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By D. Rahal, I. Shah, B. Hines, S. Reddick

"The development of stirred milling technology has proven to be an enabling technology in fine grained metallic deposits. The increased grinding efficiency allows for the economic size reduction required to produce saleable concentrates. This improvement has opened the door to retreatment projects such as reprocessing of historic gold mine tailings. Recently a VXP2500 stirred mill was installed at Casmyn Mining Zimbabwe Turk mine to allow the reprocessing of historic mine tailings. After commissioning, an extensive joint research project between Casmyn and FLSmidth Minerals was conducted to optimize the performance of the mill. This paper outlines the challenges encountered in the optimization program and the outcomes from the joint research project.INTRODUCTION The development of stirred mills has opened up many new opportunities to recover valuable minerals from refractory ores. Stirred mills have already been reported as an enabling technology for the processing of fine grained ores in lead/zinc applications (Pease, Young and Curry, 2005). Historically, conventional ball mills were unable to economically grind material fine enough to produce the required recovery or concentrate grade. This often resulted in the loss of valuable materials to the final plant tailings. The advent of stirred milling has now provided an opportunity which has both economic and environmental benefits, the reprocessing of historic mine tailings. Many tailings stockpiles now contain economic concentrations of gold because of the ability of stirred mills to efficiently and economically grind the tailings to liberation sizes. The primary advantage of reprocessing historic tailings is very low cost processing. Recovering the tailings is usually as simple as pumping the material into the reprocessing circuit. The disadvantage of reprocessing tailings is the low feed grade and greater difficulty in recovery valuable minerals at the same size distribution. The material has already been previously processed so fresh surface area or an increase in metal exposure is required. These are both provided by regrinding the tailings material."

Jan 1, 2014

By José Mirão, Pedro Madureira, v Costa, Patrícia Conceição

"The exploration of seamounts south of the Azores during the EMEPC/Açores/G3/2007 campaign allowed for the collection of 30 Fe-Mn crusts from the Atlantis, Great Meteor, Small Hyeres, Irving and Plato seamounts, as well as from the East Azores Fracture Zone. These were the first samples of Fe-Mn crusts studied from these seamounts. The Fe-Mn crusts were analyzed using multiple analytical methods.The crusts are fairly homogeneous, showing typical textures for this type of occurrences. The Fe/Mn ratio, patterns and concentrations in rare earth elements, and the great homogeneity of the crusts lead to the conclusion that they have a hydrogenetic origin, precipitating directly from seawater. Although the content in Fe and Mn of the crusts is consistent with data available for the Atlantic, the mean concentration of Co is comparable to the average values for the Pacific. Cu and Ni show lower values than the ones known for the Pacific."

Sep 1, 2014

By A. T. Iannacchione

Underground limestone mines typically use the room-and-pillar method of mining in the generally flat-lying limestone formations. In some cases the dip may exceed 5° which can result in unique roof instability problems. Stability may be further exacerbated by the presence of horizontal tectonic stresses. Field studies and numerical model analyses are combined to assess the affect of the dip in various stress conditions. The results showed that where the horizontal tectonic stresses are sufficient to cause intact rock failure, increasing dip results in increased failure potential. The effect of the dip is greater when the maximum horizontal stress is parallel to the dip. Two case studies are presented and evaluated against the findings of stress analysis results. The study showed that the empirical rules of orienting headings parallel to the maximum stress are generally applicable to dipping excavations, except when mining in the up-dip direction. The importance of accurately determining the orientation of the maximum horizontal stress is emphasized because the window of favorable orientations relative to the stress is small.

By Rolf Katzenbach

The principle questions related to the design of deep foundations especially in soft soils are the stability and the cost optimised settlement reduction to prevent possible damages and to minimise the deformations of the adjacent infrastructure. The present develop­ments in the design of deep foundations lead to the design approach of the Combined Pile-Raft Foundation (CPRF) which offers a lot of new possibilities, e.g. the utilisation of the CPRF for horizontal loading or the use of the subsoil as a geothermal storage system.

