Search Documents

By C. W. Newcom

The mining industry continues to be under expanded scrutiny in the health and safety arena, both from federal regulators and the media. While this paper will briefly discuss how enforcement activity, both with citations issued and the size of penalties proposed, the primary focus will be practical suggestions to deal with some key, high-risk areas for a mine operator which could have substantial impact, both in terms of liability and mine operations. It goes without saying that all mine operators need to continue compliance programs they have in place with careful ongoing evaluation of those plans for areas of improvement. The focus here will not be compliance as such, but rather steps to take and procedures to have in place to try to minimize risks in the face of the potential for more significant liability. Thus, our focus will be procedures to respond to unwarrantable failure citations, immediately reportable accidents, and to deal with potential pattern of violation issues.1

Jan 1, 2011

By T. Wang

A new generated NaNO3 ? NaNO2 ? KNO3 ternary thermal energy storage system which has low melting point as 124°C and high specific heat capacity was studied for the short and long?term thermal stability by using the Thermogravimetric Analyzer (TGA). Based on the actual working condition of molten salt in solar two, the simulated cyclic thermal stability measurement was also conducted. The ternary system demonstrates excellent short ? term thermal stability and thermal reliability after cyclic heating and cooling processes. However, in the long ? term as well as the simulated cyclic stability measurement, large amount of weight loss was observed. Moreover, the stepwise long ? term isothermal study reveals that below 440°C the weight change is minimal and this temperature is viewed as the upper limit temperature of thermal stability for this ternary system. To determine the lost phases at high temperature above the upper thermal stability limit, techniques such as XRD and SEM are used to compare the condition of the salt mixture before and after the long ? term thermal stability study. On the basis of the comparison, it can be concluded that the major weight loss was due to the decomposition of sodium nitrite.

Jan 1, 2012

By Carlos Tarazaga

Progressive Design-Build (PDB) is an emerging variation of alternative delivery programs in the underground construction industry. PDB refers to the way a construction project design is developed by the Owner and the Design-Builder in a step-by-step process. According to the Design-Build Institute of America (DBIA), Progressive Design-Build allows the design and construction team to collaborate during the earliest stages of project development. This enables engagement between the three key players in a construction contract: the owner, the designer, and the contractor. Is the PDB the best alternative program delivery for large contracts? What is the perspective of the private sector? This paper will provide an overview of the different alternative delivery programs used in the underground industry, pros and cons of each of programs, and the perspective of the designers and contractors. The paper will focus on how the PDB works, reasons why owners should consider PDB for their projects, best collaboration strategies among owners, designers, and contractors to deliver a successful project, and how to manage the project risks using a PDB method.

Jun 13, 2023

By Marcus Digre

The autogenous grinding method has been progressively employed in mineral dressing plants during the last 15 years. The term has been used with somewhat different meanings (1), (2), (3). In this paper the author will use it in the most restricted way, for processes where run-of-mine ore (rock) in one step is reduced to a grind product by the action of the ore itself without any other grinding media present. The pebble grinding process where the major part of the ore enters the mill as finely crushed product which is ground further with selected coarse ore pieces acting as grinding media, is not considered autogenous grinding. Processes where a minor amount extraneous media as steel-balls is added to supplement an autogenous mill charge will be called semiautogenous. Other terms need also to be defined. "Mill charge" will be used about the active part of the mill content which performs the grinding, that is the steel balls in ball grinding and the coarse ore pieces in pebble and autogenous grinding. The interstitial nearly finished material is not included in the term "mill charge", and for the wet grinding operations is called the "mill pulp' The term "pebble" will be used for any rounded ore or rock piece in the mill charge whether it is an autogenous or a pebble grinding operation.

