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GOLD has played a part in the development of Australia. The total yield exceeds SIX hundred million pounds sterling, while the glamour of gold-mining and the unfailing demand for the product have enhanced its influence. The production is still considerable, but the yield is less than one-quarter of that twenty years previously, while the number of men employed has dropped from 70,000 to 11,000. Not only has there been a marked decline in production, but it is anticipated that thisdecline will continue, and continue more markedly. It is therefore desirable to ascertain the causes of the decline and inquire into means for diminishing or preventing it.The problem under discussion is far from being only local. Finlay states: The grand feature of the history of the business has been the progress of an economic cycle unfavourable to gold milling. The USA yield fell from $101,000,000 to $44,000,000.South Afriea has for some time produced one-half of the world's gold; yet in the Mining and Scientific Press of 11th February, IH22, General Smuts is quoted as saying that if the premium disappeared entirely 24 out of 34 mines would shut down. The solution, however, might be either general eg, a great advance in the metallurgy of gold; or local eg, a bonus; but before discussing any of the proposed solutions it will be advantageous to review the situation.STATISTICS OF THE PAST AND PRESENT PRODUCTION OF THE WORLD AND OF AUSTRALIAThe inquirer soon finds that there is a good deal of uncertainty, and that much care is needed in collating figures. In some cases a considerable part of the output is not officially reported, and returns...

Jan 1, 1924

By Marco Taipe

Uno de los mayores costos del proceso minero es el de perforación, en tanto emplea aire comprimido. Por tal motivo, la industria minera busca diferentes alternativas para reducir los costos del aire comprimido o eventualmente a través del uso del sistema electro-neumático. Este sistema es de fácil instalación y mantenimiento puesto que se basa en electricidad y agua, reduciendo costos y a su vez mejorando las condiciones de trabajo a través de la versatilidad del presente sistema.

Sep 12, 2011

By V. T. McLemore

Deposits of rare earth elements (REE) are found in NM, but they have not been important exploration targets in past years because demand has been met elsewhere. However, with the projected increase in demand and potential lack of available production from China, the New Mexico deposits are being re-examined for their potential. REE-Th-U veins are found in the Gallinas, Caballo, Capitan, and Cornudas Mountains and Laughlin Peak-Chico Hills. Past production of bastnaesite has come from the Gallinas Mountains. Carbonatites are found in the Lemitar and Chupadera Mountains, Laughlin Peak-Chico Hills, Lobo Hill, and Monte Largo (Sandia Mountains). Although carbonatites have not been found in the Gallinas Mountains, they are suspected to occur in the subsurface based upon mineralogy/alteration. Disseminated Y-Zr deposits in syenite are found at Pajarito Mountain, Mescalero Apache Indian Reservation near Ruidoso. In 1990, Molycorp, Inc. reported historic resources of 2.7 million short tons grading 0.18% Y2O3 and 1.2% ZrO2 as disseminated eudialyte. Two additional deposit types have potential for REE in New Mexico: Cretaceous heavy mineral, beach-placer sandstone deposits and pegmatites. Exploration is ongoing in the Lemitar, Gallinas, and Cornudas Mountains.

Jan 1, 2012

By Tristan Worsey, Nathan Rouse, Kyle Hall

Drilling accuracy is the foundation to any successful blast operation. Even the best blasting practices cannot overcome poor drilling and still obtain desired results. Inaccuracies in boreholes can result in flyrock, increased vibration, uneven floor, and other undesired effects. As depth increases, variation in actual burden and spacing is expected even if collars are located precisely. Problems arise when this deviation reaches a point where it adversely affects the function of the blast design. Not only can unsafe conditions such as insufficient burden at the face develop, but poor fragmentation can compound adverse effects. As with any troubleshooting, problems cannot truly be fixed if they cannot be measured. As a result, significant work has been done in the past on this subject. Currently, there are both cheap and expensive methods used to quantify deviation for a given borehole. However, implementation of these techniques is limited. In general production blasts, little is known about the variance in designed versus true borehole geometry. This is especially true if the blaster does not see telltale signs of drilling deviation. However, losses in blast performance may exist and provide an opportunity to obtain better fragmentation and reduce fines. As drill and blast operations strive for better optimization, greater focus is being placed on drilling accuracy and solutions to this problem. The following paper details the use of several current methods for deviation measurement in order to help prevent compromises of safety and improve overall blast performance.