Jan 1, 2006

The 2003 SME Annual Meeting and Exhibit will take place Feb. 24-26 in Cincinnati, OH. The meeting will feature a host of special symposia and programming geared toward the industrial minerals and aggregate industry sectors. This programming focus is particularly relevant for this annual meeting, as it will be hosted in the center of America’s transportation hub and industrial mineral center. Cincinnati, located on the Ohio River, is key to the movement of America’s supplies and construction material needs.

Jan 1, 2003

Despite technological improvements and better understanding of the hazards, coal dust explosions stilI occur. Experimental explosions in galleries in various countries extend knowledge with the constant aim of providing safer working conditions. The inadvertent ignition of an accumulation of methane is the traditional initiator of the coal dust explosion.There are specific parameters of coal dust explosibility and explosion propagation, including the important volatile matter in the coal, fineness and dispersibility of the dust and its concentration. Accepting that initiation cannot be absolutely prevented, it is necessary to consider explosion suppression. While both limestone dust and water are the chosen explosion suppressants, in practice water has more limitations to its efficacy when related to the degree of explosion violence. These data give rise to the criteria for explosion suppression, differences in favoured mining geometries, and using the same principles, to differences in suppression treatments.

Jan 1, 1988

By A. Tylczak, C. Norman, C. Shook, S. Loif

"There are a lot of good reasons to manage energy use at mining operations. Optimizing process energy use reduces operating costs. Tracking energy use can help identify unplanned process changes or malfunctioning equipment early, which allows problems to be corrected promptly.Sacré-Davey Engineering in Vancouver has performed over 50 Energy Management studies for various industries including: mining, pulp and paper, oil and gas, etc. Energy Management programs can be used to identify energy reduction opportunities, assess project feasibility, complete equipment selection trade-offs, as well as to monitor and manage energy costs. Benefits of energy management programs are reduced energy costs, reduced maintenance, and increased plant automation. Additionally, energy management can provide access to utility incentive funding and quantify savings which can greatly improve the return on investment of potential projects.Energy management studies are funded by many Utility programs across Canada. There are various programs available for existing plants energy audits, project feasibility studies, new plant design reviews and energy monitoring and targeting, etc. There are capital incentives available which can significantly reduce payback period.This paper discusses how energy management can be used to support mill/mine operations groups, maintenance programs, as well as expansion or green field projects. This paper will also provide an overview of Canadian Utility companies programs and how they can assist mining companies.IntroductionThere are a lot of good reasons to manage energy use at mining operations. Optimizing process energy use reduces operating costs. Tracking energy use can help identify unplanned process changes and identify malfunctioning equipment early, which allows problems to be corrected promptly."

Jan 1, 2015

By L. W. Brandt

The Bureau of Mines, as part of its mission to effect pollution abatement, conducted research to study various means of dewatering Florida phosphatic clay wastes and reclaiming mined lands. The work was done in cooperation with 10 Florida phosphate companies. During this work, a novel technique to effectively dewater phosphatic clay wastes was developed. The solids contained in the clay waste slurry are slowly compressed by moving wire mesh screens through the system. In a typical application, the screens were moved downward, compressing solids ahead of the screens. The rate of movement of the screens is an important variable in the process. It is believed that the moving screens distort the gel structure of the phosphatic clay system and cause the release of water. Samples of 18 clay wastes, including a high-grade attapulgite from beneficiation plants of the Florida phosphate field, were studied using the method. Typical samples were concentrated from initial solids of 4.7 and 11.9 percent to 16.8 and 25.2 percent, respectively, in 3-1/2 days. The high-grade attapulgite sample was dewatered from 2.7 percent solids to 13 percent solids in the same period.

Jan 1, 1980

By Kenneth R. Sites

Under this program two tape recording and triggering systems were developed and delivered for use in the Bureau of Mines microseismic program. The systems are designed to improve the effectiveness of the Bureau owned Sangamo 3500 series and SABRE VI instrumentation tape recorders. The system is designed to capture random microseismic data, digitize and temporarily store these data, start the tape recorder; and then transfer the data to magnetic tape for permanent storage. The system is designed to pack data on tape such that the tape may be simply played back through galvo drivers onto an oscillograph such that a continuous series of analog records, with corresponding time of day information, are reproduced without excessive oscillograph paper waste or the need for the operator to search for valid events.

