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By L. A. Taylor

The production of oxygen on the Moon utilizing indigenous materials is paramount to a successful lunar colonization. And several processes have been put forth to accomplish this. The LLOX generation schemes which have received the most study to date are those involving?: 1) the reduction of ilmenite (FeTi03) by H2, C, CO, CH4, CO-CI2, & Cl2 plasma, 2) magma electrolysis, both unadulterated and fluoride-fluxed, and 3) several others, including carbo-chlorination, HF acid leaching, fluorine extraction, magma oxidation, and vapor pyrolysis. The H2 reductions of ilmenite and magma electrolysis processes have received the most study to date. They are both feasible schemes with various pros and cons, including their feedstock requirements. However, all processes should be addressed at least at the onset of our considerations. There is an obvious need for considerably more experimentation and study. Some of these requisite studies are in progress, and this paper reviews several of the most studied and feasible processes for winning oxygen from lunar materials.

Jan 1, 1991

By D. Shink

A small scale continuous flotation cell was designed and constructed at Noranda Technology Centre to develop a mobile testing flotation circuit located next to the production circuit. This mobile small scale flotation pilot plant can easily and economically be set up at any circuit in a mill and used to evaluate and predict plant performance against a given flotation condition. The main feature of the cell, beside the provisions of automatic pulp level and feed rate control, is to provide a reduced surface to volume ratio approaching to that of an industrial machine. This paper describes the basic design and the results of various testwork carried out to date including aeration, conditioning, reagents, recirculation, flotation gas, etc. are presented in comparison with the plant production results.

Jan 1, 1992

By Shilpa S. Haramkar, Bhaskar N. Thorat, Sachin V. Jadhav

The filtration of phosphogypsum is a ubiquitous step in the manufacturing of phosphoric acid. It is highly desired to achieve the minimum concentration of P2O5 in the phosphogypsum cake. This work is aimed at addressing P2O5 losses in phosphogypsum (PG) along with the recovery of P2O5 from slurry by using constant pressure filtration at 1 bar pressure. Laboratory tests were carried out in the phosphoric acid production plant situated in Paradeep, India. Recycled water source near acid plant (i.e., pond water) was used for cake washing to reduce the burden on fresh water stock. The findings indicated that pressure filtration offered the most effective P2O5 recovery (nearly 93.48%). The moisture was reduced to 14–16%, and watersoluble P2O5 in the gypsum cake was found to be negligible. A narrow particle size distribution was observed, which offered effective filterability with average cake resistance of 2.38 × 1010 m/kg, indicating a moderately separable cake.

Aug 23, 2023

By C. J. Bise, P. Bucks

Central Appalachian coal reserves are a valuable natural resource in high demand, both domestically and internationally, justifying efforts to increase percentage recovery through pillaring. Unfortunately, the challenge associated with pillar extraction introduces additional safety risks during the activity. Although pillaring developed prior to mechanized mining, current technology and mining practices have made this form of mining highly modernized. However, current fatality trends suggest that work still needs to be done to control the residual risk that is not controlled by modern practices, such as those having a personnel-performance-based component. This paper investigates the application of modern coal pillaring techniques and will present a risk-management-based strategy that targets personnel-performance-based risk, in order to improve the ability of safety engineers, managers and trainers to provide training programs addressing the needs of pillaring sections.

Jan 1, 2012

By J. F. Snyder

Minor elements determined by atomic absorption spectroscopy include: zinc, cadmium, copper, cobalt, nickel, chromium, manganese, and iron. Of these elements, only three; zinc, cadmium, and copper are found to have been introduced with the ore-forming fluids. Iron, manganese, chromium, and nickel were increased in dolo-stone lithologies when compared to limestone lithologies. The uniform distribution of cobalt suggests this element was neither increased nor decreased during ore emplacement nor during dolomitization of the rocks. Zinc increases adjacent to ore result from leakages into open spaces rather than as pervasive aureoles surrounding ore bodies.

