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By H. R. Thorpe

A floating gold dredge operating in coarse alluvial gravels of the Grey River on the west coast of the South Island, New Zealand, generated high concentrations of clay and colloidal particles in the dredge pond, which entered the groundwater system. Sampling was carried out at depths down to 20 m and it was found that variation of the length of the flow path occurred because of the movement of the dredge towards the piezometers. The alluvial gravels, the suspended sediments, the groundwater system and the water chemistry were all studied. Sediment concentrations were found to be highly variable with depth, but the relative concentrations in the depth profile were generally consistent as the flow distance shortened. The sediments were extremely fine and travelled further through the gravels than predicted. Comparison of field results with the available theory of deep filtration in clean beds of porous media gives some basis for estimating the behaviour of fine sediments in other alluvial systems

Jun 19, 1905

By D. M. Walters

To achieve safe and healthy working conditions in shaft sinking operations, ventilation, and where necessary cooling, must be provided. These requirements are considered for sinking vertical, sub-vertical and decline shafts. Regulatory requirements, determining air volumes and amount of cooling required, the various ventilation methods used such as force, exhaust, twin columns, air reversal using four gate systems and the equipment required to achieve this, are discussed. Consideration is also given to the sinking of single and twin declines using diesel equipment, calculating the air volumes required to dilute pollutants and the various methods for achieving this. Also discussed is the importance of having early ventilation design input to the overall design of the mine. In many cases ventilation can be the prime determinant for the size and configuration of the shafts or declines that have to be sunk.

Jan 1, 2009

This article focuses on TurkeyÆs gold potential with respect to exploration, development and operation after 1985. Apart from TurkeyÆs geology, which offers a substantial number of volcanic-associated gold (Ag) and gold-copper (Au-Cu) projects, there are numerous other factors which make the country a favourable place for mining. Turkey has a mining history which goes back to pre-Roman times and an excellent mining code which ensures security for long-term production. In the country, the Government and local villagers are very positive and the country works extremely well logistically with excellent road and telecommunication links. The opportunities for new discoveries in Turkey are very high. Moreover, Turkey has its eyes turned west as it moves towards joining the European Community and it is no surprise that international companies believe it has got its timing as well as its partner relationship right. Newmont, Teck Cominco, BHP Billiton, Rio Tinto, Eldorado Gold, etc all have direct or indirect interests in Turkey, as do an increasing number of midtier and junior exploration companies. Turkish Koza Gold Mining is the first Au producing company of Turkey. The Eldorado Gold owned 245 t Kisladag Au deposit in Western Turkey is currently also producing Au. In the meantime Anatolia Minerals Development is advancing the 131 t resource at the C÷pler Au deposit in North Eastern Turkey. These are significant world-class deposits. Further encouragement for investment in the Au mining sector has been provided by the introduction of a new mining law in 1985. Foreign investments in the country were encouraged and have seen a rapid increase in the last two decades. Gross domestic product (GDP) growth is in excess of five per cent per annum, inflation is down from 70 per cent to single figures, the budget deficit has been cut by 40 per cent to 11 per cent and industrial output and productivity are increasing rapidly. Turkey is politically and economically stable, is a member of the European Customs Union, has a supportive mining legislation, is highly prospective and under-explored and hosts significant recent gold discoveries.

