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By K. Holmberg, D. Herriot

This paper by Mr Mclvor is yet another contribution to the eternal controversy surrounding the benefits, or otherwise, of high circulating loads in closed circuit grinding. Throughout the paper it is difficult to establish whether the author is referring to effects relating to the mill, classifier, or to the overall circuit. Table 1 is put forward as indicating the advantage of operating at high circulating loads. From the two (it would be interesting to see more) product sizing points provided in each case, the conclusions to be drawn are that cases one and two have very similar size analyses. The third case, however, indicates a much flatter curve, that is to say, higher fines production and a very wide spread of size ranges. If the objective of this circuit is to provide a closely sized product with minimum overground slimes to the downstream process, then it would appear to be the less "efficient" by far. No data is given for product pulp densities either. The term "efficiency" should never be used without a careful and clear definition. In this case, "efficiency" is used to express an apparent percentage reduction in operating work index (Bond) from the measured "standard" at 250% circulat¬ing load operation. The Bond calculation is itself based upon

Jan 1, 1989

By Gerald C. Dohm

INTRODUCTION After a mining company has discovered a mineral deposit, the problem is then how to mine and process that deposit the best way. The principal problem facing managers or engineers who must decide on mine plant size, equipment selection, and long-range scheduling is how one can optimize a property not only in terms of efficiency but also as to project duration. Mine opti¬mization is dependent upon the interaction of con¬tributing parameters which leads to maximizing the net present value (NPV) Realistic mine planning is the key, to the analysis. The process is to be used when evaluating undeveloped properties or when a complete revamping of existing facilities is scheduled The proc¬ess is not intended for detailed mine design but rather for property evaluation and feasibility studies. The derivation of the various input parameters will only be discussed to the point where a meaningful correlation can be made with the overall analysis. The interrelationship of the parameters will be the central point because most company guidelines and financial analysts have their own standards when deriving the various inputs. Assume that the data is totally acceptable and pro¬vides at least the following categories of information and guidelines- (1) mineral and waste inventory; (2) geologic, hydrologic, and geotechnical criteria; (3) topographic layout including property boundaries; (4) metallurgical flowsheet, recovery and design criteria; (5) access, water, power, and environmental base-line study; and (6) financial constraints (minimum rate of return, payback period, etc).

Jan 1, 1979

By D J. McDougall

Due to changes in the solid-state conditions of minerals in the rocks surrounding hydrothermal, contact meta-somatic or metamorphosed ore deposits, positive or negative thermoluminescent anomalies may be found in their vicinity. Several types of equipment which can be used for both quantitative and semi-quantitative measurements of the emission are discussed and compared. Methods of selecting, preparing and testing samples to ensure reproducible results are outlined, along with the kind of data which can be obtained from different types of equipment. The normal thermoluminescence of rock-forming min~ erals in the common rock types is noted, and variations in the solid-state conditions in the wall rocks which will cause marked increases or decreases of true thermoluminescence are outlined, as well as the thermolum-nescence-like emissions which are present in the vicinity of ore deposits. Introduction T HERMOLUMINESCENCE occurs when certain crystalline materials are heated to temperatures ranging between 180' and 400°C. The light emission can be ascribed to the release of electrons metastably trapped within the crystal lattice, with peak emissions taking place at temperatures which are more or less specific for a particular set of traps; the area under

Jan 1, 1965

By H Mali, B Kain-Bückner

Different types of lump iron ore-bearing particles were investigated in terms of their raw material properties depending on their behaviour during reduction. To predict the reduction behaviour different types of lump iron ore and pellet brands were characterised by their mineral abundance, texture and pore size. The image processing software VisuMet was developed to semi-automate the evaluation of photomicrographs from polished sections of lumpy iron particles. The results were compared to the standard reducibility test after ISO 4695. The evaluation of lump iron ores is based on the simulation of the transformation of the different iron minerals due to their sequence of reducibility. The progress of the reduction front is simulated and the result is a degradation curve. Pellets were also investigated due to their different pore size distribution. The results indicate that the pore size influences the reducibility in addition to mineral abundance. The evaluation with VisuMet of the lump iron ore and pellet samples correlates with the reducibility provided by the ISO 4695 test. The determination of the mineral abundance by VisuMet is comparable to common point counting with a correlation coefficient of 99.67 per cent.CITATION:Kain-Bückner, B and Mali, H, 2017. VisuMet – analyses of lumpy iron carriers with image processing, in Proceedings Iron Ore 2017, pp 557–560 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By G. E. MeGlelland

