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By S. C. Dhara

The recovery of Platinum Group Elements from various industrial scraps and spent materials in the form of high and low grade, such as, impure metals, matte, catalysts and other ceramic substrates, etc., has .been described by using high pressure reaction method. Nickel, Stainless Steel, Titanium and glass lined reaction vessels? are used in the reaction process. Primarily, the method involves either direct leaching of the substrates from the metal value or dissolving the precious metal from the substrate. Both acids and alkalies are used along with other reagents in the reaction process. The temperature and pressure of the leaching process are the main criteria for the reaction kinetics.

Jan 1, 1989

By M. Kaya, A. R. Laplante

"Since the beginning of eighties the use of flotation columns has surged in Canada and abroad; the metallurgical superiority of columns over mechanical cells is in great part due to froth washing, which ensures higher gangue rejection and selectivity. Can wash water, which has proven so beneficial, be used in mechanical cells? Although froth washing technology was widely implemented in Soviet plants for bi tuminuous coal, and alusite, powellite, scheelite, molybdenite, etc. more than 25 years, it has been neglected in the western world. Published data suggest 10 to 15~ increases in grade and/or recovery with wash water in mechanical cells (Klassen and Mokrousov, 1963). There are at least three wash water plant applications in Zaire, Chile, and Canada, but little, if any, published information is available. This research work, which is the first extensive fundamental study related to froth washing in mechanical cells, attempts to answer the questions of how, how much, and where should wash water be added.This project was undertaken in three stages:1. Bench-scale laboratory tests with a 6.5 L Denver cell at McGill using a silica flour and a slime reject from Niobec (St.Honor6).2. Pilot-plant scale tests with a 65 L Denver cell at McGill using the silica flour and a complex Cu-Ni sulphide ore from the Strathcona mill of Falconbridge.3. Plant-scale tests with a bank of 2800 L Denver cells at Falconbridge Ltd. for complex Cu-Ni sulphide ore and Eastmaque Gold Mines Ltd. for Au tailing reclaimation."

Jan 1, 1989

By R. L. Beatty

Bond International Gold's Colosseum gold mine was discovered in 1865. No recorded production occurred, however, until the 1930s, with production of about 19 kg (615 oz) of gold. The mine was closed in 1942 as a nonessential industry during World War II. The property was acquired by Dallhold Resources in mid-1986. Construction of a 1.1-million Mt (1.2-million st), carbon-in-pulp (CIP), cyanide mill began in November 1986 and was completed in September 1987. Minable reserves are estimated to be 9.5 Mt (10.5 million st), with an average grade of 2.1 g/t (0.061 oz per st). This article describes the general process flow and plant equipment. And it looks at the maintenance and operational problems encountered in the first six months of operation. Process description Ore is direct hauled from the open-pit mine 1.5 km (1 mile) to the crushing facility. There it is crushed to -152 mm (-6 in.) with a single- stage, 1.5-m x 1.2-m (60-in. x 48-in.), 186.5-kW (250-hp), Fuller-Traylor jaw crusher. The ore is then stockpiled in a 31.7-kt (35,000-st) reclaim ore pile. Lime is added to the crushed product as it is conveyed to a single 6.4-m x 4-m (21-ft x 13-ft), Hardinge semiautogenous grinding (SAG) mill, followed by a single 4.3-m x 7.3-m (14-ft x 24-ft) Hardinge overflow ball mill. After grinding, the slurry is thickened and then preaereated for three hours. Following preaereation, the pulp is leached with NaCN at a pH of 11, also for three hours. The slurry then goes through a seven-stage CIP circuit for 21 hours. Then the tailings slurry is preaereated for three hours before cyanide destruction using the Inco process. Loaded carbon is eluted using an Anglo American strip, followed by electrowinning on stainless steel wire. The stainless steel wire is transferred to refinery cells where the gold and silver is plated on stainless steel plates. Following electrore-fining, the gold-silver foil is removed, melted, and poured into dore bars for shipment. The crushing, milling, refining, and maintenance processes require 37 people. Crushing The crushing area required changes and modifications following start-up. Several areas are of specific note. Structural failures Rubber support cushion blocks located under the coarse ore bin failed. These were replaced with heavier, more durable blocks and have since appeared to be satisfactory. A severe structural vibration was encountered in the entire crushing facility. A mechanical engineer, brought in by the contractor, determined the structure needed more support and cross-bracing.

