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By T Roberts, D Faulkner, G Watt

Traditional mechanised resin rock bolting in hard rock underground mines requires the installation of resin capsules into a pre-drilled hole prior to the rock bolt being spun into a hole to mix the resin and set the bolt in place. In poor rockmass conditions, especially at depth or in highly altered faults and shears, the condition of the holes often deteriorates as the poor ground around it unravels and falls into the hole. This results in partially or fully blocked holes that either damages the resin capsule when they are being inserted into the holes or prevent it entirely until the hole is continuously cleaned of debris. This deterioration of the hole condition, and continuous need to clean and re-drill holes, also increases the diameter of the hole which in turn affects the continuously mechanically coupled anchorage mechanism of the rock bolt to the rockmass as there is simply not enough resin in the hole to fill the annulus between the bolt and the rock. This results in a large increase to critical heading cycle time and, more importantly, results in the rock reinforcement not performing as per design specification and increases the risk of instability. To overcome the quality control issues with resin bolt installation in poor ground, a single pass drill, install, inject and tension self-drilling resin bolt application was designed and implemented for use in such conditions. This system allows the operator to inject a two part polyester resin through a self-drilled hollow bolt to mix and fully encapsulate the rock reinforcement. The self-drilling bolt allows for post injection of the hole after the bolt has been installed into the rock and gives the operator manual or automated control on the amount of resin used in the hole to ensure complete encapsulation and continuously mechanically coupled anchorage to the rock. This allows the reinforcement to work as designed and provide the Geotechnical Engineer extra quality control confidence in these conditions. The implementation of this single pass resin bolting system resulted in significant decreases to the resin bolting cycle time and rock bolt quality control failures. In this paper the design, implementation and embedment into the development cycle will be discussed and the in situ quality control checks used to validate the increase in rock bolt installation quality will be shared. CITATION:Watt, G, Roberts, T and Faulkner, D, 2018. Single pass drill, install and inject self-drilling resin bolt application in poor ground, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 323–343 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

By T. Sakai

Present authors have succeeded in single pass large draught rolling of AZ31 and ZK60A magnesium alloy sheets below 200 °C without heating rolls by raising rolling speed above 1000 m/min. Heavy reduction larger than 60% can be applied by single pass high speed rolling even at room temperature. The rolled sheets showed fine recrystallized microstructure by dynamic recrystallization. The improvement of workability at lower rolling temperature is due to temperature rise by plastic working. In high speed rolling, almost all of the work done by plastic deformation is converted into the heat that raises the temperature of the sheet during rolling because the heat did not flow out of the sheet by conduction and radiation within very short time.

Jan 1, 2006

By Sanja Miskovic, Manjunath Basavarajappa

Numerical investigation of fluid flow characteristics and mixing efficiency of different impeller designs, based on the mixing characteristics of a passive scalar/tracer, is conducted using CFD for lab scale flotation cells of diameter D and height H equal to 300 mm. Fine computational mesh containing close to 1.6 million cells is used to obtain fully resolved steady state flow field close to the impeller. Unsteady scalar mixing simulations are performed on a relative coarse grid consisting of approximately 450,000 cells. Based on detailed numerical simulations, flows are fully characterized for four impeller designs at two off-bottom clearances C of 50 and 25 mm (D/6 and D/12). Passive scalar is injected from the cell bottom and the time required to attain uniform concentration distribution inside the cell volume is taken as the mixing time by monitoring scalar concentration at four discrete locations. The effect of varying agitation speed and off-bottom clearance on mean flow characteristics is also investigated. The scalar mixing results reveal regions of low mixing efficiency and are used to understand mixing process in greater detail. Through the previous research work, it was found that the main flow pattern undergoes transition from double-loop to single-loop configuration with decrease in off-bottom clearance below a certain critical height for stirred tanks using flotation impellers in the absence of stator. The inclusion of stator is found to alter the mean flow behaviour by preventing the jet from transitioning to axial type flow for lower clearance. Power numbers for different impeller designs are calculated based on the torque generated on impeller blades, and also from the total turbulent kinetic energy dissipation in the overall fluid volume. Power number is found to exhibit a significant dependence on off-bottom clearance based on the CFD results.

