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The Porgera Joint Venture commenced production during September 1990. A small tonnage underground mine extracts high grade gold ore using small scale stopes. Conventional drill and blast methods are used for development and production mining. Ground support is effected with Splitset anchors, grouted rebar bolts and grouted cable bolts. Splitsets and grouted rebar can be installed by mechanised means. Vertical crater retreat, slot and massfire, and modified VCR stoping tech- niques are used at Porgera. Stopes are backfilled with a relatively strong cemented rockf ill. Future stope sequences require recovery of pillars beside and under filled stopes.

Jan 1, 1991

By V. K. Alves, P. Lacoste-Bouchet

"In order to improve ball milling efficiency in pellet plants, Companhia Vale de Rio Doce (CVRD), experiments new technologies in Santa Luzia (M.G. – Brazil) research center facility. Pilot grinding tests have been conducted with small grinding media, size distributed from 5 to 12 mm (millpebs). Tests have been conducted on an ore from CVRD’s Usina 5 Nibrasco, in Vitória, Brazil. A sample of the regrind circuit feed was obtained and used in comparative grinding tests with two types of grinding charges: 100% balls and a blend of 70% balls and 30% millpebs by weight. According to the balls charge, the grinding media mixture has showed the following benefits: reduction of the power draw, increase of the mill capacity, reduction of the circulating load and a slight increase of the ore blaine. Following the results obtained, CVRD is going to further explore the regrinding potential of millpebs.INTRODUCTIONCompanhnia Vale de Rio Doce (CVRD) is the largest mining company in Brazil. CVRD is involved in iron, base metals, gold and bauxite industries. Moreover, CVRD operates several pelletizing plants in Brazil and in other countries.CVRD’s Center for Mineral Development (CDM) is equipped with a comminution laboratory where studies are carried out that are aimed at the optimization of existing plants at several mining sites as well as the technical and economical feasibility of new projects. The laboratory is equipped with a complete pilot plant with several mills and classifiers, enabling continuous grinding tests in grinding circuits of almost any capacity and characteristics.In January 2004, CVRD undertook to conduct pilot tests at CDM for evaluating the effect of small grinding media on ball milling efficiency. Generally speaking, it is not unusual for operators to add oversize grinding media in a conventional regrind mill. This fact originates mainly from prohibitive prices of grinding media below 25 mm due to a production capacity decrease of grinding media producers. The size of the grinding media is an important variable affecting ball milling efficiency. Use of oversize balls decreases the number of contact surface between which particles can be caught and broken."

Jan 1, 2005

By G. St. J. Perrott, G. W. Jones

"In the course of its investigations pertaining to the promotion of safety the Bureau of Mines is actively engaged in investigating all promising materials that may be of value in rendering methane or other combustible gases, vapors, or solids less inflammable.Added substances are of value if such additions narrow the limits of inflammability, raise the ignition temperature, lower the speed of propagation of flame, or reduce the maximum pressure developed. Of major importance is the effect of added materials on the limits of inflammability, because methane is the chief combustible s liberated in mines, considerable work has been done with extinguishing agents on methane flames. For obvious reasons, a substance to be of value for the extinction flames should be a gas, or a liquid having a sufficient vapor pressure to give concentrations of the vapor in sufficient amounts to extinguish the flames or markedly narrow the limits of inflammability. The substance should be nontoxic, cheap, and noncorrosive and must be incombustible. Solids, such as rock dust, are undesirable and of little value for combustible gases because they soon settle out of the atmosphere, and their flame- extinguishing value is thereby lost. There are at present only a few gases and vapors-for example, nitrogen, carbon dioxide, and carbon tetrachloride-which meet these requirements.The extinction of methane flames by nitrogen, carbon dioxide, and argon has been reported by Coward and Hartwell 4; the extinction by water vapor by Coward and Gleadell 5, and the extinction by helium and carbon tetrachloride by Coward and Jones 6."

Oct 1, 1930

By J. A. Mielczarski

Surface properties of minerals could be modified selectively and very specifically by adsorption -desorption (dissolution) processes. This requires a monitoring and control of the outermost surface layer at a molecular and atomic level. The nature and structure of self-assembled submonolayers and monolayers at the interface of minerals were studied by infrared reflection spectroscopy. The external reflection spectra of the adsorbed monolayers on any type of minerals: transparent, opaque or non-transparent, recorded at different angles of incidence and for two polarizations are an excellent source of information about the nature and surface distribution of the adsorbed species. The developed method allows to obtain detailed information at a molecular level about the adsorbed surface species. By combination of the simulated and experimental data, the qualitative description of the adsorbed species as well as quantitative evaluation of orientation and the thickness of the adsorption layers were obtained. This fundamental knowledge allows to determine the mechanisms of surface phenomena which govern selective separations. Examples of different surfactant - mineral systems and industrial applications will be discussed.

