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By Darrell M. Hladun, Linda M. Dufour

The benefits of computer simulation in the design of a refracto­ry gold autoclave facility is discussed. Three computer simula­tion programs used for autoclave design are briefly described in this paper. 1) METS IM® - A Process Simulation Software Package Developed by Proware: Mass and energy balances are conducted around the auto­clave and its ancillary processes. Results from the process simulation define process equipment requirements and are used for establishing operating costs. The p_rocess model integrates various unit operations including grinding, acidu­lation, pressure oxidation, counter-current-decantation, neutralization, cyanide leaching, and carbon-in-pulp or car­bon-in-leach. 2) ALGOR® - Finite Element Analysis (FEA): A computer software program is used in the design and analysis of brick lined pressure vessels, such as autoclave, heater, and flash vessels. This software creates a steady state thermal model, and accurately predicts temperature distribution throughout the entire vessel, including nozzles, which represent regions of high thermal intensity. 3) Compress©: A software package developed by Codeware used for the sizing of pressure vessel components, includ­ing shells, heads and nozzles, according to ASME Boiler and Pressure Vessel Code, Section VIII, Division 1.

Jan 1, 1996

By M. S. Walton

A conference attended by a limited number of invited participants was held last September in Denver under the auspices of the Underground Construction Research Council of ASCE funded by the National Science Foundation (RANN) to explore the problem of accelerating the transfer of advanced geophysical technology, used principally in the petroleum exploration industry, into more effective and widespread use in subsurface investigations for underground construction. There are technological problems, but technical difficulties and unfavorable ratios of benefits to costs are not the major obstacles. The problem centers on the complex way in which potential net benefits are translated into effective incentives to innovate for each actor in the complex web of individual, corporate and institutional entities involved in the planning, designing, building, funding, operation and ownership of major underground construction projects. The entities responsible for site investigation, design concepts and specifications do not directly bear the risks of unanticipated costs and failures, nor directly gain from savings. The conventional unit-price construction contract is strongly implicated in blocking innovation. Problems of risks and incentives, more than technical feasibility, must be solved before large investments in technical adaptation and adoption can occur.

Jan 1, 1974

By Kathryn C. Sole, Angus Feather, Leslie J. Bryson

A novel solvent-extraction route for the production of high­purity gold has been successfully demonstrated on a pilot-plant scale, and the first full-scale production plant is being commissioned. This plant, at Harmony Gold Mine in South Africa, is designed to refine 24 tons of gold per annum when operated for one shift per day. The commercial implementation of this process represents not only a significant advance in gold­refining technology, but may also be instrumental in initiating important changes in the legislation regulating the marketing of gold in South Africa. The Minataur™ Process (Mintek Alternative Technology for Au Refining) is able to produce gold of either 99.99% or 99.999% purity from intermediate process products having a wide range of gold contents. The process comprises oxidative leaching of the feed material, followed by selective solvent extraction of the gold from the leach liquor to reject impurities, and then precipitation of high-purity gold powder. This paper introduces the process, presents selected results of pilot-plant trials in which high-purity gold was produced from two significantly different feed materials, and illustrates some of the applicable cost benefits.

Jan 1, 1997

By Andrew H. Stearn, Robert O. Agbede, Edward F. Divers

The ability to compete profitably in a competitive, demanding and specialized market, requires all components of productivity to be optimized toward the same manufacturing goal. This ever present requisite is seldom more apparent than with the quality control (PC) considerations that confront the super-refined metallurgical production necessary for today's exacting technical applications. In a work-place that already exceeds all environmental standards for cleanliness, this paper describes the development of specific environmental mechanisms and controls implemented at a titanium processing facility to impact both the minimal air-borne particulate contaminants and excessive process heat generation which are believed to degrade product purity. Based on the analysis of a carefully structured and instrumented field survey, two alternative solutions were proposed to modify the present facility utilizing a forced air (blowing) system. The first scenario requires ambient air to be drawn from a louvered rooftop installation and ducted to specific zones within the plant with appropriate weighted louvers and wall and roof exhausters designed into the system for air control. The second scenario incorporates a properly sized baghouse to be used in conjunction with the first system.

