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The use of controlled recirculation can be dated back to the early 1930s. Although this method has been applied in many mines since then, a generalized comprehensive network analysis is still lacking. This paper presents a unique approach in which the ventilation network with a controlled district recirculation is divided into two subsystems: a main subsystem and a recirculation subsystem. The subsystems are analyzed individually and the results and their relationships are then integrated into discussions of the total ventilation system. The analysis of the recirculation subsystem is facilitated by introducing a non-dimensional parameter A, which represents the ratio of the air quantity for the working face to that for the subsystem. As a result, fan and regulator pressures and air power for various recirculation arrangements can be effectively expressed as a function of A and the subsystem air quantity. Numerical examples are included.

Jan 1, 1995

By Mingfei He, Jianhua Chen, Yingchao Liu, Yuqiong Li

Pyrite is one of the most common sulfide minerals on earth, which is usually grown with chalcopyrite and other sulfide minerals. In flotation practice, pyrite from different mines or different sections in a same mine may have different flotation behaviors. This is because the pyrite crystal contains lattice defect, including ionic vacancy and lattice impurity. The present work investigates the effects of three typical 3d transition metal (Co, Ni, and Fe) on the adsorption of CH3OCS2 −, OH−, and CN− on pyrite surface by density functional theory (DFT) calculations. Calculated results show that Co impurity reduces the adsorption energies of CH3OCS2 − and CN− on the surface of pyrite, while Ni and Cu impurities significantly increase the adsorption energies of CH3OCS2 − and CN− on the surface of pyrite. Co impurity has small influence on the adsorption of OH−, but Ni and Cu impurities significantly increase the adsorption energies. Calculations on Mulliken charge population of Co2+, Ni2+, and Cu2+ indicate that the Mulliken charges of Co2+, Ni2+, and Cu2+ after OH− adsorption are more than those after CN− adsorption. This suggests that the ionic property of the M-OH- coordination bond is greater than that of M-CN- coordination bond, while covalent bonding of M-CN- coordination bond is greater than that of M-OH- coordination bond. The adsorption results are discussed based on coordination field theory (CFT).

Oct 6, 2020

By D. J. Beeby

California's Surface Mining and Reclamation Act (SMARA) was passed in 1975 to identify and protect mineral resources in areas of high land-use conflict and ensure reclamation of mined lands. Under SMARA, aggregate resource availability is quantified and compared to forecasted demand in specific market regions. Fifteen regions studied thus far cover 20,000 square miles and contain 50 billion tons of high-quality aggregate resources which have been legally designated as ?regionally significant?, providing a measure of protection previously unavailable. SMARA reports and State testimony at local hearings have supplied objective information and helped reduce conflict in mine-permitting decisions.

Jan 1, 1987

By Shirley Mason, L.G. Huntley

The predominant sedimentary formations in Colombia are those of Tertiary age. They form the floor of the Magdalena Rivcr valley and the coastal plain that borders the Caribbean Sea: this is also true of the southern part of the narrow coastal belt of the Pacific coast.

Jan 1, 1923

By Shirley Mason, L. G. Huntley

The predominant sedimentary formations in Colombia are those of Tertiary age. They form the floor of the Magdalena Rivcr valley and the coastal plain that borders the Caribbean Sea: this is also true of the southern part of the narrow coastal belt of the Pacific coast.

Jan 1, 1923

By Silvana Costa

The quality of life in remote mining communities is a significant factor that impacts the mining industry?s ability to attract and retain high quality workers in remote areas. The rapid growth of mining development, along with the shortage of skills and training globally are reflected in an increasing need to identify the ideal conditions for employee wellbeing and investigate ways to improve quality of life of miners and their families in remote locations.

