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By T. C. Pool

Physical and chemical conditions permitting, in-situ leaching (ISL) of uranium offers a variety of advantages over conventional production methods including less surface disturbance and less solid waste. Commercial production of uranium by in-situ leaching techniques was initiated in 1963 in the Shirley Basin of Wyoming by Utah Construction. On a world-wide basis, ISL uranium production amounted to about 13.2 million pounds U3O8 in1999, approximately 16% of world output. Both acid and alkaline systems are used, the selection of which is primarily dependent upon groundwater quality and related reclamation requirements. ISL offers low capital costs per unit of annual capacity and is particularly flexible in adapting to changing market conditions.

Jan 1, 2000

By Douglas F. Stevenson

Your committee doesn't assign any easy topics to us speakers. How do you define "successful" in what is essentially a losing game? I am reminded of the fellow who returned from a one-week vacation in Las Vegas, and proudly stated, "I only lost $150." To him, that was "success." I am afraid that workers' compensation is a losing game for employers, too, and success has to be defined in terms of how much or how little is lost. We have no chance of producing a profit for our employer. We will narrow down to some suggestions about conducting a workers' compensation program at the plant level, but first I want to discuss the general legal, social and legislative climate in which your plant program operates. Workers' compensation is a statutory program with its general parameters established by the legislature. These parameters are then amplified by the boards and commissions established to administer workers' compensation. What influences the legislature and the boards and commissions as they establish the framework in which we must function?

Jan 1, 1986

By D. Bernabe

The mine scheduling process defines a mining sequence across the life of the mine and stipulates the amount of ore, waste, and specific blocks to be mined each year so that the highest economic return can be obtained under a number of constraints. There are a number of mine scheduling software packages available. Each claims to be the best scheduler by maximizing Net Present Value (NPV) or by minimizing overall mining costs. These mine scheduling programs follow different procedures and scheduling philosophies based on either mathematical or heuristic principles. There was no study in which the mine production scheduling procedures applied by these packages were discussed and compared. This paper evaluates four open pit mine scheduling programs recently developed and compares them in order to determine if significant differences exist among them. The same input data, which consist of a 3-D block model, an economic set of parameters, and the initial surface topography for a operating copper mine in Southern Peru, was used to test each technique. The following programs were investigated with respect to their ability to optimize the NPV for the case study. 1) M821V1 Scheduler by Mintec; 2) NPV Scheduler by Earthworks; 3) Milawa Scheduler by Whittle Programming; and, 4) Fundamental Tree Scheduling Method (FTSM) developed at the Colorado School of Mines. The results from this case study demonstrate that the scheduling software packages, Mintec, Earthworks, and Whittle obtained similar NPV’s, while FTSM scheduler gave a six percent higher NPV than the other schedulers.

Jan 1, 2002

By Richard A. Thomas, Connor B. Brown, Thomas H. Dubaniewicz, Teresa Barone

Electric vehicles powered by lithium-ion (Li-ion) batteries are being developed by mining vehicle manufacturers as a replacement for diesel-powered vehicles. Explosion-proof (XP) enclosures are frequently employed to enclose electrical ignition sources in gaseous underground mines to prevent the spread of an internal methane-air explosion to a nearby explosive atmosphere. Due to thermal runaway (TR), Li-ion batteries have the potential to cause pressurized explosions in an enclosed structure. Past research has shown the potential for well-confined Li-ion cell TR to drive pressures beyond the conventional pressure specification for XP enclosures. Researchers at the National Institute for Occupational Safety and Health (NIOSH) used an Accelerating Rate Calorimeter (ARC) to induce thermal runaway of Lithium Titanate or Lithium Titanium Oxide (LTO) type 18650 cells enclosed within containers with various volumes and found an inverse power relationship between the TR pressure and available free space. The results were similar in magnitude to that of lithium iron phosphate (LFP) cells, which were used in prior testing. Temperatures, gas amounts, and TR pressure-rise rates were also recorded. The data indicate that with enough free space, the pressures can be lowered below the conventional pressure specification for XP enclosures.

