Search Documents

By Gabriel Voicu, Marc Bardoux, Ross Stevenson, Nuno Machado, Jean Lafrance

"Abstract - Paleoproterozoic gold is found in two different volcano-sedimentary sequences and intrusive bodies separated by 600 km within the Guiana Shield. The 2148 Ma St-Élie granite intruded volcanic-arc sequences of the Paramaca Group, whereas the 2096 Ma Omai stock penetrated backarc/ island-arc sequences of the Barama-Mazaruni Group. Positive ?Nd values suggest that both suites lack Archean crustal contaminants, which is consistent with an origin in an oceanic arc setting.The St-Élie deposit is characterized by quartz-dominant vein systems with minor metallic minerals, represented chiefly by pyrrhotite and pyrite. Biotite, calcite, and chlorite are the main gangue minerals. The alteration haloes at St-Élie feature a strong potassic zone, which is absent at Omai. The ore-controlling structures are ductile and the vein emplacement is related mainly to contemporaneous, high-angle ductile shear zones. The St-Élie deposit formed at temperatures >350°C. The stable isotopes values are compatible with a magmatic or metamorphic source.The Omai deposit is characterized by quartz-dominant vein systems with minor metallic minerals, represented mainly by pyrite. Ankerite, scheelite, albite, and chlorite are common gangue minerals. The vein emplacement is syn- to post-deformation and it is related mainly to brittle shear zones with low-angle, stockwork networks and breccia zones. The Omai deposit formed in a temperature range between 250°C and 170°C, much lower than the St-Élie deposit. The stable isotope values are compatible with mixing between deep-seated fluids of metamorphic or magmatic origin with surface- derived fluids.These differences between St-Élie and Omai are interpreted in terms of their depth of formation. Alteration patterns, structural elements, and paragenetic assemblages indicate that the gold at St-Élie was most probably emplaced at a mesozonal depth, whereas the Omai setting yields evidence for epizonal conditions."

Jan 1, 1999

By J. M. Livingstone

"This paper covers some of the problems confronted by Canada's railways in moving bulk materials from their source to the dock-site. The ""cost center"" concept is presented, and hypothetical examples of its use given. Also discussed are systems design, the unit train and pipelines.INTRODUCTIONCANADA LIVES BY RER EXPORTS and the Port of Vancouver by the exports of the Mountain and Prairie Empire at her back. The most recent estimates of off-shore shipments of bulk from the Port of Vancouver rise to 35.8 million shipping tons in 1985 and deep-sea general cargo estimates, in and out, are estimated at 7.6 million shipping tons for the same year. This compares to 7.67 and 2.87 million shipping tons, respectively, in 1965."

Jan 1, 1968

By W. E. Roscoe

The probability of making an exploration discovery in Canada can be calculated from Derry's (1970) data on exploration expenditures and number of discoveries over the last nineteen years. Considering an average exploration "try" to be $30,000, the probability of a discovery with one try has decreased tenfold from about 0.01 in 1951 to 0.001 in 1969. A plot of these probabilities can be extrapolated to the future, giving a 1969-71 three-year average probability of 0.00096 with 90 per cent confidence limits of 0.00042 and 0.00153. Using this probability, various calculations can be made, such as (1) the probability of making at least one discovery for any given exploration expenditure, (2) the probability of ultimate ruin or survival of the exploration investment process and (3) the expected value of an exploration investment. There is a critical minimum amount per discovery that must be re-invested in exploration, no matter how large the original investment is, for exploration to survive at all in the long run. Currently, this critical minimum is $31,200,000 with 90 per cent confidence limits of $19,600,000 and $71,400,000.

