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By Gino Vogt

In mechanized tunnelling operations, performance, consumption and safety are main factors for jobsites. One of the most important components effecting these factors, especially in slurry TBM operations, are Slurry Treatment Plants (STPs). Inadequately dimensioned and designed STPs create bottlenecks for tunnelling operation and jeopardize time schedules and performance. Inefficiently planned STPs could drastically increase consumption figures such as electrical power, bentonite, water polymers, etc. Inaccurately selected and treated suspension properties can cause a high-risk potential for the whole project. This paper debates the relevant key parameters for STPs from start to finish of a project and its results in influencing factors from the manufacturer’s point of view.

Dec 1, 2022

By Ryan Marsters, Adam Pring, Robin Dornfest

Raw water supply in the central Rocky Mountains often relies on trans-basin conveyance. Many of these older diversions incorporate high-elevation, miles-long tunnels driven over a century ago in hard rock. Tunnels were excavated using conventional drill-and-blast mining and weak ground was supported by timber sets and other various means. Over time, timbers rot and fail, rock quality deteriorates, and the timbers are gradually replaced by more timber, steel patches and braces, formed concrete, rock bolts, split sets, shotcrete, and other means which are commonly applied over existing support, thereby reducing tunnel cross sections, obscuring previous support systems, and rarely addressing the failing rock itself, leading to further deterioration of both the rock and the existing support. Traditional investigation techniques to assess compromised areas are often unfeasible due to access, depth, rubble and voids behind weight-bearing existing supports, confined space, poor invert conditions, poor ventilation, and flowing water. This presentation will discuss design procedures for assessing obscured ground conditions, assigning support classes which accommodate for unknowns, and implementing contractual means to address inevitable surprises or quantity overruns. Case studies include raw water supply tunnels in the Rocky Mountain region constructed between early to mid-20th century.

Dec 1, 2022

By P. Malíková, I. Osičková, R. Sousedíková, P. Rys, J. Dvořáček, S. Heviánková

Each mining project goes through the same life-cycle, from prospecting and exploration to closure and post-closure periods. This prompts the question whether the closure of a mine constitutes the end of its life-cycle or whether the decommissioned mine can be employed for some other purpose. Best-practice references indicate that there are many viable options. In our opinion, the production of service water is one such option. Laboratory research was carried out on the water from a flooded underground coal mine in Ostrava- Karviná coal district, Czech Republic, concerning the production of service water from pumped minewater. The research proved the practical feasibility of service or process water production. Given the effect of global climate change with regard to water resources, good prospects for this additional resource can be assumed since the water has to be pumped in any case for safety reasons.

Oct 1, 2022

By B Yang, L Wang, C Y. Ng

Flotation process intensification is often achieved through changing chemical reagent scheme or flotation machine or both, which likely brings a hefty burden to the flotation plants in terms of capital or operating expenditure. A novel approach to flotation process intensification is the use of acoustic sound, which has been demonstrated to be effective in improving the flotation of various mineral systems with different type of flotation cells. This approach was based on the dynamic stabilisation effect of acoustic sound on the flotation froth. The present work aims to understand the influence of various experimental conditions on the effectiveness of the approach. First, the effects of sound frequency and amplitude were studied with column flotation of silica particles. Results showed that the flotation performance was improved only within a certain range of frequencies and above certain amplitude. The study was then extended to the mechanical flotation of quartz particles with various size ranges and at two solids concentrations. With sound, the recoveries of different size fractions within the range of 20–212 μm were all increased. In particular, the recovery of 150–212 µm particles was increased from 0 per cent to approximately 25 per cent, demonstrating the potential for extending the upper limit of particle size in flotation by using acoustic sound. Furthermore, mechanical flotation of chalcopyrite particles at various collector dosages (50–150 g/t) was carried out with and without sound. Results showed that the increment of the final flotation recovery was increased with sound at different collector dosages. Overall, acoustic sound has the potential to be used as an effective and versatile method for flotation process intensification.

