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Smarter Gravity Separation Using the Kelsey Centrifugal Jig With relatively coarse grained and easy-to-process ore sources rapidly dwindling, smarter techniques are becoming more necessary for the continued success of mineral processing operations, while increasing environmental pressures also require more environmentally friendly solutions. Gravity concentration has long been employed to pre-concentrate minerals using water, reducing or eliminating the need for less environmentally friendly processing techniques such as flotation. Conventional gravity recovery devices however, operate in a 1 g environment with limited efficiency in the separation of fine particles of heavy and gangue minerals. More recently developed centrifugal concentrators operate in a multi-g environment and enable finer heavy minerals to be recovered, but also exhibit limited separation efficiency due to the separations being based on solid particle mass differentials. Further enhancement of gravity separation has been achieved using the Kelsey Centrifugal Jig (KCJ), which also operates in a multi-g environment, but separates minerals on the basis of specific gravity differentials, using 'ragging' media and a pulsation mechanism, which maximises the effect of differential particle accelerations. This enables the efficient separation/recovery of minerals down to a particle size of ~6 ¦m and/or separation of minerals with a low specific gravity differential. This paper presents details on the principals of operation of the KCJ, recent improvements in the technology and recent developments in modular KCJ plants, as well as some KCJ application areas, which offer smarter, environmentally friendly processing opportunities for the mineral processing industry.

Sep 13, 2010

By Peter Swanson

One of the primary methods for analyzing roof stability in underground mines is the age-old method of “roof sounding” where a miner taps on the roof and listens for the hollow sound of loose blocks of rock. This paper looks at the feasibility of using noncontact laser-based vibration measurements to detect roof fall hazards with the ultimate vision of improving, expanding and automating procedures for mine roof inspection. Vibration measurements made on loose blocks of rock in underground mines are summarized and compared to estimates of fundamental resonance frequencies for rock slabs of the size responsible for highly hazardous “skin failures.” Both laser Doppler vibrometry and full-field interferometric methods are examined and are considered to be feasible methods for detecting anomalous vibrations in loose roof rocks. Results from simple laboratory experiments using laser vibrometry demonstrate some of the proposed application concepts. While considered a challenge to move these techniques from the laboratory to heavy industrial or outdoor environments, the potential for success in the current application is enhanced by the reduced requirements of qualitative analyses.

By James F. Kvitkovich, George V. Weisdack

Longwall mining techniques were introduced into U.S. bituminous coal mining operations in the early 1960s. These techniques were gradually adopted by many mines during the 1970s. By 1983, considered to be the peak of the longwall mine census, there were 118 active longwall faces in 79 coal mines throughout the United States. Beginning in 1984, longwall faces began a decline in numbers that has continued to the present day (Fig. 1). The geographic distribution of longwall faces today is shown in Fig.2 according to region. A breakdown of recent longwall mine production by region is shown in Table 1. An approximate breakdown of present longwall face installations by product (metallurgical and steam) is shown in Table 2.

