Search Documents

By John Wilson

"The Rietveld numerical method was used to calculate the relative abundances of phases in both synthetic binary mixtures and synthetic and natural ores, using X-ray diffraction data. The results were compared with those of image analysis and a chemical method. The ranges of the relative errors were estimated. The Rietveld method is found to be acceptable for determining the abundances of major and minor phases and the amorphous component of partially crystalline samples. In complex mixtures, where there are several trace phases (~<2 wt%) present, the technique becomes less accurate. It is most useful as an alternative technique to image analysis when sample preparation is problematic or sample particle sizes are sub-micron. It is a manual method which requires user input during the fitting process, but is both simpler and faster than image analysis due to the reduced set up time and sample preparation required. It is now implemented at CANMET as a technique for quantitative analysis.INTRODUCTIONUntil recently, the Applied Mineralogy group at CANMET used only image analysis and chemical techniques to determine phase quantities. An effort to develop quantitative X-ray diffraction (XRD) has been on-going for several years. Initially, the reference intensity ratio (RIR) method with external standards was tried with some success (Szymanski and Petruk, 1989). The main difficulty with this technique was finding adequate standard material for each phase present in the sample. This shortcoming made the method ultimately impractical, given the wide variety of materials which come to the laboratory for analysis.The Rietveld refinement method of quantitative XRD (Hill et al 1993, Mumme et al 1996), in contrast, requires no standards and requires minimal sample preparation and therefore a more rapid turnaround compared to image analysis. The Rietveld method also has advantages over image analysis in that it can identify and quantify polymorphs, ultra fine materials and many types of hydroxide products. As well, it is useful for analyzing materials such as bauxite or talc, which do not polish well enough for making mounts of the quality required for image analysis. To quantify amorphous material and phases which are present in amounts below the detection limit of XRD, the addition of a standard material is still required. However, in such cases only one standard is needed, which is alumina."

Jan 1, 2003

By V. F. Hollister

Although it is apparent that porphyry copper deposits may have formed in the Andean orogen from Permian time onward, commercial deposits thus far developed appear to have Cenozoic ages only. Following Chilean usage, the porphyry deposits are divided into either (1) a stockwork or (2) a tourmaline breccia model. As indicated by evidence cited in the paper, stockwork-type deposits tend to be related to major strike-slip structures which may be either transcurrent or transverse faults related to plate movements, while the tourmaline breccia type may more frequently form independently of regional faults. Stockwork types may be conjugate fractures that intersect and ramify as a network of veins and veinlets, cutting altered rock, and genetically related to a major regional fault, or in other cases they may reflect the intersection of two large fault structures. Circular fracture patterns may more rarely occur in stockwork deposits in response to a specific intrusion. Tourmaline breccia types are characterized by circular and radial fractures genetically connected in some way with touramline breccia pipe development or an intrusive piercement that preceded it. Each structural model contains mineralized intrusions which have a close time-space relationship to ore, and in each model mineral paragenesis is similar, regardless of age or location in the plate. Also, each model contains the same type of alteration halos (phyllic, argillic, propylitic) as are developed in intrusive centers in porphyry copper deposits found in North America. The potassic zone is exposed best in the older deposits. Examples of each type of deposit are illustrated, demonstrating the feature evolved.

Jan 1, 1975

By Norberto Dominguez

In the year 1820 a commission, assisted by Sr. C. Fernando de Ainada, was appointed by Sr. Jose Ramon Mila de la Roca to report on the condition of the mining region of Parral, in the State of Chihuahua, Mexico, where in recent years the mines of Batopilas have reached an important development under American management. The object of the inquiry was to provide Sr. De la Roca with facts to support a project for reopening mines that two centuries before had produced a large amount of silver. Although this plan failed, many facts of interest in the history of the mines were presented.. Much of the report dealt with questions that had only local application or were restricted to the conditions of labor and equipment in the opening of the nineteenth century. The historical part is presented in the following paragraphs: Abstract of the Report. Notwithstanding the difficulty of forming a just estimate of the system of mines in this mineral group in the valley of Senor Sail Jose del Parral without an examination of each of them, that which we shall say in a general way will suffice to convey an idea of their value and of the urgent necessity of reopening them. If this is undertaken, we believe the results will be of the highest consequence to the Republic, as well as to this immediate locality. The group of the Villa del Parral covers the mineral territory in which the village of that name was located. Its moantains contain large metallic veins, from which, as from the trunk of a tree, depend others much more slender, locally called ,fibras, crossing and interlacing each other in many directions. The first and oldest of these very rich deposits of gold

