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By M. Copeland

Phase relations of gadolinium alloyed, up to 40 weight-percent (wt pct), with AISI 304-type stainless steel were established. Body-and face-centered cubic iron-rich solid solution phases and several intermetallic gadolinium-containing compounds of variable composition that approximated the formulas Fe9Gd, Ni7Gd2, Ni3Gd, Fe2Gd, NiGd, and NiGd3 were identified. The intermetallic phases Fe9Gd and Ni7Gd2 were noted to melt at about 1,080° C at about 0 to 2 wt pct gadolinium. The melting temperature of Fe9Gd increased with increas-ing gadolinium content to a plateau at about 1,230°C and 30 wt pct gadolinium, and the melting point of Ni7Gd2 decreased to a plateau at 900° C and 30 wt pct gadolinium where Ni3Gd, NiGd, and Fe2Gd coexist. Body-centered cubic iron solid solution was stable from 1 to 2 wt pct gadolinium to higher contents, 30 wt pct gadolinium or possibly more, and face-centered cubic iron up to 12 wt pct gadolinium below 1,200° C. The stability of these phases above 1,200° C was not resolved except for the mel points. A limited number of fabrication variables as well as mechanical and corrosion properties of alloys containing up to 5 wt pct gadolinium were studied. Equilibrating and forming operations were best conducted at about 940° to 1,080° C. Some variability in the yield and tensile strengths of alloys was noted; however, there was a continual decrease in ductility and impact resistance with increasing gadolinium contents. The resistance of gadolinium alloys to corrosion in water at 354° C was about the same as stainless steel.

Jan 1, 1965

By Sarma S. Kanchibotla

In overburden cast blasting the explosive energy is used to move a significant percentage of overburden from the high wall to the spoil pile thus reducing the amount of material to be handled by machinery. However, the obvious trade-off between the extra explosive energy in the cast blast versus reduced dragline effort is complicated by an increased risk of damage to the underlying coal. This damage may not be obvious but inevitably leads to reduced coal recovery and may negate much of the benefit sought from cast blasting.

Jan 1, 1999

By David Hake, David Salisbury

The Drainage Services Department (DSD) of the Hong Kong SAR Government commissioned the design and construction of the West Kowloon Drainage Improvement, Stage 2, Phase 2, Kai Tak Transfer Scheme (KTTS) project in 2000 to relieve potential flooding in Mong Kok caused by the insufficient capacity of the existing storm water drainage system. The KTTS involves construction of a 1.5km,4.4m drainage tunnel and a 450m long box culvert, running from Waterloo Road near Hereford Road to the existing Kai Tak Nullah in San Po Kong. This paper describes the design and construction of; the bored tunnel through both hard rock and soft ground using a slurry Tunnel Boring Machine (TBM), six associated access shafts, a connection structure at Waterloo Road and the box culvert connecting the bored tunnel to the outfall at Kai Tak nullah. Details will be provided on the contractor’s alternative designs adopted during the contract including the use of fibre reinforced shotcrete as one-pass temporary and permanent support for three of the shafts and modifications to the Engineer’s design for the box culvert structure.

Jan 1, 2005

Pipe Flow Stability of Concentrated Coal-Water Suspensions in the Presence of an Electric Field

Sep 13, 2010

By Robert A. Field

Static-Load Piledriving utilizes a hydraulic push to facilitate the installation of a pile. The pile is not rotated, impacted or vibrated. A smooth pushing force advances the pile incrementally into the ground. Static-Load devices must have a reaction mass to push against. The most simple form of a Static-Load device is a jack; more advanced equipment, such as the Still Worker, also utilizes this approach. This paper focuses on the use of the Still Worker on three challenging projects. In each case, the existing site conditions made it risky, or unattractive, to utilize conventional impact, vibratory, or drilled-shaft equipment.

Jan 1, 1997

By S Robotham, P C. Stewart, K Maher

A data science based dilution study was conducted to identify the causes of dilution at South32’s Cannington Mine (Cannington), a large open stoping operation. In terms of industry benchmarks for unplanned dilution, Cannington is already performing very well, and so opportunities for improvement are more difficult to identify. The study is based upon back analysis of nearly 150 case studies from the mines reconciliation database, and has quantified the relative effect and significance levels for the following dilution parameters; time until paste filling, faulting and cable bolt reinforcement. Specifically, significant contributions were associated with faults and stope open duration. Quantifying the effect of faults on stability graph accuracy enabled a site specific adjustment to improve the predictive ability of the Cannington stability graph (unstable stope specificity improved from 63 per cent to 74 per cent). Despite Cannington’s already high levels of stope performance compared to industry benchmarks, data science methods have identified a complex interaction between identified dilution factors (ie stope open duration, presence of faults and cablebolting). Specifically, a third order Factorial ANOVA (Analysis of Variance) provided evidence that stope open duration reduces the effectiveness of cable bolts in faulted ground (average dilution = 2.1 m, p-value = 0.13). These results are consistent with site observations of a relationship between the stope open duration and the extent of failure when unravelling on a fault, even when cables are present.CITATION:Maher, K, Stewart, P C and Robotham, S, 2016. A data science approach to identifying and quantifying causes of dilution at Cannington Mine, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 491–500 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By Kira Mizell, James R. Hein, Tracy Conrad

