were made and much knowledge shared. A swap meet was held Saturday afternoon for the teams to exchange miscellaneous equipment, hats, shirts, etc. The teams were asked to evaluate the program and the evaluators. Then responded with many positive suggestions that will help improve the upcoming events in the years to come. Culmination of the Mine Rescue program was a Tuesday morning awards breakfast where the teams were presented with plaques. The participating victims and evaluators were also commended for their outstanding efforts. Sponsors for the Mine Rescue program were Big Sky Coal Company, CMC Rescue, Magnum Metals, Inc., and Rocky Mountain Electric. Many hours of volunteer time and effort from various family members of participants helped make the 2000 event a huge success.

Jan 1, 2000

The seventh Annual RMCMI Mine Rescue Evaluation was held during the 1998 Institute convention at the Silvertree Hotel, in Snowmass Village, Colorado. The Mine Rescue committee, co-chaired by Becki Boam and Elliott Tsosie, is one of 18 committees of the Institute. In 1998 a record number of 10 teams participated in the program. The teams were from the four western states of Montana, New Mexico, Texas and Wyoming and were comprised of about eight members each. Teams participating were BHP-La Plata Mine, BHP-Navajo Mine, BHP-San Juan Mine, all from Farmington, New Mexico; Bridger Coal Company, Rock Springs, Wyoming; General Chemical, Green River, Wyoming; Jacobs Ranch Mine, Gillette, Wyoming; Powder River Coal Company-North Antelope/Rochelle, Gillette, Wyoming; Sabine Mining, Hallsville, Texas; Solvay Minerals, Green River Wyoming, and Western Energy-Colstrip, Montana. The professional evaluators provided challenging scenarios for over 90 participants and many observers. The evaluators were: Art Saenz and Tom Bass of Western Environmental Associates, Keith Mitchell and Jim Jennings of Emergency Services Detail; Mary Bailey of Mary Bailey Associates; and John Peleaux of Innovative Access. Teams are not given advance warning of what the problem will entail. They are provided the necessary details when they arrive at the scenario location and work to resolve the problem in an effective and efficient manner. [ ] Seven participants made up each team with an . eighth member as an alternate. Team trainers and other mine personnel traveled with the team from scenario to scenario providing support and encouragement. The teams were presented with four scenarios each day, involving High Angle Rescue, Low Angle Rescue/Medical, Hazmat, and Confined Space. All of the victims, except for one, were provided through the cooperative efforts of the Snowmass Fire Department, who also assisted with providing several evaluators. Snowmass Fire Department is to be commended for providing over 20 victims/evaluators each day to facilitate the evaluations. Training sessions were held Friday afternoon and Saturday evening to help the teams prepare for the scenarios. A swap meet was held Friday evening for teams to trade hats, shirts, belt buckles, stickers, etc. All mine rescue participants and spouses and registered families attended the Bar-B-Q on Sunday evening followed by an adult dance. [ ] Front row: Ray Blaisdell, Solvay; Gary Rasmussen, General Chemical; Spencer Thompson, Sabine; Jack Ervin, Western Energy. Back Row: Ken Kellywood, BHP Navajo; Jonathan Sorrell, BHP LaPlata; Elton Stanton, Jacobs Ranch; Travis Roy, Powder River Coal; Ron Neff, BHP San Juan; Steve Whaley, Bridger. Sponsors who contributed to the 1998 program financially were: Blue Mountain Energy, (Deserado Mine); Flanders Electric Motor Service, Inc.; Rocky Mountain Electric Motors, L.S.; and Western Environmental Associates. Glass trophy cups, with an etching of a Mine Rescue figure and the RMCMI Logo on cherry wood bases, were presented to the 10 team captains at the Monday Mine Rescue Awards Breakfast. Eight of the ten teams had a proficiency level of 3 and 2 teams achieved a proficiency level of 2.

Jan 1, 1998

By I. M. Charles

Mr. Chairman and Gentlemen: At the request of our Secretary, Mr. Shubart, I am pleased to present the following brief discussion of the Alamo Washery. In order to insure an excellent and uniform preparation of nut coal, the Alamo Coal Company erected last year a modern washery at a cost of about $50,000, in which, since the completion last December, all of the nut coal shipped from the Alamo Mine, has been washed. In part of the workings of the Alamo Mine, the coal is overlaid by a lenticular strata of slate, which invariably falls when the coal is shot down and breaks for the most part into fragments of such size as pass through three-inch round perforations, and are retained on plates having one and a fourth inch round holes with the nut coal. This "draw slate" comprises the principal impurity in the Alamo coal, and to remove it, some bone and a few small fragments of sandstone from the roof and floor, the washery was designed and erected. The few impurities contained in the lamp are readily re-

