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By G Brudek, P Elestedt

Schalker Eisenhütte und Maschinenfabrik GmbH, Nordic Minesteel Technologies and Bombardier Transportation have developed an evaluation tool that considers the main cost drivers of the rail, truck and conveyor haulage systems on the market today. In almost every circumstance, the advantages of a haulage solution are clear. A haulage system is outlined that is fully automated, including driverless operation, and that provides increased tonnage, safety and equipment life and reduced maintenance downtime. The haulage system has been implemented by a number of companies, including Codelco, LKAB and Freeport’s Grasberg mine. CITATION:Brudek, G, Elliott, R P and Elestedt, P, 2016. Moving mORE for less, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 535–542 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By Wang Zuoyu

The manuscript of this paper was not available for publication when the Proceedings went to press. Should the author elect, he may distribute copies to the time of the Symposium.

Jan 1, 1986

By S. Ianos, C. Vibert

Type and shape of large dams founded on rock depend upon the expected deformation of their foundation. Their design consequently requires the assessment of the deformability of the rock mass at large scale. Seismic refraction, laboratory tests on rock samples and empirical formulas can provide an order of magnitude of the deformation modulus, with a limited degree of reliability. Direct in-situ measurement of the deformability of a volume of rock is therefore preferred, which integrate the effect of discontinuities, such as plate loading tests, dilatometric tests, etc. The authors have been compiling results obtained by in-situ deformability tests on a number of dam sites, including the Scarabée (“Petite Sismique”) method. This last method consists in thoroughly analysing the shape of seismic wave forms transmitted through the rock mass. It has been used since now more than 40 years over a large number of dam foundations, and has proved to provide a satisfactory assessment of the static deformation modulus. After comparing the results obtained from different methods on six dam sites, the Authors conclude that their reliability closely depends upon the size of the loading device in relation to the spacing of the discontinuities. Attempts to correlate results from different types of in-situ loading tests reveal difficult, because closely depending upon local geotechnical conditions at test location. Plate jacking tests appear to be the most reliable, because involving a relatively large volume of rock. On the other hand, the Scarabée method (“Petite Sismique”) allows a rapid assessment of the deformation characteristics of the rock mass at large scale, and has been found to provide values generally in agreement with those from plate loading tests, while dilatometric or flat-jack tests were found too dependent upon local conditions. The Authors conclude that preference should be given first to the Scarabée method, which uses light equipment and is quickly performed, together with an accurate geological and geotechnical assessment for interpretation. In a second stage, Scarabée shall be complemented by adequately performed plate jacking tests in selected locations, in order to cross-check results and refine the assessment. The general accordance between the results of the two methods, which both can integrate anisotropy of rock masses, justifies this statement.

Jan 1, 2015

By Felipe Henríquez, Daniel Silva

"Traditionally, the implementation of an automated advanced process controller in any mineral processing complex is a challenge, mainly due to the quality of resources and technologies required, the uniqueness of each control solution and the uncertainty of the engineering hours needed to complete the task. Thus, the use of advanced and proven control technology becomes a key factor when deploying the control strategy. However, success would still not be possible without the presence of common sense, process knowledge and fundamental process data. Minera Los Pelambres, taking advantage of such factors and its accumulated process experience, implemented a novel and successful combination of MPC (Multivariable Predictive Control) and advanced control for secondary grinding and regrinding stages at its copper concentrator plant. In both cases, the control objectives are: being capable of processing a variable feed from the upstream process while at the same time avoiding to become a process bottle neck and yet, maintaining an adequate product quality (in terms of size distribution) to the process downstream. Additionally, for the case of the vertical regrinding mill (vertimill), the control system should also be capable of keeping an adequate circulation load and making an efficient use of the available grinding power. In either case, extending hidrocyclones availability while maintaining their performance is a must, since both factors are required for process and maintenance purposes. Thus, the process control problem becomes one with a multi-variable type of process with multiple control objectives to satisfy simultaneously. In trying to solve it, many mineral processing operations have implemented basic or conventional control or even better yet, expert systems. Minera Los Pelambres believes that better and faster results can be achieved using a combination of MPC and advanced control. Such strategy was successfully implemented, reducing considerably process variability while maintaining high throughput and keeping the process well within constraints limits. Their control philosophy, implementation process, main results and their key performance indicators are discussed here."

