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By Franc R. Joubin, Donald H. James

"The Algoma (or Blind River) uranium district is centred in an area of some 600 square miles on the north shore of Lake Huron, about half way between Sudbury and Sault Ste. Marie, Ontario (Figure 1). Its favourable location, adjoining the main provincial highway and Canadian Pacific Railway line which follow the lake shore, has contributed greatly to its rapid development.By Canadian standards, the district has long attracted geological attention, beginning with the discovery of the Bruce mine in 1846. It has been repeatedly prospected at intervals since then, chiefly for copper and nickel but also for lead, zinc, cobalt, silver, iron, and gold. Numerous discoveries have prompted the suggestion by Yates (13) and others that one metal-logenic province embraces the entire mineralized area from Michigan through Sudbury and Cobalt.Geological mapping was initiated by Murray in 1847, and the area attracted much interest as the type locality of the Huronian, the correlation and stratigraphic position of which are still not entirely agreed on. Subsequent contributors to the geological literature of the area have been very numerous, and the bibliography at the end of this paper includes only some of the more modern reports.The history of uranium in this part of Ontario also dates from 1847, when J. L. LeConte identified as uranium-bearing a pitchblende-like mineral which he named ""coracite"". The specimens came from Theano Point, north of Sault Ste. Marie. In 1948 a search for the source of these specimens led to the discovery of the Camray uranium field. Occurrences in this field consist of numerous small and locally rich pitchblende-bearing fractures, within or along the contacts of diabase dykes cutting Archaean granite and gneiss.None of the showings explored proved large enough to justify production, but they stimulated prospecting of adjoining areas and thus led to the Algoma discoveries.The first find of radioactive conglomerate in place was made in 1949 in Long township, and it was partially staked as the Fisher-Audette-Breton property. Rusty, overgrown rock-cuts indicated that the pyrite-bearing conglomerate had been investigated years before, probably during searches for base metals and gold. Examinations were made at this time by a number of geologists, including the senior author. In spite of high radioactivity, sampling returned only negligible uranium. The claims were allowed to lapse and the showings reverted to obscurity."

Jan 1, 1949

By Parsons. Robert B.

"Starting this year, corporations that conduct business in Ontario face a new tax a corporate minimum tax. This tax is in addition to the myriad of other taxes that make up a corporation's total tax burden including federal and provincial capital 1oXJ!S, payroll tax and sales taxes. Mining companies with gross revenues in excess of $10 million or total assets exceeding $5 million may be liable for this new tax. IntroductionOn December 8, 1993, the Ontario government introduced legislation to implement the corporate minimum tax (CMT promised in its May, 1993 budget. There are very few differences between the final legislation and the budget proposals.The CMT is effective for taxation years commencing after 1993. Subject to certain specific exemptions (detailed below), the tax applies to all corporations liable for Ontario Corporate Income Tax that have either gross revenues in excess of $10 million or total assets in excess of $5 million. These measurements apply to the aggregate gross revenues and total assets for all corporations in an associated group and a corporate partner's share of partnership assets and revenues must be included in the determination.In essence, the CMT is an income tax that is based on financial statement profit instead of an income amount that is determined separately under a statute. Accordingly mining companies (including so called ""junior"" exploration companies), which traditionally sheltered their taxable income by claiming generous exploration and development deductions, could find that they have a CMT liability."

