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By E. L. C. Martins, M. J. Nicol, D. Majuste, A. D. Souza

The effects of organic compounds on the current efficiency (CE), morphology, crystal structure and mechanical properties of the metal deposited during the electrowinning of zinc are described. A flotation collector and lubricating oil were selected based on observations made during the industrial production of zinc from silicate ores, in Brazil. The analysis by Fourier transform infrared spectroscopy of these compounds, which may be present in minor amounts in the electrolyte solution, indicated the presence of a polar amine group in the collector, while the lubricating oil is a non-polar compound. The average CE value obtained from organic-free industrial solution was 91.15 ± 0.26 %. The CE dropped to 54.35 ± 0.73 % in the presence of 100 mg·L-1 of collector in the solution, and a negative effect was also observed in the presence of similar amounts of oil (88.84 ± 0.61 %). The characterization of the deposits by scanning electron microscopy and X-ray diffraction revealed the formation of pores in deposits obtained from solutions containing the oil, while a different growth pattern (perpendicular zinc platelets) was identified when the flotation collector was added to the industrial solution. In the presence of these contaminants in the solution, guided-bend tests revealed that the deposits have a higher resistance to deformation, but lower ductility, properties that may affect the performance of the stripping stage. As a result of this work, simple control and optimization actions were applied in the industrial plant, which resulted in important improvements in the electrowinning process.

Jan 1, 2014

By A G. Rogers

This paper discusses the lubrication of surface and underground mining machinery and equipment from the standpoint of machine components. The machine components considered are bearings, cylinders, gears, chains, couplings, fluid drives, hydraulic systems, screws and wire ropes. The best selection of lubricants for these machine components, and for sub-divisions of the components, are outlined. They form general recommendations, for average operating conditions in both surface and under-ground mining operations. The American Petroleum Institute's service classification of both engine crankcase oils and gear oils is de-scribed and used in recommending products for these applications. The practical aspect of lubrication is kept foremost in the recommendations, which are designed to meet the requirements of a wide variety of equipment with the minimum number of lubricants. THE lubrication of mining machinery and equipment presents a variety of problems peculiar to the industry. The type of mine, the ambient temperature, water, dust, and operating and maintenance practices, as well as the age and condition of the equipment, are variables which have to be considered in making lubricant recommendations.

Jan 1, 1963

By A. R. Hekmat

Hypereutectic Al-Si alloys are used in applications that require high resistance to wear and corrosion, hardness and low coefficient of thermal expansion, To maximize the properties of these alloys, semi-solid processing can be utilized to modify the solidification structure of the primary silicon crystals as well as to reduce microsegregation and porosity, The transformation and spheroidization of primary Si crystals by shearing in the semi-solid state are not fully understood as they precipitate in the presence of other alloy phases, The objective of the present work is the determination the rheological characteristics of A390 (Al-17%Si-4,5%Cu-0.5%Mg) alloy using a Couette type (Haake RV12) viscometer and examining the microstructural evolution during continuous cooling and isothermal shear rate experiments, The effect of shear rate, solid fraction (temperature) and morphological evolution of the silicon crystals are investigated.

Jan 1, 2005

By J. S. Moretzsohn, D. F. Graham

"Airborne Synthetic Aperture Radar (SAR)was acquired over the Carajás Mineral Province, within the rainforests of the Amazon, which hosts the world’s largest Fe-ore deposit(Santos, 1986). Significant chemical weathering exists in this humid environment. PrevalentAu mineralization is thought to be generally associated with deformation zones in Archean schists.Radar data have proven to be very useful as an aid to geological mapping in the tropical rainforests of the Amazon Basin in Brazil. In these densely vegetated areas, a sense of regional structural trends is obtained as a con-sequence of the sensor/terrain geometry. The top forest canopy is the main terrain reflector of X-band radar energy, and consequently is the main terrain surface feature expressed in processed radar imagery. Radar is important for extending t,he continuity of mapped structural lineaments. Differential weathering is related to variations in radar image texture which is used to infer gross lithologic variations and relative age relationships of major rock units. Specifically, quartzites and banded iron formation are highlighted in the radar imagery due to their unique tonal and textural appearance, in contrast to schists, gneisses and metavolcanic rocks. As tropical areas are typically enveloped in cloud or mist, radar data are invaluable in providing information for logistical planning of field mapping activities."