Aug 24, 2022

By M Edgar, G Pattemore, M Auad, K Job, A Job, S Gale

In recent decades, significant advances have improved the modelling techniques for predicting slope failure. Predicting failures is vital in open pit mining due to the significant risk posed to personnel and equipment from unstable pit walls. Failures not only cause harm and damage to people and equipment but also cause delays to production and subsequently increase operational costs. Coupled with improvements in modelling techniques, utilisation of advanced scanning systems, such as high-definition imagery from UAVs has enabled faster and more precise mapping and modelling. However, one key element required for accurate slope stability modelling and monitoring is the ability for mine geotechnical engineers to have an accurate understanding of the mineralogy and moisture content of slopes, in real-time. To address this challenge, research has been undertaken to utilise hyperspectral imaging across a broad spectrum, combined with high-definition imagery, and LiDAR to scan slopes for minerals and moisture content. In addition to accurately mapping mineralogy and moisture, the data must be collected autonomously and remotely to ensure ongoing safety. The results show that there are many direct and indirect benefits from this new technology, including the ability to monitor slopes at a safe distance and in real-time, improved accuracy of modelling, detection of risks, and improving the automation workflow for geotechnical engineers. The paper presents recommendations for the implementation of the technology in open cut mining environments.

Jun 22, 2022

By Wieda Azani, Alexander Tarigan, Willem de Beer

In block caving, the rates and sequencing of undercut production blasting, drawbell blasting, and mucking are the key levers for attempting to manage cave performance. Cave performance encompasses a range of factors, which include growth, shape and the effect of the cave on the abutments, excavations, geological structures and lithology. We compare production data in several panels in the Grasberg DMLZ and GBC block caves with the seismic response in work areas, around geological structures, and in geotechnical domains. These comparisons enable evidence-based conceptualising of the effect of production rates and mining layouts. By also considering the correlation of seismic release rates in different parts of the rock mass, the wider influence of a cave can be gauged through considering possible stress and / or deformation transfer. This concept is not novel, but it is rarely implemented in a routine fashion, principally because production data rarely are easily available. Previously, it has also been used to retrospectively compare seismic hazard between different mines. This paper discusses practical, day-to-day tools to manage seismic response to mining. Therefore, the paper presents a methodology for presenting seismic release and production rates on integrated plots at any time to facilitate quick identification of correlated spatial regions. This methodology explores the production data collection and geolocation at Grasberg, which will be described in some detail.

Apr 26, 2022

By J. A. Batista-Rodríguez, F. J. López-Saucedo

A new methodology is proposed for the preliminary assessment of coal blend quality, which combines gamma-ray spectrometry and magnetic susceptibility measurements. This methodology does not replacethe conventional methods of assessing coal quality, but can help to control the quality of the coal blending process, as well as reduce the amount of proximate analysis required and the determinations of calorific value and total sulphur. The methodology includes five steps. First, both geophysical measurements aremade with handheld equipment. The samples with magnetic susceptibility ≤ 1 × 10-3 SI are then separated. From these samples, those with total gamma intensity ≤ 20 nGy/h are separated. These samples have a higher calorific value and lower ash and moisture content. To separate the samples of better quality and with lower total sulphur content, in step four the samples with total gamma intensity > 20 nGy/h are separated from those with magnetic susceptibility ≤ 1 × 10-3 SI. This last group includes samplesthat will cause less total sulphur-related environmental pollution. In the final step, the quality of both radioactive sample groups is corroborated from the calorific value measurement and ash, moisture, andtotal sulphur contents in at least 10% of all coal blend samples from both groups. In this study, more than1000 samples were analysed with this new methodology, and the results are remarkably similar to the ASTM classification of the Sabinas Basin coals.

