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By Bisshop J. P W

Maximum recovery of sulphide minerals by flotation is achieved over a limited size range. Valuable particles above and below this range have a smaller probability of being recovered. In the normal grinding-flotation operation, not all valuables are reduced to the optimum size range, and therefore sub- stantial losses occur. A significant improve- ment in the size distribution is not usually possible within the conventional circuit, and a more complex arrangement may be necessary to obtain optimum recovery of the valuable mineral. This problem is considered with refer- ence to the Mt. LyeZl concentrator. The performance of the existing circuit is dis- cussed, and it is shown that losses in recovery occur in both coarse and fine sizes. Laboratory tests indicate that regrinding the coarse particles results in an increase in recovery of up to 4%. Redistribution of plant grinding capacity to reduce initial grinding power by 6% and use this capacity to regrind coarse particles was considered. It is con- cluded that overall plant efficiency would be increased by 2% provided that overloading of the regrind mill could be avoided.

Jan 1, 1977

The narrow quartz vein deposits at Konongo and Ghana Main Reef gold mines in Ghana were emplaced during the plastic flow cross folding of pre-existing sub-isoclinally folded volcanic and perivolcanic deposits of Proterozoic age. The older fold structures tightened differentially according to their position in relation to the axes of the cross fold pattern giving complex outlines to the reefs in both plan and cross section.Some 4500 measurements of bedding plane linears were used in the resolution of the Boabedroo footwall structure at Konongo. The methodology developed at the Boabedroo mine was then successfully applied to other complex bodies at the Konongo and Ghana Main Reef mines.All mine development, especially stope preparation, of the folded quartz reefs at Konongo and Ghana Main Reef was controlled by the geologist to ensure that the veins were removed with as few geologically enduced hiccoughs as possible.

Jan 1, 1993

Mr. Bradford said: - On assuming this chair, which has been oc- cupied by so many gentlemen of conspicuous ability, my first words must be an expression of the gratitude I feel for the honour you have done me in electing me to be your President for this year. When considering the subject matter of this address to you to- night, quite frankly may it be stated that for a long time I was on the horns of a very great dilemma, for while I could discourse on the modern political trend in relation to our industries at great length, it appeared to me that this was not the place for such a discussion.

Jan 1, 1987

By R Farnf, M Pegden, S Hosein, T White

A number of theoretical papers have been published outlining the use of electronic detonators to limit peak particle vibrations levels, but few empirical studies have been undertaken and even fewer examples have been published of the use of such technology in the aggregates industry. This paper gives a summary of the research work carried out at two limestone quarries in the North of England, where a series of blasts were used to compare and contrast the use of electronic and non-electric detonators. The majority of blasts were carried out using the same burden, spacing and decked charge weight loadings. A methodology was established that could be used to reduce the peak particle velocities (PPVs) at two or more specific locations by using single-hole blast vibration signatures in conjunction with specific electronic detonator timing intervals. The initial study concluded that this was only possible if single-hole signature blasts were periodically recorded to establish the shape of the correct vibration envelopes as properties were approached. These wave envelopes could then be used as the basis for choosing the specific electronic detonator timing intervals to give the lowest PPV for the properties or locations concerned. This methodology was then used in the second study to access a large volume of aggregates adjacent to a working railway tunnel. The financial benefit for the company was to convert these additional tonnages of rock from being a resource to an exploitable reserve. The project involved careful blast design and the instrumentation of a number of boreholes to enable the results of blast monitoring exercises to be compared with predicted PPV results. The iterative process involved the vibration results being uploaded into æBlast LogÆ (an expert blasting database system developed by the Blasting and Environmental Research Group at the University of Leeds) and analysed to produce predictions ready for the next blast.

