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It is recognised by the current JORC (1999) code that resource classification involves the interaction of numerous qualitative and quantitative criteria such as data quality, geological continuity and grade continuity. No prescribed criteria and rules will work for all situations or even between different ore types within the same deposit. Also these criteria and rules are sometimes applied without a clear understanding of their appropriateness, accuracy or correct implementation. For these reasons case studies are useful to evaluate and compare criteria commonly used to assist in resource classification. In this paper blasthole data from a selected area of Joffre Member hosted ore of the Brockman Iron Formation at the Mt Whaleback orebody are used as the basis of a case study for the above-mentioned purposes. Iron grade, in per cent, is interpolated from a blasthole dataset into a block model using ordinary kriging. Samples are then removed from this blasthole dataset to produce a random sample grid, a semi-random sample grid and a regular sample grid. Using nearest neighbour, inverse distance squared, ordinary kriging and sequential gaussian simulation, block iron grades are estimated using these three blasthole data subsets as inputs. This provides four groups of estimates with the ordinary kriging estimate based on the complete blasthole dataset being considered to represent the true estimate of iron grades. Also generated during this process are estimates of the error for each block. These error estimates range from the simple, such as drill spacing, through to more advanced methodologies such as kriging efficiency and simulation. These estimates of grade and grade estimation error are then compared to the true estimate using graphs and statistics. In order of increasing accuracy the block grade estimation and simulation methods were nearest neighbour, inverse distance weighting, ordinary kriging and finally conditional simulation. The simulation in some instances doubled the accuracy of individual block grade estimates when compared to nearest neighbour and inverse distance weighting estimates. It was found that many methodologies for estimating the error of individual blocks performed equally well with only methods such as average drill hole spacing and classification by search ellipse pass number performing poorly. An approach on how to convert the abovementioned error estimates of individual blocks into a meaningful JORC classification is also discussed. Although advanced non-linear resource estimates are applicable, most iron ore mines are still using relatively straightforward methods. The use of blasthole data and some simple linear interpolation methods and simple linear based error estimates makes this study repeatable for most iron ore sites and their resource geologists. This style of investigation is recommended as a useful approach for the Competent Person to apply to their deposit and thus better select, implement and understand the criteria used for resource classification and provide more consistency and confidence in the resource classification process.

Jan 1, 2002

By Moxon NT, Torrace AC

The detonation pressure of an explosive is a function of its density and its velocity of detonation (VOD) and relates directly to the degree and manner in which the explosive loads the surrounding rock. The suitabil- ity of an explosive to any particular situation is determined not so much by the total energy released but more by the rate at which it is released. As the science of rock blasting advances it is becoming economically more important to quantify explosive performance, particularly with respect to quality control and fragmentation. As part of a major explosive user, BHP Central Research Laboratories have developed a number of tech- niques to determine the detonation characteristics of explosives. These include a method of continuous velocity of detonation measurement based on the SLIFER principle. This not only enables the VOD of the explo- sive to be determined, but also has the versatility to allow factors such as under priming, slow run up, the effect of water, variable energy load- ing and the velocity of the shock wave in the stemming to be assessed. Multi point VOD systems have also been developed for more routine appli- cations. With a minor modification they can be used to determine the absolute delay of detonators accurately and economically. Direct deto- nation pressure measurement methods have also been developed based on piezoresistive techniques. Future developments include the incorpo- ration of all the above techniques into a single, portable package, allow- ing easy use on the mine site.

Jan 1, 1988

By T C. Souza Pinto, M Safari, F S. Hoseinian, D Deglon, L Leal Filhoc

In this study, the effect of hydrodynamic parameters on the iron ore reverse was investigated in a mechanical flotation cell. The work carries out using the case study of Iron ore from Vale in Brazil. The influence of hydrodynamic factors such as froth height, impeller speed, superficial gas velocity and solids percentage were evaluated on the quartz flotation. The results showed that the hydrodynamic conditions have a great effect on the flotation performance, especially on the fine and coarse quartz. The size-by-size analysis of the froth products showed that froth height, impeller speed, superficial gas velocity and solids percentage have a significant effect on true flotation quartz particles. The increase in the froth height decreased the recovery of quartz particles. The increase in the impeller speed increases the recovery of quartz particles to an optimum. The increase in the superficial gas velocity improved the flotation of coarse quartz particles. The increase in the solids percentage increases the recovery of quartz particles.

