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By A. Tosun

Muckpile fragmentation formed by blasting depends on the specific charge factor, the discontinuities in the rock mass, and the rock strength. Determination of the discontinuity characteristics and rock strength is a long and difficult process. These two parameters are directly associated with the rock drilling speed. Therefore, it is the drilling speed of the machine used for the blast-hole, rather than the blasthole discontinuity characteristics and rock strength parameters, that is used in the prediction of muckpile fragmentation before blasting. Primarily, it has been suggested that the muckpile fragmentation values can be correctly determined by establishing correlations between the efficiency of the loader and muck pile fragmentation, since fragmentation is directly correlated with the former parameter. Subsequently, a correlation predicting the drilling speed of the drill machine was developed according to the discontinuity characteristics of the blasting surface and the rock strength. Finally, a correlation was developed predicting muckpile fragmentation according to the specific charge factor and the drilling speed of the drill machine The data was obtained by conducting blasting tests in two different limestone quarries.

Nov 30, 2022

By C. C. Hawes

SILICA is the main impurity in iron ore. It is intimately associated with the iron oxide, sometimes free but more often in the combined state, as a mineral silicate. Its separation and purification sometimes present difficult problems to the analyst. In the absence of any definite knowledge to the contrary, orthosilicic acid. H4SiO4, is supposed to be the only silicic acid made, all other forms, such as metasilicic acid, H2SiO3, representing different degrees of its dehydration. These acids are exceedingly weak but form the most stable compounds found in nature. They are known as the silicate minerals and are formed by the combination of the different metallic oxides

Jan 1, 1936

Energy benchmarking is widely applied across industries to determine the potential to improve energy performance. Unlike the many technologies for which energy benchmarks and efficiency rating systems are already in maturity, benchmarking of mining processes is still in its infancy. Benchmarking energy usage in mining operations, where energy costs are high and represent a significant portion of overall operating expenses, is challenging due to the uniqueness of each mining operation. Mines vary in terms of geology, geographic setting, ore body geometry, mineralogy which impact the mining method, material handling, processing and waste management. In order to gauge the opportunity for reducing the energy intensity of individual operations and also to compare the energy performance of operations on a global scale, the deployment of new benchmarking methodologies, models and frameworks is necessary. As a step towards the establishment of an accurate framework for benchmarking the energy consumption of mining operations, comminution, one of the more energy intensive mining sub-processes, was selected as the focus of a new energy benchmarking method. The methodologies and processes used to onset fragmentation in a rock mass to the crushing or grinding of rock to a size that is suitable for economic extraction are predominantly dependent on the ore properties. For this reason, site specific factors, such as the size reduction requirements and ore hardness were included in an energy benchmark model so that the energy performance of comminution processes at different operations could be normalized and compared on a global scale. Single particle compression breakage has been identified by several prominent researchers in the field of comminution as the upper limit of energy utilization in size reduction processes. For this reason single particle compression breakage was proposed as the basis of a work index for ores to be used as an input for the benchmark model. Overall, the new method showed that the energy benchmark for mineral comminution can be normalized and subsequently compared for a range of mining operations once the ore hardness has been appropriately characterized.

Aug 1, 2013

By Jin Dai, Xianwen Geng, Hao Liu, Pu Wang

To investigate how deformation failure occurs in roadways surrounding rock, the relationship between cohesion and plastic shear strain of the strain softening model and the equation for calculating the shear strain of a rock mass in the ultimate elastic state are derived. On this basis, the equality relationship between the built-in maximum shear strain increment and cohesion of FLAC 3D was established to give a more intuitive picture of how the cohesion of the roadway surrounding rock changes. The cohesion attenuation and deformation of the surrounding rock are analysed. The results show that significant deformation in the roadway surrounding rock was caused primarily by the development of large areas of highly softened plastic rock masses towards residual strength. Taking the floor overhead-mining roadway under different rock pillar thicknesses (RPTs) in the Xinglongzhuang Coal Mine as an example, the results demonstrate that investigating the cohesion distribution inside the roadway during mining operation can provide a more intuitive, more accurate description of the degree of failure of the surrounding rock at any point of the roadway, as well as the overall failure range of the surrounding rock. The simulation agrees well with the field monitoring result and seems to be more practically useful than simply analysing the coverage of shear plastic zones. Based on the failure range and degree of roadway surrounding rock with different RPTs, three support schemes are designed. Classified support was implemented for roadways under different RPTs, which realizes the effective control of roadway surrounding rock.

