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By B. P. Faulkner

In 1974, Allis-Chalmers, in corporation with several iron ore operating companies, began to evaluate direct firing of coal in the GRATE-KILN System. Several coals were ground at the Allis-Chalmers Process Research and Test Center and shipped to Cleveland Cliff's pilot plant near Negaunee, Michigan, where they were used as fuel to pelletize Empire magnetite concentrates in the CCI pilot-scale grate kiln. Pilot plant tests were sufficiently favorable to warrant testing in a commercial-scale pelletizing plant. These tests were conducted at the Empire Mine in the late summer and fall of 1974 and again in the summer and early fall of 1975. In the fall of 1975, Allis-Chalmers Mining Systems Division started a program, in the Advanced Technology Center, designed to develop a laboratory test procedure for the evaluation and study of various parameters associated with the direct firing of coals in a GRATE-KILN System. The initial results of this program were presented at the 50th Annual Meeting Minnesota Section, AIME, January, 1977. This paper will briefly review the initial laboratory work and discuss the latest results obtained.

Jan 1, 1977

By F. Heivilin

Little did I know, in 1977, that when the A. P. Green Refractories Raw Material Manager showed me 5-6 burlap bags with samples of calcined high alumina bauxite in their testing lab that this was the start of China moving to be the number one user and producer of calcined refractory bauxite. According to Ted Dickson in his August 2008 Industrial Minerals article China produced about 4 million tons of calcined bauxite in 2007 using 2 million tons themselves. They imposed an export limitation of 970,000 tons in 2007 and 940,000 tons in 2008. A 10% growth will take up the difference between exports and production in 4 years. Two of these years are gone. It will take only 4 more years to eliminate the export quota in home use. Then they will be importing unless they increase production. Guyana was exporting over a half million tons in 1975 and sold less than 70,000 tons in 2002. Basai Metals Group bought Guyana?s deposits and is rose to 250,000 tons in 2007 and expects to produce 280,000 tons in 2008. PRICES According to the USGS Prices dropped from $172/per ton for Guyana calcines in 1980 just after the start of Chinese production to $122 in 1985. Guyana prices averaged around $120/ton from 1985 to 2005. China?s price dropped as low as $45/ton in 1995 undercutting Guyana and making it virtually impossible for anyone to get into the market. The price suddenly escalated to $550/ton FOB China in the summer of 2008 when China actually cut its exports in half. The price dropped in the fall as orders dropped. This is a four to five fold price increase. Is this a shortage of bauxite or a monopoly? Australia dropped out of the market in 2008 and Surinam, controlled by Alcoa, is not participating right now. Will these two come back in to make up the difference? Will the price hold up so they can make a profit? [ ] The low prices have undoubtedly affected the prices of the 60 and 79% alumina bauxite which can hold down the quantity of 80% plus calcined refractory needed in the world market. China is starting to upgrade lower quality bauxite up to 90% alumina. With high prices kaolin alteration to high alumina comes into play. The calcined bauxite is also used for proponents, Brown fused alumina, and abrasive grades which compete with Refractories. These and the tightness of supplies needed for metallurgical will hold prices up. TONNAGE China is the number one supplier and consumer of high alumina calcined bauxite in the world. Basai Metals Group Guyana (BMGG) is owned and controlled by Basai Minerals Group of China. This appears to be the second largest supplier. Australia has dropped production and Brazil is just starting to expand. It appears China is going to replace some of exports caused by the Export License 940,000 ton maximum in 2008 by raising Guyana?s (BMGG) production of calcined refractory grade bauxite. Companies exceeded restriction in 2007. Fines have been imposed for 2008. In August 2008 they appear on line to meet the 2008 quota. After August prices have dropped off as orders dropped due to the recession. Guyana was the largest producer in 1975 with 769,000 tons which decreased to less than 79,000 tons in 2002. The U. S. is a small part of the world production. I have used the United States charts to represent world imports because I have little data on what other countries import and pay FOB for their bauxite. China started exporting calcined 80% plus refractory bauxite to the United States in 1979 with 24,000 tons. By 1985 they were the number one importer with 169,000 tons. Guyana who had been number one in shipments to the United States gradually decreased to 36,000 tons in 2006. Guyana has been purchased by China BMGG and will increase there production to over 200,000 tons in 2009. Australia shut down production in 2008 and Surinam has elected to not send any Calcined bauxite to the United States. Imports to the United States from 1978 to present are as follows: [ ] Refractories are important because they affect 96% of the GNP. During the cold war we had stockpiles of 80% refractory grade bauxite

