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By Fathi Habashi

"Crushing and grinding of ores and their beneficiation by washing away gangue minerals has been practiced since ancient times. Primitive crushing was done by hand pounding the ore with a hard stone then by using metallic hammers. The mortar and pestle was mechanized using a lever and when the size of operations increased in the middle ages, the stamp mill was introduced. The grindstone played an important role in grinding of ores. Panning for gold and hand sorting of minerals were two old methods of separation, now gave way to modern techniques. Flotation started in the middle of the nineteenth century by using oils to collect the mineral particles and float them on the surface of the aqueous slurry. It was only in the 1920s when it was discovered that organic compounds were affective floating agents. Textbooks written by distinguished engineers such as Rittinger, Rickard, Pryor, Taggart, Richards, Gaudin, and others contributed to the recognition of this field as a new discipline to be taught in Universities. INTRODUCTIONThe ancient Egyptians knew already that it would be easier to melt an earth rich in gold particles than another which is poor. As a result all efforts were made to enrich the gold by washing away the light gangue minerals (Figure 1). Another ancient method for enriching gold particles from a river stream was by means of fleece, hence the Greek myth of the “golden fleece”. The present day Georgia was known in ancient times as Colchis and was a center for gold working. It was known to the ancient Greek as the land of Golden Fleece. The use of special cloth to catch gold particles was also described by Agricola in his 1555 book De Re Metallica (Figure 2)."

Jan 1, 2009

By Alice H. Zhu

Belt conveyors are widely used in materials handling industries. The bulk materials which can be transported include ores, coal, earth, grain, limestone, wood chips, fertilizer components such as potash and many others. Along with the new technology development and enhanced industrial automation requirements, belt conveyor instrumentation has also been modernized to improve conveyor availability and performance. Traditionally, belt conveyors are equipped with emergency pull cord switches to shut the conveyor down, misalignment switches to signal the belt offline condition, speed sensors to detect the belt slippage, and level switches to prevent material plugging in the discharge chute. Belt rip detectors are also normally provided for long belt conveyors. As a rule, equipment condition monitoring is not automated at most operating facilities, but is performed manually by maintenance staff via time-based surveillance. The new generation of condition monitoring instrumentation and control equipment can be successfully utilized to design a reliable, cost-effective, and centralized monitoring system, capable of monitoring a wide variety of mechanical equipment. The implementation of the condition monitoring automated system can provide continual monitoring of the plant equipment to ensure safe operation of the equipment to its required capacity. Any abnormal behavior of the motors, gear reducers and pulleys can be analyzed, alarmed, and recorded immediately, so problems can be detected and resolved before critical components failure. Therefore, the current trend is to provide the belt conveyors with condition monitoring system in addition to the traditional instrumentation, where temperature probes and vibration sensors can be installed on motors, gear reducers and all pulleys. Another innovative development is a three-in-one type belt rip detector which combines laser, tray and cord type detection together to ensure a prompt belt tear indication. The purpose of this paper is to present the latest development of belt conveyor instrumentation and introduce the application of newly developed instruments.

Nov 1, 2011

By Y. K. Yen, J. D. Miller, C. L. Lin

The image-based On-line Particle Size Analyzer (OPSA)system has been developed at the University of Utah to measure particle size distributions under plant conditions where overlapped and segregated particles are being transported on a moving belt conveyor. Evaluation of the OPSA system at several plant sites has been completed. The results show a consistent agreement between the particle size distributions obtained from the OPSA system and those obtained from laboratory screen analysis of belt samples. These results and the stable performance of the OPSA system during the field tests suggest that continuous quality control of crushed products is possible using the OPSA system.

Jan 1, 1999

By George S. Rice

In response to numerous requests for information as to the status of internal-combustion mine locomotives of the Diesel type that use heavy or non- volatile oil for fuel, with special reference to their safe use in coal mines, the United States Bureau of Mines is issuing this report. Data mere obtained, on application of such locomotives to cod mining only in Belgium, France, Germany, and Great Britain. The locomotives are used in coal mining in other countries, as well as in potash, iron, and other kinds of mining, but their chief development has been in coal mining in Germany, France, and Belgium. Recently popular interest in the Diesel type of engine for motive purposes was aroused in this country by the successful application of Diesel engines to railroad locomotives hauling fast transcontinental trains, and, according to published statements, at a low cost of fuel per mile of run.

