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By Klaus Rieker

Over the last 30 years Wayss & Freytag Ingenieurbau AG has gained a lot of experience in mechanized tunnelling on various major projects. During this period most important developments concerning the machine technology for EPB- and Slurry-Shields have taken place. Since the first application of a hydro shield for the Wilhelmsburg Collector project in Hamburg in the early seventies, several stages of development have led to the current state-of-the-art in mechanized tunnelling. The continuous improvement of TBM techniques allows the execution of high quality tunnelling, particularly with regard to maximum safety and efficiency. The practical experience of the construction companies is of essential importance in order to continue further development and improvement.

Jan 1, 2005

By Andrea Brickey, RICHARD AMOAKO, Akshay Chowdu

Production forecasts derived from the medium-term schedule represent the best path forward for underground mining operations to achieve corporate and operational goals. Unforeseen circumstances, such as equipment breakdown, can cause significant deviations from established production forecasts in the short term. Such situations require timely mitigation of the effects of the deviations in order to stay as close as possible to the medium-term plan. This paper presents a deterministic mathematical formulation for short-term scheduling that addresses this challenge. The formulation is able to make up for deficits resulting from operational disruptions by minimizing deviations from medium-term production goals and medium-term activity start dates. We demonstrate this in a case study by simulating disruptions involving reduction in ore extraction capacity and development advance rate. Aside from the rescheduling capability, this formulation can help mine planners conduct analysis on the impact of various disruptions on the schedule. The formulation can help identify those conditions or disruptions that are more detrimental to the achievement of forecast targets, or otherwise. The formulation also affords mine planners the flexibility to prioritize one production goal over the other, depending on operational conditions at the mine. In the future, we seek to incorporate in the formulation respirable dust, diesel particulate matter and ventilation constraints in order to create more realistic schedules, and enhance miners’ health and safety.

Jan 1, 2024

By E. A. Laurila

During last years many different types of X-ray fluorescence analysers have appeared in the market most of these instruments being designed for laboratory use. The instruments applied ins continuous processes are usually modifications of these laboratory types. The application of these instruments to the analysis of heavier elements seems to be quite satisfactory. By lighter elements difficulties are caused by the strong absorption of the characteristic fluorescence radiation, which sometimes makes the use of vacuum or helium chambers necessary. In the following an instrument of another type will be described. It has been developed exclusively for the analysis of titanium in ilmenite concentrate, where the content of Ti02 varies between 43 - 46%. Preliminary measurements have shown that in this interval absolute change of 1% in the Ti02 concentration causes a relative change of about 2% in the intensity. Because: the accuracy of 0.5 % Ti02 is sufficient, 1% relative accuracy should be, attained in intensity measurement. The problem is not very easy to solve due to the fact that Ti K radiation is rather soft and the requirement's for accuracy are rather high. Being applied to the analysis during a continuous process may statistically fluctuating variables in connection of sampling and disturbances of many kind set special requirements for the instrument design.

Jan 1, 1960

From a gathering storm of climate change based legislation that could potentially overwhelm the mining industry, to the nuts and bolts of mineral processing and just about everything in between, about 100 mining and mineral processing professionals heard it at all at the 60th annual Colorado MPD Meeting April 22-24 at the Broadmoor in Colorado Springs, CO. With a sweeping agenda under the banner ?What in the world is new in mining and metallurgy? attendees were treated to four sessions and 21 presentations that covered the range of mining industry issues. Bill Reid, president, chief executive officer and director of Gold Resources Corp., spoke about his company?s El Aquila gold project in Mexico. With five projects in Mexico, Gold Resources Corps. is aiming to become a low-cost gold and silver producer. Its flagship property, the El Aguila gold project, is a high-grade gold and silver property with significant base metal credits of copper, lead and zinc. Production of the El Aguila project was targeted for mid-2009. Reid said that three high-grade deposits have been discovered at the El Aguila project. They include the high-grade ?manto? style El Aguila openpit deposit, the El Aire high-grade polyme-tallic vein system, which is underground, and the underground La Arista high-grade polymetallic vein system. The project is located 120 km (75 miles) south-east of the capital city of Oaxaca, Mexico. Reid said the property has yielded several exceptional gold and silver surface samples, including a 36-g/t (1.1 oz/st) gold sample and a 3,100-g/t (90 oz/st) silver sample. Other properties that Gold Resource Corp. has are:

