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By Willis H. Carrier

Particular interest in the ventilation of deep mines, especially those in South Africa, has been created by a very complete system of cooling of the world's deepest mine, the Turf shaft of the Robinson Deep in Johannesburg. The writer visited this mine in January, 1936, and again in 1937. During these visits and subsequently, a considerable part of the theory involved in rock cooling in tunnels was developed and this has been checked by practical observations of the rates of rock cooling made within mines. The purpose of this paper is to set forth the method of attack of the mine problem. The cooling or air conditioning of mines by the use of mechanical refrigeration was not wholly newl-5 when the Robinson Deep installation was made. The first mine to be cooled was the Morro Velho mine, in Brazil. The first installation in this mine was put into operation in December 1920, the refrigerant being ammonia.5 The surface cooling gave considerable benefit but it proved inadequate as greater depths were reached, therefore in 1929 two centrifugal refrigerating machines were installed at the 6000-ft. level. These were used in conjunction with the surface cooling system to furnish additional cooling at the lower levels. This later installation used Carrene as a refrigerant. This nonflammable refrigerant, having a boiling point of 104" at sea level, insured reasonable safety, since all parts of the machine operated at subatmospheric pressure. Very favorable reports have been received on the effectiveness of this installation, but no recent data are available. An interesting feature of that plant is that the condenser water is cooled by spraying it into the exhaust air from the mine at the base of the ventilation upcast, which permits the water to be cooled within a few degrees of the wet-bulb temperature of the air entering the upcast, and the only water that has to be supplied for condensing purposes is that lost by evaporation, or about 0.5 per cent of the volume circulating through the condenser. This plan affords an ideal means for the removal of the heat load from the refrigerating system, and of course also from the mine itself. In many mines, however, especially those in South Africa, there is no

Jan 1, 1940

By Charles Zdazinsky

Many blasting applications in the mining industry demand that the hard rock being blasted remains structurally competent. For example, pre-splitting is a common technique to reduce fracturing, and operators of dimension stone quarries use this blasting method to eliminate overbreak. When pre-split design parameters are not applied correctly, there will be a redistribution of stresses within the rock, resulting in Blast Induced Rock Damage (BID). Advances in geophysical technology are enabling blast technicians to monitor BID and then use the results to correctly design their blasts.

Jan 1, 2011

By Gust Van Lysebetten, Monika de Vos

The objectives of monitoring geotechnical structures can be very diverse, including optimisation of the design, quality control, long term performance assessment, and approval of innovative execution techniques. In this context, new measurement techniques, based on optical fibres, offer the possibility of accurate strain and temperature monitoring with very small sensors and limited numbers of cables. This paper briefly presents optical fibre sensing techniques and illustrates their application to geotechnical structures by means of some projects, carried out by the Belgian Building Research Institute (BBRI).

May 1, 2022

"In mining operations, it is widely accepted that strategies to drive operational goals must revolve around improving plant availability, reliability and process efficiency. In this paper, an integrated solution framework for reducing process variability, increasing process efficiencies and maximizing plant availability and reliability is discussed within the context of a typical milling circuit. The framework exploits a real-time analysis “gap” evident in production operations that prevents timeous identification of equipment and process failures. This is achieved by leveraging predictive analytics for equipment health monitoring, control loop monitoring and advanced regulatory control solutions towards enhanced process performance, improved asset management and regulatory compliance. The framework provides for early and actionable warnings on equipment and process degradation using real-time operational data.INTRODUCTION The changing landscape of gold mining and processing presents many challenges that threaten sustainability of existing (marginal) operations as well as deter investment in new projects. As existing “shallow” ore resources become depleted, mining operations are increasingly treating low-grade ores with complex and randomly variable mineralogical characteristics. For example, in South Africa, historically one of the major gold producers, the average grade of ore treated has been decreasing from averages above 4.5 – 5 g/t to current grades averaging less than 3 g/t within a decade (Chamber of Mines, 2012). Moreover, lower tonnages are being treated as a result of the narrowing of the available resource base. Also, the regulatory framework has tightened over the years due to heightened concerns on the safety, health and environmental impacts of mining and related activities."

