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By L Lorenzen, H Muller, L Bernard

Australian companies and consultants are becoming ever more involved in projects in African, South American, East European and Middle Eastern countries. However, significant differences in culture and approach to projects sometimes make these projects challenging for reasons that are not purely technical. Often the challenges are rather related to how the project owner and local authorities perceive the reality. These perceptions and sometimes unrealistic expectations regarding project costs and potential outcomes need to be addressed by the æWesternÆ project developer and consultant.This paper will discuss the specific experience of Snowden in studies commissioned by companies from such countries for the development of very large, low-grade gold deposits in some of the most inhospitable areas in the world. The paper will further review similar projects undertaken in other ænew worldÆ countries and compare these to the initial Snowden experience.As the process operating costs of operations in many of these countries are extremely competitive when compared to the typical Australian operating costs, the paper will review the operating costs and the factors which may be pertinent to a large project of this nature, both in the Australian and the ænew worldÆ context. Will Australian-based operations be able to compete in the global gold market when the gold price softens again, as it will do at some stage in the possibly not-so-distant future?CITATION:Muller, H, Lorenzen, L and Bernard, L, 2013. Challenges of developing low-grade deposits in ænew worldÆ countries from a mining consultantÆs perspective, in Proceedings World Gold 2013 , pp 307-314 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

By Edward (Ted) Dowey

City Water Tunnel No. 3 is being built in order to provide a redundant system for delivering 4,542,500 m3 (1.2 billion gallons) of water per day throughout the five boroughs of New York City. The present tunnels, City Tunnel No. 1 and 2 (Figure 1), were put in service in 1917 and 1936 respectively, and both have been in continuous service. Tunnels No. 1 and 2 can-not be shut down for inspection or repair until City Tunnel No. 3 has been completed. City Tunnel No. 3 has two stages (Figure 1).Stage One is 20.1 km (12.5 mi) long and is presently delivering drinking water to the boroughs of the Bronx and Manhattan. Stage Two consists of the Brooklyn-Queens Tunnel 17.7 km (11 mi) and the Manhattan Tunnel 14 km (9 mi). The Brooklyn-Queens leg is complete and is set to be put in service soon. The Manhattan Tunnel is being constructed and is the subject of this paper. The Manhattan Tunnel (Figure 1) is comprised of three legs: the north, south and east legs. The con-tract includes the excavation of 8,976 m (29,500 ft) of tunnel and the lining of 14,561 m (47,773 ft) of tunnel. The south tunnel, 5,705 m (18,720 ft), was excavated but not lined, under a previous contract. The tunnel ranges from 181 m (600 ft) to 152 m (500 ft) in depth in the bedrock under Manhattan. The tunnel contract also includes the construction of nine new shafts, 161 m (530 ft) average depth, and the completion of a tenth shaft (the previously built construction shaft). The Manhattan Tunnel contract was awarded to the sole bidder Schiavone/Shea/Frontier Kemper Joint Venture (SSF) for $668,532,680.00, on January 31, 2005. The Manhattan Tunnel was designed ?in house? by the New York City Department of Environmental Protection (DEP) and the construction management was provided by a combined staff of the DEP and a joint venture of Jenny Engineering and URS.

Jan 1, 2008

By Patrick A. Turner, Timothy J. Olson, Abraham J. Schutte, Roman van Ommen

"The use of classifying devices in grinding circuits dates back to the early 1900’s when classifiers were installed to close ball mills. The search for ways to further improve grinding circuits led to the use of hydrocyclones in place of mechanical classifiers in South Africa in the early 1950’s. Today Hydrocyclones are considered as the best classifying devices to close grinding circuits. After 50 years of development the hydrocyclone has changed significantly when compared to the designs of the early days, but the focus to circuit optimization must be expanded to an understanding of the integral system consisting of mill, cyclone feed pump and cyclone.The key to good cyclone circuit design and operation in primary grinding circuits will be discussed including individual cyclone design features such as cone angle or materials of construction, as well as orientation and manifold configuration.Cyclone performance issues as well as maintenance considerations will be detailed in an effort to achieve consistent cyclone operation with minimal coarse solids in the overflow. “The importance of constant cyclone feed conditions is unquestioned today. The challenge of Cyclone sizing is a large number of not fully known variables prior to startup. The most significant unknown variable is slurry viscosity. Because of this, engineers often specify a conservative cyclone system that produces a finer than required separation. However, this approach often leads to higher circulating loads and a higher overflow density in order to produce the required separation. The higher cyclone overflow density results in a less efficient cyclone separation. The average concentrator can pick up 2-4% finer overall grind by having a more aggressive cyclone operation.”"

