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By K. Johnson, B. Schiffer

Demonstrating aquifer restoration is an essential component of regulatory approval needed to mine uranium, copper, and other minerals by in-situ recovery (ISR). A PHREEQC geochemical model provided a useful means of forecasting the time for restoration and predicting future groundwater quality following low pH mining at Strata Energy’s Ross ISR Project in northeast Wyoming. The model simulated groundwater quality at three phases of the process: at the end of mining; during restoration; and post- restoration. The model utilized the one-dimensional reactive transport and dual porosity features of PHREEQC. Mineral surface ion-exchange, dissolution/precipitation reactions, and adsorption processes were simulated to estimate water quality as the pH was shifted from circumneutral to acidic during mining and back to neutral during restoration. The model results showed that cost-effective management of mine water could meet regulatory requirements. Additionally, the model was used to interpret results from a field trial and inform operational decisions. The predictive approach and geochemical understanding developed have application in assessing aquifer restoration for other ISR projects.

Mar 2, 2022

By Werner Stahl, Karsten Keller

Vibration screens are commonly used not only in classifying bulk material but also in dewatering it. The lack of a comprehensive physical theory of dewatering often leads to difficulties in the design and operation of the vibration screens. Firstly, the dewatering of bulk material will be shown, based on a physical model. Because of the oscillatory motion of the liquid in the bulk, the inertial force of the accelerated liquid and the dripping of water out of the bulk or screen must be taken into special consideration. The physical model put forward shows the effect of the various operations parameters of dewatering screens. The comparison between dewatering theory and practice will be shown by measurements using coal, limestone, etc. Dewatering measurements, which have been conducted on a vibration screen, demonstrate that different vibration frequencies and rates of acceleration lead to different residual moistures. Finally, the possibilities of improving vibration dewatering will be described.

Jan 1, 1995

By Lawrence Neal Post

Introduction Synthetic soda ash production began to decline in the late 1930s. This was due to high operating costs and waste disposal problems. Since soda ash was used as a major component in manufacturing glass, an alternate method of producing that chemical was necessary. A process to produce soda ash from trona was developed by FMC Wyoming Corp.'s predecessor, as well as an economical way to obtain trona. Existing trona operations are located about 40 km (25 miles) west of Green River, WY. Five operators presently mine trona in this area. FMC's property has 153 km2 (59 sq miles) leased. Its eight shafts reach 488 m (1600 ft) deep to the uniform trona deposit. The seam ranges in thickness from 2.4 to 3.6 m (8 to 12 ft). History Egyptian tombs, dating from 4000 to 3000 BC, contained mummies preserved by an embalming process using soda ash. For many years, soda ash was produced by burning marine plants, then dissolving the soluble material (sodium carbonate) from the ashes. The name soda ash is derived from this method of production. In 1791, Nicola LeBlanc developed black ash, or salt cake, from salt, sulfuric acid, coal, and limestone. This process remained in use until 1863, when Ernest Solvay developed a method for producing soda ash from salt, coke, and limestone with ammonia as a catalyst. This Solvay process was widely used. And, in the 1930s, there were 17 plants in the US alone. High plant operating costs and waste disposal problems, however, necessitated finding an alternative to the Solvay process.

