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By Jose F. T. Agapito

The mining engineer must be able to predict the structural behavior of the rock around underground openings so that he can answer questions relating to safety and economics. With the present status of rock mechanics knowledge, exact predictions cannot be attained and approximate idealizations are made. As a first approximation, structural design makes use of theory, laboratory testing of rock properties, and available experience from excavations in similar rock formations. However, realistic design can usually be obtained only after in-situ observations and measurements are made. After all the information is collected, judgement and experience play a most important role in the final formulation of the design. This paper describes part of a geotechnical program which was instrumental in obtaining information for the design of large oil shale pillars. The work was carried out during 1971 and 1972 in the experimental mine of the Colony Development Operation. Colony is an oil shale venture formed between Atlantic Richfield Company, Operator, The Oil Shale Corporation, Cleveland-Cliffs Iron Company, and Sohio Petroleum Company to conduct research and development in mining and retorting of oil shale, The property is located in the southern edge of the Piceance Creek Basin in northwestern Colorado, approximately 250 miles west of Denver (Figure 1) . Mining was conducted by the room-and-pillar method in a 60-ft high portion of the Green River Formation at a depth of 600 to 850 ft, Pillar dimensions are approximately 60 ft by 60 ft. The mine site is in the eastern face of the canyon containing the Middle Fork of Parachute Creek, The distance from the mine to the side of the mountain varies from 500 to 1,200 ft, and its height above the stream floor is approximately 700 ft.

Jan 1, 1974

By Lee W. Saperstein

P.L. 95-87 contains explicit demands for land-use planning in its reclamation and designation sections. Both sections require recognition of local land-use plans; however, the sections are not well integrated. Accommodations to these planning requirements may be found in suggestions based on British mineral planning practice. Better links can be created among local land-use planners, the state's permitting authority and designation office, and mine designers. Mining companies should take more interest in local land-use plans and in resource inventories; states should consider devolving to local government responsibility for accepting mine permit applications and designation of unsuitability petitions.

Jan 1, 1982

By I. J. Duckworth

Due to improved, stringent safety regulations, many modern road tunnels are statistically safer, per kilometer, than above ground roadways. However, the public perception and reaction in the event of a serious tunnel fire is very different to that associated with a surface incident. Vehicle fires in road and rail tunnels are recognized to represent an immediate and extreme danger to the patrons of those systems. Unlike workers in the mining and civil construction industries, the general public are neither trained nor equipped to fight fires or evacuate under deteriorating smoke conditions. Accordingly, for the majority of modern transportation tunnels the ventilation infrastructure is sized on the requirement to control the combustion products from worst-case fire scenarios and to provide a tenable evacuation route for the tunnel users. It is common for these same emergency ventilation systems to be employed, often in a reduced capacity, for other operating modes such as the dilution of pollutants during congested traffic conditions. This is one of the fundamental differences to mine ventilation, where primary ventilation systems are not typically sized based on fire scenarios. This paper presents an overview of the subject of fires in vehicular tunnels. This includes a brief history of major transportation tunnel fires followed by a discussion on the resulting legislation and standards that govern the design and operation of tunnel emergency ventilation systems. A summary is provided on the common criteria, theory, and design techniques that are employed during tunnel emergency ventilation systems design. Information is provided on fire detection and suppression, with a discussion on the growing acceptance of wet suppression as a means to mitigate major fires in road tunnels worldwide.

Jan 1, 2009

By A. Eccles

Phase designs are the foundation upon which all open pit mine sequence optimizations and budgets should be built. Unfortunately, at times, mine engineers skip the step of developing realistic pit phase designs - designs that include access ramps and mineable widths. Without mineable phase designs, their optimized schedules are based on theoretical pit shells or ?quick-and-dirty? plans with no ramps. The output from such optimizations is almost always overly optimistic. Without mineable designs, the production estimates are misleading, because they overestimate ore, and underestimate waste stripping requirements. Worse yet, when plans are not based on realistic phase designs, they can point to exactly the wrong decision in feasibility studies (i.e. ?go? when it should be ?no-go?). This paper discusses the importance and features of good pit phase design, and demonstrates the pitfalls of relying on optimized production sequences that are not based on properly designed pit phases.