Jul 1, 2010

By Bernard L. Merlo

INTRODUCTION Modern mine management is constantly striving to develop improved mining methods which will not only increase productivity, but will also provide a safer work environment and make the most efficient use of our natural resources. Progress can be seen in this area by tracing mining methods through history. Work that was originally done with hand tools progressed with the age of mechanization to conventional mining, matured to continuous and longwall mining, and the advent of short¬wall mining, a combination of continuous and longwall, has recently been seen. This new method of shortwall mining provides a promising method for safe and ex¬pedient coal extraction. This study focuses upon the planning, design de¬velopment, and operation of the first producing short¬wall unit in the US which was operated in the Pittsburgh coal seam in northern West Virginia. MINE DESCRIPTION The mine is located in northern West Virginia at Grant Town in the heart of the high volatile Pittsburgh coal seam. Originally opened in 1901, the mine has be¬come one of the largest in the US, encompassing an area of approximately 103.6 sq km (40 sq miles). The seam being mined was the high volatile Pittsburgh seam which ranged in thickness from 1.8 to 2.96 m (6 to 91/2 ft). Three types of mining methods were employed: con¬tinuous mining, longwalling, and shortwalling, with each type accounting for 50%, 30%, and 20% of total pro¬duction, respectively. A total of 630 contract and super¬visory personnel were employed to produce the mine's designed annual tonnage of 1.8 Mt (2 million st). There were ten producing sections, eight continuous miners, one longwall, and one shortwall, operating a total of 22 unit shifts per day. Eight shafts, varying in depth from 80.2 to 194.2 m (263 to 637 ft) provided entrance to the Pittsburgh coal seam. These shafts were used for ventilation, portaling, coal hoisting, supply, and emergency escape hoisting. Ventilation was achieved by means of three exhaust fans which provided 707.9 m3/s (1.5 million cfm) of air to the mine and removed approximately 141 584 m3 (5 mil¬lion cu ft) of methane per 24 hr period. The room-and-pillar method was used for secondary recovery with designed barrier blocks between panels of 61 m (200 ft) in width. A double row of blocks was left around each gob area to provide efficient bleeder action

Jan 1, 1982

By Yves St-Amour, Vince Luongo

This paper will discuss one of the largest construction projects the City of Portland has undertaken. This phase of the Willamette River Combined Sewer Overflow (CSO)project consists of approximately 18,500 ft of tunnel in soft ground, requiring the construction of six deep shafts and jet grout ground improvement. The purpose of the project is to reduce volume of combined sewerage overflows from the drainage areas on the west side of the Willamette River. Bencor-Petrifond-Pacchiosi Joint Venture was awarded a contract to design and construct six deep circular shafts, jet grout ground improvement for three bridges and jet grout ground improvement break-in/outs for some shafts. Of the six shafts the Pumping Station Shaft was the deepest and largest, requiring a permanent ground support system with a deep jet grout ground water cut-off to 335-ft deep. The joint venture used state of the art methods and equipment to achieve its objectives and build the structures through some very difficult alluvial soils to great depths next to the Willamette River. The paper will provide a general discussion of the shaft construction and jet grout ground improvement installed for this phase of the project. It will also discuss some of the technical challenges encountered while effectively managing risk and costs, resulting in a successful project completed in a timely manner.

