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By L. Jones, S. R. Lawrence, A. R. Holloway

Whilst dense medium separation is best known for its ability to concentrate diamond and coal deposits, the process is now being employed in southern Africa as a pre-concentration step to improve the economics of platinum group metal and nickel ores. DMS plants built for these industries (such as the 1600tph unit at Tati Nickel, Botswana), are spearheading an expansion in this area by reducing mine and process operating costs yet maintaining economic metal recoveries. This paper provides an overview of DMS technology and examines the economic benefits available to North American operators and projects, with recent case studies as reference.

Jan 1, 2009

By J. A. Folinsbee, Andre Robitaille, Tony Y. Chong

"Conventional crushing and grinding is followed by gravity concentration to recover free milling gold. Refractory gold, finely disseminated within the pyrite and arsenopyrite matrix, is recovered by flotation followed by pressure oxidation, cyanidation, and cementation. Non-refractory gold is recovered by cyanidation/CIP processing.A comprehensive test program aimed at improving flotation recovery was initiated in June 1995. Plant testing indicated that flotation tails value could be significantly reduced using mechanical flotation cells. Based on these test results, a flotation circuit that incorporates one of the three existing flotation columns followed by mechanical scavenging and cleaning was developed. Detailed engineering was completed in September 1996. Construction started in February 1997 and was completed in 3 months at a cost of $3.2 million. An on-stream X-ray analyzer was installed to provide real-time arsenic and iron analyses and inferred sulphur value on some of the flotation streams.The new flotation circuit proved to be an instant success. Flotation tails values were reduced by 27%. Final tails solids and solution was reduced from 0.035 to 0 023, and 0.0014 to 0.0006 oz/ton Au, respectively. Based on a mill throughput of 1,620 stpd this decrease in tails value will result in an increased gold production of 7,500 ounces per year. The payback for the project is estimated to be around one year.This paper describes the evolution of the project from bench scale testing to commissioning. Also, the operational and economic impacts on down stream processing are highlighted"

Jan 1, 1998

By A. A. Rafiei, J. A. Finch

A previous study comparing n-pentanol and the polyglycol Fl50 showed that the two reagents could give the same gas holdup but with different size bubbles. The finding implies that bubble rise velocity depends on the surfactant (frother) type. A study using bubble swarms supported the frother type effect but bubble interactions were a possible confounding factor. This study resolves the question by measuring the rise velocity of single bubbles of 0.8-2.5mm diameter over a distance :::: 300cm in n-pentanol and F 150. It is shown that at typical frother concentrations used in flotation that the rise velocity in n-pentanol remains comparable to that in water alone while in Fl50 the velocity is significantly reduced. The results confirm the suspected impact of frother type. It is illustrated that in n-pentanol the rise velocity does not reached terminal; while in Fl50 it does and this is the source of the velocity difference. Advances

Jan 1, 2009

By T. R. Kostecki, K. V. Jessu

"Roof bolts are subjected to axial stresses, shear stresses, or both. Axial and shear stresses were compared between roof bolts machined with two and three slots. Shear stresses perpendicular to and at an angle to the shear planes were evaluated by analyzing a three-slot instrumented roof bolt, performing laboratory tests on two- and three-slot roof bolts, and conducting in-situ test analyses. Threeslot bolts appear to provide a complete bending strain profile, requiring no prior knowledge of the estimated shear-plane orientation. Minimum displacements occur in roof bolts installed perpendicular to rather than at an angle to the shear planes.RÉSUMÉ Les boulons d’ancrage dans le toit d’une mine sont sujets à des contraintes axiales, des contraintes de cisaillement ou les deux. On a comparé les contraintes axiales et de cisaillement de boulons d’ancrage usinés avec deux ou trois fentes. Les contraintes de cisaillement perpendiculaires et à angle aux plans de cisaillement ont été évaluées en analysant un boulon d’ancrage de toit à trois fentes, en effectuant des essais en laboratoire sur des boulons d’ancrage de toit à deux et à trois fentes et en effectuant des analyses de tests in situ. Les boulons à trois fentes semblent fournir un profil complet de résistance aux contraintes de flexion, sans avoir besoin de connaître l’orientation estimée du plan de cisaillement. Des déplacements minimums ont lieu dans les boulons d’ancrage de toit installés perpendiculairement, plutôt qu’à un angle, aux plans de cisaillement."

