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By A P. Wibowo

Indonesia holds a significant role in the utilisation of coal resources in the world. Although the number of Indonesian coal resources and reserves do not fall into the world’s top ten, according to 2009 statistics, Indonesia is the seventh largest producer of coal with a production of 256 Mt. More than 80 per cent of this amount is sold in the export market, making Indonesia the world’s second largest coal exporter. Most of the exported coal from Indonesia is used to fulfil the needs of the Pacific market, such as Japan, Taiwan, China, among others. It is also possible to reach the Atlantic market.Along with Indonesia’s development program, until 2025 the Indonesian government has adopted a National Energy Policy that aims to reduce the role of petroleum in electricity generation and replacing it with coal. As a follow-up of the policy, since 2009 PT PLN, the state electricity company has built steam power plants throughout Indonesia as an implementation of the first stage of the Electrical Acceleration Project with a capacity of 10 000 MW. Moving forward, in 2011 PT PLN will also build the second stage of the project with a capacity of 10 000 MW. As a result of the program, the domestic need for coal is expected to increase as much as 44.8 Mt.With the increase in domestic need and decrease in the number of reserves, the Indonesian government has adopted policies to secure the domestic coal supply. A policy that may potentially be adopted by the government is the limiting of coal production, seeing the high rate of increase in Indonesian coal production. The adoption of such a policy will change the distribution map of coal in the Pacific market. Thus, this paper will evaluate the change of coal distribution patterns in the Pacific market along with the increase in Indonesian domestic needs and Indonesian adoption of policies regarding the securing of coal supplies.

Nov 22, 2011

The Significance of Internal Recycle in Froth Flotation

Sep 13, 2010

By N. M. Langdon

In considering the magnificent success of Mr. Gayley's bold experiment of applying dry blast to the blast-furnace, whereby a saving of 20 per cent. of fuel per ton of iron is effected, the question arises whether still further economy in fuel is possible, and, if so, how it is to be attained. The manner in which the heat generated in the furnace is utilized in the production of pig-iron may be determined, by the method of Bell and Gruner, for any furnace for which the necessary data are obtainable ; and the study of the operation, under various conditions, of a number of furnaces, for which such information has been worked out, should enable us to form some conclusion on the subject. The tables and calculations here given cover the operations of several furnaces reported in our Transactions ; also the two furnaces using natural and dry blast ill Mr. Gayley's experiment, for which the heat-equation has been worked out by Prof. Joseph W. Richards in his admirable discussion ' of Mr. Gayley's paper, The Application of Dry Air Blast to the Manufacture of Iron, and, finally, various hypothetical furnaces. The full list is as follows : A. Isabella furnace, with natural blast. B. Isabella furnace, with dry blast. The data stated for A and B in Table 111. are those given by Professor Richards, except that the heat-units are given for one unit of iron instead of 100 units, and some items of heat supplied, as stated by Richards, have been subdivided, the total being the same as given by Richards. (Columns A and B are introduced in Table 111. for comparison with C and D.)

Jan 1, 1910

The interaction of flotation collectors with sulfide minerals takes place at the solid - solution interface. The electrochemistry of the processes which affect this interface are discussed. The interaction of xanthates with sulfides is an electrochemical process, xanthates being electro-oxidised to chemisorbed xanthate and dixanthogen. The role of oxygen is to provide a cathodic process to allow the anodic oxidation to occur. The hydrophobic condition of the mineral surface is brought about by the presence of the oxidised xanthate species. The action of reagents which can activate or depress the flotation of sulfides is discussed briefly.