Jan 1, 1971

By Thom Mambe, Angelo Fernando

The objective of this work was to identify key parameters related to the reduction of the sulphur content in ammonium diuranate (ADU), and the identification of solid products being formed under various operating conditions. A laboratory-scale, continuous ADU precipitation circuit was assembled using a glass reactor vessel immersed in a temperature-controlled water bath. A pre-prepared uranium feed solution was fed continuously using a peristaltic pump. Anhydrous ammonia mixed with compressed air was metered and pumped using a double-headed peristaltic pump. An over-head mixer was used to keep the solids in suspension. The precipitated ADU slurry was removed from the reactor at the same flow rate as the feed solution. The slurry was sampled to generate ADU solids for chemical and physical analysis after four hours of continuous operation to ensure steady-state conditions. The following variables were studied to determine their influence on the sulphur content in the resulting ADU. (a) sulphate:uranium molar ratio in the reactor (1:1, 1:5, 1:10 and 1:20) (b) precipitation pH ( pH 6, 6.5, 6.9, 7.5 and 9) and (c) precipitation temperature (40C and 60C) A total of 18 tests covering the above parameters were conducted, and the results indicated that the sulphur content in the resulting solids was highly dependent on the reaction pH. Out of the pH levels tested, tests completed at pH 6.9 and 7.5 generated solids containing the lowest sulphur contents, between 0.5 to 1.5% S uranium basis (UB). The sulphur content in solids was found to vary linearly with the sulphate:uranium ratio in the feed solution, showing a statistically valid correlation. The impact of temperature was minor between 40°C and 60°C, with a slight advantage at higher temperatures. Tests at a sulphate:uranium ratio of 1:1 produced solids with the lowest sulphur contents. The influence of pH or temperature on sulphur content in solids was almost non-existent at this sulphate:uranium ratio. Precipitation pH is the major factor influencing ADU sulphur content, followed by the uranium to sulphate ratio.

Jan 1, 2020

By D. H. C. Wilton, W. A. Sears

"Abstract-The 682.8 ± 1.6 Ma Tickle Point Group consists mainly of rhyolite flows and tuffs with- in the Avalon Zone of the Appalachian Orogen in Newfoundland. Stratabound massive sulfide mineralization, consisting of pyrite, sphalerite, chalcopyrite and galena, occurs at the Winter Hill prospect, where a lower pyritic, Cu-rich zone and an upper Zn-Pb-rich zone are hosted by a carbonate-calc-silicate lens. At the Frenchman Head prospect, stringers of pyrite, minor sphalerite, chalcopyrite and rare galena are hosted by felsic volcanic rocks of the Tickle Point Group .Base metal ratios, metal zonations and the overall stratigraphic framework suggest that these sulfide occurrences represent volcanogenic massive to semi-massive sulfide mineralization (stringer type at Frenchman Head). As such these prospects represent the only known VMS occurrences within the Avalon Zone of Newfoundland. Pb isotope data indicate that galena from the Winter Hill prospect is less radiogenic and older than galena from Dunnage Zone occurrences, and suggest that the Winter Hill mineralization formed in an environment tectonically distinct (exotic) from the Dunnage Zone."

Jan 1, 1996

By Jonathan Ruiz Lizardo, Met-Chem Canada Inc., Flavio Ccuno, Constante Umipig, Ewald Pengel, José Ruiz

"Cerro de Maimón is located in the Dominican Republic on the island of Hispaniola approximately 75 kilometers northwest of the capital city, Santo Domingo. The processing facility consisted of two separate processing plants for oxide and sulphide ores. The oxide plant processed oxide ore bearing gold and silver ore using cyanide leaching and Merrill Crowe processes, while the sulphide plant produced a copper concentrate using conventional flotation. Cormidom is a commendatory example how mineral processing facilities can co-exist in balance with the environment. In 2014, natural occurring copper oxide contamination with finer grained copper-zinc sulphide mineralisation was expected to dominate the sulphide ore body. In anticipation Cormidom contacted the original plant designer Met-Chem to assist in overcoming this challenge. Test work indicated that increased flotation time and subsequent very fine grinding were required. Met-Chem provided the detailed engineering and Cormidom proceeded with the expansion project internally. Currently Cormidom has processed the sulphide ore successfully by implementing flotation modifications. This paper describes the history of Cormidom, test work on the “new” ore body, modification in process design in the Cu-Zn sulphide flotation circuit, construction and implementation.INTRODUCTIONCorporación Minera Dominicana (CORMIDOM) was a wholly owned subsidiary of GlobeStar Mining Corporation (a Canadian based minerals exploration company) with extensive exploration of base and precious metals in the Dominican Republic. In 2007-2008 CORMIDOM constructed the Cerro de Maimom project. The company was subsequently sold and purchased by Perilya Limited from Australia in 2013. Cerro de Maimón is located in the Dominican Republic on the island of Hispaniola approximately 75 kilometers northwest of the capital city, Santo Domingo. It is near the town of Maimón in Monsenor, Nouel Province (see Figure 1)."