Apr 2, 2022

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 N Anderson

With traditional grade control processes, geological models are created by geologists at the completion of the data collection stage and wireframe construction is closed off at a set date to allow for time to complete the estimation process. Any issues identified at earlier stages or the addition of new data requires the estimation process to be started again. Alternative interpretations are explored only if time allows and often in a limited fashion. An alternative workflow has been developed at the Waihi Underground Gold Mine utilising Leapfrog Edge and Seequent Central. Geological and grade control models are created, dynamically linked, and saved as separate branches. A project geologist is able to work on the grade control model and a mine geologist on the geological model simultaneously. This allows for a non-linear modelling workflow with continual review and feedback. The introduction of new data can occur right up to the model due date, with data collection, validation, alternate interpretation, and review happening incrementally. Models are categorised and stored in Seequent Central according to project status. An approved version of the geological model and grade control estimate are uploaded at the time of release and transparently capture all data used at a point in time, as well as the review process. Dynamically updating models for grade control has reduced turnaround time while increasing accuracy and quality. Estimates of individual domains are vastly improved from being able to rapidly evaluate the effects of model parameter changes in real time and 3D. Development and stope design directly benefit from these streamlined processes, with higher quality, timely production occurring as a result.

Mar 22, 2022

By L. Schernikau, W. H. Smith

Oil, coal, and gas account for approximately 80% of global primary energy, but only a portion of total airborne CO2 eq (approx. 35% at GWP20 to 65% at GWP100), even though they account for 95% of total measured CO2 emissions. The benefits of these energy sources, as well as their related costs, are not all incorporated in current energy policy discussions. Global greenhouse gas policies must include documented changes in measured airborne CO2 eq to avoid spending large amounts of public funds on ineffective or sub-optimal policies. The authors examined airborne CO2, which is less than half of emitted CO2, as well as reported CH4 emissions and the global warming potential of CH4 as published by the IPCC for coal and natural gas. The surprising conclusion is that surfaced-mined coal appears ‘better for the climate’ than the average natural gas, and all coal appears beneficial over LNG. Therefore, current CO2-only reduction policies and CO2 taxes are leading to unintended consequences and the switch from coal to natural gas, especially LNG, will not have the desired impact of reducing predicted future global warming; in fact, quite the contrary. A large portion of anthropogenic global warming is attributed by the IPCC and IEA to CH4, but it must be noted that CH4 emissions from natural sources and from agriculture account for approximately 40% and 25% of annual global CH4 emissions respectively. Energy accounts for about 20% of documented CH4 emissions. CO2 contributes only approximately 35% of annual airborne anthropogenic GHG emissions after accounting for CH4, over a 20-year horizon. At a 100-year horizon, the contribution of CO2 increases to approximately 60%. Energy policies that do not consider all GHG emissions along the entire value chain will lead to undesired economic and environmental distortions. All carbon taxation and CO2 pricing schemes are incorrect and need to be revised. At IPCC’s GWP20 an approximately 2%1 higher loss of CH4 across the value chain prior to combustion of natural gas versus coal will lead to ‘climate parity’ of coal with natural gas. According to public data, natural gas value chains have high CH4 and undocumented CO2 losses. On a global average, using only IEA-documented CH4 data, natural gas emits approximately 15% more CO2 eq than surface-mined coal, over a 20-year horizon. This difference will increase as the use of shale gas and LNG expands. Investors should support all energy systems in a manner that avoids an energy crisis, including intermittent renewable energy systems where they make sense. If CO2 emissions need to be reduced, one of the most effective ways would be to install ultra-supercritical power plants with CCUS technology. However, the undisputed benefits of increased CO2 concentrations in the atmosphere because of its promotion of photosynthesis and plant growth effects (fertilization) need to be considered in energy policy decisions as well. The authors suggest that future research and development should concentrate on reducing net emissions from fossil fuel power plants and providing cost-effective and reliable new conventional power generation capacity, utilizing clean coal and clean natural gas technology.