Jan 1, 2005

By N. A. Abdel-Khalek

The amenability of carbonate separation from a sedimentary phosphate ore using a bioflotation process was studied. Two types of bacteria were chosen for this study. The experiments were performed using oleic acid as collector. The flotation experiments were carried out using statistical designs for optimizing the main operating parameters. A concentrate containing 0.78% MgO and 30.15% P2O5 with a recovery of 92.31% was obtained from a feed containing about 2.45% MgO and 27% P2O5. These specifications could not be obtained using conventional flotation experiments under similar conditions in the absence of bacteria. Measurements of zeta potential, adsorption of bacteria and collector, as well as froth power, were performed to explain the role of microorganisms in the surface modification of both dolomite and phosphate and in their interaction with the collector.

Jan 1, 2009

By Susana Bolhão Muiños, José Hipólito Monteiro, Martin Frank, James R. Hein, Henrique Garcia Pereira, Fátima Abrantes, Tracey Conrad, Luís Gaspar

In spite of all the work that has already been done on ferromanganese deposits, studies on the Atlantic Ocean occurrences are still in their infancy and there is a clear need for investigations concerning the origin, distribution, and resource potential assessment of these deposits. Nevertheless, studies already carried out on northeast Atlantic seamounts indicate the general presence of ferromanganese deposits of hydrogenetic origin, i.e. deposits formed by direct precipitation of colloidal, hydrated metal oxides that are scavenged from the water column on hard-rock substrates. The hydrogenetic precipitation promotes the enrichment of ferromanganese crusts in many trace metals, most of which are of economic interest, such as Co, Ni, Te, rare earth elements, and platinum-group elements and thus ferromanganese crusts are considered an important metal resource.

Sep 1, 2014

By T. B. Szwilski

The paper gives an account of the development of a mine health and safety program in China from 1987 to 1996. The project was funded by the United Nations Development Program and managed by the International Labor Office (ILO). The objective was to strengthen the capability of the National Safety Training Center (NSTC), located near Beijing to train more than 2,000 engineers per year, and provide consulting and informational services to 39 safety training centers and coal mines. Presently China has the highest mortality rate in the world for coal mine operations, the greater incidence occurring at the many thousands of small, unlicensed underground mines.

Jan 1, 1998

By D. Küster, G. Franken, P. Schütte, J. Vasters

The CTC (Certified Trading Chains) mineral certification system has been piloted in Rwanda since late 2008. CTC project implementation is jointly driven by the Federal Institute for Geosciences and Natural Resources (BGR) and the Rwanda Geology and Mines Authority (OGMR), in cooperation with other national stakeholders. Five Rwandan mineral producers participate in the CTC project with their flagship mining concessions. Based on independent third-party audits, CTC certifies supply chain due diligence measures of these companies engaged in the artisanal mining sector through on-the-ground assessments of mining conditions, transparency, as well as mineral origin and traceability. The CTC system thus allows responsible mineral producers and their clients to verifiably demonstrate supply chain due diligence and good governance in conflict-affected and high-risk areas.

Jan 1, 2011

By Paul H. Earl

This paper discusses the evolution of a modeling methodology for explaining price behavior in the aluminum industry. Three generations are described, each utilizing as a foundation a microeconomic stages-of-processing approach. The second generation represents an improvement over the initial version, by incorporating more rigorous specifications of energy cost, and market strength (demand-supply balance) as well as endogenous treatment of market strength. International linkages across prices, costs, and markets, are the major extensions in the third generation. The discussion covers theoretical considerations, data problems and limitations, and model specifications. Simulation and forecasting properties of the models are also addressed.

Jan 1, 1979

By F. J. Murrell

No other region of the world is enjoying the tremendous growth of power use that is currently being experienced in Asia. Fortunately for those of us in the coal industry -particularly in Asia -the preponderance of the power plants being planned or under construction designed to use coal as the power plant fuel. This has produced a significant increase in the demand for steam coal, which has in turn encouraged many of us in the industry to develop new coal mines. One country that has enjoyed very substantial growth in coal production is Indonesia. This developing country of 195,000,000 people who live on the nearly 13,000 islands of Indonesia have emerged very quickly to become the third largest exporter of steam coal, following only Australia and South Africa. Almost all coal in Indonesia is mined by surface mining methods. This paper will examine the surface mining of coal in Indonesia, as it continues to be an important part of the supply equation for coal in Asia.