Feb 1, 2024

By Güldane Atesoglu, İsmail Atilgan

The changes in the elemental contents and the structural properties of chalcopyrite concentrate when roasted were studied, and the main reactions contributing to the leaching process revisited. Firstly, TG/DTA measurements were performed to identify the roasting temperatures that influenced the type of species reacting with sulphuric acid leaching liquor. The temperatures of main reactions, whose output may affect the subsequent leaching process, were analysed for the concentrate at hand, and concluded to be generally lower than those reported in literature. Secondly, the obtained results were confirmed by images and XRD measurements on the roasted concentrate at temperatures in between 350 and 600 °C with increments of 50 °C. Finally, the leaching behaviour of the roasted specimens in a stirred sulphuric acid solution examined and the Cu/ Fe selectivity investigated that the maximum Cu/Fe ratio in the pregnant solution would nearly be achieved for the roasting temperatures lower than 500 °C, since the oxidation temperature of iron sulphate is found lower than that of copper sulphate.

Aug 11, 2022

By R. P. Killmeyer, W. W. Wen, B. K. Parekh

A continuous pilot-scale test of the GranuFlow Process was conducted using a screen-bowl centrifuge for the dewatering and reconstitution of column -flotation concentrate at a coal preparation plant in Virginia. In this test, a slipstream of the fine clean-coal slurry from the column flotation con¬centrate was treated with a bitumen emulsion before dewatering. The treated products from the screen-bowl centrifuge appeared to be dry and in a free flowing granularform, while the untreated products were wet, sticky and difficult to handle. Test results indicated that the average moisture contents of the dewatered coal products were 35.7%, 35.5%, 32.6%, 29.9% and 26.5% (by weight) with Orimulsion additions of 0.0%, 0.7%, 3.2%, 4.8% and 6.4% (by weight), respectively. The handleability and dust reduction of the dewatered coal products were also vastly improved.

Jan 1, 2000

By Bruce Clements

The Bagdad mill, located near Bagdad, AZ, was built in 1977 with a designed mill capacity of 36.3 kt/d (40,000 stpd). An autogenous mill-ball mill crusher (ABC) grinding circuit was chosen. The original mill contained three independent grinding circuits. Each contained one 9.75m-diam x 4-m-long (32-ft-diam x 13-ft-long) fixed-speed autogenous mill, a4.7-m-diam x 6.7-m- long (15.5ft-diam x 22-ft-long) ball mill and one 2. 1-m-diam (7-ft-diam) short head cone crusher. Total installed power per grinding circuit was about 8.4 MW (11,350 hp), with 5.9 MW (8000 hp) in the autogenous mill, 2.2 MW (3000 hp) in the ball mill and 261 kW (350 hp) in the crusher (Fig. 1). The autogenous mills were designed to be able to operate semi-autogenously. However, they were never converted to semiautogenous grinding (SAG) mills. As a result of this design, only about 4.1 MW (5450 hp) of the designed power is used in the autogenous mills. The grinding circuits are closed, with 2.4 x 6 m (8 x 20 ft) double-deck vibrating screens. A series of conveyors re- turn screen oversize underneath the mill coarse ore stockpile to feed the crushers. Variable speed belts feed the crushers and control power draw. Crusher product reports directly to the tail end of the autogenous mill feed belt (Fig. 2). A magnetic sensor detects tramp iron in the autogenous mill-crusher circuit.

Jan 1, 1992

By T. Lilley

The use of membranes in wastewater systems has increased rapidly in recent years. Microporous or semi-permeable barriers augment conventional chemical or biological processes to meet stringent treatment targets. These developments enable elegant solutions to wastewater discharge challenges and extend the scope of water recycle redressing the overall water balance and operational economics Wastewater treatment processes are discussed by reference to the spectrum of waterborne contaminants and the respective membrane separation capabilities. The role chemical pre-treatment to enable physical separation of metals with micro-filtration (MF) is described and how integration of MF with reverse osmosis (RO) is used to control a broader range of dissolved contaminants Membrane configurations are considered apropos function, operational economics and sustainability. These features are exemplified with case studies. Firstly, MF alone following chemical precipitation for the removal of heavy metals, then MF onto two stages RO of different configurations for TDS reduction and waste volume minimisation and finally an open channel RO alone for the reduction of inorganic COD from a leach stream.