Jan 1, 2007

By Yoon R-H, Luttrell GH

A theoretical model has been developed to predict the probability of particle collection by air bubbles in a quiescent flotation pulp. The model considers the effects of both hydrodynamic and surface chemistry forces acting during the bubble-particle interaction. Hydrodynamic forces considered include the gravitational, buoyancy, streamline and film thinning resistance forces. The surface chemistry forces considered include the electrostatic, dispersion and hydrophobic forces. The hydrophobic force has been estimated from extended DLVO theory. The model is capable of predicting hydrodynamic and surface chemistry conditions under which bubble-particle adhesion is possible. Validity of the model has been verified experimentally.

Jan 1, 1993

In May 2000, Kanowna Belle Gold Mines (KBGM) carried out a detailed Truck versus Shaft Haulage Study. The study showed that whilst the shaft option had many operating cost benefits the capital costs were too high, therefore the truck option was selected. In May 2001, the concept of achieving æshaft typeÆ benefits without the capital costs was floated. This is achieved by separating the hoisting of ore from other mining activities. The general concept is that material from underground is transported to a central location and then transported to the surface by a special truck fleet, thus removing the dependency between trucks and loaders, providing the mine with surge capacity and decreasing operating costs. At KBGM these advantages have been gained by installing an ore pass system with a plate feeder at its base that directly loads trucks. This provides the mine with a haulage system with enough surge capacity to remove the interdependency between trucks and loaders. The plate feeder is situated just off the decline which creates the opportunity to use larger more reliable, lower cost trucks. A number of truck types were considered for the truck loop including Elphinstone AD55Æs which are the truck type being used on site prior to the truck loop, CAT 775EÆs and power trailer road trains. This paper covers the philosophy behind the truck loop, the truck selection process, project installation and commissioning, people issues and the benefits expected by the operation. As of May 2002, the project is nearing completion, with decline haulage expected to commence in July 2002.

Jan 1, 2002

THE following paragraphs represent an endeavour to describe, briefly the equipment used for the manufacture of sulphuric acid and superphosphates by the Corporation.SULPHURIC ACID PLANTS.Two separate units are in operation, No. I Plant working on sulphur dioxide generated from pyritic ore, No. 2 Plant working on sulphurous gases obtained from the Huntingdon-Heberlein desulphurizing process. The latter plant is unique in being the first installation for the successful use of these gases.

Jan 1, 1918

By Foudoulis C, Smith CB, Drew RM, Sun S-S, Sheraton JW, Hall AE

Primay (syngenetic and protogenetic) inclusions - i.e. minerals formed during or before diamond growth and encapsulated in the diamond - provide important information on the origin of diamond. Recent Rb-Sr and Sm-Nd dating of such inclusions has yielded crystallization ages older than their volcanic host, implying that diamonds are mantle xenocrysts. In this paper we report results of studies on the nature of syngenetic inclusions and the carbon isotopic compositons of the host diamond from the West Australian diamond deposits at Argyle and Elllendale. The Argyle diamonds are dominantly, of eclogitic paragensis and are characterized by strongly C depleted compositions. We have recognized an association of stone morphology, inclusion type and carbon isotopic composition amongst the Argyle stones, and on the

Jan 1, 1989

By Benson R. P

Building a new tunnel to accommodate CN North America's needs or double stacked container traffic for the next 100 years represents new and unprecedented challenges. Innovative approaches to contracting, especially the Negotiated Compressed Process (NCP), TBM design, project management, and the regulatory and approval process, were all required to deliver a new tunnel to meet the needs of CN North America within the approved completion schedule of 33 months compared to a traditional approach of 45 to 48 months. The NCP resulted in trimming a full 12 months from the project schedule with an anticipated saving of direct and indirect costs.

Jan 1, 1993

Carbonation of reinforced concrete is a potential durability issue for vehicular tunnels. This is particularly the case where elevated carbon dioxide concentrations exist and when the design life is 100 years or more. The process of carbonation can result in loss of passive protection to embedded steel reinforcement and initiation of corrosion. Therefore, tunnel design needs to consider the potential for carbonation on internal surfaces and how design life can be achieved in severe environments. This paper examines methods for predicting carbonation and how deterioration can be mitigated through appropriate concrete mix design and construction practices.

