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By William Petruk, J. R. Schnarr

The behaviour of minerals during flotation of a fine-grained pyrite-rich base metal ore was investigated by studying the feeds. concentrate and tailings from every flotation cell in the mill of Brunswick Mining and Smelting Corp. Ltd. Bathurst. New Brunswick. The samples were analyzed for Zn, Pb, Cu. Fe, Ag. Sb, Sn, Bi, In. Hg, Mo and As. Mass balances were computed and recoveries of all metals from each cell. from each circuit and from the mill were calculated. The percentages of sphalerite. galena and chalcopyrite occurring as free grains in each product were determined with an image analyser, as were size analyses for free mineral grains and middling particles, and compared with screen analyses. The results show that the behaviour of minerals is defined much better by the recovery of free mineral grains than by the recovery of elements. The recovery of free sphalerite in the zinc circuit is 96 wt %, whereas Zn recovery from the same circuit is 88 wt %. the difference being due to unliberated sphalerite. The recovery of free sphalerite from the mill feed is 88 wt % and Zn 78 wt %. The recovery of free galenafrom the mill feed is 88 wt % and Pb 64 wt %. The recovery of free chalcopyrite is 75 wt % and Cu 45 wt %. Size analyses show that more sphalerite and chalcopyrite can be liberated by regrinding. but the galena is so fine grained that regrinding would not necessarily improve liberation. Silver occurs mainly in tetrahedrite and galena; the main loss in the tailings is due to large (+ 26 um) and small (-1 um} free and unliberated tetrahedrite grains.

Jan 1, 1981

By G. A. Barclay

"I - INTRODUCTIONSteel castings still comprise the largest volume of wear materials used in crushing and grinding in the Canadian mining industry. The range of impact and wear properties possible with steel castings enables them to be used successfully in both high impact crushing as well as milling where abrasion resistance is the main criterion. Approximately 15,000 tons per year of steel mill liners and crusher castings are used by Canadian mines.The properties of the main steel casting alloys used - manganese, pearlitic chrome-moly and martensitic medium carbon steels will be discussed with reference to their applications. Field data on a new application in primary gyratory crushers for martensitic medium carbon steels is presented. Liner wear life and mill efficiency can be improved through proper liner design.The liner wear pattern can be used as an indication for liner profile changes to improve wear life. Changes in liner configuration can improve through put and use of larger castings can reduce downtime. Casting performance can be improved and foundry production costs reduced by adopting certain design improvements.II - ALLOYS USEDTable I list the most common ferrous liner materials used in relation to their hardness and wear resistance (1). The most wear resistant materials are the irons at the top. In many applications the service impact exceeds the impact strength of the irons and tougher less wear resistant steels must be used. The impact resistance improves from top to bottom with manganese steel the toughest. The hardness of the martensitic steels approaches that of the Ni-Hards however the wear life, because of the absence of carbides, is less."

Jan 1, 1983

By E. W. Vekris

Patents are playing an increasingly important role in the business world. A diverse patent portfolio can enable a company to secure a monopoly within the market, which can provide a competitive advantage over competitors. At the same time, possessing a diverse patent portfolio greatly increases the value of a company's intangible assets. This paper provides an overview of the patenting process as it pertains to the fields of metallurgy and mining, and summarizes some general patenting strategies. A review of new "green technology" initiatives recently adopted by Patent Offices around the world is also provided.