Jan 1, 1989

By J. Launay

In order to control and dispatch the sewage water coming from 3 tunnels toward 2 downstream sewage tunnels, a large cavern has been excavated in a suburb of PARIS. Located at a depth of 47,00 m, it has been excavated using the NATM procedure through swelling clay, weathered sandstone, and marl and chalk. It is 16,50 m high, 12,40 m wide and 60, 00 m long, with an elliptical cross-section and its two ends are egg-shapped. The final lining of the cavern is composed of 30 to 40 cm of shotcrete, steel ribs and passive anchor bars. The excavation stages and related movements were surveyed by extensometers, pressure cells and convergence devices. The design, method of construction of the cavern and the results of the measurements made are commented.

Jan 1, 1989

By Chao-jiong Hou

The necessity of using tensible rockbolt in the roadway with soft rock, high in-situ stresses, mining influence and other complex conditions was discussed, the structures of three kinds of tonsibte rockbolt and design principle were introduced in this paper. The tests of analogue material simulation under plane strain condition and underground industrial tests indicated that the effect of controlling deformation surrounding roadway by use of tensible rockbolt was good.

Jan 1, 1989

The formation of tension cracks in slopes is well known. Analytical studies require the determination of a critical slip surface for any slope and, in doing so, it is necessary to consider an appropriate tension crack. A general yet simple approach is proposed for identifying the critical slope failure surfaces associated with critical tension cracks. The minimum factor of safety consequently reflects both safety against shear sliding and tensile failure. In general, the critical slope failure surface for a slope determined in this way differs from that which is obtained without optimizing the position and depth of the tension crack. In particular situations, the difference is significant.

Jan 1, 1989

By Jorge Martinez

The Muck Valley Hydroelectric Project in Northeastern California required construction of a 3.65 meter tunnel through 6,623 meters of mixed volcanic flow deposits within a critical time frame. As Engineer and Construction Manager for the Project, Morrison-Knudsen Engineers invited bids for both Drill and Blast as well as Tunnel Boring Machine methods, selecting a contractor proposing a TBM designed and built specifically for this project which could excavate a wide variety of materials and maintain acceptable progress rates to complete the work within schedule. Tunnel lining as required included shotcrete with metal fibers and full circle concrete.

Jan 1, 1989

By P. W. Ocerbeek

The occurrence, properties, and uses of andalusite, and its advantages over other refractory minerals and materials, are discussed. Ore reserves are given for the five producing areas, and statistics on production, export sales, and prices are included to illustrate the growth of the industry since the early 1960s. The mining and beneficiation procedures are described, with special reference to new techniques in concentration and magnetic separation. As fines dumps represent a considerable source of andalusite, possible methods of recovery are discussed. . The outlook for the future appears favourable, and possible competition from other sources and substitute refractory minerals are mentioned. It is concluded that the industry is in a sound position to maintain South Africa's status as the world's foremost producer and supplier of andalusite.

Jan 1, 1989

By Laxman S. Sundae

A U.S. Bureau of Mines designed and fabricated in-seam tester (1ST), retrofitted with a dust shroud, was used to establish a respirable dust index (RDI) and to determine cutting forces from a variety of bit types in four coal mines and a salt mine. Results from cutting tests at four coal mines showed that radial bits required the lowest cutting force and the least specific energy. Generally, for each conical bit the RDI and cutting force increased when the included bit tip angles increased from 70° to 90°. During field tests it was not possible to measure the total quantity of respirable dust produced by each cut; therefore, attempts were made to determine the amount of dust that became airborne from each test cut. The test results show that the quantity of airborne respirable dust is very erratic and cannot be related to bit type. Two statistical methods were employed to analyze RDI, but no correlation was found between the RDI and bit type. Despite scatter in test results for RDI, significant difference was found in RDI generated in four coal seams. In general, RDI increased with the increased cutting force for each coal seam from mine 1 through mine 4.

Jan 1, 1989

By F. A. Kruse, R. J. Madrid, P. L. Hauff

Sub-microscopic gold grains in disseminated gold deposits in Nevada are often directly associated with the clay mineral illite. Delineation of gold ore-zones can be improved by accurate characterization of the associated illite varieties or polytypes. X-ray diffraction studies of clay minerals from several disseminated gold deposits demonstrate that illite polytypes reflect lateral and vertical zonation around the ore bodies. Polytypes act as geothermometers indicating temperatures of ore deposition and proximity to hypogene and supergene fluids. Visible/near infrared spectral measurements using a field-portable reflectance spectrometer provide a reconnaissance technique for mapping the in-situ distribution of illites. Changes in the visible/near-infrared reflectance spectra are observed as illites progress from the lower temperature, less ordered 1 M variety to the higher temperature 2M type. The combination of the reflectance spectroscopy with the X- ray diffraction data creates a powerful tool for detailed mineralogic mapping for gold exploration.