Jan 1, 2016

By K. Becerra, D. G. Almond, T. D. Maru

"Nkomati Nickel Mine in South Africa processes one of the world’s hardest ores in a 375k TPM autogenous grinding circuit. The plant employs an unconventional processing circuit, comprising a primary autogenous mill (AG or FAG) and pebble crushing circuit followed by a secondary hybrid pebble/ball mill and classification cyclone cluster.Advanced Process Control (APC) or Expert Control is now generally accepted as an advantage in most modern high capacity concentrator grinding circuits. This paper reviews the installation of model predictive control at Nkomati and examines the results and benefits of installation in an autogenous mill during plant ramp-up. The paper also demonstrates how predefining process control objectives together with good plant and supplier cooperation can achieve a robust and reliable APC implementation on a very short site program.The results conclusively demonstrate operational and economic benefits during circuit operation with the advanced process control system ON. Production performance and circuit stability were significantly better than during manual control."

Jan 1, 2012

By B. L. Moreau

Certain gas wells tend to form hydrates in the production tubing. This paper outlines a method developed and used by the Author's company to overcome the problem. The injection of glycol to control hydrates results in sufficient dehydration to allow the gas to be trans-ported through a field-gathering system b a treatment plant. Sub-surface injection of glycol also offers a method of introducing corrosion inhibitors into the gas stream. The major operating difficulties have been overcome and the system is now in use in the northeastern part of British Columbia.

Jan 1, 1958

By Laura Kelsey

Contaminant Robust In Situ Water Extractor CRIWE Nafion-based water clean-up Extract purified water from natural extraterrestrial sources In situ water processing for downstream electrolysis Chemically resistant to process contaminants such as acid

May 1, 2013

By J. J. Crowder, A. L. Coulson

Ground support is a significant component of underground mining costs. The rehabilitation of failed support, however, is often much more expensive than the initial installation. This paper investigates whether the right type and length of support can be designed correctly the first time, through forward modelling of the support and the mining process. Back analyses demonstrate how high-quality instrumentation and monitoring can help with the estimation of the post-peak (post-failure) rock mass parameters required for a comprehensive analysis. A hybrid modelling approach combines a three-dimensional mine-wide boundary element model with a non-linear finite element model to allow for the failure process in the rock mass. The back analyses demonstrate that, for the case study site, the post-peak Generalized Hoek-Brown value of mr must be reduced significantly in order to properly simulate displacements observed in instrumentation data. High-quality instrumentation data is the key to post-peak rock mass parameter calibration. The procedures outlined in the paper highlight the need for a new hybrid numerical modelling package that can use the influence of three-dimensional mining-induced stresses to predict displacements in, and potential failure of, rock masses surrounding mining infrastructure in order to radically alter strategic and tactical mine design.