Sep 18, 2023

Exploration for economic nickel sulphide mineralisation has often been directed by rationalisations based on poorly understood genetic models. Among those that have enjoyed popularity over the past decade are the "layered gabbro" model and the "basal ultramafic" or Kambalda model. The new discoveries in the Mt Keith-Agnew area could well become a model for future nickel search. Exploration based on even the crudest state- ment of the Kambalda model - prospect the basal contact of Archaean ultramafic complexes for gossanous expressions of sulphide mineralisa- tion - has met with remarkable success. Refine- ments to this model, besides satisfying the geology of any particular deposit, have the major virtue that many of the genetic options - magmatic segregation, hydrothermal transport, sulphurisation, replacement sedimentary, structural control, etc. - are still open. Recent descriptions of highly magnesian silicate melts associated with the ultramafic rocks, do however, place some constraints on the formation of these deposits. Further evidence, from experimental studies on sulphide-silicate and sulphide-oxide phase relationships, and nickel-iron exchange in pyrrhotite, is taken with descriptions of sulphide nickel occurrences in Western Australia to examine genetic models for existing ore bodies.

Jan 1, 1972

Exploring for deep shallow dipping orebodies can be very expensive and very difficult. Surface exploration is often not an option and obtaining the best location for underground drilling can cause production delays if drilling is carried out from development headings. The Otter/Juan mine has been in production for approximately 34 years. All of the production is now sourced from more than 1000 metres below the surface from an area known as the Edwards Lode. The orebody is shallow dipping and open at depth. Exploration drilling has been performed from decline stockpiles and from hangingwall drill drives. Drilling from footwall positions (eg decline stockpiles) into shallow dipping orebodies can often produce intersections which are unusually thick thus leading to optimistic resource figures. The decision to develop a dedicated hangingwall drilling position can vastly improve the quality of the data used to generate an orebody model. In 1997 a new extension to the Edwards Lode was discovered and named the æFÆ surface. In 1999 a resource calculation was performed using data obtained from drilling that was carried out from decline stockpiles. In 2002 a dedicated drill drive was developed into the hangingwall of the æFÆ surface to obtain better data to verify the previous resource calculation. For this case study obtaining more representative data reduced the resource estimate by 66 per cent. This information was obtained early enough to allow for alteration to the mine plan and without loss of capital.

Jan 1, 2003

The state-owned Swedish company LKAB is one of the world's largest producers of iron ore. LKAB mines the greater part of its ore underground, and very high efficiency is vital if it is to compete successfully with open pit mines. Consequently, computers and OR are essential parts of the company's operations. This paper gives some examples of success- ful computer and OR applications at LKAB, coupled with some remarks on the costs and benefits of OR.

Jan 1, 1977

The transportable moisture limit of a mineral concentrate (TML) is of great importance in the shipping of that material from Australian ports. Each year Australian mining companies incur substantial costs as a consequence of delaying shipments and/or multi-handling concentrates so as to comply with transportable moisture limits. Despite this there is a general lack of in-depth knowledge concerning factors that influence the parameter. Eight major Australian mining companies supplied sizing, specific gravity and TML data for their concentrates. Zinc, lead, copper and bulk concentrates were represented in their data. Estimated surface areas of the concentrates, as calculated from their normalised sizing data, correlated strongly with the reported transportable moisture limits. This high correlation prevailed in spite of the acknowledged limitations associated with the use of multi-sourced data and the adoption of simplistic approaches in the normalisation of sizing data and the estimation of surface area. Based on the broad range of concentrates studied, concentrate sizing data were concluded to offer potential as an alternative means of reliably estimating transportable moisture limits.