Jan 1, 1989

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

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

Jan 1, 1989

By W. E. Straszheim

Computerized microscopic techniques were used to determine the size and identity of the ash-forming mineral components, as well as their association with the organic coal matrix, in order to aid in the development of physical methods of beneficiation which require such characterization for the most effective cleaning. Examples of particle size measurements, mineral phase identification, and especially coal-mineral association results are given for selected samples of raw and physically cleaned coals. These measurements can reveal certain characteristics of coals which can be be of significant value in predicting coal recovery and mineral matter rejection for coals undergoing beneficiation.

Jan 1, 1989

By N. Arbiter

During the first four decades of flotation practice, close to 200 machine designs were patented, although only about a score were ever used commercially. By the end of that period, the rigors of use had resulted in obsolescence of most pneumatic cells, with a few mechanical cells dominating the field. After World War II, newer designs began to appear but most were modifications in varying degrees of older designs with special features added. Of the dozen or so most recent developments, almost all are pneumatic, relying on compressed air instead of impellers for motive power, although in several cases pumps supplement compressors. Table 1 lists a few of the more fully documented new cells, with their significant characteristics, along with similar characteristics of a widely used mechanical cell. New designs in general are emphasizing: bubble size control; in several cases, methods for delivering feed directly to the froth; methods for introducing and dispersing air through nozzles, eductors, packed beds, or permeable walls; and variable cell volumes, relative to capacities, ranging from very small, with less than a second of retention time, to the largest, with retention times of over 20 min. An important question is the extent to which any of the newer designs are based on locating weaknesses in current mechanical cell designs and then using these as a starting point for innovations. In the present study, the key subprocesses which must take place in a cell are outlined; mechanical cells are analyzed to establish where weaknesses may exist; and then alternative subprocesses are considered which could effect improvements. COMPONENTS FOR CELL DESIGN It is assumed that mineral surface chemistry has been modified as necessary to provide optimum potential floatability. While the cell process may affect this to a degree, cell design is primarily concerned with actualizing the existing potential floatability. The cell design problem is to provide more effectively for the following: 1) Dispersion of air to obtain an optimum bubble size distribution at an optimum ratio of air volume to feed volume. 2) A hydraulic environment which permits most effective contact of potentially floatable particles with bubbles: [Table I - Cell Comparisons* Cell Type Mechanical Column Deister Miller ASH No. of units Multiple Single Single Single Retention time min.10/20 17/27 3.8 ca. is Capacities mt/m3s 0.022/0.066 0.066/0.20 0.11 10.4 st/ft3d 1/3 0.3//0.9 m5.0 469 Air hold-up % 15/20 20 n.a. 50/80 Air escape velocity m/s 0.015/0.0200.020/0.025 n.a. n.a. ft/m 3/4 4/5 n.a. n.a. * References: Mechanical (Harris, 1976,1985), (Bassarear, 1985); Column (Travis, et al. 1987); Deister (Zipperian and Christophersen, 1985); ASH (Air-Sparged Hydrocyclone) (Miller 1989).]

Jan 1, 1989

By B. W. Lawrence

Shaft alignment requirements are consistently met using conventional shaft sinking methods. Little attention has been given to achieving similar alignment accuracies using rotary drilled shaft methods. Alignment of these shafts is difficult to control and guarantee. Bare shafts and shafts that use drum hoisting systems can accept some deviation. However, combining drilled shafts with Koepe hoist installations presents new accuracy requirements for drilled shafts. This paper describes the importance of verticality with practical examples, and discusses various methods of measuring verticality and their respective limitations.