Jan 1, 2007

By L. Obert, D. E. Stephenson

The objectives of this investigation were to develop a laboratory procedure in which core discing could be produced under known (and variable) stress conditions, and to study the discing characteristics of several fypes of rock. Discing of rock cores refers to the formation of discs or wafers of relatively uniform thickness which fracture or rupture on surfaces approximately *Fracture is a type of failure in which there is a complete loss of cohesion and fresh surfaces are created. Rupture is a type of failure in which there Is only a partial loss of cohesion. normal to the axis to the core (see Fig. 1). Usually the surfaces of the discs are concave-convex with the concave side toward the collar of the hole. The surface of the fractured discs are like those created by a tension failure (or possibly a shear failure with virtually no normal compressive stress). This phenomenon has been observed by a number of investigators1-5 in the course of diamond drilling in underground mines, especially in areas suspected of being under high stress. The state of stress in the core required to produce discing is not exactly known. Tranter and craggs6 theoretically investigated the stress distribution in an infinite cylinder, subjected to hydrostatic pressure, minus p, from z = 0 to z = 8 and unloaded from z = 0 to z = 8, Fig. 2. The exact solution to this problem shows that a tensile stress develops in the loaded region near z = 0 with the greatest tensile stress on the axis of the cylinder. A tensile stress also developed on the surface of the cylinder at a point just outside of the loaded zone. Jaeger and Cook3 experimentally investigated the discing mechanism by biaxially loading cores in a pressure jacket sealed at the ends by O-rings. According to the Tranter and Craggs theory it would be expected that failure should occur at the pressure discontinuity at the O-rings. The experimental results showed that if the specimen was unjacketed it broke at random points within the pressurized zone and at a pressure somewhat greater than the tensile strength of the specimen, presumably due to the development of a

Jan 1, 1965

By Tapio Leskinen

"In the 1960’s, when large flotation machines appeared on the market, this was a part of a world-wide trend towards the use of ever larger machine units.One factor that has played a decisive part in this development is the increased of the amounts of ore that have to be handled as the exploitation of successively poorer ores becomes necessary. The advancing application of instrumentation and automation has worked in the same direction.In 1970, a working group was set up within Outokumpu Oy, for the purpose of flotation machine development. The principal task of this group was to be the design and development of- a new type of rotor of increased efficiency, especially for the dispersion of large amounts of air- a mechanical-pneumatic flotation machine of substantially larger size that existing plant.This development project required an extensive program of theoretical investigation and experimental studies at several concentration plants of the company.The commonest flotation machine presently used in the concentration plants of Outokumpu Oy is the VK-3. It is of the mechanical-pneumatic type, and the volume of its cell tanks is 2.5 m3 per shaft. This machine was developed within the company, and its first development phase i s represented by the OKKO 3, built for the Kotalahti concentrator in 1959. It was, in its time, comparable in volume to the largest machines that were then in use anywhere in the world."

Jan 1, 1976

By R. J. Durrheim

The seismicity of the Witwatersrand Basin and Bushveld Complex has been analysed, revealing significant differences in source and damage mechanisms. A comparison of mining taking place at similar depths and extraction ratios indicates that the seismic energy release rate is considerably lower in the Bushveld Complex. Technologies introduced in the past decade to manage the risk of rockbursting are reviewed and assessed. These include geophysical methods to detect hazardous structures ahead of mining, new mining layouts and support systems, and the mechanization of in-stope processes. Despite important differences in geology, in situ stress, mining layouts and methods, there are many opportunities for the reciprocal transfer of knowledge, experience and technology between the gold and platinum mining sectors to improve the management of the rockburst risk.

Jan 1, 2005

By Yuanbo Zhang

Zinc leach residues produced by hydrometallurgical zinc plants contain many valuable elements (zinc, iron, lead, gallium, indium silver, etc), while they have not been utilized effectively hitherto. In this paper, a new process of flotation-reduction roasting-magnetic separation to recover these valuable elements from zinc leach residues is developed on a basis of mineralogy investigations of them. The results show that silver concentrate with grade of 4321.6 g/t and recovery of 80.69% have been obtained, using 1750 g/t Na2S as conditioner, 750 g/t ammonium dibutyl dithiophosphate and SN-9 (assistant collector) as combined collector and 100 g/t terpenic oil as frother, if zinc leach residues with 523 g/t silver are floated at pH = 5.0. When the flotation tailings are subjected to reduction roasting at 1100? for 2 h, the volatilizations of zinc, lead and indium are over 96%. After roasted products are treated by wet-grinding and magnetic separation, the grade of gallium and gallium in the concentrates achieved respectively reaches 1805 g/t and 1536g/t, and the recovery of them is high to 94.67% and 93.20%, respectively.

