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By G. P. JADAUN, ANINDYA PAIN, Aditya Rana, SAURAV RUKHAIYAR, N. K. Bhagat

This study compares three different techniques — decision tree, artificial neural network (ANN) and multivariate regression analysis (MVRA) — for predicting blast-induced ground vibrations in some Indian tunneling projects. The models’ performance was also compared with site-specific conventional predictor equations. A database consisting of 137 vibration records was randomly divided into training and testing sets for model generation. The results indicate that the decision tree is best suited to predicting vibrations. Furthermore, the decision tree suggests that the intensity of near-field ground vibrations is mainly affected by the total charge fired in a round, whereas the intensity of far-field vibrations is governed by maximum charge per delay and charge per hole.

By Karl J. Benecke

Though the first patent on a bucket wheel excavator was granted in 1881 in the U.S. this technology was developed in Germany to the high standards of today. However, this development was only possible in parallel with the development of shiftable belt conveyors and boom stackers. The combination of these three types of equipment in the open pits of the Federal Republic of Germany has made lignite the cheapest energy source for power generating, despite the low heating value of German lignite in the order of 8500 kJ/kg (3600 BTU/lb) only. Comparing the costs for fuels used in power generating on the basis of their heating value, the relation between lignite, high quality black coal, and imported crude oil is in the order of 1 to 1.5 to 2.5, hence highly in favour of lignite. These cost advantages for lignite in Germany are due mainly to the concentration of lignite mining in a few high-output open pit mines. The largest one, Fortuna Mine in the Cologne district, produced a, total of 45 000 000 t lignite in 1976. That equals the annual fuel need of a 5750 MW power plant running 7000 hours per year at full capacity. Altogether 95 200 000 bank m3 equal to 200 000 000 t overburden had to be removed to accomplish this lignite output. The largest BWE (Fig. 1) ever built is working in the Fortuna Mine, too. At a digging height of 51 m above crawler level, the total vertical reach in relation to the face conveyor level is 98 m by means of its conveying bridge and loading unit. The hourly output is 10 400 bank m3. Its weight in operation is 13 000 t, its wheel diameter 21.6 m, as high as a 7-storey building.

Jan 1, 1977

By Gill Montgomery

The problems of the domestic merchant fluorspar producers are more or less common with those of many other producers of metallic and non-metallic minerals. For more than ten years the American fluorspar producers have seen an ever lowering price in the market-place for the fluorspar product, while their labor and material costs-continue to mount steadily. This cost-price squeeze has forced out of business all but a few of the merchant producers, and only two captive producers continue to operate, and one of them has announced early curtailment. The prices of domestic fluorspar, of all grades, have declined because of the competition from cheaper foreign imports, principally from Mexico, Spain and Italy. Tariff protection on fluorspar, particularly on the highest or acid grade, has never been sufficient to cover the production cost differential between foreign and domestic fluorspars. Low ocean and barge freight rates have also contributed to the barring of the product of domestic mines from, the major consuming centers along the Gulf and East Coast. Because of the freight disadvantage, all but one or two fluorspar producers in the western states have had to suspend business. More than 80% of the domestic fluorspar is being produced in Illinois and Kentucky fluorspar districts which adjoin on both sides of the Ohio River.

Jan 1, 1964

By S. Odell

The Bureau of Land Management (BLM) has constructed two biochemical reactor systems (BCRs) to treat mining influenced water from the Forest Queen Mine near Silverton, CO. The bioreactors coupled with a natural wetland provide treatment to the Forest Queen Mine drainage. The central objective of this paper is to review the performance of the bioreactors and wetland treatment system. The bioreactors have been in operation for nine years and along with the natural wetland are still removing a high percentage of the influent metals.

Jan 1, 2010

By R. J. Smith

Hornestake's Mclaughlin Mine is the first commercial application of pressure oxidation pretreatment of gold prior to cyanidation. Inherent to the autoclave process are several liquid/solid separations. Flocculant consumption represents a significant portion of the consumable reagent costs at McLaughlan. This paper focuses on the efforts of the Operating, Metallurgy and Engineering groups to improve thickener operation and minimize flocculant consumption. An operating philosophy incorporating feed solids control, increasing flocculant dilution water and minimizing flocculant solution shear has resulted in a reduction in 1986 flocculant costs of $0.054/t ($0.06 st) versus 1985 costs. Additional changes are projected to result in a further cost reduction of $0.20/t ($0.22/.st) in 1987.