Jan 1, 2005

By S. J. Benson

The Harts Range deposit, owned by Olympia Resources is located some 130 kms northeast of Alice Springs, in central Australia (part of Australia’s Northern Territory). The core economic minerals here are industrial grade garnet and alumino magnesio hornblende (AMH). The resource contains an estimated 2.3 million tonnes of recoverable garnet and 6.2 million tonnes of recoverable AMH, making Harts Range one of the most significant abrasive medium deposits in the world. Part of the general marketing axiom of Olympia Resources is to make high quality products from the garnet and also a special series of blended garnet/AMH products to match the needs for other sectors of industry. The deposit mineralization is of alluvial origin and thus, requires no significant liberation regimes. Over 50% of the head feed is in the form of SiO2/quartz and as much as 17% is –63micron clay slimes and mica. Original pilot scale testwork for flowsheet development centred around fairly conventional wet gravity systems, with spiral concentrators being the pre-eminent separating device. To a point, this type of flowsheet was going to achieve some of the aims albeit fairly predictably. The one area that this circuit would be very limited though is in the recovery of the very coarsest of the medium SG minerals. This was going to be a very important and longer-term costly flaw. Amongst the highest demand, greatest value of products to be produced will be the range of garnet & AMH in the +600 microns sector. A flowsheet dominated by spirals would be fated to forfeit a significant proportion of these coarse minerals to tails. At the Outokumpu Technology P/L test facilities in Perth, testwork was conducted using a pilot scale Floatex® Density Separator, the LPF-230 model. Using a twin stage approach, whereby a primary Floatex® underflow reports directly to a secondary Floatex®, recovery of the economically important +600 micron garnet was increased from 65% in the spirals-only flowsheet to 95% using the Floatex® based flowsheet. Finally, the other significant aspect of this approach is in substantial simplification of the circuit required and a huge reduction in plant footprint. Also, the nature of using hindered settling provides substantial opportunities for process control and automation.

Jan 1, 2005

By J. M. Ortiz

Mineral resource evaluation requires defining geological domains that differentiate the types of mineralogy, alteration and lithology. Usual practice is to consider the domain boundaries as hard, i.e. data from across the boundaries are disregarded when estimating the grades within a given domain. This practice may hinder the quality of the estimates when a significant spatial correlation of the grades exists across the domain boundaries. In this paper, several geostatistical methodologies to handle soft geological boundaries are compared through a case study on a copper mine in Chile. The estimation methods considered are: ordinary kriging using hard boundaries between geological domains; ordinary kriging omitting the geological boundaries; traditional and standardized ordinary cokriging of the grades assayed in different domains; ordinary kriging within dilated geological domains, that is, incorporating samples from adjacent domains up to a given radius from the boundary of the domain being considered. The estimations are performed using a set of exploration data (drill hole samples) and are validated using a set of production data (blast hole samples collected for grade control). Results indicate that kriging with dilated domains performs better than ordinary kriging using hard boundaries or no boundaries and better than the ordinary cokriging approaches. It therefore appears as a simple alternative to global kriging (without considering the geological domains) and allows accounting for changes in the grade average, dispersion and spatial continuity with the geological characteristics of the deposit, via the use of grade variograms proper to each geological domain. The maximal distance for searching samples from adjacent domains should be chosen according to the spatial correlation of the grades across the domain boundaries, or via a cross-validation at an early stage of the mine or a jack-knife if production data are available. Keywords: Kriging; cokriging; soft boundaries; hard boundaries; geological control; geological domains.

Jan 1, 2006

By Linneas W. Laage

MFIRE is a computer simulation program that performs normal ventilation network planning calculations, and dynamic transient state simulation of ventilation networks under a variety of conditions. The program is useful for the analysis of ventilation networks under thermal and mechanical influence. MFIRE simulates a mine's ventilation system and its response to altered ventilation parameters, external influences such as temperatures, and internal influences such as fires. Extensive output enables detailed quantitative analysis of the effects of the proposed alteration to the ventilation system Network simulation using digital computers has become widespread throughout the mining industry in recent years. However, as the sophistication of the simulator increases (MFIRE, for example), the complexity of input data requirements and interpretations of results requires more skill and knowledge from the users. Perhaps the most difficult part of using MFIRE is to construct the data set describing the mine's physical layout and its ventilation properties. The initial attempts to get the data set running often reveal unknown or ignored aspects of the mine's ventilation.