Jan 1, 1936

By Satyajit Vaidya, Rudolph Frizzi, Luis Berroteran

This paper presents design and construction challenges associated with a high-capacity rock-socketed drilled pile foundation system for a 60-story building recently constructed in an urban environment. The site is in very close proximity to surrounding 1-to-6-story buildings and a commuter rail subway tunnel structure. High compression, uplift, and lateral loads imposed by the tall, slender tower constructed over a relatively small site footprint posed a significant design challenge due to the close proximity of the subway tunnel and other structures. Construction challenges included those associated with advancing the drilled pile casings through overburden materials using internal flush method mandated by the Transit Agency, advancing the casings through very dense glacial till materials encountered above top of rock, and drilling rock sockets in variable rock conditions. This paper provides a brief overview of the site and subsurface conditions, and discusses the resulting design and construction challenges for the drilled pile foundation system and how they were addressed. SITE AND SUBSURFACE CONDITIONS The 8,350-square-foot site is located in a busy neighborhood in downtown New York City (NYC). Buildings neighboring the site are supported on shallow foundations, and their basements extend about 15 feet below the sidewalk level. A NYC-Landmarked building is located within a NYC Department of Buildings (DOB)-designated 90-foot influence limit from the Project site. NYC Transit Authority (NYCTA) subway tunnel and station structures are located in close proximity to the Project site. The subway tunnel structure extends about 50 to 55 feet below the sidewalk level. Although the upper portion of the tunnel structure is about 13.5 feet away from the site property line, the lower portion is only about 1 foot away from the property line. A site location plan is presented as Fig. 1. Geotechnical borings revealed subsurface conditions generally consisting of successive strata of surficial fill, sandy and silty soils, and glacial till (predominantly consisting of cobbles and boulders) overlying mica schist bedrock. A generalized subsurface profile is presented in Fig. 2. The surficial fill stratum was about 10 to 23 feet thick, and generally consisted of loose to medium dense sandy soils with varying proportions of silt, gravel, and miscellaneous debris such as brick. The underlying sandy and silty soil stratum was about 60 to 79 feet thick and generally consisted of loose to medium dense inter-bedded layers of fine to coarse sand, silty fine sand, and silt. The underlying glacial till stratum was about 26 to 70 feet thick and generally consisted of cobbles and boulders embedded in a very dense soil matrix. Top of bedrock was encountered in the borings about 110 to 150 feet below sidewalk level. Groundwater level was measured at about 30 feet below sidewalk level.

Jan 1, 2018

By Richard D. Begley

This paper summarizes the development of a mechanistic model to predict longwall mining induced surface subsidence. The model was originally developed from data acquired from a recent field study conducted in Northern West Virginia. Additional data has been collected from published sources and used to refine the model. The original model utilizes a negative exponential equation to predict the subsidence profile after the maximum possible subsidence is predicted based on the following input parameters: mine geometry, angle of draw and expansion factors for the deformation zones that have been identified above a longwall excavation. The model refinement involved the development of relationships between physical properties of the overburden strata and angle of draw in addition to the expansion or bulking factors. Therefore the refined model now requires only mine geometry and a typical geologic column from the site to predict the subsidence profile. This paper provides the methodology that enables the model to determine the angle of draw and expansion factors breed on physical properties of the site geology i. e. percent of strong rock and Rock Quality Designation of the overburden strata. In addition :comparisons of predicted results with measured data for over H) different sites with various geological and geometrical parameters located throughout the United States will be presented.

