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By P Shen, K Hattori, H Pan, E Seitmuratova

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. Ore-bearing intrusions in the Central Asian Orogenic Belt (CAOB) were examined from nine mines: Boshekul, Nurkazgan, Kounrad, Borly, Aktogai, Koksai, Baogutu, Tuwu and Erdenet. The intrusions are diorite, granodiorite and tonalite with SiO2 contents ranging from 58 to 75 wt per cent, and show mildly fractionated rare earth elements (REE) ([LREE]N/[HREE]N = 2.7–4.7) – light REE and heavy REE – and varying Eu anomalies ([Eu]/[Eu]* = 0.58–1.4). The ratios of Sr/Y vary from 7.9 to 115 and the contents of Y from 4.6 to 23.9 ppm. The parental magmas of the intrusions are intrinsically oxidised. Zircon grains in the ore-bearing rocks from large- and intermediate-sized porphyry Cu deposits show high Ce4+/Ce3+ ratios characterised by 65–422 at Boshekul (>4.1 Mt Cu), 76–480 at Kounrad (>4.8 Mt Cu), 90–280 at Aktogai (>12 Mt Cu), 80–250 at Erdenet (>11 Mt Cu) 74–370 at Nurkazgan (>3.9 Mt Cu), 100–210 at Koksai (>1.6 Mt Cu), and 71–340 at Tuwu (~2.0 Mt Cu). In two small deposits, the ore-bearing rocks display low values of Ce4+/Ce3+; Borly (0.6 Mt Cu) ranging from 28 to 158, and Baogutu (0.6 Mt Cu) from 29 to 113. The Ce4+/Ce3+ ratio of 120 distinguishes large intermediate-size deposits from small-size deposits. This information is potentially useful in exploration for porphyry Cu deposits in the belt.CITATION:Shen, P, Hattori, K, Pan, H, Jackson, S and Seitmuratova, E, 2015. Granitoids associated with porphyry Cu deposits in the Central Asian Orogenic Belt – characteristics and oxygen fugacity, in Proceedings PACRIM 2015 Congress, pp 377–382 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By Indresan Govender

A continuum based granular flow model of charge motion that combines the inherent frictional nature of particles with its distinctly fluid-like structure is presented. Starting with Newton?s 2nd Law on a volume element of charge, we derive the velocity field in the bed free-surface and the rising en-masse region. Invoking flux conservation within the two regimes of interest then yields a (simple) differential equation for the free-surface of the charge body. Combining the velocity field gradients with a suitable constitutive choice for the shear stress completes the picture with a description of the in-situ rate of shear power dissipation in a tumbling mill ? a mechanistically correct account of power draw in a tumbling mill. Positron Emission Particle Tracking (PEPT) was used to measure the in-situ flow fields of the charge within opaque systems like tumbling mills. The accurate velocity and mass distribution derived from PEPT form the basis for direct verification of the resulting granular flow models. In this regard a wide range of milling conditions is investigated and presented in this paper.

Sep 1, 2012

By G. Ranjan

The designers and the practicing engineers have started using latest and cost effective techniques of ground improvements which utilise the weak and poor sub-soil deposits efficiently for the civil engineering construction. In the present investigation, a new concept of 'skirted granular piles' has been advocated. An effective method of construction of granular piles as an economical alternative to vibroflot, and the skirt has been developed. The construction technique is based on indigeneous know how which effectively utilises the man-power technology avoiding import of costly equipment suiting to the developing countries. Full scale insitu tests have been carried out at four sites, having different soil conditions, on virgin weak sub-soil, and improved ground by casting plain and skirted granular piles. Effectiveness of different types of skirt has been demonstrated through insitu tests. A simple analytical approach has been proposed to predict the ultimate pile capacity. The predicted values of ultimate capacity have been found to demonstrate a good correspondance. Granular pile behaviour in terms of pile depth, diameter, spacing and stress deformation characteristics of the improved ground have been discussed. A significant improvement in ultimate capacity in improved ground has been noted. This is further augmented when granular pile group is skirted.