Jan 1, 1926

The first Mine Rescue Performance Evaluation for mine rescue teams was held just prior to the 1992 RMCMI convention meeting schedule on June 27 and 28. Six teams took part in this year's evaluation; Decker Coal, Decker, Montana; BHP Minerals' White Team and BHP Minerals' Purple Team, both of Aztec, New Mexico; Kerr McGee Coal Corporation, Jacob's Ranch Mine, Gillette, Wyoming; The Coteau Properties Company, Freedom Mine, Beulah, North Dakota and The Falkirk Mining Company, Falkirk Mine, Underwood, North Dakota. This was the first mine rescue evaluation program developed to measure a unit's proficiency in their skills rather than emphasis on a ranking order of teams. The objectives for the evaluation were to promote learning and to evaluate the current level of experience of the attending rescue units. The priority goal for this evaluation was to recognize current rescue skills, knowledge and abilities of each team participating. In doing this, each team is provided with individual evaluations and a path for improvement as needed. [ ] Realistic industrial related scenarios, closely simulating the stress of actual rescue incidents, was provided by members of the Hermosa Cliffs Colorado Fire Department under the direction of Dan Noonan, Fire Chief. On Saturday, June 27, five rescue scenarios were presented for each team to complete and on Sunday three of a more difficult nature were encountered by each team. On the final day of the RMCMI convention two of the teams performed rescue demonstra¬tions. Onlookers were afforded the opportunity to view the teams in action as they simulated actual rescue operations. The value and importance of mine rescue teams such as those participating in this year's Rescue Team Performance Evaluation are very evident as in many cases they are the only rescue personnel and medical staff on the work site in case of an emergency. Most of these persons are volunteers who spend many hours studying, practicing and perfecting their expertise in the lifesaving techniques needed in the event of a mine emergency. At the same time, they are very qualified coal miners who perform their respective duties at their mine locations, Their dedication to gaining the most knowledge they can get to handle these life and death situations is evident in their participation in evaluations such as this one. [ ] If a highly educational, informative, sharing of knowledge and expertise, while at the same time providing a very enjoyable experience, deems this evaluation a success ... the Rescue Team Performance Evaluation held during the RMCMI Convention at Tamarron this year was certainly a SUCCESS!! It is hoped that you can all enjoy this same experience with us next year! Linda G. Ash The Falkirk Mining Company [ ]

Jan 1, 1992

Jan 1, 1947

The fifth Annual RMCMI Mine Rescue Evaluation was held June 29 through July 2 in conjunction with the 92nd RMCMI Convention. Eight teams from four states participated. They were: BHP La Plata Mine NM Capt. Jonathon Sorrell BHP Navajo Mine NM Capt. Ron Miller BHP San Juan Mine NM Capt. Albert Nelson Bridger Coal Company WY Capt. Ted Laughlin Coteau Properties Co ND Capt. Terry Davis Kerr-McGee Coal Corp WY Capt. Elvin Stanton Sabine Mining Company TX Capt. Spencer Thompson Solvay Minerals WY Capt. Ray Blaisdell Activities started with a Rope Rescue class taught by John Peleaux, from Innovative Access, at 1:00 p.m. on Saturday. The Mine Rescue Reception, Team Meeting, and Equipment Inspection was held Saturday evening. All participants received a T-shirt and cap. The Mine Rescue Evaluation started Sunday morning and ran until it was rained out around 3:00 p.m. There was a team swap meet Sunday evening at which teams bought extra caps and shirts. They also traded with other teams. [ ] The Evaluation resumed Monday morning and ran until mid-afternoon. The Evaluation was made up of seven stations. There were six scenarios and a written test. Teams were also challenged by a 14-foot confidence course wall to get their team over. The teams were evaluated by: Jack Knight Champion International, Pensacola, FL Becki Pickert Colorado Northwestern Community College, Craig, CO John Peleaux Innovative Access, Evergreen, CO Lynn Busskohl Kerr-McGee Coal Corp., Gillette, WY Lenny Altenburg Kerr-McGee Coal Corp., Gillette, WY Elvin Stanton Kerr-McGee Coal Corp., Gillette, WY Clarence Baker Kerr-McGee Coal Corp., Gillette, WY The victims for the scenarios were from the Kerr-McGee Mine Rescue-Team. They were: Dana Cooper, Doland Zink, Suzanne Ott, Mike Szuma, and Craig Moore. Also helping as a victim was Candy Cobb from Casper, WY. [ ] The program concluded Tuesday morning with the Awards Breakfast. A medical kit, donated by Strategic Supply, was given to the Solvay Minerals Team for the fastest time over the confidence wall. Engraved stone awards were given to the teams indicating the rating they achieved. Four teams received Level Ill (The highest rating) and three received Level II. The Kerr-McGee team also received an award for helping put on the evaluation. Additional stones were presented to Jack Knight, John Peleaux, Becki Pickert, and RMCMI President. Marcie Greenberg. The current plans for the 1997 Mine Rescue program are that Jim Andrews with Colowyo Coal will assume the chairmanship. Goals for next year are to increase funding and participation by establishing sub-committees or task groups. With the chair located in Colorado, coordination of the evaluation should be easier. Comments from all the teams were positive and they intend to return next year at Steamboat Springs. [ ]