Jan 1, 1996

By H. F. Broicher

Introduction In April 1998, AIS Sommer GmbH of Germany delivered the first laser-induced fluorescence (LIF) analyzer to the mining industry. LKAB's Kiruna iron ore mine in Sweden shared the costs and the risk of building the prototype. This marks the beginning of LIF analysis as a technique for quality control in mining and mineral processing. Photoluminescence analysis is well established. In most laboratories, fluorescence spectrometers are standard equipment for quality or pollution control. LIF is being used in several applications, including combustion studies and particle image velocimetry. However, it has mostly been used in laboratory environments. The availability of rugged lasers for industrial use brings this powerful tool to the forefront of production, even in the rough conditions found in mining and minerals processing. Laser-induced fluorescence Basics. Fluorescence of naturally occurring minerals has fascinated man since scientific investigation of this phenomenon commenced about 200 years ago. However, importance in industrial application and peripheral activities. Hand sorting of ore under ultraviolet (UV) lamps is seen as an archaic method. Long gone are the days when geologists set out at night with UV hand lamps to find valuable ore deposits, especially those of tungsten. Today, fluorescent minerals are considered collectors' items and museum exhibits. In the late 1960s (Hemphill, 1968) and during the 1970s, attempts to use lasers for excitation of fluorescence in minerals led to the development of an airborne fluorosensor (Seigel and Robbins, 1980). However, this prospecting technology did not gain industry acceptance and vanished from the market. During the past seven years, ongoing research of the LIF of minerals resulted in new findings that give good reason to revive the interest in fluorescence and its use in the mineral industries (Broicher and Zydek, 1995; Broicher, 1998). Fluorescence is defined as the short-lived form of photoluminescence, in which matter emits visible radiation during and after irradiation with light – the fluorescence generally being of a longer wavelength than the irradiation. Fluorescence of matter is described by: • the absorption spectrum, • the emission spectrum, • the decay curve and • the quantum efficiency. The absorption spectrum shows the fluorescence intensity in a fixed spectral band as a function of the excitation wavelength, while the emission spectrum shows the fluorescence intensity at varying emission wave- lengths for a fixed excitation wavelength (Fig. 1). The decay curves describe the exponential decrease of the fluorescence intensity with time. The quantum efficiency is the ratio of irradiating energy to emitted energy. Re- cent research has found that: the quantum efficiency of minerals can be measured and evaluated,

