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By T L. Horsley

This paper deals with the drilling and blasting methods employed at the Cassiar mine, which is located just south of the B.C.-Yukon border. It covers both the "pit" and "peak" mining operations. Specific problems, such as working in frozen ground, are discussed, and the breaking characteristics of the various rock formations are outlined. The paper concludes with a brief mention of the equipment used in the operation, as "~ell as an outline of the breaking costs. Introduction T HE Cassiar asbestos mine is located just south of the British Columbia -Yukon border high on a spur of McDame mountain. Chrysotile asbestos fibre occurs in a faulted enlargement of a serpentine sill lying conformably be-tween a series of sedimentary beds and volcanic flows which dip at 45 degrees into the mountain. One end of the orebody is eroded by a cirque in which a layer of permanently frozen ore and waste talus lies at the end of the mining benches. The topography at the mine is steep, with no flat areas. Roads, dumps, and areas for crushing,

Jan 1, 1965

By S. Hobo, M. Yagisawa, T. Uchida, C. Tokoro, T. Kato

In this study, quantitative modeling was carried out for the treatment of simulated waste water containing As(V), Zn(II) and Hg(II) as toxic elements, and Fe(III), Na(I) and sulfate as coaxing ions. The objective was to predict the pH and residual concentrations of all the elements in solution after the neutralization/co-precipitation treatment. To accomplish this, the removal mechanism for As(V) and Hg(II) by ferrihydrite precipitation was first investigated for simulated waste water containing only As(V) or Hg(II). From the experimental results, it was confirmed that the removal mechanism involves not only surface complexation but also surface precipitation. However, surface complexation is the main mechanism for As(V) and Hg(II) removal to meet the target levels regulated in Japan. Next, the surface complexation model was constructed for the removal of As(V) and Hg(II) by ferrihydrite. The specific surface area and site density were determined from reference values proposed by Dzombak and Morel (1990). By comparing the experimental and calculated results, it was confirmed that our constructed model could successfully represent the experimental results. Furthermore, the surface complexation model was coupled with chemical equilibrium calculations and applied to the neutralization of simulated waste water containing As(V), Hg(II), Zn(II), Na(I), Fe(III) and sulfate. The constructed model could successfully represent the pH edge for As(V), Hg(II), Zn(II), Fe(III) and SO42- removal. In addition, the constructed model could represent the ion balance. Thus, our constructed model is useful to estimate the amount of neutralizer that is needed to achieve a target pH.

Jan 1, 2016

By Ros Taplin

Realizing the potential of cutting greenhouse gases (GHGs) associated with mining, a variety of approaches has been proposed for their mitigation. The Clean Development Mechanism (CDM) under the Kyoto Protocol to the UN Framework Convention on Climate Change (UNFCCC) has been a key mechanism to assist in implementation of mitigation measures. The objectives of CDM are not only to assist Annex I countries in meeting their GHG emissions reduction targets with cost-effective reduction but also to achieve sustainable development in non-Annex I countries. However, apart from China, India, Brazil and Mexico, many developing countries are still in the stages of formulation or realizing CDM strategies. Projects associated with methane capture and flaring are the fourth most prevalent type of CDM project internationally. This research primarily has addressed emissions abatement and sustainable development aims and effectiveness of registered CDM projects associated with coal mining in China. The paper reviews 30 currently registered CDM projects in China on the UNFCCC database and six other non- Chinese projects. Systematic evaluation involving content analysis of documentary evidence regarding coal mining CDM projects is presented in relation to firstly, quantitative reduction of GHG emissions and secondly, sustainable development outcomes. The projects have been assessed via a set sustainability criteria. Overall it was found that sustainable development goals are only briefly referred to in Project Design Documents, Letter of Approvals and validation documents. Varying types of sustainability initiatives have been implemented with weak to strong indications of effectiveness. This has implications for the future effectiveness of CDM projects in the mining sector, the proposed new market mechanism under UNFCCC, and for assessment of projects under mechanisms established outside the UNFCCC.

