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By CORA ROELOFS

While the COVID-19 pandemic has dominated the headlines, another epidemic in the United States has continued apace — the opioid epidemic. Half a million opioid overdose deaths have occurred in the United States since 1999, when the opioid epidemic began. The causes of the epidemic include the rise in prescriptions for opioid pain medications, including for work-related pain. Miners and other occupations identified as physically demanding and at higher injury risk have been found to be at increased risk for opioid overdose [1]. However, awareness of the risk factors that might lead to opioid use, the potential hazards associated with their use, and resources to prevent addiction and death can allow miners to make choices that can reduce these risks.

There is wide agreement that sustainability has multiple dimensions, but substantially less agreement on the appropriate balance among those dimensions. This occurs because peoples’ vision of a sustainable future, their goals for sustainable development, and their objectives for resource management are reflections of their values, culture, and life experiences. Even assuming agreement about the objectives of sustainable resource management can be reached; there is still a need for policy and decision makers to choose from among alternative courses of action, each of which has its own set of impacts and outcomes. One of several tools used to compare the consequences of alternative actions is the Computable General Equilibrium (CGE) model. This paper uses CGE modeling to demonstrate how policy decisions do not take place in a vacuum and how policy-makers must be aware that there are trade-offs involved in any decision.

Jan 1, 2005

By Otto E. Zwanzig

You may think long before this talk has been completed that the speaker is belaboring the obvious. Please let me put to rest here and now any doubt which you may have in this regard by assuring you that is precisely my intent, and for a very specific reason. We all profess to know and recognize the obvious, but I am impressed increasingly how often we forget or fail to act upon the obvious. Shortly after starting my first job upon graduation from college, I was asked by my boss to participate in a course on practical communications, particularly as applied to conveying proposals effectively to the client -- be he customer or company president. The concept or philosophy underlying this program was so simple and obvious that in my youthful brashness I saw only a gross waste by the company of e good, solid $1930 in compelling me to take the course. The sequel to this experience occurred about five yews ago when I was directing a 300-man marketing group. At that time I enrolled a dozen of my department heads, and subsequently about a hundred other personnel, in the contemporary version of that sane program. Why? -- because they all knew the obvious, but I could see how imperfectly they were implementing it. Truly, a wide chasm exists all too often in our beliefs on the one hand and our practices on the other.

Jan 1, 1962

By H. B. Oblad

The WEMCO® SmartCell™ flotation machine is a continuously-stirred tank reactor in which solids are suspended in water and are contacted with air. The reaction is particle flotation resulting in the separation of valuable material from gangue. The effects of several operating variables on the flows of water and air and on motor power were measured. A miniature magnetic flowmeter was installed in the draft tube that allowed measurement of the water flows into the rotor. This work has led to a better understanding of machine function which will lead to improved performance and better operation. General equations for optimization, design, and scale-up were inferred.

Jan 1, 2002

By D. L. Stevens

Following an in-depth scenario and strategic planning exercise in 1997, Noranda's mine production goal was set at 500,000 tonnes per year of both copper and zinc metal within five years. There had been no recent discoveries, reserves were shrinking and things had to be done differently and quickly. Change is now continual in our program but here is what we did first: Combined the exploration and business development groups Formed teams to search for and respond to opportunity Made our geologists more business minded and our engineers more optimistic Went global Set clear thresholds, farmed out the marginal properties, fast tracked the others Focused reconnaissance exploration where we had a clear competitive advantage Became a "flexible" partner to both juniors and seniors Is it working? A number of successes, near successes, and outright failures are discussed. The main result is a much higher rate of opportunity flux which is essential for success in the mining industry.

Jan 1, 1999

By Hasan Nizamoğlu, Z. Abidin Sarı, Aslıhan Demiraslan, M. Deniz Turan, Tolga Depci

