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By Mike Lewis

"Descending several stories down a metal staircase into a shaft spanning a quarter city block -- soon to become Roosevelt Light Rail Station in Seattle, WA -- visitors are greeted with four perfectly round, precast concrete-lined horizontal holes leading deep into the earth. The sound of water trickling out from a small drainage trough can be heard over the faint echoes of construction within. Upon entering, the light is dim, but the air is clear with barely a dust particle flowing through the sunbeams. This type of air quality is only accomplished with diligent controls, and JCM Northlink, the company in charge of building the Northgate Link Extension Project, is taking those measures seriously.Commissioned by Sound Transit, JCM is a joint venture of three companies: Jay Dee Contractors, Frank Coluccio Construction Co. and Michels Corp. The tunnels JCM constructed are intended to provide fast, reliable underground rail service, as well as relieve one of the region’s most congested traffic areas. The $440 million project will connect the Northgate, Roosevelt and University District neighborhoods north of Seattle to the downtown corridor and SeaTac airport further south.The scope of this project includes excavation for two light rail stations, boring of two parallel 5 km- (3.3-mile) long light rail tunnels in six runs and the construction of 23 cross passages. Begun in 2014, Sound Transit estimates that crews excavated more than 382,000 m3 (500,000 cu yds) of soil and installed 7,352 precast concrete tunnel liner rings during the shaft construction and boring phase. Now that tunnel boring is complete, JCM is in the process of constructing the cross passages, which act as maintenance areas and escape routes for passengers. Throughout the entire process, the company has utilized atomized mist to control particle emissions.“Our dust control needs change at every phase of the project and don’t go away until the project is fully complete,” said a JCM safety representative. “We found that different dust suppression technologies were needed at different intervals, but atomized mist seemed to fulfill our needs at every step.”"

Jan 9, 2017

By S. N. Gurulaxmi, Veerendra Singh

The abstract discusses the increasing consumption of manganese ores and the need to utilize low-grade ores and rejects. The study focuses on developing a low-cost process using a cupola furnace to recover manganese values from these resources. The process involves smelting ore blends to produce high MnO slag and pig iron. The study investigates various factors to improve iron reduction and separation from MnO-bearing slag. The results show that the process can produce slag with MnO > 35% and Fe(t) < 5% using low-grade Mn ores. The process also achieves Fe reduction between 50 and 70%. The cupola furnace offers advantages like low cost and ease of operation, making it suitable for processing low-grade ores and rejects to produce synthetic MnO-enriched products for various industries.

Apr 1, 2022

By J. Kretschmann

"By the end of the 1950s, the German hard coal mining industry produced 150 million tons of hard coal per year in 170 collieries with 600,000 employees. At that time, 70% of the primary energy demand of the Federal Republic of Germany was covered by domestic coal. However, due to coal mining becoming an increasingly globalized business and the oil and gas industry producing with lower costs, the German domestic hard coal industry stood constantly under restructur-ing pressure. The industry declined until the end of its life cycle. In 2007, a political understanding was arranged to phase out German hard coal mining in a socially acceptable manner by the end of 2018. This decision required a new strategy for the coal mining industry. Being strictly finalized, the German hard coal mining industry has to be prepared for the post-mining era. To create a sustainable development strategy, the long-term impacts of coal mining activities in Germany concerning the environmental, economic and social dimensions will be analyzed systematically and forward-looking. The regional and social responsibility during the closing process and for the post-mining era will be emphasized. High technical standards in environmental protec-tion and post-mining technologies, as well as long term experiences in the development of former mine sites to create new jobs are significant from an international point of view. The traditionally constructive social partnership between employers, union, and employees has enabled long-term stable adaption processes and avoided social friction. The sustainability strategy of the German hard coal mining industry can be regarded as a role model for other mining countries and regions facing similar transition challenges. INTRODUCTION Principally, mining is a finite business that reaches its end if the deposits are depleted or the raw materials can no longer be mined in an economically profitable way. However, the impact of mining is po-tentially an infinite one – at least if you measure it at a human time scale. Mining always means interfering with geological and ecological structures that cannot be reversed to their original condition. In general, the mining cycle (Figure 1) can be divided into three phases: 1. The exploration phase, in which the deposit is investigated to determine its technical and economic profitability. The period of these undertakings is relatively short and can lead to the launch of mining operations. 2. What follows is the actual mining phase which usually lasts for a long time and ends latest when all deposits are fully depleted. This lifespan may be shortened if the economic conditions (production cost or market price) deteriorate. Nevertheless, mining may be resumed if those conditions become favorable once more (examples are silver mining in Germany or rare earths mining in the USA). 3. The longest phase, however, is the post-mining phase as the human interference into geology and nature is usually inten-sive and irreversible. Mining can lead to consequences which have a permanently adverse impact on people and the environment; therefore, they have to be managed as best we can (1)."

