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By C A. Locke, J Cassidy, J L. Mauk

The Waihi-Waitekauri region hosts numerous low-sulfidation epithermal deposits that both outcrop and occur at depth. Zones of intense hydrothermal alteration enclose the Au-Ag bearing quartz vein deposits. Hydrothermal alteration includes the destruction of magnetite by hydrothermal fluids, pervasive silicification adjacent to quartz lodes and potassium enrichment due to adularia and illite deposition. High-resolution airborne magnetic and radiometric, and new gravity data delineate distinct geophysical anomalies associated with hydrothermal alteration and mineralisation. Five magnetically quiet zones occur in the region varying in size from 3 to 34 km2 and in geometry from circular to irregular zones. These zones represent the near-surface extent of strong to intense hydrothermal alteration associated with fossil geothermal systems. All epithermal deposits in the region occur in magnetically quiet zones. Over 120 new gravity stations together with existing data across the Waihi district have defined a positive Bouguer gravity anomaly coincident with the magnetically quiet zone. Eastern and western gradients of 50 gu/km bound the anomaly that contains two flat gravity highs west and east of the Waihi deposit. Strong potassium signatures in airborne radiometric data correlate with outcropping zones of alteration and are consistent with the presence of adularia and illite minerals. Hydrothermally altered zones are represented by areas of low Th/K ratios as a result of low thorium concentrations in andesite and elevated potassium levels in altered zones.

Jan 1, 2003

By C. F. Giermak

Over a considerable period of time great interest has been shown in selective dry concentration of fine ferromagnetic particles, although it is only recently that new permanent magnetic materials have been made available to permit building of such permanent magnetic separators. It is well known that the conventional drum separator does' not efficiently separate fine materials. The centrifugal force on any drum acts in accordance with the particle size and gravity, which may beat varying magnitude-.opposite to the magnetic force, especially when the material is not closely sized. The Magnetic-Mechanical Separator (MMS) is designed for the concentration of fine, unsized magnetic materials where the percentage composition of magnetics to nonmagnetics, or the nature and texture of the materials, is such that its unique agitation and shake-out action with no centrifugal force provides greater efficiency than is obtainable by conventional magnetic separation equipment. This machine consists of a complete double belt conveyor unit with a premagnetizing Axial Pole Agitating Pulley at the feeding end of the lower conveyor belt and a special agitating concentrator magnet above the lower belt of the upper conveyor.

Jan 1, 1965

By M. Sanchez, C. Morales, J. Palacios

The slag produced in the Peirce Smith converters at the Ilo smelter of Southern Peru Copper Corporation has shown a wide range of magnetite content, which introduces an additional problem in the smelting units due to materials? recirculation. However, the operation data analysis and the application of thermodynamic concepts have made it possible to produce slag with magnetite content between 18 and 20%. The results have suggested that matte grade enhances magnetite formation while silica controls its precipitation, and they are also influenced by the increasing temperature of the slag. Thus, in order to obtain the required magnetite content in the slag, matte grade is gradually enriched in equilibrium with slag containing from 25 to 32% silica.

Jan 1, 2004

By Muhammed Şener, Ahmet Gültek

The flotation chemicals are important in mineral processing, and new progress is made in this area day by day. For sanidine purification, some commercial collectors, which can be harmful to the environment, are used. In that respect, the poly(amidoamine) (PAMAM) dendrimers, which are non-toxic for the environment, are good candidates for flotation applications. In this study, the second-generation PAMAM dendrimer was used as a collector to remove magnetite from sanidine by microflotation method, and obtained results were compared with commercial collectors. The results showed that the PAMAM dendrimer is an efficient and selective collector for magnetite. PAMAM adsorption mechanism was determined by zeta potential and FTIR spectra. According to the microflotation results, 87.76% of magnetite recovered at pH 8 by using PAMAM as a collector. It was found that the flotation recovery with the PAMAM dendrimers is similar to the Aero 704 between pH 2 and 6 but less between pH 6 and 9 and more between pH 9 and 12. All experiments were carried out five times and the standard deviation of all results was evaluated with p = 0.05 confidence interval. The second-generation PAMAM dendrimers can be an alternative flotation chemical to the commercial ones concerning usability at a wide pH range, recovery potential, and environmentally benign.

