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By R. Addison

Boom, boom, boom, boom. The staccato beat rings out across the bush; the stamps are at work - slowly pulverizing gold-bearing ore for a patient, grizzled prospector. This is the State Battery near Marvel Loch - a tiny (capacity: 25 ton/day) gold plant operated by the Western Australian government. It is one of many such plants located in remote corners of Western Australia and the Northern Territory - miniature custom mills operated for the benefit of prospectors and small mine operators. These State Batteries, so called because they are operated by state governments and because the principal item of machinery in the plants are stamp batteries, are fascinating anachronisms: throwbacks to times long past, to a century ago, to the hard and heady existence of gold rush days.

Jan 1, 1986

By Mikula PA

This paper presents the results of in-situ and laboratory investigations into a mining method which utilises conventional continuous mining techniques to carry out two passes in thick coal seams, resulting in the development of stable pillars with relatively small width dimensions and heights up to 6 m. Geotechnical investigations included structural mapping, brightness logging and standard laboratory testing. Virgin stress was measured using overcoring techniques. Two approaches to pillar design were used in the study. These were; pillar design based on empirical formulae and laboratory testing, and pillar disign using calibrated mathematical models. A trial panel was developed at 300 m depth to study pillar deformation and stress changes due to mining. The extent of rib deformation was studied using borescopes and extensometers. In-situ geotechnical measurements were used to calibrate displacement discontinuity and finite element mathematical models of the coal seam. These models were then used to predict the behaviour of a small panel of pillars which were to be developed to 6 m height. The mining method was shown to be feasible provided adequate rib support was installed. The benefit of rib support was found to be two-fold, in that it increased confinement of the pillar in zones of low horizontal stress, while reducing horizontal stress relaxation in zones of high horizontal virgin stress. The possiblity of roof control by designing the small pillars to yield on retreat is discussed.

Jan 1, 1986

By S. Kesler

Rössing Uranium Limited has operated since 1976 a large open pit uranium mine and extraction plant at a remote site in the Namib desert, South West Africa/Namibia. The geology (Berning, I., et al. Economy Geology) and the technical aspects concerning mining, grade control and metallurgy have previously been described (Rössing Uranium, Mining Magazin and Whyllie, R.J.M. "Rössing Uranium reaches rated production", World Mining). The improvement of leach 'extraction has been reported in 1984 (Kesler, S.B. et. al. "Uranium extraction at Rössing") and the installation of a central process control system has been described (Kesler, S.B. et al. "The introduction of a central process system at Rössing"). At the beginning of 1983 a decision was made to develop a computer system for metallurgical plant optimisation which included mass and volumetric balances, analytical assays for up to 5 chemical elements and the costs for the major consumables. Within 10 months this computer system was developed and implemented. A large number of test runs were made and computer studies were undertaken. The metallurgical division now has a scientific tool for production; planning for actual comparison with plant results and for strategic investigations and decision making.

Jan 1, 1986

By F. N. Kissell, W. E. Schroeder, N. I. Jayaraman

This article discusses methods of improving airborne capture by conventional dust suppression systems. The work was performed in a full-scale plywood model of a mine entry with a wooden mockup of a Joy 12 CM continuous miner. Dust was introduced at the front of the entry, and water sprays knocked down part of the dust cloud. Sampling in the return air determined the percentage dust reduction. Based on the results, guidelines are offered for continuous miner spray systems to control dust. Empirical relations have been developed to determine the effect of changes in water spray pressure on air movement, dust knockdown, and pollutant concentrations in the face return. Nozzle selection and arrangement are discussed for high dust knockdown efficiencies.

Jan 1, 1986

By J. B. Cabezas

The metallurgical processes that are frequently applied today use strong solutions and are of alkaline, acidic, or organic nature. These play a very important part in recovery of values from many ores. These solutions are of such a chemical nature that they are generally corrosive, flammable, and contaminating. In most cases, they are highly dangerous to the environment. Within the extractive metallurgical industry, it is also very common to have to deal with the handling of contaminating solutions with a high content of cyanide, arsenic, mercury, lead, copper kerosene, acid and many other components whose temporary or permanent confinement within the process must be adequate and absolute.

