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By H Peiming, W Sakurai, Y Matsuhisa, H Shimazaki, Y Fukahori

Oxygen and carbon isotope mapping of hydrothermally altered wall rocks was applied to the blind ore prospecting of skarn Pb-Zn deposits in the Kamioka mining district, centralJapan, where the wall rocks consist of heterogeneous rock units. The results (d18OSMOW of -1.1 to +17.3ë and d13CPDB of -5.0 to +4.8ë for limestones, and d18OSMOW of -0.8 to +12.5ë for silicate rocks) show isotope zonations of the wall rocks with depletions in heavy isotopes (18O and 13C) toward the centre of mineralization. The isotope zonations likely formed by interaction of migrating thermal waters with the wall rocks during the mineralisation. The heavy-isotope depleted zone, which indicates higher temperature or higher water-to-rock ratio of the system, occurs in the footwall of a fault, indicating that the fault played the role of main conduit of the ore-forming fluids. A heavy-isotope depleted zone was also found in an area, where significant mineralisation had yet to be identified. Recent drilling in this area has intercepted a zone with a grade of 16.0% Zn, 0.8% Pb, and 35g Ag per metric tonne at a depth of about 360 m.

Jan 1, 1995

By T. Y. Yunsel

Estimation techniques such as polygonal, triangular prism, trapezoid, isopach maps, and inverse distance methods are often used in ore or industrial minerals deposit evaluation. These techniques do not express the variability of the deposit and do not allow a determination of the reliability of the estimates. However, geostatistical methods can express a measure of the error associated with the estimates, by finding weighting coefficients for a given mining block, and can also help with data configuration that minimizes the error. This work addresses an application study on the quality and reserve characteristics of the cement raw materials of the Adana Cement Factory in Adana, Turkey, based on the spatial distribution and variability of the chemical components (Si02, CaO, A1203, Fe203). The study has been carried out using a geostatistical procedure that is useful for site assessment, characterization, and monitoring situations where data are collected spatially. Directional and omnidirectional experimental variograms of the cement raw material variables showed that neither strong geometric nor severe zonal anisotropy exists in the data. The most evident spatial dependence structure expressing the continuity for omnidirectional experimental variograms were characterized by exponential and spherical variogram models. These models have been used in cross¬-validation analysis, which proved that these models, their parameters, and kriging parameters are applicable for the study area. Quality contour maps of the deposits at given levels underground were estimated using a kriging interpolation technique. Anomalies such as bullseyes and drift were not observed in the maps that were generated. Kriged maps showed the spatial distribution of quality continuity and variability of the deposits. Grade-tonnage curves and total tonnage estimates in the particular grade were determined using ordinary kriging in order to improve the mining operation and planning. Consequently, local uncertainty and the probability of extreme values occurring are tools of prime importance for the mine planning, the optimum mix of raw materials coming from different quarry stopes.

Jan 1, 2012

By Steve Skelhorn

Over the recent years, major advances have been made in design of precast concrete segmental tunnel liner. Starting from basic, parallel sided rings, we now have state of the art, universal rings incorporating custom tapers to suit individual requirements. At planning stage, the ring diameter is normally fixed and the ring geometry is one of the first items to be assessed. Obvious factors such as TBM layout and curve radius can constrain geometry; however, there others factors that should be considered in order to optimize production. This paper takes a look at the history of the segmental rings and criteria for ring selection, including: general ring geometry;; individual segment geometry; ring taper, and ring width. This paper also explores optimization of ring with a focus on constructability.

By Simon St. John Tose

We have had a long history in supporting the development of training material to ensure “safe” blasting. This has been provided as both significant technical guidance to the industry and input into the development of the new industry surface rockbreakers or shotfirers qualification in South Africa (RSA). The learning material supplied to the industry is based on both a classroom knowledge component and an assessment on the practical application of the learning by the trainee blaster on the job under the supervision of the appointed blaster. This training includes all blasting applications which can often extend beyond the “normal” mining environment of open pits, underground and quarries into civil applications such as trenches, blasting close to private buildings, public roads, pipelines, power lines, swimming pools and the removal of concrete structures and building demolitions etc.