Jan 1, 1996

By C. H. Trik

Any article or discussion on the ventilation of Working Faces under different systems of concentrated mining is of little value to any practical man unless based upon facts gleaned from actual experience, and empirical data on this subject is, to say the least mighty scarce. Of this one thing, however, you can rest assured, the old cry of "no air at the working faces" will have become a thing of the past. No longer will we hear of some operator who has been too eager to get out the coal and who has lost sight of everything else in his mad dash for production, digging himself shut until his airways are mere pin- points and his air current a feeble thing, too weak to combat the high resistance of his restricted mine. A mine operating under one or more of the various systems of concentrated mining should always have plenty of air, for in concentrated mining the tendency is toward greatly reduced mine resistances due to increased sectional areas. It can readily be seen that the tendency is to large, wide areas across the panel and where this is true large volumes and low gauges are the rule, unless inordinate restriction is encountered in the permanent airways, and no operator, far sighted or progressive enough to adopt this system of mining when his conditions permit, would ever allow his main airways both intake and return, to be anything but model courses. As a matter of .fact, we are likely to encounter the opposite of what is usually the case in most mines to day. We are apt to find the air at the working faces sluggish due to the large areas of passage rather than to high resistance. This is combated in. various ways which will be discussed further along in this article. Those companies, of which we have knowledge in this country who, to- day are using any of the new systems of mining, seem to proceed alike in the general method of developing their acreage. Let us assume, for this discussion, the Utah Colorado Coal Corporation is going to open a mine under the new system and their conditions are such as to permit their adopting the simple block system, each face served by a separate machine, each entry having its conveyor to the cars. After the permanent haulage and airways are driven "narrow work" starts to shape the blocks. We are not interested in the length of these "conveyor headings" since we do not need to drive breakthroughs nor build stoppings for ventilation until we have reached their end when we connect them together. We have two methods of sending air to the face of these dead ends. We can laboriously and expeilsively install brattice cloth, as we go, or we can use a small auxiliary blower with canvas tubing to the face. Indeed I may say that one of the great difficulties encountered under the new systems is in the ventilation of these narrow faces. After they have been connected and an air circuit or current established, ventilation becomes plain sailing until the block is worked out. The auxiliary blower when used with flexible canvas tubing, has been found to be the ideal answer to the question of how to ventilate the headings which are anywhere from 100 to 1,000 feet long. These small blowers when properly used, can go a very long way to assist in further reducing the cost of production already assured by the new method of mining. Right angle bends are made by the tubing manufacturers to enable the fan to sit in the fresh air current, yet out of the way of operations and any recirculation is positively avoided by blowing the air around the corner to the face.

