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The concept of "classification is expanded beyond the performance of the classifying equipment to include all aspects of the fines removal system of the grinding circuit. Design and operating parameters which affect fines removal are identified and discussed, and a quantitative index for circuit fines removal effectiveness is defined. This approach lends new interpretation to certain observed phenomena, and suggests useful guidelines for circuit design and operation.

Jan 1, 1985

By N. B. Prenn

Case Studies in Open Pit Design Using Whittle 4D will be discussing the following four examples: 1) Optimization of process plant design using Whittle 4D as a sizing tool. In this case, the home office and project team had different views of the size of the final project. The home office wanted to reduce the size of the project to reduce capital expenditure, while the project team suggested a larger project. Whittle 4D was used to determine Net Present Value and Internal Rate of Return using the Whittle scheduler (FDAN) to schedule many alternatives, and calculate the NPV and return for each alternative. 2) Comparison of pit optimization methods: Lerchs-Grossman vs floating cone. Many pits are developed based on floating cone economics. A comparison of methods in one large gold mine resulted in the stripping ratio of the pit being reduced by 10% in the Whittle 4D optimization as compared to the floating cone optimization. 3) Pit optimization to determine if a new mill is justified. A large heap leach gold and silver mine needed to determine if a new mill was justified. The planning and scheduling would take several man months if completed without pit optimization and scheduling software. Whittle 4D software proved to be very effective in providing optimized pits and a mine schedule in a short time frame. 4) Pit optimization to determine how to mine and size. Open pit optimization determined where the underground operation should start, and whether the material should be processed by milling or heap leaching. One of our clients asked for help in determining where the pit should end and a new underground operation start. We used Whittle 4D to help determine where the pit should end and where to go underground. In addition the operation needed to determine how to process the material.

Jan 1, 1996

By Elif Emil-Kaya

Samarium (Sm), as one of the rare earth elements (REEs), has gained significant attention in the production of samarium- cobalt (SmCo) magnets due to their high corrosion and oxidation resistance, as well as their high-temperature stability. SmCo magnets find applications in various industries, including but not limited to national defense, aerospace, military and medical equipment. Sm and Co have been classified as critical metals due to their economic importance and supply risk. Recovering Sm from SmCo magnets is an effective method to ensure a stable supply. The present study investigates an integrated hydrometallurgical treatment and combustion process for the preparation of rare earth oxide (Sm2O3 ) powders from SmCo. Initially, SmCo powders are exposed to nitric acid, and the resulting slurry is selectively oxidized at 250 °C to obtain Sm(NO3)3 , Co2O3 and Fe2O3 . Subsequently, the selectively oxidized powders are leached with water to extract Sm. Sm2O3 powders are produced from the obtained leaching solution using an energy- and time-efficient solution combustion process. Finally, the optimal conditions for the production of Sm2O3 are identified, and the produced powder is characterized through X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) analysis.

Nov 1, 2024

By M. F. Dibble

Borehole mining, as a viable concept for recovering deep sedimentary mineral resources, historically has been long on promise but short on results. Application of the technology seems best suited for recovery of Miocene phosphate resources on the East Coast of the US. These deposits are potentially enormous in scope and underlie sections of the coastal plain and the near offshore continental shelf. The landside portion of these deposits is generally too deep to mine using conventional open pit methods. Recovery of these minerals requires development of alternative mining systems. A significant proportion of the offshore resources appear to occur at depths below the practical limits of cutter suction dredges and may even exceed the limits of bucket ladder dredges. In most cases, these deposits are covered by overburden that must he removed and redeposited before the mineral section can be mined. The depth, thickness, composition of overburden and environmental sensitivity of a particular location would greatly impact mining system selection. It is probable that dredging would not be an environmentally acceptable mining method in many of the areas underlain by this phosphate rock. In cases such as these, new processes such as borehole mining must be evolved or the resource will remain undeveloped. A borehole mining test program, using an existing prototype borehole system, successfully extracted Miocene phosphate in northeast Florida in 1984-1985. The top of the main mineral zone was 80 m (261 ft) below the surface. Based on the results of this test program. plus subsequent laboratory testing and engineering studies, a new prototype borehole mining system was designed in 1986. This design incorporated several innovations of offering potentially higher productivity and lower power consumption than was achieved with the previous test unit. Economic restraints at that tine prevented the actual construction and testing of this new design.

