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By Walker G. S

A study of the crystalline materials on or near the surface of freshly made or "green" superphosphate granules and mature, "set" superphosphate granules was undertaken using X-ray diffraction, X-ray mapping, scanning electron microscopy and electron probe micro analysis techniques. Calcium sulphate (CaSO4), calcium sulphate hemihydrate (CaSO4 1/2H20), and mono calcium phosphate monohydrate (Ca(H2PO4)2H2O), were the only crystalline species present in the "green" superphosphate.In the set superphosphate however, additional compounds were present, namely complex iron and aluminium phosphates Ca(Fe,AI) H(HPO4hF2)2H2O, (Fe)3(H3O)H8 (PO4)6H2O and calcium sulphate dihydrate (CaSO4.2H2O).The complex phosphates tied up the major part of the Fe and Al in the system and were concentrated on or near the surface of the granule. An intimate mixture of CaSO4.2H2O, and CaSO4, along with the above mentioned complex Fe-AI compounds, crystallize close to the surface of the granule and cause the setting of superphosphate that takes place during storage.

Jan 1, 1980

Mt Waruwari, host to the Porgera underground gold mine in the Highlands of Papua New Guinea (PNG), is a prominent ridge of sediments and dioritic intrusives rising approximately 600m above the surrounding valley floor. Consequently, mining occurs in a low stress environment where structural and material considerations are foremost in the design of ground support and reinforcement. Three major rock types are encountered in the underground mine. These are locally referred to as "black sediments" (slightly indurated mudstones and clayey siltstones), "altered sediments" (derived from black sediments by thermal metamorphism), and "intrusives" of dioritic composition. The rocks are moderately to highly fractured, the black sediments being generally weak and occasionally sheared while the altered sediments and intrusives are quite strong but often brittle. Mining takes place from a series of stopes extracted by either slot and mass blast or a modified vertical crater retreat method (VCR), which are backfilled with a cemented rock fill. Ground support and reinforcement has been relatively conserv- ative to date and generally relies on pattern reinforcement of all development with cement grouted "rebar" bolts and mesh, extending to pattern cable bolting with occasional mesh in stope backs. In addition there has been considerable reinforcement of stope hangingwalls in some cases. A programme of broad scale structural mapping, monitoring with extensometers, material property testing, and stress analysis has been devised to allow optimum design of ground support and reinforcement in the future. Considerable work remains to ,omplete this task.

Jan 1, 1991

Removal of Arsenic in Enargite from Copper Ores by Flotation and Leaching in NaHS Media

Sep 13, 2010

By J. D. Bliss, G. J. Orris, W. O. Menzie

"Analysis of gold placer data from gold placers throughout the world suggests that gold grades and volumes cannot be used to distinguish between most types of gold placers. Only the alluvial plain and fan placers are significantly different among the types of gold placers considered. Gold grades and volumes change when working gold placers go from small-volume methods to large-volume methods. The small-volume methods are either of the surface or subsurface (drift mining) type. The odds that a gold placer will be dominantly worked using small volume methods at the surface are about 5:3. Once small volume mining has occurred, the odds against subsequent large-volume mining are about 4:1. If a placer deposit is suitable for large-volume mining, and the amount of gold produced from small-volume mining was reported, an estimate of the remaining gold (log10kg) can be made using the following equation:The relationship shown by this equation suggests that very large gold placers have over half their total gold content in the rich gravels appropriate for small-volume mining. These relationships in conjunction with other data and computer simulation can be used to estimate placer gold resources for an area targeted for mineral resource assessment. IntroductionGold placers have been an important source of gold throughout man's history and may have been one of the first sources-dating back to around 6000 B.C. (Gregory, 1980). From the primitive basket to the modern floating dredge, a variety of methods have been used to work gold placers. Placers are found in a wide spectrum of geologic and climatic settings. They have been classified by using a mixed set of criteria including age (Recent, Tertiary), climate (desert), fluvial position (modern channel, bench, alluvial fan), environment of deposition (eluvial, alluvial, residual, beach), type of transport (stream, wind, glacier), and whether the placer is buried or at the surface (Boyle, 1979; Wells, 1969). Several mining methods have usually been used to extract gold from anyone placer."

