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By V. G. Medina

The 15 000 t/d La Coipa mine initiated operation in July of 1991. The complex consists of a conventional, open-pit mining operation and a mill employing cyanide leaching with Merrill-Crowe gold and silver recovery. The process plant includes a primary crushing circuit, a 15,000 t (live) covered stockpile, a semi-autogenous mill/ball mill/crusher or SABC grinding circuit, a leach circuit, a belt filtration/washing circuit, a zinc precipitation circuit and a "dry" tailing disposal system. The process plant is described in detail with major design considerations used in the selection of the processes and equipment. The unique methodology employed in the disposal of the filtered tailings is also described.

Jan 1, 1992

By J. A. Murray

Maintaining satisfactory air quality in electro-winning tankhouses has been problematic and costly, particularly as plant operating current densities have increased. Conventional approaches, including the use of beads, hollow spheres, surfactants and coalescer devices, have not proved completely effective, requiring that powerful ventilation systems be installed. As workplace and environmental regulations become more stringent, containment of the acid mist at its source is more attractive. An electrode cap system based on this approach has been developed and tested in two commercial copper electrowinning tankhouses. The design, development, installation and cost of the new electrode cap system are described.

Jan 1, 1996

By P. M. Krishna

A five-year effort by the ASTM subcommittee E10.14 on Uranium Resource Evaluation has culminated in the approval of E901-82, Classification System for Uranium Resources. The standard classification was prepared with participation of representatives from the Dept. of Energy, the Dept. of Interior's Geological Survey and Bureau of Mines, utilities, and consultants. The classification of a resource is based on level of knowledge and the economic producibility of the resource at a given time. Alpha-numeric identifiers are used rather than words to avoid confusion with existing terms, definitions, and classifications. An effort is underway to develop estimation criteria to guide users in classifying a resource according to the above format.

Jan 1, 1983

By M. Z. Emad, M. U. Khan, A. ur Rehman

Stemming plugs are used as an accessory in drilling and blasting industry. They supplement conventional stemming material (i.e. drill cutting) with retention of gases in the drill hole that result in better fragmentation of rock and improved explosive utilization. Better fragmentation and explosive utilization along with economic benefits enhance efficacy of the project. Incorporation of stemming plugs in drilling and blasting industry is in exercise for about thirty years. The efficiency of stemming plugs is a key factor in their rising induction in mining industry. Different studies have been conducted on the economic viability of these plugs. The focus of this paper is the selection of stemming plugs for a bench blasting operation and the examination of blasting operation efficiency based on ergonomics and human factors. Three types of stemming plugs were evaluated during multiple blasts at a limestone quarry. Their performance was evaluated using split desktop software. Based on the human factors plastic molded stemming plug (stemming plug-1) was found to be the best among all selected plugs. INTRODUCTION Surface mines and quarrying operations heavily depend on bench blasting to achieve high volumetric targets and production demands. Use of explosives is the most economic method adopted for rock breakage and movement. Extensive research had been performed to enhance explosives energy utilization. This include changing the drilling pattern, application of air decks, stemming plugs, and use of other supportive devices. Optimization of explosive energy has been a major concern in those mines that rely on drilling and blasting operation to carry out main production. Due to continually increasing cost, efficient mining demands, and associated hazards of using explosives, it is necessary to utilize explosives at their best. Efficiency of a blasting operation is generally evaluated by the fragmentation size. From post blast conditions at blasting site to efficiency of processing plant, anything can be affected due to improper blast resulting in bad fragmentation. Better fragmentation is necessity for better operation of the system along with consideration of the safety of operation, environmental issues and related costs. For developing a blast design, an engineer should always attempt to minimize the cost of operation without compromising with acceptable technical and safety necessities [1]. Blast performance is dependent on many different factors associated with the process. These factors have been gauged as blast geometry, explosive specification, and rock mass properties [2]. Similarly, in 2013 Mohammad et al. concluded that fragmentation dynamics depends on blast hole diameter, primer, spacing, stemming, burden, and delay timing for blasting operation [1]. At the work site where this study was performed, blast holes were filled by drill cuttings and muds to help in confining gases. In a blast hole, gas confinement helps in better rock fragmentation along with reduced flyrocks. This practice is most common in many countries including Pakistan. Due to lack of homogenized particle size, the effectiveness of confinement is variable and majorly based on the size of stemming. Extremely small sized drill cuttings often result in hole blow out along with flyrocks from the collar. This improper blast energy will result in poor blast, bad impacts on environment, and reduced operational efficiency. In addition to the stemming material, the length of stemming is also a prime consideration. The decrease in stemming length will increase the quantity of explosive in the blast hole and an increase in stemming material generally improves stemming performance.