Jan 1, 1993

By J Col, D La Rosa, W Valery, A Jankovic

Metso Minerals Process Technology Asia-Pacific and South America (MMPT) has been working with operations around the world to increase their efficiency through æMine-to-MillÆ or Process Integration and Optimisation (PIO) projects. These projects have delivered significant improvements in mine efficiency, mill throughput and reduced operating costs at mines around the world. The MMPT methodology involves rock characterisation, site auditing, data collection, modelling/simulation and implementation of integrated operating and control strategies on site. This results in significant benefits to the operations û for example, 5 to 20 per cent increases in concentrator throughput have been measured. MMPTÆs rock characterisation utilises simple and inexpensive measurements that can be performed by trained site personnel. The advantage of these measurements is that a large amount of data can be collected in a very short timeframe, as the samples do not require shipping to an outside laboratory. Typically, a PIO project starts with a site visit to perform blasting and process audits, collect high quality data including measurements of run-of-mine fragmentation and survey data around all crushing and grinding circuits. These measurements are combined with rock characterisation and the definition of strength and structure domains to model the complete production chain. Site-specific models of the blast fragmentation, crushing, grinding and flotation processes can then be developed. This proven methodology has applications ranging from greenfield projects to long-standing operations with AG/SAG or conventional grinding circuits. Process improvements can be higher mining productivity, higher mill throughput, decreased overall operating costs and higher flotation or leach recovery. This paper discusses a recent application of PIO conducted at a large open pit operation in South America and emphasises the potential that every operation has to ædo more with what they haveÆ.

Jan 1, 2007

By L Faulkner

The Tarnagulla Gold Project in Central Victoria, Australia, was developed and operated by Reef Mining NL between 1994 and early 2000, producing 53 000 ounces of gold from the Nick OÆTime Shoot, a single narrow vein shoot structure within part of the larger Poverty Reef, with a strike length ranging from 30 m to 60 m. The ore shoot was developed over a vertical interval of 190 m, using a small cross-section decline and small, mechanised equipment. Various stoping methods were employed including mechanised cut-and-fill with a single boom jumbo, hand-held mining using airleg drills and rope scrapers, and small uphole retreat stopes using a line of sight remote operated LHD to recover a crown pillar. Experience during stoping showed that airleg drilling and rope scrapers gave much better dilution control than diesel equipment. Innovations included a low-cost hydraulic fill system. Due to the small scale of the deposit, the feasibility studies, planning and permitting for the mine were based on very limited drilling information; however, the mine was brought into production within two years of the discovery. While the mine made an operating profit, it failed to fully repay capital at the low gold price then prevailing. Applying the lessons learned from the operation to optimise the access and stoping method, the project is re-examined at todayÆs gold price and operating costs. Central Victoria has the potential to host many similar small deposits. The authors were respectively Non-Executive Director and Resident Manager for Reef Mining NL when the mine was operating.

Jan 1, 2008

By Glastonbury J. R

Commercial operation of the Sherritt Gordon process in Australia for the leaching of nickel sulphides has promoted an investi- gation of the factors which influence extraction kinetics. This portion of the investigation has been directed towards the physical and chemical nature of the concentrate and the physical evi- dence of the mode of extraction. Details of the particle size distribution, mineral composition and chemical composition are given. The dis- tribution of various minerals in different size fractions and magnetic fractions is discussed. An electron microprobe was used to determine the composition of individual grains in the concentrate. The solid residue from an ammonia oxi- dation leach was subjected to microphotograph- ic examination, X-ray diffraction analysis and scanning by an electron microprobe. Clear evidence was obtained for a shrinking core mode of kinetic extraction with an amorphous iron oxide product layer contrary to previous reports that the latter is pseudomorphic with the original mineral.

Jan 1, 1973

By Leahy GJ, Wright DJ, Player RI

The operation of a one tonne submerged combustion pilot plant for the recovery of copper from anode furnace and converter slags is described and the effects of variables discussed. Using coal as reductant, copper levels of anode furnace slag were lowered to 1% or less, with batch times of approximately 120 minutes. Fluxing with limestone was required to produce a fluid slag at temperatures of 1200 - 1300¦C. For converter slags, reduction to 0.5% Cu or less was achieved in batch times of 35 minutes. The chemistry of the pyrometallurg- ical recovery of copper is briefly reviewed in relation.to copper recovery methods.

Jan 1, 1978

By Hall C. E, Chrisholm J. M

Resource calculations for shear hosted deposits of any type are difficult regardless of which calculation technique is used. One of the main problems is the determination of the geometry of the mineralisation. Once this has been elucidated then the appropriate resource calculation methodology can be employed with a search distance and orientation that is relevant.