Jan 1, 1994

By T. H. Adair

"IntroductionCONTINUOUS casting of ferrous and non-ferrous metals is not a new innovation. Patents describing machines for continuous casting are on file as far back as the year 1842. In the middle of the last century, Sir Henry Bessemer conceived and built a continuous casting• machine for the production of mild steel sheet.The production of billets and slabs of both non-ferrous and ferrous metals is being carried out by the continuous method on a fairly large scale on this continent and abroad. At present, the volume of production of •copper and aluminum and their alloys in billet and slab form is much greater than the continuous casting of steel products. The new installation of a continuous casting unit at Atlas Steels, Limited, is designed primarily for the casting of alloy steel billets and slabs.As an introduction to the art of continuous .casting of metals, it is interesting to examine a few of the many devices which have been developed. As previously mentioned, Sir Henry Bessemer constructed a machine for the direct casting of mild steel sheet. His discoveries and ideas of continuously casting steel formed the foundation for the work of other pioneers in this field, all of whom have contributed to the improvement of this art through the ensuing years. The machines which will be selected for examination are those of Bessemer, Poland-Lindner, Williams, Ennor, and Junghans. The last unit to be discussed will be a modification of the Junghans machine recently installed at Atlas Steels."

Jan 1, 1954

By Ferrin Prince

New Gold?s New Afton mine is an 11,000 tonne per day block caving mine, located 8 km west of the city of Kamloops, British Columbia. The reserve is estimated at 52.5Mt with grades of 0.65 g/t Au and 0.93% Cu. Block caving requires a considerable amount of infrastructure development before production can begin. Each excavation had its own challenges, often further complicated by interactions with the caving stresses and fault structures. The main areas of interest were: the production crusher complex, the surface to underground infrastructure, and the footprint interaction with the faults. The ore zone at New Afton is bounded by two very weak fault zones, with large fault affected areas and associated splays. The resulting rock mass rating (RMR) is 35-50, with some areas significantly weaker due to clay infill. These conditions created a unique and decidedly difficult environment in which to develop New Afton?s infrastructure. Despite these difficulties, the mine began production on schedule in July 2012. The main production crusher for the mine is a gyratory crusher that allows for direct truck dumping, with a smaller jaw crusher in series to facilitate the initial development and production. The crusher chamber was redesigned several times to minimize the chamber volume, resulting in a 40% decrease in volume without losing functionality. After drilling and geotechnical testing, the location of the crusher was changed to eliminate the threat of fault affected ground in the area; the entire complex moved a short time before mining began on the chamber. The mining techniques used enabled tight control of the crusher pocket excavation, while also allowing for the timely completion of the chamber. The locations of the surface to underground infrastructure were tightly constrained by geology, surface infrastructure, and an existing open pit. The VR5 raise was drilled and abandoned part way through the reaming process when the drill string became stuck in fault gouge material. It was relocated and successfully completed. The VR7 raise hit a region of poor rock strength and deviated more than 11 m. Poor ground conditions caused a 130m section of the raise walls to fail. An innovative rehabilitation program was undertaken to re-establish the raise for ventilation. A surface to underground slick line was also installed to ease the material movement underground. A layout of the Extraction level was changed from herring bone to straight through drawpoints that resulted in a net reduction of 1.3 km of development. The Apex level was added to aid in the breakage over the major apex pillar and allow for geological mapping. A portion of the caving footprint is located within the footwall fault. The low strength, high clay content, and small joint spacing of the material resulted in blast-hole cut-off and drift deformation. Drift rehabilitation was a key factor in the successful development of the cave footprint. Innovative drilling and loading techniques were used to keep the holes open and to impede movement along the joint structures.

Aug 1, 2013

By Christopher W. N. Anderson

Induced hyperaccumulation of gold by plants was first reported in 1998 by researchers from Massey University in New Zealand who proposed the idea of mining gold using plants (phytomining). Since that time research has been conducted to understand the conditions under which plants can be made to take up economic amounts of the metal. One key focus has been on the geochemistry of gold-rich soils, leading to a diagnostic test that can predict how suitable a particular soil might be to gold phytomining. Field trials have been conducted at several locations around the world in collaboration with industry partners. A Decision Support System has been developed to assist in the design and management of phytomining operations, and economic modeling has been carried out to set targets levels for phytomining technology. Novel studies are now examining the form of gold in plants. Research suggests that plants may store gold as discrete metallic nanoparticles in leaf and stem tissues, an observation that may lead to new ways to recover the metal from harvested biomass.

