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By Michel Dagbert

With the growing demand for energy, explora¬tion for uranium deposits has dramatically increased in the past few years. Since the early ages of uranium exploration, natural gamma ray logs has proved fast and convenient in locating and evaluating mineralized bodies. However, natural gamma ray logging is an indirect measure of the uranium content and in some circonstances, the radiometric signal can be 'altered in a very significant way. To check the presence of any distortion, statistical comparision of radiometric counts and chemical assay values for the same samples is generally performed. Of course in such studies, one inevitably mixes samples where the radiometric signal is really proportional to the uranium content and samples where this signal is influenced by many other sources or distorted before being recorded. Nevertheless, the average tendency leads to correction factors which are then applied to every radiometric reading in the deposit or portion of the deposit where the statistical comparison is made. To account for the "average" character of these correction factors, a parameter of uncertainty like a standard deviation of possible errors is associated to each corrected value. This parameter can be latter used in an ore reserve estimation when the weights assigned to samples should depend on the precision of their grade. The purpose of this paper is to present a new regression technique which can be used without any restrictive hypothesis like a normal or lognormal distribution. Different standard ways which can be used to statistically compare radiometric and chemical assay values for the same sample and to derive a correction factor for the latter will first be reviewed, after a general discussion of disequilibrium problems. The discussion and the examples will be restricted to the case of natural gamma ray logging in drill holes but the methods presented in this paper can also be applied to data from the radiometric probing of a working face or a truck load in an operating mine.

Jan 1, 1979

By G. Wang, L. R. Moore, Y. Xiong, J. Gu

"Quartz is the second most abundant mineral in the earth’s crust. Not only does quartz have many valuable industrial applications, it is also one of the most concentrated gangue minerals encountered in the processing of other minerals. Minerals such as hematite, apatite, calcite, feldspar, barite, and many more. Numerous applications of industrial minerals are sensitive to the hardness and abrasiveness encountered with quartz minerals, while other applications may lead to processing challenges for the end user. Therefore, process and chemistry optimization must be applied to ensure optimal grade is obtained for these valued industrial minerals. Extensive studies have been conducted in processing various industrial minerals, thus achieving a range of quality specifications, which entailed the application of ArrMaz’s CustoFloat and CustAmine collectors towards the separation of quartz from other minerals. INTRODUCTION Industrial minerals often have the misfortune of the gangue mineral being very similar in surface charge, and coordination properties, to that of the mineral of interest. An example is seen in phosphate beneficiation, when dolomite can be a gangue minerals (Table 1). Therefore, the development of processing reagents are quite complicated. Some minerals, like clays, may be washed away. However, most require the manipulation of the pH, in efforts to fine tune the system to the narrow difference in isoelectric points of the different minerals, as well as the knowledge, and resources that are necessary to exploit the differences to yield and an optimal grade/recovery. In some cases, the application of a depressant may be required, such as the phosphoric acid commonly applied to achieve the optimal balance of grade/recovery for phosphate from a mineral with elevated concentrations of dolomite (Wang, 2016), or the application of hydrofluoric acid to assist in producing feldspar product from a mineral rich in quartz (Heyes, 2012).ArrMaz's CustoFloat and CustAmine product lines have successfully been applied to the processing of industrial minerals for more than 50 years. Applications include, but not limited to phosphate, sand (glass, foundry & high purity quartz), clays (feldspar, kaolin, etc.), and many carbonaceous and sulfate minerals. The successes of these 50 years are largely due to ArrMaz's ability to tailor make the processing chemistries to fit the ever changing and declining mineral feed grade and variations in water quality (Moore, 2015; Moore, 2016). This technical knowledge of mineral processing is strongly complimented by the intimate service programs in place at many of the beneficiation plants."