Jan 1, 2000

By J. A. Finch, D. Lin

The robustness of the large-sections correction procedure, Hill's fast approximation, Barbery's correction and the PARGEN correction was examined by comparing their ability to reconstruct the true liberation distribution using sectioning data from computer-generated spheres. The results indicate that the flexibility of a correction procedure is related to the assumptions it makes about the continuity of the liberation distribution, locked-particle characteristics and ore texture. Overall, the large-sections procedure appeared to be the most generally applicable. The Hill fast approximation performed well, but this was probably because it partially incorporates the sphere model; the performance of the PARGEN and Barbery corrections varied from case to case.

Dec 1, 1995

By Alfred L. Ransome

The consumption of slab zinc in the United States increased sevenfold in less than a half century since 1900. Therein is reflected the innate characteristics of this versatile and nearly indispensable nonferrous metal whose use has grown at more than twice the rate of industrial production. The total metal consumption was substantially stimulated during the two World War periods, which were likewise marked by notable changes in use pattern accompanied by shifts in geographic distribution. This information circular summarizes basic data collected for many years by the Bureau of Mines, but in particular presents for the 1940-45 period details derived from the comprehensive slab zinc consumption survey inaugurated in 1940. The total consumption of slab zinc has been broken down into four major categories galvanizing, brass products, rolled zinc, and zinc-base alloys -- with minor applications grouped under a fifth heading, other uses. Ex- cept for the inclusion of zinc-base alloys with other uses before 1926, the above-named segregation has been shown for the entire period 1900-45. 11- though a substantial tonnage was taken by all groups in all years, there were large shifts in the use pattern in both World War periods. In both, the Allied Powers depended heavily on the United States for zinc-bearing products, especially those required by war industrius. The departures from usual uses were, however, much more marked during the second than in the first period, mainly because the United States could not have met the tro- mendously expanded war-materiel demands had the greater slab zinc needs of a period of high industrial activity been supplied. The geography of consumption is known in detail only for 1940-45. Even in that short period, substantial shifts are observable, largely the reaction from conversion to war production in 1940-41 and reconversion to peacetime consumption in 1945. However, there is so evidence of other shifts in consumption centers that appear to reflect longer-term develop- ments.

Feb 1, 1948

By A. C. Johnson

This circular is one of a series published by the Bureau of Mines describing mining and beneficiation methods and costs at various mining operations throughout the United States. Inclusion of the Abbott mine in this series is of particular interest, as the complex geology and the character of the deposits make their exploitation a unique operation. The mine operates on a high-cost, comparatively small-scale basis, and only the persistence of an aggressive management has enabled it to maintain its rank among the major mercury producers of California. Rising costs and decreasing metal prices, which continuously threaten the low profit margin, are reflected in increased efficiency of operation. This report summarizes past operations and describes, in detail, the geology and ore deposits; exploration and mining methods; and furnacing and condensing operations. It covers the entire operation from initial exploration to the actual production of mercury. Comparative production costs for 1944 and 1958 are of special interest.

Jan 1, 1962

"Mineral separation by exploiting the differences in mineral or metal specific gravities (sg) has been used since antiquity. In the modern era, this is most commonly seen in the recovery of gold by the use of centrifugal concentrators and the separation of coal (low sg) from waste rock (high sg) using heavy media cyclones and jigs. Other metals, notably oxides of tin and tungsten, are successfully recovered using some combination of jigs, spirals and shaking tables. However, many conventional gravity separation systems are limited to fairly coarse (>1 mm) to medium (>100 micron) particle separations due to the limitations of the gravitational separation forces in conventional equipment.Many of the high specific gravity minerals of interest are friable (e.g. cassiterite, wolframite, etc.) and excessive fines are generated in the grinding/comminution circuits which cannot be recovered with conventional equipment and may be lost directly to the tailings stream. Recent developments in centrifugal gravity separation equipment specifically designed for fine or ultra-fine particle separation and recovery have resulted in heavy mineral particle recoveries as fine as 10-20 microns. Ongoing research work has also identified the benefit of closed-circuit, multi-stage gravity recovery circuits using some combination of centrifugal concentrators and conventional equipment (tables, spirals, flotation, etc.) which can substantially increase overall plant recovery and final concentrate grade.This paper will provide details of the evolution of non-fluidized bed gravity concentrators for high sg mineral recoveries, correlate laboratory scale development work with plant results to confirm scale-up, and show how recent flowsheet developments have contributed to significantly improved plant performance.IntroductionGravity concentration is one of the oldest and most cost effective metal and/or mineral recovery systems, ranging from the classic hand panning of alluvial gold, through to the large scale production of a wide range of metals and minerals, including gold, silver, PGMs, black sands, coal and iron oxides. Conventional gravity recovery systems, comprised of some combination of sluices, spirals, jigs and shaking tables have limited application in fine particle (i.e. <100 microns) recovery, or where there are limited differences in particle specific gravities (sg), e.g. the separation of high sg, high value metal oxides (e.g. those of tin, tantalum or tungsten), from medium sg, lower value metal sulfides such as pyrite and pyrrhotite. These unit operations tend to have limited capacity, and while double and triple turn spirals and multi-deck tables have been developed, extensive floor space is often required in order to process the tonnages incorporated in the modern mineral processing plant."

