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By Dennis R. Twining

Recently a mining analyst for a major bank called me to say that during his travels he had encountered an electric utility interested in a new uranium supply. Since we produce uranium as a by-product of phosphate operations rather than as a primary product, he assumed we simply sold our output in the spot market and that a new prospective purchaser would be of interest to us. This assumption was incorrect; the uranium had already been sold on a long term basis at terms more favorable than the currently depressed spot market. From the outset our approach to the marketing of uranium was based on the principle that by-product marketing is not unlike primary product marketing. This was particularly appropriate in the case of uranium, as we were planning a considerable technical and capital commitment to a new business. This illustrates: that the fundamental principle in by-product marketing is to follow a primary product strategy; that the terms "by-product" or "co-product" are creations of accountants; that they have no place in marketing decisions! Traditionally, the term "by-product" has implied that only a secondary marketing effort is required. Recent history has contradicted that view by demonstrating that by-product values can have marked impact on a mine's revenues and costs. In fact, by-product values can spell the difference between success and failure.

Jan 1, 1983

By G. Bonifazi

In the present work the possibility to utilize the morphometrical and morphological characteristics of an articulate solids system in a slurry flow to monitorate and to control a continuous process is considered. This goal has been reached by mean of an optical system able to acquire, to handle and to process the pictorial information derived by a suitable hardware architecture designed to realize the best lighting, focusing and sampling conditions for the examined flow stream domain. The procedure has been tested using different flow stream slurries coming from different sections of a beneficiation plant. A suitable strategy and a consequent software architecture has been set up in order to assure to the system the necessary speed and the stability to achieve correct on-line measurements and control.

Jan 1, 1994

By I. M. Stewart

In a proposed rulemaking regulating asbestos, nonasbestos varieties of Tremolite, Anthophyllite and Actinolite would be excluded from the regulations controlling permissible exposure to asbestos fibers. This proposed rulemaking is perceived as improving the scientific basis of the regulation of asbestos because it recognizes that there are no scientific data, either mineralogical or health related, which support the regulation of nonasbestos Tremoiite, Anthophyllite and Actinolite in the same manner as asbestos fibers. However, the proposed regulation, while representing a major advance in the treatment of AT A for regulatory purposes, does not provide an adequate analytical method for distinguishing between asbestos and nonasbestos particles, nor an adequate description of the regulated minerals. This paper addresses those topics, recommending that OSHA include an appropriate mineralogical definition, and implement a discriminate counting procedure to distinguish asbestos from nonasbestos particles.

Jan 1, 1992

By Joseph Githiria, Khadija Omar Said

Mineable material is defined using cut-off grade either as geological or economic cut-off grade. Both geological and economic cut-off grade affects the output generated in an open-pit mining operation. It distinguishes the amount of ore sent to the mill for processing and waste to the dump. This consequently affects the overall profits generated from the operation hence the need for cut-off grade optimization. There are several mining parameters that are considered in a typical cut-off grade model. They include economic, geological, and operational parameters. They have a significant effect to influence the cut-off grade selected in mining operations at any given period. Some of the parameters are stochastic in nature by having a random probability distribution that may not be predicted precisely. When selecting cut-off grades in a mine operation, the mining engineers must consider the dynamic nature of the operational parameters in order to maximize the net present value of the project. Modifying Lane’s cut-off grade model which was developed in 1964 to incorporate the stochastic parameters in the approach helps improve the net present value as shown in the paper. The modified Lane’s approach is developed into a stochastic computer-aided application code-named NPVMining. Using NPVMining, selected stochastic parameters are considered in this exercise to show the effect on the output (net present value). The selected parameters (price and grade-tonnage) are varied by ± 10%. NPVMining has a graphical user interface that makes it easy to use and displays results in a user-friendly way. It gives the user the choice to manipulate the data depending on the study being undertaken or any other factor affecting the specific mine. This paper analyses the effect of each of the selected mining parameters on cut-off grade using NPVMining to show the significance of monitoring their variance.

