Search Documents

By I Sherrell, R Jain, P Jansson

With the depleting iron reserves and difficult market conditions, precision in separation efficiency is of utmost importance. Classical local control options are predominant in the industry, but their inability to adjust to resolve application problems of interest has furthered the need of developing and implementing continuous control methodologies.This paper highlights the recent development in control of Outotec SLon® vertically pulsating high gradient magnetic separator (VPHGMS) including programmable logic controllers (PLC) coupled with distributed control system (DCS), on-site human–machine interface (HMI) control panel, advanced process control, continuous online sampling using Courier® 8 and additional modernisation packages including level control and cooling monitoring. These modern control options result in improved efficiencies, promote safer operation and at the same time reduce operational manpower needs.CITATION:Jain, R, Sherrell, I and Jansson, P, 2017. Automation for efficient separation with the Outotec SLon® vertically pulsating high gradient magnetic separator, in Proceedings Iron Ore 2017, pp 211–214 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By D. J. Gilbert

As a preventive action, the geotechnical department at the mine analyzed the original topography overlying a conveyor tunnel at the mine. Several dewatering drains were installed to intercept water collecting from an old lakebed. Subsequently, 20 steel arches were installed to provide additional support in an area of tunnel where original geological mapping indicated Type IV rock. This project was completed ontime with no loss to production. Construction schedules had to be developed to half hour precision, to accommodate the installation.

Jan 1, 2011

The extraction and processing of minerals from surface mines and quarries can produce significant fugitive emissions as a result of site activities such as blasting, unpaved road haulage, loading, primary crushing and stockpiling. Uncontrolled fugitive dust emissions can present serious environmental, health, safety and operational issues impacting both site personnel and the wider community. Simulation technology is finding increasing use for the purposes of advanced warning of potential problem emissions in addition to providing a basis for future planning applications where demonstrable compliance with regulatory requirements are necessary. The initial re-entrainment and subsequent dispersion of fugitive dust presents a process complicated by the combination of the in pit topography, the surrounding natural topography and the dynamic nature of emissions from these sites. These factors impact upon the accuracy and reliability of the conventional Gaussian plume based computational prediction methods employed for regulatory compliance and IPPC applications. This paper proposes that optimal modelling of open pit emissions may be more accurately achieved by the use of a multi-scale predictive modelling approach utilizing computational fluid dynamics (CFD) methods for high resolution near source dispersion and conventional Gaussian based methods for far field dispersion modeling. This paper presents a numerical based flow and dispersion analysis of a typical UK based open pit utilizing CFD in conjunction with a conventional Gaussian plume based methods. Typical operating emissions and meteorological conditions are obtained from long term data records collected at a large operating quarry extraction operation in the UK. Emissions are modelled using a Lagrangian framework within conventional atmospheric boundary layer (ABL) profiles expressed as functions of turbulence and velocity parameters under assumed neutral conditions. Results are presented in terms of the impact of site topography on in pit retention as compared to the Gaussian based method.

Jan 1, 2009

By Anthony D. Hammond

The use of geographic information systems (GIS) as a tool to analyze and display data is gathering momentum in the mining industry. Of particular interest is the capability of GIS to link spatial features and tabular data. The application of GIS in underground mining discussed here concentrates on four technical areas. They are land ownership and mineral claims, exploration management, production and mine safety.

Jan 1, 2002

By S. M. Jasinski

Peat is a natural organic material of botanical origin. Peatlands are situated predominately in shallow wetland areas of the Northern Hemisphere. Commercial deposits are formed from the gradual decomposition of plant matter under anaerobic conditions for about 5,000-years. In 2004, peat was harvested in 16 states. Florida, Michigan and Minnesota accounted for more than 80 percent of the U.S. production. Reed-sedge was the dominant variety of peat harvested in the United States, comprising almost 80 percent of the output. This was followed by humus, hypnum moss and sphagnum moss.