Jan 1, 2003

By M. T. Spyridopolous, S. J. Neethling

"There has been a significant research interest in the stability of single thin films, including prediction of their failure based on disjoining pressure and film thickness experiments and DLVO theory. It is, however, notoriously difficult to correlate information on the failure of a single thin film with measurements of foam stability. This is particularly true for the prediction of dynamic foam stability indicators, such as equilibrium froth height and surface bubble size.An alternative experimental approach to studying single thin film failure for predicting foam stability is to measure directly the coalescence probability between two approaching bubbles in a surfactant solution. These experiments can be performed under different chemical and physical conditions by using a micromanipulator that allows variation of bubble size, surfactant concentration, approach velocity and stationary position. The interface radius of curvature, the time to coalescence and the film area between the bubbles can be measured directly using image analysis.In a foam, the force exerted on the thin film separating two bubbles depends on the local radius of curvature of the Plateau borders and vertices, which depends in turn on the local liquid content. Results from different bubble sizes in the micromanipulator therefore translate into regions of different liquid content in the foam. Small bubbles, having a high radius of curvature correspond to the low-liquid content (Polyhederschaum) region higher in the foam, and large bubbles to the wetter (Kugelschaum) region closer to the liquid-foam interface. Experiments with different holding distances between the bubbles correspond to differences in bubble size in the foam, as the size of the film between the bubbles varies."

Jan 1, 2003

By Nick Lewis

Farce Mining of Texas is a surface coal mine located in Laredo, Texas. Farce mines and sells approximately 600,000 tons /year of bituminous coal. A map showing the location of Laredo is provided in Figure 1. As shown, Laredo is located on the border between the United States and Mexico. The mine property runs to the Rio Grande River, the border between the two countries. Farce pumps water from the Rio Grande for use in their coal preparation plant. Laredo’s climate is quite dry with annual rainfall averaging about 12” per year. Also, due to the southern location, Laredo is quite hot. It is common for the temperature to reach 100” F in March and maintain these temperatures through September.

Jan 1, 1994

By Harri J. Lehto, Marja I. Oja

"The purpose of grinding circuits is to produce a particle size distribution that has as much as possible the wanted particle size class. In practise, however, the production of the wanted size class is not at all as simple as it sounds. In the case of industrial minerals for example the end user may give very tight specifications for the particle size distribution and for the chemical composition of the product. This leads in many cases to a very demanding grinding process, if we want to reach and maintain these specifications. In other words, the required size distribution is not necessary the best possible for the chemical composition.Screen models aim to predict the size distribution and flow of the products when a feed size distribution, feed tonnage, and grade efficiency curve are known. The approach used in this study was to select the most suitable empirical model for classification. Suitability of the existing models has been evaluated and accuracy compared. The tests showed that best grade efficiency model was the Rosin-Rammler model.The performance of a screen was evaluated in order to minimize the amount of fine material in the screen overflow. The experiments were carried out using Derrick single-deck screen, first alone with recycling and then in the closed circuit with a rod mill using two different scales. The separate screen tests showed the expected behaviour of the grade efficiency curves. In the pilot tests the Leonard screen efficiencies stayed almost constant. This suggests that the screen works better in a milling circuit. However the loading of the screen turned the product of the mill coarser that helped screening. The grade efficiencies obtained from the pilot tests had the same general shape. The regression analysis of the pilot test runs did not give an acceptable correlation for the parameters. This suggests that pilot tests cannot be directly used to scale or to optimise industrial milling circuits. However they can be used to predict the trends of behaviour of an industrial circuit."