Jan 1, 2010

By J Pan, B-J Shi, X-B Li

The granulation behavior of specularite fines which possess poor ballability was studied with limonite fines as a function of nuclei particles and adhering fines. The results show that the permeability of granules deteriorated as the ratio of specularite fines increased in the mixture, and the optimal granulation moisture content also decreased. The granulation kinetics results demonstrate that the adhering load of specularite fines increases rapidly within three minutes and then levels off. With increasing specularite fines ratio, the adhering speed is accelerated but the granulation duration needs to be longer to reach adhering balance. The microstructure of granule quasi-particles indicates that the fine limonite particles act as binders to bond together the specularite particles which are dispersed in the adhering layers. This can improve the adhering strength of the granules. Hence, the granulation behaviour of specularite fines can be improved by blending them with fine limonite ores which have high adhering capabilities.CITATION:Zhu, D-Q, Li, X-B, Pan, J and Shi, B-J, 2015. Granulation behaviour of specularite fines in ferrous sinter mixtures, in Proceedings Iron Ore 2015, pp 91–96 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By Fernando Hernández Polanco

Transportation and handling metals and alloys from mills to consumption factories as well as dosing in conventional processes with ingots and scrap has always been considered a complicated activity with high operating costs. Several manufacturers of ferroalloys willing to solve these problems have chosen an alternative for their products that can be used to secure, during transport and dosage in the processes to making special steels, with more efficient consumption of ferroalloys. The trend for the production and sale of ferroalloys is to provide the product in the form of granules packed in bags or in bulk. In this paper we will show you how the granulation process was developed and rapidly adopted the ferroalloys industry as an effective solution to reduce operating costs, create cleaner and safer working environments.

Oct 30, 2017

By David Norval

Water solidification of mattes, metals, alloys and certain slags with high metal entrainment has customarily not been practiced due to the belief that such processes are too dangerous and unproven in the Pyrometallurgical Industry. Slag granulation on the other hand is extensively applied, although in some cases crudely, with disastrous effects, as a result of not recognising the high heat capacities prevalent in slags. This paper will examine the most common air solidification processes and compare such processes with water solidification, mainly slag and matte granulation processes and design criteria for safe and reliable operation. Finally, purpose designed granulation and solidification processes will be discussed taking into account specific applications and the individual signatures of alloys and slags, emphasising that no slag, matte or alloy responds in similar fashion to a granulation practice.

Jan 1, 2006

A molten metal granulator was designed and fabricated at the U.S. Dept. of Energy, Albany Research Center, for granulation of precious metal-bearing alloys and slags. The system was designed to safely granulate a metal alloy at a temperature of up to 1,600°C at a rate of roughly 50 kg of alloy per minute. The primary water jet was supplied by a 18.6-kW, 600 liter per minute pump which provided approximately 600 kg of water per minute through the primary jet. Two 3.7-kW, 150 liter per minute auxiliary pumps provided additional wash water to wet the granulation trough through 4 secondary jets, which were placed at either side of the primary jet. The water supply was closed-loop, including a 37,850-liter supply tank and 22,710-liter recovery tank. Magnetic separators and particulate filters were included for collection of the finest fraction of the granulation product, which cleaned the water sufficiently for continuous recycle.

Jan 1, 2006

By Horst Kappes

Tradicionalmente, a escória é descartada em poços secos ou granulada com água, gerando um produto de maior valor agregado devido à vitrificação e consequente aproveitamento na indústria de cimento. Com larga experiência em granulação e mais de 260 referências do sistema INBA®, a Paul Wurth agora apresenta a solução mais robusta do mercado para granulação a seco. Promovendo a granulação através da injeção de esferas de aço, comprovou-se, através de uma série de testes, características iguais ou superiores à da escória granulada com água. Uma apresentação desta tecnologia bem como uma narrativa de sua trajetória e os resultados parciais obtidos é descrito neste trabalho.

Aug 2, 2018

By Manuel Enrique Rodriguez Blanc

A planta industrial de produção de ferroníquel da Anglo American Barro Alto, localizada no Estado de Goiás, recebeu notificação de clientes como Aperam (Bélgica) e Acerinox (Espanha), em relação ao formato esférico apresentado pelo ferroníquel produzido. Para solucionar o problema, foi realizado teste na planta piloto da empresa de engenharia UHT para desenvolvimento de novos projetos e de nova tecnologia com objetivo de aperfeiçoar o formato do produto final. A utilização de disco de 4 canais solucionou o problema do formato esférico, no entanto, forma-se muito “bodes” ocasionando explosões. O sistema de granulação utilizando um tundish rotativo, mantem as mesmas características físicas do metal granulado com disco de 4 canais além de aumentar a segurança da operação, reduzindo os riscos de segurança do trabalho.