Jan 1, 1902

By Leonard Obert

Before 1957 a number of investigators reported stress determinations made on or near the surface of underground excavations. The usual procedure was to measure surface strains and to calculate the stresses using laboratory-determined values of the elastic constants of the rock. In some instances strain gages were stress-relieved so that the measured stress was absolute. Also, several investigators reported near-surface absolute stress determinations made by the flat-jack procedure. In 1958, Hast1 described a procedure for making absolute stress determinations within a body of rock. In this procedure a diametral deformation gage was placed in a borehole and then the borehole was overcored to produce stress relief. The secondary principal stresses in the plane normal to the axis of the borehole were calculated from measured deformations and the elastic constants of the rock. During the past nine years a number of investigations have been reported1-20 in which this technique, or modifications of it, have been reported. Both the stress distribution in the walls of underground openings and the stress field at points as great as 200 ft from these openings have been determined. Considered collectively, these reports shed some light on the nature of the stress distributions in the proximity of underground openings and on the stress field, that is, the state of stress outside of the zone of influence created by openings. To summarize these findings first consider the stress distribution in the wall and structural components of openings. Fig. 1 (a) shows a typical theoretical stress distribution curve in a linear-elastic, isotropic, homogeneous material. Fig. 1 (b) is an idealized measured stress distribution curve for the same opening in a relatively unfractured uniform, but brittle,

Jan 1, 1967

By Gerald A. Munson, Fremont F. Clarke

DURING recent years the use of lithium has expanded greatly in industrial, chemical, and metallurgical fields, while at the same time modernized methods of mining and refining lithium have increased production. Technical literature includes many papers describing the geology and mineralogy of lithium deposits. Mining and beneficiating problems, however, have not been thoroughly described. Published reports have failed to emphasize that one of the chief reasons lithium minerals were not extensively mined until recently is the difficulty of beneficiation. Four lithium minerals of pegmatites and the lithium-sodium-phosphate byproduct from the brines at Searles Lake, Calif., have been sources of lithium. Among the pegmatite minerals, only spodu-mene and petaline are known to occur in deposits large enough to support large tonnage operations. Spodumene, a lithium-aluminum-silicate, is the principal lithium mineral mined in the U. S. Lithium Corp. of America, during its rapid development and growth, has successfully employed three different methods of concentration: 1) hand sorting, 2) Heavy Media separation, and 3) froth flotation. Each method, though economic in its sphere, is becoming outdated as extractive techniques improve. The most recent development has taken place at Lithium Corp.&apos;s new operation in North Carolina, where the extractive process yields lithium compounds directly from mined rock without an intervening concentrating step. Until 1954 Lithium Corp. mined only in the southern part of the Black Hills of South Dakota, where the various types of lithium-bearing pegmatite could be used to develop untried processes of beneficiation. Concentrates from these operations are shipped to the corporation&apos;s chemical plant in St. Louis Park, Minn., where actual extraction of lithium and production of commercial compounds takes place. Nature of Deposits The geology of the southern Black Hills pegmatite deposits is admirably presented by a U. S. Geological Survey publication.&apos; Only the factors pertinent to exploitation need be mentioned here. Lithium Corp. has been interested primarily in three deposits, the Edison, the Mateen, and the Longview-Beecher No. 2. The history of these deposits dates back to the mining boom of 1880 to 1900 in the Black Hills, when most of the deposits were prospected for tin by the ill-fated Harney Peak Tin Mining Co. The three deposits described here, however, lay idle and unwanted until Lithium Corp. opened the Edison mine in 1943 and the Mateen and Longview-Beecher No. 2 in 1951. Edison Deposit: The Edison deposit is about a mile southeast of Keystone, S. D., on the northeastern flank of the Harney Peak uplift. The deposit consists of no less than four and probably at least six separate pegmatites that coalesce in a central mass from which the individual pegmatites finger outward and downward in complexly folded schist and gneiss beds of the country rock.

