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By Lynch A. J

Comminution within rod mills has been investigated by use of a matrix analysis of breakage processes. A parameter, the number of breakage stages, has been introduced and comminution within all rod mills has been expressed in terms of the number of grinding stages and a function which describes the feed rate, mill diameter, and mill speed. The effect of variation in feed rate, feed sizing analysis and mill speed on the number of breakage stages is discussed, but no general relation is proposed because more study is needed.INTRODUCTIONRod mills are normally used as the first unit of multi-unit systems for the grinding of metalliferous ores and the cost of operating rod mills may be considerable. For both economic and metallurgical reasons, it is therefore necessary that the mills should be operated efficiently and that a knowledge of the mechanism of the size reduction process within rod mills should be as complete as possible. While a qualitative assessment of the process may be of some value, a quantitative assessment gained by describing the process in mathematical terms can be of much greater use because it may also be used for design and control purposes.In this paper, an empirical mathematical model is postulated to describe the size reduction process within rod mills and it is used to analyse the effects of variations in both rates and size distributions of the feed to the mills.GRINDING CHARACTERISTICS OF ROD MILLSMyers (1953) discussed the grinding characteristics of rod mills and suggested that a pronounced screening effect, resulting in the preferential grinding of the coarser particles, occurs within the mills. This is illustrated in...

Jan 1, 1964

By Gavin Ritson, Chris Ward

"The oil sands industry is still fairly young with the first viable oil sand operation having been started in Alberta in 1960. Since then numerous modifications and improvements have been tried and implemented. The current process makes use of high velocity pumping of oil sands slurry with hot water (hydrotransport) to achieve separation of bitumen from the sand.A number of the oil sands processes have been adapted from unit operations that are used in mineral processing, such as crushing, screening, flotation, cycloning and thickening. This paper outlines a typical oil sands process flowsheet and investigates the differences and similarities in technologies and costs to other mineral processing industries. It also considers the very large throughputs required, and presents some of the difficulties and challenges currently faced by the industry as a result of high demand for oil and environmental pressures.INTRODUCTIONOil sands (also known as tar sands) deposits are found throughout the world. The Athabasca Oil Sands deposit in Aberta is the largest of these. Oil sands consist of a mixture of crude bitumen (a semi-solid form of crude oil), silica sand, clay minerals, and water. The Athabasca, Peace River and Cold Lake deposits cover 141,000 square kilometers and contain about 1.7 trillion barrels (270×109 m3) of bitumen in-place, comparable in magnitude to the world's total proven reserves of conventional oil"

Jan 1, 2009

By T. G. Carter

Support system design for tunnels and underground excavations has for many years relied heavily on the use of rock mass classification systems and the Hoek-Brown failure criterion as a means for characterizing rock mass behaviour. Because of their development, both the GSI system and the Hoek-Brown criterion admirably characterize most ?normal? rockmasses from the viewpoint of their behaviour for rock excavations. They, however, run into difficulties when applied at the two ends of the rock competence scale. This is largely because block size and incipient strength are such that rockmass behaviour in these domains tends not to be controlled by interblock shear strength but rather by material strength. At the low end of the rock competence scale (UCSi <<15 MPa and GSI generally <30) discontinuities play less of a role and rock mass strength tends to matrix strength. Similarly, at the high end of the scale (GSI >>65, mi>>15), because discontinuities are now widely spaced, block size becomes so significant that again, intact material behaviour rather than the fracturing becomes the dominant factor controlling rock mass strength. In this paper several case examples are presented to illustrate the application of the high-end (spalling) and low-end (weak ground) transition Hoek-Brown relationships proposed by Carter, Diederichs and Carvalho (2007) as a basis for better defining rockmass behaviour at the extreme ends of the rock competence scale.

