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By A. E. Torma

The efficiency of Thiobacillus ferrooxidans in the desulfurization of a high-sulfur content New Mexico coal was demonstrated. The optimum condition of process variables were found to be pH = 2.3, particle size = 38 µm, pulp density 14.1% (W/V) and temperature 33.9°C. Larger scale experiments carried out with these optimum conditions resulted in coal desulfurizations above 97%, while in sterile controls this was only about 10%.- The rate of desulfurization was described with an exponential expression with respect to the effects of coal particle size. The effect of pulp density on coal desulfurization was quantified by a Monod type equation. The apparent activation and deactivation energies, the frequency factor and temperature coefficient were derived from the effects of temperature to be ?aE - 11720 cal mol-1 and A = 30.44 mol dm-3s-lin the range of 20 - 35°C; ?Ed = 43930 cal mol-1 and A = 9.82 x 10-39 mol dm-3s-1 in the range of 35 - 45°C; and Q10 = 1.94 in the range of 20 - 30°C. The thermodynamic values [(?G+, ?H+ and ?S+)] of the activated complex were calculated. The generalized second order regression equation relating the degree of biodesulfurization of coal to the leach parameters was shown to adequately predict coal desulfurization within the range of process variables studied.

Jan 1, 1987

By Peter G. Dunn

Geologic studies during development at Copper Flat were directed at acquiring the information necessary in evaluating a low-grade porphyry copper deposit. In addition to the geologic mapping and core-logging of a typical exploration project, these studies included the following : (1) careful checks on the sampling and assaying (2) selection of representative samples used to establish the recoverable amounts of precious metals in the ore (3) examination of underground workings driven to provide samples both for metallurgical testing and for assay comparisons (4) evaluation of plant site and waste dump areas as non-mineral, including a placer examination of the taillngs disposal area (5) location of an adequate water supply. All these investigations were carefully documented to provide the necessary data both for the engineering design and, more importantly, for the feasibility studies required for successfully financing the project.

Jan 1, 1981

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 Sufi Md Gulzar, L B. Roy

Rock engineering tasks like tunnelling, dam and building construction, and rock slope stability rely heavily on properly estimating the rock’s uniaxial compressive strength (UCS), a crucial rock geomechanical characteristic. As high-quality specimen are not always possible, scientists often estimate UCS indirectly. The primary objective of this paper is to assess the efficacy of long short-term memory (LSTM), K-nearest neighbour (KNN), a combination of particle swarm optimisation (PSO) with an artificial neural network (ANN), and adaptive neuro-fuzzy inference system (ANFIS) to estimate the UCS of sandstones from Jharia, Dhanbad, India. Point load index (PLI), porosity (n), P-wave velocity (Vp), density (ρ), and moisture content (%) are the parameters used for the present study. Finally, a comparison was made between the various prediction algorithms outputs. The findings of the study validated the effectiveness of computational intelligence methods in forecasting UCS compared to other models used in this paper. The KNN achieves overall the best results, with an R2 of 0.95 for training, 0.94 for testing, and an RMSE of 0.03 for training and 0.05 for testing.