Jan 1, 2005

By B Mohanty, M P. Roy, P K. Singh

"The measured response of residential structures is a critical indicator of troublesomeor potentially damaging ground vibrations. A study was conducted to evaluate theresponse of structures situated in the periphery of four open-pit coal mines in India. Although, most of the structures were at far-off distances from the present blasting sites, an attempt was made to document the response of structures to blast vibration for future applications to optimize the blast designs for the safety of the structures. The study involved a total 215 blasts, employing one-, two- and three-hole calibration study, and production blasts. The bench height varied from 7.5 m to 42 m, and boreholes loaded with emulsion and slurry explosives were 250, 260, 270 and 310 mm in diameter. The explosive detonated in a blast were between 300-198400 kg whereas in a delay it was 33-24800 kg. Up to 12 tri-axial vibration sensors were located in overburden along a linear array from 25 m to 6.5 km distance from the blasts. Altogether, 1512 blast vibration signatures were recorded. Production and specially fi red single-charge blasts allowed the determination of natural ground frequency. The fundamental frequency of the structures ranged between 3.13 to 10.6 Hz, the same as those of the ground vibrations. The amplifi cation of vibration in the structures was in the range of 1.6 to 5.6. The study details the interaction between ground vibrations and selected structures, and the means to reduce amplifi cation of vibrations in the structures and persistence of vibrations through improved blast design."

Jan 1, 2008

By Albert Zima

ACCORDING to recently published statistics, it is predicted that as much oil must be produced during the next 16 years as has been produced during the past 75, in order to satisfy the high rate of consumption of petroleum products. During 1934, over 17,000 oil wells were completed in the United States, and it is expected that over 20,000 additional wells will be drilled during the current year. Were it not for the remarkable progress made during recent years in the improvement of drilling technique and in the development of equipment used in the production phase of the oil industry, it is doubtful whether sufficient oil could be produced to meet present requirements. A few years ago, wells seldom were deeper than 3500 to 4000 ft., owing to the limitations of the drilling methods and equipment employed. Today, however, through the application of scientific drilling methods and the adaptation of modern equipment and improved materials, many wells range from 6000 to 8000 ft. in depth, and a few recent completions exceed 10,000 feet.

Jan 1, 1935

By G. E. Agar, W. B. Kipkie, V. K. Drylie

"This paper describes mineral processing test work on drill core samples from an ilmenite deposit in Terrebonne County just north of Montreal.Mineralogical examination showed that the intimate associa¬tion between ilmenite and hematite precluded their separation. The maximum concentrate grade was therefore limited to 22.9% Ti. Liberation of gangue from the hemo-ilmenite grains occurred around 400 µm, a size which proved to be too coarse for recovery by flotation.Other physical separation techniques, such as elec¬trodynamic, magnetic and jigging, were tried in order to take advantage of the relatively coarse liberation size. An all-flotation procedure and a combination of jigging and flotation yielded similar separations.IntroductionInco Metals Company, through its subsidiary Canico, optioned an ilmenite deposit in Terrebonne County, just north of Montreal, and conducted a drilling campaign to confirm previous geological assessments of the deposit and to provide core samples for mineralogical study. Parts of these core samples were used for mineral processing studies, which will be described in this report. The objective was to identify suitable upgrading procedures, to determine the optimum combination of concentrate grade and recovery, and to provide suitable batches of concentrate for further treatment."

Jan 1, 1980

By V. F. Parry

Subbituminous coal or lignite when stored in random riles or in ordinary bins in which the temperature fluctuates and air circulates quickly undergoes objectionable physical and chemical changes, which decrease the utilization value of the fuel and increase its tendency to ignite spontaneously. Slacking takes place, and the heating value decreases. Those changes are accelerated by fluctuations of temperature and by circulation of air through the storage space. When such coals are exposed to the weather they lose moisture rapidly. If evaporation from the surface of a lump proceeds at a faster rate than that at which it is replaced by moisture from the interior, the rate of shrinkage at the surface is greater than that at the interior; consequently stresses are generated at the surface which cause the coal to disintegrate. Likewise, when moisture is absorbed by the air-dried surface the outside layers expand at a faster rate than the interior, which results in further break-down. As these cycles are repeated the lump may disintegrate completely. Therefore, successful storage of low-rank coals depends on control of the factors that influence change of moisture.