Jan 1, 1977

By Farzad Moradpouri, Kianoush Barani, M. R. Azadi

The aim of this paper is to assess the effect of microwave treatment on copper sulfide ore for ball milling and bed breakage. Liberation analysis of ground products in eight size fractions showed that microwave pretreatment liberated more chalcopyrite particles from the bed breakage product than the ball mill product. In bed breakage, microwave pretreatment caused a 2% increase in chalcopyrite liberation on average. Microwave pretreatment produces more elongated particles in ball milling and more rounded particles in bed breakage, respectively. Microwave pretreatment produces coarser chalcopyrite particles with a wide range of sizes. This effect is more significant in bed breakage compared with ball milling. Micro-flotation test results showed that in ball milling, treated and untreated materials have similar metallurgical performance and there is a little difference (1%) between the average Cu recovery values. However, in bed breakage, the average recovery for the treated materials is about 5% higher than the untreated materials.

Jul 8, 2021

By J. F. Brune

This is a shortened version of the paper ?The Methane-Air Explosion Hazard Within Coal Mine Gobs published in the 2013 volume of SME Transactions (Brune, 2013). This paper analyzes the explosion hazard resulting from the formation of methane-air mixtures in the mined-out gobs of underground longwall coal mines. Evidence from numerous mine explosions suggests that explosive methane zones can form within longwall gobs. Explosions and fires resulting from these methane accumulations have led to severe and fatal injuries to the miners, including the explosion of the Upper Big Branch mine in West Virginia, where 29 miners lost their lives. The paper also reviews current research on numerical modeling of gas flows in longwall gobs and outlines how targeted injection of nitrogen into gobs can effectively reduce the volume of such explosive methane zones. The paper concludes that comprehensive monitoring of gas compositions along the accessible fringes of the gobs along with inertization, improved ventilation schemes and further research are necessary to control this explosion hazard and make mining operations safe.

Feb 23, 2014

By V. Srivastava, T. Ghosh

The modeling and simulation of semiautogenous (SAG) mills have been widely used in the design and optimization of mill performance in terms of its power draw, processing capacity and product size distribution. However, these models are solved under steady approximation and do not provide any information on mill charge distribution in real time. 7KLVSDSHUDWWHPSWVWRFKDUDFWHUL]HPLOOFRQWHQWVE\VROYLQJ:KLWHQ¶V¿UVW RUGHUFRQWHQW EDVHGPRGHOLQWKH0$7/$% Simulink environment. The parameters in the model, such as breakage rate constant, discharge rate and appearance function, were estimated using process and design data collected from a gold mine operating in Alaska coupled with a nonlinear parameter estimation scheme. This model was then used to predict the dynamic responses of other key operational variables, such as mill power, bearing pressure, charge level and product size distribution. The transient response of mill behavior with respect to changes in feed size distribution, tonnage and mill feed water is also presented. This dynamic simulation approach can be used for practicing different control strategy and training purposes. The observed response of mentioned variables was validated using dynamic response data from the plant to encompass operational characteristics of SAG mill behavior.

By K. Fair

Using an agitated column 203 mm (8") diameter by 1829 mm (72") tall with independent agitation units for the gas dispersion zone and the collection zones, respectively, permitted the independent evaluation of the attachment and the detachment mechanisms for the chalcopyrite/ silica system. Three particle size fractions were used in this study, i.e. coarse (+75 µ m), intermediate (-75 µ m + 10 µ m) and fines (-10 µ m). The optimum selection of the two agitation zones for the three particle size fractions were determined as a function of grade, recovery, residence time and air superficial gas velocity.

Jan 1, 1990

By D. S. Kimbal

The McCoy/Cove mine is located 48 km (30 miles) south of Battle Mountain, Nevada, USA, in the Fish Creek Mountains at an elevation of 1548 m (5080 ft), see Figure 1. Joseph H. McCoy first discovered gold at this location in 1914. This discovery led to the Gold Dome Mine which produced the first gold from this area in 1928. After the Gold Dome era, the land remained relatively dormant until Houston oil and Minerals Corporation purchased the claims from the Summa corporation and defined an ore body at the present day McCoy pit. In 1986 Tenneco Minerals (formerly Houston oil and Minerals corporation), sold the McCoy mine and adjoining claims to Echo Bay Minerals corporation. The Cove ore body was discovered soon after the sale to Echo Bay. Echo Bay expanded the heap leach operation and built the present mill which began processing ore in the fall of 1989.