Jan 1, 2016

By P. L. Li, B. X. Song, C. H. Wang, T. Wang, Z. Hu

"The treatment of an oxidized copper-gold ore by stage cyanide addition was investigated. For cyanidation, free cyanide ion concentration can be an indicator of whether there is copper dissolved in cyanide solution, and maintaining the free cyanide ion concentration lower than 1.0 g/L could be an effective way to prevent copper dissolution and reduce cyanide consumption. For that purpose, stage cyanide addition was introduced to control free cyanide ion concentration within the range from 0.8 to 1.0 g/L. Cyanidation tests results indicate that gold extraction was still acceptable at reduced cyanide consumption with a lower copper extraction. Based on the experimental study, industry application works at Beiya concentrator of Yunnan province, China were successfully conducted. When the raw ore contains 2.95 ppm Au and 0.75% Cu, by stage cyanide addition method, the gold extraction was still 93% at reduced cyanide consumption of 2135 g/t, which was only half of one addition method, and the copper extraction dropped to only 5%, which indicated that dissolution was prevented for almost 75% of the malachites.INTRODUCTIONCyanide with its competency to form a strong complex with gold, is the most preferable lixiviant for gold leaching. However, cyanidation is not inherently a selective process since many other minerals present in the ore are also readily soluble, especially the copper minerals. Muir (2011) reported that every 1% reactive copper present in the ore consumes about 30 kg/t NaCN, which can have detrimental effects on the process efficiency and economics due to high cyanide consumption, reduced gold leach rates and poor gold recovery."

Jan 1, 2016

By Y. Héroux, A. Chagnon, M. M. Savard

"Résumé- Le gîte de Pb-Zn de Gays River s'accompagne d'anomalies des propriétés de la matière organique (MO) et des assemblages de minéraux d'argile (AMA). L'association entre la minéralisation, la distribution de la réflectance de la MO et des AMA suggère que ces traceurs peuvent servir à l'exploration des sulfures de métaux de base dans cette région.A l'emplacement du gîte, la réflectance varie considérablement (0,80% à 1,88%), pouvant même afficher une baisse avec l'enfouissement, ce qui est interprété comme une altération chimique de la MO. Les valeurs les plus élevées s'accompagnent localement de quelques textures en mosaïque et délimitent une anomalie thermique au centre sud de la région. Parmi les minéraux des argiles identifiés, l'illite et la chlorite sont terrigènes alors que la smectite, la kaolinite et la corrensite sont authigènes et, à l'instar de l'altération de la MO, résultent des nouveaux équilibres chimiques créés suite à la précipitation des sulfures.Abstract- The Gays River Pb-Zn ore deposit is associated with anomalies defined from the characters of the organic matter (OM) and from the clay minerals assemblages. The relationships be­ tween these anomalies and the mineralization at the mine suggest that these parameters can be used as new guides for the exploration for base-metal sulfides in this area.The vitrinite reflectance (RJ shows a wide range of values (0.8% to 1.88%) and exhibits an anomalous suppressive effect with depth of burial at the mine site, suggesting a chemical alteration of the OM. The highest R, values are associated with mosaic textures and outline a thermal anomaly at the south-center of the studied area. Among the identified clay minerals, illite and chlorite are terrigenous, whereas smectite, kaolinite and corrensite are authigenous and, like the alteration of the OM, are due to the new chemical equilibria resulting from the precipitation of the sulfides."

Jan 1, 1994

By J. E. Nesset

Significant progress has been made over the past few years on characterizing and understanding the hydrodynamic properties of frothers and collectors and their effect on flotation performance. This new understanding of the relationship between chemistry and hydrodynamics has dramatic implications for how flotation circuits should be controlled and optimized. Previous work has shown that choosing a frother of the right 'strength' is critical to the optimization process, and the work and discussion presented here serve to strengthen the argument. In addition, we know that collector chemistry may also influence hydrodynamic properties and needs to be taken into consideration. To achieve the desired outcome, the overall system of reagents and operating parameters must be considered. This paper describes and discusses some of the findings from recent research on frother and collector chemistry effects (on hydrodynamics), and how this knowledge can be used to improve flotation performance. Examples from plant experience are discussed.