Jan 1, 2014

Herbert C. Hoover, who became a member of this Institute in 1896 and who is now one of its Vice-Presidents, is the man who in 1914 extended a helping hand to Americans stranded in Europe at the outbreak of the war, and who made it possible for many such travelers to return safely to their homes. When his countrymen no longer needed his services, he turned to the Belgians, whose need of food had been presented to him. Engineers have been among his assistants from the first, and it is because we believe that members of his own profession will still be particularly interested in his work that we thus mention it in the Bulletin. A Minute adopted by the Board of Directors of the Institute, in which the Belgian Kiddies, Ltd., is recommended to the consideration of the members, immediately follows the Proceedings of the Meeting of the Board of Directors. With the thought that members of the Institute may be glad to read Mr. Hoover's own words in regard to his work, we print in full the speech

Jan 3, 1917

By John Fritz

TROUGH it is not a condition of the Award, the fact is that the John Fritz Medal never has been given to an engineer who had not already received one or more similar awards. This "medal for medalists," on the evening of April 20, was presented to Daniel C. Jackling at a special dinner held at the Union League Club in New York. The citation read "For notable industrial achievement in initiating mass production of copper from low-grade ores through the application of engineering principles." The present award recognizes the same accomplishment-the launching and guiding to the port of marvelous success of the Utah Copper Co., first of the so-called "Porphyries"-as did the award of the William Lawrence Saunders Gold Medal by the A.I.M.E. in 1930, and before that the Award of the Gold Medal of the Mining and Metallurgical Society of America in 1926. Following the custom a biography of the Medalist had been published in a small pamphlet as a supplement to the John Fritz Medal Book. T. A. Rickard was the au¬thor of the sketch of Mr. Jackling, an innovation being the placing of a copy of the booklet at the place of each of the diners. The committee in charge of the dinner consisted of two past-presidents: R. E. Tally, of the A.I.M.E., who was chairman; Bancroft Gherardi, of the A.I.E.E.; and Thaddeus Merriman, director of the A. S. C. E., the John Fritz Medal being a joint award of the four societies. Frederick M. Becket, President of the A.I.M.E., as chairman for the occasion, briefly stated the purpose of the dinner. He stressed his satisfaction that the award was symbolic of the cooperative professional activities of the four great national organizations of engineers. He introduced Francis Lee Stuart, past-president of the A.S.C.E. and now chairman of the John Fritz Medal Board of Award. Mr. Stuart outlined the history and purpose of the Medal established in 1902 in memory of John Fritz, of Bethlehem, Pa., one of the great pioneers of America's iron and steel industry, metallurgist, and president of the A.I.M.E. in 1894. Mr. Stuart called the roll of former John Fritz Medalists, three of whom, Ralph Modjeski, J. Waldo Smith, and Ambrose Swasey, were present to do honor to Mr. Jackling. He then introduced George Otis Smith, whose privilege it was to present the Medalist for 1933. Dr. Smith was the senior of the four A.I.M.E. representatives on the Board that last year selected Mr. Jackling for the honor. His speech follows in full.

