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By J. A. Botín

Investment decision for large mining projects imply an enormous financial risk and therefore, require a more complex risk evaluation methodology taking into account all sources of uncertainty from each process in the project value chain. Generally, the main sources of risk are those related to uncertainty on grade and other techical variables of the orebody. In this study, conditional simulation is applied to develop a risk management model to quantify and to manage financial risk associated to uncertainty on the grade of the orebody. The model was validated in case study on a real porphyry copper orebody in Chile.

Feb 23, 2014

By Henry R. Linden

The demand for natural gas continues to increase at higher than anticipated rates, partly because of its widening price advantage over most other fossil fuels when the cost of air pollution control is included. However, there are clear indications that natural gas supply from the contiguous 48 states and continental shelves will not indefinitely keep up with this rapid growth in demand. Projections are presented which define the extent of potential deficiencies from the 1970's to the year 2000. Among the sources of supplemental gas - imported pipeline natural gas from Canada and Mexico, tanker import of liquefied natural gas, and synthetic pipeline gas from coal and oil shale - by far the most abundant at potentially competitive costs is pipeline gas from coal. The state of development and relative economics of the various coal gasification processes are reviewed. It is shown that synthetic pipeline gas could become a very substantial market for bituminous coal and lignite at current minemouth prices - 60-70 million' tons of coal for each trillion cubic feet of synthetic pipeline gas produced. This corresponds to only slightly more than the current annual increase is gas demand.

Jan 1, 1969

By Hubert E. Risser

At the outset of a discussion on the adaptability of Illinois coals for use in iron and steel production, it is perhaps well to define terms. ?Adaptability? as used in this context, means that a coal can be, adapted to use within a given technological and economic framework. For a coal to be adaptable, to use in the manufacture of metallurgical coke within the present technological and economic framework, it must possess, among other things, at least the following characteristics: 1. The coal must be capable of producing, alone or in combination with other coals, a coke that can meet at least a minimum standard of required performance in the present-day blast furnace. The coke must have sufficient strength, stability, hardness, and freedom from impurities to make it suitable. 2. If the coal in its raw form does not meet these requirements, it must be amenable to beneficiation or upgrading so that the requirements can be met. 3. It must be available in uniform quality and in sufficient quantities to meet the need. 4. Use of the coal must be economically attractive. If its quality is equivalent; to that of the coals with which it must compete, it must be no more expensive than they. If It is better, a premium price may perhaps be demanded. If, in any respect, it is the least bit less suitable, the cost must be lower to offset its disadvantages.

Jan 1, 1961

By Gregory Rumbaugh, Christopher Mark

Recent pillar collapses have caused five large airblasts in underground U.S. limestone mines. One of these events injured three miners, but all of them put many other miners at risk. To better understand the hazards, Mine Safety and Health Administration (MSHA) conducted a comprehensive review of the international literature on airblasts. More than 40 airblast cases have been documented, in a wide variety of minerals. Experience shows that miners that are in the direct path of the air as it moves towards the mine exits are at the greatest risk. The paper describes a risk management methodology that can be used to evaluate the level of hazard throughout the mine and aid in the selection of controls to reduce the risk. The paper concludes with a detailed case history of an actual pillar collapse and airblast.

By R. E. Hamilton

Automation is a word whose meaning has been broadened by popular usage to include any labor saving device. We with restrict our usage to the replacement of human judgement by instrumental measurement and mathematical analysis in the control of industrial processes. Mineral concentration is an area which has resisted automation because of the great difficulty in developing measuring instruments which can exist in the rugged environment and can measure useful properties with acceptable accuracy. This is not the only factor limiting progress, but until recently it has been of over-whelming importance. The development of on-stream X-ray analysers, magnetic flowmeters and nuclear density meters for mineral slurries has eliminated this obvious barrier and is enabling us to locate and attack the less obvious problems which still limit our ability to automate concentrators. If we examine the history of automation in industries which are highly automated we find that it has usually gone through three distinct phases. The first phase has been regulation. This is the simplest form of control and involves manipulating some variable whose value is of no importance in order to maintain the value of some other variable which is important at a constant specified value in spite of disturbances which may occur in other variables which affect it. A simple example is the use of a control valve to maintain a constant flow of fluid in a line in spite of changes in pressure in the vessels at the ends of the line. The position of the valve stem is of no consequence, as long as it is within its operating range. Unfortunately we soon run out of variables which can be