Jan 1, 2009

By M. Pfeifer, M. N. Brodie, D. J. Barratt

"This paper reviews design trends related to the various SAG mill configuration and drive options available today. The impact of these options on capital and operating costs is assessed, and key technical issues reviewed. The discussion is based on the conventional North American ’pancake’ mill configuration. IntroductionDuring the past decade mill technology has evolved significantly in the following key areas:• improvements in variable speed motors continue with on-going advances in electronics;• ring motors, or gearless drives, are becoming more common in mill sizes 32 ft and larger, with ratings of 10 000 HP and greater;• geared drives have become available up to ratings of 9500 HP per pinion, compared to the earlier 6000 HP guideline;• improvements in speed reducer technology due to the use of carburized and ground precision gearing, make the high speed motor-speed reducer drive more competitive with the direct coupled low speed motor drive;• a unique speed reducer drive is being introduced to this industry which combines ring gear drive pinions with speed reduction. mprovement in gear alignment is claimed, and the overall drive arrangement is more compact than is possible with a conventional speed reducer drive;• the first 38 ft and 40 ft diameter mills have been designed and manufactured; and • application of large multi-shoe bearings have made shell supported mill configurations available for all, including the largest sizes. These designs have flat instead of conical mill shell ends, and have the potential for technical and cost advantages compared to conventional trunnion supported designs.This proliferation of mill design features provides several options to those involved in planning and design of milling plants, and requires more extensive evaluation to optimize mill design features to best suit specific project requirements."

Jan 1, 1999

By C. Nikolic

A process utilizing ozone for the precipitation of cobalt from nickel sulphate liquors containing ammonium sulphate has been developed. Best results were obtained using nickel carbonate to maintain solution pH at 5.0 to 5.5. Work was performed both in column and stirred-tank reactors. Variables studied included neutralizer type and concentration, NH4+ concentration, temperature, Ni++ and Co++ concentration, per cent O3 in the O2 carrier gas, O3 input rate and agitation. The over-all rate of cobalt rejection increased sharply with increasing agitation and ozone concentration in the gas phase, reflecting relatively slow transfer of ozone from the gas to the liquid phase.

Jan 1, 1978

By Claudio Acuña, Sergio Romo, Gerardo Fuentes

The leaching kinetics of a zinc concentrate in autoclave reactors were studied. A sample of concentrate from Bolivia, with typical mineralogical characteristics of the Andes region, was used. A concentrate containing 49% zinc and 145 ppm of silver from Minera Viacha was characterized chemically and mineralogically (atomic absorption, X-ray diffraction, and SEM microscopy) and tested in bench scale reactors. Two types of autoclave batch reactors were used at 40 bars of oxygen pressure and three levels of temperature (150°C, 200°C and 250°C). The solid to solution leaching ratio was 1:10 (10% sulphuric acid concentration). The effect of the particle size of the concentrate on the leaching kinetics was studied (P80: 145 and 45 µm). Iron from the leaching solution was removed by precipitation by increasing the pH in order to generate a clean solution for zinc electrowinning. The zinc solution was used to evaluate the feasibility of cathode production at the laboratory scale. Zinc extractions with higher liberation (P80 = 45 µm) reached up to 98%. Ground concentrate with finer sizes resulted in agglomeration and the use of dispersing agents did not improve slurry mixing. The leaching solution contained 55 g/L zinc and 7 g/L iron; it was purified by precipitating iron. The precipitation was evaluated using sodium hydroxide and ammonium hydroxide. In the first case, a colloidal suspension of ferric salts was formed while in the second case, different iron compounds were precipitated. The precipitate obtained with ammonium hydroxide had better filtering properties. Electrowinning was carried out using two types of cathodes (stainless steel and aluminium) and solutions purified with ammonium hydroxide. Zinc cathodes formed on stainless steel presented a better physical quality than those formed on aluminium.