Jan 1, 2007

By S. Ng, Peter Stapleton, Paul Mankowski, J. Spence, R. Siy

"Syncrude has developed a low energy extraction process for the recovery of bitumen from oil sand. This new process operates at a temperature of 25 °C, resulting in substantially lower energy costs and lower capital costs, especially for the thermal energy generation equipment. The process will be used in Syncrude’s Aurora Mine, which is scheduled for startup in mid 2000. The flowsheet for Low Energy Extraction includes hydraulic transport of oil sand slurry, and bitumen separation using collector and frother chemicals and air as process aids. A number of flow sheet innovations and optimizations have been included, resulting in the next generation of extraction technology. Experimental pilot plant results, engineering progress to date and areas of ongoing work will be discussed. SUMMARYThe Low Energy Extraction Process has been successfully developed for commercial implementation at Aurora. The 1996 100 tonne hour Field Pilot demonstrated that the bitumen recovery target could be met with an 11.1% grade oil sand. However, pilot plant bitumen recoveries for a lower grade oil sand were not acceptable. The subsequent flowsheet optimization study led to a new flowsheet for Low Energy Extraction, which includes a primary separation vessel, a flotation circuit for PSV middlings, and the use of middlings displacement in the PSV cone bottom with flotation underflow. A test program conducted in 1997 showed that the new flowsheet could significantly improve the bitumen recoveries for lower grade oil sands. Engineering work on process scale-up led to selection of a 30 meter diameter PSV, with a tangential feedwell. The successful development and commercialization of Low Energy Extraction for the Aurora Mine Project is a major enabling step in the Syncrude 21 program. The low energy requirements of this process allow Syncrude to develop the Aurora leases more cost effectively. The use of this process results in major capital cost savings, predominantly in the thermal energy infrastructure and also provides long term operating cost advantages for Syncrude."

Jan 1, 1999

By D H. Sharp

The Quebec Cartier Mining Company produces iron concentrate for twelve months of the year from Port Cartier. This J>Ort is designed to handle ship varying in size from 3,000 to 100,000 d.w.t., requiring 50 feet of water at low tide. The harbour was built on shore for reasons of economy and layout, after considering many more conventional offshore designs. It provides for heavy oil bunkering, tanker off-loading, a heavy lift derrick and freight handling, besides ship loading and mooring. The weather for the previous fifty years was studied to enable wind and wave conditions to be accurately assessed for design purposes, and to determine probable lost time due to adverse weather conditions through-out the year. The first ship to be loaded was 60,000 d.w.t.; the second, 20,000 d.w.t. The latter entered the harbour after dark, under its own power, following a tug through the partly dredged narrow entrance. Large ships use tug assistance. Ships may leave the loading berth with the other berths occupied.

Jan 1, 1963

By P. J. Le Roux

"Mining worldwide and definitely in South Africa, is constantly under pressure to reduce its cost structure so as to sustain profitability. In underground gold mines where an open stope mining method is employed, dilution often has a significant effect on the viability of sustaining profits. Target Mine practices Open Stope mining Method and it was found that in some open stopes dilution was in excess of 10%, which has a significant impact on the sustainability of the mine.Dilution in excess of 10% can result in the reduction of the recovered grade from 5,5 to 4,5 grams per ton (g/t). The reduction of 1 g/t in recovered grade results in a potential loss of about ZAR21 Million per month bases on a gold price of ZAR240 000 per kilogram. Based on Life of Mine projections the potential loss of income could be as much as ZAR3,3 Billion. A reduction in dilution would have the opposite effect. There are a number of factors which affect dilution of which falls of ground in open stopes is a major contributor. The falls of ground can be attributed to a number of factors such as beam failure as a result of a larger than normal expected roof area (hydraulic radius too large), poor ground conditions, and poor blasting. The cost of damage to or loss of trackless equipment as a direct result of the falls of ground in open stopes, is very significant. The review of financial figures has indicated that this could be as high as ZAR491 million. This combined with the added cost of transport, hoisting, secondary blasting, milling and plant treatment costs of ZAR293 results in an estimated opportunity loss of ZAR784 million.Currently there is a significant amount of data available in the mining industry which could be effectively used to develop suitable back analysis techniques but to date this has not been used effectively. If dilution can have such an impact on current and future mining ventures then the optimization of back analyses for the prediction of dilution in open stoping could assist significantly in the reduction of dilution in massive open stopes. Rockmass classifications, geotechnical information, blast techniques, blast design, the stress strain environment and hydraulic radius all have an effect on, or play a role in the evaluation of dilution. Each of these factors will be taken into consideration to ultimately determine a measurable or calculated percentage of dilution in massive open stopes.The amount of overbreak in an open stope can be determined by subtracting the planned stope volume in m3 from the actual measured final stope volume in m3, which is obtained from the CMS (cavity monitoring system). This is in turn divided by the planned stope volume in m3 to determine the percentage overbreak. The CMS wireframe is imported into the geological model and its grade re-evaluated. From this the actual percentage dilution for this open stope can be determined. The dilution obtained can result in a major reduction of recovered grade for the open stope, but can also increase the recovered grade. The latter is normally the exception rather than the rule.When analysing data from Target mine the following was achieved:• Using 11 years of data a method of measuring and predicting the percentage dilution in open stoping was developed. This took into account rock mass quality, stress-strain state, and the hangingwall hydraulic radius (size of stope hangingwall exposed).• Implementation of this prediction method resulted in a reduction in falls of ground in open stopes. The benefit of this was a reduction in the damage to mechanised equipment resulting from less falls of ground which had a positive effect on the profit margins of the mine. As a direct result the recovered grade from the open stopes increased due to the reduction in the amount of dilution.• A design criterion, Dilution Stress-Strain Index (DSSI), was developed which allows the user to calculate, with certainty, the stability of the open stope and determine if m"