Jan 1, 2008

Changes in prices and costs change the mineable grade and the profitabil- ity of an ore reserve. In a static world the grade required for an ore reserve is measured by the ratio: Cost/tonne of ore x 100 Price received/tonne of product and profitability by the ratio:- Price received/tonne of product Cost/tonne of product If the words cost and price refer to average cost and average price over some suitable period, say 3 to 5 years, the above ratios express the convent- ional wisdom of the mining engineer, and assume there will be no change in technology or politics.

Jan 1, 1979

By L Soares, W T. Hennies, F Fujimura

The engineering geological mapping of Metropolitan Area of Jopo Pessoa in the littoral zone of the Parafba State, northeast of Brazil, made possible the ambient characterisation for space using and its implications on the environmental resources. This region comes lately denoting an accented industrial growth and this work would help future projects of urban planning, distinguished by quick ground occupations for residential, industrial installations, farming, beyond mineral extractions. The mineral sector supplies material and substance demanded by industry and civil constructions, like as clay deposits, sands, calcareous rocks and mineral water. Many companies working there do not have the permission or inspection of ambient agencies for planned extractions of mineral resources. The consequences of this activity pass for the low profit of the reserves, bad uses of the sources, ground degradation, vegetation suppressions and physical impacts on landscapes, beyond noises and vibrations. These activities have causing accelerated alterations and transformations in the environment, compromising the sustainable development. It thus becomes clear that urgent solutions must be find to solve the problems with human interferences by closer inspection and management for disciplined use of its natural resources.

Jan 1, 2003

The paper discusses the characteristics of Be-zymianny activity during the last 2500 years. Three periods of increased activity have been identified which are the eruptive cycles lasting for 100-400 yrs. The periods of high activity fall on the fol-lowing time intervals: 2400-1700 yrs ago, 1350-1000 yrs ago and from 1955 ixp to the present time. The 1955-1956 catastrophic eruption after a long period of repose (about 900-1000 yrs) opened a new cycle of activity of the volcano which is continuing to-day. Several decades are distinguished in activity which differ in character and intensity of eruptions.

Jan 1, 1990

Secondary steelmaking (or ladle metallurgy) has been developed as a post- steelmaking ladle treatment to produce steel of superior quality. Its rapid growth has resulted from quality improvements, productivity increase, operational flexibility and process route economics. Advances in secondary steelmaking are very impressive during the past decade, and many commercial systems have been developed for performing one or more of the following unit operations: degassing, atmosphere regulation, reheating, refining with synthetic slag, rinsing gas treatment, injection of solid materials and alloying. The metallurgical requirements imposed by the current competitive steel market include more precise analysis tolerances, minimum level of detrimental elements, improved cleanness, demanding service performance and better processability. In most cases, these requirements could only be realized by the application of appropriate secondary refining facilities. Continuing developments in simplicity of design, cost advantage, quick cycle time, improvements in peripheral services such as refractories, instrumentation and in-situ analysis, extensive exploration of new applications, and the use of computer, can be expected. An exciting future is predicted for the widespread adoption of secondary steelmaking to perform most of the major refining functions over a variety of steel quality. It will also become a vital link in the total steelmaking process for production of tonnage steel at the large integrated steelworks and the mini-steelmills.