Jan 1, 2003

By Chen Shuwen, Yao Zhihua

In the process of thickening dewatering_the motion state of two- phase flow in a thickener has a very great influence on thickening efficiency. The investigation was made using copper mill tailings. In this investigation the authors explored the formation conditions and motion range of density current in the thickening process by model experiments, and analyzed the influence of density current on thickening efficiency. The results have shown that the formation of density current has relations with the structure parameters of a thickener and thickening process. The density current and its forming location affect thickener’s working efficiency. The author measured the motion state of two- phase flow in a 53-m dial. thickener for copper mill tailings under its operation conditions and analyzed the density distribution and motion state of two-phase flow in the thickener. The results obtained by the industry tests have shown that the motion state of two- phase flow in the thickener can be greatly improved by modification of its structure, achieving a great improvement in its thickening efficiency. It is concluded that, a thickener’s working efficiency depends on the formation and motion range of density current in it, which is of great importance to designing and establishment of thickener’s working parameters.

Jan 1, 2003

By Christopher Davey, Marian Mazurkiewicz, Yvonne Spooner, Dana Hankey, Peter Kanjorski

The concept of a high pressure liquid jet mill with highly unsteady flow, has been developed and recently patented by Cornerstone Technologies LLC (CsT), for the purpose of micron and sub-micron particle production. The mill accepts feed sizes up to 15mm for some materials and is capable of submicron production. Successful material range from precious metals such as silver and palladium to dielectric components and substrates such as Barium Titanate slips, zirconia, titania and silica. The process has also succeeded in adequately reducing the size of materials for both composite and coating uses such as anthracite coal, graphite, chrome metal, wollastonite and more than 100 others. A unique design approach has been taken to highly maximize the energy flux in the mill's chambers to create extremely high turbulence and destructive cavitation. This is assisted by shock waves, which cause particles to undergo ultra high frequency pressure pulsations, high frequency collisions and then abrasion, shattering, hydrowedging, and cleaving. Due to these extreme properties the processing occurs in just fractions of a second allowing throughputs up to 1000 kg/h on a machine that would fit inside a 60 cm box. The technical solution and technological advance, as well as the environmental and economic benefits indicate rapid and wide spread acceptance of high-pressure liquid jet milling in modern industry.

Jan 1, 2003

By S. K. Gilman

Zircon (ZrSiO4) sand production of about 1.1 Mt/a(1.2 million stpy) predominates the global supply of zirconium minerals. Baddeleyite (ZrO2) contributes less than 1 percent of supply. Zircon is almost exclusively produced as a co-product from the mining of titanium minerals, mainly from mineralized beach sands. In 2004, there were a number of new projects under consideration that were more dependent on zircon revenue than for titanium minerals. This reflected sustained higher zircon prices and forecast ongoing supply shortages in the absence of major new discoveries.

Jan 1, 2005

By Scott Orenstein

Construction blasting has allegedly been the cause of property damage in the following situations: (1) When the detonation of the shot hurls rock and debris into the air that causes property damage upon impact; and (2) When property owners notice cracks in their walls and foundations after they experience the momentary vibrations that coincide with the detonation of the shot. The current state of the law for both these situations is firmly established. Blasting is classified as an abnormally dangerous activity, for which the blaster is held strictly liable, whether the damage is the result of flying debris or vibrations and concussions generated by the blast. It is when the alleged blasting damage is supposedly from concussions and vibrations, however, that the courts usually reach the wrong result. The typical scenario involves property owners that thoroughly investigate their property after feeling blast generated vibrations, and find cracks that they believe did not exist beforehand. Most often the truth is that the property owners have never noticed these cracks before because they have never looked that closely before. Any structure has a certain number of cracks due to a variety of causes, such as settlement overtime and temperature and humidity changes.

Jan 1, 2004

By Joseph L. Fournier

Suncor Oil Sands employs delayed coking technology in converting bitumen into synthetic crude oil. Currently up to 10,000 m3 of delayed coke (coke) is produced per day as a byproduct of the upgrading process, of which up to 9,000 m3 per day is placed in dry storage on Lease 86/17. A review was completed to examine the case history of leachate potential experiments from the dry storage of coke and the environmental relevance of coke leachate studies conducted over the past decade. The review included an evaluation of the potential impacts of environmental conditions within the location of coke storage, including precipitation pH, as well as daily and annual ozone trends. Coke leachate potential has historically been characterized using standard leachate testing protocols (i.e., TLCP, SPLP) together with other studies that have employed strong acids and oxidizing agents in the extraction fluids. The present paper highlights prevailing conditions in the Athabasca Valley air-shed with emphasis given to ambient ozone (oxidizers), as well as precipitation pH and acid input deposition rates, and will demonstrate that TCLP / SPLP tests lack the intended environmental relevance relative to the conditions under which coke is stored.