Apr 28, 2023

By R Sridhar, M Fe, W G. Bacon

The problems of magnetite build-up have plagued the non-ferrous pyrometallurgical industry for many years. To better understand these problems, a study was undertaken to determine the thermodynamic variables that affect the behaviour of magnetite under different smelting conditions. Equilibration studies were performed in the nickel smelting systems of matte-gas and matte-slag(silica saturation)-gas. The relationship of thermodynamic variables such as temperature, sulphur and oxygen partial pressure and matte grade on iron and magnetite activities were calculated and the significance on smelting parameters such as metal losses and partition coefficients were defined. The experimental data from this study were employed to develop practical methods which could be used to control the build up of magnetite, as well as to obtain additional metallurgical benefits. In general, a lower sulphur partial pressure and higher temperature operation was shown to enhance the metallurgical benefits of nickel smelting by decreasing the magnetite activity. Operating in this manner can also have added benefits such as higher metal recoveries, more efficient vessel utilisation and efficiency and lower smelter emissions at equivalent or higher primary furnace matte grades.

Jan 1, 2000

By Lyman G. J

Magnetic separator operation in the recovery of magnetite in heavy medium circuits was studied by conducting a series of tests on a full size wet drum magnetic separator.The significant operational variables were found to be feed pan clearance, squeeze pan clearance, dry magnetite feed rate and separator drum speed. With feed and squeeze pan clearances optimized for typical primary separator operation, magnetite loss and concentrate specific gravity were found to be related in a regular manner to dry magnetite feed rate at any drum speed.A two component model of magnetite loss is proposed, relating total magnetite loss to losses in the feed pan and squeeze pan zones. The experimental curves relating magnetite loss to dry magnetite feed rate at the various drum speeds are interpreted in terms of the two component model.The magnetite particle size distribution in the separator was also examined. The tailings magnetite was found to be finer than the feed magnetite only when the dry magnetite feed rate was low, or immediately following the introduction of a new charge of magnetite when the separator was fed at an intermediate dry magnetite feed rate.

Jan 1, 1983

By Gabriel Riveros

The stags from the Teniente Converter (TC) have high copper and magnetite contents. The reduction and copper impoverishment of these slags in an electric furnace was simulated in the laboratory, as part of a conceptual study for the Ventanas smelter of ENAMI. The effect of power input, electrode immersion, temperature of the slag, coke and solid revert additions on the rate of magnetite reduction and copper recovery was investigated. It was found that the addition of solid reverts, containing copper matte, enhanced the recovery of copper. Magnetite stratification and a corresponding gradient of the copper content occurred in the slag. Microscopic examination of slag samples showed the presence of copper in the form of matte and metallic copper inclusions. The results of the experimental work combined with an analysis of the phenomena that take place in an electric furnace led to a better understanding of the slag cleaning mechanism. The successful start-up of the slag cleaning electric furnace at the Ventanas smelter resulted in good copper recovery and confirmed the beneficial effect of solid reverts addition. Electrode consumption is lower than anticipated. No bottom build-up problems have been experienced. Keywords: copper, slag, magnetite.