Jan 1, 2019

By Joseph D. D?Annunzio

The report on cut and cover construction as assembled by the Organization for Economic Co-operation and Development covered 17 different countries based on a total of just under 400 individual replies of which about 30% of the replies were from the United States. In general, the review of replies to the questionnaire led to the impression that cut and cover construction is a very inadequate method which needed many improvements. This unfavorable judgment, however, resulted in the manner in which questions were asked rather than in the method itself, It can be concluded that the cut and cover construction method has proved itself as an excellent method and that it has reached a high degree of technological perfection, but inadequacies stilt exist, and for purposes of complete evaluation, comparisons with mining tunnelling methods should be carried out. The principal problem in cut and cover construction is the interaction during construction between the construction process and the existing use of the surface and subsurface environment. The greatest impediments to cut and cover construction have little to do with the physical works being constructed, but more with creating a site in which the work can be performed. Utility relocation, traffice maintenance, and protection of existing structures are major problems for the construction contractor, and too frequently receive insufficient attention in preconstruction planning and design. Some OF the areas in which research should be undertaken are as follows:

Jan 1, 1970

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 R. K. Agarwal

In this paper a simple three-layered medium is considered. A circular hole is centrally located in the intermediate layer. The layered sheet is loaded uniaxially perpendicular to the stratification. The Young's modulus of the intermediate layer is lower than that of the outer layers. The stress distribution around the circular hole in a stratified medium is significantly different when compared to the case of a continuous homogeneous medium. The distribution depends upon the ratio of the height of [the] intermediate layer and [the] hole diameter. A comparison of stress the distribution and procedures for preparation and testing of [the] model are given. The potential of the technique is outlined.

Jan 1, 1968

Table A. Conversion of English to SI Units Table B. Strength Properties of Rocks Table C. Engineering Properties of Rock Table D. Properties of Common Minerals Table E. Material Properties and Characteristics Table F. Heat Value of Various Fuels Table G. Geometrical Relationships and Mensuration Formulas Table H. Standard Sizing and Meshes Table I. Ship Measures Table J. International Atomic Weights Table K. Time Value of Money Factorsfor Discrete Compounding

Jan 1, 2008

By O. A. Velasquez, A. R. Kumar

"Dust generated on underground mechanized coal mining faces is a health and safety hazard. Continuous miners deployed underground usually have an integrated flooded-bed dust scrubber mounted onto the machine that arrests the generated dust from close to the face and cleanses the air around it. However, the impingement screen might get clogged depending on the coal seam being worked. This necessitates the cleaning of the screen which in turn, reduces the overall availability of the scrubber and, hence the continuous miner. A novel non-clogging screen has been developed at the Department of Mining Engineering, University of Kentucky. The proposed impingement screen is built up of three individual aluminum screen units 1.5 mm thick and separated by 3 and 2 mm respectively. The screens have long vertical slits measuring 6 mm. A water spray continuously keeps the screen wet and provides for the filter element to arrest the dust particles. The slits force the dust-laden air to make sharp turns. The dust particles cannot change directions rapidly, impact one of the three screens and are separated out based on their momentum. Preliminary computational fluid dynamics (CFD) models have indicated significant cleaning efficiencies in the respirable range at the expense of much lower pressure drops. Results indicated by CFD models and supported by laboratory experiments have been discussed in this paper.ACKNOWLEDGEMENT The authors acknowledge the National Institute for Occupational Safety and Health (NIOSH) for funding this research. Dr. Thomas Novak, Professor of Mining Engineering, is also acknowledged for his continued support and encouragement. INTRODUCTION Continuous miners are ubiquitous in coal mining around the world. The miners are operated against bling headings, ensuring adequate flow of air at the face could be difficult. The minimum requirement of ventilation airflow quantities at those coal faces are legislated to dilute dust generated to harmless levels. New dust rules promulgated recently have further called for lower exposure levels of personnel working underground (Courtney) (MSHA, 2014) (NIOSH, 2010). Water sprays are also installed at strategic locations and serve as powerful air-movers. The sprays capture some amount of dust generated while cutting. In addition to this, usually, all continuous miners are equipped with a flooded-bed dust scrubber as shown in Figure 1 to capture the dust from close to the extraction drum (Chao & De-sheng, 2000) (Wala, Vytla, Huang, & Taylor, 2008) (Organiscak & Beck, 2010)."

