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During 1997-2001, an EC funded project investigated the environmental consequences of the use of industrial waste and sewage sludge based artificial top soils (ATS) in rehabilitating large coalmine waste dumps in the Saar region of Germany. Both the laboratory leaching tests and field lysimeter data analysis carried out by the research partners have shown that the amount of dissolved heavy metals in the leachate was low, and generally below the regulatory limits. However, the dissolved amount of nutrients, especially mineral nitrogen, was found to be relatively high. The hydrological properties of waste rocks and ATS mixtures were established through history matching of the laboratory column tests and the field measurements. 1D column models and 3D field models were used to numerically simulate pollutant transport at the ATS rehabilitated waste dumps. This paper presents the findings of the numerical modelling research carried out for the characterisation of hydrological and pollutant transport properties of rehabilitated coalmine waste dumps in the Saar coalfield.

Jan 1, 2003

Profiled on these pages are the eight RMCMl 1998 Scholarship Award winners. Six of the eight winners were present as guests of the lnstitute at the June convention at Snowmass Village, Colorado. Each received recognition at the Institute Awards Luncheon Sunday. June 28. 1998. Each state vice president served as host for the collegiate winner and his firm provided travel and hotel expenses. In addition to receiving a plaque from the Scholarship Chairman, Jim Mattern, each winner receives $1.000 tuition credit for the coming academic year, as well as transportation, hotel lodging and meals at convention as guests of the Institute. Because this IS a continuing award, the winners from the previous year also receive a $1,000 tuition credit in their senior year if recommended by the dean of the college or university and if they remain full time students. A resident from each of the eight RMCMI member states is selected from among Board approved institutions. Criteria for these awards made annually is that the recipient (1) Is a full time sophomore student who will use the tuition credit during the junior year. (2) Be both a U.S. citizen and a resident of the member state. (3) Maintain good academic standing, be pursuing a degree in a mining related field and have an expressed interest in western coal as a possible career path. The scholarship program includes curricula other than in the mining departments, but in engineering disciplines, such as geology, mineral processing and metallurgy. Through annual donations of $100 or more. the Patrons of the Institute fund the scholarship program. A listing of current donors is found elsewhere in this book. Donations to this worthwhile program are payable to RMCMl Patrons and may be mailed to the RMCMl Office, 3000 Youngfield Street, Suite 324, Lakewood, Colorado 80215. Profiles of the 1998 Scholarship Winners follow. [ ] ARIZONA WINNER Christopher L. Delp University of Arizona Christopher is the son of Drusilla and John Delp of Tucson. He is pursuing a degree in Mining Engineering as a junior at the University of Arizona. He enjoys outdoor sports including skiing, mountain biking, golf, and hiking. He also enjoys reading, ghost town and old mine exploration, computer, Japanese conversation, and sketching cars and other forms of transportation. Chris hopes to attain a Masters Degree. [ ] COLORADO WINNER Matthew D. Lengerich Colorado School of Mines Matthew, the son of Judy Lengerich, Durango, Colorado and Ronald Lengerich of Redlands, California, is pursuing his degree in Mining Engineering with a 3.93 GPA. He is a member of the National Honor Society and the German National Honor Society. An avid outdoorsman, Matt also finds time to pursue music and theater. He was unable to attend convention this year as he was on a collegiate trip to South Africa. He is Co-President CSM Newman Group and Youth Leader at Christ on the Mountain Catholic Church.