Jan 1, 1995

By G Siboni, A Correa De Araujo, M Gotelip Barbosa, M J. Venturini

In support of the development of its Liberian iron ore project, ArcelorMittal Mining Research and Development (AM Mining R&D) has performed characterisation and beneficiation test work on drill core samples received from the proposed mine area. In addition to this, a sinter feed product was composed by blending and processing the drill cores in order to predict sintering performance of the ore. This article presents the methodology used to prepare the drill core blend for characterisation, as well as describe the sinter pot trial. The results are presented, demonstrating how important this type of study is for the development of an iron ore deposit.CITATION:Gotelip Barbosa, M, Siboni, G, Venturini, M J and Correa de Araujo, A, 2017. The use of drill core blends to predict sintering performance, in Proceedings Iron Ore 2017, pp 297–302 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By Mark R. Svinkin

Regulations are needed to keep construction vibrations in tolerable limits. The existing regulations were developed for low-rise residential structures, but they are incorrectly used for different super and underground structures. The existing regulations cannot prevent most of harmful vibration effects on sensitive devices, people and structures from construction and industrial vibration sources. It is important to determine the areas of application of the existing regulations and bring attention to the necessity of measurement of the structural responses for assessment of vibration effects on structures. For multi-story residential, commercial and industrial buildings, the frequency-independent safe limit of 51 mm/s (2 in./s) can be chosen for the peak particle velocity of structural, not ground, vibrations. Specifications for construction operations with dynamic sources have to consider specifics of each construction site. Preventive measures can be used to mitigate harmful vibration effects on various structures and settlements in sand and clay soils.

Jan 1, 2006

By J. Wickens

Haile Gold Mine is located near Kershaw, South Carolina, approximately 50 miles south of Charlotte, North Carolina. Gold was first discovered at the site in 1827, and the property has been through several operating periods since. The relatively low grade and refractory nature of the deposit has been a challenge for efficient processing since the start of mining on the property. Early processing techniques included gravity separation and barrel chlorination. The last operation employed heap leaching in 1985 through 1992. After being closed and reclaimed for over 20 years, the property is poised to re-open and produce once again. In this chapter of the Mine?s legacy, flotation and ultra-fine grinding will be employed to achieve economic extraction of gold and silver from the pyrite. This paper briefly reviews some of the mine?s history, the metallurgical testing, the flowsheet and discusses design considerations. KEY WORDS: process plant, flash flotation, leaching, SMD, stirred media detritor

Feb 27, 2013

By P. Anyon

Exposure to the microscopic particles in diesel engine exhaust can lead to serious health problems, including the incidence of cancers, heart disease and increased susceptibility to respiratory ailments such as pneumonia, bronchitis, and asthma. In Australia, mining companies and state government authorities are actively responding to this major occupational health and safety issue. Their initiatives place considerable emphasis on routine monitoring of diesel particle matter (DPM) exhaust emissions, both for engine benchmarking and as a part of routine engine maintenance. Implementation strategies follow two complementary paths: determination of individual engines? emission signatures combined with periodic engine re-certification; and co-operatively agreed industry-government engine maintenance programs, which are subject to audit. Both strategies place heavy reliance on real-time measurement of DPM concentrations in engine exhaust, using ruggedized instrumentation, mainly based on laser light scattering photometry. Adding value to this cooperative approach, industry has also collectively funded a government agency to design and manage a database, into which the results of all-routine DPM testing can be uploaded directly by individual mines. This win-win outcome is a great example of how cooperative action between governments and industry can deliver the goods: in this case, a safer working environment, more efficient energy use and the capacity to benchmark performance with industry peers.

Jan 1, 2009

By A. Bobet

Design of a new underground laboratory is underway through the auspices of the United States National Science Foundation. The Deep Underground Science and Engineering Laboratory (DUSEL) is scoped to provide a diverse group of researchers with a dedicated underground facility capable of supporting a broad spectrum of fundamental and applied research at depth in the Earth?s crust. Key research partners in the endeavor are physicists, biologists, geoscientists and engineers. Engineers are not only designing the underground facilities, but are also actively involved in developing research initiatives. This paper will introduce the DUSEL engineering research program to the mining community, provide an overview of the site, geology, and laboratory facilities, and describe some key program initiatives. The particular technical challenges and opportunities afforded by the construction of DUSEL and the performance of the integrated science-engineering program will be discussed by reference to a subset of research initiatives that are currently under development: Cavern Design, CO2 Sequestration and Transparent Earth. These research initiatives target the development of new techniques that can support improved subsurface investigation, design and construction procedures. An increased use of the subsurface can actively contribute to the development of new, more sustainable solutions for use in mining and civil engineering practice.