Aug 1, 2013

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 M. M. O?Brien

THE SULLIVAN MINE The Sullivan mine of the Consolidated Mining and ? Smelting Company of Canada, Limited, is situated at Kimberley, B.C., nineteen miles from Cranbrook, a divisional point on the Crowsnest Pass branch of the Canadian Pacific railway. Production started on a small scale in 1900, and in 1914 the mine became the largest lead producer in Canada. In 1925 it was the largest single producer of lead and zinc in the world. Since operations commenced, 4,800,000 tons of ore have been produced from stopes and 170,000 tons from development. At the present time, ore is being mined at the rate of 1,100,000 tons per year, with a yield of about 200,000 lb. lead, 110,000 lb. zinc, and 4,000,000 oz. silver. The town of Kimberley is easily accessible by road as well as by rail. The altitude at Mark creek, a tributary of the St. Mary's river, is 3,700 feet. To th'e north of the creek, Sullivan hill rises to a height of 6,100 feet, and it is on the southern slope of this hill that the mine is located. Sullivan hill is in the Purcell range, which rises between the Rocky Mountain trench on the east and Kootenay lake on the west. It thus lies within what is commonly referred to as the East Kootenay district.

Jan 1, 1926

By E. S. Moore

In order that a logical conclusion may be reached regarding the possible occurrence of commercial iron deposits in Canada it is necessary to consider some important producers found elsewhere on this continent. A study of such deposits reveals the fact tl:~at a number of distinct types are producing large tonnages of ore. These types may be classified according to origin and occurrence as follows: (1) Bedded sedimentary deposits. (2) Contact metamorphic deposits. (3) Residual ores. (4) Lenses in metamorphic rocks and m some cases of uncertain origin. In addition to the types listed there are other deposits which have contained or do contain considerable ore and they either have not been worked on a large scale or they have been nearly exhausted. These include the following types: (1) Magmatic segregations. These are mostly titaniferous magnetites. (2) Dikes of magnetite of igneous origin. (3) Bog and lake ores in glacial drift. (4) Black sand placers.

Jan 1, 1925

By Mohammad Reza Khalesi, Ruhollah Rezazadeh, Mohsen Izadi Yazdan Abadi, Mahmoud Abdollahy

"The rotary vacuum drum filter (RVDF) is widely used for dewatering in mining industrial. In general, different parameters have influence in the solid-liquid separation such as: solid percent, level of vacuum, particle size distribution, filter cloth and chemical additives. These parameters can influence on some variables such as cake moisture, throughput and filter cloth life time. The aim of this study is to propose some chemical additives to improve the rate of filtration and decrease cake moisture of Gol-E Gohar iron ore concentrate by using laboratory scale bottom feed vacuum filter and suggest a filter cloth with long life time (more than 400 hours). Effect of particle size distribution on filtration investigated in large scale by measuring the thickness of cake and cake moisture.Increasing molecular weight of anionic flocculant lead to increases throughput but cake moisture increases too; While the filter aid increases throughput and decreases cake moisture simultaneously; the combination of them show different behavior. TSS and filter cloth life time have directly relation with material and type of filter cloth weave. Depending to type of feed, two polyester and polypropylene filter cloth are suggested. More over twill and satin weave have the best results. To prove the laboratory results some industrial tests performed in Gol-E Gohar hematite iron ore concentrate plant.INTRODUCTION“The process of grinding and classification involves the use of large quantities of water. The separation of solids from liquids is usually achieved by gravity sedimentation in thickeners. For fine particles this is a slow process. In general, 75–80% of the water can be separated and removed by thickeners. For further water removal, filters are used where in excess of 90% of the water can be removed” (Gupta, 2006).“Many types of filters are available, which are broadly classified here as vacuum, pressure, precoat and depth filters. Each classification contains a number of sub-processes. A category of filter that uses vacuum induced driving forces and semipermeable media to facilitate the separation of solids from suspension. While pressure differences across the filter are limited to less than 85 KPa (usually 75 KPa), most units are capable of processing a wide range of feed materials in a continuous manner” (Rushton, 2008)."

Jan 1, 2016

Operating and Social Considerations from a Contractor?s Perspective

May 1, 2013

By A. Flemming

"As the next century draws near, new mine properties must be brought into production to replace existing operations that are approaching their economic life. This paper presents some of the critical technical issues being addressed by Manalta Coal Ltd. as they strive to bring the Telkwa Coal Project near Smithers, BC into production during the year 2000. The mine is planned to produce between 1.0 to 1.5 million tonnes per year of medium volatile coal for export to overseas thermal and PCI markets. IntroductionManalta Coal Ltd. (Manalta) is proposing the development and operation of a surface coal mine and associated infrastructure approximately six kilometres southwest of the village of Telkwa, British Columbia (Fig. 1). The infrastructure consists of a coal washing facility, tailings disposal area, clean coal haul road, access road and rail loadout facility. Over a 25-year period, the mine is expected to produce between 25 and 37 million clean tonnes of coal primarily for the export market.To achieve public and governmental approval for the development, the project will be reviewed under British Columbia’s Environmental Assessment Act. Manalta entered the formal Assessment process in February 1, 1997 with the submission of an Application for a Project Approval Certificate for the Telkwa Coal Project."

