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By F. E. Steffens

The application of kriging in assessing the area rainfall in a weather modification experiment is complicated by the presence of many zero rainfall recordings on a given day, and the fact that the variograms seem to be quite different for the rainfall on different days. Indicator variograms are shown to be directly related to two sets of conditional probabilities. Probability kriging is used in estimating the probability of rainfall amounts above any cutoff at any point

Jan 1, 1987

By Sven Petersen, Iain J. Stobbs, Bramley J. Murton, Paul A. J. Lusty

"INTRODUCTIONIt is widely thought that seafloor massive sulphide (SMS) deposits, the modern analogue of volcanogenic massive sulphide (VMS) deposits, present a potential global resource for base (Cu, Zn) and precious metals (Au, Ag). In addition, SMS deposits can be enriched in ‘critical metals’ including Se, Te, Tl [1], which are essential for use in the construction of modern and green technologies. Globally over 340 high temperature hydrothermal sites have been identified at a range of ocean spreading centres [2], significant massive sulphide deposit formation has been recorded at 165 of these sites [3].To date only 13 deep sea sulphide deposits have undergone intrusive investigation (drilling or coring) and of these, only 6 sites have published tonnage estimates [2]. Almost all research and drilling of SMS deposits has been focused on active systems, the investigation of the morphology, subsurface structure and mineralogy of hydrothermally extinct seafloor massive sulphide (eSMS) deposits is almost non-existent.As such, little is known about the mechanisms that operate post-SMS formation and which have an impact on the preservation and hence resource value of SMS. Identifying these generic processes and mechanisms, and the extent to which they impact the resource grade, is critical in evaluating the global potential of SMS."

Jan 1, 2017

By L. E. Djingheuzian

"IntroductionDURING the past two decades an enormous amount of empirical data has been accumulating on grinding. These data have been obtained by mill operators on grinding ores with a diversity of characteristics, and generally they have been published. However, whenever an operator, who has started milling on a new ore, has tried to find a case in literature which would exactly fit his particular grinding problem, he has failed. Evidently, something fundamental has been lacking in all these empirical data, and, as a consequence, each new operator has had to undertake his own experimenting, get the best results he can, maybe publish these results, and let it go at that. This, in the writer's opinion, has been• due to the fact that even the ablest and most inquisitive millman has been forced to look on grinding as an art, and so, except very rarely, has not been able to find the time to stop and think; if he did so, it was rather in a philosophic way, that grinding is a fundamental process, a process that takes place in river beds, on the sea shore, etc.Nevertheless, when all the data so far published are correlated and examined as a whole, one is struck with the advances that have been made in grinding. The writer (7) had made such a study in 1949, and, when the correlation was completed, it showed that there was nothing heterogeneous about the accumulated data and that when brought together they were in harmony with each other. The writer's conclusion was that, if grinding criteria were defined and were expressed in such a way as to make integration of any data into basic formulae possible, grinding would be established as a mathematically exact science, and grinding worries of the harassed mill operator would be at an end!The first attempts to rationalize comminution were made by Rittinger and Kick. However, their theories led to endless disputes which did not accomplish much, except possibly clearing the path for subsequent investigators."

Jan 1, 1952

By Foster Fraas

This Bureau of Mines report describes a method for separating minerals at magnetic susceptibilities within the diamagnetic susceptibility range. The maximum feed rate varies directly with the square root of the lower limit of permissible susceptibility, while the lower limit of permissible susceptibility varies inversely as the square of the magnetic field strength. Minerals may be separated at particle sizes smaller than possible on conventional dry-type magnetic separators.

Jan 1, 1969

Restrictions on the use of zinc will be a thing off the past in a few months. Government allocations on the metal are also expected to go by the board. Concurrently, action is also expected in reference to lead allocations. Government stockpile goals for zinc have been reached. The International Union of Mine, Mill and Smelter Workers lent support to United Steel Worker demands and at the same time put in their own bid for a 25-cent an hour increase at a meeting held in Denver. While backing the USW, the IUMMSW charged the Steel Workers with membership raiding. Iron and steel companies producing about 92 pct of steel ingots in the United States, showed nearly a 13 pct decline in net profit during 1951, compared with the previous year, despite a 22 pct increase in their combined revenue. Federal income tax rose 61 pct, to more than 012 million. New iron ore reserves are being sought in Canada by Jones & Laughlin Steel Core, The company has acquired exploration options near Petersborough on the north shore of Lake Ontario in Durham, Northumberland and Frontenac Counties. *'A fourth property is southwest of Ottawa, in the Kingston, Ontario area..

