Search Documents

By Werner Burger, Marcus Lübbers

TBM development in recent decades has been dominated by increased face pressures, larger diameters and multi-mode functionality paving the way to realize projects deemed impossible before. In addition, the trend towards digitalization does not stop at the tunnel portal. A shortage of skilled personnel and the ever-present wish to increase workplace safety, quality and system performance automation, operatorassist or even autonomous systems have become key development targets. The paper will present the current state of the art in light of these special conditions.

Jun 13, 2023

By R. J. Barnes

Consider a typical blast at a surface gold mine in North America. For example, the low-grade area of Bench 4000 at AMAX Gold's Sleeper Mine (Winnemucca, Nevada). Bench 4000 is 20 feet high (=6m) , and blast holes are drilled and sampled on a 14 foot by 14 foot square grid (a4m x 4m). A representative blast includes between 50 and 150 holes, encompassing 15,000 to 45,000 tons of material (w14,000 to 41,000 metric tons).

Jan 1, 1989

By C. J. Konya

When blasts are designed, the assumption is made that all blastholes release near ideal energy. In many types of mining operations, some blastholes release very little useful energy. These blastholes will be called malfunctioning blastholes. Recent studies indicate that on many types of blasting applications, 30 percent of blastholes are malfunctioning. This malfunctioning routinely occurs on the operation and is not an unusual occurrence. This paper will discuss the cause of malfunctioning blastholes and methods to minimize the detrimental effect on both safety and costs.

Jan 1, 1988

By R. L. McNearny, K. A. Barker

A study was conducted to compare physical and numerical models of the block-caving mining method. Results from the numerical analysis closely simulated the blocky behavior of the physical model, including bridging and interlocking of the simulated orebody during draw. The draw-down patterns and the rate of draw developed during numerical modeling also closely simulated the physical models. An unexpected result from the numerical modeling was the development of a zone of downward deflection which preceded the development of the zone of material movement.

Jan 1, 1999

By P. R. Khangoankar, S. Devasahayam

An experimental study of the particle charac¬teristics of the magnesium carbonate crystals formed by the reaction between magnesium chloride and sodium bicarbon¬ate at different temperatures is described. The rate of growth of magnesium carbonate crystals for any constant tempera¬ture is established, and this rate of growth is related to the degree of supersaturation at the given temperature. The activation energy calculated using empirical constants de¬rived from the relationship between the crystal growth rate and supersaturation, is indicative of a surface-reaction mechanism.

Jan 1, 1996

By H. J. Zhang, W. Wui

With the adoption of market-oriented economic policies, Chinese non-ferrous metals industry has gained remarkable progress. The continuously increasing domestic demand for non-ferrous metals, however, calls for more import of raw materials in short supply, such as copper concentrate and bauxite. As an alternative for balancing the shortage and assurance of more stable mineral supply, direct investment in oversea mining project has come to the agenda. This paper discusses the computer-assisted method used for evaluation and comparison of potential mining projects.

Jan 1, 1996

By W. J. Cieslewicz

Geologically, northeastern Siberia is a region occupied by a folded belt of Triassic and Jurassic sediments and volcanics. Gold mineralization is of Upper Jurassic age. Most of the stream placers formed during the Quaternary. Placer gold was first discovered in 1916. Between 1930 and 1957, mining was carried out by the "Dal 'stroi," a Russian concentration camp organization. Since 1966, the mines have been worked mechanically. About 10 mining districts are now active, producing, altogether, 110 to 135 t (120 to 150 st) of gold annually.

Jan 1, 1987

By J. C. Stankus, J. J. McCaffrey, S. Guo, S. S. Peng

An innovative concept in longwall tailgate support is discussed. This new concept utilizes a high-capacity roof-truss system to replace conventional wooden cribs. The first field test was conducted at the Bailey Mine and was very successful. Similar tests were installed in other mines and seams. An extensive instrumentation plan was designed and implemented in the truss test area. The test data demonstrated that the dynamic roof-truss system effectively controls the various abutment pressures caused by longwall mining. Thus, a stable tailgate entry is maintained

Jan 1, 1997

By Bruce D. Hulman, Robert .. F. Gorman

Introduction Groundwater resource evaluation has historically required extensive field investigative work, usually at great cost. More recently, the advent of the microcomputer has made difficult aquifer and groundwater evaluations comparatively simple and less expensive. A groundwater model is a numeric solution to a set of equations that calculates the water level in an aquifer or other types of water bearing strata. A computer will execute the solution of the set of equations rapidly and thereby permit evaluation of large amounts of hydrogeologic data rapidly. Computer modeling of groundwater resources is very often used to forecast the effects of multiple uses of a single groundwater resource. Modeling of heavily used aquifers has proven to be beneficial for averting problems arising from competitive use of a groundwater resource. This paper describes the work tasks performed in order to evaluate a large alluvial aquifer and thereby predict the hydrologic impact of additional groundwater withdrawal. Purpose and Scope Neyer, Tiseo & Hindo, Ltd. (NTH) was retained to evaluate the groundwater supply potential of the Missouri River alluvium underlying the Fairfax District in Kansas City, Kansas (Figure 1). The proposed groundwater supply is being considered for industrial use as non-contact process water and a heat exchange medium for plant climate control. The anticipated peak groundwater demand is estimated to exceed 30 million gallons per day (MGD) during the summer months, with an average daily demand of nearly 25 MGD. The proposed groundwater supply was to be developed from 15 large-diameter production wells located at positions that would minimize potential interference.

