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By Yum Xiaoquan, Turgut Yalcin

"A laboratory study was carried out to determine the potential role and effect of ultrasonic irradiation in the flotation of a Sudbury copper-nickel sulphide ore. The use of ultrasound was tested separately at the pulp preconditioning, collector conditioning and flotation stages. While no significant benefits were evident in the latter two cases, ultrasonic preconditioning of pulp improved the grade-recovery performance and had the prospect of reducing reagent consumption rates. Tests were conducted on both the normal and oxidized ore samples, and several variables were investigated, including ultrasound frequency (25 kHz and 45 kHz), ultrasonic power (up to 1.6 W/cm2), duration of ultrasonic treatment (up to 60 minutes), and the intensity of pulp agitation employed during the application of ultrasound. Ultrasound frequency of 25 kHz and duration of 15 minutes yielded satisfactory results. Changes were found to occur in the temperature, pH and Eh of the pulp during ultrasonic processing. The favorable effects of ultrasound observed in this study were attributed primarily to its surface cleaning capability.INTRODUCTIONThe use of ultrasound for the surface cleaning of objects is well known. Ore flotation is based essentially on the surface properties of minerals, and hence stands to benefit from ultrasonic treatment which may help restore mineral surface characteristics that might have been lost or modified through oxidation, etc. Expected outcomes of this method of treatment include improved flotation kinetics, higher recovery, better selectivity, and savings in reagent consumption, as has been demonstrated by various researchers (Aldrich and Feng 1999, Celik 1989, Ozkan 2002, Letmathe et al. 2002, Nicol et al. 1986)."

Jan 1, 2005

Changes in reductant and energy inputs which are required to adjust the slag composition in anilmenite smelter to a higher or lower FeO content are calculated. The calculated changes are based on the assumption that solidification equilibrium with the freeze lining constrains the slag composition to follow a eutectic groove in the TiO2-FeO-TiO1.5phase diagram. Calculated equilibrium conditions along the eutectic groove are presented, and form the basis of the calculations. The inputs of energy and carbon need to deviate strongly from the steady-state values to adjust the slag composition. The inputs required at any given time depend on the desired rate of change of the slag composition, and the current slag composition. The steady-state relationship of a change in energy input of 5 kWh corresponding to a 1 kg change in carbon input does also hold for the changed inputs during transient changes in FeO content. Keywords: Ilmenite smelting, freeze lining, solidification, eutectic

Jan 1, 2003

By S. Felderhof, W. S. Vaughan

"Over the years, it has been increasingly difficult for the minerals industry to raise the necessary capital for its activities. To alleviate this phenomenon, complete transparency and capital market efficiency is needed. Since a company’s mineral resources and mineral reserves base is an essential component to obtaining capital, reporting these assets must also be transparent and efficient. This must occur, however, at an international level given that mineral industry operations, and its financing, are international. To achieve this, an international committee (i.e. Australia, Canada, South Africa, the United Kingdom and Europe, and the United States) was formed and has been developing standards for the reporting of mineral resources and mineral reserves.The effectiveness of these standards, however, depends on adoption by the required regulators. Unfortunately, these standards have not been recognized by the U.S. Securities and Exchange Commission (SEC). Instead, the SEC adheres to its old standard (Industry Guide 7), making it increasingly expensive and difficult for international mining companies to obtain capital in the United States. Compounding the problem is the SEC’s influence over the current work of the International Accounting Standards Board and the International Organization Organization of Securities Commissions. These organizations are in the process of standardizing international accounting practices and international securities rules and regulations. Their current position may prevent adoption of the industry-developed mineral resources and mineral reserves standards which are internationally recognized."

Jan 1, 2005

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 Charles E. McCarthy, MORTON T. PAWEL, E. A. GEE, FRANK S. RIORDAN

Large tonnages of the magnesium silicate mineral , olivine, are known to exist in the mountains of western North Carolina and in the Puget Sound region of Washington. The North Carolina deposits alone are reputed to contain at least 230 million tons of ore averaging 45 to 49 percent of magnesium oxide In both areas the mineral is readily accessible and can be mined by the simplest methods ; one of the largest of the Washington deposits is located at tidewater .

