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By M. W. Harmer

Laboratory test work, pilot plant testing and plant experience with wet, fine mesh screens is discussed. High frequency, low amplitude, fine mesh, wet screens were installed on the 6th cleaner concentrate stream. These screens produce a 60% oversize recovery split of the molybdenite concentrate that is of leached equivalent quality. The undersize stream is leached with 'hot ferric chloride to remove Pb and Cu contaminates before roasting or shipment to sulfide customers. This plant modification is a good example of using existing technology in an unconventional flow sheet to yield significant cost savings.

Jan 1, 1990

By J. W. Leonard

By using physical and chemical method to increase the bulk density of newly mined coal, the productivity of a mine can be significantly increased. Greater amounts of coal can be placed in fixed volume shuttle car by increasing bulk density. This can increase mine productivity by about 15%. Small, easy to achieve changes in mining operations are required to obtain the increased productivity. This article deals with chemical methods used to increase coal bulk density, the results and discussion are based on experiments performed in the laboratory.

Jan 1, 1992

By V. G. Lofftus

Since plant start-up in January 1983, Golden Sunlight Mines, Inc. has implemented several process changes and improvements. Among these are a pulp preaeration circuit and a sand tailings retreatment circuit. The purpose of the preaeration circuit is to reduce reagent consumption during gold dissolution. The sand tailings retreatment circuit was added to recover and process separately pyrite concentrate to maintain acceptable overall gold recoveries with the more refractory sulfide ores. Research and plant operating data along with process and improvement descriptions are presented.

Jan 1, 1987

By C. M. Chang, H Gu, J. A. Barrera-Godínez, T. J. O’Keefe

The inability to economically separate Fe3+(aq) from a variety of liquid effluents is a major Concern for the primary metals industry. A unique solvent extraction process, galvanic stripping, has been developed to address this problem. The galvanic stripping of iron from D2EHPA using only a 5~10 g/L H2SO4 solution is achieved after Fe3+ is directly reduced to Fee, in the organic phase using zinc metal additions. To date, the primary focus of the laboratory research has been on optimizing the parameters that control iron removal. The results from these studies have now been, used to make a preliminary design for a continuous flow process that is envisioned for zinc industrial applications. Specific quantitative data are shown for the use of a Zn-Ph cellos° in the iron-reams al process. Some introductory results on electrochemical potential measurements and impurity distribution with solution cycling are also giiven.

Jan 1, 2000

By C. D. Elifrits

The required reclamation of land disturbed by surface coal mining often results in the creation of some over steepened slopes which are prone to rapid erosion and sediment production. This natural activity on such slopes is not desirable nor allowed under current regulations. Experience has indicated that novel approaches must be devised to address the problem. Research conducted on field sites in Missouri has indicated that construction, during the reclamation and grading processes, of a man-made drainage system will control the erosion. The drainage system must replicate or exceed the natural system in terms of drainage density and channel frequency. Basic design considerations will be summarized in this paper and field results shown.

Jan 1, 1986

By J. P. Matoney

In recent years, the diminishing supply of natural gas has led energy suppliers and consumers to consider making synthetic natural gas from coal. A number of processes have been devised to produce gas from coal; many of these have been operated at the pilot stage and some have been operated commercially. Each process has specific coal feed stock requirements with respect to size consist and moisture content. The purpose of this presentation is to compare the estimated costs for coal handling, live storage, size reduction and drying facilities that would be required for delivery of coal feedstock to different gasification processes.

Jan 1, 1977

By E. E. Maurer

Kerr-McGee has operated the Ambrosia Lake uranium mill since startup in 1958. Tonnage milled per day has varied from 3500-7000 tons. The mill capacity is currently rated at 7000 tons per day. The process consists of two parallel circuits following crushing and sampling, \\lhich include open circuit rod mill grinding, sulfuric acid leach, cyclone classification, and counter-current washing circuits of sand classifiers and slime thickeners. Pregnant solution is clarified and polished by precoat pressure leaf filters prior to amine solvent extraction. Yellowcake is precipitated from the pregnant strip solution with ammonia, filtered and dried.

Jan 1, 1972

By Theodore Feldsher, Seung Han Kim, Mourad Attalla, John Roadifer, Chu-Chieh Jay Lin

Lifelines in seismic regions of the world seldom can escape crossing active faults. Cities in California have been mitigating this risk by constructing improved fault crossings. This paper discusses the analyses and design of the lining for a tunnel carrying a water conveyance pipeline through a fault that can potentially displace during a major earthquake event. The paper presents expected fault displacement, fault width and orientation respective to the tunnel, characterization of the ground surrounding the tunnel and its interaction with the lining, and performance required of the lining. Several other fault crossings will also be presented and discussed

Dec 1, 2022

By R. G. Reddy

Viscosities of Feo-SiO2 slags were calculated using the previously developed structural based model. An expression was derived using hole theory and the atomic pair model to relate the NO0 and temperature to the viscosity. The deduced equation n=4.9x10-9 T1/2 NO0 exp (E/RT) poise was successfully applied to predict the viscosity of FeO-SiO2 slags in the composition range of 0.1 < XSiO2 < 1 for several temperatures. The calculated data agrees well with the experimental viscosity data.