Jun 25, 2023

By J. D. Brown

The purpose of this paper is to inform members of the coal producing and consuming community about techniques used by The Carter Mining Company to control product quality at a large surface coal mining operation. During the early years of mining operations, coal quality received adequate attention but the Company's main emphasis was to build up its production rate and minimize mining costs. While these goals are still of prime importance, coal quality has received substantial attention in recent years. A Company guideline that no coal shipment shall exceed any contract or company-imposed coal quality specification has been successfully implemented. To implement this guideline, geology and coal quality modeling procedures were improved, in-pit drilling and blending programs were refined, and detailed shipment procedures were developed. Background Surface coal mining of subbituminous C rank coal in the Cillette. (Campbell County) Wyoming area has become increasingly competitive during recent years. Prior to 1974, one small surface mine produced coal for local consumption. During the last ten years, 13 new surface coal mines have been constructed. Coal production from Campbell County, Wyoming totalled 88 million short tons (79.8 million metric tons) in 1983, the majority being shipped to electric utilities in the central and southern United States via unit trains having a capacity of 10,000 short tons (9,072 metric tons).

Jan 1, 1984

By Robert E. Jones

The barite industry shares with its associates in the minerals industry the impediments of excessive federal and state regulations. We have learned to exist with the Organic Act of 1976, the Mine Safety and Health Act of 1966, and the Multiple Use Act of 1955. I do not mean to imply by the above that all aspects of mining legislation have been detrimental, however, each of you has been subjected to interpretative restrictions by federal or state bureaucrats. As frustrating and costly as this is to the barite industry, it is not the primary problem facing our segment of the industry at the present time. Our major difficulty today deals not with too much government regulation, but with the lack of a cohesive and consistent government energy program. This administration and those that have preceded it have dealt with intermittent energy crises on an emergency basis. If we remove the political rhetoric which has surrounded each of the more recent major crises, we can liken the action of our federal government to that of a rural volunteer fire department which devotes its entire efforts toward extinguishing existing fires rather than the developing of programs designed to prevent future fires. The lack of a comprehensive energy program has created an environment in which long range planning is extremely difficult, if not impossible.

Jan 1, 1983

In this study, numerical simulations of yield pillars employing the finite element method with time-dependent Drucker-Prager material model are conducted. The stress control mechanism of yield pillars on weak floor strata is studied. The development of pillar yield zone, the distribution of pillar stress and the development of failure zone in the weak floor strata are investigated. The study indicates that a properly selected yield pillar size may significantly reduce the peak stress induced in the weak floor strata and effectively control the development of failure zone in the floor.

Jan 1, 1999

By L. F. McHugh

Molybdenum conversion operations discussed in this paper encompass all major operations commercially used to upgrade molybdenite concentrates to various refined products. More emphasis is placed on discussion of key pyrometallurgical unit operations. These operations conducted at Metec include roasting, sublimation, and hydrogen reduction

Jan 1, 1986

By Sukumar Bandopadhyay

In recent years, research in the field of artificial intelligence (AI) has had many important successes. Among the most significant of these has been the development of powerful new computer software known as the "expert systems". Expert system programs designed to provide expert-level consultative advice in mineral exploration (Duda et al, 1981), scientific (Feigenbaum, Buchanan and Lederburg, 1971) and medical (Shortliffe, 1976) problem solving are generally acknowledged to be among the forerunners of this research. As the decision makers virtually in all fields face a more complex and involved world within which to operate, the need for some decision support is also becoming urgent. Thus applications of expert systems continue to spread out reaching problems that, because of their dimensions or particular aspects, set more demand on the decision methodologies. To meet these new requirements, many activities which were performed in the past by the domain expert or engineer must become automated. Furthermore, previous research (Dawes and Corrigan, 1974; Dawes, 1979) has shown that automating an expert's decision rules often provide better decision than the expert does. For large systems it would be very useful (or even necessary) to have formal tools, allowing one for example, to automatically discover inconsistencies, contradictions or redundancies, or to identify the possibilities of wrong lines of reasoning in the decision process.

Jan 1, 1990

By B. K. Baird

The application of cutoffs during and after pit optimization is examined for a lower-grade multi-metallic copper deposit. Pit optimization requires calculation of the net revenue associated with each mining block, incorporating parameters such as metal prices, grades and expected recoveries, mining and processing costs, smelting and refining charges, and penalty element and royalty charges. Sensitivity analysis during pit optimization reveals which of these parameters have a significant effect on the total contained resource tonnage and total contained non-discounted revenue in the optimized pit. The cumulative effect of changing several of the more significant parameters is investigated. Application of a copper cutoff grade to a block inside the optimized pit could result in the less than optimal extraction of the resource. A block with copper grade below the applied cutoff could be economic due to the presence of other metals. Conversely, a higher copper grade block may be sub-economic. The relative merits of applying a copper grade cutoff, "equivalent grade" cutoff and dollar value per ton cutoff to blocks inside the optimum pit are discussed.