Jan 1, 1952

By M. Roy, Y. Roux, R. McIvor

"La Compagnie Minière Québec Cartier at Port Cartier. Quebec, utilizes six parallel wet grinding open circuit ball mills to grind iron ore concentrate for the pellet making process. In an attempt to improve grinding efficiency, a mix of 605 25 mm (1 in.) and 405 38 mm (1 ½ in.) grinding balls was charged to mill D while the opposite mix was used in all the other mills. Because media costs were higher for mill D, it was necessary to find out if the smaller balls provided a net economic benefit. Therefore, a test program was undertaken to determine the relative efficiency of the charge in mill D compared to the other grinding mills. Mill F was chosen for comparative efficiency measurements.The first problem was to choose a suitable definition of grinding efficiency. In management's view, previous attempts to quantify milling performance using population balance modelling were ineffective because they were unable to relate breakage rate functions to grinding circuit economical in any meaningful way. Work index analysis was also not favoured because of a number of complicating effects, including the fineness of the feed and product streams and open circuit grinding.It was decided to adopt a recent innovative approach which had been successfully applied to closed-circuit ball milling. For ""functional performance analysis of ball milling"" (McIvor et al., 1990; McIvor et al., 1991), a size criterion is first chosen to define ""fines·' and ~'coarse particles"". In this case 45 microns (325 mesh) was chosen to distinguish fines from coarse material. The relative grinding efficiency of each ball mill environment would then be ~e cumulative grinding (disappearance) rate of coarse (plus 45 nucrons) material per kilowatt hour of energy applied to the coarse material in the mill, divided by the grindability (measured in the laboratory) of the coarse material in the mill feed.Because the disappearance rate of coarse particles is also the production rate of fines, the following equation can be written for the efficiency of the mill environment, Effe, as defined above:"

Jan 1, 1994

ON milling plants, where a large number of slime samples are collected each day, considerable work is involved preparing them for the assayer. The usual practice (as the material usually passes a 150-mesh screen) is to place the sample on a 30-mesh screen an 1 brush it through on to a cloth below. The sample on the cloth is mixed and a portion taken out for the assayer. A simple apparatus that would rapidly disintegrate and prepare these slime samples for the assayer was needed. The manufacturers of assayers' supplies appear to have overlooked apparatus for this class of work. To overcome the tedious preparation of slime samples by the above method, the writer devised the apparatus shown in the accompanying drawing (Fig. 1). It will be seen that the apparatus is a combination of a modified household flour sifter and a riffle sampler.The apparatus is made up in two parts, the top half consisting of a screen box carrying the disintegrator, and the bottom half a, riffle divider, the joints between the two being a slip-in fit. A lid is provided for the screen box. The disintegrator consists of an open drum, to which are soldered three rows of spring steel fingers. Each row has a number of steel fingers which, on rotation, press against the semi-circular screen in the screen box, forcing the slime particles through.To operate the apparatus an 8-in. sample tin is placed under each spout of the divider. The sample of slime, which is about 2 lb. in weight and usually in lumps, is placed in the screen box, the cover replaced, and the drum rotated about half-a-dozen times by means of the handle.The disintegrated sample is divided by the rifle divider into two portions, which are found in the tins under the spouts of the apparatus. One of these samples is taken, mixed on a sheet, and sent to the assayer.

Jan 1, 1922

By Thomas S. Falk, Nils G. Lindberg

The first industrial COBO (Cold Bound) pelletizing plant began operation in May 1975 at Trollhiittan, Swede n. A technical description of the process, together with operational experience with the plant, forms the basis of this paper.

