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By S. Mostaghel, S. Nicol, M. Y. Solar

Once upon a time, the process engineer developing the design criteria for a new saprolite ferronickel smelter had it easy: most ores were around 2.5% Ni, with a Fe/Ni ratio of 4 to 5 and a SiO2/MgO ratio of about 1.6; to use the French word: garnierites. The ferronickel grade selected was the conventional 20 to 25% Ni and the impurity levels could be predicted from well established [C], [Cr] and [Si] vs (FeO) graphs. However the process engineer can no longer depend on statistics to design smelters: Ni grades are decreasing while the goethite contents are increasing; SiO2/MgO ratios vary from 1 to 3; and Al2O3 concentrations are reaching levels that cannot be ignored. Mechanistic models must be developed to select or predict essential parameters such as kiln and furnace reductions, ferronickel grade, slag losses, metal and slag liquidus, operating temperatures, etc. But these models must be simplified so that they can be used on a routine basis; and they must be calibrated against a wide range of commercial operations in order to yield the most realistic predictions possible. The present paper proposes one possible approach, using FactSage as a basic source of thermodynamic data. The predictions thus obtained are compared to actual performance for two well documented operations, as well as to the predictions made with other tools that might be more accessible.

Jan 1, 2014

In spite of the many contributions that have been made to our knowledge of the creep properties of polycrystalline lead, the precise influence of various factors on these properties is not yet fully understood. Indeed, the position is such that several important points in connection with the creep of lead are a matter of controversy. This has been brought about largely by the fact that, in the case of lead, the changes that are produced in the creep behaviour by slight variations of such factors as the purity, grain sizeand previous treatment are out of all proportion to the magnitude of these variations.In order to study the fundamental properties of lead as related to creep, and so gain a more enlightened perspective with which to consider the creep of lead in general, the work that is described in a series of papers, of which the present paper is the third part, has been carried out. It deals with lead in the form of single crystals.It has been shown (1) - (3) that the grain boundaries as well as the actual grains play a part in the creep of polycrystalline lead. The present work, by eliminating grain boundaries, enables the. contribution of the grains themselves to the process of creep, in other words, crystalline creep, to be studied effectively.This object was, possibly, the major one in this work.

Jan 1, 1940

THE area dealt with in this paper is included within a radius of about 3 miles of the Poimena township. Several thousand tons of tin have been won from this field, and probably £200,000 spent in exploiting it.PREVIOUS LITERATUREThe field has been reported on by Government geologists on four occasions and several ,articles on it have appeared in the mining journals. The work done by Government geologists is summarized below:-"Report on the Blue Tier Tin Mining District and its Tin Deposits", 1886.Speaking of the tin-ore occurrences, this paper states:-"In the primary granite the lodes of tin ore occur, also dykes and belts of more recently obtruded porphyries. The really valuable metalliferous deposits may be classified as follows :-1. Lodes (of which the Lottah mine is typical).2. Dykes- (a) Indurated or hard (as shown by the formations at the Anchor and Cream Creek mines). (b) Soft (eg Hayley's Lease).

Jan 1, 1912

By John Rusnak

The Coal Mine Roof Rating (CMRR) is a practical rock mass classification system for use in design of mine openings. Data can be obtained for this purpose from exploration drill cores if simple geotechnical logging and rock mechanics testing is conducted. The CMRR is an excellent method to quantify rock characteristics for engineering purposes. It bridges the gap between geologic description and engineering design. The CMRR was utilized in the design of a 10,000 fl. long coal belt conveyor tunnel connecting an Eastern Associated Coal Corp. mine and preparation plant in Boone County, West Virginia. Data gathering and analysis techniques are discussed involving the calculation of the CMRR and its application in the design of the tunnel, which was driven through a thin coal bed zone. The preliminary findings have correlated well with actual roof and mining conditions encountered during driving the tunnel and it is concluded the CMRR is an effective method to utilize geologic data from exploration core holes for engineering analysis and design.

Jan 1, 1998

By M. M. Tilman

In a Bureau of Mines investigation to develop lead alloys with improved tensile strength and creep resistance, lead-base alloys containing cadmium and antimony in nominal 1-to-1 atomic ratios were melted in air, cast, and rolled into sheet to 90 percent reduction at temperatures varying from room temperature to 175° C. Tensile testing at room temperature and stress-rupture testing at 900±3° F were conducted on the as-rolled alloys. The best tensile properties were observed in an alloy of Pb-4.2 wt pct Cd-4.5 wt pct Sb which exhibited an average tensile strength of 7,270 psi with 36 percent elongation in 2 inches. An alloy of Pb-5.5 wt pct Cd-6.0 wt pct Sb had 100-hour stress-rupture values of approximately 2,100 psi and 1,000-hour values of approximately 1,700 psi.