Oct 1, 2003

By F. W. Crossland

Losses of metal are often traced to incorrect pH/ORP signals in flotation, leaching, extraction, electrolysis, and precipitation processes, aggravated by pressure changes. IC Controls, a Canadian mining sensor manufacturer, developed a new superior pH/ORP sensor that stops metal losses, reduces environmental footprint and contributes to sustainability. The cause of incorrect pH/ORP signal is rooted in the reference. Reference junctions are designed to allow diffusion of reference chloride ions into the process but also allow process ions to diffuse into the reference. This development is important to mines and hydrometallurgists where sulphide, cyanide, ammonia and other poisoning ions are present in the process. These ions react with reference electrolyte components causing the signal to change, drifting from the correct process value. With fluctuating process pressure, ion in migration dilutes the electrolyte producing similar signal drifts. If process ion in-diffusion could be stopped, the pH/ORP signal would be accurate. IC Controls new pH/ORP sensor stops process ion in-diffusion, and remains accurate over long periods. New processes using higher pressure and fluctuating pressurized reactors will greatly benefit from stable pH readings. Similar to IC Controls' proven model 642 Mining pH sensor, our new model 647 contributes to sustainability through reducing disposal costs from waste reagents, lost metal and fewer used sensors.

Jan 1, 2014

By Shamia Hoque, Charles Q. Jia

Smelter slags contain valuable metals such as Co, Ni and Cu in proportions of less than 1 wt% along with about 40 wt% of Fe and 15 wt% of Si. Although aqueous SO2 is a versatile lixiviant for transition metals, dissolving the slag in aqueous SO2 produces solutions in which Co and Ni concentrations are lower than that of Fe due to the low metal/ Fe ratio in the slag. To develop the options for increasing Co and Ni concentrations the solubility of slag in aqueous SO2 was studied experimentally and theoretically using OLI, a software package for simulating electrolytes chemistry. The modeling results correlated well with experimental results. The model suggested that the species dominating the system was FeSO3, which would precipitate out as FeSO3.3H2O when the concentration of Fe+2 reached 1.22 molal and the concentration of S032- was beyond 1.4 molal. In the experiments the influence of pH and solids loading were studied. The leach solution obtained after dissolution of slag at 50% solids loading had a pH of 1.85. On raising the pH to 3, precipitation occurred. Analysis of the solution collected after the addition of alkali showed over 50% reduction of Fe, Co and Ni. XRD analysis revealed the precipitate to be of amorphous nature due to the silica present. The analysis confirmed that the precipitate was mainly FeSO3.3H2O. The paper also discusses the potential impact of the slag on the environment.

Jan 1, 2004

By T. T. Chen, J. E. Dutrizac, G. Poirier

In the Waelz kiln process, EAF dust is converted to an Fe-rich slag, a (Zn, Fe)-rich dust that is recycled to the kiln and the Zn-rich Waelz oxide which is subsequently up-graded for the recovery of zinc. To clarify the reactions occurring, the Waelz kiln products from a European Waelz plant were characterized mineralogically to determine the mineral species present, their micro-textures and the metal carriers. The EAF dust contains 27 % Zn, and consists mainly of ZnFe2O4 and ZnO, together with minor to trace amounts of NaCl, PbCl2, KCl, CaO, Ca2Fe2O5, Fe203, FRO, Pb oxide and various Ca-Fe-Al-Mn silicates. The KCI and NaCI sometimes agglomerate the other particles. The slag consists of nodules which often exhibit colloform structures. The slag contains of variable amounts of Fe, FeO(OH), FeO, gypsum, Ca(OH)2, Ca2SiO4 and various Ca-Fe¬Al-Mg-Mn silicates as well as minor to trace amounts of ZnFe2O4, Cr-Fe oxide, Mn-Fe oxide and other species. The Waelz oxide contains 57-61 % Zn, and consists predominantly of ZnO, with minor to trace amounts of KCI NaCl, Pb(OH)Cl, Pb20(SO4), Pb chloride, ZnSO4, ZnFe2O4, Ca2SiO4, Ca2Fe2O5, Ca-Fe silicate and NaZn4(SO4)(OH)6Cl.6H2O. The KCI agglomerates the other particles in the Waelz oxide. The recycled dust appears to be a mixture of EAF dust and Waelz oxide, but it contains relatively more coarser-grained metallic Pb and Pb oxide particles.

