Search Documents

By R. L. Castro

Block caving methods, when operated under favourable rock mass conditions, can achieve higher production rates and lower operating costs than other various existing underground mining applications. For this reason, it has been considered the preferred method for the mining of deep and large orebodies in current and future operations around the world. One of the key aspects in the design of block caves is the selection of the production level layout, which, among other parameters, is based on the gravity flow characteristics of the caved rock. This is because gravity flow has a large impact on total ore recovery and the amount of dilution in a caving operation. Today, there are a number of computer based methods which aim to emulate the gravity flow pattern of the caved rock. In this paper, the authors present the development of FlowSiman improved model of gravity flow based on the cellular automaton approach, to estimate dilution entry, mixing and ore recovery. As part of the model development, flow simulations were conducted and subsequently compared to full-scale data collected at two mine sectors operated by Codelco Chile. The results indicate that by using proper calibrated parameters, good correlations between simulated and measured grades as well as dilution entry are obtained. The potential use of the numerical tool to evaluate drawpoint spacing in terms of recovery and dilution for block/panel caving operations is also presented.

Jan 1, 2009

By Richard J. Finno

Detailed measurements made at a test section adjacent to a deep braced cut and other published data are combined to illustrate the limitations of the common methods of predicting movements associated with excavations in soft to medium clay. While past performance data can be used to estimate expected responses before construction in many cases, actual wall and soil deformations throughout construction can only be estimated using finite element procedures. Success of such analyses depends equally upon considering all aspects of construction that induce strains in adjacent soil, such as wall installation, excavation and bracing sequence, and time, and adequately modeling soil stress-strain behavior. Even when these two criteria are met, soil deformations can not be predicted adequately when strain levels exceed those that produce peak shear stress.

Jan 1, 1991

By Anthony E. Szczuka

Two facets of surface mining were studied: feasibility of using training simulators to increase productivity of haulage trucks, front-end loaders, and shovels; and improving the efficiency of dragline operations with a computer-aided analysis of dragline usage and the addition of an on-board operator display. Training costs per student were estimated based on current training practices. Training objectives were derived from task: analyses of haulage trucks, front-end loaders, and shovels. The cost effectiveness of training simulators was determined. A computer-aided analysis defined the critical performance parameters. An on-board operator's display is recommended to improve operator efficiency.

Jan 1, 1976

By Y. C. Kim, I. S. Roditis, P. K. Medhi

P. Mousset-Jones 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. Reference Kwa, B.L., and Mousset-Jones, P., 1986, "Indicator Kriging Applied to a Gold Deposit in Nevada," Proceedings, Symposium on Ore Reserve Estimation Methods, Models, and Reality, CIMM Annual Meeting, Montreal, Quebec, Canada, May, pp. 185194. 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 comparative 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. Reference Lindsey, D.S., 1987, "A Comparative Study: Probability Kriging vs. Ordinary Kriging at the Golden Sunlight Mine," MS Thesis, Department of Mining Engineering, Montana College of Mineral Science and Technology, Butte, MT, May, 81 pp.

Jan 3, 1988

By H. A. D. Kirsten

Shotcrete has become a strategic component of support in underground mines. The ductility of reinforced shotcrete makes it a safe and economic means of surface support under adverse static and dynamic loads. The ability of ductile shotcrete to sustain load at large deflections enables excavations in squeezing conditions to be stabilized and the safety in excavations subject to rock bursting, to be assured. A Shotcrete Working Group was formed to find the configurations of fibre reinforcement that would give shotcrete the same ductility as when reinforced with mesh. Beams and panels reinforced with various types and lengths of fibre were accordingly tested. A single mix design consisting of river sand, ordinary Portland cement, fly ash, condensed silica fume and gunite dust and segregation suppressant was used. Steel and polypropylene fibre varying in length from 25 to 50 mm were used in nominal contents of 5 % and 0.5% by mass respectively. Beams, panels and control specimens were shot into specially made formers. Suitable mixing procedures were developed for the different types of fibre. The test specimens were shot in a semi-dry mix process. The shotcrete was cured until tested 28 days after shooting. The fibre contents and uniaxial compressive and Brazilian tensile strengths of the shotcrete were determined from the control specimens. The beams and panels were tested in bending in specially manufactured test rigs. The beams were examined for simple supports and fixed ends. The panels were fixed in a manner that simulated underground conditions and were loaded statically under uniform pressure. The beams were loaded and the corresponding deflections measured up to failure. The panels were loaded up to mid-span deflections of 150 mm. The results are presented in the form of load-deflection graphs. The peak loads and ultimate deflections for the fixed end beams were considerably larger than for the simply supported beams for the various types of fibre considered. None of the beams tested, however, were able to sustain load at relatively constant value beyond the peak load. The panel tests showed that 40 mm and 50 mm long steel fibre and 30 mm, 40 mm and 50 mm long monofilament polypropylene fibre reinforcement gave shotcrete the same ductility as mesh.