Jan 16, 2022

By R Markoski, P Grealish

The requirement for rapid vertical development for underground ventilation is often a factor when dealing with dynamic mine plans, with short vertical developments being used to optimise ventilation systems. In an effort to increase the safety and efficiency of the constructions, a simple and effective sinking methodology is required that is both adaptable and repeatable. A modified shaft construction methodology is proposed that attempts to minimise risk to the personnel as well as be cost-effective. Readily available equipment is used to ensure adaptability to the various environments and shaft parameters.One of the greatest risks of shaft sinking is having personnel working suspended over open cavities or underneath suspended loads. Removing this risk, by ensuring all construction is done from solid ground, allows for safer sinking operations. As the process is repeatable, familiarity and confidence in its construction sequence will increase with each successive sink.A trial sink is performed with a 3.6 m diameter, 20 m deep shaft. The shaft was excavated using a conventional strip-and-line philosophy, with the shaft then being lined from the collar via the use of large diameter corrugated steel culverts. The annulus between the steel culverts and shaft excavation is then filled with a concrete mixture to secure it in position.The new process was successful, with no personnel at any time during the process being suspended above an open excavation. The installation had relatively low capital and operational costs and was completed faster than an equivalent, conventional concrete-lined shaft construction. Therefore when compared to conventional shaft-sinking methods, this process can be considered safer, more efficient and relatively cost-effective.Further research is required to determine whether this method can be expanded to larger vertical developments.CITATION:Markoski, R and Grealish, P, 2014. A new method for rapid vertical development of underground ventilation shafts, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 603–606 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By E. Bonsall, J. J. Brummer, A. R. Graham

"A method and device are described for sampling diamond-drill core by cutting a continuous fillet of constant cross section from the cylindrical surface of the core throughout appropriate sample lengths. The apparatus employs a tapered, abrasive-set, cutting wheel, the conical cutting surface of which projects slightly into a rectangular core-guiding trough set parallel to the axis of rotation. The depth of fillet and thus the amount of sample per unit length can be regulated by adjusting the core guides. The freshly cut fillet itself, by engaging in a guide beyond the cutting wheel, acts to prevent rotation of the core during operation of the device.The cuttings which form the sample are normally collected in a tray below the cutting-wheel and appear at about 80 per cent -100 mesh. They require little or no further treatment or comminution before analysis. Speed, economy and convenience of sampling are thus greatly increased as compared with conventional sampling by im-1>act breaking or sawing, followed by crushing, grinding and sub division for assayAssays from fillets (about 1/20 the cross-sectional area of the core) and from 180-degree segments, from the same ninety-three core-samples, representing 431 feet of nickel-copper mineralization, gave the following results:"

Jan 1, 1968

By B W. Atkinson

Full-stream mechanised sampling apparatus, that collect a full cross-sectional increment from the complete screen discharge, will always be the preferred option for sampling screen overflows. However, the reality is that provisions for automated sampling are rarely, if ever, provided at the discharges of individual screens within beneficiation plants.Sampling from the discharge of high capacity vibrating screens, especially multi-slope screens, is subject to sampling bias, due to the stratification of the ore that occurs on the vibrating screen deck. The stratification in the vibrating bed translates to a stratified falling stream at the discharge end of the screen, typically with smaller particles at the back of the falling stream and large particles at the front of the falling stream (Figure 1).The chemical and physical characteristics of heterogeneous ore (mineral or coal) particles vary significantly with particle size. If samples do not correctly reflect the source material size distribution, they will be biased and the resulting analytical/assay data will not reflect the actual physical nor chemical characteristics of the source material.Prior published data for coal preparation research (Australian Coal Association Research Program) has demonstrated that a bias appears to exist for samples collected from high capacity multi-slope screens.A new form of sampling scoop has been developed with the aim of overcoming this issue.Bias was evaluated at a coal preparation plant by comparing the desliming screen overflow size distribution to that for æreferenceÆ coal preparation plant feed samples collected using the recognised stopped-belt technique. The study procured 20 sets of comparison samples in order to ensure statistical relevance.Two forms of sampling device were employed for the multislope screen discharge.A conventional square aperture scoop was demonstrated to exhibit a significant coarse bias, in that the resulting samples exhibited a significantly coarser size distribution compared to the reference samples. In other words it was evident that the conventional scoop æfavouredÆ material from the front of the falling stream.A new æcollapsibleÆ sample scoop was evaluated in parallel, and its samples were found to exhibit no relevant bias.CITATION:Atkinson, B W and Swanson, A R, 2012. A new method for sampling from high capacity screens, in Proceedings Sampling 2012 , pp 89-94 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 21, 2012