Jan 1, 2017

By P. James

"INTRODUCTION Control of target stream acidity is widely used in MIW (mining influenced water). Tailoring pH (a measure of acidity) finds application for controlling key chemistry in both process and waste streams. Traditional lime addition for neutralization and precipitation is most often used but has high reagent costs and results in large amounts of mixed metal sludge requiring costly disposal. A new adaptation of BPS’s patented DEMET™ technology (Dynamic Electrolytic Metal Effluent Treatment) platform offers a potentially improved and “reagentless” alternative to traditional chemical addition for pH adjustment. Electricity rather than chemical addition utilized in BPS’s proprietary approach controllably tailors target stream pH. The method offers a simple, low-cost processing technique yielding cleaner treatment chemistry. BPS’s “green” approach may yield lower operating (OPEX) and life cycle costs and significant reductions (up to 50%) in sludge generation compared to conventional lime treatment. It can also allow new opportunities to generate revenue via selective recovery of valuable processing byproducts. Specific savings and revenues depend on the target site chemistries, details, and processing goals. A more detailed discussion of the process and its operational principles may be found in Reference One.[1] Here application of the BPS treatment to POx (Pressure Oxidation) leaching as an alternative to traditional chemical addition is examined. An example operation process flow for gold mining is considered.[2] Promising processing points for potentially replacing conventional processes with DEMET are noted. The possibilities for lowering OPEX costs, lessening sludge creation, and capturing various valuable byproducts and residuals are examined. Financial life cycle benefit estimates of the principal gains provided by DEMET application to the example operation are noted. Extension and generalization of the analyses to a wider range of scenarios is explored."

Jan 1, 2016

By S. Fernández, L. Klinger, T. Vallejo

In the municipality of Rio Quito, department of Chocó, Colombia, alluvial gold has been illegally exploited by suction dredging. The project consists of using geospatial techniques to identify degraded areas and analyze the viability of remediation dredging to mitigate environmental liabilities. The area has sediments contaminated by mercury and cyanide, so it is necessary to reconform the riverbed with the remediated material. The work is part of the Mine Closure Plan that seeks to jointly articulate the communities, academia, the company, and the state

Mar 2, 2022

By F. W. Petersen

Slurry reactors are being used extensively throughout the chemical, biochemical and mineral processing industries. This paper describes the interaction between fine ore particles and granular porous adsorbents such as activated carbon and ion-exchange resins in a stirred tank reactor. Gold and silver cyanides were used as adsorbates to detect changes in the mass transfer characteristics of the adsorbents, which were ashed to determine the loading of ore particles. A simple kinetic model incorporating film diffusion, intrapanicle diffusion ~d the adsorption equilibrium, was used to interpret kinetic data and to estimate the effect of slurry conditions on the diffusion parameters. It was observed that the equilibrium loading of fines in the adsorbents was independent of their concentration in the slurry. Furthermore, the presence of these panicles inside an adsorbent decreases the effective diffusion of gold or silver cyanides into the adsorbent matrix. When fine suspended solids are present in the reactor, a decrease in the effective availability of the superficial surface of the pre-saturated adsorbent panicles for mass transfer from the liquid phase was observed. This newly defined surface availability factor was dependent on the concentration, panicle size, and the zeta potential of the fine particles in suspension.

Jan 1, 1993

By Duah Philip, Awuah-Offei Kwame

Regulatory pressure to mitigate the cement industry’s environmental impact has intensified recently, spurring innovation in low-carbon cement technologies. In the United States, cement production, consumption, and carbon emissions are accelerating. Despite this trend, the adoption of environmentally friendly dry clinker production technology with combined preheater-precalciner systems has surged from 53.3% in 2002 to 88.5% in 2019. Concurrently, reliance on wet technologies, known for their higher environmental impact, has dropped from 16.5% to 0.6% within the same period. This paper presents the results of our comprehensive study, utilizing over 100 years of industry data, to analyze these technological shifts and their environmental implications.

