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By Masaki Kitazume

"Abstract The wet type and dry type of deep mixing methods have been developed and widely applied for on-land and marine constructions in Japan. The quality assurance (QA) of the methods has been usually carried out by unconfined compression test on field stabilized soil sampled by core boring in Japan. In some other countries, stabilized soil excavated by the wet grab sampling instead of core sampling is often subjected to unconfined compression test for quality assurance. There are several merits and demerits in each method, but few studies have been carried out to compare the stabilized soil strength of these two types of specimens to discuss their applicability to practical construction. The author has conducted a series of field and laboratory tests to compare the stabilized soil strength and discuss the applicability of wet grab sampling to QA for wet and dry types of deep mixing method.In this study, the wet grab sampling was carried out at two road embankment construction sites where the wet type and dry type of deep mixing were applied. The cement stabilized soil was excavated at the three depths by a wet grab sampler soon after the DM column construction. The test result is compared with the other test data in the previous study to discuss the applicability of the web grab sampling method for QA of cement stabilized soil.IntroductionThe Deep Mixing Method (DMM), an in-situ soil stabilization technique using cement and/or lime as a binder, is often employed to improve soft soils (Kitazume and Terashi, 2013). A variety of factors and their interactions affect the eventual strength of a deep-mixed column, while some of which are controllable (e.g. binder type and dose) by engineers while the others are not (e.g. soil types, ground temperature, etc.; Babasaki et al., 1997). In addition to laboratory mix tests, which in essence are a parametric study to estimate the influence of these factors on a particular soil’s strength, the quality assurance (QA) practice in Japan usually involves unconfined compression test on sampling cores from the stabilized columns after a given curing period. It has been recognized, however, that the ‘field strength’, or the strength of the retrieved core, quf is on average lower than the ‘laboratory strength’, qul, evaluated by laboratory mix test. Also allowing for the inevitable variability, existing guidelines (for example, PWRC, 2004 and CDIT, 2008) recommend the design quf /qul values of, for example, 0.5-1.0 for the CDM (Cement Deep Mixing; a wet-type technique, in which binder is added as slurry) and 0.2-0.33 for the DJM (Dry Jet Mixing; a dry-type technique, in which binder is added as powder)."

Jan 1, 2014

By C. W. Whitten

Iron ore deposits in south-central Missouri have emerged as a possible resource for the rare-earth elements. The Pea Ridge Iron Mine is one such deposit. Rare-earth minerals at the Pea Ridge Iron Mine are contained in breccia pipes consisting primarily of silicon oxides and feldspars. These pipes extend up through the magnetite ore body and appear to be alterations and replacement of earlier hematite. The mineralogy of these pipes is very complex and varied, which could complicate the concentration and extraction of the rare-earth minerals. This U.S. Bureau of Mines !eport represents a study by characterization of the mineral phases to assess the amenability and development of concentration and extraction techniques. Previous characterization of rare-earth minerals has been mainly by transmitted light microscopy. This method along with reflected light microscopy, scanning electron microscopy, and X-ray diffraction was used to identify and characterize the rare-earth and associated minerals. The minerals identified were the major ore minerals, magnetite and hematite; the rare-earth phosphates, monazite and xenotime; the rare-earth silicate, allanite; the minor associated minerals, cassiterite, pyrite, and apatite; and the gangue minerals, feldspar, quartz, and actinolite.

Jan 1, 1990

By R L. Brathwaite

Previous paleodepth studies of low-sulphidation epithermal Au-Ag deposits in the Coromandel region indicated that economic gold mineralisation was generally limited to a depth zone of 100 to 400 m below the paleosurface. Notable exceptions are Waihi and Karangahake, where ore shoots extended to depths of about 750 and 900 m respectively. These studies have been extended to include Au-Ag, Hg and Sb epithermal deposits in Northland and the Taupo Volcanic Zone. The main paleodepth indicators used are sinters and hydrothermal eruption breccias, hydrostatic pressures estimated from homogenisation temperature measurements on fluid inclusions, and hydrothermal alteration mineralogy. Also the occurrence of lacustrine and fluvial sediments is an indicator of the paleosurface at their time of deposition. Selected paleodepth indicators have been compiled and mapped in a GIS environment. The distribution of the paleodepth indicators are used to define regional variations in erosion levels, and may be useful in predicting areas most likely to preserve the optimum depth window for gold deposition. In the Coromandel region, regional stream sediment geochemical data has also been used to broadly define erosion levels in terms of Zn, Pb and Cu representing deeper base metal zone mineralization and Hg and Sb representing shallower cinnabar and stibnite mineralisation. The interpretations of paleodepth and potential reconstruction of paleosurfaces are limited by the paucity of data, poor age control on the paleodepth indicators and the epithermal deposits, and marked relief and complex stratigraphy in the volcanic terranes.

