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By R. H. Weiland

The dewatering of flocculated clay suspensions by compression in a centrifugal field has been investigated. The results are evaluated with regard to both direct applicability to centrifugal dewatering, in solid-bowl centrifuges for example, and indirect applications to gravity sedimentation systems. It is well known that sediment consolidation under gravity depends on structural characteristics such as permeability and on the "self-weight" of overlying sediment layers. An important objective of the study has been to evaluate the self-weight effect using centrifugal forces to simulate consolidation in deep sediments. In this way, small-scale laboratory tests can be used to predict the rates and limits of sediment compression in industrial systems such as thickeners and settling ponds. Experiments have been conducted in which the sediment mass and initial structure were maintained constant while the effective sediment weight was varied by centrifuging at different speeds. The effects of initial structure have also been studied using controlled variations in flocculation conditions.

Jan 1, 1993

By MATTHEW HART, THOMAS BAMFORD, Kamran Esmaeili, MICHAL KOWALCZYK, FILIP MEDINAC

Improved haul road conditions can positively impact mine operations resulting in increased safety, productivity gains, increased tire life, and lower maintenance costs. For these reasons, a monitoring program is required to ensure the operational efficiency of the haul roads. Currently, at Bald Mountain mine, monthly site severity studies, ad hoc inspections by frontline supervisors, or operator feedback reporting is used to assess road conditions. These methods are subjective and provide low temporal resolution data. This case study presents novel unmanned aerial vehicle (UAV) technologies, applied on a critical section of haul road at Bald Mountain, to showcase the potential for monitoring haul roads. The results show that orthophotos and digital elevation models can be used to assess the road smoothness condition and to check the road design compliance. Moreover, the aerial mapping allows detection of surface water, rock spillage, and potholes on the road that can be quickly repaired/removed by the dedicated road maintenance team.

Sep 15, 2020

By V. B. Achanti

This paper deals with the effect of various bit geometric parameters on failure characteristics of rock material. Improvement of rock cutting efficiency of continuous mining machines has been an interesting research topic for the last few decades. In the current study, an automated rotary rock cutting simulator, duplicating a continuous miner, was utilized to study these parameters in the laboratory. Improvement of bit performance in terms of its life, cutting efficiency, dust production and energy consumption has drawn wide spread attention over the years. Research shows that optimizing bit parameters can result in efficient fragmentation of rock. Indiana limestone rock material was utilized in this study while bit tip angle, bit tip size, bit spacing, depth of cut and cutting velocity of rotary drum were varied to investigate the failure characteristics. The cutting pressure, penetrating pressure and the depth of cut were monitored on the simulator during the cutting process. Air borne dust and settled dust were measured for each experiment. Then, the specific airborne dust and specific energy were determined for the each type of bit. Triaxial tests were carried out to correlate the failure angle of the rock in static case to dynamic cutting process failure. The physical and mechanical properties of the rock were also determined in order to assess their influence on the wear characteristics of each bit.

Jan 1, 1998

By J. Killian, S. Cox

Many questions exist within the geotechnical industry as to the applicability of Strength Reduction Factor (SRF) values to the design acceptance criteria (DAC) of mining operations. There are many factors that contribute to changes in the SRF estimate, some of which are numerical (e.g. dilation angle) and some of which are geometric (e.g. model grid size)[1]. Numerous studies have confirmed equivalent values of SRF and FOS are found for soil slopes of limited height as presented in, [2] and [3]. However, significant deviation of the SRF value was observed for highly cohesive materials (rock slopes) of heights typically encountered in mining, [4]. This paper builds on the work presented in [4], providing a more rigorous examination of the modeling parameters that control the SRF estimate. The failure mechanism assumed for this study was a simple circular shear surface in a uniform material. Both LEM and numerical methods are suited well for analysis of this failure mechanism. A parametric study was completed to evaluate and test the relationships of key numerical variables that affect the estimated value of the SRF using Itasca’s Fast Lagrangian Analysis of Continua (FLACTM) software. The effect of groundwater has been tested and may be significant but is not presented as part of this body of work for brevity and simplicity of presentation.

Mar 2, 2022

By R. Mattos, E. Calcina, G. Quispe, S. S. Kanchibotla

During blasting, rock breaks and moves but standard grade control practices do not adjust ore waste boundaries to cater for blast movement. Rock movement resulting from blasts can result in mischaracterization of grade boundaries resulting in ore loss and dilution. Ore loss takes place when ore is mischaracterized as waste and sent to waste dumps, and dilution occurs when waste is mischaracterized as ore and sent for processing. Las Bambas operations of MMG Peru, realized the economic impact of blast movement on ore loss and dilution and adjust ore boundaries using limited blast movement measurements. This is a step in the right direction but has limitations for everyday application. This paper discusses the advantages of disadvantages of current blast monitoring techniques and introduces an operational tool to estimate polygon movements for different blast designs and confinement conditions. Blast movement estimates from this new tool have been compared against the estimates from the current tools for several production blasts and the results were quite promising.