By I. G. Ediz, D. W. Dixon, W. M. Fidler

In this paper a new method for the arresting of tunnel explosions is presented. In the proposed technique, the on coming explosion is detected by a pressure sensitive device by a pre-determined rise in static pressure. The sensor then triggers a mechanism which causes the explosion door to be closed in a specially constructed concrete barrier zone. The doors are of a special construction and consist of perforated steel plates that allow part of the blast wave to be transmitted but do not allow the passage of the flame. A number of design parameters have been identified, including: the likely amplitudes of the transmitted/reflected pressure waves that would govern the explosion door pressure loading; thickness of the perforated steel packages; perforation dimensions; heat transfer across the door and other factors.

Jan 1, 1995

"In response to mine head grades declining and orebodies becoming more complex, Glencore Technology has developed an alternative method for recovering economic minerals once leached into solution, rather than relying on conventional flowsheet options. The method involves the precipitation and separation of base metals from solution with limestone or lime. The final grade of these precipitate is not usually high enough to attract favourable terms of sale due to dilution from gypsum and sulphate salts. A set of operating conditions have been developed to allow the separation of the base metal precipitate from gypsum by exploiting the difference in particle size. A high-grade oxide product can be easily separated from the gypsum stream at very low cost. This process was originally developed by Glencore for zinc and copper systems. This paper reports on the successful application to nickel and cobalt, and this process has significant advantages over the incumbent precipitation process utilising magnesia.INTRODUCTION During evaluation of transitional and oxide zinc ore deposits during the 1990’s, Noranda Inc. (now Glencore) developed a sulphate based ore leach process to extract zinc into solution. For flowsheet development, conventional schemes dictated that once the zinc was dissolved in an acidified solution it was recovered by means of purification or solvent extraction followed by electrowinning and casting to produce zinc ingots. The deposits Noranda evaluated were high grade but had a relatively short mine life (10 years) and economic analysis showed that the projects couldn’t sustain the investment of a full zinc refinery. Compounding this problem was the lack of power supply infrastructure and the high power cost in the region. Noranda then evaluated alternative means of recovering zinc from solution. Laboratory testwork showed that a high-grade zinc precipitate (+50 wt% Zn) could be produced as an oxide, carbonate or sulphide by contacting acidified zinc sulphate solution with a number of reagents including soda ash, sodium hydroxide, and sodium hydrogen sulphide. Economic evaluation showed that the cost of the reagents are prohibitive, especially when the final product is still a metal intermediate (ZnO, ZnCO3 or ZnS). Noranda then continued to focus on fine zinc oxide precipitation for supply into the automotive tyre industry as this product would attract favourable terms of sale as a premium on Special High Grade (SHG) zinc."