Jan 1, 1998

By J. W. Stewart

The aim of this paper is to point out the various ways in which design is taught in standard four-year mining engineering curricula in American colleges and universities; to discuss the reasons apparently justifying the great diversity of procedure that exists along this line; and to indicate possible solutions to the difficulties now attending the teaching of design. A study was made of typical four-year mining engineering curricula in 15 colleges and universities of the United States (Table I). Great diversity in content of the various design courses, if taught as described, became apparent immediately. It appeared that it might be both interesting and instructive if the cause for this colorful variety could be found. Was the cause local mining conditions, departmental individuality, or actual necessity? Study of the school catalogues revealed that the various design courses could be classified into two fairly distinct types; namely, (I) those dealing with mine equipment or structures, and (2) those dealing with underground layout of mine workings. It seemed reasonable to label the first type of course "mining design" and the second type "mine design." Some such distinction must have been in the minds of mining educators, for we find both names (i.e., mine design and mining design) used to designate the design courses included in the various mining curricula Unhappily, the name and the apparent content of such courses do not, in all instances, conform to the classification made here, although in most instances such conformation does obtain (Table I). It is possible that in the exceptional case the method of teaching a design course, and consequently the content of it, may have been changed at some time without change in the name of the course. Apparently only 3 of the 15 schools made an effort to cover both types of design in their curricula (Table I). Two other schools did not list or describe any course of study that could with certainty be taken as a design course. Of the remaining 10 schools, 9 gave a mining-design type of course and one gave a strictly mine-design type. Obviously, the preponderance of design courses afforded are of the mining-design type. Why? To answer this question, it is necessary to make a study of the prerequisites for the two types of design courses taught. In all schools the design courses were taught in the senior year; in eight, design was taught throughout both semesters; in two, it was taught during the first semester only; and in three it was taught during the second semester only. Consequently, excepting the last three cases noted, it is obvious that all prerequisites for a design course should be completed by the end of the junior year PREREQUISITES What are the probable prerequisites for the different kinds of design courses as they appear to be taught? Let us take first the case of the mine-design type of course, having to do with layout of underground workings. Here it would seem that logical

Jan 1, 1943

By J. W. Stewart

The aim of this paper is to point out the various ways in which design is taught in standard four-year mining engineering curricula in American colleges and universities; to discuss the reasons apparently justifying the great diversity of procedure that exists along this line; and to indicate possible solutions to the difficulties now attending the teaching of design. A study was made of typical four-year mining engineering curricula in 15 colleges and universities of the United States (Table I). Great diversity in content of the various design courses, if taught as described, became apparent immediately. It appeared that it might be both interesting and instructive if the cause for this colorful variety could be found. Was the cause local mining conditions, departmental individuality, or actual necessity? Study of the school catalogues revealed that the various design courses could be classified into two fairly distinct types; namely, (I) those dealing with mine equipment or structures, and (2) those dealing with underground layout of mine workings. It seemed reasonable to label the first type of course "mining design" and the second type "mine design." Some such distinction must have been in the minds of mining educators, for we find both names (i.e., mine design and mining design) used to designate the design courses included in the various mining curricula Unhappily, the name and the apparent content of such courses do not, in all instances, conform to the classification made here, although in most instances such conformation does obtain (Table I). It is possible that in the exceptional case the method of teaching a design course, and consequently the content of it, may have been changed at some time without change in the name of the course. Apparently only 3 of the 15 schools made an effort to cover both types of design in their curricula (Table I). Two other schools did not list or describe any course of study that could with certainty be taken as a design course. Of the remaining 10 schools, 9 gave a mining-design type of course and one gave a strictly mine-design type. Obviously, the preponderance of design courses afforded are of the mining-design type. Why? To answer this question, it is necessary to make a study of the prerequisites for the two types of design courses taught. In all schools the design courses were taught in the senior year; in eight, design was taught throughout both semesters; in two, it was taught during the first semester only; and in three it was taught during the second semester only. Consequently, excepting the last three cases noted, it is obvious that all prerequisites for a design course should be completed by the end of the junior year PREREQUISITES What are the probable prerequisites for the different kinds of design courses as they appear to be taught? Let us take first the case of the mine-design type of course, having to do with layout of underground workings. Here it would seem that logical

