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By C V. B Cunningham

The assessment of blasting results under production conditions is extremely difficult. As a result, it can take months or years to establish objective and valid estimates of explosive performance in achieving rockbreaking goals. This fundamental problem often results in decisions related to the manufacture, marketing, purchase and use of explosives being largely swayed by calculated energies from detonation codes. However, these codes are by no means standardised. Different energies are given by different codes because these employ varying combinations of fundamental science and empiricism. After a basic review of code operation, important guidelines to dependability are given with reference to ICI’S state-of-the-art codes IDEX and CPEX. Distinctions are drawn between Ideal, Non-Ideal and Blasting Codes. Concepts of explosive energy are discussed in brief.

Jan 1, 1991

By Cem Colakoglu

In this study, nickel containing iron alloys were produced by carbothermal reduction of lateritic nickel ores obtained from Manisa - Caldag region of Turkiye in order to investigate the reaction mechanism of nickel and cobalt. In the experiments, the lateritic ore containing 1.58 wt.% Ni and 0.12 wt.% Co was calcined in a semi-pilot scale rotary furnace at 1100°C for 1 hour. Then, a mixture of calcined ore and metallurgical coke was reacted in sintered alumina crucibles using a graphite resistance tube furnace at different time (0- 60 min) and temperature (1500-1600°C).

Jan 1, 2009

By R. Bitmead, R Barker, A. Drake

The opencut coal mine is located about 50 km west of Brisbane, the capital city of Queensland in Australia and produces about 140 000 tonnes per annum of high grade steaming coal utilising a small team (ten) of personnel to mine remnants of the Aberdare and Bluff seams left by previous underground mining. This, in itself, is not remarkable except that one of the seams has commenced spontaneously cornbusting resulting in temperatures in excess of 55’C commonly being encountered with portions of the p’it being wreathed in steam. To extend mine life, the mine required a blasting system that would: . Safely blast in temperatures below 100°C . Significantly reduce overall unit costs . Not increase the current vibration impacts on nearby housing . Not increase flyrock.

Jan 1, 2002

By C. M. F. Vieira

This work has as its objective to characterize ceramic bodies for vitrified tiles elaborated with the mixture of nepheline-syenite flux and kaolinitic clay. Formulations were prepared with 0, 30 and 50 wt.% of nepheline-syenite incorporated in a kaolinitic clay. To determine the physical and mechanical properties such as dry bulk density, linear shrinkage, water absorption and flexural rupture strength, specimens were prepared by 30 MPa uniaxial pressure-molding and then fired in a laboratory furnace at 1150oC. The microstructure of the fired ceramics was evaluated by scanning electron microscopy. The results indicated that the nepheline-syenite improved the evaluated properties of the clay and attended the specifications of vitrified ceramic tiles.

Jan 1, 2010

The cyclone, or centrifugal separator, ,is firmly established in industry as a low cost separator of solids from gases.While it will also separate fluids of different densities, and solids from liquids, its main use is to remove relatively fine dusts from gases whose pr~erties are generally not greatly different from those of air. This latter phase of operation is the one that will be dealt with here.The duty of such a cyclone separating system is to take in a supply of dusty gas and separate it into its components of dust and clean gas as perfectly as possible for the least consumption of pressure head. Any separation at all causes pressure loss and, in general, the greater the separation, the greater the pressure drop needed to effect it. The percentage of dust in suspension which is separated from the gas-dust mixture is commonly called the collection or separation efficiency. Overall or "true" efficiency must take pressure drop into account and may be considered as proportional to the ratio of the percentage of dust collected to the resultant pressure drop. For any cyclone It will vary with different dusts.Many commercial adaptions of the simple cyclone are made solely on the basis of pressure drop improvement, without taking into account the effect on separation efficiency, probably because the latter is so difficult to assess correctly. It appears unfortunate but true that the majority of such adaptions and patent gadgets fitted to cyclones which decrease pressure drop, do have an adverse effect on separation. In other' words, the true efficiency is seldom increased but often diminished.Without a knowledge of what actually goes on inside a cyclone, it is impossible fully to appreciate the real effect of a modification. For instance, it is on record that a cyclone...

