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By McCarthy J

In both the U.S.A. and Canada regulations concerning the reporting on mineral resources and especially ore reserves have been established. The regulations are virtually identical for the two countries with the main exceptions being who is franchised to write the report and how the various reserve categories may be used in reports to the public. Both countries divide ore reserves into "proven", "probable" and "inferred" categories. "Proven" reserves are those for material for which tonnage is computed from dimensions revealed in outcrops, trenches, underground workings or drill holes and for which the grade is composed from the results of adequate sampling. "Probable" reserves are those which are less well defined than "proven" while "inferred" reserves are generally those which may exist through geological and geophysical interpretation. The AusIMM/AMIC draft guidelines as proposed for use in Australia define more rigidly the ore reserve categories into "proved" and "probable" terms, which can only be applied following a full and favourable analysis of economic, mining, metallurgical, marketing and sociopolitical factors. If the ore reserves are not supported by this analysis they are placed into a "resource" category. Proper application of this proposed Australian model could prove useful when dealing with grass-root prospects or mining properties in the pre-feasibility stage. Combined with competent reporting, use of the proposed guidelines should ensure standardised and more verifiable analysis/valuation of a company's mineral assets.

Jan 1, 1987

By J H. Heo, J H. Park, M J. Lee

In this paper, the challenging points regarding the high temperature physical chemistry of slags to achieve the improved and stable electric arc furnace (EAF) or electric smelting furnace (ESF) technology on the way to green steel will be reviewed, and the recent experimental and modelling research will be discussed. For example, the initial melting phenomena of hot briquetted iron (HBI) and the slag formation behaviour was observed using a high-frequency induction furnace. Main component of gangue oxides in HBI was SiO2, Al2O3, and CaO in conjunction with unreduced iron oxide. To increase the dephosphorisation efficiency, the distribution ratio of phosphorus between metal and slag was calculated using FactSage™ software, version 8.2 (CRCT ThermFact, Inc., Montreal, Canada) and was compared to the measured results. The optimisation of slag chemistry is required not only for maximum dephosphorisation efficiency with good slag foamability but also for minimum slag volume with less refractory corrosion in EAF process. The slag chemistry is also one of key parameters affecting the operation efficiency in ESF in view of FeO reduction behaviour, viscosity, sulfide capacity, etc.

Jun 19, 2024

By A Smith

Rock masses usually exhibit scale dependent mechanical properties primarily due to presence of discontinuities and their inhomogeneous nature. One of the essential preconditions for selection of appropriate strength and deformation parameters of a rock mass in relation to tunnel design is assessment of the scale of the joint network relative to the scale of excavation. In tunnel design practice, scale effects are estimated indirectly using small-scale unconfined compressive strength (UCS) tests and rock mass classification based empirical correlations. Large-scale UCS tests have the benefit of direct assessment of anisotropic and scale dependent properties of a rock mass.This paper presents results of a large-scale UCS test on a jointed siltstone. A 450 mm diameter sample with inclined bedding planes was cored and tested in uniaxial compression until failure with load and displacement measurements. The aim of the test is to determine strength and deformation parameters and correlate them with results of small-scale UCS tests of the same sample. The relationships between the small-scale and large-scale rock mass parameters were validated against published correlations from the literature.

Mar 8, 2011

By Shugen T

Due to the increase of passenger traffic, a new station is proposed which is about 6.8km from south station. An underground connection line is under feasibility study for connecting these two stations in order to avoid the in- terference with surface traffic. In this paper the traffic condi- tion and the geological formation along the planned route will be described and analysed. Different methods of con struction have been proposed and dis- cussed such as shield method, slurry wall method etc. In this paper compari- sons are made among these methods and advantages and disadvantages given. The authors proposal to construct this connection line by NATM raise wide

Jan 1, 1987

A new plant for grinding limestone was built at the Risdon Works of the Electrolytic Zinc Company of Australasia Limited to meet increasing process demands expected to reach 150 tonne/day of ground limestone. Plant specifications included open- circuit wet grinding, a single ball mill, a feed sizing of minus 6 Tyler mesh, a product sizing of 100 per cent minus 200 and 95 per cent minus 325 Tyler mesh and for the plant to be unmanned during normal running. Main features of plant and equipment are described; grinding performances given, as well as operating experience since commission- ing of the plant in March, 1976.

