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By K. Blaski

his paper reports an investigation aimed at optimizing the compaction of granulated hard-metal powder for the production of cutting tool inserts. The optimal compaction is that which yields optimal shrinkage during sintering, i.e. minimum porosity in the sintered part. Extensive compaction tests on 23 different hard-metal powders have been carried out and have shown that the ideal ?green density? of a hard-metal compact, i.e. the density after compaction, increases linearly with the apparent density of the powder. On the basis of this result, an equation has been derived, which allows one to predict the optimal shrinkage that a hard-metal compact undergoes during sintering once the following data are known: the required sintered density, the volatile content of the powder and the apparent density of the powder. Since these data are available to the tooling designer, this equation allows one to design tooling for the compaction of hard-metal, which leads to optimal shrinkage

Jan 1, 2007

This information circular describes research the Bureau of fines has conducted to improve technology for recovering precious metals from low-grade resources. Many of the reported findings are recent, and some of the work described is ongoing. Topics discussed include cyanidation of carbonaceous gold ores to enhance gold recovery, a new method for precipitating mercury during cyanide leaching of gold ores, a staged heap leaching process to generate suitable solutions for direct electrowinning of gold, the use of anion-exchange resins to recover gold from cyanide solutions, and precious metals recovery from electronic scrap.

Jan 1, 1986

By Youngkook Lee

The precipitation kinetics of NbC in ferrite matrix of the Nb microalloyed steel was investigated experimentally and numerically. The mole fractions of NbC precipitates formed at different isothermal temperatures were measured as a function of holding time by electrical resistivity test and were compared with both a mathematical model based on time-dependent nucleation and growth rates and the hardness. There is a good match among the calculated and measured precipitation kinetics of NbC and the hardness. The isothermal precipitation-temperature-time diagram of NbC in ferrite matrix of the Nb microalloyed steel was newly generated. Keywords: Precipitation, Carbide, Ferrite, Nucleation, Growth, etc

Jan 1, 2003

The heat of immersion of coals in different immersional liquids is measured as a function of particle size and moisture content. Decrease in particle size shows a concomitant increase in the heat of immersion. The heat of immersion is dependent upon the nature of immersional fluids. In addition the nature of moisture present in coal influences the heat of immersion.

Jan 1, 1993

Many aspects of best practice resource evaluation do not create value, but poor practice can certainly destroy value. Generally companies prefer to present how their good practice adds value and for this reason few publications exist on examples of how poor practice can destroy value. However in big and small companies there are many previous and current examples of poor practice destroying value. The incremental expenditure required to move from poor practice towards best practice can be looked upon as insurance against destroying shareholder value. Examples of how poor practice in geology has destroyed value are presented as well as the improvement model used by BHP Billiton to add value and insure against destroying value.

Jan 1, 2002

By D. E. Traut

A fluidized countercurrent ion-exchange system was developed, operated, and evaluated by the U.S. Department of the Interior, Bureau of Mines. The system consisted of integrated multiple-compartment absorption and elution columns in which the solution flows were continuous except for short periods when resin increments were withdrawn. The exchange of uranyl carbonate between a simulated in situ uranium leach liquor and a strong-base ion-exchange resin together with the subsequent elution with an ammonium chloride solution was studied. The effects of the number of sections, section height, amount of resin withdrawal, solution flow rate, and column diameter were investigated. The kinetic and equilibrium relationships for the absorption and elution steps were also examined. The experimental data indicate a strong interdependence between variables. Solution retention time appears to be a major limiting variable in the absorption process, while resin residence time is the determining factor in the elution process. The column was efficient over a range of conditions, but close control was needed for optimum operation.