Jan 1, 2004

?It is not the strongest of the species that survives, nor the most intelligent. It is the one that is most adaptable to change.? Charles Darwin. Canada?s mining and exploration companies have evolved over the past century from essentially a pick-and-shovel industry to a high-tech industrial sector. This evolution has occurred in fits and starts, and has been driven by the shifting environment of economic, technical and social opportunities and pressures in Canada. As labour costs have gone up, and labour availability has gone down, the industry has evolved more efficient processes. As mineral prices have increased or fallen, the industry has evolved either by expanding or shrinking production, or by changing processes to adapt to the newly prevailing conditions. As stringent environmental protection legislation has been implemented, the industry has adapted accordingly, and has substantially changed its mindset to incorporate sustainability into its way of doing business. These changes have occurred over a number of decades, and have usually occurred as the industry?s reluctant response to pressures it couldn?t evade. This model mirrors the classical paradigm of natural selection where evolution is driven by pressures external to the organism (or organization) ? change occurs to the degree necessary for survival and prosperity, but generally no further. In recent years a new paradigm has started to come into play in Canadian mining and exploration. Rather than only a reactive response to the external economic, social and technical factors, groups within the mining community are becoming proactive in developing strategies for future adaptive change. Instead of each against the other, they are developing more sophisticated paradigms where they can both compete against (such as in marketing) and cooperate with (such as for tech development) their fellow organizations. Most importantly, they are seeing individual and national advantage in a collaborative Canadian approach to address the advantages of overseas competitors who often have lower labour costs, lesser environmental standards, or more accessible markets and transportation. This has translated into large-scale mining community support for the Canada Mining Innovation Council, and its programs in exploration, mining, processing, HR development, energy and environmental stewardship. This new paradigm is adaptive to the current environment but is substantially different from the older way of doing business in two major ways ? it is based on a collaborative approach to competitive advantage, and it is highly proactive rather than reactive. All the programs have their priorities determined principally by the mining and exploration companies, whose first obligation is to determine the long-term research priorities of the industry as a whole, rather than for their individual companies. Only after industry consensus on priorities does the research community become engaged in the implementation of specific projects to address those identified priorities. A goal of the program is to effectively create a virtual mining research laboratory, by engaging all the major research centres in the country. This approach is being actively adopted by much of the Canadian mining community, and argues well for the adaptability and long-term survival of mining in Canada.

Aug 1, 2013

By George Kellock

In presenting this paper for discussion at the Western Annual Meeting to be held in Edmonton, it is with the idea of creating a full and general discussion by the mining men in the Province as to the best way to eliminate, or at least hold down to a minimum, the dangerous coal-dust which is made in mining pitching seams in our Alberta mines by the chute method. Also, an alternative method is outlined, whereby the percentage of lump-coal mined can be increased, and the mining costs reduced-although the paper does not go into any detailed consideration of costs. The general trend of mining practice and lay-outs is at present towards mechanization, and the results being accomplished by the substitution of machines for manual labour are fully justifying the changes. In the technical mining journals, there are published from time to time papers dealing with a variety of methods of mining, which are descriptions of actual operations, and a great deal of interesting and valuable data is given as to the comparative values of the different methods, insofar as the percentage of grades of coal produced, the cost of production, etc., are concerned; but the mechanical methods described in these papers are nearly always suitable only for flat seams, or seams with a very low inclination.