Mar 2, 2022

By Mehdi Noori, Atefeh Azizitorghabeh, Fereshteh Rashchi, Ataollah Babakhani, Sarah Mahmoudi

The focus of this research was to evaluate the synergistic effect of bis(2,4,4-trimethylpentyl) phosphinic acid (CYANEX 272) and di-(2-ethylhexyl) phosphoric acid (D2EHPA), diluted in kerosene, on the extraction and separation of Co(II) and Li(I) from synthetic sulfate solution. The results indicated that using a mixture of CYANEX 272 and D2EHPA was efficient in extracting and separating Co(II) from Li(I). The optimum ratio of CYANEX 272/D2EHPA was found to be 5:1, in which the highest separation factor was obtained (5973.23), and ΔpH0.5 was 4.10. Adding tributyl phosphate (TBP) as a modifier and increasing the temperature improved the metals’ separation rate and extraction efficiency. Thermodynamic studies were also carried out, and ΔH, ΔS, and ΔG values were computed, revealing the endothermic nature of Co(II) and Li(I) extraction by CYANEX 272/D2EHPA mixture. The conducted experiments for the McCabe–Thiele diagram showed the possibility of using two stages to extract over 99% of Co(II) and Li(I). Slope analysis and Fourier transform infrared spectroscopy (FT-IR) were employed to comprehend the Co(II) and Li(I) extraction mechanism using a mixture of CYANEX 272 and D2EHPA.

Jan 17, 2022

By Pratima Meshram Abhilash

In this review, availability of germanium in primary and secondary resources and its recovery from these resources are presented. With nearly 40% germanium consumed in fiber optics and scarcity of resources, the global consumption outplays the primary production. Germanium exists as a substituted element in zinc sulfide matrix of lead–zinc sulfides and lignites. Nearly 60% of the germanium supply is met by zinc refining residues, and about 20–30% of germanium is produced from coal and its by-products. Germanium recovery from various resources such as zinc plant residues, coal and coal plant waste, spent optical fibers, and copper flue dust has been examined. Bioleaching was exploited by few researchers to extract germanium from zinc sulfides, sulfide tailings, jarosite, coal fly ash, and flue dust. This review covers the various work carried out by different chemical separation processes, viz., chemical precipitation, solvent extraction (SX), ion exchange (IX), and membrane processes, as well as biological approaches.

Jan 16, 2022

By P. L. Ngwenyama, W. W. deGraaf

South Africa is one of the leading producers and exporters of coal globally. A significant amount of the country’s production is obtained from previously mined underground bord and pillar workings. This coal is in the form of pillars and remnants on the roof and floor of the old workings. The good quality coal pillars were left behind as primary support during underground bord and pillar mining operations. Due to the depletion of virgin coal reserves, the pillars and remnant coal are now removed using opencast mining rather than underground methods. However, the secondary extraction of pillars and remnant coal from the old workings using opencast methods entails some serious challenges that have a negative impact on the safety and productivity of the operations, affecting both personnel and machinery. If these risk factors and challenges are managed properly, then the opencast mining operations could remove the pillars safely at recoveries competitive with those of virgin coal operations. In this study we review the recurring challenges affecting opencast pillar mining by means of field investigations and consultations with experts at five opencast pillar mining operations, and evaluate the best practices used to combat these challenges. It was found that each mine has its own unique conditions and challenges.

Dec 1, 2021

By IPMI Educational and Scientific Foundation

It is with great pleasure that we announce the availability of this fourth issue of the IPMI Journal, a publication of the International Precious Metals Educational and Scientific Foundation. This digital peer reviewed publication has been created as a vehicle for the sharing of technical information related to the science and technology of precious metals. Since 1976, the International Precious Metals Institute has championed the exchange of information of critical importance to the precious metals scientific and commercial communities through its various communications vehicles. This has included instructional videos, annual conference symposia, special topic committee meetings, regional seminars, and professional and student achievement awards. Due to the breadth of important topics related to all aspects of precious metals, it has been the vision of the IPMI to provide a publication available to the general public that would become a key source of pertinent topics containing high quality publications by experts in their fields of study. Historically, the IPMI has attracted world renowned experts in many fields (including Nobel Laureates Henry Taube, Ei-ishi Negishi, Robert Grubs, Professor Ben Feringa, and David MacMillan) in the dissemination of discoveries, inventions, and industry proven practices. Such information has a total value greater than the sum of its parts as seemingly unrelated innovations from distinct focus areas can be adapted to solve problems. Because of this important characteristic of information exchange, we have decided to create a digital journal, available to the general public, that will not only communicate state of the art discoveries and sound practices, but will also review historical communications from the IPMI’s archives that have value and use even in today’s environment. On behalf of the members and leaders of the IPMI, we hope you will find value in this new publication.