Jan 1, 2009

By Roy A. Grancher

HAPPY BIRTHDAY Not only is 1971 the Centennial Year of the AIME, but it also marks the One Hundredth Anniversary of the United States Portland Cement Industry. On September 26th in 1871 David O. Saylor of Allentown, Pennsylvania, received his patent Numbered 119,413 for the manufacture of portland cement. "Cement" had been used in the United States before that. This was, however, natural cement - a direct product of rocks as found in nature, usually burned at low temperatures in open kilns. During the early 1800s this natural cement played an important role in such projects as the building of the Erie Canal. It was only after the Civil War that small amounts of high priced portland cement was imported from Europe. The successful use of this material in construction led to Saylor's experiments and subsequent patent for the manufacture of a scientifically controlled product in this country. These one hundred years have witnessed four major "ages" of cement . . . three of them occurring in the last quarter century since World War Two. The first age was the "Age of Development", a seventy-year period which saw the growth of cement and its concrete end uses as major construction materials. Next followed a period called the "Age of Demand" when, after the war, cement became in short supply relative to large building requirements. In effect a cement shortage existed. The decade of the Sixties proved to be the "Age of Reaction", with its courses of action coming in response to the problems that arose when the industry's expansion programs provided too much capacity. Today cement, and the concrete industries, find themselves entering the "Age of Reason". Overcapacity, low price, rising costs, and poor returns are several of the reasons behind that name, As these industries face the construction challenge of the Seventies, and beyond, the application of basic management principles (otherwise known