Jan 1, 1943

By P. E. Chapman, J. E. Worthington, I. T. Kiff

Increases in the price of gold starting about six years ago, and rapid fluctuations since then, have created a substantial popular interest in the noble metal. Gold prospecting had been at a low ebb since the end of World War II in most of the United States, except for a flurry of activity in Nevada after the Carlin and Cortez discoveries. The last few years, however, have seen a great awakening of interest in gold exploration as well as an opportunity for education for many explorationists in the geology and other vagaries of gold deposits. The writers have participated over the last few years in a search for gold deposits throughout the United States. This search was greatly influenced by the geologic studies of Dr. William Spence at the Haile gold mine in South Carolina, as reported in a companion paper. Spence's studies resulted in definition of a geologic model that has proven useful in a number of other geologic environments in the United States. These programs were all carried out under the auspices of Cyprus Mines Corp. and permission by Cyprus to present these results is gratefully acknowledged. The writers, however, reserve for themselves all responsibility for the results and conclusions. The exploration program to be described began in the southeastern United States. Spence's studies provided a reasonable basis for interpreting and understanding the geology of the Haile deposit, and also provided a means for predicting additional occurrences. This concept was then expanded to other gold occurrences in the Piedmont, and became an effective tool for evaluating other prospects. Finally, it became evident that the concept could be applied in some western gold districts. The following discussion will then include descriptions of other Piedmont examples and a few western districts that also appear to fit the pattern.

Jan 1, 1981

By M.J. Mitchell

Platinum-group minerals (PGM) are recorded from a number of localities along the Waiau River, western Southland, and the south coast of the South Island, New Zealand. At each locality, small amounts of PGMs were recovered as by-products of historical gold mining operations. During the period 1890-1950 an estimated 1000-2000 oz. of "platinum" were recovered from the region, the only area within New Zealand where PGM have been commercially exploited. The PGM suite of southern New Zealand consists of Pt-Fe alloys, IPGE (iridium subgroup, platinum-group elements) alloys, sperrylite (PtAs2), cooperite (PtS)and braggite ((Pt,Pd)S). The composition of Pt-Fe alloy exhibits considerable variation and two compositional populations are recognised. Some Pt-Fe alloy grains are chemically zoned. Iridium is the most abundant IPGE alloy phase and often contains considerable Pt, in contrast to osmium and ruthenium alloys. Cooperite and braggite grains are characterised by extremely low concentrations of Ni. R^~

Jan 1, 1995

By R. E. Ogilvie, N. L. Peterson

Intevdiffusion and intrinsic diffusiorz coefficients were determined in the uranium-niobium system from diffusion couples analyzed with an electron microbeam probe. A Previously unveported intermediate phase, designated in this report as the delta phase, was found to exist along the mobium-rich side of the miscibility gap. Its composition width was determined from the concentration gradients in the diffusion couples. The presence of this phase was also confirmed by microhardness analysis and metallographic observations. THE excellent corrosion resistant properties, high-temperature strength and reasonable nuclear properties of niobium have prompted its use as an alloying element with uranium and as a possible cladding material for reactor fuel elements. Hence the formation and growth of intermetallic phases as well as diffusion data for the uranium-niobium system are of considerable practical importance to metallurgists and nuclear engineers. Diffusion zones may exhibit varying degrees of complexity dependi.ng upon the mutual solubility of the metals involved, and the intermediate phases which may form. In the simplest case where the metals exhibit a calmplete range of solid solubility, a single phase region is produced. Generally, however, the metals may react to produce a multiphase diffusion zone containing several layers of intermetallic phases. A number of investigatorsl-6 have analyzed the concentration gradients present in diffusion couples in order to investigate phase equilibria and solu- bility limits. If diffusion is the rate-controlling process in establishing a concentration gradient, the compositions at the interfaces of the intermediate phases will represent the equilibrium values expected from the phase diagram at the temperature at which diffusion has taken place. No published information is available at this time on diffusion in the uranium-niobium system. A number of investigators7-" have contributed information to the construction of the uranium-niobium phase diagram from other than diffusion techniques. There is good agreement on the high uranium side of the phase diagram, but the high niobium side of the miscibility gap still remains somewhat in doubt. The phase diagram as determined by B. A. Rogers, et al.7 is shown in Fig. 1. The present work was aimed at obtaining fundamental information about the solubility limits of the miscibility gap and diffusion in the uranium-niobium system. A Kirkendall effect, which might be expected on the basis of the rather large difference in melting points between uranium (1132°C) and niobium (2415" C), was also investigated. The concentration gradients were measured by an electron microbeam probe technique, similar to that used by Castaing,l2 Adda and philibert,13, l4 and Macres.4