Jan 1, 2003

By A Giblett, T J. Napier-Munn

This paper presents the results of a test program evaluating the impact of sample mass on the precision of Stage 1 gravity recoverable gold (GRG) test results. Four ore types ranging from low to high GRG contents were the focus of testing. A method to predict the influence of sample mass on the confidence limits of the Stage 1 GRG test result is demonstrated. The results suggest that although small samples tend to overestimate Stage 1 GRG in samples with low gravity gold values due to higher mass pull to concentrate, such samples can give acceptable estimates of the Stage 1 GRG content with focussed sample treatment protocols.CITATION:Giblett, A and Napier-Munn, T J, 2015. Measuring the influence of sample size on the precision and accuracy of gravity gold estimation, in Proceedings MetPlant 2015, pp 367–372 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By Mohammadreza Khanmohammadi, Kazem Fakharian

"AbstractIn driven piles, the gradual dissipation of excess pore water pressure and consequently the soil setup significantly contribute to increasing the pile capacity with time. The question is risen that how the scale differences affect the stress state variations around the pile shaft and at the pile tip? Would the CPT predictions better correlate with End-Of-Drive (EOD) or Beginning of Restrike (BOR) conditions? On the other hand, are the proposed a and ß parameters for clayey soils mostly predicting the EOD or BOR situation? The main objective of this paper is to back calculate the a and ß parameters from CPT profiles, pile Dynamic Load Tests (DLT) at the EOD and BOR as well as Static Load Tests (SLT) and evaluate how they compare with those suggested in literature. Four precast 400 mm square concrete piles driven in North Azadegan Oilfield in Khuzestan Province were selected for the comparisons. CPT test results were available from the extensive geotechnical investigation at the study site. DLT tests using PDA were carried out at EOD, 1 day and 14-day BOR on all the 4 piles. All the piles were SLT tested as well. The UniCone software was used to estimate the tip and shaft resistances using 4 methods including the Dutch, Eslami & Fellenius, LCPC and Schmertmann. The results indicate that the a-method based on the proposed values in literature has predicted a shaft capacity of 90% of the 14-day BOR. This is while the ß-method has predicted a shaft capacity equivalent to 1-day BOR results only. Therefore, both methods have under-predicted the shaft capacities compared to real capacities measured after the significant soil setup in the study area. Two of the CPT methods have underestimated, one has overestimated and one has matched the estimated 60-day capacity."

Jan 1, 2014

By L. Bergkvist

"History can provide many answers with regard to what today’s mining industry looks like and how we got to where we are today. It has always been self-evident that safety has to be given the highest priority and, throughout history, many mine workers have been injured, become ill and have even sacrificed their lives due to the way in which attempts have been made to extract the ore, often due to ignorance of the dangers being faced. In more recent stages of history we have seen certain dangers being compensated by means of higher wages and bonus systems in order to have the work carried out: one example of this is when the rock heating method was employed and the men who first went underground to put out the fires that were burning, were paid extra. The working conditions, to which these people were exposed, with smoke-filled closed spaces, shortened their life expectancy considerably and today we can ask ourselves whether it is really possible to value these efforts just by higher wages. In all mines worldwide the working environment has been improved and many mining companies have a zero vision where work-related injuries and accidents are concerned. Despite this, incidents of varying severity still occur and a continuous improvement process and ongoing training is necessary in order to constantly minimise risks and improve the working environment. Atlas Copco takes this into account in all its development and we not only review our own production units but also the needs of our customers, with regard to the machinery that is produced in order to cater for customers’ safety and production objectives. Underground mining probably started at the beginning of the 11th century when people with modest tools tried to extract ores that were present in the bedrock. Methodology has developed enormously over the years with a strong focus on increased efficiency and higher production. In different parts of the world the development is driven forwards at different rates depending on which controlling factors are regarded as necessary. Political decisions, profit goals and productivity have partly controlled the development, but the greatest factor where improvement is concerned still remains with increased understanding of the totality. During more than 1000 years since underground mining has been conducted, all individuals at all levels have constantly improved their expertise and the human element has been of great importance with regard to the development that has been made, even though technology often occupies a leading role when we describe the improvements made."