Jan 1, 2014

By G. B. Sazuyer

DEVELOPMENTS respecting beryllium during the past year have been sufficient to center attention on it as likely to be the most important of any of the chemical elements that have recently found a place for themselves in technical industry. This importance is only potential, however, largely because adequate supplies of beryllium ore will be necessary. The beryllium industry will be only as great as the mines which support it. To find and develop large mines will be the problem. Chief of the immediate commercial developments in the United States is beryllium-copper and its espousal by Anaconda and Riverside even at present high prices. According to the pamphlets of these companies, it ap¬pears that beryllium is to copper nearly what carbon is to iron. When one considers that the tensile strength of pure copper is about 33,000 lb. per sq. in., but that the addition of 1.5 to 2.5 per cent of beryllium produces a heat-treatable alloy with a maximum tensile strength of 220,000 lb. or over, the analogy to carbon and iron is made strikingly, clear. Striking among the properties of beryllium-copper is its resistance to fatigue, claimed to be equal or superior to that of spring steel. It needs little imagination to foresee a great industry for this alloy alone.

Jan 1, 1934

By Theodore H. Boggs

The battle of the gold standard is not limited to one country alone, or even to a single group of countries. It is being waged merrily in many important commercial and industrial quarters. Though it is not always a practical issue calling for immediate attention, it is none the less, quite widely, engaging the thought of bankers and other students of finance. The controversy arises, in the last analysis, because of the desire of men to secure a stable currency. There are two ways of restoring a reasonably stable currency system: (1) the re-establishment of the gold standard, or (2) the deliberate and artificial management of a paper currency. Both systems are well known. The gold standard was in use prior to the war in the principal commercial countries. A currency of inconvertible paper has been at times employed in the past in various countries; for example in Britain from 1797 to 1821, and in the United States from 1862 to 1879. The gold standard, as all are aware, implies the selection of gold as the standard of value. The unit of value is a fixed weight of gold and, so long as the standard remains unimpaired, all other means of payment are maintained at a parity with standard gold coins. And gold coins alone constitute the standard money, inasmuch as their value as bullion equals their value as coins. Under the gold standard this would not be true of any other form of money, although all other varieties of money, including bank notes, government notes and silver coins would be freely convertible into gold money. Strictly speaking, the gold standard also implies that the gold money in turn shall itself be freely convertible, through melting, into gold bullion and freely exportable.

Jan 1, 1925

By Ehsan Moosavi, Kamyar Tolouei, Mehran Gholinejad

The literature defines rockbursts in slightly different ways based on their generation mechanisms, field phenomena, and degree of damage, but in a way that is almost consistent. Generally, a rockburst refers to seismic events that mainly happen in underground excavations, for purposes such as underground mining, road and railway tunnels, nuclear power, etc., and that are followed by the collapse and outburst of rocks. Long-term rockburst prediction can be abstracted as a classification problem mathematically, in which we can introduce deep learning to solve it. Further, using deep learning in rockburst prediction can overcome drawbacks such as subjectivity and inconsistency brought from previous traditional approaches. A rockburst data-set, was employed to evaluate the current method for predicting rockburst grade, and the good results of overall success rate were obtained. The results indicated that the proposed algorithms can speed up parameter optimization search, the proposed method is robust model and might hold a high potential to become a useful tool in rockburst prediction research.

Apr 26, 2022

By C. Schmidt, M. Kohnk, C. Siemers, J. Kiese

The application of conventional titanium alloys is limited to 550°C due to their poor oxidation resistance. In addition, severe grain growth is observed in single-phase titanium alloys in long-term runs at elevated temperature leading to a degradation of their mechanical properties. In exhaust applications in automotive or aerospace engineering, products are often manufactured by cold-deformation like deep-drawing or rolling which is normally difficult in oxidation-resistant titanium alloys due to the presence of titanium-silicides. Therefore, in the current study, titanium alloys based on CP Titanium Grade 1S (soft grade) were developed showing (1) improved oxidation resistance due to a concerted addition of silicon, iron and niobium, (2) microstructure stability by the precipitation of hafnium-silicides mainly on the grain boundaries and (3) good cold-deformation properties. The industrial production route was developed so that the new class of Ti-Si-Fe-Nb-Hf-alloys is now ready for application in exhaust systems of planes or cars at minimum 800°C.