Jan 1, 1926

PRESIDENT WHITESIDE: If the chair may be pardoned, he would like to say he knows something of the work of this committee, and I assure you that they have all worked faithfully and hard, holding meetings at least every other day, and sometimes oftener, hustling money and going through all the different work necessary to bring about and to make a successful occasion of this kind, and I-who really acted as an outsider and viewed their work-was certainly appreciative of their efforts, and I know you would have been had you been able to see how hard they all worked. One of the sad things in life always is when one becomes a "has-been." I have been more or less active in the work of the Institute ever since its in¬ception. Just why the high honor of President was conferred upon me I have never been able to fathom, but my time is about over and I am about to join the "has-beens," and while the position naturally has entailed a certain amount of work, it has been very pleasant work, and when one has the hearty co-operation of his fellow workers, such work is always a pleasure. It is, therefore, with a certain amount of regret that I lay down the gavel and take it up again to present to my successor; but in doing so, I wish to thank you, one and all, for your very hearty help and co-operation, and to wish my successor, Mr. George B. Pryde, all the possible success that can be his. Mr. Pryde. (Applause.) MR. PRYDE: I will make no extended speech at this time. I think possibly the next year I will have enough opportunity to do that; but I had a letter from my friend, Murphy, before this meeting, and he thought we were going to have a very good meeting; but I don't know the motive behind his letter. (Laughter.) I remember the story about the Scotchman who went to see the doctor, and the doctor said: "Sandy, you drink any?" "Oh, yes." "Well," he says, "you have got to cut that out. Do you smoke?" "Oh, yes; I smoke a great deal." "Well, you will have to cut that out also." And Sandy picked up his hat and started for the door. "Wait a minute, Sandy; you haven't paid me for my advice." "Yes, but I am not going to take your advice." (Laughter.) But I am deeply appreciative of the honor you have conferred upon me, electing me to be head of this Institute for the next year. I have belonged to this Institute, I should say, ever since it has been organized. This present session especially has been a very good session. As I look back over the different meetings, I think this one stands out among all the others in the papers presented and the spirit of co-operation that prevailed among the members here, and I am not going to ask your co-operation during the year; I am sure I will get it from all of you. I want to thank you for the honor conferred upon me. (Applause.) MR. WHITESIDE: The retiring President did not quite follow the reading of the by-laws, I think, in which it says that immediately after the election of a new President, the new President shall assume office, and I got so busy I forgot all about that. The committee which the chair decided to appoint is as follows. This is to formulate safety rules: For Utah, John Crawford, William Littlejohn; for Wyoming, Peter Patterson, Glen Knox; for New Mexico, William Risdon, Allan French; for Colorado, James Dalrymple, J. C. Roberts; and last and surely not least, as chairman of the committee, Mr. George B. Pryde. (Mr. Pryde later appointed D. Harrington as a member-at-large.) C. M. GODDARD: Mr. Chairman, we all realize that in a gaseous mine the application of, safety measures transcends everything else. Machinery is installed 100 per cent safe, as they might say, to take care of any condition

Jan 1, 1923

By Scott Dupont

Due to the scarcity of miners, and the necessity of decreasing the cost of mining, the Phelps-Dodge Corporation, Stag Canon Branch, at Dawson, [ ] New Mexico, decided to try, by various methods of mining, to increase the tonnage of coal mined per man, per day. With this in view, they first tried mining on a 250-foot face, maintaining the track at the face and using six to eight men shovel- [ ] ling. These men were able to aver age from ten to twelve tons each per, day when they were loading, but with

Jan 1, 1926

The 71st Regular Meeting of the Rocky Mountain Coal Mining Institute convened at the Steamboat Village Inn, Steamboat Springs, Colorado, and was in session at 10:00 a.m. The session was called to order by William W. Grant, Assistant to Manager of Navajo Mine, Utah International, Inc., Fruitland, New Mexico. Mr. Grant was delegated to open the meeting due to the untimely death of Past President A. F. Geiger. Mr. Grant introduced President Roy Coulson, President and Director of the Kemmerer and Gunn-Quealy Coal Companies, Frontier, Wymoing. His biography follows: Jan. 7, 1922 Born to Jean and Joseph Coulson, Ernest, Pennsylvania 1940 Graduated - Indiana High School, Indiana, Pennsylvania

Jan 1, 1975

By C. A. Allen

When the writers were asked to prepare a paper on this subject for this meeting of the Institute there was some question in our minds as to what to say that would be of interest to the members. You all know that Utah has some wonderful seams of good coal, on which have been opened some of the most modern mines in the United States, and that her coal operators have been putting forth many efforts to reduce losses due to accidents as well as disease. While I believe that the physical condition of Utah's mines is as good as in any other state we are not unaware of the fact that a great deal can still be done and we are always willing to frankly discuss the accident situation in the state. Dr. Murray has assembled some interesting figures showing the monetary loss due to accidents and disease which I will will proceed to give you to show the necessity of continued efforts in welfare work regardless of humane considerations.

Jan 1, 1922

Jan 1, 1986

Jan 1, 1927

The Fifty-ninth Regular Meeting of the Rocky Mountain Coal Mining Institute convening at the Hotel Colorado in Glenwood Springs, Colorado, was declared in session at 10:30 a.m., by Past President Charles M. "Dock" Schloss, Schloss and Shubart, Inc., Denver, Colorado. Dock introduced Mike Zakotnik, Jr., General Superintendent, The Kemmerer Coal Company, Frontier, Wyoming, President of the Institute. His introduction of President Zakotnik follows: Fellow Members, including our charming and beloved secretary, Gussie Whiteside, and our lovely Mrs. Cerise: It is now the appointed time to convene the Fifty-ninth Regular Meeting of the Rocky Mountain Coal Mining Institute which I now declare in session. At our last meeting we elected Mike Zakotnik, Jr., President, and lie has served the Institute intelligently and industriously since his election.