Jan 1, 1970

Gaby Copper Mining?s Gabriela Mistral property is located in the Antofagasta region of northern Chile, at an altitude of 2,660 m (8,727 ft) above sea level. The reserve contains an estimated 562 Mt (620 million st) of oxide ore with an average grade of 0.41 percent total copper. The mine went into production in 2008. Gaby Copper faced the problem of having no reliable way to measure the solids level. This is a challenge that exists throughout the mining industry, where dust in the air and accumulation of solids on a sensor make accurate measurements difficult in areas such as transfer chutes, the rock box underneath crushers, silos and anywhere else that information is needed on the level of solids. The next-generation technology in the Sitrans LR560 radar from Siemens addresses this challenge. With a frequency of 78 GHz ? higher than previous generations of radar ? it provides a more robust signal for measuring in areas where there are high levels of dust accumulation. The Sitrans LR560 provides a signal beam angle of four degrees, significantly narrower than any other product on the market can offer.

Jan 1, 2014

By O. H. Rostad

The importance of geology in ore reserve estimation has been stated by several authors. King et, a1 (1982) reported that the geological factor was the key deficiency where serious weaknesses in ore reserve estimation appeared, especially in grade. The foundation for a successful mining operation is an ore reserve estimate that neither overstates nor understates the true situation as to tonnage and grade. Overestimation of reserves can have devastating economic results. Overestimation of tonnage may lead to wasting money on an overbuilt plant or worse yet, if grade is seriously overestimated also, to undertaking an operation that is doomed to economic failure from the outset. Understated ore reserves can result in building a plant that is smaller than optimum which may result in higher unit costs. At worst, understated tonnage of ore reserves can result in a missed opportunity for a profitable operation. Failure of the ore reserve estimator to properly take into account all geologic and allied factors pertaining to the deposit can result in an ore reserve estimate that is overstated either as to tonnage or grade or both. This paper will focus on these factors and will not discuss rules about distances above or below a drift that should be given a classification of proven or probable, etc. Each deposit has its own particular characteristics which often require modification of general rules for defining limits of proven and probable ore blocks that work satisfactorily in another deposit. A number of references are included which discuss some of these problems. Definitions of ore reserve classifications and an illustration are given in the Appendix.

Jan 1, 1985

By K. Komnitsas

This paper presents the main environmental assessment techniques and indicators that can be used a) for the establishment of a sustainable development framework and b) for the evaluation of the environmental performance within the mining sector. Reference is made to techniques as environmental risk and impact assessment, life cycle assessment, cost benefit analysis and best practical environmental option assessment that can be used as tools to assess environmental impacts of processes, activities and products in the mining sector. In addition, the issue of environmental indicators, covering operational, management and environmental areas, that provide valuable information regarding both the environmental performance of a mining company and its efforts to influence this performance towards sustainability is discussed.

Jan 1, 2003

By J. O. Marsden, M. M. Botz

"Heap leaching is responsible for approximately 21 percent — 3.9 million metric tonnes — of copper production and 9 percent — 270 metric tonnes or 8.7 million ounces — of gold production worldwide. Given metal price assumptions of $2.25/lb for copper and $1,250/oz for gold, these portions of global production generate revenues of $19 billion and $11 billion, respectively. For heap leaching operations, small changes in metal extraction efficiency drive substantial changes in operating cash flow margins and affect project viability. Variances in actual metal production from budgetary forecast estimates can mean the difference between success (value creation) and failure (value destruction) for a heap leach project. Despite the importance of heap leaching for copper, gold and silver production worldwide, there are no clear standards or guidelines for developing heap leach metal production forecasts. There is considerable variation among copper and gold producers that apply heap leaching technology as to how such modeling and forecasting is applied at the operational level. There are a variety of different modeling approaches that can be utilized for this purpose. However, these vary in cost, complexity, time to implement, accuracy and credibility. This paper explores the options available for heap leach modeling, discusses the advantages and disadvantages of each approach, and provides guidelines/recommendations for an effective approach to modeling metal production at existing or planned heap leach operations. The paper also provides expected ranges of variation between actual and modeled production.Introduction and backgroundHeap leaching is fundamentally different from other methods used in the processing and extraction of gold, silver, and copper and other base metals. Considered globally, the technique represents a relatively modest portion of production compared with the primary technologies applied for copper and gold recovery. Approximately 21 percent of copper production is attributable to heap leaching techniques, as opposed to 79 percent by conventional crushing, milling, flotation, smelting and refining. For gold, about 9 percent of global production is obtained from heap leaching, compared with over 90 percent by various combinations of crushing, milling, gravity concentration, flotation and/or agitated cyanide leaching processes or, in the case of placer deposits, by direct gravity concentration and/or amalgamation. In cases where heap leaching is the primary source of metal production, the ability to accurately forecast metal production may be the difference between commercial success and failure for a project or operation. Heap leaching — of crushed or run-of-mine ore — is also commonly applied as a secondary process to treat lower-grade ores from a given deposit, such as at Chuquicamata in Chile, Cerro Verde in Peru and Bagdad in Arizona for copper extraction and at Twin Creeks and Carlin, both in Nevada, for gold. In such cases, heap leaching provides incremental revenue to supplement the primary process. Variances between actual and forecast metal production from heap leaching as a secondary process are typically tolerated and absorbed within the overall site metallurgical balance. In either case, accurate production modeling and forecasting creates significant value for heap leaching projects, is essential for managing production expectations — timing and volumes — and is likely to be a critical success factor for most heap leach projects."