Jan 1, 1986

By F Pavloudakis

The installation of on-line analysis systems in the open-pit mines of the Public Power Corporation SA (PPC, the state-owned electricity entity of Greece) is considered to be the key-parameter for performing improved quality control and blending/homogenisation of the produced lignite. In order to investigate the accuracy of these systems under the site-specific conditions of the Greek lignite deposits, a research project was carried out. This was necessary since there is lack of experience in using on-line analysers in mines that produce a fuel of such a poor and largely fluctuating quality. After thorough market research, a dual energy gamma ray transmission on-line ash analyser was installed in Kardia mine of Ptolemais û Amynteon Lignite Centre, which is located in West Macedonia, Greece. The initial results obtained after the realisation of a series of dual-comparison trials (ie using two series of reference values that allow three-way comparisons) pointed out several problems that obstacle the achievement of high accuracy on-line measurements. More specifically, the measurements obtained by the analyser were higher than the concentrations determined by the two laboratories when the ash content was lower than 12 per cent (in wet basis). On the contrary, when the ash content was higher than 12 per cent, the measurements of the on-line analyser were lower than the concentrations determined by the laboratories. In other words, the range of the measurements obtained by the analyser was narrower than that corresponding to the lab analyses results. Therefore, the use of this on-line analysis system under the site-specific operating conditions of Kardia mine does not guarantee improved quality control of the lignite fed to the mine-mouth located power plant. Most probable reasons that explain the above-mentioned problems are the following: The frequent and widely ranging fluctuations of the chemical and mineralogical composition of the lignite transported by the conveyor belt, especially as far as its calcium content is concerned. This result from the nature and the origin of the mineral matter co-excavated with the lignite, which varies from calcareous marls to sands and clays rich in aluminium and silica minerals. The fluctuations of the lignite quantity transported by the conveyor belt. The change of the linear concentration of iron contained in the fabric of different belt parts.

Jan 1, 2003

Installation of spirals as roughers and scavengers in the gravity and regrind recovery circuits has allowed rejection of large weight fractions to tailings, thus contributing to increased mill capacity.

Jan 1, 1978

By Vernon PN

The Eossing Uranium Mine is a high tonnage low grade open pit operation using acid leaching for uranium extraction and ion exchange and solvent extraction for solution purification. Advanced technology, much of it computer based, has led to major economies that have contained operating unit costs over the last four years in the face of double figure inflation. An improved ore reserve block model and mine planning system have achieved a considerable reduction in the stripping ratio. Drilling and blasting costs have decreased some 25%, mainly by the introduction of heavy ANFO explosive. A centralised computer control centre for the metallurgical plant has increased labour productivity resulting in improved process control. The all-staff workforce is united with management in the objectives of creating a safe, healthy, working and living environment and a prosperous company, capable of contributing to the wellbeing of the nation and the shareholders. This situation has been brought into being by an equal opportunity policy coupled with a management system emphasising open two-way communication through all levels in the organisation. The success of this policy is highly apparent in the morale and productivity of the workforce.

Jan 1, 1986

I have been asked to speak today on the topic of Project Finance in the Mining Industry. Through this presentation, I hope to give you a broad outline of the concept of project finance. The first half of the presentation covers the principles involved in project finance and the second half moves to aspects more specific to the mining industry. I have worked for 3 years at Rothschild Australia. Rothschild provide finance for projects in the mining industry, world wide. We finance both large and small projects, with facilities varying from $2m to $100m.

Jan 1, 1990

By Smith J. W, Wilkins R. W T

This paper is a preliminary report of research on the Mount Morgan gold-copper deposit being done at the Division of Mineralogy, CSIRO. Fluid inclusion and sulphur isotope measurements were made on a suite of 11 samples collected by the staff of Geopeko Ltd. This suite contained representatives of the main ore and rock types of the deposit. Homogenization temperatures of fluid inclusions measured on quartz from 8 of the 11 samples, ranged from 172¦C to 276¦C and to this must be added a pressure correction (in this case, up to 50¦C) to obtain the formation temperature of the mineral. Sulphur isotope measurements were made on 34 sulphides from 8 of the 11 samples. The 6S values form a well defined group ranging from -0.5%oto +3.6%owith a mean of +2.4%c. Although the preliminary data do not indicate unequivocally the origin of the deposit they do impose restraints on the wide ranging suggestions that have been put forward. This work is complementary to the paper of Dr G. Gibbons who has described other mineralogical aspects of the Mount Morgan deposit, based on a more extensive suite of Samples.

Jan 1, 1974

Relationships between lead blast furnace performance and the composition and size distribution of sinter were determined from analysis of lead blast furnace operating data. Sintering plant practice was subsequently modified and substantially improved furnace performance resulted.

Jan 1, 1971