Jan 1, 2011

By Sri C. Sawmliana, P. Pall Roy

Damage to underground roof and pillars in blasting gallery (BG) panels has been an increasingly important area of study in recent years due to the invention of new explosives and cord systems which has led to the modification and alteration of the design aspects developed by Charbonnage de France (CdF). According to extensive mine experiments conducted by Indian and foreign experts, it has been established that the induced peak particle velocity (PPV) is predominantly related to the emanated seismic energy of a source and the distance from the source. With that concept in mind, nearly 160 experimental blasts were carried out in four BG panels in India under varying geomining conditions. Based on the results obtained thus far, the authors have established predictor equations correlating explosive energy (in Joules) and distance from the shot to that of induced peak particle velocity received at the sensor point. Good correlation was obtained between the actual and the predicted values. It is realized that this equation may be used as an efficient tool to determine the size limit of blasts in BG panels so that the induced particle velocity does not create damage in underground workings as per the established Blast Damage Index (BDI) and other available safety norms.

Jan 1, 2004

By M. Gangal

CANMET-MMSL, in cooperation with Dry Systems Technologies and Quinsam Mine, conducted a study to determine the effects of B50 biodiesel on the emissions of a flameproof diesel power package in comparison with mining diesel fuel for application in underground coal mines. The emissions testing for coal mine application requires that the intake air mixture to the engine should be at 1.25 percent methane by volume in air. The tested power package system included a naturally aspirated, mechanically-controlled diesel engine with a diesel oxidation catalyst (DOC), a heat exchanger, flame arresters, and a low temperature disposable diesel particulate filter. The engine dynamometer tests were conducted at the CANMET-MMSL Diesel Emissions Research Laboratory in Ottawa using the ISO 8178-C1 test protocol. The separate and combined effects of a B50 biodiesel blended fuel, and with and without 1.25% methane enriched intake air were measured on a diesel power package. Fuelling the baseline engine (without methane), with B50 biodiesel blend reduced carbon monoxide (CO) by 44%, and increased nitrogen dioxide (NO2) by 19%, and particulate matter by 31% relative to the mining diesel fuel. Similarly, injection of 1.25% methane to the intake air for baseline engine with mining diesel fuel increased engine power by 15%, CO by 124%, and NO by 15%, and decreased NO2 by 13%. The effect of B50 biodiesel relative to the mining diesel for coal mines application (with methane for both fuels) was to reduce CO by 27%, and NO by 6%, and increase NO2 by 23%, with no change in engine power. The overall results indicate that the minimum ventilation rate for the equipment application in coal mines with B50 biodiesel was 4.11 m3/s (8,700 cfm), slightly higher than the ventilation rate of 4.01 m3/s (8,500 cfm) with the mining diesel fuel. This slight increase in ventilation rate for B50 biodiesel fuel was due to an increase in NO2 at one of the operating test points, and the ventilation rate for this equipment was governed by NO2 in the exhaust gas.

