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By Alex Luyima, Jaan Kers, Lifeng Zhang

"The pyrolysis of PWBs was investigated by a TG-DTA-MS furnace at 300–1173 K. The kinetics and the control of emitted gas during the pyrolysis of PWBs with and without chemical additives were studied. Moreover, the possibility of controlling the amount of toxic exhaust gases like HBr, C6H6, Br2, Cl2, HCl gas and recovering beneficial gaseous fuels like CH4 and H2 from pyrolysis process is discussed. The MS data for each PWB sample were examined as a function of temperature and particular m/z values could be associated with the mass loss steps in the TG data. The degradation of the organic material was characterized by m/z = 2, 16, 18, 28, 36, 44, 71, 78, 81, and 160. Fe2O3 was the best inhibitor of toxic HBr and C6H6 when compared to Al2O3, CaO Y-zeolite and ZSM-5. Moreover, it had no significant effect on the valuable H2 and CH4 gas evolution. This selective inhibition of toxic gases while maintaining the valuable ones make Fe2O3 the best candidate among the investigated additives in controlling gas emissions from PWB pyrolysis process.IntroductionThe electronic and electric industry is one of the world’s largest and fastest growing manufacturing sectors. As a consequence of this growth, electrical and electronic waste (e-waste), such as computers, washing machines, printers, mobile phones, television sets, stereos, radios, etc., is generated in large quantities around the world. Printed wiring boards (PWBs) are a common component of many electronic and electric systems.[1]. The rapid development and expansion of the electronics industry over the past several decades have led to a dramatic increase in the production of PWBs and a corresponding increase in the amount of waste generated from both production and disposal. The environmental impacts of the treatment and recycling of PWBs waste have become a major concern [1-2]. PWBs are particularly problematic to recycle because of the heterogeneous mix of organic material, metals, and glass fiber [1]."

Jan 1, 2012

By F. K. McKean

THE task of establishing a new corrosion testing laboratory is more difficult than it need be because there is very little information on the subject available in the literature. Many articles describing tests and results may be found, but a wide search will unearth only passing remarks on the different types of equipment that may be selected for accelerated corrosion tests. An article describing some of the apparatus needed in a corrosion laboratory should be of help to those interested in building a new unit or in making additions to an old one. In May of this year, the writer was given the assignment of equipping a laboratory for general corrosion testing, to form a part of the new Physical Metallurgy Research Laboratories of the Department of Mines and Resource~ at Ottawa. With the help of senior members of the staff, along with what could be gathered from other sources, a list of necessary equipment was compiled and a plan for arranging it in the rooms was decided upon. Where possible, the apparatus was constructed in the excellent machine shops at the disposal of this Department, while the rest was placed on order with the manufacturers.

Jan 1, 1945

By S. C. Gouws

"SynopsisSustainable infrastructure development has long been identified as a key enabler for socio-economic growth and poverty reduction in societies globally. Twenty-one years into the young South African democracy, economic prospects are fragile and unemployment statistics are high. According to Trading Economics (2015) the GDP growth rate in South Africa averaged 3.07% from 1993 until 2015.Through the National Development Plan 2030, the government has responded by instituting the Presidential Infrastructure Coordinating Commission (PICC) to direct national growth and drive job creation by effecting a long-term infrastructure investment programme. The Commission is mandated by Cabinet to coordinate, integrate, and accelerate implementation of more than 150 individual social and economic infrastructure plans.In the civil infrastructure development sector, increased urbanization is compelling governments and the public sector to expand safe and reliable public amenities, but the availability of real estate for construction in congested cities is a challenge. Within the mining infrastructure construction industry safe, rapid, and efficient mine extraction strategies are imperative to realize increased production, business hurdle rates, and stakeholder expectations.Asset owners and stakeholders are obliged to consider advanced mechanized underground excavation and support technologies in order to present feasible solutions timeously. From an engineering design, procurement, and construction management (EPCM) perspective tunnelling technology and boring applications have a distinct advantage over conventional excavation techniques. These solutions may enhance commerce and transportation by expanding infrastructure in concentrations of national economic activity, providing crucial linkages with rural areas, between cities, and across international borders.This paper explores the contribution by mechanized tunnelling technology and boring applications applied in conjunction with digital and automation technologies compared with conventional methodologies. The technological expertise, combined with a paradigm shift in delivery of project objectives, will promote economic growth, aid recovery from the economic downturn, and improve social development."