Feb 27, 2013

By Jr. Wallace

This paper describes an analysis performed to determine the cool-down time of drifts in the prospective commercial nuclear waste repository in volcanic tuff at Yucca mountain, Nevada. Two emplacement methods are currently being considered at Yucca mountain. The reference configuration stores the high-level waste in short vertical boreholes, and the alternative configuration stores the waste in long horizontal bore-holes. After emplacement operations for each emplacement drift are complete, the drift will be closed off from continuous ventilation. Given time, the radioactive decay of high-level waste will increase the rock temperature around access and emplacement drifts. Air cooling may be required to re-enter these drifts. The paper discusses the analysis procedure and computer programs used to evaluate the time to cool a drift to acceptable environmental conditions 50 years after emplacement of high-level waste. Key assumptions to the analysis are presented. The results of the study show that cooling either vertical or horizontal configuration emplacement drifts is possible in a reason-able period of time.

Jan 1, 1988

By Kenneth Maser, Douglas W. Ounanian, Joseph S. Boyce

Foster-Miller Associates, Inc. (FMA), under contract to the Department of Transportation (DOT) and the Urban Mass Transit Administration (UMTA), is currently developing an Extruded Tunnel Lining System (ETLS). The ETLS would reduce ground support costs in machine bored tunneling by eliminating the need for temporary support, and by slip-forming the final concrete lining directly behind the Tunnel Boring Machine (TBM). The system can advance at variable rates, from 0.6 to 3.7 m (2 to 12 ft) per hr, by combining three systems: a very high early strength concrete, continuously produced and delivered by a concrete process system; a slipform/bulkhead system for supporting the concrete prior to strength gain and exposure; and a control system for form/bulkhead alignment and concrete process control. Large-scale tests are planned to demonstrate the system in a 3 m (10-ft) diameter steel "tunnel".

Jan 1, 1981

By W. S. Fyfe, G. Southam, T. J. Beveridge

Bacterial populations play an active role in mineral weathering in subsurface and near-surface environments e.g., supergene enrichment of Cu at Morenci, AZ. An invitro bacterial biofilm model was used to examine the interaction between Sporosarcina ureae and ionic gold(which is toxic) or amino acid-gold complexes in gold mobility. The immobilization of ionic gold was between80-90% for 1 week but as the available, cellular reactive sites became saturated immobilization decreased to 14%within 2 weeks. In the asparagine-gold system, gold immobilization occurred at a high rate (80-90%)throughout the experiment with limited toxicity towards Sporosarcina ureae.

Jan 1, 1999

By Lynn B. Hales, Randy A. Ynchausti

There is a large economic driving force associated with improving metallurgical performance in mineral processing plants using process control. Because of this and other benefits, control systems of the future will develop towards more sophisticated user friendly computer based systems that use powerful software analysis and control techniques. Auto-tuning, adaptive control and process models will gain expanded use because of their transparent availability to the system designer. Control of individual unit operations will be optimized and coordinated through expert systems that monitor economic conditions and management directives and direct operations accordingly. Plant areas, considered cost centers for years, will be integrated into plant-wide control systems for economic control and optimization. New control hardware, process sensors, control strategies and software development tools will be presented, as well as an overview of the economics driving the continued development of advanced process control systems.

Jan 1, 1993

By John Oskam

In 1873 Barton tines Corporation mining Garnets for Abrasives. From providing bulk Garnet Concentrate the technology has advanced to the sizing and classification of micron sized particles utilizing a Barton process. Processing of Garnet involves extensive quality control at all steps, first to insure product purity and secondly to insure the correct size range. Barton Mines produces about 30 different sizes of Garnet products to lead the world in the manufacture of technical abrasive Garnet. This paper will examine the present technology of Garnet Abrasive Manufacture and the specification to which the sizes are produced as well as some of the markets served.

Jan 1, 1980

By Henry R. Tiedemann, William H. Hansmire, Harvey W. Parker

Although the use of precast concrete segments for tunnel linings has been common for many years in Europe, acceptance of this type of lining has been slow in the United States. This paper explores the cost, design, and construction considerations of concrete segmental lining with a view to promoting its use in this country when favorable conditions exist. The different perspectives held by owners, designers, and contractors are discussed. In addition to cost, other considerations include previous design and construction experience, size, length and function of tunnel, watertightness, and liability. Cost comparisons are made to traditional ground support and lining. Under favorable conditions, the use of precast concrete segmental linings can be technically feasible and cost effective.