Jan 1, 1986

In order to formulate appropriate and useful education and training policies and practices, it is crucial to firstly consider the demographic environment of our workforce-and the direction in which it is (known to be) heading. We can predict with a degree of certainty, that the role and influence of training on the future survivability of organisations will- become increasingly critical. This will be particularly relevant for those industries and organisations which are technologically based. The ad-hoc use of training is and, will no longer be appropriate. Organisations must move toward the on-going use of a dynamic education and training strategy based on an effective staff development programme, which meets the short and medium term needs of the organisation. The Technisearch approach is based on maximizing the efficacy of training and learning. The package provides.a total service to meet clients training needs using educational techniques geared to adult learning. it stresses the importance of ongoing research into industrial adult training and its effectiveness in improving skills and productivity. Current research on roles of supervisors in the Australian workplace and the development of the Supervisory Behaviour Questionnaire. (SBQ) indicates the need for a proper framework within which the objectives of training can be addressed.

Jan 1, 1986

By J. R. Woolsey

The cost of an offshore exploration project is mainly dependent on the size of the vessel engaged for the work and increases dramatically with increasing size. Of the various factors influencing vessel size, the type and size of the sampling equipment is typically the principal consideration. This scenario is particularly true of shallow sampling programs employing a vibracore system. The problem develops when certain bottom materials such as densely packed fine sand require sampling. This type of material being one of the most difficult for the standard vibracore systems, with integral core liner, to penetrate to a reasonable depth of some five to seven meters. The problem is mainly related to the excessive cross sectional area of the cutting bit required to accommodate the core liner. The typical solution has been to apply more power to the vibracore drive head which results in a considerable scale-up for the entire system with attendant increase in vessel size. In order to reduce operating cost, M.M.R.I. has developed several systems for deployment from vessels in the 20 meter range. Two systems are modifications to the basic vibracore and a third is a vibralift system. Basically, one of the vibracore units is employed where core liners are required, utilizing a special jet bit designed to reduce the cutting pressure on the bit while not affecting the integrity of the core. The other designed for core extrusion on

Jan 1, 1986

By George J. Allen, Laura A. Allen

Introduction This section of the text presents a general review of the different types of concentrate marketing contracts. Too often the marketing strategy is ignored in the design phase of the project and the producer is left to the mercy of the buyer. Many items such as concentrate grade, impurity levels and moisture content of the concentrate my enhance, or severely restrict the producers ability to make a profit it. Close attention should be paid to the design of the concentrator which can improve the quality of the concentrates, thus the ability to increase the rider of potential buyers can be enhanced. Difficult at best, is the position of the miner who only has one outlet available for its production. Obviously, the trade offs must be evaluated. For example, concentrate grade vs recovery and grind/filtering capacity vs moisture of the concentrate all must be weighted against freight cost to a potential buyer. In addition, the above considerations must be weighed against the capital cost to the miner. This chapter is intended to highlight important articles that are included in short and long term agreements and to give a new miner/producer some insight into hat my or my not add value to the product. Unless the miner sells the product directly to a consumer such as a gold, or silver producer, or to a large enough operation that has a totally intergrated system to make a finished product, most miners are forced to sell to buyers who ultimately will refine and market the product. Types of Contract Agreements There are many types of contract agreements just as there are colors in the rainbow, however, most contracts fall into three basic categories. (1) Smelter Schedules: Designed for the small producer, the odd lot of concentrate, smelter flux and precious metal ore. Albeit custom smelters are becoming fever by the day, because of pollution control requirements and financial difficulties, most remaining custom smelters have a smelter schedule. A smelter schedule is a posted list of charges and conditions that the smelter will buy material from a seller. Smelter schedules exist for copper, lead, zinc, silver and gold (Handbook for Small Mining Enterprises, Montana Bureau of Mines). (2) Short Term Custom Contracts: Large mine producers frequently use Short Term Contracts where the seller has the buyer frame a contract that is tailored to the sellers’ production. The short term contract my be as long as one year. A spot sale qualifes as a