Jan 1, 1941

By Z. Saw, C. Poveda, N. L. Mai

Optimising the throughput of a mining network comprising all equipment from shovels to semi-autogenous grinding (SAG) mills is a complicated task, yet the potential benefits can be significant. Key modelling challenges stem from the sheer number of possible routes which material can travel, different equipment operating under different constraints, and the rate of SAG mills being calculated through a nonlinear function of the blended materials’ rock attributes. Nevertheless, this is an ideal onapplication area of mathematical programming, a branch of operations research. This paper describes an application of mixed integer linear programming (MILP) to optimise the mining equipment network of one of the world’s largest copper mines.The model takes as input a year-long monthly mine schedule of shovels in different pits, pushbacks, sequences and faces which produce material to be moved through a network of crushers, conveyors, silos, distributors, stockpiles and SAG mills, ultimately outputting a daily operational plan for all equipment that maximises the throughput of the network. All operational constraints and business rules are considered, including three quality attributes of copper ore. Comparing model results with actual data shows an improvement of 4.47% in network throughput tonnage. Additionally, although the model is solved using a free, open-source solver, optimal solutions are still achieved within a practical timeframe.

Sep 1, 2021

By G J. Lyman

In sampling a process stream, conventional sampling theory deals only with the variation of the analyte content and neglects the impact of the variation in the mass flow on the sampling variance, whether the sampling regime is time-based or mass-based. This is an obvious simplification of the real state of affairs and it is worthwhile to study this impact via simulation.With a facility to simulate large (long) random functions having some thousands of points in the function and the ability to impose covariance functions on the mass flow and analyte variations, such a study is possible. It is also possible to evaluate the impact of correlation between analyte content and mass flows.This paper describes a limited study of the variance increase due to mass flow fluctuations over the usual sampling variance due to analyte variation during the sampling period. The bias in the sampling result is determined for specific modes of correlation. Simulation methods are used as they are the only means by which a sampling result can be compared to the true assay for the lot; in the physical circumstances of mineral process analysis, it is never possible to determine the true process stream assay.CITATION:Lyman, G J, 2017. The impact of the weighting error, in Proceedings Eighth World Conference on Sampling and Blending , pp 311–318 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2017

By J. A. Organiscak

In the United States, respirable coal mine dust exposures are limited to a 2 mg/m3 time weighted average for a working shift. If the silica content of the sample exceeds 5 percent, the 2 mg/m3 standard is reduced according to 10- (% silica) to limit silica dust exposures to 100 µg/m3. Examinations of dust sampling data collected by the federal coal mine inspectorate showed that roof bolter occupations continue to be at risk for overexposure to respirable silica dust. Testing at the Pittsburgh Research Laboratory of the National Institute for Occupational Safety and Health assessed the effectiveness of a canopy air curtain for controlling occupational exposures to respirable silica and coal dusts. Initial testing found that zones of higher velocity airflow shrank as distance beneath the canopy increased. This suggested that protection from occupational dust exposures would likely decrease as distance beneath the canopy increased. Further testing revealed that coal dust reduction efficiencies were most affected by changes in interference air velocity and, to a lesser extent, changes in canopy air quantity. However, respirable silica dust percentages under the canopy were not affected by such changes and, in fact, were not significantly different from silica percentages measured outside the canopy. This implied that the air curtain was equally effective on both respirable coal and respirable silica dust particles.