Jan 1, 1989

By Janne P. Isohaka, Anssi M. Laaksonen

"Abstract In Scandinavia the use of steel pipe piles in bridge foundations started in the mid-1980s and has increased steadily since. As the piles driven in soft soils are slender, they can fail by buckling. Buckling usually requires taking into account the second order effect in structural and geotechnical design.The purpose of this paper is to derive formulas for demonstrating the theory behind the formulas given in literature for the second order effect of initially bent piles.IntroductionIn Scandinavian countries solid bedrock usually lies at moderate depth. If the bridge site is in an area where the soil above the bedrock is soft, the bridge is usually founded on end-bearing piles resting on the bedrock.The main purpose of the piles is to transfer axial forces into bearing soil. Like columns, piles can lose their stability by buckling when surrounded by soft soil. When axial compression on a slender, initially straight, pile reaches a particular value called the critical load, the pile is subjected to lateral deflection and loses stability. The soil around the pile suffers a corresponding deformation. This soilstructure interaction increases the critical load compared to a pile without surrounding soil.It is very unlikely that piles are ideally straight. Initial curvature along with curvature and deviation caused by the installation of piles causes bending moments to the pile when normal force is applied. These lateral displacements increase when normal force increases. This increase of moment is called asecond order effect.Eurocode and literatureEurocode 7 includes guidelines for the design of piles (Eurocode 3, section 5 includes design of steel piles). However, there are no clear guidelines for considering the second order effects related to piles surrounded by soil. Eurocodes advise doing structural design of piles the same way as in the case of columns. With columns, the second order effect is taken into consideration by multiplying the first order moment with the factor shown below (SFS EN-1992-1-1, 2005):"

Jan 1, 2014

By N. Jayaraman, V. Srikant, A. Radhakrishna

Addition of a 500 MW unit to the existing units at Ramagundum Thermal Power Station requires blasting of large volumes of rock very close to sensitive installations like Turbo generator, Generator transformer and Power cycle equipments. Levelling of the areas and excavations for footings are, therefore, to be carried out cautiously. The existing sensitive installations should be protected against ground vibrations and flyrock. The paper describes the details of a few of the many blasts carried out successfully wherein the ground vibrations were restricted and flyrock was avoided.

Jan 1, 2003

In setting out to describe the methods and machinery employed at Iron Knob the writer does not attempt to give any information as to the situation, topography or geological features of the locality. This, together with estimates of the quantities of ore still available, has been carried out in a most thorough manner by R. L. Jackr and F. R. Hockey. This essay is intended to deal with working methods as they exist to-day, beginning with drilling, blasting, quarry traction, etc., and touching on such details as the supplyof electricity, water and compressed air.At the present time almost the entire output of ore is won from the hill known as Iron Monarch. The form of the hill, a smooth, rounded dome, rising some 640 ft. above the plain and having a base diameter of n miles, lends itself ideally to the "bench" system of open-cut quarrying.Fig. 1 shows the relationship of the benches "A," "B" and "E" in their order of development. Bench "E" is at present the principal working, but, as the greater part of the ore above this level has now been removed, bench "A," some...

Jan 1, 1936

By B Vorster

Falls of Ground is one of the highest causes of incidents, accidents and fatal injuries in our mines today. These falls of ground may occur as soon as the face is exposed after blasting or after machine cutting. The falls of ground can also occur after support has been installed. There are many reasons why these falls occur before and after supporting of the face. It is therefore important to support the exposed face as soon as possible to prevent the falls of ground. It is also very important to support the face with the correct support products and to support the face as designed and required by the mining engineers. The possible reasons for falls of ground, possible support methods and the products available will be discussed in this presentation. In typical conventional narrow vein stoping operations, the use of conventional temporary support components to offer some support to workers, whilst the permanent and generally more elaborate support system gets installed or constructed, still results in injuries to people. The author wishes to discuss the following items in this paper:- ? Introduction ? Basic face behaviour after exposure ? Controllable Parameters ? Mining Engineers support designs ? Primary and Secondary Support ? Products available for prevention of falls of ground

Jan 1, 2008

By J. A. Beukes, M. Marais

TICOR South Africa is a new titanium feed stock producer. In the Ticor South Africa plant the ilmenite feed to the smelter plant is roasted to enhance its magnetic properties. This allows for the magnetic separation of chromite from the ilmenite. The magnetization reaction relies on partial oxidation with both under- and over-oxidation causing insufficient magnetization. To subject the roaster plant feed material to the required physical conditions a circulating fluid bed (CFB) roaster is used. This paper describes the development of a laboratory model that will aid in the control of the CFB roaster.