May 1, 2007

By Vladimir Adamek

This paper describes the Bureau of Mines development of a novel subsidence prediction methodology suitable to the mining and geologic conditions in the Northern Appalachian Coal Region. It describes the computation of vertical and horizontal movements, inclination, curvature, and horizontal strains. The substance of this method is the separation of the effects of lithology by introducing a correlation between hypothetically homogeneous overburden and existing lithologic conditions, while providing for different mining conditions, i.e., underground geometry and overburden thickness. The effects of lithology have been expressed in the form of a variable subsidence coefficient within the subsidence trough. The subsidence co-efficient is considered a constant for other predictive methods. Field data from 16 test sites at 11 Bureau longwall panel studies were used in the analysis. For each panel, the characteristics of the variability of the subsidence coefficient were defined. Regression analysis of the subsidence coefficients from all test sites on their locations relative to the edges of their respective panels yielded a third-degree polynomial equation. The results from additional longwall panel studies, not included in the regression analysis, were used to prove the validity of this method. To facilitate the use of this precalculatlon methodology, a computer program was written in BASIC for use on a personal computer.

Jan 1, 1987

By Donald W. Scott

Chemical thermodynamic properties for the ideal gas state from 0 to 1500 K are tabulated for all of the alkane hydrocarbons through C10. These properties are based on correlations of the extant data for the entropy, vapor heat capacity, and enthalpy of formation of individual alkanes and the equilibrium constants of alkane isomerization reactions.

Jan 1, 1974

By Peter W. Lipman

Structural and topographic relief in the Sangre de Cristo Mountains of northern New Mexico provides a remarkable cross section through the recently recognized 23-26 m.y.-old Questa caldera and cogenetic volcanic and plutonic rocks. Although largely eroded, remnants of an ash-flow sheet of silicic-alkalic rhyolite and associated more mafic lavas of the Latir volcanic field are preserved as far as 45 km beyond the source caldera. Within the caldera, the tuff ponded to a thickness of 2-3 km and enclosed chaotic megabreccia fragments which slumped from the caldera walls. At the time of ash-flow eruption, the volcanic field was severely deformed along northwest-trending faults related to the Miocene Rio Grande rift, with most intense deformation occurring within the caldera. Strata were steeply tilted and locally overturned along presumably listric faults. Ash- flow tuffs locally underwent secondary flowage over concurrently developing fault scarps and accumulated within structural basins as rheoignimbritic lava flows. Cogenetic batholithic granitic rocks, exposed over an area of 20 x 35 km, range from mesozonal quartz monzonite to epizonal porphyritic granite and aplite, with the shallower and more silicic phases most abundant within the caldera. Compositionally and texturally distinct granitic phases define a highly evolved resurgent intrusion within the caldera, an incomplete ring dike along its southern margin, and a large mass of less fractionated quartz monzonite south of the caldera. A negative Bouguer gravity anomaly is closely confined to the area of ex- posed granitic rocks; it also reflects boundaries of the Questa caldera. The gravity anomaly is interpreted as defining the extent of the underlying batholith, emplaced into lower parts of the volcanic sequence and underlying Precambrian rocks. Paleomagnetic determinations indicate that the granitic rocks were above Curie temperatures at the time of caldera formation and regional listric faulting, yet most are little different in radiometric age from the intensely deformed volcanic rocks. These relations indicate that the batholithic complex represents the source magma body for the volcanic rocks, into which the Questa caldera collapsed, and was largely liquid at the time of regional tectonic disruption. Compositions of the volcanic and plutonic phases changed from early calc-alkaline metaluminous rocks, to weakly peralkaline silicic rhyolite and equivalent afredsonite-acmite granite at the time of the caldera formation, then back to post- caldera calc-riebeckite granitic rocks. Maximum concentrations of alkalis and minor elements such as Rb, Th, U, Nb, Zr, and Y were reached at the time the caldera formed about 25-26 m.y. ago, but the major molybdenum mineralization of the Questa district took place when the late calc-alkaline granitic ring intrusions were emplaced about 23 m.y. ago, along the south margin of the caldera.

Jan 1, 2013

By H. H. Murray

New and improved benefication techniques are available to allow the production of clay minerals of exceptionally high purity. This is particularly true for kaolins and smectites. Wet processing techniques including particle size separation, high intensity magnetic separation, chemical leaching, flotation, and selective flocculation are described and results and applications are discussed. The blending of clay minerals with other minerals provide opportunites to make special ceramic materials such as cordierite and other minerals which have very special ceramic properties including low heat expansion, high fired strength, low absorption, and other desired qualities.

