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By Qiang Wang, Jiaqiang Yu, Chunhui Fan, Yong Wang, Changyu Jin, Jun Bai, Yu Lu

Accurate ore blending necessitates an in-depth understanding of movement trajectories of fragments and the spatial evolution of the displacement field in the bench during blasting, Accurate ore blending is currently one of the most complex challenges faced by mining engineers. In light of this problem, a systematic study was conducted in this paper using neural network and numerical simulation based on field monitoring data. A nonlinear mapping relationship was established between the mechanical parameters of rock mass and the displacements of the monitoring points. The measured displacements of monitoring points under blasting were input into the neural network, which used back-calculation to derive the mechanical properties of the rock mass. These parameters were then applied in a forward calculation to analyze the movement trajectory of the monitoring points. The results showed that the calculated displacements were in good agreement with the monitoring results during the. The average relative errors in the horizontal and vertical displacements were 4.12% and 15.2%, respectively. Furthermore, the muckpile profile was in an inverted recumbent “S” shape after bench blasting, which was consistent with the actual shape of the muckpile. This verified the rationality and accuracy of the method proposed in this study. Finally, the movement trajectories of particles in the bench and the spatial evolution law of the displacement field during bench blasting were determined based on the calculation results, offering theoretical support and fundamental information for accurate ore blending.

Dec 16, 2023

By Aidan Giblett

"It is important to make a clear distinction on the scope of work of the Global Mining Standards and Guidelines (GMSG) guideline for sampling grinding circuits. Many mineral processing practitioners are familiar with the sampling and surveying of comminution circuits, in particular grinding circuits, for performance diagnosis and the identification of optimization potential. These surveys often provide information for population balance modelling of individual comminution and classification unit processes, and consequently require a large amount of information to calibrate and validate the unit models. As a result, these surveys are labour intensive, somewhat expensive, depending on internal capabilities of the mine site or company and have a long time span from initial planning to final reporting. They also require a high level of expertise to process the survey data, simulate the circuit and make sensible recommendations on follow up actions.As a result of these factors, full grinding circuit surveys are not a common occurrence at a large number of processing facilities, and several years may pass before follow up surveys are conducted. In the ensuing gap between surveys, the efficiency of the grinding circuit must often be taken on faith, and this is considered an unacceptable lapse in an environment of strained natural resources and low commodity prices.To support the rapid and productive energy efficiency analysis being promoted by the ICE working group, a much simplified survey and analysis process is required. The process reflected in the GMSG guideline is indeed more conducive to frequent analysis, at a skill level that is well within the capabilities of the average plant metallurgist. As a result, it becomes feasible to conduct mini-surveys of plant performance, which can be used to quickly and precisely diagnose the high level impact of process changes. These methods can also be manipulated by an experienced practitioner to provide sufficient information for modelling of the circuit to estimate the impact of process changes, allowing an initial rate and rank exercise to focus plant optimization efforts."

Jan 1, 2015

By R. Kealey, D. Huo, Q. Zhang, Y. A. Sari

Greenhouse gas (GHG) emissions from primary mineral and metal production account for ~10% of global GHG emissions. One of the main sources of GHG emissions in mining operations is fuel consumption by haul trucks. Given their size and carrying capacity, the fuel consumption of haul trucks can approach 250 liters per hour. An average of 30% of the idle time of the trucks is spent while waiting in the queue. Inefficient truck dispatch planning can waste resources, cause dilution and elevate GHG emissions. In this research, a machine learning based truck dispatch approach was developed to dynamically route the haul trucks based on the loaded material, the road traffic, the estimated wait time, and the maintenance needs of the trucks. The GHG reduction potential of this smart fleet management approach was estimated by calculating and comparing the related carbon emissions versus scenarios using traditional fleet allocation approaches. Results suggest that this dynamic fleet allocation approach can significantly reduce GHG emissions at mineral production sites by optimizing waiting times and the overall distance travelled while achieving the same production levels.