Jan 1, 1976

By V. F. Hollister

Although it is apparent that porphyry copper deposits may have formed in the Andean orogen from Permian time onward, commercial deposits thus far developed appear to have Cenozoic ages only. Following Chilean useage, the porphyry deposits are divided into either: (a) a stockwork, or (b) a tourmaline breccia model. Stockwork type deposits tend to occur on major strike-slip structures which may be either transcurrent or transverse faults related to plate movements, while the tourmaline breccia type may more frequently form independently of regional faults. Stockwork types may be conjugate fractures that intersect and ramify as a network of veins and veinlets, cutting altered rock, and genetically related to a major regional fault, or in other cases they may reflect the intersection of two large fault structures. Circular fracture patterns may more rarely occur in stockwork deposits in response to a specific intrusive. Tourmaline breccia types are characterized by circular and radial fractures genetically connected in some way with tourmaline breccia pipe development or an intrusive piercement that preceded it. Each structural model contains mineralized intrusive8 which have a close time-space relationship to ore and in each model, mineral paragenesis is similar, regardless of age or location in the plate. Also, each model contains the same type of alterntion halos (phyllic, argillic, prophllitic) as are developed in intru- sive centers in porphyry copper deposits found in North America. The potassic zone is exposed best in the older deposits. Examples of each type of deposit are illustrated, demonstrating the feature evolved.

Jan 1, 1973

By S J. Loach

Geological reconciliation is an indispensable part of BHP Billiton’s Western Australian Iron Ore (WAIO) operations. Since 2009 our reconciliations have been calculated in a single, centralised sequel-server database. This system draws data from across our operations and calculates a hierarchical sequence of reconciliation factors that span the company from the smallest grade control (GC) block to the whole of WAIO. It then presents the results using sophisticated graphical reporting tools.The initial motive for developing WAIO’s reconciliation system was to meet corporate compliance and public reporting requirements. The ability to validate our resource and reserve models by comparing their estimates of tonnes and grade with production figures remains the system’s principal function; however, as the system has matured, we have significantly developed its ability to support the improvement of various technical activities within the business. For example, the system can now calculate and report reconciliation factors for different resource classifications, short-term planning models and geometallurgical estimates.More recently, great emphasis has fallen on the system’s ability to detect and warn of possible geological issues that may pose a risk to either production schedules or product quality. We envisage a future where automated analysis of our large historical data set will enable high-risk conditions within future mine plans to be detected and highlighted.In all of these ways geological reconciliation plays an important role in contributing to this company’s financial and operational resilience.CITATION:Loach, S J, 2017. The development and future of BHP Billiton’s Western Australian iron ore geological reconciliation system, in Proceedings Iron Ore 2017, pp 415–422 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By Brooke T. Mossman

Asbestos fibers are highly fibrous silicate fibers that are distinguished by having a large aspect (length to diameter) ratio and are crystallized in an asbestiform habit that causes them to separate into very thin fibers or fibrils. These fibers are distinct from nonasbestiform cleavage fragments and may appear as thick, short fibers which break along cleavage planes without the high strength and flexibility of asbestiform fibers. Since cleavage fragments of respirable dimensions have generally proven nonpathogenic in animal studies, little data exists on assessing well-characterized preparations of cleavage fragments in in vitro models. The available studies show that cleavage fragments are less bioreactive and cytotoxic than asbestiform fibers. © 2007 Elsevier Inc. All rights reserved. Keywords: Asbestiform; Cleavage; Fibers; Fibrous

Jan 1, 2007

This symposium is dedicated to the lifetime achievements of Professor H.Y. Sohn. It covers the scientific fields, processing routes and investigation techniques in which Prof. Sohn has worked during his career and is based in the equally important three topical areas: Principles, Technologies, and Industrial practice. Professor Sohn was General Chair of the very first TMS Fall Extraction and Processing Symposium in 1983 in San Francisco which led to the Annual such symposia as this International symposium. Furthermore, the theme of that symposium was sulfide smelting, which is also included in this symposium. [ ] Professor Sohn was born in a beautiful dynastic capital Kaesung, Korea on August 21, 1941. He received his B.S. degree in 1962 from Seoul National University, M.Sc. in 1966 from the University of New Brunswick, Fredericton, N.B., Canada, and his Ph.D. degree in 1970 from the University of California at Berkeley all in Chemical Engineering. After working as a Research Associate at the State University of New York at Buffalo and as a Research Engineer at Du Pont?s Engineering Technology Laboratory, Dr. Sohn joined the Department of Metallurgical Engineering at the University of Utah in 1974 and currently holds the ranks of Professor of Metallurgical Engineering and Adjunct Professor of Chemical Engineering.