Jan 1, 1989

By G. W. Birge, D. E. Wolfson, J. G. Walters

Seventeen samples were carbonized by the BM -AGA pilot - plant test method and in industrial ovens . Chemical and physical properties of the samples were determined , and the physical properties of the cokes prepared by the two methods were compared . Since the capacity of the plants from which these samples were obtained is about 30 percent of the 1959 total for the United States , the data given in this report are indicative of the chemical and physical properties of blends used to produce industrial cokes and the acceptable chemical and physical properties of the resultant coke .

Jan 1, 1964

By Bahjat Khoshaba, Bern Klein, Haixing Yan, Libin Tong, Andrew Bamber

"When a conductive or magnetic particle was put into an electromagnetic field introduced by an electromagnetic sensor, the particle can influence the electromagnetic field which can be used to characterize this particle. The electromagnetic technology based on eddy current theory was explored to investigate its potential in both the separation of minerals and the pre-concentration of a base metal ore. Samples tested in the study included the minerals obtained from Ward’s Science and the low grade copper ore particles obtained from Mount Polley Mine. The effects of mineral type, sensor frequency, particle size, particle position on the sensor surface, and particle lift-off on the magnitude and phase of the electromagnetic spectra were investigated. The electromagnetic spectra of various minerals show that it is possible to separate chalcopyrite or magnetite from tested minerals, simply based on the magnitude of the spectra. The spectra of the ore particles were determined by the mineral in the particles with the strongest signal. The effect of the pre-concentration of the low grade copper ore is determined by the association of chalcopyrite with magnetite. Direct sorting is the mechanism in the separation of mineral particles, while indirect sorting is the mechanism for low grade ores.INTRODUCTIONSensor-based sorting technologies include radiometric, X-ray transmission, X-ray fluorescence, near infrared, photometric, inductive, microwave heating and so on. Sorting not only discards barren rocks away from the concentrator but also recovers metal bearing that would be lose to the waste dump. The benefits of pre-concentration using sensor-based sorting are achieved on reduced energy consumption for comminution and reduced water usage on a volume per weight of metal basis (Bamber, 2008; Gunson, Klein, Veiga, & Dunbar, 2012; Kleine & Wotruba, 2010; Knapp, Neubert, Schropp, & Wotruba, 2014; Kobzev, 2014; Lessard, de Bakker, & McHugh, 2014; Mazhary & Klein, 2015; Robben, Wotruba, Robben, von Ketelhodt, & Kowalzcyk, 2013). Amongst others, high frequency electromagnetic sensors were developed for ore sorting at MineSense Technologies Ltd. and are subject of this paper. Improving the understanding of ore heterogeneity is the basis for developing a successful semi-bulk or bulk sorting systems by incorporating the sensors in the material handling equipment (MineSense Technologies Ltd., 2016). The present study focuses on the bulk sorting potential and bulk sorting mechanisms of the electromagnetic technology in the pre-concentration of minerals or ores."

Jan 1, 2016

By S. Janisko

Studies have linked long-term inhalation of diesel exhaust with adverse health effects such as cardiovascular disease, cardiopulmonary disease, and lung cancer. Diesel exhaust levels in underground mines can approach 100 times the environmental level and are therefore monitored closely in the mining industry. Elemental carbon (EC) (a product of diesel combustion commonly referred to as ?soot?) has proven to be a good indicator of diesel exhaust levels. The current procedure for measuring EC levels involves taking personal samples from a mine worker?s breathing zone and/or stationary samples in various parts of the mine and subsequently sending these samples to a lab for analysis by NIOSH 5040 method. Unfortunately, the whole process can take up to several weeks to complete. To address the problem of waiting weeks for results, NIOSH?s Pittsburgh Research Laboratory is developing a portable device for measuring levels of elemental carbon. This optical device takes a continuous sample of air in the surrounding environment and measures the absorbance of light passing through a filter that collects diesel exhaust particulates within the instrument. This technology can provide a near real time measurement of EC with accuracy within 10% error. The ability to take near real time measurements, combined with the instrument?s portability (currently small enough to be worn on a miner?s belt), makes this device extremely useful in the mining industry.