Jan 1, 1956

By Williams D. J

The boundary element method is one of a number of tools that have found wide application in geomechanics for mine design and stress analysis. Two examples are presented in this paper, illustrating the use of the boundary element method to find potential problem regions in large-scale excavations. These examples are from a Papua New Guinea open cut mine and an Australian sub-level caving operation. Because of the scale of the mines and the complexity of the excavations, the boundary element method is the only practical numerical modelling technique to account for the major influences. Although the boundary element method uses only linear elastic models of the rock mass, the paper illustrates techniques for dealing with non-homogenous and anisotropic rock masses, as well as clasto-plastic effects associated with an excavation.

Jan 1, 1995

This report chronicles the historical development of longwall mining in the United States and speculates on future developments to the turn of the century. Five eras of technological development during the modern period are described and analyzed. These eras discuss the development of (1) mechanized extraction, (2) self advancing roof supports, (3) high capacity roof supports, (4) shield supports, and (5) system automation. Current trends are analyzed in terms of: longwall utilization, production capability, support capacity, face widths, and new technological developments. From these analyses, the future of longwall mining to the year 2000 is speculated. It is concluded that longwall mining will continue to grow in importance during the next decade and that the next major technological milestone will be the realization of a fully automated longwall mining system.

Jan 1, 1992

By J. C. Motz

Introduction The variations in crushing plant design seen during the past 30 years provide a valuable source of information and experience from which one can select the optimum arrangement for a specific requirement. The purpose of this paper is to examine some specific equipment configurations as they relate to operating efficiency, plant availability and final product size in the form of mill feed. Due to the varied ore properties, physical space limitations, size of ore body and financial resources, there is no single crushing or grinding flowsheet that is best. Since energy costs have risen dramatically during the recent past, it became obvious that significant savings are possible by selecting equipment and a circuit which offers low power requirements balanced with low wear metal and installed equipment costs. Relatively clear and measurable are the metal and maintenance costs and the ever increasing cost of energy. Metal costs in the form of crusher liners have not quite doubled in the last 20 years, while power costs have increased by a factor of four or five, depending on the region considered. Estimates made only a few years ago on the increased cost of energy are obsolete in view of the recent unstable conditions. Since power is therefore becoming the largest cost area, it behooves us to investigate potential cost saving methods in the form of lowering the KWH/Ton of crude. Crushing To reduce run-of-mine to mill feed requires reduction in a series of stages. The physical size and power requirements of a crusher capable of reducing hard rock vary depending on the application. Extended experience in most crushing plants show that a minus 19MM (3/4 in.) rod mill feed can be and is being produced in three stages of crushing. In the majority of cases, the last crushing stage is closed circuited using anywhere from 19MM (3/4 in.) to 14MM (9/16 in.) slotted openings on the sizing deck. In some copper concentrators, the mill feed is all passing 13MM (1/2 in.) using three stages of crushing and 14MM (9/16 in.) square openings on the closed circuit screens. It was felt by some that crushing to this fine size is only possible if the ore is friable and is relatively soft in comparison to the harder ores. Our results show that some of the copper ores are as hard as taconite and are crush-

