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By Vidyaranya Bandi, Madhav Madhira, Kota Vijay Kiran

"Using hyperbolic relationships for the non-linear responses of shaft and base resistances, a method is proposed for estimating initial shaft and base stiffnesses and ultimate shaft and base resistances of a pile from pile load test results. An iterative procedure is used to arrive at the values of shaft-soil and base stiffnesses and the ultimate shaft and base resistances. The method is applied to load - displacement data available from pile load test results to illustrate its efficacy.INTRODUCTIONA pile foundation is the most effective and economical solution in transferring large vertical loads to deeper depths. As the pile is subjected to axial load, the soil mass surrounding the pile is vital in providing vertical support for the pile. The nature of pile–soil interaction is three dimensional and to complicate the problem further, response of soil is nonlinear. Finding a closed form solution to such problem is extremely difficult. Several methods were developed to study and predict the response of the composite pile–soil system. Faruque and Desai (1982) implemented both numerical and geometric non-linearities in their three dimensional finite element model. Rajashree and Sitharam (2001) developed a nonlinear finite element model of batter piles under lateral loading using a hyperbolic relation for static load condition and modified hyperbolic relation, including degradation and gap for cyclic load condition.The ultimate capacity of the pile is estimated considering the strengths and unit weights of soil layers with depth, overburden pressure and other relevant parameters. The estimated capacities always need to be validated by conducting initial maintained load test. The estimated capacity may differ with the actual at site since the values of strength, stiffness, interface resistance between pile and soil, lateral earth pressure coefficient with depth and soil stratification, etc., differ from the design parameters considered for estimating the ultimate capacity of pile. The estimation of axial capacity of piles involves considerable uncertainties in selection of appropriate design parameters and the design rules are not always consistent with the installation procedures/processes involved."

Jan 1, 2017

By Yang Ge, Yuzhu Pan, Mansheng Chu, Jue Tang, Cong Feng, Lihua Gao, Zhenggen Liu

The low-grade nickel laterite ore used in this study was successfully upgraded through selective reduction by industrialized rotary kilns followed by magnetic separation. The results indicated that both iron metallization extent and nickel metallization extent showed obvious linear correlation. In addition, rational roasting temperature and prolonged grinding time could enhance the overall fineness level of reduced laterite nickel ore. The moderate roasting temperature at a range of 1100–1150 °C should be suitable enough to a conversion of total nickel to metallic nickel and partly inhibited the conversion of total iron. Ultimately, the obtained ferronickel alloy with a nickel content of 7.32% and an iron content of 84.15% was prepared successfully from the lowgrade nickel laterite ore containing a nickel content of 1.92%. Nickel and iron recoveries were 96.72 and 89.08% respectively, which achieved the highly efficient recovery and utilization of iron and nickel from low-grade laterite nickel ore

Difficulties were experienced in the identification of carbonate minerals intimately associated with iron oxides in the so called carbonate ore, which occurs at depth in the Iron Duke Orebody.Determination of refractive indices by examination under the microscope using the immersion method, together with inferred chemical composition indicates that dolomite and parankerite are common constituents. Histograms of the manganese and sulphur contents strongly suggest that manganese is associated with the carbonate minerals, and that the highest sulphur assays occur near the base of the carbonate body.From the present work it is concluded that refractive indices indicate only a very approximate composition for carbonates of the parankerite type.The different carbonate minerals occur in irregular zones.INTRODUCTIONThe Iron Duke deposit is situated in the southern portion of the South Middleback Range on Eyre Peninsula, S.A., 30 miles from Whyalla. (Fig. 1).Drilling at Iron Duke revealed a large body of so called carbonate ore, which was tested in detail at cross section 1000 ft. S by three diamond drill holes, DDH.57, 67 and 78. (Fig. 2)Most specimens of carbonate ore described below were obtained from DDH 67 and 78.GENERAL GEOLOGYThe South Middleback Range is composed of two parallel ridges trending north-south. The Iron Duke orebody is situated on the southern portion of the western ridge. (Fig.1) .The rocks of these ranges belong to the Middleback Group which rests on a gneiss complex. Their age is considered to be Middle Precambrian or late Archaean.