Jan 1, 1977

The Jurassic Walloon Coal Measures crop out over much of the Moreton Basin and contain numerous thin, banded coal seams which have been mined at various locations since the 1870s. Historically most mining has been by underground methods. Increased exploration during the 1970s and 1980s has led to the delineation of significant open cut coal resources and to the development of the Oakleigh, Jeebropillly and Ebenezer open cut coal mines in the Rosewood-Walloon area. Over 2 170 million tonnes in-situ of shallow, high volatile bituminous coal with a mean maximum vitrinite reflectance of between 0.5 and 0.6 have been proven in the Basin.

Jan 1, 1991

By Ryan CG, Ramsden AR, Sie SH, French DH, Griffin WL

Proton microprobe and electron microprobe analysis are being used in combination for in situ determination of the trace element contents of oxide, sulphide and silicate minerals in a sample of the Merensky Reef. Initial results indicate that chromites contain only Ni, Zn, Ga, Zr ar d Nb. Platinum-group elements, if present, are at concentrations less than 2 to 6ppm. Ru, Rh and Pd are the only platinum group elements to be consistently detected in the sulphides. PentLindite is the most important host for these elements with the concentration of these elements being dependant upon the mineral association in which it occurs

Jan 1, 1989

By C J. Noack, P B. Ganza

The concept of large trucks underground has been around for some time. While the road train concept is gaining momentum, there are underground mining applications where these trucks have not been suitable. Unfortunately few of the ægreenfieldsÆ projects that are most suited to the road train concept have come æon lineÆ since the underground road train was first introduced to Australia in 2001 so that the trucks have generally been adapted to existing operations. As at December 2004, there were 17 road trains operating underground in Australia, one being rebuilt and one under construction. This paper addresses the necessity for the mining industry to have an integrated ore transport system that starts at the underground load haul dump unit (LHD) in the stope production area and finishes at the crusher feed at the processing plant. Chute and orepass designs are investigated, as well as feeders to determine the best load and haul system for large-scale trucking. The paper also discusses potential developments in the large truck scene. The paper highlights the cost and productivity gains by introducing large trucks and associated integrated ore transport systems underground. While 400 vertical metres was seen as the limit of vertical hauling in the 1970s, one kilometre is a common discussion point for trucking limits today. In real terms the cost of underground trucking (including ownership costs) has decreased from $1.50 - $2.00/t.km in the mid-1990s to $1.00 - $1.20/t.km at present.

Jan 1, 2005

By E J. Coyle, L A. Millington

Tailings storage facilities are geotechnically complicated structures that develop heterogeneous strength profiles and varied porewater conditions. The monitoring of porewater pressures is one of the only direct measurements that can be performed to monitor the performance of a facility throughout its life and is of particular importance in upstream facilities. Foundation underdrainage, continuous and staged tailings deposition, climate inputs (rain, snow, humidity, evaporation, etc), and stratified tailings permeabilities can complicate this critical measurement that introduces uncertainty to stability analyses. These difficult conditions manifest in vibrating wire piezometer measurements as very low or negative pressure readings, both of which are within the instrument’s range of accuracy. However, the data can be difficult to interpret, and a range of interpretations are adopted from optimistic low phreatic surfaces to conservative fully saturated tailings. Where tailings are potentially liquefiable, these very low readings introduce further uncertainty regarding the pore space saturation ratio and liquefaction potential above the estimated phreatic surface. This area of uncertainty is the vadose zone, and its affect on tailings behaviour is not well understood. The two facilities analysed in this paper are upstream, raised embankments with tailings classified as clayey, sandy silt that have been found to be potentially liquefiable. The vibrating wire piezometers (VWP) at both sites show very low or negative readings when they are initially installed near the surface and then go through cycles of re-saturation and de-saturation. Eventually the readings settle as the VWPs are buried deeper within the tailings. The instrumented sections within the tailings column do not show consistent readings that would be indicative of a hydrostatic phreatic surface at either site. Rather, they are highly variable and can be interpreted as either representing a high phreatic surface within the tailings or as a ‘perched’ phreatic zone within the tailings layers. How the VWP data is interpreted has a significant impact on how the facilities are raised and operated. The design outcome for Site 1, which adopts a lower phreatic surface, results in an embankment that meets factor of safety (FoS) requirements under residual strength conditions without any buttressing. Conversely, a conservative (high) phreatic surface has been adopted for Site 2 and has resulted in the facility requiring a significant buttress to meet FoS under residual strength conditions.