Mar 2, 2022

By Salvatore Fancello, Ferruccio Cribari, Amerigo Tanzi, Mauro D’Angelo, Massimo Lodico, Alessandro Bertero, Eliano Romani, Tommaso Gondolini, Fabio Giannelli

"The new metro line “C” entails the construction and rehabilitation of 24 stations and 21,5 km of metro line, 13 of which carried out underground; the new metro line will improve the transportation system of a congested city such as Rome.The new line “C” of San Giovanni metro station will be constructed adjacent to the existing line “A” of San Giovanni station; the new metro line “C” is deeper than line “A” and will underpass the existing station. The underpass project envisages an Artificial Ground Freezing in order to excavate two new tunnels, while keeping trains running in the safest possible condition.In order to allow trains to regularly run to and from the existing station’s line “A”, a temporary structure for rail support, during excavation of the under-crossing tunnels, was installed and a real-time monitoring system was devised in order to control both soil temperature during freezing activities and the existing station’s behavior. The monitoring system has been one of the key to the success of the project.The excavation of tunnels under the water table, with a hydraulic head of over 10 m in not homogeneous soils having different mechanical properties and permeability and below existing sensitive structures, involves special ground freezing sequences and methods, as well as peculiar drilling systems and operations, such as TDDT (Trevi Directional Drilling Technology).THE NEW “C” LINE OF ROME’S METROThe world’s most complex and extraordinary Metro System is currently being built in the heart of Rome. Its underground route stretches underneath the most important monuments, churches and historical buildings.Rome’s Metro Line C is the longest urban underground railway in Italy and it is the first line in Rome to extend further east to the Great Ring Road, thus bridging the gap between the farthest suburbs and the Historical Centre. It is an original project, carried out mostly underground at a depth of 25/30 metres below road level."

Jan 1, 2016

By Liam Findlay

Optimizing a production schedule with semi-mobile in-pit crushing & conveyance (IPCC) requires integrating extraction sequence, destination policy, crusher relocation, conveyor layout, and truck fleet investment decisions. An integrated stochastic optimization framework is proposed to produce long-term schedules for mining complexes using multiple semi-mobile IPCC systems. The optimizer selects the crusher locations and designs the conveyor routes from anywhere in the mines. The stochastic framework considers simulated multi-element orebody realizations and manages associated risk. A hybrid metaheuristic based on simulated annealing and evolutionary algorithm is implemented for the optimization. The method is demonstrated using an iron ore mining complex.

Jun 25, 2023

By Carrie Smith

Along Michigan’s Upper Peninsula lies the Marquette Iron Range, home to iron mines. Just southeast of the region is the small town of Iron River, where Mary Korpi spent most of her chidhood and early adulthood. Though living in the heart of mining country, the industry did not pique her interest while growing up. As the daughter of two educators, she envisioned a different future for herself. Now, decades after working for one of the largest gold companies, she is gearing up for her term as the Society for Mining, Metallurgy & Exploration’s 2026 President.

Mar 1, 2026

By Joseph R. Hatch

During the past ten years detailed elemental analyses of approximately 8,000 well-documented samples of coils in the United States (including Alaska) have been produced by the U.S. Geological Survey and the various State geological surveys. Examples of data listings include Swanson and others (1976) Gluskoter and others (1977) Hatch, Affolter, and Davis (1979), and Wedge and Hatch (1980). These analyses serve as a basis for evaluating elemental abundances in coals from the various coal province, regions, and fields. When combined with additional geological and geochemical data, some of these analyses give insight into when certain elements were introduced into coals, and which physical and geochemical parameters are most important in determining coal elemental composition.

Jan 1, 1982

By H. Sevim

Placement of coal combustion byproducts into abandoned sections of underground coal mines for the purpose of subsidence mitigation has been investigated in Illinois. Several handling and transportation systems have been examined. Prototype pneumatic and hydraulic placement systems have been developed and demonstrated. The demonstration site, Peabody No. 10 mine in Pawnee Illinois, is selected as a case study. It is found that, for a project of 5 years, transporting 150,000 tons of byproduct annually from a power plant located 32 km (20 miles) to the mine would cost $1.80 per ton and placement into underground would cost $3.07 per ton.

Jan 1, 1998

By S. A. Sass

The design and construction of Solvay Minerals (formerly Tenneco Minerals) Soda Ash Expansion Project, which is the world's most modern natural soda ash facility, is detailed. Along with a discussion of design considerations, the international joint venture ownership and teaming arrangement for design and construction companies is examined.

