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Viscosity measurements were carried out on slags in the CaO-Cu2O-CuO-MgO-SiO2systemcontaining ~ 63 wt% SiO2in air. The experimental work was carried out over a range of temperatures where the slags were completely liquid. Initial measurements were on a binary CaO-SiO2slag to which incremental additions of CuxO-MgO-SiO2slag with the same silica mole fraction were made. The viscosity-temperature relationship was measured for slags with‘Cu2O’contents of 0.02, 0.19, 0.38, 0.79, 1.69, 2.47, 3.01, 5.31 and 10.0 wt%. The proportions of Cu+and Cu2+in the slags were determined. The oxidation state of Cushifted from predominantly Cu+to Cu2+, with the Cu+/Cu2+ratio of approximately 0.3 for slag with a Cu content above 2 wt%. This is equivalent to Cu1.13O. The trends observed for changes of Cu2+/Cu+redox ratio with slag chemistry were consistent with the literature. Decreasing the CaO content by substituting copper oxide resulted in a decrease in the Cu+/Cu2+redox ratio. The change in ratio corresponded to a shift of the value of x in CuxO from an initial value of 1.8 to 1.1,when the slags contained 10% ‘Cu2O’. In this study, the SiO2content of the slags varied between 64 and 60 wt% as the Cu content increased. The viscosity of the slag containing 10 wt% CuxO was nearly 4.5 times lower than the binary CaO-SiO2slag. As the silica mole fraction (xSiO2) actually stayed constant (0.61±0.009),the results show that CuxO acted as a network breaker. Comparison with other ternary slags with similar silica mole fractions suggest that that addition of CuxO to silicate slags has a stronger effect on lowering the viscosity than FeO or MnO has on a molar basis. Keywords: viscosity, copper, silicate, slags

Jan 1, 2004

By M. J. Miller, N. Ripepi, M. Karmis, J. M. Conrad

Unmineable coal seams present an opportunity to sequester carbon dioxide emissions from power plants, while enhancing the recovery of coalbed methane. Injected carbon dioxide is adsorbed and stored on the coal surface while releasing methane that can be commercially recovered. Carbon sequestration, therefore, allows the utilization of unexploited mineral resources while reducing “greenhouse” gas emissions. This paper presents the feasibility, efficiency and enhanced recovery potential of coalbed methane production using carbon dioxide sequestration in the Central Appalachian Basin. The focus of research is on geological characterization of unmineable coal seams in Central Appalachia and the corresponding carbon dioxide storage capacity. Virginia Tech and Marshall Miller & Associates, Inc. conducted this research under the Department of Energy’s Southeast Regional Carbon Sequestration Partnership program.

Jan 1, 2006

By W. Biermann

All industrial processes are economically driven, resulting in the ever increasing need for process optimization in order to stay competitive and profitable. Numerous models has been published depicting the optimization of the raw material usage in an arc furnace, as well as the thermal and electrical efficiency; however, to obtain a holistic view of the cost-effectiveness of the process one needs to expand the model to include the cost of all the operational variables. This project therefore aimed to not only include the raw material feeds and power consumption as input variables, but also the labour, maintenance, and environmental costs to generate an all-inclusive financial balance. In the end, the model was able to mathematically optimize the ferrochrome (FeCr) production process through evaluating the effect of a specified combination of input parameters. It could therefore be used as a tool to aid in managerial decision-making; to appraise and correspondingly adjust certain operational variables in order to achieve a maximum return on investment. This paper fully describes the reasoning behind the choice of the essential model components, the assumptions made during the models development, the calculation approach, as well as the advantages, limitations, possible applications, and areas for expansion of the final model. Through running simulations with plant data, it was found that the accuracy of final model remained fairly constant when applied to stable furnace conditions, but was met with a number of limitations when applied to more complex situations. These limitations could, however, be overcome through further development and expansion of the existing model to include a larger number of process variables.