Jan 1, 2009

The Torington Lodes.This paper describes investigations into mineralogical, petrological and structural associations of cassiterite in occurrences of economic value. The work was carried out in three mines, during a number of years, in the hope that the, data collected might be helpfulin the search for occurrences of cassiterite in stanniferous zones and reduce unproductive exploratory work. Tin-bearing lodes at Torington, in the New England district, New South Wales, have been worked since 1880, and the locality is the most important centre of lode tin occurrence in the, State. The township of Torington is 18 miles westerly from Deepwater, a station on the Great Northern Railway, 446 miles from Sydney.The tinfield forms part of the Mole Tableland, which has an altitude between 3,000 ft. and 4,000 ft. above sea level. The country rock, in which the stanniferous lodes occur, is granite of Permian age, which has been intruded into Carboniferous claystone. An inlierof claystone is exposed to the west of the stanniferous area, 'and in it, close to' its contact with the enclosing granite, are occurrences of wolfram and bismuth. These minerals, together with chalcopyrite, pyrite, arsenopyrite, zinc blende, galena and molybdenite, in very small quantity, are associated with cassiterite in lodes traversing the granite, particularly near the claystone, but decrease in amount with distance from the contact. Their occurrence is sporadic and usually causes no trouble in dressing the cassiterite concentrate, the final product containing less than 1% of total penalisable impurity. In Curnow's mine, pyrite, galena and molybdenite have been observed at 700 ft. from surface.The granite is of the biotite type and its structure may be divided into four groups, or classifications, arising from segregation processes during cooling and consolidation. The four classes, in order of extent of distribution, are:1. Granite of normal type, in which the constituent quartz felspar and mica, have a particle size approximately 14, in.2. Porphyritic granite, in which the felspar particles are from % in. to lin. in size, that of the quartz and mica approximately % in.3. A fine-grained granite, in which the particles of all constituent minerals are % in. or less in size;4. A rock of highly siliceous ground mass containing very small particles of felspar and almost negligible biotite.Type 1 is the general type of granite in all mines of the field; types 2 and 3 may occur as large masses, or all three classes may merge rapidly one into the other, and all be disclosed in 20 ft. of driving. Usually, however, the segregations are massive, but are not associated with any special horizon. For instance, a mass of porphyiiticgranite extends from surface to a depth of 440 ft., for a distance of 350 ft. south from the New England main shaft. The upper levels of Curnow's mine, 14" mile south-east, are in normal granite, but a restricted mass 'of porphyritic granite occurred between Nos. 5 and 6 levels, or 400-500 ft. below the collar of the shaft...

Jan 1, 1950

As the question of zino recovery from lead blast furnace slags has lately become such an important subject with lead metallurgists, the following description of some of the work carried out in this oonnection by the Sulphide Corporation, at CockleCreek, should prove of interest to those concerned. Early in the life of the works it was realised by the metallurgical staff that a very wide field for investigation lay before them. At the head of these was the late Mr. F. H. Evans, and it was due to his work and suggestions that the question has grown from a mere hypothesis to a commercial undertaking, in so far as these works are concerned. A great deal of the early work was carried out in the form of small laboratory expe!iments, those giving the best results being ear-marked for subsequent trial on a larger scale. One of the main obstacles in the way of research was the lack of any data or information of similar work done in other...

Jan 1, 1920

By Fookes R. A, Gardner K. J, Gravitis V. L, Watt J. S, Steffner E. J

Two radioisotope techniques suitable for the rapid laboratory determination of the ash content of coal have been tested ou unwashed coal samples from four Australian coal seams. In one techniqne, measurements of backscattered 238Pu L X-rays and iron K X-rays from finely ground coal samples have been combined to determine ash content in uuwashed coals to ±0.5 weight per ce111 ash (ls) for three seams and 0.9 weight per cent ash for the fourth.The second technique, which involves measurements of the transmission by the coal of narrow beams of 241Am 60 keV and 123Ba 356 keV ? rays, requires less sample preparat ion. The ash was determined to within the range of 0.8 to 2.6 weight per cent for the four seams (unwashed coal). For washed coals, errors are expected to be < ±0.5 weight per cent ash.