Jan 1, 2018

By Dhar B. B, Gupta R. C

Grinding of iron ore is an essential step to utilise ore fines for pelletisation needed for DRI units. While preparing iron ore pellets for DRI production, the iron ore needs extensive grinding which is highly energy consuming step causing the process to become non-viable in some cases. In the present paper an attempt has been made to evaluate grinding performance of thermally treated ore compared to normal ore grinding. Such thermal pre-treatment has been found to reduce the energy requirement with lower consumption rate of grinding media. It has been observed that by applying thermal shock the ore is rendered weak with improved grindability. The stresses generated due to thermal treatment may extend existing micro-cracks in the ore and in some cases it may even nucleate fresh cracks. Experimental studies carried out on thermally treated hematitite ore reveals that the heating to 400¦C followed by water quenching can cause a reduction of 45 per cent in grinding energy. The paper gives the details of the experiment and the Results.

Jan 1, 1999

By M. A. van Nierop

Load behaviour in an industrial mill has been measured directly by inserting probes through liner bolts. The data from conductivity probes have indicated the presence of premature centrifuging during manipulation of the load mass. Overloading conditions were also encountered. Overloading and premature centrifuging both reduce the power drawn by the mill. These effects have been successfully modelled.

Jan 1, 1997

By John Wise

Significant movement to an existing slurry wall which serves as a retaining wall on 'O' Street in Southeast Washington, D.C. initiated the Department of Public Works for the District of Columbia to invite specialty contractors to propose a rehabilitation and stabilization for the failed slurry wall. Nicholson Construction Company proposed and was awarded a contract for the construction of an anchored precast lagging and soldier pile wall to be located approximately 4 feet in front of the existing structure with granular fill placed between the new and existing walls. Stabilization of the existing slurry wall also included drilling horizontal weep holes and demolishing the failed panels down to the existing ground surface. A new and improved drainage system was also constructed to increase the amount of water directed toward the existing storm sewer system running along 'O' Street. This paper provides a detailed account of these construction activities.

Jan 1, 2003

By Reda M. Bakeer

"Measurements obtained during load testing of two steel H-piles driven at a site in Northeastern Mississippi are discussed. The general site conditions, equipment used, testing procedures and results of the pile load tests are presented. Both piles were tested in compression and one of the piles was subsequently tested in tension. The piles were instrumented with strain gauges and extensometers to measure the mobilized soil resistance and pile movement. Three different “zero strain” conditions were used to determine the mobilized soil resistance and residual loads due to driving or a load cycle. It was concluded that the effect of residual loads on driven piles could be significant. Driving residual loads influenced the magnitude and distribution of the load transfer curves more than those due to a load cycle. Results of the tension test were impacted by the residual loads from the previous compression test performed on the same pile.INTRODUCTIONSeveral factors affect the performance of a deep foundation system including the subsoil conditions, loading settings, pile type and installation method. Residual stresses develop in piles particularly due to pile driving, but they are typically not accounted for in the analysis (Fellenius 2002). Siegel and McGillivray (2009) presented an assessment of residual loads measured during load testing of instrumented auger-cast-in-place (ACIP) piles. The magnitude and distribution of residual stresses along the pile shaft and toe depend on the pile installation method, previous load cycles and time effects. Poulos (1987) reported that residual load due to driving at the pile toe is independent of pile driving equipment and may significantly affect the results of a pile load test. Hunter and Davisson (1969) reported results of pile load tests performed in compression on fully instrumented piles driven in cohesionless soils along with a discussion of the effects of residual loads. Tension loads of about 445 kN (100 kips) were measured at the pile toe after driving. Unloading residual compression load at the toe was detected as “apparent” tension since the instrumentation was zeroed prior to the test. The researchers suggested a graphical approach to obtain the “corrected” load distribution curves considering that residual load will dissipate following the tension test. Holloway et al. (1975) conducted a study on the effect of residual stresses due to pile driving and developed a computer software that accounts for residual loads. Briaud and Tucker (1984) suggested a method to account for residual loads based on the results of 33 pile load tests performed in mostly cohesionless soils."