Jan 1, 2013

Deciding on plant-scale reagent dosage regimes and air rates is a topic of ongoing investigation and high importance. The current work explains some techniques that have proven useful in deciding on plant-scale flotation operating regimes. Specific focus has been placed on the reagents: frother and depressant, as well as some discussion around the control of air rate and froth depth. Air rate has been selected based on its effects on the froth phase. Froth velocity and froth height above the cell lip are the two variables measured and used to select the operating air rate. Pulp level is then adjusted to increase or decrease mass pull. A technique has been developed using the Anglo Platinum Bubble Sizer on an industrial flotation cell to determine the relationship between bubble size and frother concentration. This technique has been extended to measure the equivalent frother concentration or frothabilities of various streams on a rougher bank. A mass balance for frother was performed successfully, and this provided a better understanding of the way frother moved in the rougher bank. With this knowledge, more informed decisions can be made about frother addition required in subsequent flotation stages. For depressant, a new protocol for deciding on dosage rate has been developed. The depressant dosage should be based on the amount of fresh feed material reporting to a bank. Currently 400 g/t of fresh feed has been assumed a reasonable starting point with promising results. Improved froth stability and grades were observed. There is scope for more accurately defining the optimal dosage rate. Importantly, the combined effect of changing the chemistry and the hydrodynamics together has been demonstrated. A significant upward shift in the grade-recovery relationship for a cleaner bank was observed.

Jan 1, 2012

Decision-making regarding plant-scale reagent dosage regimes and air rates is a topic of ongoing investigation and high importance. The current work explains some techniques that have proven useful in deciding on plant-scale flotation operating regimes. Specific focus has been placed on the reagents: frother and depressant, as well as some discussion around the control of air rate and froth depth. Air rate has been selected based on its effects on the froth phase. Froth velocity and froth height above the cell lip are the two variables measured and used to select the operating air rate. Pulp level is then adjusted to increase or decrease mass pull. A technique has been developed using the Anglo Platinum Bubble Sizer on an industrial flotation cell to determine the relationship between bubble size and frother concentration. This technique has been extended to measure the equivalent frother concentration or frothabilities of various streams on a rougher bank. A mass balance for frother was performed successfully, and this provided a better understanding of the way frother moved in the rougher bank. With this knowledge, more informed decisions can be made about frother addition required in subsequent flotation stages. For depressant, a new protocol for deciding on dosage rate has been developed. The depressant dosage should be based on the amount of fresh feed material reporting to a bank. Currently 400 g per ton of fresh feed has been assumed a reasonable starting point, with promising results. Improved froth stability and grades were observed. There is scope for more accurately defining the optimal dosage rate. Importantly, the combined effect of changing the chemistry and the hydrodynamics together has been demonstrated. A significant upward shift in the grade-recovery relationship for a cleaner bank was observed.

Jan 1, 2013

By Alastair Grogan, Ron Elliott, Dale MacLean

Blasting for armour stone presents many unique challenges. Often, blasters get themselves into trouble when they assume that they can simply modify a production blast design to produce the required fragmentation size. They bid on the project using typical production blasting costs, and then find that they cannot produce the required fragmentation size and quantity with an acceptable waste factor. This paper outlines industry best practice guidelines for the production of riprap or armour stone. The paper examines the importance of initial geological mapping to determine the average in-situ block size, and the advantages to be gained from working with the geology to maximize production of the required block sizes. The paper also outlines the importance of proper explosives selection as well as blast designs that are unique to the production of riprap. The paper reviews challenges and experiences realized from multiple projects in differing rock types.

By M S. Stern, R Aguila

To control direct blasting costs many open pit mines dewater and line wet blastholes before loading them with ANFO or Heavy ANFO blends of explosives. The plastic lay-flat tubing used for these liners can be punctured during loading and allow water to partly dissolve and desensitise the explosive column which reduces blasting performance.

Jan 1, 1997

By Osborn G

The bulk flotation behaviour of an industrial rougher bank has been determined with a view to characterising the size iepend ent behaviour of the identifiable nineral groups present. A relatively simple flotation model, based on first order kinetics and the assumption of perfect mixers in series ias been used to provide a fit to the operation of the cells. The adequacy of the model is discussed in relation to the characteristics of the ore and the size iependancy of the parameters. It is shown that improved fits are possible if the model accounts explicitly for this size dependancy and demonstrated how the model may be of use in prediction of the grade recovery relationships for different operating conditions as an aid to plant optimisation.