Jan 1, 2017

By Robert Boehnke, Bernd Mueller

This contribution presents an innovative, statistically supported method to predict blast vibrations in rock mass. For modelling the processes during and after detonation, a theory is employed which is based on linear momentum (so-called momentum theory), strongly supported by new measurement methods. During the course of the investigations, the following parameters have been found to dominantly influence vibrations: ! charge WB, includes geometrical factors such as borehole length and diameter (kg) ! detonation velocity cd of the explosives used (m/s) ! distance r between the points of emission and immission (m) and the statistically determined negative exponent n ! factor RM or RS of the rock mass which is related to the specific blast momentum and the drilling and blasting technique used and is statistically determined together with the exponent m (mm/kg or mms/kgm)

Jan 1, 2004

By R. Barbaroux, B. Dubreuil, D. Lemieux, K. Nasrallah, G. Garcia Curiel

"As conventional, base or precious metal ores are being depleted worldwide, the mining industry is being faced with an increasing exploitation of arsenical sulfidic ores. Enargite is a common example. The downstream processing of these ores poses several problems ranging from high smelter penalties to finding economical and environmentally acceptable means of disposing of the arsenic. Several hydrometallurgical processes have been proposed for extracting arsenic from enargite concentrates, notably using alkaline sulphide leaching (ASL). However, few alternatives exist for removing the arsenic from solution and stabilizing it in an approach that is both economical and environmentally acceptable.Dundee Sustainable Technologies (“DST”) has developed a technology for the sequestration of arsenic by vitrification. Originally optimized to cost-effectively stabilize arsenic trioxide (As2O3), DST has shown that vitrification could be successfully extended to the stabilization of other arsenical products, such as calcium arsenate (Ca3(AsO4)2) and sodium arsenate (Na3AsO4). In this paper, the vitrification of arsenic in the context of an enargite leaching was newly explored and demonstrated successfully.Two processing routes are being proposed by DST for the removal of arsenic from enargite concentrates and their stabilization by vitrification. In one route, arsenic is extracted by ASL and is then precipitated under atmospheric conditions and with minimal use of reagents and time. The resulting precipitate is an unstable hydrated ferric arsenate (FeAsO4•2H2O) that is then vitrified in a non-dilutive method, significantly increasing the stability of arsenic and meeting the TCLP guideline. Unlike is required for scorodite, stabilization was successfully achieved without concern for the crystallinity of the precipitate."

Jan 1, 2017

By M. England

A method for the analysis and prediction of single pile displacement behaviour is described. It is the displacement in time, under constant load, based on the use of hyperbolic functions to characterise individual constituents of the displacement-time behaviour. Extensive use of this technique has confirmed its validity in a variety of soils and that consolidation and creep settlement appear to be indistinguishable. The algorithms employed are suitable to model the displacement behaviour from the onset of load to infinite time for all types of piles and surface foundations. Until the advent of computer controlled static load testing, analysis of the displacement-time characteristic during pile load tests has been hindered by the quality of the data recorded and inconsistency of loading. This has hitherto made the development of suitable behavioural models very difficult. Understanding the soil deformation within a proper time framework allows the subject of pile instrumentation and testing to be developed. The equipment required is basically a computer controlled loading and pile head displacement measuring system which allows accurate analysis of the settlement characteristic in almost every situation.

Jan 1, 1993

By W. Todd

The Robbins Company has developed a boring machine, with a rubber packer serving as the gripper system, for blind boring of raises without using drill pipe. This machine is the BorPak and has many applications for use in the mining industry which will improve productivity. In addition to the cost savings, the boring method will lead to increased safety in constructing blind raises. The advantages of using the BorPak in a mining environment will be discussed together with possible applications.

