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By Peter Swanson, Collin Stewart, Wendell Koontz

A seismic monitoring network has recently been installed in the North Fork Valley coal mining region of western Colorado as part of a NIOSH mine safety technology transfer project with two longwall coal mine operators. Data recorded with this network will be used to characterize mining related and natural seismic activity in the vicinity of the mines and examine potential hazards due to ground shaking near critical structures such as impoundment dams, reservoirs, and steep slopes. Ten triaxial strong-motion accelerometers have been installed on the surface to form the core of a network that covers approximately 250 square kilometers (100 sq. miles) of rugged canyon-mesa terrain. Spread-spectrum radio networks are used to telemeter continuous streams of seismic waveform data to a central location where they are converted to IP data streams and ported to the Internet for processing, archiving, and analysis.

By P. T. O'Kane

"INTRODUCTION Wright Engineers Limited is active and has extensive experience in the design of pressure oxidation plants for the treatment of refractory gold ore and concentrate. In addition to the Mercur oxidation facility, similar projects undertaken during the last few years include the 3000 ton per day acid oxidation plant for the Getchell Mine, Nevada, a concentrate treatment autoclave for Asamera in 1984 and a feasibility study of a 50-tons per day autoclave plant for Consolidated Professor's Duport property in Ontario. The Equity Silver antimony and arsenic precipitation autoclaves, and the low pressure autoclaves at Key Lake Uranium in Northern Saskatchewan were also engineered by Wright in recent years.In August 1986, Wright was retained by Barrick Resources (U.S.A.) Inc. to add a 750 tpd pressure oxidation circuit to the existing mill at their Mercur Gold Mine, Utah. This paper describes this facility and outlines the start up in the spring of 1988 and subsequent successful operation. MERCUR OPERATION The Barrick Mercur Gold Mine is located at the south end of the Oquirrh Mountains in Tooele County, Utah. The carbon-in-leach (CIL) process plant camnenced operation in 1983 with a design throughput of 3000 tpd and has since been expanded to handle rrore than 5000 tpd. 'IWo ore types are mined, an oxide ore and a refractory ore, which is by Barrick's definition ""an ore from which less than 60% gold extraction is achieved by a standard CIL amenability test."" Typical of many sulphidic/carbonaceous ores, the refractory gold does not respond well to the cyanidation process. As a result, refractory ore has been stockpiled since the start of mining. As of June 1987, Mercur had about 570,000 tons of refractory ore stockpiled and 5.7 million tons of proven and probable reserves, grading 0.06 oz/t including approximately 3.5 million tons of tailings from the previous operation grading 0.55 oz/t. In 1986, Barrick decided to build a 750 ton per day pressure oxidation plant to process these ores. The process, for which a patent was granted, comprises pressure oxidation of the sulphides in an alkaline environment. It was developed in 1981 but was set aside in preference of a CIL plant treating only oxide ores by the previous owner of the property, Getty Oil. This process is capable of increasing gold recovery from the refractory ore from as low as 35% by conventional CIL processing to more than 85%. In 1986 Wright Engineers was engaged to undertake a feasibility study based on batch testing. This lead to a decision by Barrick Mercur later that year to build the commercial pressure oxidation plant. Wright was awarded the contract for engineering, procurement, construction managernent and commissioning in March 1987. The plant was mechanically complete in January 28, 1988, and was in operation by February 1988."

Jan 1, 1989

By A. A. Bakewell

This information circular, which describes mining methods and practices at the Baguio Gold Mining Co., Philippine Islands, is one of a series being prepared by the Bureau of Mines on mining methods, practices, and costs. Since January 1952, Baguio Gold Mining Co. has operated its rehabilitated mine and mill in the Baguio district. Postwar labor and supply costs are three or four times prewar costs, whereas ore tenor and tonnage are about the same. Ore reserves remain approximately the same, but deeper and more spreadout operations add to increasing costs. Recently the company has acquired an adjoining property, which may lengthen its life substantially. Costs and general operations are more or less typical of the district, which includes three other active gold mines. Gold ore mined in the district totals approximately 4,300 tons per day.