Jan 1, 2015

By J. R. Kiji

The Cerro Matoso S.A. mine and smelter, in the Cordoba lowlands of northwestern Colombia, consist of a dedicated laterite nickel mine, ore blending, drying and an RKEF process to produce high-quality ferronickel. At a project investment of $400M, first production of ferronickel was in September 1982, and in its inaugural year CMSA produced 6,150 tons of contained Ni from a mined ore grade of 3.2% Ni. Initial operational difficulties resulted in a number of furnace run-outs, which impacted ramp up to design ore throughput of 128 dry t/h Since then CMSA has steadily incorporated process improvements and initiatives to take the single line operation to an ore throughput of 175 dry t/h. A second 175 dry t/h line was added in 2001 (investment of US$ 300M) to consolidate CMSA as one of the world's lowest cost Ni producers with an installed annual production capacity of 50-55,000 tons Ni. The most recent addition is commissioning of Phase I of an ore-upgrading project to counteract the effect of declining ore grades. Keywords: Laterite, ferronickel, pyrometallurgy, smelter.

Jan 1, 2004

By Glen C. Reed

"The Avon mica district of Latah County, Idaho, is situated on a heavily forested spur of the Thatuna Range at an average altitude of 4,000 feet. The nearest rail connection is at Avon, a small farming settlement 7 miles to the south. The main supply point is Moscow, Idaho, which is 35 miles by graveled and graded county roads from Avon.Discovery of mica-bearing pegmatites in 1885 was followed in 1888 by exploitation of several outcrop deposits. Although factual data are unavailable, past production appears to have been well in excess of $100,000. Recent production (September 191 to April 1945) amounted to 65,824.78 pounds of trimmed sheet mica and 33,294.17 pounds of punch mica having a total gross value of $434,298.The several properties of the district are variously owned by estates, individuals, and the State. When active, all wore under lease or sublease to individual operators.The deposits are in an area of pre-Cambrian schists adjacent to a small granitic outlier of the Idaho batholith. The pegmatites are nearly concordant in dip and strike to the foliation of the enclosing schists. The more persistent bodies are usually tabular, lenticular, or pegmatite. Individual dikes range in length from 10 feet or less to 300 feet.The recoverable crude mica content of the pegmatites ranges downward from a maximum of 115 pounds per ton of pegmatite mined. Material discarded in rifting and trimming operations further reduces recovery to a maximum of 5 pounds per ton -of pegmatite mined. The average recoverable sheet content of the 'recently operated .deposit is estimated at 2 pounds per ton of pegmatite -mined. Available data indicate that about 21 percent of the district's recent production of trimmed sheet mica has been ""Group A"" material suitable for exacting condenser requirements. A few of the dikes contain local concentrations of beryl.Reserves of the three known major deposits of the district are estimated at about 600 to 1,000 tons of combined ""indicated"" and ""inferred"" crude block mica. One of these deposits is inferred to contain between 150 and 450 tons of beryl.It is believed that those mica reserves are minable only under a cost-market price ratio similar to that established during 1943 and 1944. A small part of the reserves can be ""high-graded"" under the present price structure. Profitable recovery of the beryl would require a market price four to five times that paid in 1944.Preliminary examination of the Avon mica district was made by the Bureau of Mines in the summer and fall of 1942. A study of the Muscovite mine and a brief reconnaissance of the surrounding district led the Bureau to recommend that the district be explored by angle-dozer trenching."