Jan 1, 1986

By Michael Amick

Over the last few years as the coal industry has seen an increase in the price of coal, a renewed interest in the additional mining of pre-law highwall sites has occurred. Much premium coal and property remains behind these pre-law highwalls but access to mining is limited because prior mining used auger machines to remove coal from under the highwall. Older augers seldom reached more than 200 feet and often no more than 100 feet but this zone of auger holes destabilizes the highwall to where additional mining is often unsafe. If the reserve is large enough, the highwall can be stabilized with common flyash and cement grouts to form a face-up for an underground mine but this expensive method is usually not practical for continuous use with a highwall mining machine. It is estimated there are hundreds of miles of highwall riddled with auger holes where the coal reserve available is ill-suited for deep mining for a variety of reasons. However, these same properties are ideal for additional mining with state-of-the-art highwall mining machines that have a reach up to 1200 feet, except to the relatively thin auger mined de-stabilized zone. The renewed interest in highwall mining these properties has driven research into finding an economical way to stabilize the highwall so the highwall mining machine can recover additional coal. This research discovered and fine-tuned a process that is economical and is successfully supporting the highwall at a highwall mining operation. This paper discusses the research involved in determining the strengths need, the methodology used to place any grouts, the effect on mining plans and the increased recoveries. ARMPS-HWM is used extensively in this research. The failure of the highwall, when not grouting, and the success, when grouting using the new materials and equipment utilized, confirmed the ARMPS-HWM method.

Jan 1, 2007

By Brian F. Osborne

A continuous on-line particle size analysis system for solid/liquid suspensions is described. The basic sensor utilizes a centrifugal principle to separate particles according to size, the resultant separation being measured by means of beta-ray attenuation. Results obtained when analyzing a variety of materials at sizes from 65 mesh (210 microns) to 20 microns are discussed in de- tail. Accuracies better than 2% are demonstrated. The effects of particle specific gravity, and mixtures of materials of diverse specific gravities, are discussed from a practical and theoretical viewpoint. It is demonstrated that particle specific gravity has a minimal effect on the size reading obtained. This renders the instrument suitable for handling materials where the ratio of light to heavy component may change. The design of the first commercial installation of this instrument is described in detail. This installation will be capable of analyzing three streams in sequence, measurement at three particle sizes being effected on each stream.

Jan 1, 1973

By William Hustrulid

Pre-split blasting is a primary technique for creating slopes with a minimum amount of unwanted damage to the remaining rock mass. Rock slopes created in such a way have both safety-related and economic advantages. The applications extend from road cuts to rock quarries to large open pit mines. For example, as deep open pit mines approach the end of their operating lives, slope steepening is one option to be considered. To be able to safely achieve and maintain steepened final slopes, good blast design techniques must be available and applied together with close operational control. Pre-split blasting is an important element in this slope creation process.

Jan 1, 2007

By G. Kang

The ferroalloys industry has generated historically substantial solid waste. The accumulated waste causes serious problems to the environment. However, it is possible to transform the solid waste into an environment-friendly resource to serve the human being. Consequently, the construction of plants that are ?environment-friendly? and that accommodate ?recycling? has become a target of most ferroalloy producers in the world to ensure sustainable development. This paper introduces the practice of Shanxi Jiaocheng Yiwang Ferroalloys Works, the biggest manganese metal producer in China, in the development of an ?environment-friendly and recycling? process. The process includes power generation using coal gangue, waste from local coal mines; hollow bricks manufacture using slag and fly ash from the power station; cement production using slag from ferroalloy smelting; recovery of ferrous and non-ferrous elements in the dust from the furnace gas cleaning system; application of silica dust in construction and so on. The final objective of the plant is to realize zero discharge of solid waste. The profit of the ?environment-friendly and recycling? process compensates in part for the operational expense of the environment facilities.

Jan 1, 2004

By Rick Wilkins

The stability of steep embankments is a major safety issue in open pit mining, highway passes, and earth filled dams. A failure in any one of these situations could mean a loss of very expensive equipment, a long term inconvenience, and more importantly, a loss of life. These possible catastrophes could be avoided by installing a reliable real time monitoring system. Robotic total stations (RTSs) give one possible cost effective solution to creating a near real time monitoring system. Repeated surveys at predetermined time intervals can automatically generate warnings if slope movements exceed a preset tolerance level. The variation in atmospheric refraction, combined with possible instabilities in reference targets, can make a monitoring system based on RTSs produce false alarms. A methodology has been developed at the Canadian Centre for Geodetic Engineering (CCGE) for reducing these systematic error effects. The methodology has been realized in the creation of a software package that has been successfully implemented at large earthen dams in California and at an open pit mine operation in British Columbia.