Jan 1, 1963

By M. A. Trevits, T. A. Gray, L. M. Crayne, P. Glogowski

Mine seals can he remotely constructed in underground coal mines through vertical boreholes when direct access to a fire is impossible or considered to he too dangerous. This method has great merit because the boreholes can be drilled to specific mine areas, and the seals can be positioned close to a fire zone. The technology however can be largely ineffective if the constructed seals do not provide of effective barriers to airflow or if they cannot he used to impound water and other inert materials. Unfortunately, no viable alternatives exists to sealing the entire mine to the ground surface. Full-scale remote mine seal construction research is being conducted at the National Institute for Occupational Safety and Health (NIOSH) Lake Lynn Laboratory (LLL). Under this effort. Howard Concrete Pumping Company and GAI Consultants Inc. have joined forces to evaluate a potentially significant improvement to the current state of the art. This paper covers the development o f novel technology or rewrote mine seal construction, the evaluation of rite materials used, the construction practice and the Fellow-up testing.

By Vaughan J. P

The Pegmont deposit is a stratiform Pb-Zn sulphide body occurring in a thin, iron-rich metasedimentary unit situated near the top of the Kuridala Formation, a part of the Mary Kathleen Group of the Middle Proterozoic"Eastern Geosyncline" succession of the Mount Isa-Cloncurry district. The deposit appears to have developed in a shallow basin or depression on a sea or lake floor.Detailed chemical and mineralogical study of seven diamond drill cores through the ore horizon shows that in addition to galena and sphalerite the orebody contains a large range of iron-rich silicates and aluminosilicates.Further, five drill cores selected to represent a section from basin centre to basin edge exhibit clear and systematic chemical and mineralogical changes in the ore horizon in both a vertical and, most importantly, ill a lateral sense.Reconstruction of the sedimentary environment of the ore horizon as a whole shows this to be a silicate facies of a phosphatic, manganiferous iron formation or, more accurately, of "ironstone" in the sense of James (1966, U.S. Geol. Surv. Prof. Paper 440, chapter W).On the basis of both mineralogy and chemistry this silicate facies may be subdivided into three microfacies according to the dominant iron silicates characteristic of each: a fayalite microfacies, a hornblende-clinopyroxenemicrofacies, and a garnet microfacies. Significant Pb-Zn sulphide concentrations are confined almost entirely to the fayalite microfacies.

Jan 1, 1979

By R F. G Phelps, C J. S Sangster, G S. C

Narrow vein metalliferous mining in the UK has a long history, but there are only two small gold operations at present (Clogau and Gwynfynydd). Four further gold properties are at various stages of evaluation (Calliachar, Cononish, Curraghinalt and Maestryfer). The South Crofty tin mine closed earlier in the year. Narrow veins are exploited underground and are challenging to evaluate because of their geologically variable nature. They are generally less than 3 m wide, discordant, of variable dip (

Jan 1, 1998

By Paul Staples, Paul Messenger, Greg Lane

"Every project is different. While “conventional” SAG and ball mill circuits will suit many projects, for others there are alternatives, which may produce improved outcomes. This paper examines particular examples of recent front end designs which either went against conventional thinking or which employed “out of the box” thinking to realize the desired results.One such example is the design strategy employed for a small capacity gold plant in Victoria, Australia. The selection of HPGR technology for small capacity projects is not generally favoured, given the relatively high cost of small HPGR machines. However, the unusual size distribution of the gold and its liberation characteristics were expected to lead to improved gold recovery offsetting the higher capital cost.Another example is the first large scale application of milling in acid for copper recovery, at a project in south east Asia. The stainless steel, single stage SAG mill using ceramic grinding media was more expensive than a mill constructed of conventional materials. However, the steps of scrubbing, slurrying, grinding and leaching could all be achieved in a single unit operation and the need for thickening and repulping with acid after milling was eliminated.Rod mills were selected for both primary and secondary milling duties for another south east Asian project despite their somewhat outdated reputation. A review of previous industry experience confirmed that rod mills could outperform conventional rod/ball or SAG/ball circuits in cases where the size distribution of the ground product is critical to downstream recovery.These examples are discussed with particular focus on the key drivers in each case."

