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By J. H. Maritz, Uludag. S.

"*Paper written on project work carried out in partial fulfilment of B.Eng(Mining Engineering) degreeAfriTin Mining Limited plans to reopen the Uis tin mine in Namibia and establish a pilot processing plant for phase 1 of the Uis tin project, which is scheduled to commence in the last quarter of 2018 . A mining plan is required for phase 1 to supply the new pilot processing plant with 500 kt of run-of-mine ore per annum, for a period of 5 years. New geological mapping and three-dimensional modelling of the mining area were utilized to identify the most optimal mining locations that require low initial waste stripping. An open-pit mining method was selected to target the surface outcrops of the pegmatite orebodies. The mine design criteria were determined and used as input to generate the mine design by utilizing professional engineering software. The mine design was optimized and an overall stripping ratio of 0.81 was achieved. A 5-year production schedule was developed for the mine design according to quarterly periods of three months. A fixed production target of 125 kt of ore was assigned to the quarterly periods, and a ramp-up production target of 65 kt of ore was assigned for the first period. The mobile mining equipment requirements were calculated, and recommendations were made for implementing the 5-year mining plan. IntroductionAfriTin Mining Limited is the owner of the Uis tin project in Namibia and plans to reopen the Uis tin mine, which is located near the town of Uis, approximately 164 km north of Swakopmund. The Uis tin mine was owned and operated by Imkor Tin, a subsidiary of Iscor South Africa. Mining commenced in 1958, and the operation was closed in 1991. Steffen Robertson & Kirsten (SRK) defined the life of mine (LOM) plan for the historical Uis mine in 1989. The SRK report estimated the historical resources and reserves, which consisted of sixteen cassiterite-bearing pegmatite orebodies. SRK developed the most economical pit designs to provide the highest average tin grade at the lowest practical waste stripping ratio. Exploration data from the SRK report of 1989 was used extensively throughout this study, since no new exploration drilling has been conducted. The pegmatites are present as large, subvertical and outcropping veins up to 100 m in thickness. Once phase 1 is operational, mining will be conducted using conventional open pit mining methods. Initial production will be from exposed pegmatite veins in the old mine workings. AfriTin plans to establish a pilot processing plant by the end of 2018 to beneficiate run-of-mine ore at a rate of 500 kt per annum."

Jul 1, 2019

By M. Kane, B. Bissonnette, D. Hodouin

"A laboratory cell has been designed for a careful investigation of gold ore cyanidation using mathematical modelling of the process kinetics. The cell is a stirred vessel with continuous monitoring and control of pH, oxygen and free cyanide contents. Samples are automatically extracted for gold analysis. The instruments are connected to a microcomputer which records all the measured variables and calculates the reagent consumption (air or oxygen, cyanide, lime). For cyanide control a sample is automatically extracted and filtered and the solution analyzed, using a specific electrode, by a flow injection technique. The rate of gold dissolution is modelled using a kinetic model the parameters of which are calculated by a non linear least-squares technique. The parameters of an empirical model of reagent consumption are also estimated. The resulting model is used in a simulator for gold cyanidation plant design, tuning and control.INTRODUCTIONThe leaching of gold ores in a cyanide solution is the usual method for gold extraction from raw ores. This process requires long reaction times and leads to very significant consumption of cyanide. The optimization of the cyanidation plant operation is a very important aspect of gold ore processing for increasing gold recovery and decreasing operating costs. The key parameters to the improvement of gold extraction are the selection of an efficient solution chemistry, the design of the size and the arrangement of the equipment and the correct tuning of the operating variables. Automatic control strategies can then be applied to maintain industrial operations at their optimum setpoints.Two approaches can be used for optimizing design and control of cyanidation circuits, either empirical trials for improving process performances or mathematical modelling of the process kinetics for subsequent analysis, simulation and optimization. The advantages of the second approach, which is used in this study, is that it gives a systematic pattern to interpret data and reliable tools, in as much as the models are good, to improve operation performances. In order to determine the structure and the coefficients of cyanidation models, well controlled measurement and calibration procedures must be used. The purpose of the paper is to present an equipment and a test procedure for modelling the kinetics of gold ore cyanidation."

Jan 1, 1990

In 2001, 14,623 mining operations reported employment statistics to the Mine Safety and Health Administration (MSHA). This was an increase of 210 mining operations compared to 2000. Almost half (49%) were sand and gravel mines, followed by stone (29%), coal (15%), nonmetal mines (5%), and metal mines (2%).

May 1, 2003

By Steven Townend

Mining-related activities have been known to create a challenging operating environment for mining companies located in close proximity to communities. Issues such as noise, vibrations from mining operations, land use and emissions are often a concern for community residents. In order to develop good community relationships it is necessary to take a proactive approach. This paper documents this approach and also deals with the social implications for Vale associated with mining activities in the heart of the community of Copper Cliff, Ontario, Canada.