May 1, 2002

By Yuan She, Qihang Liu, Keng Wu, Hailiang Ren

By observing different coal char’s microstructures and microscopic morphologies during the coking process, the characteristics of COREX coal char’s microstructure and properties were analyzed. MCRI and MCSR were used to respectively describe the reactivity and the strength after reaction of coal char, with those of BF’s coke for reference, and then the physical meaning of MCRI and MCSR were given. MCRI and MCSR were determined by the composition of coal char. For the two kinds of COREX coal, the formula to forecast the hot performance of coal char was set up by making a multiple linear regression between the hot performance and microstructure of the coal char at 1100℃, and the predictive values of coal char’s hot performance at 600℃, 800℃ and 1000℃ coincided well with the measured values.

Jan 1, 2015

By Ting Lu, Gerard Laman

"This document compares the systems of coal classification described under ASTM standards used in Canada to GB standards used in China. A preliminary connection of metallurgical coal classes was set up between the two classifications. In GB classification system, there are nine metallurgical coal groups, namely PS, SM, JM, FM, ½ ZN, RN, 1/3 JM, and QM used in coal blending for coke production. PS coal is almost equivalent to the Low Volatile Bituminous coal; SM, JM, and FM coal groups fall into Low to Medium Volatile Bituminous range; ½ ZN, RN, 1/3 JM, and QM are equivalent to bituminous coal with medium to high volatile matters; QF contains higher volatile bituminous coal compared with High Volatile Bituminous coal. The caking properties commonly used in respective country are also compared in this document. These properties include free swelling index (FSI) and maximum fluidity used in Canada, as well as caking index (GR.I.), and the maximum plastic layer thickness (Y) mainly employed in China. It has been observed that the log of the maximum fluidity has a stronger correlation with the caking index than the Y values. Metallurgical coal processing strategy and typical coking coal product qualities are briefly discussed in the last section of this paper. Currently there is a trend to use heavy medium cyclone in both countries. In Canada the conventional two-product cyclone technology is the preferred practice; whereas in China the three-product heavy medium cyclone arrangement is widely used.INTRODUCTION Coal can be simply classified by applications into two categories: i) thermal coal used to provide heat energy in combustion, and ii) metallurgical coal which is converted to coke, in a carbonization process, and used mainly in the iron and steel industry. Metallurgical coal contains even higher heating values than thermal coal. In addition, it presents unique plastic properties during carbonization which in turn produces a porous solid, high in carbon referred to as coke. Coke is one of the most important raw materials in the iron and steel industry."

Jan 1, 2012

By J Taylor, L Richards, M McKenzie

When a collapse in its services shaft caused rapid gas build up and its premature closure in. 1951, the Blackwater Mine at Wiauta was in full production with significant ore reserves yet to be mined. A total of nearly 23 tonnes of gold was produced from the mine during its 44 year life. It was New ZealandÆs deepest underground mine, producing gold from an extensive sub-vertical mineralised quartz reef that averaged 0.6 m in width. Mining was by stoping between adits and short shafts, latterly with the main mine access through the 840 m deep Prohibition shaft. Macraes Mining Company Ltd are presently investigating the possibility of reopening the mine. This paper outlines a preliminary assessment of the main geotechnical factors for achieving the reopening, using recent exploration and old mine information. The greywacke host rock mass in the vicinity of the quartz reef has been evaluated using both these sources, and the paper discusses how the geological structure, intact and rock mass strengths, the rock mass defects, in situ stresses, and groundwater inflows may effect the reopening and support of the prohibition shaft, the excavation methods and support for a new supplementary shaft, and the likely excavation and support requirements for working adits and stopes in the rejuvenated mine.

Jan 1, 1996

By F. Peer

This Technical Note was presented as a poster at the Western Cape Mineral Processing Symposium held in August 2001 The cleaning of fine coal (-1000 µm) in today?s coal preparation plants is an economically important factor. Coals with high ash contents are, in general, commercially undesirable. Current well-known techniques for treating fine coal include froth flotation and spirals. The primary critical factor with regards to spirals is the efficiency of the process whereas that of flotation, is the cost of there agents used. Research into enhanced gravity separation techniques has resulted in several commercially available enhanced gravity separators. This project was based on a preliminary investigation into the feasibility of one such separator, to effectively treat fine (-500 µm) coal. Experimental variables included particle size and speed of rotation of the said instrument. The performance of the separator was compared to the results obtained from liquid density separations done for the two coal fractions evaluated. From the results obtained in this preliminary study it appears that the piece of equipment investigated does not measure up to expectations. Recommendations for further investigation include the evaluation of the instrument on other South African coals to obtain conclusive results.

