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By D J. Clark, R F. Wright, M D. Goodz

The A1 Gold Mine is a Devonian-age narrow vein high-grade gold deposit located 115 km east of Melbourne. The mine operated almost continuously from 1861 to 1992 producing 442 334 ounces of gold (13.8 t) from 530 436 tonnes from primary gold ore tonnes processed at an average recovered grade of 25.9 g/t Au. The A1 dyke was attributed with a yield exceeding 620 000 ounces (19.3 t) of gold (including gold in alluvial and tailings deposits), and was renowned as one of VictoriaÆs premier mines paying considerable dividends. The orebody was principally in a diorite dyke bulge 150 m long, 45 m wide and 700 m deep and was mined via two vertical shafts. The mine site was closed in 1992 and the site was rehabilitated in 1999. In 2008 - 2009, a diamond drilling program identified various extensions to the host dyke lithology and to gold-bearing quartz vein filled fault zones over a 700 m strike length. The outcome of this study was the establishment of a mine geology corridor four times longer in strike length than the original 1970s model. This opens A1 dyke hosted deposit style to exploration outside the historical dyke bulge and provides exploration opportunity for all similar deposits. Construction of the first 3D geological model has developed new insights on the host rock diorite dyke system and identified various extensions to both host stratigraphy and to gold-bearing mineralised structures. Coarse visible gold in quartz vein mineralisation (>30 g/t Au) and medium-grade stockwork mineralisation (8 - 15 g/t Au) has been intersected within 100 m of the surface and up to 300 m along strike of the nearest historical underground workings. At depth it appears that the mineralisation is continuous with the main dyke body with consideration of minor rotation in the strike orientation and limited reverse thrust faulting showing maximum displacement of 10 - 20 m. Along the A1 mine corridor, between two and five parallel dykes are observed at different drill sections. The gold mineralisation is hosted mainly within the dyke rocks, but where the sedimentary rocks are intensely silicified or are xenolith rafts, the gold mineralisation continues across these sedimentary rock blocks. There has been inference to the role of silicified sedimentary rocks as a second ore host and a bounding material for inflections in fault and vein orientations. In the central 150 m long A1 mine dyke bulge, the extremities are demarcated by four to five parallel dyke fingers (referred to as apophyses) going both north and south. These apophyses are clearly observed both vertically and horizontally between levels No 4 and No 9. The dyke fingers entrap sedimentary rock xenoliths and collectively form the A1 dyke æcorridorÆ, which is quite uniform in overall width from the easternmost contact (footwall) to the westernmost contact (hanging wall). Dyke fingers were assumed to coalesce at depth into a single dyke, but recent drilling shows this feature to repeat in several positions with depth and along strike. Key observations are the relationship between gold grade and fracture density, alteration, sulfidation, host rock morphology û relation of contact shape and fault zones. These relationships allow for the classification of prospectivity indicators and geology as a guide to potential extensions of mineralised zones. Mining geology is contributing to the whole-of-mine life planning and development where decline path, stockpile and infrastructure positions are controlled by geology.

Jan 1, 2009

By Brian Rausch

Agenda ?? Refresher: Victor Project Execution ?? Operations Capability roadmap: ? Operations staffing starter group: design participation ? Operations staffing build up for production start-up ? Training and commissioning integration ? Turning OPSCAP ramp-up into a project ?? Go Live! The Results

May 1, 2009

By Ramin Motamed, Fahim M. Bhuiyan, Raj V. Siddharthan, Joseph Toth

The difficulty in material characterization and the erratic response of cemented soil layers, such as caliche in the Las Vegas valley, creates challenges for practicing engineers to reliably predict the response of deep foundations. The focus of this paper is the numerical prediction of axial response in drilled shaft foundations, which are commonly used in infrastructure projects (i.e., bridges and tall buildings) in Las Vegas, NV. The prevalence of hard caliche layers with variation in the degree of cementation add to the complication in numerical modeling. In this study, the applicability of two existing t-z models, developed for Florida limestone and soft rock, was evaluated based on numerical simulations of three bi-directional load tests conducted at caliche-dominant sites. The corresponding top-down load tests were also simulated for further assessment. A MATLAB-based finite-difference program, NVShaft, has been used to implement the mentioned t-z models in axial load analysis. Complexity originating from drilled shaft construction and the interaction with caliche during one axial load test resulted in a stiffer predicted response compared to measure data. For the other two load tests, both t-z models produced comparable load-displacement responses. It was observed that the t-z model for Florida limestone predicted relatively stiffer responses and higher drilled shaft capacity.