During the 1970?s, the Bureau of Mines investigated a particle agglomeration technique for improving the flow of leaching solution through heaps of clayey or crushed, low-grade gold-silver ores. This technology has been adopted on a broad scale by the precious-metal-processing industry. This report presents information on the application of agglomeration technology to finely ground precious-metal-bearing tailings. Two commercial operations that have benefited from agglomeration technology are discussed. The technology is cost effective because of decreased leach times and improved precious metal recoveries.

Jan 1, 1985

By K Nilsson, D Connelly

Troy Resources acquired the Karouni Gold Project in Guyana, South America in 2014 and immediately proceeded to a Pre-Feasibility Study and project implementation. The study considered two open pit mines feeding a conventional carbon in leach (CIL) gold plant with a capacity of 1Mtpa. The study assumed a total of 2.61 million tonnes of ore with an average grade of 3.84 g/t gold with a recovered gold production of 303,526 ounces over a three year mine life.The project development involved drilling metallurgical test holes, securing second-hand major pieces of equipment where suitable, and arranging shipping to Guyana. The remote location meant logistical considerations were paramount. The plant consists of conventional two-stage crushing with single stage ball milling and a gravity circuit. The tailings circuit includes DETOX.The extremely high rainfall presented challenges with water management and the necessity to dispose of clean water to the environment. The DETOX was also mandatory due to the highly sensitive environment and past history in the area. The criticality of this meant that in the design, any cyanide in the tailings would precipitate in a plant shutdown.Lessons were learned and the project has been both profitable and successful for Troy Resources in a new operating location. In addition, the project has created jobs, delivered royalties and brought new skills into an area where previously there was little current mining activity.CITATION:Nilsson, K and Connelly, D, 2015. Karouni Gold Project from drill core to commissioning, in Proceedings MetPlant 2015, pp 197–206 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By M J. Nugus, J G. McLellan, T G. Blenkinsop

High fluid pressures and deformation have been instrumental in the formation of high-grade gold lodes at the Archaean granite greenstone 12 Moz Sunrise Dam gold deposit in Western Australia. Historically, predicting the location of these lodes has been difficult due to the irregular nature and high-grade nugget characteristics of the deposit. Recent exploration successes and the discovery of the Vogue system have led to an improved knowledge of the deep extents of the mine. This new structural and gold distribution data has enabled a new 3D interpretation of the system and has provided a better insight into the links between deformation, fluid pressure evolution and gold deposition. Here we employ 3D geomechanical and coupled fluid flow modelling to better constrain areas of high strain partitioning, rheological failure and focused fluid flow, which provides a substantially increased predictive capacity for further within-mine exploration. The localisation of deformation in and around the main felsic porphyry and major shallow shear zones provides critical insights into fluid pathways that have contributed to the distribution of fracture networks and ultimately gold deposition during late stage deformation events. Understanding the relationship between deformation events, fluid pressure evolution and the partitioning of strain is paramount in understanding the distribution of gold and for focusing on future target areas.CITATION:McLellan, J G, Blenkinsop, T G and Nugus, M J, 2013. Fluid pressure, geomechanical evolution and predictive targeting of the Sunrise Dam gold deposit, Western Australia, in Proceedings World Gold 2013 , pp 419-426 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

By Chen Xizhe

The caisson is adapted to the foundation of concentrated heavy building. As there are the flowing sand, boulder or cobble and other serious obstruction, the open caisson can't sink, the caisson can solve these problems easily. Especially for the stability of the neighour building, the merit of the caisson is outstanding. Therefore, there are the pier, the foundation of heavy instrument and the large water pumping station etc. using the caisson in China. This paper introduce several caissons and successful experience by author's investigation. It contains the feature and application of the caisson : the examples of caissons such as a huge pier of a bridge acrossing a big river, a large instrument foundation and a large water pump station beside a river; the problem of the design of the caisson and notice items during the caisson construction etc.