Feb 1, 2025

By T. BACHMANN, G. SHAPLAND, E. Amini, N. BEATON, M. BECERRA

Process plant modeling in the computer environment has been developed over the past 40 years by implementing the comminution models formed by the Julius Kruttschnitt Mineral Research Centre, University of Queensland, in the early 1970s. The models for the other processes in a mine value chain, such as blast fragmentation and flotation, were continuously developed and improved in parallel as well. Other research and commercial entities have also developed process modeling methodologies in the computer environment, which evolved as specialized commercial software or through equations set up in Excel spreadsheets. These were performed on a local computer, in thousands of simulations over a long period of time due to hardware limitations and the lack of a fully automated process. This limits the application of detailed process simulations for scale-up and strategic planning analysis, as they require many simulations to cover all possible scenarios which would take a lifetime when using local computers. The Integrated Extraction Simulator (IES), as the next generation of cloud-based software package, has made it possible to run simulations on the entire operation value chain in the same platform, including drilling and blasting, crushing, grinding, flotation, and other downstream process and material-handling units. This capability has allowed IES to handle multivariable simulations across the mine value chain, including pre-concentration and in-pit size reduction, and modify the process simultaneously.

By John W. Harshbarger

The Upper Santa Cruz Groundwater Basin lies in the drainage area of the Santa Cruz River in Arizona, and extends upstream from the community of Rillito to the international boundary, see Figure 1. The principal water use area lies between and includes the cities of Tucson and Nogales. A subsurface geologic barrier near Rillito provides a reasonable dividing line between the groundwaters of the Upper and Lower Santa Cruz Basins. The Upper Basin contains the Tucson and Sahuarita-Continental critical ground- water areas. The Tucson Water Use Area encompasses the Tucson metropolitan area and extends from the northern boundary of the Basin south to the boundary between the Tucson and Sahuarita- Continental critical groundwater areas near San Xavier. The San Xavier Use Area is the San Xavier Indian Reservation. The north and south boundaries of the Continental Use Area coincide with the limits of the Sahuarita-Continental critical groundwater area. The first study of groundwater in this valley was initiated by Dr. G. E. P. Smith in 1905 and the results were published in 1910, followed by a series of bulletins of the Arizona Agricultural Experiment Station, University of Arizona, covering the general field of groundwater development and utilization. Beginning in 1939, the Ground Water Branch of the United States Geologic Survey, in cooperation with the Arizona State Land Department and the Arizona Water Commission (AWC), have published a series of bulletins concerning groundwater occurrence and utilization in various areas of the state. In 1975 and 1977, the AWC published the "Arizona State Water Plan" (1), comprising a detailed inventory of water availability and use in the State of Arizona, and a study of alternative futures.

Jan 1, 1979

By S. Gaillard, E. Cauda

"Diesel particulate matter (DPM) is an occupational health hazard in underground mines. It generally occurs in the submicrometer size range and is often present in the mine atmosphere with significant concentrations of dust particles that tend to occur in the supramicrometer size range. As dust can interfere with analytical methods to measure DPM, it is often removed from a sample stream using an impactor-type size selector such as the DPM impactor (DPMI). Because the DPMI physically removes oversized particles from the stream, its performance may be gradually reduced with aging. Sharp-cut cyclones (SCCs) are an alternative size selector for DPM sampling applications, with a major advantage that, by design, they should not be susceptible to rapid aging. This paper presents the results of a field study designed to compare the performance of aged versus new/clean DPMIs and SCCs in an underground mine. DPMI aging resulted in clogging of the device and, eventually, a reduction of its effective particle cut size, but when sample flow rate was maintained, DPM sample mass collection was not affected until significant aging had occurred. Under the conditions of this study, the effects of SCC aging were observed to be minimal at the end of the study period. IntroductionSubmicrometer-sized particles are increasingly recognized as significant respiratory health hazards (Cantrell and Watts, 1997; Kenny, Gussman and Meyer, 2000; Ristovski et al., 2012). Diesel particulate matter (DPM) represents a major source of submicrometer particles in both public and occupational environments (Kittelson, 1998; Abdul-Khalek et al., 1998). Relative to other occupational groups, underground miners can have some of the highest DPM exposures due to their work in confined spaces where large diesel equipment is used (U.S. Environmental Protection Agency, 2002; Grau et al., 2004). DPM largely consists of solid elemental carbon (EC), commonly known as soot, and organic carbon (OC) that may be sorbed to EC particles (Kittleson, 1998; Abdul-Khalek et al., 1998). EC and OC can be measured by thermal-optical methods such as the U.S. National Institute for Occupational Safety and Health (NIOSH) 5040 standard method (Birch, 2016), and their sum is referred to as total carbon (TC). While the complex nature of DPM does not allow for its direct measurement, both TC and EC have been accepted as suitable surrogates for monitoring occupational exposures to DPM (Noll et al., 2007; Birch, 2016)."