Sep 8, 2021

By Robb. V. M., F. Walraven, L. J. Robb

"Abstract -The old Albert Silver Mine is a polymetallic deposit comprising concentrations of Cu­ Pb-Zn-Ag-U-F within a set of sub-parallel quartz-hematite veins which occur within the fine-grained apical phase of the 2050 Ma old A-type Bushveld granites. Mineralization occurs as an early pyrite­ chalcopyrite-arsenopyrite-galena-sphalerite-(argentiferous) tetrahedrite paragenesis followed by a later, more oxidized assemblage comprising chlorite-hematite-fluorite-pitchblende. Accumulation of metals appears to have taken place at the interface between a coarse-grained porphyritic granite and an overlying fine-grained phase: veins occur in the latter and represent leakage of magmatic fluids from the differentiated, water-saturated, subjacent granite.Mineralization processes in the Bushveld granites are believed to be related to long-lived circulation of dominantly magmatic fluids stimulated by the high heat productive capacity of the host rocks. Endo- and exogranitic tin-tungsten and base metal mineralization formed during an evolving hydrothermal system that lasted for several hundred million years, forming innumerable small- to medium­ scale polymetallic deposits. At the Albert Silver Mine, unroofing of the cover sequences at circa 1600 Mato 1700 Ma resulted in the incursion of lower-temperature, high-f02 meteoric fluids which remobilized the earlier sulfides and introduced the paragenetically late U-F mineralization ."

Jan 1, 1994

By Behrooz Abbasi, Seyedsaeid Ahmadvand, Thom Seal, Babak Azarfar, Bryan Ulrich

Hydro-Jex® is a new enhanced method for heap leach treatment with significantly higher mineral recovery. In this case study at the Los Filos Mine in Mexico, the Hydro-Jex operation is evaluated for heap leach stability. This is pursued by numerical modeling of the heap leach pad stability and well monitoring of the phreatic surface before and after the Hydro-Jex operation. Experimental and numerical results both indicate an improvement in mineral processing under the influence of Hydro-Jex. Numerical results show an insignificant decrease and a significant increase in stability during and after Hydro-Jex injection application, respectively. The integrity of the liner is maintained in both cases. The zonal injection pressure, operationally below the overburden pressure, is found to be negligible compared with the dimensionality of the heap, and stability of the structure is not exposed to any significant risk, even up to 25%above overburden pressure. Furthermore, heap leach factor of safety increases after Hydro-Jex application. This is attributed to breakdown of the water solution build-up and thus a decrease in the phreatic surface depth below the top of the pad. It is suggested that injection wells be drilled, based on thorough geophysical data, in locations where overcompaction of heap material results in water solution build-up and pore pressure enhancement. Compared with traditional heap leaching, the Hydro-Jex technique not only expedites mineral processing by increasing chemical kinetics extraction but also increases the stability of the heap by unclogging drains.