Jan 1, 1993

By J. P. Rider, T. W. Beck, J. A. Organiscak

"The National Institute for Occupational Safety and Health (NIOSH), Pittsburgh Mining Research Division (PMRD) has recently developed a series of models utilizing computational fluid dynamics (CFD) to study gas distribution around a continuous mining machine (CM) with various fan-powered flooded bed scrubber discharge configurations in an exhaust curtain working face. CFD models utilizing species transport model without reactions in FLUENT were constructed to evaluate the redirection of scrubber discharge toward the mining face rather than behind the return curtain. The study illustrates the gas distribution in the slab (second) cut. The following scenarios are considered in this study: 100% of the discharge redirected back towards the face on the off-curtain side of the continuous miner; 100% of the discharge redirected back towards the face, but divided equally to both sides of the machine; and 15% of the discharge redirected toward the face on the off-curtain side of the machine, with 85% directed into the return. These models were compared to a model with a conventional scrubber discharge where air is directed away from the face into the return. The models were validated based on experimental data and accurately predicted sulfur hexafluoride (SF6) gas levels at four gas monitoring locations. One additional prediction model was simulated to consider a different scrubber discharge angle for the 100% redirected, equally divided case. This paper describes the validation of the models based on experimental data and the gas distribution results of the CFD models. INTRODUCTION To control methane gas and dust concentrations on continuous mining operations, it is important to provide sufficient quantity of fresh air from the end of tubing or curtain to the active face. In this region, operating machine-mounted water sprays and fan-powered, flooded bed scrubbers can significantly increase the amount of airflow reaching the face [1-3]. However, when an entry is large, especially in higher coal seams, the water spray configuration and the scrubber capacity may not be adequate to maintain sufficient forward airflow to confine the dust cloud to the face. Dust can roll back toward the machine operator as a result [4]. Currently, several coal mines having negligible gas emissions in higher coal seams (2.4 to 3.0 m [8 to 10ft.] thick) with exhaust tubing systems redirect the scrubber discharge back towards the face in an effort to improve dust collection. NIOSH studied the redirected scrubber exhaust techniques for dust and gas control in a full scale CM gallery to assess its potential for industry-wide application [5]. For a CM face, previous studies have concluded that the behavior of gas and respirable dust is a complex process. The distribution/dispersion and transport of gas and respirable dust after they are liberated at the face are governed mainly by their mass properties, the movement pattern of the ventilation air, and interactions with the mining machine and water droplets created by the external water spray systems used for dust control [6-10]. To understand these behaviors in a complex CM environment and to evaluate the effectiveness of various control techniques, numerical modeling has become a necessary supplement to laboratory experiments and field studies."

Jan 1, 2017

By C. D. Broadbent

Open pit blasting can be a low cost routine or a high cost bottleneck depending on geology, environment and the operator's ability to master site conditions. Because blasting is a repetitive operation, there should be ample opportunity to optimize the process; but ordinarily this optimization is rarely achieved and then only if conditions remain consistent and predictable. Often, however, and particularly with porphyry coppers, hidden differences in rock characteristics nullify the operator's best efforts. At a porphyry copper deposit being mined by Kennecott Copper Corporation, there are all of the following rock types: oxidized and fresh porphyry, altered and silicified limestone, explosion breccia, rhyolite, sandstone, shale and several others. The units can cover large areas or be limited to a few tens of feet in maximum dimension. They are rarely visible on the bench surface and often do not show up in the bench slope. Even though the blastability of these rocks varies substantially, a generally-uniform blasting pattern was formerly used with disappointing results. Secondary blasting was often required and high bottoms occurred frequently; overblasting wasted drilling time, and explosives caused excessive throw. Several possible methods for improving the blast design were considered and a geophysical method was chosen for testing. There had been reports in the journals that seismic methods were being used in Europe as aids for blasting design. A literature search turned up work by Haxby 1/ on use of a refraction seismograph for measuring pit bench rock strength. Using his work as a springboard, equipment was purchased and a program was planned and carried out for developing, evaluating and implementing the seismic method for routine mine use. Following are discussions of the development program and results.