Jan 1, 2012

By J. Hollow, D. Walsh

The Fort Knox Mine is located in Alaska’s interior, where the average ambient air temperatures range from -24oC in January to 16oC in July. The mill processes a free milling gold ore utilizing both a gravity recovery circuit and a conventional cyanide leach/carbon-in-pulp circuits. Mathematical models have been developed to accurately predict the impact of leach circuit slurry temperature on gold leach, carbon adsorption and cyanide destruction kinetics. Additionally, an energy balance approach has been used to model the seasonal variations in slurry temperatures throughout the Fort Knox mill. The energy balance model, combined with the kinetics models previously developed to predict plant performance, was used to justify a tailing thickener installation at the Fort Knox Mine. This paper describes the development of the energy balance model and its prediction of plant performance assuming a tailings wash thickener to reduce heat loss from the mill. Also presented is an analysis of the post project plant performance that validates the model and shows the mine produced an additional 596 kg (19,155 ounces) of gold, while reducing mill reagent costs by $6,302,000 during the first 38 months of operation.

Jan 1, 2007

By Will Foreman, Douglas D. McLearie, Edwin K. H. Tong, William H. Hansmire

Hong Kong’s Strategic Sewage Disposal Scheme (SSDS) Stage I involves the provision of a system of deep tunnels for transporting to a central treatment works wastewater collected from a number of catchments around Victoria Harbour. For the SSDS Stage I works, about 24 km of tunnels have been excavated in hard rock at depths ranging from about 80 to 150 m below Victoria Harbour and the surrounding heavily developed areas of Kowloon and Hong Kong. Five tunnel boring machines(TBMs) with diameters ranging from 3.2 m to 4.3 m were used to excavate the tunnels. Tunnel excavation has been completed and tunnel linings are in progress. Major tunnelling issues such as ground stabilisation and water control encountered in the project are summarised. An overview of one of the possible future tunnel systems that might be adopted in subsequent stages of SSDS is also presented.

Jan 1, 2001

By M. Ramström

"In 2002, Atlas Copco Rock Drills AB released the new rig control system (RCS) technology for all of its drill rig types. RCS opened the way for a new generation of computerized drill rigs based on modern, standard PC-computer technology. Drilling accuracy, information logging, reduction in manpower in some types, and serviceability have all taken a quantum leap forward when compared with previous generations of drill rigs. RCS is modularized and distributed by means of CAN-bus technology. This technology, which is well proven in automobile applications, forms the communication backbone of the rig. The modularity facilitates almost unlimited possibilities for the expansion and adaptation of drill rig functions."

Jan 1, 2005

By Jogeshwar P. Singh, Aser I. Abbas, Mohamed Ashour

The presented methodology predicts the pile head response (i.e. pile head load - displacement curve) and develops the load transfer (t-z) curve of piles in sandy soils under tension forces based on soil/pile properties and soil-pile interaction. The proposed approach improves the prediction of the t-z curve in sandy soils compared to current practice. The method employs a nonlinear soil constitutive model to calculate the mobilized shear stress/strain in soil at the soil-pile interface induced by pile upward displacement. The approach accounts for the influence of the pile slenderness ratio on the predicted t-z curve and is validated through comparisons with measured pile head response and t-z curves from full-scale pile load tests. INTRODUCTION Piles may be subjected to axial uplift forces due to either static loading or cyclic loading. The majority of methods are only concerned with the pile ultimate tensile capacity. However, the mobilized pile stiffness (i.e., pile-head load-displacement relationship) is essential to determine the interaction between the foundation and the superstructure and consequently the performance of the whole structure. Methods that assess the pile ultimate tensile capacity usually assume the failure surface at the soil-pile interface and estimate the local side shear resistance using a lateral earth pressure approach. The Naval Facilities Engineering Command (NAVFAC 1986) and the US Army Corps of Engineers (USACE 1991) employed Eq. 1 to assess the ultimate shear stress (τ) developed at the soil-pile interface.

Jan 1, 2018

The paper outlines the history and current status of the VALMIN Code and sets out the background, methodology, results and recommendations of the Independent Review of the VALMIN Code undertaken during 2001 under the Chairmanship of Ian Goddard. The paper is based on the final report of the Taskforce, which was submitted to the Board of The AusIMM for consideration.