Jun 29, 2020

By M C. Evans

"Mine decommissioning is the final phase in a mining project. Planning for decommissioning must commence for a proposed mine even before the government approves it. Queensland mining approvals require proponents to commit to completion (or closure) criteria defining successful rehabilitation. Queensland mining project statutory environmental authorities must also specify how progressive rehabilitation is to occur throughout the mining project. Final landforms with graded banks together with creek and run-off diversions are often required and constructed early in the life of a mining project. At closure, mining projects must demonstrate that future medium-term risks are not significant, or failing this, a residual risk financial payment must be made to the state. CSIRO climate change projections indicate that Queensland is likely to become warmer this century with less rainfall in parts and with extreme rainfall events likely to occur more frequently. This project was undertaken to?determine: if current rehabilitation planning tools assist in determining the environmental risks from mining closure not adequately addressing climate change if these risks are addressed by current rehabilitation outcomes.The north-west Queensland mining region and the central Queensland coalfields were represented in this project by five study sites. Local data sets for temperature, rainfall and rainfall intensity were produced using conservative greenhouse gas emission scenarios representing likely future atmospheres, and using the SimCLIM climate model, Evaporation data sets were also derived from available climate parameters. These projected climate variables supported equations and models used in Queensland to determine mining project rehabilitation completion criteria. Storm intensities and return intervals were directly applied to assess the likelihood of failure of engineered structures such as stormwater diversions and banks. Plant cover change determined by an existing growth model together with rainfall intensity and changes in the R and C factors of the universal soil loss equation (USLE) erosion model enabled estimates of long-term erosion rates. Flood estimates were undertaken using regional rated catchments.The study found that stormwater diversions and banks on recontoured rehabilitated landforms, if constructed to currently accepted completion criteria, would likely fail within 30 years and with the likelihood of failure steadily increasing thereafter. The change in likelihood of failure was able to be estimated and could be applied to the determination of residual environmental risk for approval of a surrender application involving rehabilitation. The USLE model showed that long-term erosion rates increased as a consequence of climate change from north to south across the Queensland mining precincts. Because the growth model did not consider carbon dioxide fertilisation affects, results would likely be worse-case.Likely climate change outcomes have consequential residual environmental risks of mining project rehabilitation failure. This increased risk may result in increased payments to the state from mining projects where high consequences exist. The liability to the state and risk to the environment can be avoided if today’s completion criteria address tomorrow’s climate change impacts.CITATION:Evans, M C, 2014. Queensland mines should consider climate change impacts for decommissioning, in Proceedings Life-of-Mine 2014, pp 535–562 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jul 16, 2014

By D. A. Elkins

Design plans and detailed cost estimates of mining and treating ore from Maggie Canyon deposit by two alternative methods which can be used in the event of a sudden need to exploit this resource are given . Lower costs are estimated for the operation employing oil - emulsion flotation . The total capital investment required for this operation is estimated at $ 11,750,000 . Assuming an 85 percent recovery in mining , 55.6 pct of the manganese in the ore reserve would report in 153,333 tons of ferromanganese containing 75 pct manganese . The production cost for the 5 - year operation would be about $ 245 per ton of ferromanganese . The total annual operating cost would be approximately $ 7.5 million , distributed , in pct , as follows : Mining 11.9 , milling 24.4 , sintering 9.9 , smelting 47.2 , hauling ore and sinter 2.8 , and general offices 3.8 . Recovery and costs are both higher for the operation employing dithionate leaching . In this operation the required investment is about $ 17,220,000 . Manganese recovery would be 67.6 pct in 186,160 tons of ferromanganese . Production cost would be about $ 284 per ton of ferromanganese . The total annual operating cost would be about $ 10,575,000 , distributed , in pct , as follows : Mining 8.4 , milling 44.4 , sintering 7.4 , smelting 34.7 , hauling ore and sinter 1.3 , and general offices 3.8 . Potential process modifications might reduce the operating cost of the first operation by as much as 7 pct and that of the second operation by as much as 9.5 pct , but exploitation of the deposit by the techniques studied is not economical today .

Jan 1, 1964

By J. Schoenbacher

Park City Municipal Corporation (PCMC), long before being recognized as an Olympic venue was known as one of the great American silver mining towns. During a century of active mining, the Park City mining district produced millions of ounces of silver in addition to a substantial amount of mine tailing waste. Since 1985 the City has been remediating these impacts with state and federal oversight. One particular challenging CERCLIS site, that was previously a historic mine tailings pond is known as Prospector Square Development (CERCLIS Listing Silver Creek Tailings UTD98051404). This site has been very challenging due to the metals that impact the shallow ground water that eventually drain into the Silver Creek Watershed. To address the water quality impairment the City and Missouri University of Science and Technology teamed up to investigate the feasibility of constructing a horizontal-flow wetland to treat this pollutant source. This effort began with the building of a pilot cell in June of 2004 and lead to the construction of a full scale horizontal-flow wetland in the fall of 2008. The design of the pilot and full scale biocell was based upon lab-scale research conducted by the Missouri University of Science and Technology. In October of 2008, the Prospector Drain effluent was introduced to the system and to date analytical results reveal that the biocell is treating the Prospector Drain outfall below the Silver Creek Total Maximum Daily Load (TMDL) endpoint goals for zinc .39 mg/L and cadmium .00075 mg/L. The water chemistry of the influent, that originates from the historic silver mine tailings pond, is impaired with zinc and cadmium and has low iron with a pH of roughly 6.5. The construction of this unit encountered many challenges related to constituent relations, regulatory scrutiny, constructability and start-up. Nonetheless, since implementation this unit is considered a success for improving water quality within the Silver Creek Watershed.