May 1, 2011

Mining at Waihi on the Martha Hill commenced in 1878 and between 1892 and 1953 produced 35 million ounces of bullion from some 13.5 million short tons of ore from 40 named quartz reefs. The general geology of the ore is recorded in detail with differing interpretations by Bell and Fraser (1912) and Morgan (1924). The reefs and stringers have formed by fissure filling and replacement in mainly quartz andesite dacite flows within the Waihi 'Graben'. The host rocks are extensively propylitised with intense alteration forming zones of kaolin adjacent to the main reefs.

Jan 1, 1979

By P. T. Slatter

The efficient and accurate design of pipe and pumping plant for non-Newtonian mineral slurries remains a problem. The objective of this paper is to present the development of the Balanced Beam Tube Viscometer (BBTV), an instrument which could facilitate more accurate design for these slurries. The background of rotational and tube viscometry is reviewed and the fundamental principles and inherent advantages of the BBTV are given. The design, data acquisition and processing techniques are introduced and results showing the reliability of the new instrument are presented and discussed. It is concluded that the BBTV is a reliable and versatile instrument for both routine analyses and research work, and has the potential to provide data for the refinement of the design procedure for mineral slurry pipe and plant design.

Jan 1, 1998

By F. Y. Kang

There are rich resources of natural graphite in China. It would be a good opportunity to upgrade national graphite industry if natural graphite with modification is used in lithium ion battery. Micro-crystalline graphite in high purity was coated with a carbon film on the surface. The initial cycle efficiency was improved to be 89.9% and cycle stability was remarkably improved. The experiments proved that microcrystalline graphite with carbon coating have excellent electrochemical performances at low cost as anode materials for lithium-ion battery. In addition, H2SO4-GIC technique was used to prepare the natural flake graphite powders with mild-exfoliation. Sub-micro and nano pores were found in the graphite samples. In correspondence the reversible capacity, rate capacity and cycle life were improved, which would meet the demand of high-power lithium-ion battery. Natural graphite is the most promising anode material for large-scale lithium-ion batteries. The demand of modified graphite grows up greatly in the market. Microcrystalline graphite with surface coating and flake graphite with mild-exfoliation are the promising commercial anode materials for the industry of lithium ion battery.

Jan 1, 2014

By O. Matwijenko

"The Kidd Creek concentrator is located twenty-six kilometres east of Timmins, Ontario, within a metallurgical complex including a 109,000 MTPY zinc plant and a new 59,000 MTPY copper smelter and refinery. A complement of 159 persons is employed in the operation of the concentrator.Ore from the Kidd Creek Mine is crushed underground to minus 15. 0 cm, then transported twenty-seven kilometres by rail 1:0 the concentrator. After being crushed to minus 1. 6 cm, the ore is further processed by grinding and flotation.The concentrator commenced operations in November of 1966 at a designed capacity of 8,200 MTPD. Two parallel flotation and grinding circuits treated copper-zinc ore (2.28% Cu, 5.63% Zn) and a third treated silver-copper-lead-zinc ore (230 g/MT Ag; 0.57% Cu, 0.88% Pb, 7.89% Zn).By 1975, the concentrator was treating 9,100 MTPD of ore. Seven concentrates were being produced, namely, high silve1: copper, low silver copper, lead, low silver zinc, high silver zinc, pyrite and tin.Planned minesite expansion to a second underground mine required increased concentrator throughput. Expansion of the concentrator enabling a thirty-three percent increase in copper-zinc ore throughput occurred during the period 1975 through 1978. This expansion included increased load-in capacity, major redesign in the crusher house, the addition of a fourth grinding and flotation circuit, the building of a fourth dryer, and numerous expansions of services."

Jan 1, 1980

This backgrounds the methods, and technical terminology, of digital image processing techniques used to write out remote sensing imagery.