Jan 1, 1997

By D. D. Downing

This paper is a review of material selection considerations concerning protective coatings in the mining industry. The discussion will cover both capital-dollar projects and maintenance requirements. Emphasis will be on industrial finishes for structural steel and process equipment subjected to aggressive atmospheres. The presentation will cover the total needs of a job, emphasizing not only the owner's requirement for a cost-effective system during plant operations, but also taking into consideration the short-term requirements of general contractors, steel fabricators, erection firms and paint contractors.

Jan 1, 1979

By O. Mejia

"As study was undertaken to investigate the relationship between mill liner wear and grinding energy efficiency and to assess the opportunity to control mill speed to improve energy performance as mill liner wears. The study involved analysis of plant operating data and liner wear profiles over time. The operating work index was found to be an effective tool to identify the decrease of grinding efficiency along the liner service. The plant data show that the mill grinding efficiency as determined by monitoring the operating work index, and throughput decreases as liner wears. However, efficiency and throughput can be maintained by either changing the liner more frequently or by increasing the mill speed. Two scenarios for increasing mill throughput were analyzed. The first one involves changing the liner before the efficiency drops and the second one requires increasing the mill speed from 75% to 79%. Both scenarios show financial benefits that can be used in mill operations.INTRODUCTION The analysis of the mill power draw is used in this study as a key parameter for comparing mill liner profile and its effect on mill performance. Current technology and simulation software used in the mining industry do not factor in the impact of liner wear profiles in grinding efficiency and mill throughput (Toor, 2013). To address this gap, this study provides an analysis of key factors affecting mill throughput and grinding efficiency: mill speed, ball loading, and liner profiles. Several years of plant mill operating data, published research papers, and MillTraj® simulation results are used to demonstrate that face angles impact grinding efficiency and throughput and that mill speed can be used to overcome this problem. Moreover, the liner profile wear analyses clarify a mismatch between actual and estimated power draw calculations."

Jan 1, 2019

By Robert Thomson

"The Cobalt camp is by far the most productive camp of the Temiskaming silver-cobalt area. The date of discovery, 1903, is an important one in the history of Canadian mining; from then on prospecting and mining grew rapidly to take the prominent places they now hold in Canadian life.At Cobalt, prospectors and operators, who were to play prominent parts in other Canadian camps, received their initial training. The exploration campaigns leading to the discovery of several new camps were organized at Cobalt, and a considerable part, indeed, of the funds for these campaigns were profits from mining at Cobalt.The discovery of the Cobalt camp was purely accidental, not the result of any purposeful search. Fred LaRose, a blacksmith employed in the construction of the Temiskaming and Northern Ontario Railway, discovered mineral, afterwards determined to be valuable, within a few feet of the right-of-way. This discovery became part of the very productive LaRose mine. The publicity given this discovery, particularly by Willet G. Miller, later Provincial Geologist of Ontario, led to the rapid development of the camp.ProductionCobalt is a great camp by virtue of its silver production; cobalt is also important, although clearly subordinate. Copper, nickel, arsenic, and bismuth are by-products of mining for silver and cobalt and have not been of great importance to date.The following table gives the metal content of ores, concentrates, etc. from the Cobalt camp for the years 1904 to 1954 inclusive, as reported by the mines (l):"