Jan 1, 2002

By Ronald C. W. Webber‑Youngman, Philani Larrance Ngwenyama

Entrapments are a huge risk in underground mines. This happens when miners (or any other persons who have entered underground) survive the initial event of an accident, become trapped or lost in unknown and life-threatening locations after evacuation, and remain unaccounted for. At this point, every second counts, and emergency response is highly desired for any chances of saving survivors. The survival chances of the missing persons depend on how quickly they can be located. Rescue teams are often deployed to search for the missing persons underground. However, the rescue teams are forced to search in random and presumed areas of the mine. This is due to the unavailability of information pertaining to the whereabouts of the missing persons. Not only the provision of accurate locations, but various other types of information such as post-accident two-way communication can enhance the survival chances of the missing persons. This information can be provided by a fit-for-purpose missing person locator system. A wide variety of missing person locator systems are already commercially available, some are in testing phases and others in prototype and development phases. This includes tracking, tracing, location detectors and post-accident two-way communication systems. These systems have unique functionalities, capabilities and limitations; making it difficult for mines to select the most effective, applicable and suitable system specific to their mine. In this study, the user requirements for a fit-for-purpose missing person locator system were developed. The purpose of the user requirements was to provide a guideline to facilitate the system selection process. The user requirements can also be used as a tool to measure and evaluate the performance of the selected missing person locator system. The user requirements were also used to predict the success of the selected system under different missing person incident scenarios. The development of the user requirements showed a potential for many other benefits for missing person locator systems.

Nov 2, 2023

By Ronald Branstetter

Gaseous and particulate exhaust emissions from 20 diesel engines in service at five underground mines were measured with high accuracy instrumentation. The engines that were tested were checked for faults or maladjustments. The vehicle and engine maintenance organization was studied at each mine and an idealized maintenance program was devised. Faults were induced in a new diesel engine to determine their effect on the characteristics of the exhaust emissions. The results, conclusions and recommendations from this investigation are presented in this final report.

Jan 1, 1983

By Steve Chorley

Open-type, or main beam, tunnel boring machines (TBMs) can achieve impressive rates of production. This type of TBM typically outperforms other types of TBMs currently in use around the world. In good ground conditions, main beam machines have achieved production rates of more than 1 km/month (0.6 miles/month). However, installing effective ground support in poorer rock conditions on main beam machines can be a major cause of concern. The design of main beam machines is such that installation of ground support equipment, particularly at the front of the machine in what is commonly known as the L1 support zone, has traditionally been limited to rock drills and basic working platforms. Personnel working in the L1 zone have, until recently, been protected by roof supports and extended fingers, often with restricted access to working areas.

Jan 1, 2011

By Jérôme Girard, Shiu Kam, Sue Longo

"Historically, tailings management in a northern climate has involved the deposition of tailings into the Tailings Management Area (TMA) as conventional slurry. This type of system is obviously viable but presents challenges that are difficult to manage as circumstances change over the life of mine. These issues can include:? Increases in mill throughput, and? Life of the TMA for the life of mine.This case study will present how thickened, high-density, non-segregating tailings are used as an alternative to conventional slurry disposal to achieve greater storage capacity and enhanced environmental performance for a gold tailings facility in a northern climate. This paper will focus on how this change in deposition strategy accommodated the increased throughput of the mill and the increased life of mine. Specifically, the paper will discuss the addition and integration of new processes to the exiting mill system to accommodate the tailings management issues. It will highlight the challenges from laboratory testing to pre-feasibility to the engineered design of the thickened tailings system implemented at Musselwhite Mine.BACKGROUNDGoldcorp Canada’s Musselwhite Mine, in Northwestern Ontario (120 km north of Pickle Lake), is an underground gold mining operation that began production in 1997. The current mill throughput is about 4000 tpd (1.4 Mtpa). Gold extraction is based on a CIP process with cyanide destruction.The existing tailings management area (TMA) is located about 2 km southwest of the mill complex. The TMA is contained by high ground to the north and to the west and flanged by a moraine ridge along the south side. A number of dams have been constructed along this ridge. The dams were first built in 1996 and subsequently raised in 2000 and again in 2005. Excess tailings pond water is discharged to a polishing pond then released to the environment via a wetland.The TMA was originally designed to contain 13.7 Mt of tailings under a ponded surface for closure. The water cover was to inhibit adverse long-term environmental effects because the tailings contain pyrrhotite and other sulphide-bearing minerals that are potentially acid generating. The design was modified during Stage 3 Construction in 2005 to expand the storage capacity to 17.3 Mt (Golder, 2005). As of end of 2009, over 16 Mt of tailings had been deposited in the TMA. The slurried tailings were historically deposited at 50% solids."