Jan 1, 2017

By Erle C. Donaldson

A study of subsurface waste disposal in the United States shows that in eight States a wide variety of industrial wastes are being injected into formations ranging in age from Precambrian to Recent. More than 30 wells ranging in depth from 300 to 12,000 feet are used for waste disposal into subsurface formations which include unconsolidated sand, sandstone, vugular limestone, and fractured gneiss.

Jan 1, 1964

By Erle C. Donaldson

A study of subsurface waste disposal in the United States shows that in eight States a wide variety of industrial wastes are being injected into formations ranging in age from Precambrian to Recent. More than 30 wells ranging in depth from 300 to 12,000 feet are used for waste disposal into subsurface formations which include unconsolidated sand, sandstone, vugular limestone, and fractured gneiss.

Jan 1, 1964

By C. -G. Zhang

This paper presents the results of a study on cellular acclimation of Acidithiobacillus ferrooxidans to sulfur biooxidation in terms of cells growth and changes in surface properties and morphologies of both cells and sulfur particles. The results showed that A. ferrooxidans cells were grown faster and demonstrated higher concentration in the soluble thiosulfate substrate than in nonsoluble hydrophobic S0 substrate. The results showed that A. ferrooxidans cells acclimated to the sulfur biooxidation by actively expressing some extracellular polymers substance and maybe some outer membrane proteins that modified the surface properties of both sulfur particles and the cells themselves. In addition, the results showed that the A. ferrooxidans cells were able to dynamically adsorb to or desorb from the surface of sulfur particles. The cells aggregating onto the S0 surface enhanced the use of S0 substrate by the bacteria cells. This mode may be one of the most important characteristics for the better growth and propagation of the cells in solid sulfur-containing media.

Jan 1, 2009

By Peter L. Sheehan, David A. Fawcett, Dennis C. Martin

"Smoky River Coal Limited has successfully completed a major program involving the pattern rock anchoring of a high, steeply dipping footwall slope. The slope dips at approximately 65 to 70 degrees to the north, is benched for the upper 200 feet, is supported with rock anchors for another 240feet, and is unsupported at the pit bottom. In addition to the height and steepness, several structural features including shears, rolls and stratigraphic pinch- outs complicate footwall stability.This paper presents an overview of the project with descriptions of the engineering geology and footwall design, anchor installation, instrumentation and monitoring and a cost summary.IntroductionSmoky River Coal&apos;s mines are located in the foothills of the Rocky Mountains near Grande Cache, Alberta, approximately 200 miles west of Edmonton. The Smoky River coal leases were initially developed in the late 1960s and, except for minor shutdowns, have been in continuous operation since 1969 producing a low volatile metallurgical coal, mainly for the export market. Initial coal production was from underground mines; sur face mining started in 1971, and a large surface mine, No.9 Mine, was opened in 1974. Since that time, a number of open pits have been mined within the No.9 Mine area. Surface mining is by conventional shovel-truck method s with the use of a backhoe for mining the narrow pit bottoms.Coal recovery is mainly from the No.4 seam, which has a typical unstructured thickness of 20 feet. The most attractive opportunities for open-pit mining exist in areas of over thickening of the coal seam in the hinge zones of synclines and anticlines and in dip-slope situations. The mining of the more structurally complex pits and steeply-dipping footwall slopes requires that consideration be given to footwall stability."