Jan 1, 2001

By K Edwards, A J. J Mouton

Hematite represents the vast majority of iron ore exported from Australia as the development and processing cost of magnetite is generally seen as a barrier to the development of vast magnetite resources. However, a number of magnetite projects have attracted a significant amount of interest and investment from large Chinese steelmakers.This paper compares the relative merits of the development of Australian magnetite and hematite ore from the point of view of the steelmaker, taking into account the factors that influence the capital costs of the development of the ore types and the relative costs of operating the process plants to treat these ores. By modelling the relative operating cost for the production of hot rolled coil in China for the two ore categories, the paper demonstrates the economic drivers behind the Chinese steelmakers’ large investments in the magnetite resources of Western Australia. It does this by estimating the potential value of magnetite concentrate to the steelmaker in the event that the maximum potential is realised by operating the blast furnace with a 100 per cent pellet burden.Under the conditions described, it was found that direct reduction (DR)-grade magnetite concentrate could command a price premium over 62 per cent Fe fines of up to 46 per cent (December 2014 on a cost and freight (CFR) basis). The corresponding premium for blast furnace (BF)-grade magnetite concentrate is 17 per cent, which demonstrates the dependency on grade.The capital expenses for a 14 Mt/a concentrate plant is estimated at US$3.1 B for BF-grade magnetite and US$3.35 B for DR-grade, with operating expenses at US$45 and US$50 respectively. The corresponding free on board price for a break-even net present value is calculated at US$82/t for BF-grade magnetite and US$90/t for DR-grade. The minimum long-term iron ore price (62 per cent Fe) that would be required to underpin such a project is estimated at US$78/t CFR for BF-grade magnetite and US$68/t CFR for DR-grade concentrate.Apart from the financial benefits, it is demonstrated that the use of magnetite concentrate in ironmaking has the potential to reduce CO2 emissions by approximately 400 kg per tonne of hot rolled coil.CITATION:Mouton, A J J and Edwards, K, 2015. Magnetite – a higher-grade blast furnace feed and its potential benefits for the ironmaker, in Proceedings Iron Ore 2015, pp 613–620 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By G Mark, K L. Blake, G de Jong, J F. Rotherham, N D. Adshead

Magnetite deposits with distinctive ¦ actinolite ¦ apatite-bearing gangue and spatially-extensive sodic-calcic wall rock alteration occur in both Proterozoic metamorphic terrains and Mesozoic-Tertiary magmatic arcs. Examples from both settings constitute significant sources of iron ore (egKiruna, Sweden; El Romeral, Chile) and some host major Cu-Au deposits that have a local association with K-silicate alteration (eg Cloncurry district, NW Queensland; Copiapo district, Chile). A growing body of evidence points to a hydrothermal origin for these systems involving high temperature, low S oxidised fluids. The Cloncurry magnetite-Cu-Au deposits are products of the local structurally channelised influx of a specialised high salinity ore fluid into larger-scale alteration systems developed during pluton emplacement at greater depths than those associated with subvolcanic (porphyry) Cu-Au deposits. The geological characteristics of deposits in magmatic arcs are consistent with a similar mode of origin albeit in rather different tectonic settings.

Jan 1, 1995

The banded iron formations "jasper bars," jaspilites, banded hematite quartzites or banded ironstones, etc., as they have. variously been termed in Western Australia, constitute one of the most striking features of the Pre-Cambrian in this State. They occur in at least two distinct divisions of the Pre-Cambrian, viz., in horizons interbedded with quartzites, shales and thin bedded dolomite in the N~llagine (Proterozoic) Series; and amongst the Older Pre-Cambrian rocks, associated with the metamorphosed sediments of the Jimperding-Chittering Series, the Yilgarn Whitestone Series and the Mosquito Creek Series, and interbedded with metamorphosed basic lavas, tuffs and sediments of the Older prenstone or Kalgoorlie Series.In the Hamersley Ranges in the north-west of Western Australia banded ferroginous cherts are well developed amongst the horizontal sediments of Nullagine Age. These iron formations have recently sprung into prominence as they have been found to form the host rocks for important deposits of· blue asbestos. They are closely comparable with the unique crocidolite-bearing banded ironstones of the Cape Province, South Africa, and have been described elsewhere in some detail by the writer. (1) t .The banded iron formations with which it is intended to deal principally in the following pages, form most abundantly in the Central and Eastern Goldfields of Western Australia where they form portions of the Older Greenstone or Kalgoorlie Series of auriferous rocks. In these regions their chemical inertness and physical hardness provide considerable resistance to the agents of erosion and consequently they frequently stand out in strong topographic relief in otherwise monotonously flat or gently rolling country. These banded-iron formations have proved of considerable direct economic importance in the goldfields and in other portions of the State because of thei!! associations with 'gold, iron -and to' a lesser extent, manganese; whilst indirectly because of their peculiar nature, form and topographic prominence, etc, they have been of tremendous assistance to the field geologist both in the practical application of methods of geological mapping and in the' elucidation of geological structures. Finally, they have recently acquired a new importance in the specialised search for ore-bearing lodes or for structural information over areas of soil-covered country, as their form and composition make them ideal subjects for the use of either electrical or m!1-gnetic methods of geophysical prospecting.