Jan 1, 1998

By David Whalen

Mobile equipment in oil sand mining operations experience more maintenance problems than similar equipment in other surface mines, due to soft underfoot conditions. Oil sand properties are known to vary with temperature, bitumen content and previous loading cycles. One of the challenges is the widely variable underfoot pressure which supports shovels and trucks. In the case of a heavy hauler driving on in-pit roads, each tire is supported by a different ground stiffness resulting in an apparent uneven surface. Driving over uneven ground causes twist in the truck frame, which is transmitted to the dump body. Through a finite element analysis of a haul truck dump body, it was shown that slight frame twists produce localized stresses in the intersections of the floor stiffeners. These stresses are at times greater than those resulting from the maximum ore weight and are primarily responsible for cracking in these intersections. Syncrude maintains high quality haul roads, which are constructed of gravel, and makes every effort to keep the shovel pit roads as smooth as possible. This problem cannot be avoided through operational practices only and must also be accounted for in the design of haul truck bodies.

May 1, 2003

By M. C. Pietrobon

"A common problem in assessing the applicability of laboratory flotation data is determining how closely conditions during laboratory testing of the ore matches those that occur in a plant. Typical laboratory based investigations do not consider factors such as water quality, pulp temperature and the pulp chemical environment during both grinding and conditioning on laboratory flotation performance. Disregarding these important factors may seriously compromise the validity of conclusions based solely on laboratory experimental results. Furthermore, considering these factors during the flowsheet design stage in the development of new ore resources may reduce financial risk associated with building a new plant. A methodology is described here which embraces these factors in an attempt to bridge the gap between laboratory and plant. The methodology should be considered a vital first step in all laboratory based experimental programs and has implications for fundamental studies on the flotation behaviour of single minerals. This methodology increases the confidence with which findings of laboratory based studies can be transferred to the plant and highlights the effect of variables which may be accessible to manipulation in the plant.Pulp chemical parameters, such as pulp dissolved oxygen demand, pH, Eh, mineral oxidation and solution composition were manipulated in the laboratory by adjusting the duration of gas purging after grinding, the process water input and pulp temperature. A key finding was that matching of the laboratory pulp chemistry to the plant pulp chemistry was dependent upon oxidation after grinding. In turn, mineral oxidation was dependent upon the pH in grinding, water composition and the duration of oxygen purging after grinding. The methodology closely matched the dissolved oxygen demand and surface chemistry of laboratory and plant pulps."

Jan 1, 2002

The Australian mining industry is at an interesting stage in its development. Of the large number of mining companies in Australia, some are still solely domestic in their focus, others have made their first tentative forays offshore, and others are global players of significance in tile world industry.   It is not long ago that the entire industry was almost exclusively domestic in its focus. Very few companies before the early 1980s had ventured offshore, and those that did so were considered quite risque. The initial moves were made mainly by large companies who could afford to lose the funds expended in getting started in a range of offshore locations.   Almost all offshore jurisdictions were considered to be high risk compared to the safety of home - I recall the extreme difficulty I encountered in the mid 1980s in endeavouring to persuade a Board to joint venture into an attractive gold opportunity in South East Asia.   One of the problems inhibiting the offshore development of the Australian mining industry was that some mining companies had had unfortunate experiences offshore. Others had heard of those who had had unfortunate experiences offshore and, as such, 'offshore' gained a bad name and the more risk averse boards and. management of the time simply put the whole idea into the 'too hard' basket.

