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By M. E. Kuchta

LKAB's Kiruna mine, located above the Arctic Circle in northern Sweden, is one of the world's largest underground mines, and it is one of the most modern. The Kiruna orebody is a high-grade magnetite containing about 80% low-phosphorous iron ore and about 20% high-phosphorous iron ore in situ. The mining method used is large-scale sublevel caving. Due to the blending of high-phosphorous ore with low-phosphorous ore during the extraction process, only about 20% of the run-of-mine ore can be used for the mine's low-phosphorous product. The blending process is highly irregular and difficult for the mine-planning personnel to predict. An algorithm was developed that uses principles of gravity flow to predict the run-of-mine phosphorous grades from the in situ geologic block model. The model can be used for both long- and short-term predictions.

Jan 1, 2003

By Ratnakar Singh, Raj Kishore, Kisor Kumar Sahu, Ranjeet Kumar Singh, Ganesh Chalavadi

The Falcon concentrator is capable of separating minerals in fine size classes based on their differential density. Separation of mineral particles depends upon the fluid flow characteristics and relative movement of particles in a fluid. In the present study, a fluid flow characteristic inside the Falcon concentrator was established through experimentation and modeling. The Falcon concentrator has two fluid entry points: (a) Fluid entering through gravity assisted feeding system and (b) Fluid entering through the fluidized hole on the concentrator wall. In order to identify the role of fluid entering the concentrator, a tracer was injected into the system. As per the tracer based experimentation, it was established that fluid entering through the gravity based feeding system is responsible for thin flowing film formation in the stratification zone where particles are stratified based on their relative density. The momentum balance and continuity equations were simplified for a high centrifugal force field, and the fluid velocity profile was estimated inside the thin flowing film. Estimated fluid flow profiles will help to simulate the particle trajectories inside the Falcon concentrator. The influence of rotational speed, fluid flow rate, and cone angle on the fluid velocity profile were investigated. Fluid thickness over the concentrator wall is also estimated, and it is typically of the order of ~150–200 μm.

By G. C. Allen

Selective flocculation is used for the purification of clay minerals. Here we present data from a surface spectroscopic investigation into the polyacrylamides mediated selective flocculation of kaolin from an impure matrix. Use of X-ray photoelectron spectroscopy (XPS) was shown to offer a useful approach for investigating the observed selective separations. In particular, a new small area XPS technique was used to characterize, in situ, the differential competitive, f1occulant adsorption onto mixed kaolin/gangue systems.

Jan 1, 1998

By B. Devulapalli

A mathematical model of the industrial hydrocyclone based on fluid dynamics is a better alternative to the currently existing empirical models. The swirling-flow velocities are determined by solving the Navier-Stokes equations with an appropriate turbulence model. The solution of the momentum-balance equations yields the flow field inside the hydrocyclone which determines the particle trajectories, and subsequently the classification curve. The essence of the model is that the physical dimensions of the hydrocyclone and the slurry characteristics can be incorporated, and the influence of these parameters reflects on the flow predictions. The predicted tangential and axial velocities in a 250-mm hydrocyclone are in good agreement with the laser-Doppler velocimetry measurements. Finally, the predicted classification curves show good agreement with experimental data measured on a KREBS Dl0B hydrocyclone.

Jan 1, 1993

By Zong-Xian Zhang, Charlie C. Li

It has been observed that the rock debris of a strain burst event are often in the mode of tensile fracture. Seismic waves could create tensile fractures in the material nearby reflecting surfaces, such as at the boundary of the fracture zone and the rock surface of an underground space. The fractured rock could be ejected to the space when the seismic waves are powerful enough. The average ejection velocity of the ejected rock is a measure of the magnitude of a burst event. The ejection velocity is directly associated with the released energy from the seismic waves and with the strain energy stored in the rock prior to the burst. In some cases, the seismic wave induced tensile fracture and the energy conversion occur in successive moments during bursting. In this paper, tensile fracture caused by seismic waves is investigated through an 1D model. The relationship of the average ejection velocity of the ejected rock in a rockburst event is analytically established with the energy of the seismic waves and the strain energy stored in the rock.