Jan 1, 2008

By J. A. Meech, G. R. Baiden

"A dynamic simulation of a mine-mill complex has been conducted using networked microcomputers (IBM PC/AT and IBM PC/XT). These models allow simultaneous operation of an open pit using shovels and trucks, a primary crusher, and a secondary crushing plant. Each process transmits information via the network, linking all operations together. The effects of blasting, ore quality, equipment utilization and configuration on productivity can be studied either interactively or from a report listing at the end of each shift. Programs are menu driven leading the user through the decisions required in day to day operations. The mine-mill simulator is currently being used as a teaching tool at Queen's University to provide senior mining and mineral processing engineering students with an experience and appreciation for the operating problems across the mine-mill interface. The need for coordination and close communication between the mine and mill can be aptly demonstrated using these models. The simulator could be used to contribute to the training of operating personnel in a real mining operation. INTRODUCTIONThis paper describes a computer simulator that is capable of showing the interactions and operating strategies between a mine and a secondary crushing plant. The simulator uses two models developed at Queen's University; one for open pit mining and the second for secondary crushing. PITSIM is a dynamic shovel/truck haulage model origin2lly developed by P.D.D. Chick (1) and K.G. Fytas (2) to solve shovel/truck scheduling problems. CRUSHSOFT is a dynamic secondary crushing plant model developed by R.J. Tucker (3) and C.A. Harris (4) to study alternative operating and control strategies in a crushing plant."

Jan 1, 1987

Energy Dissipation in Long-Distance Slurry Pipelines

Sep 13, 2010

By Turker L

The leaching of Tellness (Norway) ilmenite concentrate in hydrochloric acid and mixed aqueous HCl-alcohol solutions at boiling temperatures was investigated. It was found that the alcohols methanol, ethanol and ethylene glycol all substantially increased the leach rate and in the case of methanol and ethanol this was achieved at lower boiling temperatures compared with aqueous HC.

Jan 1, 1986

Except for uranium search, conventional oil well logging techniques are relatively little-used in mining exploration. The main reasons for this are cost and an apparent lack of awareness of the potential use of the methods in the search for ore. However, relatively inexpensive portable units are currently available for performing the simpler electrical and radiometric logs in diamond drill holes.The emphasis in oil exploration logging programmes is largely on the estimation of porosity. In most mineral work, however, porosity is not very significant, and factors such as mineral conductivity and radioactivity assume an important role.The Bureau of Mineral Resources (BMR) during a programme to explore for uranium and associated base metals in the area east of Rum Jungle, N.T., carried out electrical and radiometric logging of diamond drill holes as a routine part of their investigations. Case histories are described in which the logs were used to aid in defining stratigraphic sequences and transgressive structures in base-metal prospects. Some surface geophysicalanomalies were explained by the logging: induced polarization and electromagnetic anomalies were related to black slate; and self-potential anomalies were related to oxidation of pyrite black slate, or apparent electrokineticeffects in the black slate. The logs provided an objective appraisal of the rock units penetrated and thereby helped to differentiate lithologies.Borehole logging, including newer techniques such as downhole analysis, could be done in geological and geophysical investigations in other areas for a relatively small cost with a considerable potential gain of information.

Jan 1, 1978

By Werner Burger

The last decade has witnessed a rapid development and application of slurry and EPB type tunnel boring machines. Both soft ground types are able to excavate tunnels in unstable ground conditions below the water table with positive face support. The most significant component of the excavation process is the cutterhead and tool con-figuration were the excavation and face support meets the geological challenge. The TBM downstream processes cannot take place unless the cutterhead and tools effectively do their job. This paper will review the current state of the art design for both slurry and EPB cutterheads and highlight both common as well as geological specific design features.

Jan 1, 2007

By A. Sandberg, M. Nzotta, Du Sichen, N. N. Tripathi, K. Beskow

The present study was carried out to investigate the impact of slag refractory lining reactions on the formation of inclusions during ladle treatment of steel. The experiments were conducted on an industrial scale in the ladle at Uddeholm Tooling AB in Hagfors, Sweden. The inclusion chemistry and population during ladle treatment were studied along with the composition of the ladle glaze, taken from the ladle lining. The inclusions in the steel were classified into four groups according to the Swedish standard SS 111116. SEM/EDS analyses were carried out to identify the phases present in both the inclusions and the ladle glaze. The number of inclusions in the steel before deoxidation was found to increase with the ladle age, i.e. the number of times the ladle had been in use. A similar increase was also found after vacuum degassing and before casting. A great portion of inclusions before casting was found to be supplied by ladle glaze. This observation was further confirmed and explained by thermodynamic analysis. The present results show that ladle glaze is a major source of inclusions in the ladle at Uddeholm Tooling. Keywords: Slag/ refractory/ lining?reactions, ladle glaze, inclusions, inclusion chemistry, ladle treatment