Jan 1, 1995

By K. K. Murray, D. G. Gelderland

"The pressure oxidation autoclave at the Goldcorp’s Red Lake Gold Mines (RLGM) was commissioned in 1991. Since commissioning, the circuit has been well maintained and its capacity increased to mechanical and gaseous oxygen limitations. With advances in available technology, opportunities to produce more sulphide concentrate and a changing business environment, an optimization project has been initiated at RLGM. A multi-phase approach has been developed to optimize both the operations and economics of the circuit. This paper describes the history and future of the autoclave circuit at RLGM.AcknowledmentsWe would like to thank the operations and maintenance staff at Red Lake Gold Mines for their support and openness of mind to enact changes to enhance the operation. We would also like to acknowledge the members of the integrated team from Red Lake maintence, metallurgy, operations and corporate technical services that did the hard work to push past the status quo in order to advance productivity.OpportunityThe Red Lake Gold Mines (RLGM) pressure oxidation (POx) circuit has been in operation for over 25 years processing the high sulphide content gold bearing minerals. Increased sulphide concentrate production from improved flotation recovery and increasing gold sulphide association at depth has led to the POx circuit becoming a throughput bottleneck. The opportunity exists to process increased tonnages of sulphide concentrates and increase gold production. In order to realize this value, it will be necessary to increase the throughput capacity of the POx circuit.BackgroundThe POx autoclave at the RLGM, commissioned in 1991, was Canada’s first gold autoclave. It was installed to replace the two-stage fluid bed roaster that was built when the Campbell mine and mill were constructed in the late Forties. The circuit was originally designed to process 12.5 t/d sulphide sulphur in about 50 t/d of Campbell flotation concentrate. Following the merger of the Campbell and Red Lake Mines in 2006, the POx circuit started processing flotation concentrate from both Campbell and Red Lake Mills. In recent years, the circuit has been processing about 18 t/d sulphide sulphur in 75-85 t/d flotation concentrate."

Jan 1, 2017

By V. F. Swanson

As part of the Bureau of Mines titanium resources examination program, samples of altered rock (saprolite) and unaltered rock from the Roseland anorthosite near Roseland, Nelson County, Va., were tested for amenability to beneficiation by flotation. A flotation technique was developed to produce bulk concentrates of ilmenite, rutile, sphene, and leucoxene. It was necessary to first float apatite using oleic acid as the collector, in an alkaline pulp with dextrine as a titanium mineral depressant. The titanium minerals could then be floated from the apatite tailing, using fluosilicic acid to depress the remaining apatite, morin to depress ferromagnesian minerals (when present), and oleic acid as the collector. A bulk titanium mineral concentrate, analyzing 66.0 percent Ti02 and 0.08 percent P205, was obtained from a sample of the unaltered rock which contained 5.45 percent TiO2 and 2.81 percent P205. Overall recovery in the concentrate was 47.1 percent of the total TiO2 in the ore. About 55 to 65 percent of the saprolite sample was clay and was removed by attrition scrubbing and decantation. The apatite prefloat procedure was applied to the saprolite sands; subsequent titanium mine: 1 flotation recovered 72.2 percent of the Ti02 in a bulk concentrate containing 65.1 percent TiO2 and 0.20 percent P205.

Jan 1, 1962

By Stanley K. Haines

This Bureau of Mines publication comprises 19 tables of data concerning domestic barite production and consumption, imports, and world production for the years 1880 to 1976. Barite is vital to the petroleum industry, with 90 percent of domestic consumption used in drilling muds. Domestic production has traditionally fallen short of consumption: in 1976, 41 percent of the 2.2 million tons consumed was imported. World production of barite increased from 269,000 tons in 1923 to 5.2 million tons in 1975 but is in danger of falling short of future demand. The compiled data provide a comprehensive base of information.

Jan 1, 1978

By Tim Hughes, Steve Gannon, Jennifer Abols

"In the past year, two very innovative gold ore processing plants have been designed, built and commissioned by Gekko Systems Pty Ltd. The first plant in Vietnam utilizes conventional crushing and ball milling followed by gravity concentration (Inline Pressure Jig (IPJ) and Falcon concentrator), flotation, intensive leaching (GFIL), the first industrial scale use of AuRIX®1001 ion exchange resin and a cyanide destruction circuit. The second plant, in Australia, uses a 3 stage crushing circuit to crush the gold ore to minus 1mm, followed by gravity concentration utilising a rougher, scavenger, cleaner circuit of IPJ’s and a Falcon concentrator. A direct smeltable gold concentrate is produced as well as a lower grade concentrate for future intensive leaching or sale. Both plants were designed and built within very tight time frames and budgetary constraints. The experience gained during the plants’ design, commissioning and operation are discussed.INTRODUCTIONGekko Systems (Gekko) is a leader in the development of innovative technology for gravity recovery and intensive cyanidation. It provides low cost and metallurgically optimal solutions for its customers. It has also led the trend away from whole ore cyanidation (CIP/CIL) towards gravity/intensive cyanidation (GIL) and gravity/flotation/intensive cyanidation (GFIL) plants. These types of plants offer low capital costs, low environmental impact and maximum return to investors (Rob J Longley et al, 2002). Key to this type of flowsheet is the application of a continuous concentrate unit, such as the InLine Pressure Jig (IPJ), which is designed to produce high gold gravity recoveries at a coarse grind (Sandy Gray, 2003). When combined with other gravity devices, and/or flotation, and intensive cyanidation, using the Gekko InLine Leach Reactor (ILR), very high overall recoveries can be achieved.In 2004, Gekko launched a new range of products called Gekko Modular Systems. The idea was to provide off the shelf, complete solutions for the separation and recovery of complex and free gold as well as the pre-concentration of diamonds. A series of modules were designed that incorporated Gekko manufactured as well as outsourced equipment. Gekko now offers modules ranging from feeding and conveying to crushing, gravity recovery, flotation, intensive cyanidation, refining and detox (see Figure 1)."