Apr 26, 2022

By M. L. W. Tuttle, B. R. Berger

Our study focuses on the geology, hydrology, and geochemistry of a variety of molybdenum (Mo) porphyry systems. The systems are either high fluorine, granite, Climax-type, systems (e.g. Mount Emmons/Redwell Mo deposit, Colorado and Questa Mo deposit, New Mexico) or low fluorine granodiorite systems (e.g. Buckingham Stockwork Mo deposit, Battle Mountain, Nevada and Cannivan Gulch Mo deposit, Montana). The water quality of streams, natural springs, mine discharge, and ground water from drill holes were assessed in the region of these deposits. The ultimate goal of our study is to understand the environ-mental behavior of these Mo porphyry systems in the context of geologic setting, hydrologic regime, and climate.

Jan 1, 2004

By Christopher Laughton, Michael P. Bruen

At Fermilab, a 4000-ft long underground complex has recently been constructed for a high-energy physics experiment. The complex is sited up to 350 ft, below grade principally in bedrock. The rock excavations were mined by TBM and drill and blast methods and supported by a combination of rock bolts, dowels and shotcrete. Water control was achieved using a combination of pre- and post-excavation grouting, drainage systems, drip shielding and air desiccation measures.

Jan 1, 2003

By Jon Y. Kaneshiro, John S. Griffith, Anthony F. Stirbys, Mauricio Andrade

This paper presents an overview of the New Mississippi Tunnel Outfall for the Transportation Expansion Project (T-REX). The Outfall conveys highway and other urban drainage to the South Platte River as well as provides long needed relief from flooding problems in the southeastern portion of the Interstate 25 highway corridor. The Outfall tunnel incorporates a one-pass precast concrete segmented liner to convey storm water under I-25 then under Mississippi Avenue to the river. The Outfall crosses both the existing I-25 as well as the future improvements including under the Light Rail Transit, a new bridge abutment, widened lanes, and new retaining walls. The Outfall also crosses adjacent to several buildings and five bridges, under major traffic and utility intersections, and through difficult geology.

Jan 1, 2003

By R. K. Mehta, M. G. Bersch

Characterization of an ore or mill product is routinely performed by time consuming and tedious chemical analyses, sink-float separations, etc. Additionally, these types of tests do not provide data concerning the interrelations and interlocking of the mineral constituents. This paper discusses some of the applications and capabilities of the Minerals and Material Science Research Center at The University of Alabama. Back-scattered electron images of coal, oil shale, complex suldfide, and tantalium ores were acquired using a JEOL 8600 electron microprobe with a NORAN (formerly Tracor Northern] 8500 image analysis system. Methods of analysis and typical results are discussed.

Jan 1, 1992

By J. D. Miller

Physical separation of bitumen from low-grade Utah tar sand deposits containing a relatively high viscosity bitumen phase (Sunnyside and Tar Sand Triangle deposits) has been accomplished by traditional size reduction and froth flotation techniques. At appropriate experimental conditions more than 90 percent of the bitumen can be recovered in a concentrate, containing more than 20 weight percent bitumen, which should be a suitable feed material for subsequent hot water or thermal processing. The efficiency of bitumen recovery depends on the extent of size reduction, promoter and dispersant addition. Rejection of greater than 60 percent of the sand at ambient temperature and ease of water removal from the concentrate make such a process strategy both energy and cost effective. The energy required to achieve effective separation by the ambient temperature process is significantly less than the energy required for the recently developed hot water process. The flotation behavior of the tar sand has been analysed with respect to flotation pH, contact angle measurements and the apparent iso- electric point of the bitumen. The best flotation response at pH 7.8 to 9.0 can be correlated with the maximum in contact angle developed between the air bubble and bitumen surface and with the apparent iso-electric point of the bitumen (-pH 8.0).

Jan 1, 1981

By Bruce H. Mason

The exploration for a commercially acceptable deposit of limestone is consid¬ered by many to be a relatively easy task; however, trying to locate a zone of high calcium limestone of economic thickness within a formation, which outcrops only in a narrow band varying in width from a quarter mile to ten miles, adds considerably to the normal problems experienced during an exploration program. The existence of varying glacial and karst features in the outcrop area intensified the problems encountered and complicated the interpretation of the economic value of the deposit. This paper highlights a recently completed five year exploration program during which approximately 3,900 acres of ground in seven civil townships were evaluated as potential sources of high-calcium limestone. Details are given with respect to the final site chosen and the methods used in determining the suitability of the site. This site exhibited many karat features and several methods were utilized to determine the effect of these features on the gross characteristics of the deposit. Aerial photography for both mapping and interpretation were utilized. Black and white panchromatic photography, black and white infrared and color infrared photography were flown. Resistivity, diamond core drilling and close-interval angering were used to supplement the information obtained from the aerial photography.

