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The paper highlights the conceptual developments in rock mechanics applied to quantify the effect of bolts in the stabilization of joints and yielding soft rocks. NOTATION Aa = stress change after excavation Eä EE, Eä = moduli of intact rock, single joint and jointed rock Eb = elastic modulus of the bolt k, = normal stiffness of joint Ab = cross section area of the bolt A, = area of influence per bolt ab = axial bolt stress e, = axial strain of the bolt eä e,, ej, = strains of intact rock, joint and jointed rock Ai = area of the joint ,r+ = shearing resistance of the bolt (at the joint) a = normal stress at the joint plane aäa3 = major and minor principal stresses c;, 4i; = cohesion and friction angle of the joint 0 = angle between the bolt and the joint a = inclination of the joint to the vertical axis P = bolt density parameter u, = convergence of unsupported tunnel section u, = convergence of bolted tunnel

Jan 1, 1992

By T J. Napier-Munn

This paper proceeds from the premise that process improvement is a key part of the mineral engineer’s role, and one in which he/she can make a significant contribution to shareholder value. It presents four tools to help with process improvement projects. Two are designed for process monitoring, to determine as soon as possible whether there has been a true change in performance: the cumulative sum (cusum) control chart plot with V-mask, and the control chart using a process model. The other two are used for process optimisation: simplex self-directing evolutionary operation (SSDEVOP), and a response surface model developed using a central composite rotatable experimental design (CCRD). These methods are robust, have a rigorous theoretical basis and are easy to implement. They also promote project continuity which increases the chances of success, particularly in fly-in/fly-out (FIFO) operations. Variants are used in other industries, but they are rarely if ever applied in mineral processing to-day for reasons which are unclear. The paper gives examples of the application of each method in concentrators which demonstrate that they have the potential to be useful additions to the mineral engineer’s professional toolbox.CITATION:Napier-Munn, T J, 2014. Cunning solutions to process improvement, in Proceedings 12th AusIMM Mill Operators’ Conference 2014, pp 5–10 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By Mann LD

The Haveluck gold deposit, located 2.5km north of Meekatharra, contained 1,284,000 tonnes at an average grade of 1.8 g/t gold of drill delineated proved and probable ore prior to commencement of production. Following successful laboratory and pilot scale testing a decision was made to establish a 300,000 tonnes per year heap leaching operation. The ore, crushed to minus 100mm was stacked on an impermeable membrane and irrigated with a dilute cyanide solution. Gold was recovered from the resulting pregnant solutions by adsorption onto activated carbon and gold bullion produced in a modified Zadra process desorption plant. From the commencement of mining it was obvious that a high percentage of fine material was being produced which would adversely affect the percolation of the cyanide solution-through the leach heaps. A screening plant was incorporated into the crushing circuit which provided an oversize product satisfactory for heap leaching and an undersize for carbon-in-pulp treatment. Plant design provided for the slurrying of minus 0.8mm ore before feeding to the pachuca tanks. Initial practice was to use four tanks for gold dissolution and two for carbon contact. Vibrating screens were used through- out for the carbon-ore separation and the loaded carbon was stripped in the existing desorption plant.

Jan 1, 1982

By G Capes, L Morizzi, N Mitkas, E Jones, D Grant

This paper describes the mining setting for the sub-level open stoping (SLOS) mining method used at Olympic Dam (OD), and investigates the range of stope performance conditions encountered over 30 years of production, using a qualitative description of the factors influencing performance. Utilising a continuous improvement tool, the Plan-Do-Check-Act (PDCA) process, and a forward-looking rock mechanics program, the intent is to identify the key factors driving productivity and performance to create a stable and achievable long term mine plan.

Mar 15, 2021

By BLAKE DAWSON WALDRON

I must acknowledge my strategic adviser, Mr Lance Grimstone, who contributed to the development of this paper, and collated the text and figures.