Jan 1, 1991

By William Cowan, Robert Spencer, Lynn Carpenter

INTRODUCTION The Bureau of Reclamation is conducting a research program to investigate, develop, and test polymer-impregnated concrete tunnel support and lining systems for gravity flow, circular cross-section water conveyance tunnels. This system consists of segmented precast rings, backfilled with concrete. Polymer-impregnated concrete is conventional precast concrete which has been impregnated with a liquid monomer. The liquid monomer is subsequently converted to a polymer by thermal-catalytic or radiation methods. The polymer is a solid plastic which fills voids and microfractures within the concrete, resulting in greatly improved strength and modulus of elasticity and reduced permeability, which in turn increases the durability of the concrete. The immediate goals of the program are to develop techniques for the fabrication of precast concrete segments, test single segments to determine physical and mechanical properties, assemble the segments into a support and lining system, load and test the full-scale system, evaluate specific applications, and develop design criteria and construction procedures. NEED FOR THE TEST PROGRAM Modern rapid underground excavation technology emphasizes desirability of supporting and lining a tunnel closely behind the heading without reducing the excavation rate. Therefore,

Jan 1, 1997

By E. J. McGuire, E. W. Brickle

INTRODUCTION Several recent technological improvements - largely by the convey-or industry - have increased the importance of inclined shaft construction for developing mines where ore deposits are relatively shallow. With these newer systems, long conveyor haulages are economically feasible, allowing mine owners to justify the expense of the inclined shaft or slope. What this actually means is that they can now take advantage of the versatility this construction offers. For example, haulage capacity can be changed by conveyor additions or replacements; equipment can be trammed to and from the surface quickly without costly breakdown and re-assembly; and a walkway is available for workers in the event of an emergency. Now, another innovation may accelerate this type of construction, the use of tunnel boring machines or "Mechanical Moles" to dig the slopes. While conventional. drill and blast methods have been used previously to build inclined shafts, the tunnel boring machine technique offers greater production rates, higher safety and a better, much cleaner bore. McGuire Shaft & Tunnel Corporation of Ft. Smith, Arkansas recently started such a slope project - the first ever bid by a contractor based on the use of a "Mechanical Mole".

Jan 1, 1997

By J. D. Scott

This paper consists of a review of the development and application of spherical charge blasting at Inco Metals Company. Topics will include the Livingston Strain Equation, the field data required for its use in full scale operation, the type of ground in which mining has been carried out, explosives in use and their characteristics and finally, an overview of actual production applications. These applications include Primary Stope Mining, Secondary Mining Against Fill, Mining a Faulted Ore Zone and Drop Raise Blasting. INTRODUCTION Crater blasting in itself has been in use for over twenty years, but only recently has the technique been combined with a spherical size charge to form the Vertical Retreat Mining Method. This article endeavours to put the Livingston Strain Equation in a practical light, to describe several actual hard rock applications, and the results achieved in each case. THE LIVINGSTON STRAIN ENERGY EQUATION C.W. Livingston put forward the following equation as a standard means of determining the optimum burden required for full crater production blasting. The constant "E" is included in an attempt to recognize secondary breakage caused by strain waves.

Jan 1, 1981

By Alf Thidemann, Per Marius Nilsen

Tunnelling with hydraulic drills has been a success in Norway. In the fall of 1976 excavation of tunnels for the development of the Aabjoera scheme was started. Two and a half years later a total of 25 kilometers of tunnels are completed. During the most busy period 5 rigs with hydraulic drills were in operation. GENERAL INFORMATION. Aabjoera Hydro Electric Plant is located in the central part of Norway (Fig. 1). The scheme covers a mountaineous area between the Tosen Fiord and the valley of Namdalen. Water from the area of precipitation is transferred through 5 tunnels to the main reservoir. From here the water is conducted via a 10 km long, unlined supply tunnel down to the Kolsvik power station. The power station is situated underground with a short tailrace tunnel out in the fiord. Average head of water is 507 m. The Aabjoera plant is jointly owned by Helgeland Kraftlag A/S, 8650 Mosjøen and Nord-Trøndelag Elektrisitetsverk, 7700 Steinkjer. The Civil Engineering Division of the latter company has acted as Consulting Engineers for the scheme. General contractors for the whole scheme has been Ing. F. Selmer A/S, Box 6035, Etterstad, Oslo 6.