Jan 1, 1983

A Life Cycle Assessment (LCA) of stainless steel production, including that of the nickel, ferronickel, ferrochromium and iron feedstocks was carried out using inventory data derived from the literature. The environmental impact categories considered in the study were Global Warming Potential (GWP), Acidification Potential (AP) and total (or full cycle) energy consumption. The effects of different sources of electricity (black coal, natural gas and hydroelectricity) were also examined in the study. The results of the LCA showed that when ferronickel is used as the nickel source, the total energy consumption for stainless steel production is approximately 50% higher than when nickel metal is used as the nickel source (75 MJ/kg cf. 49 MJ/kg). This result comes about largely because the Fe units in ferronickel have a much higher energy intensity than do the Fe units in pig iron, and the greater the use of the former at the expense of the latter, the greater is the total energy consumption. The results also showed that the production of ferronickel made by far the largest contribution (59%) to the total energy consumption for stainless steel production when this feedstock is used as the nickel source, but when nickel metal is used as the nickel source the contributions of the various stages are more evenly distributed. It was also observed that the electricity consumption of the electric furnaces used in the production of ferronickel, ferrochromium and stainless steel contributed approximately 50% to the total energy consumed in stainless steel production. Given the relatively low efficiencies associated with electrical power generation, significant reductions in the total energy of stainless steel production could be anticipated if more direct use of thermal energy was made in the ferronickel, ferrochromium and/or stainless steel smelting stages, for example by utilising bath smelting processes.

Jan 1, 2004

The U.S. Code of Federal Regulations (Title 30) requires that a methane monitor be placed on every mining machine to continuously observe and record methane levels at the face. The monitor must provide a warning whenever methane levels are 1.0 percent or higher. An effective monitoring system will indicate a methane concentration of 1.0 percent on the mining machine before methane levels at the mining face reach 5.0 percent. Where the methane monitor is located on the mining machine is one of the most important factors that determines how effectively face methane levels can be predicted. Any change in the sampling location will result in a change in measured methane concentration. To protect the methanometer, it is usually located on the cutting boom at least 1 to 1.8 m (3 to 6 ft) outby the front cutting bits. A face ventilation system using blowing tubing was simulated in a full-scale test facility. Methane released from the face area was monitored at multiple locations on a model mining machine as well as locations near the face. Based on the relationship between concentrations measured on the machine and at the face, criteria were developed for selecting the best machine locations for monitoring methane. Recommendations are given for revising methane action levels for alternative sampling locations.

By R. H. Church, William E. Webb, Walter E. Pittman, James R. Boyle

As part of the Bureau of Mines health and safety research program, a short-range locator system, capable of locating miners who have become trapped following a mine accident, has been devised, The system consists of a lightweight, low-power radio transmitter incorporated into a miner's cap lamp battery and a directional receiver carried by rescuers. Prototype transmitters have been constructed, and the propagation of their signals has been investigated, The detectability of the signal in underground coal mines has also been investigated, This research indicates that a short-range location system would serve as an economical and practical means of locating miners from within the mine following an accident,

Jan 1, 1984

By W. J. Taylor

Nature has furnished us with fuel in three forms, solid, liquid, and gaseous; solid, the most common; liquid, containing the greatest energy; gaseous, the most convenient for use. The tendency of the day is to the conversion of solid and liquid fuel into the gaseous form. There is magic in the word gas to many men who through ignorance or indifference imagine that by mere conversion into gas an immense quantity of energy can he added to fuel of other forms, forgetful of the law of nature, that. the conversion of any substance from one form to another involves a loss of effective energy, and therefore that if in certain cases more duty can be obtained out of the gas resulting from a given amount of coal than the coal itself will supply when used direct, the cause lies solely in the more efficient utilization of the fuel in its gaseous state. Nevertheless, new processes for making gas are constantly crowded upon our notice with claims of less cost for manufacture and delivery than natural gas, and often of far more energy for the product than is contained in the coal or oil from which it is made. I was recently asked to examine a new process of this kind. From an analysis shown me the calorific energy of the gas approximated 375 heat-units per cubic foot; on ascertaining the quantity of gas claimed to be made from a given amount of solid and liquid fuel, it appeared, that for every 325 heat-units contained in the latter 900 heat-units were alleged to he delivered into the gas, or nearly three times as much energy as the original fuel really held. The extravagant claim of some oil-gas advocates is still frequently heard, that by vaporizing oil with steam and then passing the mixture through a coil of hot iron pipe, an oil-water-gas containing 26,600 heat-units is formed from 1 pound of oil carrying originally 21,000 heat-units, while the only energy expended on the gas has been by the introduction of a -little steam and a little extraneous heat. Theoretically, 1 pound of oil converted into water-gas carries 26,600

Jan 1, 1890