Mar 2, 2022

Several years ago, North American mining companies began to realize they needed to expand their spheres to remain viable. This strategy has been successful, according to Robert W. Schafer. Today, companies from other continents have also recognized the need for an international view for long-term growth and viability, he said. Schafer is vice president for exploration with Kinross Gold. He was the program chairman and moderator of the keynote session at the 1997 SME annual meeting, held in Denver, CO, Feb. 23-27. The theme of the meeting was "Minerals - Serving the Global Community." A record attendance of more than 6,000 people participated in the meeting, which featured 415 exhibitors occupying 582 booths. The title of the keynote session was "Corporate Perspectives on a Global Minerals Industry." Each of the three keynote speakers discussed a different perspective of a global minerals industry.

Jan 1, 1997

By B. Pesic

The recovery of silver and gallium from flue dust with acidified thiourea solutions was examined. The studied parameters were temperature, particle size, thiourea concentration, acid concentration, and the presence of oxidants. The study of the extraction of these two metals was undertaken in sulfuric acid medium. Silver dissolution was dependent on all examined parameters, whereas gallium extraction was only dependent on the initial acid concentration. The experimental results suggest a new very efficient method for recovery of both silver and gallium. Almost complete recovery of silver and gallium can be accomplished within 90 minutes. A technological scheme for recovery of both metals is also proposed.

Jan 1, 1986

By Simon Strong, Tim Brown, Luis Ignacio Sanz Vivanco

"One of the most significant technical and practical challenges facing the tunnel construction team on the Legacy Way road tunnel project in Brisbane, Australia was how to erect the pre-stressed precast concrete slabs to form the smoke duct in the tunnel boring machine (TBM) tunnels. An essential part of the tunnel ventilation system, the smoke duct, extends the full length of the 4.6km long twin, two lane tunnels. The vast majority of the tunnels (approx. 4.3km) were constructed using two 12.4m diameter double shield TBMs. The refurbished Herrenknecht machines broke several world records on the way to completing the tunnel excavation works in just over nine months. With the excavation complete the focus turned to solving the complex civil tunnel fit out challenges. A key component of the civil fit out of the tunnels was constructing the smoke duct in the TBM tunnels which was designed as a precast solution. The slabs which each measure 8.62m long by 2.0m wide by 200mm thick and weigh close to 9 tonne need to be erected above cast in situ corbels whilst other tunnel finishing works continue. The space proofing clearance offered by the design to the support corbels below and the precast segmental lining above was in the order of only 100mm. This paper details the events of how the Transcity JV tunnel fit out team, comprising some of Europe and Australia’s leading tunnel construction specialists, drew upon the global strengths of the existing JV member companies and the global reach of leading TBM manufacturer Herrenknecht to develop an innovative system to solve this challenging problem. This globetrotting story, which starts in Australia, visits Europe and mainland China before returning to Brisbane where it all began."

Jan 1, 2016

By Janusz Szywacz, Bozena Bojko, Stanislaw Wasilewski

Two groups of computer programs are described in the paper. First one is the OWEN system containing software modules designed for air flow distribution analysis and prediction within the whole ventilation network of a mine. The second group is a set of programs commonly used in a routine design work connected with chosing the optimal ventilation schemes and equipment for individual areas of a mine (headings. longwall districts etc). All the programs are designed for running on the IBM PC/XT, IBM PC/AT and compatible computer systems.

Jan 1, 1989

By Patricio A. Riveros

Various types of commercial ion exchange resins were evaluated with respect to their ability to extract gold from cyanide leach solutions. Large differences were found among the various resins in terms of selectivity and gold loading. The hydrophi­licity and the charge density appear to be the main factors that determine the resin characteristics. Polystyrene weak-base resins, such as Dowex MWA-1, exhibited the best all-round performance.