Jan 1, 1989

Between 1985-1986, the Bureau of Mines reviewed the mining history and minerals information for areas in and near the San Isabel National Forest to appraise the mineral resources present and determine the types of deposits, and their location in the Forest, that could be mined economically if sufficient demand and metal prices existed. The two major metallic deposit-types that are of national mineral resource significance within the Forest are stockwork- molybdenum (with tungsten and tin) and carbonate-replacement zinc-lead-silver deposits. Historically, small gold placers, gold-quartz veins, silver-quartz veins, skarn iron and copper deposits, volcanogenic copper-zinc-precious metal deposits, and base- and precious-metal veins have been mined. Barite, carbonate rocks, gypsum, other non-metallic deposits, and pegmatites, have also been mined. Sand and gravel, present in large volumes, occurs along and has been mined outside the Forest along the upper Arkansas River valley. Turquoise and gemstones are present in small amounts and are of interest to collectors and jewelers. Geologically, sediment-hosted uranium and copper are present in small occurrences but no resources have been identified. Geothermal resources are related to the Rio Grande rift which parallels the central part of the Forest. Four hot spring areas are present - two of these are within the Forest. Because of the low power requirements of the region, and the presence of other generating facilities, these geothermal resources have had only limited local use. Evaluation of mine models that may be found in the region show that base-metal deposits require a high precious-metal component to be economic. Although molybdenum can be produced at economically competitive prices, there is little demand for the product. Capital costs to start new molybdenum mines would be very high and it is not likely that new mines will be put into production in the near future.

Jan 1, 1989

By LeEtta M. Shaffner, John R. Marks

The Homestake Gold Mine in Lead, South Dakota, commenced operations in 1876. As is the case with old, deep, continuously developing mines, a ventilation improvement is periodically required to maintain acceptable underground environmental conditions. Recent historical improvements at Homestake include a 5.2m diameter air shaft driven in the 1960's and a 2.1 MWR (580 ton) chilled water plant installed in 1978. By 1983, it became apparent that yet another ventilation upgrade would be needed to keep pace with accelerated development in the deepest mining sections. A study was therefore undertaken to project ventilation requirements for the next ten years and to select the method(s) most suitable to meet those requirements. The study called for a two-phase approach in which air flow and air conditioning were carefully balanced. Phase I, the installation of a new 2240 kW surface fan and several underground circuit changes, was completed in 1986. This paper describes Phase 11: the planning, design, installation and initial performance of the air-conditioning portion of the upgrade.

Jan 1, 1989

By Stanislaw Wasilewski, Zdzislaw Krzystanek, Boleslaw Firganek

The experimental system for mine venti1ation control in Staszic colliery has two - level structure. In the lower - measuring 1evel the existing computer - based early fire detection system has been used completed with a number of additional sensors needed for ventilation parameters monitoring. The higher 1evel is a secondary computer equipped with a suitab1e dedicated software performing data processing according to the control a1gorithm. Direct control of air flow in a selected mine district is performed by means of a remotely controlled automatic regulator. Apart from functional tests of the system and its elements some research work has been carrying out in the colliery based on observations of transient effects caused by changes in air flow distribution.

Jan 1, 1989

By Terence G. McCusker

Precast concrete segmental tunnel linings have been used since at least 1903. More serious attention was devoted to them in England during the World War II steel shortage and they have become increasingly common since that time. They are now coming into common use in the United States, especially as primary linings for soft ground tunnels and for rock tunnels in poor ground, although they have also been used as final lining, especially in rock tunnels. The developmental logic, design considerations, and current practices are examined. Particular attention is given to unbolted linings, with and without secondary linings. Probable future developments are considered.

Jan 1, 1989

By R. T. Stain

Dynamic methods of load testing piles using a drop hammer to generate the input force have been in use for many years. These systems are based on the wave equations developed at the Case Institute of Technology, Cleveland, Ohio in the late 1960's and are well documented. Such tests are generally restricted to preformed driven piles, the driving hammer being a convenient means of generating large input forces. In 1979 the CEBTP (France) was sponsored by the FNTP (Fédération Nationale des Travaux Publics) to undertake research into existing classical methods and to develop a test that would be equally applicable to bored cast in place piles. The result of this research programme is a methodology known as SIMBAT, and which was included in a series of class A prediction trials in Belgium in 1987 (Refs 1 & 2, Paquet 1987, 1988). The purpose of this paper is: a) to examine the type of 'dynamic'/'static? load test correlations that can be obtained. b) to highlight the differences between the classical' methods and the 'SIMBAT' technique.

Jan 1, 1989

By D. G. Wymer, A. G. du Plessis, N. C. Joughin

The use of a dense hangingwal-support configuration extending right up to the face would enable greater levels of safety and productivity to be achieved in stopes, and becomes a practical proposition if water jets are used for stope cleaning. Such an arrangement opens the way for extending the use of water hydraulic power to the whole stoping operation. This, in turn, can provide further productivity benefits and significant savings in working costs. With al the necessary equipment being available, such a system could be introduced immediately, although the designs of props and rockdrills are not yet ideal.

Jan 1, 1989