Jan 1, 1980

By M. C. Irani

This survey was conducted to determine the magnitude of the methane emission and control problem in U.S. bituminous coal mines. The resultant data indicate that the emission rate for any given coalbed depends primarily on the coal production rate and on mine depth, as well as on the nature of the coalbed and the surrounding strata. An excellent correlation was found between (1) the methane emission rate and (2) the product of coal production rate and mine depth for the mines in the Pittsburgh, Pocahontas Nos. 3 and 4, and the Illinois Nos. 5 and 6 coalbeds. The highest total emission rates found in U.S. bituminous coal mines were as follows, in million cubic feet per day: Monongalia County, W. Va., 39; Marion County, W. Va., 30.4; McDowell County, W. Va., 13.1; Washington County, Pa., 11.9; Greene County, Pa., 11.4; Buchanan County, Va., 21.6; Jefferson County, Ala., 10.3; and Franklin County, Ill., 6.6.

Jan 1, 1972

By Thomas E. Finch

This report is a continuation and expansion of a previous USBM grant (No. G0254004) which examined alternative methods of handling the parting between two coal seams in a surface mining operation. The alternative methods consist of equipment implementation in either a stowing or haulback technique. Following a typical strip mine conformation, the parting is directly stowed or hauled back and placed in the pit bottom after second seam removal. The objectives are to produce an environmentally sound material placement technique and to increase prime stripping machine utilization. This report contains the engineering philosophy behind two computer programs created to evaluate parting handling methods over d wide range of coal and parting thickness ratios. The nature of the computer approach allows cost sensitivity analysis and quick updating of costs. The two programs are clearly presented with documentation and examples such that consumers may apply then to their own operations.

Jan 1, 1977

By Roger Davieds

FACT: a company?s profitability (or loss) is directly related to the efficiency and effectiveness of its maintenance operation. Fact: in order to contribute in a positive manner, maintenance must understand what its true purpose is in the organization. It is easy to say our main purpose is to increase: ?equipment uptime ?OEE ?asset life cycle We all understand this; so does management.

May 1, 2010

By Frank C. Townsend

Centrifugal model embankments with varying geometries and materials were constructed of- coal waste material, accelerated From 100 to 120 times earth's gravity, and subjected to various throughflow rates until failure occurred. Complementary laboratory tests were performed on the waste materials to obtain strength and permeability parameters for analytical calculations to predict observed centrifugal model behavior. Failures in the form of deep.-seated failure, or erosion and sediment transport or a combination of both, occurred in model embankments with 1V:1-1/2H and 1V:2H slopes when the phreatic surface due to seepage exited on the downstream slope: Positive seepage control, i.e., a toe drain successfully prevented sloughing and failures. Slope stability analyses agreed well, albeit conservatively, with observed model performance. Factors of safety ranged from 0.7 to 1.02 at the instant of failure for models with retrogressing slips as compared with 1.05 to 1.7 for stable embankments, These models verified existing criteria of a minimum safety factor of 1 3 and the necessity of positive seepage control.

Jan 1, 1980

It is not uncommon to find large quantities of combustible materials in underground metal and non-metal mines. Support timber is the predominant combustible material. Spontaneous combustion, welding and cutting, shorted or overloaded electrical cables and careless smoking are common ignition sources. More recently, there is increased use of diesel mobile equipment that requires fuel storage and transfer areas. Diesel fuel spillage on hot engine manifolds and motors can result in rapid flame growth and heavy smoke accumulation in a matter of seconds. In-expensive, reliable fire detection and suppression systems are available to provide early warning of fire conditions and to isolate and extinguish fires that originate in fuel storage and transfer areas. This report presents an example of how technology developed and demonstrated under Bureau of Mines Contract H0242016, Mine Shaft Fire and Smoke Protection System, may be applied to protect underground diesel fuel storage and transfer areas. The area application described in this report is a representative example only; the fire protection described includes the concepts of ? Early warning and alarm ? Isolation ? Extinguishment ? Control