Jan 1, 2018

By E. Martinez

A heavy mineral sand sample was tested containing 13% heavy mineral consisting of rutile, zircon, and ilmenite. Eleven tests were run at a mill site with a Mineral Deposit Limited MG 4 spiral to determine the effect of the addition 0; magnets to the spiral compared to conventional gravity separation. Different magnet configurations and field strengths were tested. Optimum results were obtained with the spiral retrofitted with magnets. The heavy mineral content of the concentrate was increased from 55.5% in the control to 64.2% with the magnets. The 8.7% improvement in heavy mineral recovery was due not only to the weakly-magnetic ilmenite, but also to increased recoveries if the non-magnetic zircon and rutile. The increased recoveries were achieved with no loss of concentrate grade.

Jan 1, 1992

By N. S. Tanious

This paper summarizes the results of an investigation into possibly the largest coal pillar failure in the USA. The newly opened drift mine is located in Southeastern Kentucky and worked an 11 feet thick coal seam, all other mines in the District worked seams 4-5 feet thick. The initial mine development consisted of 14 main entries (Fig. 1) which were driven in two sets of 7, under increasing depth of overburden. As the left seven entries came under deeper overburden the pillar ribs began sloughing which caused many of the concrete-block ventilation stoppings to crack. The mine management stopped the advance in the left seven and continued with the right seven entries. During the spring of the following year development resumed in the left seven, rib sloughage occurred again and this time severely cracked many stoppings and many were totally disintegrated from the excessive deformation. Within few weeks the sloughage was so heavy that many of these entries behind the active face were filled with piles of sloughed coal slabs. When the face reached a depth approximately 1150 feet, the sloughage became a slow, massive squeeze. The entry convergence (closure) reduced their height from 11 to 7-8 feet and the squeeze spread back to shallower depth covering an area roughly 300 pillars.

Jan 1, 1989

Lingering effects of the 1990 oil shock that included overbuilding and corporate and individual financial distress caused the Gross Domestic Product to fall slightly to $5.67 billion (US billion = l09). With 254 million people - 697,000 in mining and petroleum - the US has more than 100 million dwelling units and 190 million licensed motor vehicles. New private housing starts fell 15% to one million units. New car production fell 11 % to 5.4 million units. Truck and bus production fell 8% to 3.4 million units. The inflation rate was 3%, while the prime rate of interest was 8.5%. The Producer Price Index (1982 = 100) changed as follows: -fuels and related products and power down 1% to 8l, • metals and metal products down 2% to 120, • chemicals and allied products up 2% to 126, and • non-metallic mineral products up to 2% to 117. Energy Imports of crude and refined petroleum, costing $50 billion, fell 5% to 2.8 billion bbl. Domestic petroleum production rose 1% to 3.6 billion bbl. Petroleum supplied about 39% of US energy, natural gas 24% and coal 22%. The National Energy Strategy was announced in February 1991. Its purpose is to encourage domestic production of fossil fuels and nuclear and renewable energy and to stimulate efficiencies in use. Congress continued to debate the strategy and took no action. Coal production fell 3% to 902 Mt (994 million st). About 60% of that came from surface operations. Seventy-eight percent of the total was used to generate electricity and 3% was coked.