Jan 1, 1971

By C. L. McKenzie

American Girl Mine is located in the Cargo Muchacho Mountains in the southeastern Imperial Valley of Southern California. Production from the current open pit mine and heap leach recovery system began in early 1989. Previous mining and gold recovery took place commencing in 1987 at the Padre Madre site, situated adjacent to the American Girl site to the southwest. In mid-1990, a 790-tonne-per-day underground gold mine and mill went into production. Approximately 6,500 troy ounces of gold per month are recovered from the combined open pit underground mine operation. Copper in the form of Azurite [Cu3(CO3)2(OH)2] and Malachite [Cu2CO3(OH)2] are abundant in the mined ores (Henshaw, 1942). The high solubility of these minerals in caustic cyanide solutions has a negative impact on carbon adsorption and electrowin processes. This paper presents the results of monitoring programs, process chemistry, and control changes introduced at American Girl Mine to abate production complications in the refinery and measures taken to minimize solution gold losses in the adsorption circuit(s).

Jan 1, 1993

The market for titanium feedstocks (ilmenite, rutile,synthetic rutile and slag) is driven primarily by offtake from the titanium dioxide (TiO2) pigment industry. The pigment sector depends on the performance of the global economy. Titanium sponge is the first stage of titanium metal manufacture. It constitutes a minor component (3 percent) of overall demand for titanium feed-stocks. Production and consumption TiO2 pigment consumption in 2004 was estimated to be 4.63 Mt (5.1 million st), up 7.6 percent from 2003. It was driven by strong demand in most regions. In the United States, apparent TiO2 pigment consumption rebounded by 5.4 percent (highest growth rate since 1997) to an estimated 1.12 Mt (1.23 million st), following the decrease in demand during 2003. Chinese TiO2 pigment consumption continued its strong upward trend, increasing by 10 percent to 598 kt (659,000 st) in 2004.

Jan 1, 2005

By D. M. S. Bhatia

Five sulfide minerals from the Magiwnt mine, southeast Missouri were analyzed for 31 trace elements in over 300 samples by laser microprobe spectrographic analysis of polished sections. The concentration of several trace elements shows a pattern of progressive variation with depth (space) and variation with different paragenetic stages (time) of each mineral. Factor analysis of the geochemical data shows sympathetic correlation both in space and in time of Bi, Cd, Ge, and Sn in galena and sphalerite, and Ni and Co in sphalerite and marcasite.

Jan 1, 1979

By R. S. Ondrey, R. A. Haney, T Tomb, R. T. Stoltz, Novakowski D. L. Chiz, E. J. Gerbec, D. J. Atchinson

Although the number of operating longwalls in the United States (approximately 100) has remained relatively constant over the last five years, longwall production levels have significantly increased and in some cases more than doubled. As a result of this production increase, control of respirable dust continues to be a problem. Therefore, the Mine Safety and Health Administration (MSHA), Pittsburgh Health Technology Center, Dust Division, initiated a study to investigate the availability and adequacy of technology for controlling dust on longwall mining operations. The study involved 23 longwall mining operations in three different Coal Mine Safety and Health Districts. Each operation was visited for a full shift. Respirable dust samples were collected on face personnel and at fixed locations along the face. Methods being used to control dust were noted, with special emphasis placed on obtaining quantitative data relative to ventilation, headgate dust controls, cutting drum sprays, external machine sprays and cutting sequence. Attempts were made to correlate dust control practices in place at the time of the visit to dust concentrations measured at the tail and on the tail shearer operator and to the average of all the dust concentration measurements from the occupations sampled. The methods used to control dust were also compared to the gamut of methods known to be available. This paper presents a discussion on the effectiveness of the methods being used to control dust and on the availability of technology for the control of dust on longwall mining operations.