Jan 1, 2011

By J. Golamnejad

This paper attempts to model long-term production scheduling problems by chance constrained binary integer programming in a stochastic environment. This stochastic model is set up to account for ore block grade uncertainty. The probability distribution function of grade in each block is used as a stochastic input to the optimization model. This distribution function in each block should be determined using a Geostatistical Simulation approach. The deterministic equivalents of these chance constraints are then achieved, which are in the form of nonlinear in binary variables. A confidence level at which it is desired that the uncertain constraints holds, is specified in each scheduling period. Rather than the previous risk-based model, this formulation will yield schedules with a high chance of achieving planned production targets while maximizes the expectation of net present value and minimizing the variance function simultaneously. Using this method, the grade uncertainty is integrated explicitly into the optimization process.

Jan 1, 2006

By Shane McDonald

Australia produces approximately 84 million tonnes of coal per annum from 30 longwalls in New South Wales and Queensland, operating at an average depth of around 300m. Industry trends and expectations place increasing emphasis on the reliability of these operations; for example, the current average face width is 245m and this is expected to increase to approximately 270m by 2010. In recent years, Beltana No.1 Mine has consistently been Australia?s highest longwall producer, with ROM output of 7.2Mt in YEJ2007. Strata management has become a key feature of the operation of Australia?s longwall mines, as a tool to manage variances in the geotechnical environment. This involves an understanding of the impacts of the geotechnical environment on ground behaviour and the implications for mine design, stability and associated support, interaction and horizon selection. The anticipated ground control impacts of these factors form the assumptions that drive the format of plans specifying both triggers and actions, with quantified, monitoring-focussed experience used to refine the plan in a continuous improvement (ie ?plan-do-check-act?) process. This paper summarises the Beltana No.1 Mine strata management methodology and experience to-date.

Jan 1, 2008

Your assessment of the minerals business. I would first like to express our profound sadness and sincere condolences to the families of the miners who lost their lives in recent mine mishaps particularly in West Virginia, and other locations. Any loss is unacceptable. It is time to review and, if required, re-establish a rigorous health and safety agenda in the mines. It must involve a review of health and safety regulations. And innovative training methods for sensing, awareness and mitigation of health and safety hazards must be developed. As far as the minerals business is concerned, I am excited about the outlook for mining. Over the last 20 years, global demand for minerals has closely mirrored the growth of the gross domestic product. Minerals re-main a major part of the world’s economic foundation. And that will continue to be the case. It is no surprise that the fortunes of the mining industry rise and fall with general economic trends. Globally, mining has been strong — thanks to the explosive economic growth in Asia. The U.S. mining industry has performed reasonably well, with notable strength in the metals, coal and construction and aggregate areas and with some softness in the industrial minerals sector.

Jan 1, 2006

By G. Noce

The ever more present necessity for greater precision in foundation structures on vertical piles subject to horizontal forces applied to the heads, in the light of of the latest knowledge about the elastic-plastic behaviour of the soil has led to the use of numerical calculation for the formulation of a general resolution method for the problem. The calculation method that will be set out, applicable to piles with inertia moments variable discreetly along their axes is especially useful when studying steel structures for medium and large tonnage vessels for which the metal piles are often constructed for the assembly of section of equal external diameter but different thickness and therefore different inertia moments. Two examples are given of constructions whose foundations have been projected with these calculation tools, one in the railway sector (foundation pile for the river Nera viaduct - Italy) important for the limitation of horizontal relative deck displacement, the other maritime (Dolphins of the petroleum pier of the port of Bandar Abbas - Iran).