Jan 1, 2007

By S. V. Burr

"A 28-year study of cross folds leads to the conclusion that the northwest-southeast folds recognized in many areas of North America are part of a regional pattern. Detailed examination of over 650 geological maps and reports of Ontario indicates that this folding can be traced across the province. Evidence is presented that this fold pattern played an important part in determining the pattern and scale of intrusion, that its recognition in the field can aid in defining stratigraphy, folding and faulting, and that it may have played an important role in channeling hydrothermal or magmatic mineralization. IntroductionThe concept of regional cross folding in Ontario is not new. W.H. Gross (1955) discussed regional cross folds in the Archean of Northwestern Ontario, and A.M. Goodwin (1961) referred to regional cross folds in the Archean of Ontario and Quebec. However, the interpretation in this paper is new.The writer saw a cross fold for the first time, underground, at Little Long Lac Gold Mines in Geraldton, Ontario, in 1951. This recalled the ""transverse folds"" on E.R. Faribault's classical maps of Nova Scotia, published by the Geological Survey around the turn of the century; M.E. Hurst's cross fold(s) at Timmins, Ontario (Figure I); and the cross folds mapped by A.W. Jolliffe in the Yellowknife area of the Northwest Territories. All these mapped cross folds had one thing in common with the fold at Little Long Lac: A northwest-southeast axial trend. Were such cross folds of purely local extent, or might they be indicative of a widespread regional fold pattern? If so, has such folding any significance for mineral exploration or potential?By 1959, based on a study of about 1000 Canadian geological maps and reports, including 291 in Ontario, the writer reached the conclusion that cross folding trending northwest-southeast is so widespread as to constitute a pattern of folding, and that such cross folding should produce changes in plunge along pre-existing greenstone fold belts."

Jan 1, 1980

By W. F. Rochow, W. C. Burke

Numerous designs of linings and accessories, including dams, lifters, and heat exchangers, contribute greatly to kiln efficiencies. Greater conductivity is achieved with basic brick than with fireclay and high-alumina refractories, depending largely upon the use of steel plates in radial joints between adjacent brick to increase heat transfer through the lining. Refractory lifters expose all portions of the load to radiant or convective heat and raise some portions to higher temperatures by cascading the load down through the path of the hot gases.

Jan 3, 1955

By J. S. Miller

This report presents a complete coverage of results from Bureau of Mines preliminary research and the field application of explosive fracturing techniques to prepare oil shale for in situ recovery of shale oil. Small-scale surface tests were conducted to determine the feasibility of using a nitroglycerin-base explosive for creating rock fractures. Prior to underground testing, surface and near-surface tests with liquid explosives showed that explosions in sheetlike layers simulating underground fractures would propagate effectively. Successful surface experiments were conducted using layers of explosive placed between glass plates and explosive-saturated sand confined in small-diameter metal tubes. The tests in glass-plate reservoirs and metal tubes demonstrated that nitroglycerin would detonate and the explosion would propagate in cracks as thin as 1/32 inch and through distances up to 12 feet. In a shallow field test, nitroglycerin was detonated in a vertical crack in limestone and produced extensive fracturing. Explosive fracturing tests were performed in oil shale formations on seven sites near Rock Springs, Wyo. The procedures included (1) displacing and detonating nitroglycerin in natural or hydraulically induced fracture systems; (2) detonating nitroglycerin in wellbore shots; (3) displacing and detonating nitroglycerin in induced fractures followed by wellbore shots using pelletized TNT; and (4) detonating wellbore charges using pelletized TNT. The research on oil shale formations demonstrated that nitroglycerin displaced in a natural or hydraulically induced fracture would detonate, and the explosion would propagate through the explosive-filled fracture. Shooting a pattern of wells in oil shale at 100-foot depth with wellbore charges of pelletized TNT developed a satisfactory interwell fragmented zone. Tests performed on other sites at depths to 385 feet caused fragmentation of rock around the wellbore and provided interwell communication. Fourteen methods used to evaluate the extent and degree of fragmentation in the explosive fractured oil shale are discussed.