By P. L. Duncanson, J. D. Toth

Since 1995, when "freeze lining" refractory systems were introduced to the ferroalloy industry, they have gained in popularity, due to the freeze lining?s reputation for reliability, safety, and the contribution it makes to profitability. As with many popular and effective technologies, however, the freeze lining has spawned low-cost pretenders that claim the "freeze lining" name. On the surface they appear to contain some of the components of the technology, such as thermally conductive materials, but they fail to incorporate all of the principles that define a true Freeze Lining. The term "freeze lining" refers to the refractory system?s ability to maintain a temperature profile that is low enough to freeze a layer of process material on its hot face, which insulates the refractory and prevents direct contact with molten metal and slag. In doing so, the common wear mechanisms found in the submerged arc furnace - chemical attack, erosion, and thermal stress - can be prevented. These wear mechanisms are all related to high temperature; thus, they are prevented by maintaining low temperatures. Certain refractory properties and design concepts are absolutely necessary for the lining system to function as a true Freeze Lining. The paper explains these requirements and why they are important - the Truth of freeze linings - and further explains why systems that ignore one or more of these requirements cannot claim to be freeze linings, thereby exposing the Myths.

Jan 1, 2004

By William Pitman

Ground instability and subsequent rock falls are a major concern in underground mines. As a result, several mining companies are conducting risk assessments of the ground support installed in their mines. Risk assessment is now commonly used to provide mine operators with a systematic process to assess the strategic risks that could lead to injury to personnel or loss of production, and evaluate possible risk control measures. Risk assessments can be carried out to identify major hazards, assess the likelihood of occurrence and consequences of each hazard and estimate the level of risk. This process allows assessment of possible remediation actions to minimize the risk and likelihood of occurrence or mitigation of the consequences to a level that is reasonable and practical. This paper presents two practical mine applications of qualitative risk assessment of ground support to highlight the benefits of this process. Yearly or bi-yearly risk assessment of mine excavations can assist mine operators in prioritizing resources and areas that require support remediation. In addition, it provides a mechanism for proactive response to reduce potential risks associated with personnel safety, equipment safety and environmental impact. It also provides a baseline against which changes in ground condition can be compared and quantified.

May 1, 2004

By T. Warren, R. Pender

"Significant strides have been made during the past decade to integrate the traditionally separate administrative functions of financial management, materials management and maintenance management.In 1983, Key Lake Mining Corporation (KLMC) brought on-stream one of the most technologically advanced mining operations in North America. There was a requirement to support this new facility with state-of-the-art management information systems.This paper will discuss the development and evolution of the corporation's computerized information systems with specific emphasis on the utilization of computer systems to assist maintenance personnel in performing their work activities:Note: In August of 1989, the administration and operation of the Key Lake Mine was assumed by CAMECO - A Canadian Mining and Energy Corporation.IntroductionThe Key Lake Mining Corporation was incorporated in 1979 and operates a $500 million uranium mining and milling complex located in northern Saskatchewan.The feasibility study and environmental impact statements for the Key Lake Mine were submitted in 1979and in August of 1981, following a public inquiry, approval to proceed with construction was granted. Ore processing commenced in October of 1983 and during 1984 a total of 10.4 million pounds of uranium oxide (U3O8) was produced. In 1987, an annual production of 13.5 million pounds was achieved clearly establishing Key Lake Mining Corporation as the world's leading producer of uranium oxide. Current ore resources are expected to extend production of the Key Lake facility into the year 2000."

Jan 1, 1990

By A. Adu-Acheampong

Stope instability at Ashanti Goldfields Company Ltd. (AGC) is a major concern. Using information from field mapping, major discontinuity sets were defined, Rock Quality Designation (RQD) was determined. The stability of wedges in the stope walls was assessed using the commercially available computer program UNWEDGE(Rock Science, 1992). Analytical results indicate that the presence of graphite infilling in joints contributes to instability, while steeply dipping joints control wedge slabbing and wedge toppling in the hanging wall. Stable stope widths and dimensions were determined to range from8.1 to 30 meters (m).

