Search Documents

By Daryl R. Tweeton

The Bureau of Mines measured the geochemical changes as H2S04 was used for in situ uranium leaching by Rocky Mountain Energy Company near Casper, Wyoming. Cores and ground water were analyzed before leaching. Water samples were taken from observation wells located between injection and production wells as the leach solution was brought up to full strength in several steps. Measurements were made of pH, Eh, temperature, conductivity, total dissolved solids, dissolved oxygen, HC03, U, V, Na, K, Ca, Mg, SO4, C1, Mo, Mn, Fe, Al, Si, F, P, As, and Se. The data were gathered to assist in geochemical modeling of leaching and to study the potential environmental effects of acid leaching. Environmental considerations appear favorable. For example, the concentration of Se, a toxic element often found in uranium deposits, stayed below the EPA standard for drinking water.

Jan 1, 1979

By D. Potter

Freeport Exploration initiated regional reconnaissance exploration programs in Irian Jaya, the easternmost province of the Republic of Indonesia in 1990 (see figure 1). Irian Jaya occupies the western half of the island of New Guinea. Freeport was awarded an initial contract of work which totaled 2.6 million hectares (6.4 million acres) and was subsequently awarded additional?concessions which added 1 million hectares (2.5 million acres). The concessions require work commitments and periodic relinquishments. Due to these relinquishments Freeport?s current land position totals l. 9 million hectares (4.7 million acres).

Jan 1, 1998

By C. L. Schneider

The calculation of the liberation spectrum in the product from continuous milling operations is a problem of considerable importance and is difficult to solve because the population balance equation must be integrated in two-dimensional space. Complete solutions require the estimation of a large number of parameters unless a structural model of the ore texture can be used. A very simplified textural model based on the use of the modified Andrews-Mika diagram and the PARGEN simulation of multi-phase particles has been formulated and is used to simulate the behavior of a continuously operating laboratory ball mill. A sensitivity analysis for this mill has been done to show the likely effect of model approximations on the predicted liberation spectrum which will be measured.

Jan 1, 1992

By J. R. Sims

Gold assays from production blastholes in the Mercur Hill Pit were used to delineate known ore zones and to determine how well previous exploration drilling defined these zones. The most important factors causing inadequate ore zone definition were: 1) inappropriate location of drill holes relative to the ore zones, 2) presence of stopes from previous mining, 3) sampling and assaying errors, and 4) smoothing of the ore zone boundaries during ore reserve estimation. Infill drilling strategies were evaluated to determine the efficiency with which a given drill pattern defined the known ore zones. A drilling strategy was developed which improved ore zone delineation when compared to techniques which maintained uniform drill spacing.

Jan 1, 1992

By Alfredo Valencia-Toledo

This study delves into the satisfaction levels of indigenous communities in Apurimac-Cusco, Peru, concerning mining activities in their region. Our primary objective is to elucidate the interrelationships among observable variables, which are conceived as linear combinations of multiple factors. Employing the statistical methodology of exploratory factor analysis, we aim to pinpoint the pivotal factors influencing the progress of mining activities in Apurimac-Cusco. Through our analysis, we have identified eight key factors that exert a significant impact on mining’s sustainable development in the area. These factors encompass diverse facets, ranging from the support offered by mining company to communities, environmental considerations, education, economic factors, provision of basic services, transportation and communication, support for social organizations, and social-health-related aspects. This research endeavors to provide a comprehensive understanding of the complex dynamics surrounding mining activity satisfaction among the indigenous population, offering a basis for further exploration and policy development.

Feb 17, 2024

By John B. Goddard

In-situ leaching of uranium by aqueous ammonium carbonate containing oxygen or hydrogen peroxide as oxidant results in the partial dissolution of sulfides. While some of the sulfide sulfur is oxidized to sulfate, a considerable portion is oxidized only to thiosulfate and polythionates. Polythionates poison the anion exchange resin used to extract uranium. At the Palangana operation in southeast Texas, the trithionate ion (S3062-) was found by infrared spectrometry to be the major resin poison. Treatment of ion exchange feed solutions with hydrogen peroxide only resulted in partial conversion of reduced sulfur species to sulfate, and trithionate conversion was particularly slow. Poisoning of the resin also occurred from the ammonium chloride eluant, which built up trithionate because of recycling. This was essentially eliminated by chlorinating the eluant prior to yellow cake precipitation.

