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By J. G. Pearson, F. H. MacDougall, A. G. Galley

The difference in age, host rock lithology, alteration and style of mineralization indicates a fundamental difference in the format ion of gold deposits in the Flin Flon and Amisk Lake areas. The Flin Flon area contains early quartz-sulfide-gold veins fo rmed within intermittently active fractures and later plutonic hosted deposits thought to be generated in a porphyry system. In the Amisk Lake area two types of gold occurrences are recognized: I) gold-quartzcarbonate- sulfide veins within or flanking fault zones and 2) structurally and stratigraphical ly controlled zones of dissem inated and vein type sulfide-gold mineralization within extrusive and intrusive rhyolite and dacite porphyries. Both types of deposits are set within supracrustal rocks. are accompanied by intense alteration haloes and were formed prior to the major deformation event suggesting an early, epigenetic hydrothermal origin.

Jan 1, 1986

By A. R. Barnes, N. O. Lotter

Recoverable economic copper sulphide minerals such as chalcopyrite, bornite, chalcocite and covellite often occur together in varying proportions in the major copper-bearing ores, and have individual flotation requirements and characteristics. Pyrite also occurs in these ores to varying extents as the sulphide gangue, and is problematic because of its natural tendency to float quickly and easily. In a bulk sulphide float, selectivity against pyrite is desirable, particularly if it does not host other paymetals such as gold or silver. At the same time it is a requirement to float all of the copper sulphides despite their electrochemical differences. The electrochemistry and semiconductor properties of these minerals are reviewed, together with implications for flotation with and without collector addition. Mixed collector systems for the improved flotation of these sulphides are proposed as a solution. The use of xanthate and dithiophosphate in the collector suite allows the co-existence of dixanthogen and free dithiophosphate radical because the latter has a higher redox potential requirement than xanthate to oxidise to the dithiolate. Because some of these minerals require dixanthogen, and others, free thiolate, to generate surface hydrophobicity, a bulk flotation of all the species becomes possible in the overlapping area of Eh and pH between the two dithiolate equilibrium lines on the Pourbaix diagram. The arsenic-signature copper minerals are added to the study, since many copper operations encounter arsenic as a penalty element in the saleable concentrate. It is shown that the addition of arsenic to the copper and iron sulphides alters the semiconductor and electrochemistry properties, and in turn, its flotation characteristics. The degree of mineral association and liberation between these minerals can be a complicating factor due to textural associations, and should also be considered in the process as a next step.

Jan 1, 2016

By Christie AB

Stream sediment geochemical analyses from 140 mining company exploration surveys of the Coromandel, Northwest Nelson, Marlborough and Westland regions of New Zealand have been compiled from open file reports and entered on a database called REGCHEM (for Regional Exploration GeoCHEMistry). REGCHEM is supported by GEOEXPL, a custom-written computer software application which operates under the Microsoft Access relational database mangement system on a PC-type computer. The data are plotted as maps using the Maplnfo geographic information system (GIS) package. Thesholds separating anomolous values from background values are determined using the PROBPLOT univariant statistical package, which enables the descrimination and modelling of several populations. Relevant REGCHEM data are being incorporated into a GIS for the Coromandel region as part of ongoing studies to sevelop mineral deposit and metallogenic models for the region, and to assess regional prospectivity.]

Jan 1, 1995

Jan 1, 1962

The case study has identified and characterised additional subsidence arising from longwall mining above or under existing longwall goaf. It suggests that the magnitude, mechanisms and prediction methods for such additional subsidence are different between the two mining configurations. This paper presents a proposed method to predict maximum vertical subsidence due to longwall mining under existing longwall goaf. It suggests that, unless different results from further new cases become available, the findings presented in this article, including the aforementioned prediction method, be applicable to the majority of sites in New South Wales, where multi-seam longwall mining is to take place. This article also presents an important concept of 'overburden modification' due to multi-seam mining. A causal relationship between the above-mentioned additional subsidence and 'overburden modification' has been identified as a result of the case studies. Further investigations into the physical processes that cause such overburden modification will be fundamental to the understanding and management of multi-seam subsidence.