Jan 1, 2008

By Juan Kobashicawa, Bernardo Falcón

En este trabajo se explican los controles automáticos desarrollados (In-House) e implementados en el circuito de Molienda de Compañía Minera Antamina, el cual abarca Molinos SAG, de Bolas y los Hidrociclones respectivos. Los controles implementados son basados en el Control por Lógica Fuzzy y las Bandas de Bollinger; así mismo se indican los criterios en el diseño de los controladores y las variables del proceso que se han tomado para la implementación donde se controla un indicador de distancia del centro de masa de la carga respecto al centro del molino de Bolas. Asimismo, se muestra el impacto positivo logrado con la estabilización del circuito.

Sep 1, 2017

Shaft sinking through an amphibolite-granite rock mass experienced rock bursts on the shaft walls and benches. However, rock burst phenomena was exhibited only in granite, which is e1asto-brittle with ability to store strain energy caused by orogenic and man made stresses. To improve ground conditions, blasting of destressing holes at shaft corners was carried out. By this technique rock burst during shaft sinking was minimized, but not eliminated.

Jan 1, 1982

By J. L. Kohler

Component failures in the electrical control circuits of mining machines account for a large percentage of the total downtime of the machine, Once a failure has occurred it is always a tedious and usually a time-consuming task to locate the failed component. Moreover, the pressure to quickly locate the cause of a delay can lead to compromises in safety. Thus an onboard diagnostic system, essential for an automated machine, would be a very useful addition to existing machines. This report details U.S. Bureau of Mines development of a generic procedure for synthesizing diagnostic systems for electrical-control-circuit failures in mining machinery. A continuous mining machine is used as the testbed to illustrate the application of the developed methodology. Substantive differences among mining machine control circuits made it impossible to achieve a generic diagnostic system, but a generic approach for the synthesis of the diagnostic system was possible. As the research progressed, it became apparent that an algorithmic approach was better than an expert-system-based implementation. A prototype system was constructed and used to evaluate the diagnostic system. Prototype implementation issues are also examined.

Jan 1, 2010

By H. S. Venkatesh R. Balachander, G. C. Naveen

During the construction of a 1020 MW underground hydroelectric project in Bhutan a huge rock fall took place in the Downstream Surge Chamber (DSC) during March 2016. The total quantity of rock in the fall area is estimated to be about 1,50,000m3 (2.6 billion cubic feet), out of which about 25,000m3 (0.44 billion cubic feet) of muck was removed. The removal of muck was stopped apprehending that the cavity formed due to the rock fall may get further aggravated leading to widening and destabilising the adjacent transformer hall cavern or it might day light as the top cover was about 190m (623 feet). As the fall has virtually blocked the 314m (1030 feet) long cavern and divided it into two different chambers (south and north), and that the muck cannot be disturbed, it was decided to erect concrete wall on either side of the fall up to the cavern roof and then later address the filling of the cavity with appropriate fill material. As the access to the DSC was there for the southern side it was decided to extend a cable tunnel which was terminated at a distance on the north side of the cavern by D&B so that once it gets punctured into the north wall of the DSC it can be used to access the fall from this front too. This is a unique situation where in every blast approaching the DSC, the parting between them is diminishing and hence the tunnel blast will be exerting axial load on the parting wall leading to dynamic transient loading conditions and buckling may take place on the northern wall of DSC. This paper describes the various drill blast combinations adopted for successful excavation of this tunnel.

Jan 1, 2019

The cost of preparing a feasibility study is notoriously difficult to estimate. Studies for mining projects are typically commenced when an exploration programme has identified a mineable resource and pre-feasibility studies have shown that development of the resource would lead to an economically viable project. Pre-feasibility studies will normally include an estimate of the cost of a formal feasibility study and this estimate would then be firmed up before a commitment is made to proceed with the formal study. Data for preparing the feasibility study cost estimate will be sketchy, geological investigations, metallurgical testwork, and marketing studies may be needed before the scope of the project and hence the scope of the formal study can be finally determined. Before an estimate of the work required and hence of the cost of the feasibility study can be prepared the source of project funds must be decided. Studies for internally funded projects are often less rigorous than those which must be "bankable" and subject to the scrutiny of external financial institutions. This paper sets out suggestions for preparing more accurate cost estimates for feasibility studies by ensuring that all activities are included and shows how a staged approach to preparing such studies can minimise costs and guard against cost overruns. It also provides a case study showing how the estimate compared with actual costs for a recent feasibility study completed by Pancontinental Mining Limited.