Feb 27, 2013

By Jürgen Kretschmann

Principally, mining natural resources is a finite business that reaches its limits once the deposits mined are depleted, the resources can no longer be mined in an economically profitable way or substitutes are pushing the mined products out of the market. An example of the latter is the increasing replacement of coal with natural gas and renewables in power generation in the United States [1]. According to the model of the product lifecycle, the global hard-coal mining industry has reached a stagnation phase [2]. The trend is obvious. Coal use peaked in 2013 [3], and the coal demand of China has been slowly decreasing since then [4]. Coal consumption in the United States saw a 16 percent decline from 726 Mt (800 million st) to 608 Mt (670 million st) between 2015 and 2019. In addition, according to the U.S. Energy Information Administration, it will not rise again [5]. The decline is attributed to complex market dynamics, from low gas prices because of the “shale gas revolution” [6] to federal environmental regulations like the Clean Power Plan. Moreover, important players like the United Nations and the European Union have already begun to describe pathways toward decarbonization. Increasing competition between coal-mining companies and the mining regions can be expected worldwide if companies want to keep their positions on the global and national coal markets. Companies will focus on the best deposits. European countries, like France, Spain or Germany, are only forerunners of this development — their centuries of coal production have passed. The concept of sustainable development (SD) is fundamentally based on a model of progress in which ecological, economic and social dimensions should be developed equally and positively. Questions arise, such as: How can SD be a corporate goal in a phase of decline? How can former mining regions sustainably progress to a better future? The steps Germany has taken to handle the coal decline in a sustainable way and the lessons learned from this process are described in this paper. 

By Antoni Kalukiewicz

From 1997 through 2000, a team of Polish experts headed by the author studied the prospects of mining newly discovered emerald deposits in Afghanistan. This article describes the scheme for mechanization of the mining operations, along with improvements made to the ventilation facilities and lighting. The required equipment was flown to Afghanistan and the Afghan miners were trained in machine operation and maintenance.

Jan 1, 2005

By S. S. Klima, J. A. Organiscak

Researchers at the National Institute for Occupational Safety and Health (NIOSH) performed laboratory testing to examine and improve airborne dust capture and methane removal performance of flooded-bed scrubbers on continuous mining machines using a blowing face ventilation configuration to reduce respirable dust exposure to shuttle car operators. Several testing conditions were examined to minimize shuttle car operator dust exposure without adversely affecting continuous miner performance and production. Curtain-to-face setback distance of 9.1 m versus 15.2 m (30 ft versus 50 ft), face ventilation airflow of 226.5 m3/min versus 339.8 m3/min (8,000 ft3/min versus 12,000 ft3/min), and the use of side-body-mounted blocking sprays (on versus off) were the three primary parameters compared. Scrubber airflow was set and maintained at 198.2 m3/min (7,000 ft3/min) throughout testing. An examination of slab cuts versus box cuts and the location of the shuttle car (present behind the continuous miner versus not present in the entry) was also performed to demonstrate the effects of these constantly changing scenarios on scrubber performance. Results show that the best blowing face ventilation setup for minimizing shuttle car operator dust exposure for the tested parameters uses a 15.2-m (50-ft) curtain-to-face setback with 339.8 m3/min (12,000 ft3/min) face ventilation while operating the side-body-mounted blocking sprays. INTRODUCTION Coal mine worker overexposure to respirable coal dust continues to be a problem in U.S. underground coal mining operations, potentially leading to coal workers’ pneumoconiosis (black lung). The U.S. Mine Safety and Health Administration (MSHA) requires that respirable dust exposure to coal mine workers does not exceed a 1.5 mg/m3 average over the actual working shift (79 Fed. Reg. 24814 (2014)). Although using a blowing face ventilation configuration on continuous miner (CM) sections is beneficial for removing methane emissions from the mining face, it can be detrimental for dust control for shuttle car (or ram car) operators and any other workers on the return ventilation side of the CM when compared to exhausting ventilation. Even with machine-mounted scrubbers on CMs, shuttle car operators still have some of the higher dust exposures with blowing face ventilation systems (NIOSH 2011, Beck et al. 2015). Although scrubber discharge air is not completely clean, dust being blown around the scrubber inlet and therefore not being captured by the scrubber can further increase these dust exposures (Goodman 2000). Dust control problems are also caused by inadequate face ventilation quantities causing scrubber face airflow recirculation issues (Schultz et al. 2010). In order to minimize respirable dust exposures on blowing face ventilation sections, ventilation, water spray, and scrubber parameters were experimentally examined to improve operating ranges for both dust and gas control. Several blowing face ventilation factors were examined with respect to CM spray systems and scrubber operation. Curtain-to-face setback distance and side-body-mounted blocking sprays were previously examined in the laboratory for dust control on a full-scale CM model using a scrubber on a blowing face ventilation system (Goodman 2000). The blocking sprays produced larger dust reductions at the CM’s rear corners and return for a 6.1-m (20-ft) curtain setback distance as compared to a 12.2-m (40-ft) curtain setback distance with equal face and scrubber airflows of 169.9 m3/min (6,000 ft3/min). Because face ventilation airflow quantities, shuttle car operator locations, and tracer gas concentration gradients were not previously examined during these experiments, additional research was required to determine improved operating parameters for blowing face ventilation systems.