Jan 1, 1941

By Peter Wells, Adrian Sabau, Turgut Yalcin

"The nickel ores of Sudbury contain substantial amounts of the gangue mineral pyrrhotite (Fe7S&) which causes certain diflculties in the milling of these ores. This paper proposes a process called “magnetoflotation” as an effective means of dealing with pyrrhotite. The method reduces the pyrrhotite content of concentrates by applying a magneticjield on the path product as it leaves the flotation cell.Successful performance of magnetoflotation requires the optimization of several variables. In this study, three of the variables (air flowrate, collector concentration, pother concentration) were investigated by Box- Wilson experimental design, and others (magnet speed, grind size, pulp density, flotation time) were examined individually. The process was tested on a Falconbridge nickel ore, assaying 1.92% Ni, and under the best operating conditions, a concentrate was obtained with 13.56% Ni grade and 74.32% recovery in a single step. Further improvements to grade and recovery were possible by cleaning and scavenging. The same ore was also tested with conventional methods for comparison, and results indicated that magnetoflotation performed better.INTRODUCTION“Magnetoflotation” refers to the process of carrying out magnetic separation and flotation simultaneously within the same device, and is intended to prevent magnetic minerals from reporting to the froth products while non-magnetic minerals are being floated. Typical cases where this method might be beneficial include the processing of magnetite and nickel ores. Its use on magnetite ores has been reported elsewhere [Yalcin, 1992; Yalcin, 19931. This paper describes its application to nickel ores, more specifically to the nickel ore of Falconbridge Limited in Sudbury."

Jan 1, 1999

By Krahmann, Rudolf

THE following is an account of a survey undertaken to test the possibility of outlining a kimberlite pipe by magnetouietric methods. Kimberlite is a basic igneous rock closely related to melilite-basalt or alnoite, which occurs either in the form of volcanic plugs or as dikes intruded into rocks of various types and geological ages up to and includ¬ing the Lower Cretaceous. The famous diamond mines of South Africa are all in kimberlite pipes and these pipes are probably the original source as well of the vast alluvial deposits found in various parts of the country. The pipe chosen for this experiment is one that ' occurs on the farm Goedgevonden No. 20, about sixteen miles north of the village of Klerksdorp and ninety miles southwest of Johannesburg. Some prospecting has been done on this pipe and diamonds were produced from it but not in paying quantities. The magnetometric survey was made in June, 1932, by R. Krahmann and H. Wallisch and the results are shown on the accompanying plan. On the plan are shown also the boundaries of the pipe as exposed at the surface and details in regard to the surrounding foundations. These are taken from a geological survey made at a later date by W. Beetz, of Johannesburg.

