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By Gaudin. A. M., S. C. Sun

THIS paper presents the results of a study of the relationship of the electrokinetic or zeta potential to flotation phenomena. The relationship is established on the experimental evidence that mineral behavior in flotation and in cataphoresis is generally governed by the chemical properties and amount of the reagents adsorbed at mineral surfaces. Cataphoresis1-5 or electrophoresis is the name given to the movement of a charged particle in a liquid medium under the influence of an applied electric field. Mineral behavior in cataphoresis, as indicated by the magnitude and sign of its ionic charge, can be represented by the term zeta potential. In this paper, the zeta potential represents the difference in potential between the immovable liquid layer attached to the surface of a solid particle and the movable liquid layer in the body of the liquid, and is the result of the tendency of ions on the surface of the particle and within the liquid boundary layer to establish a condition of equilibrium. A high positive zeta potential means that the mineral surface is dominated by cations, a high negative zeta potential indicates domination by anions, and a low zeta potential indicates that the surface is influenced almost equally by cations and anions. In terms of observed quantities the zeta potential is given by the relation [z = 47ruu(300)$ Kx] in which z is the zeta potential expressed in in volts, u the viscosity of the solution in poises, u the velocity of particles in centimeters per second, x the impressed potential gradient in volts per centimeter, and k the dielectric constant of the solution in c.g.s. units. A convenient source for the derivation of the equation is the book by Thomas,6 The term zeta coefficient is an expression coined to denote the difference between the magnitude of the zeta potential of a mineral suspended in solution A, and that of the same mineral suspended in solution B, which consists of solution A and an additional chemical agent, but is at the same pH. For example, the difference between the zeta potential of galena particles in distilled water and that in any chemical solution at the same pH is a zeta coefficient. Or, when the zeta potential of a mineral particle is measured first in distilled water, then in a mixture of water and copper sulphate, and finally in a mix-

Jan 1, 1946

By Kenneth C. Ko

An engineering investigation was carried out on the technical and economic feasibility of implementing flexible liner/backpacking support systems In an advancing tailgate longwall mine. The system for a model mine consists of a circular tube constructed of liner plates and flyash backpacking. Flyash is pneumatically stowed into the tailgate. Small amounts of cement may be mixed to improve the support capability of the fill In difficult local ground conditions. Water is added inside the nozzle immediately prior to spraying. Results of theoretical analyses and a field test show that the designed system is technically feasible, can be cost-competitive, provides more stable ground conditions, and can Increase productivity and coal recovery, when compared with existing retreat longwall systems. In certain mine layouts, the new system can reduce the direct mining costs by a significant amount. The system would be particularly applicable to deeper coal beds with bad ground conditions.

Jan 1, 1980

By Brian W. Stump

"Seismic waves from explosions can be used to characterize physical processes in and around the source. The quantification of absolute levels of ground motion is important for minimizing impact on nearby people and structures. We contrast work in characterizing seismic radiation from contained nuclear explosions with ground motions from multiple explosion quarry blasts. A physical basedunderstanding of the explosion source function allows prediction and extrapolation to new environments where experimental data may not exist."

Jan 1, 1990

The history of soft and hard rock underground mining is blemished with regional instabilities of mine workings. Whilst the potential consequences of regional instability events are recognised to be high, there is a false perception that the probability of them occurring is very low. In fact, Australia has averaged more than one event per year for the past 20 years. At least five fatalities and over $100 million of losses have been associated with the events. As such, they are a core risk to underground mining and have a significant effect on the quadruple bottom line of business û safety, environment, community acceptance and economics. This paper explores the important roles that risk management has in reducing the probability and consequences of regional instabilities. It concludes that education and continuing professional development are essential elements for effectively managing the risk.