Jan 1, 1933

MR. McKEEVER: I think we had to start some- where. The proceeds of the beltbuckles and hard hat stickers will certainly be a beginning in a scholarship for some of our young people. And maybe, you know we might even get one of them sometime to go to the University of Oklahoma. A few years ago the luncheon speaker for tomorrow, Brooks Mitchell, got a few of the mine presidents together and we spent a full five hours of just dedicated listening to Carl Terzian. We listened basically on three subjects: how to work with the media, how to work with image, and how to identify with our political systems and those who are in them. I remember that as one of the turning points in my perspective on how our system really works. This gentleman who will be addressing you today, Mr. Terzian, will be conducting about a three-hour session tomorrow. And it's a shame that our other activities will not allow some of the golfers to probably be there. Those of you who can come to the session tomorrow morning will find it most rewarding. A little bit later on we will also have a panel session. And I see all of the panelists are here except for Bob Golten, but I understand that he is registered. We should have a full afternoon session with Charlie and his panel. When we started working on this, we naturally went back to Carl Terzian to give us some guidance. If there is anything wrong with your session, it's my fault because he knows how these should be done and he guided us along the way. One thing that I am sorry, it wasn't his fault necessarily, is that Harry Reasoner will not be with us for lunch tomorrow. Brooks Mitchell is going to make all of the PR he can out of the fact that Harry got scratched and he got in place for him. Brooks gave me one comment along that line. He said, "Do you know what you get when you cross a gorilla with a computer"? Of course I bit on that. He said. "Well, you get a Harry Reasoner." A little over a month ago I was invited out to California to Woodbury University at Carl Terzian's insistence. I happened to be sitting by one of his vice presidents. It was a formal affair. We had to wear tuxedos and everything and Mr.Green was sitting there and he said, "You know," he didn't know who I was at that time, but he said, "You know Carl really didn't want this formal affair. Said he had a couple of friends coming from the coal mining industry and they wouldn't know what to do with tuxedos." So with that Carl, we will start this little session and it's your mike. MR. TERZIAN: Thank you very much Ira. Let me begin by expressing my appreciation to the men and women of the Institute for allowing me to be here. I'm deeply concerned about my reputation, my image and don't want you to get the inference that I am responsible for Ira McKeever's image. Nobody could be responsible for that! But it is a great case in point that we all should be concerned about our images. I guess tomorrow morning from about 8:30. a.m. to about 11:30 a.m. we are going to do a? hopefully, a productive and very pleasant expertence for all of us in this growing field and great interest that people have in the area of image. I happen to be from Los Angeles. I have a national firm which has handled about 600 corporations', over the years through the areas of public relations,' community, civic involvement all built around a strengthening and safe guarding our precious, free enterprise system. And the message that I hope to give you, as you will be eating your lunch today, is really not so much about the image of individuals but as the attitudes built on what Bill Banowsky

Jan 1, 1982

The U.S. Department of Labor?s Mine Safety and Health Administration (MSHA),through its winter alert program, warns U.S. mine operators and miners at underground coal mines of workplace hazards that can arise when the weather turns colder. MSHA records indicate that, historically, most explosions in underground coal mines occur during winter months. ?The changes in weather can increase the risk of fatal accidents,? says David G. Dye, Acting Assistant Secretary of Labor for Mine Safety and Health. ?Each miner and mine operator must take individual responsibility to eliminate the kinds of hazards that can cause fatal accidents in the workplace. Safety is not the other guy?s job?safety begins with you.? In fact, MSHA?s slogan for this year?s campaign is ?Winter Alert Starts Now and Safety Begins with YOU.? This message reminds miners and mine operators of the risks of colder weather and educates them about helping to reduce risks and hazards. ?Safety requires the joint effort of both management and labor,? Dye says. ?Everyone at the mine site must see safety as an individual value and act to ensure a safe working environment.?

Jan 1, 2006

Active and abandoned mine sites can be an irresistible- - and sometimes deadly - - draw for outdoor enthusiasts, particularly children and young adults. Despite repeated warnings, posted signs, and fencing, tragedies involving accidents on active and abandoned mine property continue to make headlines, especially with the arrival of warmer weather and the summer months ahead. Over the last few years, there have been dozens of tragic incidents involving children and adults ventur­ing onto active and abandoned mine property. They include: A 16-year-old youth suffered fatal injuries after his all-terrain vehicle became airborne in an accident at a gravel mine near Albany, New York. A young boy was electrocuted when he contacted a high-voltage power line while sliding down a stockpile at a sand and gravel mine in Grand Island, Nebraska during its off-shift hours.

Jan 1, 1999

By Henry Chajet

Good morning, it is truly an honor to have been invited to speak before you today Before I begin my update on MSHA's activities, I?d Like t o quickly say a few words about the American mining congress and its mission in Washington, AMC is a national trade association representing most of the producers of the nation's metals, nonmetals and coal, we also represent the manufacturers of mining equipment and supplies and the financial and consulting institutions which service the mining industry. It is the diversity of our representation which gives us our greatest strength in our petitioning efforts, the administration and the members of congress know that an AMC position is the result of the careful consideration of a vastly diverse group of mining concerns. Our president, Al Overton, perhaps has the best description of AMC when he speaks of us as "the mining industry's eyes and ears and its collective voice in Washington."