Jan 1, 2014

By David R. Beadman

The Fleming method is widely used for the analysis and prediction of single pile behaviour under maintained loading. The method does not distinguish between bored and driven piles. Driven piling avoids the need to dispose of spoil from the pile installation and is therefore becoming increasingly attractive. This paper considers the theoretical effects of the possible preload at the base of a driven pile after installation, using the hyperbolic functions as defined by Fleming. The Fleming method is reviewed and the equations and analyses are adapted, using spreadsheets, to allow for a possible preload. The simplifying assumption of the effect of the elastic compression of the pile is also reviewed and a more analytical method adopted to assess the elastic compression. Some driven pile test data is analysed to consider the possible effects of the preload on the performance of a driven pile and to test the theoretical relationships that are developed in the paper.

Jan 1, 2006

By Jim Galvin

4 and 6 point timber chock constructions are used extensively on both a systematic and spot basis by Australian longwall operators to support tailgate roadways. In 1996, the School of Mining Engineering at UNSW published design and performance criteria for timber chocks constructed from Australian hardwoods. The research was funded by the Australian Coal Association Research Program (ACARP). In 1997, ACARP awarded funding for a stage 2 testing program. This testing focussed on examining the effect of using thinner timber elements in chock constructions to improve OH&S and comparing the full-scale performance of traditional 4 point chocks to Link-n-Lock constructions. It was established that chocks constructed from thinner elements have failure loads much less than thicker elements. However up to the failure loads of the thinner elements there was no significant difference in the response to convergence of chocks constructed from 25, 50 or 100mm thick elements. Chocks constructed from 150mm thick elements have a similar ultimate strength to the 100mm thick elements. However, they have a significantly lower resistance to load, thereby permitting more convergence to occur. There is more potential for chocks comprised of thin elements to be constructed 'out of plumb' and so suffer eccentric loading. The full scale testing program established that at any given level of convergence up to 10% strain, the timber in a Link-n-Lock chock generates twice the support resistance of the same quantity of the same timber in an equivalent size 4 pointer chock. On the basis of support resistance per cubic metre of timber, there is only a marginal difference in the performance of 1.0m Link-n-Lock chocks and 1.2m Link-n-Lock chocks constructed from select Blue Gum. The cost per tonne of support provided by a Link-n-Lock chock is effectively half of that provided by a 4 pointer chock of equivalent dimension and timber. Up to a strain level of 4%. Link-n-Lock chocks constructed from 1.2m long elements are slightly more cost effective than the same chocks constructed from 1.0m long elements. Thereafter, there is no significant difference in cost per tonne of support resistance. Beyond a strain level of about 4%, Link-n¬Lock chocks constructed from landscape grade Blue Gum are just as cost effective as Link-n-Lock chocks constructed from structural grade 4 Blue Gum.

Jan 1, 2000

By Tom Short, Bill Beam

Some of the weapons testing shafts at Mercury, Nevada require depths of 1000ft and diameters of 10 feet. The top 40 feet to 65 feet is drilled, blasted and excavated by Large caisson type augers in order to provide vertical working room for the placement of large, oil field type, drilling rigs and the required drill collar.

Jan 1, 1991

By Bonifacio Degay, Mike Lovitt

PT Freeport Indonesia is a block cave mine that now utilizes an advanced undercut method to set up the min in the Deep Ore Zone (DOZ). In this method a slice of rock (undercut) is broken such that it sits on top of the drawbell level. The drawbells are developed to channel the broken ore into the extraction level and to enable the caving orebody to be drawn out in an even and controlled manner. These drawbells are difficult to form due to the small amount of void that can be developed in the low strength rock before firing. Starting with two rises of 2m square, the void ratio for the entire drawbell around 6%, which would normally result in a frozen and unproductive blast. Orica -Mining Services have worked with PT Freeport in a collaborative effort to find a solution to the mining problem. With excellent control of timing of the blasting it is possible to get fluid flow of blasted rock out of the draw points such that more void can be made available for blasting the remaining parts of the drawbell. The i-konTM electronic blasting system gives the exacting control of timing within the blast to achieve this Dynamic Void Generation (DVG). The solution stops the need to charge close to brows in the drawbells and reduces the cost and time related to developing initial blast voidage. This paper identifies the results of the trials including design, photographic evidence and vibration analysis. The flexibility and accurate timing of this electronic blasting system has enabled single hole initiation rather than 4 or more holes being initiated together, thereby reducing the damaging vibrations to the extraction level.