Jan 1, 2004

Evaluation of Grinding Medium Wear in Stirred Mills The standard fine grinding machines in the minerals industry are stirred mills whose performance largely depends on the competency of the grinding medium. Medium wear in stirred mills is one of the key parameters for medium selection. A wear evaluation methodology is developed and applied in this paper to measure the wear rate of river sand using a laboratory batch stirred mill. The procedure is demonstrated by testing the sand medium in a 0.55 kW batch stirred media detritor (SMD). The sand wear rate determined in the laboratory batch mill is successfully scaled up to that determined on a full-scale Metso 355 kW SMD mill.

Sep 13, 2010

By A. Drouin, D. Lemieux, C. Chouinard

"A gold bearing pyrite concentrate was treated at the demonstration scale (15 t/d) for the extraction of gold using a cyanide-free process. The pyrite was depressed in the flotation circuit in order to promote the flotation of copper and to achieve a sufficient copper grade to meet the copper smelter criteria. However, the recoveries of copper were 80% and only about 50% for the gold was found in the copper concentrate. The balance of the gold (50%) and copper (20%) contained in the pyrite concentrate as a reject from an overall flotation circuit. The gold grade in the pyrite concentrate is 5.40 g Au/t and copper about 0.77%. About 170 tons of pyrite concentrate were processed in the DST demonstration plant. The concentrate was first oxidized using a fluid bed to produce a calcine. Copper was then extracted as copper sulphate using diluted sulphuric acid. The residual solid was submitted to the DST chlorination process for gold extraction. Thereafter, the gold was recovered from the pregnant brine by precipitation over silica using DST proprietary process. The maximum gold recovery by chlorination was 90%. The average gold recovery by cyanidation of these calcines was 71%.IntroductionDundee Sustainable Technologies (“DST”) has developed a chlorination process as an alternative to the conventional cyanidation process for the extraction of precious metals from ores or concentrates. The technology offers viable and efficient gold recoveries and the ability to handle refractory ores and contaminated material (As, Hg, etc..). The process was successfully demonstrated on hundreds of samples provided by various mines, exploration and development projects and has evolved from laboratory experiment to demonstration at an industrial scale.DST’s chlorination process operates in a closed loop circuit, which implies that no liquid effluents are generated. The chemistry and process design allows precious metal deposits containing base metals to be treated viably. The tailings from the process are inert and non-toxic, sulphide depleted and thus non-acid generating. The efficiency of the process has demonstrated excellent gold recoveries within a fraction of the time needed for cyanidation to obtain similar results. The company completed in 2015 the construction of the first industrial demonstration plant operating with the DST technology. The plant has a capacity of 15 tons per day of mineral concentrate, and the ability to extract gold and silver utilizing DST chlorination technology.DST has tested its chlorination technology at demonstration scale on the refractory pyrite concentrate containing 5.40 g Au/t and 0.8 %copper. This auriferous pyrite concentrate, was by-product of copper concentrate respecting the copper smelter norms, is produced in a country where cyanide is prohibited and refractory to cyanidation. The pyrite concentrate was initially processed successfully (gold recoveries: > 90%) by the DST technology at laboratory (2011: 20 kg) and pilot (2014: 5 tons) scales to extract gold. About 170 tons of this pyrite concentrate were processed in the DST demonstration plant located in Thetford Mines."