Jan 1, 2015

By A. H. Onur

Spontaneous combustion of coal is a significant hazard in underground coal mines. It causes serious problems for miners for many years after the fact. It threatens workers? lives and causes economic losses for companies. It disrupts coal production and makes it necessary to abandon the main drift where the spontaneous combustion occurred. Coal fires have to be prevented before they occur; otherwise they are very hard to control. Precautions thus have to be taken in potentially risky areas. For coal to spontaneously combust, it needs 3 elements: fuel, oxygen and heat. If one of them is missing, the fire cannot occur. The best way to prevent spontaneous combustion is to prevent contact between coal and air. Coating of the coal surface with an air-proof lining material would be a practical and useful solution to prevent spontaneous combustion of coal. In the scope of this study, a lining material for coating the coal surface was designed at laboratory conditions. Lining material to be used for preventing coal fires should be airproof, cheap, sufficiently strong, have low rebound, be water- and heat-resistant, and easily obtained and applied. It should also be safe for human health when in contact with mine ventilation. By considering these obligations, 3 kinds of gypsum (plaster, satin plaster, molding plaster), as well as lime, cement and fly ash and different mixtures of these materials were applied in laboratory conditions to form a lining material. Samples of lining material were subjected to uniaxial compressive strength tests to determine their behavior against roof loads. Although there is no need to carry any roof load, the lining material has to be sufficiently strong to stay in place on the applied surface. If the lining material is broken, coal and oxygen can react again. Air permeability and curing time of the mixtures were also tested in laboratory conditions. Then the tested mixtures were applied on a wall with a pump to test the applicability of mixtures. After all tests were performed in laboratory, the most suitable mixture was determined as the optimal lining material to prevent coal fires.

Aug 1, 2013

By Maurice Morton

THE use of organic and inorganic stains has found wide application as a means of detection and estimation of organic fibres. Such stains have enabled the analyst to distinguish between organic fibres of different type and even between wood fibres produced by different processes. Among these stains, aqueous iodine solutions have figured prominently, as in the case of the well-known Sutermeister and Herzberg stains. At the Johns-Manville laboratories, the idea of applying a stain to asbestos fibres was first considered solely as a visual aid in the microscopic examination of such fibres. The staining medium used in this work consisted of a 1 per cent solution of iodine in C.P. glycerine, the latter being used extensively here as a dispersing and mounting liquid for asbestos fibre. This iodine solution was found to have distinct staining properties when used on the local chrysotile fibres, and to improve greatly their visibility under the microscope. It was soon revealed, however, that this staining is apparently limited to the chrysotile variety of asbestos, as against other varieties. It can be readily seen that, if such were the case, the staining test would become a very useful tool in differentiating between chrysotile fibre and the other mineral fibres, without recourse to a lengthy chemical analysis. Hence this investigation was launched, with the purpose of obtaining more information as to the selectivity of this stain as well as its mechanism. The only previous work of this nature that could be found in the literature was that of Van Winsen and Graham (1, 2, 3) on the adsorption of erioviolet dye by serpentine and related magnesia minerals. However, these authors did not refer to any specific behaviour of chrysotile as against other types of asbestos fibre.