Jan 1, 1961

By A. R. Kaufman, P. Gordon, C. H. Schramm

AS a part of the general program on alloys of uranium carried out at the Massachusetts Institute of Technology under contract W-7405-eng-175 for the Manhattan Project during the recent war, it was considered desirable to investigate the boundary binary phase diagrams of the ternary alloy system uranium-tungsten-tantalum. Previous work on these alloys was practically nonexistent. A brief statement to the effect that tantalum and tungsten form a continuous series of solid solutions was found in a general paper on tantalum by W. V. Bolton1 but no information was available on the uranium-tungsten and uranium-tantalum systems. The research to be described in this paper has served to delineate the main features of the uranium-tungsten, uranium-tantalum phase diagrams and to check Bolton's work on the tungsten-tantalum diagram. Experimental Details Metals: The tungsten and tantalum used for preparing the alloys were 99.96 and 99.65 pct pure, respectively. The chief impurities in the metals were about 0.02 pct molybdenum in the tungsten, and 0.2 pct columbium, 0.05 pct tungsten, 0.02 pct barium and 0.01 pct silicon in the tantalum. The uranium used was 99.9 pct pure, with the main contaminants being iron and carbon. (An appreciable amount of magnesium was present in the uranium as received, but this distilled off during melting and so is not reported as an impurity.) The composition of specimens indicated in the subsequent figures and tables of this paper are the results of chemical analyses on the cast alloys except for the tantalum-tungsten alloys. For the latter, chemical analysis was not very reliable as a result of the difficulty of separating tungsten and tantalum chemically. Consequently, the nominal

Jan 1, 1951

By D. Oyler

The National Institute for Occupational Safety and Health (NIOSH) Pittsburgh Research Laboratory (PRL), RAG Pennsylvania and Strata Control Technologies of Australia collaborated in an intensive study of ground behavior, reinforcement performance, and stress redistribution at the Emerald Mine in Southwestern Pennsylvania. The study site was a longwall tailgate subjected to a severe horizontal stress concentration. Field measurements indicated that the stresses applied to the study site nearly doubled during longwall mining, resulting in roof deformations extending to a height of 4.8m (16 ft) above the entry. A computer simulation of the field site was conducted using FLAC-2D, incorporating a broad range of rock behaviors and failure mechanisms. Comparison between the measurements and the simulation showed that the model was able to capture the most significant aspects of the roof and support system behavior, particularly, the extensive slip along bedding that created a partially destressed "softened" zone in the immediate roof. The model also showed that supplementing the normal roof bolt support pattern with cable bolts would allow the entry to survive a further 20-25% increase in the applied horizontal stress. Such information could have very practical application to the design of roof support systems for coal mines.

By John G. Henning

Unplanned ore dilution has a direct and large influence on the cost of a stope, and ultimately on the profitability of a mining operation. This paper presents results of a study on the influence of a variety of factors on ore dilution in a blasthole stoping environment. A series of 3-D numerical models were developed and analyzed to examine the effect of mining depth, stope geometry and stope setting within the orezone extraction sequence. To quantify modelled ore dilution from the three-dimensional simulations, the ore Dilution Density (DD) is a term introduced in this study to denote potential hanging-wall overbreak. It was found that hanging-wall overbreak is not significantly influenced by depth alone, and that stopes with large or small axial ratios are more stable than large rectangular stopes. It was also demonstrated that, in addition to stope dimension, the amount of unplanned dilution differed according to stope type. Five stope types were identified, based on their position within a tabular blasthole mining sequence. The methodology presented in this paper can be adopted to develop mine-specific design tools for the estimation of ore dilution associated with a proposed mine design. This can prove extremely helpful in the process of underground mine planning and optimization.