Jan 1, 2011

By Brad Sampson

Project Ownership ?Discovery Metals Limited ?ASX (DML), BSX (DML), AIM (DME) ?Market Cap AUD 195M ?Key assets ?Boseto Cu ?Dikoloti Ni The Boseto Copper Project ?Location ?Setting ?History ?Status ?Future

May 1, 2010

By M. Fall

The progressive depletion of ore available at shallow depths in several underground mines around the world means that underground mining operations would increasingly be carried out at greater depths and therefore at higher temperatures. However, our understanding of the effect of hot temperatures on the response (mechanical, economical, environmental) of cemented paste backfill (CPB) is still limited. Hence, an extensive laboratory investigation was conducted to study the performance of young and aged CPB, in response to deep mine temperatures. Several CPB samples with different compositions, cured at different temperatures (20 to 50°C) and different times (7 to 160 days) were tested regarding their mechanical properties, economical performance (binder consumption) and microstructural properties. The results show that hot temperatures significantly affect the performance properties of CPB at young and advanced ages. An increase in the curing temperature leads to a considerable improvement of the rate of gain of CPB strength and also to a significant increase of the strength of CPBs studied. CBP samples cured at hot temperatures show lower binder consumption and finer pore structure. Results of this study could serve as background information for the development of optimal mine backfill design procedures.

May 1, 2007

By G. Rong, W. Du

Stability of some potential unstable blocks in the left bank slope of Baihetan hydropower station is evaluated in this paper using the three-dimensional (3D) limit equilibrium method. The Baihetan hydropower station is in the downstream of Jinshajiang River, China. The geological condition in the river valley is complex, and many large discontinuities are detected in the slope of the two banks. As a result, much attention should be paid to the stability of the slope in the feasibility study stage. Because the left bank slope is an oblique consequent one, we mainly focus on the slope stability analysis in the left bank. Comprehensive geological exploration is conducted in the studied area and the detected discontinuities are well researched. By building a 3D geological model of the left bank slope, three potential unstable blocks which are close to the dam site are detected. An irregular wedge analysis method is then used to calculate safety factors of the three blocks under three conditions, which are natural condition, rainfall condition, and seismic condition, respectively. It is found that the safety factors of the block 1# and the block 2# are quite low when compared to the suggested values. Extra care must be exercised when excavating the slope near the block 1# and the block 2#. A preliminary reinforcement is also suggested.

Jan 1, 2015

By A. P. Yovanovic, P. Bonadia, M. N. Moraes, C. F. Matos

"The magnesite flotation operation of Magnesita Refractories, in Brumado – Brazil, has four parallel ball mills working in closed circuit with hydrocyclones to grind the ore for the reverse flotation of silicates in mechanical cells. The modification proposed here opens the circuit for three of the ball mills so that their products are collected together to feed a high frequency screen. The oversize of the screen feeds the fourth ball mill in closed circuit for secondary comminution. The product reports to dewatering and flotation. The undersize undergoes desliming and subsequent flotation operation. According to pilot tests performed, the modification on the magnesite flotation operation will promote a 20% increase in the productivity, 8.5% increase in mass recovery and a 26% reduction in water consumption. The gains are due to the fact that the silicates in the feed are concentrated in the smaller particles (<100µm) with over grinding in the existing closed comminution circuit, making it impossible to take advantage of this natural selectivity. The combination of open circuit, more selective milling, and the high frequency screen, ensures high efficiency particle size classification. This renders the process more effective, both to the screen undersize with its high contents of silicates and fines, and to the screen oversize, which is almost without fines and has a higher magnesite grade. This situation allows for the setting of specific parameters for the flotation of both the primary milling undersize and the secondary milling product.INTRODUCTIONMagnesita Refractories, with its operations site in Brumado, is the largest producer of high purity dead burned magnesia (DBM) in Latin America. The magnesite ore is extracted from an open pit mine, named Pomba, after which it is crushed and handpicked. Due to the presence of disseminated silicate the ore has to be ground and concentrated by means of reverse flotation, before feeding the high temperature kilns for sintering and conversion to DBM.The magnesite flotation unit has an impact crusher to reduce the size of the feeding ore, which is transported to the mills by conveyor belts. The milling operation is composed of four ball mills in closed circuit with hydrocyclones. The closed circuit generates a high circulating load with excess fines, which is detrimental to the selectivity of the desliming and flotation operations, reducing both mass andmetallurgical recovery.In the current scenario, the capacity of the flotation plant is insufficient to meet the demand of the DBM kilns, forcing the operation to work with high purity ores in order to attain the highest possible mass recovery in the concentration process. This is not an ideal situation as it requires the mining site to work with higher stripping ratios.The objective of this work was to improve the magnesite flotation unity to increase its productivity. After a detailed analysis, the milling was identified as the limiting process, which made the authors to focus on this operation."