Jan 1, 2000

By J. A. M. Cano

Introduction Since the beginning of operations at the pellet plant at Ponta Ubu ES, Samarco Mineração SA has produced pellets for direct reduction and blast furnace processes. Of the total amount of pellets produced from 1977 through 1993, 55 % are used in the blast furnace, about 45 Mt (49.6 million st). The principal components of pellet gangue are calcium oxide, magnesium oxide, silica and alumina. They should be added in adequate quantities to guarantee the mechanical resistance of the fired pellets under blast furnace conditions. Over the years, the pellets produced by Samarco had a silica content between 2.5% and 2.8% and varying binary basicity preferably between 0.8 and 0.85. On the other hand, the increasing amount of industrial waste in siderurgical plants caused by the increase of steel production has caused some countries to put into practice methods to reduce the volume of slag produced in the blast furnace. This paper's goal is to find an alternative for decreasing the amount of slag produced in the blast furnace. It is possible to decrease pellet gangue by decreasing the silica content to about 2%, leaving the metallurgical properties and quality of pellets unaltered. For this work, Samarco pellets were used with Si02 between 2.5% and 2.8%, pellets with high silica and pellets with Si02 between 2.0% and 2.3% low silica. Both were partially fluxed by the range of varying basicity CaO/SiO2 from 0.8 to 0.95 during production. Experimental tests on pilot scale Thhis work began in January 1986 in the pilot plant (pot grate, Fig. 1) at Samarco. Its goal was to obtain preliminary data that would indicate the bybility of the project. It also formed a solid base to extend the studies in tests on an industrial scale of production for blast-furnace pellets. The pot grate is a test furnace composed of a gas burner, a combustion chamber and a grate, connected by hot air ducts. The burner is fed by a mixture of LPG and air. It reaches high temperatures through oxygen injection. The combustion chamber heats the air that comes from the turbocompressor. This hot air flows through the ducts to the grate on which the pellet samples are fired. During updraft drying, downdraft drying, preheating, firing and afterfiring, the upward and downward direction of the air flow can be controlled by valves driven by pneumatic cylinders. The pot grate indurator was fully automated in August 1989. Positive and negative pressures measurements resulting from gas passing through the pellet layer, as well as temperature readings, are recorded in graphs in relation to time for all tests. The tests depend on the various steps carried out in sequence that can influence the results of the tests. Therefore, some criteria were adopted to restrict the number of variables in the process. This was done to facilitate the results of the analysis. The pellets were composed of concentrate, bentonite, hydrated calcitic lime and metallurgical coal, all regularly used in the pellet plant. The material balance of the pellets mix was determined from the chemical analysis of the components. Table 1 shows the chemical characteristics of the concentrate and the additives used in the pilot plant and industrial tests. The basicity has a marked influence on the metallurgical properties of the pellets produced by Samarco with a silica content between 2.5% and 2.8%. However, for pellets with low silica (about 2%), it was necessary to study the variation in the parameters of quality in a wide range of basicities to deliniate with precision a scope of work. A large variety of low-silica blast-furnace pellets were produced at the pilot plant with binary basicity varying between 0.8 and 0.95. After chemical analysis, those pellets were separated into five groups of different binary basicity (0.8, 0.84, 0.87, 0.90 and 0.95). Each was then split, one part for metallurgical tests in the laboratory at Samarco and another to be evaluated in a laboratory for metallurgical tests in Germany. It was agreed that the tests to evaluate the quality of the pellets in the two [ ]

Jan 1, 1996

By John A. Reeves

The unit-train concept of moving raw materials .is considered by many railroad men as the most signifigant contribution to reducing rail freight costs since the introduction of the diesel locomotive. The idea, which involves assigning railroad equipment to only one haul and keeping the equipment rolling results in the maximum utilization of equipment. For example before the unit train was plaged in servige on coal hauled to one of Mid. Continent's customers, about 900 cars and 9 locomotives were needed to move the coal requirements for this plant, compared with. 250 cars and 6 locomotives used by the present scheduling of unit trains. If the economics of unit-train movements are to be achieved, coal companies no longer can use railroad cars as small storage bins on wheels to accumulate their coal in trainload shipments, but, rather, must build large bins which incorporate facilities for the rapid loading of railroad cars in a minimum length of time. In this manner railroad equipment is operated at a high degree of efficiency 'with consequent dollar savings. After negotiations between Mid-Continent, the customers and the Railroad, it was decided a unit train loadout and storage facility at Carbondale was required in order to reduce the delivered price of coal to the customers and thereby contribute to the reduction in the cost of manufacturing steel. Carbondale was selected as the bin site location, because the cost of constructing a railroad to Redstone could not be justified for the tonnages anticipated.

Jan 1, 1969

By C. G. Tester

Automatic tripper control systems can be reliable and as such are suitable for use in the mining industry. Proper application of fundamental engineering principles provides the means for the reliability. Some of the principles are: (1) Be sure the system designer designs a system that does the job operations people want done; (2) Use sound logic design practices to avoid internal electrical problems; (3) The design must be maintenance oriented; and (4) Use good quality components. I would like to discuss a tripper control installation at Kennecott Copper Corporation, Chino Mines Division, in Hurley, New Mexico, and how these principles apply to this tripper control system. First, however, I will expand on the principles to clarify just what is meant. First, "Be sure the system designer designs a system that does the job operations people want done.? Operator acceptance is often the key to the success or failure of an automatic control system. One of the best ways I know of to get operator acceptance is to give him a system that he wants. I don't mean to imply that if bad practices or procedures exist that they should be incorporated in the control system. I do think that many designers feel they haven't done their job if the control system doesn't do things drastically different than the old manual method. Good engineering principles dictate that the job should be done right and if the manual method was right it can very likely be right for the automatic method.