Oct 30, 2017

By S. P. Nagaeva, A. V. Kuptcova, O. Yu. Poperechnikova

"The present paper contains study results of gold morphology and grain size distribution in flotation concentrates produced from original ore samples from deposits of different genesis. Pre-concentration methods were used with selective dissolution of rock minerals and mineral heavy medium separation to obtain statistically valid data on gold grain size and morphology in concentration products. Special attention is given to study of flash flotation concentrates that is mainly used for coarse gold, underextracted in gravity circuit. Analysis of geometrical optics has allowed to establish that during flash flotation gold grains more than 150 µm can be extracted from 10 to 35%, and in some cases single gold grains above 300 µm. INTRODUCTION Distinctive features of gold that have a significant impact, and in some cases, decisive influence on its recovery into saleable products are mineral shape, grain size and morphology of metal particles, paragenetic associations of gold. Peculiar feature of coarse gold is its easy extraction during grinding from associated mineral components like quartz, sulphide and other and almost complete recovery into gravity concentrates (Lodeischikov V.V., 1997). Morphology of native gold is so diverse that different gold grains are better extracted using different methods of concentration. Compacted and rounded particles are easily processed using gravity concentration but low cyanidable and hard to process using flotation. On the contrary, lamellar, flake, dendrite and capillary aggregates of high specific surface are easily cyanidable and under definite conditions it has strong floatability (Lodeischikov V.V., 1997). Flotation of gold-containing sulphide minerals and free gold takes place simultaneously during flotation concentration. In case of low-sulphide ores, native gold takes the basic load, having the high density (15.6 to 18.3 g/cm3, for pure gold – 19.3 g/cm3) it has limited size and morphology for successful flotation. It is known that flake gold and fine-grained gold up to 0.1 mm are easily extracted (Lodeischikov V.V., 1997). Authors of the present paper performed a study of gold granulometry and morphology in flotation concentrates produced from gold-containing ores from two deposits of different types: gold-copper oxidized hematite ores and low-sulphide gold-quartz ores. Ores are different by both host rock composition, mineralogical and petrographic features, gold grade in mineral assemblage and morphology and size of precious metal. Common for both ore types is low-sulphide content and presence of free gold."

Jan 1, 2018

By S. Kauchali

"Underground coal gasification (UCG) is recognized as an efficient mining technique capable of chemically converting the coal from deep coal seams into synthesis gas. Depending on the main constituents of the synthesis gas, chemicals, electricity, or heat can be produced at the surface. This paper provides a high-level graphical method to assist practitioners in developing preliminary gasification processes and experimental programmes prior to detailed designs or field trials. The graphical method identifies theoretical limits of operation for sensible gasification within a thermally balanced region, based primarily on the basic coal chemistry. The analyses of the theoretical outputs are compared to actual field trials from sites in the USA and Australia, with very favourable results. A South African coal is studied to determine the possible synthesis gas outputs achievable using various UCG techniques: controlled retractable injection point (CRIP) and linked vertical wells (LVW). For CRIP techniques, an important result suggests that pyrolysis, and subsequent char production, are important intermediate phenomena allowing for increased thermal efficiencies of UCG. The conclusion is that South African coals need to be studied for pyrolysis-char behaviour as part of any future UCG programme. The results also suggest that UCG with CRIP would be a preferred technology choice for Bosjesspruit coal where pyrolysis dynamics are important. Lastly, the use of CO2 as oxidant in the gasification process is shown to produce syngas with significant higher heating value. Introduction and literature surveyCoal is a commonly utilized fossil fuel, providing over 40% of global electricity demand and about 90% of South Africa’s primary energy needs. However, less than 20% of the known world resources are suitable for possible extraction using conventional surface and underground mining techniques (Andrianopolous,, Korre, and Durucan, 2015). Underground coal gasification (UCG) has the potential to recover the energy stored in coal in an environmentally responsible manner by exploiting seams that are deemed unmineable by traditional methods. The UCG process, if successfully developed, can increase coal reserves substantially. For example, in the Limpopo region of South Africa alone, the estimated potential for UCG gas, based on existing geological records, is over 400 trillion cubic feet (TCF) natural gas equivalent – this is about a hundred times more gas than the existing 4-TCF Pande-Temane natural gas field reserve in Mozambique (de Pontes, Mocumbi, and Sangweni, 2014)."