Jan 1, 2016

By D. M. Maijer, S. M. Mohseni, A. B. Phillion

The microstructure evolution kinetics of aluminum alloy B206 during artificial aging has been investigated using non-isothermal calorimetry. A combination of differential-scanning calorimetry (DSC) and tensile tests have been utilized to develop an Avrami model to predict the precipitation kinetics as a function of the thermal processing parameters. The Avrami coefficients, found based on a Kissinger analysis, compare well against those reported in the literature for aluminum-copper alloys. The rapid precipitation kinetics predicted by the Avrami model at temperatures higher than 200°C were assessed through a qualitative comparison against hardness measurement results. In contrast to the continuous hardening observed at 150°C, the material softens with continuing heat treatment at 250°C resulting in an overaged state. This can be attributed to the rapid precipitation kinetics at this temperature, leading to the termination of the precipitation-hardening effects at early stages of artificial aging.

Jan 1, 2015

By J. S. Laskowski

Anisotropic minerals are important constituents of many ores. This group includes both valuable minerals (e.g., molybdenite in Cu-Mo ores) as well as gangue minerals (e.g., talc in platinumbearing sulphide ores in South Africa, graphite in Cu-Ni sulphide ores in Canada, chrysotile in Ni sulphide ores in Australia, and clay minerals in all types of ores). Aqueous suspensions of anisotropic minerals exhibit different properties than suspensions of isotropic minerals. The presence of anisotropic minerals in flotation circuits affects the flotation process.

Jan 1, 2012

By Md. Rashedul Islam

Magnetic data was collected from the Yeoju historical sites using the fluxgate gradiometer through six sites & several grids. We measured the vertical gradient by the FM256 Fluxgate gradiometer. The readings were logged every half meter. The obtained data were processed and treated to introduce a high quality magnetic image. The gradiometer results defined various positive and negative magnetic anomalies, which revealed the existence of several archaeological features of different shapes and sizes. The study of the process magnetic images give us a concept that the subsurface features are caved shape stone chamber tombs, burial mounds, deep room structure, Yeoju mausoleum, pagoda?s square foundation stones, walls etc. All these are superior work of early Goguryeo inheriting orthodox Silla style. So, the study area may have great archeological interest.

May 1, 2009

By J. A. Maritz

"The Hedley and Grant formulation for pillar strength has been widely adopted by the South Africa hard rock mining industry. Today, some forty year later, this formula still provides the foundation for pillar strength calculations when designing for stability and utilising pillars in mine layouts. Various mine specific back analyses were conducted to adjust the equation parameters based on underground observations of failed pillars and comparing to the pillar stresses calculated using numerical models. In all these instances, the influence of shear stresses was ignored. The key to more representative pillar strength estimation is a better understanding of the pillar loading environment.In this paper, special mining cases are evaluated and the existence of shear stresses on the pillar loading environment is illustrated. By revisiting some back analysis data for optimisation of the equation parameters, recommendations were made in respect of the influence of the shear stress component and on how this should be considered in determining the pillar strength.INTRODUCTIONCommon practice on flat dipping, shallow and intermediate depth ore deposits in the South African hard rock and coal mining industry is to exploit the mineral resource using a room-and-pillar layout. The design methodology is mainly based on a Factor of Safety (FoS) approach, where the strength of the pillar is compared to the effective load on the pillar. In these environments, FoS values of 1.6 are applied as it was found to correspond to a probability of failure in coal mines of 0.001. As discussed by Ryder and Jager (2002) page 279: “For lack of anything else more substantial, the figure of 1.6 is generally used in hard rock pillar design in South Africa”. Dependant on the designed purpose of the pillar, the FoS might be selected as high as 2.0 where long term stability is required. The factors directly influencing the FoS include the pillar height (which is linked to the mining height), effective pillar width, a rock-strength factor and extraction ratio."

