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By S. W. Jacobsz, F. O. Abimaje

Internal stability is a key consideration in the design and long-term performance of granular filters, as it precludes particle migration and internal erosion. This study evaluates the internal stability of coal discard material in coal co-disposal facilities. Reusing coal discards could reduce mine waste volumes and mitigate associated environmental impacts. However, coal discard material differs from most soils in terms of particle strength and density, with possible implications for hydraulic stability. Laboratory seepage tests were conducted on coal discard material under varying void ratios, subjected to a range of hydraulic gradients, and the results were used to confirm the applicability of the widely used empirical Kenney and Lau filter criterion to coal discard. Findings revealed that particle loss increased with higher void ratios. Nonetheless, particle migration remained minimal, with a maximum particle loss of only 0.2%, suggesting that coal discard exhibits sound internal stability under the tested conditions.

Jul 3, 2026

By R. Minnitt , D. Fourie, P. le Roux

This study proposes that the moving search neighbourhood used in ordinary kriging selects a subset of data surrounding each estimation block, and that this subset represents a local subpopulation of which the distributional parameters can be used to determine local, spatially-adaptive outlier capping values. This paper introduces a distance-weighted capping method applied within the kriging search ellipse after kriging weight calculation, transitioning from one-dimensional point estimation to two-dimensional block estimation for Witwatersrand-type gold deposits. Accurate ore grade estimation is essential for mine planning and economic evaluation, particularly in deep-level gold mines where extreme grade values (outliers) may distort resource assessments. Traditional capping methods, which apply a uniform threshold to outliers, often fail to account for spatial and geological variability, leading to biased estimates. A high-resolution simulation generates a synthetic ‘ground truth’ orebody, subsampled to mimic real-world data scarcity. A two-parameter lognormal distribution models grade variability, with capping values optimised by minimising the mean squared error between estimated and simulated block grades. Comparative analyses against traditional capping techniques demonstrate that the dynamic method improves regression fit, reduces conditional bias, and aligns more closely with production reconciliation data. Validation using swath plots, QQ-plots, and mine call factor comparisons confirms that the spatially adaptive capping technique mitigates over- and under-estimation, particularly in high-grade zones. Results indicate superior performance over conventional domain capping, with higher R² values and better alignment with actual production metrics. This approach offers a reproducible, scientifically rigorous framework for resource estimation, reducing reliance on rigid sub-domaining while enhancing decision-making in complex ore bodies. The study underscores the importance of integrating geological information with advanced geostatistics to optimise grade estimation and mine planning.

Jul 3, 2026

By Taylor K. Kruger, A. H. Basson , S. Fataar

The mining industry remains heavily reliant on mineworkers, whose working conditions are typically more arduous than in most industries. With recent technological developments in mining and other industries focusing on the digitalisation of workspaces, mineworker safety should be at the forefront of the digital transformation. Underground mines should be viewed – and developed – as human cyber-physical systems, where digital technologies are integrated with human roles to enhance safety and coordination. Contributing to this vision, this paper presents a set of functional requirements to guide the development of human cyber-physical systems that improve the safety of mineworkers in underground mines. The formulation of the functional requirements is informed by an analysis of the current context of underground mines and an exploration of opportunities for improved human-system integration within such environments. The functional requirements are related to the real underground mining context through an illustrative example, which demonstrates how a human cyber-physical system could monitor mineworker and environment states, perform predictive safety analyses, and coordinate operations. The proposed functional requirements serve as a starting point for the development of human cyber-physical systems within complex underground mining environments; however, further research (supported by real case studies) is required to refine and obtain specific target values for the functional requirements, and to formulate accompanying performance requirements.

Jul 3, 2026

By Karen Dawson, Qiang Li

Unreinforced displacement augercast piles, or rigid inclusions (RIs), were installed for foundation support of a combined sewer overflow treatment building. The RIs penetrated loose silty sand and soft silt and terminated in medium-dense to dense silty sand, approximately 40 ft below grade. The building houses water-holding basins and level-sensitive weirs and equipment. Strain gage-instrumented static axial load tests and low strain pile integrity tests (PIT) were conducted on the RIs as part of quality control for this technology. Strain gage monitoring continued during the installation of the remaining production RIs, construction of the building, and water preloading of basins and channels within the building. While the composite RI-reinforced ground and load distribution mat system performed as expected for settlement control and was not needed for lateral support, RI fractures as observed by PIT in this project might need to be controlled in other situations. Case history information regarding the subsurface fill and deltaic deposit character, RI installation production rates, RI testing procedures and results, and construction settlement monitoring are presented.