May 1, 2007

By H. Kandemir, G. Neeling, P. A. Spencer

Gold extractions from three refractory sulphide concentrates have been increased by bacterial oxidation with T. ferrooxidans prior to cyanide leaching. Arsenopyrite, pyrite and stibnite were the major sulphide components associated with gold in the concentrates examined. Kinetic oxidation tests were conducted for each concentrate by monitoring iron and arsenic levels in leach slurry. A correlation has been established between the level of bacterial oxidation and gold extraction from cyanide leaching of oxidised residues. High levels of bacterial oxidation have been achieved in approximately 8 days at pulp densities of 20-25/ w/v solids, resulting in 70-90% gold extraction.

Jan 1, 1987

By Edmund Leaver

IT is generally recognized that the .addition of limited small amounts of various lead salts may aid the extracting power of the mill cyanide solution in the dissolution of silver from ores and in some cases may aid in the treatment of gold ores. Excess soluble lead compounds retard the dissolution of precious metals by the usual mill cyanide solution. Another phase of cyanidation is the use of the zinc-lead couple as an aid to better precipitation of gold and silver from solution containing a low percentage of cyanide. The chemistry of the use of lead salts in cyanidation has been dis-cussed by Clennell;1 the addition of lead salts in various cyanide mills is recorded by von Bernewitz;2 and the reasons for the use of lead salts in cyanidation have been explained by Clevenger.3 This paper deals with the adaptation of cyanidation to a different condition, in which the presence of lead minerals in a gold ore that is refractory to direct cyanidation complicates the treatment. If free gold is roasted in the presence of sulfur and lead salts, or if pyritic gold ores containing even a small percentage of lead minerals are roasted to free the gold from the pyrite, lead compounds coat the gold particles enough to make them almost insoluble in the usual mill cyanide solution contain-ing lime for protective alkalinity. Also, the lead compounds remaining in the calcine are slightly soluble in the mill solutions and such dissolved lead may retard the dissolution of the gold by the removal of oxygen or

Jan 1, 1933

By P B. Hills, R J. Walton

Narrow vein tabular orebodies are prone to mining induced seismicity. The Tasmania Mine is a complex example of a seismically active tabular orebody, where the contrasting material properties of the host strata and of the orebody itself, serve to exacerbate the seismic response. Analysis of a continuous record of seismicity over a period of seven years has provided significant insight into the fundamental mechanics of the rock mass. Understanding seismicity to permit safe extraction of the orebody has been enhanced by instrumentation of rock mass behaviour in response to mining and mining induced seismicity. It is the purpose of this paper to explore that understanding in respect to the adoption of an alternative down-hole Avoca stoping method for use in particular circumstances.Intensive instrumentation of the Tasmania Mine over a period of four years has provided insight into the behaviour of the rock mass in response to extraction of the narrow vein orebody it encompasses. A range of instruments have been installed in clusters or single installations in order to measure changing stress conditions and the impact of those changes on the rock mass and the reinforcement system.Instruments are often installed in very close proximity to active production stoping. While it has been possible to observe the impact of the mining and mining induced seismicity at very close quarters, instruments installed in these locations are vulnerable to damage and consequently, the level of instrumentation is high. Instruments are continuously logged, typically on a six hourly basis coinciding with the end of regular blasting times. The response of the instrumentation to changed rock mass conditions is considered against the background of development and production blasting and against the seismic record to assess the viability of downhole Avoca stoping.CITATION:Hills, P B and Walton, R J, 2012. Continued observations of rock mass behaviour in response to stoping at the Tasmania mine, Beaconsfield, Tasmania, in Proceedings Narrow Vein Mining 2012 , pp 169-178 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 26, 2012