Jan 1, 1987

By W. Hoecker, S. Watson

The use of oxygen (Goldox™) in gold leaching has emerged as a significant modification in the past nine years. The Goldox™ process was ori gi na 11 y developed by Afrox Ltd ( part of the BOC Group) and is currently used in South Africa, Australia, Canada and the United States. Although a variety of benefits have been observed with oxygen, this paper out 1 i nes the main ones with reference to Australian plant data. The case studies were categorised into the ore type: Oxide, blends and primary ore.

Jan 1, 1992

By Peter Krag, Rob Henson

It is well known that titanium and zirconium alloys offer superior corrosion resistance in the oxidizing sulfuric acid environments present in sulfide pressure leaching operations. The use of these materials is limited, however, due to their pyrophoricity; several accidents attributed to titanium equipment have been described in technical literature, and other, minor incidents·occur regularly1 • We describe an application of a commercial titanium alloy, Nb-55 Ti, with suitable mechanical properties, corrosion resistance similar to Grade 2 Ti, and featuring a significantly reduced field of ignition conditions

Jan 1, 1992

By Pierre Louis, Jacques Duparque

ACTIRED is a new process for gold and silver elution from activated carbon based on the addition of hydrazine, needing no extra investment and which generates a systematic increase in elutions kinetics. This process either operates at a lower temperature and maximizes financial gain or reduces elution time or operates at a compromise between these two options taking into account the needs of each plant. Industrial use of the process at SNC Lastours, France (Zadra elution column 3,5 bars -125°C) has proved at 95 ° C the following points:

Jan 1, 1995

By Ian J. Corrans, Gary Johnson, John E. Angove

Activox® is a hydrometallurgical process used to oxidise sulphide concentrates. The process is based on two relatively simple, established unit operations; i.e. fine or ultra-fine milling (UFM) and pressure oxidation under mild conditions. An under-standing of, and ability to control the pulp chemistry during oxidation has resulted in the successful Activox® treatment ( on a batch scale) of a wide variety of sulphide flotation concentrates; • pyrite/arsenopyrite + gold • pyrite/chalcopyrite + gold • pyrite/chalcocite + gold • pyrite/enargite/tetrahedrite + gold Oxidation rates are rapid (1-2 hours retention time) and gold

Jan 1, 1995

By G. W. Ford, S. E. Black

Current research into coal based synthetic fuels is taking place on two fronts, fuels for power generation and conversion of coal to ultra-clean fuels for transportation. Present research into solid synthetic fuels is concentrated on development of clean coal technology which will meet or exceed the proposed cap and trade emissions set forth in the Clean Air Act Amendments of 1990. Research into ultra-clean liquid fuels is concentrated on either direct or indirect liquefaction process which could be used to manufacture both diesel fuels and gasoline.

Jan 1, 2003

By S. Luning

In the nineties the gold sector in Burkina became subject to internationally prescribed liberalization policies. The national state is at present only one of many players. Who are these players, and how are they involved with one another in organizing goldmining activities and prospects in Burkina? One mining site serves as a case to study the scope of players and the types of authorities they build upon in governing gold sites. What conclusions can be drawn in regard to the present position of the Burkinabe state within this field of governing authorities?

Jan 1, 2007

Dunn has written an excellent paper providing a wealth of advice on what is often the most costly consumable in the mineral processing plant. As he pointed out, grinding media selection and quality control can play a major role in successful plant operation. Owing to the economic importance of this topic, there are some important factors related to media sizing that I believe merit further comment. Dunn made reference to a slightly simplified version of the Azzaroni (1981) equation and pointed out its successful use for the Henderson SAG and Climax ball mills.

Jan 1, 1991

By John D. Welsh

Heap leach pad liners are important to leach operations for maximizing recovery of gold bearing solutions and minimizing potential environmental impacts. Liners must be designed so that they can be built economically, but careful attention must be paid to the potential for liner damage during installation or placement of ore on the completed pads. This paper summarizes field experience gained on several leach pad construction projects in Nevada. Both soil and synthetic membrane installations are discussed. Emphasis is placed on principles that should be considered during design to provide economical and practical leach pads.

Jan 1, 1987

By Mark J. Schultz, William J. Francart, Michael P. Snyder

The Pittsburgh Safety and Health Technology Center surveyed MSHA Coal Mine Safety and Health Districts to monitor the implementation of computer based atmospheric monitoring systems (AMS) in underground coal mines. This survey was first completed in 1984, and has been periodically updated with the latest update completed in 1995. The utilization of computer based monitoring systems has steadily increased over the past 12 years, with over 16 percent of all producing underground coal mines using this technology in 1995. This paper discusses the results of the MSHA 1995 AMS Survey.

Jan 1, 1997

By Janusz Szywacz, Bozena Bojko, Stanislaw Wasilewski

Two groups of computer programs are described in the paper. First one is the OWEN system containing software modules designed for air flow distribution analysis and prediction within the whole ventilation network of a mine. The second group is a set of programs commonly used in a routine design work connected with chosing the optimal ventilation schemes and equipment for individual areas of a mine (headings. longwall districts etc). All the programs are designed for running on the IBM PC/XT, IBM PC/AT and compatible computer systems.

Jan 1, 1989

By Gopalan Ramadorai

This paper presents a review of halogen solvents used in the processing of precious metals. Reagents of widely varying chemical structures, such as chlorine gas, calcium and sodium hypochlorite, chlorine dioxide, iodine and bromine have been used for precious metal extraction. None of these chemicals are a replacement for cyanide: however, each of these chemicals present an opportunity for use in processing a specific type of ore. The ore and chemical must be matched to each other for success. Recovery of metal from the leach solutions also offers challenges.

Jan 1, 1994