Jan 1, 1991

By Claude Bazin

"The On-Stream Analyzer has proven and is still proving to be an extremely valuable tool for the control of flotation circuits. This paper examines the possibility of going further in the utilization of the provided assays using a real-time material balance program to calculate the distribution of solids within the streams of a circuit. Mass balance results can be used for process control, process analysis and detection of sensors malfunction. Examples from 3 Canadian and one American concentrators are presented to illustrate the potential of the method.IntroductionThe On-Stream Analyzer (OSA) has gained, over the last two decades, the status of key instrument for the control of flotation plants. The OSA is currently used in almost every sulphide flotation plant and its application in oxide mineral flotation plants is increasing. On-Stream Analyzers provide X-rays pulse counts that are converted into assays using multilinear regression programs. The estimated assays are passed to the flotation operators, via an operator console, or to control loops of various degrees of complexity (McKee, 1991) implemented in a Distributed Control System (DCS). Operators and/or controllers take control actions based on these assays to ensure an adequate operation of the plant. Although this application pays off very rapidly for the purchase of the OSA, one should ask: Could we get more from the OSA?Some plants reported the use of OSA measurements to process optimization (McKee, 1991). The optimization strategy is based upon economic indices calculated from metal recovery using the 2 product formulae (Wills, 1992, page 124). The 2 product formulae is however sensitive to measurement errors in the assays and can lead to considerable scatter in the calculated indices (Hodouin et al., 1993). Least squares algorithms provide an interesting alternative to filter out measurement errors (Spring, 1992). This paper presents a recursive least squares algorithm that estimates in a real time fashion the mass flow rates in a flotation plant using OSA and mass flow measurements. The algorithm is robust and its recursive structure is not demanding in terms of computation time and memory. The method was tested with data from four concentrators. Results of the material balance algorithm prove to be useful to detect sensors malfunction and may potentially be used for the control and optimization of flotation plants.The paper is divided into two sections. The first section gives a description of the proposed method. The mathematics of the method are kept to a minimum, since the detail is presented elsewhere (Bazin and Franklin, 1994). The second section shows the application of the method to different flotation plants."

Jan 1, 1995

By C. Lemire, A. Biscaro

Ferro-alloys are sold according to the size grading specifications of users. Fines are produced during crushing and the amount produced depends on the crushing process and the physical characteristics of the ferro-alloy. The market value of fines has declined. Market demand is very weak and in some extreme cases is nonexistent. An induction furnace melt process has been developed to solve this problem. The process feasibility has been demonstrated on a small scale with charges of approximately 2.5 kg. The piloting was carried out using a 100 kW furnace with a metal liquid capacity of 140 kg. The operating parameters were determined during the pilot process. The procedures were defined and the equipment required for melting fines produced at the client's site was sized. With the production of ingots, the client can now recover the full value of ferro-alloy fines.

Jan 1, 2004

By Steve Kral

In the United States, the U.S. Environmental Protection Agency (EPA) is set to implement its Tier 2 air quality standards governing high-horsepower, off-road diesel engines. The regulations take effect in January2006. In Europe, similar standards, called Stages, are due to take effect about the same time. And other markets, such as Japan and Australia, have their own standards on tap. Tier 2 standards will further reduce the amount of nitrogen oxide (NOX), sulfur dioxide (SO2), diesel particulate matter (DPM), carbon monoxide (CO) and hydrocarbons off-highway diesel engines are allowed to emit. And even more restrictive Tier 4 standards are due in 2011. The upshot is that operators of high-horsepower engines, particularly in mining, will begin using in their new off-road haul trucks, excavators, shovels and other mining machines diesel engines that are designed to meet these more stringent standards.