Nov 25, 2010

The Tennant Creek goldfield is situated in the Northern Territory, 360 miles north of Alice Springs, or a tot~l distance of 1,300 miles north of Adelaide, and 600 miles south of Darwin. The auriferous area extends 20 miles north and south by 50 miles east and west. The overland telegraph line and the AIice Springs-Darwin road pass through the centre of the field.HISTORY, PRODUCTIONThe country comprising the goldfield was traversed by J. MacDouall Stuart between 1859 and 1861 in the course of his last three exploring expeditions, which terminated respectively at Attack Creek, Newcastle Waters and at the mouth of the Adelaide River. The explorer named Tennant Creek and also Mount Samuel, on which mining operations are now in progress. The overland telegraph line was completed in 1872 and a relaying station established eight miles north of the site of the present township. There was no other settlement in the adjacent country prior to the opening up of the goldfield.Gold was discovered in 1926 on what is known as the Great Northern lease, three miles north of the township. The field was remote; the nearest plant at which gold ore could be treated was at Peterborough, in South Australia, 1,186 miles distant, and it was not until 1932 that the development of the field actively commenced.The production of the field from its inception to December 31, 1939, was 57,895 QZ. of gold, valued at £522,000, recovered from 61,793 long tons of ore, won from 98 mines. In 1940 seven of these mines had reached depths between 100 ft. and 230 ft., the workings of the majority being less than 60 ft. below surface.TOPOGRAPHY, WATERThe country is traversed by parallel and sub-parallel lines of hills trending east and west and rising to altitudes varying from 50 ft. to 100 ft. above the intervening valleys. The low ranges and isolated hills owe their survival to the resistance offered by their indurated, harder rocks to erosion which has removed the softer intervening formations. Their elevation and area depend to a considerable extent upon the presence of; and, the size of, the more or less exposed haematite formations, or are due to the influence of extensive siliceous dykes which traverse the locality.Watercourses head from the hills and either flood out on the flats within a short distance, or in a few cases follow longer courses to the northward. In the channels of the larger creeks billaoongs, which form important water storages for a considerable part of the year, -are to be found. Tennant...

Jan 1, 1942

By T. M. Gurr

In response to concerns voiced by local, state, and federal agencies and various environmental groups, the Central Florida Phosphate Industry and various governmental agencies have been investigating methods to accelerate the consolidation of waste clays generated during phosphate washing and beneficiation processes. The objectives of research efforts have been to reduce the storage volumes required for clay waste, accelerate reclamation and to return the land to approximate pre-mining topography. Government and industry research to accelerate waste clay consolidation has evolved two general methods: gravity thickening and chemical flocculation. Gardinier, Inc. one of the phosphate mining companies, evaluated the use of synthetic (polyacrylamide) flocculants as an alternate waste clay thickening method in response to mining conditions encountered at their Fort Meade Mine and the proposed North Hardee County extension of the Fort Meade mine (Figure 1). After considerable research and evaluation, the Alsthom-Atlantic Clariflux Super-flocculation method was chosen by Gardinier, Inc. as a method to seriously consider for use at their Fort Meade mine.

Jan 1, 1986

By Wilbur I. Duvall

In this report, the Bureau of Mines presents a theoretical solution for the stresses and displacements in an infinite elastic plate containing a circular hole the boundary of which is loaded by applied radial stresses over four separated arcs. The problem solved is a two-dimensional approximation of the stresses and displacements developed by a large tunnel-boring machine anchored in a circular tunnel. Analysis of the solution shows that the tangential tensile stresses induced on the boundary of the circular opening can be minimized in the roof and maximized in the floor of the opening by proper spacing and loading of the four arcs.

Jan 1, 1967

By Mary Nelima Ondiaka, Oladunni Oyelola Alabi, Fatai Olufemi Aramide, Francis Gitau, Talabi Henry Kayode

Iron ore is essential in steelmaking but high-grade ores have diminished, making it necessary to turn to low-grade ores, which need further beneficiation to upgrade the iron content. Biobeneficiation techniques such as bioleaching, bioflotation and bioflocculation have proven successful in iron ore processing. Consequently, these methods have emerged as sustainable alternatives to conventional beneficiation. The biobeneficiation processes occur in mild conditions using bioreagents and biosurfactants derived from microbes, and offer a reduction of chemicals used in processing. This potentially offers methods that are relatively energy efficient, cost effective and environmentally friendly while tackling the constraints of dwindling high-grade iron ore resources.