Jan 1, 2017

By C. R. Tinsley

Valuations can be molded, twisted and misinterpreted. Cases of spurious scope setting; limits to the information or access by the valuer; difficulties with the lack of comparative valuations; inappropriate valuation methods and outright speculations are described. None should be accepted by an experienced, independent minerals valuer. The Australasian Institute of Mining and Metallurgy (TheAusIMM) is working on a Valmin Code for which a Manual of Best Practice and Valuation Guidelines may be developed.

Jan 1, 1995

By Len Harris

Webster?s Dictionary describes culture as: ? The totality of socially transmitted behavior patterns, arts, beliefs, institutions and all other products of human work and thought typical of a population or community at a given time. ? A style of social and artistic expression peculiar to a class or society. ? Intellectual and artistic activity. ? The art of developing the social, moral and intellectual facilities through education. The authors have nearly 100 years of combined experience in the mining industry working with and consulting to mining companies and companies engaged in the supply of goods and services to the mining industry worldwide. In this report, they present their experiences and ideas on the importance of cultural aspects in the successful development and implementation of mining ventures. Their suggestions on how to handle culture shock will be of interest to expatriate managers, operators, social workers, and engineering and construction personnel posted to overseas operations, as well as to nationals posted to other parts of their own country.

Jan 1, 2008

By Friedrich Steinhäusler

RADON SOURCES AND CONTROL MEASURES IN THE MINING ENVIRONMENT Most of the contamination of the mine atmosphere by radon 222 is due to radon emanating from solid or fractured ore surfaces of walls, roof and floor. Also radon gas emanates from broken ore either from storage in backfilled mined-out areas as applied in e.g. shrinkage stopping methods or from ore spillage along intake airways mainly due to the use of trackless haulage. To a lesser extent water itself can represent an additional source of radon, which emanates into air from open drainage ditches or seepages along intake airways. The contribution from water can be controlled effectively by isolating the water from the primary intake air system, e.g. by diverting the water through pipes and/or sealing of seepages by grouting. However, control of radon emanating from rock surfaces creates a major technical problem with significant impact on the economic aspects of mining operations, if adequate radiological conditions must be maintained. Basically this can be achieved by suppressing the emanation process itself, confining already emanated radon or by removal of radon from the mine atmosphere. Extensive research has been carried out on the rate of radon emanation as a function of barometric pressure changes (Pohl-Rüling and Pohl, 1969). It could be shown that the radon supply consists of a permanent and variable component. The former results from the surface of the rock and depends mainly on the emanating fraction of its radium 226 content; the latter originates from within the rocks and is a function of the suction effect of decreasing barometric pressure, rock porosity and fissures. The practical application of this barometric pump effect for depressing the rate of radon emanation, e.g. by pressurizing the mine atmosphere, is limited due to high costs for providing a sink for absorption of radon and air as well as lack of permeability in most uranium ore bodies (Schroeder et al., 1966). Mine air cleaning by removal of radon can be achieved with the use of cryogenic methods, chemical removal, adsorption into charcoal beds, use of a gas centrifuge or general ventilation techniques. Technical problems have so far prevented the application of any of these methods other than ventilation. It is common practice to use the age-of-air concept, i.e. fresh air is delivered to the worker as directly as possible and removed quickly afterwards thereby maintaining the air "young". Engineering principles for quantity distribution of air through underground working areas are straightforward for general mining situations where radon constitutes an environmental contamination problem. However, in cases of high uranium ore content this concept may result in high costs with regard to installation and energy requirements for effecting both frequent air changes as well as sufficient heating of the air in cold seasons. Taking into account that the investment in ventilation systems is a major cofactor for the overall ore production costs this can be a limiting and decisive component in the assessment of the economic feasibility of specific mining operations and mineral reserves in general. Effective