Jan 8, 2018

By B. A. Ashley

Rosebud Mining Co. (RMC) is based in Kittanning, PA. As of October 2013, it operated 24 active underground mines in Pennsylvania and Ohio. RMC?s Tracy Lynne Mine is located approximately 5 km (3 miles) east of Apollo, PA, (approximately 48 km or 30 miles northeast of Pittsburgh, PA) and mines the Lower Kittanning coal seam. The coal seam averages approximately 1.1 m (45 in.) thick and is of steam coal market quality. The mine is a single unit operation. Coal is mined using a continuous mining machine and is transported from the face to the conveyor belt using a continuous haulage system. Typical ventilation in the mine consists of an exhausting fan that draws air through isolated intake, belt and return air courses (Fig. 1).

By Jian Wang, Xiaoming Sun, Ming Jiang, Fuxin Shen, Chengyu Miao, Wenchao Zhao, Yong Zhang

The increased thickness of the coal seam leads to higher goaf roof collapse height. In contrast, the dynamic pressure from the mining of ultra-thick coal seams generates higher abutment pressures around the mined area and may affect the stability of roadways servicing these panels. To mitigate the deformation and damage issues in the roadways during the extraction of ultra-thick coal seams under a high depth of cover, researchers have proposed combining high prestress constant resistance support and roof-cutting technology (HPCR-RC). The deformation and failure mechanisms of the roadways during the extraction of ultra-thick coal seams under a high depth of cover, along with the mechanisms and field control effects of the combined support system, have been analyzed through theoretical analysis, numerical simulation, and field experiments. The research findings reveal that the high in situ stress, initial excavation disturbance, rotation, and subsidence of the fractured roof of the extra-thick coal seam led to significant deformation and damage in the roadways. High prestress constant resistance support compensates for the initial stress loss, reduces initial stress concentration, and absorbs deformation energy. Moreover, the roof-cutting technology severs the connection between the goaf roof and the roadway roof, disrupts the path of stress transfer, raises the level of roof backfilling in the goaf, and provides support to the roof, effectively alleviating the pressure on the coal pillar ahead and adjacent to the working face. Field experiments have confirmed the effectiveness of HPCR-RC, as indicated by a substantial decrease in surrounding rock deformation and support pressure within the roadways.

Sep 25, 2023

By W. L. Price

Since first introduced in the United States in 1964, rail mounted bucket wheel stacker-reclaimers have gained wide acceptance by users. The coal burning power plant group has adopted this new storage tool most quickly. The actual history is traced in this area in some detail. Installations in phosphate and steel mill ore storage and a listing of present users are included.

Jan 1, 1969

By D. G. Chedgy

Environmental improvement efforts are focusing with increasing intensity on pollutants resulting from combustion. The high cost of removing these pollutants at the power station is well documented. Physical coal cleaning has always been and should remain the most economic method of reducing sulfur oxide emission from coal combustion. It is critical in the selection of preparation plant circuitry to consider capital and operating costs, as well as the level of sulfur reduction. This paper describes the technical criteria which must be used for efficient process selection and summarizes the cleaning systems available or in development.

Jan 1, 1990

By Murat Erdemoğlu, Turan Uysal, Thierno Saidou Barry, Mustafa Birinci

The rapid development of the global alumina and aluminum industry is straight coupled with the demands and the needs of these materials. Nowadays, the only well-known accessible resources to produce alumina and aluminum are bauxite ores. But bauxite ores are limited, and the remaining exploitable reserves do not have high contents in alumina. In countries where there is little or no bauxite reserves or where the recovery of existing bauxite ores to produce alumina with the Bayer process are not economic, alternative resources for alumina have been explored. The most attractive resources for replacing bauxites are aluminosilicate clay minerals and coal fly ash. The important processes developed for the recovery of alumina from these sources are acid leaching and alkaline leaching processes. The acid leaching is known as the most efficient in which thermal and mechanical activation are included for improving the performance of the process. The objective of this review is to give a comprehensive insight on the production of the alumina from thermally or mechanically activated clays and coal fly ash by hydrochloric, sulfuric, and nitric acid leaching processes.