Jan 1, 2003

By S. Kevin McNeil, William Joa, Catherine Johnson, S. Omar Garcia

The geometry of an explosive is known to have a fundamental effect on the resulting shock wave propagation. Typically researchers use a spherical or hemispherical geometry in order to simplify the shock wave so that resultant overpressure and impulse are uniform in all directions. The goal of this research is to understand the overpressure characteristics from a sheet explosive, a geometry often utilized for breeching in the military. In training alone, soldiers can be exposed to several tests per day, which may be contributing to the prevalence of blast induced mild traumatic brain injuries. Using PCB pressure transducers and high speed video, it was found that as the angle departed from normal (perpendicular) to the face of the sheet explosive, the over pressure decreased significantly. When in line with the plane, a decrease of over pressure by as much as 20% was observed. Time of arrival was roughly 20% faster directly in front of the charge with a pressure amplification of 46% relative to a spherical baseline charge of the same mass. This testing may reveal a more complete relationship between the pressure and angle from the explosive that could have applications for military and law enforcement with respect to best practices on blaster location for reduced over pressure exposure.

Jan 1, 2019

By Israel Liebman

The Bureau of Mines conducted an investigation to determine those factors that are significant in affecting the velocity of flames propagating along the boundary separating gaseous fuel and air. In addition the aerodynamic motion of the gases in the vicinity of such interfacial flames was delineated. Parameters in the study included flammable zone thickness, flammable zone concentration of gradient, fuel type, and position of the flame relative to various environmental surfaces. Of all these factors, the flammable zone thickness and burning velocity of the stoichiometric mixture were found to have the most significant effect on the flame speed. Notion of the gases in the vicinity of the interfacial flames was examined by particle track and interferometric techniques. The relative velocity of the interfacial flame with respect to the unburned gas on the central streamline was found to equal the burning velocity of a stoichiometric homogeneous fuel-air mixture. In addition, it was observed that the composition of the lean fuel-air mixture at the boundary of the combustion zone appears to be less than that defined as the fuel's lower flammable limit.

Jan 1, 1968

The Bureau of Mines Minerals Information organization collects worldwide data on virtually every commercially important non fuel mineral commodity. These data form the base for tracking and assessing the health of the minerals sector of the U.S. economy. This data collection activity was instituted by the 47th Congress in an appropriations act of August 7, 1882 (22 Stat. 829), to place the collection of mineral statistics on an annual basis. The most recent authority for the Bureau of Mines Minerals Information activity is the National Materials and Minerals Policy, Research and Development Act of 1980 (Public Law 96-479, 96th Congress), which strengthens protection for proprietary data provided to the U.S. Department of the Interior by persons or firms engaged in any phase of mineral or mineral-material production or consumption.

Jan 1, 1984

By Steve Massman, Edward Wipf, Gary Beerkircher

"As mine size and tonnage continues to increase, material handling/processing equipment has also increased in size with 400 MT haul trucks, 2000 KW crushers, 12 M SAG/AG mills, 8.5 M ball mills, 3000 M3 flotation cells and 12.5 MW HPGR’s all with planned designs to increase in size further. Related equipment including vibrating screens have also increased in size with screens seeing feed rates of 3000 MTPH. Open circuit SAG Pre-Crush and closed circuit HPGR flowsheets are becoming more common with large screening requirements. Large multi-slope (banana) or horizontal screens are commonly used for these applications, however as the size of these screens has increased, the number and size of the brute force/overhead exciters has increased but with limitations. An example is a SAG discharge screen that will see surges of material from the SAG mill which overload the screen, reducing the screen stroke or throw causing a large reduction in screen efficiency with excessive fines & moisture in the screen oversize feed to the pebble crushing circuit. This paper will present some actual examples of the use of Two-Mass screens as a solution to these overloading problems and the advantages of Two-Mass screens in other high tonnage applications.Brute Force Drive Compared to Two Mass Drive Vibrating ScreensThe standard single mass screen as depicted by figure 1 is generally recognized in the mining industry. It is characterized by the screen body – labeled as the single mass (Mt) that is supported by isolation springs (Kiso). The stroke needed to process material is obtained by incorporating large eccentric wheels and/or drive boxes (Fb) directly mounted to the screen body via a drive tube."

Jan 1, 2017