Jul 1, 2021

By M A. Vinokurova, V M. Mullov

Due to treatment of refractory carbonaceous low-grade gold ores a new technology providing improved precious metal recovery is required. For this reason, a technology including gravity, flotation, recleaning of the flotation concentrate, intensive cyanidation of the gravity concentrate and carbon in leach (CIL)-process for intensive cyanidation tailings and the recleaned concentrate was developed. The proposed technology allows to decrease preg-robbing activities of concentrates treated by subsequent cyanidation. Total gold recovery by the proposed technology from the ore with a head grade of 0.8 g/t was 83.9 per cent. The gold loading onto the activated carbon from CIL process was 6.500 g/t.

Jan 1, 2007

Mining of copper ore is still the most important business in Chile. In order to mine ore with a copper content of less than one percent at Minera Los Pelambres in an economical way, opencast mining is mandatory. Due to the prevalence of avalanches at the mine, the concentrator was located in a stable area, some distance from the mine. As a consequence, the material has to be transported between mine and concentrator by conveyor. A downhill conveyor system has been implemented for more than ten years as the most suitable and most economical ore transport alternative. Due to the length (12.6 km) and inclination (1300 m drop) of the conveyor system, the stresses in the steel cord belt are the dominant design criterion, resulting in a belt quality of ST 7800. Additional dynamic belt stresses during transient operating conditions are avoided by the installation of high capacity adjustable frequency drives. The rating of a single drive unit is 2500 kW. During ten years of operation, several capacity increases have been implemented, from an initial 5800 t/h up to the current capacity of 9900 t/h. This presentation describes the engineering challenges of the implementation of the world's strongest belt conveyor system. Capacity increase measures like the development of new control and breaking strategy, proved by dynamic simulation of belt forces and belt speed scenarios are explained. During this long-term partnership of RWE Power International, the former Rheinbraun Engineering, with Minera Los Pelambres, RWE has been engaged continuously for development work, safety checks, expert opinions and maintenance audits, and giving new impulse to conveyor technology.

May 1, 2010

The need for a carefully prepared set of special conditions, to be used with general conditions of contract or, alternatively, a purpose written contract for adoption in tunnelling work in Australia is discussed. Recent decisions on the proprietor's liability for tender information and arbitrator's power to award interest are examined. A new clause for inclusion in contracts specifically giving arbitrators power to award interest is suggested. Similarly, a new clause covering delays due to environmental disputes is suggested, particularly for marine outfall tunnels. An alternative method for the settlement of disputes by negotiation is suggested for consideration and contracts and contract administration are discussed as the possible weak point in the construction process. At the conference it is intended to present a method or process to be used in contract administration which should reduce disputes, result in a better quality and efficiency of administration and ultimately in better contracts'.

