Search Documents

By Daniel Lakovic

"Mining operations can create a negative environmental impact, especially when considering the tailings that are produced through the processing of ores. Tailings are finely grained residues that form sludges. The tailings are deposited into giant basins, or sludge ponds, where they create a burden on the environmentby limiting the use of processed water.Tailings are one of the most important environmental liabilities for mining operations because of their large proportion in relation to the ore mined — generally 90 to 98 percent. To get to the valuable minerals, mining companies must move large amounts of rock. The rock is ground and then treated, usually with the addition of chemical solutions and large amounts of water. The lower the concentration of the valuable resources, the greater the proportion of accumulated excavated material sludge.Sustainable tailings management requires responsible handling, making it one of the mining industry’s greatest challenges. The proper technology should include consistent control of the environmental risks and impacts, as well as a proper relationship with the communities that surround the mining operations.The tailings, which can remain partly contaminated with chemicals, are pumped into the large sludge basins, which are secured by earthworks. During the mining operations, the basins must be stable enough to withstand the pressure of the stored excavated material. The storage option is still used, but it has failed on occasion. And when it does, it increases the risks to the environment and binds the unused process water. The more complex the availability of fresh water required for industrial use and for human consumption and their economic activities — for example, farming and agriculture — the more complex the conflicts that have the potential to shut down mining operations. With modern separation technology solutions, it’s possible to process the sludge and recover the processed water. However, the responsible use of the water is critical. Therefore, mining companies must rely on technologies that allow for proper reclamation of the water, whether re-using in their own processes or treating it to return it to the environment."

Dec 1, 2018

By M. Bai

The influence of mining on the hydro-geomechanical environment is greatly constrained by alternating mining geometries. The limiting magnitudes of surface subsidence and groundwater flow over the mining area, as a result of geometry changes, can be reasonably predicted through a coupled finite-element model introduced in this paper. Verification of the model has been tested using real and conceptual case studies which reveal that changes in strata conductivities are strongly related to the strata deformation induced by mining. The greatest modification of hydraulic conductivities occurs within the caving or severely fractured zones. The study indicates that narrowing the panel face width will substantially reduce both the intensity and extent of mining damage to the overlying strata, limit surface subsidence and constrain the change in hydraulic conductivity to a reduced scale and smaller extent, particularly as mining depth increases.

Jan 1, 1993

By E. Molleman

This paper reports on testwork exploring the dissolution/reprecipitation reaction: ZnS + 2HCl ? ZnCl2 + H2S, as part of a process for the production of pure ZnS. In spheroidal form, this would constitute a premium fonn of zinc refinery roaster feed enabling the production of pure ZnO. The research focused on the influence of proton activity on dissolution of zinc concentrates from Brunswick Mining & Smelting, Red Dog and Tara. The results and thermodynamic data suggest that the three concentrates contained significant amounts of the more reactive mineral wurtzite, although XRD analysis showed mainly the presence of the mineral sphalerite.

Jan 1, 1997

By E. R. Bauer

A primary goal of Ground Control Research, Bureau of Mines, U.S. Department of the Interior, is to develop information that can be used by the mining industry to reduce accidents and fatalities due to failure of mine roof. A specific research objective is to determine methods to detect hazardous coal mine roof. This paper reviews the existing and experimental techniques, and describes a recent Bureau of Mines contract research project that resulted in a simple technique and prototype instrument for evaluating mine roof competence.

Jan 1, 1986

By Francis Martino

Just as coal producing mines are faced with various handicaps which control the quantity of coal produced and sold, the subsequent user of that product is faced with parameters that impact the optimum utilization of coal. Traditionally, the industry focused on the quantity of mineable coal in a reserve. The mine planning development was primarily concerned with two important criteria: (1) safety and (2) the productive efficiency in a quest to produce the lowest cost coal.