Jan 1, 2011

By The Staff

"THE property of Red Mountain Mines Limited is located 11/2 miles north and west of the town of Rossland, in southern British Columbia. The mine is situated on the flank of Red mountain, famous in pioneer days as the site of a number of profitable gold-copper producers. Mining and milling commenced in May, 1966, and by the first of July the concentrator was treating close to its average design capacity of 400 tons per day. The following description of the property and its operations is divided into three parts, dealing respectively with geology, mining and milling.GeologyAll the known ore reserves of Red Mountain Mines occur on the Coxey claim, on the west slope of Red mountain. Although there are indications of molybdenite mineralization elsewhere on the Company's property, these have not been developed.The Coxey and adjoining areas are underlain by the Mount Roberts formation of the Rossland volca-nics. This formation consists of an interbedded series of volcanic and sedimentary rocks, mostly brecciated and silicified near the ore zone, and all intruded by igneous rocks which occur in various forms, and vary in composition from basic to acid. The country rock in the vicinity of the mineralization seems to be mostly a volcanic, approximately andesitic in composition, and possibly a surface flow. There is much banding, some of which is undoubtedly due to tuff and agglomerate layers, and some to narrow, siliceous, sedimentary horizons such as the surface exposure of the main ""A"" orebody, much of which was a thin capping of greyish banded rock that looked like quartzite. The drill holes also intersected occasional layers of black, argillaceous quartzite, sometimes altered to a greenish colour. The whole assemblage has been silicified with varied intensity, sometimes to such an extent as to have obscured or obliterated the original characteristics. The mineralized zone has also been strongly brecciated, the fragments varying in size from less than an inch up to large masses, best described as a mega-breccia. Anomalous results obtained in drilling, such as sedimentary sections that do not appear in adjoining holes, may sometimes be due to the presence of these large blocks, no longer in their original position. The whole volcanic unit is thus very complex and confusing. For practical purposes, the ore may be said to occur in a greenstone formation with minor sedimentary interbeds and considerable later igneous material."

Jan 1, 1967

By Steve Custer, Chris Bennett, Patrick Garretson, Glenn Dobby, Jacques McMullen

"Barrick Gold is in the process of expanding one of its grinding circuits at the Goldstrike property as a response to both increasing ore hardness and increased ore sensitivity to finer grinding as it relates to gold recovery. The plant currently operates with two parallel grinding lines, each with a SAG mill, a pebble crusher, and a ball milling arrangement. As part of determining what additional equipment was to be required, a CEET evaluation program was conducted (CEET is an acronym for Comminution Economic Evaluation Tool). The work included: Development of a hardness ‘model’ for the ore body, as described by SAG Power Index and Bond Work Index;Site benchmarking surveys to fine tune the SAG and ball mill calibrations within CEET;Conducting CEET studies to examine the process options;Comparing CEET results to standard grinding circuit design techniques.The recommendation of the study, presently being implemented, is the installation of an additional ball mill on one of the two grinding lines. This paper reviews the sizing techniques applied, providing a CEET case study for circuit performance analysis and circuit design. OVERVIEW OF COMMINUTION AT GOLDSTRIKEOre feeding the autoclaves at Goldstrike are first processed through two parallel grinding lines. Both lines use SAG mills with cone crushing of pebbles followed by ball milling. A summary of the key circuit parameters is provided in Table 1. Line 1 primarily processes underground Meikle ore, although when no Meikle ore is available, it processes open pit Betze ore. Line 2 processes Betze ore exclusively. The Mill Line 1 P80 objective for Meikle ore is 74 microns. According to the recovery optimization analysis, a P80 of 90 microns was recommended for Betze ore. The potential however exists to perform co-mingling of both ore types and feed the higher grade Betze ore to Line 1, in which case the P80 of 74 microns would be retained."