Jan 1, 1988

By Aidan Giblett

"It is important to make a clear distinction on the scope of work of the Global Mining Standards and Guidelines (GMSG) guideline for sampling grinding circuits. Many mineral processing practitioners are familiar with the sampling and surveying of comminution circuits, in particular grinding circuits, for performance diagnosis and the identification of optimization potential. These surveys often provide information for population balance modelling of individual comminution and classification unit processes, and consequently require a large amount of information to calibrate and validate the unit models. As a result, these surveys are labour intensive, somewhat expensive, depending on internal capabilities of the mine site or company and have a long time span from initial planning to final reporting. They also require a high level of expertise to process the survey data, simulate the circuit and make sensible recommendations on follow up actions.As a result of these factors, full grinding circuit surveys are not a common occurrence at a large number of processing facilities, and several years may pass before follow up surveys are conducted. In the ensuing gap between surveys, the efficiency of the grinding circuit must often be taken on faith, and this is considered an unacceptable lapse in an environment of strained natural resources and low commodity prices.To support the rapid and productive energy efficiency analysis being promoted by the ICE working group, a much simplified survey and analysis process is required. The process reflected in the GMSG guideline is indeed more conducive to frequent analysis, at a skill level that is well within the capabilities of the average plant metallurgist. As a result, it becomes feasible to conduct mini-surveys of plant performance, which can be used to quickly and precisely diagnose the high level impact of process changes. These methods can also be manipulated by an experienced practitioner to provide sufficient information for modelling of the circuit to estimate the impact of process changes, allowing an initial rate and rank exercise to focus plant optimization efforts."

Jan 1, 2015

By A. C. Johnson

This report describes exploration, development, and exploitation methods, and summarizes costs at the Stormy Day mine, which was discovered in 1941. Several shipments of tungsten ore were made in 1944 to the Metals Reserve Company, Salt Lake City, Utah. The purchase of tungsten by the Federal Government, which began in 1951, stimulated interest in tungsten, and a successful program of exploration with participation of the Defense Minerals Exploration Administration (DMEA) indicated enough ore to warrant development of the property. Development work comprised drifting, crosscutting, and raising. Shrinkage stoping was used for mining the ore. Operations were suspended in October 1956, when the Federal Government terminated its purchase program. Total production of the mine was approximately 20,000 tons of tungsten ore. INTRODUCTION This information circular is one of a series, prepared in cooperation with various mining companies and published by the Bureau of Mines, relating to methods and costs of equipping and developing mining properties in the United States.

Jan 1, 1958

By Bobby Dupree

I remember a big problem with a seismograph in the winter two years ago. In response to a citizen’s complaint I placed a transducer near the corner of a two-story home. It was a pretty nice day for the winter months, the people were pleasant, and I had no problems digging a hole to place the transducer.

Jan 1, 2004

By Tano Balbin, Valery Astakhov, Juha Timperi, Lauri Koresaar

"Online elemental analysis is the basis of optimal flotation control in mineral concentrator plants. Traditionally XRF analyzers have been used as the online analysis method. However, online XRF analyzers struggle to measure elements below calcium in atomic number (Z=20). For many processes lighter element assays would be beneficial to improve control of grade and recovery. Processes where elements below Ca are required include P, Mg and Si in phosphate concentrators, Si, Mg and Al in iron concentrators, and S and C in gold concentrators. Laser-Induced Breakdown Spectroscopy (LIBS) based elemental analysis can readily be applied to these processes. LIBS is based on generating plasma in the slurry sample by a high energy laser and analysis of the plasma by optical emission spectroscopy. Capabilities of a new Courier® 8 analyzer based in LIBS technology are demonstrated for elemental analysis starting from lithium (Z=3). Results of a plant installation in a sulfide gold concentrator provide a good agreement with the analyzer and laboratory assays.IntroductionEffective process control can be regarded as one of the fastest paying investments for a mineral processing plant. Process optimization in flotation circuits requires constant feedback of the process state. If only manual laboratory samples are available, this optimization becomes difficult due to the long delay between taking the sample and acquiring the laboratory result. If the element grades are available in online basis, the operator or automatic process control system can make corrective actions in real time.Online X-Ray Fluorescence (XRF) analyzers have been in use at concentrators for decades. The XRF analyzers can provide a fast, accurate and precise analysis from slurry streams. However, the drawback of XRF analyzers is their lack of capability to measure elements below Ca (Z=20) in atomic number. The low energy X-rays of the low atomic number elements get absorbed by water in the sample, protective window of the analyzer, or air between the sample and spectrometer."