Jan 1, 1988

By W. M. Hart

The current Automatic Data Acquisition system developed by some support manufacturers makes it possible to continuously monitor and record changes in leg pressure and advancing ram stroke in every shield, and shearer position at any moment during the mining operation. In order to effectively use the massive data obtained from this system for improving production and maintenance managements as well as providing better roof control at a longwall face, the research currently conducted jointly by West Virginia University and Cyprus-Amax Coal Co. attempts to develop a Longwall Management System for mine operators. The LMS software package runs on a MS Windows NT environment and consists of four sub-systems: (1) Data Interpretation and Analysis; (2) Production Management; (3) Maintenance Management; and (4) Ground Control. This paper presents the details of each sub-system.

Jan 1, 1995

By Lynn B. Hales

The Supervisory Computer System at Cities Service copper mine and concentrator at Miami, Arizona was installed at Pinto Valley in the spring of 1975. Design and specification [l] of the digital system was initiated jointly by key plant personnel at Pinto Valley and staff of Cities Service Research and Development Company. The Pinto Valley digital system [2] may be classified as a supervisory control system of hierarchical design. There are three fully independent satellite computers which retrieve and reduce the raw plant data from each of the three main operating areas - the primary crushing plant, the fine crushing plant, and the grinding and flotation plant. While the three satellite computers are core resident systems, the master computer is a disc-based operating system which also interfaces with a computer controlled on-stream x-ray analyzer system. Figure 1 illustrates the basic system configuration [3]. The software systems required to support a large system are quite diverse and vary greatly in function. The philosophy followed in dividing the software into three categories was designed to: 1) fully utilize existing process knowledge of technical staff; 2) delegate certain software tasks to outside sources already skilled and trained in software development; and 3) maintain final control over the design and operation of each system.

Jan 1, 1976

By C. V. Deutsch, D. A. Silva

The geologic modeling of multiple domains is required for the prediction of mineral resources and reserves. In general, explicit methods have wide acceptance among modelers due to the ability to manually add deemed important trends and geological features into the models. As an alternative, implicit geologic modeling techniques are increasingly adopted to reduce professional time requirements. These methods aim for objective, repeatable and flexible models by replacing the manual time-consuming interpretation of sections with the interpolation of signed distance values. These techniques, however, have been developed for the binary case of two domains at a time. The current paper presents an algorithm that extends the binary case to multiple domains. The method is able to transfer large-scale geological features from data to geologic models. A case study illustrates the benefits of the algorithm and practical implementation considerations.

Jan 1, 2016

By J. L. Weaver

The spiraling rate in phosphate rock demand during the period 1957 to 1967 led producers to expect a continuation of a high growth rate. Consequently they expanded production capacity to meet the expected demand. Both the domestic and the world demand has shown little growth over the past three years. Florida producers operating at less than 75% of installed mining capacity, produce all that their markets will absorb. We expect that the nest few years will bring only a slight improvement in this condition. An increased demand in the domestic agricultural market will be partially offset by a continuing erosion in the export market.

Jan 1, 1972

By J. Sidhom, W. Fourie

"As the mining industry continues to face difficult challenges the need to persistently focus on productivity and utilization of labor and equipment costs will intensify. With these challenges in mind, Joy Global is helping to bring mining performance and analytics to the next level. By evaluating underground haulage, a significant component of the Room and Pillar mining value stream, variables have been identified and sensitivities have been performed to show opportunities to balance and streamline throughput. As a result of applying operational excellence tools to the mining environment, Joy Global is seeking to optimize mining performances by limiting waste, simplifying the process, increasing productivity and machine utilization, as well as removing workers from harm’s way. These days it’s not enough to work harder; mines have to work smarter. Improving efficiency, reducing costs, increasing safety: these are no longer ‘nice to haves’, they are ‘must haves’. Starting with the best products and the right people is a first step, but then what? How do mines take their operations from just OK to being a top performer? By using operational excellence principles aimed at eliminating waste, simplifying processes, automating where possible and removing people from harm’s way. The fundamentals of operational excellence (OpEx) are based upon the DMAIC process, which stands for define, measure, analyze, improve and control. DMAIC is an improvement cycle that helps with, for example, haulage optimization by: defining the issues and problems in the process as well as the areas of improvement; measuring and collecting mining operational data by time study and equipment monitoring system; analyzing through sensitivities and production modelling to determine root causes; then improving the performance and controlling the operation. Joy Global uses Joy OpEx or ‘lean’ principles inside its organization to drive efficiency, but it also helps its customers employ them to achieve new levels of productivity and safety. These same principles can be applied in most situations to streamline processes, improve operations and deliver value. As applied to mining, OpEx is seen as moving the needle on value creation by first identifying the value stream, then analyzing the areas that are not optimized. Once defined, these areas are ‘designed out’ of operational processes to create an automated operational flow. At a US coal mine, Joy Global was brought in to apply Joy OpEx principles to optimize mining and haulage to improve productivity and reduce costs. This multi-phase process started by defining the existing systems challenges to start finding areas for improvement."