Jan 1, 1991

By B. R. Pothini, H. von Schonfeldt

In underground coal mining many excavated openings have a relatively short projected life span. To ensure safety for men and materials at a minimum cost over the projected operating life, only pillars for overburden support and roof bolts for support of the openings are used extensively. Mining activity constantly changes the geometry of the mine producing load changes on the structural support members of the openings that often induce unstable deformations which can lead to roof falls or pillar failures. The paper describes how simple deformation measurements can be used to design primary and supplementary roof supports and to predict roof falls and possibly pillar bumps. Specifically, bed separations in the roof measured directly with the help of borescopes and calculated from differential convergence data are used to optimize bolt links or support requirements for chemical stabilization of mine roofs. Roof falls are predicted on the basis of admissible values for cumulative convergence between roof and floor, convergence rate, and the change of the rate of convergence. The pillar extraction operations convergence anomalies detected from contouring identify bump prone pillars, while convergence and pillar dilation determine the yield zone in a pillar to verify pillar softening and de-stressing. Manuscript not received in time for publication.

Jan 1, 1983

By H. Shafick Hanna

The beneficiation characteristics of low grade Birmingham red iron ores of the Big Seam and Ferruginous Sandstone seams were investigated using flotation and magnetic separation after reduction roasting. Samples of Bib Seam Ore responded more readily to concentration than the Ferruginous Sandstone ores. The impurities inherent with the iron oxide minerals limit the grade of concentrates recoverable from these ores to a maximum of about 61% Fe if reasonable iron recoveries are sought. Flotation concentrates assaying 60-61% Fe and about 0.1% P with attendant iron recoveries of about 63% were achieved from Big Seam ore charges while those obtained from the low phosphorus Ferruginous Sandstone samples analyzed 54-56% Fe. Reductive roasting and magnetic separation of ground charges of the two ore samples yielded concentrates assaying 60-61% Fe. Iron recoveries were better than those achieved by flotation, but the magnetic products of Big Seam ore were high in phosphorus (0.2-0.3% P).

Jan 1, 1983

By William J. Shampine

The Floridan aquifer, which underlies all of Florida, yields water with a sulfate content of less than 50 parts per million in the north-western part and throughout most of the center of the State. In the southern part of Florida and along the most of the east coast, the sulfate concentration generally exceeds 100 parts per million and is as much as 1,700 parts per million. The sulfate concentration tends to be higher in the deeper zones of the aquifer. This map shows the sulfate concentration in the upper part of the aquifer. Sulfate is found in almost all natural water. Sulfate in rainwater is dissolved from impurities and gases in the atmosphere. Rankama and Sahama (1955, p. 314) report that the average sulfate content of rainwater is two parts per million; however, concentrations have been as high as 283 parts per million. Much of the sulfate in rainwater comes from hydrogen sulfide gas which is generated in shallow water on the continental shelves. The combustion of bituminous coal used for heating and industrial purposes seems to be an important local source of sulfate.

Jan 1, 1966

By E. L. Piper

Natural graphite has been known for many centuries, having first been reported as a distinct mineral form by Gessner in 1565. At that time, graphite was used extensively as pencil "lead" because of the ease with which it marks paper. It is a black, unctuous material found as flakes, lumps, or needles in scattered locations throughout the world. The less crystalline, or "amorphous", natural graphites are thought to have been formed from coal under conditions of high temperature and pressure. The more crystalline varieties, such as those mined in Ceylon, probably were precipitated from molten solutions or were pyrolyzed from gaseous carbon compounds. Recognition of the good thermal and electrical conductivity of graphite, together with its highly refractory nature, led to an increasing number of appli¬cations for this material. Clay and pitch bonded natural graphite has been used in crucibles, refractories, foundry facings, and other high-temperature appli¬cations. These forms constitute the most important current uses for natural graphite in the United States. Other products containing natural graphite include batteries, lubricants, pencils, brake linings, etc.