Jan 1, 2019

By Steven B. Van Kouteren

Value added is a loosely used qualifier in the industrial minerals industry. What exactly does it mean? What does it take to make a value-added product? More importantly, how does a company maintain the value added to its products? Most people agree that value-added means the value of a mineral minus the cost to produce it. This is misleading, though, because producing value-added products does not necessarily guarantee the profitability of the products. In some cases, firms that make value-added products are not very profitable. It is important not only to understand how to make a value-added product but also how competitive forces in the market can erode the value added. Therefore, when looking at value-added opportunities, producers must understand how to obtain the value added and how to maintain that value. Four major factors limit a company's ability to add value to its products. This paper examines these factors. It uses the ground calcium carbonate and mica industries as examples.

Jan 1, 1990

By Ezz El Din Abdel Hakim Khalaf, Khalid S. Essa, Marc Munschy, Mohamed A. S. Youssef

This study focused on joint interpretation of the aeromagnetic and radiometric data to allocate and describe the structural elements and mineralization zones such as uranium, gold, and sulfide in the Gebel Umm Tineidba and its surroundings, Eastern Desert, Egypt. The study region is covered by exposures of Precambrian rocks such as gneisses, migmatites, ophiolitic mélange, metavolcanics, younger granites, and Quaternary sedimentary covers. The application of the total intensity magnetic and reduced-to-pole maps, power spectrum, analytic signal, tilt-angle, and local wavenumber maps helps in recognizing magnetic sources distribution, lineament features, and mineral zones delineation. The obtained results indicate that the depths of the deeper NE–SW, NNE–SSW, and N–S trending structures extend from 400 to 1750 m and shallower ones range from 100 to 400 m. Finally, the main trends of these structures affect the probable mineralization zones.

Sep 22, 2022

By Jon Y. Kaneshiro, Sean A. Menge, M. Luis Piek, Brian Barker

The Lake Hodges to Olivenhain Pipeline project is part of a 40-megawatt pumped storage project linking two reservoirs as part of the San Diego County Water Authority’s $939 million Emergency Storage Project. Seeking to expedite project completion, the project was advertised as Design-Build, a first for the owner. Awarded to Kiewit Pacific with Parsons as designer, the 1,750m (5,700ft) long, 4.25-m (14 ft) horseshoe tunnel was excavated with conventional drill-and-shoot technique. The mining method was well suited to deal with the shear zones, the very abrasive rock, and 13.3% and19.6% grades. At the apex of the alignment, a 60m (200ft) by 3.6m (12ft) diameter raisebore shaft with surge chamber to protect against pump malfunction was constructed. Upon completion of mining, the tunnel was lined with a 3m (10 ft) diameter high strength steel pipe. Scheduled to come on-line by January 1, 2008, the Lake Hodges to Olivenhain pumped storage project is valued at $108 million, delivering a reliable source of water in emergency situations and electricity-generating capability to meet the growing demands of the San Diego region.

Jan 1, 2007

The only significant iron ore deposit in Hungary could be found in Rudabánya. The mine was closed in 1986. The area of Rudabánya was always the home of heavy mining activity. In former times, mainly silver and other non -ferrous metals were excavated.