Jan 1, 2015

By F. Henríquez

Traditionally, the implementation of an automated control for a ball mill has been a challenging one. First, it must be capable of processing a variable SAG mill feed while at the same time avoiding to become a process bottle neck. Second thing is, it must deliver an adequate quality product (P80) to the process downstream. Then the ball mill itself and its associated classification equipment has problems of its own: it must maintain adequate control of cyclone?s pressure, density and pump-box level with often, less manipulated variables than needed, namely, variable pump speed and the opening/closing of cyclones. Thus, it becomes a non-linear multi-variable type of process with often too multiple and contradictory control objectives to satisfy simultaneously. On top of that, to extend cyclones availability and yet, maintaining their performance, is must both for process and maintenance purposes. Trying to solve the puzzle, Minera Los Pelambres implemented a novel and successful combination of MPC (Multivariable Predictive Control) and advanced control in two of its newest ball mills, reducing considerably process variability while maintaining high throughput and keeping the process well within constraints limits. Because of their differences in processing capacity, size and topology, two different stabilizing-control strategies were developed, tested and tuned. Hence, for both control approaches their implementation process, main results, areas of applicability, limitations and their key performance indicators are discussed further. This paper also discusses the need of such advance control technologies in the mining industry, including the impact of these technologies on best practices for their implementation, operation and long term sustainability

Sep 1, 2012

By K. V. Raj, A. T. Weakley, A. L. Miller, D. A. Parks

Diesel particulate matter (DPM) is a common and well-known health hazard in the mining environment. The current approved method for monitoring both the organic and elemental carbon (OC, EC) portions of DPM is a laboratory method with a turnaround time of approximately one week. In order to evaluate exposure levels and take corrective action before overexposures occur, a portable real-time device capable of quantifying both OC and EC is needed. To that end, researchers from the National Institute for Occupational Safety and Health (NIOSH) designed and tested a device based on narrow bandpass optical filters that is capable of targeting infrared absorbance bands associated with DPM. Five optical bandpass filters were chosen based on previous work quantifying DPM using Fourier-transform infrared (FT-IR) spectrometry. The resulting device, referred to as a filtometer, is optimized to exclusively determine DPM and could serve as a cost-effective, field-portable alternative to laboratory-grade FT-IR analysis and instrumentation. The performance of the filtometer was investigated by calibrating FT-IR data from DPM (dependent variable) to the filtometer spectra (predictor variables) using a partial leastsquares (PLS) and ordinary least squares (OLS) approach. The square of the correlation coefficient and root-mean-square error of cross validation m

Mar 2, 2022

By M J. Noy

The automated measurement of rock fragmentation particle size distribution in the muck during muck excavation has been developing over the last 16 years. The introduction of stereo camera imaging of the muck has provided improved automated particle segmentation for image-based measurement algorithms. Recently, a new vision system processing algorithm has been developed. The inclusion of 2D texture in the analysis has provided a significant improvement in the definition of the finer size fractions, which has resulted in the automated analysis no longer requiring calibration.The previous stereo vision system algorithm required analysis calibration to account for poor ‘small particle’ definition in the 3D surface profile. This was because of the depth perception limitations of the stereo camera system at greater than 8 m. The new algorithm has been implemented on a number of shovel-installed vision systems, and the algorithm’s performance in automated analysis has been assessed against a diligent manual analysis of the same fragmentation images. The new algorithm provides improved distribution resolution and accuracy.CITATION:Noy, M J, 2015. Evaluation of a new vision system algorithm for automated fragmentation measurement from a shovel, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 721–726 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By George Comstock