Jan 1, 1949

By Bryon Cerklefskie, Michael Schulte

"This case study explores the usage of polymer ducting as a replacement to curtains and FRP for face ventilation in two coal mines. There are two mines looked at, one is the highest elevation underground coal mine in North America, the other is the gassiest mine in North America. The paper details the trials of both mines switching from FRP and curtain respectively to polymer ducting. The results discuss the ability for the mines to not only achieve consistent airflows and keep them in compliance but the unexpected positives. Mine A was allowed to do longer cross cuts due to increased air volume at the face. This drastically cut their costs of mining down due solely to modification of the ventilation cycle. Mine B saw economic benefits due to longer cuts between place changes. Both mines have documented lower dust, methane, noise, and improved wear and tear on their equipment as a result.INTRODUCTIONThe emergence of longwall mining in underground coal operations has resulted in new ventilation challenges. Numerous production crews strive to complete their development sections with enough time to adequately prepare for the upcoming longwall panel. Continuous miners will cut out two or three entry development sections per their ventilation plan, that is approved and controlled by MSHA (Mine Safety and Health Administration), which will drive amount of footage that can be mined at a time prior to installing roof support. At this moment the continuous miner, hereafter referred to as the CM, will back out of the entry and moves to the second entry to complete a similar cut. Typically, a roof bolter crew will pull in to the finished cut section and install ground support. This is called a place change style of production coal mining. There is an alternate method that includes a miner/bolter combination as well but that was not featured at either test site in this case study. Ventilation has to be provided to sweep the working face of each entry to control dust and gasses. Each task will have an MSHA prescribed ventilation requirement dependent on the dust levels and methane emissions of the rock for that particular mine. The CM, roof bolting and unused headings will each require constant ventilation but at different volumes. Since each working face is changing throughout the mining cycle the ventilation requirement in a working heading is never static and is changing with the working task.Traditional Ventilation ControlsTraditionally face ventilation for coal mining operations has been completed thru the usage of a curtain system and\or using auxiliary fans and ventilation tubing. Room and pillar mining systems typically utilize curtain systems, which use curtain walls that are installed by the miners by erecting wood framing and covering it with brattice curtain. This splits the drift width to allow fresh air to sweep the face and take the contaminated air and dust behind the curtain to the ventilation exhaust\return area of the mine. This method is difficult to adjust the airflow from entry to entry during changing cycles and requires that a wider drift is mined out in order to have enough room for the brattice wall. In operations that require roof bolting, this method limits the length of the cuts from the CM prior to advancing and can lead to not providing enough ventilation to keep dust and methane levels below compliance requirements."

Jan 1, 2019

By W. E. Oching, M. M. Ghomshei

Attracting and retaining workers in mining industry has become an uphill battle to many mining companies. As workers with significant experience retire, it is getting more difficult to attract not only new workers but also top talent to the mining industry to replace professionals exiting the workforce. To make matters worse, students’ enrolment in the post-secondary mining programs in Canada and USA is continuously declining year after year for reasons not directly linked to job market. This raises a question of how can the future needs of mining be met? This paper focuses on avenues for collaboration of industry and educational institutions to meet the current and future needs of mining. It provides effective approaches that mining institutes can engage with program advisory committees, role of the mining industry in supporting both faculty and students, how to harness the benefits of diverse workforce in the country and use of innovative technologies to attract young workers in mining. This work presents Human Resources (HR) professionals with tools that they can use to hire and retain skilled workers with strong interest to work in the mining industry. It also provides HR professionals with an opportunity to re-evaluate their restructuring practices during economic downturns as they reduce number of employees on temporary or permanent basis. The paper stresses the need of working together of the mining stakeholders including mining industry, academic institutions, First Nations’ communities and provincial(state) and federal governments to meet the current and future demands of mining as the industry experiences shortage of labour and low students’ enrolment in post-secondary mining programs. It is shown that mining educational institutes can enhance their programs and recruitments through establishing a better communication with all stakeholders. This communication can be facilitated by creating a national advisory board, to work with all mining programs at the national level for sustainable mining.