Oct 1, 2018

By B. M. Davis

Frequently ore reserve studies utilize samples from a series of drilling or other types of sampling campaigns. Sometimes there is a mix of sample types, say for instance, channel samples from underground workings and drill core from surface drilling. Since drilling, sampling, logging, and sample preparation protocols tend to change over time, there is always a question whether the samples give similar results that vary only by chance alone. The problem of comparing the various campaigns is complicated by the presence of spatial relationships among the samples. Geostatistical tests take the spatial correlation into account, but these tests may be complicated and cumbersome to implement. A comparison method based on familiar statistical graphics is presented which accounts for the spatial relationships. It allows comparisons to be made quickly by using simple statistical graphs such as scatterplots and boxplots.

Jan 1, 1996

By William Marsh Baldwin

[Two of the most useful and important equations available to the metallurgist for the study of plastic deformation of metals are the Huber-von Mises-Hencky1-3 and the St. Venant7-10 equations. HUBER-VON MISES-HENCKY EQUATION The Huber-von Mises-Hencky equation answers the question: When does plastic flow occur in metal that is subjected to a multi-axial stress? It occurs, according to this equation, when the three principal stresses,? al, a2, and a3 satisfy the equation: (s1 - s2)2 + (s 2 - s 3)2 + (s 1 ? s3)2 = 2K2 [I] Here K is the yield strength of the material as determined in an ordinary tensile test. If the quantities a1, a2, and a3 are assigned to the coordinates of a Cartesian three-dimensional system, this expression describes a cylinder whose axis of symmetry is inclined at equal angles to the three coordinate axes4,5 (Fig. I). The radius of this cylinder is v2/3K. For the purpose of simplicity, it is sometimes advantageous to ascribe the values s 1/K = si, s 2/K = s2, s 2/K = s3 to the three coordinate axes instead of the principal stress alone. In this case, Eq. I becomes (s1 - S2)2 + (S2 - S3)2 + (Sl - S3)2 = 2 [2] and the radius of the cylinder becomes 2/3v. In the latter method of representation, a point lying inside the cylinder indicates that the metal will react elastically, whereas a point lying on the cylindrical surface indicates that the metal will behave plastically. Some of the geometric features of this cylinder are worthy of study. Let us inquire first as to what interpretation may be placed upon what we will choose to call the "circles of latitude" of the cylinder (L in Fig. I) and the "meridians" of the cylinder (M in Fig. I). Circles of Latitude Circles of latitude are formed by allowing a plane, passing perpendicular to the cylinder axis, to intersect with the cylinder. Any point, P, on this circle is presumed to have the coordinates s1, s2, and s3. The coordinates of the point resulting from the intersection of the plane and the cylinder axis will be a, a, and a (since the cylinder axis is equally inclined to the three coordi¬nate axes). Let us now pass a line through the point on the circle and the point on the axis.]

Jan 1, 1946

By C. C. Harris

The two best known graphical methods for presenting and comparing comminution data are obtained by linearising the Gates-Gaudin-Schuhmann and the Rosin-Rammler size distribution equations. It is shown that the Gates-Gaudin-Schuhmann equation can cause excessive congestion in the 50 per cent oversize range and that, overall, the Rosin-Rammler is a better procedure. Examples are given

Dec 1, 1971

By R. J. Woody

DESIGN of the most economic continuous counter-current decantation (CCD) circuit is based on selection of the number of stages and the wash volume that will give the minimum summation of the following items: 1) Capital and operating costs of the CCD circuit. 2) Capital and operating costs of the precipitation circuit. 3) Value of the dissolved product lost.