Jan 1, 1994

By W. M. Hart

The remote face loading and entry convergence monitoring systems, employed at some of the Cyprus Amax's underground coal mines, have been able to continuously record changes in face shield resistance across and entry convergence ahead of the longwall face at any moment during longwall mining. The instrumental data obtained from these systems plus in-situ observations during the mining operation can help us better understand the mechanism of overburden strata movement above a longwall face and verify the effectiveness of the current face and entry supports. This paper describes the functions of both the face and entry monitoring systems, and discusses our findings and the issues related to successful ground control for longwall mining.

Jan 1, 1996

By Klaus Rieker

"Since the mid-19th century the River Emscher in the German Ruhr District has been used for disposing of wastewater. In the early 1990s, it was decided to replace the existing open wastewater system with a sewer system and to restore the River Emscher to its natural state. The major Emscher conversion project is divided into a large number of individual schemes, with construction phase 30 being the largest. By applying the pipe jacking method, interlinking tunnels with section lengths in excess of 1,100 m are constructed. USAGE OF THE EMSCHER OVER TIME The 85-km long river Emscher flows right through the Ruhr District. It has its source to the east of Dortmund and flows into the river Rhine near Dinslaken (Figure 1).The Emscher has been used to dispose of wastewater since industrialization began about 200 years ago. Intensive coal mining over the years led to considerable subsidence causing stagnant sewer areas which in turn led to typhus and other deceases. Thus in 1899, the Emschergenossenschaft was founded to create an efficient interceptor system for a catchment area of 865 km² through lining, raising and Emschergenossenschaft decided to free the waterways of the Emscher system from sewage and to improve them in ecological terms by 2020. A budget of 4.5 billion euros was earmarked for this purpose.The construction of sewer conduits began in order to no longer transfer the wastewater into the Emscher. The currently ongoing construction of the “Emscher Interceptor” - the main sewer - represents the heart of the Emscher conversion project. The interceptor will run along the river over a length of 51 km. Three pumping stations are required to confine the sewer’s depth to elevations between 15 and a maximum of 40 m below the surface. Since early 2012, the Emscher has been free from wastewater east of the Dortmund-Deusen clarification plant. There are two further clarification plants situated along the Emscher, which treat the still contaminated river water down-stream. Once the Emscher Interceptor is in operation, they will receive wastewater solely from the tunnel system."

Jan 1, 2016

By J. Gathje

Normal process development for pressure preoxidation treatment of refractory gold ores starts with laboratory batch autoclave tests, followed by operation of a continuous autoclave pilot plant for confirmation of the various process options. This scheme will generally provide good information showing the effects of such variables as grind size, time, and temperature, and will indicate whether autoclave preoxidation will produce solids that are amenable to cyanidation for gold recovery. However, several recent test programs conducted over the last three to four years have shown that the cyanide leaching responses of treated solids from the batch tests can differ considerably from those achieved by the continuous pilot plant autoclave. Examples are provided to demonstrate these differences and to show the importance of extending the laboratory investigations to include the use of a semicontinuous autoclave test procedure. A test case is cited in which this procedure provided data that could not be obtained from batch tests.

Jan 1, 1995

By T. C. Eisele

The separating efficiency of a flotation column is largely limited by the degree of backmixing of tailings into the froth zone, and its recovery is limited by the degree of short-circuiting of feed to the tailings. Current columns are typically made very tall, on the order of 30-40 feet, in order to limit the effects of backmixing and short-circuiting. These effects can also be reduced in a much shorter column, provided that the flow in the column approaches plug-flow. In this work, horizontal baffles were shown to improve the performance of a 6-foot tall laboratory-scale flotation column treating a difficult-to-clean, heavily oxidized coal. Tests with variation in the position of the baffles showed that for the greatest benefit, baffles are needed both above and below the feed inlet. Tracer tests with a fluorescent dye water tracer showed that the addition of the baffles reduced the amount of feed water entrained into the froth at any given coal recovery.

Jan 1, 1994

By D. A. Norrgran

The recent development of rare earth permanent magnets has revolutionized the field of magnetic separation. The advent of rare earth permanent magnets in the 1980's provided a magnetic energy product an order of magnitude greater than that of conventional ferrite magnets. This has allowed the design of high-intensity magnetic circuits operating energy free and surpassing the strength and effectiveness of electromagnets. New applications and design concepts focused on the mineral and metal processing industries have evolved. This technology also led to the development of various magnetic separators specifically designed for mineral processing applications. Applications which were not previously considered are now being applied to primary mineral upgrading and recycling and secondary recovery.