Jan 1, 1963

By David Scrymgeour

All low cost coal has been mined. Engineers are searching for a safe and effective way to mine coal seams' deep within the earth. The most modern of these is the RL, an acronym for Robotic Labor. Mining robots are programmed to do specific jobs but can think on their own during an emergency. MR's, or mining robots, usually have a same basic shape. A torso is mounted on treads. Designers chose treads because it gives the robot a great deal of mobility. The torso has two arms. One arm is equipped with a human hand. The other has a human-like hand. Mining is done underground. A small robot goes around punching holes in the coal. A small charge is inserted in the hole. The MR ignites the charge with his laser. It explodes after three minutes. The MR returns to the station where his battery is recharged. Mobile cement barricades are moved between the blasting area and other working MR's. After the charge explodes the barricades are moved to another area. The MR returns and cuts the coal chunks into pieces. Another robot comes and loads the coal and carries it to the loading bin. From there it is taken to the surface where it is weighed and shipped. The whole process was done by robots. Humans just supervise but help in an emergency or malfunction.

Jan 1, 1987

By F. A. Young

A description of the dry process coal cleaning plant which has been built and operated by St. Louis, Rocky Mountain & Pacific Company at their mine at Brilliant, New Mexico, should at first be a description of the special machinery which is used in this process. This equipment consists primarily of screens for sizing the coal into six different sizes all smaller than 1 ½ inch and the pneumatic machines for cleaning each size. These machines are patented and were manufactured by Sutton, Steele & Steele of Dallas, Texas, until a few months ago when all rights of sale were acquired by the American Coal Cleaning Corporation. These screens, a plan of which is now before you, are called anti-gravity screens because the coal travels up hill. The screens which we have at Brilliant are 3 feet wide and 7 feet 4 inches long. They consist of one upper deck which slopes upward in the direction of the flow of the coal, at an angle of 12 degrees. This deck is a wire mesh screen the size of which determines the size of oversize from that screen. Under this is a lower deck with a slope of 7 degrees. This is a solid bottom and is for advancing the undersize to the next screen. On account of the difference in pitch of these decks they are about 11 inches apart at the discharge end, which allows the oversize to be taken off at one or both sides and the undersize to fall only a few inches on to the following screen. This is perhaps the most valuable point in this patent as it allows any number of screens to be placed on a-level floor, tandem in a battery without elevating or rehandling the coal in any way. The length of the screens corresponds to the proper spacing of the cleaning tables which naturally operate on the floor below. I know of no other screen which can be operated in this way. The coal is caused to travel by a reciprocating motion. A shaft as shown near the center of the screen box and under it has an eccentric at each side of the screen with connecting rods attached near the rear of the screen box. The screen box is attached to the stationary under frame by means of cast iron plates extending full width across the screen box. These are placed at an angle as shown so that the forward motion of the eccentrics causes the screen box to rise as it moves forward and the backward motion drops the screen from under the coal thereby causing it to advance. The coal advancing over the screen cloth in this rolling or jumping motion causes very perfect sizing. It should be stated here that very accurate sizing is necessary for the success of the cleaning tables. The stroke is 1 inch and the speed 350 revolutions per minute. In describing the pneumatic cleaning table, I place before you a plan furnished by the makers. The basic principle is that if a film of coal one to two inches thick and all of nearly the same size pieces is placed on a flat perforated surface and a large volume of air passed through it, the lighter particles which are the clean coal will soon find their way to the top of the film, while the heavier particles, or waste, will remain on the bottom. The machine is built with a perforated deck about 4 feet square under which is an air chamber and air duct connecting with a fan which is part of the machine. The deck of the table has a reciprocating motion the same as the screens already described, which tends to advance the product up a slight slope which is adjustable. The coal is fed at one corner of the table as shown and the deck slopes also away from the feed and at right angles to the reciprocating motion. On top of the perforated deck are riffles about 2 inches apart and running parallel to the line of reciprocating motion. These riffles are about 1/2 inch high at the fan and feed side of the table and taper to nothing at the far side. When the coal is fed on to the table, the air through the perforations tends to raise it 'and roll it over these riffles down the slope toward the clean coal discharge. The heavier particles do not get over the riffles so rapidly and the reciprocating motion is constantly pushing them

Jan 1, 1923