Jan 1, 1978

By M. Massinaei, M. R. Yarahmadi, S. Zeidabadi, M. Oliazadeh

"Although the majority of new flotation column installations continue to be for cleaning or recleaning, an increasing number of flotation projects are specifying columns for roughing or scavenging duties. NICICO has recently installed flotation columns operating in rougher, cleaner and re-cleaner circuits at three new copper concentrators; Miduk, Sungun and Sarcheshmeh. Miduk is probably one of the unique operations that use flotation columns in a rougher circuit. The Miduk rougher circuit comprises five CISA parallel columns. The rougher concentrate constitutes 88% of final concentrate and reports to concentrate thickener. The rougher tailings are scavenged with ten 50 m3 mechanical cells. The scavenger concentrate is then reground and cleaned in three 3.2 m columns in parallel. The cleaner tailings are scavenged in six 50 m37mechanical cells. The cleaner tailings along with the rougher scavenger constitute final tailings.In Sarcheshmeh, the cleaner concentrate is re-cleaned in a column. The column tailings are sent back to the cleaning circuit and the concentrate is reported to the concentrate thickener.This paper reviews performance details of the flotation columns utilized in rougher circuits at Miduk and compares their metallurgical performances in an industrial scale with columns at cleaning circuits for copper flotation. Practical limitations for applying the flotation columns in rougher circuits will be discussed in details.INTRODUCTIONThe use of flotation columns has grown rapidly since the first successful commercial application at Mines Gaspe, where columns were used in a cleaning circuit to float molybdenite. Early applications of columns were restricted to replacing or adding final cleaning stages in existing circuits. Columns can achieve superior cleaning as compared to conventional cells due to their ability to support a large froth depth and the use of water for washing froth. Wash water travels down through the froth and crosses the pulp/froth interface, replaces the entrained particles reporting to the froth from pulp and improve the concentrate grade."

Jan 1, 2011

By Quentin L. Rhoton

"The use of explosives in a surgical manner was approved to facilitate, due to time constraints, anextremely significant paleontological find in the Plunket Point area of the Dominion Range, Antarctica. The organic material revealed by surgical blasting techniques may have altered basic scientific dogma on Antarctic glaciation theory."

Jan 1, 1999

By P. Rosario

"Industry practice for high-pressure grinding roll (HPGR) assessment and sizing relies on tests using pilot-scale machines with 0.7–1.0 m roll diameters. Typically 1–10 t of sample are required, depending on the level of study and resource complexity. This is challenging during early-stage development, which hinders incorporating HPGR into designs. With support from the Canadian Mining Industry Research Organization, researchers at the Norman B. Keevil Institute of Mining Engineering at The University of British Columbia developed bench-scale piston–die press tests (PPTs) that correlate to pilot- and full-scale HPGRs. This paper describes a new regression model to estimate the HPGR-specific throughput rate using both PPT results and an HPGR database. A case study is presented to show how the current PPT method is used for engineering studies. ¦ KEYWORDS Empirical modelling, High-pressure grinding roll (HPGR), Piston–die press test (PPT), Sizing and scale upRÉSUMÉ La pratique en vigueur dans l’industrie concernant l’évaluation et le calibrage d’un cylindre de broyage à haute pression (HPGR, de l’anglais high-pressure grinding roll) dépend d’essais menés à l’aide de machines à l’échelle pilote dont les diamètres de bobine sont de 0,7 à 0,10 mètre. On a généralement besoin de 1 à 10 tonnes d’échantillons en fonction du niveau de complexité de l’étude et des ressources. C’est une pratique difficile durant les premières phases de développement, qui empêche l’intégration du HPGR dans les plans. Bénéficiant du soutien de la Canadian Mining Industry Research Organization (CAMIRO, l’organisation de recherche de l’industrie minière canadienne), des chercheurs du Norman B. Keevil Institute of Mining Engineering (l’institut Norman B. Keevil de génie minier) de l’université de la Colombie-Britannique (UBC) ont mis au point des essais en laboratoire sur des presses à matricer à pis¬ton (PPT, de l’anglais piston–die press tests), qui mettent en corrélation les HPGR aux échelles pilote et réelle. Cet article décrit un nouveau modèle de régression qui évalue le taux de production spécifique aux HPGR à l’aide des résultats tirés des PPT et d’une base de données dédiée aux HPGR. Une étude de cas est présentée afin de décrire l’utilisation de la méthode actuelle des PPT dans les études techniques. ¦ MOTS CLÉS calibrage et mise à l’échelle, cylindre de broyage à haute pression (HPGR), essai sur presses à matricer à piston (PPT), modélisation empiriqueINTRODUCTION It is widely accepted that high-pressure grinding rolls (HPGRs) are a viable, energy-efficient solution for modern comminution flowsheet design. Table 1 summarizes select examples of HPGR applications in the mining industry. The main benefits of HPGRs are energy savings, which leads to lower operating costs, and stable operating characteristics that can better cope with variations in ore hardness compared to the conventional autogenous (AG) or semi-autogenous (SAG) mill-based comminution circuits."