control of the radon flux from the rock surface prevents the initial contamination of the mine air with radon directly at the source. A radon diffusion barrier for practical application in mining requirements should fulfill the following requirements: - reduction of radon emanation rate by at least an order of magnitude - high mechanical strength - ease of sealant application onto surface to be coated - water resistant - low fire hazard - resistant to temperature changes encountered in mines - high cost efficiency in relation to exposure reduction achieved (direct and indirect costs) - low degree of maintenance. In the past several materials have been tested as sealants for controlling the emanation of radon from surfaces of rock and building materials. Epoxy paints reduce radon emanation rate only by a factor of 2 to 6 (Auxier et al., 1974; Eichholz et al., 1980; Keith Consulting Engineers, 1980). Although it is possible to prevent the escape of more than 99 % of the radon to the environment with gel seals over 80 mm thick (Bedrosian et al., 1974), practical applicability is very limited. Multilayer coatings of epoxy resins with various additives require meticulous preparation and flawless application of seamless four-layer coatings in four days to impede radon diffusion (Culot et al., 1976), otherwise results from this method have not been totally satisfactory (Leung, 1978). Aluminium foil laminated with polyethylene and paper on each side is under test as radon barrier but results are not available yet (Ericson, 1980). However, this method has the inherent disadvantage that possible malfunctioning electrical installations can cause fire or electrical shock through the sealant. Polyurethane foam coatings have been used on stoppings as very effective sealants. It does, however, represent a potential danger of spontaneous ignition and it is expensive (Rock, 1975). Thus, there is still need for a material which has similar properties as outlined above. In the following results are reported from investigations on the suitability of various materials as radon diffusion barriers.

Jan 1, 1981

By Richard W. Brummett

Problems in new strip mine development is a subject that could require several days to cover adequately. Coupled with the fertile imagination of television writers, we could probably expand it into a series rivaling Gunsmoke in longevity with just as many shootouts at sundown. It would-of course-be subject to a high Neilson Rating. To bring the subject into perspective, we will limit the comments to a general discussion covering western strip coal developments. Stimulated by increased demand for low sulfur coal, surface mineable western coal operations began a shift into high gear approximately four years ago. Then came last year's "energy crisis" that increased the pressure on coal development not only in the west, but nationwide. Several eastern power plants having dual oil and coal burning facilities were directed to discontinue using oil. Also, a number of new south and southwestern power plants scheduled to burn natural gas or of I commenced an ordered conversion to other fuels, namely, coal. The involved utilities with reserve positions accelerated their planning while others began the search for long-term commitments from coal producing companies. In addition, announcements were made for proposed mine mouth coal gasification projects in New Mexico, Wyoming, and North Dakota.

Jan 1, 1974

By Northcutt Ely

My topic today is our Nation's interest in the minerals beneath the oceans. I will state what I think should be our objectives, the means available to attain these objectives, and the obstacles to their accomplishment. It is possible that as early as this year of 1969 our country must make policy decisions on this subject, and that these, once made, will be almost irreversible. Two factors are hastening an. early decision. First, the 1958 Convention on the Continental Shelf becomes eligible for amendment after June 10, 1969, if the Assembly of the United Nations so decides. Second, the United Nations has created a permanent committee of 42 nations, which was preceded by an ad hoc committee of 35 nations, to study the question of the peaceful uses of the seabed "beyond the limits of national jurisdiction. While these measures purport to deal with the creation of a regime to govern mineral development on the deep sea floor beyond the limits of the jurisdiction of the coastal nations, it has become clear that the urgent issue is the extent to which this future regime shall acquire jurisdiction over the mineral resources of the continental margin, and receive royalties therefrom. This brings the proposal into potential collision with the interests of the coastal nations under the 1958 Convention on the Continental Shelf, including, of course, the United States.