Jan 1, 1974

By S. C. Suboleski

In a high risk venture such as mining where capital is committed and contracts are signed on the minimum of information, decisions are based primarily on production forecasts derived through consideration of such factors as management-labor relations, mining practice, variations in physical conditions and the equipment applied. Among these factors, the physical conditions offer the least opportunity for control and, due to the wide range of mining conditions that may be experienced, little effort has been made to develop objective methods for measuring their effects on mine out- put. The aim of this paper is to demonstrate a method for assessing these relationships that can be applied under a wide range of conditions both in new mines and in working sections where there is a need to determine the impact of proposed operational modifications. psing empirical data from active underground mines, a mathematical model was developed to derive a set of regression equations for predicting production as a function of mining conditions

Jan 1, 1980

By John B. Gustavson

Gold was first discovered in Alabama in 1830. Before a decade had passed more than 20,000 people were employed in the various gold districts scattered across east-central Alabama. By 1849 most of the presently defined gold districts were known with such towns as Arbacoochee, Chulafinnee, Goldville, Pinetucky, and Idaho being the principal mining camps. The California gold rush of 1849 signaled the end of intensive prospecting in the Alabama Piedmont for the precious metal. Reactivation of many of the old gold districts has been attempted several times since 1849. Significant activity and development took place between 1874 and 1880, 1888 and 1916, and 1929 and 1936. Locally, some of the development met with moderate succes. The last productive gold mine in Alabama ceased production in 1935. The sharp increase in gold prices since 1973 has caused renewed interest in the potential values of gold of the Alabama gold districts. Most of the gold workings have been abandoned for nearly 75 years and are for the most part inaccessible for convential property evaluation. The early gold miners and prospectors in Alabama were more intent upon finding and mining the valuable metal than in recording their activities for future generations. No matter how interesting or historically significant these records might have been the miners kept no records and left behind them few maps as clues to their activities. Inasmuch as most of the old gold districts have been extensively mined and prospected during the past 150 years, there is very little chance of finding large deposits through conventional outcrop prospecting methods. Similarly, the present geologic knowledge of the various districts is insufficient to launch successful exploration programs looking for large blind lode deposits in new locations within the general gold bearing region.

Jan 1, 1975

By M. E. Buzon, M. E. Gunter, B. D. McNamee

A Google search on talc asbestos yields more than 500,000 hits due to the growing number of civil lawsuits in this area. Historically, the litigation was centered on amphibole-containing industrial talc. There was no debate these talcs contained amphiboles, but the issue was the definition of asbestos and whether the amphiboles had an asbestiform habit. Ultramafic-hosted talcs, however, are formed in such a way as to not favor the formation of amphiboles in the talc, but they can occur in the surrounding black-wall. In these deposits, the serpentinite host rock is in direct contact with the talc, therefore, allegations can be made that non-asbestiform amphiboles or non-regulated serpentine group minerals can occur in the final products. We analyzed talcs from both metamorphosed carbonate- and ultramafic-hosted talc deposits using polarized light microscopy (PLM), scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS), electron microprobe (EPMA) with wavelengthdispersive spectroscopy (WDS), transmission electron microscopy (TEM) with EDS, and powder X-ray diffraction (XRD). Compositions of minerals determined by EDS alone are not sufficient to confidently identify asbestos, despite common practices by some researchers. We emphasize, using both historical samples, and analyses of currently contested minerals, the importance of determining both the structure and composition of a mineral, as well as defining its morphology, before concluding whether it is asbestos.