Jan 1, 1986

A new porphyry copper gold district has been discovered at Goonumbla near Parkes in central New South Wales. Endeavour 26 North is the largest deposit known to date with a possible resource of 166.4 million tonnes at 0.74% copper, 0.12g/tonne gold and 1.7g/tonne silver, using a cut-off grade 0.3% copper. Mineralisation is primarily bornite in the higher grade zones and chalcopyrite in the peripheral lower grade zones. Most of the copper, gold mineralisation is associated with potassic alteration. Two mineralised quartz monzonite porphyry intrusive stages have been identified and these are related at depth to a large monz- onite stock which may have been the source of some of the mineralisation. On the basis of detailed paragenesis studies, the potassic zone can be divided into three symmetric subzones. The low grade inner potassium feldspar subzone is confined to the later intrusive porphyry. The outer potassium feldspar subzone is the most highly mineralised alteration halo due to the focussed superimposition of two hydrothermal cycles which have overprinted intrusive and volcanic rocks. The fringing biotite potassium feldspar subzone reveals alteration minerals which are developed early in the paragenesis. Fracture controlled quartz sericite alteration with low sulphide content, fringes and, in part overprints the potassic zone. The restricted pipe-like nature of the alteration zones and related mineralisation suggests that Endeavour 26 North is repres- entative of a multiphase focussed porphyry copper gold system.

Jan 1, 1986

By V. A. Marple, K. L. Rubow

"4.1 IntroductionIn previous chapters impactors have been described as useful instruments for classifying particles by their aerodynamic diameters and for measuring particle size distributions. These impactors can be used most reliably if the user has some understanding as to how the impactor classifies particles and what parameters are important in this classification process. This understanding can best be obtained by a theoretical inspection of inertial principles.This chapter reviews the most recent theoretical impactor work and the latest theoretical efficiency curves. Procedures are then given for using these efficiency curves in the design and evaluation of cascade impactors. Finally, several examples are given comparing theoretical and experimental efficiency curves, pointing out when the theory can be used with great confidence and when the theory should be used only as a guideline.Due to the rather simple principle of operation of an inertial impactor (i.e., the impingement of a jet of particle-laden air on a flat plate) the impactor readily lends itself to theoretical analysis. Three notable works in the early 1950,s were those of Davies and Aylward (1951), Davies et al. (1951), and Ranz and Wong (1952).Davies and Aylward (1951) used a method of conformal mapping to obtain an analytical solution to Euler's equation for the flow of a frictionless fluid through a rectangular impactor. Numerical calculations were then carried out whereby the equations of motion of the particles were solved in a stepwise manner, leading to a determination of the efficiency curves. Since this theory assumed potential flow, the effect of Reynolds numbers on the characteristics of the impactor could not be determined.Ranz and Wong (1952) used an approximate flow field to calculate the efficiency of both round and rectangular nozzle impactors. In the vicinity of the stagnation point, the flow field was assumed to be that of frictionless stagnation flow. Here, the resulting equation of motion for the particles was found to be in a form similar to equations for free vibration with viscous damping. Therefore, the known solutions of the vibration equations were applied directly to the problem and the efficiency curves calculated. This solution technique, however, could not take into account the various geometric variations such as the jet-to-plate distance in the determination of the efficiency curves.The work of Ranz and Wong (1952) was later modified by Mercer and Chow (1968) and Mercer and Stafford (1969) so that the rather simple flow fields of Ranz and Wong (1952) could be used to account for various jet-to-plate distances. The same techniques, however, were used to determine the impactor collection efficiency curves."

Jan 1, 1986

By C. Richard Groves

As the level of technology applied in the electrical measurement, control, and display portions of mine hoist systems continues to advance, the issues and concerns associated with the ramifications of the application of microprocessor technology on the safety-related aspects of these systems become paramount. This report, in part tutorial, addresses several aspects of these concerns. Beginning with discussions of microprocessor-based system architectures, the report addresses some existing and anticipated uses of this technology in mine hoist systems and discusses safety related considerations associated with the areas of data derivation; control and display panels; and system reliability issues. The report concludes with electrical maintenance and inspection considerations associated with the safety assurance of microprocessor based mine hoist systems.