Jan 10, 1985

By S. Kemball-Cook, D. Heinze, A. Kornberg, M. Harmon

Climate change presents risks to mine infrastructure, operations and long-term obligations to protect environmental conditions. Management strategies and design of infrastructure and containment systems based on past or current climate conditions may be inadequate in the future if changes in climate are not taken into account in planning for mine operations, decommissioning, closure and post-closure. Data-driven assessments using climate model projections of the future can be used to quantify: • Changes in site-specific risks to mine structures, access, containment facilities, operations and staff safety. • Changes in vegetation and water balance/chemistry, and potential for acid mine drainage, erosion and design failure. Climate- and weather-related risks are a serious threat to the mining industry, but risk transfer solutions can alleviate these vulnerabilities. Mining companies can protect themselves through bespoke solutions which provide operators, investors and buyers with protection against weather-related disruptions to operations by hedging to smooth revenues. Using risk transfer structures to mitigate climate risks is a mechanism that is available to all types of mining operations world-wide. In this paper, we describe methods for evaluating site-specific climate change impacts and developing risk transfer solutions to mitigate their effects. EVALUATING MINE RISKS FROM CLIMATE CHANGE The best available tool for understanding potential future changes to the earth’s climate system are global climate models (GCMs) (IPCC, 2014). GCMs are computer simulations of the climate system which include the atmosphere, ocean, land surface, cryosphere and biosphere. Because of the computational demands of running a global model for many decades, the spatial resolutions of the GCM grids are necessarily coarse, typically on the order of 100-300 km. GCM data are therefore suitable for evaluating future physical risks on global or continental scales, but may not be appropriate for evaluating location-specific risks (e.g. Kotamarthi et al., 2016). For site-specific, quantitative physical risk assessment, GCM projection data are “downscaled” or adapted for use at the local level using statistical techniques together with observed data (statistical downscaling) or using high-resolution regional climate models (RCMs) that focus on a single geographic region and have spatial resolutions of 10-50 km (dynamical downscaling). Downscaling bridges the gap between the GCM scale and regional/local scale. Through the downscaling process, new information is added to the GCM output from observations and/or RCMs, resulting in patterns for weather variables that are more consistent with local terrain and weather influences. Downscaled climate change projections for the mine site are selected considering mine location and geography, the availability of local observations, and the performance of the downscaling method and global/regional models used to develop the projection in simulating the variable under study. Where possible, we use projections from an ensemble of global and regional model runs spanning a range of future greenhouse gas (GHG) scenarios.

Jan 1, 2019

By Y. C. Kim, W. L. Meyer, W. Cai

Although the first published optimum pit limit design algorithm by Lerchs-Grossmann dates back to 1965, the majority of the open-pit mines in the US has not as yet adopted such a rigorous optimization algorithm. Instead, the floating cone approach initially developed by Kennecott Copper in 1961 is still used today for various reasons. However, shortcomings with the floating cone algorithm, particularly for precious metal deposits with erratic mineral distributions, have provided a renewed interest in optimizing algorithms. This paper compares the performance of the floating cone algorithm with the rigorous optimization algorithm of the Lerchs-Grossman's graph theory and the newly developed maximum network flow algorithm by Hanson (1986). The maximum flow algorithm is a modified version of the logic as initially advocated by Johnson in 1968. Comparisons are made for three different deposits in terms of the total profits generated and the computation times involved. The results of the comparison show that both algorithms produced higher total profitability pits than the floating cone in all three deposits, although the increase in profits never exceeded 1 % of the base design obtained using the floating cone. Between the graph theory and maximum flow, graph theory produced consistently higher profits. The current version of maximum flow, however, cannot be modified to produce the optimum pit. Nevertheless, the authors prefer the maximum flow over the graph theory, simply because it is easy to program as well as to explain.

Jan 1, 1987

By Kostas Fytas

A computer package has been developed which is capable of evaluating alternative production schedules (long and short range) of an open pit mine once the ultimate pit limits have been defined. The model user can choose the best alternative according to cash flow considerations and the particular mining conditions. The package involves a combination of simulation for long range production scheduling and linear programming for short range scheduling. The simulation model based on an iterative technique, maximizes the profits within each long scheduling period (eg. year or sixth month period), and at the same time defers stripping as long as possible. A minimum exposed ore quantity is kept at the beginning of each mining period. The final long range schedule satisfies a set of constraints for each period, mainly ore quality and quantity constraints for ore and waste. An interactive smoothing procedure at the end of each period results in a schedule that is feasible in terms of mining practice. Finally a cash flow analysis model carries out cash flow calculations so that the user can select the best alternative. The linear programming model, based on a certain number of shovel regions, defined interactively by the model user, calculates the optimum production schedule for each short period under consideration, so that a set of constraints is satisfied.