Jan 1, 1959

By C. Larsen, D. Fragomeni, A. Vien, D. G. Fisher

"MOCCA is a Multivariable Optimal Constrained Control Algorithm developed specifically for non-square industrial control applications with practical difficulties such as interactions, time delays, constraints, modelling errors, etc. MOCCA consists of an off-line simulation/translation module, for tuning the control parameters, and an on-line module that implements the designed control law.This paper describes an evaluation of MOCCA on the Hemlo grinding circuit which comprises one open circuit ball mill and two closed circuit ball mills in series. In this case a 4x4 unconstrained control problem was considered. The manipulated variables included the fresh ore feed rate and three pump box water additions. The controlled variables were the grinding circuit product particle size and three pump box levels. In this application soft constraints were implemented through control action and control error weighting. The feedforward capability of MOCCA was used to compensate for a measured water flow disturbance to one of the pump boxes. MOCCA performed very well during plant evaluations when compared to the original classical multi-loop control strategy and proved to be quite robust. Perhaps most importantly, the process engineers and plant operators have a high level of comfort both in understanding MOCCA's general operating principles, and with its demonstrated performance."

Jan 1, 1991

By M. A. Bussell, G. S. Camm

The study included lode zones at Wheal Pendarves, South Crofty and Rosevale tin mines. Fluid inclusion-containing microfractures are a common feature of the granites and typically show a preferred orientation over quite a large area. The close proximity of a dominant vein or fault controls their density and orientation. They are important pathways for fluids and provide a marker for palaeo-fluid flow. Overprinting provides a reliable representation of the evolution of the hydrothermal fluids in a vein system from early magmatic fluids to late-stage meteoric and basinal brine input. Measurement of microfracture orientation allows estimation of the regional stress regime during a specific hydrothermal event. Since micro- and macro-structures can generally be reliably correlated, these studies assist in modelling the detailed development of complex vein systems. Microfracture density is a good measure of palaeo-permeability, with implications for control of wallrock alteration. The determination of the location and density of microfractures can assist the mine geologist in identifying the location of potentially economic vein structures where macroscopic markers are absent

Aug 1, 1996

By Michael Cruickshank

Bob Woolsey was born in 1936 in the state of Georgia and grew up to be a man of great integrity, vitality, wisdom and charm, totally neutral on matters of race, gender, and religion. A true Southern Gentleman in every sense of the word. His passing on July 9, 2008, the victim of an automobile collision, left an empty space in the hearts of his family, and his many friends and colleagues throughout the globe. The posthumous award of the Moore Medal of the International Marine Minerals Society, to Dr. J. Robert Woolsey for Excellence in the Development of Marine Minerals, is a well deserved tribute to this man who spent the last 30 years of his professional career heavily involved in research and development of marine minerals on an international basis. He first came to my attention in Burma in 1979 where, as a newly appointed technical advisor to the United Nations Development Program Offshore Exploration for Tin, I had to fill the shoes of an almost legendary figure "Dr. Bob", who accompanied by his wife Maxine had spent the previous two years initiating the program. Bob had planned to completion the construction in Singapore of a unique drilling vessel the RV Sea Drill, a spud anchored, twin-hulled barge, mounted with a Becker Drill, and designed for sampling alluvial tin deposits in the coastal waters of the Mergui Archipelago in the Andaman Sea, off Tenasserim. He had also designed and built, with the help of his side -kick Bruce Jernigan, a barge mounted dressing plant for reducing and concentrating the drill samples. The adventures of Dr. Bob in transporting the equipment to the drilling site in monsoon weather and the transfer of the drill barge from the Malaysian port of Ranong across the strait to Victoria Point in Burma with a mutinous crew will remain in the hearts and minds of his Burmese colleagues for many a long year. On his return to the States he joined, in 1980, the faculty of the University of Mississippi (UM) as assistant Professor of Geology and Geological Engineering. His prior experience in private industry and the United Nations had focused on marine mineral resources and related environmental engineering projects in Africa, South America, the Mediterranean, the South Pacific as well as south east Asia, working with dredges, mining for alluvial tin, gold, diamonds and industrial minerals. He continued to work in the area of marine minerals at UM, making a name for himself as Director of the Mississippi Mineral Resources Institute (MMRI).

Jan 1, 2008

By Michael R. King

The application and use of steel fibre reinforced concrete in precast tunnel lining design is a growing trend due to its advantages in performance over plain concrete, and ease of manufacture compared to traditionally reinforced concrete. However, the design process and performance characteristics of the material are poorly served by current codes and standards. This paper provides some basic design guidance for segmental linings, and compares the material properties for the different material options. A typical example is considered to compare the possible results of lining arrangement and thicknesses for a plain, reinforced, and fibre reinforced design solution.