Jan 1, 1999

By Syd S. Peng

The key design parameters of roof bolting using expansion - shell type support for underground coal mine roof support are bolt length, bolt spacing, installed load and anchorage capacity. Depending on the utilization of suspension effect or friction effect, the bolt length is dictated either by the distance between the roof surface and the first overlying strong strata encountered or the desired magnitude of reduction in bending stress at the roof surface, The current prevailing practices about the bolt spacing and installed load are that an initial torque of 125 - 170 ft-lbs is applied and the bolts are spaced at 4- or 5- ft. square grid pattern. This seems to be a rather broad generalization in view of the great geological variances which are expected in underground coal mines. A modest evaluation program to measure the effectiveness of current roof bolting practices is to monitor the load history of roof bolts during a complete mining cycle including the phases of room development and pillar robbing. The load history, when compared with the anchorage capacity of roof bolts determined by in-situ pull tests, will provide information for evaluating the installed load, the bolt spacing as well as the specifications for structural and anchorage characteristics of the bolt assemblies. This paper presents a case history of monitoring the complete load histories of roof bolts in an underground coal mine of Pittsburgh seam.

Jan 1, 1976

By W. Rocher

The Minera Ojos Del Salado (?MINOSAL?) concentrator is located 20 kilometers southeast of Copiapo, Chile and processes copper ore provided by its Santos and Resguardo mines at a capacity of 4,200 tip (4,620 stpd). Phelps Dodge acquired the majority interest in MINOSAL in 1982. The principal incentive for this purchase was the exploration potential of the property. At that time, the concentrator plant was a small, antiquated installation with a capacity of 674 t/d (740 stpd). In 1982, the majority of the ore was produced from the Santos and Resguardo mines, but custom ores of copper, silver, and gold were also treated. The acquisition occurred at a crucial time in the copper business, since the price had fallen to nearly $0.50 per pound. In 1985, Phelps Dodge purchased the outstanding interest in MINOSAL and acquired 100% of the property. Today, after numerous improvements and two expansion projects, the concentrator is an interesting combination of old and new equipment. The regrind mills, for example, have been in service for about 50 years, while the ceramic concentrate filter represents the latest technology.

Jan 1, 1993

By L. O. Bond

High costs--and high risks--are normal in coal exploration and mine development. But risks and ultimate costs are minimized by foreknowledge of prospective coal seams and adjacent formations. Extensive drill hole programs are often used to obtain needed information. Cores and cuttings from these holes are used to determine coal location, thickness, and quality; they are also used to study physical and geological characteristics of surrounding beds. Valuable as these core and cuttings studies are, their effectiveness is often diminished by loss of recovery or by incomplete analysis. Needed is an effective and economical method for augmenting these studies. Well logs provide information of the type needed for efficient cool prospecting. Furthermore, obtaining these logs in drill holes, and evaluating the data they provide, is both fast and economical. To investigate the usefulness of well logging methods in coal explorations, the authors worked with Mr. Jon Jenkins of Truax Truer Coal Company. Logs were run in a number of drill holes in various areas of the Illinois Basin; these areas provided variety both in coal quality and geologic conditions. The data were studied extensively using computer methods similar to those now used in the evaluation of oil and gas wells. (2, 3) This study was used to produce a computer-generated analysis designed especially for mining problems.

Jan 1, 1969

By L. C. Atkinson

A three-dimensional finite element Ground-water flow code has been developed that incorporates saturated/unsaturated, two-regime flow (i.e., both Darcian and non-Darcian) and solves for the seepage face at a surface of outflow. This code is capable of more realistically predicting ground-water inflows to an open-pit mine under the throttling effects of non-Darcian flow. The height of the seepage face on highwalls and the shape of the phreatic surface in the vicinity of the pit that it calculates can also produce more probable estimates of pore pressures for analysis of slope stability.

Jan 1, 1992

By J. J. Schwoebel

Resource Enterprises, Inc. (REI) is exploiting the coalbed gas resource by working in unison with active underground mining operations. At REI?s pilot project at the Soldier Canyon Mine, Carbon County, Utah, REI has drilled nearly 15,250 m of horizontal in- seam and slant boreholes during the initial two years of drilling activity. Produced gas has been sold to a natural gas transmission company on a continuous basis since mid 1983.