Jan 1, 2003

By P. S. Pashkovsky, S. N. Smolanov

The essence of the method consists in creation of drop of opposite sign at the isolating stoppings, by which air losses through the accident district change direction of their motion. The period of reversal is selected in that way so that air may not find itself in the zone of burning. The method of fighting the fire considered was repeatedly used in the coal mines of the Ukraine. The theoretical basis of efficiency and two examples of use of this method by fighting the underground fires are adduced in the paper.

Jan 1, 2003

By Christopher J. Bambridge, Lee Seng Hoor

The Stormwater Management and Road Tunnel (SMART) Tunnel is a world first in the use of tunnel space transmitting both road and water through the same spatial envelope. The unique aspect of the SMART project is that the highway decks are used periodically for the conveyance of water. This aspect of the project has posed its own technical challenges that have been overcome in the design stage of the work allowing the project to be taken forward to construction with confidence in the systems to be Installed in the tunnel.

Jan 1, 2005

By AMIRA P588 Research Team

This contribution summarises new knowledge and data, obtained during a three year ARCAMIRA funded research project, on the mineralogical and geochemical characteristics of hydrothermal alteration associated with low sulfidation, gold-silver epithermal deposits. These data are used to develop exploration vectors for use at both deposit and district scales, plus techniques have been established to distinguish ore grade epithermal systems from barren or low grade systems. Deposits investigated were Ladolam, Papua New Guinea, Gosowong and Mt Muro, Indonesia, Cerro Vaguardia, Argentina and Bimurra and Twin Hills, Australia.

Jan 1, 2005

By Pengfu Tan

The control of converter slag chemistry and slag viscosity has played an important role in optimizing converter operations. A thermodynamic model of copper P-S converter and a viscosity model of converter slag have been used to predict the chemistry and viscosity of converter slag. The effect of oxygen potential, SiO2/Fe in slag, detection of slag blow endpoint, and temperature on slag viscosity, liquidus temperature of converter slag and skimming operation has been discussed. Some applications of the industrial operations have been presented.

Jan 1, 2006

By Andrey V. Tarasov

To carry out a physicochemical substantiation of a transition to ?soft? modes of reduction of calcine obtained by desulfurizing roasting of nickel concentrate produced as a result of copper-nickel converter matte separation in a nickel anode production circuit, an analysis has been conducted of the macrokinetic behavior of actual calcine samples in the presence of gaseous H2-CO mixtures and solid reductant additives. Within a temperature range of 900°C to 1100°C the main regularities typical of the calcine reduction process with individual gases (H2, CO) also take place when using a gaseous mixture. Under the conditions of low-temperature (900°C to 1000°C) nickel oxide reduction with products of fuel oil conversion in the presence of coke, the role of the latter is insignificant from the technological viewpoint. As a result of the present investigations, we have obtained analytical expressions of macrokinetic parameters of the reaction interaction within the [NiO] calcine-H2-CO-C-CO2-H2O-O2-N2 system.

Jan 1, 2005

The authors describe two stratiform intrusions within a two miles thick ophiolite belt, one of the many ophiolite (serpentine) belts of the eugeosynclinal sequences of the Kalgoorlie System (metamorphic age c.2700 million years). Unusually good evidence of gravitational differentiation involving cumulates for an Alpine type peridotite-gabbro intrusion has been obtained, in spite of modifications of the original igneous rocks imposed by regional metamorphism. Unmetamorphosed relics of cumulate rocks are a surprising feature of this occurIfence.'fhe differentiation process reflected in the layered sequences is compared to that of the Stillwater Intrusion, Montana. Phase, cryptic and rhythmic layering are recognized. The economic significance of this study lies not only in the possibility of nickel mineralization in this ophiolite belt, but also in that much detailed information on the nature of these belts, which is difficult to obtain in the case of the more altered and sheared rocks of the belts carrying gold and nickel ore deposits nearby, is gathered from the Yilmia occurrences.