Jan 1, 2002

By L. Frost

"Since the late 1990s, increased prevalence of severe lung disease among US coal miners has been observed, particularly in central Appalachia where thin-seam mining is prevalent. While respirable silica exposures have been implicated in many cases, the available dust monitoring data from mines shows no explanatory trends. One possible factor could be differences in the relative toxicity of silica particles based on their surface condition. Previous research has indicated that particles with occluded surfaces (e.g., by a thin layer of clay) may be less toxic than those with non-occluded surfaces. However, this dust characteristic has not been investigated before now in central Appalachian mines. In the present study, 18 respirable dust samples from seven central Appalachian mines and two northern Appalachian mines were analyzed to assess the relative occurrence of surface-occluded silica. Results showed that the dust from central Appalachian mines actually had higher fractions of occluded silica, which may be due to extraction of large amounts of rock strata along with the coal. However, the central Appalachian mines also more silica particles overall (i.e., occluded + non-occluded) in terms of total number percentage of respirable particles.INTRODUCTIONResurgence of occupational lung disease among US coal miners, especially in the central Appalachian region, has been observed since the late 1990’s (Gibson, 2016; Zosky et al., 2016; Suarthana et al., 2011; Gamble et al., 2011; Antao et al., 2005; Attfield & Sexias, 1995). In addition to increased prevalence of simple Coal Workers’ Pneumoconiosis (CWP, or “black lung”), the prevalence of severe and rapidly progressive disease has risen dramatically (Almberg et al., 2018; Blackley et al., 2018a, 2018b, 2016, 2014; Graber et al., 2017; Cohen et al., 2016). While exposures to respirable silica have long been known to cause or play a role in diseases such as silicosis or progressive massive fibrosis (PMF), which is conventionally considered as the most advanced form of CWP, it is unclear whether silica is the only culprit in the recent outbreak of severe disease. Indeed, as disease rates have risen, both total respirable dust and silica concentrations generally appear to have declined since the late 1980s, based on regulatory monitoring data in the most affected mining districts (i.e., MSHA coal Districts 4, 5 and 12, which cover central WV, eastern KY and southwestern VA, and southern WV, respectively) (Figure 1). Of course, the latency of disease can vary and may be or more 10 years, but many of the most recent cases are likely to have resulted from exposures that occurred since the late 1980s."

Jan 1, 2019

In 1961, West Australian Petroleum's Eneabba No. 1 bore encountered 22 seams of coal totalling 40 ft in thickness between the depths of 6373 ft and 6441 ft. On analysis, this coal had a similar calorific value (8000-HOOO B.T.U./lb, assuming 20 per cent water) to the coal from the Collie Coalfield, Western Australia's only known area of commercially exploitable coal. Being buried to depths in excess of 6000 ft, the coal at Eneabba had developed weakly-coking properties, and thus, although much younger than the Permian coals of Collie, gave promise of being a major potential source of power for Western Australia.West Australian Petroleum undertook a programme of stratigraphic drilling and shallow test drilling to determine whether this coalhorizon persisted into the outcrop of the Lower Jurassic sediments in the Hill River district, 140 miles NNW. of Perth, and, if it was present, if the quality and quantity of the coal would warrant development of the deposits by open cutting. The coal horizon was identified in the near surface, but the poor quality of the coal and the complexity of the structure made development (in the area examined) uneconomic at the time.A strong seismic reflection in the Eneabba area occurs at the same depth as the Jurassic coals. This event originates within the upper beds of the Lower Jurassic and it is probable that the velocity contrast between the higher velocity siltstones and the very low velocity coals enhances this very strong, distinctive seismic reflection.This event can be followed on continuous seismic data over a large area of the northern Perth Basin, from 13 miles SE. of Dongara to 20 miles SW. of Coorow. It can be followed from a depth of 4000 ftnear Dongara to over 17,000 ft to the SE., so development of thisvast potential source of power will depend on the economics ofprocesses being developed for the production of power from theburning of coal seams in situ.INTRODUCTIONThe discovery of 22 seams of economically useable coaltotalling 40 ft in thickness in the Lower J urassic sedimentsof the Eneabba No. 1 bore (Fig. 1) led to the search forthese seams at economically workable depths. The Ministerfor Mines in Western Australia granted to West Australian1. Supervising Geologist, West Australian Petroleum Pty. Ltd.Manuscript received at The Institute, 25th May, 1964. and presented to the 1964Annual Conference.

Jan 1, 1964