Jan 1, 1990

By T. Sun, J. Kou, D. Tao

"The reduction behavior of low-grade lump hematite ore (100% 20-50 mm) has been evaluated by performing a series of coal-based direct reduction roasting tests followed by magnetic separation under different process conditions such as roasting time, temperature, reductant type and dosage, and grinding stage. To investigate mineralogical transformation and reduction characteristics of lump hematite ore, roasted ores and magnetic concentrates were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive spectrometer (EDS) and polarizing microscope. The results have shown that a magnetic concentrate with a total iron (TFe) grade of 90.7% was produced at an iron recovery of 83.9% when lump hematite ore was reduced at 1,200° C for five hours using 35% lignite as a reductant followed by two stages of grinding, for 20 min and 30 min each, and low-intensity magnetic separation. The degree of reduction is closely related to the change in the internal structure of the roasted ore. Lignite with a higher fixed carbon content and lower ash generated roasted ore with a more highly porous structure, which provides better permeability of reducing gas. Magnetite, fayalite and wustite were the dominant intermediates of coal-based direct reduction of lump hematite ore. Parts of wustite reacted with SiO2 or Al2O3 in gangue and generated fayalite or hercynite. FeO in fayalite was replaced by CaO to produce wustite, which was finally reduced to metallic iron. However, Fe in fayalite and hercynite produced with low contents of CaO cannot be reduced into metallic iron. Introduction Low-grade hematite ore, characterized by low Fe content and high SiO2 content, cannot be treated by traditional mineral processing methods due to its nonmagnetic property and fine liberation size. The direct reduction (DR) roasting process has been studied and proven satisfactory in treating difficult-toprocess ores, such as low-grade nickel laterite oxide ore (O’Connor et al., 2006; Cao et al., 2010; Guo et al., 2011), high phosphorus oolitic hematite ore (Li et al., 2012; Yu et al., 2013), low-grade hematite ore (Wei et al., 2013;) and iron ore tailings (Li et al., 2010), which greatly expand the resources of usable iron ores (Srivastava and Kawatra, 2009). Therefore, the use of a DR process to treat low-grade hematite ore to produce direct reduced iron (DRI) is of great interest to many researchers of mineral processing and metallurgy (Weissberger et al., 1986)."

Jan 1, 2015

By Charles H. Minott, Michael J. Markow, Robert D. Wyatt, Fred Moavenzadeh

The substantial investment in tunnels anticipated in the next twenty years has focused new attention on the economics of tunnel construction itself and on some costly problems associated with underground work: the uncertain geologic conditions, the performance and adaptability of men and equipment, and the need for quicker, more efficient excavation methods. There also exists a need to develop better ways of estimating tunnel construction. Inaccuracies in current bid estimates stem from a number of causes, among them (1) the effects of geologic conditions, which are not adequately known prior to construction, (2) the dependence of actual cost on the construction method used and on the interactions among the operations occurring underground, and (3) the reliability of tunneling equipment. Inability to estimate final costs for conventional tunneling more accurately has in turn caused difficulty in gauging the costs and benefits attributable to new tunneling technologies either under development or for which R&D programs are planned. ATTRIBUTES OF THE TUNNEL COST MODEL This paper presents a computer based Tunnel Cost Model (TCM) which quantitatively assesses the uncertainties inherent in underground work, and is detailed enough to aid in preparing estimates or bids. The model employs appropriate techniques of subjective (or "degree of belief") probability and computer simulation of tunnel construction operations to estimate distributions of total tunnel

Jan 1, 1974

By William W. Kephart

Brockway Glass Company, Inc., manufactures glass containers at fourteen plants located in nine states. The relatively high place value of the major glass batch components dictates that raw material supplies be obtained from numerous sources in the United States and Canada. One objective of our central composition control program is to arrive at a glass composition with similar physical properties at each of our plant locations. This requires that adjustments be made in the batch compositions to compensate for chemical variations from one raw material source to another. Minor chemical variations will occur in sand, limestone, and dolomite from one source to another. Major variations are present in the alumina sources because of the diverse rock types utilized.