Jan 1, 1971

By Jerry T. Shelby

Surface and underground mining operations require equipment with high power output ratings. Haul trucks, loaders, dozers, and other equipment need increasing horse-power to meet production demands. To get more horsepower out of the engines driving the equipment, most manufacturers use turbocharging. Detroit Diesel puts the number at about 90% turbocharged, while Caterpillar estimates 75% to 80% of all its equipment is turbocharged. Turbocharging increases the power output and overall engine efficiency. But it presents some maintenance and operational problems that were not factors when only naturally aspirated engines (nonturbocharged) dominated the scene. A turbocharger is an exhaust-driven air compressor. Using the waste energy in the engine exhaust, a turbine wheel is driven. This wheel is connected by a common shaft to a compressor wheel. The shaft is supported by two plain bearings, or bushings. As the turbine wheel is rotated, the compressor wheel continually compresses the intake air to the cylinders. Compressing the intake air means that more air can be put into the cylinder to burn more fuel. The more fuel the engine can completely burn or combust, the more horsepower the engine can produce. Even though the turbocharger is a relatively simple device, it is a sensitive engine component. It requires special consideration at engine start-up and shutdown. Being freewheeling and exhaust driven, turbochargers can experience temperatures of 540°C 1000°F) and rotational speeds of more than 100,000 rpm. Due to those temperatures and speeds, lubrication is critical to the operation and life of a turbocharger. The turbo is located high on the engine, with the oil supply running through an external line from the sump. The recommended practice is to start the engine and allow it to idle for a few minutes before any revving or loading. This allows the oil to reach the turbo and properly lubricate the bearings before high rotational speeds are seen. Turbo oil supply lines can be as long as 1.5 m (5 ft). Depending on ambient temperatures and oil viscosity, it can take as long as 30 seconds for oil to reach the spinning turbo. However, as little as five seconds without oil can damage the turbo's bearings, reducing its life and overall efficiency. Lubrication problems seen at shut-down can also significantly affect turbo life and efficiency. Manufacturers recommend an idling period of five to seven minutes before engine shutdown. This allows the turbo to slow down and cool off somewhat to help prevent oil coking and bearing damage. When the engine stops, so does the oil supply. There is very little oil left on the bearing surfaces and in the turbo oil supply passages. The immediate heat transfer from the turbine wheel to shaft, bearings, and turbo body literally cooks what is left. This high heat without oil flow can cause bearing deformation by actually melting some of the bearing material. The rapid oil oxidation and coking will restrict oil passages, damage bearings and shaft. Besides heat soaking, there is another problem. If the turbo is spinning at high speeds when the engine is shutdown, the turbo must spin-down to a stop without oil flow. With the large size of turbos used on mining equipment, this spindown time without oil can be for as long as 10 to 20 seconds. Fortunately, lack of lubrication at start-up and shutdown and the subsequent bearing damage can be prevented by oil injection devices. These devices hold a reservoir of engine oil. The oil is injected to the turbocharger bearings immediately on start-up and for several minutes after shutdown. Oil injection devices are spring loaded, hydraulic accumulators. They are actuated at start-up by a solenoid wired to the starter motor. Engine oil pressure charges the accumulator during normal operation. Upon shut-down and loss of oil pressure, the device provides oil to the turbo for about two or three minutes. With an oil injection device, the engine can be started and immediately driven without fear of turbo damage. Also, an abrupt shutdown will not damage the turbocharger since the device will continue to lubricate for two or three minutes. A word of caution. Be sure the oil injection device provides positive oil displacement (pressurized oil flow). Do not use a gravity-flow device. Unless it is a true accumulator, the device could starve the turbo for oil on start-up, Ask for start-up and shut-down pressures and delivery times before considering installation. Keep the oil clean, and follow the manufacturer's recommended oil change intervals. These intervals are usually shorter than with naturally aspirated engines. Use oil with a CD rating designed for diesel applications. A multiviscosity oil is preferable. Use a synthetic engine oil, such as Mobil's Delvac 1, Gulf's Super Duty II, or Chevron's Sub-zero Fluid. Synthetics have much better flow properties at low temperatures. They also have greater oxidation stability (they can take the high heat of turbo-bearing lubrication. And they produce fewer deposits because they are more thermally stable. But synthetic oils do cost more - two or three times more. One additional point - maintain the air intake system. Since all mining is usually in a dusty environment, air filters should be changed regularly and intake systems should be checked for leaks. All intake air passes through the turbo. Any dirt or abrasives entering the turbo will damage the unit and shorten its life. While mining is a heavy duty business with severe operating conditions, you can get the life from your turbocharger that you expect by following a few simple steps: • equip the turbo with an oil-injection device to provide lubrication on start-up and shutdown; • change the oil and filters regularly; and • use the proper oil-synthetic, if possible.

Jan 3, 1987

By Peter J. Tarkoy

A great deal of attention has been directed toward the complexities and inadequacies of exploration and pre-bid geotechnical information for heavy construction projects, differing site conditions, and the adversary relationships which generally develop as a result. The adversary position has been maintained at all cost. The solution is simple, if not easy. The solution requires strict and equal adherence to given principles by all parties involved, throughout the life of the project, from conception to completion. It is necessary to review and redefine some basic concepts, without value judgements, from a context of getting the job done. In a recreated context, the role of truth, judgement, responsibility, and integrity, in exploration, engineering design, construction estimating, and project construction, will be examined. It is suggested that anticipated geotechnical conditions be defined unconditionally. The alternative choice is to give the bidder the opportunity of making the interpretive judgements based on geotechnical data. Similarly, a unilateral method of establishing encountered conditions that are agreeable to both owner and contractor, must be outlined prior to contracting. As anticipated and encountered conditions are firmly and accurately established, significant differences can evaluated based upon limitations specified in the contract documents. Impact of differences on project costs can be fixed by pre-defined methods.

Jan 1, 1983

Coal that meets customer specifications is often stored in silos before being loaded into cars. It is often found that coal in a particular car does not meet customer specifications due to the mixing of coal inside the silo. Some new contracts require meeting specifications on a per car basis. Silo flow models are used to predict quality in such cases. However, coming up with an accurate silo flow model for each case is very difficult and time consuming. This paper examines the viability of using an online analyzer at the loading end of the silo in conjunction with a feedback circuit, to optimize the quality of the coal being loaded into trains, so that each car meets quality specifications.