Jan 1, 1991

By Manuel Gomez

This report presents prediction equations for eleven factors indicative of metallurgical coal quality which have been developed from data obtainable during exploration. Five coke strength parameters and six carbonization product yields have been predicted for coking coals having volatile matter contents in the range 16.3 to 42.1 percent, dry basis. The prediction models developed contain information from the proximate and ultimate analyses, the size consist, and the petrographic composition of coking coals carbonized in BM-AGA retorts at 800°, 900°, and 1,000°C. The equations reported have been evaluated with independent data derived from the 900°C carbonization of 33 binary blends. Present results show that metallurgical coal quality can be predicted ahead of mining. Capability to forecast coal quality is useful in mine planning and should provide basic information for optimization of blending and crushing techniques, leading to the production of uniform coke.

Jan 1, 1968

By J. E. Urosek

In October, 1990, a fire started in a large underground coal mine in Western Pennsylvania. During fire-fighting activities, an explosion occurred and all personnel were evacuated. Safe re-entry into the mine was not possible and the mine was sealed. Recovery efforts began in January, 1991 and continued until March, 1991, when permanent underground seals were installed between the fire area and the mine openings. This paper describes an extensive atmospheric monitoring program conducted by the Mine Safety and Health Administration (MSHA), Pittsburgh Safety and Health Technology Center (PS&HTC) including the analysis of mine fire gases, natural ventilation, fan pressure and air quantity distribution.

Jan 1, 1993

By Connor Langford, Murray Gant, Ken Massé

For public organizations, preparing accurate project cost estimates is a critical component in capital project planning. Project delivery methods provide a structured approach to moving projects through the design and construction lifecycle, and typically use cost estimates as key inputs at each stage to determine if the project will advance. As design stages can occur years or even decades before construction contracts are awarded, estimates need to make reasonable assumptions about how the work may be executed (means and methods) as well as potential future market trends so that appropriate values for material pricing, labour costs, escalation, and owner’s costs can be included. This process is challenging enough during stable markets, as historic trends can often be misleading and require a suitable understanding of economic factors to use appropriately. When you mix in the market volatility that has been observed since 2020, developing accurate project cost estimates becomes even more challenging. In cases such as this, having a structured approach to cost estimating that includes an adequate risk-based reserves cannot be overstated as it provides the basis for ongoing project decisions. This paper explores some of the historic and more recent market trends that have impacted key aspects of project cost estimates for capital project planning. It also provides recommendations on how to develop cost estimates for infrastructure projects, with examples from Metro Vancouver, which plans for and delivers regional-scale services to 2.6 million residents. A brief commentary on the use of escalation clauses in contracts is also presented.

Jun 13, 2023

By Richard Snyder

Secretariat of the Coal Mining and Mining Executive Committees' of the National Safety Council (NSC) and Manager of the memberships to both Mining Sections; Senior Consulting Safety Engineer, NSC; member of several committees for consensus Standards of the American National Standards Institute (ANSI); a Certified Safety Professional (CSP) of the Board of Certified Safety Professionals of the Americas, Inc. and a chief proctor for CSP testing and certification procedures, et al. It appears that the tunneling trade is merging into its own renaissance for the decade of the 1970s', and most likely on past the year 2001. Federal interest in underground excavation, and more specifically, rapid excavation expertise has been on the upswing since the latter part of the 1960's, mainly due to the pressing national needs for more raw materials based on the rise for material goods and the projective gloom of possible power shortages. On the pure tunneling side the national needs encompass, in the mainstream of priorities, rapid transportation and water supply excavation as the two top contenders. For instance, the estimates for tunnel mileage for the period 1968-1975 are:(1) Subways---85 miles Urban Highways--- 123 miles Intercity Highways---210 miles Water Supply Routes---528 miles at a total of 946 miles of tunnels. The estimated cumulative underground excavation demand in dollar amounts for the period 1970-1989 are:(1) Construction Oriented Demand--- $35 billions Mining Oriented Demand---$34 billions (which includes the coal-oriented demand on the order of 26 billions.