Jan 1, 2017

By B. A. Slaker, T. Miller, M. M. Murphy

An underground limestone mine in eastern Ohio was experiencing significant floor heave and roof falls, attributed to high horizontal stresses. Areas of the mine showing floor heave were monitored with roof-to-floor extensometers and photogrammetry surveys to determine the rate and magnitude of heave. Extensometer data were recorded hourly at four locations across adjacent entries while photogrammetry surveys of the floor were performed at the same locations every two to five weeks. A final survey was performed using an I-Site 8200 laser scanner. Following instrumentation, floor heave up to 10.1 cm (4 in.) was measured by the extensometers, photogrammetric reconstructions and laser scanner over a six-month period. The extensometers were biased by the location where they were placed, failing to consistently capture the location and extent of floor heave and cracking. The photogrammetry surveys were not precise enough to capture small magnitude movements. Mining in the area was halted and within several months the floor movement and incidence of roof falls were significantly lessened.

Jan 1, 2018

By Manuel Pérez-Tello, María M. Salazar-Campoy, Óscar Rodríguez-Hoyos

The Kaldo furnace is a type of top-blown, rotary reactor that is widely used for the production of precious metals. During the production of doré, a gas jet of compressed air is injected through a water-cooled lance to impinge upon the molten bath surface in the presence of molten metal and a slag phase. A common problem during operation is the difficulty in controlling the distance that the injection lance can penetrate through the reactor mouth without being splashed by the molten phases. Splashing may produce accretions on the lance surface as well as plugging of the nozzle at the lance tip. An additional problem may occur when the gas jet impinges upon the furnace wall and causes rapid wearing of the refractory linings. Because the conditions prevailing in the Kaldo furnace offers poor visibility to the human eye, its operation mostly relies on the empirical knowledge of plant operators and process engineers. A systematic study in a scale model of the Kaldo furnace under controlled laboratory conditions may be valuable to estimate the maximum penetration distance of the injection lance, and thus help improve the operation of an industrial reactor. From a fundamental perspective, the observation of the basic features of the flow patterns in the scale model may help elucidate the relevant phenomena governing the hydrodynamics in this type of system.

By W. M. Tupper

[The two types of sulfide deposits in the Bathhurst Newcastle area are; (a) epignetic fissure deposits, and (b) massive sulfide deposits. Geological evidence has been variously interpreted to suggest a syngenetic origin, a source bed' origin, or a magmatic hydrothermal origin for the massive sulfide deposits. Sulfides disseminated through the black shales and argillites of the host rocks are enriched in S32 (mean value 22.34, S34. = 5.8 per mil) relative to the meteoritic standard of 22.21, and have a broad spread in range of values. S32/S34 ratios of sulfide minerals from the deposits occur in two distinct groups. The massive sulfide deposits exhibit ratios between 21.88 to 22.05, while the fissure deposits exhibit ratios between 22.18 and 22.21. These results suggest two separate sources for the sulfur, each, however, resulting in magmatic hydrthermal deposition because of the narrow spread of ratios in each group. Granite intrusive into the host rocks of the sulfide deposits have a mean K/A age of 386 ± 10 M.Y. Lead minerals in the sulfide deposits have a mean nodel lead age of 370±20 M. Y. Thus the lead minerals and the granite bodies were emplaced during the same major orogenic event. Sulfide minerals from magmatic hydrothermal deposit have a very narrow range of S32/S34 values, as do those of the Bathurst area. It seems reasonable, therefore, that well homogenized magmatic hydrothermal solutions are the most logical source of the sulfide deposits. Furthermore, the homogeneity of the lead isotopic abundance data gives strong independent evidence that the ores are of a magmatic hydrothermal origin.]