In this study, recovery of copper from solid material (obtained by leaching of chalcopyrite with oxalic acid in the presence of hydrogen peroxide) with a copper oxalate structure was carried out selectively using HCl. The chemical composition of the solid was as 29.3%, 9.7%, and 13.3% for Cu, Fe, and S, respectively. Selective recovery of copper by degrading the copper oxalate structure with a low-solubility product (Ksp = 4.43 × 10−10) was performed by conventional leaching in the presence of HCl. The optimum leaching conditions were determined as 5 M of HCl concentration, 318 K of leaching temperature, 120 min of leaching time, 25 ml/g of liquid–solid ratio and 400 rpm of stirring speed. Under these conditions, approximately 77% of copper and 3% of iron were taken into the solution. According to the characterization of the leach residue that was obtained, the oxalate structure was degraded. Moreover, the results of XRD analysis showed that the sulfur (S) and cubanite (CuFe2S3) phases were mostly observed in leaching residues, and this was supported by the SEM-EDX data. Based on the results, it may be stated that selective copper extraction can be obtained from a chalcopyrite concentrate by a two-step leaching method using a conventional hydrometallurgical technique.

By G. H. Kuhnhausen

The Bear Creek Uranium Mill was designed in 1975 to process 909 tonnes per day (1000 STPD) of low-grade uranium ore from the Powder River Basin in Wyoming. The mill was expanded to 1818 tonnes per day (2000 STPD) in 1979. The Bear Creek Uranium Project is owned by the Bear Creek Uranium Company, a partnership of Rocky Mountain Energy Company and Mono Power Company. The original mill design contemplated processing ores from Bear Creek Uranium Company properties exclusively. The expanded capacity has been utilized for tolling ores from Kerr McGee Nuclear Corp. and other mining companies in the region. This paper describes the process of designing the original mill, the lessons learned from operation, and the design of the process modifications required for expansion. The project background, design philosophy, design basis, design criteria, actual flowsheet, special design considerations, and a comparison of assumed operating conditions and actual operating results will be presented. Bear Creek Uranium Company wishes to thank and acknowledge the help granted by the many operating companies who provided invaluable information, insight, and critique of the Bear Creek design through all the various stages and were instrumental in the successful completion and start-up of the mill. Without their contributions, the design philosophy used at Bear Creek would not have been possible and the results obtained would surely have been less satisfactory.

Jan 1, 1979

By Kenneth J. Miller

A novel two-stage froth flotation process to remove pyritic sulfur from fine- size coal is described. The process consists of a first-stage, standard coal flotation step in which high-ash refuse and some of the pyrite are removed as tailings. The first-stage clean coal froth concentrate is then repulped in fresh water, and a coal depressant, a pyrite collector, and a frother are added to float the remaining pyritic material. Laboratory and pilot plant flotation results with coals from the Lower Freeport and Pittsburgh beds are given. The pilot plant test results show that up to 80 percent pyritic sulfur reduction was achieved with the Lower Freeport bed coal and up to 50 percent with the Pittsburgh bed coal. Laboratory and pilot plant results were in excellent agreement, indicating that the process is a viable means of removing much of the sulfur from some coals.

Jan 1, 1974

By M. A. Berdine, C. N. Thompson, D. Brock

The raise bore method of shaft construction has been success-fully used in the mining and construction industries for over thirty years. In the mid 1990’s, Twentymile Coal Company (“TCC”), now affiliated with RAG American Coal Company, used this method for a moderately deep small diameter shaft and the raise bore and slash method for a shallow larger diameter shaft. In late 2001, TCC contracted to raise bore a 431-meter deep, 6.2-meter diameter shaft. During the raise bore and shaft lining processes, regional horizontal stress fields resulted in extensive elliptical caving beyond the original design diameter. This paper discusses the engineering approaches and procedures used to safely complete construction of the raise bore shaft.

Jan 1, 2004

By S. K. Kawatra

A high calcium fluid-bed combustor ash has been shown to be an effective binder at dosages of 1 to 2% of the magnetite concentrate weight. Magnetite pellets 1.3 cm (1/2 inch) in diameter were produced with dry crushing strengths greater than 22.3 Newtons/pellet (5.0 pounds force/pellet), which is comparable to the results produced using conventional bentonite binder. The effectiveness of fly-ash-based binders was considerably improved when calcium chloride was added as an accelerator. Addition of calcium chloride at a rate of 0.1 to 0.2% of the total powder weight increased the strength of dried pellets by as much as 22% compared to the strength of pellets made using fly-ash without accelerators.