Jan 1, 1986

By H. Ehnes

"“Industry 4.0” – “Mining 4.0” - perhaps you have already heard of these terms? These keywords signify the next stage of industrial production. The internet and production technologies are growing closer together. Machines can communicate with one another, wherever they may happen to be located. The “Internet of Things” is the appropriate term. But what does SAFETY 7.0 mean? It is both brand new and traditional at the same time. It also has to do with the success of companies, with efficient production. And yet there is a great deal more at stake. It has to do with our lives and our safety – the supreme commodity in this world. What exactly SAFETY 7.0 means, what the number 0 stands for and the meaning of the number 7, and what this all has to do with mining will be explained in the following article. Mining is a fascinating undertaking. Mining is indispensable for a country’s economic development, whatever that may concern: infrastructure, energy supplies or raw materials for industrial production. Mining has brought forth many technological developments and innovations that can currently be found in our daily lives. Mining is impressive, grandiose and repeatedly fascinates mankind with its immense dimensions. Miners throughout the world still work hard and, for this reason, are bound to one another in a special way. In mining, every man looks out for the other; you have to be able to rely on each other. That creates a strong bond. The other side of the coin is that mining and disasters belong to normality in the media and thus also in our perception. Accidents at work and even catastrophes occur in mining, quarries, or raw material operations almost on a daily basis somewhere in the world. They are often associated with extremely serious injuries, or even a fatal outcome, for the miners affected and, in turn, dramatic consequences for the families of those involved. It could be in China, India, Russia, or somewhere in Africa, Asia or America – it mostly does not happen in front of our door or in our neighbour- hood. Perhaps because of this in the daily concert of negative headlines, we do not register these catastrophes any more in our minds. We write them off under the heading “Nothing special”, since there are, day in day out, more terrible news items about wars, civil wars, famines, or ecological disasters. Things only really change if there is a dramatic number of deaths or when we are personally affected, close by in the vicinity, or can witness the rescue action live. In Europe, these three mining disasters in particular have recently generated media resonance:"

Jan 1, 2016

By Guerry H. McCullen, Bruno Despujol

Quartz and phosphate grains from concentrates and ores from Atlantic Coastal Plain sediments often are wholly or partially coated by humates. Coatings were studied in situ using infrared microscopy, by transmission Fourier transform infrared of extracts, and scanning electron microscopy. The 14C age of the coatings is about 20,000 years, much younger than the mineral substrates. Coatings on double flotation concentrates indicate that the conditioning pH may be too low, allowing coated quartz grains to follow phosphate grains through beneficiation. Organic matter from coatings may contribute to processing problems as well as affect final product quality.

Jan 1, 1999

By M. S. Klima, B. K. Kim

The use of a 25.4-mm- (1-in.-) diam water-only hydro-cyclone for separating liberated 125 x 25- µm high-density particles from similar-size lower-density (2.65 g/cc quartz particles, as might be used in soil washing applications, was investigated. As expected, cyclone performance was greatly affected by changes in cyclone geometry and operating conditions. A single-stage separation recovered 75% of the magnetite (4.8 g/cc) while rejecting nearly 60% of the quartz. With ferrosilicon (7.0 g/cc) as the heavy component, the recovery improved to 85%. The use of dense medium in a single stage increased both ferrosilicon recovery and quartz rejection to approximately 90% each. In addition, computer simulations of a three-stage circuit were performed. The simulations showed that recoveries approaching 97% with quartz rejections of 95% were possible.

Jan 1, 1999

By Michel David

Once a mineralized body has been delineated, drilled and estimated from surface samples, it often happens that before the final go-no-go decision is taken, an underground sampling program is decided, very often via a ramp which hopefully will be later used to extract the ore. The cost of such a program can be close to a million dollars. On other occasions, when a property changes hands and is reexamined maybe 20 years after the original drilling program, a "check sampling" program is carefully, designed to make "sure" that the old assays are "correct". One may fear poor sampling practice in old days, or deliberate highgrading by promoters. Again one may be talking of resampling cost which may be in the six-figures range. Other similar situations include the drilling of a few large diameter holes to ascertain the validity of a majority of small diameter drill holes, or auger drilling, or back-rimming. In uranium checking radiometric information is also a problem related to the above ones.

Jan 1, 1979

By Eugene V. Cilento, George B. Georgellis

The hypothesis that freshly-sheared quartz makes it more reactive in lung tissue than aged quartz was tested by its ability to stimulate superoxide anion (02-) release from single adherent pulmonary alveolar macrophages (PAM). Fresh quartz was prepared by grinding for 30 min and then used within 2 hr, while stale quartz was from the same stock but aged 15 days prior to use. Also, dipalmitoyl lecithin (DPL), the major constituent of lung surfactant coating the alveoli surfaces, was coated onto the particles. Release of 02- was measured after 40 and 180 min of direct contact with quartz dust (225 µg/ml). Fresh quartz was more reactive than aged quartz, as indicated by the 78 and 63% increase after 40 and 180 min, respectively. A time delay and suppression of 02- release was observed in the ability of the DPL- coated fresh or stale dust to stimulate PAM. These results supported the hypothesis that the natural process of surfactant coating of inhaled particles in the alveoli may play a role in their phagocytic removal by PAM.