Jan 1, 2019

By Tracy E. Chantson, Brian R. Green, Kenneth G. Ashurst

Work that has culminated in the manufacture and testing of a old-selective resin on a pilot-plant scale is dcscribed. Following a brief discussion about the nature of commercially available resins which identifies them as poor candidates for a gold extraction application, the improved properties of the new type of resin are illustrated using results from comparative loading tests. Further results from continuous countercurrent extractions using synthetic leach liquors and elution work using thiourea as the eluant demonstrate the superiority of the new resin over commercial resins and hence, its potential for use in a resin-in-pulp process for gold.

Jan 1, 1989

By George M. Douglas

The southeastern shores of Great Slave lake present a curious anomaly in geographical and geological exploration, in that an area so large and important, and withal so comparatively accessible, should nevertheless have remained unexplored, unmapped, and indeed almost unknown, until quite recent" times On their return from the famous journey to the mouth of the Coppermine, the band of Indians with whom he travelled led Samuel Hearne across Slave lake. He was the first white man to see that great body of water and it is rather curious that it should have been seen first from the north rather than from the south. Hearne's account of the lake is vague, and he made no attempt ?to map the part through which he travelled. About 30 years later John Franklin, on his first journey to the Arctic, crossed the lake from the mouth of the Slave river to the Yellow Knife river. Franklin's maps show all of his route in accurate detail, except that part of it which lay through Slave lake. In 1833-34, Captain, afterwards Sir George, Back made the first exploration of the eastern end of the lake. Captain Back was then on his way to the Arctic coast by way of the Great Fish river, and his Indian guides led him through Great Slave lake by the route they had followed from time immemorial. This route, partly because of its directness, and partly because of its sheltered character, lay through the great mass of islands in the middle of the lake to the Talthei narrows, and thence along the sheltered north shore with its many coves and harbours. Pere Petitot made extensive journeys in Slave lake as well as other parts of the far north.

Jan 1, 1929

By David Conover

The El Boleo Copper Project is currently in the final design stages for development of a 3-MM-tonne/yr underground copper mine located in Baja California, Mexico. The nearly horizontal mineralized zones are amenable to exploitation by conventional mechanized coal mining technology using continuous miners, shuttle cars, and belt haulage. The mine design resembles a typical full-extraction coal mining operation utilizing a sequence of mains, sub-mains and production panels. Due to numerous faults, mining will be conducted as several small adjacent mines accessed through adits from large arroyos cutting through the mine area. Up to four seams may be mined in some areas with a maximum overburden depth of about 250 m. The ore zone is relatively weak and plastic, subject to extensive creep over time. The mine workings will pass through areas of historical shortwall mining panels where the ground has flowed into old entries and gob areas, and then reconsolidated. A small test mine was developed to evaluate mechanical cutting performance, roof-bolt anchorage capacities, roof and pillar stability and caving behavior. In-mine measurements were combined with two- and three-dimensional FLAC models to evaluate alternative development and production pillar designs. The paper will discuss the various factors influencing ground stability at the El Boleo project and the strategies employed in developing a suitable ground control design.

Jan 1, 2009

By William J. Rothschild

Ground water at construction sites can be controlled by properly placed wellpoint dewatering systems. Care must be taken in planning cofferdams to have adequate space for and access to pumps, headers and the points. A most important part of dewatering is protection of adjacent structures from movement. A checklist gives items to consider in bidding.