Jan 1, 2006

By Steve Kral

For the past several years, copper producers have faced a tough business climate. Nagging low prices forced many them to reduce their production and make other drastic cutbacks just to breakeven. And sometimes even that did not work. But, like other downturns in the industry, this latest dismal copper market allowed technology to make further inroads into mining and processing operations. Now that the copper market appears to be making a turn for the better, those years spent investing in technology by equipment manufacturers and forward-thinking mining companies should begin paying off.

Jan 1, 2004

By K. Rainer Massarsch

In some parts of the world, vibrators are used extensively for different types of foundation engineering projects. If used correctly and in suitable soils then vibratory pile driving for example is very efficient. However, soil conditions and the installation procedure have great significance for the driving resistance and affect the bearing capacity of vibrated piles. Also the intensity of ground vibrations which are transmitted to the surrounding soil is affected by the vibration process. In spite of the increasing use of vibrators and the rapid development of vibrator technology, many aspects of pile-soil interaction are not yet understood. In order to asses the importance of factors, which govern pile installation (and extraction), it is necessary to consider the entire chain of vibration energy transmission from the vibration source to the pile, the interaction between the vibrating pile and the soil and the wave propagation in the subsoil, Fig. 1. [ ] Fig. 1. Transfer of vibration energy from the vibrator through the pile into the ground In the present paper, some important aspects of vibratory driving and their significance for pile installation and soil compaction will be discussed.

Jan 1, 1995

? Hollow Stem Auger ? Drill Bits ? Leads/Torque Arm ? Hydraulic Gearbox ? Hydraulic Power Unit ? Grout Pump ? Crawler Crane

Jan 1, 2002

By Lawrence Melis

Fission Uranium Corp.’s Triple R Uranium Deposit at its Patterson Lake South Project is located in northwest Saskatchewan in Canada’s Athabasca Basin. As part of pre-feasibility studies for the project a detailed metallurgical test program was completed to provide process design criteria. The testwork program encompassed preparation and analysis of test composites, comminution testing, uranium acid leaching, liquid-solid separation, solvent extraction of uranium, precipitation of uranium yellowcake products, tailings and effluent treatment, tailings physical and chemical characterization, and environmental testing of prepared tailings, as well as investigations of gold and silver recovery from the mineralization. The paper provides mineralogical information, testwork methodologies and test results which were used to arrive at process design criteria and the selection of the process flowsheet for the project.

Jan 1, 2020

By Thomas M. Keevin, Gregory L. Hempen

"Natural resource agencies, under various regulatory authorities, are challenged with permitting underwater explosive use while at the same time protecting aquatic resources. Deciding on whether or not to allow use of explosives requires striking a balance between development and aquatic resource protection. A company’s goal in underwater explosive use is to select methods that are both expedient and cost effective. The use of explosives is often the best alternative for engineering reasons or economic considerations. Over and above legal requirements, indiscriminate destructionof fish and other aquatic resources is not in a company’s best interests because of concerns relatingto public image, as well as the need to secure future contracts."

Jan 1, 1995

By T. F. Bamber

The South Nottinghamshire Area has not been greatly troubled by spontaneous combustion until the last few years, during which the Blackshale Seam has been developed and exploited. The problem was first encountered at a colliery which was heavily preoccupied with a major reconstruction scheme, and with the sudden appearance of a completely new hazard both men and management had to adapt themselves very quickly to meet the situation. The paper contributed to the Symposium by the South Nottinghamshire Area illustrates the problems by reference to actual incidents, and shows how the lessons learned from them have been applied to the shaping of future policy on the avoidance and treatment of spontaneous combustion.