Oct 31, 2023

By Max Ho, Hiu Lee

The Port Lands in Downtown Toronto is a vast waterfront area that has been long remained undeveloped. This is due to the dual challenges of soil contamination resulting from decades of industrial activities and high flooding potential from the nearby Don River. The Port Lands Flood Protection and Enabling Infrastructure Project (PLFP) seeks to unlock the development potential of this strategic downtown land. This initiative also simultaneously mitigating flood risks for the Port Lands and surrounding areas. The project involves the creation of a new river channel through the existing Port Lands to redirect floodwaters into the inner harbor and Lake Ontario. This new river channel excavation is protected by three dam liked plug walls which isolate the lake water from entering the excavation. Given the industrial contamination in the soil, the installation of a permanent cut-off wall along the new river alignment is also imperative to isolate contaminants from migrating into the future river channel. The west plug wall is positioned at the westernmost point of the river channel excavation and directly adjacent to Lake Ontario. The innovative use of a diaphragm wall technique to construct the west plug wall allow the wall to serve as a dock wall, dam, excavation support, cut-off wall, and load-bearing element throughout the different stages of the river excavation. This paper provides a comprehensive overview of the design and installation of the west plug wall. It provides valuable insights into the practical application of diaphragm walls and how it helps deliver this complex urban flood protection and infrastructure projects.

Oct 7, 2024

By Marcel Martineau, Vincent Landry, Simon Didone Arseneau, Ali Fallah Yeznabad, Damien Lamblot, Mathieu Cattone, Habib Akande, Marion Bouet

Vaudreuil-Soulanges Hospital Center in Greater Montreal area is a substantially large construction project with challenging schedule and geological conditions. The foundation consisted of 519 piles with an average overburden of 15 m and 4.5 rock sockets that were constructed in a tight schedule of 9 months. Special Geotechnical considerations were required and adopted for design and construction of this large-scale foundation. In this Design and Build contract, the strong cooperation between the designer and the contractor resulted in a substantial optimization of the quantities through in-situ full-scale vertical static and lateral cyclic pile-load tests, seismic simulations in design of the piles, and orienting the design to fit the planned drilling method. To maintain a challenging schedule in a cost-effective manner, seven drilling rigs fitted with temporary casings were used, operating in two shifts up to seven days a week. For drilling of the piles, cluster drilling was used by contractor due to uncommon abrasiveness and high strength (> 200 MPa) of the encountered sandstone bedrock. To further assist the construction of the piles, a new concrete mix was developed specifically for this project for the purpose of tremie pours. The concrete mix design is based on optimizing its rheology, maintaining its workability up to 6 hours and its durability more than 75 years design life in a particularly aggressive environment in chloride, sulfate, and others aggressive ions. An effective quality control and assurance program made it possible to find optimal solutions during construction.

Oct 7, 2024

By L. Xingwana

Mining operations face challenges like declining ore grades, rising costs, labour shortages, and aging infrastructure, necessitating increased efficiency. However, achieving operational efficiency in underground mining is complicated by inherent limitations, non-value-adding tasks, and inconsistent methodologies. This study examines the application of the integrated operational excellence model to improve operational efficiency in South African gold mining operations. The research conducted a combined quantitative and qualitative analysis, presenting a framework that illustrates the application of the theory of constraints and Lean Six Sigma in enhancing operational efficiency and excellence within the mining sector over six months in 2018. The study identifies key limitations, inefficiencies, and inconsistencies that impede operational excellence within the integrated operational excellence model. Successful implementation requires a deep understanding of the interdependencies between personnel, processes, and technology. These insights are valuable for mining executives, engineers, and policymakers seeking to modernise operations and improve sustainable productivity. Furthermore, the research paves the way for broader adoption of integrated excellence frameworks across South Africa's mining sector.