Jan 1, 1991

By G. Vijaya Kumar, B. Srinivasa Rao, G. V. Krishna Rao

The paper outlines the ventilation practices prevailing in coal mines of Singareni Collieries Company (South India). The high annual average surface temperature and relatively steep geothermic gradient results in virgin strata temperatures in the region of 38- 42°C creating environmental problems in the working places. Expensive methods of air cooling can not be employed as the mines are small, and production and productivity do not justify the costs of artificial cooling of mine air. Controlled recirculation of mine air -- the unconventional technique being tried with success in some coal mines in U.K. has been analysed for improving the environmental conditions. The analysis shows that the method is safe, cost effective and can be applied with very little extra equipment.

Jan 1, 1991

"INTRODUCTION Foam, unless intentionally created, in any industrial process presents operational problems, or at a minimum, is a nuisance. Some foam problems are unique to a given industry and others are common across many industries. A few problems foam presents to any particular industry are: (a) Poor Housekeeping, (b) Environmental impact, (c) Safety Hazards, (d) Slower Production Rates and, (e) Reduced quality of the end product. Defoamers address these issues. Sadly, the assumption in most industries is all defoamers are alike. In reality, a lot of chemistry is involved in the manufacture of even the simplest defoamer sold today and rarely are any two defoamers “just alike”. Today’s defoamers can include polymer chemistry, fatty esters, alkoxylated alcohols, silicone chemistry, silicone surfactants, ethoxylated and propoxylated block polymers, and a tremendous amount of emulsion chemistry just to name a few. This paper will discuss the various types of defoamers, defoaming mechanisms, the advantages and disadvantages of defoamer selections, and how to choose the proper defoamer for your application. Before a discussion of defoamer can be brought about, foam generation and composition must be discussed. WHAT IS FOAM? Foam is a colloidal suspension of a gas dispersed in a liquid. Most often foam consists of air dispersed in water. If a stream of air is introduced into a liquid, the bubbles produced assume a spherical shape. As the density of the bubble is less than the liquid the bubble rises. When the individual bubbles reach and pass through a surfactant free liquid they collapse. Air from the bubble dissipates and the liquid previously surrounding the bubble flows back.It should be noted a pure liquid will not foam. In the case of air dispersed in water a surfactant is necessary to make the water support a stable foam. A surfactant is a term used to describe a surface active agent; a compound with a hydrophilic end and a hydrophobic end on the same molecule."

Jan 1, 2016

By J. R. Sturgul

A dynamic input-output model for a coal power enterprise that now includes four underground coal mines, three coal washing plants, a power plant and a railway transportation system was developed. The model is applied to analyze investment alternatives for long-term development, including the expansion of existing mines, the opening of new mines, the construction of new coal washing and power plants and the upgrading of the railway system. As a result, the optimal investment strategy with capital schedules and projected sector outputs is obtained. Also, the importance of the new power plant to the strategic development of the company is demonstrated. It is concluded that, without applying a dynamic input-output model, it would be much more difficult or impossible to conduct such a systematic and compete analysis.

Jan 1, 1999

By J. P. Golightly

The nickeliferous laterites of Soroako are described in their setting in the huge Cretaceous ultramafic complexes of central Sulawesi, Indonesia. The ore bodies occur on spurs, ridges and hill flanks beneath remnants of extensive erosional surfaces. Weathering pro- files that have developed on unserpentinized harzburgite and on strongly serpentinized lherzolites show distinctive laterite structures, mineralogy and chemistry. The former are unique to the Soroako area and permit an unusual degree of upgrading by rejection of unserpentinized peridotite boulders. A mass balance calculated for a selection of profiles indicates that in situ leaching of a column of peridotite 20-50 meters thick has taken place with only minor lateral migration of nickel in solution.

Jan 1, 1979

By David Akers, Clifford Raleigh, Glenn Shirey

Under a Cooperative Agreement with the U.S. Department of Energy’s National Energy Technology Laboratory (NETL) and the Mining Industry of the Future Program, CQ Inc. is demonstrating the GranuFlow™ process for improving the recovery of fine-sized coal in commercial coal preparation facilities. The State of Pennsylvania’s Energy Harvest Grant Program is also providing funding for this project. The GranuFlow technology involves the addition of an asphalt emulsion to a slurry of fine-sized coal (<100 mesh or 0.15 mm, typically froth flotation concentrate) before mechanical dewatering in screen-bowl centrifuges. The emulsion selectively agglomerates the carbon-rich particles, resulting in increased particle size and improved recovery of the coal fines during the dewatering process. This paper summarizes the test conditions and current results for both bench-scale investigations and full-scale commercial plant demonstrations.