Jan 1, 2017

By Hargraves A. J

With increasing depth, stresses and stress phenomena are becoming more important considerations in Australian coal mining.A large number of compressive and tensile strength tests was made on coal and rock cubes cut from samples taken in various Australian collieries. In addition, an empirical impact strength test was carriedout on fragments of the same samples, to obtain a correlation with compressive strength.In one colliery, flat-jack measurements were taken to assess stresses in coal ribs and in the roof.INTRODUCTIONBy world standards, some of the New South Wales collieries are approaching depths of cover considered a maximum for bord and pillar the normal Australian coal mining method. Several South Coast collieries are winning coal at depths of about 1500 ft., and future operations are being planned at deeper cover. Some areas of these deep workings produce considerable quantities of seam gas.Phenomena associated with high stress and copious gas under pressure in the seam violent phenoma presenting a danger and a nuisance in mine working - have occasionally occurred, and the phenomena are being investigated as a whole (Hargraves, 1958), and separately as a gas problem (Bolt and Innes, 1959; Hargraves, 1962) and as a stress problem. This paper relates to the latter - to investigations into the strengths of coals and coal measure rocks, and into the stresses in and about coal seams...

Jan 1, 1962

Probably no other country or coutinent has so many rich deposits of various different minerals as Australia. Long ago in the days of my boyhood in the old land the marvellous discoveries of high percentage copper at Burra Burra, Peak Downs, Yudanamutana, and other mines, was one of the principal themes of conversation in mining circles whilst the specimens of malachite, azurite, etc, brought home by returning miners were the admiration of my boyish eyes.Later on the WalIaroo and Moonta mines still further helped to heighten the reputation of Australia as a copper-producing country. During the 21 years that the writer has been resident in the Australian colonies, other mineral deposits have sprung into prominence, and with a Mount Bischoff for tin, a Broken Hill for silver and lead, and a Mount Morgan for gold, Australia can now boast that it has had within its borders the leading mines of the world, in four different minerals, and still at least maintains that pre-eminence in gold, silver and tin. To the miner from the old land, Australian mining is at first a revelation and a wonder. In very many instances he looks in vain for the regular strike and dip of the veins he has been accustomed to'Smooth hanging and foot alls are often wanting. 'Huge irregular deposits, like those mentioned above, viz., Burra Burra, Mount Bischoff, Broken Hill, and Mount Morgan, are mysteries that will take time to fathom-if, indeed, they are ever thoroughly understood and in many a smaller deposit there is much to interest alike the professor in the college and the miner in the mine.

By George G. Goble

The use of augercast piles has been limited by the engineer's concern for the structural quality of the installed pile. The nature of the pile is such that its final structural continuity is very dependent on the skill of the personnel that do the installation. Thus, NDT methods have been used to verify integrity and when problems are indicated the available solutions are usually quite costly. If information were available during the pile installation so that immediate steps could be taken to correct perceived problems, the concerns of the engineer could be addressed and the system would gain increased reliability. Pile Dynamics, Inc. has developed a quality control system, the Pile Installation Recorder for Augered Cast-in-Place piles (PIR CFA). This system consists of the following devices as shown in Figure 1. 1) The Control Unit powers the sensors, conditions the signals from the sensors, records all measurements, takes input information from the operator, displays the results, and stores the recorded data on a flash card for later permanent storage and processing. During the use of the system all of the results obtained during a test are seen during recording and can be reviewed on the screen again after completion of the installation. The ability to review the measured information makes it unnecessary to print a copy in the field. Since printers often give difficulty in the construction site environment the ability to review the results quickly after completion of the installation is an important capability.

Jan 1, 1997

By T S. Giraudo

The Macraes Gold Project, operated by GRD Macraes Limited, engaged GRD Minproc Limited to assist with the evaluation of a pressure oxidation circuit, this being the key component of a recovery enhancement project. The initial study gave sufficient confidence in the process to enter into project execution. GRD Macraes Limited was the first company to license Newmont Mining Corporation's pressure oxidation technology, which aims to improve gold recovery from the carbonaceous sulfidic flotation concentrate. This paper outlines the fundamental chemistry of the process followed by a description of the plant that was ultimately installed. A summary of the commissioning is given together with an overview of the production results to date. The project ramp-up was rapid, with design temperature and throughput being achieved within days of hot commissioning. Gold recoveries have exceeded expectations, improving from around 70% prior to the installation of pressure oxidation to above 84%. The project has increased the nominal gold output at Macraes from 120,000 oz/y to 170,000 oz/y. On-going plant optimisation for process parameters is discussed, giving rise to flexibility in gold production, with key controlling parameters exceeding design.