Jan 1, 1982

By Dale S. Hursh, William A. Brooks

Introduction US dependence on external energy sources is dangerous because of unstable political situations existing in key energy exporting countries. So, recent national energy policies call for increased reliance on domestic energy sources. Coal ranks as the most feasible domestic energy source due to its abundant reserves and continental distribution. But to efficiently extract these coal reserves, huge sums of capital funds are needed. Due to the depressed economy, lenders of capital funds are forced to be more stringent with loan applications. This results in fewer loans granted. In many cases, it is uncertain if funding can be obtained. Furthermore, the greatest level of domestic mine financing is expected to be in the coal sector. Demand for capital in the domestic coal industry is anticipated to increase 80% by 1990. The Chase Manhattan Bank in New York warns that these future needs cannot be met by the present capital markets. This article analyzes the current and expected situations of the capital markets available to the domestic coal industry, including: • current and expected future types of financing used in the domestic coal industry; • problems the domestic coal industry may encounter as it seeks capital; and • the future availability of capital funds as concluded from analysis of the first two items. Background Information Regardless of industry, all projects or ventures can be divided into four basic stages: generation; evaluation; selection; and execution. Within the mining industry, one can break down these stages to draw a clear picture of mine development, as shown in Fig. 1. Each successive stage has a corresponding risk level. This risk level defines the type of financing available to the mine operator. Mining Venture Risks A coal mining venture can be characterized by its unique blend of technical and financial risk. As the mine moves through different development stages, varying proportions of each of these risks are encountered. It is these risks that the lender evaluates to determine project suitability. For a coal mining venture, the major complexities generally occur with the technical risk. These include: • quantifying the coal reserves: • assessing the feasibility of the mining method; and • evaluating the design of the wash plant. The reserve risk is gauged by the amount of measured, mineable, and saleable reserves. The greater the latter amounts, the lower the risk. Secure title to the reserves plus title for any surface areas required are also of concern to the banker. Feasibility of the mining method and evaluation of the wash plant design should verify that the project can be completed according to the engineered spec-

Jan 9, 1982

Phase equilibria have been determined experimentally for pseudo-ternary sections of the form ?MnO?-(CaO+MgO)-(SiO2+Al2O3) with a fixed Al2O3/SiO2 weight ratio of 0.17 and MgO/CaO weight ratios of 0.25 and 0.17 respectively for temperatures in the range 1473-1673 K. The primary phase fields present for the MgO/CaO weight ratio of 0.17 include manganosite (Mn,Mg,Ca)O; dicalcium silicate a-2(Ca,Mg,Mn)O?SiO2; merwinite 3CaO·(Mg,Mn)O·2SiO2; wollastonite [(Ca,Mg,Mn)O?SiO2]; diopside [(CaO,MgO,MnO,Al2O3)?SiO2]; tridymite (SiO2); tephroite [2(Mn,Mg)O?SiO2]; rhodonite [(Mn,Mg)O?SiO2] and melilite [2CaO?(MgO,MnO,Al2O3)?2(SiO2,Al2O3)]. For the section with MgO/CaO weight ratio of 0.25 the anorthite phase (CaO·Al2O3·2SiO2) is also present. The liquidus temperatures of ferro- and silico-manganese smelting slags have been determined. The liquidus temperatures at low MnO concentrations are shown to be principally dependent on the modified basicity weight ratio (CaO+MgO)/(SiO2+Al2O3).

Jan 1, 2004

By G. van Hout, D. Rahal

Caving is a mass mining method that is normally applied to large, low grade orebodies because of its low production cost and high capacity. However, equipment breakdown and poor draw management can cause mining costs to exceed that of all other mining methods. One way to minimize the effect of disruptions in the mining cycle is to use Mixed Integer Linear Programming (MILP) for long-term scheduling. This paper describes a MILP goal program which has the dual objectives of minimizing deviation from the ideal draw profile while achieving a production target. Schedule optimization is performed using a life of mine approach in which all production periods are optimized simultaneously. The underlying assumption being that material mixing in the short-term (between monthly optimization cycles) has a minimal effect on the long-term state of the panel. Schedule optimization is carried out using six general constraint types to model and control production. The constraint types define: deviation from ideal practice, panel state, material flow conservation, production quality, material flow capacity and production control. These constraints define production targets and drive production toward the ideal profile while maintaining correct mining practice. Application of the model using production scheduling data for a De Beers kimberlite mine. It is shown how different production control constraints regulate production from individual drawpoints as well as recovery of the ideal panel profile by implementing an optimised draw schedule.

Jan 1, 2003

By Healy T. W, Dixon D. R

The present study 'of pure ZnS and NiS and ZnS (marmatite) by detailed electrokinetic methods has shown that by careful control of experimental parameters much new' information on sulphide-water interfaces can be obtained. Time-dependent processes of alteration of sulphide surfaces are foHowed by electrokinetic methods and indicate that the isoelectric point of the surface depends on elemental sulphur coverage, oxidation product coverage, and the conditions which promote or minimize such reaotions in the presence and absence of activator.