Jan 1, 1973

By Malte J. M. Gurgel, Axel Preusse

The planning, construction, and monitoring of underground storage facilities is a key factor in meeting upcoming challenges as part of the energy transition from fossil fuels to renewables. Therefore, the many years of knowledge and expertise in ground control gained from coal mining are highly valuable for new mining and storage operations. For such applications, our previous work examined cavity registration, combining structure from motion and LiDAR through a case study in a former lead ore mine. Building on this, the results of this recent case study are discussed regarding the possible application in sites for nuclear waste disposal in Germany including a view on the situation in the United States. Photogrammetric methods are particularly suitable as part of long-term monitoring, which relies on both precise survey results and a large variety of detailed visualization. In order to gain a better understanding of the resulting application potential for holistic monitoring, both existing repositories sites in Germany and ones yet to be found are examined. This search and selection process for high-level nuclear waste disposal is studied in detail together with rules resulting from the (German) mining law, regulations, and other guidelines. Hereby, key requirements of photogrammetric products like oriented images, point clouds, and three-dimensional (3- D) models are identified for different case studies. The findings on accuracy and integrity of the generated models are not only of interest for future repository sites or underground pumped storage power plants, but also offers various possibilities for underground mining of coal and other commodities.

Jul 1, 2023

By A. A. Compoli

Injecting water under pressure to wet the coalbed in advance of mining reduces mining-generated respirable dust. Owing to economic and geological barriers, water infusion for longwall dust control in the United States is currently limited to the Pocahontas No.3 Coalbed in Virginia. Water is pumped into the coalbed through underground boreholes drilled horizontally from the headgate toward the tailgate side of retreat longwall panels. This paper theorizes that the barriers to widespread utilization of water infusion for longwall dust control could be overcome by long-duration, low-pressure water infusion through vertical gob gas boreholes. Currently, 43% of the 72longwall mines in the United States employ vertical gob gas boreholes. Computer coalbed reservoir simulation suggests that one vertical surface borehole could infuse the same longwall panel area as four horizontal boreholes in the current water infusion system for longwall dust control in the Pocahontas No.3 Coalbed.

Jan 1, 1995

By QU Hong-lue, YANG Lin-han

Aiming at the subjective impact caused by subjective weighting method in the establishment of rockburst risk attribute identification and prediction model, the combined weighting method was introduced to eliminate the influence of unreasonable weight of each index. Eight discriminant indexes affecting the risk of rockburst were selected. Through the literature review, relevant rockburst cases were collected and 8 index rockburst sample sets were established. A variety of machine learning methods were used to analyze the feature importance of discriminant indexes in the samples, and then to determine the objective weight values of different methods. Combined with the subjective weights determined by the Analytic Hierarchy Process, the combination of weights were successively carried out. Based on the attribute recognition theory, the combination weights with different objective weight methods were established to identify the rockburst risk attributes, and verified by the confidence criterion. The results show that the objective weight value determined by the feature importance analysis of machine learning reduces the subjectivity of the weight of Analytic Hierarchy Process method, improves the prediction accuracy, and makes the prediction result closer to the fact.

Apr 26, 2022

By Steven E. Mischler, Jay F. Colinet

The Mine Safety and Health Administration (MSHA) promulgated a rule in 2014 that required numerous changes in compliance dust sampling requirements for coal mine operators. Two key parts of this rule were the lowering of the respirable coal mine dust standard from 2.0 mg/m3 to 1.5 mg/m3 and requiring operators of underground coal mines to use a continuous personal dust monitor (CPDM) for compliance sampling. The CPDM currently approved for compliance sampling is equipped with a display that provides miners with in-shift information on their respirable dust exposure. The goal was to provide an indication of a potential overexposure and empower the miner and mine operator to implement changes in controls and/or operating practices to prevent an overexposure from occurring.