Jan 1, 1997

By D. V. Dorling, J. T. Bowker, J. A. Gianetto

Over the last few years, interest in the development and construction of large diameter, high pressure pipelines from the Mackenzie Delta in northern Canada and Alaska's North Slope has steadily increased as a result of the projected decline in recoverable natural gas from existing reserves in western Canada. The success of such enormous pipeline projects, which will require utilization of a strain-based design approach, is largely based on successful application of high strength line pipe steels, such as X80 and X100. To fully realize the economic benefits of high strength steels, welding processes and procedures must be developed to ensure that the requirements for high strength and good low temperature toughness are confidently obtainable in field girth welds used in the construction of such pipelines. This study aims to provide a better understanding of the factors that control weld metal strength and toughness for a series of mechanized X100 girth welds produced using a range of narrow-gap gas-metal arc welding procedures. The attainment of high yield strength (> 810 MPa) is considered to be an important target to ensure overmatching strength relative to the longitudinal property distribution of X100 line pipe steel. Some factors that have been considered in this evaluation include influences of gas-metal arc welding process variants (single and multi-wire) and changes in welding procedure specifications, including joint preparation. Key components of this work relate to the reliable measurement of weld metal strength variation through-thickness and as a function of position around the circumference of a given girth weld.

Jan 1, 2005

By E. J. Debicki

"At the 1992 PDAC Convention, Norman Keevil announced the formation of the Exploration Technology Division (ETD) of the Mining Industry Technology Council of Canada (MITEC). It was evident that base metal reserves in Canada were declining and that the cost of discovering a deposit in Canada was increasing. Coordinated research to develop new exploration technologies was required to discover the next generation of ore-bodies. The ETD was formed in response.The mission of the ETD is to contribute to the survival, profit, and growth of the Canadian mining industry by improving the efficiency and effectiveness of mineral exploration through development of innovative technology by man-aging and coordinating applied cooperative research. In addition, it is the intent of the ETD to become the principal agency by which cooperative research funds are transferred to researchers from the mining industry. The division is industry driven, industry funded and industry managed.The ETD’s Three-Year Plan has focussed80% of its research funds toward two objectives, improving the efficiency of exploration for VMS deposits and establishing the parameters necessary to discover the next Hemlo deposit. The remaining 20% is allocated to other projects, with the current emphasis on geophysics.In 1995, corporate members total twenty-three major mining companies accounting for90% of the exploration expenditures in Canada. The ETD is currently managing ten cooperative research projects totalling $4.6million. Other projects, estimated at $1.6 mil-lion, are currently under development."

Jan 1, 1996

By A. Hussain

PAPER NOT SUBMITTED FOR PUBLICATION

Jan 1, 1987

By V. G. Papangelakis, M. Cheung, M. Dry

The high pressure acid leaching of laterite was modelled and simulated using a combination of two commercially available software packages, namely Aspen Plus 11.1 and the OLI Stream Analyzer. New kinetic parameters for the acid-controlled metal dissolution and precipitation reactions at temperature were first determined from previous experimental data on the leaching of limonite. A grain model with cylindrical pellets was used to model the solid-liquid dissolution reactions. Precipitation reactions were modeled via aqueous equilibrium chemistry. A dedicated thermodynamic database previously developed at the University of Toronto was used in conjunction with the OLI software to model the solution chemistry and calculate the concentration of hydrogen ions in solution at the leaching temperature. Mass balances were handled by Aspen Plus. The simulation gave good predictions of nickel dissolution under industrial and laboratory conditions, for the dissolution of limonite and limonite/saprolite blends. Computational

Jan 1, 2005

Arguably the SMC Test® has become the most popular laboratory hardness test in the world with over 17,000 tests having been completed to date, covering over 650 different ore bodies. It is now routinely used in design, optimisation and orebody profiling projects. The test is unique in that from relatively small amounts of drill core it simultaneously provides parameters that are used in simulation modelling of AG/SAG and crushing circuits as well as work indices that are used in power-based equations for predicting the specific energies of AG/SAG/Crushing and HPGR circuits. The very large data base that has been accumulated has provided the opportunity to study the differences in variability from deposit to deposit. This paper describes and discusses the trends that have become apparent from the study of this data base. Recommendations for appropriate selection of sample numbers are also made which are based on these trends.