Jan 1, 1974

By F. Matanzo

[Nine wire rope terminations were pull tested and fatigue tested to destruction to measure the termination efficiency and relative fatigue life. The terminations were selected on the basis off mine site visits and the specimen were assembled in a manner similar to industrial slings. To measure a termination's sensitivity to poor workmanship, both standard and modified assembly specimen were tested. Lang and Regular construction of the 6x19 and 6x37 class wire ropes were used in diameters of 13 mm (1/2 in.), 19 mm (3/4 in.), 25 mm (1 in.), 38 mm (1 1/2 in.), and 51 mm (2 in.). In static pull tests rope class, construction, and diameter interacted with the termination to influence the efficiency of the termination. In axial fatigue tests using only the 6x19 class rope, the effect of rope construction was negligible since failure was primarily dependent on the termination type. The Swaged Socket, a termination requiring a high capacity hydraulic press, gave the best overall performance in terms of efficiency and fatigue life. The short body length of the Zinc Poured Socket (RR-S-550) was attributed with the short fatigue life of this termination. The use of thermosetting resins as a replacement for zinc was demonstrated successfully for some socket designs. The fatigue life of the termination, expressed as a percentage of the fatigue life of the wire rope, was shown to be a guide for the retirement of the wire in these applications where the wiry' rope is primarily in axial loading.]

Jan 1, 1978

Owing to the number of chemical processes now in use for the separation of metals from their ores, and the consequent employment of chemicals at the mine, it is sometimes necessary to be able to produce them on the spot. This particularlyapplies to sulphuric acid which may be required for the manufacture of chlorine and of sulphate of copper, or for the treatment of'sulphides and other purposes. It can be made from brimstone for rather less than £3 per ton, but when delivered to any distance from the works, the cost of packages and other charges would amount to more than the value of the acid.I hope therefore, that to any of the members of the Institute who may find it necessary to make sulphuric acid for their own requirements an outline of the process, and some details of the plant etc may be useful, and perhaps lead to their devising improvements, mechanical or otherwise. Though acid can be made from pyrites in Europe for about 15/- per ton, it is probable that for most metaIIurgical purposes the quantity required. and the uncertainty as to how long it would be needed, would make it advisable to spend as little as possible on plant, and so use brimstone, though more expensive, I have therefore given no details of pyrites burning, which is very fully treated by Prof, Lunge in his work on " Sulphuric Acid and Alkali."

By Jom Kresta

Fundamental changes in the Bitumen Production process at Syncrude have led to the integration of Mining and Extraction operations. Successful operation of the integrated process requires the coordinated effort of several business units. Hence, decision-making has become increasingly more complex and better tools are required. IO2 is a collaborative effort to develop a proof-of-concept prototype of a distributed decision-support system for integrated short-term production and maintenance planning with fleet allocation and dispatching. The prototype includes three main modules (planning, dispatch, and maintenance), a shared database, and a simulation module. At this stage, this prototype is used to plan and operate a simulated mining operation. It is used to demonstrate the viability of the chosen systems architecture and algorithms, as well as the information flows and interactions necessary for improving the overall performance of the integrated operation. While the problem is demonstrated using Syncrude?s site, the methodology is applicable to most integrated resource allocation problems.

May 1, 2002

By R. J. Lytle

INTRODUCTION Prior to excavation in soil and rock, it is useful to know the subsurface structure. This is important information both for safety and for equipment scheduling reasons. It is useful to know whether parts of the subsurface might be potentially troublesome or of different character than is generally thought present. By using geophysical probing, it is possible to infer the location and size of these unusual regions. The ground structure is commonly estimated from core samples taken from boreholes. These cores give a detailed knowledge of the structure in the borehole. However, knowledge of the structure exterior to the borehole can only be extrapolated from core data. By using seismic and electromagnetic cross-borehole geophysical probing, remote probing can be used to sense the region exterior to boreholes. A recent advance has significantly improved the state-of-the-art for defining the ground structure between boreholes. This new procedure utilizes large amounts of data and provides a detailed picture of the subsurface. The data processing algorithms used are similar to those in medical imaging of the human body using x-rays, a science called x-ray tomography. This imaging of the ground is called geotomography, which is a shortened acronym for geophysical tomography. Several examples of geotomography applied to imaging ground structure are presented. Our approach has been to probe the ground with electromagnetic and seismic waves. We map the region of interest with signals transmitted between multiple source and receiver pairs lowered in boreholes on opposite sides of the region (Figure 1). The received signals vary according to the transmission properties of the media

Jan 1, 1979

High Pressure Grinding Rolls Scale-Up and Experiences

Sep 13, 2010