Jul 1, 1946

By Prasenjit Basu

Drilled displacement piles are being increasingly used as foundation elements, particularly in projects requiring fast construction. Different types of drilled displacement (DD) piles are available in practice. DD piles are classified according to the drilling tool design and installation method. The capacity of a DD pile, depending on its type, is between the capacities of geometrically similar nondisplacement and full-displacement piles installed in the same soil profile. This paper provides an overview of the different types of DD piles and their installation techniques and describes three design methods used in practice. It also compares DD pile capacities obtained with these design methods for two different sites.

Jan 1, 2010

By Frederick W. Horton

With large deposits of low-grade molybdenum ore and a latent market for molybdenum, which with development might perhaps equal that for tungsten, the United States has for years made no pro- duction of molybdenum ore worthy of mention. In fact, during the decade previous to 1914, there was no output of molybdenum ore in this country except in 1905, 1906, and 1907, when a few small lots of molybdenite and wulfenite were marketed." To ascertain why this possible source of economic wealth should remain undeveloped, the United States Bureau of Mines undertook an investigation in 1914, with a view of assisting the establishment of a molybdenum industry in this country. A preliminary review of the situation showed the following conditions: Briefly there was a lack of any considerable demand for molyb- denum for the one known use that might consume any large tonnage of it, that is, for the manufacture to certain alloy steels to which molybdenum imparts properties roughly similar to those produced by tungsten. It was at once evident that the market for molybdenum in alloy steels must be developed, or that extensive new uses for the metal must be created, before the demand would be sufficient to war- rant any extensive mining of molybdenum ore. Investigation showed that one of the chief factors in retarding the development of any demand for molybdenum by the alloy-steel trade was that manufacturers who might use, or might investigate the possibilities of using, the metal were kept out of the market by the fear of not being able to obtain steady supplies. On the other hand, those who might be interested in the development of some of the extensive low-grade molybdenite or wulfenite deposits in this country were prevented from doing so by the small visible demand and the fear that any large production would glut the market. Owing to these conditions the mining of molybdenum has in the past been confined almost entirely to small-scale operations on high-grade streaks of molybdenite ore, and the methods of recovery have been limited largely to cobbing and hand picking.

Jan 1, 1916

By G. H. Lind

New South Wales has a successful history of pillar extraction stretching back more than 60 years. Various methods of pillar extraction ranging from the rib pillar methods (such as the Wongawilli system) to the more recent pillar stripping techniques (similar to those used in the USA) are discussed in this paper. These discussions are based on the experiences of the author stemming from a recent research tour of seven underground pillar extraction operations in New South Wales as part of the Coaltech 2020 collaborative research initiative. Some operational issues of each site visited are presented before some general comments pertaining to the overall success of pillar extraction in New South Wales are discussed. Generally pillar extraction in New South Wales is on the decline in favour of longwalling. However, the pillar extraction that is conducted is done so along specific guidelines to ensure their success, and these are also discussed.

Jan 1, 2002

By N. Simpson

Low carbon 11.5% chromium stainless steels are finding increasing use in industry as square or rectangular tubing material for the construction of structures by welding. During processing, resistively welded circular pipes are bent into square or rectangular shapes. During this process longitudinal cracks can sometimes develop atone of the inner corners of the section. An investigation has shown that the processing of round into square tubing with very sharp corners can cause excessive cold working at the inner corners of the squared tube. This, together with the high tensile residual stresses and a susceptible microstructure due to the presence of grain boundary carbides, can result in brittle cleavage cracking. Measures that can be used to reduce the problem are described.