Jan 1, 1990

By Volker Vogt, Wolfgang Sand, Eberhard Gock

"For about 20 years, the use of bacteria to control the flotation process for the production of raw material concentrates has been the subject of worldwide scientific and engineering efforts. The objective is to reduce the consumption of biologically non-degradable toxic reagents. The principle idea is to use the activity of bacteria in natural leaching processes – known since the middle of the last century – for controlling flotation processes.It was discovered that the selective activity of bacteria during the extraction of raw material concentrates by means of flotation could also be achieved with extracellular polymeric substances (EPS), excreted by bacteria. EPS, which is extracted by means of centrifuging bacterial cultures, can help to significantly reduce the use of cyanides, approximately 200,000 t/a are used for ore dressing today.The bacterium used was Acidithiobacillus ferrooxidans. In order to identify the bandwidth of the oxidation activity, 21 bacterial strains of the strain collection of the University of Hamburg were attracted to iron(II) sulfate and pyrite under defined conditions. All strains oxidized iron(II) sulfate ten times faster than pyrite.EPS has so far been derived from four strains. In general, EPS extracts are divided into a hydrophilic and a hydrophobic fraction. The hydrophilic fraction is composed of e.g. fucose, rhamnose and glucose; fatty acids such as dodecanoic acid, hexadecanoic acid, octadecanoic acid and nonadecanoic acid were found in the hydrophobic fraction. Pure mineral phases and mineral mixtures were used for the flotation tests. The outcome was reproducible results with technical flotation machines. The research results known so far are mainly based on investigations with micro flotation devices, which are usually used for the characterization of reagents and which do not allow a direct translation to the technical scale."

Jan 1, 2003

OWING to the gradual depletion of the hitherto plentiful supply of firewood in the immediate vieinity of Queenstown and Gormanston, which caused a steady increase in the cost of fuel for domestic purposes, the Mount Lyell Company took steps several years ago to make available as a substitute electric current from its Lake Margaret hydro-electric supply. In order to make this practicable it was necessary that the cost of electric power for heating purposes should compare favourably with the cost, of fuel, and the installation of domestic appliances brought within reach of the average householder, and efforts have been continuously directed towards this end since the year 1928.WATER HEATERSThe installation of electrical apparatus in local dwellings began with hot-water services, the heating elements being the types then procurable on the market and adapted to meet requirements.These, however, did not prove satisfactory, but the study of their bilure resulted in a type being developed locally which has overcome all difficulties. The first type of water heater evolved was an outside circulation one the element of which consisted of an iron pipe through which the water passed, insulated with micanite and wound with nichrome wire, the latter being covered with alundun cement to keep it in position and prevent oxidation. This was insulated on its outside surface with a layer of asbestos flour, and connected to the hot-water container as shown in Fig. 1. It was found, however, that the iron pipe had a short life, due to a certain amount of acidity in the water, and a copper pipe was substituted which proved very durable. Some heaters with this improved type of element are still operating after six years of use. The resistance wire is run at a very low current density, which ensures durability.

Jan 1, 1927

By M. R. Dion, K. Frenette, R. K. Jonas, S. Simard, F. Robichaud

"In 2011, a site study indicated that the application of Honeywell’s Multivariable Predictive Control Technology (MPC) to the Goldex processing facility would provide significant opportunities for improvement. Grinding MPC was implemented in the SAG Mill in June 2015. This pilot application, called Phase 1, featured one of the first Multivariable Predictive Controllers to be installed in a Canadian mineral processing plant. Since the implementation of MPC, gold recovery from the gravity circuit has increased. MPC contributed to a decrease in flotation feed particle size (120 to 112 µm) and an increase in the SAG feed tonnage (8.5% increase). MPC also increased and stabilized the % solids of the SAG feed, which can have an impact on cost reduction (mechanical maintenance). Additionally, MPC increased productivity, providing grinding operators with more time to perform other tasks. Further anticipated benefits include the standardization of the grinding circuit operation from one team to the next, thereby minimizing circuit disturbances resulting from different operating philosophies. This paper will discuss the advanced control project development and justification, the technology and rapid implementation process, the performance results and the benefits obtained.IntroductionGoldex is an underground mine located near Val-d’Or that is owned and operated by Agnico Eagle Mines Limited (AEM). Between 2008 and 2011, mining focused on the Goldex Extension Zone (GEZ). In 2011, the project was halted due to geotechnical problems; operations ceased until late 2013. Goldex operations resumed in September 2013 with the M and E zones, for which there were 0.7M gold ounces of proven and probable reserves, 2.1M ounces of measured and indicated resources and 1.2M ounces of inferred resources, totalizing 4M ounces. Life expectancy was extended until 2024."