Jan 1, 1986

By Lawrence Pelham

The demand or consumption of fluorspar has been somewhat taken for granted in recent years, except for the specific interest of those that produce, market, and/or consume the commodity. A tradition was established of thinking that as the steel and aluminum industry goes, so goes fluorspar. This is much less true today than in the past. The industry is becoming more dependent on chemical industries that feed primarily off hydrofluoric acid (HF) production. The Bureau of Mines recently published an assessment of world fluorspar reserves and resources that created a foundation of valuable data that can be used to monitor fluorspar availability. Celebrations were held this year commemorating the 100th anniversary of the isolation of fluorine. The United States and other countries continue to struggle with the controversy of ozone depletion and the effect of fluorocarbons on the atmosphere. The goals for the U.S. Government's strategic stockpile are being reevaluated. The market for fluorine chemicals is changing and diversifying, making it a challenge to assess and forecast fluorspar/fluorine demand. This paper reviews the recent past of fluorspar and helps set the stage for a more detailed assessment of this critical commodity.

Jan 1, 1986

The Palmer River rises in the Windsor Tablelands area of the Paleozoic Hodgkinson Basin, 110 kilometres northwest of Cairns. It flows west across the Palmerville Fault and Proterozoic Dargalong Metamorphics to the Mitchell River. East of the Palmerville Fault, its course lies immediately south of the onlapping Mesozoic Laura Basin conglomerates, sandstones and siltstones.Gold occurs in quartz reefs in the Hodgkinson rocks of the Maytown District, in narrow quartz veins in the Dargalong Metamorphics, in the basal conglomerates of the Mesozoic, and more importantly, in alluvial bars within the Palmer River.

Jan 1, 1986

By W. D. Faulkner, J. E. Urbanic, R. J. Jula

The process of treating granular activated carbon for return to service in the recovery of gold in carbon-in-pulp and carbon-in-leach circuits has been investigated. Carbons from two US mines, one Canadian mine, and a South African pilot plant operation were characterized before and after regeneration. Thermal regeneration of the carbon was investigated using factorial analysis to determine the effect of interaction of furnace temperature, retention time, and use of supplemental steam. The operation of acid washing the service carbon was investigated, including a comparison of the use of nitric and hydrochloric acids. The effect of quenching regenerated carbon was also briefly studied. Prom the data obtained, guidelines are given for effective regeneration operation.

Jan 1, 1986

The paper poses certain questions relating to mine design aspects of deep shaft pillars. It then explores these questions in relation to Western Deep Levels (South) where a sub-shaft system is to be sunk to 4 000 metres below surface to exploit two narrow tabular reefs in the down dip extension of the mine workings. After brief discussion of some broad considerations, the findings of a major rock mechanics investigation are reviewed. Some overall conclusions as well as the outcomes of separate studies of the anticipated behaviour of shaft pillars on each of the two reef horizons are outlined. The effect of this behaviour on the barrels of the shafts in the system and on the associated shaft excavations and in-pillar development is Cnnctdarcrl

Jan 1, 1986

By Larry Powell

Rend Lake is an Army Corps of Engineers reservoir located in Franklin and Jefferson Counties in south-central Illinois. The lake consists of 20,000 acres of water and 19,000 acres of public access land. The site attracts over two million visitors a year and is surrounded by campgrounds and other recreational facilities. The lake overlies the largest tonnage of low sulfur coal in the state. Coal is being removed beneath the lake from five mines operated by three coal companies. Currently high extraction mining operations are approaching low-lying, environmentally sensitive, and high-use recreational areas. Advanced planning to maximize coal extraction and minimize potential effects of subsidence requires the development of procedures to assess the impact of high-extraction mining on the land use of the area. The Bureau of Mines, the Corps of Engineers, and the coal companies have initiated research to assess the following proposed planning steps to ensure the maximum recovery of the coal resources while minimizing impacts to surface land use: 1) Establish a dialogue between the surface and mineral owners; 2) develop a geographic information system to aid in assessing existing land use and potential changes; 3) assess the potential effects of subsidence on drainage, wildlife habitats, and changes in land use prior to mining; 4) coordinate the mining displacements with surface activities to minimize disruption; and 5) develop appropriate mitigation plans before mining occurs.