Jan 1, 1974

By M. Manrique

Various pyrometallurgical methods for treating Ilmenite and Zircon concentrates are reviewed. Laboratory experiments, using a thermal plasma reactor, have been performed to evaluate: the conversion of ilmenite to TiC or TiC-Fe and the conversion of zircon to ZrC or ZrC-SiC. Results are examined and possible processing routes are identified.

Jan 1, 1996

By S. Tuylu, D. Adiguzel, A. Bascetin

"In recent years the fact that mining tailings cause serious environmental problems resulted in increasing number of studies about their disposal, storage and usability in various areas. Therefore the new studies about using the tailings for some purposes such as using in shotcrete or producing concrete have been increasing recently. The study is focused on applicability of tailings for producing shotcrete. Under this scope it is considered that mining tailings can bring many advantages in case of that they are used instead of sand, silt or fine aggregate in shotcrete applications. Most important advantages can be listed as decreasing shotcrete cost, decreasing amount if mining tailings to be disposed and the contribution to be provided on sustainable production of sources. The main objective of this study is the investigation of using mine tailing instead of fine aggregate in shotcrete. In this study, 10 shotcrete designs in different proportions were formed, and properties of the mixtures were identified. Then, the experimental results were statistically analyzed, the effects of the amount of the tailing material used on shotcrete properties were presented, and empirical approaches that can be used for the estimation of these properties were developed. INTRODUCTION The disposal of high amount mine tailing on the surface is caused a lot of problems in terms of environmental impact. Unfortunately, it is known that classic disposal techniques such as tailing dam cannot provide a solution these problems. The tailing dams which are usually used in the disposal of mining tailings bring along many problems in terms of cost, environment, and human health. So mine tailings are used in different production such as shotcrete. This technique is becoming increasingly common during recent years. The usability of mine tailings in brick and concrete production instead of cement and fine aggregate has been studied by many studies [1-4]. This situation has been promising for the usability of tailings in shotcrete which is commonly used for ground support especially in tunnels. Shotcrete (sprayed concrete) is applied mainly for construction of tunnels, shafts, renovation works and strengthening of slopes. Main advantage of shotcrete is fast development of strength, which quickly ensures stability of strengthened structure [5]. Shotcrete can be defined as spraying the grout consisting of water, aggregate, cement and optional additive mixture on the desired surface with a compressed air. According to the definition of the American Concrete Institute (ACI), it is the spraying of sprayed grout or concrete on a surface at high speed with air pressure [6]. In recent years, the use of shotcrete for the support of underground excavations is decreased in the mining industry. The design of shotcrete support for underground excavations is a very imprecise process. Strength and pumpability properties of shotcrete are very significant for determining suitable shotcrete design. Flow characteristics of the shotcrete must be determined for pumpability and fluidity of the material."

Jan 1, 2017

By Sah Rameshwar, T. Umadevi, K. S. SRIDHARA

In the magnetite iron ore pelletization process, oxidation of magnetite followed by sintering of the oxidized magnetite (hematite) is desirable. Optimum preheating time & temperature and roasting time & temperature is required to get the desired properties of the pellets with magnetite, hematite, and hematite–magnetite blend. In order to utilize the magnetite resources in a current induration furnace, which is designed for hematite resources, detailed pelletization studies have been carried out to optimize the firing cycle for magnetite concentrate as well as magnetite with hematite concentrate. Under optimum conditions, such as preheating temperature 1000–1150 °C, preheating time 10 min, roasting temperature 1250 °C and roasting time 7.5 min, the cold compression strength (CCS) of magnetite roasted pellets was 325 kg/p, and this was due to recrystallization of secondary hematite particles, and development of the strong slag bond between primary and secondary hematite particles. The strength of hematite concentrate pellets was 260 kg/p. From laboratory studies, it was found that without disturbing the induration furnace firing cycle, which is designed for hematite ore ~5%, magnetite concentrate can be used along with hematite concentrate in pellet blend and the strength of the pellets was 270 kg/p. As the magnetite concentrate increases in the blend beyond 5%, the preheating zone residence time should be increased or a supply of extra oxygen is required. Laboratory as well as plant investigation has shown that the addition of magnetite to the hematite mix blend improved the strength of the pellets compared to hematite pellet alone.

