Search Documents

By Kenneth D. Winters

This Bureau of Mines report presents a Fortran IV computer program for the structural analysis of (1) protective canopies used in underground mines to protect equipment operators from roof falls and (2) rollover protective structures (ROPS) used in surface mines to protect equipment operators during vehicle overturn accidents. The program, entitled PLASTIC CANOPY, permits rapid and inexpensive calculation of the ultimate strength and deformation characteristics of a canopy for a variety of static loading conditions. The structure is modeled as a series of interconnected beam and/or plate elements. Stresses in, and displacements of, each structural element are computed and printed out at the yield strength of the canopy, at several intermediate load levels between the yield and ultimate strength of the canopy, and at the ultimate strength of the canopy. Other features of the program include prediction of buckling of a beam member under combined axial compression loading and bending, plotting of the input geometry of the structure, and plotting of the deformed shape of the loaded structure. Program description, input instructions, program listing, and four example problems are included.

Jan 1, 1979

By G Dunstan

The Ridgeway gold mine has been an enigma of the international underground hard rock community for nearly 20 years. It nearly didn’t eventuate as it was more than 500 m below a farmer’s paddock in Central New South Wales when the exploration team, looking for open pit deposits, got a sniff on its last attempt and then drilled the high-grade discovery hole. It took separate studies to find an economic mining approach. Newcrest, then a mid-tier mining company, took the venture that set it on a path of growth and built what was to become the backbone of the company for the next 15 years.The initial mining method was sublevel caving (SLC) for the upper 300 m of the orebody. The nameplate production rate for the SLC was 4 Mt/a, which was reached in June 2002 shortly after the commissioning of the materials handling system. The ultimate production rate was subsequently lifted to around 6 Mt/a through a series of innovative and efficiency initiatives. In June 2007, approval was granted for the development of a block cave (BC) operation to extract the ore reserve situated immediately below the existing SLC operations, Ridgeway Deeps. The BC was designed at approximately 6 Mt/a to match the concentrator and a systematic improvement process through the entire underground system again saw delivery rates consistently around 10 Mt/a.In line with the production rate increases, Newcrest was also committed to advancing caving knowledge through a number of targeted research and development experiments and new processes. These were primarily related to improving cave ore recovery through systematic draw marker trials, cave propagation through preconditioning techniques with associated monitoring systems. New technologies were also developed to improve the safety and efficiency of the mine through data collection, cave establishment techniques, production dispatching and autonomous loading.CITATION:Dunstan, G, 2016. The truth is stranger than fiction – the story of Ridgeway gold mine, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 19–30 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By A. M. Richardson

The significance of a massive sandstone unit in the immediate roof to longwall support weighting is well known. If the unit lies in the main roof above the zone of caving, its influence becomes more difficult to calculate using traditional methods. Much of the reserves at Cyprus Plateau's new, multi-seam Willow Creek Mine are located in the A Seam. The massive Kenilworth Sandstone is typically situated 21.3 m (70 ft) above the A Seam in the main roof and is on average 14.6-m (48-ft) thick, ranging to 29.0-m (95-ft) thick. This paper describes the application of distinct-element modeling to determination of the appropriate yield capacity for supports at Willow Creek. The modeling was determined to be useful for understanding support loading mechanisms and as an aid to engineering judgment in selecting supports.

