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By H. E. Rudi

The advent of open nit mining permitted the development and processing of minerals never before thought possible. New equipment was needed; new techniques were devised; new methods were called for. This development and acquisition of new techniques, methods and equipment did not, however, stir the souls of our industry and educational leaders sufficiently to a recognition of the problem of people, especially the future development of the people needed in open-pit mining. The people problem has been and will be with us as long as there are two of them. The development of people will be required for the same reason. The problem of developing future personnel for open-pit mining is not what must be developed; that is known to all of us and can be briefly stated ashore and better of everything." As I see it, the real problem lies in determining (1) what personnel are really critical, (2) why are they critical and (3) how can we develop them.

Jan 1, 1965

By C. Iglesias

Innovation in the tilemaking ceramic industry is stressing properties like powder flowability, ability to toughen green tiles, so turning technological requirements of ball clays ever stricter in terms of plasticity, dispersion in water, rheological behavior, workability in the green state, refractoriness and firing colour. Technological performance of ball clays was improved by taking as benchmark the highest quality raw materials on the market. The mineralogy, plasticity, methylene blue index and ceramic response of the Patagonian ball clays are analogous to those of European clays, but improvement is needed to approach the highest quality materials. On this basis, the Frente A, Super, Puma, and Lote 8 deposits were selected and their characteristics enhanced by additions of highly plastic and white-firing corrective clays targeted on the benchmark. Porcelain stoneware formulations, containing improved ball clay mixes, were experimented at both laboratory and industrial scale. The improved ball clays behave like the best raw materials currently used, although modest changes occur in the mechanical properties, water absorption and whiteness of the fired products.

Jan 1, 2010

Passive seismic monitoring is a useful tool for measuring wave propagation in rock mass in deep underground mining. About 20000 mining ? induced seismic events of a hard rock mine, are identified and investigated. The travel times of source-receiver pairs allow us to demonstrate temporal change in velocity. It was found that the average P wave velocity is about 6000 m/s in the mining regions. Velocity investigations on the data during about three months around the main shocks show a significant decrease of the average seismic wave velocity after the main shocks. The sudden drop of average velocity change after the main shocks implies the creation of new fractures in the rock mass due to the main shocks. Afterward, the average velocity increased to a normal level after a time duration of several days. A reasonable explanation for the post seismic velocity increase is that opened cracks begin to close due to crack healing.

Feb 23, 2014

By E. Hsieh

Proximity detection in the open pit mine can be used effectively as an operator assist strategy which improves digging production through enforcement of best practices, although it is normally thought of first as a safety tool, and second as a step toward full automation when combined with object avoidance.

Feb 23, 2014

By O. J. Tassicker

The Electric Power Research Institute (EPRI) initiated a program in 1976 to develop and demonstrate an instrument system for on-line continuous measurement of coal properties. The program has focused on the use of Prompt Neutron Activation Analysis (PNAA) for elemental determinations and microwave absorption for moisture determination. One of the major results of the EPRI program is the development of the CONAC (Continuous On-Line Analysis of Coal) instrument, with Science Applications, Inc. (SAI) as the prime contractor and Kennedy Van Saun Corporation as a subcontractor.

Jan 1, 1983

By K. Fair

Using an agitated column 203 mm (8") diameter by 1829 mm (72") tall with independent agitation units for the gas dispersion zone and the collection zones, respectively, permitted the independent evaluation of the attachment and the detachment mechanisms for the chalcopyrite/ silica system. Three particle size fractions were used in this study, i.e. coarse (+75 µ m), intermediate (-75 µ m + 10 µ m) and fines (-10 µ m). The optimum selection of the two agitation zones for the three particle size fractions were determined as a function of grade, recovery, residence time and air superficial gas velocity.

Jan 1, 1990

By J. C. Judd

The U.S. Department of the Interior, Bureau of Mines investigated solvent extraction methods for recovering gallium from filtrates produced from sulfuric acid leaching of hydrometallurgical zinc residues. These filtrates typically had pH values of 0 to 0.5, too high an acid content for effective gallium recovery by traditional extractants. Of the nine extractants studied in batch tests, 0.3M octyl phenyl acid phosphate (OPAP) in a kerosene diluent was the most effective extractant for gallium recovery, extracting up to 99.9 pct of the gallium. This high extraction was possible when the iron in solution was maintained in the reduced ferrous state. Batch tests also showed that a 1.5M-H2SO4 strip liquor recovered 98 pct of the gallium from the loaded OPAP. A continuous solvent extraction system was designed and operated based on McCabe-Thiele analyses of equilibrium loading and stripping isotherms. When 12 L of leach filtrate containing 0.32 giL Ga and 20 giL Fe were pumped through the system in 32 hr, results showed that 95 pct of the gallium was extracted in four stages at an A:O ratio of 1:1. Stripping the loaded solvent with a 1.5M-H2S04 liquor recovered 94 pct of the gallium in four stages at an A:O ratio of 1:4. A two-stage, 50-pct-phosphoric acid strip successfully removed ferric iron from the OPAP, allowing high gallium extractions to be maintained.