Jan 1, 2017

By Robert Hopler

DESCENT INTO A COAL MINE From “The Playbook of Metals, including Personal Narratives of Visits to Coal, Lead, Copper, and Tin Mines,” by John Henry Pepper. Published by Routledge, Wa rne, and Routledge, London, 1862 ENGINEERING NEWS New Yor k January 22, 1903 THE BEGINNING OF THE END OF DYNAMITE. In another part of this issue we have reported the results of some test results made upon one of the safety powders. It will pay every c o n t r a c t o r, miner, or user of explosives in any form to carefully re a d the article re f e r red to. Dynamite has done a gre a t work in the service of man, as did black powder before it; but its i n h e rent dangers are admitted by all and are proved by the long list of deaths and injuries, and destruction to property which annually occur through its use. Why should we continue to use an explosive that annually kills and maims hund reds of men, when others are available which are equally powerful, no more expensive and far less liable to accidental discharg e ? Dynamite when first manufacture d is pure and comparatively safe; but most unfortunately it does not always stay pure; it “rots,” and then it is exceedingly dangerous. More than this, the explosive part of dynamite is a liquid, nitro - g l y c e rine, which is absorbed or soaked up by sawdust, wood pulp or the like. So long as this liquid nitro - glycerine remains pure and remains “soaked up,” or absorbed t h e re is little danger. It has been found, however, that the nitro - g l y cerine leaks under certain conditions. During thawing it fre q u e n t l y leaks out of the stick, or if it becomes wet the water causes the n i t ro-glycerine to leak out. In either case free liquid nitro - g l y c e r i n e escapes, and in that free state it may be exploded by any very slight shock. Nor is this all, if a stick of frozen dynamite be bro k e n a c ross it has been found by tests that the frozen nitro - g l y c e r i n e w h e re thus broken is very sensitive to shocks afterward .

Jan 1, 2004

By S. A. Osterberg, J. L. Breckenridge, R. S. Popielak

Multidisciplinary investigations were completed to prove the availability of water resources for the proposed San Cristóbal silver-lead-zinc mine in the arid Altiplano of Bolivia. Surface water resources are scarce, of poor quality, and unsuitable for development. Therefore, hydrogeological reconnaissance targeted alluvial aquifers for development. Follow-up resistivity, refraction, and water quality assessments were used to prioritize areas with prolific production potential. Pumping tests and regional water balance analysis indicate an alluvial aquifer can sustain the required approximately 40 000 m3 per day production for the life of the mine and predict no significant negative environmental effects on local groundwater users and the environment.

Jan 1, 2002

By Rudolf E. Greuer

This report contains a theoretical study on the usefulness of fighting mine fires with inert gases. Four introductory chapters review the role of fires in the mining industry; the conventional fire fighting techniques, the influence of inert gases on the burning of gases and solids, and the well established inert gas fire extinguishing systems for buildings and machinery. A large chapter describes the use which inert gas has found so far for fighting mine fires in major mining countries. More applications have occurred than generally expected and the inert gas method has in the last years become routine in Czechoslovakia and the USSR. This chapter is based on an evaluation of the extensive literature as well as on personal information obtained from leading experts.

Jan 1, 2012

Since 2001, the Hybrid Stress Blast Model (HSBM) project members have developed a software suite to model the complete blasting process from non-ideal detonation to muck pile formation. To preserve the physics and improve solution time, the breakage engine uses a combination of analytical models and 2D axisym-metric finite differences to model near-field crushing, coupled to 3D discrete lattice fracturing and distinct element numerical methods to model throw and muck pile development. The model has been validated by comparison with laboratory and field tests in kimberlite. Multiple blasthole simulations are used to demonstrate how changes to blasting parameters can influence downstream efficiencies. Case studies of wall control blasting show that the presplit design must balance the two opposing effects of increased damage with increased charge and decreasing attenuation of the seismic waves with decreasing charge. Modelling of decoupled explosives needs further development. Reducing the charge towards the back of the trim blast results in a much more significant decrease in back damage than altering the timing. The model demonstrates how separation along the weaker planes in a jointed rock can coarsen the fragmentation, leading to inefficient beneficiation, and extends the damage to a distance of at least twice the burden behind from the blasthole, severely compromising the wall stability.