Jan 1, 2005

By E. Contestabile, R. von Rosen, R. Guilbeault, R. Fouchard, P. Lightfoot

In August 1998, a truck loaded with 18 tons of blasting explosives, including over 13 tons of ANFO, left the road near Walden, Ontario. The crash caused a fire; approximately 30 minutes later a large detonation occurred, causing substantial damage to the roadway and local property. Although nobody was injured in the explosion, the consequences of a similar incident in a heavily populated area could have been catastrophic. Following the Walden incident, Transport Canada and Natural Resources Canada embarked on an extensive experimental program to determine the cause of the detonation. This paper describes part of that experimental program, designed to understand better the thermal decomposition of ANFO.

Jan 1, 2003

By Matt Slezak, Tristan Worsey, Nathan Rouse, Kyle Hall

As everyone knows, blasters are required to file blast reports of every blast for regulatory purposes. To this day, the authors see many handwritten blast reports. Handwritten blast reports are notorious for containing errors or omissions. This is not because the blaster intends to misreport information. It is because blasters have many tasks to complete in a day, are sometimes in a rush, and could accidentally miscalculate data, omit items, or record incorrect data. In most cases, blasters do not suffer consequences to these errors because blast reports are seldom reviewed in detail. In some cases, such as when a blasting operation undergoes some sort of litigation process, the reports are reviewed in detail and the blaster is ultimately held responsible. If the reports contain errors, the blaster can be fined, have his/her license revoked, or worse. Electronic blast reporting and centralized data management can help reduce or eliminate the potential for accidental blast reporting errors to occur. This paper presents many ways that electronic blast reporting can reduce or eliminate blast reporting errors, decrease time and extra costs spent reporting, and improve efficiencies in the field and the office.

Jan 1, 2018

Owing to improvements in computer capacity, it is now possible to undertake fully coupled or partially coupled, three-dimensional (3D) hydromechanical Finite Element (FE) simulation of mines, including explicit representations of large numbers of discontinuities. The analysis requires fewer assumptions than uncoupled analysis or two-dimensional (2D) analysis, but may require a change in how hydrological data is collected. The way hydrological data is incorporated in stability assessment and the approach to uncertainty in hydrological information also requires discussion. The current procedures for this type of analysis are discussed, along with some practical difficulties and teachings from early applications. A work flow for integration of 3D hydromechanical modelling with pit planning and some considerations for the management of uncertain data are also proposed.

May 1, 2010

A physical modelling study has been carried out to simulate the slag-metal dispersion induced by a high-strength bottom gas injection. Water and kerosene were utilized to simulate metal and slag respectively. A water model of CLU (Creusot-Loire Uddeholm) vessel was used with three different nozzle orientations, namely, off-centre, triangular off-centre and centre. The gas flow rates changed from 0.00599m3/sec to 0.01081m3/sec. Height of heavy and light phases was kept fixed at 0.23 m and 0.02 m respectively. The dispersed phase holdup was determined at various axial and radial distances, gas flow rates, and tuyere configurations. The observations revealed that at a fixed gas injection rate, as the vertical distance increased in the centerline, straight off-centre orientation resulted in greater dispersed phase hold up values than those of the centre configuration and the triangular off-centre orientation. The dispersed phase holdup was found to increase with gas injection rate and decreased with axial distance. The variation of the dispersed phase hold up with the dimensionless axial distance and the gas injection rate was correlated by using the Modified Froude Number. The experimental values of the dispersed phase holdup were found to be in good agreement with the correlated values obtained from the modelling equations. The findings of the present study may be utilized in the ferroalloy refining vessels in terms of designing tuyere locations for optimum processing conditions.

Jan 1, 2004

By Swapan Ghosh, Amitava Sengupta, Proloy Das

Ferro-alloys are very important ingredients used for making of quality steel with desired composition. In view of high demand in various types of ferro-alloys, it has become necessary to produce the same efficiently, safely and cost-effectively with consistent quality maintaining the anti-pollution norms. To achieve this goal, it is necessary to adopt latest process/equipment with the state-of-the-art instrumentation and automation system. A Programmable Logic Controller (PLC) based automation system with suitable Human Machine Interface(HMI) terminals along with intelligent field mounted sensing/control devices allows to monitor and control the complete plant effectively with optimum deployment of man-power. In association with this, use of process optimization controllers enables to achieve specialised functionalities of the submerged arc furnaces like material management, lining management, electrode management, power management, overall production management etc.