Jan 1, 1973

By D. W. Carson, R. J. Trembley

Thoron daughter WL&apos;s measured by alpha-spectroscopy and the Kusnetz method are about one-half those of radon daughter WL&apos;s in a uranium mine in Canada.1 A diffusion model can account for the relative concentrations.l Since the Kusnetz technique is most widely used for measuring radon daughter WL&apos;s in uranium mines, a general procedure is derived to extend this method to measurement of WL&apos;s of radon and thoron daughters in air containing their mixtures. Coté P. and Townsend M.G., 1981. A procedure is also suggested for counting radon and thoron daughters by 3-channel [a]-spectroscopy. Errors in WL(Rn) are calculated for standard radon daughter counting procedures when a-decay of both thoron and radon daughters is attributed to radon daughters alone. Providing overall counting times are short, [<]30 min, these errors are generally small. The precision of ß -counting methods is also investigated. A portable 3-channel alpha spectrometer for measurement of radon and thoron daughters in uranium mines or homes is described, Carson D.W., 1979. The computer programs for analyzing the data to give, depending on the mode employed, some or all of the concentrations RaA, RaB, RaC, ThB, ThC and WL of radon and thoron daughters by alpha spectrometric, modified Kusnetz, Rolle and Tsivolglov methods are presented.(l) A commercial apparatus, based on the above prototype, incorporating a microprocessor and built under contract to EMR is now available.(2) A number of personal radiation dosimeters for miners are now being tested in mines. One of these is the CEA dosimeter which uses the track-etch film method, Duport P., Chapuis A.M. and Pradel J., 1979. An apparatus for rapid reading of track-etch films by the spark technique has been described previously, Cross W.G. and Thomasino L., 1970 and Huang V.F., 1975. We have developed such an apparatus for rapid semi-automatic reading of films exposed to radiation from mixtures of radon and thoron daughters in CEA dosimeters. The films used, Kodak LR 115 Type II Strippable, may be stripped rapidly and easily, for counting after irradiation and developing, by use of a special punch and suction technique. The method promises to provide an inexpensive and rapid technique for reading large quantities of personal dosimeter films. However, the present CEA dosimeter has faults in design, leading to a contamination problem. Those films that show contamination cannot be read by automatic means. A commercial apparatus based on the above prototype spark counter and built under contract to EMR is now available.3 1. These computer programs are available on request. 2. Pylon Instruments, Ottawa 3. Bondar Clegg, Co. Ltd., Ottawa. REFERENCES Carson, D.W., 1979, "Canalph-3, a Portable Three-Channel Alpha-Spectrometer for Measuring the Daughter Products of Radon and Thoron", CANMET Division Report MRP/MSL 79-108 (TR). Coté, P. and Townsend, M.G., 1981, "Mixtures of Radon and Thoron Daughters in Underground Atmospheres", Health Physics, Vol. 40, pp 5-16. Cross, W.G. and Thomasino, L., 1970, "Rapid Reading Technique for Nuclear Particles Damage Tracks in Thin Foils", Radiation Effects, Vol. 15, pp 85-89. Duport, P., Chapuis, A.M. and Pradel, J., 1979, "Appareil Individuel pour lu Dosimetrie des Descendants du Radon", Advances in Radiation Protection Monitoring, IAEA Vienna, pp 435-443. Huang, Y.F., 1975, "Determination of Uranium in Minerals using Fission Tracks", M. Sc. Thesis, University of Toronto, 48 pp.

Jan 1, 1981

By R. L. Pozzo

A previous investigation showed that corrosion currents estimated from polarization curves for the pyrrhotite-grinding media system under abrasion correlated well with corrosion currents estimated from marked ball wear test data by applying the Faraday&apos;s Law. Freshly abraded metal debris were magnetically attracted to pyrrhotite and lowered the rest potentials of the mineral particles, thereby affecting the corrosive wear. The investigation was extended to explore the interactions between a nonmagnetic sulfide mineral, pyrite, and abraded metal debris and their effects on the corrosive wear mechanism. The electrochemical behavior of a three-electrode system involving pyrrhotite, pyrite and grinding media was also investigated as a first step towards elucidating the nature of interactions that occur in the grinding of complex sulfide ores.

Jan 1, 1987

An insufficient hydrologic data base exists for most large and small coal basins in Alaska owing to the lack of need in the past to collect data. The runoff process is insufficiently understood which is complicated by specifically northern phenomenon, and the lack of understanding of hydrologic relationships in permafrost environment. This paper presents an understanding of the hydrologic effects of frozen ground and presents methods by which the influence of surface mining upon the hydrologic balance can be analyzed.