Jan 1, 1986

By R. P. King

A new device, called the dual impact load cell, has been developed and built at the Comminution Center to measure fracture energy and damage accumulation in brittle particles that are subject to impact. The results show that damage accumulation during impact is not a significant factor in determining the fracture energy or the particle strength. However, predamage induced by thermal pretreatment of the particles has a significant effect on both fracture energy and particle strength.

Jan 1, 1995

By D. W. Fohlen, B. A. Filas

The International Finance Corporation (IFC), the private investment arm of the World Bank Group (WBG), requires all IFC-financed projects to comply with its environmental and social policies and guidelines. IFC's review process involves an environmental and social assessment and the implementation of an Environmental Action Plan (EAP) that will set forth the necessary actions to bring the operation into compliance. This paper provides an overview of the environmental and social policies and guidelines that apply to mining projects and examines how WBG/IFC policies and guidelines are applied to mining projects in developing countries. In addition, it includes a review of the increased emphasis IFC is giving to social issues over the past several years based on the existing WBG policies. IFC’s process for the environmental and social review of proposed investments is briefly discussed. The paper focuses on how IFC emphasis has shifted from the traditional environmental and impact mitigation analyses of a few years ago to the integrated social and environmental awareness, action (EAP), and implementation programs (social plans) required today. Today, IFC's focus is to promote sustainable development by investing in projects that directly benefit local communities and the environment. Examples of these changes will be highlighted by a review of recent investments located in West Africa. The goalposts have not moved, but the rules of the game have become tougher.

Jan 1, 2001

By M. Sengupta

Surface mining in arctic regions is characterized by many unique problems. Continuous and discontinuous permafrost (perennially frozen ground) occurs in most of the arctic and subarctic areas. Permafrost presents special problems of slope stability. Stability of permafrost depends on its temperature, moisture content and material type. Permafrost slope fails due to solifluction, disturbance of ice rich slopes, and liquefaction. Drilling and blasting of frozen ground present special problems. Depending on their degree of saturation with water, freezing soils and rocks have a number of important characteristics that affect blasting efficiency. Metals used in mining equipment and mining structures require special selection. At low temperatures many steels lose most of their normal ductility and toughness (resistance to brittle fracture). The paper discusses engineering solutions to unique problems of arctic mining.

Jan 1, 1986

By Harold A. Taylor

The first use of graphite is lost in the mists of time. It was used by primitive man to make drawings on the walls of caves and by the Egyptians to decorate pottery. As early as 1400 AD graphite crucibles were being made in the Haffnerzell District of Bavaria. Through the Middle Ages graphite was confused with other minerals, especially galena and molybdenite. Two common names that are still being used for the mineral are plumbago, meaning lead-silver, and black lead. The latter name implied that graphite is either composed of lead or at least contains a large percentage of it. Gessner is credited with having recognized it as a separate mineral in 1565, but its composition was not determined until 1779, when Scheele demonstrated that graphite oxidized to carbon dioxide, thus proving its carbon constitution. In 1789, Werner named it graphite from the Greek word graphein, meaning to write. The United States has long relied on foreign countries for its graphite supplies. This reliance has been due more to the lack of suitable domestic graphites than to any particular preference for buying minerals overseas. Sri Lankan graphites were imported as early as 1820, and Madagascar graphites have been imported since the properties on that island were opened up about a hundred years later. Mexico has long supplied the United States with most of its requirements for amorphous graphite.

Jan 1, 1994

By D. Antonov

The physical and mechanical properties of coal play a important role in the planing and design of coal mines. However, due to the complexity conditions in situ and the influence of unknown factors, it is hard for people to evaluate the physical and mechanical properties of coal directly. In this research, uniaxial compressive stress was used to change the attribute of coal samples, and the ultrasonic measure technique was used to evaluate the physical and mechanical properties of coal. The results of laboratory test showed that there was a strong relation between uniaxial stress and velocity of ultrasonic wave. Sensitivity analysis with numerical simulation was used to define the relation between the physical-mechanical parameters of coal and ultrasonoc wave. With the dynamic analysis module of FLAC, three elastic and plastic models were built to model the coal samples. The modeling parameters were changed pro rata, and the correlation of coal and ultrasonic wave properties were summarized and presented. The result from this research will be base for further analysis of caving behavior of coal.

Jan 1, 2010