Jan 1, 1941

By D. Verhulst

The Altair process digests ilmenite concentrate in high-chloride HC1 solution, with complete dissolution of titanium and iron. The Fe(III) ions are reduced to the ferrous form, and the solution is cooled to produce crystalline ferrous chloride. Titanium is transferred by solvent extraction into a purified, concentrated Ti stream, which is spray-hydrolyzed to produce TiO2 hydrate. The hydrate is further calcined with additives to generate a high-quality pigment. All the chloride streams are recycled. In the original flowsheet, the iron chloride is pyrohydrolyzed by spray roasting to regenerate 18% HCl, which is subsequently converted to HC1 gas and water by pressure-swing distillation. A modified flowsheet includes an alternative to iron chloride spray roasting, producing more concentrated HCl and decreasing the amount of solution to be distilled. Improvements in digestion, solvent extraction and final pigment production are also introduced. A 100 t/y pilot plant is being built and will test the new concepts and confirm the overall water, acid and impurity balances of the process.

Jan 1, 2006

By P. S. Arthur, G. R. F. Alvear

Development of a new smelting process is risky. Many novel processes in the metals industry failed to fulfil the initial expectations of their inventors. Large sums of capital have been invested in technologies that either didn't provide a satisfactory return on investment, or didn't perform at all, and had to be replaced. One of the keys to success in process development is incremental scale up of the technology, with potential problems being identified and rectified as early as possible. In this way the cost of any rectification that is required can be minimized. The ISASMELTTM process was developed to maturity by Mount Isa Mines through the 1980's and 1990's using incremental scale up. Commercialization only occurred once the process had been proven on laboratory, pilot and demonstration scale over many years. As a result ISASMELTTM technology now operates successfully at numerous plants around the world. The methodical approach to development of the technology has allowed owners to modernise their existing operations or create new businesses with significantly reduced technical risk.

Jan 1, 2011

By Robin Sheremeta

What is the goal of every organization when it comes to safety? Everyone Going Home Safe and Happy Every Day Good old days: Era of Death (accidents will happen) Era of Engineering: (Eg. hand rails, limitswitches, machine guards, etc.) Era of Legislation: procedures, laws and regulations (Eg. SWP?s, Mines Act) Era of Behaviour-Based Safety: (eg. STOP program)

May 1, 2010

By R. Edinger

Aerospace and space products depend, probably more than any other products in industry, on advanced materials. While there are many ways of producing aerospace parts, in many cases the process does not allow the design of the metallurgical properties according to the part or product requirements in accordance with its mechanical configuration. Key to the next level of innovative manufacturing is the capability to control the amount of energy applied to the process, as well as the addition of materials in form of vapor or solid particles such as powder in order to build up the metallurgical composition required. With the development of a high speed pulsed laser-electron beam source, the LASTRON(TM) technology, we deliver the basic requirement for a digital manufacturing process of aerospace and space products. This technology, combining Laser and electron beam, finds application in welding, drilling-machining, and is currently modified to allow digital coating (PEB-PVD) methods. In addition to the coating, a powder metallurgical process, called Rapid Manufacturing (RM), will allow the precision melting of parts based on CAD/CAM files. The RM process and the digital coating will allow the production of graded aerospace alloys in parts for jet engines and aero-structures.