Jan 1, 1996

The application of biogeochemical methods in mineral exploration in semi-arid to arid environments in Western Australia has been investigated in an area near Norseman.The study involved a comparison of trace element characteristics of rock, soil and plants in the vicinity of the Pioneer BB prospect, where nickel-iron sulphide mineralization occurs in a "greenstone" sequence of ultrabasic, basic and sedimentary rocks.Analyses of unweathered and partly weathered rock from diamond drill cores show the ultrabasic rock to be highly variable with respect to Ni, Cu, Co, Zn and Mn.Samples of weathered bedrock and overlying soil were analysed for total trace element contents and for the trace elements associated with secondary iron and manganese oxides. Approximately 30 per cent of the total nickel content of the weathered basic rock is associated with secondary iron and manganese oxides, compared with approximately 15 per cent in the weathered ultrabasic rock.The soil has a sufficient residual content to provide a reliable indication of the chemistry of the underlying rock. Total trace element analyses of the -89 mesh fraction show strong anomalies for nickel and copper over the mineralized zone. Important amounts of nickel, cobalt and, to a lesser extent, copper are apparently associated with secondary iron and manganese oxides in the soil.Melaleuca sheathiana (tea tree) has been used to study the relationship between soil and plant chemistry. No strong relationship between plant and rock type was observed. Analyses were made of leaves, twigs, wood, bark and roots, and all plant organs were found to have anomalous nickel and copper contents near the mineralized zone. Leaves were found to give the best contrast in the anomalous area and to show fewer erratic values than other organs. It is concluded that the uptake of trace elements by tea tree is low in the semi-arid to arid environment of Western Australia, but that analyses of the plants do reflect the presence of mineralization.

Jan 1, 1973

By Henk E. Brassinga

In Rotterdam a number of underground parking facilities have been built and are under development in the inner city, and in the suburbs. These parking facilities are located at already densely built areas. The design of these constructions has to take into account the impact of the building activities and that of the final construction on the surroundings. In this paper some examples of the different building methods of newly realized underground parking facilities are described, and problems that occurred during the construction are pointed out. In the soil conditions as present in Rotterdam the cost effectiveness of underground facilities can be improved by deepening the parking facility, and at the same time reducing the surface area so that the total parking volume remains constant. In this way the total volume of the diaphragm walls and the costs of the project is reduced.

Jan 1, 2006

By J. D. Morgan

Introduction In 1986, the US economy passed the $4 trillion mark. However, the value of domestically processed materials of mineral origin fell slightly to $240 billion. The value of metals produced from US ores was unchanged at $5.6 billion, as was recycled scrap at $4 billion, while the value of industrial minerals rose slightly to $17.9 billion. Consumer demand strongly affects mining and the US economy is relatively saturated with longlived products. Moreover, in recent years there has been a steady increase in consumer, mortgage, and federal debt, inhibiting new purchases of goods. Motor vehicles and housing are major traditional markets for mineral materials. However, the 242 million US citizens already possess 170 million licensed motor vehicles and 92 million dwelling units. In 1986, domestic motor vehicle production fell 3%, to 11.3 million units, while new housing starts rose slightly to 1.8 million units. Nearly all mineral commodities move relatively freely in world trade. As detailed in Figs. 1 and 2, in the last three decades world production of major mineral materials has greatly increased. At present, substantial excess productive capacity exists not only in the US but also in many other countries. Consequently, the US mineral industry is encountering increasing competition from other sources, along with increasing competition from newer, engineered materials. For example, US production of plas¬tics has risen from 900 kt (1 million st) in 1950 to 22.7 Mt (25 million st) in 1986 - on a volume basis significantly greater than steel. Plastics, too, are mineral-based materials, some 7% of petrochemicals going to their manufacture. 1986 saw increased calls for protection. But President Reagan, in his 1987 State of the Union Message and Economic Report to the Congress, reaffirmed adherence to a policy of free and fair trade. However, he stressed the need for increased efforts to open foreign markets to US exports and to increase competitiveness of US industry US imports of mineral-based minerals in 1986 were valued at $40 billion and exports at $24 billion. Strategic minerals As detailed in Fig. 3, imports supplied a significant proportion of total US consumption of several important materials, including many classified as "strategic and critical." There were no changes in stockpile policy during the year. Congress debated the President's 1985 proposals to reduce stocks of World War II-type materials and to focus more on high technology materials needed for the cutting edge of future military material. But no final action resulted. However, Congressional concern about apartheid in South Africa did result in increasing pressure to limit imports of South African minerals. Meanwhile, the National Critical Materials Council in the Executive Office of the President intensified its efforts to be better able to advise the President. The Defense Production Act provides authority for priorities and allocations, supply expansions, voluntary agreements, and