Jan 1, 1997

By Steven W. Hunt, Isabelle Lamb, Steven B. Fradkin

Groundwater control is generally an important consideration and significant source of risk during most tunneling projects. Proper baselining of groundwater conditions requires: 1) a thorough understanding of the geological environment; 2) a focused site investigation; 3) identification of construction and adjacent property damage risks associated with inflows and short and long term piezometric level changes; and 4) consideration of contractual issues including restrictions on means and methods and pay items for associated work. This paper provides an overview of groundwater baselining issues and risks based on selected design studies and construction case histories.

Jan 1, 2005

By E. Watkins, V. Gangrade

Large-opening stone mines often rely on natural ventilation and a network of auxiliary fans to produce adequate ventilation conditions in the mine instead of main mine fans, which are commonly utilized in coal mines. Large air volumes in underground stone mines, poor ventilation practices, and low operating budgets for mine ventilation potentially increase mine workers’ risk for dust, silica, and diesel particulate matter (DPM) emissions exposure. To help improve mine ventilation practices, the optimal auxiliary fan location for maximum airflow production from a ventilated intersection was determined using a combination of field measurements and computational fluid dynamics (CFD) modeling. In this study, conducted by researchers at the National Institute for Occupational Safety and Health (NIOSH), airflow quantity and fan data were collected at a partner mine to be applied as CFD model input parameters and comparison data for model validation. A six-foot diameter auxiliary propeller fan was introduced into the validated CFD model at three locations at a mine entry intersection with established ventilation flow perpendicular to the fan direction. Placing the fan on the opposite side of the intersection from the target active face area produced the highest ventilation flow rates at the downstream locations tested and produced the lowest amount of air re-circulation. The findings show that optimizing the placement of an auxiliary fan may increase the net effective ventilation flow rate by 70,000 cfm and reduce recirculation by 26%, which maximizes the potential effectiveness of large-opening stone mine ventilation systems and decreases mine worker exposures to airborne contaminants.

Mar 2, 2022

By M. S. Fraley

As we compete for close margins in wholesale sales, the effects of both quality and price have a major impact on the cost of producing electricity.SO2 emission allowances have traded as low as$60/ton to as high as $215/ton over the last three years. This price spread in emission allowances clearly demonstrates the correlation between the quality of fuels versus the price utilities will be willing to pay for them. This paper provides an overview of the effects of the qualities of fuel, coupled with transportation as well as environmental concerns on the price of fuel and the ability to compete in a deregulated electric market.