Jan 1, 1979

By Nestor M. Fillip

INTRODUCTION The Advisory Conference on Tunneling held in Washington, D.C. in 1970 under the auspices of the organization for Economic Cooperation and Development (OECD) forecast that $54 billion would be expended by member countries on underground construction in the 1970s. Construction activity since the Conference indicates the forecast may have been conservative. Statistics in the report indicated a vast increase in tunneling projects for mass transit, hydro-electric development, railroad tunnels, sewer and sewage retention reservoirs and water tunnels. Development of equipment is required to meet the demands for high speed excavation and provide tunnel driving systems with maximum efficiency and capability to sustain high speed advance rates. BORING MACHINE CAPABILITY During the last decade, use of Tunnel Boring Machines (TBMs) has increased. Where ground conditions and limits of machine design criteria permit, circular tunnel sections are either the only section , or an alternate sections specified in the documents: a TBM is either required or is an acceptable alternate means of tunneling. The evolution and acceptance of the TBM has had an impact on the construction and to a lesser degree on the mining industry. The traditional drill-blast-muck or "hand" mine

Jan 1, 1974

By W. A. Crosby, A. Bauer

The recent increase in size of open-pit mining operations has resulted in major improvements in efficiency that are beneficial to the mining industry. Higher bench heights, larger diameter blast-holes, and more powerful explosives have played an important part in reducing mining costs. These measures have, however, resulted in increased energy concentrations in the blast area, which can result in severe backbreak problems for final pit walls. If backbreak is not controlled, a decrease in the overall pit slope angle will ultimately be necessary, and consequences, such as decreased recoverable ore reserves and increased waste-to-ore ratios, will result. Greater amounts of loose face rock will be produced, and planned safety berms will be less effective or nonexistent. Hazardous working conditions can also result. Remedial measures, such as scaling large areas and using wire mesh or other artificial support, are very expensive and difficult to implement. There must be a trade-off between the money saved by using larger blasts, and the time spent to maintain pit wall quality. The best approach is to control blasting effects so the inherent strength of pit walls is not destroyed. Presplit and trim blasting are two control blasting techniques used to accomplish this. Both techniques are designed to create a low explosive energy concentration per unit of wall area at the perimeter of the pit. Energy concentration of the main production blast must also be controlled to avoid damaging the final pit wall. A low-energy concentration at the final wall can be obtained by decoupling charges, decking charges, using less powerful explosives, decreasing blasthole diameters, and changing the burden and spacing. Rock properties-fragmentation and the final state of the pit wall-influence the success of a blast. The most important properties to consider are: in situ rock strength, and the nature, frequency, and orientation of structural features. Since these variables cannot be controlled, they must be evaluated by suitable field tests, and then a control blast can be designed using controllable variables, such as spacing, burden, and hole diameter, so the blast will be successful for appropriate rock conditions. One main thrust of this article is to show how control blasts can be successfully designed for larger hole sizes, up to 381-mm-diam. While efforts to produce a good control blast in shovel/truck pits have been ongoing for some time, recent use of a modified presplit technique in dragline operations has helped reduce water problems, improve safety, and increase dragline productivity in a number of surface coal mines. This article presents examples on designing and using presplit and trim blasting for large hole operations in both shovel/truck and dragline mines. Presplit Blasting As introduction to presplit blasting, Fig. 1 illustrates a typical presplit blast layout using 102 mm-diam presplit holes for 381¬mm-diam production holes. For this type of blast, presplit holes would normally be drilled first, ahead of main production holes. The choice can then be made between loading and firing the presplit line or infilling the main blast. In the latter case, the presplit line would be fired instantaneously 100-150 milliseconds before the main blast. As shown in the figure, the presplit line is formed ahead of the main