Jan 1, 1971

By E. A. Bekchurina, Yu. P. Morozov

"This paper presents the results of a study of the concentration of flotation froths in tapered chutes. The tests were conducted on lab and full-scale plants, and the results obtained were mathematically processed. The kinetics of monophase recovery from a stationary flotation froth, hydrodynamics of froth flows traveling in a tapered chute were investigated. The effect was studied of the mass fraction of the valuable component in the chute feed, yield of the chute’s overflow, and chute design on the concentration performance. Processing of the collected data revealed the general laws of the process and allowed to develop a technique for modeling concentration of the flotation froths of sulphide copper ore in a tapered chute to predict the performance without testing. It was found that concentration in tapered chutes allows to obtain products that are comparable in quality with froths after one or several cleaner flotation stages.INTRODUCTIONThe present production expansion rates require continuous improvement in the grade of flotation concentrates, while the grade of the mineral feed is constantly deteriorating. This leads to a significant complication of flotation flowcharts. Flowcharts become multi-staged with multiple cleaner flotations, negatively affecting the production costs.In recent years, researchers are paying close attention to the processes occurring in the froth layer in the flotation cells. Improving the concentrate grade is facilitated by secondary concentration of minerals in the froth layer, which consists in fixing the hydrophobic particles released as a result of the coalescence of the bubbles of the upper layer when moving downward at the liquid-gas interface of the froth layer. In this case, the released hydrophilic particles, trapped in the froth layer as a result of mechanical removal, migrate from the froth together with the liquid phase."

Jan 1, 2018

By A. P. N. Sutherland

Pipelines for transporting high concentration slurries are often designed using methods applicable to homogeneous non-Newtonian laminar flow. Many industrial slurries though comprise coarse particles in a non-Newtonian carrier fluid, and existing experimental evidence from tests with such slurries demonstrates that they are not homogeneous. Under laminar shear conditions the coarse particles settle, even in statically stable carrier fluids. To understand this better, the Institute of Materials Science and Technology (IMST) at Cape Peninsula University of Technology (CPUT) is conducting ongoing research into the flow of these high concentration non-Newtonian settling slurries. Since pressure gradient and flow rate measurements alone are insufficient to adequately model the flows, an electrical resistance tomography (ERT) instrument developed by the University of Cape Town (UCT)was incorporated into the pipe test loop to determine pipe cross-section concentration and velocity profiles. The software developed to do this is modular and allows different image reconstruction and cross-correlation algorithms to be implemented and tested without significantly changing the rest of the application. At a total frame capture rate of 566 frames/sec a 2.67 GHz Intel Celeron processor with 500 MB of RAM is fast enough to calculate and display velocity profiles in ?real-time? at an update rate of one profile every two seconds. Examples of experimental concentration and velocity profiles obtained using the system are shown and some proposed improvements/extensions to the system are listed.

Jan 1, 2008

By C. O. Karacan, S. J. Schatzel, W. P. Diamond

In coal mining, longwall mining is a preferred method to maximize production by extracting large blocks of coal that have been outlined with a set of development entries. In U.S. mines, longwall panels are typically 305 m (1,000ft) wide (with a continual trend towards even wider panels), and usually over 3,050 m (10,000ft) in length. The increasing size of longwall panels, while helping to increase coal production, may also increase methane emissions due to the exposure of the mining environment to a larger area of fractured, gas-bearing strata. Thus, understanding the impact of increased panel widths on methane emissions, and designing gob gas ventholes and bleeder systems accordingly, can enhance the safety of the underground workforce by reducing their exposure to potentially explosive accumulations of methane/air mixtures. As part of its mine safety research program, NIOSH’s Pittsburgh Research Laboratory has initiated a reservoir modeling effort to better understand the interaction of the various geotechnical factors influencing gas flow within and to the underground longwall mining environment. A focus of this modeling effort has been 1) the prediction of the incremental amount of methane emissions to be expected due to increasing longwall panel widths, and 2) optimizing gob gas venthole completion practices to capture more of the gas in the subsided strata above longwall panels before it can enter the ventilation system of the underground workplace. The history matching phase of the study has been carried out on a 381-m (1,250ft) wide panel in the Pittsburgh Coalbed. Simulations have also been completed for a 442 m (1,450ft) wide panel to estimate the incremental increase in methane emissions and the performance of current gob gas venthole placement configurations. Additional venthole placement configurations were simulated to investigate options for optimizing methane capture from the subsided strata above the wider longwall panel.