Jan 1, 2003

By M. J. Beus

Many mines in Canada, the United States and South Africa are reaching the hoisting limit. Very little payload will be possible without compromising safety due to the excessive weight. It has been suggested (DeLorme, 2000) that one of the most attractive concepts to enable deeper hoisting is to reduce the allowable factor of safety in the wire rope. Researchers at the Spokane Research Lab are developing new technology to improve hoisting safety and productivity by providing new monitoring and analytical tools. A Shaft Conveyance Monitoring System (SCMS) has been developed which determines hoist rope end load, true conveyance position and acceleration, and rope safety factor, as well as other hoist operating parameters. This information is transmitted to the hoist operator display 20 times per second. Recent field measurements on 45 mm (13/4 in.) diameter hoist rope indicate that dynamic forces during loading of a 9000 kg (10 ton) skip could exceed the safety factor of the rope. To improve on the current understanding of the mechanical behaviour of hoist ropes, and to help interpret the results from field-testing of the SCMS, a new approach to computer modelling of stranded wire rope is also being developed. Particle Flow Code, PFC3D (Itasca, 1999), is used to simulate the structural behaviour of wire rope and the interaction between individual strands when the rope is subjected to static and dynamic end loading. Details of the SCMS, field results from the measured rope loads, and the results of numerical modelling on the wire rope will be discussed.

Jan 1, 2002

By M. P. Hay

"For a model to be successful it must address the concerns and needs of a target audience. Further, the model must demonstrate the same patterns of behaviour as the real system, and need only be complex enough to meet this objective. If the model is too complex it can become unusable to those who need it most.With this in mind, SUPASIM has been developed for the practical metallurgist requiring only laboratory flotation rate data as input. Some 35+ successful plant simulations have been completed since 1985. The approach of SUPASIM is to characterise an ore, organise information in an understandable way and add structure to the complex flotation situation and hence support the metallurgist to interpret the relationship between variables and optimise the flotation process.The paper describes the basis on which the model was developed and sets out to provide an insight into interpreting laboratory flotation kinetics and their physical meaning in a production plant and the influence floatable gangue has on float performance and plant design. A case study illustrates how the ratio of slow floating mineral to gangue can influence circuit design and improve recovery on a plant scale.INTRODUCTIONThere is an enormous amount of useful data in the results of a laboratory scale rate test. Each variable of fraction and rate, for mineral, metal and gangue has a physical meaning in the plant. The link between float kinetics and the plant in respect of recovery, grade, pulp density, pulp flowrate, residence time, number of stages of cleaning and circuit configuration has been established by the author in the process of developing SUPASIM."

Jan 1, 2005

By N. O. Lotter

The reliability of a set of flotation results is key to minimizing project risk either at concentrator commissioning, or at the point of implementing an improvement to an existing concentrator operation. High-Confidence Flotation Testing was developed for this purpose, and is part of the list of technologies of various scales used by Xstrata Process Support (XPS) in addressing these projects. The methodology is based on two principles: one, to ensure that the ore sample is representative and has been well-blended and subsampled; two, to perform the flotation tests in sufficient numbers of replicates with appropriate quality controls, so as to improve the reproducibility of the test data. Across ten years of practice and continuous improvement with this methodology at Xstrata Process Support, Sudbury, several improvements to this method and complementary connections into sampling and quantitative mineralogy have been developed. Two case studies are reviewed. These show the capability of this system in both optimizing an existing concentrator operation and in serving a new mine scenario. Further work to improve the efficiency of this procedure has been identified.

Jan 1, 2009

By S. E. Olsen, K. Tang

The complex heterogeneous equilibria associated with the production of manganese ferroalloys have been simulated by employing recently developed thermochemical databases. The non-ideal Mn-Fe-Si-C alloy and the MnO-SiO2-Al2O3-CaO-MgO-FeO slag system have been modelled separately by the compound energy and cellular model. A large number of experimental thermodynamic and phase-equilibrium data were used to evaluate the model parameters for the liquid and solid Mn-Fe-Si-C phases. In addition to the liquid metal phase, solid mixture phases occurring in the Mn-Fe-Si-C system have also been studied. Over 500 measured equilibrium data have been utilised to verify and calibrate the model calculations. The paper will present typical simulation results, from activities of components to multicomponent heterogeneous equilibria. Good agreements can be obtained for many important technological parameters such as carbon solubility, phase relations and equilibrium diagrams, element distribution as function of temperature and slag composition etc. Application of the present models to the silicomanganese production will be demonstrated in this paper.