"The Ninetyeast Ridge (NER) extends roughly N-S as a topographic feature for 5000 km, from 31° south to 10° north (Fig. 1) where it becomes buried beneath the Bengal Fan at its northern end. These two geographic characteristics make the NER an ideal natural laboratory for determining the influence of latitude and terrestrial input to ferromanganese (Fe-Mn) crust formation and composition. In addition to study of geographic controls on crust composition, the NER is the largest feature in the Indian Ocean that may host crusts of economic interest.Crusts were collected from 9 of 33 dredge sites from 1.4° north to 26° south latitudes during the 2007 R.V. Roger Revelle Knox06 cruise. Nineteen samples were analyzed for 69 elements each. Nine bulk crusts and 10 layers from four crusts were analyzed. Three of the crusts sub-sampled for layers did not have the bulk crust analyzed and the weighted means for those layers were calculated to obtain bulk compositions. One sample was left out of the statistical analyses because it is phosphatized and chemically quite different from the other samples (Table 1).In order to determine changes in composition with latitude, Pearson product-moment correlation coefficients were calculated for the chemical dataset and latitude of dredge sites, as well as water depth. At the 95-99% confidence level, the following elements increase in crusts moving north along the NER: Mg, Ti, S, Cd, Ni, Tl, Mn, Ba, Co, Cu, In, Li, and Zn; and the following elements decrease northward: Fe, Fe/Mn, P, As, Sc, the rare earth elements plus yttrium (REY), Bi, Ge, and Pb. These correlations indicate that the iron oxyhydroxide component and its associated elements are more prevalent to the south, and the manganese-oxide phase and associated elements increase toward the north end of the NER. This change occurs between dredges D20 and D14 (Fig. 1), with crusts from D20 and south having Fe/Mn !1.0 and those north of D20 ""1.2, with the exception of the phosphatized crust. Crust composition also changes with water depth: Th, Ge, Pb, and the middle rare earth elements (REEs) increase with increasing water depth. Thorium commonly increases in deeper water crusts, which explains the higher Th concentrations in Atlantic and Indian ocean crusts in general compared with Pacific crusts (Fig. 2 and Hein et al., 2012), including the samples analyzed here with a mean water depth of 3584 m. However, water depth does not explain the latitudinal changes because the mean water depths of samples along the northern and southern segments of the NER are roughly comparable. Surprisingly, Si and Al, representing the aluminosilicate/detrital phase, do not correlate with latitude; that is as the ridge approaches and is buried by the Bengal Fan the Si and Al contents do not increase. However, overall, Si and Al have higher concentrations in NER crusts than in central Pacific crusts. Ba can be used as a proxy for primary productivity and statistically does increase to the north along the ridge in the direction of the equatorial zone of high biological productivity. Correlations of Mg, Li, and Zn with latitude may also reflect increased primary productivity at lower latitudes."

Sep 1, 2014

By D Chalmers, C R. Ward, B B. Beamish

Coal workers’ pneumoconiosis (CWP) has re-emerged as a major concern in the Australian coal mining industry. Harmful effects from coal dust inhalation have been well documented, but the underlying causes and mechanisms of CWP are still debatable. Research conducted in the USA has proposed a plausible link between the presence of pyrite in coal and the prevalence of CWP. Reactive pyrite in coal oxidises under ambient mine conditions to produce various iron sulfate minerals such as melanterite, rozenite, roemerite and szomolnokite. Rapid reaction rates are promoted by the form (size and morphology) of the reactive pyrite present, which provides both increased surface area and increased porosity for easy air access to reaction sites. The products formed from reactive pyrite oxidation are often needle-like crystals with thicknesses in the order of 1–2 µm (eg melanterite and rozenite) and prismatic crystals with thicknesses less than 5 µm (eg roemerite) have been recorded. The densities of these minerals are significantly less than quartz, which makes them prone to becoming airborne with the normal coal dust. In fact, the mix of these mineral salts is commonly referred to as ‘fairy dust’ by mine workers due to the way they can become entrained and sparkle in the mine ventilation air, particularly if they occur in the upper part of a seam that is forming a coal roof. Examples are presented of the various products of reactive pyrite oxidation found in three Australian coal samples, which provide evidence of the physical and chemical mechanisms that would support the USA findings, particularly in terms of a source of bioavailable iron leading to increased inflammatory stress response.CITATION:Beamish, B B, Ward, C R and Chalmers, D, 2017. Products of reactive pyrite oxidation in the mine environment – implications for coal workers’ pneumoconiosis, in Proceedings Australian Mine Vent Conference 2017, pp 87–92 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