Jan 1, 1984

By Verne E. Hooker

This Bureau of Mines report summarizes the results of modifications in the borehole deformation gage design and subsequent changes in the overcoring techniques. Modifications in the borehole deformation gage have greatly improved the creep characteristics and enhanced the versatility of the gage. In situ field tests in competent rock near St. Cloud, Minn., provided sufficient data to compare the reliability between gages and new techniques in obtaining good engineering estimates of stresses. Near-surface horizontal stresses at the test sites are compressive and biaxial in nature.

Jan 1, 1974

By Reynold Q. Shotts

CHEMICAL methods, based on the relative rates of oxidation of fusain, bright coal, and dull coal by nitric acid, have been devised to determine these coal components.1-4 Results obtained by oxidation methods for fusain have been checked against results obtained from microscopic methods5, 6on duplicate samples of the same coals, but to the author's knowledge this has not been done for bright and dull coal components. For this reason it is not certain that the two methods of analysis identify essentially the same chemical or physical units. It would be highly desirable to see results of the application of both methods to duplicate samples, but in the absence of any such data the author has attacked the problem indirectly. From the U. S. Bureau of Mines samples were obtained of three Alabama coals which the USBM had analyzed optically and reported on over the past 30 years. These samples were subjected to analyses by oxidation rate methods. Results of this work, and comparisons with the USBM analyses, have been published." This was the first indirect approach to the problem. The present report attempts a second indirect approach by way of internal validation. By nitric oxidation samples of two whole coals were carefully analyzed for fusain, bright coal, and dull coal. One coal was analyzed in duplicate. Duplicate portions of each of the coals were divided into three density fractions by means of heavy liquids. A duplicate portion of one of the coals was divided by sieving into three size fractions. Each fraction was analyzed by oxidation and its percentage composition calculated in terms of fusain, bright coal, and dull coal. Because the weight percent of each fraction was known, a material balance calculation for the whole coal was also made. The resulting reconstituted analysis of the whole coal could be compared to that determined by direct analysis. In addition, specific reaction rate constants were determined for each component and for each whole coal or fraction. Arbitrary reactivity indexes were calculated by dividing by 100 the sum of the products of the percent of each component in the coal and its specific reaction rate constant. The resulting figure was an average reactivity index for each coal or fraction. Weighting the reactivity indexes for each fraction by the percent of the fraction in the coal gave a reactivity index for each whole coal which could be compared to that calculated directly from the whole coal analysis. If oxidation analyses really delineate definite physical entities within the coal, or even definite groups of similar entities, reconstituted analyses calculated from fraction analyses should check closely those made of the whole coal. It probably is true that optical methods identify and describe a greater variety of components than do chemical methods and that variations are wide in the appearance and quantity of those components identified optically. Chemical methods based upon differences in oxidation reaction rates would of necessity be less discriminating, as between similar components, than would optical methods. The procedures followed for oxidizing the samples, analyzing the residues, plotting and calculating the percentage of each component, and calculating its specific reaction rate constant have been fully described.'-' In brief the method originally proposed by Fuchs et al.1 for the determination of fusain consists of the oxidation of small samples of coal in boiling 8N nitric acid in a condenser-fitted flask. After boiling for periods of 1/2 to 4 hr, the unoxidized residue is filtered and washed. The washed residue is treated with normal sodium hydroxide, diluted, and allowed to stand for several hours. The resulting brown liquor is removed, and the filtered residue dried, weighed, ignited, and weighed again. The ash-free residue is expressed as a percent of original dry, ash-free coal. The percent residue is plotted against time, and the extrapolation of this line to zero time gives the percentage of dry ash-free fusain present in the original sample. The shape of the resulting time plots has been explained' by the assumption that they are the result of two different types of reaction, the first part representing a first order reaction with rate a func-