Jan 1, 1992

The Peruvian mining industry has seen an explosion of foreign investment since President Albert? Fujimori's government was first elected in 1990. Since then, Peru has taken some large steps toward recovery, making it the envy of most other developing countries. A measure of political stability was gained in 1992 when Shining Path leader Abimael Guzman was captured. In addition, the country has taken on a huge privatization program, rewritten its foreign investment laws and has reined in its annual inflation rate from 1,700% in 1990 to about 8% by late 1997. Small wonder then that attendance at the XXIII Peruvian Institute of Mining Engineers conference reached a record level, many of whom are employed by some of the world's largest mining companies. About 2,700 mining industry professionals from all over the world attended the week-long event, held in late September in Arequipa. That was an increase from 1995s 1,600 attendees, that meeting also held in Arequipa.

Jan 1, 1998

By William D. Leech, Peter S. Buskirk

Virginia Electric and Power Company commencing in early 1985 will begin operating the Bath County Pumped Storage hydroelectric facility, presently the largest capacity installation of its kind. Six concrete lined vertical shafts, 3 ea x 44.0 ft (13.4m) diam x 330 ft (100m) and 3 ea x 28.5 ft (8.7m) diam x 740 ft (226m), comprise a portion of the three underground power conduits. The project team decided to employ the slipform over the conventional jump form method. This selection was based on the engineer's hydraulic design and the contractor's performance requirements. This paper presents the key elements of the shafts' successful slipform operations. The contractor achieved slip rates as high as 60 ft (18m) per day; and the owner received competent permanent linings as specified by the engineer. The authors describe the team's effort to progressively improve both concrete quality and placement rate.

Jan 1, 1985

By Jeffrey P. Chanton

A specialized Pore-Fluid Array sampler (PFA) was designed to collect and store pore-fluids to monitor temporal changes of ions and gases in gas hydrate bearing sediments. We tested the hypothesis that pore-fluid chemistry records hydrate formation or decomposition events and reflects local seismic activity. The PFA is a seafloor probe that consists of an interchangeable instrument package that houses OsmoSamplers, long-term pore-fluid samplers; a specialized low-dead volume fluid coupler; and eight sample ports along a 10-meter sediment probe shaft. The PFA was deployed at Mississippi Canyon 118, a Gulf of Mexico hydrate site. A 160-day record was acquired from the overlying water (OLW) and 1.3 meters below seafloor (mbsf). Fluids were measured for dissolved chloride, sulfate, and methane concentrations and dissolved inorganic carbon and methane stable carbon and deuterium isotope ratios. Chloride and sulfate did not change significantly over time, suggesting the absence of gas hydrate formation or decomposition events. Over the temporal record, methane concentrations averaged 4 mM at 1.3 mbsf and was thermogenic in origin (d13C-CH4 = -32.4±3.4?). The timing of an anomalous 14 mM methane spike coincided with a nearby earthquake (Mw=5.8), consistent with the hypothesis that pore-fluid chemistry reflects seismic events. Keywords: Osmosampler, gas hydrate, methane, stable isotopes

Jan 1, 2008

By Philip D. Lindahl

The US Bureau of Mines (USBM) began research to improve the safety and efficiency of transporting coal from underground coal mines using a balanced air-lift hydrohoist (ALH). ALH includes a U-tube pipeline that can be installed through an existing shaft or two surface-drilled holes connecting the mine level to the surface. Bench- and pilot-scale models were tested to evaluate the feasibility of hydraulically hoisting a coal-water slurry in a riser pipe by injecting compressed air microbubbles. A prototype injector was developed that continuously compacted -50-mm (2-in.), run-of-mine coal in a screw feeder and injected a thick coal slurry into ALH. Initial production rates of 40 t/h (44 stph) through a 200-mm-(8-in.-) diam riser pipeline were achieved with a50-m- (165-ft-) high pilot-scale model. The potential productivity was expected to increase to 100 t/h (110 stph) through modification of the coal injector.