Jan 1, 2011

By N. J. Bunce, B. Vollick, A. F. Souza, D. Bejan, P. Maharaj, C. Shamshoom

"Copper electrodeposition from synthetic and authentic acid mine drainage (AMD) is inhibited by ferric iron (Fe(III)), through re-oxidation of copper. Polarization to –2.5 V versus standard hydrogen electrode prevents the dissolution of predeposited copper from the cathode. Above pH 1, copper deposition is independent of Fe(III) concentration to approximately 25 g/L. Fe(III) is reduced to ferrous iron (Fe(II)), with a high combined current efficiency for iron and copper reduction. In a divided cell, the conversion of Fe(III) to Fe(II) is almost quantitative, with efficient transfer of acidity from catholyte to anolyte. Prospects for developing electrochemical technology for complete remediation of AMD are discussed.RÉSUMÉ En raison de la réoxydation du cuivre, le fer ferrique (Fe(III)) nuit à l’électrodéposition du cuivre à partir de drainage minier acide (DMA) véritable et synthétique. Une polarisation à -2,5 V par rapport à l’électrode standard d’hydrogène empêche la dissolution du cuivre déjà déposé de la cathode. À un pH supérieur à 1, la déposition du cuivre est indépendante de la concentration en Fe(III) jusqu’à environ 25 g/L. Le fer ferrique est réduit en fer ferreux (Fe(II)) avec une efficacité combinée élevée pour la réduction du fer et du cuivre. Dans une cellule divisée, la conversion de Fe(III) en Fe(II) est près de la quantité théorique, avec un transfert efficient de l’acidité de catholyte à anolyte. Les perspectives de développement d’une technologie électrochimique pour la remédiation complète du DMA sont discutées."

Jan 1, 2016

By Daniel G. Di Canio

Reference information and user instructions for Version 3.0 of the Accident Cost Indicator Model (ACIM) software package are presented. ACIM estimates the tangible costs of occupational injuries, illnesses, and fatalities in the United States mining industry.

Jan 1, 1983

By Marcel Vanpee

Eight extinguishing powders KCI, were tested on five types of diffusion flames. The effect of flame temperature on the inhibition efficiency was investigated by varying the oxygen index of the flame supporting atmosphere. Inn addition a spectrographic investigation of powder flame dissociation products was carried out on the methane/air/ABC (NH4H2PO4) flame. Dissociation products for this flame included P0, PH, NH, and Na. It is concluded that the main factor to be considered in the efficiency of tie powder is the flame temperature Purple K (KHC03) was typically inefficient in low temperature flames and very efficient in high temperature flames. On the other hand, ABC (NH4H2PO4) was found to lose its efficiency at high temperature but to be quite efficient in the low temperature flames. The effect of temperature is offered as an explanation of the poor efficiency of Purple K (KHC03), against coal dust explosions as contrasted to the high efficiency of phosphate salts against coal dust explosions.

Jan 1, 1982

By Farrukh M. Mazhar, Philippe P. Martin

Electrical Vertical Sounding (EVS) profiling has proven to be a valuable tool to set the alignment and guide the design of a 17 km-long, 4.7m diameter water-conveyance tunnel in the Peruvian Andes at an altitude of 4,260 m. EVS profiling helped determine where to locate boreholes, and reduce the amount of drilling to 1,200 m of vertical and inclined boreholes. EVS profiling allowed the designer to identify and verify by drilling the existence of zones with difficult tunneling conditions that were avoided by realigning the tunnel. The rock quality was checked by drilling and a combined scheme of excavation by TBM and conventional drill and blast technique was developed for the final design.

Jan 1, 2003

The New Zealand Steel Ironsand Slurry Pipeline was successfully commissioned in February 1986. The project includes 18 km of high pressure, polyurethane lined buried pipe. McConnell Dowell Constructors Limited has developed a coupling which has allowed this pipeline to be fully welded. The design and development of the coupling and its application on this project is discussed.

Jan 1, 1986

Jan 1, 1962