Jan 1, 2000

By D. D. Banerjee, S. K. Kawatra, T. C. Eisele

A high calcium fluid-bed combustor ash has been shown to be an effective binder at dosages of 1 to 2% of the magnetite concentrate weight. Magnetite pellets 1.3 cm (1/2 inch) in diameter were produced with dry crushing strengths greater than 22.3 Newtons/pellet (5.0 pounds force/pellet), which is comparable to the results produced using conventional bentonite binder. The effectiveness of fly-ash-based binders was considerably improved when calcium chloride was added as an accelerator. Addition of calcium chloride at a rate of 0.1 to 0.2% of the total powder weight increased the strength of dried pellets by as much as 22% compared to the strength of pellets made using fly-ash without accelerators.

Feb 24, 1997

By C. E. Dobbin

The coal fields of Montana are widely distributed through the plains region in the eastern and northern parts of the State, and the mountain regions in the central, southern, and southwestern parts of the State. (See fig. 1.) SURFACE FEATURES The Fort Union region in eastern Montana is a broad plain of almost horizontal rocks, characterized by extensive "bad lands" along the larger streams and by red hills, benches, ridges, and buttes which represent shale and sandstone that have been fused by the burning of an underlying coal bed.

Jan 1, 1932

By M. Y. Solar, W. G. Davenport

Most of the recent growth in nickel demand has been for the production of stainless steels and virtually all of it has been satisfied by new ferronickel and nickel pig iron projects. But "good" laterite resources are more and more difficult to find: Ni grades are decreasing while Fe contents are increasing and SiO2/MgO ratios vary from 1 to 3 and even higher if limonites are included. Predicting the smelting behaviour of such ores requires a more fundamental understanding of the thermodynamics of these systems in commercial operations. One valid question is thus whether these furnaces are at thermodynamic equilibrium or not. The present paper investigates this question, compares calculated and measured O2 partial pressures and mechanical/chemical slag loss ratios and concludes that ferronickel furnaces are not at thermodynamic equilibrium. This departure from expectation is actually to the operators’ advantage: the targeted ferronickel grades can be obtained at lower reduction potentials than calculated from pure thermodynamics.

Jan 1, 2014

During August, 1926, with the consent of Mr. Schell, mine manager, the writer conducted a mill test on this company's concentrators. Mr. Schell not only gave him his permission, but rendered all possible assistance. Although it was impossible to take all the samples one could have wished to obtain, yet the salient points of the mill flow-sheet were sampled for a continuous period of eight hours, and from these samples and separate data supplied by the manager, valuable information was collected.THE MINEThis is a true vein-type of mine; the lode formations, striking almost due north-south, cut the large porphyritic intrusion at right angles. There are three distinct veins on this property - parallel, persistent, and dipping at an angle varying between 40° - 50° to the horizontal.The country rock is very sound, and timber, save for the small amount required for ore chutes, is entirely absent from all mine workings.The lode varies from a width of 1 in. to 8 in., but the stopes are carried forward with a minimurn width of about 30 in.The mine is particularly dry for a West Coast property, and conditions underground are very favourable. Air drills are used...

Jan 1, 1928

By R. N. Powell

The Pipeline ore body was discovered in March 1991. The construction of the new mine and mill did not start until early March of 1996. Upon completion of permitting and corporate project approval, the 289 million USD project was “fast tracked”. The commissioning began 11 months after start of construction and the project ended 40 million USD under the budget figure. The objective of this paper is to review and highlight the Pipeline Project history from discovery, design, lawsuits, permitting, and re-design through to current - 1998operating practices. Particular emphasis will review the process design, design mistakes, and design successes. The paper will review project history, feasibility, design concepts, operator training, construction, financial and the current operation. Additional discussion will review what design features worked and which did not work within the process plant.