Jan 1, 2003

By Brandon Fryman, Josh Hoffman, Rhys Baker

A post-detonation debris collection project was led in conjunction with a large ammonium nitrate(AN) railcar detonation conducted by the Department of Homeland Security-Transportation Security Administration, Department of Defense-Combating Terrorism Technical Support Office, Sandia National Laboratories, and the U.S. Army Dugway Proving Grounds. This important work will aid in underpinning algorithms used in a Quantitative Risk Assessment (QRA) tool. The test also provided valuable data about the effects and consequences following an AN detonation. The test took place at the Utah Dugway Proving Grounds on April 27, 2018 and the debris collection was conducted the following two weeks with an average of 20 persons per day and an approximate total of 1,400 manhours. A paper was presented at the 2019 ISEE Conference on the collection efforts, challenges, and lessons learned. A complete data analysis effort was completed on the test data in 2019 that resulted in updates to the QRA Railcar Potential Explosion Site (PES)model and AN engine. The analysis included an assessment of the debris data resulting from the Derailed test. This paper is meant to serve as a summary of the analysis effort and findings and as an update to the previously presented lessons learned from the debris collection and analysis effort.

By Yeonuk Choi, Gus Van Weert

"In regular CIL circuits, activated carbon is used for two purposes: avoiding solid/liquid separation after cyanide leaching, and minimizing gold losses in the tails. The carbon distribution and gold profiles in the successive CIL stages are operating variables, not objectives. When the CIL feed contains a preg robbing constituent however, such as native carbon, there will be competition for gold cyanide and this conflicts with minimizing of losses of gold to CIL tails. This paper examines some of the limitations of activated carbon in CIL circuits handling preg robbing Carlin Trend ores.INTRODUCTION Carbon-In-Leach (CIL) has been a great success treating regular gold ores, but the technology is still challenged by preg robbing feedstocks. Little information is available in the gold milling literature on CIL gold extraction from “free” milling gold ores which are preg robbing, or on autoclave discharge (POX’ed) slurries of double refractory ores. Neither feedstock is readily available for experimentation. No literature reference could be found describing deliberate modifications to CIL operations or CIL circuits due to the presence of two types of carbon: “native” and activated. There is some literature on the gold cyanide adsorption activity of native carbons (Schmitz, Duyvesteyn, Johnson, Enloe & McMullen, 2001). Various tests have been devised to measure this activity, commensurate with CIP and CIL practices (Tretbar, Arehart & Graves). In this paper, the term “native” carbon indicates (severely) preg robbing carbonaceous materials found in gold ores. There is considerable literature on the gold cyanide adsorption activity of man-made “activated carbons”. Various tests have been devised to measure this activity, commensurate with CIP and CIL practices. These tests are comparative, i.e. results relate to a standard carbon and depend on the test methodology and carbon history. The test results are equilibrium oriented, hence of limited value to CIL circuit designers or plant operators handling preg robbing solids; in CIL circuits most carbons are not loaded to capacity. Information on gold cyanide adsorption and desorption kinetics might be more relevant and that is one subject explored in this paper."

Jan 1, 2012

By S. K. Oraee

Most management decisions at all levels of the organization are as directly or indirectly depends on the circumstance of future. With regard to predict the future events in the process of decision-making plays a main role, therefore, forecasting is very important for every organizations and institutions. There is a variety of methods to predict time series. In general, these techniques can be divided as following: statistical, artificial intelligence and analytical techniques. Two of the most common methods for time series prediction is autoregressive integrated moving average (ARIMA) and artificial neural network (ANN) methods, these methods are the subset of statistical and artificial intelligence techniques respectively. In this paper, a hybrid model of ARIMA and ANN models are employed to predict the number of fatal injuries in the USA underground coal mines. This research showed the result of hybrid model is better than split model.