Jan 1, 2006

"Metallurgical process development in greenfield projects must define the comminution flowsheet and establish the equipment sizes that are required to deliver the project design criteria. These are critical steps that heavily influence the financial performance of the project, requiring a detailed understanding of the ore properties of the project resources and the best practice methods to size comminution machines. This paper reviews current practices for determining the ore characteristics relevant to comminution circuit design. Particular attention is given to the design of sampling and testing programs, and the methods commonly applied to size crushers and mills for conventional size reduction applications in mineral processing. IntroductionMetallurgical process development in greenfield projects requires the selection of a comminution flow sheet and must establish the equipment sizes required to deliver the project design criteria. This necessitates a detailed understanding of the ore properties that define the project resource. For brownfield projects the same objectives may apply for plant expansions, or the project objective may be simply to define the capacity and operating cost of an existing facility for a new ore source. The process development phase in either instance will typically comprise the following key activities:• Geometallurgical classification and sampling of the ore deposit or deposits.• Determination of comminution energy requirements.• Benchmarking similar projects.• Identification of flow sheet options.• Equipment selection and sizing.This paper is concerned specifically with process development testing and will as such focus on the first two activities on the list: sampling and testing of the deposit. The discussion will focus on testwork programs to support the design of comminution circuits commonly in use in mineral processing today, specifically crusher, tumbling mill and stirred mill technologies.It is important that any testwork program is designed giving consideration to the types of flow sheets that are viable for the project, and the data that will need to be generated to support the final equipment sizing. Designing a testwork program to only provide information about one particular type of flow sheet will not allow sufficient information to be generated for a rigorous trade-off analysis of options, and may therefore preclude financial optimization of the project. Testing programs should be designed to collect sufficient data to ensure that any backtracking at a later stage to fill in missing information is minimal."

Jan 1, 2016

The scheme of rehabilitation of surface plant commenced in 1936, included the provision of improved and more hygienic changing and bathing facilities for the employees.At that time the Thompson's Shaft section of the British Mine was being prepared for a resumption of operations, and it was decided to repair and re-equip the existing building. Thus any new scheme adopted could be given a thorough trial, and the proved arrangement used as a basis for the contemplated new main changehouse on the North Section.Investigations were carried out to determine the most suitable arrangement for the Thompson's Shaft changehouse, to provide for a total of 120 men, with particular regard to the internal fittings and fixtures. Also, as the mining conditions were such that a large proportion of clothes worn underground by miners, etc., were wet by the end of the shift, the problem of drying these clothes in the availaole time from a man coming off shift to his commencing again some sixteen hours later was one of the most important to be dealt with.The changehouses in use on the North mine section of the lease were provided with racks around the walls for the men to hang their street clothes on, and a section was partitioned off to house the mine clothes and their drying facilities. The actual drying was carried out by means of hanging the wet clothes over racks between which ran pipe coils heated by means of hot water circulated from the hot water boiler supplying the showers.This method had proved to be far from satisfactory for several reasons, the main objections being:-

Jan 1, 1940

By G. Van Weert

Separation of minerals by shape has received little attention, since minerals normally do not break into different shapes during crushing and grinding. However, comminution of consumer wastes generates opportunities for novel separations based on particle shape. For instance, ductile plastics are broken into longer curved shapes, whereas brittle plastics yield angular particles. Using spouting beds for particle separation in water requires controlling the spout's instability. The preferred geometry for such redesigned spouting beds is reported. Plastic cylinders, discs and spheres were separated as a function of rising water velocity and amount of particles in the system. By using 5 mm particles, differences in settling behavior could be video recorded.