Jan 1, 1982

By John Chipman

DESPITE the rapidity of chemical reactions at steelmaking temperatures, deoxidation reactions cannot be expected to reach equilibrium immediately after addition of a deoxidizing agent. A considerable period of time may be required merely to obtain complete mixing of the deoxidizing element throughout the volume of steel to which it is added. Evidence in the literature indicates that in some cases the time is long compared with that allowed for completion of the experiment or for teeming of the heat. The great turbulence observed during the filling of the ladle is no guarantee of complete dispersion on a fine scale throughout the heat. During the process there are initially certain volume elements which are high in deoxidizer and others which retain substantially their original oxygen content. Mixing consists of the subdivision and ultimate destruction of these liquid segregates through the process of shear and elimination of concentration gradients by diffusion. The shear process does not continue indefinitely and a quiescent state may be reached in the ladle before all volume elements of divergent deoxidizer and oxygen content are completely eliminated. In furnace deoxidation the time required for complete mixing may be very long unless continuous stirring is employed.&apos; In Fig. 1, let the circle represent one small volume element of aluminum-rich metal surrounded by oxygen-rich steel in which no stirring movement remains. Further mixing requires inward diffusion of oxygen and outward diffusion of aluminum, resulting in precipitation of A12O3 in the diffusion zone. It is important to note that such a precipitate may itself interfere with the diffusion process. Moreover, if the precipitate forms as a film with even minimal mechanical strength, it may interfere not only with diffusion but with shear as well, thus stabilizing compositional differences in volume elements of greater than microscopic size. A film surrounding such a volume element would have little or no ability to rise or to sink unless it enclosed a liquid whose density differed from that of the ambient. Consider now the effect on the overall composition of the melt. Fig. 2 represents the A1-O equilibrium at the temperature of the bath. High-aluminum elements of composition X may exist alongside high-oxygen elements of composition Y in such proportions that the average composition 2 has a much higher A1-O product than that corresponding to equilibrium. The A1-O product supposedly corresponding to equilibrium at 1600 °C was found by Wentrup and Hieber2 to be 10-10, by Hilty and crafts3 to be 2 X 10-9 and by Gokcen and chipman4 to be 2 x 10-14. Only the last named investigators approached equilibrium by means

Jan 1, 1962

By Yashar Pourrahimian, Magreth S. Dotto

Fragmentation by blasting is a critical process in hard rock mining. The blasting process and outcomes are highly influenced by rock mass properties and their response to higher stresses and loading rates. Each rock mass is unique, but some features affect the blast energy similarly, leading to similar outcomes. Having analyzed these features and their influence on blast results, they can be incorporated into the blast design to achieve better outcomes. This paper presents a numerical model validated by a case study from the actual mine blasts that studied the effect of rock mass properties on explosive energy production, attenuations, and overall blast outcomes. The results show that when the model parameters are calibrated based on real data, they can be used to simulate the fragmentation process and therefore be used to aid blast design.

Jun 25, 2023

By Randy Settgast, Daniel Moos, Hyunil Jo, Ghazal Izadi, Christine Baba

"Analyses of production logs of multiply fractured horizontal wells in unconventional plays show that only a small percent (~30%) of perforation clusters contribute to production. We present in this paper one possible approach to mitigating this problem, based on use of a fully 3-D numerical model of fracture propagation through a heterogeneous medium, by studying the influence both of spacing and of perforation friction on the initiation and propagation of simultaneous hydraulic fractures from a horizontal wellbore. The results indicate that while limited-entry perforating can help to equalize the lengths of fractures simultaneously growing from multiple clusters, it cannot equalize their widths. Both fracture width and fracture length can be equilibrated by combining non-even cluster spacing with limited-entry perforating. This has obvious benefits as it allows equalized placement of proppant across the entire series of perforation clusters, resulting in similar fracture widths and conductivities which enhances the likelihood that all clusters will contribute equally to production.INTRODUCTIONThere is substantial evidence from production logs and other information that during the hydraulic stimulation of horizontal wells, not all perforation clusters within a given stage will produce. One possible cause is the interaction between the hydraulic fractures emanating from each perforation cluster. Typically fractures created at the outer perforation clusters create “stress shadows”, i.e. increases in compressive stress in the minimum principal stress direction, which limit the growth of fractures growing from interior clusters; this is confirmed by modelling [1, 2, 3]. An example of this can be seen in Figure 1 which shows the final configuration of simultaneously propagating fractures from multiple, evenly spaced clusters when there is no perforation friction. The inner fractures are substantially shorter, reproducing the results by Bunger and Peirce [3]. The inner fractures also have substantially smaller widths.One approach to equalize the growth of simultaneously propagating fractures from a horizontal wellbore is by using limited-entry perforating as a method to equilibrate the flow rates into each of the different perforation clusters. Perforation friction is caused by the finite diameter of the entry points into the formation, and leads to a pressure drop across each perforation which is proportional to the flow rate squared. Fractures that take more fluid have a higher fluid velocity through the perforations than fractures receiving less fluid. This causes a larger pressure drop between the wellbore and more rapidly growing fractures, compared to the same pressure drop between the wellbore and the fractures that grow more slowly. Because pressure within the wellbore is approximately the same at each entry point, the larger pressure drop leads to less pressure being delivered to rapidly growing fractures, thereby decreasing their ability to propagate and reducing the amount of fluid they are able to receive. Because the mass rate of injection into the wellbore is constant, this forces more fluid into the fractures that were propagating more slowly, increasing their growth rate. It also increases the pressure required to drive fluid injection. The balance of these effects makes the system largely self-regulating and delivers more balanced fracture growth. While this effect is well known, it is often neglected in current numerical models."