Jan 1, 1993

By D Smith, D Reid, D Bradshaw, C Brough

The Merensky Reef at Northam Platinum Mine in South Africa is characterised by a high degree of variability with respect to reef elevation (difficult to mine), as well as mineralogy and texture (difficult to process). Development along strike and down dip of multiple reef types has led to unpredictable run-of-mine characteristics that pose problems for the mineral processing circuit at Northam. Following mining terminology, Normal, Transitional (NP2) and Pothole (P2) Merensky reef types can be defined, and this geometallurgical study aims to characterise and understand the relationship between their mineralogical characteristics and laboratory scale batch flotation performance. The plagioclase-rich NP2 reef ore is the easiest ore to process in terms of capacity for high mill throughput as well as flotation performance. The lack of very fine-grained disseminated sulfide textures in the NP2 reef ore results in better liberation characteristics relative to the Normal and P2 reef types. Consequently, chalcopyrite, pentlandite and sulfide recoveries are highest for the NP2 reef ore. The lack of ferromagnesian minerals in the NP2 reef ore also results in the recovery of the least amount of floatable gangue during flotation tests. The Normal and P2 reef ores are similar to each other, with an orthopyroxene-rich mineralogy with associated alteration minerals. The P2 reef is also characterised by the highest sulfide content and degree of pentlandite liberation. Chalcopyrite, pentlandite and pyrrhotite liberation is only significantly increased by a change in grind for the Normal reef ore. The change in grind, however, only significantly affects pentlandite flotation performance and overall froth stability for the Normal reef ore. However, for all three ores, a small change in grind has a detrimental effect on pentlandite flotation performance.

Jan 1, 2008

By M Csar

The Nicolsons Find gold project is located 35 km southwest of Halls Creek in the east Kimberley. It was discovered in the late 1980s by John Nicolson and Stuart Skoglund, when high grade gold mineralisation within outcropping gossanous quartz reefs was found. The area has produced a modest 28 150 ounces of gold over two brief mining periods in 1996 and 2002 - 2003. Indicated and inferred resources as of September 2011 stand at 1 384 000 t at 5.58 g/t Au for 248 500 ounces of gold.The project is situated within the Halls Creek Orogen. Principal host units are metasediments and volcaniclastic sediments of the Koongie Park Formation. Minor mafic units are also recognised. Immediately east of these units, emplacement of the loadstone granite is believed to have provided the structural setting for the later gold mineralising event.Mineralisation is hosted within a broad, brittle-ductile arcuate shear zone about the western contact of the Loadstone granite. In the Nicolsons Find area, the shear zone strikes north-northeast and within the shear zone, gold is hosted in a series of narrow, quartz rich veins up to 200 m in strike length, plunging moderately to the north-northeast. To date, mineralisation has been drilled to a depth of 360 m below the surface. The veins are stepped or en-echelon in nature with low gold values towards the quartz vein limits where compression is inferred and higher grades present in the dilational body of the quartz veins. Gold is fine grained and can be present with or without associated sulfides. Sulfides are generally minor and consist mainly of arsenopyrite with traces of chalcopyrite, pyrite and sphalerite. Where present, sulfides are generally indicative of higher gold values.CITATION:Csar, M, 2012. NicolsonÆs Find gold project, East Kimberley, Western Australia, in Proceedings Narrow Vein Mining 2012 , pp 31-36 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 26, 2012

South Africa is the world's largest producer of gold. The survival of its gold mining industry is dependent, to a large extent, on the successful implementation of new mining technology which reduces the operating costs. Gold mines of the country have a record of a high operational cost per tonne of rock excavated. The geology of the gold-bearing rock, in addition to the mining depth and the gold recoverable grade, profoundly affect the profitability of the industry. Among the other mining operations, drilling and blasting take a fair share of the mining cost. It is therefore proper to implement a dynamic approach of technological review aimed at combating the escalation of mining costs. Over the years, the industry has moved away from labour intensive activities. Mechanised operations are introduced where possible. Management techniques are oriented more towards better utilisation of human resources and machinery so as to enhance productivity in the stopes. This paper addresses the issue with particular reference to blasting operations in the stopes of deep gold mines. It reviews the conventional drilling and blasting techniques. It outlines some innovative changes brought about in the course of recent years with the aim of optimising productivity and the stope efficiency in particular. It focusses on the peculiarities of the blasting technology in deep mines. It discusses the issue of interaction between the high stress fields underground and the blasting generated stresses on rock fragmentation, as well as their impact on the remaining excavations. It anticipates the concept of the new technology of selective blasting in stoping. Finally it puts forward the crucial role played by management of the human factor underground.