Jan 1, 2001

By C. Morlot, C. Auvray, E. Fourreau, J. Talandier

"During the excavation of underground galleries in a rock mass, reorganisation of the stress field around the site results in damage to the surrounding material. In the framework of research undertaken at the ANDRA underground laboratory in France, galleries have been excavated in a Callovo-Oxfordian argillite formation. The damage has manifest as a number of fracture systems in the adjacent rock. Observations have shown that fractures generated during excavation and storage exploitation are able to self-seal during re-saturation of the site in the post-closure stage. Although indirect evidence for argillite self-sealing has previously been reported, from experiments performed both in situ and on samples, no direct observations of self-sealing have yet been made.For the present study, we performed a range of self-sealing experiments using a newly-developed triaxial compression cell placed within a nano-CT scanner with a 10 µm resolution. The body of the compression cell is X-ray transparent, allowing sample healing to be monitored directly. The samples contained an artificial fracture that had been generated in the laboratory, into which a fluid was injected. The fractures were orientated either perpendicular or parallel to the plane of anisotropy of the material. Our initial results demonstrate that when fluid is injected perpendicular to the plane of anisotropy, the flow-rate has no apparent influence on the kinetics of fracture closure. Permeability varies significantly, from 2.10-14 to 2.10-18 m2 over 116 hours. Post-test observations of the fracture lips show swelling that appears to be orientated perpendicular to the fracture plane and therefore parallel to the plane of anisotropy. Initial results for an injection parallel to the plane of anisotropy suggest that, in this case, the rate of flow affects the kinetics of fracture closure. For a flow-rate of 0.25 ml/min, closure begins after around one minute. In contrast, for a rate of 0.05 ml/min, it is necessary to wait several minutes before partial sealing of the zone is observed. The reduction in permeability is again significant, from 2.10-15 to 4.10-18 m2 over 96 hours. After completion of the test, swelling was observed in elongated zones that lie parallel to the fracture plane and therefore to the plane of anisotropy."

Jan 1, 2015

The coal resources of the Singleton- Muswellbrook area of New South Wales are of major importance to Australia, and are likely to play a significant role in meeting the expanding demands for energy in many countries of the world. Coal resources of 45 thousand million tonnes of which 15 thousand million tonnes lie at a depth of less than 200m have been estimated. The history of coal mining in the area commenced in the mid 1800's and has been one of fluctuations in production but of rapid expansion in more recent years. It is destined to become the largest coal producing area in New South Wales. Coal is being won from the area by strip mining, open pit mining and by underground means. The techniques involved are described. The area is well endowed with infra- structure such as modern towns, railways, road- ways and access to port facilities. Production of both coking coal and steaming coal is expected to rise significantly within the next 25 years. A large proportion of the State's anticipated increased production to between 117 and 177 million tonnes by the year 2000 is likely to come from this area.

Jan 1, 1979

By William H. Lewis

This paper describes the Bureau of Mines efforts in the research and development of a new and innovative mine lighting system which is based on fiber optics technology. The new lighting concept offers significant advantages over conventional systems in the areas of both safety and long- term maintenance costs. An overview of Bureau research into the problems and limitations of present-day mine lighting systems is also presented.