Jul 3, 2026

By Erich Steinlechner, Freddy Lopez

The Rhine, with its length of approx­imately 1,230 km (764 mi), is the second-longest river in Central and Western Europe and one of the most important navigable waterways in the world. The alpine Rhine (or Alpenrhein) is the section of the river between Reichenau, Switzerland, and the Rhine's confluence with Lake Con­stance on the borders of Germany, Austria and Switzerland. A Swiss­Austrian flood control project known locally as RHESI aims to protect the habitat of about 300,000 people living in the valley along the "international stream" of the alpine Rhine. Along the international stream, the Rhine flows within a central channel toward Lake Constance in a canal-type bed with fortified embankments. In the event of rising water levels, the Rhine floods the foreland, stressing the existing flood embankments (dams). In order to allow even larger amounts of water to flow off safely, more space and new (or rehabilitated) dams are re- quired. With the implementation of the RHESI project, the middle channel of the Rhine will be significantly widened, and the foreland reduced, creating more space for the river. Around 65% of the flood embankments will be rehabili- tated and 25% completely renewed, while 10% of the dams will remain as they are today. These measures will increase the discharge capacity from the current 100-year to a 300-year flood rate. More discharge capacity means better protection against flood events.

Jul 1, 2024

By Blaise Fettig

Santa Cruz Mountains, Ben Lomond, CA Vortex Project Sponsor- Blaise Fettig Vortex PM- Peter Dworetzky Obayashi Corp (Prime Contractor) PM- Kenji Yamauchi ABSTRACT: The City of Santa Cruz Water Department in California replaced the existing Newell Creek Dam inlet/outlet works. The existing inlet/outlet works included a deteriorated 36-inch diameter pipeline under the dam and other components that did not meet current California DSOD dam safety reservoir drawdown requirements. To maintain the reservoir, the City’s engineer designed a new inlet/outlet works that could be constructed under full reservoir conditions, in water up to 115 feet deep. The underwater work began with the dredging of an “amphitheater” on the native 2:1 rock slope. After dredging, three large, critically located benches were excavated into the rock slope with a heavy digging bucket and specialty designed underwater tools. A marine rail was constructed, on which three large concrete donuts were precast and lowered into the water before picking with a crane. These donuts were then installed and grouted in place on the excavated benches. Six foot diameter shafts were drilled through the hole at each inlet foundation donut to the tunnel intersect elevation, and steel casings were installed and grouted into each shaft. Divers installed the three intake structures at design elevations. These 30” intake structures were 30-inch standpipes with 30” diameter hydraulic valves and 48” diameter by 56” tall drum screens. The piping was connected to a 20” diameter air vent line which is designed to prevent vacuum conditions and plumbing to provide a minimum downstream flow. Once the shafts and intakes were in place, a new tunnel was advanced by the general contractor from the downstream right abutment to intercept the shafts. 30” CISS piles were installed to support the 20” vent line from the intake locations to the dam crest. These piles were drilled from barges. Divers then installed Vortex designed articulating pipe supports on the piles, and finally the vent pipe to shore.

Oct 7, 2024

By Jacob Blake, Dan Dwyer, Tulin Fuselier

The recent renovation of Boston City Hall’s Plaza, one of Boston’s premier public meeting spaces, involved heavy construction and grade changes over the country’s two oldest subway tunnels, built in 1898 and 1902. These tunnels presented unique challenges throughout the course of the design and significant logistical issues that had to be carefully managed during the construction process. Despite these challenges, the renovation of the Boston City Hall Plaza has been a major success. This paper aims to explore the successful outcome of the project, highlighting how effective teamwork and collaboration between Owner, Contractor and Engineer played a crucial role in overcoming the challenges faced during the project. The paper also intends to provide insights on how such collaborative efforts can lead to the achievement of a project's goals, despite the hurdles encountered along the way.