By T. V. Philip, Paul A. Beck

IN a previous note1 it was pointed out that the available information suggests a distinct correlation between the occurrence of the CsCl-type ordered structures formed in equi-atomic binary alloys of transition elements and the location of the components in the periodic table. A definite increase in the bond strength between unlike atoms, as compared with that between like atoms, is indicated when, in binary alloys of iron group elements, the other component is changed from chromium to vanadium or tantalum, to titanium. Laves and Wallbaum,2 eported a CsCl-type ordered structure for the stable intermediate phase at the equi-atomic composition in the Ti-Fe system (and also in the Ti-Ru and Ti-Os systems). On the other hand, Tagaya, Nenno, and Nishiyama8 found no ordering of this kind in the body-centered-cubic solid solutions in the Cr-Fe system. It was concluded' that the occurrence of a CsC1-type ordered phase of intermediate stability may be expected in the V-Fe system. Preliminary results were described: suggesting that at least some degree of order does exist in the equi-atomic alloy VFe, annealed at 1200° C and quenched in cold water. Using CrK radiation, at least one weak superlattice line was found in the X-ray diffraction pattern which could be indexed as (100). and which disappeared, as expected, when FeK radiation was used. It was found more recently that the impurity phase (presumably VN), previously giving rise to additional X-ray diffraction lines and thus preventing definite indentification of the (111) superlattice line,' can be eliminated by preparing the alloy by arc melting in a helium atmosphere. The alloy specimen melted in this manner had clean surfaces and showed very littte, if any, nitride phase in the microstructure after annealing in vacuum at 1250°C and quenching. The relative intensity of the (100). superlattice line with CrK radiation was greatly increased and, in addition, a fairly strong (Ill) , superlattice line and even a detectable (210) , super- lattice line was obtained, when the powder produced by filing from the 1250°C annealed and quenched specimen was reannealed in vacuum at 625°C for 1 hr. By using a cellulose acetate film as a filter in front of the photographic film in order to absorb the soft radiation resulting from air fluorescence, the background intensity could be reduced considerably in relation to the intensity of the diffraction lines. All three superlattice lines, (100),, (111)., and (210)a, disappeared, as expected, when a radiation other than CrK, was used.1 For the powder reannealed at 625ºC, the strongest lines of the s pattern also appeared weakly, indicating that during an: nealing at 625°C a small amount of transformation took place from the body-centered-cubic to the u phase. However, since all superlattice lines to be expected in the 0 angle range used were actually very clearly present, it was evident that the high temperature body-centered-cubic phase had transformed into a CsCl-type ordered structure before much s phase could form. Reannealing filings for 1 hr at 700°C resulted in complete transformation into the u phase. After 1 hr at 650°C the transformation into IT was not quite complete, the strongest body-centered-cubic diffraction lines were still present, although fairly weak, and only the (100), super-lattice line was detectable (extremely weak). These findings not only confirm the previous conclusionsL as to the existence of a CsCl-type ordered structure in the Fe-V system, but they also indicate that this metastable ordered structure forms at about 600°C preceding the formation of the stable s phase, while at 1250°C the disordered body-centered-cubic phase is stable. The faint (loo) , super-lattice line previously observed in specimens quenched from 1200°C was probably due to the fact that the quenching of the powder in an evacuated fuse:! quartz capsule was not fast enough to prevent completely the ordering reaction on cooling. The present results conform with the suggestion that the A-B bond, in relation to the A-A and B-B bonds, increases in strength from CrFe to VFe to TiFc. It is, therefore, of interest to compare the measured values of the average atomic diameter for these three alloys with the corresponding average atomic diameters calculated from the atomic radii of the elements concerned. ASSUming A-B contacts