Jan 1, 2012

By R. Loney, M. Militzer

There is a significant demand for new high strength steels with fine grain sizes for structural applications. One approach in this regard is to develop hot-rolled HSLA steels where refining the microstructure leads to increased strength levels, e.g. 700 MPa yield strength, that can be attained by suitable modifications of chemistry and processing. Here, an HSLA steel is investigated that contains 0.05wt%C-1.65wt%Mn-0.20wt%Mo¬0.07wt%Nb-0.02wt%Ti and approaches the above strength class. The ability to control and predict the mechanical properties of hot rolled steel depends strongly on the thermomechanical processes, which the steel undergoes. The final microstructure and, thus, the properties of the hot-rolled steel are a function of the austenite decomposition obtained during accelerated cooling on the run-out table and precipitation during coiling. The austenite-to-ferrite phase transformation under run-out table conditions has been investigated using a Gleeble 3500 thermomechanical simulator equipped with a dilatometer. The effects of cooling rate and initial austenite microstructure including the degree of work hardening on austenite decomposition kinetics and ferrite grain refinement have been quantified. Results show that grain refinement can be optimized by the presence of work hardened austenite and accelerated cooling. Based on the experimental results, a model is proposed to predict the transformation start temperature and the resulting ferrite grain size for run-out table cooling conditions.

Jan 1, 2004

By G. Van Weert, O. Wang

"As part of a general review of processing double refractory ores through Barrick Gold’s autoclaves / CIL facility at Goldstrike, blanking the preg robbing native carbon in the process solids with hard (m.p. 55 - 60 º C) paraffin wax was studied, specifically in relation to pressure oxidation. The improvement in CIL gold extraction was found to depend on the wax addition point, with hot, dry contacting of the ore in the presence of wax - prior to POX - yielding the largest, most consistent improvement in gold extraction.INTRODUCTIONDouble refractory gold ores present two barriers to gold extraction. The first is generally a physical barrier: the gold is encapsulated or dispersed in a matrix which is impervious to the gold lixiviant. In most cases, including Carlin Trend, NV, deposits, this involves a pyrite or arsenopyrite matrix, although minor gold may also be dispersed in competent silica (quartz) or iron oxides. Gold can be rendered accessible by oxidative destruction of such sulphide matrices. At Goldstrike this is practised by roasting and autoclave oxidation (Thomas, 1994). It is the latter route to which this paper refers.The second barrier refers to the actual gold recovery. Gold may be extracted from the pressure oxidized solids with cyanide, forming a gold cyanide complex. One characteristic of this complex is that it adsorbs on graphitic surfaces. This is taken advantage of on a large scale by gold millers, who use manmade activated, i.e., graphitized carbon particles to remove the gold from solution during leaching: the Carbon-In-Leach, or CIL process. The gold cyanide bearing carbon particles are larger than the ore solids and can be separately recovered by screening. Goldstrike uses the CIL technology to recover gold. The second barrier becomes problematic when the ore naturally contains graphitic orcarbonaceous material, hereafter referred to as native carbon (versus the man-made activated carbon). This material may also adsorb gold cyanide in competition with the activated carbon. Since the native carbon is ground with the ore it is much smaller than the activated carbon. Any competition between the two carbons may produce a loss of gold from the pregnant leach liquor to the process tailings. This phenomenon is called “preg robbing”. Goldstrike ores come from the Carlin trend, which is known for the occurrence of native carbon (Adams & Burger, 1998; Schmitz, Duyvesteyn, Johnson, Enloe & McMullen, 2001; Tretbar, 2004)."