Oct 26, 2020

By Rodolfo Lagos, Nicos Pfeiffer, Ben Harding, Clayton V. Deutsch

This paper documents a probabilistic resource modeling workflow for the Round Mountain epithermal gold deposit. The set of categorical and continuous variable simulated realizations provides a model of variability and uncertainty given the current orebody knowledge. These realizations can be used to quantify and understand expected deviations in reconciliation during mining and provide a more accurate measure of expected gold than an estimated model. Gold mineralization at Round Mountain is primarily contained within tertiary tuff units, which dip gently to the west and thicken towards the southern part of the orebody. Domain boundaries are modeled as combinations of lithology and alteration; alteration domains are constrained to be within the tuffs. Large-scale geologic uncertainty is strongly influenced by parameter uncertainty, particularly the input histogram. The spatial bootstrap characterizes prior global uncertainty in the input histogram for categorical and continuous variables. Categorical models are generated using hierarchical truncated pluri-Gaussian (HTPG) simulation. Continuous variable simulation is carried out within the simulated domain boundaries using trend models to account for non-stationarity.

Aug 19, 2023

By W. E. Crandall

The Star-Morning mine is a. 1000-ton-per-day lead-zinc producer located in the easterly part of the Coeur d'Alene Mining District of North Idaho. The property includes both the Star and Morning mines which are located on the westerly and easterly portions of the same complex of veins. The mine is 70% owned by the Bunker Hill Company (Gulf Resources, Inc.) of Kellogg, Idaho, 30% owned by Hecla Mining Company, and operated by Hecla Mining Company with head-quarters in Wallace, Idaho. One of the characteristics of mines in the Coeur d'Alene District is that many of the ore bodies extend to very great depths. The Star is no exception, but rather a leading example. The complex of near vertical veins and ore shoots extend some 7000 feet below the surface at present, with a maximum strike length of about 4000 feet. Ore has been mined on 20 separate veins and ore structures. More than 50 miles of headings have been driven and nearly 23 million tons of ore mined since the Morning mine started in.189S. The problems of mining at such depths are formidable temperature on the bottom level is 1100 F and high humidity problem. Pressure from the sheer weight of rock is as high foot. This paper will deal with providing a new access to the deeper levels of the mine and the installation of a hoist and related items to service these levels. By the time development had reached the 7100 level (Figure 1), it became apparent that a different 'hoisting system was going to be necessary if we were going to continue to mine at a profit. The main shaft extended to the 4000 level at which point a ?:3100"'foot winze shaft provided access to the 7100 level. The two hoists were limited to handling 3-ton payloads at 1200 to 1500 feet per minute. Some ores are still produced from above the 4000 level but as these ore reserves become depleted the hoisting of the desired tonnage (1000+/day-) from the lower levels of the mine would exceed the capacity of the existing hoisting system. A decision was made to sink a new vertical shaft at a point well in the south wall of the ore bodies where strong rocks and a minimum of faulting was expected and to purchase and install a new hoist capable of hoisting over 7000 feet. This new' shaft, designated as the No. 4 Shaft, was planned to reach 2000 feet below the 7100 level which was the deepest level at that time. The hoist would be in-stalled on the ,main 2000 Adit level which is used as an access and haulage level to the concentrator and surface plant in Burke.