Jan 1, 1999

By Fredrik Sarvell, Leo-Ville Miettinen, Veli-Matti Uotinen

"Abstract The continued concentration of building activities in cramped areas of city centres means more underground construction and facilities. Demand to minimize execution time and any kind of disturbance to business, general traffic, people and nearby technical structures is increasing. To answer these challenges foundation business has to develop schedule-wise and technically reliable deep excavation and foundation solutions in vulnerable surroundings and challenging soil conditions.Drilled pipe pile wall – RD-pile wall – is a combination of Ruukki drilled steel pipe piles and interlocking sections. Individual RD piles, typical diameters between 219 mm to 610 mm, are connected to each other with interlocks welded to the piles on the automated welding line at the workshop. The matching dimensions of the drilling system and interlocking sections allow the installation of RD piles through stones and boulders and even into the bedrock, if necessary, in a single operation. Installation is done by a down-the-hole hammer (DTH) using the centric drilling system and oversized ring bits or a drilling system consisting of a pilot bit and reamer wings.RD-pile walls have been used as permanent and temporary retaining walls for different kinds of demanding excavations and structures, such as bridge foundation, as quay wall and as sealing structure in rehabilitation of an existing dam. Rigidity and watertightness of the lower end of the RDpile wall is being researched as well as fire design issues examined. One of the most fascinating RDpile wall solution is to utilize the wall as a permanent underground basement wall. Reliable and rigid connection to bedrock decreases the bending moment and deflection of the wall and good fire resistance in addition to large variety of pile dimensions and steel grades gives possibilities to design and execute a cost-efficient basement wall and foundations without temporary retaining wall works. 1. IntroductionIn northern Scandinavian soil conditions, installation of sheet pile walls, or even secant pile walls, is often problematic due to the existence of hard and large boulders in the overburden, and especially when the retaining wall structure should penetrate to or into the hard bedrock. On the other hand, an efficient and reliable piling technique suitable for the demanding soil conditions described above, percussion drilling, has been developed since the 1960’s, and especially from the mid-1990’s, when the concentric drilling method with the ring bit and pilot was introduced. A new retaining wall application, the RD pile wall was developed by combining that drilling method with the widely used retaining wall solution based on steel pipe piles and welded interlocks (a pipe pile wall normally installed with vibratory or impact hammers)."

Jan 1, 2014

Several factors contributing to the loss of fibre during treatment are a function of the paragenesis of the veins. The occurrence, of magnetite from the cap rock within the veins prevents complete fiberization. There is a marked similarity between these veins and those in the Koegas-Westerberg area of South Africa.INTRODUCTIONAn investigation of the mineralogy of the Wittenoom Gorge crocidolite veins was undertaken in the latter part of 1962 at the request of the Colonial Sugar Refining Co. Ltd. It was anticipated that such a study might reveal the cause or causes of the lack of recovery of some asbestos during beneficiation. Some interesting features of the mineralogy and paragenesis of the crocidolite veins become apparent, but it is emphasized that the investigation is far from complete, as the study did not extend to the field occurrence.The samples examined were selected from the mill and from the untreated ore.GEOLOGICAL SETTINGWittenoom Gorge is situated on the Fortescue River in the Hammersley Ranges of Western Australia and is one of several gorges in these ranges, on the sides of which 'crocidoIite asbestos is known to occur. The Hammersley, Ranges consist essentially of a series of quartzites, shales, ferruginous quartzites and dolomites. These' rocks are part of the Nullagine Formation (Proterozoic) and are usually either horizontal or gently folded. In some 'areas small beds of riebeckite as well as crocidolite are known to occur interbedded in the sequence.Riebeckite is a monoclinic amphibole, the formula of which may be stated as Na2Fe2"Fe2" (OH) 2Si8O22, and crocidolite is a fibrous variety of this mineral. This formula...

Jan 1, 1963

By Maurício Covcevich Bagatini, Maycon Athayde

Nowadays, the HPGR (high-pressure grinding rolls) is an intermediate step between filtering and balling in the most modern iron ore pelletizing operation. The operation debottlenecks filtering process and reduces pressure over the typical milling process to control particle size to the balling. The present study evaluated aspects of microwave application to the iron ore concentrate fed to HPGR in a bench scale unit. Iron ore concentrate was irradiated varying the microwave exposure time and grinding efficiency was evaluated. The moisture influence in the HPGR efficiency was also assessed. The pellet feed blaine surface area (BSA) improved by 300 cm2/g and % < 325# fraction by 3%. Scanning electron microscope (SEM) images show the formation of micro-cracks onto the particle surface induced by microwave; the effect observed helped improve the milling process performance, in addition to the moisture reduction observed due to the temperature increase.