Jan 1, 1969

By A. R. Naderian

Laboratory strength and deformation testing of freshly blasted sandstone and claystone overburden from Jeebropilly colliery in Queensland and in-situ plate-bearing tests on four backfills of different ages showed that the bearing capacity of backfill is a function mainly of compaction, not of age. The modulus or stiffness of the backfill is significantly increased by previous loading, in some cases up to threefold. Backfill material experiences some compaction through the passage of mining vehicles, likely to provide a bearing capacity that will support normal construction activities; the limited testing performed suggested that completed backfills are capable of supporting loads of up to 200 kN/m2 while sustaining displacements acceptable for a wide range of residential and industrial uses, but may be susceptible to collapse settlements due to saturation in the long term

Jun 19, 1905

By Grainne A. Matthews

Jan 1, 2009

By Seffen Leppla, Rolf Katzenbach, Matthias Seip

"Abstract The economic and safe design of deep foundation systems in difficult soil conditions is based on a reduction of construction material used, construction time spent, energy consumed and a high-level modelling of the soil-structure-interaction. The special foundation system Combined Pile- Raft Foundation (CPRF), in-situ load tests on the construction site and a sufficient soil investigation allow cost optimised constructions. In any case at challenging projects the observational method has to be applied for verification and quality control of the design. Regarding the 4-Eye-Principle as basis of the quality control management an independent peer review of the planning, design and construction phases is the guarantee for safety, serviceability and optimisation of all projects. Main execution standards for the construction of deep foundations based on the Eurocode 7 are summarised and discussed. The paper presents the basics of the safe and qualified design and construction of foundation systems including quality assurance. The application in engineering practice is shown on achallenging project of high-rise buildings with difficult boundary conditions.IntroductionThe construction of deep foundation elements in inner cities are special challenges due to the limited space for the construction works and the effects on existing buildings (Figure 1).An economic and safe design of deep foundation systems in difficult soil conditions is based on the following main aspects:•,qualified experts for planning, design and construction•,interaction between architects, structural engineers and geotechnical engineers•,adequate soil investigation•,design of deep foundation systems using the Finite-Element-Method (FEM) in combination with•,enhanced in-situ load tests for calibrating the soil parameters used in the numerical simulations•,quality assurance by an independent peer review process (4-eye-principle) combined with theobservational method if necessary"

Jan 1, 2014

The solvent extraction section of an old Uranium Plant in the Vaal River region (North West Province in South Africa) produced a substance called CRUD (Chalk River Unidentified Deposit) that formed within the aqueous/organic interface of the settler of the solvent extraction circuit. The CRUD was deposited together with gold tailings to the tailings dam many years ago. Previous research done on the CRUD confirmed that exposed CRUD leaches Mn and Ni at concentrations that are well above their acceptable risk limits as well as Zn that leaches at concentrations that are slightly lower than its acceptable risk limit. Soil washing and bioremediation technologies were employed to treat the contaminated soil.   Various laboratory test work and the pilot scale studies were conducted in parallel with each other and the results of the laboratory studies were used to determine critical parameters. Four lixiviants, ie sulfuric acid, acetic acid, oxalic acid and ethylene diamine acetic acid were tested at three concentration levels ie 0.001 M, 0.0001 M and 0.00001 M, respectively. Column tests showed that the leaching of the heavy metals increases as the soil porosity increases. Silica sand was added to increase porosity of the contaminated soil. Highest Mn removal was achieved mainly by sulfuric and oxalic acid at 0.001M at all soil levels. EDTA was significantly efficient in the removal of Ni and Zn. The recovery of heavy metals, particularly Mn, decreased as the depth of sampling increased.   Heterogeneous bacteria and filamentous organism plate counts were conducted to evaluate the growth of the bacteria and filamentous organisms in the soil. Results showed that more organism growth took place in the bioremediated soil with a fertilizer added to it. The leaching of metals from the soil that was bioremediated in the pilot study was generally higher than the extraction of the metals from the soil that was leached with no bioremediation carried out. The results from this study suggest that the leaching of heavy metals from the contaminated soil is to a large extent dependant on the pH of the leaching solution. By increasing the soil's porosity and bioremediating the soil, higher extractions of metals were achieved.

Jun 1, 2010

By W. K. Connor, O&apos

The U.S. Bureau of Mines investigated the Sheep Creek prospect in the north-central Alaska Range to evaluate the Pb, Zn, Ag, and Sn resources. The studies included field investigations, mineralogical characterization, and concentration tests. Mineralization at Sheep Creek consists of disseminated, banded, and massive pyrite, sphalerite, and galena. Tin occurs as grains of cassiterite (Sn02) in the quartz-mica matrix and within pyrite and sphalerite grains, and Ag occurs in solid solution within the galena. Three bulk surface samples and two sets of core samples were collected at the Sheep Creek prospect for this study. Gravity concentration yielded products with up to 30 pct Sn, and the best result was a product that recovered 52 pct of the Sn at a grade of 22 pct Sn. Bulk sulfide flotation yielded products that recovered up to 89 pct of the Zn, 73 pct of the Pb, and 75 pct of the Ag, but grades were relatively low; selective flotation would significantly increase the grades.