Jan 2, 1982

By Ronald J. Searle, Howard S. Latham

In April 1964 the Bureau of Reclamation awarded the first contract for rapid machine excavation of a water conveyance tunnel . Since then the Bureau has excavated seven tunnels with a total length of over 190,000 feet utilizing rapid excavation tunneling machines. Tunnel bored diameters have varied from 9' 0" to 20' 10" (See Table #1) and tunnel lengths from 5,000 feet to 67,000 feet. Driver and cutter units varied from 43 rolling teeth and eight rolling discs mounted on a rotating head driven by five 200 HP 23,000 volt electric motors to 20 discs and one tricone unit mounted on a rotating head driven by two 100 HP 440 volt motors. All tunnels were driven with a laser beam guidance system governing both line and grade. Trailing conveyors and rail haulage systems were used to dispose of the excavated material. Approved Bureau of Mines diesel locomotive engines for waste trains were prevalent power sources supplemented by battery units on some projects. Sandstone, conglomerates, agglomerates, siltstone, shale, and granite were the geological formations encountered, with sandstone and shale the preponderant material . Tunnel support systems utilized were structural steel ribs; rock bolts and metal plates; and shotcrete, or combinations of these. Progress varied from 51-1/2 feet to 154 feet per working day for three shifts, depending on rock material and supports required. One contractor established a record rate of advance of over 400 feet in one day, 1,905 feet in one week, and 6,848 feet in one month. Such diversified experience in underground machine excavation methods presented an excellent opportunity to observe, analyze, and evaluate associated environmental health problems. Also, to develop measures for controlling

Jan 1, 1997

By Eugene A. Lang, William R. Archibald

Early in 1972, Rocky Mountain Energy Company approached MARCONAFLO with a unique request for assistance. They controlled a series of scattered ore deposits in a remote section of Wyoming which had become increasingly valuable despite their relatively small size, great depth and low grade. At the time, MARCONAFLO was in the process of developing a tailings reclaim system which was based on the use of submersible capsules. It appeared that this basic concept might be adapted to slurry uranium ores and pump them to the surface through a bored hole. This presentation will review for you the development of this unique and potentially very important application of MARCONAFLO technology. This first slide (SLIDE 1) depicts the total mining concept envisioned by MARCONAFLO and Rocky Mountain Energy Company. A series of six self-contained mining units would be positioned through boreholes into the ore strata. An oscillating MARCONAJET would direct a high pressure jet stream into the orebody and put it into a slurry which would flow back to a slurry pump. The slurry would then be pumped to the surface and to a collection tank from which it would be transferred to processing. Both the MARCONAJET and the slurry pump would be actuated and controlled by means of a hydraulic power console mounted on the trailer behind the service tower. By means of a high pressure water pump also mounted on the trailer, return water from processing would be delivered to the MARCONAJET to slurry the ore. Tailings would be returned to a backfill unit for redepositing in the mined-out cavities. A drill rig would precede the mining, and it was estimated that this configuration would represent an optimum system for most effective equipment utilization.