Jan 1, 1960

By L. F. Zeiler

In the past, health concerns in coal mines have primarily centered on those elements which have been essentially inherent to the mining environment. These would include respirable coal mine dust, respirable crystalline silica, excessive noise levels, and diesel exhaust particulates. Commercially-available chemical products are prevalent on mine property. These potentially toxic materials are chemical formulations that can degrease, clean, and lubricate metal parts, separate coal from rock in float/sink operations, and aid in roof consolidation, among other uses. As the general public has become more aware of the hazards of chemical exposures, miners have likewise become more concerned about working with an ever-expanding variety of chemical products on the job. Often, product or chemical specific hazard communication training is inadequate or ineffective, and miners do not know exactly what the ingredients are in the products they handle, or the health hazards involved with their use or misuse. Currently, the Mine Safety and Health Administration (MSHA), by law, enforces 1972 Threshold Limit Values (TLV). MSHA is making preparations to adopt new personal exposure limits for enforcement. The values given throughout the article are 1994 TLV's and are not enforcement standards, but are used for discussion purposes. They reflect the current scientific thinking regarding personal exposure to these chemical agents. An overview of these products is presented, and the potential health hazards associated with their use are discussed. Controls needed to prevent overexposures, such as proper handling procedures and personal protective equipment, are covered. Methods used to collect and identify contaminants are presented.

Jan 1, 1995

By Colin Connors

Cemented rockfill is a key component in the success of underground mining at the Jerritt Canyon Joint Venture. The Murray and SSX mines are characterized by relatively poor rock mass quality, and the goal of complete mining recovery makes maintaining a high quality backfill product vital to the safety and efficiency of the mining operations. A large portion of the ore production from the Murray mine originates from drifting under backfill. Modelling studies performed to investigate induced loading of the backfill were used to develop engineering specifications for the backfill material. Operations history has shown an almost 100 percent stability of the backfill when mining is carried out beneath it. The volume of backfill required each year (approximately 300,000 tons) and the required cement content have a significant impact on the total mining costs. The potential for cost savings associated with higher replacement of cement with Type "C" fly ash and the implementation of a backfill strength management strategy were therefore evaluated.

Jan 1, 2001

By Reinhard Gertl, Maximilian Weithaler, Harald Kammerer, Juan Pablo Muñoz, Juan-Carlos Rueda

The Guillermo Gaviria Echeverri tunnel and its access roads project in Antioquia, Colombia is a mega infrastructure project that includes a road network with the longest tunnel in Latin America and several short tunnels, the latter being the focus of this study. The design of the project required careful consideration of several special factors, such as the tunnels’ steep slopes of up to 5%, high fire load of 100 MW, bidirectional operation, and short lengths that make it difficult to place ventilation equipment. The combination of all these parameters cause a challenging design problem for the ventilation systems and smoke control of the short tunnels. To address this challenge, a risk assessment study was conducted to support the design of a new and innovative ventilation strategy that deviates from relevant guidelines and standards, like the Austrian RVS [1][5][6] or the German EABT [8] in order to provide a customized solution for this particular project. This strategy resulted a cost-effective solution, that allowed a reduction in the number of required jet fans and at the same time reaches or reduces the risk level compared to traditional ventilation strategies.

Jun 13, 2023

By Steve Kral

"Repairing and replacing the nation’s aging and crumbling infrastructure has become a major issue with the American public. It is no secret that the upkeep of roads, tunnels, bridges, and water and waste water facilities has been neglected for decades. Cities, states and towns across the United States are now grappling with these issues, ones that will take decades and billions of dollars to fix.Because of this infrastructure issue, the North American tunneling industry is flourishing. Cities across the country are looking to go underground to alleviate traffic issues, transporting water and waste water to more people in more efficient ways.In October, the seventh annual Cutting Edge conference was held in Atlanta, GA. Put on by the Underground Construction Association of SME and Britain’s Tunnelling Journal, about 175 tunneling and underground construction professionals from around the world attended. Attendees included owners, designers and contractors. An accompanying exhibit included 28 companies.The theme of the two-day conference was Advances in Tunneling Technology. Speakers examined the latest advances in tunneling technology, its methodology and how these advances can be harnessed to assist upcoming major tunneling projects. The conference featured a tailored, high-end, single-track program of subject-specific presentations that focused on innovation and practical experience. Two in-depth panel discussions at the end of each day were also included.Patricia Mulroy was a keynote speaker on Monday. She is senior fellow for climate adaptation and environmental policy at The Brookings Institution. Like many others, Mulroy believes the U.S. infrastructure in in a state of disrepair. But, she said, no one wants to talk about it. “We need to have a conversation about infrastructure. We cannot be afraid to talk about building it and the cost.” For this to happen, though, the nation needs leadership."