Jan 1, 1987

By Prosser A. P

The conditions under which vanadium is rendered insoluble by silica in the alkali-roast process have been investigated starting with both slag and reagent-grade materials. The inert phase is a glass formed slowlyfrom soluble NaV03 produced at lower temperatures. It contains approximately 30 per cent V in a partly reduced state; iron is not a principal component. Some of the vanadium in the inert phase is slowly returned to a soluble form by heating in an oxidizing atmosphere below the temperature at which the glass is formed (750°C). As the reaction leading to the required, soluble form of vanadium is also slow between 600 and 750° optimization and control of the temperature profile and atmosphere in the furnace, and the residence time of the solids, are necessary to ensure high vanadium extraction during subsequent leaching.

Jan 1, 1976

Ore from the Hill 50 Gold Mine, consists essentially of pyrrhotite, with minor amounts of pyrite, chalcopyrite, galena and gold, replacing "jaspilite." The gold is associated with the sulphides as shotty particles. About 8 per cent. of the particles are less than '0.010'mm.The Hill 50 Gold Mine, at Boogardie in the Murchison goldfield, about 300 miles north-west of Kalgoorlie, was first operated in 1898. From 1898 to 1917 it yielded 20,000 short tons of ore for a recovery of 6,225' fine oz. gold, equivalent to a recovery grade of 6.22 dwt. gold per ton.The present company since the beginning of its operations in September 1936 to June 30, 1954, produced 811,081 short tons of ore for a recovery of 242,554 fine oz. of gold, equivalent to a recovery grade of 5.98 dwt. gold per ton.The grade of ore (recovery grade) has shown a remarkable variation with depth. From the 120 ft. Ievel to the 300 ft. level, it averaged about 7.5 dwt. Au per ton. Below the 300 ft. level it declined, and from 300 ft. to 400 ft. averaged 4.9 dwt. per ton, falling further with increasing depth to about 4.5 dwt. per ton at the '600 ft. level.On the 820 ft. level the grade improved sharply to about 14 dwt: per ton, and this grade has persisted down to and on the 1060 ft. level.The orebody has been described by Finucane (1953) as a series of lenses of finely banded jaspilite conformably enclosed by greenstones. The jaspilite is tightly folded and faulted and intruded by dykes of felspar porpnyry.Mineralization is practically restricted to the jaspilite.

Jan 1, 1955

After the closure of collieries, they naturally start to fill up with water. As a result, hydraulic gradients develop between them and different hydraulic pressures are exerted onto peripheral areas or compartments within mines. This results in water flow between mines, or onto the surface. This flow is referred to as intermine flow. The collieries in the Witbank Coalfield have geometries such that there are several areas where this intermine flow is possible. Since the Department of Water Affairs and Forestry has declared intermine flow as one of its greatest concerns for granting closure to South African mines, much research into this phenomenon is required. The challenges in determining intermine flow are numerous, and attention has focused on identification of areas where these flows can take place. The quantification of these flows is problematic due to the uncertainties in exact geometric configurations and the variation in site-specific hydraulic properties of thecoal and overlying lithilogical layers. During this study, use has been made of numerical flow modelling and several analytic solutions to test the applicability of the flow models as well as to predict groundwater flow directions, filling times of voids and flow volumes. The numerical modelling methodology entailed a downscaling approach starting with a broad regional model covering the entire area, followed by modelling the interactions between interconnected mines, and finally looking in detail at the major areas of interaction.