Nov 23, 2023

By H. Huang, R. N. Gow

"EH-pH diagrams are useful tools in understanding how mineral surfaces react in solution and particularly how aqueous conditions can be changed to enhance mineral leaching processes. Successful application of these diagrams, however, requires that several considerations be kept in mind to prevent what had been termed as “gross errors” in their calculation and use. In this paper, the aqueous Cu-S system is used as the basis for explaining the mass-balanced method of calculating EH-pH diagrams with the STABCAL thermodynamic equilibrium software. A breakdown of the Gibbs’ Phase Rule and how it is used in STABCAL to modify the diagrams is included. The methodology was applied to the aqueous Cu-As-S system, and resulting diagrams were compared against examples of those generated using the predominant-ion method. The complexity of such diagrams increases with every additional component, and competition between species becomes more apparent, as can be seen by curvature in the resulting mass-balanced diagrams. The complete diagram for enargite (Cu3AsS4) is shown. It compares well with spectroelectrochemical measurements from Raman spectroscopy and cyclic voltammetry studies.IntroductionInnovation in the field of processing arsenicbearing copper ores has been of particular interest. Copper arsenic sulfosalt minerals such as enargite (Cu3AsS4) and tennanite (Cu12As4S13) are now frequently prevalent in ore bodies as the oxide and easily leachable sulfides become harder to find. These minerals, unless pretreated somehow, concentrate in copper sulfide flotation processes, in turn concentrating the arsenic levels. Increasing environmental restrictions on arsenic content for smelters makes the hydrometallurgical processing of these concentrates more favorable. While enargite is considered one of the more refractory copper sulfides, more so than chalcopyrite (CuFeS2), there are still several methods, both industrially proven and in development, that are capable of processing these ore types. Alkaline sulfide leaching can be used as a pretreatment method to solubilize arsenic selectively (Delfini et al., 2003; Anderson and Twidwell, 2008; Tongamp, Takasaki and Shibayama, 2010a, 2010b), or the entire metal content can be leached using acid-type leaches such as acidified ferric sulfate (Dutrizac, 1981; Hackl et al., 1995; Klauber, 2008), or the chloride assisted, CESL (McDonald and Muir, 2007) or nitrogen species catalyzed (Anderson, 2003) processes can be used.As development of these leaching technologies proceed, it is also important to develop an understanding of the mineral thermodynamics. To date, there are numerous studies on the Cu-Fe-S-H2O system, particularly as it relates to chalcopyrite leaching, yet few studies have done on the Cu-As-S-H2O system. Computer-generated EH-pH diagrams have been employed to illustrate the importance of thermodynamic calculations in providing insight into such a system."

Jan 1, 2016

By Frederick McNeill, John Harper, Mahmood Khwaja, Shawn Lavoie, Timothy Cloughert, David Polcari

City of Manchester, NH, is implementing a 20-year plan to control and significantly reduce overflow of its sewer system. The long-term control plan had called for large scale box culvert installation through downtown Manchester. The City and the project team evaluated, and eventually selected, tunneling as an alternative to mitigate construction related impacts for open trench approach. This paper provides an overview of the alternative evaluation process; discusses the development of the preliminary design for the 12,000 feet long, 12-ft internal diameter tunnel, including plan and profile selection, subsurface conditions, drop shafts and the anticipated packaging of the separation areas.

Dec 1, 2022

By Earl M. Woodward

INTRODUCTION Kerckhoff-2 is a 140 MW underground hydro-electric project designed and owned by Pacific Gas and Electric Company and constructed between May, 1980 and May, 1983 by Auburn Constructors. The project is located in the western foothills of the Central Sierra Nevada Mountains, about 30 miles northeast of Fresno, California, and develops the power potential of the lower San Joaquin River and its tributaries between the existing Kerckhoff and Millerton Lakes. The Kerckhoff-2 Project consists of project roads, adits, and access tunnels, service tunnels, power tunnels, powerhouse, tailrace tunnel surge shaft, buss shaft, intake structure, discharge structure, and switchyard. In the 1920s, the Kerckhoff 1 project, consisting of a dam, reservior, tunnel, and 34 MW powerhouse, was built in the same general area as Kerckhoff-2. The tunnel was constructed by conventional methods, and was left unlined. In time, other projects were built upstream, allowing the flow of the San Joaquin River to be regulated. The Kerckhoff 2 project is designed to harness that regulated flow, providing an additional 140,000 ON of power. Kerckhoff 2 will be the primary power plant; Kerckhoff I will produce power whenever the flow rate exceeds 4,800 cubic feet. The new power tunnel is built along the east side of the San Joaquin River between Kerckhoff and Millerton Lakes, parallel to the existing tunnel but extending approximately one mile further downstream.

Jan 1, 1983

By M. Schlegel, J. A. Villa Mena, R. E. Vivas

ArcelorMittal, headquartered in Luxembourg, is one of the world’s largest steel and mining companies. It supplies steel to industries such as automotive, construction and energy, with a strong emphasis on sustainability and innovation. The company employs about 125,000 people, and in 2024 produced 38.5 Mt (42.4 million st) of iron ore and 52.5 Mt (57.9 million st) of crude steel across 15 countries. Its mining operations span Canada, the United States, Mexico, Brazil, Ukraine, Bosnia and Herzegovina, Kazakhstan and Liberia, focusing on iron ore and coal extraction to support steel production.