Jan 1, 1982

By L. Xia, B. Hart, V. Sidorkiewicz

Sodium silicate(s), also known as “water glass”, are one of the oldest and most widely used industrial chemicals. Its first use in North American mining operations can be traced back to around 1925, which coincided with early use of xanthates in mineral flotation. Silicate functions as a sulphide and non-sulphide gangue mineral dispersant, depressant and modifying reagent in grinding and flotation operations. It is believed that soluble sodium silicate promotes selectivity of value added sulphides against gangue minerals, resulting in both grade and recovery improvement. This paper seeks to link improved grade/recovery to the interaction characteristics of minerals and the sodium silicate. A systematic study was performed with individual mineral species, an artificially designed model ore and the feed ore from a copper metallurgical operation. The function of sodium silicate was evaluated in the context of colloidal chemistry and linked to mineral surface chemistry. Measurement of pulp rheology and mineral zeta potential identified that sodium silicate works as a dispersant. The dispersion is accomplished by increasing a mineral’s net surface charge, resulting in a mineral variable change in viscosity. Bench scale laboratory flotation tests suggest that better dispersion leads to a diminished interaction of chalcopyrite with gangue. The improved Cu grade and recovery then are likely in response to an increased accessibility to collector along with a linked increase in particle bubble attachment resulting in better separation efficiency. ToF-SIMS surface chemical analysis of the flotation samples found a higher proportion of sodium silicate on minerals from the flotation tailings relative to the concentrates. Moreover, attachment of sodium silicate appears to be mineral specific; the data indicates that sodium silicate favours the surface of gangue phases over the value sulphides. INTRODUCTION Mineral processing involves enrichment of valuable minerals from an ore, where the separation process utilizes differences between the properties of the value-added and gangue minerals. The properties of minerals, for example composition, specific gravity, particle size, magnetic properties etc., in any flotation feed ore, can vary significantly between the various minerals present. In flotation seperation surface chemistry and wettability is a significant component promoting selective separation of the various mineral phases [1,2] Mineral surface wettability can be changed, advantageously or deleteriously, by many factors including: surface layer alteration through oxidation; galvanic interactions; attachment of secondary precipitates; the adsorption of various reagents [3] In the flotation context the wettability of a minerals surface can be manipulated by various reagents. Collector reagents may selectively attach to specific minerals in the mineral/water slurry enhancing their surface hydrophobicity, increasing bubble-attachment efficiency and improve flotation kinetics and mineral recovery [4]. In contrast, depressant reagents may selectively reduce a minerals surface hydrophobicity resulting in poor particle-bubble attachment and non flotation. In essence, a mineral flotation flow sheet is designed to induce/promote a hydrophobic surface to the value mineral and a hydrophilic surface to all others. Therefore, the versatility of the froth flotation process lies in the selection of different flotation reagents.

Jan 1, 2019

By R. K. Sinha, B. S. Choudhary, Desh Deepak, A. K. Mishra, Hemant Agrawal, Shankar Kumar

Despite several methods (empirical, statistical and machine-learning tools) to calculate blast-induced ground vibration, it is not easy to predict and simulate blast vibration precisely under varying blasting loads and strata conditions due to complications in the blasting procedure. In this study, field blast data were simulated in Ansys software using explicit dynamics, and ground vibrations for 20 single-hole blasts were monitored. The densities of emulsion explosives were in the range of 0.9 to 1.15 g/cm3. In the laboratory, rock properties were determined from rock samples collected from the mine site before blasting. The in-hole velocity of detonation (VoD) and density of the emulsion explosive were also determined and used in numerical analysis to know the ground vibrations at specific points. The results of ground vibrations predicted by the model were validated using field data.

By K. E. Robinson

During operation of tailings impoundments, water is lost through decanting, evaporation and seepage. Techniques have been developed to regulate or control each of these components. Collectively implemented, these techniques form the basis of tailings impoundment management. Regulation of the rate and level of decanting influences the size of a free water pond, and, thereby, the amount of evaporation and seepage, which are both area-dependent. Conversely, the encouragement of seepage and/or evaporation could also be used to reduce decanting requirements. Management of one of the components of a tailings impoundment's water balance is reflected in changes in the other components. The seepage component has the greatest potential impact on the environment, and consequently requires the closest scrutiny. Water percolating through tailings backfill transports heavy metals and other dissolved solids from the impoundment into the local groundwater regime. Depending on the seepage volume and concentration of contaminants, seepage from impoundments could exceed environmentally tolerable limits. Once mobilized, seepage-borne pollution is much more difficult to treat, mainly because of the problems in collecting the diffusive transportation medium. Pollution abatement measures relative to tailings impoundment seepage depend on seepage prevention or reduction. Seepage control measures include constructing barriers to flow, pump-back systems of interception and restricting the supply of water available for seepage.