Jan 1, 2017

By K. L. Whitehead

An examination of 60 mines, 11 illumination hardware manufacturers, and Q mobile face-equipment manufacturers was conducted to determine the state of the art of mine-illumination hardware, define lighting system installation and maintenance problems, and assess personnel acceptance of lighting. Longwall and mobile face-machine illumination were studied. Major problems on room and pillar installations include damage of exposed components, electrical failures, and reduced lamp life, with extreme variability in the degree of these problems. Most longwall systems had low or moderate maintenance requirements, cable damage being the most significant problem. Most mobile face-equipment operators liked their machines' lighting systems, but many complained of glare and other problems. Longwall lighting was unanimously accepted by face personnel, and most complaints were minor. Based on the survey, general installation and maintenance guidelines have been established, addressing hardware design aspects, approaches proved effective to minimize problems, and improper practices noted which are detrimental to effective lighting.

Jan 1, 1981

By O. Bernal, G. Velarde

Sociedad Minera Cerro Verde, majority owned by Phelps Dodge produces 200M lbs per year of LME Grade A copper from low cost leaching of secondary sulfides and SXEW processing. Central to the success of Cerro Verde has been the continuous improvement of leaching practices which currently yield over 80% recovery of the contained copper in the ore. This recovery has been achieved by careful attention to operational practices and leaching process fundamentals. This paper details the development of the concept of “Lixiviant Request Rate” where by solution is applied at an optimal rate for the grade, mineralogy, and the point in the leach cycle. Also paramount to the success of Request Rate technology has been the development of irrigation practices such as drip irrigation and irrigation grid design. These developments have ultimately resulted in improved copper production, decreased sulfuric acid and water consumption, decreased pumping cost, and more consistent PLS grades.

Jan 1, 2004

By Robert H. Robinson, Levent Ozdemir, Russell J. Miller

The paper summarizes an investigation into the applicability of mechanical excavation to oil shale mining; identifies available machine types that are best suited to various aspects of the mining operation; presents preliminary comments on the configuration of an "IDEAL" oil shale mining machine; and establishes the background information necessary for conceptualizing and evaluating new mining methods using mechanical excavation equipment. Conclusions are also presented as to the best currently available systems, as well as potential future systems.

Jan 1, 1983

By G. K. Mann

Fragmentation analysis of blast or crushed rock material is a time-consuming and costly process. During the last two decades, the mining industry has been investigating image-based analysis systems as an alternative to generate fragmentation results. Many image-based techniques and commercial products have emerged during the last few years, and the mining industry has recently begun using these tools for real-time estimation of size distributions. Some existing systems require manual image editing to add or delete edges (or net) before executing the fragmentation analysis routine. This manual procedure may take hours of time for each image analyzed. Reliable and robust image segmentation should be able to handle a wide range of rock textures and sizes under a variety of lighting conditions. This paper describes a novel software application, which has the capability to autonomously capture images and analyze them to generate the particle size distribution. The system can also process a batch of images captured during a fixed duration of time and produce the overall particle size distribution. The new method has different layers of segmentation modules, which allows the system to operate under a wide range of rock textures and lighting conditions. A new grey-level slicing technique is developed which can perform under a range of illuminating conditions. The Canny-based edge detection technique is used to segment rocks appearing in dark regions.

Jan 1, 2006

By J. D. Noll

Elemental carbon (EC) is used as a surrogate for regulating the exposure to diesel particulate matter (DPM) of underground metal/non-metal miners. EC was chosen as a surrogate because EC is selective to DPM and is a major component of DPM. Using EC as a surrogate also gives one the advantages of no sampling artifacts and being able to sample at all locations in the mine. Currently, EC represents DPM well in underground mines. Some control technologies have been shown to possibly alter the relationship between DPM and EC and characteristics of DPM. Therefore, future work will investigate the relationship between DPM and EC as new control technologies are implemented.

Jan 1, 2002