Jan 1, 2000

By Peter Schmäh

Pipe-jacked tunnels are considered for a large variety of applications from water and sewage, cable ducts to challenging pipeline crossings or landfall construction. In most cases, Slurry MTBMs are used to carry out these projects. Continuous further development of technological features for pipe jacking plays a key role to overcome feasibility limits and to meet increased project requirements. As tightened safety regulations in terms of accessibility and escape routes increasingly limit the options of small segment lining tunnels in the diameter range below 4 m, 13 feet, pipe jacking has partially taken over. During the last decades, a growing number of large-diameter and long-distance pipe jacking projects have been completed. Experienced contractors successfully use the technological capacity of the MTBM equipment. The machine and cutting wheel have to be designed according to the ground conditions. Bentonite lubrication and interjacking stations are key factors to keep push forces moderate. For long pipe jacking drives, a so-called push module can be installed in the machine can, to be able to switch from pipe jacking to segment lining in case the machine gets stuck. The overall aim is to provide clients and the tunnel construction industry with safe and economical solu- tions for successful project execution. This presentation will present international milestone projects and will also discuss the latest developments in automation, related opportunities and limitations, and the future of digitization and artificial intelligence in pipe jacking.

Jun 23, 2024

By Lit-Mian Chan, David H. Carlson, John H. Johnson

This paper presents an apparatus and procedures to implement a methodology for controlling ambient air quality in a confined working environment, such as an underground mine, an underground storage area, or a tunnel. The air quality control methodology is directed at limiting the quantities of exhaust pollutants emitted by diesel-powered vehicles into the confined space by identifying vehicles that are excessive polluters. The methodology is based on tailpipe and ambient air measurements in the confined space, and the ambient air threshold limit values (TLVs) for the various diesel exhaust pollutants. The methodology consists of two computational methods; a deterioration criteria computational method to identify excessive polluting vehicles, and an engine performance computational method to determine engine performance and to provide information needed to diagnose engine faults. The methodology is designed for implementation in conjunction with a preventive maintenance program. The first part of the paper describes the mine air and tailpipe emissions measurement apparatus and techniques used to obtain data. This is followed by sections discussing the deterioration criteria and the engine performance computational methods. A section discussing some common engine emissions-related faults is also presented. Lastly, a proposed procedure to implement the methodology including a possible hierarchical structure for mine personnel involved to implement the procedures is presented.

Jan 1, 1993

By M. L. Free, L. Anthian

Electrochemical, chemical, and image analysis techniques were utilized together with statistical analysis methods to determine the effect of various anode impurities on copper electrorefining performance. Results indicate that arsenic is a beneficial anode impurity. Anode lead and sulfur are shown to decrease electrorefining performance. Specific emphasis is given to the influence of individual elements on current efficiency, slime particle generation, and cell voltage parameters.

Jan 1, 2000

By J. D. Grenia

The Buick Mine is a joint venture of American Metals Climax, Inc., and Homestake Mining Company located 120 miles by road southwest of St. Louis, near the village of Boss, in the 'New Missouri Lead Belt' (See Figure 1). Since start-up in 1969, over four million tons of lead-zinc ore have been mined and milled at Buick. Situated about 1,100 feet below the surface at an elevation 270 feet above sea level, the flat lying sinuous ore bodies are up to 250 feet wide, 85 feet high and several thousand feet long. Mineralization is galena, sphalerite and chalcopyrite in dolomite, Access to the mine is through two 18'Ø concrete lined vertical shafts - one for servicing and the other for hoisting ore (See Figure 2). The mine is being worked by a modified room and pillar method using both rubber tired equipment and a sub-level rail haulage. Ore is broken from first pass headings, back and bench faces and transported by load-haul-dump units to ore passes located on 900 foot centers. The ore is pulled from chutes on the sublevel 90 feet below into 15 ton bottom dump cars and delivered in 10 car lots by a 15 ton diesel locomotive to a 42" gyratory crusher (See Figure 3). A recent innovation has been the introduction of two 50 ton trucks with plans to haul up to 60% of the ore on the mining level to an ore pass feeding directly to the primary crusher (See Figure 4). Ventilation raises up to 16'Ø, which were originally planned for 900 foot centers, are now driven on 450 foot centers.