Jan 1, 2012

By Y. S. Sun, Northeastern University, W. B. Li, P. Gao, Z. Y. Zhang, J. W. Yu

"The boron-bearing iron concentrate was extracted from ludwigite ore by the process of magnetic-gravity separation. In order to fully utilize the refractory ore and meet the boron consumption of China, a novel process for separation of boron from iron in boron-bearing iron concentrate was proposed in this paper. In particular, laboratory scale experiments of improving boron reactivity were performed. Fine boron-bearing iron concentrate briquettes were reduced by bituminous coal completely at 1125 °C for 150 min. The effect of sodium carbonate, which was used as an additive in the roasting process, was investigated. The addition of sodium carbonate decreased the boron reactivity and facilitated the volatilization of boron. The influence of diverse cooling methods of the reduced samples on the boron reactivity was studied. The results indicated that boron reactivity could reach up to 80.76% when the reduced samples were cooled by rapid water quenching. In addition, the magnetic material containing 92.71 % Fe with a recovery of 95.11 % and boron-rich non-magnetic material containing 14.51% B2O3 with a recovery 88.85% could be obtained by low-intensity magnetic separation. The magnetic material and boron-rich non-magnetic material were good raw materials for steel-making and borax production, respectively.INTRODUCTION Ludwigite ore is abundant in Liaoning province of China, with 28.43 Mt B2O3 accounting for 57% of the boron resources of the country (Liu et al., 2006). However, it has not yet been utilized on an industrial scale due to its complex mineralogy and fine mineral dissemination (Wang, Wang, Ding, Ma & Xue, 2012). At present, boron-bearing iron concentrate and boron concentrate can be obtained from ludwigite ore using magnetic-gravity separation. The boron concentrate contains B2O3 12%~16%, which can be used as a high-quality raw material for the boron chemical industry after activated roasting, but the B2O3 content in the iron concentrate reaches up to 4%~6%. In order to further separate boron and iron from boron-bearing iron concentrate, a blast furnace and a solid pre-reduction followed by electric arc furnace melting have been proposed (Liu, Cui & Zhang, 1998; Wang et al., 2012). However, both of these two current routes face the same crucial problem that molten boron-rich slag has to be cooled slowly to obtain the alkali-dissolution activity of boron, which affects the yield of boron resource."

Jan 1, 2016

"These guidelines set out information on timely disclosure of news releases which are intended to provide, existing shareholders and potential investors, factual information on which a reasoned investment decision can be made.Consider the problems and concerns raised by the following hypothetical news releases:Natural Resource Company""The Company has recently optioned a large and exciting gold property near the ""XXX"" gold discovery area. In describing the property, the Company's independent consultant has said: ""The favourable location of, and some of the results of prior work done on the property give the Company a worthwhile mineral exploration opportunity .... "". The Company proposes to expeditiously conduct a sizeable exploration program on the property as soon as the appropriate financing has been arranged.""Non-Resource Company""Based on discussions with several European countries, the Company anticipates that it will have orders to ship over 200,000 crates of widgets to those European countries over the next two years. These orders, which considerably exceed the Company's forecasts for the first year, represent a projected profit to the Company in excess of $1,000,000 over the next five year period.""GuidelinesTimely disclosure news releases are intended to provide, to both existing shareholders and potential investors, factual information on which a reasoned investment decision can be made. National Instrument 43-101 Standards of Disclosure for Mineral Projects provides requirements for disclosure of a scientific or technical nature for a mineral resource company.The examples do not provide sufficient detail and are misleading because material information is omitted. The following guidelines should be observed when preparing a news release:"

Jan 1, 2003

By B. S. Ignasiak, B. N. Nandi, D. S. Montgomery

The growing need to measure the extent of weathering of coking coal in storage and in transit prompted the comparison of the dilatation of coking coal on heating, which is known to be a sensitive index of oxidation, with the composition and volume of the gases produced by a mild pyrolysis of the same coal. It was found that the pyrolysis method had the advantage in that it could be used to study coking coals in advanced stages of oxidation, when the swelling properties had been largely destroyed. Of the various constituents in the pyrolysis gas, the most sensitive indication of coal oxidation was the volume of carbon monoxide evolved per gram of coal. For the coals examined, this index appeared to be at its best when the temperature of pyrolysis was approximately 35oC.