Jan 1, 1987

By Charles V. Riley

While the late 1960's are known as the years of the public recognition of impending environmental crises, the 1970's will be known as the decade of public concern for improving the quality of that environment. One of the present major environmental concerns is the temporary disturbance resulting from coal surface or open cast mining. To realize that this concern will continue in the future, one need only observe the daily news media. Increasing energy demands in the U.S., a doubling of electrical power consumption each decade during the present century, and the projected needs for the remainder of the century are indica¬tions that coal surface mining as a major extractive industry will continue. Coal and lignite, prime energy resources and extremely abundant in these United States, in the face of seemingly limited gas, oil and uranium reserves, are both destined for expanded future use. Presently some extremely serious techno-logical and environmental problems are associated with the develop¬ment and use of nuclear power. It is true that the extraction and use of coal as an energy fuel poses disruptive problems for the environment, but the solutions to many of the problems are known or can be solved within a reasonable time framework. Certainly our national well-being and continued survival, as a free nation within the world community, automatically dictate the continued use of the coal resource for energy. Concurrently, those engaged in coal surface mining, with the temporary disturbance of the land and water resources, must also realistically conclude that public concern for maintaining and improving the quality of the environment will not diminish. Although as ecological, economic, social and aesthetic elements

Jan 1, 1972

By Dan Nilsson

The Luossavaara "Research Mine" is the First large, offensive effort in mining research conducted by the Swedish state. Over a 5-year period, 1981-1985, the Swedish Mining Research Foundation works in the "Research Mine" on the development of mining systems and equipment. The purpose is to bolster the competitive strength of the Swedish mining and mining equipment industry. The previosly abandoned Luossavaara mine in Kiruna, in northern Sweden, has been reopened especially For the project. Ore is mined and sold during the course of the research project. The income from the sales covers a large portion of the costs for teh research.

Jan 1, 1985

By Verya Nasri, Behrouz Esmaeilkhanian, Mohammad Motallebi

Réseau Express Métropolitain (REM) is the new Light Rail Transit (LRT) network of Montreal, Canada. This new LRT network uses a century-old Mont Royal Tunnel (MRT) to connect Downtown Montreal to the north side of the Island of Montreal by passing through Mount Royal Mountain. This railway double track horseshoe tunnel is approximately 5 km (3.1 mi.) long, 8.8 m (29 ft.) wide and 5.5 m (18 ft.) high, with a constant 0.6% grade. Due to different geological characteristics of the surrounding ground, varied from hard rock to soft soil, different cross sections and excavation methods were adopted for construction of this tunnel. In order to use MRT in the modern transit system, the tunnel needed to be inspected, rehabilitated and be compliant to the recent safety standards. This paper presents a summary of history and characteristics of the existing tunnel plus the implemented steps to upgrade the tunnel. It includes the details of the structural inspection and rehabilitation methods of the tunnel. Further, this paper summarizes the procedures for the space proong, construction of the separation center wall, and the tunnel enlargement. It also describes parts of complications encountered during the construction and solutions implemented to tackle these issues.

Jun 23, 2024

By W. G. Pariseau

A study of coal pillar strength at the Beehive Mine in central Utah was done in the 1970s. This study was a cooperative effort by the University of Utah, RE/SPEC, Inc., and the American Coal Company and was funded by the U.S. Bureau of Mines. Mine measurements of closure at 117 points and pillar stress using 119 vibrating wire stress gauges were made during retreat mining in this room-and-pillar operation. Laboratory testing for the strength and modulus of 372 coal cylinders up 0.3 m (1 ft) in diameter and 0.6 m (2 ft) in length was also done. Two-dimensional finite element model analyses complemented the study. However, the real world of mining is three-dimensional and in consideration of the significant advances in computing power since the time of the original study, a revisit of the data seemed warranted. In this regard, a novel finite element method was used that allows for the whole-mine analysis of tabular excavations on the kilometer scale and yet enables details to be obtained at pillar walls on the meter scale. The effects of material properties variability in situ and of joints can also be taken into account. Results that compare computed two- and three-dimensional seam-level closures with mine measurements show noticeable differences; three-dimensional results are reasonable, while two-dimensional results overestimate closure by nearly a factor of two.