Jan 1, 1929

By Gaétan Bourdages

A clarification technology used by municipalities to produce high-quality drinking water, polish sewage treatment plant effluent and handle combined sewer overflows has recently found new applications in the mines and iron and steel industry. This patented process, known as ACTIFLO®, utilizes microsand in a ballasted flocculation process to enhance the settling characteristics of suspended solids, increasing the efficiency sufficiently to achieve a clarifier footprint that is smaller than the one of a conventional clarifier. ACTIFLO® rise rates vary from 40 to 170 m/h with a total system hydraulic retention time of about 10 minutes. The result is a clarification system so compact that a full-scale system can operate as a trailer-mounted unit for temporary applications or as a permanent installation in facilities with space limitations. This paper explains the process and presents case studies in which this innovative technology was used at mines and steelmaking facilities to meet compliance requirements.

Feb 1, 2008

By G. Yan

The gas diffusion layer (GDL) is one of the most critical components of the proton exchange membrane fuel cell (PEMFC) in achieving good performance. The GDL serves as a current collector, transport media for fuel and oxidant to the catalyst layers, a support for the catalyst layer and a medium for water management. In this paper, we will discuss the modeling and experimental measurement of the reactant distribution in the GDL and to the catalyst layer. This will be done for some new and advanced engineered GDLs. Novel optical technique which correlates measured data with reactant distribution are used. This technique combined with modeling allows optimal design of engineered GDLs.

Jan 1, 2005

By E. Y. Carlson

"IN A SHORT PAPER it is impossible to do much more than to list the industrial minerals found in Saskatchewan and to give a brief description of the activity associated with each. I will not attempt to discuss the geology. It is sufficient to say that the settled part of the Province is covered by glacial drift which varies in thickness from a few feet to several hundreds of feet, and that this has hindered the search over much of the Province.CLAYA notable exception to this is the Cypress Hills area in the southwest corner which did not suffer any glacial action and where we find some of the large exposures of Cretaceous clays. In this area, the majority of the deposits are of stone-ware clays which are •an excellent raw material for such products as face brick and sewer pipe. Although the clay cannot be transported over any great distance it is used extensively in Alberta and Saskatchewan in the production of these products."

Jan 1, 1959

By M. Soleimanifar

With more and more industrial construction projects implementing RFID and other sensor-based technologies on fabrication and project sites, new innovative processes are needed to help automatically read and re-position RFID tags while reducing the cost to deploy RFID infrastructure over large areas. RFID tags are being used on construction sites to help identify the location of materials, equipment and personnel to aid in finding project critical materials and equipment required to construct the industrial facility on time and on budget. This research provides a cost-effective process for reading tens of thousands of RFID tags over large project sites from outdoor laydown yards, to warehouses to the workface where the materials and tagged equipment are installed. Based on the collected RFID and sensor data, localization mechanisms determine the most recent coordinates of the tagged components. The paper will cover analysis of RFID collected data and key lessons learned from a commercial deployment of the SiteSense® system with one Alberta-based industrial contractor, JV Driver Fabricators, at an 80-Acre module, pipe spool and structural steel fabrication site.