Jan 1, 1984

By K. T. Stafford, N. A. Iverson, V. T. McLemore

Southwestern New Mexico is part of a large belt of Late Cretaceous to Eocene copper porphyry deposits found in Arizona, New Mexico, and Mexico. These deposits are the result of arc magmatism that occurred during the Laramide orogeny. Recently, attention has been brought to other commodities that can be extracted as by- and co-products, many of which are critical minerals. A new compilation of the geochronology of these deposits shows two main pulses of magmatism that produced mineralized deposits and, along with new dates by the author, shines new light on the geologic history of these deposits and the role it plays in critical mineral abundance.

Feb 1, 2024

By David C. Slack

In recent years public concern over the environment has grown enormously. A very aware populace has exerted pressure on its legislators to enact enforcement laws dealing with pollution. Among the different types of pollution, sulfur dioxide in the air is a large and readily identifiable constituent. Air pollution, according to the EPA, costs the U, S. billions annually with SO2 a major portion of this cost. Fossil fuel and oil fired power plants release better than 50% of the SO2 in the country. Thus great attention is being focused on the methods power plants are utilizing to control emissions. With a time schedule of compliance by early 1975, decisions are being made and systems chosen that will have to perform - and perform - and perform. Therefore, a large majority of the power plants are presently considering lime in the planning and operational phases of their stack gas desulfurization programs. The reasons for this are: Lime scrubbing has more development and pilot work completed than most other methods; the removal potentials are relatively high; the stoichiometric ratios are not excessive and, the process has relatively low capital and operating costs. Many pilot plant studies have been completed recently using lime and the first operational full scale lime scrubbing unit is now in the start-up phase at this time at Duquesne Light Company's Phillips Station here in Pittsburgh. Also, because of completed development work, the problem of solid waste disposal will also be tackled at this power station at the same time. There are various methods for the use of lime in scrubbing for S02, but for our purposes I would like to describe the cyclic wet lime process. This method called "Scrubber Addition of Lime" involves contacting the flue gas with a slurry of milk of lime.

Jan 1, 1973

By Roland Arnold, Richard Gradnik, Martin Zeindl

This paper presents the details of the Kramer tunnel project in the Federal State of Bavaria, Germany. This road tunnel, which has been under construction since December 2019, is the key component of the western bypass of the town of GarmischPartenkirchen. Once completed, it will relieve the town’s central district from enormous volumes of traffic. The contractor is the joint venture named ARGE Kramertunnel consisting of BeMo Tunnelling and Subterra. The whole project will be completed and handed over to the project owner, Staatliches Bauamt Weilheim, in 2023. The opening of the entire bypass section including the tunnel to traffic is planned for 2024. The tunnel, with a total length of 3,609 m (2.24 miles) and an estimated cost of EUR 178 million (incl. VAT), is designed as a single-tube, double-lane structure with one traffic lane for each direction of travel. The safety issue that exists for single-tube tunnels is solved by a parallel escape tunnel passable for vehicles. All tunnels and ducts are excavated according to the principles of the New Austrian Tunnelling Method (NATM). In order to reduce the geological risk for the owner, the escape tunnel was supposed to be completed before the design process for the main tunnel ever began. The exploratory tunnel was awarded to a competitor with an separate contract.

Jun 13, 2021

By V. Svalbonas

Presently the U.S. mining industry is very conscious of costs. It is timely, therefore, to review the dominant specifications used in the industry for procuring large size-reduction equipment. These are compared with other specifications and procurement methods, such as ASME and DOD, using the criteria of resulting costs, safety/ quality, and fitness-for-service.