Jan 1, 2011

By Christopher Gammons

In developing countries throughout the world, gold ores are being processed by mercury amal-gamation, a technique long banned in the U.S. - unless a retort operation is used for mercury recovery - due to mercury toxicity and its effects on the environment. Amalgamation is a simple process that involves contacting a ground, slurried concentrate or ore with mercury in a slightly agitated vessel, usually for several hours, The amalgamated mercury is separated by gravity and then filtered through a fine cloth to collect the gold amalgam as a sponge, which is then fired to remove the final remnants of mercury and produce high quality gold. However, in Peru and other developing countries in South America and throughout the world, tailings are simply discarded into uncontrolled drainages and ponds and the sponge is fired in the open air. Clearly, in this case, environmental friendly and, to make matters worse, is typically conducted by family members of all ages without proper protection. Furthermore, the technique is inefficient, yielding approximately 50% gold recovery. For the past two years, faculty members from Montana Tech in Butte, MT, USA and the Universidad Nactonal del Altiplano in Puno, Peru have teamed to study the La Rinconada Mine Complex located in southern Peru approximately 100 kilometers north of Lake Titicaca and 25 kilometers west of Bolivia. The mining complex is over 5,000 meters above sea level and exists at the foot of a receding glacier in the Andes Mountains. A suite of soil and water samples collected in 2001 documented extensive Hg contamination in the Rinconada area [1]. The present paper summa¬rizes a follow-up investigation in July-2002, in which water samples were collected at numerous locations along the 200 km length of the Rio Ramis, from the Rinconada mine com¬plex to Lake Titicaca, In addition, we report new results of Hg analyses of fish from Lake Titi¬caca, The results of this study have relevance to safety and health concerns for the miners as well as people in downstream communities.

Jan 1, 2003

By J. F. Papp

In the United States, chromium has been consumed in three major markets: chemical, metallurgical, and refractory. The predominant end use for chromium in the United States is in the metallurgical market as an alloying element in the production of stainless steel. In addition to being a major stainless steel-producing country, the United States is a major world producer of chromium-containing chemicals and has used substantial amounts of chromite ore for refractory applications. Chromium use is not easily further subdivided within the chemical and refractory industries because there is insufficient publicly available information to do so; however, chromium use can be subdivided among metallurgical industry uses based on the American Iron and Steel Institute (AISI) reported shipments of stainless steel by market classification (agricultural, aircraft, automotive, etc.). It is the goal of this study to determine the distribution of U.S. chromium apparent consumption among major markets in the United States. The distribution is expressed in the form of dimensionless fractions that are computed based on documented chromium consumption by major market. The distribution of chromium among markets within the metallurgical market is computed in a similar manner. Distribution factors are first computed for the major markets, then for markets that are subdivisions of the metallurgical market. The distribution of chromium among major markets has changed substantially over the time period of analysis. The fraction of chromium consumed by the metallurgical market has increased while that of the chemical and refractory markets has declined. Within the metallurgical market, the service industry market accounts for the greatest fraction of chromium consumption followed by transportation. Electrical, machinery, and fabricated products markets account for a substantial share of the metallurgical chromium consumption.

Jan 1, 2004

By K. Hopperstead

Ventilation planning in trackless metal mining is often taken for granted. This paper highlights the trials of planning and executing the ventilation design for Bog Zone at the Lisheen Mine. Ventilation planning for Bog Zone started at the feasibility study stage in 2003; subsequent design changes continued until 2006. In August 2006, the development of the Bog Zone ore body was accelerated through the use of contractors; in addition, the Lisheen equipment fleet was revised based on a larger load and haul fleet. As a result, the circuit was reviewed in terms of changes in design conditions and best practices. This review resulted in a 40% increase of total airflow required to mine Bog Zone. Resources utilized to design the circuit include: external review, computer modeling, and in-house Lisheen planning and operational staff review. The final ventilation design configuration was adopted in 2007, after modeling and evaluating 30 different scenarios, resulting in a better distribution of airflow, optimized secondary escape way, reduced contaminants, and a total power reduction. The value of investment in computer modeling of primary ventilation circuit and planning for staged implementation should never be underestimated.