Jan 1, 1994

By Hikosaka A, Chiba A

In a fundamental study of the physical chemistry of steelmaking slag, equilibra bet- ween hydrogen-water vapour gas mixtures and liquid slags contained in solid iron crucibles have been measured for four binary slags, FetO-CaO, FetO-Si02, FetO-TiO2 and FetO-Al203 at 14000C. From the data, the activity of iron oxide and the ratio of ferrous and ferric ions (A = Fe3+/Fe2+) were calculated for the slag composition. The best ionic model is found to be that based on regular solution of cations. The oxygen distribution between slag and metal is quantitatively expressed by this model over a wide range of slag composition.

Jan 1, 1980

By A Tsoy

This abstract describes long-term mining schedule optimisation approach that may be suitable for complex marginal projects and is based on modern scheduling techniques. CITATION: Tsoy, A, 2018. Strategic mine schedule optimisation, in Proceedings Complex Orebodies Conference 2018, pp 91–92 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 21, 2018

A nine-month investigation was conducted into the effect on coke quality and blast furnace operation of the addition of bentonite and southern coal to the northern coal fed to the coke ovens at the Newcastle steelworks.Additions of 0·3 per cent bentonite or 25 per cent southern coal to the northern coal increased the coke strength from 15-20 A.S.T.M. stability to 25-30 A.S.T.M. stability. It is likely that improved mixing and blending facilities would, in both cases, give a coke of over 30 A.S.T.M. stability.For the same coke strength, the use of 0 3 per cent imported Wyoming bentonite was considerably cheaper than the use of 25 per cent southern coal, but the use of Australian bentonite promises the same coke strength for still lower costs. Other additives such as coke breeze, charcoal, iron ore fines, and certain other finely divided materials, gave relatively minor improvements in coke quality.There appeared to be sufficient improvement in blast furnace operation and production to justify full scale addition of bentonite to improve coke quality, although other variables, particularly iron ore physical quality, overshadowed on many occasions the effect of coke quality. Further coke trials with southern or bentonite will be carried out when ore quality has been improved by the introduction of ore sintering at Newcastle.INTRODUCTIONDuring the period of operation of the Newcastle coke ovens and blast furnaces from April 1960 (when No. 3 blast furnace was blown in after rebuilding) to December 1960, a bentonite coke trial was carried out based on earlier research findings (Gregory, 1959a, 1959b; Felton and Gregory, 1960; Gregory, 1960) that as little as 0 3 per cent to 05 per cent bentonite clay added to northern N.S.W. high volatile coking coals gave a significant increase in coke strength. The bentonite coke trial was followed by trials...

Jan 1, 1962

By C Delwig

ThyssenKrupp specialises in the manufacture of high-grade steel-sheet products. Its main customers include the automotive, construction, household appliance, energy and packaging industries.At its works in Duisburg, Germany, ThyssenKrupp Steel Europe produces 12 Mt of crude steel annually, making Duisburg one of the world’s largest steel hubs.ThyssenKrupp have installed an online elemental analyser and limestone dosing control System on one of three Sinter strands at Duisburg in an attempt to control the sinter raw mix with better precision. Traditionally, set point changes to the raw mixture were made after sampling and laboratory analysis of the sinter product. The analyser chosen uses prompt gamma neutron activation analysis to determine the elemental content of moving material on a conveyor each minute and was supplied by Thermo Fisher Scientific. The project goal was to control the CaO/SiO2 ratio (basicity) and reduce its variability in the sinter feed.Evaluation of the system has shown that the addition of the online analyser reduces the time lag related to the former method, therefore upset conditions can be reacted more quickly by the control system, and this has resulted in a more stable sintering process. As a result, the sinter feed variability in case of the basicity has been reduced by half. While CaO/SiO2 control was the initial aim of the project, a number of other benefi ts have been realised, such as a reduction in return fi nes and a financial benefi t of 0.11 €/ton of sinter attributed to the reduction of coke breeze and limestone. ThyssenKrupp Steel Europe has identifi ed that additional information available from the analyser could be used to optimise the complete sinter process.The project was carried out with a financial grant of the research program of the ‘Research Fund for Coal and Steel’.