Jan 1, 2018

By A. Palit, M. K. Mohanty

This investigation has concentrated on optimizing the newly developed Pansep linear screen and developing empirical models to predict the screening performance. Most empirical models developed in the past to predict the performance for industrial screens are suitable for the vibratory screens. Understandably, these models are deficient in predicting the performance of linear screens due to the difference in their operating principle. Thus, the main objective of this study has been to develop empirical models suitable for linear screens to predict the partition coefficient for a given size fraction as a function of the aperture size. The inadequacy of the conventional model equation originally developed for vibratory screen has been demonstrated and a modified equation developed to predict the partition coefficient as a function of the normalized mean particle size (d/d50c). In addition, new model equations have been developed for linear screens to predict the screening efficiency as a function of the separation size(d50) and to predict the separation size as a function of the screen aperture. It is believed that these model equations will be useful for the plant operators in selecting the mesh panels of correct aperture size and in predicting the product size distribution based on the selected aperture size.

Jan 1, 2003

By Peter F. Howard

The lower Middle Cambrian phosphorite deposits of the Georgina Basin shown in Figure 1 were found in the period 1966-1968 by three companies, namely, International Minerals and Chemical Corporation, Continental Oil Corporation and Broken Hill South Limited. Of these deposits the significant ones are Duchess, Sherrin Creek, D Tree, Lady Annie, Lady Jane, and Wonarah which together aggregate several billion tons reserves of phosphate. Due to the economic factors of freight costs to the coast and softening of the world market price for rock phosphate, none of them is in production, nor is any in the development stage. This paper reviews the historical background to the discovery of these deposits and then deals principally with the discovery of non-outcropping phosphorites in the Barkly Tablelands of Northern Territory by the interpretation of gamma radiation logs of abandoned water bores.

Jan 1, 1971

By J. C. Ashby

Electric utility response to certain amendments of the Clean Air Act has resulted in a production of several types of alkaline coal combustion byproducts. Alkaline combustion byproducts are gaining increasing usage for acid mine drainage mitigation as research leads to a better understanding of their beneficial applications. Since January of 1997, Mettiki Coal Corporation has been injecting alkaline flue gas desulfurization material from Virginia Power's Mt. Storm Unit #3 wet limestone scrubber into abandoned portions of the active Mettiki mine. This paper provides an overview of the key design, transportation, regulatory, and environmental issues faced in the project.

Jan 1, 1998

By R. M. Enick

A novel liquid-liquid separation for the recovery of free or liberated gold from mixtures of fine particles was evaluated. The separation, conducted at ambient temperature and a pressure of about 1000 psi a, was based on the difference in wettability of precious metals and minerals. Contact angle results indicated that in the presence of water and liquid CO2, gold, platinum and silver had intermediate wettability. Minerals such as quartz and magnetite, however, were hydrophilic. Therefore fine gold particles. -325 mesh, that were mixed with water and liquid CO2 dispersed in the CO2 or agglomerated at the H2O-CO2 interface while the minerals tended to remain in the aqueous phase. Best results were obtained when these fine gold particles were liberated, were not agglomerated in slimes, were not adhering to minerals, and were not coated with minerals.

Jan 1, 1998

By G. Babut

The restructuring of mining operations in Valea Jiului coal basin imposed by the transation to the market economy calls for an increased coal production. Under the circumstances, the role of drainage networks grows ever more important. The paper describes an original mathematical model and software developed on its basis, with enables the ventilation engineer to assess the configurations of different systems, as well as to test their reliability and prognose their future performance before conceiving another methane drainage system or changing the existing one. The paper also includes the underlying principles of an optimization program for methane drainage networks, which will enable the detection of the optimal methane drainage system, both from a technical and an economic point of view.

Jan 1, 1996

By Paul J. Smith, Eudomar A. Silva, Quang D. Tran, J. Milton Brooks

The Dallas Mill Creek Drainage Relief Tunnel is an 8.04 km (5 mile) tunnel that will provide 100-year flood protection for impacted neighborhoods in the east Dallas area. “Big Tex” is a main beam gripper TBM capable of changing diameters in mid-tunnel to excavate 2.83 km (9,290 ft) of 11.45 m (37.58 ft) diameter tunnel and 5.21 km (17,095 LF) of 9.93 m (32.58 ft) diameter tunnel. Construction began in April 2018 and is anticipated to be completed in 2024. This paper will discuss the challenges and lessons learned during assembly and re-assembly, start-up and mining with “Big Tex.”

Jun 13, 2021