Jan 1, 1981

Good Morning. Thank you for your kind welcome, Lyle and thank you for having me here today. I spoke at the fall meeting of the Utah state RMCMI in Price and it's nice to be invited back. I can see by the program that you have two great days of interesting and informative meetings, including the mine rescue team exhibition and the safety recognition award presentations. As you all know, I am here standing in for Dave Lauriski, who is in China with Secretary of Labor Chao. As you also know, Utah is near and dear to his heart - and so is the Rocky Mountain Coal Mining Institute. I want to assure you Dave would be here if it were at all possible. But it is my good fortune that I could come in his place. We have made great progress as an Agency thanks to the hard work and dedication of MSHA's employees. But we are always looking for new ways to solve problems and continue to send more miners home safe and healthy every day. And we have been working on some great ways to do that, including thinking strategically. During my presentation today I'm going to talk about where the Agency is in terms of our transformation to the MSHA of the 21st century, a little bit about how we got to be where we are, and then describe our roadmap to the future state. And I'm going to focus on the significance of our plan and the planning process to demonstrate the implication for the mining industry. Former President Dwight Eisenhower once said, "In preparing for battle I have always found that plans are useless, but planning is indispensable." Now I do like Ike, but I would have to take exception to the first part of the sentence. I have found plans and the planning process to be indispensable - the plan to give me a roadmap to my goal, and the process to focus me on the steps I must take to get there. We all know that having a strategic plan makes the difference between success and failure. We've seen it time and time again, in business, in our lives - and in government: Having a strategic plan is crucial to success. And the process of making the strategic plan is crucial to its success. Putting together a workable strategic plan - a good roadmap - that will successfully lead you to your goals requires a thorough, careful process that takes into account each factor that you may encounter along your way to success, as well as those with whom you will travel. In order to talk about our current plan I want to take you back to three years ago, when Dave Lauriski went to Washington to lead MSHA. He knew that change was in the air. Dave was confirmed as Assistant Secretary with 30-plus years experience in the coal mining industry, and more than 20 years of experience in dealing with

Jan 1, 2004

By P Radulovic, V Lawson, M Muller, J Wallace

The Mount Isa Copper Concentrator was commissioned in 1973. Since commissioning some significant upgrades have been undertaken such as: • the replacement of the rod mill/ball mill circuit with AG mills and the subsequent conversion of the AG mills to SAG Mills. • the introduction of columns as retreat cleaners in 1987, then reallocated as prefloat cleaners in 1994 and rougher cleaners in 1996.• the repurposing of some rougher capacity to preflotation roughing to remove carbonaceous pyrite and talc in 1994.• the introduction of a Jameson Cell for preflotation cleaning in 2000. • the expansion of the rougher and cleaner circuits in 2002 with the inclusion of 6 x 100 m3 Wemco cells to replace the capacity lost to preflotation and to increase residence time and improve recovery. In 2013 work commenced to replace the cleaner circuit after 40 years of operation. The new cleaner circuit, consisting of 3 x B5400/18 Jameson Cells, replaced the rougher cleaner columns, cleaners, recleaners and retreat Agitair banks and was commissioned in Sep 2015. The new cleaner circuit was configured as two cells in series producing the final concentrate and a cleaner scavenger cell to supplement the existing Wemco cleaner scavenger cells. The performance of the new circuit is discussed.CITATION:Lawson, V, Muller, M, Radulovic, P and Wallace, J, 2017. Mt Isa copper concentrator cleaner circuit redesign, in Proceedings MetPlant 2017, pp 279–287 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 11, 2017

By P York

The study commenced in October 2012, to understand the basic ecology of the spotted-tailed quoll (Dasyurus maculatus) and to confirm whether the species utilise previously mined land on the Mt Owen mine site that was rehabilitated in 1996 to 2011, as part of their home range. The spotted-tailed quoll is a widely distributed marsupial carnivore that is listed as rare or threatened in every state in which it occurs. The species is a forest-dependent marsupial carnivore that occupies a wide range of habitat types (Long and Nelson, 2004).The first part of the study involved trapping a spotted-tailed quoll and fitting the individual with a combined global positioning system / ultra high frequency (GPS/UHF) radio-transmitter collar (Telemetry Solution – Quantum 4000E). The benefit of the GPS/UHF collar is that it records locations (or fixes) at intervals programmed by the user. The UHF component allows the researcher to locate the individual at a frequent interval, and the Quantum 4000E also has a remote download function, enabling the GPS data stored in the collar to be wirelessly transmitted between the collar and researcher. The benefit of this new technology is that the animal does not need to be repeatedly captured to retrieve the GPS data.Daytime searches are also undertaken using the UHF receiver to locate the individual and locations of daytime denning and latrine sites. The location of each den site is recorded using a hand-held GPS. Data downloaded from the GPS collar is then imported and mapped using computer software program ARCGIS (geographic information system), to overlay the data points onto aerial photography.Results demonstrate that threatened species will utilise rehabilitation areas post mining. The data presented will be used to develop a greater understanding of threatened species ecology in and around rehabilitated areas, which will assist in the planning and design of native forest rehabilitation areas.CITATION:York, P, 2014. Mt Owen Mine spotted-tailed quoll study, in Proceedings Life-of-Mine 2014 , pp 591–596 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 16, 2014