Jan 1, 1970

By J. M. Hong, H. K. Zheng, R. Hu, C. B. Zhou

The Jinping-I double curvature arch dam, located in the middle reach of the Yalong River and with a maximum height of 305 m, is the world highest dam of the same type that has been completed. Since the second and third periods of the reservoir impounding, after which the reservoir water level was raised by about 200 m, a significant amount of leakage was observed out of the drainage holes deployed in the lowest drainage tunnel at the left-bank abutment at EL. 1595 m, with a pressure of 0.3 MPa at one typical hole when it was blocked. In this study, a number of analyses including water quality analysis, digital borehole imaging, tunnel geological mapping and in-situ groundwater monitoring were performed to investigate the source of leaking, the leakage passages and the performance of the grouting curtains. An inverse modeling procedure combining the orthogonal design, finite element forward modeling of the transient seepage flow, artificial neural network and genetic algorithm was invoked to further evaluate the permeability of the foundation rocks whose permeability was underestimated in design, using the in-situ measurements of flow rate and piezometric head. The geological structures that lead to the leakage were identified and the seepage flow behaviors in the dam foundation and the left bank abutment were assessed. Given the connectivity nature of the sub-vertically oriented fractures that induce the leakage event, it is found that some of the drainage holes with relative larger amount of discharge could be closed or blocked for reducing the amount of leakage without remarkably increasing the pore water pressure in the foundation rocks.

Jan 1, 2015

By Kaiwen Xia, Bibhu Mohanty, Per Svedensten, Sheng Huang

"The mechanics of crushing and grinding operations in mining and excavation processes has been investigated in a laboratory simulation study. It employs a multi-particle bedded rock target, which is subjected to multiple impacts. The impact set-up consists of a Hopkinson pressure bar and a Piston-holder system. The apparatus, employing a 38 mm diameter pressure bar, was used to apply varying but calibrated dynamic loading force on the rock particles. The energy consumed by the sample during fragmentation was determined by considering the energy carried by the incident wave and the reflected wave. The Pistonholder system is used to hold rock samples and to recycle fragments after each test for particle size analysis, for single as well as multiple impacts. The feed size selected was in the range of 9.5 to 12.7 mm for all rock samples, and the impact velocity was set at 14 m/s. Two strong granitic rocks and a relatively weak limestone were the target rocks. The resulting particle size distribution after each set of impacts, ranging from single to 10 consecutive impacts, were analyzed, and various size distribution functions (i.e. Rosin- Rammler, Swebrec, Grady and Gilvarry functions) were fitted to compare their suitability in predicting the fragment size distribution for each rock type. INTRODUCTIONCrushers are widely used in the mining industry all over the world. Understanding fragmentation behaviour of rock under crushing process is fundamental to improved productivity and efficiency in mining operations. This is particularly so as all subsequent size reduction processes such as crushing and grinding are far more energy intensive than the initial blasting process employed in breaking of in situ rock. A considerable body of experimental studies exists on the behaviour of rock crushers for specific rock types in order to aid in the design of various types of crushers. However, these studies are mainly site specific, that is, the results are largely empirical, and the fundamentals of fracture process that lead to size reduction have not been dealt with adequately. Most such studies have attempted to link the input parameters, such as feed size and crusher parameters, with output particle size, and global energy expended in the process. However the physical mechanism of crushing process is still not well understood. First of all, the energy consumed by the rock sample is hard to calculate during standard crushing or grinding tests; secondly, multi-particle test is hard to perform in the laboratory due to irregular shape of the subject rock sample. In This paper, describes a laboratory crushing apparatus for multi-particle rock samples, with sufficient control of the energy expended in the process, with a view to relate creation of new fracture surfaces in the size reduction process."