Jan 1, 2018

By F. Sime, X. Wang, J. D. Miller, T. Akinseye, S. Assemi, L. Pan

Respirable coal mine dust (RCMD) is a complex mixture of carbonaceous and mineral particles with a variation in size and shape. Accumulation of RCMD in the lungs of underground coal miners results in severe respiratory damage and ultimately progressive pneumoconiosis known as the black lung disease. The occurrence of the black lung disease dropped to a low of 2.1% in 1990s but has increased to 3.1% in 2000s [1], prompting more research on coal mine dust mitigation. In addition to surveying the impact of new mining technologies on the size of generated dust and exposure measurement, a comprehensive characterization of physico-chemical properties of RCMD particles are essential for a better understanding of the adverse health effects of coal mine dust. Such vital factors include particle size, surface charge, morphology, composition, and agglomeration state. The respirable fraction of RCMD, has been designated as particles < 10 μm in diameter, and almost all studies on the RCMD toxicity have focused on micron-sized particles. However, recent toxicological studies have shown that nanoparticles (particles with one dimension less than 100 nm) can have a magnified toxicity compared to the larger particles with the same chemistry [2]. Nanoparticles have a much higher specific surface area compared to the same mass of larger particles and are thus more reactive. Most micron-size particles can be cleared by the body’s defense mechanism. However, inhaled nanoparticles can easily deposit in all regions of the respiratory tract and can translocate to vital organs. [2].

Mar 2, 2022

By K. KAKLIS, O. SAUBI, Z. Agioutantis, R. JAMISOLA

Machine learning in the form of artificial neural networks was applied to investigate whether specimen load evolution can be predicted as a function of acoustic emission (AE) signals in the case of three-point bending (TPB) marble specimens instrumented with piezoelectric sensors. The ultimate objective of this study is to develop a model that can quantify rock behavior under loading that can lead to rock-failure prediction in underground structures subjected to bending, such as roof failure in development or production openings.

Nov 1, 2022

By N. Zouridakis

Radon is an established lung carcinogen and remains the most important environmental radiation exposure. It was estimated that inhalation of radon and its short-lived decay products accounts on average for about one half of the effective dose equivalent from all natural sources of radiation. Radon contained in household water can transferred into room air as a result of agitation or heating. An indoor air concentration of 400 Bq/m3 is obtained if the radon concentration in household water is 4 kBq/L. A typical concentration of radon in ground water is about 1000 times lower than this concentration but sometime elevated concentrations of some kBq/L in ground water are reported. In this work a Liquid Scintillation counting system is used to obtain fast and accurate measurements of radon (222Rn) in water samples from Argolida, Greece.

Jan 1, 2007

By Michael C. Stanley

The set of discoveries for a mining district or camp is a reflection of the exploration history. In the western Abitibi greenstone belt of Ontario, future exploration can be guided by a study of statistical trends of known gold deposits. In this area simple trends indicate a strong decrease in the contained quantity of gold discovered through time. Much of this decrease is attributed not to falling mining grades but to smaller tonnages of ore. A plot of the largest discovery in each ten year time period suggests that deposit discoverability is following a size-biased sampling model. Cumulative ounces of discovered gold indicate that an asymptotic value has been reached where exploration is not expected to add significantly to known reserves. This is substantiated by a downward trend in the exploration success ratio of the number of new deposits discovered versus the number of new mineral prospects. The set of discovered deposits reflects a non-random sampling process where size- biased modeling suggests that the largest deposits will be discovered early in the exploration effort. It is the exceptionally large deposit contributing to the observed size-biased distribution. Although this pattern is observed for the western Abitibi the model is complicated by recent, large reserve additions that are attributed to the original discovery. There is present in this area a subtle learning process in exploration leading up to the largest discovery. For comparison a learning model was estimated using cumulative size of discovery per unit of time. This model yielded results consistent with the statistical trends and is thought to be a superior forecast of future discoveries in this region.