Jan 1, 1981

It is indeed a pleasure to be here this morning to open the 4th Mill Operators' Conference. It is no mean feat to organise such an event and I would like to congratulate the committee for the work that they have done. I am sure that the Conference will be an outstanding success. I welcome overseas visitors and hope that they gain and share in the openness of this Conference. There is personal satisfaction for me to speak to you as a mining engineer addressing a large group of metallurgists and mill operators. I would have thought that it would be impossible for a mere mining engineer to inform a metallurgist of anything. I will desist from using such derogatory terms as "xanthate munchers", "bubble makers" and "glorified mathematicians". Terms of endearment as these may not be seen with much equanimity. Such is the warm association that the two professions have enjoyed over the years. The economic climate that we at present face is a major problem to all of us. I wonder how many people here come from mining operations that are in trouble financially or that are cutting back in one form or another. This is the recession that we needed to have. When the world's greatest treasurer can tell us that then we truly have a lot to fear. The present downturn can be seen as a normal adjustment in the cycle of our business. Yet the world does not experience such severe adjustments as frequently as we experience ours. The root cause for the regular adjustments can be placed at the feet of inflation. Until the politicians of this country of ours can come to grips with inflation, we will continue to experience downturns on a 5 to 7 year cycle. This, in my opinion, is the basic reason why we appear to experience more downturns than the rest of the world. We simply price ourselves out of the market. This takes about 5 to 7 years to be highlighted and then we need to make adjustments. However, this recession is worldwide. The adjustments usually take the form of redundancies, retrenchments and early retirements. What is the solution?

Jan 1, 1991

By P Murthy, Z Guan, P Townson

In this paper, we introduce a methodology to optimise mining equipment operation in terms of the conflicting concerns of productivity and availability. We also introduce the concept of damage points and equipment dutymeters. These provide the mine management with tools to monitor the success of such optimisation. Since we have quoted the results of an on-going Australian Coal Association Research Program (ACARP) project, the apparent focus of this article is on draglines. However, the concept is equally applicable to other equipment. Mining is the type of business that requires a large investment in capital infrastructure and equipment to produce a product that is sold at a relatively low unit cost. In such a business, the key to competitiveness lies in achieving the full realisation of capital investment ie sustained production at high levels. Some of the concepts outlined in this paper are essential components of this picture.

Jan 1, 2000

By Young JA, Rogers G, Bannister S, Edwards SA

Many coal mine operators have responded to economic pressures by massive investment in machinery to reduce unit costs. To sustain the increased production which must justify the expenditure it is essential to know the resource in great detail months or even years in advance of its extraction. The required detail includes variations in composition and any lateral disruptions to the seam which night affect production. As Wilson (1985) has pointed out, a day's production loss can mean half a million dollars income forgone, and an unexpected major fault can mean a shutdown of weeks. Traditionally, seams were probed by surface drilling on (typically) 250 or 500m centres, and by horizontal drilling from sithin'the seam. Core was analysed chemically. The new generation machinery cannot tolerate the risk attendant on such widely spaced sampling, but the costs of much closer sampling rapidly become prohibitive.

Jan 1, 1987

The activiltion of sphalerite with electrolytically generated copper ions from a copper electrode instead of the usual practice of the addition of copper sulphate was studied in the laboratory. A large surface area of copper was provided by lining three sides of a bench flotation cell with copper sheeting. The lining was connected to the positive terminal of a low voltage d.c. source, and the cell impeller to the negative terminal.Sphalerite was effectively activated by this arrangement and was subsequently floated using xanthate as the collector.Flotation results comparable to those obtained with 1 lb/ton CuS04.5H20 (0,255 lb/ton copper) were obtained using 0·1062 lb/ton of electrolytic copper and 0·488 kWh of electrical energy. The wastage of copper due to the formation of insoluble precipitates was found to be dependent on the length of time the current was passed. Maximum current was passed for the shortest time to minimize wastage.