Jan 1, 2012

By Willie M. NeSmith

Conventional augered, cast-in-place (ACIP) piles were introduced into the New York City area as a result of the damage to existing structures caused by pile driving operations. ACIP piles are often specified where deep foundations are to be installed adjacent to transit facilities, sensitive underground utilities or in close proximity to existing structures. However, loss-of-ground issues associated with the installation of ACIP piles have prevented the wide-scale use of these systems. Beginning in 2002, Berkel & Company Contractors, Inc. began using its augered, cast-in-place displacement (ACIPD) system in the New York City area. Like conventional ACIP piles, this system produces almost no vibration. Also, as almost no material is brought to the surface, there is no opportunity for loss of ground. This paper presents a description of Berkel&apos;s displacement pile system and a brief discussion of six projects in the New York City area that have been executed with this system over the past two years.

Jan 1, 2004

By Doris M. Hyde

The 350,000-barrel-per-day Bahamas Oil Refining Co remained closed throughout 1986. Financially troubled Charter Oil Co., joint owner of the refinery with Chevron Oil Bahamas Ltd., agreed in principle to have Chevron assume full ownership in return for canceling debts owed Chevron. Finalization of the agreement was pending at yearend. Burmah Oil Ltd. took more than a $30 million loss on the sale of its interest in South Riding Point Grand Bahama Transshipment Terminal to South Riding Point Terminal Holding Ltd.

Jan 1, 1988

By Ramdane Bahar

"Abstract The design foundations can be performed using Menard pressuremeter rules that require a limit pressure and a pressuremeter modulus. In recent years, another trend of interpretation of this test is appeared. It consists of identifying the rheological soil parameters using analytical or numerical methods and then used to evaluate the bearing capacity and settlement of soil foundations using numerical software. This paper deals with the bearing capacity and settlement predictions of bored piles using two approaches. The first one is the method called ""Pressident"" which is a numerical program developed to analyse pressuremeter tests taking into account the Duncan and Chang model. The second approach is the method developed by Bahar and Olivari based on the generalised elastoplastic Prager’s model with the Von Mises criterion which is suitable to describe the behaviour of saturated clays under undrained conditions. The pressuremeter data, collected on various research and consulting projects are used to explore the relationship between limit pressure and undrained shear strength obtained by the two methods. Numerical calculations, by FLAC2D software taking into account the rheological parameters derived from these two methods, are performed in order to predict the behaviour of a single bored pile subjected to an axial vertical load. The predictions are comparedto the measured data.IntroductionThe Menard Pressuremeter test has been used extensively to measure in situ soil properties and for the design deep foundations in Algeria. These tests are an useful and economical way for obtaining reliable in situ properties of soils and provide the measurement of in situ stress-strain response of soils. From this test, the design foundations can be performed using pressuremeter rules that require a limit pressure, pl, and a pressuremeter modulus, EM. These two parameters are derived from the pressuremeter curve or deduced from existing correlations with undrained cohesion and internal angle friction (Ménard, 1957; Amar and Jézéquel, 1972), and are used to evaluate the bearing capacity of soil foundations and the expected settlements. But, they can also help to identify usual soil parameters required by simple constitutive models for soils in numerical calculations."

Jan 1, 2014

By Shazad Hosein, William Birch, Douglas A. Anderson

This paper will present the results of tests of a new method for assessing explosive performance using wavelet transform analysis of standard blast seismograms. The theoretical background of the method was presented at an earlier ISEE conference.

Jan 1, 2015

By Gordon DM

Tyres account for 25-30 per cent of the operating costs of large capacity haul units as used in open-cut mines.Tyre operating costs can be substantially reduced and often contained in real terms by applying knowledge that is now available.This paper describes certain specific advances in tyre management, namely batching, bias adjustment, cumulative plotting and the so-called &quot;pressure-temperature&quot; system of tyre pressure control, originated on the Mt Newman Mining Company&apos;s Newman minesite, and discusses the contribution that each has made to improving tyre management and reducing costs.

Jan 1, 1983