Jan 1, 1992

By Zhen-xing Diao, Feng Zhao, Ya-dong Xue

"Two important aspects of excavation performance of TBM are advance rate and cutter replacement/ring consumption, which is closed to the cost and construction duration of the project. To achieve this, a database of TBM parameters and the geological-geotechnical conditions during the excavation of Yinhanjiwei was compiled and analyzed. Relationships between different geological and TBM operational parameters were investigated. Results of analyzes show that there are qualitative correlation between Field Penetration Index (FPI) and rock geological parameters. And strong relationships between FPI and operational parameters are suggested. In this study, the cutter replacement and ring consumption were analyzed using statistical method for preliminary estimation in similar conditions. 1. ITRODUCTION Hard rock TBM is widely used in tunneling project nowadays because of its advantages to conventional drilling and blasting, especially in long tunnels. The biggest advantage is its high advance rate. However, rock conditions of tunnels are complicated. So TBM performance becomes a primary topic in tunneling engineering, which includes of rate of penetration, utilization, daily advancement, cutter consumption and so on. Many prediction models have been developed to estimate the TBM performance in the project planning phase. The most widely accepted and used models around the world are semi theoretical CSM model (Rostami and Ozdemir, 1993; Rostami, 1997) and the empirical NTNU model (Blindheim, 1979, Bruland, 1998).With increasing uses of TBMs in different ground conditions, an increasing number of researchers have developed new models in order to predict the performance of TBM more accurately in similar geological conditions.(Gong and Zhao, 2009; Hassanpour et al.,2009, 2010, 2011, 2014; Delisio et al., 2013; Delisio and Zhao, 2014)"

Jan 1, 2016

By Chris Ashton, Andreas Rädle, Taner Aydogmus

"The Contract C310 is part of the current biggest infrastructure project of Europe “Crossrail” which is a major new cross-London rail link project and comprises the construction of the North Woolwich Portal, Plumstead Portal and the twin tube Thames Tunnels with a length of approximately 2.6km. Two Mix-Shield TBMs (Diameter 7.12m) were driving through differing challenging ground conditions (Thanet Sand, Gravels, Flint and Chalk) below the ground water table. The two tunnels were underpassing several listed buildings, sensitive structures, operational railway tracks with low overburden and close to existing subway tunnels in an urban environment. Several additional measures as compensation grouting, micro piles and an intensive monitoring has been carried out to ensure a safe tunnelling process. PROJECT OVERVIEW CROSSRAIL Project Crossrail Crossrail is currently the biggest infrastructure project in Europe which has been developed to serve London and the southeast of England. The project includes the construction of twin-bore tunnels on a west-east alignment under central London and the upgrading of existing National Rail lines to the east and west of central London. The new rail track, as shown in Figure 1, starting in Shenfield/ Abbey Wood in the east of London and ending in Reading / Heathrow Airport in the west of London, includes the construction of nine central area stations, providing interchange with London Underground, National Rail and London Bus services, and the upgrading or renewal of existing stations outside central London.Altogether there will be 118km of new rail tracks, including 42km of tunnels and 40 train stations. After completion in 2018, Crossrail expects 200 million passengers per year (Tauriainen, Rädle, Ingram 2013)."

Jan 1, 2016

By P. Mousset-Jones, G. Danko

Rock thermophysical properties, i.e. heat conductivity and thermal diffusivity, were obtained for reference values at the Waldo Test Mine for mine fire simulation purposes. An in situ measurement method was chosen since it could include the effect of rock fractures. The REKA method (Rapid Evaluation of k and alpha) was used because it can measure conductivity (k) and diffusivity (alpha) simultaneously within an eight-hour measurement period. A total of six measurements were taken in three different holes, and at two different depths from the collar of the hole. Each measurement provided an averaged conductivity and diffusivity for a volume of rock of approximately one cubic meter. The boreholes were driven into the upper and lower limestone, two at right angles to and one parallel to, the stratification of the rock. Significant representative conductivity and diffusivity values were obtained for the whole mine by averaging the six measurement results. The thermal properties for the band of shale in between the two limestones were not measured in situ, but only in the laboratory. Problems were encountered in the evaluation because of unexpected heat conduction on one side of the symmetrically built probe. A modification was made to the previously developed evaluation method together with further testing and correction, before the final results were obtained. As expected, the in situ and lab- oratory measured values of k and alpha compared favorably, since the in situ rock was dry and relatively unstressed.