Jan 1, 1997

By Harry Teicher

The subject of Specialty Silica Products could encompass a broad range of materials, some of which would be familiar to members of the Society of Mining Engineers. With the concurrence of your chairman, I have chosen to limit my remarks to synthetic materials, not including such siliceous materials as diatomaceous earth, asbestos, quartz and clays. For purposes of discussion, I have classified Specialty Silica Products into two groups -- powders and liquids -- which I will discuss in that order and which are categorized in Figure 1. The synthetic silica powders are amorphous to x-rays and are manufactured by various processes resulting in products of a wide range of physical and chemical properties, as well as functional performance and applications. Applications or functional properties are generally dependent upon such physical properties as micron-sized particles exhibiting large surface areas per unit weight and low apparent bulk density. Their presence in various systems modify surface properties. As summarized in Figure 2, they act as viscosity modifiers, flow conditioning agents, anti-slip agents, anti-blocking agents, flatting agents in surface coatings, reinforcing agents in polymers such as silicone rubber and numerous other applications. Although the various types of silicas exhibit various levels of functional performance in these end uses, they are not usually equally effective as direct replacements and I will briefly discuss the various types of materials.

Jan 1, 1974

By Malcolm D. Flavel

As indicated in the introduction to this paper, it is a sequel to that which I gave to the last annual meeting in Atlanta in march. This paper goes further into aspects of crushing and screening, primarily from the standpoint of circuit control. There has been little published by equipment manufacturers on this subject and this is the first paper on crushing circuit control to be sponsored by Allis-Chalmers corporation. By proper control over the use of crushing energy, we will be able to produce finished products from feed materials uti¬lizing minimum capital for the lowest cost of production. The subject will be discussed as follows. Firstly, we will look briefly at what we are trying to accomplish; Secondly, what is presently available in the way of technology; Thirdly, we will look at a suggested new system of control which will best fit the parameters of the normal crushing and screening operation; As a conclusion, I will summarize the advantages of the new system.

Jan 1, 1977

By Leonard Bronitsky

The construction mineral aggregates industry--the largest industry on a tonnage basis--is threatened with large shortages in the near future. Ironically, these common minerals which include sand, gravel, and stone are among the most plentiful in the earth's crust. However, as these minerals are low in value and used in large volumes, they are extremely sensitive to transport cost, e.g., a haul of 20 miles doubled the delivered cost of mineral aggregates. Consequently, these minerals must be located close to points of demand to have economic usefulness. But the development of new deposits is virtually impossible near many urban areas for legal, sociological and economic reasons. The spector of unfinished urban transport systems, curtailed residential construction, and a general deterioration of the physical urban plant, looms as a direct consequent of future mineral aggregate shortages in the U. S. metropolitan areas. The shortages of mineral aggregates in the Greater New York Metropolitan Area (G.N.Y.M.A.) are prototypical of the shortages faced by the U. S. Metropolitan areas. This paper presents an economic analysis of the consequences of not considering the broad aspects of conservation economics as a major component of resource management. The needless annual cost for the G.N.Y.M.A. is shown to be $30 million.

Jan 1, 1974

By A. E. J. Gallagher

There are many influences which have a bearing on the economics of industrial minerals production. The purpose of this paper is to discuss briefly three factors which have economic significance in the production of these mineral commodities. The three items of discussion include 1) the nature and relative value of the industrial minerals group, 2) project planning, and 3) market analyses. General aspects of these factors are familiar to most of us. However, an attempt will be made to give some current details regarding each. Also, in reality, project planning and market studies are usually so closely associated that they will be discussed jointly, rather than separately. This will be done by way of examples which show how these two activities actually evolved for two industrial minerals projects.

Jan 1, 1984

By Judson H. Whitman

To evaluate intelligently and to market a source of rare earth raw material, it is necessary that the producer understand the requirements of the processor and the manner in which these requirements effect the value and salability of his product. This paper will be an attempt to aid in such an understanding. The majority of rare earth processors are primarily chemical companies, not mining or metallurgical companies, as the complexities of the processing procedures are' much more chemical in nature than metallurgical. The rare earths and the rare earth industry are normally divided into two groups - the ?light? or cerium group and the ?heavy? or yttrium group. They are so named because cerium and yttrium are the most common elements in 'heir respective groups and are so divided on the basis of mineralogical and chemical characteristics. The dividing line of the two groups is not rigidly fixed but usually is considered as being between samarium (atomic number 62) and europium (atomic number 63). Although the two groups are quite similar, processing procedures differ significantly, hence most processors tend to specialize in one group or the other. There is, however, a growing tendency toward participation in both groups.

