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By G. A. Rosario, G. Peach

Twin 8.5 m diameter, 10 km long headrace tunnels under overburdens of up to 1870 m were excavated for the neelum jhelum hydroelectric project in north-eastern pakistan using two main beam gripper tunnel boring machines (tbms). Rock bursts were encountered and presented a significant danger to personnel and equipment. Micro seismic monitoring was installed to analyze rock burst characteristics and to create a database for future reference. Correlation of rock burst characteristics improved the ability to predict the likelihood, location, severity, and number of rock burst events. This paper presents the analysis of the micro seismic data

Dec 1, 2022

By D. K. Steele

The U.S. Bureau of Mines has investigated the recovery of metals from copper industry wastes by sulfuric acid leaching in a semi-continuous, bench-scale system to solubilize arsenic, copper, and molybdenum. Leach residues contained approximately 40 wt pct PbSO4, suitable for processing at a lead smelter. Arsenic and molybdenum removal from leach solution was examined using solvent extraction with tri-n-butyl-phosphate (TBP), and copper was subsequently recovered by cementation. Bleed electrolyte from a copper refinery was determined to be a viable source of acid for the initial leach stage.

Jan 1, 1991

By M. Kuchta

A linear integer programming (MIP) model to solve the long-and short-term production-scheduling problem for sublevel caving operations is presented. The MIP model is designed as a multi-time-period problem to provide monthly schedules that meet production, blending and sequencing requirements. One of the most important issues during the development of the MIP model was the requirement of sequencing between blocks. In this mathematical model, unique constraints that ensure sequencing of the production from sublevels are developed. A suggested method of handling a large number of variables is also given. The MIP scheduling model was implemented on a data set obtained from the Kiruna Iron Ore Mine located in northern Sweden. The initial MIP model implementation was successful and provided a solution that optimized resource recovery while meeting monthly and yearly production constraints. The scheduling results obtained based on the Kiruna Mine are further presented and discussed.

Jan 1, 2003

By S. Zendejas-Mendivil, E. Pérez-Segura

The Cananea porphyry copper-deposit is the site of the second largest mining operation in Mexico. Mineralization is related to quartz-monzonite Laramide stocks that intrude volcanic and volcaniclastic Mesozoic rocks. The ore deposit is a stockwork and breccia-pipes system with Cu-Mo sulfides and pervasive quartz-sericite hydrothermal alteration. A study was made of the arsenic distribution in the mine and the ore-dressing plants. The arsenic (As) in the mine is related to a feldspathic quartz-porphyry type rock associated mainly with the breccia pipe structures (100-700 ppm As in the Veta 7 Breccia). There is vertical zoning, with As decreasing in the deepest part of the breccias. This As mineralization corresponds to a later sulfide hydrothermal stage. The concentrates are made of Cu, Fe and Mo sulfides and some minor quantities of As minerals. The most important copper minerals are chalcocite-covellite, bornite and chalcopyrite. Some of these minerals have 390-880 ppm As. The main As mineral is enargite[ [Cu2.97Fe0.06(As0.90 Sb0.01Pb0 01 )0.92 S4 051 and there are traces of stibioluzonite-luzonite I Cu, .95(Aso.4vSbu.49)0.9rfS4.07-Cu2 93(Aso.H4Sba.10)0.94S4.13] and of another stibioluzonite mineral type with substitution of As by Bi[Cu,96(Ascr,,'Sb0ccrB'OJ3jI~6S] These minerals contribute 80% of the As in the concentrates.

Jan 1, 1992

By Fritz Eder, Rick Hendrickson

The quantities requires decisions growing demand for large of oxygen by gold smelters today that economic and operational be made regarding their selection providing electrical power, water, communications, sewage facilities and access roads. Liquid storage and supply system is of the system. decisions most appropriate oxygen supply Key factors affecting such are discussed in the following.