Jan 1, 1987

By R. W. Barbaro, R. V. Ramani, K. V. K. Prasad, P. T. Luckie

Discussion by A. Unal Barbaro et al. (1990) implemented a tedious study aimed at delineating the short-scale spatial variability of sulfur in a coal seam. It is not possible, however, to extend their conclusions to any other coal seam or use their in any other fashion, because the background geology was not presented. Nor were the conclusions accompanied by geological interpretations in the paper. In addition, an unfortunate printing error occurred where the total sulfur (determined by High Temperature Combustion) variogram in Fig.3 was duplicated in Fig. 2 instead of the seam height variogram. A more serious error, however, has been committed in the definition of the variable, seam height. What is defined as seam height by Barbaro et al. (1990) is, in essence, mining height, and is not a regionalized variable that should be studied by geostatistical methods directly. Despite the fact that the variable, seam height, is not defined in the paper explicitly, the following quotation discloses the fallacy: "All roof rock that exceeded 1.8 m (6 ft) from the floor was not taken because the longwall was operated to not mine more than 1.8 in (6 ft) unless the coal seam height exceeded 1.8 m (6 ft)." From this definition, the seam height, and therefore the sampling height, is equal to the actual coal thickness, if the coal thickness is greater than 1.8 m (6 ft). Otherwise, it is equal to the sum of the coal thickness plus the thickness of the roof rock that complements the thickness to 1.8 m (6 ft). In the latter case, the seam height is constant and equal to 1.8 m (6 ft). It is possible to conduct a variogram study on a pool of samples that are realizations of two different variables. But the conclusions derived would not belong to any one of the two variables uniquely and, therefore, do not possess any significance. Geostatistical analysis is irrelevant for the sum of multiple regionalized variables formed by arbitrary selections. In a two-seam setting, for example, the mining height, as defined by the thickness of one seam at one location and the thickness of both seams at another location (due to quality and/or minimum thickness considerations perhaps), should not be used in the calculation of one common variogram. The two seams should be modeled separately. They can then be combined according to the specific purposes of the study. On the other hand, if a constant is added to a regionalized variable (to incorporate dilution perhaps), the variogram of the new variable will not change. Barbaro et al. (1990), surprisingly, does not give any geological interpretation of their results despite the fact that most of them can be explained by the origins of sulfur in a coal seam. The presentation of the results of a geostatistical study with no reference to the geology of the deposit is uninformative. It may also be misleading for the potential users of geostatistics, It is not unusual to find nuggets of pyrite in coal seams. In such cases, pyritic sulfur will probably display a spatial structure for only a very small distance that will appear in the experimental variogram as no spatial correlation. This very well known phenomenon is called the pure nugget effect in geostatistics (Journel and Huijbregts, 1978) and perhaps can explain the lack of correlation found for pyritic sulfur content. The lack of correlation found for the total sulfur content may also be explained in the same way because the total sulfur content is dominated by the pyritic sulfur content in this case study. One should notice, however, that the situation may completely be reversed after cleaning the coal. Not all of the inorganic sulfur should be expected to be in the form of pyrite nuggets in a coal seam. It may also be disseminated in the coal seam and it is expected that it follows a certain spatial structure. However, an existing spatial structure may be masked by including a part of the roof rock, rich in sulfides, into the seam thickness in an arbitrary fashion because areas having a sandstone roof sometimes are known to show a higher sulfur content due to the downward percolation of solutions rich in iron sulfides (Clark, 1979). Plants use sulfur in their growth processes. Much of this sulfur is bound organically during peat accumulation and coal formation (Cecil et al., 1978.) This suggests a spatial structure of some sort for the organic sulfur. However, it is not possible to test this hypothesis because the results obtained by the authors for the organic sulfur content are not given in this paper. For this reason, the conclusion that simple average of the nearby samples would provide the best unbiased estimates is questionable for organic sulfur and is not based on any substantial supporting evidence. It is suspected that no spatial structure was detected and this was due to high sampling and laboratory analysis errors. Before concluding that sulfur variability in the seam at the location of study was random, a more detailed study for the disseminated non-pyritic sulfur should have been conducted, not for the sake of scientific curiosity only, but also due to its utmost importance with regard to coal cleaning and emission control. Pyritic sulfur can be cleaned to a considerable extent, whereas organic sulfur can not, making the emission control strategies highly dependent on the spatial distribution of the organic sulfur (Knudsen, 1981). In the light of these facts, one wonders why Barbaro et al. (1990) did not present the results of their study for the sulfate and organic sulfur content. References Barbaro, R.W.. et al., 1990, "Short-Scale Spatial Variability of Sulfur in a Coal Seam,' Mining Engineering, Vol. 42, No. 11, pp. 1267-1269. Cecil, C.B., et al., 1978, "Geology of Ccontaminants in coal," report prepared for Environmental Protection Agency, North Carolina, 123 pp. Clark, W.J.. 1979, "An interfluve model of the upper Freeport coal Bed in part of western Pennsylvania," unpublished MS thesis, University of South Carolina, 57 pp. Journel, A.G., and [Huijbregls], Ch. J., 1978, Mining Geostatistics, Academic Press, London, 600 pp. Knudsen, H.P., 1981. "Development of a Conditional simulation model of a coal deposit," unpublished PhD dissertation, The University of Arizona, 109 pp.