Jan 1, 2009

By R A. M Maddever, P Jeanneau, V Flahaut

Over the entire life cycle of a mine, from early resource evaluation to the blasting of benches, the collection of geochemical data is crucial for the site operator, who must routinely and intensively drill and sample the orebody. This produces huge numbers of physical samples, in turn requiring significant cost and time for their preparation and assay. Moreover, despite best efforts, the sample recovery process is prone to error, which limits the quality of data.The pulsed neutron gamma technique has been used for decades in various industries, in particular oil logging, for its ability to provide direct identification and quantification of elemental concentrations. However, its implementation in logging tools for the mining sector is relatively recent. Built around the latest in technology for optimal spectrometric measurement, a commercial tool referred to as FastGrade™ 100 has been available for a few years and used with increasing success in the mining environment, specifically the iron ore industry, resulting in a reduction in the amount of collected samples. Relying on the physics of neutrons and gamma photons, both of which are particles that penetrate the surrounding bedrock through several tens of centimetres, such spectroscopy tools measure in real-time the composition of a much larger volume than the delimited volume of the drilled material traditionally used for geochemical mapping. Better statistics and reliability of the estimated composition increase the ability to properly and quickly measure drilled holes and allow the substituting of all or part of the sampling and assaying efforts by geochemical log data. Our paper focuses on this technology, known as pulsed fast and thermal neutron analysis (PFTNA). It reviews the main drivers for the design of such a logging tool and discusses how the fundamental characteristics of the technology, in terms of neutrons and gamma interactions, translate into interpretation of the analytical output.CITATION:Jeanneau, P, Flahaut, V and Maddever, R A M, 2017. Iron ore benefits from neutron pulsed geochemical tools, in Proceedings Iron Ore 2017, pp 387–396 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

The Morning Star diorite dyke has been subjected to two periods of mineralization. The earlier, genetically related to the dyke magma, gave rise to a weak chalcopyrite-pyrrhotite-pentlandite-gold mineralization in a narrow zone, up to 25 cm. wide, which parallelsthe nearby western (hanging) wall of the dyke. Subsequently a set of conjugate shears formed in the dyke as a result of tectonic movements. Gold-quartz veins formed in these shears giving rise to the classical "ladder veins" of the Morning Star mine. On either side of the veins ("floors") the diorite has been bleached for up to 3 ft. This involved introduction of much CO. and some K"O, and S with abstraction of SiO. and FeO, giving rise to carbonates, sericite, zoisite and pyrite. The veins consist of quartz with minor amounts of albite and carbonate, together with pyrite, arsenopyrite, pyrrhotite, chalcopyrite, sphalerite, tetrahedrite, galena, bournonite, boulangerite and gold. Spectrographic analyses of gold show that the suite of trace elements is consistent throughout the mine.INTRODUCTIONThe gold-quartz veins of the Morning Star Gold Mine, at Wood's Point, Victoria, are a classic example of the "ladder vein" type of deposit. The structure of this series of repeating quartz veins or "floors", some barren and some productive, occurring in a set of conjugate shears which transect a "dyke bulge" of diorite (Fig. 1), has been described on numerous occasions as mining has progressed and figures in the textbooks (Whitelaw, 1905; 1916; Junner, 1920; Lindgren, 1933; McKinstry, 1935; 1942; 1949; Kenny, 1949; Hills, 1952; Clappison, 1953) ; but there has been no study of the mineralization apart from that in Junner's (1920) general study of the Walhalla-Wood's Point Goldfield, made at a time when mining had not developed below the 400 ft. level,. and the mine was dormant.