May 1, 2011

By M. A. El-Sohby

The paper describes some problems encountered with the foundation of a deep drainage caisson constructed on the Nile Bank in Cairo. The use of suction dredging while sinking the caisson led to a piping failure of the sandy soil in the base which was loosened during the process of pumping. A study was carried out to investigate the problem and a procedure was adopted to retain the stability of the caisson.

Jan 1, 2010

Advanced Jig Separation of Shredded Plastics The authors have reported that the RETAC jig is very useful in separating relatively low density particles such as plastics, and demonstrated that highly efficient jig separation of plastic components in discarded office machines is possible in pilot-scale tests. To further improve the separation efficiency, a hybrid jig (RETAC jig with air bubbler under the particle bed) which can separate plastics having similar specific gravities using differences in wettability produced by a pretreatment, and a reverse jig (modified RETAC jig for plastics lighter than water) were developed. This paper reviews the separation of shredded plastics using advanced jig separation technology (RETAC, hybrid and reverse jigs). Wettability control of the plastics for the advanced jig separation is also reported.

Sep 13, 2010

Project Schedule ?Construction 2005 ?2008 (3 years) ?Operations mid 2008 ?2020 (12 years) ?Closure 2020 ?2023 (3 years) ?Post-closure monitoring Victor Economic Facts ?$982 million investment; ?$110 million already invested in the Project; ?1100 person years of employment in construction; ?375 full time positions during operations;

May 1, 2006

By Thomas E. Brown

Commercd explosives have evolved through this century f?om dynamite through ANFO to the current lines of Water Gels and Emulsions. Water Gels and Emulsions evolved to counter the lack of water resistance and density of ANFO yet maintain its low cost position verses dynamite. Today, explosives must be safe and inexpensive and perform under a wide range of temperatures, function efficiently in wet or dry boreholes and have a good shelf life. Emulsions meet this criterion, which is why they are the current trend products worldwide.

Jan 1, 1998

By D. J. Kemp

The 20th century saw changes in the mining and metallurgical industry not only technically but also in social and environmental expectations. As projects continue to become larger their visibility raises concerns among many groups. For mining companies, transparency, openness, and early engagement of all parties are fundamental to assure success. An equally important task is to anticipate the standards that will be required to meet society’s expectations in the 21st century.

Jan 1, 2005

By George D. Raitt

Anyone who has spent any time in and around the drilling and blasting profession knows that probably the most critical part is the drilling portion. A blasthole is nothing more than a cylindrical vehicle designed and strategically situated to hold and contain an explosive charge so that it can be detonated in the most efficient and optimum manner possible. It matters very little if the latest “State-of-the-Art” explosive or detonation system Is employed if the hole is poorly placed; i.e. excessive burden and spacing, sized incorrectly for desired results, insufficient in depth etc.. This is not to mention that the drilling phase is the most expensive, requiring sizeable initial outlays and upkeep. It’s also true that improper drilling can cause costs to skyrocket throughout the remainder of the work cycles such as excavating and hauling, crushing, screening and so on.

Jan 1, 1990

By M. Q. W. Jones

This paper summarizes important features of a compilation of thermal properties of stratified rocks from Witwatersrand gold mining areas. The database consists of more than 1000 thermal conductivity measurements, more than 700 density measurements, and nearly 100 heat capacity measurements. Most important rock types and stratigraphic units are well represented. Heat capacity does not differ significantly from one rock type to another, and density is relatively uniform although particular rock types are characterized by distinct average values. Different rock types also have distinct thermal conductivities, but this parameter varies by a factor of four to five. Primary factors controlling the thermal properties are mineral composition, degree of metamorphism, and porosity. In addition, the temperature dependence of thermal conductivity and heat capacity of quartzite may significantly decrease the thermal diffusivity of this rock at deep mining levels.

Jan 1, 2003

By Michael Olmsted

Inspection of boreholes prior to blasting can result in cost reductions as well as increases in efficiency and safety. Until recently, borehole inspection was performed in two manners. For simple inspections, a flashlight was used to view the upper part of the hole. More thorough inspections were performed with long tool strings developed for oil field applications. Borehole inspection tools developed specifically for mining and blasting applications have now been developed. Video Cameras developed for borehole inspection have been in service for several years. Now measurement tools are available, developed specifically for mining.