Jul 11, 2011

Lower Silesia Coal Basin/SW Poland/ is adjacent to highly gas saturated igneous massiv and since the beginning of this century more than 1500 outbursts have occurred in four existing mines, including 1295 in the most hazardous mine Nowa Ruda. Prevailing part of these are carbon dioxide/coal outbursts of ejected masses 50-5000 tonnes/av.200/t and gas volume released from 200 m3 to 800,000 m3 Magnitude of these phenomena is growing with the depth and for present extraction levels/ 375-753 m/ may be expressed by a formula: M = 4.25/H-400/, where M-masses ejected, t and H - depth of extraction, m. Regulations obligatory hitherto call for gas pressure measurements to be made in 3 m long and 42 mm dia. boreholes spaces not more than 25 m along the longwall face and taking sample of drillings for desorption testing. Criteria of a hazard are following: pressure higher than 30 kPa /for C02/ or 80 kPa /for CH4/ and desorption more than 1,44 cm3/g. These criteria are not satisfactory because many outbursts occurred in spite of low values of parameters measured and for several times no hazard was evident after very high values were obtained. Moreover, observations show that a huge majority of case outbursts occurred in coal weakened by local geological distortion.

Jan 1, 1980

With the theme of û æUnderground Ore Handling SystemÆ, Kopanang Mine completed an extensive project on a specific system with technologies for the handling of ore from a dedicated drawpoint to the shaft system. The intended rail haulage tramming system had to be capable of handling the shaft design and Life of Mine (LOM) requirements. Kopanang is an AngloGold Ashanti gold mine situated in the province of the Free State in South Africa. In the Sotho language the name æKopanangÆ means to come together as a team. ItÆs an appropriate name given that 25 companies worked on this project. The future focus at Kopanang is to establish four mining levels between 3 to 4 km south-west of the shaft and two mining levels to the west. The mine has an expected life of almost 20 years and capital was approved in order to access this reserve to establish the infrastructure to handle the ore, hence this exclusive rail haulage tramming system of close to R40 million (SA rands), which took three years to construct. Apart from the fact that this system had to be capable of handling 6500 t per shift at a depth of over 2 km over a length of 3.2 km, some of the major considering factors were: safety, economic factors with improved labour productivity, efficiency and reliability, risk termination, and ergonomics. The system comprises two 20 t locomotives operating in a double header configuration from a dedicated draw point to a dedicated tip area for the reef and waste ore. With the objective of handling high speed and high capacity, this 200 t payload train is capable of running at 35 km/h powered from a 500 volt ac overhead line. Each loco consists of two 90 kW dc motors with ac/dc power conversion on the locomotive. For the system to operate at this speed, the rail system is constructed with Class 1 rails over the entire hauling distance. The tipping mechanism is unique and the span of 11 hoppers each with a load of close to 20 t is capable of tipping the pay load of 200 t in about 20 seconds hands free.

Jan 1, 2005

By J MacDiarmid

Atlas Copco is a leading provider of industrial productivity solutions (Atlas Copco, 2007) and one of the worldÆs largest suppliers of rock drilling equipment. The business division of Atlas Copco Construction and Mining Technique is based in +rebro, Sweden with the majority of their equipment produced in a number of facilities within the area. As part of the 2006 AusIMM/Atlas Copco Scholarship I was fortunate enough to visit these facilities to experience first hand this truly unique global company. Through numerous presentations on the various divisions and products manufactured by the company, I saw the broad range of products and services offered by the company and came to realise it is much more than just selling drills. Other highlights included a brief love affair, a tour of EuropeÆs largest underground mine (or factory depending who you ask), a drink at the ice bar at the ice hotel in JukkasjSrvi, and a number of dinners of reindeer. Overall this it was a truly amazing experience with all involved with the program going out of their way to ensure I got the most out of the trip. More importantly, through no effort at all, everyone naturally conveyed their passion for the industry and the company which is a great credit to the æAtlas Copco WayÆ thereby creating a company æcommitted to your superior productivity through interaction and innovationÆ.