By D M. Aranha, M A. Fonseca, M Echtern

The regional syndeformational metamorphism affecting the Itabira Iron Formation (IIF) at Quadrilßtero Ferrffero (QF) was formerly discussed by Dorr (1965), who proposed that quartz grain size could monitor the metamorphism, according to James (1955), and that the formation of haematite could be the result of the synchronous metasomatic process. Herz (1979) suggested the existence of three metamorphic zones, not mentioning the haematite formation. It could be observed that the primary oxide phase in the IIF is magnetite and most of the hard haematite was derived from the metamorphic replacement of magnetite, forming micaceous or schistose haematite. Differently from most iron formations in the world, the formation of haematite deposits at QF occurred under high oxygen fugacity during metamorphism. The haematite microlaths display a strong preferred orientation, which determines the alongated shapes of the fragments. The terms foliated and unfoliated haematite have been applied by Dorr to the micaceous or schistose haematite, and to the isotropic, hydrothermally derived haematite. Under the microcope, the haematite exhibits a strong crystallographic or lattice orientation encircling the magnetite and martite porphyroclasts. The strain rate determined and defined the textural variation, size and economic importance of the deposits and the ore grade. Metamorphism at QF increases eastward and resulted in the formation of a gruneritic Fe-Mg amphibole, at the western portion, followed by a cummingtonitic amphibole at the central-western part, succeeded by the actinolite zone at the central-eastern part, and finally to the tremolite-anthophyllite zone to the east. These zones, arranged in a north-south pattern, can be followed in the pelitic units, whereas appear sericite-chlorite, kyanite-chloritoid and garnet-staurolite respectively. Carbonate geothermometry in IIF also may support the metamorphic variations. At the western zone the haematite forms small lenses within the itabirite, P-contents are slightly higher than in the remaining IIF, haematite grain size is minute, resulting in a submicaceous texture and the amount and dimension of relict magnetite within haematite is greater than in the other parts of QF. Jangada and Serra Azul deposits are examples of this zone. The central-western zone is characterised by significant haematite deposits, in considerable quantity and size, haematite grain size increased, in order to produce a micaceous texture, the P-contents and the amount of magnetite decreased. Pico do Itabirito, Cappo Xavier, Capitpo do Mato and Tamanduß correspond to the deposit type of this zone. At the eastern-central portion the amount of the hard haematite deposits decreases, increasing the soft haematite ore due to higher strain rates. However, it can be perceived that the relict magnetite almost disappeared and the haematite grain size became coarser than the haematite from the western zones. At the eastern zone, the haematite deposits exhibit typical schistose texture, the magnetite porphyroclasts are absent and the lowest P-grades in the haematitic iron formation. The haematite bodies characteristic from this zone are Andrade, Morro Agudo and the deposits at the Itabira District. The hydrothermally derived compact and isotropic haematite deposits, formed subsequently to the micaceous haematite bodies, were generated after deformation ceased, but under very high fluid pressure. The metamorphic reactions magnetite + quartz + H2O = grunerite + haematite and magnetite + quartz + H2O = grunerite + O2 were decisive in the formation of the metamorphic haematite deposits.