Jan 1, 1999

Jan 1, 1946

By Carl Keuffel

THE manufacture of optical glass is a new industry in this country. In 1914, after the war started, the supply of optical glass from Europe was cut off, but as there was a fairly large stock of glass on hand, it was not until the end of 1915 that the optical instrument makers made serious efforts to produce their own glass. These early attempts were generally made by practical glass men and, due primarily to the fact that very little scientific help was used, the first attempts were unsuccessful. It was not until the whole problem was attacked by technically trained men who used advanced methods of research that good results were obtained. These researches proved that the accurate control of the temperature was a most important factor in the manufacture of optical glass. The early glass maker judged temperatures with his eyes; later, Seger cones were introduced into the furnace at various stages of the melt. Then radiation, indicating and recording pyrometers with rare-metal thermocouples were introduced. Now, in addition to these, an optical pyrometer every hour or so is sighted right into the pot and on the molten glass. Figs. 1 and 2 show how pyrometers are used to control the melt. InFig. 2, Y is the clay pot in which the batch is melted to glass within the furnace X. The rare-metal thermocouple S, protected by a clay tube, extends through the wall and about 4 in. into the furnace. This couple is connected to an indicator T and a recorder U so that a complete record of the furnace temperatures is obtained. The section of the curve ABCD, Fig. 1, shows how gradually and carefully the clay pot must be heated to get rid of moisture AB and during the calcining at CD. The stem of an expansion pyrometer R is extended through a hole in the door Z of the furnace and into the pot in order to more closely follow the temperatures of the clay pot itself during the burning process, that is from A to D. After the pot is calcined, the temperature can be rapidly raised to E (about 1430° C.); from E to F this temperature is much higher

Jan 9, 1919

By M. Timucin

High-temperature phase relations in the Pb-PbS system were established by the quenching of samples equilibrated in evacuated and sealed silica capsules. The liquid-miscibility gap seen in some previously published phase diagrams was not observed. The thermodynamic activities of PbS in liquid solutions of this system were derived at 1473 K from the isopiestic equilibration of samples belonging to this solution series with Cu2S-PbS melts of known PbS activities. The behaviour of Pb-PbS melts was found to be compatible with a subregular solution model. This model also made it possible to obtain an analytical liquidus for PbS that was in excelent agreement with the experimental determination.

Jan 1, 1988

By Magnus Ruin

The dry deep mixing method for stabilization of soft soil has been used in the Scandinavian countries for 25 years. The typical application has been stabilization of soft inorganic clay. Today the method is used more frequently in organic soil with good results. The Limix System, introduced in the USA by Hercules Grundläggning AB and TREVIICOS Corporation, is a cost-effective dry deep mixing method used to stabilize most types of soft soil. This paper presents the general principles of stabilizing organic soil with the dry mix method and two case histories of soil stabilization projects in organic soil. Between October 2000 and June 2001 the Limix System was used in England to stabilize soft organic alluvium at the Channel Tunnel Rail Link, Contract 440. During year 2000 the Limix System was used in soft organic soil in Holland near the Groene Hart Tunnel entrance to support trench excavations for slurry walls and concrete barrettes.

Jan 1, 2001

By D Brooks, S Gunn, T Perkins, J Siliezar

Ernest Henry Mining (EHM) is a copper, gold and magnetite mining and processing operation located 38km north east of Cloncurry. The EHM ore body has an average grade of 0.9% copper (chalcopyrite), 0.5g/t gold and 22% magnetite.Open pit mining commenced in March 1998, but EHM transitioned to underground mining in December 2012, extending the life of operations beyond 2024. The underground mine currently produces up to 3Mt/year of ore, hauled up a decline by truck. This figure shall double in 2014 with the completion of a 1000m shaft. The EHM Concentrator has a nameplate capacity of 10Mt/year. In June 2011, Xstrata Copper acquired the Mount Margaret resource to supplement underground production and utilise the full capacity of the Concentrator. The Mount Margaret Mining (MMM) operation was established to develop the five deposits making up the resource by way of open pit mining.Copper concentrate is produced by the EHM Concentrator via grinding, flotation and dewatering circuits. The grinding circuit comprises a SAG and ball mill in a closed AB configuration. Flotation consists of a rougher train, regrind and three stages of cleaning, with the tail from the first stage reporting to the tailings thickener.The mineralogy of the MMM ores is complex, comprising fine textures of active pyrite, copper oxides, native copper, clay and secondary copper sulphides. This paper provides an overview of the metallurgical test work completed to forecast the performance of the MMM ores through the EHM Concentrator and identify flow sheet modifications for maximising copper recovery and producing a saleable concentrate. A discussion of the challenges experienced in the plant to date follows.CITATION:Gunn, S, Siliezar, J, Brooks, D and Perkins, T, 2013. Adapting the Ernest Henry Mining concentrator to process the Mount Margaret ores, in Proceedings MetPlant 2013 , pp 347-370 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 15, 2013