Jan 1, 1976

By Raja V. Ramani

The importance of adequate mine ventilation for good health and safety conditions has been recognized since miners first ventured underground. All over the world, governmental actions on mine health and safety are directly connected with mine atmospheric environments, their assessment and control. These governmental actions have been, and continue to be, motivated by the repeated experience that potential threats from inadequate control can evolve, either suddenly or in the long-term, into unpleasant reality, with catastrophic health and safety consequences. These governmental actions are also an indication of the remarkable professional progress being made in the field of mine ventilation. Surely, no developed country allows underground mines to operate without strong measures for the control of ventilation under legislation specific to the mining industry. In the United States, the federal government's responsibility for mine safety has evolved over the years through a series of legislative actions beginning in 1865 and continuing through 1910, 1941, 1947 and 1952. The passage of the Federal Metal and Nonmetallic Mine Safety Act of 1966 (the 1966 Metal Act), the Federal Coal Mine Health and Safety Act of 1969 (the 1969 Coal Act) and the Federal Mine Safety and Health Amendments Act of 1977 (the 1977 Mine Act) are the most important milestones in this long legislative history. The 1977 Mine Act adopted many of the stronger features of the Occupational Health and Safety Act of 1970, perhaps the most significant piece of legislation on workers' occupational health and safety in US history. It is worthwhile to ask, "How far has the United States come in mine ventilation since the enactment of the 1969 Coal Mine Health and Safety Act?" This Act and its associated regulations defined in great specificity many standards for healthful and safe operation of a mine and, in some cases, what constitutes good ventilation practice. Since 1969, the frequency and severity of disaster-type events in US coal mines has decreased markedly. A primary reason for this achievement is the strength of the Coal Mine Health and Safety Act's regulatory features in such areas as methane concentration control, dust control, intrinsic safety and explosion-proof enclosures, minimum air quantity and quality standards and air distribution and escapeway provisions. These requirements greatly influenced mine ventilation planning, engineering and practice, leading to increasingly safe working conditions.

Jan 1, 1993

By Pierre Mousset-Jones

I wish to submit this discussion item on an article published in the August issue of MINING ENGINEERING by Wala and Altman on the use of canonical diagrams for mine ventilation networks. The advent of computer graphics and plotting has enabled complex underground mine layouts to be displayed and plotted in a variety of three-dimensional formats that very closely represent the actual mine layout. This enables the ventilation engineer, who is familiar with the mine, to display the network pressures, quantities, resistances, and fan locations in a way that can be understood by everyone working at the mine. This is important if the ventilation engineer needs to discuss changes in ventilation with production personnel, or escapeway procedures with union personnel. While I can see some of the potential advantages in the canonical ventilation network diagram described by Dr. Wala, it appears to me that the fact that the diagram has no visual equivalence with the actual mine layout means that most mine personnel will find such a diagram almost incomprehensible. The authors have alluded to certain advantages with the canonical diagram. However, I find it difficult to see that these outweigh the fact that almost everything listed can be duplicated in isometric diagrams, and in a manner that is easily understandable to everyone in the mine from the miner to the mine manager. Perhaps the authors could show a clear example comparing an isometric with a canonical portrayal of a mine network showing the information that is immediately available from the canonical network that is not obvious in the isometric diagram. There is in this country a severe problem with the need for ventilation engineering and expertise to be used and accepted by mine management as a necessary part of mine planning. It seems to me that to introduce the requirement for further explanation so that management can understand a canonical network display will hinder more than help the recognition that ventilation engineering needs at so many mines in this country. However, I can see that the canonical approach does have its place in assisting the practicing mine ventilation engineer, wherever he or she exists in the organization chart for a typical mine. In this case, could the authors please indicate the availability of the computer program to compute and plot the canonical diagram for a mine ventilation network.