Jan 1, 1994

By Kenneth M. Bravinder, Jonathan E. Koogle, Dean H. Sheldon

THE solution of subsurface geological problems requires an analysis of vertical and horizontal dimensional relationships. For many, the ability to visualize structures in three dimensions is not easily acquired, and for areas where the structural conditions are complicated by faulting the need arises for illustrative models. This has led to the many forms of peg models, in which the usual course of construction includes a peg for the well bore, and the suspension of strings from peg to peg to illustrate the formation correlation between wells, thus developing the usual folds and flexures. Such models proved unsatisfactory for the analysis of fault problems. Consideration was then given to the use of transparent materials. A model of the Dominguez oil field was constructed in 1935, which consisted of a series of glass panels from well to well on which the formations were shown in color. This model, though serving its purpose at the time, proved to be impractical from the standpoints of cost, breakage hazard, and extreme difficulty in maintenance. The cost of materials was estimated to be approximately $300, and the construction required the services of one man for a period of from 10 to 12 months. Maintenance after actual construction was an additional expense. Consideration was then given to the use of celluloid, and after some experimental work it was found that the advantages in its use were: (I) a short construction time, (2) ease of handling the material, (3) sections are easily reworked, (4) low cost. CONSTRUCTION It would be of little value to recount here the difficulties encountered in the building of the first celluloid model. The conclusions drawn, however, suggest the following procedure for those who contemplate the construction of such a model: I. Determination of the Scale.-Accurate geological interpretation requires the use of the same scale horizontally and vertically. It should be emphasized that the limited size of the celluloid sheets (20 by 48 in. maximum dimensions), the area to be studied, the maximum depths to be plotted, and area of possible future development are the controlling factors in adopting a scale to be used. 2. Construction of the Base.-A satisfactory base may be constructed by using two pieces of three-ply wood separated by strips of i by 2-in. material. This type of construction prevents warping of the base. The size of the base is determined by the dimensions of the area to be studied plus 5 in. on all sides. A map of the same scale as that adopted for the model, indicating the lines of section to be used, should be fastened to the base. 3. Construction of the Frame (Fig. I).-In the construction of the frame the use of 1/2-in. o.d. pipe welded in a box shape is suggested, with two horizontal rods on each of the four sides, top and bottom. The top rod should be at least I in. higher than the

Jan 1, 1941

By Rossiter W. Raymond

I DESIRE to call the attention of the Institute to a novel system of dredging, which, it seems to me, may prove applicable, not only to river and harbor improvements, but also to certain varieties at least of alluvial and diluvial gold mining; that is, river-mining, barmining, coast-mining, and any other similar operations now carried on by means of coffer-dams or dredging machines. The simple and effective method to which I refer is the invention of General Roy Stone, formerly an officer of volunteers, and at present a civil engineer, engaged under General Newton, of the United States Engineer Corps, upon the government works in New York harbor. General Stone has been, since September, 1878, in charge of operations upon Diamond Reef. This reef, lying between Governor's Island and the Battery, is one of the most dangerous in the harbor. Its position in the highway of navigation, and the fact that it is dangerous only to vessels of considerable draught and at certain stages of the tide, combine to increase the serious nature of the disasters which it has caused. The reef consists partly of rock in place, and partly of deposits of glacial clay, boulders, and pebbles, over all of which lies, or did lie until it was removed, the ordinary silt and rubbish of the harbor. As the purpose of the present paper has nothing to do with the special dimensions and other circumstances of this particular work, I describe those features only which are connected with General Stone's ingenious device. Various attempts have been made to remove the upper portion of Diamond Reef and secure a navigable depth at low tide. Some years ago Maillefert undertook to accomplish this by firing charges of high explosives, simply laid upon the surface. He accomplished some good in the removal of projecting points and ridges ; but as soon as the surface of the reef had become approximately level, his method was no longer effective. After the work had been taken up by the Engineer Corps, the well-known drilling-scow invented by General Newton was brought into action ; and, so long as holes could be bored and fired in solid rock, this process was effective enough. In the mixture of hard-pan

Jan 1, 1880

By B. P. Verma, K. N. Sinha, N. M. Raju, B. Singh

The paper describes a new method of grouting bolts developed at the Central Mining Research Station at Dhanbad in India. This method makes use of wire-mesh sleeve instead of the expensive metal tube to insert the cement mortar into the drill hole. The field trials confirmed that the method is cheap and an effective system of support.

Jan 1, 1972

By Mukhopadhaya K. K, Cory A. H

The concept of using travelling magnetic fields created by linear motors was stimulated by Laithwaite who advanced ideas on motors with shaded poles (Laithwaite, 1968), rack and pinion motors (Laithwaite, 1970) as well as low speed, brushless motors and three dimensional motors (Laithwaite, 1973a and 1973b).Sudan (1963) and Sundberg (1969) had applied the concept to metallurgical processes. However, the use of travelling magnetic fields has not been used widely to produce conditions for the separation of magnetic from non-magnetic minera1s or even magnetic materials from non-magnetic materials, although some attempts were made by McCarthy (1922), Davis (1934), Dean, Gottschalk and Davis (1934) and Gottschalk (1934).Laithwaite (1973, a) while working with linear motors made suggestions for designing separators and in the work described here, the observations of Laithwaite and others are extended to determine the characteristics of the motor with a view to using it as a magnetic separator.