Jan 1, 2015

By Nabeel Khan

Annual oil production from the Canadian Oil Sands in Northern Alberta has been rising for several decades, and more ore and overburden are excavated each year from an increasing number of open pit mines. Overburden meeting certain specifications will be used to dam tailings and fill open pits, but the remaining material must be stored in overburden storage structures (OBSS). Well-designed overburden storage structures are more stable and cost less in the short- and long-term. The purpose of this paper is to explore OBSS designs that will be stable yet economical in the short- and long-term. The geological background of the site is briefly discussed, including the effect of each of the main geologic layers (recently deposited till and muskeg, Clearwater Formation clay shales, McMurray Formation oil sands, and the Devonian limestone) on the slope stability of the OBSS. Cost is considered in the analysis when balancing between minimizing costs (steeper slopes) and acceptable factors of safety (flatter slopes), all the while considering the financial consequences of failure. Potential failure planes are identified and probabilistic analysis is conducted on the critical failure surface. The variations in the factor of safety caused by varying pore water pressure, friction angle, and cohesion, are plotted and discussed.

Jun 1, 2012

By T. Alan O'Hara

"Annual mining revenue can be computed by formulae relating metal prices, smelting schedules, concentrate grade and recovery to known ore grade and an assessment of core samples. Operating costs at different daily tonnages are related to orebody shape, mining method, milling process and general plant services. Capital costs are related to sizing of mining equipment, mine development, plant-site topography, climate and accessibility, plant services and personnel housing. IntroductionA crude guide to the average 1978 cost of mine projects is shown in Figure 1, but the costs of many mine projects have differed widely from the graphed average costs of $800,000 T0.6 for underground mine/mill projects and $400,000 T 0.6 for low-grade open-pit mine/mill projects.High mine project costs and high operating costs are characteristic of open-pit mines with high stripping ratios, underground mines with thin orebodies, mills with complex metallurgy, and projects located in isolated regions with severe climate, mountainous topography, and lacking access to existing roads, towns and electric power. When none of these adverse conditions prevailed, the mine project cost was typically much less than the graphed average cost. Virtually all the conditions likely to cause high capital and operating costs are known from knowledge of the local topography, climate or accessibility, or can be assessed by tests on core samples, as soon as the orebody has been outlined by drilling .A more accurate estimate of over-all project capital cost and operating cost can be made from a summation of items of cost after judging the effect of specific local conditions on each item of capital and operating cost. This paper offers guides in judging the effect of local conditions on the sizing and 1978 cost of specific items of capital cost and operating cost and operating cost of mine projects. When the specific items of capital cost and operating cost are totaled and measured against expected net revenue and taxes over the life of the mine using the net-present-value or discount-cash-flow methods, the result should show whether the mine project development is clearly feasible, doubtfully feasible or clearly uneconomic. If the development of the mine project is clearly feasible, or probably feasible, a detailed feasibility study by experienced consulting engineers should be commissioned before any financial commitments are made; but if project development appears to be uneconomic, the time and cost of a detailed feasibility study is not warranted."

Jan 1, 1980

By R. D. Brown

In his April 10, 1978 budget address, Finance Minister Chretien declared that the federal government will restrict the growth of its spending to less than the trend growth of the gross national product; over the past year, both the federal and a number of provincial governments have taken action to cut back on spending policies. This new emphasis in restraint would seem 10 be a response to a mounting public reaction to the rapid growth of government spending - and taxation - over the past 25 years. Although this relatively new government posture on public spending may be admired by many, to others it raises the question: "Can the growth in government spending really be stopped?" This article comments on just how government revenues - and spending - have grown over the past few years in Canada, and mentions some of the issues relating to a slowdown in that growth.