Jan 1, 2004

By H. B. Muller

Single stage autogenous grinding of run-of-mine ore was selected by Broken Hill South Ltd., parent Company of Cobar Mines Pty. Ltd. for the concentrator to treat 60,000 tons per four weekly period of copper and complex copper-lead-zinc sulphide ores from the C.S.A. Mine at Cobar, Australia. Ore is mined by mechanised horizontal cut-and-fill stoping and is prepared for grinding by crushing under- ground in a 60 in. x 48 in. jaw-crusher set at 5 in. closed side setting. The ore is reduced to 80% minus 76 microns in two parallel sections each of one 22 ft. dim. x 7 ft. long autogenous grinding mill, powered by a 1,250 H.P. motor, operating in closed circuit with a single stage 20 in. dim. cyclone. Broken Hill South's original concept of the concentrator required the maximum use of reliable instrumentation, centralised control, and the minimum of manning. To achieve this objective the control room, housing the process recorders, alarms, closed circuit television monitors and all the control equipment, overlooks the grinding and flotation sections, and the whole plant is serviced by a public address system. The grinding units and associated equipment are located in the open and are serviced with the aid of a mobile crane and a mobile hydraulically-operated liner lifting device.

Jan 1, 1970

By S Jahanshahi, T Norgate

In single stage copper making appreciable amounts of copper report to the slag phase. Various strategies are available to minimise copper losses to the slag. However a slag treatment stage is likely to be required in an economically viable process. A number of slag treatment process options are available and include: flotation, leaching and thermal reduction. In the design of an industrial process some type of economic as well as technical analysis of these options will be required. In this paper an outline of the techno-economic analysis procedure used to design a single stage copper making process is presented. The calculated operating and capital costs of industrial copper making processes are compared and used to determine the optimum single stage copper making flowsheet. The most economic slag treatment options is flotation of slags containing low amounts of copper.

Jan 1, 2000

By M. Somerville

In 1989 CSIRO Minerals initiated investigations into continuous converting of copper matte into low sulphur blister in Sirosmelt type reactors. Following the successful piloting of this processing route, some effort was directed towards a single stage copper making process where copper metal is made in one step from concentrate. The aim of the project is to develop a continuous process, which offers considerable environmental and economic benefits over conventional copper making processes, which use Pierce-Smith converters. In the selection of the optimum flowsheet a number of slag treatment options have been considered and tested. These unit operations include: leaching and electrowinning, flotation-leaching-electrowinning and flotation with recycling of recovered copper through the smelting vessel. In this paper the suitability of these process options are evaluated using the available information and recently measured copper recoveries from our testwork at CSIRO. The operating and capital costs of the various options have been estimated using Aspen Plus simulation procedures. The most attractive flowsheet in terms of capital and operating costs is the treatment of slag using mineral processing techniques and the recycle of a copper slag concentrate to the smelting vessel. It has been found that the chemistry of the slag being treated has a large bearing on the recovery of copper in flotation and hence on the economics of the process.

Jan 1, 1999

By Brian Putland

Single stage semi-autogenous / autogenous (S/AG) milling has become a common design for a variety of ore types with the advantages of being comparatively low capital cost and flexible for future expansion. The single stage SAG/AG milling option is ideal for starter projects with significant exploration and expansion potential. Currently a number of the largest SAG mills designed are installed in single stage configuration. This paper discusses the challenges associated with the process design of single stage SAG/AG milling circuits, the design flexibility required to ensure a robust circuit and the operating techniques adopted at successful installations.