Jan 1, 1992

By Raphael G. Kazmann

Water occupies a dual role in our industrial society. It is the indispensable raw material, essential to life itself. It is equally an industrial nuisance, interfering with the production of industrial minerals, making construction difficult, flooding valuable land, and generally producing problems because it is in the wrong place at the critical time. The legal position of water as a nuisance, and the counter measures to be taken, have been well established procedures for determining the responsibility for damage caused by water, and the organization of drainage districts and flood control and levee districts have been legally tested many times. Thus there is rather adequate legal doctrine concerning water, the common enemy. But recently efforts have been made to regularize the position of water as a useful, industrial, commodity. Such laws are not new to the West, where the doctrine of appropriation for beneficial use is slowly becoming the water law. Elsewhere the University of Michigan has produced a "model" water law and efforts are being made to induce all of the states to use this law, or a slight variation of it, as the basis for legislation. There are many serious criticisms of the proposed "model"-law, and the writer strongly opposes many of the provisions. But the fact remains that water is, in itself, so useful and essential that laws have been, and will be, passed to insure the orderly development of our water resources and to prevent waste. The, most important aspect of these "water-use" laws is that, wise or unwise, the existing laws and the proposed laws have been "water oriented". "Water oriented" means that it has been tacitly assumed that the beneficial use of water, either surface water or ground water, is the overriding consideration.

Jan 1, 1960

By T. W. Beck

Drilling into coal mine roof strata to install roof bolts has the potential to release substantial quantities of respirable dust. Due to the proximity of drill holes to the breathing zone of roof bolting personnel, dust escaping the holes and avoiding capture by the dust collection system pose a potential respiratory health risk. Controls are available to complement the typical dry vacuum collection system and minimize harmful exposures during the initial phase of drilling. This paper examines the use of a bit sleeve in combination with a dusthog- type bit to improve dust extraction during the critical initial phase of drilling. A twistedbody drill bit is also evaluated to determine the quantity of dust liberated in comparison with the dust-hog-type bit. Based on the results of our laboratory tests, the bit sleeve may reduce dust emissions by one-half during the initial phase of drilling before the drill bit is fully enclosed by the drill hole. Because collaring is responsible for the largest dust liberations, overall dust emission can also be substantially reduced. The use of a twistedbody bit has minimal improvement on dust capture compared with the commonly used dust-hog-type bit.

Jan 1, 2014

By J. Larsson

In the pursuit of increased safety the mining industry has worked to develop systems for remote control and autonomous operation of both stationary and mobile equipment. This paper reports on a newly developed system for teleoperation and autonomous tramming of LHD (Load-Haul-Dump) mining vehicles that not only increases the safety of the operators, but also has the potential to increase productivity.

Jan 1, 2010

By P. Rusin

A new bacterium, Thiobacillus cuprinus, can extract copper from chalcopyrite as rapidly as T. ferrooxidans. On solution with and without nutrient amendments and bacterial growth media were supplemented with T. ferrooxidans or T. cuprinus in shake flask studies. Both species extracted -42% of the copper using growth media. In one case, T. cuprinus solubilized approximately twice as much copper as T. ferrooxidans utilizing a seeded On solution. Thiobacillus prosperus also oxidizes chalcopyrite and tolerates high chloride concentrations. These sulfide-oxidizing bacteria are representatives of the mixed microbial community found in sulfide dumps. Rates of biological copper extraction from sulfide ores, using the native microbes, have been significantly enhanced by amending On solution with PGM.

Jan 1, 1994

This paper presents the results of column flotation of a fine feed sample of Florida phosphate. A central composite design is used to study the main and interaction effects of parameters affecting column efficiency. The statistical design is also used to determine the optimum conditions. The results indicate that, depending on the experimental conditions, it is possible to achieve a concentrate of high grade and recovery. A concentration of 15 ppm of non-ionic frother is found to be enough to maximize the recovery at the pH of 9.5.