Jan 1, 1990

By D. T. Jr. Tarr

History of Development The hydrocyclone, probably because of its basic simplicity, has been used for various classification applications since before 1890. A patent was granted in the United States in 1891 to Bretney on a device for separating sand from water, collecting the sand in a closed chamber for intermittent discharge, practically identical to some present-day water desanding cyclones. Between 1900 and 1937 there were 30 or more additional patents issued on liquid cyclone configurations or their use. About 1937 liquid cyclones began to be used commercially in the treatment of cellulose fiber in the pulp and paper industry separating contaminating particles from the fiber in water suspension used for making high grade paper products. Nichols Engineering & Research Corp. of New York was marketing a liquid cyclone for cleaning sand and din particles from fiber suspensions in the pulp and paper industry by 1937. The designs during this period were such that the cyclones discharged a small amount of relatively high density material into a chamber connected to the cyclone apex which in turn discharged the collected dirt material intermittently. By the early 1940s hydrocyclones as we know them today began to appear both in the pulp and paper industry and in coal prorzssing.18 Considerable experimental work was done on small, mostly 3-in.- diam, cyclones operating at relatively high pressure drops, in the range of 50 psi, to remove very small contaminating particles from cellulose fiber in the production of high-grade writing papers in the paper industry.18

Jan 1, 1985

By S. Park

In a flotation froth (and foam), air bubbles become larger due to coalescence, causing less hydrophobic particles to drop off. A bubble-coarsening model has been developed by calculating the changes in Plateau border area as a function of the initial bubble size at the base of a foam, liquid fraction, and foam height and then relating the predicted Plateau border area to the critical rupture thickness of lamellae film. The model predicts that bubble coarsens with increasing froth height, decreasing frother dosage, and decreasing aeration rate. The model predictions are in good agreement with actual bubble size measurements.

Feb 23, 2014

A major Brazilian iron ore producer, SA Minerayao da Trindade (Samitri), has recently completed modifications at two operations which involve the use of Derrick high frequency vibrating screens. Details of these modifications are presented, together with a review of product quality improvements.

Jan 1, 1997

By C. R. Tinsley

In maybe the world's first in a mine project financing, a US $55 million Rehabilitation Indemnity was given on behalf of the banks in a US $250 million loan to develop the Ranger uranium mine, Northern Territory, Australia. The basis of the financing was an estimate of removal of the tailings and replacement into the pit. The Indemnity was amortized by a sinking fund from the mine's revenues. Such a concept could be valuable for mineral developments in sensitive areas or jurisdictions such as British Columbia or Alaska.

Jan 1, 1992

By B. Sameti

Blast engineers have been taking advantage of image-based rock fragmentation analysis methods for the past 3 decades to estimate rock size distributions. These methods utilize a wide range of image segmentation techniques, from manual to fully-automated, to delineate the edges of rocks in images. Rock delineation results are then converted to physical rock sizes (and percentage passing curves) by scaling the image pixels to correspond to physical measurements. The size scaling process is critical for acquiring physical measurements, but specific to the limitations of different applications. This article starts by presenting a shovel bucket-based fragmentation analysis system, where scaling is done using the known width of the shovel bucket within the image. Next, it describes methods that use pictures captured by digital cameras with scaling reference objects in the view. Finally, the article presents a method that uses three-dimensional imaging to capture images without the need for scaling reference objects. A portable device which utilizes a three-dimensional imaging method is proposed, and compared with the other methods. The proposed solution combines the generated three-dimensional points with the delineated rock boundaries in the image to reconstruct the surface, and generate accurate rock size estimates and percentage passing rock size distributions. System operation is described and its accuracy and performance are discussed for various scenarios. It is shown that since the device does not require a physical object for scaling reference, it is free from the limitations of other methods, and can be applied for automatic rock size measurement from various sources such as mining shovels, loaders, crushers, stockpiles, haul truck beds, and conveyor belts.

Feb 23, 2014

By Yang Song, Li Shaokang, Wang Zhiqiang, Wang Jinjun, Li Guofeng, Su Meixuan

The paper investigates the triboelectric charging properties of calcium carbonate (CaCO3) particles under different conditions using a cyclone tribocharger. It explores the effects of airflow velocity, tribocharge material, and particle moving distance on the charge-to-mass ratio of CaCO3 particles. The study aims to provide guidance for the design of triboelectric separation systems for magnesite.

Sep 1, 2023

By Mohammed Laraba, Rodrigo Alvarez Garcia, Juan Maria Menendez-Aguado, Roula Abdelmalek

The aim of this research is the study of the WHIMS parameters on the improving process of a local (DD: Djebel Debbagh, East of Algeria) kaolin. The obtained results of performed XRF, SEM, and XRD characterization showed that this local material is an alumino-silicate containing kaolinite and halloysite with MnO and Fe2O3 impurities (respectively 39.30% and 34.67% alumina and 38.18% and 39.70% silica in both samples (DD2 and DD3). After homogenization, crushing, and milling, a multiparameters factorial experimentation (grain sizes, intensity, and dimension of matrix balls) showed that WHIMS is an effective process to improve the quality of this kaolin, mainly: removing their impurities. Dimensions of matrix balls (Db) = 2 cm, intensity of the applied magnetic field (I) = 1.5 T, and grain sizes (Dp) = > 100 < 250 μm) are the optimal values to reach 91.06% for manganese and 93.45% for iron as removing yield. The statistical analysis of these results sorted the investigation parameters and showed that Db has the highest and most significant influence on the recovery of iron and manganese particles. The magnetic field intensity (I) has a less important influence while the grain size has an average influence (positive on the iron recovery but a negative one on the recovery of manganese).