Jan 5, 1987

By Huw Williams

It is becoming increasingly common practice to re-use existing foundations for new projects, especially on urban sites where geotechnical conditions are congested. A knowledge of the foundation dimensions and capacity is essential for this to take place, however, as-built records are often non-existent. Non-Destructive evaluation (NDE) is now becoming an important tool in assessing old foundation properties and their potential for re-use. Pile dimensions are also critical in the power industry, when they are supporting transmission towers which need to be upgraded, and may carry additional wind loading. This paper describes the application of various NDE techniques that are available and how they can be used to determine pile length, shape and capacity in difficult site conditions, including foundations under structures.

Jan 1, 2006

By H Bibby

Initial analysis of Long Offset Time Domain Electromagnetic (LOTEM) data has traditionally been made in terms of early and late time apparent resistivities. By using more than one grounded bipole as a source, a tensor analysis technique analogous to the method used to analyse DC resistivity multiple-source bipole-dipole surveying may be formulated. We define the æinstantaneous apparent resistivity tensorÆ as the tensor that relates the total electric field vectors at each instant to the steady state (DC) uniform half space current density vectors due to each source. Instantaneous apparent resistivity tensors calculated for a 3D resistivity model suggest that profiles of LOTEM measurements across simple 3D structures can be used to create an image that reproduces the main features of the subsurface resistivity. Where measurements are distributed over an area, maps of the tensor invariants or the tensor ellipses at different times can be made into a sequence of images which provide a way of ætime slicingÆ down through the target structure.

Jan 1, 1996

The major copper orebody at Mount Isa is being extracted at a rate of four million tonnes per year. The method used requires an equivalent rate of back filling with (mainly) cemented fill. There were three major incentives for developing this mining system. The first was the prospect of high ultimate recovery of the orebody. The target is 100 per cent recovery. Also the proposed stoping layout appeared to offer significant advantages in development and production costs. Finally, extensive subsidence above the northern end of the orebody could have disturbed permanent surface installations and jeopardised a possible future open cut. The full implications of this ambitious strategy were not apparent in the early years. Now, after 12 years of production the benefits are being realised and they can be weighed against the costs. Probably the most interesting result which comes from this analysis is the significance of cutoff grades and dilution factors in balancing mining and filling rates.

Jan 1, 1980

Brief descriptions of several types of unit pulverizeI' are given and the functioning of the components that crush, carry, dry and classify the coal is considered. A distinction is drawn between pulverizers which crush particle beds and those .operating by free-crushing. The overall performance of pulverijlers is considered in terms of correlations between mill variables, coal grindability, abrasiveness, moisture and particle size. Brief discussioiJ. of the influence of pulverized fuel quality on boiler operation and of pulverizing costs concludes the paper.INTRODUCTIONModern coal pulverizers function as carriers of materials and as crushers, as dryers and as size classification machines and, thus, the unit pulverizer comprises. several components that normally function as separate apparatus. The controls of the unit pulverizer must have sufficient flexibility to accommodate rapid variations of boiler load or coal quality. Further, the machine must be robust, yet easy to maintain preferably at annual intervals-so that maintenance costs are small (for coal is a relatively cheap material). Usually, the full load of a modern pulverized-fuel fired boiler can be raised with one pulverizer off-line. All coals, from anthracites to brown coal, may be prepared as pulverized fuel (hereafter P.F.) .Each pulverizer of a direct-fired boiler has, broadly, to supply the burners with coal powdered so that about 80 per cent passes a 200 B.S. sieve and only a small proportion, less than about 10 per cent, remains on the 100 B.S. sieve. The classification processes must prevent any appreciable proportion of coarse particles in the P.F. and yet not return excessive proportions of "finished" fines. The quality of the P.F. should not vary greatly with output rates which may be anywhere between the maximum rate and one quarter ofthe maximum. The suspension of P.F. in the primary air...