Jan 7, 1958

By Nicolae Dobritoiu

The literature in this field and the practical activity record that a method, respectively the technology used for an underground mining work have many components which, in order to be applied, demand that for each of the parameters that describe the environment of the mining work and that influence the chosing of that method and that technology of execution, must have values in an interval well determined. There are situations when one or many parameters of the set of parameters that describe the environment of the mining work, can modify its values, and, as a result, one or more components of the methods or technology cannot be applied anymore, making necessary a replacement of their values. The information offered by this graphical-analytical model allow the determination of optimum solutions for the process of digging of the underground mining work and thus it will result the incresing of the technical-economical efficiency of the digging process and, also the increasing of the quality of the underground mining work.

Oct 1, 2009

By Eugene N. Cameron

Graphite is the hexagonal form of crystal-line carbon. It is found in nature locally as tabular crystals but occurs mostly as disseminated flakes, foliated, platy, or fibrous masses, or microcrystalline compact to earthy material. Graphite is characterized by its gray to black color, metallic luster, black streak, perfect basal cleavage, softness (H = 1-2) and unctuous feel. It is sectile and flexible and has a specific gravity of 2.1 to 2.3. It is an excellent conductor of heat and electricity and is inert to ordinary chemical reagents. It melts at a temperature of about 3500°C and vaporizes at a temperature of about 4500°C. In the presence of oxygen it oxidizes to CO2 in the temperature range 600° to 700°C, but it is stable at ordinary temperature and markedly resistant to chemical weathering. Although some natural graphite is nearly 100 pct pure carbon, most contains mechanical impurities of various kinds; quartz, biotite, muscovite, pyrite, iron oxides, and feldspars are the most common. Commercial graphite products have a wide range of graphite content, but the better grades contain 80 pct graphite or more. Both natural and manufactured (artificial) graphite are used in industry. Natural graphite products are divided into two broad categories based on grain size. Graphite composed of visible crystals is called "crystalline" graphite, whereas graphite so fine-grained that it is not visibly crystalline is termed "amorphous." The distinction is arbitrary, for all natural graphite is crystalline, and all gradations between the two commercial categories are known. Within the two categories the terminology used in industry is confusing and not entirely consistent. Crystalline graphite comes from two principal types of sources. The first consists of rocks containing disseminated flakes of graphite. This source yields the "flake graphite" of industry. The second comprises vein deposits of graphite, of which those in Ceylon are the most important and furnish the Ceylon graphite of industry. Amorphous graphite comes from any of a variety of sources, including some of those that yield crystalline graphite. Manufactured graphite is made by electric furnace processes, mostly from petroleum coke. Occurrence and Distribution of Graphite Deposits GENERAL Graphite is widely distributed in nature, occurring in igneous, sedimentary, and metamorphic rocks, and even in nickel-iron meteorites. Graphite deposits of economic interest, however, occur mostly in metamorphic terranes. Five principal geologic types of deposits are recognized: 1. Deposits consisting of flake graphite disseminated in metamorphosed siliceous sediments. 2. Deposits consisting of flake graphite disseminated in marbles. 3. Deposits formed by thermal or dynamothermal metamorphism of coal or other highly carbonaceous sediments. 4. Vein deposits of the Ceylon type. 5. Contact metasomatic or hydrothermal deposits in marble. DEPOSITS IN METAMORPHOSED SILICEOUS SEDIMENTS Deposits consisting of flake graphite disseminated in metamorphosed siliceous sedi-

Jan 1, 1960

By George D. Graffin.