Jan 1, 2007

This paper pays tribute to the pioneers in geomechanics, and addresses some of the most pressing issues of our time related to deep mining, and how to mitigate these issues. Solutions developed by our predecessors seem to have reached their limits as mines continue to go deeper. The International Society for Rock Mechanics (ISRM) guidelines for rock mass characterization for excavation design also require re-thinking to reflect current knowledge and experience. Thus, a whole new approach is urgently required to increase mine safety and productivity. The paper will draw on the challenges and experiences in medicine and science that have been overcome through genuine collaboration, advances in technology, and impressive funding, which can be adopted to provide solutions to contemporary geomechanics challenges for increased safety and productivity as mines continue to go deeper.

Jan 1, 2014

Experimental Study of Ore Characterisation Methods for AG/SAG Mills Mining companies have long recognised the importance of ore breakage characterisation in design and optimisation of their crushing and grinding circuits. In one of the industry standard methods relevant to AG/SAG milling, ore is characterised using mainly high energy single impact tests. However recent DEM studies have suggested that breakage in AG/SAG mills is mainly due to low energy repetitive (or multiple) collisions rather than single high energy impacts. Hence a study was initiated at the JKMRC to investigate the behaviour of ores under such conditions. Carefully designed experiments have been performed using two laboratory mill sizes (0.6 m and 1.1 m diameter) to mimic the reported low energy repetitive impact breakage under low load conditions. The breakage characterisation parameters derived from standard high energy single impact tests on the same ores was then used to predict the low energy repetitive impact breakage. Significant bias was found in the simulations which clearly warranted further investigation. The extensive experimental program which followed employed three separate methods: the JKRBT (JK Rotary Breakage Tester) for high energy single impact and low energy repetitive impacts, gravity drops for low energy repetitive impacts, and laboratory mills to provide an extended number of low energy repetitive impacts. The breakage energies associated with these experiments were accurately measured with a high speed video camera. Two breakage indices, the degree of breakage (t10) and the breakage probability (S) were used to describe the breakage test results. This paper summarises the major results from this experimental study, which has facilitated the development of a new breakage characterization method relevant to AG/SAG mill modelling.

Sep 13, 2010

By Derek Egan

"Abstract Construction clients want their foundation solutions to be right first time, every time; but it is often the geotechnical contractor who carries the most risk in achieving this. Robust validation to ensure that the installed geotechnical product is appropriate for the encountered ground conditions, will perform as required and be correctly measured for payment and record purposes is very important to minimise the contractor’s and the client’s risk. This paper outlines the development and operation of a robust real-time installation monitoring system which controls and validates the installation of driven cast in-situ (DCIS) piling. Using state of the art information technology the system allows the design engineer to interrogate the data acquired from the piling rig via his computer as the piles are completed. The use of the validation process, where data acquired during the driving of DCIS piles can be processed to estimate the finished pile performance, will be explained with reference to a new case study on large diameter DCIS piles. Examples of the routine use of the system will be presented to illustrate how automated monitoring of installation parameters can be used to raise the standard of reliability, efficiency and sustainability on piling projects. The conclusions to the paper will cover the key features and operational challenges characterising real-time monitoring of the execution of geotechnical works as developed from a number of years of experience of using a rig based data acquisition instrumentation system.INTRODUCTIONDriven Cast In-Situ (DCIS) piles have a long and successful history of use worldwide. The process, where a temporary steel drive tube, sealed at the bottom with a sacrificial base plate, is driven into the ground and filled with concrete before the tube is withdrawn, is well known (BS EN 12699, 2001 and Egan, 2013). Examples of large structures supported on DCIS piles installed by Keller UK include the Millennium Dome (now the O2 Arena) and the 2012 Olympic stadium in London.In recent times advances in piling rig instrumentation and telecommunications have enabled a new level of sophistication in the recording of installation parameters and the validation of pile performance. It is now possible to embed these features into the DCIS design and installation process which has improved the quality and efficiency of DCIS piling.This paper summarises the development and operation of a real time data acquisition and processing system for DCIS piling, but which is equally applicable to other forms of driven piling (for example concrete precast piling)."

Jan 1, 2014

"Drilling twinned holes is a traditional technique used for verification of intersections of high-grade mineralization, testing of historic data, or confirmation of drillhole data during geological due diligence studies. Twinned holes can also be used for special tasks such as correcting earlier data that are recognized to be biased. Successful implementation of the twinned-holes technique requires thorough planning. Experience suggests that good practice is to drill twinned holes no more than 5 m apart. Many unsuccessful twinned-holes programs could possibly have failed because the twinned holes have been drilled too far apart.Twinned holes are best compared by mineralization intersections and, if the data and geological characteristics of the deposit permit, by samples, equal-length composites, or geological units. Variables to be verified by twinned holes should include the thicknesses of the geological units of interest (e.g., mineralized thickness) as well as the presence of significant geological features (e.g., ore/mineralization contacts, alteration, etc.).A formal, rigorous analysis of twinned-hole data is essential. Repeatability of sampling, analytical results, and bias must be analyzed and statistically quantified. The number of twinned holes required for conclusive statistical and geostatistical analysis can be as high as 20-30, in particular where the studied variables are characterized by high short-range (local) variability.The efficiency of this approach is demonstrated by several examples of successfully applied twinned-hole projects, including applications to orogenic gold, mineral sands, bauxite, and iron ore deposits."