Jan 1, 2011

By N. E. Hanna

To be approved for use in underground coal mines in the United States, explosives and blasting devices must pass certain safety tests prescribed by the Federal Bureau of Mines. These tests are described in Schedule 1-G4/ (explosives) and Schedule 26A5/ (blasting devices). An explosive or blasting device that passes the appropriate tests is placed on the active permissible list. As this list is subject to continuous revision, it has been the practice of the Bureau of Mines to publish periodically the names of explosives and blasting devices that have been added to the active list, as well as those that have been transferred to the inactive list; changes in brand names also are reported. The present circular gives all explosives and blasting devices on the active permissible list as of December 31, 1957, and shows all changes, additions, and transfers in that list between December 31, 1951,6/ and December 31, 1957.

Jan 1, 1958

By Mingming Zhang, Marshall S. Coe, Marcelo W. Andrade

To supply iron units and flux burden in blast furnaces, sinter basicity is one of the vital parameters for sinter plants. The sinter basicity also plays an important role in sinter quality since it imparts the formation of different mineral phases in sinter. Pot-grate sintering tests were carried out with low and high basicity to investigate the effects of sinter basicity on sinter mineralogy, properties and productivity. It was found that with an increase in sinter basicity, both sinter productivity and reducibility (RI) increased. Tumbler index (TI) and low temperature degradation index (LTD) of high basicity sinter were comparable to low basicity sinter. Softening and melting tests showed that sinter with 3.5 C/S basicity had slightly higher softening temperature comparing to lower basicity sinter with C/S 2.6, acid and fluxed pellets. XRD analyses confirmed the formation of silico-ferrite of calcium and alumina (SFCA) and calcium ferrite (CF) in the tested sinter samples.

Jan 1, 2015

By Linlin Tong, Xiangling Song, Guobao Chen, Zhenan Jin, Hongying Yang

Biooxidation of a high arsenic-bearing refractory gold ore was investigated to determine the arsenic removal efficiency by the cultured bacteria and to examine the effect of biological pretreatment on subsequent gold cyanidation. The biooxidation pretreatment process utilizes the ability of adapted acidophilic bacteria to oxidize pyrite and arsenopyrite and release the encapsulated gold. The released gold can be efficiently extracted by the subsequent cyanidation process. The biooxidation experiments were conducted with cultured bacteria using various sizes of agitation tanks. Leaching results showed that over 96.26 % arsenic extraction could be obtained from this ore after 6 days of bioleaching with continuous stirred tank reactor (CSTR). Gold extraction during the cyanidation process was increased from 29.35% to 96.71% after biological pretreatment. The content of arsenic in the biooxidation residue was reduced to below 0.3%. The transformation process of As was considered as [AsS]2- ? As (?) ? As (?) during the biological pretreatment.

Jan 1, 2014

By Sushil Bhandari, Amit Bhandari

Drilling and Blasting are core operations in a mine. They impact all the downstream operations and their costs. Digital technologies exist for optimizing both drilling and blasting for many years. However, these technologies have largely been non-integrated and non-real time. This gap results in sub-optimal drilling and blasting operations. Also traditionally focus has been on optimizing individual areas (drilling or blasting and subsequent subsystems). Industry has largely lacked real time or near real time integration available to the user in the field and in the office. In this paper, a case study is presented of a large global cement company using a cloud and mobile based platform across 17 of their mines consistently over a large number of users over a period of over two years. The use of a blast platform is detailed which include blast designs, blast data collection and the trends in terms of results. On the drilling side, this paper describes the ability to capture drill logs, plod reports etc. Also actual drilling information in the field using a mobile device and its real time synchronization with a blast designer to provide visibility of expected fragmentation and vibration levels based on the drilling done. Key parameters such as hole ID, design depth, actual depth, hole status, designed and actual charge (length and weight), designed and actual stemming length are captured. The case study also highlights the challenges in technology adoption and implementation in mining in drilling and blasting. Making drill and blast results predictable should be the desired direction. Also digital technology tool adoption has been seen at the biggest miners – not so much in mid-sized miners or drill and blast contractors. Benefits of this platform on the safety side are highlighted including predictions on safety parameters and appropriate alerts if blast safety parameter / clearance zones are not met. The safety parameters are made available visually to the operator using maps and / or on drone images. Future possible improvements in the digital technology platform at the site are also highlighted including greater possible automation.

