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By C E. Loayza, R M. Pinto, J G. G=mez

The Yanacocha District is located 20 km north of the city of Cajamarca, in the Northern Andean Orogenic belt of northern Peru.Gold production may have occurred as early as Incan times (Paverd, 2000), but modern exploration that began in the 1960s targeted only copper and silver. Newmont Mining Corporation, BRGM and Compa±fa de Minas Buenaventura began exploring for gold in 1983, with Newmont as operator.Initial drilling took place in 1985. By 1992 a reserve of 1.28 million ounces was reported (Teal et al, 2002).Production began at the Carachugo deposit in 1993.Current reserves are 31.7 million ounces at $US 325 per ounce at a grade of 1.03 ppm (Newmont Annual Report, 2003).The operating company, Mineral Yanacocha SRL (Newmont 51 per cent, Buenaventura 44 per cent and International Finance Corporation five per cent) produced 2.85 million ounces in 2003, making Yanacocha one of the largest gold mining operations in the world. The district is made up of a series of epithermal, high sulfidation style gold deposits and one gold-rich gravel deposit (La Quinua), aligned in a NE trend.La Quinua is not discussed in detail in this paper. The bedrock deposits are hosted in a Miocene volcanic package, the Yanacocha Volcanic Complex that also trends NE.Re gional NW striking Andean faults intersect the NE striking Trans-Andean Chicama-Yanacocha structural corridor (Turner, 1997), localising the district mineralisation. These two structural orientations dominate the district, controlling breccia and intrusion locations, and gold mineralisation. Discontinuous EW oriented fracture zones are interpreted as extensional and locally are important in controlling gold mineralisation.

Jan 1, 2004

By Smith J. W, Hart G. N

Compositional and isotopic analyses of coal seam gases in the Southern Coalfields have shown that these gases frequently contain abnormally high concentrations of magmatically derived carbon dioxide. The size of this carbon dioxide reservoir and the extent of permeation of the sediments by carbon dioxide are not known.Therefore caution in evaluating the natural gas potential of the region is advised.

Jan 1, 1981

By Espig D, Standish N

In the paper a stochastic model of the batch sieving procedure is presen- ted resulting in a system of ordinary differential equations to describe the time dependence of the mass fractions on the sieve surfaces being randomly influenced by sampling errors. The coefficients of the system can be interpreted as sieving velocities. Their dependence on the sieving con- ditions is discussed and a special type of functional relationship and methods are suggested to determine this function experimentally. Moreover the applicability of the approach is demonstrated by an example to evaluate the particle size distribution, if only the result of incomplete test sieving is known. For this problem a rough error estimation is performed.

Jan 1, 1984

For an exploration area with a predetermined grid of data points, a construction is given for elementary blocks which subdivide the entire area without omission or overlap, and with the property that each data point is situated at the centre of its corresponding block. The construction has a useful optimal property, and more importantly avoids an error which has been made recently in more than one publication.

Jan 1, 1985

By C Grobler, M Recklies, G Jiang, I Taylor, M Morgan, G MacDonald, L Smith

The resource estimation of lateritic deposits, such as Aurukun, presents specific issues related to the lateral changes in thickness and elevation of the various horizontal layers (or zones) within the deposit where the x and y dimensions are orders of magnitude greater than the z dimension. The objective was to develop a three-dimensional (3D) block model that retained the vertical and lateral variation inherent in deposits of this type to allow full optimisation of the production plan without prior selection of an economic portion (enriched bauxite layers) of the profile at the resource estimation stage. The Aurukun bauxite deposit is held by Chalco Australia Pty Ltd (Chalco) and forms part of the world-class Weipa bauxite province, Cape York Peninsula, Queensland, Australia. The bauxite is predominantly pisolitic with an upper boehmite-rich zone and lower gibbsite-rich zone. The bauxite consists of both in situ and reworked domains, is overlain by a thin soil horizon and has kaolinite clay as a transitional base. A portable infrared mineral analyser (PIMA) was utilised on site, in addition to elemental assay, on each drill sample to determine the mineralogy, in particular levels of boehmite, gibbsite, kaolinite and reactive silica. As part of the scope of work, a field program was undertaken using large diameter Boart Longyear sonic drilling to acquire detailed density measurements across the deposit to allow compliance with Joint Ore Reserves Committee (JORC) reporting requirements. Interpretation of the stratigraphy was conducted on a hole by hole basis with definition of the zone layering based on stratigraphy, geochemistry and mineralogy. The zone boundaries were then modelled as 3D surfaces and used to constrain a block model. The block model estimation used the ordinary kriging method, with the estimation done in unfolded space and then refolded, therefore maintaining the zones irrespective of thickness or orientation. The unfolding process converts the real-world positions for both blocks and informing samples to a scaled position relative to the roof and floor of each zone. Analysis of the data and variography were also undertaken in unfolded space. The x and y dimensions are unchanged, but the z dimension is a relative position. The effect of the unfolding and limits on number of samples per hole is to æpushÆ the informing sample search sideways but within the stratification, rather than vertically. This honours the strong vertical zonation within the bauxite profile. The JORC Code requires that the stated resource must have æreasonable prospects for economic extractionÆ. This is a qualitative rather than quantitative definition. A number of selection criteria to define a resource roof and floor were developed in consultation with the project engineers and owners to meet these criteria. The vertical selection of material to include in the resource highlights the variation in the development (and destruction) of the bauxite profile from area to area within the deposit.