Jan 1, 1949

By Russell R. McLellan

As part of an effort to develop new or improved placer mining technology in the Tertiary gold-bearing channel gravel of northern California, the Bureau of Mines conducted investigations at the old Badger Hill placer mine in Nevada County, Calif., to collect data and information regarding drilling and sampling methods and deposit characteristics. Sampling studies involved the collection and processing of 400 tons of large-and small-volume samples from drill holes, underground workings, surface pits, and blasthole rounds. A total of 355 samples averaging 2,296 pounds per sample provided reasonably accurate data for analysis of the gold distribution. These studies indicated that the bulk of the gold is within 40 feet of bedrock in stacked, lenticular zones of cemented gravel that are largely confined to the relatively narrow, meandering course of the deepest portion of the bedrock channel. Drilling studies involved the testing of truck-mounted rotary, buckett and vibratory drills, none of which proved to be a completely versatile tool for sampling quickly and reliably both consolidated and unconsolidated gravel..

Jan 1, 1974

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 G. W. Tracy, R. D. Carter

Numerical calculations were made to determine the behavior of reservoirs with high-pressure drawdown and wide well spacing where the initial productivity is low and the wells are completed by hydraulic fracturing. The two-phase flow equations were solved for the flow into a single well. This well was assumed to be producing from a reservoir with hydraulically created horizontal fractures (four different systems with fractures were studied). For comparison purposes, additional two-phase flow calculations were made assuming a reservoir with uniform rock properties. The two-phase flow results were also compared with the conventional calculation methods, which do not include the effect of saturation gradients resulting from a simultaneous flow of oil and gas which are normal to this type reservoir. It was found that the conventional methods predict (1) a high and too optimistic value of ultimate recovery, (2) a high producing rate and a high reservoir pressure at a given oil recovery and (3) a low trend of gas-oil ratio with oil recovery. Included in the two-phase flow calculations were provisions to control the oil production rate by an allowable rate and, also, by a gas-oil ratio penalty rule. For the systems with hydraulic fractures, the producing rate was controlled by the gas-oil ratio penalty rule for most of the life. This is in contrast to the system with uniform rock properties which went "on decline" almost immediately. An unexpected characteristic of the systems which included fractures was the early rise in producing gas-oil ratio from 730 cu ft/bbl to approximately 1,200 cu ft/bbl, followed by a "leveling off" before the normally expected gas-oil ratio rise began. Additional features which are a result of hydraulic fracturing are (I) greater ultimate recovery, (2) higher average producing rates and (3) a lower average reservoir pressure at a given oil recovery. INTRODUCTION Some oil fields discovered during the past few years are producing from certain volumetric ally controlled reservoirs (often referred to as solution or internal gas- drive reservoirs) which are characterized by high-pressure drawdown at the wells. Since the available pressure drawdown at a well is limited by the static reservoir pressure and the producing rate is controlled by the available drawdown, wells completed in this type of reservoir usually produce at a rate less than the allowable from the time of completion. Because of this, this type of reservoir is referred to as a low productivity reservoir. Economic considerations require the use of wide well spacing and well stimulation by hydraulic fracturing to make commercial wells in this type of reservoir. Performance predictions for volumetrically controlled reservoirs have been made using a combination of two standard equations. 1. The "Schilthuis" or "Muskat" type material balance equation is used to relate the average reservoir pressure and the cumulative oil recovery. 2. The results from the material balance equation and the productivity factor as described by Pirson' are used to relate the cumulative recovery with producing rate and time. The material balance equation assumed uniform pressure and liquid saturation conditions throughout a reservoir. The steady-state radial flow formula allows for a pressure gradient toward a well but assumes uniform liquid saturation. These calculation methods are adequate for application to reservoirs wherein the drawdown at the well to realize satisfactory producing rates is small compared to the total pressure. In low productivity, volumetrically controlled reservoirs, the pressure drawdown at the well is large cornpared to the total pressure. Although a precise number cannot be given for the magnitude of a large pressure drawdown, values in excess of 1,000 psi would definitely be included. For practical considerations, this usually occurs when the formation flow capacity is less than about 100 md-ft. However, this limit of formation flow capacity will vary with the well producing rate. The low pressure in the neighborhood of the well which results from a high drawdown causes evolution of large volumes of gas. This causes the gas saturation to be higher near the well than at a greater distance—-hence, a non-uniform gas saturation. Also, the relationship between the relative permeability to oil (K/K) and gas saturation is nonlinear but decreases approximately in an exponential way with increases in gas saturation. Because of this, the following chain reaction is established.