Jan 1, 1980

By Ellis Thomson

The microscope is now used extensively not only in the examination of solid ore but also in the determination of fragmental mill products. It has therefore become a matter of paramount importance to be able to mount and polish fragmental as well as solid specimens in the easiest and most efficient way, so that the minerals present may be readily determined. In the case of the solid ore the ordinary mount of plasticine set on a glass or metal slide serves for most practical purposes. An improvement on this is furnished by the small brass container inside of which the specimen is mounted in a cementing medium of sealing wax. The latter is the method in use at Harvard University. It has the advantage of uniform height, thus obviating the necessity of a slide of any sort. It is also easily catalogued as the brass holder may be stamped with a convenient series of letters and numbers that will serve as a label. Other advantages of this type are the ease with which any particular part of the section may be re-located, the excellent storing facilities afforded by mounts of uniform size, and the possibility of polishing ten or a dozen sections at the same time by means of a holder which is placed over the polishing wheel, is geared with it, but revolves the opposite way.

Jan 1, 1926

By Nikolaus Schneider

"Abstract: The combination of failure in joints of diaphragm walls and their exposure to water pressure may have far reaching effects ranging from water leakage to the risk of catastrophic loss of stability for the retaining wall and civil structures behind it. Investigations of imperfect joints in diaphragm walls have led to the development and testing of a quality tool to monitor the joint integrity of diaphragm walls during construction. By applying independent mechanical sensors (“joint inspector”) to the steel frame of hydraulic or mechanical grabs, it is now possible to record the surface conditions of exposed primary joints during the construction of secondary panels. This allows for the implementation of corrective action during the construction process should joint quality not indicate a watertight connection to the adjacent panel. The joint inspector, used for different types of stop ends, was tested on a full scale test field at several construction sites. The implementation of this new quality tool drives a new quality standard for deep excavations in inner city areas.General introduction to diaphragm wallsDiaphragm walls are reinforced concrete elements constructed using bentonite slurry to temporarily support an open trench in the ground. They are used in two main fields of application in civil construction, as foundation elements for vertical and horizontal loads (barrettes) and as retaining walls for excavation pits.Particularly for deep excavation pits in inner city areas, diaphragm walls are used as temporary or permanent walls of retaining walls. Alternative retaining wall systems would be secant pile walls, sheet piles or soldier piles, but these have disadvantages in structural strength when compared to diaphragm walls. If the vertical load of existing buildings next to the excavation pit has to be accommodated, the most practical solution can be found using diaphragm walls supported by prestressed anchors, steel struts or slabs."

Jan 1, 2014

By Gary Cavanough

The spontaneous exothermic reaction of ammonium nitrate explosives with sulphide-containing rocks, commonly referred to as reactive ground, is a site-specific condition that can lead to spontaneous detonations. Mine sites typically carry out regular assessment of ground for reactivity. In Australia, reactive ground testing is conducted according to the Australasian Explosives Industry Safety Group (AEISG) Code of Practice. This paper presents a new method to assess reactive ground. The new method can be completed on the mine site or in the laboratory. The new method allows samples to be tested in hours not weeks, as required when using the method prescribed in the AEISG Code of Practice. The new method also provides an explanation of why ground is reactive or not reactive, Whereas the AEISG Code of Practice provides a reactive, not reactive or marginal results with no understanding of reason for these results. Case studies on the use of weathering agents, pH, sulphide content and carbonate content will be reported. These case studies identify instances where the testing as per the AEISG Code of Practice provides false positive and false negative results. A false positive result will require the use of inhibited products when they are not actually required which increases costs and reduces productivity due to the need to used multiple explosive products. A false negative result increases the risk of an unplanned initiation of a blast hole.

Feb 6, 2023