By A. G. Belova

With the federal climate change legislation in progress, there is a need for demonstration-stage technologies aimed at providing clean energy from coal. Our research aims to experimentally illustrate the feasibility of capturing CO2 on a novel sorbent system from a gaseous stream. The gas is then released resulting in a regenerated sorbent and a pressurized stream of pure CO2 to be used for storage. The proposed sorbent is a ceramic honey-comb structured monolith coated with CaO supported on a high-surface area alumina. CaO is a natural acceptor of CO2 and our design ensures the physical stability and chemical reactivity of CaO over a large number of CO2 capture/release cycles. Furthermore, the use of the monolith ensures a uniform flow through the reactor, minimizes pressure drop across the reactor, and maximizes the surface reactive area. In this paper, we will present the results from a flow-through laboratory-scale reactor that establishes the efficiency of the proposed system to capture CO2. Future applications of the reactor include integration within the new-generation coal gasification power plants, such as IGGC, as means of providing decarbonized electricity.

Jan 1, 2010

By Ronald R. Bauer

Wollastonite is a little known industrial mineral of the silicate group. The largest and purest known deposit in the free world is being mined and beneficiated in Millsboro, New York by NYCO, A Division of Processed Minerals Incorporated. The associated garnet and diopside are separated from the wollastonite using dry high intensity magnetic separators. Beneficiated wollastonite is used extensively as an additive and filler in the ceramic, paint, refractory, and wallboard industries. Wollastonite acts as a functional filler due to its unique chemistry and physical acicularity.

Jan 1, 1982

By B. Mishra, Q. Shi

Numerical simulations have been used to investigate roof fall in the past decades. Comparing to the continuum based methods, the discrete element method has been well recognized for its excellent performance in simulating large strain problems and fracturing processes in the rock mass. However, the discrete element method has its limitations. When simulating a large-scale problem, a large number of particles are required, which consumes significant computational resources. In the present study, a 3D numerical model coupled with the finite-difference method (FDM) and the discreteelement method (DEM) was created to simulate the laminated roof failure in an eastern coal mine in the US. In the FDM-DEM coupled model, the laminated roof of the entry is represented by an assembly of bonded particles using PFC3D. The laminated roof is simulated by adding parallel discontinuities. The discontinuities are given certain stiffness and strength in the model. The ribs, floor, and far-field surrounding rock are represented by continuum zones using FLAC3D. The strength of the discontinuities is varied sequentially and the fracturing of the laminated roof was analyzed with respect to entry advance. The results showed that the laminated roof fractures along the discontinuities while an intact roof fractures in a dome shape. Increasing the strength of discontinuity could enlarge the tensile zone inside the laminated roof and hence change the crack distribution. In addition, the crack quantity in the laminated roof behind the advancing face decreases with the increment of discontinuity strength while this trend is not occurring ahead of the advancing face. The simulation demonstrated that coupled method using PFC3D/FLAC3D can reproduce the laminated roof failure in underground coal mines.

Mar 2, 2022

By Andrew J. Petruska, Rik Banerjee

This study explores implementing a machine learningbased system to generate a 3D surface repre- sentation of the roof and support straps in the mine. Event cameras have been chosen for their performance in high-dynamic-range lighting conditions and for their low latency. To enable automated drilling and bolting, 3D vision using eventbased cameras has been developed. A ground-truth set is created using two, time-synced event cameras and a LiDAR camera. These sensors are used to construct a ground-truth dataset of corresponding event- camera images and surface maps from the LiDAR. The network is tested with stereopairs of event images and produces a depth image with ±5 mm RMS error on average across 1000 test images.

Feb 1, 2024

By Anastasia Xenaki, Edmundo Laporte, Antonio Nieto, Jesus Castillo Gomez, Oscar Velasquez

It is particularly challenging for the mining industry to create and implement an efficient and adaptable mining innovation model to secure the continuous improvement of processes and products via technology. Human resource departments must play a vital role in shifting the mining culture, enabling these new classes of digitally skilled professionals to manage the mining operations of the future. This paper proposes the implementation of a concept based on the 5S mining innovation model ((a) Nieto, 2019), in a coal mining project in Central Asia, Mongolia. Practical and empirical evidence suggests that the model could serve as a roadmap to developing technologies and methods for the mines of the future.

Feb 1, 2023