By J. J. Komadina

Since the advent of resin-in-pulp (RIP) technology for treatment of uranium-bearing ores in the 1950?s to current carbon-in-pulp (CIP) processing of gold values, metallurgies and operators alike have wrestled with the problem of interstage screening. Early gold CIP plants such as at Homestake utilized externally mounted vibrating screens in conjunction with air lifts to effect carbon-pulp disengagement. Other operations world-wide have likewise adopted this technique with varying degrees of success. Subsequent development of in-tank launder screens both in South Africa and the United States have been of the air cleaned variety (EPAC)

Jan 1, 1988

By C. J. Webb

Abandoned uranium mines in the southern Black Hills of South Dakota were sampled for uranium, radium, and rare earth elements during 1992 and 1993. Analyses of water samples from several shallow ponds in the mine pits showed pH values between 3 and 4 with uranium concentrations between 1600 and 2600 ppb. Rare earth elements and their respective isotopes were analyzed with an inductively coupled plasma mass spectrometer and were referenced to a shale normalization pattern. All samples showed an enrichment in the middle rare earth elements. Rare earth levels often were greater than 0.2 ppm. At one site, the concentrations of lanthanides were 150,000 times above background levels. While the southern Black Hills have long been known for rich uranium ore deposits, these analyses show that significant levels of rare earth elements also are present, indicating that the potential exist for future development.

Jan 1, 1995

By Martino Scialpi, Miriam Piemontese, Claudio Cimiotti, Matt Kendall, Nicholas Karlin, Roberto Schuerch

The Los Angeles, California JWPCP effluent outfall tunnel will transport secondary-treated effluent from the Joint Water Pollution Control Plant in Carson to the White Point Manifold. Upon completion, through ground conditions ranging from soils to hard rock, the tunnel will be approx. 7 miles (11 km) long with a finished internal diameter of 18-ft (5.5 m). This paper will present the Tunneling Condition Assessment Report (TCAR) and Tunnel Operation Plan (TOP) developed prior to construction, as well as the actual TBM performances achieved along the northern portion of the alignment in soft ground, shallow cover, and beneath a densely urbanized area.

Jun 23, 2024

By Jr. Raleigh

In a cooperative agreement between the U.S. Bureau of Mines and the U.S. Department of Energy, laboratory column-flotation tests were conducted to evaluate fluorosurfactants as selective fine coal flotation collectors. A Middle Kittaning seam coal responded to flotation with both anionic and nonionic fluorosurfactants. These fluorosurfactants were no more selective than MIBC alone. However, for increasing coal yields, nonionic fluorosurfactant systems did not increase total sulfur and ash contents as sharply as MIBC systems. Flotation selectivity also improved slightly when a combined anionic fluorosurfactant-MIBC system was used in acidic pulps (pH < 3.6). While the fluorosurfactants examined will not likely have direct application in current coal flotation practice, other fluorosurfactant systems could eventually prove beneficial for floating fine coals.

Jan 1, 1990

By J. Stachulak

This paper deals with theoretical considerations and practical applications of ventilation network calculations, based on mass flow rates and performed by computer simulation in our deepest operating mine - Creighton. The paper also deals with natural ventilation. In the usually accepted air-flow theory, the air is assumed to behave like an incompresssible medium. This introduces considerable error where temperature and pressure changes are great. Therefore, any study of the air flow in deep mines, must take into account compressibility. Basing ventilation calculations on mass flow allows a distinction to be made between air leakage and such quantity changes which occur due to air density changes. The energy which is required to convey one pound of air through a mine can be obtained by adding all head losses hL (ft-lb) of the ventilation paths through which the air flows. However, this total energy will not be correctly expressed in a compressible fluid by summing all pressure losses PL = hL x d (ft-lb/ft3 = lb/ft2) d = density. There is a law of mass conservation, but no law of volume conservation. Natural ventilation is caused by the conversion of heat into mechanical energy and not by the difference in upcast and downcast densities, as often believed. In an existing mine natural ventilation can be determined correctly by plotting a pressure volume diagram and measuring the area ? [ ] vdP = hN, where v = specific volume, or by measuring the sum of all friction losses and work provided by a fan. These procedures are tedious. The natural ventilation head (hN) can be approximated by the equaticn hN =[ ] tdZ. Where T is the average absolute temperature, t air temperature and Z elevation. In Prof. R. Greuer&apos;s computer program this determination of hN is automatically done for every mesh of the network.

Jan 1, 1980