Jan 1, 1935

By Purushottam Kumar

Keywords: Magnetostriction, magnetic properties, Pd(Fe,Co,Ni) single crystals Fe-Pd, Co-Pd and Ni-Pd alloy systems show appreciable magnetostrictive strains that are of interest for sensor applications. These systems exhibit congruent melting minima. In this work the magnetic and magnetostrictive behavior of congruent melting Fe-Pd, Co-Pd, and Ni-Pd compositions have been examined. The alloys examined include Fe-54.9 at.-% Pd, Ni-45.4 at.-% Pd, and Co-45 at.-% Pd. The paper describes the growth of bulk single crystals of these alloys using Czochralski technique. X-ray diffractometer was used to obtain rocking curves that were used to determine the [001] crystal direction. Magnetostriction in [001] direction was measured using strain gages. Magnetic properties were measured using a vibrating sample magnetometer. Ni-Pd showed the highest magnetostriction values among the congruent melting compositions. Magnetic and magnetostrictive behaviors of these alloy single crystals are presented.

Jan 1, 2005

By Pinai Mungsantisuk

Keywords: Pd-Ni alloys, Pd-Fe alloys, Pd-Co alloys, Magnetostriction, Magnetic Properties The presence of congruent melting minima, the occurrence of ferromagnetic transition over a large composition range, and FCC type crystal structure make Pd-Ni, Pd-Co, and Pd-Fe based systems attractive candidates in our search for materials with no rare-earths, large low-field magnetostriction, and good mechanical properties. The presence of paramagnetic-ferromagnetic transition over a broad range of composition also provides opportunity for fundamental studies. In this work, we have examined the magnetic and magnetostrictive behavior of Pd-Ni, Pd-Co, and Pd-Fe alloys over the entire composition range. Alloy sample rods were prepared by arc melting and casting. X-ray diffractometer was used to obtain lattice parameter data. Magnetostriction was measured along the rod axis using strain gages. Magnetic properties were measured using a vibrating sample magnetometer.

Jan 1, 2005

By Clifford R. Porter

A 200 pound per hour Magnex Pilot Plant was designed and constructed. A non-compliance Eastern Coal which would generate more than 2.0 lb of SOZ per million Btu upon burning was brought into compliance (less than 1.2 lb of S02 per million Btu) during continuous operation of the pilot plant. Approximately 85 percent of the pyritic sulfur was removed while recovering 86 percent of the Btu of the feed coal. Pilot plant operation is summarized and preliminary economics presented. Present status of the Magnex Program is reviewed.

Jan 1, 1977

By D. Rudenko, C. T. Aimone-Martin, J. K. Ratliff, I. G. Wong, J. Aiken, R. E. Burnham, T. A. Davidsavor

A small quarry blast was conducted with a maximum of 90 pounds per delay and shortly afterwards, area residents sensed ground motion and building shaking indicative of an earthquake. In addition, seismometers up to 500 miles (800 km) away recorded a magnitude 2.8 earthquake located in the area. Positioned in a seismically inactive area, southern Minnesota is not known for earthquakes. The earthquake was originally described by the USGS to be a surface blast at the quarry. Analysis showed that the earthquake occurred shortly (approximately seven seconds) after the quarry blast some distance away and well below the surface. This paper describes the evaluation of the “seismic events” including the blast, the following earthquake, initial governmental response, and provides the framework for assessing the relationship between the blast and the earthquake. The paper also discusses management of large volume claims from a complex event and presents a claims management strategy with best practices.

Feb 6, 2023

By J. A. Domenico

A safe and precise mineral separation alternative to heavy liquids is being used for mineral sands exploration on large scale orebodies. The separation process, Magstream®, uses ferro-fluids and magnetic and centrifugal forces to produce precise split points over a range of specific gravities from 1.5 to 18.0 g/cc. This paper describes a commercial scale exploration program treating, roughly, 90 samples per day in Senegal (West Africa). Separation results comparing Magstream® and conventional heavy-liquid separation are presented.