Jan 1, 2005

Detailed petrographic analyses of coal seams from the Newcastle, Illawarra, and Lithgow Coal Measures were made for a number of localities for each of twelve seams. From these analyses characteristic standardprofiles were derived for each seam. Two broad types of profile were found; one in which vitrite-poor and vitrite-rich layers alternate, and another in which there is a steady decrease in vitrite from the base to the top of the seam. From comparison of the petrographic profiles it was concluded that the Great Northern Seam in the Northern Coalfield is a possible equivalent to the BulIi in the Southern; and likewise the Fassifern to the Balgowni...

Jan 1, 1967

By Arthur A. F, MacKenzie I. H

Copper in zinc/lead sinter charged to the Imperial Smelting Furnace operated by Sulphide Corporation Pty Limited at Cockle Creek, New South Wales, concentrates in a complex lead dross which forms as the bullion is cooled to around 400°C. The 0.35 mm portion of this dross, containing approximatelY 67 per cent of the total copper, is treated via a hydrometallurgical route to produce 5000 tonne/yr of CuSO4 5H2O crystal.Around 3000 tonne/yr of copper-lead dross containing 49 per cent copper is leached at 55°C in continuous leach reactors with ammoniacal ammonium carbonate leach liquors to convert copper to soluble copper amine complexes. Leach ettlciencies of 80-85 per cent are obtained. Leach residues are repulped with ammoniacal liquid diluents from the plant and heated in a four stage steam distillation unit to reduce ammonia levels to between 0.5 and 1.0 g/Iitre. The resultant slurry is directed to an effluent treatment plant for final treatment, and separation and return of solids to the sinter plant.Copper is extracted from leach liquor by solvent extraction techniques based on the use of L1X 54 diluted 3:1 with Shellsol 2046 to give a nominal copper loading of 30 g/litre. The loaded organic is contacted with a sulfuric acid solution of pH 5 to remove the bulk of ammonia and zinc, then stripped at 55°C with a 60 g/Iitre H2SO4 95 g/Iitre copper solution to yield a 15 g/Iitre H2SO4 125 g/Iitre copper solution.This liquor is fed to an adiabatic vacuum crvstalliser operating at 35°C and 5 kPa vacuum where crystals of CuSO4 5H2O are formed. Crystals are separated from mother liquor and washed in a two stage pusher centrifuge, then dried in a hot air rotary drier. The crystal product obtained is of a high chemical purity and readily conforms to both Australian and overseas standards.

Jan 1, 1983

By F. Hassani, D. O’Donnell, M. Momayez, P. Guevremont

Shotcrete is a practical and economical support system in many Canadian underground mines. Although shotcrete technology has gained acceptance in the mining industry, there are some problems that have emerged with respect to quality assessment and thickness measurement of the liner. This paper presents recent tests performed with miniature seismic reflection technology (MSR) developed and patented at McGill University primarily for thickness measurement of this heterogeneous liner. MSR is also capable of providing information regarding the quality of shotcrete in terms of its mechanical properties such as modulus of elasticity and Poisson’s ratio. Work was performed on site in an underground mine in Ontario, Canada. This paper also presents the results from laboratory tests performed on fiber-reinforced and non-reinforced shotcrete panels that were used to assess the P-wave velocity in both materials. The results of these tests were used in a second site investigation. The NDT thickness measurements showed good agreement with direct thickness measurement such as coring. In addition, the MSR technology has the advantage of being more accurate and more affordable compared to other non-destructive testing (NDT) systems in the market.

Jan 1, 2002

By J. C. Borland, J. H. Rogerson

Jan 1, 1963

By Maurice Deul

This bulletin summarizes the work conducted under the Bureau of Mines methane control research program during the years 1964 to 1979. This research effort was directed toward improving existing methods and developing alternative methods of reducing the explosion hazard during mining. The research was performed in three general areas: (1) basic factors that control the emission of methane into coal mines, (2) methane control during mining, and (3) methane drainage in advance of mining. Topics discussed in this bulletin include the magnitude of the methane problem; the equipment and instruments developed; the geological, chemical and physical parameters that control the movement of methane in coalbeds; the direct method of determining gas content; the estimates of gas content from adsorption data; and methane drainage, through shafts, through horizontal boreholes, through vertical boreholes, or through slant holes. Improvements in ventilation, control of methane in gob areas, and water infusion are also discussed, as is the potential use of coalbed methane as a supplement to natural gas supplies. This bulletin provides a comprehensive source of information on the accomplishments of the Bureau's methane control research program, on the technology developed, and on the direction of further research.