Sep 1, 1946

By R. S. Fukuhara, M. J. Allan

"Highmont, a wholly owned subsidiary of Teck Corporation, operates a 25,000 ton/day mine and concentrator located in the Highland Valley of British Columbia. Construction of the plant commenced in the spring of 1979, and production from one grinding line began in late December 1980. The second grinding line began production in March 1980.The ore body consists of two main zones, the east and west pits, containing 134 million tons of ore, averaging 0.26% Cu and 0.27% Mo. Mineralization consists mainly of chalcopyrite (2/3), bornite (1/3), and molybdenite.The concentrator design incorporates an A-B-C grinding circuit (auto mill ball mill - crusher), followed by bulk flotation, copper-moly separation and leaching for moly concentrates. The two grinding and bulk flotation circuits are parallel and independent. Concentrate storage is provided between bulk flotation and copper¬moly separation and also ahead of molybdenite leaching. The plant design has been previously described in some detail. (""THE HIGHMONT CONCENTRATOR"" by C. V. Sibbald, CIMM Bulletin, March 1981).This paper will outline some of the problems associated with the construction, startup and early operation phases of the concentrator. The objective is to help others avoid some of the potential pitfalls by outlining those areas where problems occurred, or where things went well. Criticism of design or equipment is not intended."

Jan 1, 1982

By F. Schlosser

The extension of Montparnasse Station in Paris required the construction of supports of very high unit capacity to support a particularly rigid super-structure. The majority of the site is characterized by the existence of old limestone quarries at a depth of approximately 20 metres. These workings have been backfilled in some places, have collapsed in some places and have given rise to local subsidences in the marne layers above them. This paper addresses the steps taken by the group of companies and their consultants to evaluate the equivalent stiffnesses of the supports necessary for the design of the superstructure, and gives details of the construction techniques chosen by the foundations specialist to adapt to the particular conditions encountered on this site.

Jan 1, 1989

The AusIMM is concerned about the longer tem sustainability of the minerals sector in Australasia. Our contention is that the sustainability of the sector is at risk if we do not:   ò encourage more exploration in Australasia by removing impediments and         increasing incentives; ò fund our university and research centres appropriately to increase both our   prospectivity, and our processing efficiencies; and ò manage our human resources better.   This paper will focus on how we can better manage our human resources to assist in ensuring sustainability of the sector in Australasia .   From a production point of view:   Economic output = f (Land, Labour, Capital, Environment) where Land refers to all of the natural resources used in production. As well as land itself it includes water, forest, fisheries, oil, gas and mineral deposits. Labour refers to the skills and capabilities used by humans in the production process. Capital describes all of the manufactured aids used in the process of production1. The challenge for management is to ensure maximum efficiency and effectiveness of labour in the production process whilst maintaining sustainable development.   The 1992 Rio Summit defined sustainable development as maintaining and enhancing:   ò natural capital û defined as all natural resources, both environmental and   those of traditional economic value; ò manufactured capital û made by human kind, including produced goods,     infrastructure and built environment; ò human capital û defined as the health, well being, intellectual capabilities and   spiritual welfare of individuals; and ò social capital û defined as social relations and consultations within and   between societies, their norms and functionality2.   The minerals sector in Australasia has successfully focused on the technical aspects of each of these components of sustainable development with primary attention applied to natural capital and efficient utilisation of manufactured capital. The technical aspects of human capital and social have also been addressed through an emphasis on occupational health and safety and interaction with local communities however I suggest that, to date, insufficient emphasis has been placed on labour (human capital) to maximise economic output1.   It has become increasingly common practice to identify land as natural capital, labour as human capital and capital as physical capital. That is labour has been treated as a commodity rather than an opportunity to create a comparative advantage and this will be the greatest challenge for mine management to show leadership over the next decade of the 21st Century.   This paper will outline characteristics of the sector which are relevant to the management and utilisation of labour, outline the outcomes of recent AusIMM surveys, review the reasons for the current and future anticipated skills shortages, some innovative responses to the challenges and finally, suggestions on how mine management can show leadership.

Jan 1, 2006

By D. Whittles, S. Kingman, K. Jackson, S. Bradshaw, N. Miles

The influence of microwave energy at high electric field strength on ore strength has been investigated. Two ores of varying mineralogy were treated in both multimode and single mode microwave cavities. After treatment, any change in strength relative to untreated ore was established. It was shown that in the multimode cavity reduction in strength was related to the applied power level. Results of tests carried out in the single mode cavities showed that, for both ores, reductions in ore strength > 50% could be achieved in very short periods (<1 second). Thermal stress analysis showed that the mechanism of microwave induced failure was the development of tangential stresses at the grain boundaries. It was concluded that operation at 915 MHz with high power and short residence times gives feasible scale-up possibilities.