Jan 1, 2015

Paper written on project work carried out in partial fulfilment of M.Sc. (Chemical Engineering)degree Identification of non-linear systems can be a daunting task and in the process industries the problem is complicated considerably by the presence of noise from various sources, non-stationarity of the data and intermittence, such as observed in particulate flows. Traditional methods, such as frequency analysis and linear model-ling do not handle these systems well. Similar problems arise with the application of non-linear theory developed over the last few decades, where much of the analysis depends on embedding of the data in a phase space or pseudophase space, since these methods were not originally designed to deal with noisy systems. In contrast, singular spectrum analysis is a method which can be used to identify structure and distinguish noise from important information in multivariate data, such as the trajectory matrices of time series measurements. It provides an orthogonal basis onto which the data can be transformed, so that components of the time series can be investigated individually. With Monte Carlo methods, the components can be compared with those from linear surrogate data in order to identify possibly non-linearities in the data. In this paper, this versatile technique is briefly explained and illustrated by means of case studies.

Jan 1, 2003

By A. Romero-Juarez

This paper is concerned with the effect of propping-agent concentration on flow capacity of a fracture in the case in which there is embedment of the propping agent. Previous published studies have shown definitely that there is a relationship between fracture flow capacity and prop ping-agent concentration, and it has been shown that the theoretical results are confirmed by laboratory experiments. The problem of directly finding sand concentration for maximum flow capacity of a sand-propped fracture is solved, and formulas and charts are given to obtain this concentration under various conditions of effective overburden pressure, medium sand-grain diameter and rock properties. It is shown that, for the same effective overburden pressure and the same rock characteristics, optimum sand concentration in pounds per gallon does not depend on medium sand diameter. For conditions met in bydraulic fracturing operations, it is found that sand concentration in grains per square inch for maximum flow capacity varies within a wide range of values; this indicates the convenience of using data of fracturing pressure and rock characteristics for calculating sand concentration in order to achieve the best results in fracture treatments. INTRODUCTION It has been pointed out in the published literature1 that one important factor controls the success of a hydraulic fracturing operation — the propping of the fracture. The main effect of the propping agent is to hold the fracture open by means of the reaction forces that oppose the pressure due to the overburden. It is assumed in this paper that the propping agent is sand, that the grains are spherical and uniform in size, and that this sand is distributed in a monolayer in the fracture. The existence of a sand concentration value for maximum fracture flow capacity has been recognized since the publication of one of the first studies on the subject.2 In the reference cited, flow capacity was assumed to be proportional to the cube of the fracture volume per square inch not filled by sand. The obtained experimental curves relating to flow capacity and sand concentration had the same appearance as the curves obtained with the afore-mentioned assumption. Recent work3 has shown that fracture permeability, in the case of a monolayer, can be calculated accurately by means of a modified Kozeny-Cacman equation; thus, it can be shown that fracture pqmeability is a function of free volume in the fracture and of the rock and sand wet surfaces. The flow capacity of a fracture is dependent on the permeability of the fracture and on the fracture width. If all excessive quantity of sand is present in the fracture, its width may be large but its permeability i:; low due to the greater flow resistance; too few grains of sand per square inch are present in the fracture, sand embedment in the rock is greater and the width becomes small enough to appreciably decrease the rate of flow. To determine optimum conditions of flow, therefore, it is necessary to know the dependence of fracture width on density or concentration of propping agent. This relation is given in a study4 in which the approach to embedment is similar to the one made in a penetration hardness test of metal. With the equacions presented by Darin and Huitt,3 the number of sand grains per square inch that results in maxirnum fracture capacity can be determined graphically by plotting fracture capacity vs sand concentration. Since the relationship between fracture capacity and sand concentration may be considered known, one is led to formulate the analytical problem of directly determining sand concentration for maximum fracture flow capacity, in order to study the effect of the various quantities that come into the process. The solution of this problem appears to be interesting both from the viewpoint of fluid mechanics and from the practical viewpoint of oil production in hydraulic fracturing treatments. EQUATION FOR FRACTURE FLOW CAPACITY It can be shown3 that the fracture flow capacity of a monolayer is given by the following expression,