Apr 1, 2026

By D. McElhinney, K. Mohamed, T. Batchler, T. Matthews

Steel props are a type of standing support utilized in coal mines to support mine roof. In addition to the vertical roof loading, sometimes the steel props are subjected to lateral loading of spalled ribs. To enhance the safety of mine workers, the performance characteristics of the steel prop was studied under different scenarios of vertical and lateral loadings. Quik Stik props were used for use in this study. A uniaxial compression loading test was conducted for the Quik Stik prop assembly (inner and outer tubes, ball bearings, collar) to investigate the loading mechanism of the prop. Rupture tests were conducted for the inner and outer steel tubes of the Quik Stik props to estimate the yielding strength of the steel tubes. Nine Quik Stik props of 8-ft high were tested using the Mine Roof Simulator (MRS) at the National Institute for Occupational Safety and Health (NIOSH) Pittsburgh research facility. Three props were tested under vertical loading to measure the vertical loading capacity of the props. Six props were tested under lateral loadings with low and high roof-to-floor convergences to measure the lateral loading capacity and the retained vertical loading capacity of the props during lateral loading. Vertical loading tests showed that the tested props could be classified as yieldable supports with a stable load capacity of about 110 kips to 140 kips. Lateral loading tests showed that the vertical load capacities of the tested props were diminished because of applying lateral loads, and the props behaved as nonyielding supports with a maximum lateral load capacity of about 8.5 kips to 9.5 kips at stable lateral displacement up to 3 inches.

Feb 1, 2023

By H. E. Hirsch

Propelled by the invention of the transistor at Bell Laboratories, germanium's unique properties have advanced our electronic world by many years. Germanium has found major uses in infrared optics, fiber optics and a revised vigor as a catalyst for PET plastic production. Other advanced applications are in various stages of development. The solid state electronics industry has been the driving force behind the accelerating demand for gallium since the late sixties. Past developments of substrates for light emitting diodes, lasers and magnetic bubble memories are paling in view of the current excitement over the use of semi-insulating gallium arsenide for high performance integrated circuits. This application requires gallium metal and gallium compounds of extraordinary purity.

Jan 1, 1986

By A. D. Rovig

Metallurgical evaluation of autogenous grinding of Anaconda's Berkeley Pit ores indicated that tonnage throughput increases, at a finer flotation feed size, were possible by converting autogenaus mills to steel ball mills. In addition, initial test work showed that the improved grind resulted in slight recovery gains in subsequent flotation processing.

Jan 1, 1974

By E. Maré

Some of the members will probably ask themselves what close relationship exists between hydro-metallurgy and a wet scrubber, but we are sure that as soon as deeper thought is given to the matter it will be realised how vital scrubbing, operations are in metallurgical plants. In ordinary metallurgical installations or pyro-metallurgical processes ore concentrates are first of all shifted from place to place and dust is created. In other cases the ores or concentrates are crushed or dried or roasted, and in each one of these operations dust and fumes, are created. All suspended particles and fumes originating from the abovementioned conditions not only, in many instances, provide health hazards which disrupt production and endanger the personnel in the plant, but also are the source of economic losses through extra maintenance and wear to moving machinery due to abrasion and corrosion. Further losses are incurred by the waste of fine, very often valuable, components. The Party who once said that in several metallurgical plants the bulk of the profits was discharged into the atmosphere by the stack wasn't stretching the truth. There is a place in Africa where a gold producing concern used to lose over 5 oz. of fine gold per day out of a total production of 3000 oz. per month. In another instance, copper concentrate going as high as 80% Cu was discharged into the atmosphere at the rate of 4 tons per day. Realising the value of removing and collecting solids and fumes created in metallurgical plants, a thorough study was made of the available plant and equipment offered on the market. Some units were found very efficient, but very expensive; some others also very efficient but with temperature and maintenance limitations. Some others were also efficient but prohibitive from the point of running costs.