By M. Dupuis

It has been previously demonstrated [1,2] that using selective collector bar rodding has a big impact on the uniformity of the current density at the top surface of the cathode block and hence on the intensity of the horizontal current in the metal pad, The present study investigates the impact of using selective collector bar rodding on the MHD stability of a 500 kA aluminium electrolysis cell, For this purpose the recently developed MHD package for the aluminium reduction cell time dependent behavior is used.

Jan 1, 2005

By George Espey, George Sachs, G. B. Kasik

IT has been reported frequently that the hardness and strength vary over the cross section of cold-worked, particularly cold-drawn, material. Brass rod and wire usually have been found to possess a maximum strength and hardness near the surface.1,2 According to Sachs,' the center fiber has about the same strength as a wire stretched by the same amount in a tensile-test machine, the strength increasing toward the surface (Fig. I). These differences are particularly large for wire given a small reduction on drawing through a die with a wide opening. However, with increasing reduction and hardness, a tendency to form a thin soft surface skin becomes apparent. On the contrary, copper wire has usually been found to possess a soft surface skin3-5 and it has been reported by Harris3 that during the cold-drawing of hot-rolled wire the surface layer becomes increasingly softer than the core, while the layer of maximum strength moves toward the core, it being found near the surface at first. The increase of strength and hardness from the core to the skin is readily explained by the observation that, in addition to the stretching, the layers of a rod or wire are sheared more the closer they are to the surface.1,6-8 However, the presence of a soft surface layer can be attributed only to an annealing effect. The source of such a softening might be the extremely high temperature that originates from the friction between

Jan 1, 1942

By G. B. Kasik, George Sachs, George Espey

IT has been reported frequently that the hardness and strength vary over the cross section of cold-worked, particularly cold-drawn, material. Brass rod and wire usually have been found to possess a maximum strength and hardness near the surface.1,2 According to Sachs,' the center fiber has about the same strength as a wire stretched by the same amount in a tensile-test machine, the strength increasing toward the surface (Fig. I). These differences are particularly large for wire given a small reduction on drawing through a die with a wide opening. However, with increasing reduction and hardness, a tendency to form a thin soft surface skin becomes apparent. On the contrary, copper wire has usually been found to possess a soft surface skin3-5 and it has been reported by Harris3 that during the cold-drawing of hot-rolled wire the surface layer becomes increasingly softer than the core, while the layer of maximum strength moves toward the core, it being found near the surface at first. The increase of strength and hardness from the core to the skin is readily explained by the observation that, in addition to the stretching, the layers of a rod or wire are sheared more the closer they are to the surface.1,6-8 However, the presence of a soft surface layer can be attributed only to an annealing effect. The source of such a softening might be the extremely high temperature that originates from the friction between

Jan 1, 1942

By Barry A. Hillman

The rapid evolution of computer and field sensor technology is now providing the ability to integrate mine and office operations. Digital maps and mine plans as well as CAD and GIS can be transferred to ruggedized field computers for development of real-time mine surveys and real-time GPS machine navigation and monitoring. Surveyors can insure that their surveys are accurate before returning to the office. Engineers and surveyors are also able to upload field computer-based surveys to mine planning software and directly to mine equipment including shovels, drills, and dozers providing the operator of the equipment with a real-time view of their work space. Production information can be transmitted through dispatch and/or centralized mine servers to update mine plans with mining progress and production data. Static mine models then become a dynamic element of operations, providing greater use of information that emphasizes the spatial aspects of the mine by providing real-time maps, productivity charts, and graphs. This information can be disseminated through various mine communication systems to provide operators and management with real-time feedback as well as daily and weekly reports. Integrated systems now being used in extensive trials are reporting productivity increases of 4 -7% or more thereby providing rapid payback to the mine.

Jan 1, 1998