Jan 1, 1995

By C. Richard Tinsley

Investment activity in the Pacific Rim of Fire has seen a phenomenal surge from epithermal gold exploration. Individual countries are attractive because of lower up-front minerals lease costs (United States, Canada), better geological prospects (Chile, Indonesia), or cheaper equities (Australia). Since the October 1987 stock market crash, large companies are shedding minority joint venture interests to focus on core businesses. Some vertical integration is evident in Japanese coal investments in the Pacific Rim. This article does not cover the aluminum industry oligopoly, which is multinational in character. Nor does it cover the many Canada to US minerals investments. It will be interesting to see if the new US-Canadian free trade treaty will reverse that investment flow. Cross-border investments The following examples should dispel any doubts about the significance of cross-border investment in the Pacific Rim. BHP, Australia's largest public company, has invested $US 4.5 billion in the JS for the following transactions 1984 $2 billion Utah Minerals 1984 $500 million Energy Resources 1985 $745 million Monsanto Oil 1987 $400 million 50.7% Hamilton Oil 1989 $378 million Pacific Resources Placer Dome, mainly through 76% owned Placer Pacific, has the following gold mine developments in hand including the date the project began, Placer Dome's ownership, project name, its location, and capital expenditures: • 1985, 53.1 %, Kidston, Queensland, $A 139 million; • 1989, 37.9%, Big Bell, Western Australia, $A135 million; • 1989, 60.6%, Misima, Papua New Guinea, $C252 million; • 1990,45.5%, Granny Smith, Western Australia, $A95 million; • 1991, 50%, La Coipa, Chile, $US276 million; and • 1991, 25.3%, Porgera, Papua New Guinea, $C1.1 billion. Australia's Western Mining Corp. (WMC), through a foray of off-market acquisitions in late 1987, acquired con¬trol of five Canadian gold companies for a $A488-million outlay ($C452 million) as follows:

Jan 1, 1990

By William Wargo

The basic reason for lining underground cavities is to keep the cavity open during its useful life by providing adequately for the support of the surrounding rock and for the necessary degree of water tightness. This covers the entire field of support methods from the simpliest timber support to reinforced concrete in all its variations as applied to tunnels, galleries or shafts. The problem involved in the design of more efficient and economical lining systems for even bigger cavities has been magnified by increased speed of advance made possible by better blasting tecniques, improved tunneling machines and more efficient material handling. Tunnel lining today requires a disproportionate amount of time and money compared to other operations mostly due to the manuel labor involved in its installation. One solution to this problem is the developement of an entirely new concept in tunnel lining designed notoonly to overcome this bottleneck but also to open up the field for further increases in speed of advance. This new lining system acts first as a fast protective armour then becomes the concrete metal form and ends up as reinforcement sheet inside the concrete lining. This system developed and manufactured by Bernold A. G. of Switzerland since October 1968 has been installed in 25 applications in Europe under all ground conditions from stable rock to unconsolidated ground.

Jan 1, 1970

By Zhenqi Cai, Mike Lichte, Kimberly Kennedy

The Ohio River Tunnel is the first of three combined sewer overflow tunnels to be constructed under Allegheny County Sanitary Authority's Clean Water Plan. The project consists of a total of approximately 5.5 miles of 18-ft and 14-ft finished diameter, segmentally lined deep rock tunnels and smaller diameter dewater and flow connector tunnels, as well as 8 deep flow drop and access shafts varying from 25-ft to 70-ft in finished diameter and 130-ft to 170-ft in depth. This paper describes the project components and the primary engineering challenges faced during design, including tunnel alignments and shaft site optimization with tight right-of-way constraints and multiple railroad and highway crossings. Assessment of tunneling methodology as well as tunnel and shaft designs and constructability included overcoming 5-bar hydrostatic pressure, abrasive bedrock, and the selection of the appropriate support of excavation systems in high-permeability alluvial soils adjacent to the Ohio River.