Jan 1, 2000

By I. O. Ojala

Detailed knowledge of velocity-depth trends is essential for constructing well-to seismic ties, determining background velocity and generating synthetic seismic traces for interpreting seismic amplitudes in terms of porosity, lithology and pore fluid type. The acoustic properties of shales are of particular importance in the exploration setting as shales constitute more than 80% of sediments and rocks in siliclastic environments. Seismic and sonic log data may be used for estimating overpressure in shales in order to maintain borehole stability during drilling. In addition, velocities in shales can be used for predicting its mechanical properties and hence, borehole collapse. Despite of the apparent importance of understanding shale acoustics, sonic logs in shales are frequently unavailable or unreliable especially for older wells. Hence, it is essential to compute pseudo-velocity logs from other available information. This can be accomplished by using empirical relationships or rock physics transforms. In this study we have compared the predictive power of resistivity (Faust 1951, Hubert 2008) and porosity based models (Wyllie 1956, Holt & Fjær 2003) for computing synthetic P-wave velocity logs using wireline log data from mudstone intervals at three North Sea wells. The wells 6507/2-1, 6507/2-2 and 6507/2-1 are located at the Haltenbanken area at the Norwegian Sea. The wells targeted hydrocarbon potential at the upper Cretaceous and lower Tertiary sandstone sequences. The sandstone beds are overlain by thick Tertiary and Cretaceous sequences of mudstones. Since our primary goal is to model acoustic velocities in shale, we used wireline data from the Nordland (NL), Rogaland (RL) and Hordaland (HL) groups that are mainly composed of mudstone. The mudstone beds were identified from the well log data by using natural gamma log, sonic and resistivity data as well as information from the Norwegian Petroleum Directorate website. The volume of shale was estimated from the natural gamma log and the data points with values higher than 0.65 were discarded. Similarly, the data points with shale volume less than 40 % were discarded. Furthermore, exceptionally high resistivity values amounting to more than 6 Ohm m were not included in the analysis. Porosities were determined from the density log assuming 2.7 and 1.05 g/cm3 for matrix and fluid densities, respectively. The depth that was used for calculating Vp from Faust (1953) was the depth below mudline in order to the compare of well data from wells that have been drilled at different depths (Hubert 2008).

May 1, 2009

By Tom Olsen, Tom Ohrling, Peter Taggart, Chris Martin

"North American Palladium commissioned the new concentrator at the Lac des Iles mine in the summer of 2001. The 15,000 tonnes per day mill replaced the existing 2,400 tonnes per day facility, as part of a major mine expansion.At Lac des Iles, the grain size distribution of the platinum group minerals (PGM) is bi-modal. Roughly two-thirds of the PGM are relatively coarse-grained, and often associated with fast floating copper and nickel sulphides. The remainder is ultra-fine, and locked in silicates, which poses a special challenge to the metallurgist. The previous mill typically recovered just the fast-floating mineralisation, but to achieve target recoveries, the new mill has to recover a substantial amount of the ultra-fine PGM. The metallurgical challenges associated with the recovery of fine-grained PGM in the talcous Lac des Iles ores, are described.The paper describes the approach used in circuit optimisation, and how metallurgical and operational optimisation raised palladium recoveries by more than 6% in six months, by tuning the circuit to recover some of the ultra-fine PGM mineralisation.BACKGROUNDThe Lac des Iles mine, owned and operated by North American Palladium Limited, is located about 115 kilometres north of Thunder Bay, Ontario. The mine originally opened in December 1993, and prior to 2001 included a mill capable of handling 2,400 tonnes per day of ore delivered from the nearby Roby pit.Following an intensive exploration programme conducted in 1999, and a detailed feasibility study, conducted in 2000, North American Palladium initiated a mine expansion project, the objective being to expand milling throughput from 2,400 tonnes per day to 15,000 tonnes per day. This required construction of an entirely new mill, which was commissioned in May 2001."

Jan 1, 2003

THIS bulletin presents all analytical and lest methods regularly used by Bureau of Mines laboratories for characterizing coal and coke. To provide better service to coal producers and consumers, the scope of this bulletin has been expanded to include important test methods used to evaluate coal properties for commercial processing. The methods described will prove valuable to all persons interested in analyzing and testing coal and coke.

Jan 1, 1967

By T. Watanabe, S. Hayashi, M. Hayashi, K. Nagata, H. Fukuyama

Chemical states of fluorine in CaO-SiO2-CaF2glasses in a composition range of CaO/SiO2=0.5?1.3 and 5?25 mol%CaF2have been investigated by 19F solid-state NMR with and without MAS. The isotropic chemical shifts of the glasses are close to those of cuspidine crystal (59.4 and64.3 ppm with respect to C6F6) and CaF2crystal (58.6 ppm). The fluoride ions are coordinated with four or less than four calcium ions in this composition range. The chemical shifts move to the lower frequency with an increase in the CaF2content, whereas those are not affected by theCaO/SiO2ratio. The ionic distance between calcium and fluoride ions increases with an increase in the CaF2content. The chemical state of fluorine is not disturbed by the degree of polymerization of the silicate network. Comparing the MAS and static NMR spectra, the second moment attributed to 19F-19F dipole-dipole interaction has been estimated. The values of the glasses range over 3.1?7.3107Hz2andthose are larger than the calculated value of cuspidine crystal. This indicates that fluoride ions form Ca-F clusters in the glasses and that the size of clusters increases with increasing the CaF2content. Keywords: chemical state of fluoride ion, CaO-SiO2-CaF2glass, solid state 19F NMR spectroscopy