Jan 1, 1990

By C. R. McClung

"Molybdenum, in the form of molybdenite, is a common byproduct of many copper mining and concentrating operations. Contrary to most copper sulfide minerals where recovery is principally liberation controlled, the recovery of molybdenite is much more complex with fully liberated particles commonly lost to tailings. It is this complexity that facilitated the necessity for a geometallurgical investigation of molybdenite from the Bingham Canyon deposit. The aim of this investigation was to determine the effect mineralogy and/or mineralogical attributes (i.e. morphology, angularity, liberation, size) have on the recovery of molybdenite in the processing circuit. A set of samples was collected from the ores and products produced by Rio Tinto Kennecott’s Copperton Concentrator. All samples were analyzed using normal polarized reflective light, Mineral Liberation Analyzer (MLA) and X-ray diffractometery (XRD) techniques. The results of this investigation revealed the presence of two distinctly different types of molybdenite, which have been identified as the two polytypes of molybdenite, i.e. hexagonal (2H) and rhombohedral (3R). The 2H polytype occurs as textbook-shaped particles in quartz-molybdenite veins that are located in the core of the Bingham Canyon deposit. The 3R polytype occurs as disseminated, “ball”-shaped particles with a dull or frosted appearance along the margins of the mineralized intrusive body or central core. Concerning their metallurgical behavior each type exhibits unique metallurgical properties that are consistent with those reported in the published literature. For instance, the 2H polytype is easily ground and kinetically “faster” floating with surface attributes that are amenable to higher rates of recovery. This commonly results in the production of a high quality molybdenum concentrate under normal operating conditions common to most copper concentration operations. In contrast, the 3R polytype is difficult to grind and kinetically “slower” floating with surface attributes that less amenable to recovery under normal operating conditions. Therefore, in deposits with higher concentrations of the 3R polytype, modifications to the normal operating parameters may be necessary to improve the recovery of molybdenum. Finally, a preliminary investigation into the metal budget of porphyry Cu and Mo deposits indicates that a positive correlation may exist between the total economic metal budget and the polytype content. For example, higher concentrations of the 3R polytype appear to be more prevalent in Au-enriched porphyries versus Mo-enriched porphyries. This observation may also serve to help explain why it is easier to obtain high rates of recovery in Mo ± W-rich deposits, which contain little to none of the 3R-polytype. Consequently, the potential for the metal budget of a porphyry deposit to be used as an indication of the molybdenite polytype present, as well as its impact on the economics (exploration) and/or on the processing circuit (plant design) could exist. In conclusion, this investigation highlights the necessity of understanding the mineralogical properties or characteristics of molybdenite and/or other economic mineral(s), as these can and will have a direct impact upon the performance and plant optimization."

Jan 1, 2016

A digital computer program has been developed to mathematically simulate the effect of limited changes in feed rate on the grinding circuit of an operating mill. The data on which the program is based was supplied by the staff of the mill in question. Samples taken around the complete grinding circuit were analyzed for solids content and particle size distribution for two feed rates. Matrix models were used to represent the grinding units: rod mill and pebble mills. Parameters for these models were computed using a method developed by Mular(l). Classifier parameters were computed by the Powell search method(2) for the Plitt model (3) . The simulation program, which permits the computing of the size distributions in the circuit resulting from the changes in feed rate between the two measured values, assumes that a linear relationship exists between the corresponding parameter coefficients. The program uses an iteration method to bring the simulated grinding circuit to a steady-state material balance for any specified' feed rate between those measured. The program is, in addition, extremely fast and economic in computing time. The results show that the simulations are not everywhere consistent with practice. For example, higher feed rates on simulation predict finer products. These errors are shown to be attributable to anomalies in data gathering techniques. An improved sampling procedure for grinding-circuit data gathering is suggested for future simulations of this type. It is concluded that the

Jan 1, 1971

By A. Anani

The goal of hot mix asphalt (HMA) design is optimal material blending to meet Superpave specifications. HMA cost minimization has being modeled as linear programing (LP) (Awuah-Offei et al 2011) and mixed integer LP problems (Brown et al, 2012) and solved with commercial software such as LINDO and CPLEX. Often these software, which are designed to solve general optimization problems, have licenses that cost thousands of dollars. The objective of this study is to develop a novel solution algorithm to the HMA optimization problem presented by Brown et al. (2012), which will negate the need for expensive commercial packages and is specific to this problem. This novel algorithm is based on the branch and bound algorithm for solving mixed integer problems. The algorithm is incorporated into a software package with an easy-to-use graphical user interface. The developed algorithm is validated using a real-life HMA problem. Using this solution algorithm will save companies thousands of dollars, otherwise used to purchase software licenses.

Feb 23, 2014

By Donald R. Simon

Money... not many subjects are as personal or as emotional. Hessiod said it well in 700 B.C. "Money is life to us wretched mortals". Are you getting paid enough? Does your company reward its top people? Does coal or copper pay more? Production or engineering? How is the synfuels industry going to influence mining salaries? Do high salaries attract and retain the best people? Do modern compensation systems ensure fairness or destroy entrepreneurial spirit? With our tax system and high standard of living why are we so salary conscious? Salary is not only important for what it can purchase but it is also a yardstick, measuring how well we are doing. We all need money to pay the bills and maintain our standard-of-living, but once we reach a certain point the psychological ramifications become more important than the purely practical side. Even necessary payments like the mortgage and the car are a function of our egos. Are our choices of cars and homes based on simple transportation and shelter?