Jan 1, 2003

By Steven Dapp

A new hyperbolic model for generating P-Y curves is developed for use in lateral analyses of cemented soils (a ?C-F? soil with both cohesive intercept and friction angle), and includes degradation of the static loading soil response to model the effects of load cycling (repeated loading) with load cycle number. The p-y curves, for both static and cyclic loading, were derived from full-scale lateral test results conducted on a set of six drilled shafts in a loess deposit at the Kansas DOT test site. Values of the model parameters obtained from the load testing at this site are presented, as well as a discussion of the model parameters effect on the results such that the model may be rationally applied to other sites with C-F type soils. A step-by-step procedure is presented to illustrate the application of the model. Correlation of the model to the CPT cone tip resistance (qc) from CPT testing is made, as this was found to be the most reliable; However, the model is applicable to other methods, both in-situ and laboratory, of assessing the soils strength.

Jan 1, 2011

By S. J. Swart

This paper discusses the principles and application of risk assessment and management as the basis for environmental management within the mining industry. Unlike in other industries, mines are required to obtain closure certificates in terms of section12 of the Minerals Act, which should ultimately release them from further environmental responsibilities. It is emphasized that the concept of environmental risk assessment and management, when applied correctly will mean that the mine will be identifying and managing environmental issues beyond those set by current legal requirements and management strategies. The focus shifts from conventional minimum legal compliance management to management of real environmental risks. The advantage of this approach is that the perceived ?shifting of legal and management goal posts? due to changing environmental laws or management principles, will not influence or dictate the mine?s short or long-term management objectives or actions, mine closure funds can be more accurately determined and mine closure should become a relatively simple procedure. The risk assessment approach has been applied to the planning of mine closure at Iscor?s Durban Navigation Collieries (Durnacol) in Kwa-Zulu Natal and certain key risk issues such as the long-term risk of water pollution from coal discard dumps have already progressed to fully quantitative risk assessment. This paper will discuss the process, which has been followed to date, with particular emphasis on the most recent phase, namely quantitative risk assessment and management of pollution from coal discard dumps. It is believed that the approach that is being pioneered at Durnacol and which overcomes some of the more obvious deficiencies of both the EMPR and the traditional IEM process will ultimately serve as the model for all responsible mines in South Africa. It is also believed that this approach will enable the authorities to issue closure certificates with the confidence that there will be no unforeseen surprises in the years after closure.

Jan 1, 1998

By D. G. MacBeth

Most belt scales on the market are factory calibrated to minimum accuracy figures of 0.1% - 0.2% at several load points. However, if the same belt scale is not properly installed and maintained on the customers conveyor then the scale will not measure up to the claims of the manufacturer or to the requirements of the operator.

Jan 1, 1975

By Francesco Montanari, Gianni Schena

"Recent improvements in X-ray computed tomography allow investigation of objects several tens of millimetres in dimension with spatial resolutions in the order of a few microns. These improvements are made possible by coupling the micro-focus technology adopted by some of the latest cone-beam X-ray sources with an increase in the efficiency of the detectors. The micro-focus technology allows the production of clearer images at high magnification by reducing the penumbra (fuzziness) associated with larger focal spot size.Even higher resolutions can be expected in the next few years with the commercialisation of nano-focus X-ray tubes. In practice one can inspect a system of fine composite particles and analyze the different mineralogical phases in each individual particle. Computed tomography allows accurate liberation studies, e.g. providing liberation spectra or washability data in tens of minutes. However, on-line application of micro-focus computed tomography is unlikely in the foreseeable future, despite rapid development.Dual-energy (DE) radiography is another X-ray technique, which allows retrieval of the volumetric content of valuable components in two-phase particles in a fraction of a second. A digital radiograph of a single two-phase particle produces a grey level image, where the luminosity of the pixels is determined by the sum of the attenuation levels of all the structures. Thus morphological and compositional effects concur to produce the radiographic image, which does not allow retrieval of the composition of the particle, as the 3D-structure of the particle is compressed into a 2D-image, with an obvious loss of information. Thus, in principle it is not possible to discriminate between thick, comparatively penetrable, and thin, comparatively impenetrable mineralogical components."