Jan 1, 1973

By A Ruotsalainen

Mining industry sees a comprehensive future in optimisation and process control. High resource utilisation is a starting platform when lower operational costs with higher rate of return are the target. Simulation is quickly penetrating the mining industry as a planning tool. A discrete event simulation helps to visualise the reality of a mine and the various mining processes, which typically include a fair degree of complexity. What-if scenarios can help to determine the impact of occurring changes to production. Understanding of critical points in the layout and resource allocation at an early stage can help to optimise the material flow. The obtained information may then be used as proposal or confirmation of the system applicability and economy. Simulation is a way to fine-tune and optimise the resources within. It helps to predict system sensitivity to various aspects. Although simulation today is used typically in a feasibility stage, there is an opportunity to continue using simulation for further process enhancement. In the future simulation will without doubt be used increasingly as a dynamic simulation and continuous improvement tool. This paper discusses the use of OptimineÖ simulation tool in resource optimisation. Some examples describe the way the tool operates and how it helps to view the technology, mine layout and operational data.

Jan 1, 2003

 Increasing concern about the impact of alluvial mining discharges on the water quality of some West Coast rivers lead to a joint West Coast Gold Miners Associate, Trade and Industry funded study by Water Technology (NZ) Ltd. The objective of the study was to assess the treatability of West Coast alluvial gold mining discharges and to develop simple treatment systems which could be effectively adapted to a variety of sites in the region.   The approach was to apply standard water treatment techniques to field situations using low cost technology. Initially the various types of alluvial gold mining operations were identified then after preliminary site investigations and laboratory studies were carried out, site pilot plants were set up. The results of the trials particularly those using chemical aids were encouraging and it was found that chemical aid performance was largely dependent on the degree of mixing at and downstream of the chemical addition point. Design alterations to settling pond configurations in conjunction with optimised chemical addition yielded dramatic results in the form of reduced effluent turbidities.   A generalised approach to effluent treatment was developed and some of the specific 'mix and match' requirements were identified for different types of sites. The general conclusion is that improved physical treatment combined with good plant management and operation and (where necessary) chemical treatment, will produce water of acceptable discharge quality.

Jan 1, 1989

In presenting the paper, Mr. Davey quoted subsequent work which yielded k, at miscibility gap composition, of about 50.We can confirm the authors' findings for k j 300 for nearly pure tin to k 2 about 50 (average 47) from our own experience and from repeat experiments on materials described by the authors, at 1150°C.During laboratory-scale trials we also found confirmation of the authors' view that it is more difficult to reach equilibrium from the high-iron (in slag) side than from the low-iron (high-tin) side. Working from the high-iron side tends to yield results that point to a high k, leading to optimistic values of iron/tin ratio in final slags. In practice the smelting of a tin concentrate, unless it is exceptionally low in tin and high in iron, must yield initially a tin-rich slag and therefore equilibrium can only be reached from the "tinny" side.

Jan 1, 1967

By M Angus, S Konopa, A Virisheff, S Crispin

A positive mill reconciliation at a mine is a double-edged-sword. Much back slapping happens. The bank and the board can’t get enough until the downside becomes apparent. Over a prolonged period, there becomes an issue with market perception and the potential for shareholders to be misinformed regarding the potential value of the project. In addition, there are impacts on mine scheduling, waste allocation (or lack thereof), government expectations, and the potential for misguided external assumptions regarding the ‘unexpected’ results. The PT Agincourt Resources Martabe Gold Mine has shown a significant under-call, in the order of 20% total gold metal, between the Mineral Resource (MR) estimates and Grade Control (GC) estimates since production commenced in 2012. Recently, the under-call has been reduced by incorporating the use of grade control drilling in the MR grade estimates. Despite recent improvements in reconciliation, drilling in 2017 at both Purnama and Barani open pits shows that infill reverse circulation (RC) drill holes often produce significantly higher grades than those predicted in the MR block model. CITATION: Angus, M, Virisheff, A, Konopa, S and Crispin, S, 2018. Martabe Gold Mine, Indonesia: a positive solution for positive reconciliation, in Proceedings Complex Orebodies Conference 2018, pp 76–78 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018