By Jay Rodgers

There has been a longstanding acceptance that burden plays a major role in the magnitude of ground vibration amplitudes generated from surface blasting. Much of the data that this belief is based upon is empirical in nature and may or may not represent an example of false inference. Recent published reports have rightly questioned the influence of burden and confinement on blast vibration amplitude, suggesting that the fracture condition of the rock mass is a better indicator. The increased investment in electronic detonators as a tool to control ground vibration amplitudes demands an understanding of vibration production detailed enough to make use of the vastly improved timing accuracy that they provide. A more accurate relationship may be found if we strip away the assumptions of the past and search for the underlying mechanism of vibration production in surface blasting. We must answer the question: What happens at or near the borehole when an explosive charge detonates that produces ground vibrations?

Jan 1, 2003

Study on the New Flow Sheet and Wastewater Recycling for Xiaoliuguo Copper-Bearing Low-Grade Scheelite Ore

Sep 13, 2010

Several years ago, Hudco Industrial Products began experimenting with the idea of levitating a conveyor belt with a film of air, much like the puck on an air-hockey table. While conducting its research, the company found out that some Russian and Dutch companies attempted the concept during the 1970s. After studying those conveyors, Hudco determined that its design was better. The Hudco advanced air-supported conveyor consists of an air-tight plenum, or chamber, that runs the length of the belt. The topside of the plenum has a formed trough. It corresponds to the profile of conventional troughing rollers. Low-pressure air is provided to the sealed plenum from a low horsepower blower. This pressurized air is metered and released through the central portion of the trough and reacts against the underside of the belt. The differential pressure between the top and bottom surfaces creates the lift to support the loaded belt. Airtight covers are installed to seal the transported materials in the plenum trough.

Jan 1, 2002

By S. H. Jason Choi

The Systems Conveyance and Operations Program (SCOP) is being implemented to convey tertiary-treated effluent to Lake Mead near Las Vegas, Nevada. The Reach 3 Tunnel Project is part of SCOP. The tunnel?s planned location along and across the Las Vegas Wash creates challenging tunneling conditions. A number of feasible excavation and initial support methods are being considered during the final design stage. This paper describes how the tunnel construction options were refined based on anticipated tunneling conditions and compatibility between tunnel excavation and initial support methods. A brief description of the most significant characteristics of the anticipated ground conditions is included for the purpose of discussion.

By experience we know about the natural event of ocean-tides. In geophysics we say that the earth-tides phenomenon is the elastico-viscous response of the earth's body to the attraction potential of moon and sun. By the fact that the tides on the planet take place in a regular periodic frequency, due to the earth rotation of 24 houres for one cycle, the rotation of the moon in about 28 days around the earth and finally to the rotation of the earth-moon combination around the sun in 365 days this phenomenon is a very important one in geophysics. The exact calculation of the acting forces is possible and the comparison of the earth's body response to these forces as well.