Jan 1, 2005

By Dennis V. D’Andrea, Peter G. Chamberlain, James J. Olson, William C. Larson

Blasts designed for in situ copper leaching must produce adequate fragmentation and permeability for successful leaching. Copper recovery depends to a large extent on the particle size distribution created by the blast, the permeability in the blast- fractured zone, and the ability to maintain solution flow with a minimum amount of channeling. This paper presents the results of Bureau of Mines experiments where core drilling was used before and after blasting to establish the degree of fragmentation. Data are presented from tests at the Sierrita mine of Duval Corp., and also from tests at the Emerald Isle mine of El Paso Mining and Milling Co. Copper recovery is predicted from fragment size distribution data using a computer model. Data from several blasts are used to show how predicted copper recovery is related to powder factor.

Jan 1, 1977

By K. K. Haramy, J. McDonnel

INTRODUCTION Primarily because of mining at greater depth, an increasing number of coal mines in the United States experience floor heave problems. In many instances, the floor heaves at a slow rate without causing health and safety related problems; only additional roadway maintenance and coal handling equipment are required. However, when rapid, massive heaving occurs, the safety of mine personnel in the vicinity is jeopardized. Extensive floor heave causes a redistribution of stress around the mine opening and can cause additional ground control problems. This paper presents an analysis of rapid floor heave in a deep western coal mine. The analysis is based on field measurements, laboratory data, and beam design theory. Factors affecting floor heave, such as mining-induced stress, mine opening size, entry orientation, mine geology, rock physical properties, and gas pressure, are considered. Examination of floor heave in the mine indicates that heaving is primarily caused by deformation of a soft floor member that is subjected to high mining-induced stress. Theoretical analysis of in situ floor stresses resulting from overburden loading indicates that floor failure will occur. The analysis is confirmed by visual observations of floor heave in the mine. Recommendations for mine layout and opening design to control rapid, massive floor heave under these conditions are also presented. MINE-FLOOR-FOUNDATION THEORY The floor stratum in a coal mine acts as a foundation to support coal pillars and artificial supports, thereby providing support to the mine roof. The overburden load, transferred through pillars and other supports, applies tremendous stress to the floor. Soil mechanics theories provide solutions for foundation design problems that apply to the mine floor. Based on foundation theory, vertical load on pillars causes high shear stress zones in the floor. If the floor is relatively weak, it may fail and dislocate upward into the mine opening. Strong roof strata that do not readily fail transmit most of the overburden load through pillars to the floor. Heaving may result, depending on the thickness and physical properties of the floor

Jan 1, 1986

By Julian Boldy

The discovery of the Delbridge massive sulfide deposit in the Noranda district of Quebec resulted from an appreciation of the significance of a mercury leakage haloas a lithochemical pathfinder to blind ore, coupled to its location relative to a geologically inferred ore-bearing horizon within complex volcanic stratigraphy. Systematic sampling of microfractures present in outcrops delineated a diagnostic anomaly, drawing attention to an area considered prospective for buried ore. The massive sulfide deposit was subsequently found to be blind and topped at the 107-m (350-ft) level. This case history is presented in the context of its time and was the first volcanogenic ore deposit to be discovered utilizing mercury as a pathfinder in the Canadian Precambrian. The case history also illustrates that the practical application of an innovative technique coupled to a new geological interpretation can result in success, even on a property that was centrally located in a mining district and had undergone intensive exploration efforts over a 38-year period.

Jan 1, 1991

By Todd Kilduff, Michael Tinney

The North Temple Tunnel pedestrian underpass in Salt Lake City, UT was built using a pipe canopy method that met significant challenges in potentially running ground conditions. Kilduff Underground Engineering (KUE) was the designer for the 20-foot-diameter SEM tunnel, Design-Build contract. Geotechnical data indicated ground conditions consisted of loose silty gravel for the majority of the face overlying soft to medium stiff clays in the tunnel invert. KUE designed a pipe canopy as pre-support to stabilize cohesionless gravels in the crown, a shotcrete initial liner with lattice girders to minimize disturbance of the finer-grained materials in the invert and a final liner with waterproofing system. The project was presented with a few unique challenges, primarily from the adverse ground conditions, but was successfully completed safely and schedule

Dec 1, 2022