Jan 1, 2012

By Brian Putland, Fred Kock, Leigh Siddall

Single stage semi-autogenous / autogenous (S/AG) milling has become a common design for a variety of ore types with the advantages of being comparatively low capital cost and flexible for future expansion. The single stage SAG/AG milling option is ideal for starter projects with significant exploration and expansion potential. Currently a number of the largest SAG mills designed are installed in single stage configuration. This paper discusses the challenges associated with the process design of single stage SAG/AG milling circuits, the design flexibility required to ensure a robust circuit and the operating techniques adopted at successful installations.

Jan 1, 2012

By C. E. Schmidt

Homestake crushing and grinding, practice-was completely revised during the period of 1951-1953. During the conversion, both crushing plants at the head frames the Ross and the Yates, were changes at each plant involved replacing the two 8K gyratories with a rebuilt, The flow sheet single thirty inch gyratory for primary crushing to four inch. The gyratory discharges to a seven foot Symons standard cone crusher set at 1-1/8 inch opening. The cone discharge goes to Tyrock screens fed by vibrating feeders. Screen openings, are l/2 inch by 5 inches: at the Ross. Plant, and 3/8 inch by 5; inches at the Yates. Screen oversize goes to a seven foot Symons cone brusher converted to the short head type; the crusher setting is 5/16 inch. Crusher, discharge; is closed circuited with the Tyrock screens, The above crushing installation delivers a minus 5/8 inch rod mill feed to the mill bins. The crushing revision eliminated the-180 heavy South African type stamps, which had previously reduced the 2 inch crushing plant product to a minus 5/8 inch feed for the 10 rod mills, and 8 ball and pebble.; mills, other revisions in the mill flow sheet, resulted in 3 identical units of about 1350 tons per day, capacity per unit, Each unit consists of an open, circuit 6 foot by 12 foot rod mill, fed from two 24 in by 48 inch vibrating feeders of the four feeders available per unit. A gathering belt delivers the ore discharge of the feeders to the Transportoweigher, which in turn discharge s, into the rod; mill feed spout. Rod Mill discharge is the feed for the 9 foot by 11 foot ball mill, The ball mill is closed circuited with a 16 foot by 30 foot Dorr Classifier. The Homestake make amalgamator, for coarse gold recovery in the ball mill circuit, made' necessary a 36 inch spiral conveyor between the classifier rake discharge and, the combination drum and double scoop feeder on the ball mill See Figure l - the flow sheet of the two stage grinding units.

Jan 1, 1958

By Corby Anderson

The efficient separation of palladium from the transition metals copper, nickel and iron can be effected by passing a leach solution of these metals through a column of the silica polyamine composite material, WP-1, patented by Purity Systems Inc (PSI), Assignee, University of Montana with exclusive license to PSI. The separation can be done at the intrinsic pH of a nitrogen species catalyzed (NSC) oxidative pressure leach solution (~0) and stripping of the palladium from the composite can be effected with hydrochloric acid/ammonium chloride solutions at 50oC. Batch capacities of the composite for palladium are ~ 1.8 mmol/g resin. The possibilities for isolating the metal from the strip are discussed. Given the proven longevity and rapid capture kinetics of the polyamine composites, this new approach should prove to be an economically viable alternative to the multi-step concentration processes practiced in the PGM industry to date.

Jan 1, 2003

By B. Elevli, M. D. G. Salamon

Production scheduling of an open-pit mine is one of the most important steps in open-pit mining. The mine's production schedule defines the distribution of cash flows and, as a result, directly influences the net present value (NPV) and overall economic feasibility of a project. The need to plan and operate a mine with an optimum production schedule has been obvious for some time, but the methods used to obtain such a schedule have not been so obvious. The current practice is to do a trial and error analysis by hand. In an attempt to improve the way production scheduling is currently done, a new computer based production scheduling algorithm was developed. This paper describes the fundamentals of this newly developed heuristic scheduling algorithm and its application to a gold deposit. The results of this case study show that the schedules, based on the new method, provide improved cash flows compared to production schedules done manually.