By Nidagal V

This paper discusses the dewatering strategy adopted and the considerations and procedures required to incorporate a dewaterinq scheme into the Mt Whaleback mining operation. It concludes that in pit pre-dewaterinq has successfully allowed mining to progress below the standing water level with the minimum of disruption or radical change to the mining method. It is recognised however, that dewatering is not a static activity and there is a requirement for ongoing investigations and development. Pre-dewatering commenced in October, 1984. Purpose designed pumping trailers have been employed to minimise the loss of pump availability resulting from the frequent. need to remove and reinstall pumps when close vicinity blasts occur. To July, 1986, some 0.5 Mm' of groundwater had been pumped from the unconfined orebody aquifer. Mining has progressed to some 20 m below the standing water level without. any undue water associated problems. Ultimately, it is ,cheduled to extend some 300 in below the original water level in the West Pit. With the development of an increasing area of the mine below the standing water level, the influence of seasonal high intensity rainfall events, which had previously caused little concern, now need to be addressed. Pumping equipment has been designed to evacuate storm water at a rate consistent with mine production Considerations.

Jan 1, 1986

By P Wilson

The Mt. Wright Underground Mine is located near the town of Ravenswood in North Queensland and is operated by Carpentaria Gold – a wholly owned subsidiary of Resolute Mining Limited. The establishment of the world’s first Sub Level Shrinkage (SLS) mine from a tradition Sub Level Open Stoping operation has proven to be a geotechnical challenge which has required tailored solutions to overcome unique issues. This paper will be broken into two distinct sections that will outline: a brief overview of the mining method and how the SLS method was chosen; and how the SLS is managed and key geotechnical learnings. The story of the world’s first SLS originated from the need of a bulk mining method to ensure the viability of Mt. Wright into the future. Traditional bulk mining methods such as; Block or Sublevel Caving were originally ruled out due to the low natural ‘cavability’ of the orebody and the proximity of the orebody to existing major infrastructure (Decline, Ventilation Rises and Egresses). The first section of the paper will outline the key geotechnical information that helped decide the SLS method in addition to how continuous backfill influenced the design. The second section is intended to address issues that the geotechnical engineers encountered since the inception of the SLS. The feature topic of this section is mining induced stress. Like most bulk mining methods, Mt. Wright had success when the production front was running parallel to the stress (production front being ‘shadowed’ from the stress). This was until a design change, forced by a splitting ore body resulted in this shadowing effect becoming harder to achieve. As a result, rehabilitation and production hole re-drilling become a regular occurrence, which teamed with a strict set of access controls made the production cycle longer and harder to complete. CITATION:Wilson, P, 2018. Mt Wright – geotechnical learnings from a sub level shrink, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 119–132 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