Jun 23, 2024

By Alan G. Fricker

Cyprus Gold NZ Ltd will be recovering residual free cyanide in barren gold pulp by air stripping. Laboratory investigations by DSIR have indicated additional advantages by recovering the cyanide from pregnant pulp. These are a lower leach pH, a greater cyanide recovery and less carbon consumption. They have a net economic advantage of $1.20/tonne over recovery from barren pulp. The realisation of these advantages is dependent on three crucial technical aspects -optimum pH for dissolution, the absolute loss of cyanide and the stability of the aurocyanide ion. The laboratory investigations described herein address these aspects. Earlier work had indicated that the rate of dissolution of freely revolving gold discs at constant cyanide ion concentration increased with decreasing pH from 11 to 8. Attempts to repeat the work in a more controlled manner by measuring the corrosion potential and current density have, to date, not been reproducible, but do not contradict the earlier observations. Cyanide recoveries and balances were obtained on leaches at pH 10.5 and 9 at the same cyanide ion concentration -the lower pH requiring three times as much total cyanide. Unaccounted-for losses, unfortunately, exceed the accounted-for losses, making interpretation of the balances difficult. Nevertheless, it appears that the additional amount of cyanide at the lower pH of 9 may not be fully recoverable. It may not, however, prove necessary in practice to use more cyanide at a lower pH. Both the gold and silver cyanide complexes remain available for carbon adsorption, as do mercury, copper and iron. Zinc, and probably cadmium, nickel and lead, may precipitate during stripping, which is an environmental advantage.

Jan 1, 1991

By D. Lee Petersen, Charles R. Nelson, Marvin Marshak

INTRODUCTION Construction is underway on a laboratory cavern 713 m below surface at the Soudan Mine, Tower-Soudan State Park, in northeastern Minnesota. The 13.9 in wide by 11.6 m high by 71.8 in long cavern will provide a laboratory space for basic research in physics, in which experiments can be conducted with greatly reduced interference from cosmic radiation. A first generation experiment, called the Soudan 1 detector, is currently operating in a converted drift 591 in below surface at the mine. The initial phase of the Soudan 2 detector will be an 1100-metric ton unit, which will occupy approximately a 19 m length of the cavern. Control and monitoring equipment will be in a prefabricated shop office enclosure erected in the cavern. The location and planned usage for the laboratory cavern present special excavation, lining, and outfitting requirements. Temperature and humidity control, a relatively clean dust-free environment, and a long service life are required. Low cost and risk to the owner were basic requirements due to the nature of the funding. The most common type of site selected to meet these two constraints is either an operational mine or a civil works facility such as a road tunnel. There are often serious problems for such laboratories because of ongoing operations such as blasting, hauling, etc. Most of these problems do not exist for the Soudan 2 laboratory because the mine is used as a historical site with regular tours only in the summer season. The laboratory owner, the University of Minnesota, and the park owner, Minnesota Department of Natural Resources, are both public agencies of the

Jan 1, 1985

By G. L. Dollinger, W. H. Hamilton

INTRODUCTION Design and development of new products generally proceeds through a phase of initial development and discovery based on the evolution of existing arts, followed by technical innovation and development based on both pure and applied research. The development of the mechanical tunnel boring machine (TBM) has followed a similar pattern, with the first machines closely resembling continuous coal miners. In general, however, the design of TBM's to date has been more a result of evolution and discovery than of new technical innovation, even though large sums of money have been spent on research and development. In particular, the results of experimental laboratory and field investigations have had little effect on tunnel boring machine design, and the better performance of TBM's today over those of 10 or 15 years ago, is due more to increased mechanical reliability and greater operating experience, than to improvements in penetration rates and rock fracture capability. The improvements made, have been mainly by the machine and cutter manufacturers who recognize the greater efficiency and economic advantage of utilizing large single row cutters with high load capacity along with large edge spacing. Are there any improvements to be made, therefore, in TBM performance without new and dramatic technological breakthroughs? Can TBM manufacturers design greater performance into their machines by a logical extension of the present art, and by applying what has been learned in the laboratory and field? Some, for example, believe that the kerf cutting system of boring rock is at, or close to, its opti¬mum and little improvement can be made in the present TBM concept.

Jan 1, 1979

By Y. Nan

A new computer simulation model for the analysis of underground coal mine production systems in the Peoples Republic of China is presented. As a case study the model was used to analyse the railway system of an existing underground coal mine. Some results of this first application are given in this paper and some conclusions of common interest for underground rail haulage systems are discussed.