Jan 1, 2004

Ensuring the success of a major resource development project, whether in the Gippsland Basin or elsewhere, is typically both a complex and costly process. It is therefore imperative from the point of view of the proponents of such a project - and in particular the financiers - that everything possible be done to minimise administrative confusion and delay in the establishment phase of the project, and to put systems in place which enable the project to run smoothly and efficiently in the later stages of its development and operation. An essential element in this process is ensuring that the project management is able to come to terms with and deal effectively with the relevant planning and environmental laws.

Jan 1, 1992

By R E. Myers, G N. Phillips

Many of the worldÆs larger iron ore deposits are hosted by rock sequences of Archaean to early Proterozoic age. Most models for the genesis of these deposits are influenced, either directly or indirectly, by the nature of the atmosphere at the time of their formation, and more specifically by the presence or absence of oxygen in the early atmosphere. Since the early-1950s, the geological literature suggests that the Archaean atmosphere was æreducingÆ, and that it may not have contained significant amounts of free oxygen until ca 2 Ga. There are many different definitions of the term æreducingÆ, but the criterion adopted here is whether crustal iron was limited to Fe2+, or whether Fe3+ was also widespread, ie was there scope for redox changes in the state of iron? Significantly, major Australian banded iron formations span this period of inferred atmosphere transition, eg Mt Goldsworthy, Mt Tom Price, Middleback Ranges. Geological evidence for a reducing Archaean atmosphere is both ambiguous and controversial (see review by Phillips, Law and Myers, 2001). Many earlier ideas (eg no Archaean redbeds; all very large iron ore deposits being post-Archaean) have been disproved by dating, whereas other evidence (eg homogeneous detrital gold grains, inferred palaeosols) has not withstood geological scrutiny. The interpretation of some data sets (eg inferred detrital uraninite and pyrite in some Archaean meta-sedimentary rocks) is still controversial. In fact, some lines of evidence now suggest that oxygen was present in the atmosphere well before 2.5 Ga (eg sulfates in the Pilbara craton, carbon distribution in clastic sedimentary rocks). An oxidising Archaean atmosphere has important implications for the development of iron formations. First, the atmosphere is an obvious potential source of oxygen to stabilise ferric iron minerals. Second, reduced fluids in equilibrium with ferrous iron are commonly inferred to transport iron in solution to the depositional site. The redox state of the atmosphere thus provides critical constraints on the solution chemistry of surface waters, effective transport paths for iron and particularly on viable precipitation mechanisms. Iron formations developed from fluids in equilibrium with the atmosphere also have the potential to provide important constraints on the evolution of EarthÆs early atmosphere. If an oxygenated atmosphere is a necessary condition for the development of iron formations, then the Archaean atmosphere must have been oxidising since at least 3.5 Ga. If the redox state of the atmosphere is not a necessary condition, then the time distribution of iron formations cannot be used to provide constraints on atmospheric evolution. Given these uncertainties, models for the genesis of iron ore deposits of Archaean or early Proterozoic age should not rely on a reducing atmosphere in the absence of independent evidence and the alternative of an oxidising atmosphere should also be considered.

Jan 1, 2002

By Chu E. Ho

Key variables that govern the jet cutting process are examined based on fundamental theories of jet hydrodynamics and soil mechanics. Under normal conditions of jet grouting operations, lift speed and rotation speed are found to be of less importance than the depth of jetting, nozzle pressure, nozzle diameter, and the soil bearing resistance, with regards to their influence on jet cutting distance. An analytical equation linking the governing variables is proposed, which allows for the possibility of evaluating column diameters achievable in different ground conditions based on theoretical calculations. When used in conjunction with shallow jet grouting field trials, the equation can provide a means for extrapolating trial results to conditions at actual depths for production jet grouting.

Jan 1, 2006

By Russell Carter, Tom Barkley

"Optimization of blasting is hampered by the lack of inexpensive methods of measuringblast results. Optical methods of size analysis have the potential of creating abreakthrough in size analysis and in overall blast optimization. Attainment of reliablemeasurements hinge on solving a number of shortcomings inherent to optical systems."

Jan 1, 1999