Dec 1, 2021

By D Giles, A C. Bailey

In the first 20 years of the 21st century, just over 20 per cent of Australian mineral exploration expenditure was dedicated to iron ore, totalling >A$8 billion and >30 million metres of drilling (Australian Bureau of Statistics, 2021). Improvements in the cost, efficiency, safety, reliability and data quality of drilling have the potential to deliver significant productivity improvements, increasing the probability of discovery and reducing the time from discovery to mining. Currently in its third year of research, Mineral Exploration Cooperative Research Centre (MinEx CRC) is focused on a new set of exploration tools and new ways to deploy those tools which recognise the fundamental importance of collecting quantity and quality data from the subsurface, to enable exploration success for all minerals, including iron ore. MinEx CRC is focused on developing more productive, safer and environmentally friendly drilling methods to discover and drill-out deposits. This includes pioneering work on Coil Tube (CT) drilling technology and innovations in Diamond and Reverse Circulation (RC) drilling techniques aimed at improved drilling optimisation and automation. In parallel, MinEx is developing new technologies for collecting data whilst drilling. This is being undertaken in four separate industry-led projects utilising geophysical, seismic, downhole analytical and 3-dimensional (3D) modelling improvements. A National Drilling Initiative (NDI) is also underway, with two drilling programs completed in 2020. The NDI is a world-first collaboration of Geological Surveys, researchers and industry, which undertakes drilling in under-explored areas of potential mineral wealth in Australia and provides a test-bed for new mineral exploration technologies.

Nov 8, 2021

By Omid Asghari, Amin Mousavi, Arshad Ranjbar

Geometallurgical modeling of the production benches is an attempt to estimate the geometallurgical variables of the different ore domains, which leads to a better understanding of the ore and its properties. Having geometallurgical variables results in a more accurate prediction of ore characteristics, an improved drilling and blasting operation, and better efficiency of the processing plant. In this research, the geometallurgical variables required for the geometallurgical modeling of the extraction benches are discussed. Then, the relations between Bond work index (BWi), as one of the most important geometallurgical variables and the primary grindability index, and rock geomechanical properties are investigated based on the previously published studies. The BWi is the main parameter for measuring the resistance to the grinding of ore minerals. It represents the energy required for processing (e.g., crushing, grinding) ore rocks in the beneficiation plant. As a real case study, BWi of a production bench in Sungun Copper Mine, located in East Azarbaijan province, Iran, was estimated. The rock’s geomechanical properties were measured using laboratory tests, including uniaxial compressive strength, Brazilian tensile strength, point load strength, and hardness. Then, BWi was estimated using the proposed formulas in the literature and the results of the rock’s geomechanical properties. The selected bench consists of three ore zones and two dyke domains. The laboratory tests revealed that the first ore zone has a slightly higher compressive strength than the other two zones, while the compressive strength of the waste rocks is larger than the ore domains. Using the proposed equations in the literature, the predicted values of the BWi for the samples in ore zones are in the range of 6.36 – 14.44 (kWh/t), and therefore this wide range must be considered when the short-term production schedule is planned. In addition, variations are observed in the samples within a specific zone and between the ore zones, demonstrating heterogeneity in the selected bench. Finally, wide-open results obtained by different equations show a necessity to perform a geometallurgical program specifically for the Sungun mine.