Jan 1, 1958

By Albert J Hoskinson

Progress on the earth depends to a large extent upon the rapid interchange of ideas and commodities between the various nations of the world. The smooth flow of commerce, by which these ideas and commodities move, is accelerated by accurate and complete maps of the various land and water areas of the earth. The production of accurate maps depends upon a complete knowledge of the figure and dimensions of the object to be charted, therefore a knowledge of the shape of the earth is a prime necessity for accurate charting purposes. Gravity observations were first undertaken to aid in determining the shape of the earth so that the geodetic surveys of its land and water areas might be more accurately connected to form an undistorted map. A large part of the earth's surface is water and it is therefore necessary to get gravity values at sea as well as on land before a complete and accurate figure of the earth can be determined. Dr. F. A. Vening Meinesz, of Holland, was the first scientist to perfect a pendulum instrument that would accurately measure gravity at sea. He had previously developed a multiple pendulum apparatus for measuring gravity upon swampy and unstable land areas in Holland and it was therefore quite natural that he should adapt the instrument to give accurate results upon a still more unstable support, the surface of the sea. His instrument as perfected gives satisfactory results when mounted in gimbals on any vessel where the roll and pitch are not more than about 5" and where the vibrations from rotating machinery and wave action are not large enough to cause the pendulums to shift on the knife-edges. This degree of stability can be obtained on surface craft only in protected waters or on very calm days. Therefore, Dr. Meinesz mounted his instrument in a submarine so that he could submerge below the disturbed surface waters and get the desired stability in nearly any kind of weather by simply diving to greater depths. Most of the gravity-at-sea work has been done with a Meinesz instrument and a very large number of the observations have been made by Dr. Meinesz himself. He has occupied nearly 1000 sea, stations and probably has traveled as many miles by

Jan 1, 1940

By Albert J. Hoskinson

Progress on the earth depends to a large extent upon the rapid interchange of ideas and commodities between the various nations of the world. The smooth flow of commerce, by which these ideas and commodities move, is accelerated by accurate and complete maps of the various land and water areas of the earth. The production of accurate maps depends upon a complete knowledge of the figure and dimensions of the object to be charted, therefore a knowledge of the shape of the earth is a prime necessity for accurate charting purposes. Gravity observations were first undertaken to aid in determining the shape of the earth so that the geodetic surveys of its land and water areas might be more accurately connected to form an undistorted map. A large part of the earth's surface is water and it is therefore necessary to get gravity values at sea as well as on land before a complete and accurate figure of the earth can be determined. Dr. F. A. Vening Meinesz, of Holland, was the first scientist to perfect a pendulum instrument that would accurately measure gravity at sea. He had previously developed a multiple pendulum apparatus for measuring gravity upon swampy and unstable land areas in Holland and it was therefore quite natural that he should adapt the instrument to give accurate results upon a still more unstable support, the surface of the sea. His instrument as perfected gives satisfactory results when mounted in gimbals on any vessel where the roll and pitch are not more than about 5" and where the vibrations from rotating machinery and wave action are not large enough to cause the pendulums to shift on the knife-edges. This degree of stability can be obtained on surface craft only in protected waters or on very calm days. Therefore, Dr. Meinesz mounted his instrument in a submarine so that he could submerge below the disturbed surface waters and get the desired stability in nearly any kind of weather by simply diving to greater depths. Most of the gravity-at-sea work has been done with a Meinesz instrument and a very large number of the observations have been made by Dr. Meinesz himself. He has occupied nearly 1000 sea, stations and probably has traveled as many miles by