Jan 1, 1957

By Robert Keyes, Charle Knowles, Glenn Kendall, Gary Fletcher

"The metal mining industry in Canada has been dramatically affected by the changes that have occurred in the world mineral market place. World economic restructuring in the post ""oil shock"" period of the mid-1970s, greatly increased competition from suppliers in the developing countries, and commodity price and currency pressures have all combined to severely test Canadian competitiveness. In the new mining world, the rate of growth of demand for metals has declined due to product downsizing, materials substitution, and a relatively slower growth of over-all world economic activity.The interplay of market and political factors is complex. Canadian metal mining companies must compete in world markets against low-cost producers in developing nations whose priorities often appear to be centred on maximizing foreign exchange earnings to foster development goals and debt repayment. Many of these countries have high levels of government intervention in their mining industries. The result is a greatly in-creased number of suppliers all vying for a share of a world demand growing at a relatively slower rate than in the past. To be able to compete under these circumstances, Canadian companies have had to undertake 'survival mode' measures and look to new ways of doing things. In order to identify the effects that the recent market and economic trends have had on the Canadian metal mining industry, a study was undertaken by Canada Employment and Immigration to assess these changes and their implications for the metal mining workforce.The Canadian Occupational Projection System (COPS)—Sector Study Group with the cooperation of the Mining Association of Canada, undertook a human resource survey to gather current employment and occupation information. This formed an important part of the Canadian Occupational Projection System Metal Mining Sector Study. This article addresses the with survey results, a C.E.I.C. worker mobility study, and trends and issues that are changing the mix of jobs and the way they are being done.Figure 1 shows metal mining employment for the period from 1974 to 1984. It provides a clear picture of the employment swings that the industry has experienced especially during the recession period of 1981 to 1983. From 1981 to 1983, employment dropped by 14 000, from 68 000 to 54 764, and then dropped to its lowest point in 1984 of 52 783. We feel that employment in the medium term will be flat with growth in gold mines being largely offset by continued workforce rationalizing in other sectors.Perhaps the key point is that equivalent levels of output have been achieved in the recent period (1981-1984) with a workforce that is 25% smaller than it was in 1974. This also raises the questions which the COPS/MAC survey and COPS mobility study sought to clarify, namely, what jobs have been cut and where have these people gone? Equally important are the questions of occupational skill level changes, and what types of jobs are declining and which ones are becoming increasingly important, as economic and technological changes have altered the mining work place."

Jan 1, 1987

By R. W. Courtney

The objective of this study is to make a critical evaluation of the magnitude and extent of electrostatic hazards in typical U.S. mining operations and to assess the adequacy of techniques, materials, and equipment for detecting and minimizing these hazards. This was accomplished with an incident/accident survey, mine visits, literature search, and engineering analysis. It was concluded that it would be desirable to (1) utilize ground fault interrupters to minimize stray current from electrical utilities, (2) decrease the current and electrostatic sensitivity of electric detonators used in areas with a high incidence of lightning strikes or troublesome stray currents, (3) institute quality control and test standards for blasting material and protective devices, (4) establish an electrostatic monitoring program for loading ANFO in plastic lined holes, and (5) establish a risk criteria for operator exposure in mines.

Jan 1, 1982

Jan 1, 1998

By Maurice A. Ponti

The D.C. Water and Sewer Authority is implementing the Anacostia River Projects component of its Long-Term CSO Control Plan, including 21 kilometers of 3.7- to 7-meter-diameter CSO near-surface diversion storage/conveyance structures and flood relief, pressurized-face, soft ground tunnels at a maximum depth of 65 meters. This paper describes a project-specific soil grouping system that is primarily based on soil characteristics for tunneling derived from tests including Atterberg limits, grain size, swelling, mineralogy, triaxial, pressure meter, and consolidation, which differentiates the project from past area tunnel projects using descriptive systems based primarily on area geology.

By Emad Iskander

The seepage forces generated around pressurized water tunnels in rock are investigated using the analysis tools of geomechanics. The theoretical background of the two-phase material behavior is explained and the equations of motion and continuity are presented. Applications on two case studies typically occurring in practice deal with the required minimum rock cover for a pressurized tunnel and the separation between two tunnels carrying different heads. The rock mass behavior as described by the Mohr-Coulomb and Hoek-Brown material models is investigated by numerical analyses and the results are compared. The effect of key material parameters on the safety factors and the associated modes of failure is discussed.