Aug 1, 2013

By Michael Klichowicz, Holger Lieberwirth

"For a detailed prognosis of mineral comminution processes, simulation tools like DEM still pose various challenges. Less realistic mineral structures can affect the results of simulation models such as bonded-particle models (BPM). Hence, in order to design mineral processes with these models as tools, representative mineral input data should be used. The article shows, how realistic 2D-structures can be modelled by taking advantage of the parameters identified by the Quantitative Mineralogical Analysis (QMA). Important quantitative parameters can be derived by analyzing three orthogonal thin or polished sections. For this reason point, line, and area analysis are applied. The mentioned parameters precisely describe the texture and structure of minerals. The newly developed software is able for the first time to semi-automatically analyze images of mineral structures using QMA. Moreover, statistically equivalent structures of minerals can be modelled using the QMA- parameters. Generating synthetic, but equivalent mineral structures opens the door for more reliable BPM based simulations. Within future research, the procedure will be adopted to generate 3D-structures. Therefore, QMA-based routines that already have been applied to generate 2D-models shall be utilized as basis. The aim of this procedure is to synthesize realistic microstructures based on certain statistical figures in order to improve comminution simulations.INTRODUCTION Due to its increasing capability, the use of computer technology is permanently intensifying in the design of mineral processes. The recent past has impressively shown that computer models can enhance the understanding of mineral processing. There is in fact a rising number of research activities, which are using simulation approaches to study various aspects of it. Weerasekara et al. (2013) give a comprehensive overview over the application of discrete element modelling (DEM) in the science of comminution.Nonetheless, using simulation tools such as DEM in general still poses a challenge. For a detailed simulation of a mineral comminution process with DEM, bonded particle models (BPM) appeared suitable in the past. The following issues, however, affect an appropriate prediction when modelling with BPM:• Simulations with high numbers of particles may need a lot of time for computation. • Internal modeling parameters like the spring and damper constants in DEM have to be adjusted by comparing its specific crushing behavior in the simulation to reality.• In order to use DEM for prediction of mineral processing, it is essential to validate the correctness of the models and assumptions, which is sometimes difficult. As Weerasekara et al. (2013) have stated it is crucial that the DEM method as well as the DEM code work properly.• It is challenging to implement the complex geometric structures of real minerals into the model."

Jan 1, 2016

By MacKenzie Dickson

"INTRODUCTIONGold is found in many natural states, native nuggets, loose grain in river sands, veins in rock, as well as associated with sulphides, oxides, etc., disseminated more or less minutely.Its high value in recent years has spawned new technologies to win values from sources once considered too lean for commercial recovery. Cyanide leaching from fine milled ore or tailings, from upstream recovery operations, coupled with adsorption onto relatively coarse granules of activated carbon, concentrate the gold enough to be converted to bullion by time-honoured methods.The carbon granules are fragile. Size degradation in handling must be minimized not only to prevent loss of gold on fine fragments of carbon that could pass with the barren tailings, but to maintain adsorption efficiency. Besides, the granulated carbon itself is costly. Circular Vibroscreens are winning acceptance for dewatering carbon granules thanks to their gentle yet effective performance in gold recovery systems around the world. The system at Equity Silver is illustrative.BackgroundEquity Silver Mines Ltd., Houston, British Columbia, first began production in September 1980. In 1984, a feasibility study showed that additional gold and silver could be economically recovered through cyanide leaching of the flotation tailing.Although the carbon-in-pulp (ClP) or carbon-in-leach (CIL) process is commonly used for extracting precious metals from slurries, the use of circular vibrating screens, and Vibroscreens in particular, for the carbon circuit is an innovation that cuts costs.Rectangular vibrating screens have been the conventional separation mechanism of choice across North America. In contrast, the use of Vibroscreens has been proven to be less costly for the initial purchase and installation. Also, these circular vibrating screens require less power and less space. A description of Equity Silver Mines' process shows how these screens have been successfully integrated into the system."