Jan 1, 1993

By J. Bilant, J. Donnelly

"A spatially-discretized heap leach simulation model was developed within the GoldSimTM modeling framework for the Coeur Rochester Mine, Nevada. The model is being evaluated by Rochester as a means of improving forecasting of silver and gold production on an actively loaded valley fill heap leach facility. Optimization of future heap leach operations and crusher product size is also being evaluated with this software. Simulation modeling incorporates metallurgical data such as mine planning, particle size distribution of placed ore, stacking plans, pad geometry, and leaching dynamics. The heap leach model is represented as a discretized matrix with lifts providing vertical separation to form 19,840 spatially discrete cells. Each cell is quantified with regard to ore properties and metal content. The model tracks solution and cyanide-complexed silver and gold within each cell as a function of time based on pad operations, unsaturated flow properties, and kinetic rates. Practical heap leach management and daily operation will be discussed as it relates to the simulation and forecasting model. INTRODUCTION The Rochester mine, and associated valley fill heap leach facilities, is an open-pit silver and gold mine located in Pershing County, Nevada. In 2015 Rochester produced approximately 4.6M troy oz silver (Ag) and 52K troy oz gold (Au) through combined cyanide heap leaching of the Stage II, III and IV heap leach pads with recovery via a Merrill Crowe process plant. Rochester is actively stacking and leaching ore on the Stage III Heap Leach Pad. The Stage III pad contains approximately 70M tons of ore in a valley fill configuration and is forecasted to receive an additional 20M tons of ore by the life-of-pad in 2019. The ultimate height of the pad is permitted to be 400 ft above the liner and solution collection system. Approximately 80 percent of the ore loaded on the Stage III pad is produced from tertiary crushing split from two crushing circuits that produce a nominal 80 percent passing 3/8” product. The remaining material consists of run-of-mine (ROM) from off loads of re-mined waste rock stockpiles. Metallurgical testing of the ore indicates low variability in geologic properties and high variability of both Ag and Au extraction rates for the various particle size distributions. Historically the valley fill configuration provided metal forecasting challenges that could not be predicted as the leach pads grew. Forecasting metal production and leach optimization of the Stage III pad became challenging due to the extreme variation in heap leach pad depth, application of available barren leach solution and the variability of Ag and Au extraction rates for the various ore particle size distributions. To assist with understanding and optimizing metal production forecasting with these factors for the Stage III pad, Hatch developed a spatially-discretized heap leach simulation model using GoldsimTM dynamic simulation software. The model incorporates metallurgical data such as mine planning (tonnages and grade), particle size distribution, ore crushing, ore stacking plan, pad geometry, and both leaching dynamics and kinetics to forecast metal production from a consolidated mine plan."

Jan 1, 2017

By Paul Shimizu

BHP Robinson contracted Minnovex Technologies to implement a Comdale Expert System at their greenfields operation in Ely, Nevada. The expert system has resulted in a significant increase in tonnage. Other benefits have also been realised, including a reduction in operation upsets (having a positive effect on downstream processes, i.e. flotation) and reduced production variances between crews. The expert system is written in a unique manner using trend based logic with minimal hard limits. The result is a robust system that requires minimal operator supervision while producing very high results. The development, success and acceptance of the system can be attributed to the strong team that was assembled for this project. The team not only consisted of BHP Metallurgists and Minnovex but most importantly included operations.

Jan 1, 1998

By Y. Q. Lu

Efficient flotation of fine phosphate minerals from a deslimed waste phosphate stream (-74 microns) has been achieved by both bench-scale flotation and by flotation with a 2-inch air-sparged hydrocyclone (ASH) unit. A sample was collected from the waste phosphate slime stream at the SF Phosphate Limited Operations near Vernal, Utah, for flotation experiments at University of Utah laboratories. The collector used was a mixture of fatty acid, petroleum sulfonate and kerosene. Bench-scale flotation test results show that the minus 15-micron particles have a significant adverse effect on phosphate flotation. When the minus 15-micron material was removed by a classifying hydrocyclone, improved flotation recovery and concentrate grade were realized. A bench-scale flotation recovery of 86 % with a concentrate grade of 16% P2O5 was obtained from classified waste slime (74 x 15 microns) feed material containing 11.3% P2O5 In contrast, a 90% P2O5 recovery was achieved with a concentrate grade of 16-18% P2O5 by single-stage ASH flotation. With a second stage of ASH flotation, a concentrate containing 23% P2O5 was realized at an overall recovery of 75%. These results indicate that the industrial application of ASH flotation technology for phosphate recovery from waste slimes is promising.

Jan 1, 1995

By M. L. Smith

The U.S. Bureau of Mines Cost Estimating System (CES) has been used for prefeasibility analysis and mine cost engineering since 1978. In the past, prefeasibility analysis with CES has involved the solution of regression equations. The new generation of CES uses an object-oriented expert system in a Windows? environment. Knowledge bases are structured around generic mine models which access shared knowledge bases for system design.

Jan 1, 1994