Jan 1, 1995

By Best R, Poulos H

This paper discusses the results of an Australian Coal Association Research Program project into the development of a routine analytical design method for roof support in underground mines. Simple design tools have been developed using a combination of elastic solutions, free body diagrams, and pile theory. An approach to the design of roof support in layered strata based on the ability of bolts to resist shear stresses is outlined. It is shown that pre-tensioning and angled installation are effective ways of increasing the effectiveness of bolts in such a situation. In highly stressed strata, macroscopic failure is predicted and a design based on the support of surcharged rock wedges is proposed. The methods are applicable to both coal and metalliferous mines.

Jan 1, 1995

By Paine G. G

The Red Dome Gold/Copper Mine is located approximately 15 km west of the township of Chillagoe which itself is approximately 220 km by road west of Cairns, Far North Queensland. The deposit, with other mines in the Mungana region, was worked from about 1901 to 1927. Exploration by Amoco Minerals Australia in the 1970s and early 1980s outlined a geological resource of 15 million tonnes. A mining reserve of 9.3 million tonnes was identified and originally developed by Elders Resources Limited. The mine commenced operations in March 1986 and was the first large-scale gold project in Australia to be developed solely on the heap leach process. The mine operated successfully as a gold heap leach operation until 1989 when new grinding, flotation and carbon-in-leach plant facilities were installed to process the non heap-leachable component of the orebody including the copper rich -ore. In March 1991, Red Dome Pty Ltd became a wholly owned subsidiary of Niugini Mining Limited. After six years of successful operation and having excavated a 200 in deep pit, it became evident in 1992 that unless more open cut reserves could be identified the operation was limited to six to nine months of high grade ore and a further 15 months of low grade stockpile material. A preliminary feasibility study was carried out to assess the viability of deepening the open cut. This indicated that from a technical and financial point of view it was possible to expand and deepen the open cut. This presented the daunting challenge of developing a 300 in deep, single access, open cut between a high chert ridge, a government railway line and a National Park. The meeting of this challenge is the subject of this paper.

Jan 1, 1994

The need to estimate the block size distribution of a jointed rock mass is of great importance in the design of blasting rounds to attain a pre- established fragmentation. Other Geomechanics topics, such as ,hydraulic behavior of rock-masses, as well as the determination of their strength properties, also require the accurate prediction of a rock-mass composition in terms of block size taking in due account the three dimensional interference of joints and other geologic discontinuities. In this paper, a method for computing the block size analysis of a jointed rock mass is described, using as input the common geologic data (dip and strike) of fracture planes existing in a rock bench prior to blasting.

Jan 1, 1977

By E Jak

A viscosity model has been developed for both completely liquid and heterogeneous, partly crystallised slags in the Al2O3-CaO-æFeOÆ-SiO2 system in equilibrium with metallic iron. The Urbain formalism has been modified to describe the viscosities of the liquid slag phase over the complete range of compositions and a wide range of temperatures. The Roscoe equation has been used to describe the effect of presence of solid suspension (slurry effect) on the viscosity. The parameters of the viscosity model were optimised to describe large experimental data set in the low-order subsystems, as well as in the multi-component system. The computer package FACT was used for prediction of the proportion of solids and the composition of the remaining liquid phase. The model provides a good description of the experimental data (over four thousand experimental points) in liquid phase, and liquid + solid mixtures, over the complete range of compositions and a wide range of temperatures. This model can now be used for viscosity predictions in industrial slag systems. An example of the application of the new model to slag cleaning and reduction smelting processes is given in this paper.

Jan 1, 2000

By Unver B

Longwall advance mining is still the predaninant system of coal extraction in the U.K., contribiiting to sane 70 % of underground coal production. Gate roadways providing access to a longwall advancing coal face are maintained adjacent to a rib pillar under high strata abutment pressures and the caving rock mass. It is very difficult to realistically model such access roadways using mathematical or numerical techniques and hence, predict roadway closure. For the past 15 years, a research group in Nottingham University has been engaged in the study of longwall gate roadway stability using observation methods. Gate roadway deformations have been measured in 224 gate roadways and a comprehensive data base has been established. The paper describes the statistical analysis of this database and presents sane. predictive equations which will enable a forecast of the gate roadway closure to he made. Further field work to validate these equations. is described together with an error analysis. The results are very promising and indicate that it is possible to predict gate roadway closure in the U.K. within practical limits of Accuracy.

Jan 1, 1986