Jan 1, 1999

By S. Tafazoli, D. Cooper, I. Bell, S. Nouranian, B. Sameti, M. Ramezani

"Image-based rock fragmentation sensing in mines and quarries includes an important rock boundary delineation step, commonly referred to as rock segmentation. This paper presents an artificial intelligence-based solution to this challenge. The proposed technique encodes prior knowledge of previously analyzed images into mathematical/statistical models. Human-labeled images are used as inputs to train neural networks through an optimization process. The networks can then be used in real time for rock delineation. To build the models, special deep artificial neural networks are used as a pixel classifier. The proposed classifier labels each pixel (edge, rock or fine) by analyzing a plurality of pixels within the image. Advances in machine learning allow the network to contain many parameters. The increased number of parameters is a strong factor in the classifier’s ability to correctly classify each pixel. Deep learning-based segmentation, combined with 3D imaging followed by post processing, provides a unified fragmentation sensing solution. Results from automatic segmentation are compared to human labeled segmentation using the percentage passing curves for 64 rock images. INTRODUCTION Mines and quarries can see significant productivity and performance benefits by controlling material sizes (McKee, Chitmobo, & Morrell, 1995; Sellers & Gumede, 2012). During the past decade, image-based fragmentation analysis has been applied to estimate rock size distributions in order to optimize procedures in mines and quarries. Using a roving camera and operator assisted analysis Maerz, Franklin, and Coursen (1987) measured the size distribution of the blasted rock and eliminated the need for manual sieve analysis. Since then, many others have introduced automated and manual methods for fragmentation analysis and improved upon existing approaches (Girdner, Kemeny, Srikant, & McGill, 1996; Smith & Kemeny, 1993; Palangio, Palangio, & Maerz, 2005; Tafazoli & Ziraknejad, 2009; Raina, 2013). In image-based fragmentation, rock boundaries are identified in the image, and an image scaling is applied to transform rock pixel sizes into real world dimensions. Usually geometric references, such as regularly shaped objects (discs and basketballs) (Siddigui, Ali Shah, & Behan, 2009), or the known size of an excavator bucket (Zeng, Chow, Baumann, & Tafazoli, 2012), are used to determine the proper scaling factor. In recent years, 3D imaging and sensing have also been incorporated to improve rock delineation. Specific methods include using camera-laser combinations and stereo imaging to measure rock fragmentation on conveyor belts (Noy, 2013; Thurley, 2013; Dislaire, Illing, Laurent, & Pirard, 2013) as well as portable fragmentation analysis devices with 3D imaging sensors (Sameti, et al., 2014)."

Jan 1, 2018

By S. Anderson

Advances in inexpensive computer automation led to the development and utilization of a computerized ore control system at Cyprus Coppers tone Gold Mine near Parker, Arizona. These new ore control practices improved accuracy, performance, and productivity of the ore control effort. An automated system for data collection, including bar coding of blast hole samples, laboratory analysis, data management, grade estimation, cut delineation, and ore zone stakeout, plays a major role in ore control practices. This is of particular interest because of the large amount of blast hole information being processed, analyzed, and reported daily.

Jan 1, 1991

By G. Keizer

Cortez Gold Mine (C.G.M.) is located in Lander County, Nevada, approximately 80 miles southwest of Elko, Nevada. It is accessed via Nevada State Highway 306 south from Interstate 80. This operation is a joint venture between Placer Dome U. S. Inc. (60% operator) and Kennecott Corporation (40%). The claims which supply oxide and refractory ore feed to the Cortez milling facility are located in both Lander and Eureka Counties. These include the Cortez and Horse Canyon deposits all operated by C.G.M. Joint Venture. Other deposits outside the C.G.M. claim area include; Fire Creek, Buckhorn, Gold Bar and Tonkin Springs. These deposits all occur along the Battle Mountain/Eureka Trend.

Jan 1, 1993