By I Ametov, G Levay

It is now common practice to use substantial amounts of recycled water in mineral processing plants to minimise both environmental discharge and withdrawal of fresh water from often limited water resources. Recycled water additions to process water are frequently obtained from sources such as tailings dams, tailings thickeners and concentrate dewatering. It has been suggested for some time that addition of recycled water to process water will impact the quality of the process water and that changes in water quality may influence flotation performance. To date, investigations of process water quality changes as a result of water recycling have been limited and as a consequence there are very few data available to substantiate these ideas. Thus the impact of recycling on process water quality remains largely unquantified. Over recent years we have conducted water quality studies at a number of mineral flotation plants with varying degrees of water recycle. This paper describes the results of these investigations, including data which suggest that build up of salinity due to recycling while it occurs, is reduced by fresh water make-up. The fate of flotation reagents such as collectors, promoters, frothers and flocculants during process water recycling has also been investigated. Results show that process water concentrations of these reagents vary from plant to plant, but that, with the exception of frothers, most reagents are generally removed from the system through mineral adsorption. In general, the results of these investigations suggest that recycling process water will not result in continuous increase in solute concentrations as appears to be the commonly held view.The effects of changing water quality on flotation can vary. In many cases, flotation conditions can be optimised to suit the water quality, while in others, treatment of the water may be necessary to obtain acceptable plant performance.

Jan 1, 2009

By K. J. Reid

A historical background of the development of automated material balance packages is presented including a summary of currently available packages and a description of the present work at the Mineral Resources Research Center of the University of Minnesota. A brief mathematical statement of the problem is given and solution techniques discussed. The problems and difficulties normally associated with material balances, both hand calculated and computer calculated are described. Several aspects of the available material balance packages as related to the "user/computer" interface are evaluated in detail. Elements of the material balance packages that affect the solutions are examined and the relative performance of the main packages on specialized problems presented. Finally, areas associated with automated material balances that require further work before computer packages can be widely used in industry are outlined.

Jan 1, 1982

By F. W. Metzger

Coal quality control in mining and mine planning has always been important and has become even more essential in recent years due to environmental considerations. The primary consumers of the sub-bituminous coals found in the Powder River Basin of Wyoming are electric utilities that require low sulfur coals to meet government air quality regulations. Electric generating plants are designed to burn coal of a specific quality, and the supplier of that coal must be able to guarantee shipments within specified quality tolerances. Over the past several years, Exxon Coal USA and, more recently, The Carter Mining Company, a division of Exxon Coal USA have established an evaluation and development program to accurately define the geology and quality of their coal properties. This requires an adequate drill hole density so that detailed correlations of the coal seam and the lithologic sub-units, of the coal seam can be made. These units must be recognizable in the core and also on geophysical logs.

Jan 1, 1981

Mining is a high risk industry where miners seek to secure certainty in all of their dealings. The introduction of native title to the Australian legal system with the High CourtÆs 1992 Mabo decision and subsequent Native Title Act 1993 has added to the risks associated with implementation and the ongoing operation of exploration and mining projects. The High CourtÆs Ward case in August 2002 confirmed Crown ownership of minerals and petroleum. But the Court also found that a mining lease that allowed an exclusive possession for mining purposes did not extinguish all native title rights and interests. Although the Court was specifically considering WA mining tenements, the WA mining lease is very similar to the mining leases and licences that exist across Australia, meaning that these tenements are unlikely to fully extinguish native title. The Ward case means that native title remains squarely on the table now and into the future for those involved in developing exploration and mining projects. However, certainty and workability is capable of being secured and this paper discusses some means by which this may be achieved. The paper starts by considering two of the many 1998 amendments to the æfuture actsÆ regime under the Native Title Act, Indigenous Land Use Agreements (ILUAs) and the application of ægood faithÆ negotiation to all negotiating parties. It then looks at native title agreements, other issues affecting negotiations and tips for negotiation technique.