May 23, 1905

By Steve Klein

The Transbay Downtown Extension (DTX) in San Francisco involves the construction of a large-span tunnel with a width ranging from 43 to over 60 feet. The tunnel will be excavated using the New Austrian Tunneling Method (NATM), also known as the Sequential Excavation Method (SEM), in highly fractured and sheared rock. This paper discusses the FLAC (Fast Lagrangian Analysis of Continua) analyses that were completed for conceptual design of the tunnel support system and to develop surface settlement estimates for the evaluation of measures to protect existing buildings located above the tunnel from damage.

Jan 1, 2008

By P. J. Brereton-Stiles, M. S. Rennie, N. Singh

Ferroalloy producers are large-scale users of electrical energy, which in many countries is in short supply and increasingly expensive. Preheating and/or pre-reduction using natural gas, recycled furnace gas or coal fines have lowered the specific use of electricity, but the high energy concentration necessary for most reduction processes can be achieved only by the use of high electric currents. Most countries have insufficient electricity to supply the demands of industry and the domestic consumer, particularly during certain periods of the day and certain times of the year. The generation and distribution of electricity is a large-scale expensive business, which is financed and managed directly or indirectly by government bodies in most countries. Both economic and political imperatives determine how much electrical energy is made available to whom and at what price. In South Africa demand is set to outstrip supply within the next few years, and the local supplier Eskom has moved from a traditional demand tariff pricing structure to a time-of-use tariff pricing so as to limit peak demand usage. This will mean a substantial increase in electricity cost to those users unable or unwilling to reduce consumption during peak periods. The optimal use of the available electrical energy depends both on the process, the furnace size, the configuration and infrastructure of each plant and its cost structure. As the cost and availability of electricity is set to change dynamically, the management of the situation becomes a real time control and optimisation problem. This paper discusses some the process and operational constraints associated with low- or no-load conditions and how to manage the situation. Electrode management will be one of the key issues.

Jan 1, 2004

By Walter S. Bergholz, Michael L. Schreder

"Since Escondida began operations in fiscal 1991, a series of aggressive expansion projects have enabled market share to be increased and ever larger profits to be realized. This was possible due to the very large size of the ore body and its high grade - averaging 2.7% copper from startup through fiscal 1997. The situation has now changed: ore grade is falling rapidly and is projected to be only 1.55% by 2003. Since revenue is directly proportional to ore grade, while costs are proportional to quantity of ore processed, profits will begin to fall dramatically. The Phase IV Expansion Project is intended to forestall this drop in profits by increasing ore processing capacity by over 85%.The Phase IV concentrator is designed for a nominal capacity of 110,000 MTPD and the key to achieving this value is through the proper design of the grinding circuit. This paper presents the general design criteria for the grinding circuit, as well as a description of the facility.INTRODUCTIONThe Phase IV Expansion Project consists of a new copper concentrator located 8.5 km south of the existing operations, a new tailings disposal and water reclaim system, a new concentrate slurry pipeline to the coast, and added concentrate handling capacity at the port of Coloso. The new concentrator has a nominal capacity of 110,000 tonnes per day (MTPD), compared to the existing concentrator’s capacity of 127,500 MTPD. The Laguna Seca concentrator is based on using the largest and most efficient ore grinding mills now available.The concentrator has been designed for a 110,000 MTPD nominal capacity. The process design criteria for the Phase IV project were established from in-house operating information and from test work. Unlike a green field project, Escondida already had an operating plant and it processes ore from the same pit that feeds the Phase IV plant. It is expected that the current mineralization will be similar for the first 6 years of operation of the new project. Therefore, some of the current plant operating conditions were incorporated directly into the design criteria."