Jan 1, 1986

By D. N. Tallman

The electrokinetic properties of MgO have been utilized to simultaneously filter suspended solids and remove trace amounts of dissolved heavy metals from synthetic mine water. Greater than 95 pct removal of metals from influent at neutral pH containing 1 to 6 mg/L of dissolved Cd, Cu, Mn, Ni, and Zn can be routinely achieved by filtering through a granular bed of MgO at flow rates typical of rapid sand filtration (0.3 cm/s). Filtrate concentrations of most metals can be maintained below 0.1 mg/L for 160 bed volumes or more loading. The more mobile metals (those with larger solubility products) are more difficult to remove, and are strongly bonded to the MgO granules so that chemical stripping with chelating agent is required to clean the bed. Less mobile ions are easily removed by the filter and are effectively stripped by conventional filter backwashing. The fraction of metals recovered by chemically stripping the loaded MgO filters correlates to the zero points of charge of the metals. This process may be applicable to removal and recovery of trace amounts of heavy metals in mine drainage that is partly neutralized by liming. Also, since many of these metals are critical and strategic, the technique can be adapted not only to recycle process water from mineral and milling waste streams, but also to reclaim their metal values.

Jan 1, 1986

By Robert D. Schmidt

The Bureau of Mines is conducting an investigation to develop remediation techniques for residential water wells whose yield has been affected in the long term, by underground mining. Initial work relating to this project was conducted in 1984-1987 at a room and pillar mine in Indiana County, Pennsylvania. Piezometer nest data from the room and pillar mine reveals that a downward gradient in piezometric head exists in shallow strata as a result of drainage into the underlying mine void. The vertical gradient in head in turn results in well bore leakage in open-hole water wells. The relative yield of valley wells is only slightly affected however because the high surficial recharge rate through fractures more than compensates for fracture leakage into the underlying mine. The relative affect of well bore leakage on well yield is greater in certain hillside and hilltop wells that have comparatively low inflow rates at shallow depths. The static water level of such wells is determined to a much greater extent by the chance interception of deep outflow fractures, than is the case for wells drilled in a more intensively fractured valley bottom. The lower static water level of wells that intercept deep fractures does not necessarily reflect the water table conditions outside of a small radius around the affected well. The results suggest that permanently isolating well bore outflow fractures may remediate certain open-hole residential wells that have been affected by high extraction underground mining.

Jan 1, 1986

The Mt Leyshon Volcanic Complex lies 24 kilometres south-west of Charters Towers and is part of a major continental volcano-plutonic province of Permo-Carboniferous age in north-east Queensland.The volcanic complex is located on the contact between Cape River Beds of Cambrian age and the Ordovician Ravenswood Granodiorite Complex. The emplacement of the complex appears to have been structurally controlled and is at the intersection of major north-east and minor north-west trending lineaments. The gold mineralisation occurs in the form of cavity coatings, matrix replacement, disseminations, and vein and fracture fillings containing quartz, chlorite, carbonate, pyrite, sphalerite, chalcopyrite and galena in various volcanic breccias and rhyolitic intrusives. The current published mineable ore reserves, calculated by Noranda Australia Limited, are 6.3 million tonnes of 1.8 grams per tonne gold and 4.8 grams per tonne silver. The orebody is open at depth, and in all directions except north where it abuts the granodiorite.

Jan 1, 1986

Water quality standards for some of the substances likely to be discharged to natural waters by the mining industry are discussed. After briefly examining how uses of water can be affected by discharges, standards for suspended solids and turbidity, pH, and toxic materials are considered. Heavy metals are examined in some detail because of recent public concern regarding their discharge. Caution is given in connection with their analysis at the very low concentrations required for management of natural waters. Finally, the issues of what constitutes a water right concentration compliance breach, and the appropriateness of biological monitoring as a condition on a water right are raised.

Jan 1, 1986