By G. Demi

Chromium ore exploitation has commenced in 1948 in Albania and there are produced about 24.3 million tons up to the end of 2006. Last years the prices and need were increased notably. Main export of chromium ores and concentrates was accomplished respectively 114 500 ton and 13 000 ton in People Republic of China during 2006 year. Location, status, reserves and grade of chromium deposits of Albania are presented in the paper. Chromium ore enrichment is related with their composition and Cr2O3 content, as well as with market requests. Actually, high grade chromium ores with Cr2O3 content over 38% ~ 40% are directly exported or treated in metallurgy, but last time have been exported and chromium ores with 28% ~ 30% Cr2O3 content for the reason that dressing plants can not be operated for investment lack. High grade chromium ores have been treated in heavy media separation plant before 1990. It is presented flow sheet, figures and necessity to put in operation HMS plant in the paper. Actually, low grade chromium ores with content 16% ~ 20% Cr2O3 are not enriched for the lack of investments, but before 1990 they have been concentrated in dressing plants producing chromium concentrates grade 48% ~ 50% Cr2O3. In the paper are shown technological schemes and industrial figures during more than 20 years operation and possibilities to reconstruct these mineral processing plants. Only chromium mineral processing plant of Bulqiza is in operation using as raw material its old existing tailings. The flow sheet and figures show that are possibilities to increase recovery and grade of concentrate in the plant. Separation and concentration of slimes in suitable equipment gives visible improvement of Cr2O3 recovery. Several tests have been carried out with flotation and magnetic separation methods for enrichment of low grade chromium ores. Flow sheet and figures of mineral processing ores content olivine as gangue mineral are interesting, because combination of gravimetric with magnetic methods is necessary in this case. In the paper are presented the tests and good results of low chromium ore pre concentration. Metallurgical treatment of chromium ores to produce Ferro chrome, as well as technological process, figures, consume of electrical power and materials in Elbasani and Burreli furnaces are shown and necessary investments to treat in metallurgy all produced chromium ores in Albania are considered.

Jan 1, 2014

By Richard E. Sylwester

Evaluating surface and subsurface conditions for marine foundations (bridges, causeways, terminals, etc.) is often done with a limited amount of data. Subsurface information for these projects is primarily acquired using traditional methods, such as boreholes, test pits or divers, which tend to be expensive and limited in the area of coverage. A number of geophysical methods, including precision bathymetry, sidescan sonar, and seismic reflection or subbottom profiling are extremely cost-effective and obtain significantly more data than can be acquired using traditional intrusive methods. These geophysical methods provide detailed surface images and continuous profiles of the subsurface stratigraphy. This information can be invaluable for selecting the best location for geotechnical boreholes and to map potential geohazards such as submarine slides and filled or open scour holes. Offshore investigations conducted for a proposed highway bridge (Knik Arm Bridge, Cook Inlet, AK), the retrofit of two existing bridge (Antioch and Dumbarton Bridges, CA) and a proposed cruise ship terminal (Ketchikan, AK) used a combination of geophysical methods to map water depth, detect and map debris on the seabed, map the thickness of unconsolidated sediment, determine the depth to bedrock and identify potential geohazards such as scour holes. The results of the geophysical investigations will be used to select locations for obtaining geotechnical borings, to extrapolate geologic information between existing or proposed boreholes, evaluate the potential depth of scour and design a pile support pier. Geotechnical engineers, offshore contractors and bridge designers are realizing the importance of the early use of offshore geophysics for (i) site characterization, (ii) to reduce the uncertainty of geotechnical conditions thus avoiding designs that may be overly conservative and thus more expensive and (iii) to assist in selecting locations for geotechnical borings.

Jan 1, 2013

By Sushant Upadhyaya, Deniz Karadeniz

As part of the widening of I-64 in Williamsburg, Virginia, an extensive subsurface exploration program consisting of Standard Penetration Tests (SPT), Cone Penetration Tests (CPT), Dilatometer Tests (DMT), and Vane Shear Test was performed. In addition to these in-situ tests, an extensive laboratory testing program was completed including Consolidated-Undrained Triaxial, Unconsolidated-Undrained Triaxial, Direct Shear, and consolidation tests. The strength and the compressibility properties are deemed conservative for Yorktown and St. Mary’s Formations when evaluated based on the current topography, the existing overburden pressure and SPT values. SPT exhibited low blow counts especially within Yorktown Formation due to the increased excess pore water pressures resulting in a localized liquefaction at the tip of the split spoon sampler corresponding to remolded or fully softened strength of the soil. Therefore, the applicability of the SPT correlated soil parameters somewhat leads to conservative designs with deeper piles to achieve a desired structural load demand. Generally, the in-situ estimated soil design parameters are found to be comparable with the laboratory test results corresponding to long-term resistance gain with time. It is of practical importance to employ realistic soil design parameters for design applications such as pile foundations to provide cost and schedule savings. This paper presents a discussion on the soil strength estimates and variability from in-situ and laboratory tests for realistic strength characterization of Coastal Plain deposits.