Jan 1, 2009

The carbon-in-pulp (CIP) process is now well established in the South African gold industry, with a total of over I million metric tons of material being treated each month in six large plants. This tonnage is derived from ground ore, from filtered pulp, from calcine, and from reclaimed sand-tailings dumps. With this new process and the new large plants, those concerned with CIP are experiencing a learning process, since each new plant presents a different set of problems to be overcome. The knowledge and experience gained from these plants is being shared, and will be of benefit in the design and operation of new plants. The CIP process can be subdivided into the following unit operations: prescreening at a fine size, adsorption, acid-washing and elution, reactivation, and electrowinning. Results concerning each of these unit operations, which were obtained from pilot plants and from large-scale CIP plants in South Africa, are presented. The latest developments in each of these areas is summarized. Tables that are included as an appendix contain some information concerning the equipment in these new CIP plants plus operating results from some plants.

Jan 1, 1982

With the advent of the mini computer and the relational database project management has experienced a new lease of life. The project manager no longer has to wait days for his reports, and he doesn't have to thumb through a foot of four part stationery to find that one line of information. The new techniques bring characteristics that are music to the ear of the project team giving them a better chance of bringing the projects in on time and within budget.

Jan 1, 1983

By Manlapig E. V

ABSTRACT- I Results are given for a series of tests in which a 300 mm pilot-scale Jameson cell has been used in copper recleaner flotation, and for the flotation of a lead rougher feed. the results indicate that the production rate of solids, at the same superficial air velocity Jg, is higher than in conventional columns. Thus in the copper recleaner application, the pulling rate reached 14 gm/cm2/min compared with between two and three for an operating column, while in the lead cleaner application the comparable figures were 12 - 14 gm/cm2/min for the Jameson cell vs 8 - 9 gm/cm2/min for a test column. A froth crowder was used to increase the air superficial velocity Jg in the Jameson cell in the copper recleaner, while holding the collection mechanism and pulp feed rates constant. The recovery increased from 50 per cent to over 90 per cent, suggesting that recovery is controlled mainly by the froth conditions, rather than the particle-bubble interactions in the Downcomer.

Jan 1, 1991

By Mahony BK

This paper discusses the major infrastructure elements required to support a typical Australian mining development. Infrastructure elements are grouped into four major types, urban planning, transportation, power and communications and water supply. The design criteria applying to individual elements within these groups are briefly discussed as well as order of magnitude cost estimates. The use of simulation models to test the capacity of existing rail networks, as well as novel sources of energy generation, are also described.

Jan 1, 1983

By Sheer T. J, Van Rensburg J P

The primary objective of this research was to address the demands imposed on self- contained self-rescuer (SCSR) performance dur- ing simulated escapes. The results clearly indicate that SCSR performance, apart from the inherent technological features, is a function primarily of the physical and anthro- pometric features of the wearer, and of the particular nature of the escape route. These factors consequently play a major role in the planning of any escape strategy, which may vary from mine to mine. It is therefore concluded that each mine would have to formulate its own escape strategy which in turn would depend on the choice of SCSR, and the particular escape Route.

Jan 1, 1988

Financial markets are subject to constant change and project finance, as a product within these markets, adapts and will continue to adapt with those changes. A meaningful discussion of these adaptations requires an understanding of differences between non-, limited and full recourse project finance. The reasons sponsors seek and lenders provide project finance are also pertinent in this context. Arranging a project, financing package can be a canplex and time consuming task. An important first step is choosing the right advisor for the assignment and then structuring and tailoring the financing before approaching prospective lenders. The last thirty years has seen changes in the needs of sponsors and the ability of lenders to meet them. These shifts in preference may well be a guide to the future. Several major project financings successfully canpleted in Australia in the last few years and more recent examples are broadly discussed. Project finance will be keenly sought in the future and the form and nature it takes will continue to vary.