Jan 1, 2009

By J. L. Fuentes-Cantillana, J. B. Solar Menéndez, A. O. Cámara

The Principality of Asturias is a region situated in Northern Spain with two centuries of tradition in underground coal mining. In addition, its uneven relief has obliged the construction of a great number of tunnels both for railways and roads. Basing on this experience and an ever increasing need to improve on safety, the Barredo Foundation dependent on the Regional Government and the University, provides and manages a Centre for Research of Fires and Ventilation in Tunnels. The Centre has as its most important infrastructure, a tunnel 540 m long, 9,5 m wide and 8,0 m high at centre. This section coupled with ventilation equipment allows the simulation of risk conditions at real scale, which is achieved by modifying the geometry of the section and through two powerful stations situated one at either en of the tunnel. In addition, the Centre houses two test benches for fans and electrical motors at high temperatures. One bench with a re-circulation conduit is the most appropriate for tests in Transversal and Semi-transversal type of installations. The other, is for the testing of electrical motors or fans which operate in zones where the surrounding temperature is high. In this Centre, training has also been developed for Fire Fighters and Civilian Protection Personnel who have to work in fire and smoke rescue conditions in underground structures. Testing conducted at real scale enables this formation and also to improve different computer programmes in the field of Fires and Ventilation.

Jan 1, 2003

By J. Lehmann, H. Gaye

A brief review of Computational Thermodynamics software concerning the modeling and prediction of reactions involving metals, slags and fluxes is presented. Their application for various steelmaking treatments is discussed. Examples concern phosphorus removal in BOF and EAF, ladle steel desulfurization, and specific treatments for inclusions control in semi-killed or Al-killed carbon and stainless steels.

By Russel Bohn

The purpose of this study was to evaluate the various techniques far mine roadway dust control. This evaluation included (a) the types of dust suppressants available, (b) the interaction of these products with the properties of the roadway surface, and (c) the costs and performance measures of the predominantly used dust suppressants. Over 30 products were identified having a wide range of effectiveness depending largely on the properties of the road base, subsurface, and wearing surface. The effectiveness of a dust suppressant was also found to depend on the application and maintenance procedures employed. As a result of this investigation five dust suppressants were identified s being predominant in the surface mining industry: Coherex, wetting agents, lignin sulfonate, water, and calcium chloride: An approximate cost-effectiveness analysis, limited by the lack of quantitative field performance data, showed that the five suppressants ranked in the order given above, with water being one of the least cost effective. This report also presents an analysis of applicable federal and state regulations.

Jan 1, 1981

By Benedicto Hadad Cintra

In an inflationary environment the need for reduced cost is a daily concern of all industries. The Du Pont do Brasil "Expanded Pattern" method has proven to be an extremely effective means of reducing costs in mining, quarrying and construction operations. Over the past years much emphasis was placed on rectangular drilling patterns where the burdens are less than the spacing. The Expanded Pattern method combining rectangular and staggered patterns, was implemented in 1971 in Brazil after extensive trials in close collaboration with numerous explosives users and Du Pont do Brasil Technical Services Engineers. The best multiple row spacing-to-burden ratio (S/B) was demonstrated to be in the 2 to 5 range and the effective spacing to burden ratio (Se/Be) was found to vary from 5 to 11. These ratios are for the interior of the blast pattern and do not hold true along the front row of holes. Geological rock properties, hole diameter and inclination, explosives energy and loading density, explosives characteristics, blast pattern geometry, bench height and delay patterns along with type and size of digging, hauling and crushing equipment must all be evaluated for each and every operation. The integration of these interrelated parameters, together with sound blasting practices are the basis for the Expanded Pattern method. Color slides and documented case histories will be presented.

Jan 1, 1985

Ecological Fuel from High-Sulfur-Content Coal

Sep 13, 2010