Jan 1, 2023

By Zhan Zhang, Hiromi Nagaumi, Zhen Li

"Recently, the remarkable strengthening effect of ??-Al(Mn, Fe) Si dispersoids at both ambient temperature and elevated temperature were found by several researches. A large amount of dispersoids can be formed by applying special heat treatments and within a suitable range of chemical composition of AA3xxx alloys. In the present work, the influences of Cr addition on the mechanical properties and microstructures of the Al-Mn-Mg-Si alloys were investigated. The mechanical properties at ambient and elevated temperatures were evaluated by micro-hardness and yield strength. Moreover, the microstructures in as-cast and heat-treated conditions were quantitatively analyzed by optical and electron microscopes. Results revealed that Cr also had effect on the number density and volume fraction of dispersoids. Micro-hardness and yield strength at ambient temperature increased with the increasing content of Cr, and the Cr addition increased the yield strength at elevated temperature as well. Moreover, the creep resistance at 300°C improved dramatically with the increasing content of Cr.INTRODUCTION Traditionally, AA3xxx aluminum alloys were widely used in packaging, automobile and architecture industries, because of its good formability, excellent corrosion resistance and weldability. And AA3xxx alloys were considered as non-heat-treatable alloys. However, the strengthening effect of dispersoids in AA3xxx alloys was discovered recently (Li & Arnberg, 2003;Li, Muggerud, Olsen, & Furu, 2012; Li, Zhang, & Chen, 2016; Liu & Chen, 2015).Alarge amount of dispersoids could precipitate by a proper heat treatment.In order to further improve AA3xxxalloys, the composition of the alloys should be optimized. A few previous studies were reported to investigate the influence of compositions on AA3xxx alloys. Adding Mn element could enhance the precipitation of ??-Al(Mn, Fe)Si dispersoids and improve the yield strength(Muggerud, Mørtsell, Li, & Holmestad, 2013), as long as the concentration of Mn was under the solid solution limit. Fe decreased the solubility of Mn and accelerated the precipitation rate of ??-Al(Mn, Fe)Sidispersoids(Li & Arnberg, 2003), the yield strength and creep resistance at elevated temperature could increase with an optimized content of Fe(Liu & Chen, 2016). Mg element would affect the nucleation process of ??-Al(Mn, Fe)Sidispersoids by forming metastable Mg2Si(Hirasawa, 1975; Li, Zhang, & Chen, 2017a; Lodgaard & Ryum, 2000), metastable Mg2Si precipitated during heating process and promoted the precipitation of ??-Al(Mn, Fe)Sidispersoids, moreover, Mg provided solid solution strength for AA3004 alloys(Li et al., 2016). Si increased the volume fractionof ??-Al(Mn, Fe)Sidispersoids(Muggerud et al., 2013)and decreased the size of ??-Al(Mn, Fe)Sidispersoids(Li, Zhang, & Chen, 2017b). With the addition of Mo, the size of dispersoids became finer with a higher volume fraction, the volume percentage of dispersoid free zones was reduced. Elevated temperature yield strength and creep resistance improved due to Mo addition (Liu, Ma, & Chen, 2017).However, the effect of Crelements on microstructure and mechanical properties of AA3xxx alloys were rarely reported."

Jan 1, 2018

By C. I. Walker

Field tests at a number of large mineral processing operations have been undertaken to better understand the wear life impact of different aspects of pump design, materials of construction and maintenance procedures. Data are presented for wear rates, and typical result variability is explored. To improve the availability of pumping equipment in a milling circuit it is not only important to improve the wear life, but also reduce the variability in the wear life of components so that the incidence of premature failure is lessened. Localised gouging wear due to flow separation and turbulent eddy formation is often the point at which part-holing occurs. A number of improvements to the design of pump impeller and throatbush (suction side liners) to reduce the localised gouging wear are outlined. Also, results are presented on the use of composite materials (mix of metal, rubber and ceramic) for throatbush materials to protect specific areas against wear.

Jan 1, 2012

By Julian Boldy

"A review of lI5 significant volcanogenic massive sulphide discoveries in the Canadian Precambrian during the past 65 years reveals that only 7% resulted from surface exploration methods aimed at depths below the effective reach of current geotechnical systems. This has been due to the relative ease of shallow discovery, resulting in the harvesting of ore deposits within 100 m of surface. This surficial layer has been more or less effectively supersaturated by routine exploration. In view of the fact that a mining district's metal content is not likely to be confined to a surficial layer, the time has come to explore the vertical dimension, prospecting for ore at depths in excess of 150 m in productive districts.Essential to this task is an understanding of the Precambrian volcanogenic ore deposit model. The deposits generally have .a tendency to be associated with the terminal phases of felsic volcanism, and to be located along certain time-stratigraphic horizons, marked by the products of volcanic exhalation. The significant massive sulphide deposits are discrete entities, ranging from the top 5% of deposits greater than 45 million tonnes in size, with a surface area of 0.30 km2, to median-sized deposits greater than 1.2 million tonnes in size with a surface area of 0.02 km2. These significant economic ore deposits range in value from $5.5 billion for the top 5% of deposits to $125 million for median-sized deposits. In terms of their frequency of occurrence, the former group has a 4% distribution and the median-sized deposits have a 15% distribution.An historical review of many of the principal Precambrian mining districts, such as Noranda and Flin Flon, shows that major tonnages are usually discovered during the initial phase of application of each new geotechnical search system, until carried to its ultimate limit of effective depth penetration. With the exception of the Noranda district, the mean depth of ore discovery in the other districts is still generally confined to within 50 m of surface.Targeting deep ore is difficult. One effective prospecting method is the detection of fracture-controlled mercury leakage haloes in outcrop (or core) above and peripheral to blind deposits. This technique has proved to be a useful pathfinder, and focuses attention on deposits buried at depths in excess of 700 m in some instances. Down-hole EM systems also promise to be effective in locating deposits previously bypassed by drilling. In addition, trend surface analysis programs of trace element geochemistry should be used as an aid to targeting ore by directing exploratory drilling along the plane of ore-hosting stratigraphy.By definition, mining districts have a proven ""favourability"" for the occurrence of ore. Discovery probabilities in these districts will be considerably enhanced if future search efforts are concentrated below a depth of 150 m, and more use is made of ""deep"" ore search systems coupled with sound geological reasoning. Deep drilling programs to a depth of800 m should initially be designed to search for the top 25% of deposits greater than 3.3 million tonnes in size, with a surface area of0.05 kmt. :a value of$310 million and a 12% frequency of occurrence; This can be accomplished for an over-all cost approximating $40,000 per drill hole. If the search depth is limited to 400 m, the over-all cost of each drill hole is $20,000, equivalent to expenditures routinely allocated to grassroots exploration drilling in the remote greenstone belts of the Precambrian. Depending on a company's objective, prospecting for deep ore offers a stimulating challange - though risky, it has its rewards."