Jan 1, 2009

By A. K. Majumder

Particle motion in fluids is a subject of considerable practical importance to engineers working in fields such as hydraulics, river mechanics, chemical engineering and mineral processing. Many mathematical models have been proposed to predict the terminal settling velocities of particles in a fluid medium. The selection of an appropriate mathematical model has, therefore, become a challenging task for practicing engineers. This paper reports on an attempt to identify some of the useful models found in the literature for predicting particle-settling velocities in a fluid under free- and hindered-settling conditions. From this study, it was concluded that there is no well-accepted model validated by experimental data available for predicting particle hindered-settling velocities in a suspension of polydisperse and polydens particles. Collective efforts should, therefore, be made towards developing a hindered-settling model, as this is an absolute prerequisite for many model structures in mineral processing and other engineering disciplines.

Jan 1, 2007

By A. Krishnan

Keywords: Tantalum extraction, SOM Technology, inert anode, membrane stability The Solid Oxide Oxygen Ion conducting Membrane (SOM) technology offers great potential for environment friendly and energy efficient extraction of high-energy content metals. This work was performed to demonstrate the technical and commercial viability of the technology to produce tantalum metal directly from tantalum oxide and ore concentrates using a solid-oxide, oxygen-ion-conducting membrane (SOM). The process can be used to efficiently produce tantalum metal without expensive pre-processing of raw materials and without harmful by products. The work reported in this paper is: the proof that high purity tantalum metal can be produced, study of the electrochemical behavior of the cell and the method to increase membrane stability.

Jan 1, 2005

By E. Orowan

LONG before the role of dislocations in the plastic deformation of crystals was recognized, the stress-strain field around dislocations received considerable attention in the theory of elasticity. It seems that Weingarten1 was the first to consider dislocations as simple and typical sources of internal stress in elastic solids, and Volterra2 and Timpe3 investigated their elastic field. Fig 3-1 shows the two basic types of dislocations considered by Volterra. The first arises by making a straight-edged .plane cut in a solid, displacing the two surfaces of the cut in their own plane relatively to one another by a constant amount in a direction perpendicular to the edge, and welding them together; this is shown in Fig 3-la, where the outer cylindrical surface represents the boundary of the solid, and the thin spiral cylinder around the edge of the cut has been removed in order to avoid infinities of stress and strain. The second type of dislocation is shown in Fig 3-lb; here the surfaces of the cut have been displaced relatively to one another by a constant amount parallel to the edge, and then welded together. After J. M. Burgers,4 these two types are called edge and screw dislocations, respectively. They represent simple limiting cases; in the general case, the surfaces of the cut are displaced by a constant vector that lies in the plane of the surface but has components both parallel and perpendicular to the edge of the cut. This vector is the Burgers or slip vector. The name “dislocation” was given by A. E. H. Love;5 it was bor-

Jan 1, 1954

An Innovative Process for Comprehensive Utilisation of Clay-Vanadium Ores By adopting conventional processing technologies such as flotation, gravity concentration, and magnetic separation, it is difficult to enrich vanadium mineral effectively. At present, vanadium extraction process usually has not the mineral processing enrichment procedure, but rather uses direct hydrometallurgical process: roasting - leaching - precipitating vanadium for obtaining high quality V2O5 product. But it results in problems, for instance, high consume of auxiliary materials like acid and alkali, serious pollution and high cost of vanadium extraction. In the project study on the ore of a certain clay vanadium mineral, by adopting the test process: scrubbing raw ore with reagents added in - dispersing and segregating with reagents - grading enrichment, vanadium concentrate product with higher grade was made by virtue of reagent's selective inhibiting, and the purpose of upgrading the raw material used for vanadium extraction with hydrometallurgical process is achieved. The process technology obtained from project study features simple process structure, low equipment investment, low cost of mineral processing and pollution-free to environment. It provides high efficient and practical technology for the comprehensive utilisation of clay vanadium mineral, and has a prominent prospect for its popularisation and application.

Sep 13, 2010