Jan 1, 1971

By G. Ofori-Sarpong, A. -S. Adam, R. K. Amankwah

"In the application of the BIOX® technology, high tailings grade (2-16 g/t) may be generated with a decrease in overall gold recovery, which sometimes make it economically unattractive. This paper investigated the causes of the high tailings grade by using samples from the Bogoso BIOX plant. Partial chemical analysis, diagnostic tests and cyanidation optimisation studies were conducted to invoke understanding into the high tailings grades. Diagnostic study on the tailings showed 48.34% of gold in carbonaceous matter, 17.12% in quartz, 13.40% as liberated gold, 11.51% imbedded in sulphides and the remaining 9.65% in carbonates. Optimum cyanidation recovery of 90.4% was established for the BIOX concentrate at 7 kg/t NaCN, 40-50 g/L activated carbon and residence time of 40 hours. The recovery was sensitive to carbon and cyanide concentrations but additional cyanide was not economical. High preg-robbing indices of 72.7% and 64.4% were recorded for the BIOX product and the flotation concentrate respectively. This confirms the inability of the BIOX process to deactivate carbonaceous matter, which remains a serious precursor for low overall gold recoveries and high CIL tailings. INTRODUCTION Gold ores may be broadly classified as refractory and non-refractory. Non-refractory ores are easy to treat but refractory materials require complicated flowsheets for metal extraction (Hausen and Bucknam, 1985; Schmitz et al, 2001; Marsden and House, 2006). As near surface non-refractory gold deposits are getting depleted, the increasing price of gold and increasing demand for gold, have encouraged many gold producing companies to treat refractory ores for gold recovery. The refractory behaviour of these ores may be due to the presence of sulphides, tellurides, cyanicides and/or carbonaceous matter. Refractory ores do not respond well to conventional cyanidation as the gold is either occluded by or in solid solution in sulphides, or is in association with cyanicides (Marsden and House, 2006). Further, carbonaceous matter preg-robs gold during leaching (Osseo-Asare et al, 1984; Hausen and Bucknam, 1985; Schmitz et al, 2001). The two major causes of refractoriness are the presence of sulphides and carbonaceous matter, and these render the ore double refractory (Nyavor and Egiebor, 1992). Oxidative pre-treatment processes such as high pressure leaching/oxidation; biological oxidation, ultra-fine grinding and roasting are required to render refractory ores amenable to conventional cyanidation (Marsden and House, 2006). Biological oxidation, however, has become the preferred pre-treatment route because it is more environmentally friendly and convenient even where only partial oxidation is required. Comparative tests have demonstrated that bioleaching can achieve the same or better results than roasting or pressure leaching in terms of gold recovery (Yannopoulos, 1991; Brierley, 1997). Further, biological treatment processes are more cost-effective, environmentally friendly and safer."

Jan 1, 2017

By X. Li, J. C. Stankus, J. Ma, H. Chen

Accurate evaluation of stress and geological conditions is critical to ground control design in underground openings. For a slope entry, the problem is more difficult, because a slope will transverse through many types of strata. Over the last few years, Keystone Mining Services LLC, an affiliate company of the Jennmar Corporation, has developed a new methodology designated the “Stress, geologic and support design system (SGS).” The method analyzes the stress, geology and support design for a mine slope. The method has been successfully applied in various new slopes across the United States, and ground control plans developed using SGS methodology has helped coal companies successfully pass review and/or hearings by state and federal regulatory agencies. With a case application in the U.S. Midwest, this paper details and demonstrates the main concepts of the methodology, including (1) analysis of stress and geology and identification of strong, fair and weak zones along the slope; (2) primary and supplemental support design; (3) long-term support design in the form of steel square sets or arches and (4) validation of the support design utilizing advanced finite element computer modeling.

Jan 1, 2011

By Weiran Zuo, Jinsheng Guo, Chun Yu, Jinyu Zhan, Bao Guo

High-precision prediction of the target minerals’ content in the feed and concentrate products is vitally important for the efficient beneficiation of mineral resources. Visible and near-infrared (NIR) spectroscopy provides a cost-effective way for online measurement of the mineral content in an industrial process. In this investigation, simulated specimens consisting of five different types of minerals that are present in the copper oxide ore, malachite, quartz, calcite, hematite, and chlorite were prepared with a variety of malachite contents, and the mixed specimens were analyzed by a visible-NIR spectrometer in an integral sphere mode. The reflectance spectrum is used as input and the malachite content as output to build the prediction model. The obtained data was modeled by support vector machines (SVM), and a Grey Wolf Optimization (GWO) is proposed with the goal of improving the prediction accuracy. The GWO algorithm has been applied to adaptively search for the best combination of featured values. After cyclic comparison, the optimal penalty factors c and g can be quickly and accurately selected. The experimental results show that the SVM model established by the GWO algorithm has a better fitting effect and smaller prediction error, compared with other models.

Aug 3, 2023