Jan 1, 1983

By Buttrose RB

The Pine Creek gold mining development consists of a 1000000 tonne/yr open cut mine, a carbon-in-pulp processing plant and support facilities. The operation is located at Pine Creek, 230 km south of Darwin in the Northern Territory. The mine was officially opened in late October 1985, having been designed and constructed in less than twelve months, despite front end expenditure constraints and unseasonal cyclonic rains shortly after commencement of site activity. Non-traditional methods and attitudes were required to be adopted by both Engineer and Owner to successfully bring the project from preliminary design through construction and commissioning in a minimum time. Those areas which differ from the more traditional approaches to Project Management are examined together with a review of the advantages and penalties of these methods.

Jan 1, 1986

The history of the down draught Dwight- Lloyd system of iron ore sintering in Australia is developed. Characterisation of the broad process is given for one plant, and regional divergences from the reference practice are noted and briefly analysed. The subject of the development of high basicity sinters is introduced, and regional differences in approach and results are Examined.

Jan 1, 1972

Universal Resources Ltd has acquired a large portfolio of high quality exploration projects in two of Australia's most prospective regions for base and precious metal exploration: the Mt Isa Inlier (the Mt Isa-Cloncurry area) of North West Queensland, and the southern Lachlan Fold Belt in New South Wales. Drilling techniques commonly employed by the company for mineral exploration include diamond core drilling, air core drilling, reverse circulation (RC) drilling, and rotary air blast (RAB) drilling. Using examples from these two regions, each drilling technique is briefly described and compared, with particular reference to the specific advantages and disadvantages of each method for: sampling size, sample representivity, recovery, integrity and potential contamination. The applicability and implications of the different drilling techniques described for subsequent mineralogical and metallurgical evaluation work are discussed.

Mar 1, 2010

By N K. DavT, A Coggan

The performance of in situ, shallow water covers in controlling acid generation was evaluated at four recently decommissioned pyritic uranium tailings sites at Elliot Lake, Ontario, Canada. The tailings are acid generating, having a pyrite content of approximately five to ten per cent and a very low to non-existent alkaline buffering capacity. Adverse market conditions led to the closure of all operating uranium mines in the early- to mid-1990s, followed by rehabilitation and decommissioning of mine and waste management facilities. In order to control acidic drainage, all new and active tailings areas at Denison, Quirke, Panel, Spanish-American and Stanleigh mine sites were re-engineered to provide in situ submersion of these tailings under shallow water covers. The tailings impoundment dams were upgraded and reinforced or in some cases reconstructed, to minimise seepages and provide a minimum 1 m depth of water cover. With the exception of Stanleigh mine, which was closed in 1996 and rehabilitated during the late-1990s, the water covered Tailings Management Areas (TMAs) at other sites have been in operation for a period of six to nine years. The surface water quality at these sites is maintained at near neutral pH conditions by periodic addition of lime slurry to the established water covers. Additional treatment of effluent is provided as required to meet the discharge water quality standards. The performance of the established water covers at the sites was evaluated by analysing the annual equivalent limestone consumption data. The results were compared with the performance of an older, decommissioned Nordic TMA, which was rehabilitated using revegetation techniques. The water covers at these sites are performing as designed and acid generation has been reduced to low levels. Based on the total amount of yearly equivalent limestone required to maintain water quality in the water cover and at the effluent treatment plant, it is concluded that acid generation rate at the Denison TMA has reduced to less than 0.15 per cent of its pre-water cover conditions during normal operation and rehabilitation periods. In comparison to the revegetated Nordic TMA, the acid generation rates at Denison and Panel TMAs have decreased to less than 1.6 per cent of that at the Nordic TMA. The acid generation rate at the Quirke TMA was comparable or only slightly lower than that at the Nordic TMA because of its unique terraced cell configuration, having tailings in five hydraulically interconnected cells at different elevations. Historic acidity and oxidation reaction products, accumulated during normal operating and pre-water cover periods, are flushing from upstream locations to downstream cells, thus requiring much higher equivalent limestone additions for acid neutralisation and effluent treatment.

Jan 1, 2003

Fluid circulation occurs in oceanic crust of all ages, at the seafloor spreading axis, on mid-ocean ridge flanks, in the ocean basins, and in subduction zones. In the first three settings the fluid originates as seawater. At the axis and on the ridge flanks, the circulating seawater produces a major chemical exchange between the oceans and the crust. Based on heat budget constraints, between 10 and 40% of the river flux of Mg can be taken up during high-temperature alteration of the basaltic crust along the mid-ocean ridge axis. Most of the hydrothermal -heat loss, however, occurs on the mid-ocean ridge flanks, where the temperatures are lower and the seawater flux correspondingly larger. The estimated heat loss on the flanks is so large that upwelling must occur over a large fraction (5-30%) of the seafloor less than 65 Ma in age, at seepage velocities on the order of 10 to 100 cm/yr. The circulating seawater need lose less than 1 to 2% of its Mg content in order to solve the Mg mass balance for the oceans. Fluids in subduction zones are commonly less saline than seawater and are rich in methane and other light hydrocarbons. These fluids may originate by dewatering of the downgoing slab. If so, they may close the geochemical cycle of H2O that began with hydration of the basaltic crust at the ridge axis.