By A. George Stern

The literature dealing with the drilling of oil wells has become extensive during the last few years, and oil men can find much information relating to drilling muds in the technical literature of the petroleum industry. Although large tonnages of clay are used in preparing drilling mud (also known as drilling fluid), almost no information has been published to apprise the clay industry of the types of minerals used, with their requirements and limitations. It is from this point of view that the present report has been prepared.

Jan 1, 1941

By D. P. Roberts

This paper reviews the use of crush pillars on mines in the Bushveld Complex and the Witwatersrand Supergroup. Stress measurements were undertaken in order to determine the residual strength of these crush pillars. The results from these stress measurements are compared with previous attempts to determine the residual strength of crush pillars using back analysis. It is concluded that the residual strength of such crush pillars lies in a band between 13 MPa and 25MPa. Using the data from the stress measurements, as well as published and unpublished data, a stress-strain curve for a crush pillar with a width-to-height ratio of 2:1 is proposed. Where further work is required, this is indicated in the text.

Jan 1, 2005

By Jury P. Nazarov

"At present the traditional study of crystal lattices of nmerials in a topic “flota tion mineralogy ” is used up. The present investigation is development of the a sclsical approaches to t he analy sis of ideal crystal lattices and f ormation on the basic obtained results of consultation, having practical chara cter.The strategy of develop ment floatation reagents i s offered, which basic pr inciple – complementary assembling m olecules forming surface co mpounds so thatth e steric charact eristic of the “visitor "" (of a polar gro up of molecule SAS) corresponded to the st er ic requirements of the ""o wner"" (elementary cell of a mineral), or coincided inter molecular cavities). In itsh case process of for mation of surface com pounds ca n be considered(a first approximation) as a realization of a principle of the design er "" LEGO "".The approach, which basic idea consi deration actioonf reactant ions and ions of ele mentary cell as three-di mensional objects is developed. And at suchp paroach the laws of a ster eometry - laws describin g spatial effect s are applicable. Thus it is possible toconsider a miner al surface as a mat r ix - basis for formation of the requirem ents to polar group of a molleec cuollector, and or (it is possible) depressant. As a whole approach represents a generalized principle double com plementation, enveloping both power, and geometric asp ects (concept ""lock "" and “key "" - spatial conform ity. Figure 7 (left). Fragment of a crystal lat tice of ap atite. Oleic acid ions interact on ly with th e calcium cations locate d on a long axi s of an elementary c ell. Magenta colour represe nts the calciu m cations, which are n ot particip atin g in interactio n, as th e degree of screening by ions neighbours exceeds 1.Figure 2. (right)The illustration of space complementary. “Afterbuilding” an elementary cell of apatite (radical PO4) related molecules of the visitor – alkyl phosphate (polar group PO4). Cations of calcium are not shown."

Jan 1, 2003

By M. Ganster, H. Krenn

The mission of the project is the fast and cost-effective rehabilitation of decommissioned lignite mining and coal upgrading facilities. This is necessary to ensure the successful future utilization of these sites. On the one hand, for founding new industrial and commercial facilities and on the other hand for touristic activities.

Jan 1, 2013

It is widely accepted that particles stabilise flotation froths and that stable froths result in improved flotation performance. Predicting the effect of particle addition on froth stability is, however, challenging. Dynamic surface tension measurement using maximum bubble pressure presents an attractive technique to investigate the effect of surfactant and particles at the air-water interface. The range of bubble lifetimes that can be studied (typically 0.1 to 60 s) is analogous to variations in air rate in flotation cells, and the corresponding changes in surface tension give an indication to the diffusion and adsorption rates of particles at the interface. In this paper, we use dynamic surface tension measurements to investigate the effect of particles on bubble surfaces at the microscale and link this to bulk froth stability measurements carried out using a froth column. Using the maximum bubble pressure method, the results show that the addition of particles results in lower surface tension, both at the dynamic (i.e. short) bubble lifetimes and towards equilibrium (i.e. 60 s bubble lifetime). This corresponds with the bulk froth stability measurements, where the three-phase system yielded more stable froths than the surfactant only system. Furthermore, increased particle loading at the air-water interface, whether through higher surfactant concentrations or lower air rates (longer bubble lifetimes), gave lower surface tension and higher froth stability. This demonstrates the link between bubble loading and froth stability. It is proposed that the maximum bubble pressure technique can be used to predict froth stability for two- and three-phase systems, enabling the effect of particle loading to be accounted for and quantified. Moreover, the technique has the potential to allow rapid determination of particle and surfactant diffusion at the air-water interface and prediction of the corresponding effect on bulk froth behaviour.