Jan 1, 1958

In flotation, particulate materials are separated by controlling the hydrophobicity of the particles using appropriate collectors. In this regard, contact angle (?) is the most important process variable. However, the flotation models used in industry today do not include ? as a parameter. As result, flotation circuits are designed based on the first-order flotation rate constants (k) determined from laboratory experiments. A problem with this approach is that laboratory experiments usually give substantially higher k values than achievable in full-scale operations, which makes it difficult to use the model for plant design. In the present work, we have developed a model from first principles using both surface chemistry and hydrodynamic parameters, such as ?, ?-potentials, surface tension (?), particle size, energy dissipation rate, etc. The basic approach is similar to the one developed previously for bubble-particle interactions under laminar flow conditions (Yoon and Mao, J. Colloid and Interface Science, 181, 61, 1996) except that the model parameters have been modified by considering the turbulence in a flotation cell. In addition, the model describes the recovery processes in froth phase, including bubble-coarsening due to coalescence. Based on this model, we have developed a computer simulator (FlotSim) that can be used to design flotation circuits from the mineralogical (or liberation) data on the feed and the hydrodynamic characteristics of a flotation machine. Since the model is dynamic, it can also be used for process control. Further, the simulator has predictive capacity as it is based on a first-principles model. The model-based simulator has been validated in a carefully controlled bench-scale flotation experiments. Keywords: flotation kinetics, flotation model, contact angle,?-potential, size-by-size recovery, liberation, DLVO theory

Sep 1, 2012

By L. J. Cunningham

Introduction The property of Rouyn Merger Gold Mines, Limited, is in Rouyn and Joannès townships, Western Quebec, seven miles east of the town of Rouyn. Traversing it is the east-west trending Cadillac-Bouzan fault. Diamond drilling in 1944 and 1945 along a shear zone south of the fault indicated an ore deposit lying at the contact between sedimentary and volcanic rocks and dipping approximately 60° to the northwest. In the summer of 1945 it was decided to sink a shaft to investigate the indicated ore zone. In the immediate vicinity of the deposit, bed-rock is overlain by clay beds, in some places as much as 70 feet thick. Consequently, possible shaft sites were limited to those locations where overburden would not be excessive. The most favourable site was about 125 feet to the south of the ore zone as projected vertically from bed-rock to the surface. Accordingly, it was decided to sink the shaft at this point, with an inclination of 60° N. W., paralleling the dip of the ore zone.

Jan 1, 1948

By Steven A. Savage

Agrico Chemical Company, as we presently know it, is the result of the coming together of several different fertilizer operations. The Williams Companies, our parent organization, first entered the fertilizer business in 1971, when it acquired the fertilizer operations of the Gulf Oil Company. This gave us, among other things, the manufacturing facility at Donaldsonville, Louisiana. In 1972, The Williams Companies acquired Agrico Chemical Company from Continental Oil Company, bringing in a manufacturing facility and phosphate mines at Pierce Florida. Our Florida Mines are in the region commonly known as the Bone Valley Region of Florida. The majority of the phosphate fertilizer produced in the United States utilizes rock mined in this region. The Donaldsonville Plant was originally built in 1967-68 on the site of the old Faustina Plantation at an approximate cost of $80,000,000. (This plant is commonly referred to as our Faustina Plant.) Until such time as Agrico was acquired from Continental Oil, the Donaldsonville Facility was solely used to upgrade phosphoric acid into finished granular products.

Jan 1, 1986

According to the Darcy?s law, filtration rate should increase with increasing pressure drop (?P) across a filter cake. In centrifugal filtration, ?P is created by the free water present on the surface of a filter cake. Thus, ?P can become negative when the free water disappears from the cake surface, which makes it difficult to achieve low cake moistures. In the present work, we have developed methods of overcoming this problem by either increasing the air pressure inside or applying vacuum outside a centrifuge. Laboratory dewatering tests conducted using these provisions showed that the moistures of various minerals and coal fines can be reduced to the level that can obviate the need for thermal drying. The new concept has been successfully tested both at pilot- and full-scale, which lead to commercial deployment through Decanter Machine, Inc., under the trade name Centribaric® centrifuge. Keywords: dewatering, hyperbaric centrifuge, pressure drop, Darcy?s law, Centribaric® centrifuge

Sep 1, 2012

By R. J. Gochin, P. Bevilacqua, G. D. Schena

This class of flowsheet-dependent simulators does not replace modular simulators, such as Modsim and Microsim, which are necessary for the assessment of different flowsheets before selection of the most desirable technical option and for investigation of the fine details of unit processes. The system presented here is regarded as complementary, serving in the early stages of feasibility studies as an aid to assessing the convenience and economics of preconcentration; the example used is of dense-medium preconcentration of a barytes-fluorite ore

Jun 13, 1905