Jan 1, 1960

By Andrea Brickey, RICHARD AMOAKO, Akshay Chowdu

Production forecasts derived from the medium-term schedule represent the best path forward for underground mining operations to achieve corporate and operational goals. Unforeseen circumstances, such as equipment breakdown, can cause significant deviations from established production forecasts in the short term. Such situations require timely mitigation of the effects of the deviations in order to stay as close as possible to the medium-term plan. This paper presents a deterministic mathematical formulation for short-term scheduling that addresses this challenge. The formulation is able to make up for deficits resulting from operational disruptions by minimizing deviations from medium-term production goals and medium-term activity start dates. We demonstrate this in a case study by simulating disruptions involving reduction in ore extraction capacity and development advance rate. Aside from the rescheduling capability, this formulation can help mine planners conduct analysis on the impact of various disruptions on the schedule. The formulation can help identify those conditions or disruptions that are more detrimental to the achievement of forecast targets, or otherwise. The formulation also affords mine planners the flexibility to prioritize one production goal over the other, depending on operational conditions at the mine. In the future, we seek to incorporate in the formulation respirable dust, diesel particulate matter and ventilation constraints in order to create more realistic schedules, and enhance miners’ health and safety.

Jan 1, 2024

By Christopher Mark

Horizontal stresses are caused by global plate tectonic forces. During 1995 alone, they were largely responsible for closing two U.S. longwall mines. This paper presents six case histories from Pennsylvania, West Virginia, Kentucky, and Alabama. In each case history, a mine encountered roof falls or difficult ground conditions in the headgate, caused by horizontal stress concentrations. The problems are detailed, and the control measures adopted are described. In most cases, nearby longwall panels without stress concentrations were trouble-free. The paper also discusses detailed measurements made at two adjacent Pennsylvania longwalls. One headgate was oriented to avoid a horizontal stress concentration, and the other was not. Eliminating the stress concentration dramatically reduced roof support loads and roof deformation. The paper concludes that proper panel orientation and sequence is the key to maintaining headgate ground control. The optimum orientation is not parallel with the maximum horizontal stress, as previously thought, but rather 20° in the stress shadow of the gob. Other stress control techniques, including artificial support, are briefly discussed.

Jan 1, 1997

By Frederic Chavan, Hans Jakob Windier, Shane Yanagisawa, Willy Ritz

The Zurichberg twin track tunnel is the main segment of the Swiss Federal Railway's new expressline. A heavy concrete lining with a circular cross-section was chosen to cope with the swelling tendency of the surrounding rock. The 4,356 m (14,300 ft) long, 11.52 m (38 ft) diameter tunnel was driven using a shielded Robbins TBM. A 1.20 m (4 ft) wide, 25 cm (10 in) thick precast lining was placed from within the shield tail as the excavation progressed. Tunnel excavation and initial lining operation were completed in 18 months, averaging 11.86 m/day (40 ft/day) in two nine hour shifts. After breaking through, the final 28 cm (11 in) thick concrete arch lining was cast in place.

Jan 1, 1989

By S. S. Peng

In this paper, the precise definitions for a number of commonly used subsidence parameters are given. The subsidence parameters have been determined using an integrated approach for 110 subsidence cases collected in the major US coal fields. Attempts have been made to establish empirical formulae for the parameters. The results of this study indicate that some traditionally-held concepts should be changed.

Jan 1, 1995

Sphalerite is commonly floated in an alkaline environment and under such conditions the overall activation mechanism is obscured by the hydrolysis of Cu2+ and precipitation of Cu(OH)2. Electrokinetic and kinetic flotation tests show that the activation of sphalerite is a two-stage process; the activation products formed on the surface of sphalerite in near neutral and in alkaline solutions in the first rapid activation stage are "flotation-inactive". These layers, when formed in an alkaline solution, are unstable and are transformed into the "flotation-active" form in the second stage. However, the surface layers formed during activation in alkaline environment by copper in the presence of lead ions are very stable and even after a long conditioning time the flotation rate is not improved. Consequently, while both Cu2+ and Pb2+ activate sphalerite flotation, quite unpredictable effects may result when both are present in the solution.

Jan 1, 1997