Jan 1, 1986

By E Breese

The Grey River dredge is the first large scale alluvial operation to be permitted under the Mining Act 1971 and the Water and Soil Conservation Act 1967. The experience of Grey River Gold MiningLimited in pursuing these statutory approvals has identified weaknesses and strengths in the present system and problems which need to be resolved. The Company has learnt lessons, which if heeded, will assist future large scale alluvial mining projects.

Jan 1, 1989

The State of Washington has a federal program that gives the Office of Surface Mining responsibility for assuring the reclamation of lands affected by coal mining. Most of Washington's coal-bearing regions lie west of the Cascade Mountains. The state's coal reserves are estimated at 1.4 billion tons, about 0.3 percent of the nation's total coal reserve. Steeply dipping. minable seams range from 2.5 to 25 feet in thickness. The occurrence of coal in Washington has been documented since the early days of its settlement; at one time, coal production played a significant role in the state's economy. During the late 1800s and early 1900s, coal was second only to lumber in Washington's industrial production. Coal production declined as other sources of energy were developed. By 1959, production was at 200,000 tons. Regulation of the coal mine operations in Washington is conducted by the Office of Surface Mining's Casper, Wyoming, Field Office and its local office in Olympia, Washington. All permit applications and abandoned mine land reclamation are completed by the OSM Western Support Center in Denver, Colorado. Inspections of mine and reclamation sites are conducted by OSM reclamation specialists located in Olympia.

Jan 1, 1992

By David V. Lewin

Heavy structures in central Cleveland, Ohio, are supported on raft foundations, driven piles, or caissons. Settlements can be predicted and structures are designed to accommodate such settlements. On one project the settlements were not provided for in the design of the structure. Soils are sands, silts, and varved clays to shale. A rift in a central area is 600 feet deep. Solutions to problems, and results, are detailed.

Jan 1, 1985

By Jean Cayouette

"In 1995, Louvicourt Mine started one of the first paste backfill operations in Canada. From 500,000 tonnes in 1995, the annual paste backfill tonnage produced reached 800,000 tonnes in 1999. The maximum throughput of the surface plant (including binders) is 3,50Ot/d with a final density of 75 to 76% solids which gives a slump of 15 to 17cm. Following the start-up of the paste backfill plant, the backfill strength performance levels were well below the pilot plant’s predictions. The introduction of ferrous slag, laboratory tests on various binder ratios with or without additives, and the desliming of the tailings enabled us to optimize the mix and operation costs. Primary and secondary stopes are filled respectively with a paste containing 4.5% and 2% binders consisting of a mixture of 20% cement and 80% ferrous slag. In certain stopes, the binder ratio may vary from 2 to 7%, but always in a ratio of 80/20. Six years after start-up, or 4.5mt of paste backfill later, this paper discusses the present operation and the major changes that have occurred over the years to optimize both the operation and the paste fill quality.INTRODUCTIONLouvicourt Mine is operated by Aur Resources Inc. which owns 30% of the shares. Its partners are Novicourt Inc. (45%, subsidiary of Noranda Inc.) and Teck Corporation (25%). The mine is located in the north-west part of Quebec, about 600 km north of Montreal and about 25 km east of Val d’Or. The mine commenced commercial production in July 1994."