Jan 1, 2015

"This paper deals with the reconciliation of open stope performance at Olympic Dam, South Australia, with a focus on stope stability, recovery, and operational aspects of stope reconciliation in relation to the expected or planned stope design. The observed stope performance is inconsistent with the equivalent linear overbreak sloughing criteria for assessing the performance of large open stopes. The aim is to investigate new stope performance criteria using quantitative (overbreak, underbreak, maximum depth of wall failure) and qualitative (stope productivity, observed fragmentation) information that correlates with the observed stope behaviour, providing a process for improving future stope designs.RÉSUMÉ Le présent article traite de la réconciliation de la performance des chambres ouvertes à Olympic Dam, Australie du Sud, en ciblant la stabilité des chambres, la récupération et les aspects opérationnels de la réconciliation des chambres par rapport à la conception attendue ou planifiée des chambres. La performance observée des chambres ne concorde pas avec les critères d’épaisseur équivalente du bris hors profil pour évaluer la performance de grandes chambres ouvertes. L’objectif est d’étudier de nouveaux critères de performance des chambres au moyen de données quantitatives (rupture hors profil, rupture à l’intérieur du profil planifié, profondeur maximale d’effondrement du mur) et qualitatives (productivité de la chambre, fragmentation observée) qui concordent avec le comportement observé des chambres, fournissant ainsi un processus pour améliorer les futures conceptions des chambres."

Jan 1, 2015

By E. Dernedde

Cell rooms of aluminium smelters have large openings in the sidewalls and in the roof. These openings provide a high ventilation rate, which removes heat and contaminants emitted by the reduction cells and thereby ensures acceptable working conditions inside the cell room. However the large openings make the airflows through the smelter building sensitive to the wind. In this study equations for the airflow through the openings of a smelter building exposed to crosswinds were developed and verified against plant measurements. The equations were then used to estimate the airflows through a two-storeyed smelter building containing VS Soderberg cells. Wind protection by wind-covers over the sidewall openings and by upwind buildings made the airflows through the building less sensitive to the wind. Physical and mathematical modelling showed that working conditions inside the wind-protected cell room would be acceptable for crosswinds at speeds up to 16 km/h. These predictions were confirmed by measurements taken in a VS Soderberg smelter.

Jan 1, 2007

By L. A. Wrigglesworth, A. S. Dadson

The orebodies of the Giant Yellow-knife mine occur in zones of schist, in an assemblage of typical Precambrian greenstones which form part of the Yellowknife Greenstone Belt. One of the most interesting problems at the mine concerns the fold-like attitudes assumed by the schist zones. The internal structure of the zones and orebodies provides much evidence of folding. A logical conclusion would be that the zones represent a single horizon which has been folded and drag-folded in the ordinary course of mountain building. However, surface mapping, and correlation of certain marker horizons, in underground work, indicate a homo-clinal succession of steeply dipping flows. If this concept of the geology is correct, the zones must cross-cut the regional strike at a small angle and, in the over-all aspect, the regional dip at a large angle. A mechanical interpretation of the zone structure is presented as a suggestion for the present until new evidence is found.

Jan 1, 1959

By J. Bednar, R. R. Rogers, W. Dingley

"Zinc is by far the most important metal used for protecting steel from the ravages of corrosion, and cadmium is also used extensively for this purpose. These metals are applied by electrodeposition in cyanide baths when a particularly good appearance and high throwing power are required. One great disadvantage in using these baths has been the decrease in cyanide concentration and the increase in carbonate concentration that takes place during the plating. Another disadvantage has been the development of serious embrittlement in high-strength steels. The present authors have developed new cyanide baths for electroplating both zinc and cadmium on steel. These baths are stable in composition during plating, they have not produced appreciable embrittlement in the high-strength steels that have been investigated up to the present time, and they permit the use of considerably higher plating current densities. In addition, they produce extremely fine grained coatings that are attractive and have excellent adherence and covering properties. Brighteners can be used in the plating baths if bright finishes are required."

Jan 1, 1967