Jan 1, 2004

By Albert Ruiz

South Coast Water District (District) operates the Beach Interceptor Sewer Tunnel (BIST) in South Laguna, Orange County, California between Mon-arch Beach and Aliso Beach (Figure 1). The 10,424-foot long BIST houses a 24-inch Techite gravity sewer pipeline critical to the District Sanitary Sewer Collection System that conveys 1 MGD of raw sewage to a wastewater treatment plant. The original tunnel was constructed in 1954 and the sewer line replaced in 1974. Periodic inspections by sewer pipeline maintenance crews have documented deterioration of specific intervals of the tunnel within the past few years (Sancon 2003). Rotting timber supports and rock falls in the tunnel as a result of the deterioration were endangering the sewer pipeline. A 50-foot section of the tunnel was determined to be in need of immediate repairs, which were carried out from January to August in 2007. This section was enlarged to a horseshoe shape and lined with shotcrete. The pipe was encased in concrete in the invert of the new enlarged cross section. Hatch Mott Mac-Donald (HMM) designed the emergency repairs, carried out an assessment of the rest of the tunnel alignment, and is currently developing a work plan for rehabilitating the entire tunnel.

Jan 1, 2008

Although the Diamond that is cut and polished and made up into an article of jewellery, is so well known, there are, comparatively speaking, very few outside the industry who know this beautiful crystal in the crude state, as turned out ofNature's laboratory, and the means employed in winning this precious stone.This article is written with the endeavour to give the reader some idea of the geological formations in which the Diamond occurs, and as it is reported that Diamonds have been found in Western Australia, as well as in other parts of the Australian Colonies, a few hints as to the means employed in working the ground in South Africa may be of use to those intending to prqsecute the search in this country. The general geological formation of the South African Diamond Fields is Lacustrine shales and sandstones, intersected by dykes of various eruptive rocks, varying considerably in their character. and in places vesicular in texture, the vesicules being more or less filled in with zeolites by permeating waters.

By V. Bari?ic

The scheduled power cuts of early 2008 were a disturbing reminder that South Africa needs to expand its power-generating capacity. Low-grade and discard coals, of which South Africa has much, are a source of energy and amenable to combustion in circulating fluidized beds (CFBs). Foster Wheeler (FW) has a long record in developing this technology in boilers. The technology is flexible in burning a variety of fuels; low-grade, high-ash coals, good quality bituminous and anthracite coals, and biomass and waste fuels have all been used. CFB boilers are efficient, reliable and can be designed to meet tight emission standards. In recent years once-through supercritical (OTSC) CFB technology has been developed. It enables the next stage in CFB development to proceed to a medium-scale (500 MWe) utility in such projects as Lagisza, which runs at a net efficiency of nearly 44%. Scaling the technology up to 800 MWe with a net efficiency of>45% is planned to be commercial during 2009. CFB technology can reduce CO2 emissions in the repowering of coal-fired and greenfield power plants. It does so through greater efficiencies and by co-combusting coal with biomass. FW has also developed CFB technology for the gasification of biomass, as, for example, in a pressurized gasifier to produce syngas, which can be used for the production of biodiesel, thereby reducing CO2 emissions from vehicles. Carbon capture and storage (CCS) can potentially cut CO2 emissions in the generation of power from fossil fuels in the short term, provided that it gains public acceptance, that the required regulatory framework is created, and that emission-trading mechanisms or other incentives provide a solid return on the major investments required. Oxyfuel combustion is an option in CCS; Foster Wheeler is adapting its CFB combustion technology for oxy-fuel combustion to meet this challenge. It is developing Flexi-burn?, which enables a plant to be operated either with or without carbon capture. This paper describes the status of CFB technology in terms of boiler efficiency and fuel flexibility. It highlights the advantages of CFB technology for oxyfuel combustion, presents a development plan for Flexi-burn?, and discusses a pressurized gasifier for biodiesel applications.