Jan 1, 2007

By W. A. Calhoun, M. M. Fine

"One of the most important wartime activities of the Bureau of Mines was the search for new sources of mineral necessary to the prosecution of the war. Part of that effort was in the form of metallurgical service extended to other government agencies engaged in purchasing and stock piling some of the more critical and strategic materials.Fluorite was one of the materials stock piled by the Metals Reserve Company. The fluorite was usually in the form of coarse metallurgical con¬centrate purchased in the United States and abroad. The material was stock¬piled to insure an adequate reserve of fluorite for the metallurgical industries. The domestic production of metallurgical fluorite containing a minimum effective calcium fluoride content of 55 percent,4/ however, gradually increased until production was at least equal to consumption. The stock-piled metallurgical fluorite, therefore, soon became a surplus commodity.On the other hand, the supply of acid-grade fluorite, containing a minimum of 97.5 percent calcium fluoride and n maximum of 1.5 percent silica,5/ was never entirely adequate. Increased consumption of acid-grade material in the aluminum, petroleum, and chemical industries kept that material on the critical list during the war.Under the circumstances, it was felt that a study of the possibility of producing acid-grade fluorite from the metallurgical stock piles would be of some benefit to the war effort. Consequently, samples of fluorite from several of the Metals Reserve Company stock piles were tested by the Bureau of Mines at the request of the War Production Board.Two groups of samples were submitted for testing. One consisted of metallurgical fluorite purchased from Mexico and stock-piled in the El Paso and Laredo, Texas, stock piles of the Metals Reserve Company. The second group of samples was from the stock piles at Gila, N. Mex.The sample submitted from the El Paso stock pile consisted of about 5,000 pounds of minus 4-inch material. Mineralogically, the sample consisted of fluorite contaminated by calcite, chert, quartz, and small amounts of iron and alumina. Although some of the fluorite was reasonably free from gangue at minus 1-inch, much of it remained locked in sizes as fine as 65-mesh.The Laredo sample was about 5,000 pounds of material from five different piles. The samples from each stock pile, A to E, inclusive, were analyzed separately to determine whether the grade of the material in the piles varied markedly. As there was little difference in the analyses, the samples were combined in proportion to the tonnage represented to make a composite sample for testing. The composite sample consisted of fluorite with small amounts of quartz, calcite, and barite. Most of the fluorite was the dark-colored, opaque variety. A small amount of iron-oxide staining was present, and traces of muscovite, clay, pyrite, and tourmaline were noted. The quartz was present as crystals in vugs, and as finely disseminated grains in the fluorite. The druzy quartz and the calcite were free at minus 10-mesh, but the disseminated grains, some of which were 1 to 15 microns in size, were not entirely free at minus 270-mesh. A petrographic estimate indicated that 65 percent of the silica was locked in the 150- to 200-mesh."

Jun 1, 1946

By Pierre Mousset-Jones

A questionnaire was sent out to three classes of mines to determine the extent of the heat problem in U.S. and Foreign underground mines. The following list shows the replies received from this questionnaire, however not all the known hot mines in the US replied. A complete listing of the results can be seen in Appendix I. 1) US coal mines - 37 replies 2) US non coal mines - 23 replies 3) Foreign non coal mines - 36 replies. At the present time there are approximately eleven non coal and one coal mine in the US experiencing heat problems which require special efforts to maintain an acceptable working place climate. However since the survey was completed some of them have been placed on standby. The Mine Safety & Health Administration (MSHA) does not have any specific regulations relating to heat stress. Informally the American Conference of Governmental Industrial Hygienists guidelines are followed which use wet bulb globe temperature (WBGT) with values ranging from 26.7°C to 31.1°C for a moderate workload, and different rest regimes. An MSHA report (Misaqi 1976) recommended that conditions should not exceed 26.1°C WBGT for men and 24.4°C WBGT for women. However, quite recently the organizations involved with planning two of the proposed nuclear waste repositories in the United States, have opted for the criteria of an air cooling power of 300 w/m2, and a WBGT of 27'C respectively.

Jan 1, 1986

By Olaf Hondrum

CHURN drilling equipment at Bagdad consists of two Bucyrus Erie 27-T model drills and one 22-T drill with gasoline engines. The drilling tools weigh approximately 1600 lb. The holes are drilled with 7-in. bits which are heated in an oil burning furnace and sharpened in an electrically powered bit sharpener. A service truck brings the bits to the drills and takes the dull bits back to the shop. The bits weigh around 250 lb. when new and are handled by drill crews without any mechanical handling device. When the management decided to start open- pit operations in 1945 the ruggedness of the terrain was one factor that led to the purchase of the small 22-T model drill. The orebody lies on both sides of Copper Creek Canyon. The sides of the canyon are steep and are cut by numerous narrow branch gullies. The drill had to travel over roads that were narrow and steep. It proved adequate for drilling the capping formation and is still in use.