Jan 1, 2015

By Margaret Anne Stephenson

Today, in Australia, it is increasingly common to see agreements between Indigenous peoples and resource companies being achieved generally as Indigenous Land Use Agreements or agreements pursuant to the ?right to negotiation? process under the Native Title Act 1993 (Cth). Despite progress in this area, resource development on Indigenous lands is not without its challenges for both the resource proponents and the Indigenous parties. History demonstrates that resource development on Indigenous lands has produced struggles between the traditional owners of the land and the resource proponents. In Australia their relationship is generally defined by issues of access to land and assuring continued access to the land for the life of the project. In this context, divisions in Indigenous communities often emerge. The proposed resource project can have the effect of polarising members of an Indigenous community. It may be regarded by some traditional land owners as an advantageous opportunity for the community and by others as a hazard to country and culture. The process of agreement making has proved not only a test for the Indigenous community but also for the resource proponent. In this paper we undertake a contemporary case study of a proposed Australian resource related-development project on Indigenous lands. This project involved a multi-billion gas hub precinct proposed at James Price Point in the Kimberley region in Western Australia. The James Price Point proposal produced a litany of challenges for all parties. The traditional owners faced fundamental social and human rights issues, including a minority opposition to the project, the project's potential cultural heritage impact, the threat of compulsory acquisition of their native title interest by a State government due to an initial failure to settle an agreement, a fracture of their unsettled land claim and a minority rejection of the agreement ultimately reached. Additionally, the ?green? lobby also rejected the proposed gas hub on environmental grounds bringing the green lobby into direct conflict with both the traditional owners in favour of the project and the resource proponent. Ultimately, Woodside announced its decision not to proceed with the proposed gas precinct at James Price Point, in April 2013. In this paper we analyse the complexity of the James Price Point gas hub negotiations with the traditional owners which resulted in an Agreement that promised to deliver substantial benefits for the Indigenous communities. We question why such a favourable and beneficial agreement for the Indigenous community also produced the plethora of challenges and concerns and we consider how future negotiation processes could be better structured to avoid the difficulties that have confronted Indigenous land owners and resource proponents alike.

Aug 1, 2013

By Dogan Paktunc, Larry J. Hulbert, Robert C. Carne, D. Conrad Gregoire

A thin layer of stratiform Ni-Zn-PGE sulfide mineralization of sedimentary-diagenetic origin was deposited during the Middle to Upper Devonian in the euxinic "Nick basin". The mineralized unit (=3 cm thick), which seems to have been developed over the entire sedimentary basin of > 80 km2, consists of pyrite, vaesite (NiSz), and sphalerite. The average grade of the mineralization is about 5.30/0 Ni, 0.73% Zn, =770 ppb (pGE+Au), and up to 61 ppm Re. Anomalous Se, As, Mo, P, Ba and U are present. A minimum of 0.90 x 106 tonnes of Ni were deposited in the basin (based on a bed thickness of 3 cm) during the Devonian. The unique metal association, extensive lateral distribution, persistent metal grade, mineralogical makeup, and stratigraphic control demonstrate that this is a new deposit type and a new geological environment for Ni and PGE + Au. The sulfide layer occurs at the base of a Phosphatic Chert Member which is underlain by a distinctive marker unit consisting of concretionary limestone structures. The limestone spheroids may represent a vent-specific carbonate facies developed adjacent to faults that emanated nutrientrich hydrothermal discharges just prior to the main mineralizing event. The suite of elements associated with the Nick mineralization suggests that the ore-forming metals were originally bound to organic matter derived from decaying marine organisms. Discharge of hot brines bearing organic matter-bound metals took place along numerous conduits within basin faults that are now manifest as bitumen veins. Our syndiagenetic model proposes that these fluids were discharged laterally from the conduits into the unconsolidated bottom sediment (ooze). The introduction of this metalliferous fluid, rich in organic matter, stimulated biological activity and bacterial reduction of its contained 804 to sulfide. Hot, dense, laterally migrating hydrothermal fluid precipitated thin sulfide-rich larninae within bottom sediment. Published thermodynamic studies suggest that the diagnostic vaesitepyrite assemblage crystallized at approximately 138°C. The 034S values range from -14.7 0/00 to -10.00/00 and are up to 340/00 lighter than locally surrounding sulfides and age-equivalent mineralized strata elsewhere in the Selwyn Basin. The Ol3C values of calcite in the footwall of the mineralized unit (- 12 0/00 to -6 0/00) are isotopically much lighter than regional values. The lighter isotopic character is attributed to the hydrothermal discharge of fluids enriched in organic compounds. Although geochemical profiles of the lower Earn Group sediments that host the Nick mineralization reveal that these black shales are not distinctive, the unusual Ni, Zn, PGE, U, Ba, and P elemental associations and their anomalous concentrations in stream sediments can be used to explore for this deposit type.