Jan 1, 1987

Coking coals are very much in demand on a world wide basis, particularly the higher rank coking coals, which form an important part of many coking blends and which represent the smallest portion of the world'scoking coal reserves. Conventional coke oven plants, using these coals, will predominate at least until the next century.Blending schemes for conventional coking require definition of the basic properties of coals so that the factors influencing the carbonization behaviour may be assessed. Several concepts, which are relatively simple, ate available to help promote a better understanding of the bask factors controlling -coke strength and are also useful in suggesting possible lines to follow in the blending of coals for coking.The interpretation of carbonization behaviour and coke structure in terms of petrographically defined coal rank and type provide a basis for planning and exploitation of coal Teserves. The optimum parameters for coking are suggested as follows.1. Type- Vitrinite content (% m.m.f. by volume) 55 ± 5%2. Rank- Mean maximum reflectance of vitrinite 1.30 ± O.10% Carbon content of vitrinite (% d.m.m.f.) 87·5 ± 1·0%The value of a coal should be assessed in relation to all its possible uses in blends. This is a more realistic and productive approach, as compared with considering coals only in relation to the results of blending with"good" coking coals. Blending schemes have been outlined to assist in the assessment of the blend potential of coals of all ranks and types.Reserves of higher rank coking coals in N.S.W. are very limited and should be conserved by blending with the low rank coking coals, of which there are large reserves.Examination of blending theories in relation to N.S.W. coals suggest that blends in the broad categories of minimal downgrading of the higher rank N.S.W. cok...

Jan 1, 1972

To form a true picture of the early history of Queensland, we must think of white settlement advancing like an incoming tide, wave by wave; each wave lapping ahead a little further than the last. The credit for opening up the country belongs to a large number of pioneers, each of whom pushed out just a little further than his predecessors.Contrary to what one might expect, Rockhampton district was settled by overlanders from the south and not from the ocean side. When the Archers, the pioneers of the Rockhampton district, reached Gracemere in 1853, settlement had already made its way down the valley of the Dawson River; for it was from Leith Hay's station at Rannes (a few miles below Mount Morgan) that the Archers advanced northward into the unknown, to find the river that the explorer, Ludwig Leichhardt, had told them must enter the sea somewhere near the Tropic of Capricorn.The Archers travelled northward from Rannes up the valley of the Dee, coming out on the edge of the Razorback Range not very far from the point at which the Dawson Valley Highway drops over into Poison Creek. (Their diary records the bearings from a lookout point to various peaks around Rockhampton, and to-day, by plotting back from these peaks, we can determine the exact spot at which they descended on to the Fitzroy Flats.) We can be certain, then, that they must have been the first white men to set eyes on Mount Morgan; though to them it would have seemed to be nothing more than an insignificant hill...

Jan 1, 1939

By Ron Millions, J. A. Folinsbee, Ishwinder Grewal, Michael Fullam, Don Strickland, Tony Y. Chong

"Since milling began in 1912, the Dome mill, now part of the Porcupine Joint Venture (PJV), has been expanded several times, the most recent increasing the milling rate from 3,500 to 11,500 tonnes per day. Dome uses conventional crushing and grinding followed by gravity concentration to recover free milling gold. A cyanidation/CIP process recovers the remaining gold in the gravity tails.Over the past few years, continuous gravity improvements have increased the gravity recovery from 20% to nearly 50% of the plant feed gold. This paper describes some of the factors that have contributed to this dramatic increase, and suggests how gravity recovery can be further improved. Gravity circuit availability has been improved to >98% with the implementation of a preventative maintenance program. More Knelson concentrators have been added to the circuit, and in 2002, an Acacia Intensive Leach Reactor was installed to replace the shaking table. In 2003, the entire gravity circuit was audited to evaluate and quantify the circuit performance. The metallurgical and mechanical operating conditions of the gravity circuit are now well understood, and areas for further improvement are well defined.INTRODUCTIONThe Porcupine Joint Venture was formed in 2002 between Placer Dome Inc. and Kinross Gold Corporation. One of the goals of the JV was to use the milling capacity of the Dome mill to process ore from Placer Dome and Kinross mines in the Timmins Camp. The PJV Dome Mill utilizes gravity concentration, cyanide leaching and carbon in pulp gold circuits to recover gold. Gravity recovery has been used in some form at the Dome Mill for most of its existence, first using conventional jigs, these being replaced in 1993 by two Knelson Concentrators, one for each of the two grinding circuits in the Dome mill. Over the years more concentrators have been added to improve the gravity recovery, most recently in 2002 for a current total of five. Also in 2002, an Acacia Intensive Leach Reactor was added to process the Knelson concentrate, replacing the shaking table."