Jan 1, 1969

By E. Piesch, M. Urban, G. M. Hassib

INTRODUCTION In radon dosimetry diffusion chambers with passive [a]-detectors are now in current use to investigate the long-term accumulated indoor exposure of radon and daughters. For the diffusion chamber developed at Karlsruhe the electrochemical etching technique (ECE) was applied to reveal [a]-particles in polycarbonate plastic detectors. Compared to conventional etching, the main advantages of the ECE are the large track diameter, simple track counting in a single field of about 1 cm2, stability of the latent tracks to humidity and temperature and ability for a long-term accumulation up to 1 year. The electrochemical etching system was designed to etch in one run about 101 foils by using a 200 W high voltage generator. The commercial available radon dosimeter system is applied for a country wide program of measuring radon in dwellings. Because of an increasing interest of radon monitoring in mines, environmental monitoring and personnel dosimetry the properties of several track etch detectors have been studied. In the comparative study, Makrofol E, LR 115 and CR 39 were used in the diffusion chamber to investigate the etching techniques, the relative efficiency, the measurable [a]-energy range, and the counting statistic for the measurement of radon concentration. THE KARLSRUHE DIFFUSION CHAMBER The design of the Karlsruhe diffusion chamber is presented in Fig. 1. The upper part of the chamber is closed by a fibreglass filter to separate radon from aerosols, heavy dust particles and radon decay products. Inside the diffusion chamber [a]-particles from radon and daughters are detected by two passive radon detectors, one on the bottom of the chamber and the other in front of the filter. With the fibreglass filter applied the diffusion time is about 1 minute for radon. Therefore, also short-term variations in the radon concentration are recorded by the track detector. Mainly because of the short halflife of thoron (56 s) only about 7 % of the thoron concentration is expected in the diffusion chamber. Radon monitoring provides the estimation of the long-term accumulated mean value of the radon concentration with a lowest detectable concentration of 0.1 pCi/1 after 3 months accumulation by using polycarbonate track etch detectors, an electrochemical etching technique and track counting in a single field of 1 cm2. The diffusion chamber was optimized for the polycarbonate track detector with respect to chamber geometry and detector position [1]. Table 1 presents data for 3 different diffusion chamber designs. The radon sensitivity of the diffusion chamber depends on the [a]-energy discrimination and the angular response of the [a]-track detector. The difference between foil No 2 and foil No 1 can be explained by an additional plate-out effect of radon daughters on foil No 3. The high sensitivity of foil No 3 compared to that of foil No 2 is caused by an increase of the effective volume and the effective area for [a]-particle from radon and from plated-out decay products, respectively. Additional experiments have been performed in order to investigate the electrostatic properties of the plastic material and the properties of the diffusion filter [1]. The properties of bare a-detectors were compared with those inside the diffusion chamber. In contrast to laboratory results, dust particles deposited on the detector surface or in the environment of the detector obviously affect the reproducibility of the bare detector significantly. After 4 months exposure in dwellings the scatter of 10 dosimeters exposed in the same room exceeds a factor of 3 compared to 15 % for the diffusion chamber. COMPARATIVE STUDY OF TRACK ETCH DETECTORS Detector types and evaluation technique In the comparative study the properties of the following plastic track etch detectors have been applied: - LR 115 from Kodak Pathé, France, is a red dyed cellulose nitrate layer of 13 µm thickness on a 100 µm thick polyester support. The holes appears as bright spots in a dark red background. In an optical microscope counting of through etched [a]-tracks which must penetrate the detector layer - CR 39 from Pershore, England, is an ally1 diglycol carbonate plastic of about 300 m thickness. The normal etched [a]-tracks are counted by an optical microscope and the ECE [a]-tracks by a microfiche reader.

Jan 1, 1981

By Steve Kral

Globalization was the key word for the mining industry during the 1990s, just as productivity was the key word of the 1980s. And globalization will remain the key word as the industry enters the 21st century, according to speakers at the Colorado MPD Meeting held in Colorado Springs, CO in May. The meeting, put on by the Colorado Section SME Minerals Processing Division, drew about 120 people to the Broadmoor Hotel. “Operating Globally” was the theme of the 49th annual conference. Speakers addressed the reasons why mining companies have limited their spending in the United States and have moved into Third World and developing nations.

Jan 1, 1999

By S. Kanai

Nodular piles is to be piles provided with several nodular projections along the pile shaft, as shown in Fig. 1. Nodular piles are usually installed through either driving method with hammer or preboring method. This paper presents that the bearing capacity installed through each method is considerably higher than that of cylindrical pile without nodules. This paper also proposes the statistically analyzed unique formulae of the bearing capacity of nodular piles.

Jan 1, 1989