By S Long, D Carnovale, L Louwrens

The Mt Wright underground mine (MTW) is located near the town of Ravenswood in north Queensland and is operated by Carpentaria Gold – a wholly owned subsidiary of Resolute Mining Limited.The Mt Wright mine has gone through many stages, from the conception and implementation of the world first ‘sub-level shrinkage’ stoping (SLS) with continuous fill mining method in 2010, through to steady state production. These have been outlined in detail in papers presented by Mackay (2011) and Mackay, Long and Koen (2014) at previous Underground Operators Conferences.Since the last paper was presented, MTW has experienced significant change in two key areas.The first significant change was the discovery of a previously unknown hazard in the form of flat rilling events (FREs) from closed drawpoints (DPs). These events are believed to be unique to MTW and pose a significant risk to both the safety of personnel and the business as a whole. The paper will discuss this hazard and the evolution of the controls and practices that have been introduced to mitigate the risk posed by the identified hazards. The material involved in these events is extremely dry, fine and hot.The second significant change is an altered stress regime bought on in part by a change in the production front orientation and a general deterioration in ground conditions in some areas of the mine. This has caused some production interruptions at MTW. The second half of the paper will describe the challenges encountered, the mechanisms behind these challenges and the strategies implemented to safely return MTW production to planned levels.It is believed that other operations can learn from the issues mentioned above, and the paper has been written with this in mind.`CITATION:Long, S, Carnovale, D and Louwrens, L, 2017. Mt Wright – managing unique risks, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 295–304 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

By M Nagarajan, S Esen

This paper presents three case studies from three surface coalmines. The first case study is from a coalmine where a dragline operates in 60 m wide and 1 km long strips. Typical overburden height ranges from 30 m to 50 m. The base case blast was modelled using an advanced blasting model (Distinct Motion Code – DMC) to establish the baseline using the blasting parameters in use before optimisation. DMC was used to model the alternative blasting scenarios to obtain the following key objectives:the post-blast muck pile profile was required to have an optimum height of ~28 moptimise cast percentageachieve a well-fragmented muck pile for the draglinethe muck pile profile should be appropriate for the dragline entry into the strip.Achieving these objectives would optimise the dragline performance through reducing rehandle and improving advance along the strip. DMC modelling resulted in the following outcomes:the required muck pile profile could be achievedthe cast percentage increased from 21.1 to 25.1 – a four per cent increaserehandle volumes were reduced.Establishing a good quality assurance / quality control (QA/QC) process was essential to delivering a blast that could achieve these outcomes. The blast was fired successfully and the dragline completed the strip approximately two weeks ahead of the time taken for the previous strip.The second case study is from a coalmine where D11 dozers are used to move the blasted material to the spoil. An optimum profile was required for the dozers for this low-cost mining operation. To achieve this, an electronic blasting system (uni tronicTM 600) was introduced to optimise the muck pile profiles being delivered. The new muck pile profiles showed improved cast percentage from 10.6 per cent to 17.8 per cent. The changes in the muck pile centre of mass displacement improved dozer efficiency as a result of pushing material shorter distances to its final position. Dozer productivity (bcm/h) statistically did not change but coal was being exposed at a faster rate.The third case study summarises the results from a site where dozers are used to minimise the total mining cost. Traditionally, excavators had been used on-site with conventional blast designs. After firing the first cast shot, the blasted material was found reasonably well-fragmented. Although dozing productivity hasn’t been quantified on-site, operators were providing positive feedback (easier push) due to the reasonably good muck pile profile suiting to the dozers. This site also realised significant savings with the dozing as compared to their truck/shovel operation.CITATION:Esen, S and Nagarajan, M, 2015. Muck pile shaping for draglines and dozers at surface coalmines, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 409–416 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By J. J. Montoro

The influence of blasting on the excavators’ efficiency, defined as mucking rate (amount of rock mucked per unit time) and mean bucket load (amount of rock loaded in each bucket operation), is investigated. Rock characteristics, blasting parameters (drill pattern, explosive energy, and charging), and the excavator’s performance (truck loading time and number of buckets to fill a truck) were monitored in eleven blasts in an open pit iron ore mine. ANFO, ANFO/emulsion blend, and watergel were used in the blasts and the powder factor was varied between 0.98 and 1.45 kg/m3. The mean bucket load is mainly affected by the bucket size, which is independent of the blasting parameters. Besides the relation with the mean bucket load, the mucking rate was found to be positively correlated with the explosive energy, whereas no significant correlation with the rock properties was found. The analysis of the data, together with other published works, suggests a non-monotonic relation of the mucking rate with the powder factor, with a maximum mucking rate at a certain powder factor. This is especially true when the useful work of the explosive per unit rock volume is used rather than the classical mass powder factor and when only the amount of explosive above grade is considered.