Jan 1, 1986

By Stanislaw Nawrat, Waclaw Dziurzynski

An increasing concentration of coal production, especially in the circumstances of intensive methane inflow makes the coal mine managing staff apply new techniques of safe mining. It paves also the way for scientists to develop new directions of investigations and implementation of state-of -the- art technical solutions. Simultaneously, it could be noticed that the funds assigned for expansive 'En situ ' investigation are continuously decreasing. Better and better results are reached when applying computer technique in calculations of the parameters of ventilation process. Recent theoretical and experimental investigations of air and gas (methane) flow in longwall areas with caving, combined with the implementation of methane drainage system allowed to create, a mathematical model and consequently to elaborate a computer supported numerical simulation of discussed phenomena. The mathematical model has been modified and the simulation program was prepared in such a way that the software is convenient for a user looking for an optimal solution. The paper presented the methodology of optimal choice of following parameters: - ventilation system - rate of flow through the wall. The procedure takes into consideration keeping a safe level of concentration methane in air flowing through the longwall as well as the criterion of maximum methane concentration within the methane drainage pipe line. Results of variant computer simulation regarding the longwall with caving are shown in graphs and tables.

Jan 1, 1995

I found the article most interesting and timely. I consider it imperative that mine case studies like this one are undertaken and published so that the practicing mining engineer and geologist can obtain a better idea of what is the preferred estimation and grade control technique to use, given the site-specific geology, grade distribution, etc. Mining companies, with operating gold mines, need to be encouraged to either initiate such a study in-house or support a research project by financing a graduate student at a local university. The latter method is preferable since it not only provides research support but also an excellent training opportunity for young mining engineers and geologists. Ideally, what is needed is exploration drill-hole, blasthole, and mine production data that can then be used to assess the efficiency of different estimation and grade control methods by comparing the results obtained using the drill/blasthole data with the actual production data. It is hoped that more mining companies will realize that the rewards from this kind of research greatly outweigh the sometimes perceived problem with releasing data to a university. I noticed that the authors used the blasthole data to represent the actual values, the validity of which relies heavily on the two key assumptions with regards to blasthole assays and in-pit ore-waste selection procedures. Could the authors comment in more detail on these assumptions and what criteria they used to check the validity of the assumptions? Since the article was published, have the authors had the opportunity to compare their estimates with the actual production data? It would be interesting to compare other estimation methods with OK and IK. For example, how well did the polygonal method used at the mine compare with the results given in the paper? I would like to mention that B.L. Kwa completed a similar study (Kwa and Mousset-Jones, 1986) using exploration drill-hole, blasthole, and production data from the Alligator Ridge mine in Nevada. The study compared a variety of estimation methods, including IK, and the final results are shown in Fig. 1. The IK method exhibits the smallest difference between estimated and production results and is closely followed by the indicator moving window (Ind MW) method. Reply by Y.C. Kim We do concur with Professor Mousset-Jones with respect to the merit of such case studies performed at a local university. In answer to his request for comment on the validity of the two key assumptions made in our paper, we can only say that these are reasonable assumptions that are very difficult to validate. The assumption of blasthole assays being accurate can be partially validated by a careful analysis of the nugget component of blasthole variograms. The assumption that the in-pit ore-waste selection procedure in use was an effective one can only be validated through comparison between the mine estimates of ounces of gold versus the actual recovered ounces of gold at the mill. Neither one of these two assumptions has been validated to date due to several reasons. For example, the mine went through a change in management since the study. Similarly, no compelling reasons have been presented to perform detailed variogram analysis of the blasthole data. We do, however, believe that the obtained results (i.e., indicator kriging performs better than OK in a highly skewed deposit) will remain the same in relative terms, regardless of how valid these two assumptions may be. The most recent com¬parative study by D. S. Lindsey of the Montana College of Mineral Science and Technology also shows a similar ranking between ordinary kriging versus probability kriging, which is an extended version of indicator kriging.