Jan 1, 2007

Although the last decade has seen the growth of many new licencing and approval requirements for the exploration and mining industries, there remains in each State of Australia and the Northern Territory a predominant "Mining Act" containing provisions for the grant of exploration and mining tenements. What then are the rights and duties of tenement holders either by virtue of a Mining Act or through other approval and licencing mechanisms? What rights and duties does a person acquire when he is granted an exploration licence or a mining lease? In this paper I will attempt to cover these types of questions using in particular examples from New South Wales. I will also refer to a range of other subordinate approvals and licences which today's society requires and the need for ethics and recognition of liabilities.

Jan 1, 1995

By Sans H

The geostatistical Discrete Gaussian (DG) model is demonstrated to be capable of providing an effective means of implementing change of support for Enterprise-style mineralisation and thus providing reliable global recoverable resource estimates. At Enterprise, sample grade distribution proves to be highly positively skewed, therefore significant deskewing of the histogram and reduction of variance occurs when going from sample to block support. The DG model was experimentally tested in'the Southern Primary Zone (SPZ) at Enterprise, where high anisotropy ratios and pronounced short range structures are observed in variograms. The experimental test was run for a change of support for which the variance reduction was. approximately 60 per cent. This reduction is similar to that predicted by Krige's Relationship ('the volume-variance relationship') for the practical situation of a change of support from 5 m vertical blasthole samples to 3 m x 8 m x 5 m selective mining unit (SMU) blocks. The DG model was found to correctly predict the grade tonnage relationships for a wide range of cut off grades. The experimental test indicated that, given a representative histogram and variogram, the DG change of support provides a computationally efficient and practical means of reliably assessing global mineable resources at the early stages of a mining project. Further, it allows a range of selectivity strategies to be meaningfully and comparatively considered prior to mining.

Jan 1, 1995

By H Park, V Sahajwalla

"Due to the increasing amount of gangues in iron ores, a beneficiation process is required more as a preliminary step for ironmaking process. However, mechanical grinding and washing of iron ore needs tremendous effort that increases operating cost. Therefore, there is a necessity of a novel approach to ironmaking which can tolerate considerable amounts of silica or alumina. In the present study, a high alumina-carbon composite pellet was examined for an ironmaking process. The effect of compositional changes in the CaO-FexOy-Al2O3-SiO2 oxide system on the reduction of carbon composite pellets was investigated in a purpose built thermo-gravimetric analyser (TGA) at 1473K (1200¦C). As a result, alumina increased the reaction rate of carbon composite pellets by increasing surface area, while silica decreased the reaction rate by lowering surface area of samples. Infrared gas analysis assisted with the reaction kinetics of carbon composite pellets through measurement of CO and CO2 in off-gases. This study will assist with establishing the new pelletising method which differs from the conventional fluxed pellets.CITATION:Park, H and Sahajwalla, V, 2013. Effect of CaO-FexOy-Al2O3-SiO2 oxide system on the reduction of carbon composite pellets, in Proceedings Iron Ore 2013, pp 467-472 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Aug 12, 2013

Working thick coal seams in Poland is a very serious problem. Nearly 40 per cent of all coal is extracted from seams more than 3 m. thick. In absolute figures this represents about 70 million tons of coal per year. Working seams with thicknesses up to 3.5 m. does not present, at present, major difficul- ties. Working thicker seams calls for a steady improvement in order to increase the degree of utilization of the deposit and to enlarge the concentration of output. The problem is sometimes more difficult because, in many cases, the seams are worked under protected surface structures which compels the mines to use hydraulic stowing with all its advantages and disadvantages. Rock burst hazard, the control of which is the basic problem hindering the mining, is a further problem. The mining systems used in Poland are adapted to these natural and technical conditions.

Jan 1, 1976

By Ely K. W

On January 21, 1986, a methane ignition and subsequent mine fire occurred in the under- ground workings of the Jim Walter Resources, Incorporated No. 3 Mine located near Adger, Alabama. The fire, which began on a longwall face and eventually spread into the adjacent gob area, could not be extinguished directly and raged out of control for several hours. Sealing operations were begun underground by Mine Rescue Teams and the fire area was successfully sealed with the mine able to resume production in about one month. The No. 3 Mine liberated over sixteen million cubic feet of methane in twenty-four hours. The operation was unique, in that, the successful underground sealing of a fire in an ultra-gassy mine had not been attempted or com- pleted for several years. Maps and charts are included to give explanation of the typical data used to manage the recovery effort.