Results are given of scleroscope and Brinell tests on specimens of cast 10-per cent. aluminum bronze, quenched and reheated at various low temperatures. The scleroscope was not found as reliable as the Brinell machine for measuring the hardness, for the size of the piece tested seemed to affect the scleroscope results. The maximum hardness was obtained by quenching and reheating to between 315° and 370° C. Softening was produced by reheating above 370° or 400° C. A series of polished and etched microsections showed a more reddish color in those that had been reheated above 400° C., and a change in microstructure above 500° C. IT HAS been known for many years that the alloy containing 90 per cent. copper and 10 per cent. aluminum can be hardened, like steel, by quenching from a suitable temperature, and that the hardened alloy can be softened again by annealing or drawing the temper. It does not seem to be generally appreciated, however, that the effect of the first slight reheating after quenching is actually increased hardness, the softening effect not taking place until a certain temperature of "drawing" has been exceeded. This paper gives the results of a few experiments on various specimens of cast 10-per cent. aluminum bronze, quenched for maximum hardness, and subsequently annealed at different temperatures. The hardness measurements were made with both a scleroscope and a standard Swedish Brinell machine; some peculiarities of the scleroscope test on this material are described. The author is not aware of many previous investigations of the hardness of this alloy when quenched and drawn, but two important papers on the subject should be mentioned. The earliest was by Portevin and Arnou,1 in which it was stated that tempering quenched 10-per cent. aluminum bronze at 400° C. increased the hardness as compared with the quenched untempered alloy and that reheating above that temperature was necessary to obtain any softening effect.

Jan 7, 1924

By E. F. Loiseau

(Read at the Philadelphia Meeting, February, 1878.) UNTIL June, 1868, it had not been attempted, either in this country or abroad, to manufacture by mechanical means, from anthracite coal-dust, artificial fuel for domestic use. Several attempts had been made to utilize coal-waste by converting it into a fuel for manufacturing purposes, but none of the processes were original, and they were merely applications of the well-known European processes and machinery, slightly modified by American ingenuity and mechanical skill. With one exception all those attempts have been failures. The great difficulty in the application of European processes and machinery has always been the limited production, and the excessive cost of the manufactured product, as compared with the cost of mining and preparing the ordinary anthracite coal for the market. The only serious and intelligent attempt to manufacture, on a large scale, artificial fuel for manufacturing purposes, has been made by the Anthracite Fuel Company, whose works are erected at Fort Ewen, near Rondout, New York. This company, organized under the auspices of the Delaware and Hudson Canal Company, had to go through the usual course of difficulties, breakages, and disappointments, which seems to be the lot of every new industry. Thanks, however, to the energy and perseverance of Mr. L. L. Crounsse, a gentleman of means, from Washington, D. C., the enterprise succeeded, and it is to-day established on a permanent basis. In order to increase the production, and to reduce its cost, the Anthracite Fuel Company was compelled to change most of its plant, and to erect more powerful machinery, producing lumps of a larger size, almost twice the size of the lumps made previously by the same company. This increase in the size of the lumps has been resorted to in Europe as well as in this country, in order to increase

Jan 1, 1878

By A. J. DeArdo

Linepipe steels have come a long way in the past forty years. In fact, modern, high strength steels for large diameter linepipe applications represent one of the seminal accomplishments in metallurgy of the past half-century. The synergy of advanced steelmaking, alloy design including microalloying, hot rolling, and interrupted accelerated cooling has led to the marvelous steels being used today. The drive for higher performance pipelines has been motivated by the energy sector of our global economy who wanted both higher throughput capacity, i.e., larger diameters and higher pressures, and lower material cost, i.e., relatively thinner gauge wall thicknesses. These requirements led to new steels with higher strengths, better toughness and improved weldability. The goal of this paper is to trace the evolution of linepipe steels from the X60 grades of the small diameter pipelines of the 1960s to the (X80 - X120) grades used in the large diameter pipelines of today. The metallurgical triumphs permitting this success story, e.g., clean steel practices, controlled rolling, microalloying with Nb, and using IAC to obtain low temperature transformation products, will be highlighted and discussed.