Jan 1, 1987

By Ryne Goodnough

INTRODUCTION The Wyodak Mine is located in the northern Powder River Basin of Wyoming and is thought to be the oldest continuously operating coal mine in the United States, having recorded yearly production since 1923. The mine has expanded over its 80-plus-year history from an underground room and pillar operation to a modem surface snip mine. Currently, the mine feeds four on-site power plants using conveyors, has a filly automated truck load-out, and ships coal by rail to nearby Wyoming power plants. Annual production of 4.8 MTFT is accomplished on a single-shift basis with 53 fill-time production, maintenance and administrative personnel. In 1990 a decision was made to modernize the coal feed system to the power plant complex with modular conveying equipment. The project involved constructing coal storage silos, overland conveyors, feeder breakers and modular conveyors to follow the mining benches. Total project cost in excess of $25 million was used to construe or commission: A 2,150-TPH 48-inch overland conveyor with horizontal curve A 2,150-TPH 48-inch plant feed conveyor 13 shuttle conveyors, each 150 feet in length 2 front-end loaders equipped with large coal buckets 2 crawler-mounted feeder breakers with compatible discharge conveyor 1 high-lift shuttle conveyor with adjustable discharge height 1 high-angle conveyor 2 4,500-ton coal silos with automated truck load- out capabilities. Conceptually, the plan was to develop 33 MTONS of reserve adjacent to the plant complex and use front-end loaders to tram ROM coal to in-pit feeder breakers. The primary crushing would reduce coal to 6-inch minus and feed through a series of shuttle conveyors to an overland supply conveyor. The overland conveyor would feed the secondary crusher, and the crushed product would be moved to any of four storage silos using conveyors. The in-pit crushing and conveying system is a unique fit for the power plants and provided many interesting challenges for the coal mine to overcome. System integration, maintenance windows, equipment availability and the like had a major role in engineering the system to a power plant complex having no emergency coal stock- pile and limited plant storage. In crediting the designers and operators, the in-pit conveying system at the Wyodak Mine has delivered coal to the power generators since 1994 with little or no downtime. ENGINEERING CONSIDERATIONS Yearly production for the mine is based on 3.5 MTPY which requires about 1,550 TPH on an 8 hour, one-shift- per-day, 5-days-per-week basis. Considering efficiencies for starting and stopping, crew transport, loader trams, and operational delays, a nominal conveyor feed rate of 2,150 TPH or 72% system utilization was used in engineering design application. This ton-per-hour basis is used to size and commission the remaining components of the in-pit system. Coal quality requirements also played a role in equipment selection. The mine reserve grades vertically and coal from Upper and Lower benches needed to be mixed in any given proportion. This required equipment to be filly variable and capable of producing all or part of the 2,150-ton-per-hour requirement. Bisecting the 80-foot- high coal face for quality required construction of a high lift module capable of reaching a single overland conveyor 40 to 50 feet above the pit floor. Designers built a high-lift, adjustable and portable module specific for this application Having two bench systems capable of each producing the required feed for the power plants required computerized control processes to control on-line production. RSLinx, RSLogix, and RSView were chosen as the communication and control software, and a Data Highway Plus serves as the communication backbone. Each of the two in-pit benches are controlled with a data center equipped with Allen Bradley 5-40 processors. This

Jan 1, 2004

By Tench C. Page

The Yarnell gold deposit is located 1.5 km (1 mile) south of Yarnell in the Weaver mining district of Yavapai County, AZ (Fig. 1). Elevations within the area of the deposit range from 1400 to 1560 m (4590 to 5120 ft). Historic production, principally from quartz veins localized along the Yarnell fault, was about 200 kt (220,000 st) at an average grade of 6.9 to 10.3 g/t (0.2 to 0.3 oz/st) gold. The federal government closed the mine in 1942 due to World War II. Norgold Resources Inc. leased the property in 1988 and joint ventured it with Asarco the same year. Asarco drilled 7822 m (25,660 ft) in 96 reverse circulation and four diamond drill holes and identified 8 t (260,000 oz) gold reserve. IBema Gold Inc. acquired Norgold in 1991 and is currently permitting the project. Production is expected to begin within the next two years

Jan 1, 1994

A portable electronic instrument was developed which will measure change of longitudinal wave velocity with change of uniaxial stress in rock columns. The instrument is a solid-state device powered by nickel-cadmium batteries. It uses a probe of two piezo-electric crystals spaced inches apart to send and receive a pulse through a stressed rock. A one-inch cathode ray oscilloscope visually displays the longitudinal wave. A reference chart is used to find the stress. Laboratory results have indicated that the average stress on a sandstone column can be found to within 35 psi. The feasibility of using this instrument to determine stresses in mine pillars is to be studied. The instrument may be used to investigate physical properties of rock.

Jan 1, 1970