By S. Frimpong

The cable shovel excavator is used for primary production in many surface mining operations. A major problem in shovel excavation is the variability of material diggability, resulting in varying mechanical energy input and stress loading of shovel dipper-and-tooth assembly across the working bench. This variability has a huge impact on the shovel dipper and tooth assembly in hard formations. In addition, the geometrical constraints within the working environment impose production limitations resulting in low production efficiency and high operating costs. A potential solution to the above problems is the application of an intelligent cable shovel excavation(ICSE) technology. In this paper, dynamic models of the cable shovel excavator are developed with numerical examples. These models form the basis for developing dynamic shovel simulators for an intelligent shovel excavation technology. The dynamic equations are developed using the Newton-Euler techniques. The path trajectories for efficient excavation, dynamic velocity and acceleration profiles, and dimensioned parameters for optimum feed force, torques and momentum of shovel boom-bucket assembly are modeled and used for efficient excavation. The optimum digging forces and resistances for the cable shovel excavator are modeled and used to predict optimum excavation performance.

Jan 1, 2003

By Bassam Kattaa

"Abstract - A heavy mineral survey of beach and dune sands including geochemical analysis for trace elements was undertaken to evaluate the economic potential of the sands and to understand the nature and distribution of the heavy minerals relative to potential source rocks. Results indicate that heavy minerals are generally derived from outcropping volcanic rocks that comprise a proportion of the hinterland in the south part of our survey area. The most abundant minerals are magnetite and pyroxene. The morphologies of the heavy mineral grains are angular to subangular, suggesting that they were transported short distances from the source rocks. Factors controlling heavy mineral distributions include wave and wind action, proximity to provenance, the fluvial drainage network, and longshore currrents.The most economically important mineral is ilmenite. Zircon and rutile concentrations are relatively minor and thus have lower economic potential."

Jan 1, 2002

By E Villaescusa, C Drover

Fully resin encapsulated threaded bar and cement grouted cable bolts are common forms of reinforcement for underground mining excavations constructed at great depth. These elements are frequently installed to dissipate the dynamic loads caused by violent rock mass failure mechanisms. Failure of the ground support scheme without rupture of the reinforcement elements implies that the maximum energy dissipation capacity of the scheme was not utilised. The ground support damage mechanisms are useful to identify in this context as they reveal vulnerabilities which limit the scheme performance. This paper presents a number of field observations of reinforcement performance following a range of dynamic loading conditions. It was observed that fully resin encapsulated threaded bars exhibit variable behaviour. In particular, inconsistent resin encapsulation was frequently observed in combination with surface support failure, indicating that the retention function of these elements may allow preferential loading of the surface support system. Observations of cement grouted, twin-strand plain cable bolts reveal a common mode of damage involving differential displacement across the steel-grout interface and slip of the cable within the borehole. This is common where strands are not mutually tensioned with barrel and wedge assemblies. Surface fixtures that exceed the strength capacity of the cable strand are required in order to minimise the occurrence of this response. Improved load transfer from the rock mass and surface support to the cable can thus be achieved, particularly where small block size failure occurs.CITATION:Drover, C and Villaescusa, E, 2016. Field performance of fully encapsulated reinforcement during violent failure events, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 659–668 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By Sergio N. Monteiro

Wastes generated by our society and the question on how to dispose them is, nowadays, a relevant matter of concern. The objective of the present work was to characterize the technical properties of composites made of discarded jute sackcloth with its coarse wove fabric, serving as reinforcement phase, and polyethylene wastes collected from city dumps, as continuous matrix. Different amounts, up to 30 wt.% of jute plain weave, fabric were press molded at 160°Ctogether with sieved polyethylene particles. The resulting composites displayed mechanical properties that could compete with those of low-density wooden board. Both by presenting a solution to, otherwise, disposed wastes and by helping to prevent deforestation, the investigated composite may be regarded as an environmentally correct material.