Jan 1, 1963

By W. V. Swarzenski

In its, effort to combat waterlogging and coil salinity, the later and Soils Investigation Division of WAPDA (West Pakistan's Water and Power Development Authority) has carried out an extensive program of test drilling and water sampling, since 1954. Data collected during the past ten years have permitted the delineation of fresh and saline ground-water-zones in the Punjab Plain. Fresh ground water containing generally, less than 500 ppm (parts per million) of total dissolved solids is found in wide belts paralleling the major rivers and in other areas of fresh-water recharge. Locally, fresh ground water extends to depths of 1,500 feet and more. Saline ground water occurs downgradient from sources of recharge, particularly in the lower central parts of the interfluvial areas and, presumably, underlies most of the Punjab Plain. The ground waters of the Punjab are characterized by their evolution from calcium, magnesium bicarbonate waters, near sources of recharge, to waters containing a dominant proportion of sodium. The highly mineralized waters of the Punjab are generally of the sodium chloride type, whereas in Dera Ismail Khan District sodium sulfate waters predominate. The pattern of distribution of saline ground-water zones and the observed gradual increase in mineral content, downgradient from sources of recharge, can be explained best by a hypothesis stressing the processes of evaporation from the water table and solution of minerals within the alluvial aquifer.

Jan 1, 1967

By R. H. Ring

The Automatic Extraction System (AES) was designed and built under a U.S. Department of Energy Contract by the National Mine Service Company in cooperation with the Lee Engineering Division of Consolidation Coal Company. The Pennsylvania State University, Mining Engineering Section, was contracted as an independent auditor of the AES performance. The AES had a rotating cutter drum like a continuous mining machine; but two hydraulically powered roof supports, four roof-bolting drills, a dust scrubber, a ventilation fan and ducting in the roof supports, semi-automatic control, an extensible chain conveyor, and other innovations led to the distinction "extraction system" as opposed to "miner-bolter" or "continuous mining" machine. After design and assembly, the AES was field tested experimentally in an underground coal mine. The in-mine performance audit was preceded by a computer simulation of the potential production for a later comparison with the actual tonnage mined by the AES. This paper describes the results of an in-mine trial and assesses the production potential of the AES.

Jan 1, 1980

By S. Kenzap, V. Kazakidis

Risk assessment is an essential component of mine feasibility studies. However, it is often challenging to identify the appropriate analysis and derive the required input data. The uniqueness of a mining project and the associated technical issues require customization of the risk assessment approach to meet both requirements and characteristics. The uncertainty driving the operating risk in mine feasibility studies and its assessment through Monte Carlo simulation as a component of a cash flow analysis are discussed in this paper. The paper introduces the use of the analytic hierarchy process for derivation of qualitative input and conducts quantification of the three main sources of operating performance delays, equipment, ground and schedule problems, in a cash flow simulation. A methodology for the assessment of operating risk in mine feasibility studies is presented.

Jan 1, 2011

By N. J. Keys

This paper concerns the development and application of a high throughput multi-stream photometric sorting machine developed for the South African gold mines. It is now believed that this sorter and its progeny may be found suitable for a large proportion of all possible sorting applications. A laser light source and sensitive photomultiplier are employed in a scanning system to detect light reflected from the surfaces of rocks passing through the sorting zone. Electronic circuitry then analyzes the photomultiplier signal, which represents the varying intensity of the reflected light, and produces control signals to actuate the appropriate valves of an array of air blast rejection devices to remove from the feed certain particles selected by the analyzing process. Typical throughput per machine ranges from 50 tons/hour for a-2 ½? + 1 ¼? feed to 200 tons/hour for -6" +2 ¾ " material.