Jan 1, 2008

The mineralogy of the platinum group metals is fairly complex, and it is therefore not surprising that the different minerals have variable responses to metallurgical processes, in particular, flotation and leaching. The PLATSOL® leach process was developed to extract simultaneously base metals, gold and platinum group metals from various materials. Extensive research has indicated that most PGM?s were amenable to the PLATSOL process, with the notable exception of cooperite PtS. Further work showed that a thermal pretreatment at 500-700ºC transformed the structure of the cooperite and similar refractory minerals (Pt,Pd)S into Pt metal and Pt-Pd alloys that responded well to the PLATSOL® process. Examples are presented of the mineralogy of PGM concentrates as produced, in the residue from the PLATSOL® leach and after thermal pretreatment.

Jan 1, 2006

By Cam Thomas, Steve Bernard

Various types of blasting instrumentation can be used in the field to analyze conditions before, during and after a blast, and to indicate what changes need to be made. When different types of measurements are combined together, the blaster can end up with useful data that can pinpoint the source or sources of problems and what changes have to be made. This paper outlines two case examples where blasting instrumentation was used to overcome problems in separate quarry operations. Extensive measurements with different systems led to significantly improved blasting results.

Jan 1, 2012

Laboratory induced polarization measurements were made on representative samples of concentrated sulphide ores from three environments in New South Wales Comparisons were made with the membrane polarization exhibited by an argillaceous sandstone. The sulphide samples showed a strong polarization effect, the magmtude of whIch depended directly on the conductivity of tlIe pore electrolyte.

Jan 1, 1969

During the period 1979 thru 1982, Multi Mineral Corporation conducted a mining research program at the United States Department of the Interior's Bureau of Mines Oil Shale Mining Environmental Research Facility in the Central Piceance Creek Basin, Rio Blanco County, Colorado. The program consisted of mining, environmental and geotechnical research data and the results are described in this report.

Jan 1, 1983

Precision surface mining is increasingly occupying a significant role in open pit mining. Improvements in technology now allow continuous surface mining of material well above 140 MPa (20 300 psi) efficiently and cost effectively when compared to drilling and blasting/primary crushing methods. These include the elimination of the use explosives and primary crushing, the ability to precisely extract the ore from the waste, or separate ores of varying chemistry and mine thin seams and non-homogenous orebodies cost effectively. In addition, precision surface mining extends the useful life of a mine by extending the mine boundaries. It can expand production capacity in existing mines and is particularly cost effective in greenfield start-up mines. Precision mining techniques result in higher percentage recoveries. This paper reviews several of these techniques for the Terrain Leveler« surface excavation machine (SEM), and shows their impact. Vermeer's current approach to precision surface mining is utilisation of the T1255 Terrain Leveler SEM. Several units have been proven in round-the-clock, seven day operations throughout the world. Among other innovations are design simplicity, stability, maneuverability, rear-mounted tilting drum and top-down cutting. The impact of these items are discussed in more detail in the paper. After a detailed analysis of the importance of machine availability on overall mine performance, Vermeer has extended its equipment line to include a direct-drive option for its T1255 Terrain Leveler SEM. In addition, improvements in dust suppression are presented. While the T1255 Terrain Leveler SEM is of optimum size and cost in small and medium sized mines, Vermeer has recognised that larger mines require larger machines with increased capacities. Vermeer will prototype the T1655 Terrain Leveler SEM later this year. Specifications of this machine and up-to-date preliminary results are presented. A discussion of the role of each machine size and driving mechanisms are included. Finally, the next stage in Vermeer's providing solutions to the surface mining community will be described - a continuous loader. The impact on current mine planning is presented using a detailed computer program developed for studying the impact of loading techniques and higher production rates on mine plan optimisation.

Dec 6, 2010