The first use of graphite is lost in the mists of time. It was used by primitive man to make drawings on the walls of caves and by the Egyptians to decorate pottery. As early as 1400 A.D. graphite crucibles were being made in the Haffnerzell district of Bavaria. Through the Middle Ages graphite was confused with other minerals, especially galena and molybdenite. Two common names that are still used for the mineral are "Plumbago," meaning leadlike, and "Black Lead." The latter name implied that graphite is either composed of lead or at least contains a large percentage of it. Gessner is credited with having recognized it as a separate mineral in 1565, but its composition was not determined until 1779, when Scheele demonstrated that graphite oxidized to carbon dioxide, thus proving its carbon constitution. In 1789, Werner named it "graphite" from the Greek word "graphein," meaning to write. The United States has long relied on foreign countries for its graphite supplies. This reliance has been due more to the lack of suitable domestic graphites than to any particular preference for buying minerals overseas. Ceylon (now Sri Lanka) graphites were imported as early as 1820, and Madagascar graphites have been imported since the properties on that island were opened up about a hundred years later. Mexico has long supplied the United States with most of its requirements for amorphous graphite. Physical Properties and Classification Graphite is found in laminated, flaky aggregates disseminated in schistose rocks. It also occurs in veins and exhibits a foliated or fibrous structure. Graphite is a black lustrous mineral that crystallizes in the hexagonal system, with rhombohedral symmetry. The crystals have tabular form and are six-sided; the faces are commonly striated. The flakes have perfect basal cleavage and are opaque. When well crystallized, the flakes have a black metallic luster while the amorphous material is black and earthy, with a microcrystalline compactness. The flakes feel greasy. Graphite is an excellent conductor of heat and electricity. It melts at approximately 3550°C at a triple point under 1250 psi. It sublimes between 3300-3500°C at 14.7 psi. At 3726°C a second triple point occurs at approximately 100,000 atmospheres. Thermal oxidation in the presence of oxygen begins at 300°C and the rate increases with temperature. The three forms of carbon (charcoal, graphite, and diamond) are distinguished by chemical and physical tests. The specific gravity of charcoal is 1.3 to 1.9, of graphite 2.266 g/ cm3 (crystal density), and of diamond 3.5. Graphite has a hardness of 1 to 2 (Mohs' scale). Natural graphite can be divided into three classes: disseminated flake, crystalline vein (fibrous or columnar), and amorphous. Flake graphite is a lamellar form found in metamorphic rocks, such as marble, gneiss, and schist. Each flake is separate, having crystallized as such in the rock. Crystalline vein graphite is found in the form of well defined veins or as pocket accumulations along the intrusive contacts of pegmatites with limestones. The graphite of such deposits is of two types, foliated and columnar. The important Sri Lanka (Ceylon) deposits are vein type. Amorphous graphite is commonly found as minute microcrystalline particles more or less uniformly distributed in feebly metamorphic rocks, such as slates and shales, or in beds consisting practically entirely of graphite. The latter usually are metamorphosed coal seams and carry as much as 80-85% graphitic carbon, while the former, being altered carbonaceous sediments, commonly range from 25 to 60%

Jan 1, 1983

By J. F. Peterman, M. C. Roberts

The success of any industrial mineral project requires an accurate forecast of the demand fir the material as well as accurate projections of costs and prices. This paper develops a general method of predicting mineral requirements and applies it to the case of graphite. The basic method is to explain graphite consumption in each of its major uses by the output and manufacturing technology of the using industry. Once these underlying factors are determined, they can he projected to establish future requirements. This forecast is critical to the evaluation of a new source of supply, such as the graphite resources of Upper Michigan.

Jan 1, 1990

By A. B. Kinzel

ALTHOUGH the iron-carbon diagram has undergone many changes in the last 20 years, the region below the eutectoid line and up to approxi-mately 1.7 per cent carbon has been little affected. This region is generally considered to consist of cementite and ferrite. Graphite has been noted occasionally in the hypereutectoid steel region, and the ready formation of graphite nodules in malleable cast iron is a phenomenon difficult to interpret in the light of cementite, supposedly stable at sub-eutectoid temperatures. In this case the graphite formation has been partly explained by the presence of silicon, and many have believed that silicon acts to change the stable state rather than to accelerate reactions so as to arrive at the stable state in a briefer period of time. Consider-ation of this phenomenon indicates that cementite is not the stable phase in the temperature composition zone referred to. In the course of examining a low-carbon steel tube taken from a petroleum cracking still, which had been in service for approximately three years at temperatures somewhat below the eutectoid temperature, observations were made that shed light on this entire subject. The tube in question analyzed:1 C, 0.15 per cent; Mn, 0.49; Si, 0.02; S, 0.023; P, 0.015. The microstructure of the tube after service is shown in Figs. 1 and 2. From these it is evident that cementite as such is absent, and that in its place nodular graphite has been formed. In order to check this observation further, samples taken from the tube were heated at 850° C. for varying periods of time. The small samples were put into a large hot furnace, and the total time is recorded. The structure of the

Jan 1, 1934