Jan 1, 1980

By Douglas M. Dwosh

INLAND STEEL COAL COMPANY'S experience with a gypsum cement, with and without fiber glass filler, indicates that the concept of utilizing standard rock dust equipment to dry handle and apply gypsum cement as a mine sealant is feasible, simple and economical. Prior to 1975, Inland had casually experimented with a few sealants and had discussed the advantages and shortcomings of other sealants with various users. Hower in mid-1975, Inland foresaw the need to seriously acquire a practical sealant system. There were nearly a dozen sealant materials on the market at that time: silicate-based materials, Portland cements, vermiculite cements, gypsum cements, and magnesium-oxysulfate cements, each with their own fillers and additives. The applicating equipment ranged from simple to complex: wet mix or slurry machines operating on either a batch or continuous basis, high viscosity pumps, and pneumatic, dry conveying machines with water nozzles. Compounding the selection process, two or more products could often be used with the same machine, or a given material could be successfully applied with more than one type of machine.

Jan 1, 1976

By D. E. Severson

The coal solution refining process under investigation is basically a modi¬fication of the German Pott-Broche Process, on which patents date back to 1927, (5, 6). This process was used in Germany during World War II for the partial dissolution of coal in hydrocarbon solvent and removal of the ash by filtration to produce a raw material for carbon electrodes for aluminum plants. At the end of World War II the German synthetic fuel program, of which this process was a small part, was abandoned as not economical. In recent times the whole field of coal liquifaction has been given a new impetus; present technology indi¬cates that the economic processing and refining of coal may be possible in the United States. A number of approaches to coal liquifaction have been investigated, and several of these are currently being funded by the U. S. Office of Coal Research. One approach is direct thermal treatment of the coal as in the FMC Project COED, in which coal is thermally cracked to produce gas, liquid products and char. Another approach is the Hydrocarbon Research Institute's H-coal process in which coal is catalytically hydrogenated. Two other federally funded projects involve the extraction of coal by solvents. The Consolidation Coal Company's Project Gasoline, now in the pilot plant stage in Cresap, West Virginia, is an attempt to produce gasoline plus a residual char by partial solution of the coal substance. The coal de-ashing process being developed by the Pittsburgh and Midway Coal Company is a modification of the Pott-Broche process. Coal derived solvent is used with hydrogen to dissolve the entire coal substance, subsequent filtration removes the ash and the solvent is recovered for recycling.

Jan 1, 1968

By M. S. Celik

The principal impurities in some feldspar ores are titanium and iron which impart color and in turn degrade the quality of the ore. The mineralogical investigations indicate that titanium element originates from mainly rutile with small amounts of sphene. Conventionally, fatty acids and particularly sodium oleate are extensively used in the flotation of colored minerals from feldspar ores with reasonable success. In this study, new reagents, oleoyl sarcosine and hydroxamate have been used to float colored impurities before and after magnetic separation. Oleoyl sarcosine is found to exhibit better results compared to fatty acids and hydroxamate. The mechanism of the action is elaborated on the basis of experimental data.

Jan 1, 1999

By Russell L. Cook

Stringent environmental regulations, which have limited the use of sludge ponds, coupled with the economic incentive to clean more 'coal or to add fine coal cleaning additions to existing preparation plants have increased the use of static thickeners in preparation plants. The Lamella Gravity Settler, sometimes de signated Lamella Thickener, is a shallow depth sedimentation device which has been applied in a variety of industrial process and wastewater control projects in place of the conventional raked thickeners. This paper presents the theory and design of the La-mella Thickener, as well as describing the operating results from several full scale installations in a variety of Appalachian preparation plants.

Jan 1, 1977

By R. A. Meyr, K. A. Perry

Following three major mining accidents in 2006, the MINER Act of 2006 was enacted by the U.S.Congress. The U.S. Mining Safety and Health Administration subsequently released the Final Rule on Refuge Alternatives for Underground Coal Mines, which required every underground coal mine to install refuge alternatives to help prevent future fatalities of trapped miners in the event of a disaster. The following paper documents the research that was performed on a structural wall to be used in conjunction with a breathable air system to create a refuge alternative. A 103.4-kPa (15-psi) safe haven polycarbonate wall for use in underground coal mines was designed and modeled using finite element modeling in ANSYS Explicit Dynamics. The successful safe haven wall design was modeled for an actual underground coal mine environment using the explicit finite difference formulation program FLAC3D to determine the responses of the wall and surrounding strata within a mine. A full-scale design was fabricated and installed in an underground coal mine to determine any construction constraints and as a final step in proof of concept for the safe haven wall design. This paper is meant to introduce the reader to a new wall concept to be used in conjunction with current technology.