Sep 1, 2024

By Iván Salas

Los bofedales (humedales altoandinos) son considerados ecosistemas frágiles, con características y recursos singulares, con baja resiliencia ante eventos naturales y presión antropogénica los cuales producen una profunda alteración en su estructura, composición y funciones, estas características hacen que la protección de estos ecosistemas sea legislada a nivel nacional e internacional. Hudbay Perú viene ejecutando el Plan de Manejo de Bofedales como parte de su compromiso de compensación ambiental el cual tiene como objetivo mejorar las condiciones del ecosistema del Bofedal de Cochapampa ubicado en territorio de la comunidad campesina de Chilloroya a 4300 m.s.n.m (comunidad de influencia directa de la Unidad Minera Constancia).

Sep 30, 2022

By Ann M. Hagni

One of the most costly factors in the production of aluminum is the consumption of energy in the form of electricity. Energy consumption is increased as refractories in the Hall-Heroult reduction cells are corroded by penetration of the fluxes cryolite (Na3AlF6) and villiaumite (NaF). To decrease thermal conductivity and refractory waste, protective barrier linings are installed. Dry powder barrier linings form stable reaction products at cell operating temperatures. Four dry powders composed of vermiculite, corundum, wollastonite, and anorthite are characterized mineralogically by X-ray diffraction, reflected light microscopy, scanning electron microscopy, and cathodoluminescence microscopy in this research project.

Jan 1, 1998

By C. Kloppers

The aim of this investigation was to reduce the cost of primary steel de-oxidation by substitution of aluminium primary de-oxidation with a practice that uses carbon. The cost of carbon is four times lower than that of aluminium. The application of carbon would directly result in raw material cost savings. Investigations were conducted at Iscor?s Newcastle steel plant on various steel grades. Specific production aspects were emphasized to ensure that the cost savings accrued would not create secondary expenses. These production aspects entailed: ?Yields on de-oxidation elements ?De-oxidation capabilities ?Alloying yields (Mn and Si) ?Carbon-pickup ?Nitrogen-pickup ?Temperature loss during tap ?Steel cleanliness ?Slag morphology. This project proved that carbon de-oxidation, apart from reducing de-oxidation raw material cost due to cheaper raw materials being used and lower consumption rates, resulted in steel that is cleaner and has lower nitrogen concentrations. Carbon primary de-oxidation has been implemented at Iscor?s Newcastle plant on a large range of steel grades, ranging from ultra-high carbon (> 0.60% C) to ultra-low carbon (< 0.03% C) grades. A net saving of between R100 000 and R200 000 per month was achieved.

Jan 1, 2001

By Brad Wahlquist

An ex-situ biological treatment system was implemented at a gold mine site in South Dakota. The system removes selenium and nitrate from a mixture of groundwater and surface water runoff at ambient water temperatures. The Applied Biosciences? system replaced a denitrification system that did not perform consistently, did not treat for selenium and required heating of the influent water. Installation was completed in phases starting with the selenium circuit being brought into operation in February, 2002 and the nitrate circuit in March, 2002. System design can accommodate average flows of 380 L/min (100 gallons/minute) and a maximum flow of 1,136 L/min (300 gallons/min). Four cells were designed to remove nitrate from approximately 30 mg/L to below 10 mg/L and two cells were designed to remove selenium from 0.01 mg/L and higher, to below 0.005 mg/L. No pretreatment is required to operate the system at ambient temperatures, which can fall as low as -12C in the winter, and treat water at temperatures ranging between 8C to 16C. Nutrient requirements are met using a sugar based nutrient mixture that includes a balanced C:N:P:S ratio, trace elements and vitamins. Since start up, the system has consistently been in compliance for nitrate and selenium, treating water to below detection limits for both contaminants. This paper discusses laboratory biotreatability testing of a system designed to remove selenium, arsenic, and nitrate and full-scale implementation and optimization of a system to remove nitrate and selenium.