Jan 1, 1981

By Yi Yang, Mark Zoback

"We report laboratory studies of the time-dependent deformation of core samples from four different formations in the Williston Basin - the Lodgepole formation, the Middle and Lower Bakken formations and Three Forks formation. The laboratory tests reveal varying amounts of viscoplastic deformation in response to applied differential stress. The time-dependent deformation is generally greater in rocks with higher clay and organic content, and can be described by a power-law function. Because the magnitude of the creep strain is linearly proportional to the applied differential stress, we can utilize viscoelastic theory and geophysical logs to estimate the degree to which tectonic stress is affected by viscoplastic stress relaxation. We suggest that viscoplastic stress relaxation results in the Upper and Lower Bakken Formations act as frac barriers during hydraulic fracture stimulation in the Middle Bakken, but the Lodgepole and the Three Forks Formations are not frac barriers.INTRODUCTIONHorizontal drilling and multi-stage hydraulic fracturing in shale reservoirs are critical for successful exploitation of ultra-low permeability shale gas, tight gas and shale oil reservoirs. Characterization of the mechanical properties of the reservoir rocks is essential to understanding the behavior of rocks during drilling and completion. Previous laboratory studies have shown that the timedependent deformation in clay-rich shales can be characterized as linear/viscoelastic deformation (Chang et al., 1997; Hagin and Zoback, 2004a, b; Sone and Zoback, 2013b, 2013c). Sone and Zoback (2013c) showed that laboratory measurements of time-dependent deformation in various gas shale reservoir rocks, and demonstrated that the viscoplastic deformation of these rocks can be characterized by a power-law function. They interpreted the results in the framework of linear viscoelastic theory to quantitatively assess the geomechanical effect of viscous time-dependent deformation over engineering and geological time scales. (Sone and Zoback, 2014) further extended the theory and proposed a viscous relaxation model that can be applied to predict the continuous differential stress magnitude using the geophysical logs. They tested the validity of their model by comparing the stress prediction with the occurrence of drilling induced tensile fractures (DITFs) and the vertical hydraulic fracture penetration observed from microseismicity."

Jan 1, 2015

By M. Ataka

Magnesium alloys are not easy to plastically deform at room temperature and may suffer from edge cracking at high reductions, especially during sheet rolling. In this study, the authors attempted to improve the rollability by the low-temperature hot rolling method, in which the rolling temperature range is lower than that of hot rolling, and also by the edge-heating method, which locally heats sheet edges.

Jan 1, 2006

By Nirmal Weerasekara

Mill liners serve the dual purpose of protecting the shell from wear and transferring the rotary motion of the mill to an effective grinding action. As the liners wear, the efficiency of energy transfer changes, so there is balance between liner profile for wear and for milling efficiency. A tool that can simultaneously predict the evolution of the liner profile and the associated change in milling efficiency should prove most useful in optimal liner design. This paper presents such an approach, based on measured 3D liner profile data informing 3D DEM simulations of charge motion and liner wear modelling.

Jan 1, 2012