Jan 1, 2011

By Michael L. Ogilvie

The proportion of underground coal production as a percentage of overall Australian production has fallen in the last 10 years, with underground production remaining more or less static at about 53 Mt (58 million st). However, underground coal mining remains a viable industry in Australia, due to use of modern longwall mining systems. In 1993-1994, 26 longwalls were in operation, with total production exceeding 39 Mt/a (43 million stpy). Some of these longwalls achieve productivity levels approaching efficient opencut operations, and in some cases, they exceed them. These high-production longwall mines are not without problems when depth and distances from outcrop increase and the gas content of the seams approaches or exceeds critical limits. When gas content of a coal seam exceeds 6 m3/t (233 cu ft/st), gas flows into the mine may be sufficient to interrupt production from time to time.

Jan 1, 1995

By Alok Garg, Rajeev Kumar Dayal

The Himalayan ranges have complex geological formation induced with locked up tectonic stresses and squeezing ground conditions. High overburden, steep slopes, perennial snow, and forest cover restricts accurate prediction of geological features, resulting in surprises during excavation. The tunnel planning under high altitude, extreme climatic, and unfavorable approachability conditions requires elaborate detailing. The construction technique and working faces for excavation are influenced by site accessibility/high overburden conditions, restricting the provision of access tunnel or shaft. The paper discusses site constraints influencing construction method and working faces for 8.9 km long highway tunnel at elevation 3,000 m under 1,900 mover burden through quartz-mica-schist formation.

Jan 1, 2001

By Ralph H. Light

The recent surge in demand for uranium in the United States, accompanied by a significant increase in price, has resulted in exploration, mining, and milling of lower grade ores than have been exploited in the past. To sustain production levels of uranium with lower grades of feed requires larger tonnage mill operations. Also, because of recent environmental regulations, mill operations must be prepared to properly contain large tonnages of tailings, and recycle, treat and discharge, or evaporate mill effluents. Thus, the advent of lower grade ores, larger tonnage mills, and environmental considerations has made the cost of milling a critical factor in today's uranium production economics in the United States. Three basic milling methods are employed for extracting uranium from ores: 1. Acid leach, countercurrent decantation, and solvent extraction. 2. Acid leach, resin-in-pulp, and Eluex. 3. Alkaline leach, solid-liquor separation, and precipitation. Vanadium often occurs as a valuable by-product in ore deposits located in the Uravan mineral belt in Western Colorado. Also, lesser amounts of vanadium may occur in ores from South Dakota, New Mexico, and Utah. Vanadium is usually extracted in the acid leach solution with uranium and recovered by solvent extraction after recovery of the uranium. By-product recovery of uranium from phosphoric acid and porphyry copper dump leach solutions is now receiving considerable attention. Pilot plant studies are under way and construction of commercial plants is in progress.

Jan 1, 1977

In February 2001, Kalgoorlie Consolidated Gold Mines (KCGM) commissioned its first full-scale ultra fine grinding (UFG) plant to supplement existing roaster concentrate treatment capacity. This process involves the fine grinding of refractory pyritic concentrate to 10µm, followed by direct cyanide leaching for the recovery of gold. By this means gold is economically extracted from the concentrate without the need to first oxidise the host pyrite. This paper details the history of the project from initial laboratory testwork comparing possible treatment options, to current performance of the 12 tph plant. This includes the cost comparison of the major treatment options, the laboratory and pilot scale UFG performance, the UFG mill selection, cyanide leaching of UFG product, commissioning and plant performance to date.

Jan 1, 2002

By Abb Raymond

Finely processed industrial minerals in "powdered" form have long been utilized by the plastics, paint, rubber, paper, ceramics, and adhesives industries as fillers, extenders, coatings and special additives. These minerals, primarily calcium carbonate, talc, kaolin, titanium dioxide, and the like, have provided economic, uniform and consistent base materials which have, in turn, been used by the referenced industries to manufacture quality products. The focus of this paper will be the development of equipment and systems at ABB Raymond for the dry processing of such non-metallic minerals in order to meet what have become increasingly stringent requirements of the producers of these minerals. Changes in these requirements seem to have been accelerating rapidly during the last ten years, and it is expected this process will continue into the 1990's.

Jan 1, 1990