Jan 1, 2004

An investigation into the causes of variable sulphur content in blast furnace metal produced at No. 4 blast furnace at the Port Kembla works of Australian Iron and Steel Pty. Ltd. was carried out. Theprogramme included an extended and detailed experimental study of a great number of the operating variables of the furnace, on a cast-bycast or four-hourly basis, over fourteen days.Possible causes of the variation were found in irregular operation due to sinter variability, and it was also clearly shown that slag conditions were most important in controlling sulphur contents of pigiron. Some decrease in sulphur variability was achieved, arising partly from this investigation, and it is hoped to try magnesia additions to modify slag conditions for better desulphurizing.INTRODUCTIONSulphur in pig iron is a problem common to many blast furnace operators throughout the world, but the direct causes and means of overcoming them are functions of the available raw materials, and are hence more particular to each plant and its operating practice. Sulphur in hot metal influences the steel-making operations, the rolling operations and the quality of the finished steel. The main problem associated with high sulphur in steel is "hot shortness", which leads to cracking of ingots and billets in rolling, to poor surface finish and to poor welding properties in the finished steel. On the other hand, sulphur is sometimes a desired additive to steel in order to promote free machining properties.Normal means of controlling sulphur A small degree of control of sulphur in steel is available to open hearth operators by alteration of slag volumes and basicity, but any large degree' of sulphur elimination is...

Jan 1, 1961

By Joseph Githiria, Khadija Omar Said

Mineable material is defined using cut-off grade either as geological or economic cut-off grade. Both geological and economic cut-off grade affects the output generated in an open-pit mining operation. It distinguishes the amount of ore sent to the mill for processing and waste to the dump. This consequently affects the overall profits generated from the operation hence the need for cut-off grade optimization. There are several mining parameters that are considered in a typical cut-off grade model. They include economic, geological, and operational parameters. They have a significant effect to influence the cut-off grade selected in mining operations at any given period. Some of the parameters are stochastic in nature by having a random probability distribution that may not be predicted precisely. When selecting cut-off grades in a mine operation, the mining engineers must consider the dynamic nature of the operational parameters in order to maximize the net present value of the project. Modifying Lane’s cut-off grade model which was developed in 1964 to incorporate the stochastic parameters in the approach helps improve the net present value as shown in the paper. The modified Lane’s approach is developed into a stochastic computer-aided application code-named NPVMining. Using NPVMining, selected stochastic parameters are considered in this exercise to show the effect on the output (net present value). The selected parameters (price and grade-tonnage) are varied by ± 10%. NPVMining has a graphical user interface that makes it easy to use and displays results in a user-friendly way. It gives the user the choice to manipulate the data depending on the study being undertaken or any other factor affecting the specific mine. This paper analyses the effect of each of the selected mining parameters on cut-off grade using NPVMining to show the significance of monitoring their variance.

Jun 25, 2023

By T. F. Curry, L. B. Berger, H. A. Watson, S. J. Pearce

The conduct of work at elevated air pressures , such as in caissons and in tunnel - driving in subaqueous strata , poses safety problems not encountered in mining and tunneling operations at ordinary atmospheric pressure . This publication discusses some of the problems involved and presents information on the following subjects : ( 1 ) Physiological effects of gases at elevated pressure . ( 2 ) Use of respiratory protective equipment in rescue or recovery operations in event of fire or other emergency in pressurized tunnels . ( 3 ) Effect of elevated pressure on performance of some gasdetecting instruments ; interpretation of the results . Various types of respiratory protective devices are discussed in relation to their possible use at elevated pressures , especially the 2 - hour , selfcontained , recirculating - oxygen - breathing apparatus , which has had wide use in the United States during rescue and recovery work in the mining industry . A modified procedure that eliminates the hazard of oxygen poisoning enabling the safe use of this apparatus at elevated pressures , up to 45 pounds per square inch , gage , and tests to verify its practicability are described . procedure involves control of the partial pressure of oxygen in the breathing