Jan 1, 2005

By M. Ramachandran, R. G. Reddy

"A direct route for the reduction of magnesium oxide to magnesium using thermal plasma processing, with methane as the reducing gas, has been systematically evaluated. A feasibility study of the reduction reaction has been performed on the MgO-CH4 system at different methane concentrations and temperatures. The effects of changes in the key process parameters, such as the oxide-to-methane ratio and plasma power, on the yield of magnesium have been systematically evaluated. A maximum yield of about 61 mol% Mg was obtained using power of 20.0 kW and a molar ratio of MgO:CH4=1:1. Phase, morphological, elemental and binding energy analyses were performed on the product powders to understand the reduction reaction. Surface oxidation was observed in smaller magnesium particles in all the experiments, while the in-situ sintering of magnesium rods was observed at a molar ratio of MgO:CH4=1:1.5. Magnesium carbide (Mg2C3) was observed in the product, and its mechanism of formation is proposed using phase equilibrium data and a predominance diagram.IntroductionMagnesium has an excellent combination of low density and high strength. These properties have increased worldwide demand for and use of magnesium. Two major processes are used in the commercial synthesis of magnesium metal. The first method is electrolytic reduction and the second is thermal reduction using Pidgeon process. These processes can be classified as traditional techniques, but there are numerous emerging technologies that aim at reducing the production cost of Mg, its environmental impact and energy consumption. Thermal plasma processing is one emerging technique that has great potential in all the abovementioned key areas of magnesium production.Traditional reduction techniques. Two major reduction techniques, namely electrolytic and thermal reduction, have been used in the commercial production of magnesium. Electrolytic reduction is typically carried out in electrolytic cells from magnesium chloride (obtained from seawater or well and lake brines) (Tripp, 2009). The following simplified reaction shows the reduction of magnesium chloride to liquid magnesium and chlorine gas:"

Jan 1, 2015

By Ross D. Lawrence

"Comparable transaction analysis is the best known of the market approaches to valuation of exploration-stage mineral properties. The analysis of option and farm-in agreements can also provide useful guidance to valuators. While such approaches can be distorted by incomplete analysis, market-based methods are capable of providing consistent, credible results when carried out carefully with due consideration paid to all factors which buyers and sellers consider when dealing in the real market.RÉSUMÉRoss D. Lawrence graduated from the University of Toronto with a B.A.Sc. (Applied Geology-1956) and an M.Comm. (Mining Finance-1959). As a student and following graduation, he worked across Canada on a variety of mineral exploration projects.In 1962, he was one of the founders of Watts, Griffis and McOuat, and has practiced as consulting engineer since then. For the past 20 years, Mr. Lawrence has headed up the WGM valuation practice, responsible for a group of professionals which has carried out scores of valuations of mineral properties and mining companies. He is a Certified Minerals Appraiser of the AIMA and an active participant in professional affairs.INTRODUCTIONMineral properties without defined resources present one of the most challenging tasks to the mineral valuator. You will hear from others at this conference about the use of cost and income approaches to the problem of valuing exploration properties. This paper will concentrate on market-based approaches. Market based-approaches are based on the principle of substitution and include such techniques as:??Comparable transaction analysis (sometimes referred to as sales comparison analysis).??Farm-in commitment analysis??Rules of thumbAre there any valuation standards available to assist the valuator? In Canada there are none that apply to the valuation of mineral assets or securities. This problem is being addressed, at least in part, by the CIMVal committee of the Canadian Institute of Mining, Metallurgy & Petroleum (CIM)1. Further, the recently established Canadian Association of Mineral Valuators will be giving consideration to the adoption of valuation standards."

Jan 1, 2003

By David Ziegler, John Babcock, Gregory Poole

On December 9, 2003 at 3:59 PM EST an earthquake with a 4.5 magnitude occurred in central Virginia. According to a survey on the US Geological Survey website, this quake was felt as far away as Bridgeton Missouri, approximately 683 mile from the epicenter1. We recorded the vibrations from this earthquake on 14 seismographs that were set up for monitoring vibrations from blasting activities in the area. Having this data gave us an opportunity to compare earthquake and blasting vibrations. The amplitudes, frequencies and duration were much different than vibrations from mining and construction blasting. A common question we get from homeowners when discussing vibrations from blasting activities is “How does that compare to the Richter scale?” The goal of this report is to provide some simple answers for that question. The Richter and Mercalli scale are compared to the particle velocities in order to show their relationship.