Jan 1, 1994

By A B. Christie, R L. Brathwaite

Since the first occupation of New Zealand in 800 - 900 AD, various useful minerals, rocks, and energy resources have been identified and extracted. The Maori prized greenstone for ornaments, tools, and weapons, used argillite and obsidian for tools, and decorated their carvings and bodies with colours made from clays, limonite, and vivianite. They were aware of coal (waro), but are not known to have used it for fuel. Before 1840, visiting whalers used coal from Shag Point to heat their trypots. Mining activities got underway in the 1840s, with the finding of manganese oxide deposits in the Bay of Islands, Kawau Island, Waiheke+ Island, and Taieri Mouth. Secondary copper ore was mined on Kawau Island (1846 - 1869), and native sulphur was exported from White Island to Europe. The discovery of gold at Coromandel in 1852 and a few years later in Northwest Nelson and Otago opened the way to gold rushes in these areas and subsequently in Marlborough and Westland. Mining of alluvial gold evolved through sluicing to the invention of gold dredges; first (1863) was the simple spoon design, but later (1881) large steam-powered bucket-ladder machines weighing around 3800 tonnes were built. Most of the gold dredges had gone by the early 1960s, following a revival in the 1930s, but one large dredge operates today on the Grey River. Other mining events included: underground mining of coal from 1849 and underground mining of lode gold from 1863 in the Coromandel, Reefton, and Otago fields. Most outcropping coal deposits had been discovered by 1870. Building stones were used by the early settlers for construction of houses, churches, banks, public buildings, and some universities from 1836. Aggregate for roads, railway ballast, and concrete, and limestone for cement and fertiliser, and clays for bricks and china have been quarried for many years.

Jan 1, 1993

South Africa?s primary electricity supplier, Eskom, provides incentives to reduce power demand during critical times by granting capital through a Demand Side Management programme. DSM encourages the end user to review and optimize energy consuming systems and use capital, provided by Eskom, to purchase or modify the equipment required to achieve a load-shift. As part of the DSM agreement the mine ultimately acquires the capital equipment and benefits from reduced power costs, but in return is required to sustain the load-shift tactic for up to five years. The paper focuses on one DSM tactic, main fan energy management. In this case, reduced air flows during selected peak and off peak periods, results in a substantial reduction in peak power demand. DSM incentives provided capital for automated main fan control as well as improved control of the mine ventilation systems. To examine the work in detail Gold Fields Ltd Driefontein gold mine near Johannesburg was chosen as a case study.

Jan 1, 2009

By E. P. Olberg, A. Yu. Chikin, S. V. Petrov, M. P. Belykh, N. L. Belkova

"Bacteria that grow in autochtonous communities of gold heap leaching (HL) wastes are adapted to high concentrations of contaminants and environmental conditions. An example of a mine in the Sakha (Yakutia) Republic showed that the bacterial factor had a significant influence on cyanide breakdown and copper and nickel removal in the conditions of HL ore pile zoning compared to chemical oxidation. The diversity of bacterial communities growing in natural and simulated conditions of a HL ore pile was determined for the purpose of the study. The identified bacterial communities included genus Achromobacter and Serratia, which were found to be adapted to a wide range of temperature and can be considered as potential microorganisms for detoxification of gold HL wastes. INTRODUCTION Technologies and systems of passive treatment are of a special interest in relation to solving environmental problems of gold HL wastes detoxification, when neutralization time is not considered as a limitation (Alvarez et al. 2005). Passive treatment methods are based on reagentless spontaneous breakdown of cyanide caused by natural factors, including activity of autochthonous bacterial communities. Implementation of a reagentless biodetoxification technology for mature HL operations provides reduction of environmental impact on industrial site locations and substantial economic benefits compared to conventional chemical processes of neutralization that prevail in the Russian Federation territory. Passive treatment of cyanide-containing wastes was investigated by M. Botz, T. Mudder, S.V. Petrov, L. Simovic, A. Smith, C.A. Young etc. However, the bacterial factor (autochtonous bacterial communities) role in this process is practically unexplored. Thus, the aims of the study included the investigation of a bacterial factor influence on passive treatment of gold HL wastes and the identification of functional groups of bacteria involved in passive treatment."

Jan 1, 2018