Jan 1, 2000

By Erik Westman, Brandon Stables, Benjamin Mirabile

"Standing support is often used in conjunction with underground retreat mining. Knowledge of the load-displacement behavior of standing support and loading induced by the mine opening is critical to proper support selection. The NIOSH STOP database contains load-displacement laboratory test data for most commonly used standing supports. Hydraulic load cells currently used to measure in-situ loading of standing supports have exhibited leakage under load, producing irregularities within the dataset. An improved hydraulic load cell eliminates leakage and produces more consistent data.INTRODUCTIONA hydraulic load cell, more commonly known as a flat jack or JackPack, is a device installed to determine the loading characteristics of the roof-to-floor supports. These standing or roof-to-floor supports include, but are not limited to pumpable cribs, cans, wooden cribs (4-point, 9-point, etc.), metal props, wood timbers, concrete donut cribs, and other variations of these standing supports.Flat jack devices have been used previously to determine the loading of such roof to floor supports. The most commonly used load cell for standing supports is based on a design intended for pre-stressing standing supports, not load measurement. Preloading helps to keep the supports, such as timbers props and cribs, in place during the dynamic loading associated with blasting (Barczak and Tadolini, 2004).Flat Jacks are manufactured in various shapes and sizes depending on the application; common shapes are square and round that are 25.4 mm (1.0 inch) thick when collapsed, as shown in Figure 1. These load cells are produced in South Africa and can be formed into several different shapes depending on the application (Barczak, 2003). The sheet metal that makes up the bladder is comprised of 19-gauge or 1.11 mm (0.04 inch) thickness; the top and bottom pieces of sheet metal are resistance-seam welded around the perimeter. There are two different ports installed on one of the bladder skin corners of the flat jacks; these ports allow fluid to fill the unit, and the other port has a relief valve. The fill port is comprised of a check valve. The pressure relief valve is located in the second port; preset to 1,724 kPa (250 psi), the pressure relief valve keeps the load cell from bursting. Bursting of these load cells typically causes a small tear in the metal skin allowing the fluid to leak out without a large catastrophic failure.The effective inflation range of these load cells is between 25.4 mm (1.0 inch) to 254.0 mm (10.0 inches) thick. Different types of fluids can inflate these load cells but the most common and easily accessible fluid for testing applications is water. Water pressure from the mine supply line can inflate these load cells to the desired load. Depending on the pre-stressing requirements, a pneumatic powered pump, hydraulic pump, or hand pump may be required to inflate the load cells."

Jan 1, 2019

By P. K. Kankar, Manoj Khandelwal, Ramesht Shukla

One of the utmost severe mining catastrophes in underground hard rock mines is rock burst phenomena. It can lead to damage to mine openings and equipment as well as trigger accidents or even threat to life as well. Due to this, a number of researchers are forced to study some easy-to-use alternative methods to predict the rock burst occurrence. Nevertheless, due to the extremely multifaceted relation between mechanical, geological and geometric factors of the mines, the conventional prediction methods are not able to produce accurate results. With the expansion of machine learning methods, a revolution in the rock burst occurrence has become imaginable. In present study, three machine learning methods, namely XGBoost, decision tree and support vector machine, are utilized to predict the occurrence of rock burst in various underground projects. A total of 134 rock burst events were gathered together from various published literatures comprising maximum tangential stress (MTS), elastic energy index (EEI), uniaxial compressive strength and uniaxial tensile stress (UTS) that have been used to develop various machine learning models. The performance of machine learning methods is evaluated based on the accuracy, sensitivity and specificity of the rock burst prediction.

Mar 17, 2021

By Douglas G. Fox

Outputs from industrial activities planned in the Riley Ridge natural gas project are modeled to determine the potential locations of air pollution impacts on the Bridger and Fitzpatrick Wildernesses in Wyoming. The nature of modeling, especially with regard to its realism, is discussed. Alpine lakes which, along with their watersheds, have minimal buffering capacity are being studied because of their sensitivity to acidic deposition from proposed new air pollution sources. A hypothesis which relates a source's emissions to deposition and lake chemistry in a worst-case sense is presented. Research designed to test the hypothesis and reduce uncertainties is outlined and progress reviewed. Focus is placed on the meteorological transport and atmospheric deposition parameterization contained in the hypothesis.

Jan 1, 1984

By J. J. Gusek

Several final pits in the Seneca No. 1 Surface Coal Mine were abandoned in the 1960's without being reclaimed. In addition, a progressive landslide aggravated by the abandoned mine land conditions was threatening a county road and private property. An AML-funded project to stabilize the landslide and reclaim the final pits was completed in 1986 for the Colorado Division of Mines and Geology (formerly Colorado Mine Land Reclamation Division). The site was visited after ten growing seasons. The land is stable and the vegetation re-establishment is strong. Volunteer native plant species are now invading the reclaimed sites.

Jan 1, 1997