Jan 1, 2007

By L. C. Clare

In a meeting of this kind where everyone present is connected with or engaged in coal mining, and where each one is present with the set purpose of learning new thoughts or ideas, the subject of the saving of life by any method in the industry is a vitally interesting and important one. On the cost per ton basis, it mounts to a formidable figure especially so during these days of depression and stagnant, or no business. But entirely outside of the human side of the question, to lose lives would cost more than saving them. Your insurance under haphazard safety measures would mount, loss of time due to accidents would impair efficiency among employees and the breaking of the morale of the staff, due to criticism of lax methods would cost more than an efficient safety program. Taking it for granted that most of you are looking at the question from the viewpoint of a yearly or five-year cost sheet, and that at this time you are doing all that can be done without bringing a ruinous cost upon your companies, I can offer only one suggestion: Raise the quality of your safety, or lower the cost. In this meeting, there should be no question of standing still or retreating in the quality of safety, so I will amend the suggestion with "Raise the quality and lower the cost." We have learned that when the coal beds were forming, nature sealed them in with a strata of mud that the ages have turned to shale, sealing them effectively against the deteriorating influences of the air. Mudite is carrying out nature's plan of coal preservation to the inside of the coal mine. Text books teach us that a large proportion of the vegetation that forms our present coal beds grow on what might be termed mud, later falling and being buried practically where it grew by mud, then on being subjected to heat, pressure and time, was changed to coal. The mud being subjected to the same three forces forms our present shale stratas. Now if nature saw fit to use this solidified mud as a preservative through countless centuries, isn't it reasonable to expect that occasional coatings on the ribs and roofs of entries and rooms will aid materially in preserving our coal and coal dust? Nature took mud and formed it into shale; mudite takes the shale, reduces it into dust, adds water and makes a mud, applies it to the ribs, roofs and floors of the mine in a thin coating

Jan 1, 1925

PRESIDENT LITTLEJOHN: We have with us a gentleman from Utah, who is familiarly known -as the "Mudite King," Mr. Reid, of the Lion Coal Company. Here is a letter I would like to read, and probably Mr. Reid will give us an idea of his Mudite machine, or the results he is obtaining. This question was brought up in Rock Springs, Wyoming, but Mr. Reid was not there personally during the discussion, but Mr. Burnell, who is general superintendent of the Lion Coal Com¬pany, as much as he possibly could, described the system and its effects. I believe Mr. Reid will probably be able to give a somewhat clearer statement this afternoon. This letter is from the Coal Mining Inspector of the State of Utah, John Crawford. "February 10, 1925. "The Industrial Commission of Utah, Building. "Statement of John Crawford, Coal Mine Inspector, in regard to Muditing in Coal Mines: "That Muditing used in connection with our present sprinkling system in coal mines is the missing link to the system we have had heretofore, because the water applied by the former system began to dry out, in heavy air currents, the moment it was put on. Consequently the dust that had been humidified by sprinkling, came back to its natural condition, and if anything, the combustible parts of it, in my opinion, were more intensified than previous to being wetted down. "The advantages that Muditing has over the old system of sprinkling are: "1st. The dust that is on the roof, timbers and sides of the entry is washed completely off and rolled up in the Mudite solution which entirely destroys the wings, crudely speaking, of the fine coal dust. "2nd. Sprinkling with the Mudite system, the water and mud is of greater extent than could be applied with a hand hose by a sprinkler. This sprinkling can be done while the mine is in operation, just the same as if water alone was being used. "3rd. The Mudite solution, when dried out, leaves a coating which serves as an armour to the coal, so that in the event of a local explosion, the inflammable matter on the coal is non-combustible; whereas, if that same coal had been sprinkled with water only, and made free of dust, the heat would have the same effect on the coal as it has on a stove when coal is thrown into it-instantaneous combustion. "Therefore, it is my opinion that the Mudite system is the missing link to the perfecting of our sprinkling system here in Utah. "(Signed) JOHN CRAWFORD." Mr. Reid has with him a few sam¬ples of his Mudite, after it has become solidified, taken from the floor, as I understand it. It is interesting. We have a few minutes to spare to good advantage, were we to ask Mr. Reid to give us an idea of his machine, as briefly as he possibly can, and also what he thinks the effect of the Mudite is compared to dry rock dust. Mr. Reid. (Applause.) MR. W. J. REID (Lion Coal Company) : I came down here with no intention of making any talk on Mudite. However, there being so many people that have seen Mudite at Wattis

Jan 1, 1925