Jan 1, 2003

By L. K. Bandyopadhyay

The expert system component of Knowledge Base System supports the analysis and interpretation phases of ventilation design with an algorithmic program used for the solution of alternate design. The paper describes the ?ES-VENT? knowledge based system developed at Central Mining Research Institute, Dhanbad, India for an on-line diagnosing of the ventilation problems using the ?IITMRULE? expert system development tool. In the ?IITMRULE? expert system tool, it has been decided to use a backward chaining reasoning process to reach the goal state i.e. the final conclusion. ES-VENT system is made of three modules: On-line Data, Diagnostics and KBS. Each module is being a collection of several programs. The paper mainly deals with the parameters affecting the ventilation of underground mines such as air-velocity, air pressure, temperature, dust, and humidity and gas contents. The graphical presentation of these parameters on the computer and the interactive part of the developed program is expected to help a ventilation officer to determine the changes in a ventilation circuit necessary to bring the mine ventilation to the desired value. Once such changes are physically effected, the display will indicate if the changes have brought the desired effect or not on ventilation. Keywords: Ventilation network, on-line data, expert system, intelligent system, knowledge base, inference engine.

Jan 1, 2002

By A. Bhattacherjee

The Shewhart [X]?and R charts are still the most popular control charts in use today for continuous monitoring of quality data. However, for these charts to function properly, the underlying assumption of normality and independence of data must be satisfied. When either independence and/or normality of data are not present, which is a common feature of ore quality data, an application of the conventional Shewhart [X]?and R charts may introduce false alarms in the analysis of the data. To address these issues, a guideline is proposed for construction of appropriate univariate and multivariate control charts for a variety of situations. A use of this guideline to a bauxite mine suggested the construction of special cause control chart for the analysis of individual variables namely, Al2O3% and SiO2%; whereas, the multivariate T2 chart based on residuals is proposed for the bivariate analysis of the variables. The case study clearly revealed that without considering the data correlation, one may be in a state of false impression about an out of control condition while using the Shewhart [X]?and R charts for univariate and the Hotelling T2chart for multivariate analysis. To compare the effectiveness of the control charts, specifically the Shewhart [X]?and the special cause control charts, a simulation study was conducted. It was found that the conventional Shewhart chart provided lower probability of coverage than the special cause control chart. It was also revealed that the quality specification of Al2O3% is met as the variation of Al2O3% is well within the specification limits; whereas, it is difficult to meet the quality specification of SiO2% on a regular basis.

Jan 1, 2002

By J. A. Cruise

With the end of the official apartheid legislation in the early 1990s, South Africa was heralded as a non-racial country. However, racial awareness has been reintroduced into the country with the Affirmative Action and Black Economic Empowerment legislation. Gender and racial transformation are the current order of the day. All organizations are required to reflect in their make-up the demographics of the population as soon as possible. Scorecard shave been drawn up to measure the rate of transformation for gender and race in organizations. The mining industry in South Africa has been in the forefront of this transformation legislation and scorecards. This paper seeks to show the effect of gender and racial transformation on mining engineering education and professionalism by analysing the changing demographics of graduating mining students at both the South African universities offering a degree in mining engineering, the professional registration of mining engineers with the Engineering Council of South Africa (ECSA), and the membership of the Southern African Institute of Mining and Metallurgy (SAIMM), the vocational institute for mining engineers. It also demonstrates the absurdity of gender and racial quotas based solely on the demographics of the current population of the country. This paper shows the degree to which mining engineering has transformed in both gender and race.

Jan 1, 2011

By R. M. Whyte

The Konkola Deep Mining Project (KDMP) seeks to exploit the deep level potential of the Konkola Deeps orebody, producing high grade copper concentrates for treatment at the Nkana Smelter and Refinery. As an alternative to smelting, Konkola Copper Mines (KCM) has examined a processing route involving pressure leaching of the Konkola concentrates at Nchanga, with the leach liquor being treated by solvent extraction and electrowinning to produce high purity copper cathode. The solvent extraction circuit would be operated to achieve a high ?delta? copper, thereby providing a strong acid raffinate which can be used in the existing Tailings Leach Plant (TLP) to treat Nchanga oxide copper materials. The main focus of the hydrometallurgical option is to capitalize upon the synergy that exists between the treatment of sulphide copper concentrates (acid producing) and oxide copper ores (acid consuming). The paper discusses the key features of a comprehensive piloting campaign carried out at Anglo American Research Laboratories, which involved the co-treatment of Konkola copper concentrates and Chingola refractory ore in a fully integrated pilot plant circuit.