Jan 1, 1992

By C. D. Wittreich

The University of Idaho, Department of Metallurgical and Mining Engineering, through the Generic Mineral Technology Center, has been engaged in mine design research at the Lucky Friday Mine, Mullan, Idaho. The purpose of the research is to develop and implement the longwall underhand cut-and-fill mining method for conditions at the Mine. The longwall underhand cut-and-fill mining method involves backfilling mined stopes with a compacted tailings-cement mix. After the backfill has been allowed to cure, mining is resumed from underneath. Horizontal stresses in the Lucky Friday Mine are exceptionally high and rock bursts are a common problem. Beus and Chan (1980) have reported a 2:1 horizontal to vertical stress ratio at the mine with a 65-MPa (9,500-psi) maximum horizontal stress at the 1,295-m (4,250-ft) level. Using this mining method under these stress conditions, it is desirable to have a backfill material that has sufficient strength to safely carry the high horizontal wall loads while minimizing external steel supports.

Jan 1, 1987

By Charles E. Dunne

One of the most frequently asked quesitons is: "Where is copper (price and usage) going?" I will not attempt to forecast either the future price of copper or the future growth of the copper industry; rather I would like to discuss the current trends experienced in the smelting and refining terms and conditions for sales and/or purchases of copper concentrates. A brief review of contract language and terms, together with a review of the common jargon, I believe, would be helpful. To accomplish this review, I will first list what I consider the four basic parts or sections of a basic ore contract and then illustrate basic terms with calculations.

Jan 1, 1984

By A. Nieto

Rare earth elements (REEs) are crucial to green technology such as hybrid-electric vehicles, wind turbines and fluorescent light bulbs. As of 2011, China dominates the global production of REEs and is reducing its export quotas. To predict the supply of rare earths in the United States based on future supply scenarios, a web-based database and geographic visualization tool was built. Five case scenarios with varying levels of REE demand were created by varying several economic conditions including (1) international trade policy, (2) greenhouse gas regulations, (3) environmental mining regulations and (4) tech applicability ratio of REEs. The most likely scenario, which is based on current international demand levels, indicates the importance of expediting the development of extractive operations of current REE resources within the United States. The results of the different case scenarios are supported by using dynamic geographic maps indicating the location of rare earth ore (REO) resources.