Jan 1, 1990

By Pierre Mousset-Jones

I wish to submit this discussion item on an article published in the August issue of MINING ENGINEERING by Wala and Altman on the use of canonical diagrams for mine ventilation networks. The advent of computer graphics and plotting has enabled complex underground mine layouts to be displayed and plotted in a variety of three-dimensional formats that very closely represent the actual mine layout. This enables the ventilation engineer, who is familiar with the mine, to display the network pressures, quantities, resistances, and fan locations in a way that can be understood by everyone working at the mine. This is important if the ventilation engineer needs to discuss changes in ventilation with production personnel, or escapeway procedures with union personnel. While I can see some of the potential advantages in the canonical ventilation network diagram described by Dr. Wala, it appears to me that the fact that the diagram has no visual equivalence with the actual mine layout means that most mine personnel will find such a diagram almost incomprehensible. The authors have alluded to certain advantages with the canonical diagram. However, I find it difficult to see that these outweigh the fact that almost everything listed can be duplicated in isometric diagrams, and in a manner that is easily understandable to everyone in the mine from the miner to the mine manager. Perhaps the authors could show a clear example comparing an isometric with a canonical portrayal of a mine network showing the information that is immediately available from the canonical network that is not obvious in the isometric diagram. There is in this country a severe problem with the need for ventilation engineering and expertise to be used and accepted by mine management as a necessary part of mine planning. It seems to me that to introduce the requirement for further explanation so that management can understand a canonical network display will hinder more than help the recognition that ventilation engineering needs at so many mines in this country. However, I can see that the canonical approach does have its place in assisting the practicing mine ventilation engineer, wherever he or she exists in the organization chart for a typical mine. In this case, could the authors please indicate the availability of the computer program to compute and plot the canonical diagram for a mine ventilation network.

Jan 1, 1989

By M. Gordon, J. M. Tranquilla

Microwave power, used in conjunction with properly designed applicators, is an efficient and practical energy source for pre treating a wide range of mineral ores and concentrates. Novel processes which take advantage of the unique properties of rapid microwave excitation present many distinct advantages over other pretreatment methods. These include dramatically reduced costs and elimination of all or most of the toxic by-products. A capital and operating cost analysis is presented of EMR's microwave process for treatment of refractory gold ores and con­centrates based on the company's experience using both small and large scale pilot plants. Comparisons are presented between the microwave process and roasters, autoclaves and bio-oxidation.

Jan 1, 1998

By Leonard Harris

Since the end of the cold war following the collapse of communism, enormous amount of funds are pouring into the developing countries including investments by mining companies for the development of gold and silver mines. A great deal of these funds are destined for expenditure in areas riddled with bandits, terrorists and active and latent criminals bent on stealing the mine operators hard earned production on its way from the mines to markets. Brambles Security Services employs experts in the field of safely transporting gold and silver products under various alternatives and aimed at relieving the mine owners of this responsibility. This paper examines the various service options available.

Jan 1, 1997

By K. M. Atencio, T. Pike, S. Forrest

We will introduce the Small Business Liability Relief and Brownfields Revitalization Act, which is an amendment to CERCLA and the types of sites it includes and excludes, especially as related to mine-scarred land. We will also describe the types of available funds, whether they are competitive or not, what entities are eligible to receive them, and how to access them. We will introduce the legislation’s liability provisions; for example, the recently issued interim guidance clarifying some of the conditions that contiguous property owners, bona fide prospective purchasers, or innocent landowners must meet to qualify for the liability limitations provided in the Brownfields Law.

Jan 1, 2004

By T. Mudder, K. Harvey

The objectives for closure of a hard rock mine include minimizing long term environmental liability, attaining regulatory compliance, and maintaining geotechnical stability, while closing as cost-effectively as possible. Proper planning for closure should come during the feasibility study, design and permitting phases, and during operations as updates. The lack of a proper or updated closure plan can result in severe environmental and economic consequences. Effective mine closure is the result of a combination of innovative concepts, long-term commitments, and multi-party cooperation. The purpose of this paper is to discuss concepts, commitments, and cooperation as they relate to an effective closure plan.

Jan 1, 1999

By Henk van Muijen

To create a feasible plan to extract marine minerals there are a significant number of factors that must be analyzed. Most of these are known from conventional mining types. The following issues are the most relevant factors that have to be considered for mining a deep sea reserve economically: Sufficient reliable geological, physiographic data to create a proven reserve and mineral resources, Environmental Conditions, Geological & Geotechnical Study, Mining and ancillary equipment selection (design) and suitability, Environmental Conditions, Initial Transportation (seafloor to surface), Locations for stockpiling & processing, Processing, Power requirements, Land (Seafloor) ownership, Government, Economic Climate, Waste Handling, Methods of obtaining information and Post-Mining Activities.

Jan 1, 2008