Jan 1, 1992

By B. Elevli

Production scheduling of an open-pit mine is one of the most important steps in open-pit mining. The production schedule of a mine defines the distribution of cash flows and as a result directly influences the net present value (NPV) and overall economic feasibility of a project. Although the need to plan and operate a mine with an optimum production schedule has been obvious for some time, the methods used to obtain such a schedule have not been. The current practice for doing is to do it by hand on the basis of trial and error analysis. In an attempt to improve the way production scheduling is currently done, a new computer based production scheduling algorithm is developed. This paper describes the fundamentals of this newly developed heuristic scheduling algorithm and its application on a gold deposit. The results coming from a case study show that the schedules based on the new method provides improved cash flows compare to a manually done production schedules.

Jan 1, 1989

By Mahmoud Sepehrmanesh, Verya Nasri

The purpose of this paper is to outline the advantages and disadvantages of single tube and twin tubes for subway systems. Different aspects such as diameter of the tunnel (tunnel spaceproofing), configuration of subway line and stations, impacts on passenger safety and evacuation, ventilation system as well as rail system for each solution were evaluated and compared. In addition, a multi-criterion approach is established to facilitate the decision making for these two different subway systems. The practical example of a mega project has been discussed and the details of the decision-making process has been explained. This proposed multicriterion can be used to facilitate selecting the best subway system in any urban areas.

Dec 1, 2022

By F. Michael Jenkins, Elaine T. Bowers

Longwall systems are used to mine approximately 50 pct of the world's total coal production. Single entries are the predominate method of longwall development in Europe and Asia where mining conditions are much more severe than those encountered in the United States. During the 1970's and early 19801s, the Bureau of Mines and the coal mining industry invested nearly $20 million in single entry and related research. This report reviews the accomplishments of single-entry research in the United States. Two U.S. single-entry field projects are described; the Sunnyside Single-Entry Project conducted in central Utah, and the Tunnel Boring project conducted in northern West Virginia. Two other important studies are discussed, the Single-Entry Study by NAMCO and the Single-Entry Design Study by Ketron. Inc. This review compares the resulting technology with European counterparts to further assess the utility and efficiency of the U.S. systems, and final1 y, it discusses future research and development options which would lead to safe and productive single-entry longwall development in this country.

Jan 1, 1986

By J. Nakayama

Down-the-hole hammer is commonly recognized as the most powerful drilling equipment for weathered to fresh rock formation including boulders. However, its drilling diameter is restricted by reasons of difficulty to actualize large diameter drillhead and to ensure discharging means of cuttings. Cuttings are usually removed by flushing i.e. uprising return air after compressed air actuates hammer, but in case of large diameter drilling, as the clearance between drill rod and surrounding wall of hole become fairly large, necessary up-hole air velocity to transport cuttings can not be maintained. In case of marine or underwater drilling or high groundwater table, orthodox down-the-hole hammer is obstructed its operation by water. This single head hammer drill combined large diameter drillhead with reverse circulation of drilling fluid enables large diameter drilling extending to 1.5 m, i.e. actualized large diameter mechanical drillhead incorporated with ensured cuttings removal means enabled this range of drilling. This paper introduces its features and actual applications to large diameter bored pile drilling for varied sorts of rocks in maritime construction projects.

Jan 1, 1996

Chalcopyrite concentrate was combusted in oxygen-nitrogen atmospheres, the composition of which ranged from 1-100 per cent oxygen. Factors studied included particle size, experimental temperature and oxygen concentration. The study was assisted by chemical and X-ray diffraction (XRD) analysis and temperature measurements of single particles. Size reduction occurring after melting was found to have a major effect on the overall reaction time. Thus time to attain ignition was largely determined by the original particle size, whereas combustion time was independent of this factor. For particles larger than 40 I'm in air the time to attain ignition predominated. The maximum temperatures measured for single particles were the result of pyrite present in the concentrate. Chalcopyrite did not attain thesame temperatures. Vaporization, either as CU(g) or CuO(g) lImited the temperature. Maximum temperatures measured for single particles of pyrite ranged from 1610°C in 14 per cent oxygen to 2360°C in 100 per cent oxygen (both at 700°C). Measured temperatures were compared with those calculated from a diffusion-based model.

Jan 1, 1983