Dec 1, 2018

By B. T. Lusk, J. J. Silva Castro

Currently, there are several methodologies to assess ground vibrations from blasting. Of all available methodologies, one that is becoming more important is the waveform superposition or signature hole technique. This technique is based on a signature waveform assigned to each hole to build the complete waveform for the whole production blast, using the convolution between the time initiation sequence and the signature hole waveform. In the basic methodology of the signature hole technique, the waveform hole-to-hole is assumed to be the same. Several studies and field tests have proven that the waveform hole-to-hole, even in ideal rock mass conditions (rock mass with little or no joint system), changes. In addition to distance or confinement, other factors that could change the waveform hole-to-hole include different geologic paths from the source to the monitoring point and a different energy output of each hole, due to hole loading, explosive composition and/or contamination, priming, etc. These factors result in varying waveforms generated for each hole, making the waveform produced by each hole a somewhat random process. There is available in the literature some proposals to include variability in the waveform hole-to-hole, but the parameters involved are complex and difficult to estimate. In this paper, the variability in the signature waveform hole-to-hole in a blast event was recorded through a field test, and a proposal to include signature waveform variability to develop an equation based on the Fourier series is presented. This methodology is the basis for a future signature hole analysis using a Monte Carlo scheme, taking into account the variation of the amplitude and the frequency content of the waveform hole-to-hole in a production blast event.

Jan 1, 2012

By G. E. McClelland

Agglomeration techniques have been successfully applied to commerical heap leach cyanidation operations for the recovery of precious metals from low-grade ores, mine wastes, and tailings. The major parameters important for successful agglomeration pretreatment of these feed materials are discussed. Several commercial agglomeration-heap leaching operations are described. Two of the operations converted from conventional heap leaching to agglomeration-heap leaching after coventional heap leaching proved unsuccessful. Heap performance before and after agglomeration is discussed. A fairly recent operation that began production using agglomeration-heap leaching technology is also described. Two operations that processed milled tailings by agglomeration are discussed. The tailings feeds could not have been economically processed by means other than agglomeration-heap leaching.

Jan 1, 1986

By M. S. Davis

The Tek Process can produce masonry products such as bricks, roof or wall tiles, and block from virtually any inorganic waste. In the process the aggregate raw materials, portland cement, water and common chemicals are first mixed together; then mechanically subjected to several thousand pound pressure per square inch. This causes a novel chemical reaction between the cement, chemicals and water; producing the "patented" Tek adhesive binder which holds the aggregate together in a stone-like mix. Simultaneously, the desired product shape is formed. The building modules can have strengths of 8000 p.s.i. (pounds per square inch) with completely sound aggregates utilizing air curing for a period of 28 days. With most aggregates, 3000 p.s.i. is achieved within 24 hours. Eventual strengths usually exceed 5000 p.s.i. with almost any raw material. Water absorption ranges from 5-7.5 percent. Both absorption and strength figures are superior to the most rigid of any and all A.S.T.M. specifications for the highest quality bricks. In most locations, the product (when brick shaped is called Tekbrik) can be produced significantly more economically than can comparable grades of clay or other bricks, be- cause almost any inorganic waste materials or pollutant can be used as a raw material. The process results in a lower manufacturing cost as compared to clay bricks; fuel cost to operate a clay kiln represents a substantial portion of the total cost. Capital expenditure for a Tek plant also is lower due to the large investment in clay kilns. Transportation savings also are important, clay brick factories must be very large because the kilns are uneconomical unless they are large. Most bricks are manufactured at the sites of clay deposits in relatively uninhabited areas. The cost of transportation to the job site represents a considerable percentage of the selling price.

Jan 1, 1974