By Yong Pan, Purushotham Tukkaraja

It has been well understood that blasting is the cost-effective method for breaking rocks as compared with the mechanical systems. However, vibrations induced by blasting in open-pit mines could pose problems to the structures surrounding the mine site. Blast-induced ground vibration has been the subject of research for several studies in the past; because of the complex nature of blasting mechanism, it is difficult to predict blast-induced vibrations. Even though there are several approaches proposed by the previous researchers, traditional regression analysis is still playing an important role in predicting blast-inducedgroundvibrations.

Jan 1, 2019

By C A. Brannon, C A. Dipas, H A. Vega, D Villa

The development and construction of the Grasberg block cave mine (GBC) is in progress, currently targeting initiation of caving in late 2018. Current production planning anticipates ramping up to full production of 130 000 to 160 000 t/d by 2027. As GBC approaches the production phase, there is a high priority on increasing the accuracy and level of detail in the production plan. The advance of the cave front directly controls the drawbell opening rate that is achievable. Therefore, an essential component of this plan is to produce an undercutting and drawbell sequence that honours the caving parameters that have been set for the mining blocks by the GBC production planning team.The PT Freeport Indonesia (PTFI) mine planning team and the Geovia caving business unit have developed a computational tool (Undercut Tool) capable of generating an undercutting sequence that follows a set of caving rules, such as advance rate per tunnel, maximum blasted area per period, control of lead-lag and shape of the undercut face. This tool also produces a drawbell sequence that honours the undercutting advance sequence, which is ultimately used to generate a life-of-mine production plan. This paper describes the inputs and outputs of the Undercut Tool that have been used to compute the long-term production plan for the GBC mine. It will further describe how the Undercut Tool takes into account operational constraints and geotechnical considerations that must be considered when developing a defendable production plan. Included is a discussion of the initial results of the planning outcomes from the tool; it will demonstrate how this work will support specific aspects of the plan such as the detailed undercut production drill and blast plans for the drill ring sequence, as well as how that plan will drive the drawpoint opening plan.CITATION:Villa, D, Brannon, C A, Dipas, C A and Vega, H A, 2017. Integrated drawbell and undercut scheduling using a computational tool at the Grasberg block cave mine, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 271–276 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

By Brosnan J. G

Simcoa Operations is the only silicon smelter in the region and since the plant was commissioned in late-1989, has progressed from supplying silicon metal to the secondary aluminium market to the current position of supplying in excess of 90 per cent of its production to the high quality chemical and primary aluminium markets. This position has been achieved through the unique advantage which Simcoa has developed within the industry, namely raw materials, people and Simcoa's ability to adopt and use modern technology. A quality culture was instilled into the workforce prior to commissioning which ultimately led to AS3902 qualification in 1992. Simcoa has continued its quality drive through the formation of 'Simcoa's Quality Leadership Process' which is planned to make Simcoa the best silicon producer in the world.

Jan 1, 1995

By Kasai H, Hibi T, Matsuishi S

Coal oil mixture (COM), a liquid fuel pro- duced by mixing together coal and heavy oil on the 50-50 basis, has been brought to a level of practical use in Japan, being actually employed by a oil fired system at Yokosuka Thermal Power Station of The Tokyo Electric Power Co., Inc. A COM Production Plant, built in Onahama which is located about 160 miles from Yokosuka, required COM to be transported by sea. Mitsubishi Heavy Industries, Ltd. therefore performed a series of studies to develop a spe- cialized COM carrier, the world's first of its kind. Long lasting high stability is of pri- mary importance to successful use of COM. Much have been done in the way of research on stability of COM in the static storage, and the mechanism of COM static: stability is almost completety known. On the other hand, the knowledge about the COM dynamic stability, such as the stability while being transported aboard the COM carrier at sea, is still limited at the moment. The motion of COM aboard the COM carrier and how COM would settle were studied by tests. A visualization test on the COM behavior under dynamic motion was also performed and the mechanism of COM dynamic stability was analysed. The tests showed that the ship rolling motion had @n effect of promoting the settling of coal content of COM in the cargo hold. And studies were also made to device a method for esti- mating the settling quantity of coal during sea Transportation.

Jan 1, 1987