Oct 31, 2023

Since 2001, the Hybrid Stress Blast Model (HSBM) project members have developed a software suite to model the complete blasting process from non-ideal detonation to muck pile formation. To preserve the physics and improve solution time, the breakage engine uses a combination of analytical models and 2D axisym-metric finite differences to model near-field crushing, coupled to 3D discrete lattice fracturing and distinct element numerical methods to model throw and muck pile development. The model has been validated by comparison with laboratory and field tests in kimberlite. Multiple blasthole simulations are used to demonstrate how changes to blasting parameters can influence downstream efficiencies. Case studies of wall control blasting show that the presplit design must balance the two opposing effects of increased damage with increased charge and decreasing attenuation of the seismic waves with decreasing charge. Modelling of decoupled explosives needs further development. Reducing the charge towards the back of the trim blast results in a much more significant decrease in back damage than altering the timing. The model demonstrates how separation along the weaker planes in a jointed rock can coarsen the fragmentation, leading to inefficient beneficiation, and extends the damage to a distance of at least twice the burden behind from the blasthole, severely compromising the wall stability.

Jan 1, 2012

By Sidi Deng, Sharon Pedraza, Aaron Noble, Subodh Das, Bin Ji, Wencai Zhang, Michael Van Brunt

In this study, a MSWI bottom ash sample was assessed to evaluate the feasibility of various physical beneficiation processes in concentrating valuable elements prior to chemical leaching. The raw sample was initially assayed to determine the content and economic value of various metals present in the material. The potential recoverable value (PRV) of the sample was calculated, and the result showed that the total PRV of the sample was 483 $/ton, with Ti, Sc, Fe, Cu, and Zn being the most valuable metals. Next, various physical separation processes, including size fractionation, froth flotation, magnetic separation, and gravity separation, were conducted to determine the extent to which the valuable elements can be concentrated. The results were compiled into an element-by-beneficiation enrichment ratio (er) matrix that was used to develop suitable beneficiation flowsheets for further consideration. The result clearly show delineation of four products, including a Fe-rich product that can be isolated by magnetic separation (er = 5.0), a Cu/Zn-rich product that can be isolated by flotation (er = 5.3 to 9.4), a Sc-rich product that can be isolated by gravity separation (er = 0.6), and a Ti–rich product that is produced in the residue. Lastly, the leachability of valuable elements from the bottom ash sample was determined by acid leaching tests. The results indicated that it is viable to employ hydrometallurgical methods to recover and purify the valuable metals. This work provides a reference for the recovery of valuable metals from MSWI bottom ash from both the technical and economic aspects.

Apr 27, 2024

By Lars Hultman, Abu Yaya, Gabriel K. Nzulu, Per Eklund, Martin Magnuson, Prosper M. Nude, Hans Högberg

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons. org/licenses/by/4.0/.

Apr 3, 2024

By Aaron Noble, Mahmud Esad Uluer

Respirable coal mine dust (RCMD) is one of the biggest occupational health hazards for underground coal miners. Dusty mining environments can cause long-term health problems, including pneumoconiosis and progressive massive fibrosis. The Mine Safety and Health Administration (MSHA) has recently revised regulations promoting enhanced dust mitigation technologies, which have sparked renewed interest in the development of dust mitigation technologies. The flooded bed dust scrubber (FBS) is one of the most widely used technologies; however, it is limited by technical challenges, the most notable being the potential to clog. Recent studies have shown that applying vibration to filter mesh can improve the overall efficiency of the scrubber and that the system can be readily integrated to existing continuous mining equipment using an energy harvesting approach. In this follow-up study, the impact of mesh design and surface modification on system efficiency was examined using different vibrating liquid-coated stainless-steel mesh panels in a laboratory-scale FBS. Based on the two-way interaction data from a multi-factor experimental design, the results show that the performance of the system can be optimized by using hydrophilic 20- or 30-layer filters and by excitation frequencies between 67 and 134 Hz. This laboratory study suggests that a 20-layer mesh screen with hydrophilic surface applications and optimized vibration parameters can perform similar to that of a 30-layer static mesh, which is typically used in industrial units.