Jan 1, 1950

By Dean G. Heitt

"The Rain and SMZ mines from 1987 to 1994 produced a total of22.0 t of gold from a pre-mine reserve of 14.24 Mt of ore grading 2.13 g/t Au.Gold at Rain is hosted within the basal portion of the Mississippian Webb Formation. ·Mineralization is closely tied to the Rain Fault which is interpreted to be the main feeder for the deposit. Multiple collapse and hydrothermal breccia events provided permeability for the mineralizing fluids in the otherwise unreactive siltstones. Major alteration events include: decalcification and dolomitization of the Devils Gate Limestone; and silicification, baritization, argillization and oxidation of the Webb Fm. Six ore types based on XRD and visual rock chip Jogging have been identified: siliceous ore containing >40% quartz and <30% barite; siliceous-baritic ore containing mostly silica but >30% barite; baritic ore containing >40% barite; argillaceous ore containing >40% total clays (including alunite); calcareous ore containing mostly calcite and dolomite; and carbonaceous ore which has significant pyrite and organic carbon. Metallurgical testing of the oxide leach grade ores found that recoveries, on -1.3 cm crushed material, were greater than 70%. Results also found that Rain ore has strong grind dependency due to silica encapsulation.The Rain leach pad was commissioned in 1988, and to date 9.3·Mt at an average grade of0.65 g/t Au have been placed. Life to date recovery, through December 1995, is approximately 51 %, for a total of3.87 t of gold produced. Two major factors have contributed to the low leach recoveries at Rain when compared with the metallurgical testing: 1) More argillaceous ore than expected was placed on the pad especially late in the mine life and 2) approximately 50% of the tons placed were run-of-mine with no agglomeration."

Jan 1, 1997

By Thomas J. Feeley

The US Department of Energy (DOE) is supporting the engineering development of three advanced physical coal cleaning technologies: selective agglomeration, advanced flotation and advanced cycloning. Each is capable of significantly reducing the pyritic-sulfur content of US coals. The objective is to provide the coal and electric-utility industries with a cost-effective option for addressing the SO, emission reductions required by the 1990 Clean Air Act Amendments (CAA). A secondary objective is to evaluate the potential of advanced coal cleaning for removing trace elements that are precursors to the formation of hazardous air pollutants (HAS). The proposed National Energy Strategy (NEE) and the 1990 CAA lay a foundation for a more efficient and environmentally sustainable energy future (1991). The need to use energy resources in an environmentally sound manner presents critical challenges and opportunities for coal preparation during the next decade, particularly regarding the control of SOS and HAY emissions. The principal challenge is the development of cost-effective coal preparation approaches for sulfur and HAY precursor removal.