Jan 1, 1989

By W. J. Theron

The purpose of the paper is to give an introduction to the concept of fatigue and its causes in the mining industry. By knowing the fundamental role it plays, together with its dynamics, can positively contribute to a mine?s safety management system. The difference between physical and psychological fatigue will be addressed with a possible range of causes that could trigger fatigue. There are two main sources of fatigue: firstly, work-related fatigue which is associated with activities at the workplace; and secondly non-work-related fatigue. The shared responsibility between the employer and employee is also discussed as it involves factors that occur both in and outside the workplace. Employers have the responsibility to manage fatigue through using a risk management approach. Employees have the responsibility to ensure they get enough sleep, take sufficient and regular nutrition, are healthy and physically fit and come to work fresh and alert. The impact of the implementation of a fatigue management plan and procedures has the potential to eliminate employee fatigue or its causes, reduce the likelihood of fatigue occurring in the workplace, and counteract the effects of fatigue when it occurs. Factors considered when implementing a fatigue management system include: extended hours of work, shift work, time of day and work design. Fatigue is one of the major role players (either causal or contributory) when it comes to causes of fatalities in the mining industry. Our main challenge in identifying whether fatigue played a role is the fact that it cannot be tested in post-mortems like drug or alcohol abuse. It is an aspect worth understanding and getting an organization sensitive to managing it properly to benefit both organizational as well as employee needs. Keywords Signs of fatigue: Causes of fatigue, circadian rhythms, the fatigue equation, fatigue management, fatigue affecting safety, fatigue fighting tips, lifestyle suggestions.

Jan 1, 2011

The mechanization of the coal industry in New South Wales involved the introduction of large face and transport machines. The trend is towards still higher capacity units with .greater horsepower and it became apparent that a potential risk of damage to the hearing of workmen existed. In order to assess whether the sound levels were SUfficiently high to impair the hearing of workmen a sound level survey of all major operations in the industry was carried out by the Mining Engineering Division of the Joint Coal Board.The results indicated ·that the operations could be classified into three categories of risk, probably hazardous, of doubtful hazard due to the intermittency of the operations, and of low hazard.Legislation has subsequently been enacted requiring the wearing of hearing preservation aids in some of the probable risk operations.

Jan 1, 1974

As the surface reserves are being depleted, more and more stone operators are seeking underground mining options. Stability of underground openings is a major concern for the safety and productivity. This paper relates to a field study conducted at a large underground limestone mine in Central Pennsylvania. Identification of hazards leading to ground failures and assessment of roof fall risks are important in mitigating injuries. Field observations at this mine were integrated with Roof Fall Risk Index (RFRI) mapping software recently developed by West Virginia University. The system is designed to combine field study data related to geologic factors, mining-induced damages, roof profile, and ground water influx to generate RFRI maps. The mine has adopted a proactive ground control program consisting of comprehensive examination of drilling and bolting logs; precision surveying of roof and rib; accurate mapping of cutters, falls, and geologic structures; and installation of extensometers and microseismic monitoring systems. Investment of time and resources has eliminated fatalities and lost-time injuries due to ground fall. This paper presents the geologic settings, mining conditions, ground control issues along with risk management and control techniques adopted at the study mine.

Jan 1, 2009

By J. R. Goode

"Coarse ore sorting is here defined as the physical separation of a mixture of coarse (+3/8 inch) ore particles into two or more separate groups of total value greater than that of the unsorted ore. An ore will probably be sortable if the geology of the orebody and the mining practices employed meet conditions outlined in this paper.The paper points out how sorting can substantially reduce tonnage variable operating costs because sorting can double the mill head grade of amenable ores by rejecting waste rock from the mine output. The effect of sorting on ore reserves is outlined. It is also suggested that sorting is a low cost alternative to conventional expansion.The mode of operation of the Ore Sorters Kadel 13 Photometric and MK VI A Radiometric sorters is detailed. The report concludes with detailed descriptions of the photometric sorting plant operated by the Doornfontein Gold Mining Company is South Africa and the Radiometric Sorting Plant presently under construction at the Schwartzwalder mine of Cotter Corporation in Colorado."