Jan 1, 1989

By Damian Connelly

The option to leach iron from low grade copper concentrates could reduce transport costs and significantly improve the saleability of the concentrate. In addition, it reduces smelting costs and can remove undesirable impurities. The trend to produce cleaner and higher grade copper concentrates is very appealing to the smelters. A recent copper project came on line and there were three serious deficiencies which were not identified in the feasibility study. This came as a surprise and resulted in a number of projects to investigate ways of rectifying the problems in the shortest timeframe possible and using minimal new capital. The first serious issued not identified when commissioning was the lower than expected copper recovery, which was 70% compared to a predicted recovery of 80% to 87% in the feasibility study. This required investigating new flotation reagents and incorporating controlled potential sulphidisation. The second serious issue overlooked is the presence of significant amounts of talc minerals (insol) in the ore which are naturally floatable. This leads to lower concentrate grade and attempts to remove the talc resulted in lower copper recovery. Smelters have limits on the amount of talc in concentrate because it produces viscous slags and difficulties for the smelter. It also incurs higher transport costs. The third serious issue not identified in the feasibility study was the high arsenic reporting to the concentrate. Arsenic is a penalty element for smelters and at levels exceeding 0.3% the smelters may reject the concentrate. Arsenic is a problem environmentally for copper smelters and penalties apply when it is high. This paper describes the options for penalty element removal and suitability to incorporate into the modified flowsheet. It also highlights where the geometallurgy was not properly addressed and how these surprises could have been avoided. INTRODUCTION From 1970 to 1985, a copper company undertook metallurgical testwork on the Peruvian project copper ore. The ores were mined underground and treated over many years previously. Various other groups undertook studies and work until Aker Kvaerner undertook a feasibility study in 2006. Three ore composites were tested and grind-recovery relationships were developed. The feasibility study testwork identified that talc was a possible concern and will have an impact on copper concentrate grade. This was to be managed by blending. The current operating reality is that there is so much talc in the ore body it is not possible to blend it out. There was far more emphasis on molybdenum recovery. No mention was made of arsenic issues other than blending. There was a Concentrate Leach Study and a Molybdenum Hydrometallurgical Plant Study but these options did not proceed to a final flowsheet. A Scoping Study in 2006 looked at a Heap Leach project. The heap leaching gave very poor copper recovery on the sulphide ore. Heap Leaching was evaluated and tested for the high talc and high arsenic ore but recoveries were poor. The Aker Kvaerner feasibility study opted for a simple primary crush SAG/ball grind followed by flotation and sale of a concentrate. This is the current flowsheet utilised and the scale of the project is very large based on processing 117,200 tonnes of ore per day. A feasibility study does not guarantee success and the deviations from the feasibility study suggest there is a lot of technical work required to improve the current metallurgical performance.

Jan 1, 2019

By P. R. A. Andrews

"Talc ore from Bakertalc, High water, Quebec analyzing about 60% talc, previously dry ground to about 95% minus 53 µm was beneficiated in an 11.4 kg/ h pilot-plant flotation circuit. A concentrate of 95.9% talc (necessary for paper-grade) was obtained at a recovery at 75.3% by employing 53 g/t of Dowfroth 250 collector at pH 9.2; further cleaning increased the grade to 97.2% talc at a recovery of 57.5%.Flotation of fresh ground 60% minus 44 µm ore at a feed rate of 18.6 kg/ h produced a grade of 96.4% talc with a recovery of 78.2%, using Aerofroth 70 collector a six carbon-branch chain alcohol, at pH 9.2.The similarity in the concentrate grade and recovery between pre-ground and fresh-ground ore indicated that it was not neces¬sary to grind to 95% minus 53/2m to achieve comparable selectivity. A grind of 60% minus 44 pm corresponds to 100% minus 300 µm.Flotation retention times obtained with fresh ground ore indicate 33 min. for combined rougher/scavenger, and 15 min. each for the first and second cleaners.Talc-magnesite flotation separation is explained in terms of physico-chemical forces, with reference to surface charge and adsorption mechanisms."