Jan 1, 1992

By J. E. Hawley

"The Aldermac copper deposit is in Beauchastel township, Abitibi county, Quebec. It lies about 11 miles west of Noranda. It has been described by Cooke, James, and Mawdsley(2) and by Bruce(3) and has been mapped in detail by W. Samuel and the late K. W. Fritzsche, former Mine Geologist, and by J . E. Gill and A. R. Byers, so that most of the particulars contained in the description that follows are largely the result of the work of others than the writer, whose connection with the deposit, in a consulting capacity, extended over the last 5 years of the life of the mine.According to A. V. Corlett, former Mine Manager, the property was staked during the early winter months of 1923 because of its location adjacent to the syenite intrusive that had been mapped by Cooke near the height-of-land in this township. An examination by Mr. Corlett in 1924 revealed mineralized zones to the north of MacKay lake, and in the vicinity of these K. W. Fritzsche, by dip needle and trenching, discovered the No. 1 and No. 2 deposits, which were both too small and too low grade for exploitation. During the winter of 1925, A. A. MacKay, with a dip needle, picked up a magnetic 'anomaly' in a drift-covered area about 600 feet to the north of previous workings. Trenching here revealed only a narrow zone of mineralization of little consequence, but, farther east, MacKay discovered a more pronounced 'anomaly' over what later drilling and underground work proved to be ore of commercial grade (No. 3 and No. 4 orebodies)."

Jan 1, 1954

By P. Kordi, L. Egorova, R. J. Bowell, D. Gurevich, V. Sedov, A. Mikhailov, D. A. Holwell

ABSTRACT Reconnaissance exploration in the Kuene region Namibia has included geological mapping, soil and stream sediment geochemistry, and ground geophysical methods. Copper mineralization occurs within a well-defined belt with north-northwest to south-southeast trend, parallel to the regional strike of the sedimentary rocks. The occurrences vary in size but are generally stratabound. The mineralization is centred on the transition from calcareous shale and interbedded limestone, through carbonate rocks, to quartzite. Geochemical anomalies have been identified correlating to induced polarization (IP) and magnetic anomalies. The anomalies identify one potential metallogenic zone more than 17 km in strike length.

Jan 1, 2012

By C. J. Edmonds, R. Bland, W. C. Ferguson, R. Whitehead

"In 1969, the Environmental Science Division of James F. MacLaren Limited received authorization from The International Nickel Company of Canada, Limited to carry out a water quality monitoring program in the Lake Shebandowan region of Ontario, where a new base metal mining and milling complex was expected to go into operation in 1972. The objective of the program is to establish base-line water quality characteristics. Fully realizing their corporate responsibility to minimize the effects of the proposed activities on the environment, Inco decided that it would be desirable to establish a program by which any change in the quality of environmental waters will be detected before detrimental conditions ensue, permitting prompt corrective measures to be taken. The program has been in progress for over two years. The waters are sampled and analyzed four to six times per year. Sampling stations are located in Lake Shebandowan and on the adjacent Gold Creek - Matawin River system. On-site analyses and measurements are made of flow, dissolved oxygen, temperature and pH. Samples also are collected for later analysis in the laboratory. These samples are analyzed for a wide range of chemical and biological characteristics. The paper discusses the extent of the sampling program, the techniques utilized and the value of such programs in maintaining the quality of the environment."