Jan 1, 1964

By Ronald Molnar

"High demand for metals is driving the exploitation of lower grade and more complex orebodies. These projects are often the initiatives of junior mining companies with limited financial resources. In addition, existing operations seek to enhance revenue from their existing metal recovery operations, through the production of value-added by-product metals and chemicals. Typically, hydrometallurgical circuits, often with novel chemistry, are required to exploit these new ores, to produce the multiplicity of products that will make a marginal project economical, or to increase the product range of an existing operation. Often, the mineral processing engineer is given the task of coordinating the development of a back-end hydrometallurgical flowsheet for their mineral processing project. This paper discusses the objectives that companies have when they commission the operation of a hydrometallurgical pilot plant. The paper goes on to enumerate some of the principal differences between mineral processing and hydrometallurgical pilot plants and the effect these have on the design, operability and potential pilot plant outcomes. Important factors include working with chemically reactive solutions and pulps, elevated temperatures operation, changing rheological properties of slurries, the complexity of integrated circuit flowsheets with long hold-up times and multiple recycle streams, and the need in some cases for extreme attention to purity and cleanliness. Examples will be drawn from the extensive experience base of SGS Minerals Services at the Lakefield site, in piloting both mineral processing and hydrometallurgical process flowsheets.INTRODUCTIONWe are currently experiencing a period of strong growth in the demand for metals. This in turn is turning the spotlight on a great many smaller mining companies and mining promotion ventures trying to tap into the rising metal demand. Some of these companies want to develop their properties and recover metals while others want to develop to the point that a major company will take an interest, or in some cases buy them out completely.With the heightened interest in metals, many orebodies that have been known about for years are being reconsidered for exploitation. Often, the reason they have not been developed to date is because of difficult metallurgy and marginal grades leading to marginal economic viability. In both cases the key that unlocks the resources is often the application of a novel metallurgical flowsheet, often a hydrometallurgical flowsheet."

Jan 1, 2006

By Yuting Xue, Alper Kirmaci, Taghi Sherizadeh, Dogukan Guner, Khaled Mohamed

Rib brows present a significant safety hazard in underground coal mines in the United States. To address this issue, researchers at the National Institute for Occupational Safety and Health (NIOSH) and Missouri University of Science and Technology (MST) are developing a practical tool to assess both the potential of rib brow formation and the stability of any formed brows. As part of this effort, a monitoring study was conducted to assess the potential for rib brow formation in coal pillar ribs. This study was conducted in a room-and-pillar coal mine where coal pillar ribs are prone to developing rib brows. Although no rib brows formed in the instrumented pillar, data from monitoring and visual observations provided valuable insights into the loading mechanisms impacting the instrumented pillar. These findings helped identify factors that may reduce rib brow formation, including the cavability of the roof in mined areas, the applied rib support, the strength of rock partings, and the overall integrity of the coal seam. The scientific findings published in the case study aid in assessing the potential of brow formation, offering additional evidence for the need to improve rib control methods in underground coal mines.

Feb 1, 2025

By Frank P. Frandina, Michael J. Loehr, Paul E. Gabryszak

The Heartland Corridor Clearance Improvement Project is part of a regional Public-Private initiative to allow double stack container trains a direct route from the Port of Norfolk through Virginia, West Virginia, Eastern Kentucky and into Central Ohio. In the Preliminary Engineering stage, 30 existing tunnels were assessed and 28 were found to need clearance improvements to allow the use of double stack trains. Alternative tunnel enlargement methods were developed to achieve the desired clearance improvements, while maintaining structural integrity and minimizing disruption to train traffic. This paper summarizes the geometric and condition investigations of the existing tunnels, as well as describes the preferred methodologies to achieve the desired clearance. The clearance improvements will be implemented beginning in the summer of 2007.