Jan 1, 1989

By Hongyan Qu, Lihui Zheng

"Horizontal wells in coal seams, Qinshui basin, China are prone to wellbore instability problems induced by drilling, completion and production operations due to the presence of natural cleat network, anisotropy with regard to permeability, brittleness and mechanically weak property of the coal rock. The mechanism of wellbore instability in coal seams is very different from that in conventional formations, the traditional wellbore stability study methods therefore, are not proper for wellbore stability analysis in coal.In this study, the mechanism and controlling of wellbore stability of coal seams in the Qinshui basin was investigated through theoretical modeling, laboratory experiment and field operation. Firstly, a new physical model of wellbore stability for highly-cleated coalbed was proposed, considering the combined effect of mechanical mechanism and reservoir characteristics, specifically, taking the effect of reservoir pore pressure in the vicinity of the wellbore on the wellbore stability into account. Then experiments on the triaxial stress evaluation were conducted at laboratory where rock mechanical parameters such as Poisson's ratio, Young's modulus, compressive strength, tensile strength, angle of internal friction and cohesion ability were measured respectively. The in situ stress at different depths in four wells of Zheng 1-303, Zheng 1-308, Zheng 1-309, and Zheng 1-310 in the Zhengzhuang were calculated, and the collapse pressure and formation breakdown pressure were predicted through the theoretical model we developed. Finally, by comparing the maximum collapse pressure and minimum breakdown pressure of the four wells in the coal as well as in the roof and floor of the coal seams, the fluid weight window for safe drilling in each coal seams was determined, and appropriate approaches against anti-sloughing in coal seams, Qinshui basin were applied in the field operation.The wellbore stability was found not only related to the wellbore pressure, but also affected by the pressure in the reservoir through the theoretical model. The fluid weight window for safe drilling in each coal seams varies with the coefficient of wellbore stability in the model. The laboratory experiment results indicate that the roof and floor of 3 # coal in Qinshui basin has high breaking strength, high heterogeneity, and are easy to collapse and breakdown. In addition, the whole rock mineral analysis shows that 3 # coal in the Duanshi block has high clay content, resulting in the phenomenon of hydration swelling as clay encountered water, and leading to unstable coal and extreme large drilling uncertainties. Due to the effect of the unstable rock mechanical properties of the roof and floor formation on the wellbore stabilizing, drilling parameters, drilling fluid performance and BHA were optimized during the drilling process according to the formation properties, rock mechanical properties and drilling techniques in the field operation."

Jan 1, 2015

By Debasis Deb, Ankur Narang, G. P. Raja Sekhar, Kamal C. Das

"The stability of underground structures made (especially) in jointed rock mass is of the utmost important to designers, engineers and operators. Rock bolting is generally being practised to reinforce excavation walls and roofs by minimizing the movement of rock joints. This study proposes a new analytical model for the prediction of displacements, axial load and shear stress of a fully grouted rock bolt intersected by single or multiple rock joint(s). The governing equations for rock bolt are derived based on the assumption that shear force generated by slippage along the bolt-grout interface has a linear relationship with respect to the relative displacement at the interface. The proposed model is novel compared to the existing literature in the sense that it accounts for rock kinematics as an enriched sum of a continuous part (elastic) and a discontunous (jump) part due to the presence of joint planes. The complete solution of the bolt displacement, axial load and shear stress is derived as a function of the rock displacements, and, it comprises of Heaviside and/or Dirac delta functions in the solution space due to the jump at the intersection point(s) of bolt(s) and joint(s).Our novel solution is able to predict the elastic behavior of a grouted bolt, subjected to opening of the joint planes in pull-out test and also in excavated tunnel. These two cases also serve as benchmarks for grouted rock bolts with multiple joints and can be used for validation of numerical and experimental models. Further, the solution is applied to analyze the behaviour of grouted rock bolt as well as cable bolt installed in circular tunnel, with variations in rock joint(s) opening displacement, shear stiffness in the boltgrout interface and locations of the joint planes. Results indicate that for a specified grout stiffness, the maximum axial load developed in the bolt for discontinuous distribution of rock mass displacement is significantly higher than that of the continuous distribution of rock displacement. This paper provides an analytical interpretation of bolt beaviour considering multiple joint planes with variable joint opening displacements. The results obtained via the analytical method are in line with the corresponding investigation done by other authors. Thus, our analytical treatment can be used to understand bolt behaviour in realistic situations."

Jan 1, 2015