Jan 1, 1969

By H. Haselhuhn

Filtration of hematite ore slurries can be a bottleneck in some hematite processing plants due to inadequate filtration rates caused by the dispersion of fine particles. Flocculation of fine particles in the slurry decreases the specific cake resistance of the filter cake allowing for increased filtration rates. CO2 sparging of hematite slurry was shown to increase the filtration rate by altering the pH and the surface chemistry of the particles. It was shown that an increase in filtration rate of 278% can be accomplished by lowering the pH from 11 to 6.5 using CO2. This was attributed to increased flocculation of hematite and silica particles in the ore.

Jan 1, 2012

By E. M. R. Santos

Acid mine drainage (AMD) is a serious environmental problem in mining activities. Prediction is the first step for evaluate the potential of acid generation and there are some possible methods to estimate it. They are described as static tests, which examine the balance between acid producing and acid consuming materials, and kinetic tests, which attempt to predict drainage quality over time. Static methods are very simple and give a qualitative classification of the ores based on their potential to generate acid drainage. The characterization of ores to determine their acid producing potential is vital for the prevention of long term environmental liabilities. Laboratory tests were conducted under different methodologies to predict the acid producing potential of sulphide overburden, ore materials and tailings from a deposit of copper ore.

Jan 1, 1999

By David R. Maneval

In 1956 the Legislature of the Commonwealth of Pennsylvania created a "Coal Research Board" in the Department of Mines and Mineral Industries. Over the years through amendments to the original legislation, the scope of authority for research has been expanded from the narrow area of improving and increasing the utilization of coal to covering all aspects of coal technology and any other area of interest which would be of value to the coal industry. In January of 1964, the Board commenced a vigorous program using appropriated funds and funds donated by the coal industry to finance a research program devoted to seeking solutions to the mine drainage problem. A review of published literature on the treatment of mine drainage indicated that much work done up to that point in time concerned only the mechanism of mine drainage formation and theoretical chemistry. Very few applied, developmental, or engineering studies had been devoted to finding practical solutions to the problem of polluted waters being discharged from active or abandoned mines. Projects were therefore undertaken on a wide variety of more utilitarian approaches. This paper will discuss briefly some of the pollution abatement approaches which have been funded by the Coal Research Board of this State, and will describe in some detail a multistage flash evaporator treatment plant now under construction.

Jan 1, 1970

By Firat Atalay

Estimating the spatial distribution of ore grade is one of the most critical steps to proceed with an investment decision on a deposit. Kriging is the most widely used method to estimate the ore grade, but alternative techniques are being developed. Machine learning algorithms can be used as alternative methods to classical kriging. In this paper, the iron (Fe) grade of a deposit is estimated with the XGBoost algorithm, and the results are compared with kriging estimation results. For the estimations, samples collected from drillholes were used. Due to the different natures of the estimation methods, different steps were taken to perform the estimations. The results show that XGBoost produced higher-range estimates, which is a desired result in ore grade estimation, and the minimum and maximum of the estimates were lower and higher than the kriging estimates, respectively. However, like kriging, the estimation results were smoother than composites, and the variance of the XGBoost estimates was lower than the variance of composites. This means that even though estimation with XGBoost mitigates the smoothing effect, the estimation results suffer from smoothing like kriging.