Jan 1, 2009

By Mingju Liu

China has been suffering from coal and gas outbursts since 1950s. Nowadays, the situation has become worse than ever with the need to mine deeper coal deposits at higher production rates in a more complex underground mining environment. In the year 2006 alone, 37 outbursts occurred in underground coal mines with a death toll of 232. This paper describes a case study of an outburst event, which occurred in July 2006 during the shaft development of the Mengjin Coal Mine, Henan Province, China at a depth of 768m below surface. Detailed analysis of the possible causes that led to the occurrence of the outburst is reported. These include the study of complex geological features, gas storage conditions, possible improper technical management practice as well as incomplete prevention and control measures. Based on the case study and the observation of outburst occurrence in China in the year 2007, suggestions have been put forward to help prevent and control future coal and gas outbursts.

Jan 1, 2007

By Martti Hagfors

The Finnish Defence Forces Technical Research Centre (PVTT) studied the effect of shape of boost-er to its ability to ignite insensitive (IM) plastic bonded explosive (PBX). Therefore an explosive fac-tory produced 20 insensitive (IM) plastic bonded explosive (PBX) charges for the tests. The mass of each of the charges was exactly 9.2 kg (20.3 lb). The charges were equipped by two different type of boosters; RDX and PETN. Both the explosives contained some parts of plasticizers. The weight of all the boosters was exactly 300 g (0.66lb). On the bases of their shape, the boosters were also divid-ed into two different groups, cylindrical and “pancake”. In the middle of the “pancakes” there was also shaped a small cone in such away that the detonation could accelerate to its full speed after the charge was ignited. The following shots were exploded;

Jan 1, 2013

By David Cole, Paul Cooper, Dale Preece, Jerome Stofleth

The Explosive Destruction System (EDS) has been designed at Sandia National Laboratories for the disposal of chemical munitions (phosgene, mustard gas, sarin etc.), many dating back to World War I. EDS is a portable system that is trailer mounted and consists of a vessel into which a chemical munition can be loaded and opened for neutralization with linear and conical shaped charges. Gases are contained within the sealed chamber. The linear shaped charges split the munition in two and the conical shaped charge (CSC) is aimed at the explosive burster, in each munition, which is detonated by the resulting shaped charge jet, Toxic chemicals remaining in the vessel following detonation are neutralized and disposed of. This paper documents the development of a new CSC needed to reliably detonate explosive bursters in an expanding array of chemical munitions that are beyond what the EDS device was originally designed to eutralize. Design of this new CSC was controlled by the need to deliver energy above the detonation threshold into the explosive after penetrating the outer steel casing, fluid, the burster casing and finally the explosive. Design considerations were driven by jet conditions at the steel/explosive interface inside the burster. Parameters to consider in CSC design include: 1) diameter, 2) liner thickness, 3) liner position in body, 4) explosive weight, and 5) liner shape or interior (apex) angle. The effects of these parameters on final CSC performance are examined in detail. CSC’s that meet the design specifications have been manufactured and tested. The performance of these charges are compared with the original design requirements.

Jan 1, 2002

By B. W. Gandrud

This is the third report published by the Bureau of Mines concerning the washability of Black Creek coal. Both of the former reports5/6/ dealt with the Black Creek coal at the Bradford mine, Dixiana, Ala., near the northeastern extremity of the Warrior field, whereas the present report is based on float-and-sink tests of coal from what is presumably the Black Creek bed near the southern extremity of the field. Although the Yolande Coal & Coke Co., owners of the property at Yolanda No. 6 slope, consider this opening to be on the Black Creek bed, the authors do not feel that there is as yet positive proof that this correlation is correct. There has been little or no development of the Black Creek bed in the Yolande Basin in the past, and a posy-tine identification of the bed at Yolande No. o will have to await further exploration and development. The Yolande No. 6 is an exploration slope 3/4 mile north of Rockcastle, Ala. The slope is approximately 400 feet from top to bottom on a dip of 18° As fax as the authors can ascertain, coal has never been produced commercially from the Black Creek bed in the southwestern part of the Warrior field. Exploration work in the past has indicated that the Black Creek coal in. this area is extremely friable and high in sulfur. Extreme friability would naturally discourage its' use as a domestic and railroad fuel, and high sulfur content would be a disasvantage in its use for coking coal. The present study of this coal has been made with particular reference to sulfur elimination on the assumption that it would make a good coking coal provided enough of the sulfur could be eliminated by washing.