Jan 1, 2014

By J. F. Barry

Newmont Mining Corporation and Barrick Goldstrike Mines, Inc. concluded an exchange of land and reserves in an agreement signed May 3, 1999.This exchange of assets allowed Newmont to develop the Deep Post underground mine from within Barrick’s Betze-Post open pit, thus reducing capital expenditures, lowering operating costs, and advancing the production schedule by nearly three years. Based on previous experience, Newmont is confident that the Deep Post underground mine can be successfully developed and operated within a large, active, open pit mine. The project also faces difficult geotechnical conditions including weak ground, scattered pockets of groundwater, and elevated rock temperatures.

Jan 1, 2000

By T. C. Murray

An automatic control system was recently installed to insure the continuity of operation between the ship docking and ore handling facilities and the computerized conveyor-fed sintering plants and blast furnaces. Although the basic concept for material handling has not changed, many innovations including computer control have been implemented.

Jan 1, 1978

When it comes to safety in the mining and extractive industries, success is literally a matter of life and death. Anything short of perfection is not acceptable. In recent years, the mining industry in the United States has made tremendous strides in terms of health and safety for its workers. Part of that success has come with an increased focus on the issues of safety, an intense examination of procedures, liberal sharing of best practices and a focus on the synergy between safety, reliability and environment. During his closing keynote address of the Safety Management & System Reliability Conference in Minneapolis, MN on Nov. 15, Joe Driscoll, vice president of Great Basin Gold, showed a calendar from the coal fields in Pennsylvania from the early 1900s. The calendar marked the number of mine-related deaths each month. Some months, the number was as high as 50. It was an illustration of how far things have come, but there is still much more work to be done.

Jan 1, 2013

By Stacey Leichliter

The Cripple Creek and Victor (CC&V) Gold Mine (Cresson Project) (Fig. 1) is undergoing an expansion to extend production to the year 2025. This expansion involves building a high-grade ore mill, another valley leach facility (VLF) for heap leach operations and expanding the overburden storage areas. The current operating pits are progressing downward from the oxide ore into a more sulfide and telluride-rich orebody. There is still oxide ore present in the current pits and planned pits not yet mined. There is an increased need for two recovery processes for these two different types of ore. The key component to this expansion is the high-grade ore mill, which has gravity, flotation and carbon-in-pulp (CIP) circuits. The mill will be the main recovery process for the higher grade, more sulfide/telluride-rich ore. This ore type does not recover well on the heap leach pad due to its refractory nature. Geometallurgy is vital for ore characterization for the two recovery methods. Geometallurgy helps develop indices that are used to predict parameters that influence overall recovery and production, such as hardness, crushability, grindability, pH fluctuations, gravity (coarse) gold, flotability and cyanidability. Using geology and mineralogy along with other analytical data, geometallurgical models are constructed and applied to the resource block model for proper planning and extraction of the gold. Geometallurgy aims to analyze the variability in the different responses to the parameters to help reduce risk (costs) and optimize recovery (profit).

Jan 1, 2013

By Jorge Alberto Soares Tenório, Denise Crocce Romano Espinosa, Amilton Barbosa Botelho Junior

A new step in the Bayer process has been used to recover NaOH and to reduce its content in red mud. After digestion, the residue is separated from the Bayer liquor and goes through press filters, which enables the recovery of NaOH and decreases the moisture content. It is well known that red mud is one of the most important sources of scandium. For this reason, the goal of this work was to characterize a Brazilian red mud (BRM) for scandium recovery. The sample was collected after the press filter system process. Analysis of energy-dispersive X-ray fluorescence (EDXRF), scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS), and X-ray diffraction (XRD) was performed. Microwave digestion using an acid mixture was carried out to determine the concentration of the main elements. Fe2O3 represented 40% of the BRM, and the Sc concentration was 43 mg/kg. The SiO2 content was 24%, which is the highest value found in the literature, whereas the sodium concentration was the lowest. A literature review was carried out to compare results with BRM, as well as the current studies for recovery of scandium by the leaching/ion-exchange process. Scandium recovery using a leaching/ion exchange process may be possible with efficiency higher than 90%. The greatest challenge is the occurrence of silica gel formation during leaching.