Jan 1, 1956

By F. Lambert

"Amok Ltd./Cluff Mining operates a uranium mine at Cluff Lake in northern Saskatchewan. The project consists of one open pit and one underground mining operation along with a full-scale milling installation.The underground stoping operations are of the narrow vein type and are done between two levels 50 m apart. The mining method is undercut with concrete backfilling. Cuts are 3.5 m in height and can be as narrow as 1.4 m in width.Stoping operations are mechanized utilizing a CT-500E electric Microscoop marketed in Canada by Teledyne. The machine is only 85 cm in width and does all the mucking in stopes. Ore passes are provided in stope roughly every 40 m to 50 m.This paper describes the utilization of the CT-500E Microscoop in the company's underground operations and provides performance data related to the experience.IntroductionThe Amok Ltd ./Cluff Mining operation is located in the northwestern corner of Saskatchewan. The project started in 1980 with open pit mining and milling operations. In 1983, an underground mining operation began production . Today, the Amok Ltd./Cluff Mining installation produces 800 tonnes of uranium per year , which originates from both the open pit and the underground mine at about the same proportion."

Jan 1, 1990

By A E. Annels, G F. Johansen, B W. Cuffley

Nuggety gold-quartz reefs are characterised by localised, high-grades and in many cases coarse free-gold. Geometrical and grade complexities are often observed. The high-grade regions are generally erratic and have a low continuity; though may make the deposit economic. Viable grades are generally contained within discrete oreshoots, which are surrounded by barren/low-grade material. Drilling is an effective measure of geological continuity, however grade distribution can only be reliably obtained from underground development and bulk sampling. In general terms, only an inferred resource is likely to be estimated from surface drill data alone. Underground development, further drilling and probably bulk sampling will be required to delineate inferred and indicated resources. Closely spaced development with bulk sampling is likely to be the best way to determine a probable reserve. The resource evaluation process must driven by a clear geological model that should attempt to understand the controls to reef geometry and grade distribution. Geological interpretation has traditionally been undertaken in two-dimensions, though computer software is now being used to produce three-dimensional models. Grade interpolation has generally been undertaken using classical methods, typically weighted averages, zone of influence weighting and polygonal/sectional blocks. Tonnages can generally be calculated from diamond drill and development information with a reasonable degree of confidence. Grade is much more difficult to define with confidence because of its highly erratic and discontinuous nature. To account for variability it is recommended that a best estimate be reported within a grade range, as this more accurately reflects the uncertainties involved. Reporting should be undertaken within the framework of the JORC code, but should involve special consideration of grade reliability.

Jan 1, 2000

By Bradley Stoughton

THE importance of magnesium alloys as engineering materials has increased rapidly in the past few years. The most important properties of magnesium alloys are their lightness and strength, which result in their. extensive use in aircraft and automobile construction. Recent progress in the metallurgy of magnesium seems to offer hope of the production of the pure metal at a reasonable cost. The use of magnesium would doubtless increase greatly if it could be produced at a cost comparable with that of aluminum. AA preliminary survey of the magnesium-base alloys shows that the most promising from a practical standpoint are magnesium-aluminum and magnesium-zinc as binary alloys, and magnesium-zinc-aluminum as ternary alloys. The research reported in this paper is a preliminary study' of binary magnesium-aluminum and magnesium-zinc alloys, as an introduction to a series of further investigations.

Jan 2, 1926

By F. J. Sotillo

The objective of this investigation was to determine the feasibility of using a high-pressure roll mill (HPRM) to improve the separation efficiency of dolomite from apatite in downstream operations when treating high-dolomitic pebbles. High-dolomite samples from four phosphate mines were used for the test program. The research work plan included sample characterization studies; INSTRON tests to develop preliminary crushing data; high-pressure roll mill evaluations to determine crushing parameters, such as feed rates, rolls speed and gap, and applied torque, pressure and energy; and screen, microscopy, and flotation studies to assess dolomitelapatite separation efficiency. The results of the HPRM tests show that commercial products for all four mines can be obtained. Recoveries of 74-82% of the P2O5 and rejections of 46-83% of the MgO were reported with an specific energy consumption of 0.2-0.5 of that of a laboratory rod mill.

Jan 1, 1998

By Alton Gabriel

During the fall of 1940, J. R. Thoenen of the Mining Division, Bureau of Mines, accompanied by the senior author, surveyed the more important domestic alunite deposits. Although the study was designed primarily as an economic survey, samples from a number of the deposits were collected to investigate the beneficiation of the lower-grade material.

Jan 1, 1942