Jan 1, 1975

The addition of cement to underground backfill at The Zinc Corporation, Limited and New Broken Hill Consolidated Limited, Broken Hill commenced in 1967. A deterioration in metallurgical performance at each concentrator occurred as a result, with increased loss of lead and zinc to residues. Investigations to determine the reasons for this problem and methods to counteract it have been undertaken. This paper outlines the effects of cement on lead-zinc beneficiation at Broken Hill and presents an interim report on attempts to overcome the metallurgical deterioration.

Jan 1, 1971

By B. Larsen, S. Z. Nascimento, K. Fidje, J. P. M. Amaro, H. Gran

Safe and good operation of Søderberg electrodes is dependent upon high quality electrode paste coupled with correct electrode operating procedures. Good electrode performance depends further on proper melting and densification of the electrode paste. The melted paste should form a dense and viscous layer that prevents gasses from the baking process to move upwards. Both paste cylinders/blocks and briquettes can be used, but the procedures may differ between the various types of paste products. For briquette columns the formation of the important viscous layer is obtained through melting and densification of the briquettes. By basic rheological studies of electrode paste and by laboratory tests of briquette beds at isothermal conditions we have achieved a better understanding of the melting process. The effects of temperature gradients, pressure and friction between the briquettes and the electrode casing have also been evaluated qualitatively in pilot scale experiment and in industrial scale tests. The paper shows that melting and densification starts at a considerable lower temperature than the pitch softening temperature. It is concluded that the formation of a briquette electrode column depends on parameters as temperature, briquette column pressure and the friction. Operating conditions influencing the above parameters should be defined and established for each specific furnace operation. Such factors are e.g., charging and slipping procedures, column heating and electrical conditions.

Jan 1, 2004

An incremental analysis based stope design optimization method was developed at Exodus, an underground project located 30 miles north of Carlin, Nevada. Traditional underground stope design methods, by manually drawing stope shapes, are typically very time-consuming and lacking of consistency and accuracy. For quick reserve calculation and economic analysis, a new method named '3D Incremental Analysis based Stope Optimization' was created for mine wide stope designs at Exodus. With this unique but practical method, multiple options of mine designs were completed within a short period time, which allowed us to select the optimal cutoff grade and best stope design option for the project.

Jan 1, 2012

By David M. R. Stone

Underground mining in the gold industry is gaining popularity in Nevada, and with it the use of cemented rockfill is becoming mainstream. Even with today?s high metal prices, however, mining companies are very sensitive to the margins they realize, and are constantly looking for ways to reduce costs or improve efficiencies. Given that the backfill is one of the largest cost centers in underground mining, mines are constantly under pressure to reduce backfill costs. This paper will present an overview of the factors that impact cemented rockfill quality in Nevada mines based on the authors many years of consulting experience. Cemented rockfill quality can be linked directly to binder consumption, hence programs aimed at improving quality generally result in lower binder costs, better performance in the fill (hence less dilution), and improved safety. The paper will conclude with the key elements of a comprehensive program of backfill quality assessments and backfill QA programs. Comparative laboratory and minesite data from a number of operating and proposed mines will be presented.

May 1, 2007

THERE are certain facts that the mining industry in Australia is faced with at the present moment which may be accepted as axioms. The industry is at a low ebb, as evidenced by statistics. Metals form the basis of all modern industries, and are necessaryfor the welfare of Australia. Mining is a wasting asset. Every ton of ore extracted is one ton less which c.annot be made good, and it should be our duty to get as much profit froin that ore as possible, otherwise there is a permanent loss to the country.The metal market cannot be controlled by Australia; it is more or less an international matter. Australia has not been thoroughly prospected. There are no mines being developed that are likely to replace those which are being depleted.Our mining engineers are as capable as those in other parts of the world, and have made good where they have been given a chance. There is no one cause for the present depression; there are several, more or less, interwoven. Of course, the war has had an adverse effect, but that has only dislocated things temporarily; it upset our markets, influenced the price of metals, and affected the labour market and cost of stores. Labour troubles made their appearance before the wave of unrest swept over the world. The cause of labour discontent must be investigated, and if possible removed. As each industry has .its·own problems, miners must inquire into their special problems, as there is no sovereign remedy that will suit all cases.It is obvious that we cannot mine ore if we do not know where it is; therefore, the first thing is to discover workable deposits.

Jan 1, 1919

By Roberto Maldonado

El presente texto señala el proyecto de profundización en la mina Animón considerando sus características como: geología e hidrogeología, parámetros geomecánicos, niveles de producción, costos de capital y operación, eficiencia del sistema, flexibilidad para cambios en las operaciones, reservas de mineral y consistencia con el sistema de explotación. De forma que a través del conocimiento de estas y de las herramientas gráficas tridimensionales, se pueda analizar las diferentes alternativas, incluyendo condiciones que debe cumplir el proyecto de profundización, el cual abarca también los servicios auxiliares y ventilación.

Sep 12, 2005