Jan 1, 1987

By Moussa Wone

The Washington, DC Water and Sewer Authority (WASA) has implemented facility planning for the Anacostia River Projects portion of a program to bring its Combined Sewer System (CSO) into compliance with federal water quality regulations by 2025. The program includes approximately 19 kilometers (12 miles) of deep CSO storage/conveyance and flood relief soft ground tunnels, construction, vortex drop, overflow, maintenance and air release shafts, as well as near surface diversion structures and conveyances. The Project encompasses major technical and non-technical challenges including completion under a federal consent decree schedule, construction within the confines of heavily developed urban areas, difficult ground conditions, major infrastructure crossings, and close coordination with several major public agencies. This paper discusses the planning stage considerations related to the geotechnical investigation program, discusses obstructions that influenced alignment selection, and provides two examples of preliminary estimates of settlement induced ground movement due to the tunnel and shaft construction.

Jan 1, 2008

By D. R. Nagaraj

Secondary Ion Mass Spectroscopy (SIMS) was used to study copper ion adsorption, and its effect on subsequent sulfide collector adsorption, on pyrite and pyroxene minerals under flotation related conditions. Copper was found to adsorb on both of these minerals and cause enhanced sulfide collector adsorption. The distribution and depth profile of copper and collector on these mineral surfaces were obtained by using SIMS in the imaging mode. The results of this study have provided a valuable insight to understanding pyrite and gangue flotation observed frequently in operating plants.

Jan 1, 1995

By Y. Tao

The features of the teeter bed separator and its application in the coarse slime separation of Chengjiao coal preparation plant were discussed. The relationship between the coarse slime separation efficiency by TBS and the particle size were studied, and the influence of using TBS on dense medium consumption and oil consumption were investigated, it increased the clean coal yield and the comprehensive recovery of the whole plant, and brought huge economic benefits to Chengjiao coal preparation plant.

Jan 1, 2011

By B. A. Filas

Stabilizing fine coal refuse ponds for reclamation at Monterey Coal Company's No. 1 Mine has been difficult. Entrained water in the stored refuse causes liquefaction as reclamation caps are placed, resulting in additional material requirements than originally projected to stabilize the pond surface. Laboratory results indicate that in-place refuse densities may be substantially improved at No. I Mine by converting from a single-point to a managed slurry distribution system. Increased densities result in improved storage efficiency, less entrained moisture and a more stable refuse mass, thereby providing an improved working surface for reclamation and improved post-closure cover stability.

Jan 1, 1993

By Ajay Mahajan, Manoj Mohanty, Vishal Gupta

Modern coal processing plants utilize multiple cleaning circuits to efficiently beneficiate different size coal fractions of run-of-mine coal. An older plant optimization approach is to maintain average product quality from individual cleaning circuits at the same level as the given product specifications for the overall plant. However, many past studies indicate that the equalization of product quality approach fails to produce the maximum plant-yield. A newer approach, known as equalization of incremental product quality, requires that the incremental product quality obtained from each circuit be maintained at the same level to satisfy the overall plant product quality. This approach ensures the maximization of plant yield while satisfying a single product quality constraint. However, while dealing with multiple product quality constraints, this approach by itself may not be sufficient to obtain the desired maximum yield. For the simple reason that the dirtiest particle (or group of particles) with respect to one quality constraint may not be the same particle (or group of particles) with respect to another quality constraint, the mass yield versus product quality relationship generated by equalizing different incremental product quality may not be exactly the same. Therefore, an additional search technique has to be utilized to determine the global-maximum value of plant yield. Thus, the main objective of this study was to utilize an emerging optimization technique, known as genetic algorithms (GA) to maximize plant yield while satisfying multiple product quality constraints. The maximum plant yield obtained from this approach was nearly same as the maximum yield obtained by the incremental product quality approach while satisfying one specific product quality constraint. The GA was applied on a coal preparation plant that utilizes four circuit operations - heavy medium bath, heavy medium cyclone, spiral and froth flotation. The results showed that using GA as an optimization process gives 2.56% higher yield that will result in additional revenue generation of $5,120,000 per annum than average product quality approach.