Oct 19, 2020

By MUSTAFA ERKAYAOGLU, Muhammet Mustafa Kahraman

Particulate matter (PM) is one of the main actors related to air pollution caused by surface mining. Fugitive dust, considered as particulate matter that cannot be collected by conventional measures, is classified by the particle size. The Environmental Protection Agency (EPA) categorizes PM as coarse and fine particles based on the particle size being less than 10 μm (PM10) and less than 2.5 μm (PM2.5). Basic operations of surface mining such as drilling and blasting, loading, haulage, and processing are processes that can potentially generate fugitive dust. Regulations and legislations enforce the mining industry to use environmental monitoring systems, fugitive dust level measured by PM10 level as part of this. Air quality monitors are positioned at different locations around surface coal mines and track air quality levels during production. This study introduces a data-driven methodology to handle air quality issues related to fugitive dust at surface coal mines. Data is sourced from different mine equipment in real-time and they are integrated with air quality monitoring systems to provide information to support decisions for fugitive dust. The method is implemented and demonstrated in a case study at a large surface coal mine.

Sep 29, 2020

By Michael J. Beus, Jan G. Patricio

INTRODUCTION The U.S. Bureau of Mines, Spokane Mining Research Center, has been conducting and documenting rock mechanics research in the Coeur d’Alene mining district for the past ten years (1, 2, 3, 4, 14, 15). A current project combines the information gathered from rock mechanics instrumentation, geologic structure, and analytic techniques to improve shaft and support design for the deep mines of the district (3). This project required knowledge of the anticipated loads and the physical properties of the rock mass to provide accurate input data for computer design models. Several techniques have been utilized to determine the physical parameters including the USGS (U.S. Geological Survey) solid inclusion probe, the CSIR (Council for Scientific and Industrial Research) biaxial and triaxial strain cells, and the CSM (Colorado School of Mines) dilatometer. This paper describes the determination of the in situ modulus of deformation in three mines over a period of three years and the evaluation of these results as they applied to this project. The need for in-situ rock mass properties such as the modulus of deformation has stimulated research and development of a large number of instrumentation techniques. One area of continuing interest involves various methods of radial borehole dilation. This concept was pursued by Menard (9) with an apparatus known as the pressure meter, which is used frequently in soil mechanics. Other developments in rock mechanics include the CPC (cylindrical pressure cell) by Panek (11) and the dilatometer by Rocha et.al. (13) in Portugal. The CSM dilatometer, which also utilizes this technique, was chosen for this project because it required a small amount of background study, was inexpensive, and could easily be combined with other experiments being planned for the test locations. Although no previous field applications to hard rock (compressive strengths greater than 20,000 psi) has been documented, the instrument was selected since good results have been achieved in granite, oil shale, and several coal measure rocks (11, 12).

Jan 1, 1977

"In the conceptual stages of engineering, benchmarking and empirical ratios are commonly the only references for estimating the production rate of greenfield projects. For underground mining projects, the lack of similar cases often makes the comparison difficult due to each project’s unique geology, rock quality or other singular characteristic. This paper discusses an analytical alternative for determining the maximum achievable production rate for underground stoping mining by modeling production as a continuous process. The results show that long-term maximum capacity depends exclusively on the achievable development rate and the development intensity of the design. In operations constrained by backfill, the development rate could be limited by the backfilling rate. Extraction rate and stope size only have impacts on capacity estimates during the ramp-up period.These findings allow shaping of the maximum capacity profile of a project. They can be used as a tool for quick assessment of conceptual capacities, and sensitivities of mining rates. Benchmarking tests compared favorably with projects, mines in operation and scheduling exercises. IntroductionA key consideration in the value proposition of a mining project is its capacity or production rate (Tatman, 2001). At a conceptual level, it is common practice to refer to empirical references (Taylor, 1986; Long, 2009), rules of thumb (de la Vergne, 2014), benchmark ing studies or consultant experience to estimate or validate a target value. There is, however, a lack of analytical methodology to guide an early estimate of the maximum capacity.Araneda and Gaete (2004) presented an interesting mathematical approach to estimate the capacity of panel caving mines. Using a continuous model, they confirmed that the mine capacity is essentially determined by the rate of area incorporation, in terms of area per period, and ore column height. This simple relationship has been confirmed by multiple detailed scheduling works"

May 1, 2016