Jan 1, 1988

By Biswajit Samanta, Pranjal Pathak

This article presents a customized genetic algorithms (GA) with new crossover and mutation operators to solve the short-term production scheduling problem of multi-mine mineral value chains (MVC). The preceding problem consists of determining the extraction sequence and destination allocation of blocks from all the mines collaboratively while closely meeting the quality and quantity requirements of the processing units subject to relevant technical and operational constraints. The short-term production scheduling is carried out at shorter scales wherein the operations are modeled in a great detail with large number of constraints. This makes the industry-scale instances of the problem computationally intractable for standard mixed-integer programming (MIP) solvers. Thus, a GA-based heuristic approach is developed to obtain nearoptimal solutions to the large-scale instances of the problem in a reasonable amount of computational time. Computational experiments show that the developed GA-based method is a promising way to handle industry-scale instances of the problem. Moreover, the sensitivity analysis on various parameter combinations of crossover and mutation operators indicates that the customized global mutation operator, when used in combination with the customized crossover operators, took on average 12.5% less time than the customized local mutation operator to converge to a solution.

May 21, 2022

By P. Geoffrey Feiss

The Piedmont province of the southern Appalachians is becoming the focus of interest for many exploration geologists. In the past, only those deposits with significant surface exposure have been exploited. Thus, few deposits have been found and relatively little exploration has been conducted in recent years. Modern geochemical and geophysical techniques can alleviate this problem of concentrating on exposed ore bodies by allowing us to "look through" the soil and saprolite to detect the presence of significant mineralization at depth. This paper will attempt to evaluate the feasibility and effectiveness of several geo¬chemical exploration techniques in the Piedmont, of Cabarrus and Stanly Counties, North Carolina. The area chosen for the study is shown in Figure 1, lying almost wholly within the Mt. Pleasant quadrangle, North Carolina. The area is on the eastern boundary between the Charlotte belt, a zone of plutonic and intermediate grade metamorphic rocks, and the Carolina Slate belt, a series of complexly interbedded volcanic and sedimentary rocks of predominantly low grade metamorphism. The area is now considered to be a 500 million year old active, continental margin.1 As is typical of most of the piedmont, outcrop is sparse. Figure 2 is a sketch map of the general geology of the area under study, showing the Charlotte belt rocks in the northwestern quadrant and slate belt rocks, to the east. Within the area are a number of old mines and prospects, the most famous of which are the Furniss and the Phoenix mines in Cabarrus County. All are reported to have contained Au and Cu. Ag and Pb were reported from some. A summary of the deposits is given in Table 1. Data used in this study are from three Master&apos;s theses conducted at the University of North Carolina at Chapel Hill. 3,3,6 In separate studies, well waters5, B-zone soils3, and vein and float quartz6 from the area described were sampled and analyzed. Each study concluded separately that geochemical anomalies in the vicinity of the ores justify use of that specific sample type in a geo-chemical exploration program. However, no comparative study of the methods has

Jan 1, 1977

By S. Makni, F. Wang, A. Rosa, B. Klein, C. Saud, R. McIvor, A. Kumar, C. Gagnon, D. Gong

In response to the Natural Resources Canada “Crush It Challenge”, Corem partnered with the University of British Columbia and led a project to develop and demonstrate the use of high-pressure grinding to replace the workhorse of the industry, wet ball milling, with high-pressure grinding. Two plant case studies, a small tonnage gold recovery operation, and a large tonnage copper recovery operation, were carried out. Plant circuit performances were compared to pilot plants operated on the same circuit feed set up to represent the novel equipment and flowsheet that was developed to produce separation circuit feed. Numerous obstacles to industrial implementation of highpressure grinding in this role which were recognized at the outset of the work were successfully addressed. In both cases, comminution equipment energy savings alone, and final stage total circuit energy savings, exceeded 60% and 50%, respectively. Downstream mineral separation performance was the same or better.

Mar 2, 2022

By Jean E. Tilden

An investigation of several trace elements distributed among sulfide minerals from deposits located in the southeastern United States was conducted. The deposits investigated are distributed within both the Blue Ridge Province and the Piedmont Province, which are contiguous geographic provinces. Twenty five deposits were examined;&apos; eleven in the Blue Ridge Province and fourteen in the Piedmont Province. Figure 1 shows the locations of deposits investigated. In the deposits investigated, the mineral phases examined were pyrite, pyrrhotite, chalcopyrite, and sphalerite. These phases were chosen because of their relatively widespread occurrence, although no pyrrhotite was seen in the Piedmont Province. A total of 116 polished surfaces of ores were prepared, and mineral phases were collected from these surfaces for analysis. Samples were analyzed for cobalt, nickel, manganese, lead, tin, chromium, molybdenum, and gold. A total of 372 analyses were made. Trace elements were determined by atomic absorption spectrophotometry following standard procedures. In this study, trace elements are defined as those elements which are present in the mineral but which do not affect the chemical formula for that mineral. Lead is considered as a trace element only in ores where little or no lead sulfide could be identified as a distinct mineral phase.

Jan 1, 1972