Jun 11, 2022

By John K. Hollmann

The use of the direct method of determining coal methane content has grown in the last decade from a research technique into a practical coal exploration tool. However, the literature available on the subject is somewhat lacking in site-specific guidance and observations on the conduct of the method and the use of the resulting data. This study discusses some practical lessons learned in conducting a large scale direct measurement project at an operating mine, describes the initia1 interpretations and uses of data from the project, and presents observations from subsequent mine operations into the success and limitations of using direct measurement data in mine planning. The site studied is in central Pennsylvania on the Appalachian Plateau and includes coal seams in the Allegheny series.

Jan 1, 1987

By Chester A. Rowland

La conminución de Ios minerales es, generalmente, una etapa de preparación de la alimentación para las subsiguientes etapas del proceso. La molienda, fase de conminución de productos finos, requiere una gran inversión de capital y frecuentemente es el área de máxima utilización de potencia y de materiales resistentes al desgaste. La molienda se produce normalmente en tambores rotativos que utilizan un medio de molienda que se pierde en la misma, al elevarse con la rotación del tambor, se rompe el mineral por combinación de los efectos de impacto, atrición y abrasión, hasta producir el producto especificado. El medio de molienda pueda ser: - El propio mineral (molienda autógena - primaria y secundaria). - Medio no metálico, natural o fabricado (pebbles) - Medio metálico (barras o bolas de acero) Este capítulo tratará de molinos de barras y bolas que utilicen medio metálico de molienda.

Jan 1, 1982

By K. L. Hanning

Grinding and classification circuits at Climax Molybdenum Co. are described. Since the installation of a direct digital control computer in 1974, a number of control strategies were developed and evaluated. This paper deals in particular with the practical experience and results obtained in direct digital control of a wet grinding circuit consisting of a ball mill, constant speed sump pump, and hydrocyclones. For this circuit throughput is maximized, while maintaining a desired product size. Product size is inferred from measurement of operating variables.

Jan 1, 1977

By S. T. Hall

The authors have previously described a method of enhancing the magnetic susceptibility of pyrite by a mild alkaline oxidative pressure leach (Hall et al, 1985). This finding was successfully applied to enhance the magnetic desulfurization of an Eastern Canadian coal (Hall and Finch, 1984). This paper reports on enhancement of the magnetic susceptibilities of iron-containing sulfides (arsenopyrite, chalcopyrite and marcasite) upon similar treatment. It also explores the application of this pretreatment in the magnetic separation of fine sulfides from oxides and other sulfide minerals. In the latter case galvanic interference effects have a serious impact on the potential use of this method.

Jan 1, 1985

By S. W. Nicholson, L. G. Woodruff, K. J. Schulz, W. E. Cannon

The 1.1 Ga Midcontinent rift of North America has many similarities to the geology of the Voisey&apos;s Bay region in Labrador and the geology of the Noril&apos;sk region in Siberia. These similarities include the hosting of large volumes of sulfur- undersaturated and trace-element-enriched basalt, having igneous centers characterized by crustal contamination, being characterized by metal depletions in some mafic units (an indication of prior sulfide segregation) and having known occurrences of Ni-Cu sulfide mineralization. These similarities along with new geophysical data and refined models for Ni-Cu sulfide deposits suggest that the Midcontinent rift probably contains undiscovered Cu-Ni [±] PGE sulfide deposits, some of which could be the size and grade of a Voisey&apos;s Bay or Noril&apos;sk deposit. In particular, intrusions and related feeder systems that occur in northern Michigan and Wisconsin, as well as to the southwest along the rift margin, deserve serious examination.

Jan 1, 1999

By R. R. Klimpel

The grinding of coal-water slurries has received increasing industrial attention during the last decade. In particular, there is long-term interest in the use of pulverized coal-water slurries to replace oil in combustion equipment and the development of coal gasification/liquefaction processes which require coal-water slurries as feed. More specifically, the use of coal-water slurries in gasification requires grinding a high density slurry containing the smallest amount of water consistent with slurry pumping and spraying. As part of a fundamental engineering research support program aimed at the industrial implementation of dense coal-water slurry grinding, this author has published several papers on how specific rates of breakage vary as a function of slurry rheology, Klimpel (1982, 1982/83). These papers demonstrated that there is a consistent pattern of change in specific rates of breakage of coal in dense slurries with controlled variations in slurry rheology. By matching rheological data with laboratory grinding results, it was possible to identify directly slurry conditions that correspond to: (1) slowing down of breakage rates, (2) the occasional acceleration of breakage of some sizes, and (3) conditions where chemical additives will increase rates of breakage.

Jan 1, 1990