May 23, 2024

By Hong Yong Sohn, Xiaoyi Cai, Wei Wang, Liangzhao Mu, Fengqin Liu, Hongliang Zhao

Thebottom-blownsmeltingtechnologyhasbeenwidelyadoptedinnon-ferrousmetalsmeltingindustries.Thelargestbottomblown smelting furnace used in copper smelting was numerically simulated to improve the stirring effect in the molten bath by optimizing the oxygen injector arrangement and blowing parameters. The results show that a small injector spacing leads to gas jet coalescence, which is detrimental for smelting efficiency, increases copper loss and shortens furnace service life. Three schemes were proposed to improve the uneven stirring and reduce the gas jet coalescence by increasing the axial spacing of the injectors, the radial installation angle and the gas injection angle. Changing the axial spacing of the injectors can significantly reduce the gas jet coalescence, yielding the best stirring effect. The results of simulation suggested that when the axial spacing of the injectors was increased from 0.380 m to 0.610 m, the mean melt velocity in the mixing zone increased to 0.243 m/s, which was 20.9% higher than that before the optimization. Meanwhile the RSD (relative standard spatial deviation of melt velocity) decreased from 123% to 84%. In the actual production, the matte content in the smelting slag decreased from 6.57% to 3.12% after changing the axial spacing of the injectors from 0.380 m to 0.610 m.

Apr 10, 2024

By Danu Putra, Budi Sulistianto, Tri Karian, Mohammad Nur Heriawan

Stope layout optimization is an important feature of underground mining that maximizes the economic value of the project while taking mining limits into account. The large number of parameters and constraints makes it difficult to obtain the optimum condition. Several algorithms have been created to address these problems using a variety of methods. However, the circulating method has not explicitly included stope dimension stability analysis, resulting in a solution that is not stability-proven, which can result in a suboptimal solution. This study integrates the Mathews stability graph into the stope optimization algorithm so that the optimized stope layout considers stability conditions directly through an assessment of the available geomechanical data within the block model. The proposed algorithm is validated through a case study of a synthetic block model created by considering variations in grade and the geomechanical conditions of the rock. Furthermore, several scenarios are created to compare the performance of the algorithm that applies variations in stope sizes with the common case study of stope sizes that remain fixed. A more detailed assessment is also conducted on each final stope layout wall to ensure the successful application of stability analysis in the proposed algorithm through back analysis on the Mathews stability graph. The optimization results show that all walls in the final stope layout fall into the stable condition. Also, the proposed algorithm is also capable of maintaining the project’s economic value. Ultimately, the proposed algorithm can be deemed applicable and suitable for use in the initial stages of mining as a comprehensive assessment of the optimal stope layout, taking into account the stability conditions of the stope.

May 22, 2024

By Shankar Kumar, Arvind Kumar Mishra, Chitranjan Prasad Singh

Formulating a predictive model for blast-induced ground vibration (BIGV) has always been challenging due to the complex non-linear relationship between the BIGV and its influencing factors. Researchers have used empirical, artificial intelligence methods and numerical modelling methods to predict BIGV. In a dragline bench blasting, a massive quantity of explosives is used compared to other loading machinery, and the height of the bench depends on the size of the dragline. For effective utilization of explosives energy, decking is used to reduce the hazardous effects of blasting. In this paper, an attempt has been made for effective prediction of BIGV, and its mitigation on dragline bench blasting considering a deck length, stiffness ratio, hole spacing to burden ratio, hole depth to burden ratio, the distance of monitoring PPV from blasting site, Schmidt hammer rebound number of the bench to be blasted, and maximum charge per hole to total charge per blast. So artificial neural network (ANN) model and random forest (RF) model have been developed considering the parameters mentioned above. For the statistical performance of the predictive model, the coefficient of determination (R2) value is 0.8895, MSE is 22.84 for the ANN model, and the random forest (RF) model whose R2 is 0.8165 and MSE is 27.18. The sensitivity analysis results show that stiffness ratio, deck length, and Schmidt hammer rebound number are more influential parameters out of the selected parameters. The reduction of ground vibration with the introduction of decking led to a 3 to 15% reduction in ground vibration.