Jan 1, 2005

By Robert B. Parsons

"Finance Minister Paul Martin's first budget disappointed almost everyone. The business sector was disappointed at the some what feeble attempt to grapple with the country's deficit. The mining industry was disappointed by tax proposals regarding mine reclamation that fall short of the industry's needs. Has anybody been happy with a federal budget? Federal Budget DisappointsThe federal government's budget papers that were tabled on February 22, 1994, contained a rather bizarre mixture of unrelated tax proposals. The budget signals an unexpected attack on the tax treatment of debt settlements, on certain types of corporate reorgani2ations, and on income earned by foreign affiliates. This is an old style budget, which proposes a pot pourri of technical changes and policy initiatives. Mine ReclamationEffective February 23, 1994, a taxpayer's contributions to a prescribed mine reclamation trust fund will be deductible as a current expense. The budget papers do not provide a definition of what will constitute a ""prescribed"" trust: this definition will surface in due course. However, the budget papers indicate that:• income earned in such trusts will be subject to tax each year;• all withdrawals from the trust (including income already taxed) will be included in computing the income for tax purposes of the recipient;• reclamation costs will continue to be fully deductible at the time incurred; and • contributions, trust earnings, and withdrawals will not be taken into account for the purposes of determining a taxpayer's resource allowance."

Jan 1, 1994

By E Asakpo, S Chaffer, A Heath

Newmont has had continuous production at their Ahafo operations, Ghana, since 2006. In 2013, Ahafo initiated an efficiency programme to improve mill performance and reduce energy consumption. Following this assessment, a Turbo Pulp Lifter (TPLTM) was installed in the Ahafo SAG mill in April 2015 to replace the existing radial pulp lifters. Plant operational data showed delivery of a power saving of 10 per cent, an improvement in throughput of 3.3 per cent, with no loss of grind size. Pulp lifter life was also doubled from 11 to 22 months.However, during subsequent relines when the grates were removed it was found that one in four of the outer pulp lifters were wearing at a faster rate than the remainder. This was investigated by Discrete Element Method (DEM) modelling, which predicted some overtopping and internal recycle within the pulp lifter. Significantly, the model predicted that the recycled material would pass back down every fourth outer pulp lifter, matching the field observations. Subsequently, the DEM investigation was continued and became an R&D project to improve the TPL design. The results are summarised here, leading to the development of the next generation Spiral TPLTM.CITATION:Heath, A, Chaffer, S and Asakpo, E, 2018. The development of optimised pulp lifter design for the Ahafo SAG mill using discrete element method modelling, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 585–594 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By Joel Lööw, Jan Johansson, Lena Abrahamsson

Industry 4.0 offers new possibilities to combine increased productivity with stimulating workplaces in a good work environment. Used correctly, digitalization can create attractive jobs in safe control room environments, which provide space for the employee’s full expertise and creativity. This is true also for the mining industry. But, to succeed, it is important to analyze the development from a worker’s perspective. What will happen to their work? What skills will be needed in the mine of tomorrow? We must also consider the risks, such as privacy issues, increased stress, and work-life boundaries. These questions must be understood if we are to create workplaces that can attract a young and diverse workforce to tomorrow’s mining industry. In this article, we try to illustrate what the new technology can mean for the individual miners. We formulate the notion of Mining 4.0 (Industry 4.0 in the mining industry), where we try to create an image of how the future might look from a miner’s perspective and how mining companies may navigate their way to a future that works for all miners. To illustrate the range of possible outcomes, we formulate two scenarios: one utopian and one dystopic. At the end of our article, we bring forward six recommendations that can be considered a beginning of a road map for the human side of Mining 4.0.