Jan 1, 1993

By B. H. Caudle, R. L. Slobod, E. R. Brownscombe

An earlier publication has discussed three methods lor obtaining relative permeability data on small core sample-: and the apparatus and technique for the capillary pressure displacement method. This paper describes the apparatus and technique for the solution gas and the dynamic displacement methods and presents a routine procedure for obtaining oil-gas and water-oil relative permeability data. Theoretical and experimental considerations are presented to show that the end effect commonly associated with the dynamic flow mechanism is extremely small where constant rates are employed in the flowing phase. An effect of flow rate on relative permeabilities obtained by the dynamic system is found only when gas is one of the flowing phases and this effect is ascribed to a form of channeling in the capillary system. The apparatus and procedure* used to obtain relative permeability data with three phases flowing are described and some preliminary results of the use of this method are shown. INTRODUCTION In a previous publication from this laboratory there appeared a brief discussion of the concepts behind three basic methods for obtaining relative permeability data.&apos; These three methods were called the capillary pressure displacement method. the solution gas displacement method, and the dy. namic displacement method — the names being suggestive of the type of process used for obtaining the desired saturation prior to making the permeability measurements. In the same publication, the apparatus and technique for the capillary pressure displacement method were described and some typical results obtained by this method were presented. This paper will present: 1. The routine procedure used to obtain complete relative permeabilitv data (In small core samples with two phasec flowing; 2. The experimental techniques for the solution gas and dynamic displacement methods for obtaining relative permeability data; 3. The results of some studies on the mechanism of fluid flow through consolidated porous media; and, 4. The preliminary results on the determination of relative permeability for a system in which three phases are flowing. TECHNIQUE AND APPARATUS FOR THE DETERMINATION OF RELATIVE PERMEABILITY WITH TWO PHASES FLOWING In order to obtain relative permeability data on a small core sample which will describe the various phases of reservoir depletion. it is necessary that the methods used duplicate, as closely as possible, the various mechanisms involved in rescbrvoir depletion. It is important that. in any type of relative permedbility determination. the core be originally at virgin reservoir conditions with respect to the fluids within the pore *paces. (for example. oil used to displace water from core until connate water saturation estahlished). and that the subsequent saturation changes in the core be analagous to tile reservoir depletion mechanism for which the data are to he used. PROCEDURE OF DETERMINING RELATIVE PERMEABILITY DATA WITH TWO PHASES FLOWING A standardized procedure has been set up for obtaining relative permeability data and other information on small core samples. This procedure essentially consists of 11 steps as shown below: 1. Determination of tile capillary pressure curve.&apos;! This information is used to help select samples for relative permeability determinations and to charactrrize. in general. the pore size distribution of the sample. 2. Determination of the specific permeabilities to air, oil. and water. These values are those on which the relative pern~eahility calculations are based. 3. Reduction of the core to connate water by an oil drive using the high speed centrifuge. 1. Determination of the critical gas saturation value and the associated relative permeability to oil by the solution gas drive method. 5. Determination of the relative permeabilities to oil and gab in the region where both phases are flowing by the capillary presqure method. 6. Reduction of the sample to residual oil in the centrifuge by an air drive. and the determination of the relative permeability to gas at this point.

Jan 1, 1951

By R. L. Slobod, B. H. Caudle, E. R. Brownscombe

An earlier publication has discussed three methods lor obtaining relative permeability data on small core sample-: and the apparatus and technique for the capillary pressure displacement method. This paper describes the apparatus and technique for the solution gas and the dynamic displacement methods and presents a routine procedure for obtaining oil-gas and water-oil relative permeability data. Theoretical and experimental considerations are presented to show that the end effect commonly associated with the dynamic flow mechanism is extremely small where constant rates are employed in the flowing phase. An effect of flow rate on relative permeabilities obtained by the dynamic system is found only when gas is one of the flowing phases and this effect is ascribed to a form of channeling in the capillary system. The apparatus and procedure* used to obtain relative permeability data with three phases flowing are described and some preliminary results of the use of this method are shown. INTRODUCTION In a previous publication from this laboratory there appeared a brief discussion of the concepts behind three basic methods for obtaining relative permeability data.&apos; These three methods were called the capillary pressure displacement method. the solution gas displacement method, and the dy. namic displacement method — the names being suggestive of the type of process used for obtaining the desired saturation prior to making the permeability measurements. In the same publication, the apparatus and technique for the capillary pressure displacement method were described and some typical results obtained by this method were presented. This paper will present: 1. The routine procedure used to obtain complete relative permeabilitv data (In small core samples with two phasec flowing; 2. The experimental techniques for the solution gas and dynamic displacement methods for obtaining relative permeability data; 3. The results of some studies on the mechanism of fluid flow through consolidated porous media; and, 4. The preliminary results on the determination of relative permeability for a system in which three phases are flowing. TECHNIQUE AND APPARATUS FOR THE DETERMINATION OF RELATIVE PERMEABILITY WITH TWO PHASES FLOWING In order to obtain relative permeability data on a small core sample which will describe the various phases of reservoir depletion. it is necessary that the methods used duplicate, as closely as possible, the various mechanisms involved in rescbrvoir depletion. It is important that. in any type of relative permedbility determination. the core be originally at virgin reservoir conditions with respect to the fluids within the pore *paces. (for example. oil used to displace water from core until connate water saturation estahlished). and that the subsequent saturation changes in the core be analagous to tile reservoir depletion mechanism for which the data are to he used. PROCEDURE OF DETERMINING RELATIVE PERMEABILITY DATA WITH TWO PHASES FLOWING A standardized procedure has been set up for obtaining relative permeability data and other information on small core samples. This procedure essentially consists of 11 steps as shown below: 1. Determination of tile capillary pressure curve.&apos;! This information is used to help select samples for relative permeability determinations and to charactrrize. in general. the pore size distribution of the sample. 2. Determination of the specific permeabilities to air, oil. and water. These values are those on which the relative pern~eahility calculations are based. 3. Reduction of the core to connate water by an oil drive using the high speed centrifuge. 1. Determination of the critical gas saturation value and the associated relative permeability to oil by the solution gas drive method. 5. Determination of the relative permeabilities to oil and gab in the region where both phases are flowing by the capillary presqure method. 6. Reduction of the sample to residual oil in the centrifuge by an air drive. and the determination of the relative permeability to gas at this point.