Jan 1, 2012

By Leonard B. Rothfeld

For many years, pulverized coal (PC) boilers in utility power plants have been the dominant market for domestic coal. Today, two new coal utilization technologies challenge the PC boiler's dominance. Atmospheric fluidized bed combustion (AFBC) and "coal gasification/combined cycle" (GCC) stand on the verge of commercial demonstration in the utility environment at a scale of 100 MW. Developed over the past decade, these technologies respond to the demands for cleaner ways to burn coal and for more flexibility in fuel supply. In the near term, these are the "clean coal" technologies most likely to have a significant impact, because they are ready for commercial application. As for environmental acceptability, consider that just a few years ago one of the environmental slogans was "no coal in California." Indeed, the only large quantities of coal above ground in California at that time were in transit on the way to Asia. Today, thanks to new technology, we can point to two operational coal-burning plants in California and one in the works: * Cool Water GCC demonstration plant (100 MW) * California Portland Cement AFBC commercial cogeneration, near Riverside (190 000 lb/hr steam) * Energy Factors AFBC commercial cogeneration at Stockton, to be operational 1988 (44 MW)

Jan 1, 1987

By Pierre J. Goossens

Since Guild 1 and Snelgrove 2 attracted our attention to the relationships between certain endogenic ore deposits and plate boundaries, an abundant flow of papers appeared in the metallogenic literature concerned with this problem and its application to mineral exploration. Some of the papers only speculate with the formation of specific type of ore deposit 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 Other papers are more concerned with genetic and structural relationships between plate tectonics and mineralization 13, 14, 15, 16, 17, 18, 19, 20 They are philosophical, in that they are generalized and refer to no specific area. Yet it is true that a large part of the world mineral potential is concentrated at the convergence of oceanic and continental plates, for example, around the Pacific. Therefore, the interaction of two plates by either subduction, obduction or slippage likely has an important role for the genesis and/or the (structural) control of these "orogenic" ore deposits. If subduction is the driving mechanism for the generation of igneous rocks 21, 22 and endogenic ore deposits 18, volcanic activity and the nature of volcanic products certainly are the major geologic processes and events to be tested. Fonteilles 23 and Alsac 24 have already emphasized the important relationship between mineralization and the talc-alkaline affinity of the volcanics. The Andean orogen is one of the best areas for testing such genetic relationships. Rich and varied endogenic and volcanogenic ore deposits occur there and plate interaction is still active.

Jan 1, 1975

By Kendall Y. Onstott

The paper presents the results of a plant test using WEMCO 1 + 1 enclosed flotation machines for inert gas (nitrogen) flotation of by-product molybdenite from copper sulfide concentrate. Copper depressant consumption in the rougher flotation stage was reduced by 68% as reagent consuming oxygen was removed from the flotation air. Unlike other nitrogen flotation systems used in the industry, nitrogen is recovered above the flotation cells and from froth in tails and concentrate streams and recycled, resulting in minimal nitrogen makeup requirement.

Jan 1, 1984

By Jamal Rostami, Jürgen Schmitt, Rohola Hasanpour

"Double Shield TBMs can be used in fast track projects for accelerated completion where there is limited information available on ground conditions and there are possibilities of encountering weak ground and shear zones. As such, the shielded TBMs are the primary choice of the machines in long tunnels, but face the possibility of entrapment in squeezing ground, which entails long delays and major risks. This paper examines the possibility of using ground improvement methods to increase ground strength, and thus, increase the capability of the machines to cope with squeezing ground conditions. In this study, 3D finite difference simulation of a shielded TBM in squeezing ground was performed to estimate the operational parameters including required thrust to get a machine out of an entrapment. This analysis was also used to evaluate the possibility of preventing machine jamming by the implementation of pre-excavation ground improvement to increase the strength of the ground. INTRODUCTION In order to face adverse tunneling conditions especially using a shielded TBM in squeezing ground, new shield designs, with extra thrust and torque, step shield geometry with reduced shield diameter from front to the back, and conical shape shields have been used. In addition, many of the new machines have the capability to implement ground improvement at distances up to 50 m ahead of the face in order to reinforce the ground and further increase in their chances to cope with squeezing ground conditions. While these features have been added to the machine, there has not been a thorough evaluation of their impact on improving the chances to avoid machine jamming in weak rocks at high depth, which is conducive to rapid convergence of the ground."