Jan 1, 1978

By 000-900-009-492

The flotation has been and is still the most widely used mineral concentration method. Because of its complexity, the flotation process required the development of robust control strategies which was facilitated by the introduction of on-line sensing instruments such as x-ray fluorescence (XRF) on stream analyzer (OSA), gamma density gauges and electromagnetic flowmeters. The interest in developing control strategies has persisted because the benefits to be gained in terms of improved metallurgical performance are substantial. As the flotation control becomes more and more difficult due to the emergence of low grade and complex ore cases, other control strategies have to be introduced. Froth based control is one of the emerging useful control strategy This paper will focus on the state of the art in the on-line froth characterization as obtained by numerical image analysis. The technology of machine vision provides a novel solution to several of the problems encountered in conventional flotation systems for monitoring and control, and constitutes a powerful tool for the investigation and interpretation of the effect of various flotation parameters as driven for the froth phases. Copyright @2001CIM

May 1, 2001

By M. Hekmati1

SAG/AG mills have been most common choice in grinding circuits last decades. In the most cases, at the discharge of SAG/AG mills, a trommel screen is used that is equipped with baffles to provide appropriate residence time and improve separation efficiency. Using baffles, with the resultant maintenance requirements could lead to decrease in mill availability. In this research, an innovation in the structure of baffles of a trommel is presented. The results show that using new baffles led to 67% decrease in SAG mill downtime due to problems of baffles and 80% decrease in fine particles on recycle conveyor.

Jan 1, 2012

By Robin N. Adair

The Halfmile Lake stratiform volcanogenic massive-sulfide deposit consists of pyrrhotiterich breccia-matrix sulfides and pyrite-pyrrhotite-rich layered sulfides that form a laterally continuous sheet stratigraphically underlain by an extensive pyrrhotite-chalcopyrite-quartz stringer zone. Mineralization is hosted by a sequence of felsic pyroclastics and volcanic-derived, fine-grained metasediments. The proportion of volcanic to sedimentary rocks indicates increasing vent proximity from southwest to northeast across the deposit area. Fine- to medium-grained felsic pyroclastics and roughly equal amounts of fine-grained metasediments comprise the stratigraphic footwall to the mineralization. Quartz-feldspar porphyritic bodies cut this sequence and may have provided the heat source for exhalite activity. Felsic tuffs, locally crystal-rich, and lesser amounts of metasedimentary rocks make up the immediate stratigraphic hanging wall. This sequence is stratigraphically overlain and locally interfmgered with mafic volcanics that contain substantial proportions of felsic fragments. Deposition of sulfides post-dated the beginning of felsic volcanism, which places the deposit in the middle of the Lower Tetagouche Group. Compositions of the volcanic rocks range from basalt to rhyolite and exhibit sub-alkaline affinities. Strongly overprinted whole-rock, trace-element, and REE geochemical signatures resulting from mineralizing hydrothermal activity confirm the genetic relationship between the stringer zone and the mineralized sheet. Large-scale D1 folding has overturned the entire sequence. D1 thrust faults and related sheath-like folds have profoundly affected sulfide distribution. D2 is manifested by a penetrative S2 foliation, and D3 is represented by large-scale open folds.