Jan 1, 2001

By Derek J. Cyr

Climate has an immense impact on the properties of Athabasca oil sands and the ease or difficulty with which it is excavated and extracted. During the winter months, exposed oil sands surfaces freeze. When hydraulic and electric shovels used in the various operations in the Fort McMurray area excavate the benches, large frozen lumps are created. These lumps are either destined for a lump dump where increased costs are incurred due to rehandle, or they are sent to the primary crushers where they can cause significant downtimes by jamming the crusher. The crusher down time can sometimes be in the order of hours of lost production. Studies on data from two consecutive winters at Syncrude Canada?s North Mine show a high correlation between climate and the generation of frozen oil sands lumps. Temperature, ground cover, traffic, bench exposure time, oil sands grade and moisture content all contribute to this problem. A 1D frost penetration model was used to predict the depth of frost expected in oil sands and the corresponding likelihood of frozen oil sands lumps. To combat the challenge of frozen lump generation, a number of proactive and reactive measures can be taken: artificial snow, shallow ponds, scheduling, blasting or ripping.

May 1, 2004

By L. A. Updegraff

Before discussing the application of capacitance for the measurement of moisture content in a moving stream of coal it might be well to first give a brief description of the process and then show how it can be applied to the coal industry. A capacitor may be described as a device having two conductors separated by an insulator, the conductors hereafter being designated as a test cell or test plates and the insulator as the dielectric. Capacitance, therefore, is a measure of the ability of a capacitor to store an electrical charge. Two basic factors that affect capacitance are the dimensions of the capacitor and the dielectric constant of the insulator. Capacitor dimensions which affect its capacity are the area A of the conductive surface, and the distance d between plates. Capacitance is inversely proportional to the distance between plates and directly proportional to area A, so if capacitance is indicated as C and the dielectric constant as K the equation for capacitance would be C = AK/d. The dielectric constant can be described as the ratio of the actual capacitance of any given material to that of a vacuum, which is unity. In industrial applications the area of the plates remains constant as also does the distance between them, leaving the dielectric constant as the only variable to affect the capacitance measurement. Figure 1 is a schematic diagram of an r-f excited capacitance bridge in which a test cell is part of the circuit. This bridge consists of four capacitors in two pairs connected across an a-c voltage source. In one side of the circuit the two capacitors are fixed but in the other side they are variable, one being the rebalance capacitor operated by the servo motor and the other the test plates between which the dielectric passes. Capacity of the plates is a function of the dielectric constant of the material between them and is measured at radio frequency. Within the recording instrument is an r-f oscillator and a 60 c ps modulator. The radio frequency signal is generated by the oscillator, modulated by a 60 cps wave, and sent to the bridge. Therefore the signal entering the capacitive bridge is a radio frequency carrier with a 60 cycle envelope, If the bridge is in balance as the signal enters there would be no voltage drop and so no output by the detector. As long as the dielectric constant remains the same the bridge will stay in balance. However, any change in the dielectric constant, which in this case would be a change in moisture content, would affect the bridge. Higher moisture increases the capacity of the test cell which causes less voltage to develop across it causing imbalance of the bridge. This in turn causes a radio frequency signal to appear at the detector. Output from the detector is a 60 cycle ripple which is in proportion to the imbalance of the circuit. A 60 cycle amplifier boosts the detector signal to enough power to drive the servo motor which positions the recording pen and also rotates the variable capacitor, to which it is mechanically connected, to bring the bridge back in balance. An increase in moisture causes the servo motor to rotate in one direction, but a decrease causes imbalance in the opposite direction, and thus rotates the motor in that direction. This brings the bridge back in balance and stops the motor. The bridge shown in Figure 1 has been modified so as to provide a wide range of adjustments. Coarse and fine span adjustments located in the recording instrument are set to govern the amount of pen movement for a given change in capacitance. A measuring head unit contains coarse and fine zero adjustments for

Jan 1, 1961

By Jon Sinnreich

Ensuring the accuracy of collected data during deep foundation static load tests is of paramount importance. Typically, pile head displacements are measured relative to a purpose-built reference system, which is assumed to be fixed. This study presents a simplified error analysis of this assumption, illustrates the potential magnitude of these errors, and proposes an improved method of pile head displacement monitoring.

Jan 1, 2009