Jan 1, 1973

By Christopher Mark

Sixty years ago, underground coal mining was the most hazardous job in the United States. Roof falls killed about 100 miners every year, more than all other causes put together. Fast forward half a century to 2016, and the first year ever with zero roof fall fatalities. Just three miners were killed by roof falls during the following six years. To understand how this historic goal was achieved, this study analyzed hundreds of roof fall fatality reports covering five decades. It found that the immediate effect of the Federal Coal Mine Health and Safety Act of 1969 (Coal Act) was to reduce the riskiest activities, like needlessly going under unsupported roof. Other hazards, like large roof falls, required technological developments before they were brought under control. Roof control plans, which the U.S. Bureau of Mines had been advocating since the 1920s, fostered the necessary improvements in both the safety culture and the mining technology.

Jun 1, 2024

By Patrick J. Doig

The contract for the construction of the Inline Pump Station for the Milwaukee Metropolitan Sewerage District involves the sinking of three shafts and the excavation of a pump chamber. The shafts are being sunk to a depth of 104 meters and pass through 52m of sediments before encountering dolomitic bedrock. The pump chamber is constructed in dolomite. The sediments are alluvial, estuarine and lacustrine in origin, with some ice margin deposits. They comprise loosely consolidated fine to coarse grained sand, silts, clays and gravels, and they are heavily saturated with a water content often above 60%. The water table is at a depth of 3m. The dolomite is silurian, generally dense, with some clay-filled vugs and shale partings. Until 1983, underground construction in the Milwaukee area had been limited to depths of 26m in the sediments and 20m in the dolomites. Water control methods had included caissons, compressed air, extensive internal and external dewatering, and grouting. Flows of 20 liters per second were commonplace with as much as 80 liters per second being encountered in the rock. However, in 1984 work was commenced on the deep sections of the Milwaukee sewerage scheme with the letting of three major contracts including the Inline Pump Station. With excavation taking place at greater depths, it become obvious that previous methods of water control would be inappropriate. To protect against major inrushes of high pressure water in the rock, an extensive program of pre-grouting from the surface was specified. Water control in the sediments was left to the discretion of the contractor and in each case freezing was choosen. This paper describes in detail the grouting and freezing procedures.

Jan 1, 1985

By T. M. Yegulalp

A numerical model is being developed to assess the enhancement of permeability by improved fracture connectivity by micro-hydrofracturing. A generic two-dimensional percolation model has been developed to test the impact of various field conditions on permeability. Field data from Cyprus Minerals' Mineral Park Mine has been used to establish statistical properties of the observed fracture systems. Results of statistical anlyses of the field data and examples of the use of percolation model are presented.

Jan 1, 1995

By Robert Stefanko

The most perplexing problem that has confronted mining engineers since the dawn of mining has been strata control. For the purposes of this paper, strata control will be defined as control of ground in the immediate area surrounding the, mine opening. To prevent movement of the surrounding strata into underground mine openings, miners have traditionally relied upon some type of artificial supports placed within the openings and located in a manner determined by trial and error from previous experience. Without the means to measure changes of stress in the supports and within the mine structure itself, an evaluation of the efficiency of the supports and mining system was impossible. Strata control thus remained an art with very little application of science. During recent years a revolution has occurred in mining. The modern mining engineer is contented no longer-with trial and error methods but is utilizing all the technological information at his command to obtain a solution to this age old problem. However, serious problems have arisen due to the lack of certain basic knowledge in three important areas: 1, The original stress distribution within the earth strata prior to mining. 2, Redistribution and concentration of the original stresses with mining activity. 3. The properties of rock that are significant in failure and its prevention.

Jan 1, 1960