Jan 1, 2002

Previous methods for measuring the flow of solids in Jnrdraulic conveying have not considered the important effects of slip velocity and particle concentration. In this paper an extension of the method proposed byShirato et al. (J. Chem. Engng. 'Japan, 1: 164-167) for determining mass flow in a vertical conduit is outlined.The present method consists of measuring' the volumetric flow of the slurry (by a magnetic flow meter for instance) and the density of the slurry in two pipe sections of different diameters. Effects of variation of slip withparticle concentration, not previously considered, are allowed.Problems involved in estimating the density of a slurry from differential pressure measurement are discussed.The major problem is the uncertainties in estimating frictional losses due to the wall in two-phase flows. The greater reliability of a more "direct" technique, such as by 'Y-ray absorption, for measuring solid concentration is emphasized.

Jan 1, 1971

By Peter Radziszewski

"Typical mining operating costs can be divided between extraction (30 % to 70 %), comminution (30 % to 50 %) and separation (5% to 20% ). Cornminition process costs, representing an important contribution to mining operating costs, can themselves be divided roughly between energy (50 %) and linerkharge wear (50 %). Developing the ability of predicting mill wear will allow a more accurate estimation of wear costs. However, total media wear in a given ball mill grinding process is a product of three recognized wear mechanisms those being abrasion, corrosion and impact. Further, the contribution to total media wear of each of these wear mechanisms has not been well established. In this paper, a overview of abrasive, corrosive and impact wear mechanisms is made from which an empirical wear prediction procedure is proposed. Further, future directions in wear prediction research is outlined. INTRODUCTIONTypical mining operating costs can be divided between extraction (30 % to 70 %), comminution (30 % to 50 %) and separation (5 % to 20 %). Comminition process costs, representing an important contribution to mining operating costs, can themselves be divided roughly between energy (50 %) and lined-charge wear (50 %). With respect to wear, world wide steel consumption as grinding media is estimated at over 600 000 tomes per annum (Malghan, 1982). As such, developing the ability of predicting mill wear will allow a more accurate estimation of wear costs.Charge media wear prediction is actually estimated using the Bond abrasion test. From Bond abrasion index tests, it is possible to determine a wear rate using the following function:"

Jan 1, 2000

By M. Perolo, A. Contini, E. Ramelli, G. Borgonovo, L. Locatelli

This paper presents the ground settlement monitoring system used during the construction of two tunnels bored by two EPB TBMs, beneath the existing and active railway embankment in Bologna (Italy). The tunnels run close to large buildings and beneath bridges and other infrastructure. Data are collected from remote total stations and from electro levels installed directly on the railway tracks. The automated monitoring system acquires and analyses data then sounds an alarm in the event that there is a problem. Alarms are sent out in case of excessive tilt or settlement. Data is provided through a dedicated web application for multiple-party access, to gather, manage and store monitoring data.

Jan 1, 2007

By J. E. Forciea, O. E. Palasvirta, L. G. Hendrickson

AH pilot and commercial plants working with Mesabi Range taconite employ wet magnetic separation. Progress is being made with a dry magnetic process, but this has not yet been applied to taconite except in the laboratory and pilot plants. Flowsheets in all five plants are similar, including multiple stages of grinding, each followed by magnetic separation, which rejects a finished tailing. The flowsheet in Fig. 1 is used in the preliminary and commercial plants of the Erie and Reserve mining companies and in Unit C of Oliver's Pilotac plant. At Erie the desliming operation is omitted. In the Reserve plants two ball mills are used with each rod mill. Pilotac uses flowsheet 2 in Unit A-B and has also tested flowsheet 3. Principal differences in the three flowsheets are the number of grinding stages and the type of roughing. The terms open-circuit roughing and closed-circuit roughing are best defined by the diagrams. Special Test Data Given in Table I: For the Erie and Reserve commercial plants, Table I reflects routine conditions. Pilotac, the experimental plant, has been run with several flowsheets, including those followed at Erie and Reserve's commercial operations. Pilotac data for these last two flowsheets are similar to commercial plant results and are not repeated in Table I; statistics are given, however, for special test conditions. using other flowsheets. when the objective was to 'to extra-grade concentrate, Variations Among Taconites: Although crude ore tributary to these plants is generally classified as taconite, there are important differences in mineralogy and fineness of dissemination.

Jan 1, 1959