Jan 1, 1973

By C E. Gordon Brown

Aircraft utilization, weather and cost data are given for three separate projects north of the sixtieth parallel in the Northwest Territories and the Yukon Territory. These operations, carried out by helicopter-equipped geological and prospecting parties, have cost $24 to $30 per square mile, depending principally on the distance from the base. They provide adequate surface exploration of areas with 40 to 50 per cent rock outcrop. A good one-inch-to-one-mile geological map can be made. T HE exploration of the Canadian northland has been given increasing attention by the mining industry during recent years. In many cases, the initial problem is to make an adequate reconnaissance of a large area where existing geological information is meagre. The Geological Survey of Canada pioneered the use of helicopter-equipped geological parties for mapping at a scale of eight miles to the inch.

Jan 1, 1964

By P. C. Lightfoot, J. M. Duke, A. J. Naldrett

"The segregation of magmatic sulphides from mafic and ultramafic silicate magmas, in many circumstances, leaves the magma with a lower-than-normal Ni/MgO ratio, which is characteristic of both lavas erupted from the magma chamber and olivine crystallizing within it. Two end members of the segregation process are discussed; i) batch segregation and ii) fractional segregation.In the former, the critical factor is the magma/sulphide ratio. Computer modelling suggests that where this ratio has been less than 1000, the magma will be recognizable as anomalously low in Ni, due to sulphide segregation, and thus a good target for exploration. In fractional segregation, the critical factors are the proportion of sulphide to silicate being segregated and the degree of fractionation.Samples believed to represent the liquid portion of komatiitic lava f lows from a series of unmineralized sequences in the Abitibi greenstone belt, Canada. Belingwe belt, Zimbabwe, and Barberton Mountainland, South Africa coincide with the sulphide-free fractionation model. They are in marked contrast to samples from the ore-bearing districts of Kambalda and Scotia. Western Australia in which distinct Ni depletion, corresponding to fractionation of olivine plus sulphide in a ratio of between 100 and 200:1 is recognizable. Ni-depleted olivines also mark the sulphide-bearing Dumont intrusion of the Abitibi belt.The Moxie intrusion of northern Maine has distinctly Nidepleted olivines, as does the nearby and petrologically related Katahdin body. In both of these intrusions, the composition of the olivine allows reasonable predictions to be made of the Ni tenors of sulphide showings within them. At Katahdin, the Ni depletion is so widespread that little hope is help out for the presence of economic concentrations of sulphide. At Moxie. the olivine compositions suggest that the best chance of economic sulphides lies in the southern lobe of the intrusion.Ni-depleted olivines also characterize certain rock units within intrusions of the Insizwa complex, Transkei, Southern Africa. Many millions of tonnes of Ni have apparently been removed by sulphides from these rock units, many more than are contained within the single mineralized occurrence so far identified at Waterfall Gorge."

Jan 1, 1984

"Energy efficiency in mining and minerals processing has attracted considerable public and industry attention because of the significant quantities of energy consumption involved. In this context the question of what are worthwhile targets for energy efficiency improvements ought to be of the highest priority. It is however worth taking a step back to avoid falling in the trap of taking preconceived ideas that have been reiterated repeatedly before as gospel. The aim of this paper is to highlight areas where new or alternative approaches could potentially be the better way forward. Some may come as a surprise to conventional industry thinking. Ultimately any such solutions are attractive to practitioners not just in an environmental but also in an economic sense, and hence should be targeted through applied research and development efforts. This paper highlights key aspects of each group of opportunities and some of the individual approaches to provide an overview of the current status quo.MINING INDUSTRY POWER UTILISATION – WHERE IS THE BIGGEST BANG FOR THE BUCK?The question of where is the biggest bang for the buck when trying to determine worthwhile targets for energy efficiency improvements has not always been reported on broadly enough, typically because industry practitioners operate in specific areas of expertise and comfort zone. Looking beyond the familiar doesn’t always come easy. Any technology or methodology consideration to address energy efficiency needs to take into account the context of alternative opportunities of superior value or risks not achieving desired uptake. The following sub-chapters have been ordered by magnitude of improvement potential as best as is possible, starting with the biggest first, and the smallest last. Some may be a surprise relative to conventional mining industry thinking."

Jan 1, 2016