Jan 1, 2004

By C G. Ryan, T P. Mernagh, S R. Hunns, R A. Both, R R. Large, J B. Gemmell

 The Hellyer and Mt. Chalmers deposits are mound-style volcanic-hosted massive sulphide (VHMS) deposits in Australia. Textural, petrographic and microthennometric investigations of fluid inclusions in the Hellyer stringer system indicate that Type I, primary, liquid-vapour inclusions are 10 - 15 J.UIl in size, and yield homogenisation temperatures of 170 - 220¦C in early 2A veins, 165 - 322¦C in main-stage 2B veins and 190 - 256¦C in late-stage 2C veins. These data suggest a waxing and waning thermal history. However, the average salinity remained between 8 - 11 NaCl equiv. wt % in all Stage 2 veins. At Mt Chalmers, Type I inclusions up to 20 urn are found in quartz from the mineralised zone, and these inclusions yielded homogenisation temperatures of 160 - 268¦C and salinities of 5 - 8 NaCl equiv. wt %. Laser Raman spectroscopic (LRS) analysis indicates the presence of CO2 (<1 mole %) in the Hellyer and Mt. Chalmers VHMS systems. Semi-quantitative SEM/WDS microprobe analyses of fluid inclusion decrepitates indicate that the Hellyer and Mt Chalmers ore fluids were enriched in potassium and calcium but depleted in magnesium relative to seawater. PIXE microanalysis of fluid inclusions in quartz also indicates a significant base metal concentration in these fluids. Cation composition and higher salinities relative to seawater suggest that recycled seawater alone cannot be the sole source of the ore fluids. High base metal content and the presence of CO2 in the fluid inclusions imply that magmatic input of ore metals during seawater leaching of the footwall volcanic pile is a distinct possibility.

Jan 1, 1995

By William M. Gleason

Hard times continued to plague the industry when the calendar rolled over to 2000. During 1999, the United States economy had grown vigorously, capping the longest economic expansion in United States history. However, the mining industry was not so fortunate. Commodity prices remained in a slump in the “new-economy” that was fueled by excitement and speculation about the power of the Internet during the infancy of the Information Age. Much of the investment money that once went to mining and exploration was now headed to the world of virtual gold mines. SME President Donald E. Ranta implemented new technology into his plans for SME. His two major goals were new membership growth and to foster the establishment of the comprehensive Internet presence for the Society’s technical information. His strategic priorities included enhancing the quality and quantity of publications, programs, meetings and short courses. “The Internet is the vehicle that will advance the priorities,” he said.

Jan 1, 2007

By S. C. Brown

A number of studies have suggested that microscale asperities enhance bubble-particle attachment efficiency; however, in practice the roughening of particulate surfaces can also lead to a decrease in flotation. In the present investigation, it is proposed that nanoscale asperities may be partially responsible for this phenomenon. It is suggested that as inter-asperity separation distances are reduced capillary effects are enhanced leading to the formation of stable liquid domains, which adversely impact bubble-particle adhesion. In addition, obstruction of surfactant self-assembly may occur, further limiting flotation.

Jan 1, 2003

By C. W. Owings

A few of the more progressive mining companies have taken precautions to safeguard employees or man-trips. Specially constructed men-cars -have been provided with special devices or mechanisms to stop the cars on slopes, if the hoisting cable should break. Cars have been equipped with safety chains to connect and hold them together if a coupling should break. Steel frames covered with heavy wire netting have been placed over cars to reduce injuries to the riders from roof fails on slopes. A safety cable passing from the front car to a point above the cable socket on the slope hoisting cable is used frequently as a precaution in case the socket loosens o the main cable breaks at the socket. Such devices are commendable, but the percentage of man-cars and man-trips protected is relatively small - entirely too small. Man-trips that travel level haulage roads are rarely protected safety devices, and haulage roads are seldom inspected by mine officials to determine the condition of roof and ribs.

Jan 1, 1935