Jan 1, 1977

By John G. Henning

The Porcupine Joint Venture operates the Dome Mine in South Porcupine, Ontario. Dome underground began production in 1910. It is the longest continuous operating gold mine in Canada, producing in excess of 15 M ounces. More than 900 underground stopes have been mined and hundreds of miles of drifts, sublevels and raises developed. Underground mining methods included shrinkage, cut and fill and longhole. Not all stopes were backfilled upon completion, particularly the longhole stopes. The Dome open pit was designed above the underground mine workings such that, as the pit is excavated, it intersects underground drifts and stopes. Potential operational problems associated with the interactions between the stopes and the pit walls may occur, necessitating pit wall redesign, ground support installation and operational rescheduling. Each intersection of the pit with the underground mine workings is closely evaluated to maintain a safe working environment and wall stability. This paper discussed how risks to pit wall stability are assessed, mitigated and monitored.

May 1, 2004

By L. F. Miao

Studies were carried out to investigate the ultimate soil pressure acting on pile(s) undergoing lateral soil movement in soft clay. A special apparatus has been designed to apply a uniform rectangular profile of lateral soil movement on the rigid pile(s) with pinned head and tip conditions to obtain the ultimate soil pressure. The piles were 16 mm (5/8 in) in diameter. For the pile group tests, the behavior of different number of piles (2, 3, 4, 6 and 9), pile arrangements and center-to-center spacings (3 and 6 diameters) were investigated. In this paper, the group factors of 11 combinations of number of piles, pile arrangements and pile spacings are presented. The group factors are given for individual piles in a pile group as well as for the entire group. Generally, the group factors of individual piles in a group varied significantly according to pile spacing in both directions, and pile arrangement; the group factor of the whole group reduced with an increasing number of piles, and increased with increasing pile spacing. For a pile group with the same number of piles but different pile arrangement, no significant difference was found in the group factors for the entire group.

Jan 1, 2008

By Rob Farnfield, Charlie Adhock

The measurement of near-field shock has always been an attractive proposition for those working in the field of explosive and blast performance. The most commonly employed technique involves the use of piezoelectric accelerometers. Although highly effective, these complicated devices are relatively expensive and are often destroyed in the blast event. This paper describes the development and field-testing of a shock sensor of sufficiently low cost to enable it to be routinely used in product blasting. This new device is based on piezoelectric wafer technology and does not require any external signal conditioning. The device is housed in a small cylindrical package with approximate dimensions of 30mm (1.2”) length and 5mm (0.2”) diameter. It has been determined that the most effective way of fixing the device to rock is in a small diameter hole with epoxy glue. Alternatively the sensor can be simply placed in holes filled with either water or bulk emulsion explosive.

Jan 1, 2005

By B. Comley, M. C. Harris

There is as yet no accepted method of predicting flotation frother performance in plant processes based on laboratory scale characterisation techniques. This paper investigates the use of dynamic surface tension, using the maximum bubble pressure method, as a means of evaluating frothers and frother mixtures. An adsorption model is presented, which has been used to quantify the role of frother type and concentration during frother bubble interaction, based on the correlation of model parameters to physical frother characteristics. This approach was found to provide useful insight with respect to blending and selection of flotation frothers to meet specified flotation performance criteria.

Jan 1, 2001

By Sutham Niyomwas

Synthesis of alumina-mullite-silicon carbide composite (Al2O3-Al6Si2O13-SiCw) was obtained in situ by carbothermal reduction of a mixture of kaolin and two different silica sources. The carbothermal reduction was carried out in a horizontal tube furnace under flow of argon gas. The standard Gibbs energy minimization method was used to calculate the equilibrium composition of the reacting species. The synthesized products were mixtures of alumina, mullite and silicon carbide in the form of whiskers. The effects of adding two different silica sources of rice husk ash and silica powder to the mixture of kaolin and activated carbon were investigated. XRD and SEM analyses indicate complete reaction of precursors to yield Al2O3- Al6Si2O13-SiC as product powders, with the SiC having whisker morphology.

Jan 1, 2006