Jan 1, 2004

By Thomas J. Crocker, Douglas B. Uthus

Tunnel Boring Machines (TBM) have gained worldwide acceptance in the construction field and are being employed in ever increasing numbers to drive underground transit lines, drainage systems, etc. However, TBM utilization in the mining industry, and more specifically coal mining, has been very limited. This paper reviews past and present applications of TBMs to coal mining and examines the needs of the industry in an attempt to offer some insight as to what a TBM system must provide if the excavation potential demonstrated in civil works projects is to be realized in coal operations. EUROPEAN EXPERIENCE Germany The Germans recognized long ago the potential of mechanized drivage for coal mine entry development. Early in the 1960's experimental runs were made with a full-face Wohlmyer roadheader at the Westerholt Mine and trials were conducted on a roller bit armed full-face Bade roadheader. But because of problems with penetrating the various carboniferous strata occurring in changing sequence and hardness, these first attempts were soon terminated. After viewing later successes in the construction industry with improved TBMs, new attempts were initiated by the German mining industry in 1971 to mechanize drivage of their development entries. Four TBMs of two different types were placed in operation.

Jan 1, 1976

By L. M. Sekhukhune

The atmospheric leaching of copper-bearing matte by acidic ferric chloride solution was studied at the laboratory scale. The aim was to achieve maximum copper and nickel recovery by investigating the mechanisms of leaching, as well as identifying the effect of temperature, and concentration of ferric chloride and oxygen. Djurleite (Cu1.96S), hazelwoodite (Ni3S2), and Ni alloy were the primary phases detected in the matte. The quantitative composition of the matte was Cu 31%, Ni 50%, S 13%. Fe and Co constituted 2%, with platinum group metals (PGMs) accounting for 0.5%. A maximum nickel extraction of 98% was achieved using two-stage oxidative leaching at 90°C and 11 g/L Fe3+ as compared to 65% under non-oxidative conditions. A copper extraction of 99% was achieved in the first 45 minutes using two-stage non-oxidative leaching, and copper was recovered from solution by cementation. Three processes took place simultaneously throughout the leaching process, namely: dissolution, cementation/ metathesis, and oxidation. The leaching process was found to be diffusioncontrolled.

Jan 1, 2014

By Forrest T. Moyer

INJURY experience in the metal and nonmetal mineral industries during 1964 was better in rates of occurrence but worse in severity rates than in 1963. The frequency rate of injuries per million man-hours was improved at metal mills, nonmetal mines, and sand and gravel operations, and was virtually unchanged at metal mines; however" the rate of occurrence of work injuries at nonmetal mills, stone operations, nonferrous reduction and refining plants, and slag plants was higher than in 1963. The severity rate of injuries during 1964, data for which are presented for the first time in this chapter, was better at metal mills, nonmetal mines, stone operations, and slag plants. However, the severity rate was worse at metal mines, nonmetal mills, sand and gravel plants, and nonferrous smelters.

Jan 1, 1965

By P Breuer, X Dai, A Bergamin, D Hewitt

"Copper-ammonia-thiosulfate?leaching of gold has been researched for several decades as a potential alternative to cyanidation. However, this technology has not yet been applied commercially due to many challenges such as complex solution chemistry, reagent degradation and losses, system instability with losses of precious metals and difficulties in gold recovery from the leachate. Progress has been made at CSIRO in tackling some of these challenges including:better understanding and control of the leach conditions to minimise reagent losses whilst maximising gold recovery use of strong base ion exchange resins to recover the gold strategies to deal with polythionates that adsorb competitively with gold on ion exchange resins development and evaluation of process flow sheets.As a result there has been increased interest from the gold industry and renewed activities to develop thiosulfate based processes for gold recovery. One application area, which has been developed to the point of piloting, is the treatment of gravity gold concentrates using a copper-ammonia-thiosulfate leach with ion exchange recovery of the gold thiosulfate. This paper describes some of the advancements in the development of a potential process flow sheet for this application.CITATION:Dai, X, Breuer, P, Hewitt, D and Bergamin, A, 2013. Thiosulfate process for treating gold concentrates, in Proceedings World Gold 2013, pp 61-70 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Sep 26, 2013