Dec 1, 2024

By S. Pastor, S. Hahn

"As the concept of autonomous haulage systems (AHS) moves from proto-types to production-ready applications, the operating performance of the haul road will become ‘mission critical’ to the overall success of autonomy in mining. Deterioration in road performance will require remediation, human intervention and significant, albeit temporary, changes to operating procedures, to accommodate road maintenance. With autonomous trucks comes the opportunity to reduce road formation and operating width, and therefore generating potentially significantly reductions in stripping ratios and improvements to mine economics, but only if the design of the road, and it’s associated deterioration rate, is predictable and manageable, based both on the materials used to construct the road and the maintenance interventions to be carried out on the road. This paper presents the assessment of a digital photogrammetric approach to the characterization of a mine haul road surfacing, or wearing course material. Design and maintenance parameters for these roads are currently determined from physical particle size distribution (PSD) assessments of ‘in-road’ material. However, this approach does not accommodate the need, nor leverage the benefits from, AHS. The digital imaging approach is assessed in this paper, using two standard digital analysis software tools, together with in-service mine haul road wearing course samples and images which are assessed to determine the applicability and reliability of the approach to deliver a real-time assessment of haul road surfacing conditions and thus to identify the road maintenance interventions required to address deterioration. INTRODUCTION Enhancements in mine road design, construction and management for the past 20 or more years has largely been focused on short-term tactical needs. These improvements have not been matched by advances in the fundamental technologies that underpin mine road design and management, and although the quality of mine roads have probably increased, many of fundamental and longer-term issues have yet to be addressed. With AHS’s evolving from prototype to production applications, any decision to implement these systems in a mine requires a thorough evaluation of impacts, not only operational improvements, but the inter-connectivity of this autonomy technology to other organizational processes. In developing an understanding, the full interactions that may affect autonomous truck behaviour due to changes in various sub-systems or external environments, haul road conditions and operating performance is a key consideration. This is as true in autonomous as well as in conventional mine truck-based hauling systems where the mine haul road network is a critical and vital component of the production process."

Jan 1, 2015

By T. A. Laser

"INTRODUCTION A positive workplace environmental, health, and safety (EHS) culture affords organizations and corporations many benefits, including increased trust and employee morale, sustainable EHS performance improvements, and reliable productivity and profit margin growth. Unfortunately, many leaders and EHS professionals struggle daily to achieve and maintain positive workplace cultures and consistent business results. While lack of management support, corporate or employee buy-in, resources, and time are common factors that conflict with an EHS culture and safe work behaviors and processes, there are many other actions that threaten the positive attributes of an organization’s culture. Often these culture killers are not recognized, or worse yet, ignored because they are considered taboo. For example, voicing observations or questioning long-held management practices or process that were initially designed to promote EHS values, but no longer do so. Unfortunately, this could be viewed as challenging authority, not being a team player or even not valuing EHS. And for those that speak up, the potential for negative consequences can be real impediments to positive change. Having an open mind, constantly striving to identify culture killers, and putting forth the effort to eliminate them are the first steps to begin reaping the benefits of having a sound workplace culture. This paper helps readers to: • Recognize culture killers that negatively impact fostering and maintaining sustainable EHS cultures in the workplace. • Understand how to prevent, avoid, and respond to culture killers, before they wreak havoc in your organization. • Assess EHS culture strength, and implement plans to continuously improve it. The desire to draw boundaries around concepts, put things into boxes, and nail down requirements for something that is virtually impossible to solidify for any length of time is quite fascinating! These desires can pose challenges when trying to define what the perfect EHS culture should look like. The very act of trying to define our culture tends to create silos, and these silos, in turn, can become “culture killers”. The following is one of the most common culture killers. UNBALANCED ORGANIZATIONS TRIGGER CULTURE KILLERS Unbalanced organizations occur when an organization’s constantly shifting focus forces other important needs to take a back seat--until the focus changes again. This balancing act can be detrimental and lead to catastrophic results including low morale, lack of trust, employee dissatisfaction, high turnover, increased incidents, poor profit margins, loss of market share, and ultimately into organization-wide failure."

Jan 1, 2018

By B. L. Gibbs

The mining industry is constantly in a state of flux -boom or bust; mine openings and closings. Part of the reason is the nature of ore deposits -they are there or they are not. Once they are mined, they are reclaimed and the move is on to the next deposit. Risks are usually high, and payoffs can be great or not so great. Many factors go into making a property payoff, and mining companies are continually searching for ways to remain profitable as long as possible. Computers and the people who can make them work are one of the ways available to improve productivity and ensure this happens. Computers have been used in the mining industry for the last 30 years (and more in a few cases). During the past 10 years, the explosion of micro-computing has changed how many mining companies do their work.

Jan 1, 1993