Jan 1, 2013

By Robert A. Bauer

Investigations of bedrock within subsided areas over abandoned coal mines reveal) very little disturbance of the bedrock. In areas that have surface subsidence of .3 to 1 m (1.0 to 3.25 ft), examination of cores from exploration drilling and investigations of the boreholes by means of closed circuit television have shown that fractures are spaced at least .9 to 3.6 m (3 to 12 ft) apart and are located within a zone 6 to 15 m (20 to 50 ft) above the collapsed area in coal mines 42.6 to 112.7 m (140 to 370 ft) deep. The dip of the fractures ranges from 25 to 60 degrees, cutting across nearly horizontal sedimentary bedding planes. Typical core recovery is 80 to 95 percent within the subsided areas and 100 percent outside the subsided areas.

Jan 1, 1984

By Goran Mathisson

In several investigations the correlation has been studied between the fuel consumption and the reducibility of the charged material in the zone of indirect reduction in the blast furnace (1, 2, 3, 4, 5). It has been found that increased reducibility allows greater gas utilization which accordingly lowers the fuel consumption. In direct reduction units this relation has not yet been fully established partly owing to the lack of accurate test methods and experience with different materials as regards reducibility. However, since the production rate in a direct reduction unit is closely related to the time required to reach high degrees of reduction, the reducibility must be regarded as one of the most important properties of the material.

Jan 1, 1979

By W. C. Goldberg

This paper presents pit slope monitoring and back-analysis case studies con-ducted to evaluate and, if possible, stabilize slopes at the Berkeley Pit in Butte, MT. Two specific slopes were studied in detail. The first slope was determined to be near limiting equilibrium, as evidenced by its response to the initiation and cessation of mining, while the second failed on three occasions. Back-analysis of the failed slope verified the laboratory-derived geomechanical properties of the earth materials. Early detection of slope movement can show a need to take action, including modifying slope geometry, dewatering if the slope were wet, and/or investigating and implementing artificial supports. Monitoring slope displacements in open-pit mines can supply data for predicting collapses and preventing serious damage, injuries, and/or loss of life.

Jan 1, 1989

By W. C. Meyer

The concept of using powdered coal-in-oil-mixtures (COM) as a composite fuel to conserve oil resources and relieve import supply problems is being vigorously promoted by the Department of Energy via the sponsoring of various demonstration units (1). The idea of COM as a useful alternative fuel has been explored on and off for over 100 years (2). The approach must be capable of grinding, mixing, storing, and combusting COM with presumably only minor equipment changes on oil-fired boilers. DOE estimates that 56 000 m3 of oil (350 000 barrels) could be spared daily if a 50-50 COM was used to generate electricity. Of course, the ability of COM suppliers to prepare and deliver a stable suspension of COM at reasonable economic costs must be achieved if the concept is to be successful. This report reviews the various methods used to attain stable coal-oil mixtures. Various physical-chemical principles associated with each method of stabilization are also discussed.

Jan 1, 1981

By MUSTAFA ERKAYAOGLU, ENVER YILMAZ

Coal mining is likely to sustain its critical role as energy requirements are increasing. While surface mining exploits coal seams near the surface, underground mining techniques are crucial for extracting deep coal reserves. Longwall mining is one of the most common methods used in underground coal mining operations. This paper introduces a data-based framework — including data collection, data analysis and the interpretation of operational data — for understanding the system efficiency of a longwall shearer. Operational performance is evaluated by the time between arrivals (TBA) and duration of the shearer stoppages, shearer drums’ reversal time, cutting speed and flit speed on daily production in a longwall top coal caving (LTCC) mine. A discrete event simulation model is developed to represent the bidirectional cutting sequence of a longwall shearer.

By Levent Ozdemir

An extensive study involving laboratory testing and computer modeling has been performed to assess the technical and economic feasibility of utilizing the recently developed minidisc cutters on roadheaders for hard rock mining. The results show that heavy duty roadheaders fitted with minidiscs can excavate hard rock formations at acceptable production rates and cutter costs. This paper presents and discusses the results of this study together with the ongoing developmental efforts of this technology, which include laboratory testing of a roadheader cutting drum with minidiscs and full scale field testing of a machine in hard rock

Jan 1, 1995