Jan 1, 2017

Delhi Australian Petroleum Ltd., acting as operator for the joint interests of Delhi and Santos Ltd., has been engaged in petroleum exploration in the western Great Artesian Basin since 1958.Extensive airborne magnetometer, gravity meter, reflection and refraction seisomograph, and surface geological surveys have been carried out. Results of the surveys have considerably altered the concepts of the geology of the area.Seven exploratory wells have been drilled in the area. Results of the drilling have established the presence in the subsurface of previously unknown Paleozoic sediments which are capable of generating hydrocarbons.Production of oil or gas has not been achieved, but each phase of the exploration programme has resulted in progressively establishing the basic conditions necessary for the discovery of commercially profitable accumulations.INTRODUCTIONDelhi Australian Petroleum Ltd. commenced operations in Australia in 1958. They have subsequently been engaged in systematic exploration for oil and gas, acting as operator for their partner, Santos Limited. The methods and techniques employed are those used throughout the petroleum industry. The results of the exploration programme contribute to a better understanding of the basic geology, and concomitantly a firmer analysis of the petroleum producing potential, of the western Great Artesian Basin.Each phase has progressively enhanced the gross geological interpretation of the area with regard to favourable conditions for the generation and accumulation of hydrocarbons, but the stage has not been reached where productive potential is definitely established.Exploration status in 1958Basin configurationIn 1958 knowledge of the pre-Jurassic stratigraphy of the geographically defined western Great Artesian Basin...

Jan 1, 1964

By G. Cordingley, A. Mwanza

Lumwana is an open pit Copper mine located in the Northwestern Province of Zambia approximately 80 km west from the provincial capital of Solwezi, approximately 300 km northwest from the Copperbelt and 700 km northwest from the national capital of Lusaka. The mine has two major Copper deposits: Malundwe and Chimiwungo. Copper mineralization includes Chalcopyrite, Bornite and Chalcocite. In addition to Copper, these deposits also contain the undesirable element Uranium contained in vein hosted and disseminated Uranite. The processing plant was designed using conventional technologies: semi-autogenous grinding (SAG) and ball mill for grinding, and mechanical cells for rougher and cleaner flotation. Soon after commissioning in early 2009, it was recognised that two stages of conventional cleaning were unable to produce plant final Copper concentrates with the desired Uranium grades. Studies have shown that a significant quantity of liberated and fine Uranium particles (up to 80-90%) is recovered with the concentrate by entrainment. Lumwana Operations sought the use of the Jameson Cell technology after observing successful implementation at other sites in rectifying similar issues. In late 2009, Jameson Cell pilot-plant test work was conducted at the site and this quickly led to the installation of a full-scale B5400/18 model into the existing cleaner circuit. Inclusion of the Jameson Cell resulted in the plant being able to effectively produce clean and saleable concentrate with Uranium contents consistently below acceptable levels. Initially designed to be used as a cleaner scalper cell at the head of the existing conventional cell circuit, subsequent operational issues with the existing recleaner cells forced reconfiguration of the cleaner circuit and reintroduced the Jameson Cell for the recleaning duty. This paper reports the Lumwana Operation from the first two years of operation where it struggled to produce a saleable concentrate with Uranium grades below 150 ppm, which is the maximum allowable limit set out in the smelting contracts, to steps taken in the subsequent years to implement a satisfactory solution. The plant can now consistently produce a clean Copper concentrate with Uranium grades well below 130 ppm and the overall improvements implemented at site have seen the overall plant recovery improve by 1.3%.

Jan 1, 2014

By R. Boom, L. Holappa

In the present paper, microstructure changes of solid-state reduction of industrial chromite pellets and lumpy ore were investigated with SEM/EPMA. To simulate the reactions in the packed bed zone of the Submerged Arc Furnace (SAF), carbon monoxide was used as the reducing agent, with the presence of graphite in proximity to chromite. The experiments were carried out at 1500 °C. Scanning electron microscopy was used to observe and analyse the structure and composition changes of the chromite samples. It was found that reduction of lumpy ore generally took place slower than that of pellet. In all samples, chromite reduction proceeded faster in the outer part of the sample than in the centre part. The reaction mechanism is discussed on the basis of experimental results and earlier investigations. The possibilities to optimize the FeCr production process are also discussed.

Jan 1, 2007

By D. F. Lascelles

D. F. Lascelles (School of Earth Sciences, MacQuarie University, North Ryde, N. S. W., Australia)- The paper contains many misconceptions commonly held by both geologists and soil scientists with regard to soil processes. The analogy between supergene copper enrichment and "nickel laterite" deposits is quite apt and the use of nomenclature from the former in describing supergene nickel deposits is justified. However, care must be exercised with regard to the notable differences in

Jan 1, 1974