Jan 1, 2007

By Virendra Singh

The load settlement behaviour of single pile or pile group may be obtained using computer based methods such as the finite or boundary element techniques. An alternative method of obtaining the vertical soil stresses adjacent to the Pile is presented Based on calculated stresses consolidation settlement for Piles foundation is obtained. This approach may be computationally more attractive than the more general finite or boundary element techniques.

Jan 1, 1996

By Dewey W. Geary, Rachael V. Bisnett, R. Michael Bivens, Thomas G. Andrews

"The powerhouse for the Red Rock Hydroelectric Project is being constructed at the toe of the existing U.S. Army Corps of Engineers’ Red Rock Dam immediately adjacent to the existing stilling basin retaining wall. The powerhouse excavation extends though overburden and 40 feet into rock. Prior to rock excavation, a grouting was performed around the excavation for the purpose of increasing the strength of zones of fractured rock. For the majority of the perimeter, the rock was fairly tight and grout takes were relatively low. However, for a 160 foot extent along the landside of the excavation, extensive grouting was required to treat a two to five foot thick zone characterized by artesian flows from grout holes on the order of 20 gallons per minute (gpm) or higher from a voided zone in rock that was partially filled with sand, clay, and rock fragments. This paper discusses the treatment measures used to fill and improve the strength of this zone, which ultimately entailed a combination of thick cement grout and polyurethane grout, holes spaced as close as 18 inches on-center, and two additional rows of grout holes.IntroductionThe Red Rock Hydroelectric Project (Project) is currently under construction at the existing U.S. Army Corps of Engineers’ (USACE) Red Rock Dam on the Des Moines River near Pella, Iowa. At peak generation, the Project will generate up to 55 MW with an average annual energy output of 178 gigawatt-hours.The powerhouse for the Project will be located at the toe of the existing dam immediately adjacent to the existing stilling basin retaining wall. The powerhouse excavation extends up to a depth of 40 feet into rock through the St. Louis Limestone and terminates in the Warsaw Limestone. Prior to rock excavation, grouting was performed around the excavation for the purpose of improving the strength of zones of fractured rock. An auxiliary benefit of the grouting was reducing seepage into the excavation. Grouting began on July 20, 2015 and ultimately concluded on September 26, 2015.Drilling and grouting occurred as planned on the riverside (southwest) of the excavation along the cellular cofferdam and stilling basin wall (grout holes P-1 through S-13) and on the upstream (northwest) side of the excavation along the secant pile excavation support wall (grout holes P-14 through S-19) (refer to Fig. 1). The rock in these areas was generally tight with relatively low grout takes. However, on the landside (northeast) of the excavation (grout holes P-20 through P-28), partially infilled voids and artesian flows were encountered during drilling generally between depths of about 28 to 40 feet."

Jan 1, 2016

By Hal T. Morris

The main Tintic mining district in central Utah has produced approximately 13,500,000 tons of ore, containing silver, lead, gold, copper, zinc, and other metals, valued at more than $315,000,000. More than 90 per cent of this ore has come from large, irregular ore bodies that have replaced folded and faulted limestone and dolomite strata. Of lesser importance are replacement veins that chiefly cut contact-pyrometasomatized carbonate rocks and fissure veins that cut altered intrμsive bodies and volcanic rocks. The district is in the west-central part of the East Tintic Mountains, a north-trending fault-block range near the eastern margin of the Great Basin. The consolidated sedimentary rocks exposed at the surface and in mine workings are miogeosynclinal deposits more than 10,000 feet thick that range in age from late Precambrian to Late Mississippian. They are folded and strongly faulted and are partly overlain by volcanic tuffs and agglomerates and by extensive flows of porphyritic and vitrophyric quartz latite, latite, and trachyandesite of Eocene age. All of these rocks are locally concealed beneath thick alluvial deposits of Pliocene and Quaternary age. The Eocene and older rocks are cut by dikes, sills, and small stocks of porphyritic quartz monzonite, monzonite, and latite, which are genetically related to the ore deposits. The district is inactive except for the production of halloysite clay and for minor leasing activity and exploration ventures. Several exploration targets remain untested.

Jan 1, 1968