Jan 1, 1988

By F I. Cox, D Peeler, T Bodisco

"Diesel particulate matter (DPM), in particular, has been likened in a somewhat inflammatory manner to be the ‘next asbestos’.From the business change perspective, there are three areas holding the industry back from fully engaging with the issue:There is no real feedback loop in any operational sense to assess the impact of investment or application of controls to manage diesel emissions.DPM are getting ever smaller and more numerous, but there is no practical way of measuring them to regulate them in the field. Mass, the current basis of regulation, is becoming less and less relevant.Diesel emissions management is generally wholly viewed as a cost, yet there are significant areas of benefit available from good management.This paper discusses a feedback approach to address these three areas to move the industry forward. The six main areas of benefit from providing a feedback loop by continuously monitoring diesel emissions have been identified: Condition-based maintenance. Emissions change instantaneously if engine condition changes. Operator performance. An operator can use a lot more fuel for little incremental work output through poor technique or discipline. Vehicle utilisation. Operating hours achieved and ratios of idling to under power affect the proportion of emissions produced with no economic value. Fuel efficiency. This allows visibility into other contributing configuration and environmental factors for the vehicle. Emission rates. This allows scope to directly address the required ratio of ventilation to diesel emissions. Total carbon emissions. For National Greenhouse Emissions Reporting (NGER)-type reporting requirements, calculating the emissions individually from each vehicle rather than just reporting on fuel delivered to a site.CITATION:Cox, F I, Bodisco, T and Peeler, D, 2014. Continuous remote emissions monitoring – the lynchpin for air quality management, in Proceedings 12th AusIMM Underground Operators’ Conference 2014, pp 137–142 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 24, 2014

By I Treloar, T Elenbaas, E Isaaks

Critical reviews of grade control generally focus on blasthole sampling and the estimation of ore control block model (OCM) grades, with little or no attention given to dig-line design. For example, the estimation of block grades is deemed important as estimation errors lead to the misclassification of ore types and subsequent dollar loss. Recognition of the problem that the underestimation of block grades may be more or less costly than overestimation led to the application of loss functions to the classification of individual OCM blocks by ore type. The method is known as maximum profit selection (MPS). However, each OCM block may be misclassified a second time by dig-line design. Although each block may initially be assigned an optimum ore type by MPS, OCM blocks are seldom individually mineable by ore type. As a result, a common solution to this problem is the design of mineable polygons or dig lines loosely constrained by a minimum mining width. All material within a properly designed dig-line polygon can be mined and sent to a single destination such as the mill, stockpile or waste dump. These dig lines are often designed manually or by simple variations of computer-generated contour lines. They are generally suboptimal and result in additional misclassifications of ore types. This paper provides an algorithm for constrained optimum dig-line design where dig-line misclassifications are also evaluated through loss functions or MPS. Constrained optimum dig-line designs minimise the dollars lost by dig line misclassifications for a given minimum mining width constraint. A case study is provided illustrating constrained optimum dig-line design and subsequent benefits.CITATION:Isaaks, E, Treloar, I and Elenbaas, T, 2014. Optimum dig lines for open pit grade control, in Proceedings Ninth International Mining Geology Conference 2014 , pp 425–432 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 18, 2014

By Robinson T

The paper describes a spreadsheet system that enables selection of projects and companies that meet the user's corporate exploration and/or acquisition philosophy. A regularly maintained commercially available database has been used as the basis for this system. It provides an easily accessible efficient com- prehensive search method. The technique enables ranking by various criteria, both technical and financial, to provide groups of projects/companies that are of interest. Initially, target size parameters such as reserves, production and mine life are applied together with geological criteria such as age and deposit type; the significance of the targets in the context of the Australian gold industry is addressed.

Jan 1, 1988