Jan 1, 1939

By John C. Machisak

THIS PUBLICATION presents injury experience and employment data for the nonmetal mining industry in the United States for 1960. Data for the mines and mills are presented separately, as shown in the list of tables. The Bureau of Mines is authorized to send questionnaires to the nonmetal mining industry for their voluntary submission of injury and employment data. As the information submitted contributes largely to the promotion of safety in the industry, special effort has been made to ma e these questionnaires as complete as possible.

Jan 1, 1963

By A Asadov, D Nair

This paper discusses the determination of the percentage of crystalline material in a natural silica deposit which would be considered harmful to health (<10 ¦m). A sample of the natural silica material was recovered and split into a number of subsamples. Samples were sieved using a conventional dry sieve to remove material >300 ¦m before testing. Particle size analyses of the fine fraction showed 75 per cent of the material was below 10 ¦m. Initially XRD and XPS were run on the samples to determine the minerals and composition of the sample. The XRD revealed strong quartz peaks and smaller tridymite peaks with a high amorphous background. The XPS indicated traces of iron, titanium and carbon with dominant silicon and oxygen peaks. The structure of the sample was investigated using the SEM. It was apparent that there were a number of larger quartz crystals (>30 ¦m) with a mix of amorphous and crystalline in the finer fraction. It was also observed that amorphous material was attached to the surface of the crystals. In order to determine the percentage of crystalline quartz a known amount of quartz was added to the sample incrementally. On each addition an XRD scan was performed and the area under the peaks recorded. Back analysis of these peaks with an assumed percentage of crystalline material in the original sample gave a crystalline content of 30 per cent. The quantity at the respirable fraction was estimated to be 18.7 per cent.

Jan 1, 2003

By Bill Stormes

This paper will discuss implementation of the Hilti OneStep rock anchor technology to improve face bolting operations during the May 2008 longwall move; increase rock anchor installation capacity; and improve safety by reducing employee exposure periods by utilizing the Hilti OneStep rock anchors.

Jan 1, 2008

By Earl Sweet

This overview of economic and financial market prospects examines the current and future state of the global and Canadian economies with a focus on commodities. Housing prices and global conflicts all have effects on the overall economy and metal prices and mining developments in particular. This presentation outlines where we are today and where the author and BMO see the economy moving over the next few years.

Jan 1, 2016

By S Thomson, M Lovitt, T Purvis, C te Kloot, T Nguyen, Z Liu

Ernest Henry Mine (EHM), located in north-western Queensland, is an underground copper/gold sublevel caving operation currently producing over 6 Mt/a of ore. The mass mining method of sublevel caving (SLC) used at EHM involves systematically blasting a series of uphole rings in parallel ore drives and drawing the broken ore using a top-down approach. Each ore drive contains multiple precharged rings to prevent having to charge in close proximity to the brow of the previously fired ring; however, the current initiation system still involves ‘hooking up’ all detonator lead cords of the first precharged ring. The unstable nature of a rill and working close to a brow presents hazards to personnel completing the hook-up process. There is also a business risk of ore loss when damaged ground support completely prevents access to the next precharged ring. If the hook-up step could be eliminated, the risk to personnel and the business would be significantly reduced.EHM engaged Orica Mining Services in 2016 to trial their WebGenTM 100 – wireless electronic blasting system (WEBSTM) for the first time in an underground mining environment. Having successfully signal-tested the equipment, two test holes were initiated, followed by a single production ring and then multiple production rings. In total, 30 production rings were successfully fired underground at EHM in 2017. To do this, WEBSTM was successfully integrated into EHM’s current charging and firing process, resulting in no business delays or loss to production. None of the 30 rings required hooking up and all were initiated from the surface with no personnel underground. A high level of ownership from all personnel involved ensured the trial was a success, and provided scope for wireless detonators to be used successfully on a large scale – both at EHM and other sublevel caving operations. WEBSTM is now a proven example of technology that can be used to improve safety in the mining industry, through eliminating the need for personnel to work in hazardous areas.CITATION:te Kloot, C, Liu, Z, Purvis, T, Thomson, S, Lovitt, M and Nguyen, T, 2017. Improving safety through technology – Orica wireless electronic blasting system trials at Ernest Henry Mine, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 39–50 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017