Jan 1, 1940

By J. Lee, M. Peart, T. Bhambhani, D. R. Nagaraj, P. Riccio

"Over the past decade or so, our efforts have focused on developing the rationale and concepts for new technology in reagent development and optimization in the processing of base and precious metals. A major outcome of these efforts have been the development of a novel family of collectors, principally driven by the MAXGOLD® and Aero XD-5002® chemistries, for precious metals recovery from primary Au ores and Cu-Au ores. These chemistries was developed to be robust to address the complex mineralogy and gold deportment in these ores. Plant trial data for a variety of ores have confirmed that the both Aero® XD-5002 and MAXGOLD® chemistry are indeed versatile in recovering gold values occurring as gold alloys and/or associated with many types of sulfides, and in altering the deportment of certain sulfides (such as those bearing As, Bi etc). An overview will be given in this paper using plant data to highlight the application of these reagents.INTRODUCTIONThe subject matter of this paper is the flotation of Au containing minerals from their ores. The motivation from this manuscript comes from the several challenges faced with the processing of Au ores, as was articulated in detail by Nagaraj (2008). The biggest challenge is the complex mineralogy; most easy-to-treat free-milling ores bodies are largely depleted. The Au values are distributed in multiple host minerals such as pyrite, pyrrhotite, arsenopyrite and Cu minerals such as chalcopyrite. Au values also happen to be finely disseminated within the various minerals and are sometimes invisible in optical microscopy. Additionally, on any given day, some mines treat multiple ore types, and the mineralogy is different for each ore type.Xanthates continue to be the collectors of choice at most Au and PGM operations around the world. Most primary Au operations tend to consume very large amounts of collectors; the dosage ranges anywhere between 40-400 g/t and this has been attributed to both mineralogical and non-mineralogical factors (non-mineralogical factors include the low cost of xanthates and the mindset that “more is always better”, which is not necessarily the case). In addition, several studies now show that xanthates alone are never sufficient where multiple value minerals are present, and that supplementary collectors are required. The large doses present a substantial cost to the minerals industry, and many mining companies have expressed the need for more efficient reagents that can improve metallurgical performance at low dosages."

Jan 1, 2013

By M. Mirnezami, J. A. Finch

The McGill component of the consortium contributed detailed examination of the electrokinetic properties of the constituent minerals, primarily pentlandite and serpentine. Mineral specimens were derived from an ore sample; mineralogical examination showed the serpentine was predominantly clinochrysotile, a fibrous mineral responsible for much of the flotation separation problem. The study included design of a novel sedimentation potential measuring device to classify the surface charge of the ore and electrophoresis measurements on single and mixed minerals which progressively approached flotation conditions. The sedimentation potential measurements provided a general association between surface charge and the visual state of aggregation as a function of pH. The electrophoresis experiments started with single minerals in a background of indifferent electrolyte and progressed to mixed minerals in a background of supernatant derived from an ore sample. The single mineral tests supported the suspected electrostatic interaction, i.e., hetero-coagulation, at flotation pH 9-10. The mixed mineral tests demonstrated this interaction and also revealed hetero-coagulation with Mg(OH)2 precipitates, derived from the supernatant. This interpretation was confirmed by optical and electron beam imaging. A series of agents, CMC, polyphosphate, soda ash, EDTA, were examined to disperse the system. To accommodate the small mass of single mineral available a novel turbidity measurement using a UV/Vis spectrophotometer was introduced. Selected conditions were used in contact angle and small-scale flotation tests.

Jan 1, 2011

By G. A. Savanick

Borehole (slurry) mining, where a tool incorporating a water-jet cutter and a downhole slurry pump mines phosphate through a borehole, was field tested in northeastern Florida as part of a US Bureau of Mines program to increase the domestic availability of critical minerals. About 1.5 kt (1700 st) of phosphate ore were mined at 23.6 t/h (26 stph) from a depth of 76 m (250 ft). The borehole was filled with water during mining for roof support and to assist slurry pumping. Underwater cutting was enhanced with an air-shrouded water jet. Mined cavities were backfilled to prevent subsidence after abandonment. Roof subsidence during mining was avoided only when the cavity was filled with water. Environmental monitoring before, during, and after mining included hydrological studies and measurements of water quality. Significant water quality changes occurred only in the zone being mined and were confined to the immediate area of the borehole.

Jan 1, 1986

Grade control plays an essential role in the good running of a mine. The factors at play are many, starting from a good analysis of the geology and a correct sampling procedure. Once this is achieved (and it is an essential prerequisite), the problem is to adequately define what is ore and what is waste. This paper tries to show, through a small example, how simple geostatistical techniques (variography, and moving average or kriging), can help in accurately defining these limits in a geologically homogeneous zone, thus allowing optimal use of the available information.

Jan 1, 1987