Jan 1, 1951

By M Lund

Due to operational and regulatory practicalities, pit lakes will continue to be legacies of many open cut mining lease relinquishments. Unplanned or inappropriate management of these significant geographical features may lead to a short-term liability to all stakeholders during mining operations, or to ongoing liability to the local community and environment following lease relinquishment. However, the potential for pit lakes to provide benefit to companies, communities and the environment is frequently unrecognised and yet may be a vital contribution to the sustainability of the open cut mining industry. Improved remediation technologies are offering more avenues for pit lake end use than ever before, at the same time mining companies, local communities and regulatory authorities are also becoming more aware of the benefit these water resources have to offer. Sustainable pit lake management aims to better minimise short- and long-term pit lake liabilities, and yet also to maximise short- and long-term pit lake opportunities as well.

Jan 1, 2006

The Mount Angelo prospect outcrops as two copper rich gossans, the larger of which is 250 ft long and 70 ftwide. The mineralization is epigenetic and replaces part of a brecciated and disturbed lime tone and calcareou sediment sequence.Magnetic and self potential survey indicated a substantial body of sulphide mineralization, the top of which was approximately 100 ft below the surface.Diamond drilling confirmed this and established the presence of a mineral body of at least 500,000 tons, extending to a depth of 300 ft. Of the 500,000 tons, 200,000 ton are primary copper ore which a ays 2 per cent copper.This mineral body is not economic at present, but could become economic if copper mining is established elsewhere in the district...

Jan 1, 1966

Owing to the &apos;creeps&apos; and consequent movements in the mines, followed by the recent fire in the southern workings, the whole of the orebody above the 800 ft. level is now very much crushed and broken. The same applies to the hanging wall or overwall coutrny, which has subsided towards the workings, so that for some years past all development work within the lode has had to be carried out with extreme care.The continual but slow subsidence of the overburden into the stopes necessitates a periodical renewal of all gangways in the lode, and, as the subsidence amounts to as much as 60 ft. in places, these new gangways must necessarily pass through the mullock-filling of old stopes in addition to broken ore. They at times pass into the broken ground of the hanging-wall for some distance, where the orebody has widened underneath by the original folding and puckering.