Jan 1, 1989

By C. O. Brawner

INTRODUCTION My first major involvement on a rock mine slope stability project was in 1966 after I had become a principal of Golder Brawner & Associates in Vancouver, Canada. I received a request from Kennecott to evaluate two serious rock slope failures adjacent to the concentrator on their British Columbia molybdenum property near Alice Arm, BC, which was under construction. A rock slope up to 200 ft* high had been excavated at a design angle of 700. The inspection indicated that several large blocks of about 1000 cu yd each had failed on steeply inclined joint surfaces. Stability was reduced by extensive seepage caused by heavy rainfall. In addition, considerable overbreak had occurred, indicating excessive blasting had been used to excavate the slope. A program was developed to rock bolt potentially unstable blocks that could slide on dipping discontinuities. Some rock was scaled back to the inclined joints, and drain holes were drilled to reduce water pressures. The project was completed successfully and within reasonable economics. As a result of this success, enquiries were received regarding other mining projects. This indicated the potential demand for rock slope engineering. As a result, I took one month off to meet and discuss rock mechanics and slope stability with various people internationally. These included D. Coates in Canada, E. Hoek in England, K. John and L. Mueller in Germany, M. Rocha in Portugal, and the US Bureau of Mines in Denver, CO. Early misconceptions Based on involvement in projects during the next few years, it was concluded that there were a considerable number of misconceptions that existed among some geologists and mining engineers dealing with surface rock mechanics. Some of these included: • Water is a lubricant. This is incorrect. Water reduces the shear strength along discontinuities due to buoyancy, which reduces frictional strength. It also reduces the cohesion of clayey-type rocks. • The optimum pit slope angle in rock is 45°. The optimum slope angle for safety and economics is variable and is influenced particularly by structural geology, water pressures, mine blasting practices, and the depth and degree of weathering. • The flattest angle for slope stability is dictated by the angle of repose of broken rock, about 370. Where clayey-type rocks or clayey infill in discontinuities exists, failure can occur at much flatter angles, requiring flatter slopes or artificial stabilization. • Uniaxial and triaxial tests provide the necessary shear strength parameters to design rock slopes. Most failures in rock slopes are controlled by directional discontinuities. Therefore, the direct shear test is the correct test to evaluate strength parameters for most problems.

Jan 1, 1987

By Ruben Piqueras, Juan Luis Magro, Jorge Vázquez, Santiago Martínez, Xavier Manjarín

The Parallel Thimble Shoal Tunnel project involves the construction of a bored tunnel under Thimble Shoal Channel in Chesapeake Bay (VA), between two artificial islands and parallel to the existing tube tunnel, built in the sixties. It will be the first transportation tunnel constructed in the Mid-Atlantic region using a Tunnel Boring Machine (TBM), a 44-foot-diameter Earth Pressure Balance (EPB) named "Chessie," manufactured by Herrenknecht, and which was assembled at the CBBT's southernmost island, with extremely limited room, live adjacent traffic, and difficult access. "Chessie" was successfully launched in February 2023 and this paper describes this complex and challenging process.

Jun 23, 2024

By Alan R. Grant

Interpretation of presently available geological information indicates that most of the periods of significant metal deposition in the Washington Cascades Range are, at least in part, genetically related to late Cretaceous -Tertiary intrusive episodes. Chemically, the most favorable environment for base metal deposition is high in potassium. Characterizing the advanced stages of these chemical alteration conditions are the silicate mineral assemblages orthoclase and/or secondary biotite. Wall rock alteration includes both deuteric and hydrothermal processes, the intensity of which primarily depends upon the degree of fracturing in the country rock prior to the introduction of secondary material. Broadly speaking, the primary physical controls for the distribution and concentration of sulfides appear to be a series of structural couples involving both northwest (paralleling regional trends) and northeast--striking systems. Meaningful base metal exploration in the Washington Cascades demands a basic understanding of the various geologic factors related to the distribution of the sulfide deposits. Any geologist contemplating Cascade work should be well grounded in the fundamental concepts of petrology and structure.as these constitute two of his most beneficial aids. The acquisition of the detailed data necessary for this understanding may seem a bit academic, yet it has been demonstrated in numerous instances that a fair economic appraisal of a particular property or mining district depends primarily upon the ability of the geologist to recognize the subtle environmental differences which could lead to the discovery of a major ore deposit.