Jan 1, 2006

By T. R. Carter, A. C. Colvine

"Rocks of the Grenville Province in southeastern Ontario are currently largely dismissed by many geologists as having little or no potential for discovery of significant deposits of metallic minerals. The present study demonstrates that the area contains numerous deposit types which elsewhere are major metal producers. Therefore, there is significant unrealized potential, especially for gold, zinc, uranium, and possibly copper.The variety of deposits of metallic mineralization include stratiform zinc in marbles; stratabound base metal sulphides in volcanic and sedimentary hosts; gold-quartz veins; quartzmagnetite iron formation; copper-nickel and iron-titanium in intrusive rocks; magnetite skarns; molybdenum in skarns and pegmatites; uranium and thorium in pegmatites, veins, and calc-silicate gneisses; hematite veins; dolomite marbles (magnesium); and barite-jluorite-celestite-galena-calcite veins. There has been significant production of iron, lead, zinc, magnesium, gold, silver, and uranium.The vast majority of the metallic mineral deposits are confined to late Precambrian supracrustal and related intrusive rocks of the Grenville Supergroup. Many of the deposits are stratiform and/or stratabound and occur within units toward the top of major volcanic successions and in the lower portions of younger carbonate-clastic sedimentary successions.Processes responsible for mineral concentration in the area include: (I) syngenetic hydrothermal activity related to both volcanism and sedimentation; (2) epigenetic processes related to diagenesis, regional metamorphism, and igneous intrusive activity; (3) magmatic processes related to igneous intrusions; and (4) supergene concentration and enrichment. The genetic classification of the mineral deposits presented is based on observed geological relationships and these interpreted geneses. The deposit types have counterparts in volcanogenic and sedimentary exhalative, Mississippi Valley type, magmatic, contact metasomatic, and lode gold deposits. Many of the exploration criteria for deposits of these types may be applicable in the Grenville Province, despite the generally high metamorphic grades and complex deformation."

Jan 1, 1985

By E. J. Schwarz, A. A. Winir

"Absolute magnetite contents were determined for asbestos specimens in various stages of milling by using a Faraday-type thermomagnetic balance. Comparison of these results with magnetic ratings (MR) supplied by the mining companies cooperating in this study reveals strong scatter. The main cause of this scatter is thought to be that the MR values were obtained in magnetic fields well below the saturating field of magnetite (5,000 oe). However, only the saturation moment is an intrinsic property and consequently must be used for the purpose of obtaining reliable estimates of the magnetite content. Curie points indicate that virtually pure magnetite and possibly Ni3Fe is present in all samples, and another phase, probably (Cr, Al) magnetite, is present in a few samples. The susceptibility in fields stronger than 5,000 oe is positive and falls in the normal paramagnetic range, whereas sy nthetic chrysotile exhibits weak diamagnetism. This suggests that, as a general rule, the least adulterated natural chrysotile concurs with the samples showing the smallest positive susceptibility above 5,000 oe. The magnetite appears to increase in quantity with a decrease in fibre length and to be somewhat more uniform in distribution for samples showing substantial fiberization (opening of the fibres)."

Jan 1, 1971

By H. Tsuruta, A. Fujibayashi, I. Sumi, A. Murao, R. Murai

Injection of biomass into blast furnace as alternative reducing agent is so effective for the purpose of mitigation of carbon dioxide emissions from steel industries, because biomass is considered to be carbon neutral raw materials. Certain amount of Palm Kernel Shell (PKS) is abandoned after Palm oil extraction process. To use as a reducing agent of blast furnace, PKS was carbonized and classified by 100 mesh sieve. To examine the gasification behavior of PKS carbide under the blast furnace conditions, several combustion experiments were conducted using hot model experimental furnace. The experimental results showed that the gasification efficiency of PKS carbide increased as the quantity of volatile matter increased. This tendency is the almost the same for the pulverized coal, so carbide of PKS can be used at blast furnace at appropriate amount of volatile matter that can be controlled by carbonization condition. In addition, the pressure drop of the furnace tends to decrease because the amount of ash in PKS carbide may be smaller than that of pulverized coal. PKS carbide is a suitable reducing agent in that respect.

Jan 1, 2015