Jan 1, 2003

By L. A. Rapoport

This paper outlines the methodology and results pertaining to the simulation of the U.S. coal industry in the context of an integrated, time-dynamic model of Long-Range Energy Developments and Supplies (LORENDAS). By way of background we will present first an overview of the overall LORENDAS model structure. We will, then, outline the characteristics of the formulation and data used for the representation of the U.S. coal industry. Finally, a series of model results will be reviewed, with particular emphasis on the long term projections of coal production and distribution under different basic economic and/or political scenarios.

Jan 1, 1977

By Wilton Johnson

Native asphalt was produced in 1981 by five companies in three States, Alabama, Texas, and Utah. Texas was the leading State in production of native asphalt. Total production increased in 1981 to 1.26 million tons, while value increased 10.5% to $27.7 million. Bituminous limestone, used primarily for street and road repair, was produced by Whites Uvalde Mines and Uvalde Rock Asphalt Co., both in Uvalde County, Tex., and Southern Stone Co., Colbert County, Ala. Gilsonite was produced by American Gilsonite Co., Uinta County, Utah, and Ziegler Chemical and Mineral Corp., Weber County, Utah. This material was used for purposes other than road repair.

Jan 1, 1982

By Anthony T. Lannacchione, Donald G. Puglio

The Bureau of Mines developed data on the methane content of the Hartshorne coalbed, Haskell and Le Flore Counties, Okla. The methane content is calculated to be between 1.1 and 1.5 trillion cubic feet, based on an estimate of total coal in place of 2.4 to 3.2 billion short tons. Methane increases with depth, but the rate of increase decreases with greater depths. Degasification in advance of mining is recommended for all mines operating at depths greater than 500 feet to reduce hazards and methane explosions, decrease mine ventilation costs, and conserve the natural gas that would be otherwise wasted.

Jan 1, 1979

By Wen H. Su

Extensive investigation has been conducted to determine the causes of a series of roof falls occurring in a room-and-pillar working located in southern West Virginia. Underground observation, along with laboratory testings and finite element analyses were conducted to search for possible mechanisms for the roof falls. Results of the investigation have led to a better understanding of the mechanisms involved in the roof falls. Necessary modifications of mine layout and roof support plan are proposed for improving safety and profitability at the mine.

Jan 1, 1984

By H Han, L Lu

Due to the international depletion of reserves of traditional high-grade iron ore, the ore resources available throughout the world, especially in steel mills in East Asia, have changed drastically from hard hematitic to more goethitic ore types, such as pisolitic and Marra Mamba ores. The level of impurities and loss on ignition in iron ore has also been slowly increasing. Finally, the proportion of fine material in the available products has increased considerably for most iron ore fines. This has been found to have significant impacts on sinter quality and sintering performance. Magnetite concentrate is typically high in Fe grade and releases extra heat when oxidised to hematite. The amount of magnetite concentrates is expected to increase due to the recent development of a number of magnetite projects. Some of these magnetite concentrates will end in sinter blends. This will not only improve the sinter quality and but also have a beneficial impact on the fuel consumption of the sintering process. However, most of the concentrates available are very fine, which will negatively impact the green bed permeability and consequently the productivity of the sintering process. This paper reviews and comments on the recent technological advances in sintering with high proportions of magnetite concentrates.CITATION:Han, H and Lu, L, 2017. Sintering technologies of sinter mixtures containing high proportions of magnetite concentrates, in Proceedings Iron Ore 2017, pp 31–38 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By P D. Katsabanis

According to Persson(1) steady state detonation along a cylindrical charge can be regarded as a self propagating process in which the axial compressive effect of the shock front discontinuity changes the state of the explosive so that exothermic reaction sets in with the requisite velocity.

Jan 1, 1990

By James R. Arnold

Over the past few years several commercial wetting agents and drying aids have been tested in the lab and in the plant at Gold Fields Mining&apos;s operations at Mesquite and Ortiz. The major goal was to increase recovery with these surfactants by improving the permeability of the pad and increasing the rate of penetration through the rock.

Jan 1, 1988