May 15, 2024

By A. A. El‑Midany, O. M. Asem, S. E. El‑Mofty, M. F. Abadir

Glauconite is a clay mineral that is most probably mined with phosphate and represents a challenge for phosphate upgrading by flotation. Reverse flotation is a common method for removing silica and silicate from siliceous phosphate. Thus, a systemic study was conducted to determine the effect of clay and its interactions with siliceous phosphate ore components on its cleaning by flotation. The flotation of each mineral (phosphate, quartz, and clay) was tested in terms of product recovery using quaternary amine at pH 9. In addition, the settling behavior of each mineral was investigated with and without quaternary amine. Binary and tertiary systems were studied to investigate the interactions between the main ore-containing minerals. The results of each mineral flotation test showed that quartz has the highest floatability, with low floatability of both phosphate and glauconite by quaternary amine. The presence of glauconite does not affect the phosphate recovery, whereas glauconite reduces the quartz floatability, which deteriorates the quartz removal from phosphate. Finally, the interaction mechanisms in the different systems are illustrated.

Apr 5, 2024

By Rendon Rieth, John Bryant, Kourosh Tamizdoust, Amr Helal

Expansive soils are widespread in the Southern, Western, and Rocky Mountain areas of the United States. Expansive natural clays and bedrock can expand upon wetting and shrink upon drying. These soils can cause damage to structures, roadways, and pipelines. Accurate estimation of volumetric deformation of expansive soils is critical to minimizing damage to the nation’s infrastructure. Free-field heave is the amount of movement the ground subsurface experiences due to wetting/drying of the soils within the active zone, with no surface surcharge load (e.g., foundation load) applied. Active zone is the depth below the ground where the soil volume deformation can still occur due to moisture/energy changes in unsaturated soils. Several methods for free-field heave estimation have been developed over the years including empirical methods and using oedometer swell test results and soil suction values. Further, in the past decade, most numerical studies have been performed to determine the free-field heave by incorporating hydro-mechanical framework which disregards the temperature effect and usually considers one-way coupling between the moisture flow and swelling/shrinkage deformation. The main objective of the current study is utilizing a strongly coupled thermo-hydro-mechanical (THM) model for the estimation of active zone depth and free-field heave when the soil is subjected to real-time climate conditions. The THM model, input thermal, and hydraulic/mechanical data are implemented in COMSOL Multiphysics software. The results are compared with experimental data from a case study in the Colorado Front Range area. The Soil-Water Characteristic Curve (SWCC) and Hydraulic Conductivity Function (HCF) are based on the Van Genuchten (VG) model and the mechanical constitutive model, which governs swelling deformation, is based on the Extended Barcelona Model. The THM model predicts the active zone reasonably well. Moreover, the simulation of free-field heave is compared with the analytical calculation produced by VOLFLO software.

Oct 31, 2023

By Seth Hamblin, Bill Oder, Les Chernauskas

Thermal Integrity Profiling is a non-destructive test method used on cast-in-place concrete deep foundation elements such as drilled shafts.  The method has progress steadily over the last 15 years with improvements to the equipment, data acquisition and analysis of the data. Current analysis of TIP data incorporates temperature vs depth and temperature vs. time. The current acceptance criteria for TIP includes using reductions in effective shaft radius and concrete cover (Piscsalko, et al. 2016).   However, these criteria are heavily based on knowledge of concrete volume and can be significantly affected by the lack of good concrete volume data.  An additional criterion using temperature is proposed for potential use in the industry, which can supplement the existing effective radius/cover criteria and will be less dependent on volume knowledge. However, the relationship between temperature reductions and defect size and position are not well known for various reasons.  The major reasons for this include; not a lot of studies/data available, variations in mix designs, variations in shaft sizes, and variation in defect types. Research was recently performed by the Authors on three drilled shafts with manufactured defects under grants from DFI and ADSC.  The study included running theoretical simulations to predict the sensitivity of temperature reductions to the defect size and location. Data was collected and the temperature with depth was compiled for various defects. The results show a promising relationship between temperature reduction and defect cross sectional area.  When considering local temperatures and average temperature changes, the criteria can consider location and size.   When including data from other recent research studies for similar size shafts and defects, we found the relationship to be consistent with our data.  The findings of this research provided a better understanding of the relationship between temperature reductions and defect size and location and provide the basis of the proposed temperature criteria.  

Oct 7, 2024