Jan 1, 1973

By Jon J. Indall

I. INTRODUCTION The challenge of moving the use of nuclear energy from military to civilian use was first issued by President Dwight Eisenhower in his December 8, 1953 “Atoms for Peace” speech delivered at the United Nations. Eisenhower stated: “The United States knows that if the fearful trend of atomic military build up can be reversed, this greatest of destructive forces can be developed into a great boon, for the benefit of all mankind. * * * * The more important responsibility of this Atomic Energy Agency would be to devise methods whereby this fissionable material would be allocated to serve the peaceful pursuits of mankind. Experts would be mobilized to apply atomic energy to the needs of agriculture, medicine, and other peaceful activities. A special purpose would be to provide abundant electrical energy in the power-starved areas of the world. In the 1950’s and 1960’s, the Atomic Energy Commission promoted the use of nuclear power as the answer to our nation’s energy problems. Nuclear power would provide energy too cheap to meter. The utility industry responded and numerous plants were planned with over one hundred constructed from the 1970’s to the 1990’s. Capital costs for nuclear power plants escalated due to permitting changes and public opposition, and the Three Mile Island incident caused new nuclear plant construction to cease. Today, we once again are experiencing a nuclear renaissance. Concerns over global warming and rapid projected increases in the demand for electricity have caused many nations to begin construction of new nuclear fleets. The price of uranium to fuel these reactors, which had dropped to an historical low of $7.10 in 2001, has surged to $56.00 as of October 2006. This paper will review some of the social, environmental, and government issues that are all playing a role in the resurgence of the nuclear fuel industry.

Jan 1, 2007

By Edward DeLilla

For the past 30 years, surface mines have moved toward more highly mechanized, automatic systems that continuously mine overburden and ore to increase productivity, lower operating costs and minimize manpower needs. To achieve these goals, mine operators must be involved in every step of the machine procurement process. Several factors are involved in making the machines operate economically and efficiently: -Prudent engineering. -Proper planning. -Realistic feasibility studies. -Effective specification. -Thorough training of the mine personnel.

Jan 1, 1994

By S. Noll

Ventilation is an essential part of any underground mining operation. It provides fresh air for workers and machinery, keeps up an adequate mine climate and dilutes and dissipates noxious gases. Possible changes in the economic environment for mining in the future, e.g. increasing energy costs, will necessitate optimization of distribution of airflow within most mines. This paper discusses the scientific set-up for measurements as well as the behavior and influence of parameters of ventilation according to airflow distribution under consideration of technically possible set-ups of mine fans. This study was done in an underground mine with a flat seam room and pillar mining method.

Feb 27, 2013

By Paul D. Tomlingson

During the next several months, SME’s E-Newsletter will feature 15 articles on maintenance management. The articles may be read online or downloaded and distributed within your organization. They will address maintenance management topics, offer guidelines to mining managers and provide techniques that the maintenance manager can use. The articles will stress equipment management, a strategy that the mining industry has accepted as a modern replacement for outdated maintenance practices. Equipment management is the mutually supportive interaction of all mine departments as they establish equipment needs, procure equipment, test, commission, operate, maintain, modify and eventually replace equipment. The successful application of equipment management principles can quickly and reliably produce cost reduction and performance improvement results while providing a dependable way of sustaining them. Equipment management embraces modern management techniques. These include reliability-centered maintenance, life-cycle costing, capital performance, the effective use of information and productive organizational models.

Jan 1, 2003

By J. W. Mustard

The Macmillan Pass tungsten property (MacTung) is the largest known copper-tungsten, calcic, exoskarn deposit in the Western Hemisphere. Located on the border between the Yukon and Northwest Territories in northwestern Canada, the deposit crops out on Mt. Allen within the Selwyn Mountain Range. It was discovered in 1962 by a subsidiary of AMAX Inc. and has since been explored by 16,300 meters of surface and underground diamond drilling and by 800 meters of underground development. Geologic reserves are in excess of 30 million tons, grading slightly less than 1.0% WO3. Scheelite (CaWO3 ) is the main mineral of economic interest. Accessible by road, the property is not in production. Previously estimated reserves at MacTung have been unable to fully utilize all the geological controls on mineralization. In the past three years, however, an intensive program has been underway to improve our understanding of the deposit and to use the resulting information in a more precise way. This paper will discuss the key aspects of the geology as they specifically relate to reserve estimation and will demonstrate how these controls are being used in a geostatistical model of the deposit.