Jan 1, 1971

By R. Hogg, T. F. Dumm

Procedures for particle size analysis on respirable dust from coal mines have been evaluated. Using respirable dusts dispersed in a laboratory dust chamber, size distributions measured using cascade impactors have been com- pared with the results of a variety of laboratory sizing methods performed on samples collected on filters placed side-by-side with the impactors. The laboratory techniques included centrifugal sedimentation, laser diffraction/scattering and automatic particle counting. The general agreement among the various methods was very good, with systematic differences which can be attributed to the different definitions of size used. Simple conversion factors have been obtained which can be used to transform the laboratory data to equivalent aerodynamic sizes. Similar comparisons have been made on samples collected in underground coal mines. Again, the results are in quite good agreement although small discrepancies were observed in some cases. These have been attributed to some degree of agglomeration in the airborne dust, leading to slightly coarser apparent distributions in the impactor samples.

Jan 1, 1987

By Moussa Wone, William Levy, Christopher Caruso, Zachary Spera, Thomas Hennings, Richard Stacy Kinchen, PE Joel Kantola

"Owners constructing new combined sewer overflow (CSO) systems increasingly seek to have project design lives of 100 or more years in response to the growing size, complexity, and cost to construct and operate these systems. However, a codified and universally accepted approach to achieving this goal in the United States does not currently exist since service life prediction is a relatively new technical field. This paper discusses how the 100-year design life requirement was met for the design of tunnels, drop shafts, and diversion structures in the DC Clean Rivers Program (DCCRP). The authors identify some commonly referenced publications, present the testing framework used by the program manager to characterize the CSOs, review the design criteria used to guide the 100-year design life development, and establish guidelines to be considered by program managers and designers when implementing similar extended design life requirements in other CSO control programs.INTRODUCTIONLike many older cities in the United States, the sewer system in the District of Columbia consists of both combined sewers and separate sanitary sewers. When the capacity of a combined sewer is exceeded during storm events, the excess flow, which is a mixture of sewage and storm water runoff, is discharged to the District’s receiving water bodies (Anacostia River, Potomac River, and Rock Creek) and tributaries through outfall structures. This excess discharge during storm events is called a combined sewer overflow or CSO. A total of 53 CSO outfalls for the combined sewer system are listed in DC Water’s National Pollutant Discharge Elimination System (NPDES) Permit issued by the U.S. Environmental Protection Agency (EPA). The DC Clean Rivers Program (DCCRP) will reduce the number of CSO outfalls into the Potomac and Anacostia Rivers and decrease flooding in DC neighborhoods during extreme rain events by capturing, storing, and conveying diverted CSOs to the Blue Plains Advanced Wastewater Treatment Plant."

Jan 1, 2016

By C. J. Webb

Column experiments were performed to determine the ability of Madison aquifer material to adsorb arsenic and other constituents in a heavily mined watershed of the Black Hills in western South Dakota. The Madison aquifer is a karstic dolomite and limestone reservoir that is exposed on the flanks of the Black Hills. Streams that cross the Madison in the eastern Black Hills typically lose all their flow to the aquifer at sinkholes. In this work, Madison aquifer material was obtained for loading of six-inch diameter columns, which were backfilled with Madison aquifer water. Stream water then was allowed to displace the aquifer water during column testing in order to simulate mixing of the two waters at sinkholes and to determined adsorption of arsenic and other dissolved constituents. Initial results show that some adsorption of arsenic occurred when compared to more conservative tracers such as nitrate.

Jan 1, 1999

By Thomas W. Traylor

Today, in Detroit, Michigan, a 14 ft. 6 in. diameter soft ground tunnel is being mined at penetration rates limited only by the logistics of liner handling and spoil removal. Soil conditions are highly variable and include clays ranging from very plastic to very hard, gravels, sands, silts and boulders. The permeable soils contain high concentrations of methane gas, compressed by groundwater levels some 40 ft. above tunnel invert. Despite these adverse conditions, mining crews frequently complete their 70 ft. production quota in six hours and go home. In one 4000 ft. reach of tunnel, progress averaged 68.9 ft. per mining shift. This paper has been written to explain this extraordinary accomplishment, and to demonstrate that truly continuous rapid excavation in difficult grounds is now limited by factors other than the excavation process itself. BACKGROUND The Detroit metropolitan area has a long and interesting history of soft ground tunneling. From 1949 to 1968 the city of Detroit alone constructed some 75 miles of soft ground tunnel. During this period the development and common usage of rotary or "wheel-type" soft ground tunneling machines was pioneered in the Detroit area. These machines are designed for, and were successful in, the cohesive or clayed soils that predominate the downtown Detroit geology.