Jan 1, 1989

Electro-Flotation Research on Fine Cassiterite

Sep 13, 2010

Ferrochrome is the major chromium source for stainless steel production, and submerged-arc furnaces (SAF) are most commonly utilised to smelt chromite ores into ferrochrome by using suitable carbonaceous reductants such as coke. Because of the complexity of feed structure and electrical-thermal-chemical interactions, there exist large gradients and wide distributions of temperature, mineralogy and other process variables in the furnace. This leads to various zones in the furnace, and different reduction mechanisms. Control of the furnace is thus often difficult due to the complicated physical and chemical situations in the furnace. The temperature profile in the submerged arc furnace has a great influence on the reduction rate and the production efficiency. Therefore, the energy generation through electrical arcs submerged in the solid feed and its distribution within the packed bed play an important role. In the present paper, an overall process model is illustrated to simulate inter-linked transport processes of fluid flow, heat transfer and reduction kinetics within the submerged arc furnace. The application of reaction kinetic data to simulate the chromite pellet/lumpy ore reduction with CO gas is presented and further adjusted to provide a submodel for a flow and heat transfer simulation for the packed bed by using computational fluid dynamics (CFD) technique. The comprehensive process model is aimed to simulate materials and gas flow, temperature and energy distribution throughout the furnace system. A preliminary model for gas flow and temperature distribution for the upper part of a 20 MW furnace (the packed bed) for high carbon ferrochrome production has been developed under simplified conditions. The integration of the reaction kinetic model into process simulation, and the future vision for a more comprehensive process modelling are discussed. It is expected that better understanding of the furnace insights through process modelling will help process optimisation and furnace control.

Jan 1, 2004

Paper written on project work carried out in partial fulfilment of B. Eng (Metallurgical Engineering) degree Electrowinning is an attractive method to recover gold from the relatively concentrated aurodicyanide solutions produced by the elution of loaded carbon, provided that the plated gold can be easily removed using high pressure water sprays. In practice, difficulty with the removal of the gold is occasionally experienced and has been correlated with the presence of high concentrations of copper in the eluate. In this work, the influence of copper on the electro-plating of gold was further investigated using a laboratory electrowinning cell with a rotating disc cathode, polarization, and adhesion tests. It was found that the reduction of copper will compete with gold electrowinning at high copper tenors and that the adhesion of the precipitated gold is also increased under these conditions. Keywords: reduction, adhesion, morphology, current efficiency, limiting current.

Jan 1, 2004

By H. H. Fields

The Bureau of Mines conducted research to determine the effectiveness of long holes drilled in solid virgin coal in degasifying an area of the Pittsburgh coalbed showing that horizontal holes drilled into a virgin coalbed from the bottom of any shaft will effectively remove methane gas in commercial quantities from the Pittsburgh coalbed. The in situ pressure at a depth of 214 feet into the coalbed and the average gas and water flows from the five degasification holes were 3 lb/in2 gage and 860,000 ft3/d and 1.7 gal/min, respectively. On June 19, 1975, after 593 days of degasification, a compressor was installed and pipeline quality gas was introduced into a commercial pipeline. As of June 1, 1976, after 1,022 days of degasification, over 753 million cubic feet of gas had been drained and 117 million cubic feet of gas had been purchased by the gas company for use in the local community of Wadestown, W. Va. The gas drained to date is six times the gas estimated to be in the area subtended by the holes. Methane emissions at the working face of 1 West mains, Federal No.2 mine has been reduced by 50 pct, proving the value of methane drainage by horizontal degasification holes drilled from shaft bottoms ahead of mining.

Jan 1, 1976

By JO Choi

Jet-grouting method is a useful technique to reinforce foundations on relatively soft or vulnerable soil layers such as fractured zone and stratum with cavities. Although jet-grouting has been widely applied to various field works, a reliable design standard has not been established yet. A number of model tests were performed to investigate end bearing behaviors of piles reinforced by jet-grouting. It was concluded that end bearing capacity was increased in proportion to uniaxial compressive strength of grout column. Based on the test results, the design criteria for the end bearing capacity were suggested.

Jan 1, 2006