Jan 1, 1992

By L. M. Pidgeon

Abstract The production of metallic calcium, by reduction of lime with aluminium, was investigated. Using a modified form of the effusion method, the vapour pressure of calcium above the reaction: 4CaO + 2Al ~ 3Ca + CaO.AI203 was determined and found to vary from 1.0 to 1.3 mm. Hg from 1,150° to l,200°C. From the magnitudes of the various thermodynamic quantities involved, together with a consideration of the known chemical characteristics of the reaction, it was suggested that the reaction proceeded by reduction of lime with aluminium vapour. INTRODUCTION The conventional production of metals by reduction of their ores by carbon (or carbon monoxide) may be represented by the equilibrium: MO+ R [] RO+ M . . . . . . . . . .(1) where MO represents the metal oxide, and R the reducing agent (carbon or carbon monoxide). The free energy change ?F° associated with the reaction is given by -?F° = RTlnKp . . . . . . . . ... . (2) where R is the gas constant, T the absolute temperature, and KP the equilibrium constant. It should be noted that ?F° represents ? the standard free energy gained by the system and hence -?F° is the free energy gained by the surroundings - and that as ?F° increases K must decrease, and conversely. For metals above manganese in the electromotive series, the ?F° associated with reaction would quantity and from it can be seen that this corresponds to a small fraction for K. The equilibrium pressure of the oxide of carbon represented by RO is then too near its concentration in the furnace gases for the reaction to proceed in an internally fired furnace. For the practical reduction of such metals, fuel fired furnaces are inadequate. Electric furnaces may be used to give higher temperatures with lower concentration of carbon oxides and the reaction may still proceed. However, for many metals such as calcium and aluminium the formation of stable carbides or acetylides may prevent production of the metal by this reaction. In this case, either electrolytic methods must be used, orrecourse must be had to reducing agents other than carbon. It is the latter method which is under consideration here.

Jan 1, 1948

By B. A. Zaharov, J. M. Shneerson, L. V. Chugaev, M. T. Zhunusov, A. M. Markelov, S. V. Drozdov

The main direction of research was the application of autoclave technology for the flotation concentrates or biooxidation feedstocks. The industry modernization also expects the possibility of increasing the yield of the flotation concentrate, to allow an increase in gold extraction in flotation circuit. This paper provides brief description of results obtained for concentrates with the yield of 4 and 8%, as well as corresponding biooxidation feedstocks. Technological efficiency of autoclave oxidation is shown for both concentrates and biooxidation feedstocks. The process has been evaluated on a laboratory and a continuous pilot plant scale. Gold extractions from POX discharge are ranging from 94-97% for each product, with only 5-7 kg/t cyanide consumed.

Jan 1, 2014

By C. J. Newman, K. Molnar, A. G. Storey, G. Macfarlane

"The Kidd Creek copper smelter started operation in June 1981 using the Mitsubishi Continuous Smelting Process. A steady increase in plant production rates has been demonstrated, and the annual tonnage of concentrate smelted is now double the original design rate. This paper summarizes recent modifications made to increase concentrate feed rates, increase on-line time, reduce copper losses and control the impurity level in anode copper. It includes improvements made to furnace design, improvements to reduce downtime f or boiler cleaning, and improvements made to the acid plant to allow handling of increased gas flowrates and higher gas strengths while maintaining low acid plant emission rates. IntroductionThe Kidd Creek Division of Fal conbridge Limited operates a base-metal mining and metallurgical complex, located in Timmins, Ontario, which includes an underground mine, a 13 500 tonne/day concentrator, a 130000 tonne/year zinc plant and a copper smelter and refinery, The copper smelter and refinery were commissioned in 1981, with an installed capacity of 59 000 tonnes/ year of cathode. The smelter, utilizing the continuous smelting technology of the Mitsubishi Process, has subsequently been expanded in production capacity, and in 1991 produced 113 500 tonnes of blister copper The capacity of the refinery, which uses Onahama No. 3 tankhouse technology, has been increased to 96 000 tonnes/year of cathode. The capacity increase at the smelter has been realized through the input of additional oxygen to both the smelting and converting furnaces, without increasing the process off-gas flowrate through the associated waste heat boilers.In this paper, a brief review of smelter operation and modifications in the period 1982 to 1987 is presented, together with a more detailed discussion of operation during 1988 to 1991, and a discussion of future planned improvements."

Jan 1, 1992