Jan 1, 2005

By E. Bakhtavar

In this paper, problem of short-term production planning for dimension stone quarries was mathematically modeled using a binary integer programming. The model includes an objective function, which was founded as the minimization of the costs due to the total cutting planes of the blocks. This objective may cause to maximization of the net present value (NPV) in dimension stone quarries. During the mathematical modeling the essential constraints are dimension stone quarry capacities and the market demand, block accessibility for the equipment and the reserve constraints. As a base, an optimal size and shape of extractable blocks should be first assigned according to the available extraction technique and the market demand, in order to create a geological block model. Then an economical block model is provided by assignment of a value of ?one? for ore blocks and ?zero? for waste. Maximum profitability and minimum amount of the ore wastage can be gained using this plan and modeling.

Jan 1, 2012

By E. Manev

Thin aqueous equilibrium film studies and surface tension measurements on a mixed surfactant system consisting of polyethylene oxide (a model frother) and potassium ethyl xanthate (a model collector) enable the interaction between the two surfactants at the air/solution interface to be elucidated. For the film containing the non-ionic frother, the interface was charged and addition of low concentrations of xanthate acted as a common electrolyte and reduced the thickness of the film inducing rupture. However, at high xanthate collector concentrations, the negative charge xanthate was found to interact with the non-ionic and caused a build-up of negative charge at the air/solution. Higher frother concentrations were necessary to produce non-rupturing thin films upon increasing the xanthate concentration.

Jan 1, 1992

By Douglas B. Silver

The key to unlocking value is to find opportunity where others have missed it. How does a company find value in a thoroughly explored asset? This article explores the approach taken by one company and the results it achieved from working this problem. The town of Shafter is located on a small bend in the road in west Texas' Big Bend Country. Its past emulates the glory days of so many other mining camps. A discovery was made, fortunes were built and World War II shut down the operation. The Shafter deposit continues to be one of the larg¬est undeveloped primary silver deposits in North America. Gold Fields Mining Co. recognized the area's potential in 1977 and embarked on studies to reopen and develop the district. Gold Fields spent $16 million on the Shafter project. It drilled more than 86,240 m (282,940 ft) in 475 holes, sunk two shafts and developed 1,550 m (5,100 ft) of underground workings. Today, the mothballed 447-kW (600-hp), single-drum Nordberg hoist and permanent production-type, single-compartment headframe continue to crown the shaft. Other buildings onsite house compressors, mine pumps, spare parts, drill core and other supplies. All these items look as though they arrived yesterday. By 1982, Gold Fields had completed an extensive feasibility study with ambitions to. construct a 1.36-kt/d (1,500-stpd) agitated cyanidation mill and base metal gravity circuit. Reserves at Shafter stand at 4.23 Mt (4.67 million st) grading 193.5 g/t (5.65 oz/st) silver. Gold Fields planned to produce 71.5 t/a (2.3 million oz/year) of silver at a head grade of 196.2 g/t (5.73 oz/st) silver with a 77% recovery rate. Cash costs were projected to be $5.54/oz with an anticipated initial and total capital cost of $46.2 million and $51.3 million (1984 dollars), respectively. The study assumed a silver price of $8.60/oz that has not been seen since the Hunt brothers quit buying silver. When silver prices declined, Gold Fields put the property up for sale.

Jan 1, 1999

By Greg T. Saretzky, Wilson G. Ward

A comprehensive hydrologic study was completed far the waste rock dump at Equity Silver Mine, BC. Characterization of the hydrologic system included geologic structure. topography, surface hydrology and groundwater systems. The results of the study conclude that the cover system is restricting net infiltration to approximately 5%. However, significant discharge continues to occur from the perimeter of the dump. A three dimensional seepage analysis was carried out to illustrate the influence of groundwater discharge associated with the regional topography and geologic structures. The results of the modelling program show that groundwater discharge occurs from the waste rock dumps when high recharge rates are specified for the surrounding topography- This groundwater discharge strongly influenced by the high hydraulic conductivity assumed far the fractured bedrock. The modelling results are considered preliminary and field drilling and piezometer installation is being conducted to determine the groundwater regime in the vicinity of the waste rock dump.

Jan 1, 2000

By A. E. Ketler

Optical smoke monitoring fills an important gap in ventilation and fire safety: namely monitoring of smoky, low temperature fires where little CO and heat are generated. Smoke monitoring also avoids the nuisance alarms due to diesel exhaust, battery chargers, blasting and welding. The smoke optical density (OD) fire alarm standard specified by MSHA presents an opportunity for improved safety. Experience of actual mine usage of the SmokeBoss*100 is reviewed, with particular regard to effectivity, maintenance and cost.

Jan 1, 1995