Jan 1, 1997

By James G. Donovan, Mario G. Karfakis

A large percentage of Southern Appalachian coal reserves are located in seams less than 36" thick. As thicker and currently more mineable deposits are exhausted, methods of underground thin-seam extraction must be developed. Past experience with highwall mining of thin-seam coal has indicated that recovery rates tend to be lower than in conventional operations. It is suspected that this will also apply to underground thin-seam mining, regardless of proposed technology or mining method. Backfilling is one alternative for thin-seam coal mining; although backfill has been used extensively in hard rock mining its use in coal mining has been limited. The ability of backfill to provide additional ground support may enhance coal recovery by allowing for the design of undersized pillars. Backfill is capable of providing additional ground support by restricting lateral deformation of surrounding coal pillars and roof. This additional support can result in significant increases in recovery from thin-seam coal deposits. However, the overall feasibility of backfill is dependent on the in situ behavior of the fill material, the properties of the fill, the effects of the filling method on the total mining operation, and the cost of filling per extra ton of coal recovered.

Jan 1, 2001

By M. K. Gangal, E. D. Dainty

The paper describes the use of portable aerosol monitors in determining real-time concentrations of diesel soot and respirable total dust in dieselized mines. The field studies were conducted in a simulated diesel environment in the laboratory where no other type of dust was present, and in four underground mines with multi-diesel machine operations. Two packages for the real-time monitoring of diesel soot were prepared which included two types of aerosol monitors: a Miniram, model PDM-3, and a Sibata, model PDS-1. These monitors utilize the principle of light-scattering to measure the airborne mass concentration in the environment. The monitoring device results were compared against the Time-Weighted-Average (TWA) values produced by the gravimetric filter sampling method, permitting calibration factors to be determined for each field test. Both instrument packages provided comparable results. The instrument calibration factors varied for different tests, which may be due to different material composition, particle size distribution, density and shape of the aerosols. This approach for real-time determination of diesel soot is found to be simple, inexpensive and easy to use. More field tests for diesel soot determination and further research on size distribution of particulates in dieselized mines are required.

Jan 1, 1989

By M. Moats

Copper electrowinning operations have dramatically improved their ability to produce high quality copper at low costs over the past several decades. Even so, some fundamental knowledge is still lacking that could allow operations to run even more efficiently. For example, a rule of thumb exists that estimates a current efficiency loss of 2-3% per gram per liter of iron in the electrolyte. While several laboratory studies have been performed that demonstrate this rule of thumb is likely true, no definitive relationship exists. In this paper, the first steps in developing a definitive relationship are presented. The effective diffusivity of ferric ions in synthetic copper electrowinning solutions was measured using chronoamperometry and the Cottrell equation. The effective diffusivity of ferric ion was determined as a function of electrolyte concentration and temperature. Synthetic electrolytes were then used in laboratory-scaled copper electrowinning experiments, where relationships between current efficiency and solution composition were found to exist under stagnant conditions. Key words: Copper electrowinning, Current efficiency, Chronoamperometry, Ferric ions

Jan 1, 2009

By Clayton Vernon Deutsch, Marcel Antônio Arcari Bassani, João Felipe Coimbra Leite Costa, Vanessa Cerqueira Koppe, Pedro Henrique Alves Campos

Traditional linear approaches oversimplify the complexities of ore blending. Adopting nonlinear blending models in mining and mineral processing is critical to enhancing prediction accuracy and allowing optimization regarding nonadditive variables, such as metallurgical recovery. This study implements a simulated annealing algorithm in short-term mine planning that seeks to optimize the metal recovery by considering how to blend the ore in the mine better. Two nonlinear metallurgical recovery models are used as inputs to the algorithm to represent synergistic and antagonistic blending. The results of the case study demonstrate that the optimized schedule exhibits improvements in both blending behaviors when contrasted with conventional linear-based scheduling plans.

Jan 1, 2025