Jan 1, 2003

By D Kavanagh, C Michaud

"A continuous improvement initiative was identified at Kalgoorlie Consolidated Gold Mine’s (KCGM) Fimiston open pit with the goal of reducing bench turnover time and increasing shovel digability by improving fragmentation around previously mined-out stopes. In the past, a higher number of blasts than normal would be required to get through a single excavation area where stopes were present. This is due to the limited reach capability of the drilling fleet from safe ground into restricted areas requiring the drilling of the shot to be done in a staged manner. In addition, the holes that were able to be drilled in the area did not remain open long enough to be loaded with explosives as a result of the poor ground conditions surrounding the stopes.Over the last 18 months, KCGM has trialled drill additives to improve blasthole stability, as well as introducing a remote drill rig allowing holes to be drilled in areas previously inaccessible by manned drill rigs. This has resulted in improved penetration rates in bad ground conditions, improved drill hole stability, better shovel digability, and an overall reduction in bench turnover of at least ten days on the benchmarked 126 days average per bench. KCGM is now in the final stages of the improvement project with the installation of a drill monitoring system on the fleet to allow live data transfer back to the office for analysis, as well as providing improved accuracy on drill holes in restricted areas.Citation:Michaud, C and Kavanagh, D, 2016. Reducing Bench Turnover Time and Improving Shovel Digability, in Proceedings Ninth AusIMM Open Pit Operators' Conference 2016, pp 19–27 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 15, 2016

By John W. Bader

Probing a mineralized area with a core drill to find out what&apos;s there is fundamentally a simple task, but a costly one. Quite commonly it costs $10, and sometimes more, to extract and assay each foot of drill core obtained. Yet, it is not unusual today to drill hundreds of holes on one mineral property. The initial objective of such probing is almost always simply to determine the potential worth of the ore- body, if any exists, and the question naturally arises: How little sampling is enough for this determination? The mathematics of statistics infer accuracy of estimates largely from the sheer number of samples taken. Mineral exploration usually involves accumulation of large numbers of samples, and thus it is usually not difficult to place narrow confidence limits on either side of the estimated average grade of a sampled orebody. The determination may, or may not, be as accurate as the derivations imply. If it is not, the fault is probably one of misapplication and not with the statistical processes themselves. Un- fortunately, indications are strong that the ordinary statistics of sampling usually cannot be applied to orebody exploration samples with actual attainment of the accuracy of estimate that they express mathematically. For this reason, a more deductive, less mathematical analysis of the sampling may well be worthwhile.

Jan 1, 1970

By R. B. Moore

Page History................................ 708 What is Radioactivity?........................ 710 Disintegration Series.......................... 711 Radium Ore Deposits......................... 713 Metallurgical Treatment........................ 717 Methods of Ore Concentration..................... 722 Future Supply of Ore......................... 723 Uses of Radium............................ 723 Mesothorium as a Substitute for Radium................. 724 Discussion.............................. 725 Probably no other metal excites as much interest, among both scientific men and the general public, as radium. This is due partly to the high cost of radium salts and partly to the peculiar properties of the element. Since radium-bearing ores were discovered in the United States, the interest of American scientific men has been stimulated and, at the present time, more radium is extracted and refined in this country than in all the rest of the world together. HISTORY The property of radioactivity was discovered, partly by accident, by Henri Becquerel, the French physicist, in 1896. He was experimenting with certain fluorescent substances in order to find, if possible, a connection between fluorescence and the recently discovered X-rays. Among other chemicals which possess the property of fluorescence, he was using salts of uranium. His custom was to expose the fluorescent substance to the action of sunlight and then register the effect of possible penetrating radiation on a photographic plate protected from ordinary light. Bec-querel&apos;s experiments gave positive results at once, and he at first believed that he had discovered a relation between fluorescence and X-rays. Later he exposed a plate to a uranium salt which had not been previously exposed to sunlight. To his surprise, on developing this plate, he found that he had obtained the same effect as he had previously secured when

Jan 1, 1919