Jan 1, 2006

By C. H. Bloomster

This study estimated (1) radon and radon daughter emissions from underground uranium mines; (2) the reduction in radon that would be released to the surface by using control techniques such as bulkheads, sealants, backfilling, and positive pressure ventilation; (3) the cost for radon and radon daughter removal from total exhaust air; and (4) total radon and radon daughter discharge for lower occupational exposure limits. For 13 large underground uranium mines, estimated yearly radon emissions from each mine ranged from 900 to 3,400 Ci. The estimated age of air emitted from the mines ranged from 11 to 37 min. Potential radon removal methods for the total mine exhaust were evaluated. The cost of these methods was prohibitive. Diurnal and seasonal changes may affect radon emission over short periods of time, but do not affect the total emissions over the long run. Radon and radon daughter emissions would be little changed by increased ventilation requirements needed to achieve lower occupational exposure limits. The concentrations in the exhaust would be lower, but the total release would be the same

Jan 1, 1984

"The Key Lake mill was commissioned in 1983 to process the two Key Lake ore deposits. With the depletion of these ore bodies in 1999, the plant was converted to mill the exceptionally rich McArthur River deposit located seventy eight kilometers northeast of the Key Lake mine site. This paper describes in detail the Key Lake milling process. The mill consists of a grinding circuit, a leachkounter current decantation circuit, a solvent extraction circuit, a yellowcake precipitatiodcalciner circuit, an ammonium sulphate crystallization circuit, and a waste treatment circuit. The paper also describes process changes to handle McArthur River ore, including the ore receiving stationLOCATIONThe Key Lake mill is located 78 kilometres south of the McArthur River mine. It is located at latitude 57' N in northern Saskatchewan, within the southern boundary of the Athabasca formation. The nearest town is Pine House, located 240 kilometres to the south. Access to the mine is by an all weather road and by a private airstrip.HISTORYAND DESCRIPTION OF OPERATIONThe Key Lake mill was commissioned in October 1983 to process ore from the Gaertner and Deilmann ore bodies. The mill was designed to produce twelve million pounds of uranium oxide (U308) a year from a feed grade of 2.4% U3O8.Following grinding, the uranium is leached in a two stage leach circuit using oxygen and sulphuric acid. An eight-thickener counter current decantation (CCD) circuit is used to separate the uranium bearing solution from the solid waste residue. The uranium is further purified in a solvent extraction circuit and then precipitated using ammonia. It is then calcined at 840' Celsius, and packaged into drums for shipping to refineries. There is a crystallization circuit to recover ammonium sulphate produced in the process and a waste treatment circuit."

Jan 1, 2001

By Patrick Pelletier, Pierre-Alexandre Bossé, Julie Fournier, Gianni Bartolacci, Jayson Tessier, Ahmed Bouajila, Carl Duchesne

"This paper summarizes research into the study of the control of flotation processes based on froth images. The use of numerical image analysis techniques for the extraction of significant patterns (froth structure and colour) from industrial flotation froths is discussed.First, the froth was analysed by the use of the Multivariate Image Analysis (MIA) method to extract the spectral variation contained in a RBG image. The Partial Least Squares (PLS) was applied to develop the empirical model for the prediction of froth grade. The results of this application are illustrated using one industrial case study.Second, the froth was also analysed by Gray Level Co-occurrence Matrix (GLCM) and Wavelet Transform Analysis (WTA) to extract features related more to morphological aspects. Since there is useful information hidden in froth texture, these methods are used as texture descriptor to classify different types of froths.Third, a control strategy based on a froth structure indicator was developed and implemented on an industrial zinc flotation circuit. The feedback controller uses a reagent flow-rate in order to maintain the froth structure at its set point. Process improvements obtained with the implemented control strategy are highlighted.Finally, the feasibility to implement a hybrid control strategy consisting in a froth structure supervision controller based on the froth concentrate grade estimated by MIA and recovery inferred by image analysis is discussed.INTRODUCTIONThe development of control strategies to achieve satisfactory control performance has always been a great challenge for engineers and the need for improved process diagnosis, control and optimization has become more and more evident for the mineral processing industry in the last decades. That is why new process variables need to be measured particularly in highly multivariable processes such as flotation. This industrial process is subject to a wide variety of disturbances mainly generated by frequent and sometimes abrupt changes in physical and/or chemical ore characteristics and also, due to some irregularities in manual process operating procedures. A flotation circuit scheme is always a complex network of more than two dozens slurry streams. Information about those streams (% solid, metal content analysis and flow rates) is important for process diagnosis performance evaluation and control. Also, because of the grade decrease and increasing complexity of the new processed ores, more instrumentation outputs and more powerful and significant pr"

Jan 1, 2005