Jan 1, 1974

By William H. Lane

After a number of years of engineering and operating assignments and through many types of evaluations, the need for a simple analytical method of evaluating mine haulage alternatives became obvious. Haulage, like 50 many other facets of mining, is generally a sequence of interconnected events that change, often drastically from mine to mine. Often the operator or the mine engineer has neither the time, manpower, facilities, or information needed to prepare a detailed evaluation. For many studies or for routine variance analysis, that detail may not be necessary. The intent of this article is to present an approach for analyzing mobile mine haulage that is simple and straight-forward. These methods are not designed to replace more formal and detailed procedures that have been developed previously and are available in our technical libraries. They are offered as a tool to be applied to preliminary designs, feasibility studies, and variance analyses where more complete detail is not warranted. These methods will eliminate combinations that are not economical or appropriate before more intensive and complete evaluations are undertaken. These methods may also be used to evaluate ongoing operations and to plan changes in those operations. This presentation describes a series of steps that have evolved for the handling of haulage evaluations. It concentrates on the factors having major impact on the results. Because the approach is a sequence of distinct steps, a case study was chosen as the best method of presentation. This case is a composite of several actual situations that have been encountered within the last few years.

Jan 1, 1978

By John S. Carman

Our industry is in trouble. Real trouble. It has never been an easy, secure business. But to-day it is engulfed in revolutionary currents. No longer can there be reliance upon the checks and balances of market forces. Supply and demand largely dictated the economics of business enterprise in simpler days. To-day politics, in particular nationalism become increasingly dominant. And as governments expand and put out tentacles of interference in the direction of the mining industry, far too little understanding is evidenced as to how that industry works. Then there is something which is relatively new -stagflation. As the prices of minerals falls, the capital investment required for new extractive facilities soars at rates which far outdistance those which are cited by governments to indicate the magnitude of inflation. To illustrate; 1) In 1971 it was calculated that $355 million would be required to bring the Cuajone property in Peru into production. Five years later that stage was reached at a cost of $680 million. 2) With the Caridad mine in Mexico, estimated capital investment doubled between 1971 and 1976. 3) The requirements calculated for Cerro Colorado in Panama have risen in two years from $560 to $800. 4) The budget of $240 million for Sar Chesmeh in Iran in 1971 had become $500 million by 1976.

Jan 1, 1977

By George D. Haley

This report will be given in two sections. The first sec¬tion outlines techniques and equipment to form almond shaped fluorspar briquettes by means of briquet presses, and the second section outlines techniques of the balling disc. PART I - BRIQUET PRESSES Fluorspar has been briquetted for a number of years and the so called "peach pit" briquet is known to many steelmen. Present production is estimated at over 100,000 tons annually. Slide 1 shows an assortment of various sizes and shapes of briquettes. It is possible to form fluorspar into almost any configuration of briquet. For safety on the melting floor, pillow type briquets are preferred. Ease of mechanical handling and durability of the product are facil¬itated by an almond shape. The dimensions of the almond can vary from 1-in. to 1-1/2-in. in length, from 13/16-in. to 1-in. in width and from 1/2-in. to 1-in. in thickness. The type of equipment to pro¬duce almond shaped fluorspar briquettes is shown in Slide 2. Here we have a Komarek-Greaves and Company 300 ton briquettor equipped with almond rolls. This machine is capable of producing fluorspar briquettes at a rats of 30 tons per hour with power consumption of 35 hp per ton par hour.

Jan 1, 1969

By Ryan Marsters, Adam Pring, Robin Dornfest

Raw water supply in the central Rocky Mountains often relies on trans-basin conveyance. Many of these older diversions incorporate high-elevation, miles-long tunnels driven over a century ago in hard rock. Tunnels were excavated using conventional drill-and-blast mining and weak ground was supported by timber sets and other various means. Over time, timbers rot and fail, rock quality deteriorates, and the timbers are gradually replaced by more timber, steel patches and braces, formed concrete, rock bolts, split sets, shotcrete, and other means which are commonly applied over existing support, thereby reducing tunnel cross sections, obscuring previous support systems, and rarely addressing the failing rock itself, leading to further deterioration of both the rock and the existing support. Traditional investigation techniques to assess compromised areas are often unfeasible due to access, depth, rubble and voids behind weight-bearing existing supports, confined space, poor invert conditions, poor ventilation, and flowing water. This presentation will discuss design procedures for assessing obscured ground conditions, assigning support classes which accommodate for unknowns, and implementing contractual means to address inevitable surprises or quantity overruns. Case studies include raw water supply tunnels in the Rocky Mountain region constructed between early to mid-20th century.

Dec 1, 2022