Oct 28, 2021

By Yanxu Shen, Cheng Liu, Zhijie Chen, Hao Chen, Huimin Gao, Zijie Ren

Fluorite, a kind of critical non-metallic minerals, is the primary source of industrial fluorine. Sodium oleate (SO) is commonly used as the collector of fluorite ores. However, because of its some features (such as the low solubility, high solidifying point, and poor dispersion of SO) at low temperatures, it profoundly inhibits its collecting ability as well as the flotation performance. Herein, we have developed a low-temperature-resistant collector for the efficient flotation separation of fluorite from quartz. The advantages and disadvantages of the SO and sodium petroleum sulfonate (SPS) were analyzed by comparing the performance under different temperature conditions. The results of flotation tests suggest that SPS exhibited much better collecting performance than SO under low temperature. The flotation mechanism of the two collecting agents were further analyzed by contact angle measurements, zeta potential measurements, Fourier-transform infrared spectroscopy (FT-IR), and flotation kinetics. The results indicated that both collectors can selectively undergo electrostatic and chemical adsorption with fluorite, with no adsorption on quartz surface. The sulfonic acid group in SPS is a hydrophilic functional group, which has a relatively higher solubility in water. Therefore, the water solubility of SPS is better at low temperatures.

Sep 30, 2021

By M. Salimov, J. Sattarvand

The conventional visualisation method of remote equipment is through the installation of one or more cameras on the machine, and sending a live feed to the operator’s flat display. However, the performance of the teleoperation can be enhanced using better visualisation through virtual reality (VR). This paper presents the process of the design and manufacturing of a robotic platform that will be used in the next phase of the project for a VR-assisted teleoperated excavator. The robot consists of a loading boom and arm arrangement installed on the undercarriage of a CAT300-9D. All hydraulic cylinders are replaced with electric actuators, and crawling motors are substituted by electric motors. The pieces of the boom and the arm, as well as the bucket were designed in Autodesk Inventor, and manufactured from aluminium sheets using a desktop and CNC machine. Parts are joined by pins and welding as needed. An Arduino-based control system is developed for the robot, and motor controllers are used to convert the power commands from the microcontroller to the high-amperage actuators. The control system is capable of communicating with a wireless Play Station controller to operate remotely. The manufactured robotic excavator is planned to be utilised in multiple autonomy research projects.

Sep 1, 2021

By F. C. Harris, S. J. Gaab, J. Sattarvand, S. Duzgun

Underground mines are inherently dangerous due to potential hazards such as fires, explosions, and caving of rock. Although these events are rare, once they occur a speedy and safe egress of mineworkers is critical to survival. Static evacuation systems use exit signs or directional lines but can get obstructed or be hardly visible in smoky or dusty conditions. This paper presents the investigation of the effectiveness of a smart evacuation technology in underground mining, where a real-time guidance system leads individuals on an optimised path to the egress while avoiding danger zones, compared to conventional practices. Participants simulated an evacuation from a virtual reality mine, using the conventional system and the smart evacuation system with real-time guidance. The highest reduction in evacuation time using the smart method amounted to nearly 40% on average. Moreover, 83% of participants preferred the smart guidance system, and agreed that it could enhance safety.

Sep 1, 2021

By Stanisław Prusek, CHONG WEI, Huawei Xu, Jun Wang, Andrzej Walentek, Artur Dyczko, Derek B. Apel

The excavation-induced stresses transferred from the panels or pillars in upper coal seams play a key role in the occurrence of rockbursts in driving roadways during close-distance coal seam mining, which has become a common problem and threat to many underground mines. The authors established a 3D finite-difference numerical model via FLAC3D software using the closedistance coal seam mining conditions in the Zofiówka Mine as a case example to reveal the rockburst mechanism in such conditions. The excavation-induced vertical stresses are analyzed, which provides a basis to build a conceptual model to explain the possible source mechanism of the rockburst under such conditions. Nine typical rockburst indicators considering different contributing factors are then selected as the evaluation criteria to assess rockburst potential in the study site. The results suggest that the superposition of multiple excavation-induced stresses of the main drift and tailgate provides an environment for stress concentration and energy accumulation. The side abutment stress induced by mining in the upper coal seam has a “strengthening” effect to the rockburst occurrence. The great deviatoric stress induced by complex excavating situations is another important exterior cause. A strict calibration procedure should be implemented before using indicators to predict rockburst potential. A methodology was proposed to estimate the location and magnitude of rockbursts combined with numerical modeling, laboratory tests, and feedbacks from the field. The study could provide some references and guidelines for preventing and mitigating rockbursts in underground mines under similar engineering conditions.

Aug 26, 2021