Jan 1, 1932

By B Putland, I Lovatt, D Schwann, A Cervillin

The Mount Carlton project in Queensland&#39;s North East sits on a high-sulphidation epithermal style deposit rich in gold, copper and silver. Mt Carlton is an open pit mining operation with ore processed using a primary crusher, single stage SAG mill and flotation to produce a concentrate for sale. Orway Mineral Consultants (OMC) was involved in the original design of the comminution circuit and the project was commissioned in late 2012, with first concentrate shipped in March 2013. When Evolution sought to optimise the project in 2015, OMC was invited to assist by undertaking a circuit review to identify opportunities for the optimisation. During 2016, the Mt Carlton site team implemented the optimisation strategies developed in conjunction with OMC. These included reconfiguring the SAG mill discharge arrangement, reducing the average ball diameter and allowing the mill to operate at higher speed and under more autogenous conditions. Cyclone operation was changed to constant pressure and the vortex finder size was decreased. The combined strategies improved energy efficiency and allowed higher SAG mill power utilisation. The additional power has been used to increase throughput by 2.4 per cent while achieving a 27&#181;m reduction in product size (P80) to gain downstream recovery improvements. The reduction in grind size has been achieved with only 6.8 per cent increase in specific energy consumption because of a 6.5 per cent increase in grinding efficiency. The circuit product size is also notably more consistent due to the improvements made to the cyclones, providing benefit to the downstream flotation circuit. A significant decrease in ball consumption was also gained, saving hundreds of thousands of dollars a year in operating cost.This paper will discuss the circuit design, start up and will detail the changes made during the optimisation and why these were successful.CITATION:Putland, B, Lovatt, I, Cervillin, A and Schwann, D, 2018. Mount Carlton comminution circuit design, start-up and optimisation, in Proceedings 14th AusIMM Mill Operators&#39; Conference 2018, pp 517–528 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By V. K. Srivastava, T. Gupta, T. Ghosh

"In recent years, the demand for rare earth elements (REEs) has grown due to increasing demand and global supply shortage. The supply deficit of these critical elements has encouraged the search for new sources, with coal and coal byproducts as possibilities. Coals from certain parts of the world can be rich in REEs and can approach a total concentration of 1,000 ppm. Two Alaskan coal samples, from Healy and Wishbone Hill, were investigated for the effects of density and particle size on REE concentrations for three selected size fractions, and flotation tests were conducted on finer fractions. Additionally, bottom ash and fly ash samples from a power plant were examined for their REE concentrations. The results show that the upgrade potential for REEs on an ash basis from a whole-coal basis ranges from 2:1 for the Wishbone Hill samples to 4:1 for the Healy coal samples. Flotations of the finer fractions of the two coal samples, conducted under similar conditions, revealed higher concentrations of REEs in the tailings. Both coal samples had comparatively higher contents of light-group rare earth elements (LREEs) than heavy-group rare earth elements (HREEs). REE content trends for the power-plant products on an ash basis indicate that fly ash has slightly higher concentrations of both LREEs and HREEs than bottom ash. IntroductionRare earth elements (REEs), also known as rare earth metals, and their compounds are vital components in industrial, automotive, petrochemical, defense and medical applications. Dysprosium in combination with other elements is used in laser materials and nuclear control applications. Neodymium is present in magnets that are used in the manufacture of wind turbines and hybrid cars. Europium, terbium and yttrium are used in devices that have visual displays such as computer screens and laptops (Haxel, Hedrick and Greta, 2002; Bunzli, 2013). REEs pose fewer environmental problems of disposal and recycling than their conventional heavy metal counterparts (Haxel, Hedrick and Greta, 2002). They are key materials for radar systems, avionics, modern national defense and satellites (Cammarata and Sieradzki, 1994; Hedrick, 2010; Martin, 2010; Szumigala and Werdon, 2011; Cordier, 2011; Bunzli, 2013). REEs are often classified into light-group rare earth elements (LREEs) and heavy-group rare earth elements (HREEs). This classification is primarily based on the electronic configuration in the outermost shell. LREEs, ranging from lanthanum to gadolinium, have a single or no spinning electron in the outermost 4f shell while HREEs, ranging from terbium to lutetium, have paired electrons in the 4f shell. This difference in electronic configuration is responsible for the differences in physical and chemical properties of REEs."

Jan 1, 2017