Jan 1, 1990

By A Purvee, M F. Lee, L J. Mollison

Oyu Tolgoi is a large Cu-Au porphyry deposit in the south Gobi desert, Mongolia. The first of several deep, large-diameter, concrete-lined shafts, Shaft 1, is nearing completion. It will have a finished depth of 1380 m at a diameter of 6.7 m. These shafts will provide access to and hoisting capacity for block caving of deep underground ore. Geotechnical site investigations, and associated predictions of stability and ground support requirements, are compared against actual construction performance. Routine mapping is essential, along with checks against predictions and informing the contractor of ground conditions and variances.Advance rates are compared against predicted rock mass quality. A reasonable correlation exists between Qwall and advance rate. Overbreak and concrete liner thickness is related to the blockiness quotient, RQD/Jn.A ætool-bagÆ of just a few support elements (chain-link mesh, fibrecrete and 2.4 m long friction anchors and resin grouted re-bar bolts) was able to cope with the ground conditions encountered. QA/QC procedures are essential from the factory, through site storage to installation.

Jan 1, 2008

By Johns AS

Comissioning of a new residue disposal tcluding upgraded classification for none backfill preparation, new variable speed pumps and a new residue dam took place in 1¦76. The system is described.

Jan 1, 1978

By Smith I. W

Australia has, and faces, a growing problem with regard to the ability to meet the demand for liquid fuels from indigenous petroleum resources. The position for natural gas is better but there is no room for complacency. Since the coal resources are relatively extensive, interest in the prospect of producing liquid fuels from coal is in- creasing. The approaches to the production of gaseous and liquid fuels are briefly reviewed and the present status of coal conversion technology is discussed. Many problems remain to be solved and it is estimated (in the USA) that another 8-10 years will be required before any of the processes for liquid fuel production are considered sufficiently efficient and viable to go to a demonstration plant. Coals represent complex feedstocks and the effects of variations in coal properties on oil-from-coal processes are not fully understood. The thermal efficiencies of various coal conversion processes are considered in relation to their impact on coal requirements. The production of Australia's present requirement for liquid fuels by the only commercial process in operation would require a four-fold expansion in the local consumption of coal. Any assessment of the suitability of oil-from-coal processes currently under development overseas for Austra- lian coals and requirements must take heed of the differences in coal properties and motivation. The economic via- bility of processes for producing oil from coal will continue to be uncertain because of the large difference between the World price for crude oil and the actual production cost.

Jan 1, 1975

By H Plewes, A Bur, L Murray, J Pottie

Water recovery from tailings for reuse in mineral processing is essential to operation of mines in the Atacama Desert of Chile. With annual rainfall of 5 mm, the prudent and efficient use of available water resources is a major issue for the Escondida Mine and other mines in the area. The Escondida Mine is located at an altitude of 3100 m, in a very arid, seismically active part of the Atacama Desert of northern Chile. The site is located about 170 km from the coastal city of Antofagasta. From 1994 to 2002, tailings were discharged into the Hamburgo Tailings Facility, which comprises a series of æpaddiesÆ located near the open pit and mill. Because water in the region is only obtainable from groundwater sources, the paddy system incorporated a number of design features with the aim to maximise water recovery from the tailings. As part of the recent mill expansion to 237 500 metric tonnes per day, a new tailings facility, the Laguna Seca Tailings Facility, projected to be one of the largest tailings facilities in the world, was commissioned in 2002. Extensive studies were conducted for the design of the new facility to predict water recovery from the conventional wet disposal of tailings. The predictions were calibrated against the performance of the Hamburgo Tailings Facility and subsequently re-calibrated against actual performance during the first year of operation at the Laguna Seca Tailings Facility. Initial operation of the Laguna Seca Facility was marked by a coincidental change in tailings characteristics from design, which highlighted the need for thoroughly understanding tailings behaviour during deposition, and the parameters and deposition techniques that could enhance water recovery. Systems have been put in place to manage the tailings deposition and respond to changes in key parameters such that water recovery targets can be reliably achieved. This paper describes the background studies that were conducted to evaluate evaporation and tailings behaviour, summarises the water balance and then presents some observations from the commissioning and start-up of the facility.

Jan 1, 2003