Jan 1, 1985

By M. J. Langley

Zinc ores were first discovered in Tennessee in 1856 at Jefferson City where a deposit of oxidized ore became known as the Mossy Creek Mine. From that time until 1913 small scale attempts at prospecting and mining were made in various parts of the district. The actual systematic development of the zinc deposits dates from 1913 when the American Zinc Company started operations at Mascot. Six mines are in operation by three companies and a seventh mine is being developed by a fourth company. The total daily production from the field is 11,000 tons of crude ore, which grades from 3 to 6 per cent zinc. Most of the ore bodies are large and ramiform, resembling asyrmetrical networks in which the ore shoots form channel like branches with areas of non-comercia1 rock, called blank islands. Most of the orebodies are adapted to large scale mechanization.

Jan 1, 1962

I reached New York at the start of my second South American adventure on Jan. 9, 1916. In the Anaconda office I found that we were not to take the steamer for two weeks which gave me time to study reports on Potrerillos and Corocoro. Reno Sales, whom I had met in Butte only casually, was to go with us to South America. Though he was only a little older than I, he was already an unquestioned leader of our profession, and we became and remained good friends. William Braden was in New York and would return to Santiago with us. Tom Hamilton would also be returning from a vacation. Leighton Stewart, a young engineer who was to work for Braden, was going on the steamer with us, taking along his wife. And of course Dr. Ricketts would go along. He had just become engaged to John Greenway's half sister, Kate Greenway, and in order not to be away from her longer than was necessary, he did not reach New York until a day before we sailed. This made eight of us who would be in the party. We were to go to Corocoro first, as Braden had taken an option on the Chilean company there. Development was already under way. As reports came in by mail we tried to get as good an idea of the property as we could before the actual examination. Mr. Thayer "put us up" at India House, one of the best lunch clubs in New York, and Reno and I ate our lunches there almost every day. Thayer, Braden, and Cornelius Kelley, who was to succeed Mr. Ryan as president of Anaconda, joined us when they could. At the lunches they told us about the under- ground war in Butte a few years earlier. When I wrote my chapter on the Butte wars in Romantic Copper more than 15 years later I could not help being biased a bit by my friends, all of whom were on the Anaconda side. But their opponents in the Clark and Heinze camp were just as biased in their comments on my book.

Jan 1, 1976

By T. M. Jones

This paper outlines the development of the theory of controlled district recirculation and indicates the advances in understanding and technology which have enabled a major change in established ventilation practice. An insight is presented into the possible future use of controlled district recirculation as acceptable practice in mine ventilation planning.

Jan 1, 1987

By Jochen Belz, Allan Henneker, Nod Clarke-Hackston

For the construction of tunnels and other underground structures, extraction of the exact amount of material is of paramount importance both economically and for engineering purposes. In the Sequential Support Method (NATM) immediate (sequential)and smooth support by means of shotcrete, steel arches, lattice girders and rockbolts, either singly or in combination are used; cutting of the precise (albeit sometimes of complex geometry) profile is an integral part of the method. In order to save unnecessary excavation and provide better information to the machine operator, VMT GmbH has developed a system to support precise excavation of the tunnel profile when using road headers or other partial face cutting machines. This paper outlines the principles of this system with examples from Australia, Ger-many, Sweden and Spain and will cite examples of typical savings achieved.

Jan 1, 2007

By T. Moller

There are differences in design aspects between steel and rubber linings in grinding mills. This paper describes the basic design rules for rubber liners for different grinding applications. When converting a mill from steel to rubber liners, the design must be changed from such familiar steel liner shapes as wedge bars and plates, wave liners, ship-lap, etc. to take advantage of the characteristics of rubber. Very little of the knowledge of the wear properties of steel can be used for the design of rubber mill liners.

Jan 1, 1989