Jan 1, 2016

By C. Newman, N. Schaefer

"INTRODUCTION As underground mining continues to operate at deeper depths and in more complex geologic and geometric conditions, there has been an increased demand for higher design standards in ground control safety and stability within the mining industry. Over the past 20 years, NIOSH has developed, validated, and distributed a number of free software packages (ALPS, ARMPS, AMSS, ARBS, etc.) for the safe design of underground coal mines with respect to ground control. While these programs were initially developed on a, “stand alone model,” where all program data resides on an individual or workgroup computer, modern day web applications have begun to migrate toward a, “multiple-tier model,” allowing multiple users to access an application through an Internet connection. webGroundControl provides users with access to NIOSH ground control design software (ARBS, ALPS, and ARMPS) utilizing a web-based three-tier architecture allowing users to easily access ground control designs, perform on-demand calculations, and provide online collaboration between operational personnel and engineers through a web server. Given advancements in cloud computing as well as the expansion of Internet connectivity on the surface and underground, webGroundControl users will be able to access the applications anywhere (where permissible) at any time. As web-based computing technologies continue to advance and cloud computing gains popularity and momentum, there is an industry need to develop Internet based applications for mine and ground control design (Barczak et al., 2016). The purpose of this paper is to introduce and familiarize those in the mining industry with the basic framework and, more specifically, the user-interface of the webGroundControl application. It is expected that the mining industry will rapidly embrace this new product and webGroundControl will be a new paradigm for mining engineering computer applications. APPLICATION ARCHITECTURE With the advent of cloud computing, web-based applications have become more popular with their adoption of multiple-tier, or n-tier, architecture containing independently operating tiers. The three-tier application architecture utilized in webGroundControl (as outlined in Agioutantis and Newman, 2016) contains a Presentation Tier (Web Server), Logic Tier (Logic/Application Server), and Data Tier (Data Server) as shown in Figure 1. While tiers have the ability to be deployed across and operating on multiple servers, webGroundControl is currently being deployed on a single server located on a university desktop computer. The separation of the application into a series of tiers greatly increases the maintainability and scalability allowing for the adoption of new technologies that can be applied to a single tier without redesigning the software package. The Presentation Tier maintains the user interface translating client requests (through a web server) and displaying results (through a web browser). The Presentation Tier allows for on-demand access from multiple users and compatibility with a variety of personal computers, Smartphones, tablets, etc. on different operating systems. The Presentation Tier has been developed with respect to the HTML and JavaScript languages. Through the utilization of CSS, a coding language which describes the style of an HTML document, the webGroundControl display is able to spontaneously adapt to any browser and any screen. The development of the Presentation Tier will be discussed in more detail in subsequent sections of this paper."

Jan 1, 2017

By Henry F. McCabe

The principals of McCabe Industrial Minerals, Inc., have been involved in the mining, processing, and marketing of nonmetallic minerals for more than 40 years. In addition to marketing nonmetallic minerals produced by other companies, McCabe Minerals owns and operates three plants that produce headlap-roofing granules, with 25 employees and annual sales approaching $6 million. During its 22 years of operation, the company has developed many different markets, and a list of factors that is used in making our marketing and feasibility studies. These criteria (Table 1) are used extensively by the company in all of its projects, and we present this and other data about the company in this brief report. HISTORY OF THE COMPANY A brief outline of the history of McCabe Industrial Minerals follows: I. McCabe Industrial Minerals, Inc. (Formerly McCabe-Woody & Co.). A. Founders: 1. Henry F. McCabe (experience): a. Heart of Texas Sand Co., Brady, Texas (1959-67) b. Delta Mining, Mill Creek, Oklahoma (1967-76) 2. A. H. Woody (experience): a. Heart of Texas Sand Co., Brady, Texas (1961-65) b. Featherlite Corp.-Light-weight aggregate

Jan 1, 1999