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By C. H. Lee, K. Adham, D. Lemieux, J. P. Mai, A. M. S. Hussein, S. Francey

Copper concentrates contain an increasing amount of arsenic, as the older sources of cleaner ores are depleted. At the same time, the market-determined price penalties on arsenic rich concentrates are rising due to limited arsenic treatment capacity at smelters and increasingly stringent environmental emissions limits, necessitating arsenic removal from the copper concentrates. Heating the concentrate to about 700°C can remove significant amounts of arsenic (as elemental and/or sulfide); however, it is important to achieve that removal economically and with due consideration to post-roasting arsenic (toxic waste) treatment. A comparison is made among different roasting options (kilns, multi-hearths and fluid beds) to qualify their potential application to arsenic roasting of copper concentrates. Both direct and indirect methods of heating as well as inert, air and oxygen atmosphere options are considered. Technology comparisons are made with respect to the roaster’s operation, its off-gas treatment and arsenic stabilization. INTRODUCTION In the last twenty years, the arsenic content in globally produced copper concentrates have risen steadily due to the depletion of cleaner ores and the increase in complex concentrate production. Smelter contracts typically limit arsenic to less than 0.5wt%, with a penalty paid per unit of additional arsenic and other contaminants such as antimony. While penalties can vary, they can be on the order of $70/dry metric tonne of concentrate per 1% of arsenic. Strategies used by miners to avoid the price penalties have been to blend clean and complex concentrates, and to remove arsenic from complex concentrates to achieve smelter limits. Arsenic can be removed from copper concentrates by the heat-induced decomposition of the predominant enargite mineral (Cu3AsS4) at ~700°C. Roasting at such elevated temperature is a commercially proven option, but still suffers from process, cost and environmental challenges. After roasting, the released arsenic sulfide fumes can be separated from most of the entrained concentrate dust in cyclones. Then, the As2S3 laden off-gas can be oxidized to generate a still volatile oxide (As2O3), which can be further separated from the residual concentrate dust in a hot electrostatic separator. Next, the off-gas can be cooled with air or water, to either deposit the arsenic oxide in a dry or dissolved state. Dissolved arsenic acid can be oxidized to As(V) and reacted with iron to yield a stabilized ferrihydrite precipitate or scorodite that can be safely disposed. In the case of dry arsenic trioxide, it can be mixed with reactants (e.g. iron) and fluxes before thermal stabilization in a glass matrix, thus eliminating the need for costly oxidation.

Jan 1, 2019

By A. Mazhary, T. Huff

Sensor-based ore sorting technology is a growing area of interest due to lower-grade ore deposits and higher costs of processing, among other reasons. Among the sensors currently utilized in the particle sorting industry, X-Ray Fluorescence (XRF), as the only sensor with elemental analysis capabilities, has always attracted more attention. Currently, the bench-scale amenability tests for this sensor are performed using hand-held XRF analysers. However, this testing method overestimates the performance of the XRF sorter, and therefore, the results from these tests can be misleading and are often mispresented. The work presented here was conducted on a copper mine and investigates how the sensor’s sensitivity to copper deteriorates under different testing methods. This work compares and correlates the results of an Olympus hand-held XRF analyser, static, and dynamic sorter responses with the actual grades of the rocks. The results confirmed that, the sorter response was extremely prone to blind spots. Furthermore, the results demonstrated that although the static sorter’s responses were comparable in terms of rock identification to those of the hand-held XRF analyzer and assays, the accuracy of the dynamic sorter response deteriorated both as a function of grade of the rocks as well as the potential for blind spots. INTRODUCTION Sensor-based sorting technology has been gaining increasing attention even by larger mining corporations as ore grades decrease, deposits get deeper and therefore cost of mining and processing increases. There are various types of sensors that are currently being used in the particle sorting industry such as X-Ray Transmission (XRT), Color, Electromagnetic (EM), Near-Infrared (NIR) and others. However, none of the sensors are capable of identifying and quantifying particles by the elemental content, except for X-Ray Fluorescence (XRF). XRF is a non-destructive, surficial analytical technique used to measure elemental composition of materials. X-ray fluorescence happens when a secondary x-ray (fluorescence) is released after a sample is bombarded by a primary x-ray source. From a sorting perspective, the most common and expected issues that are associated with XRF sorting are lower throughputs compared to other sensors due to particle presentation limitation as well as the need to wash the material before introducing to the sorter. However, one important issue that is mostly neglected is how the amenability tests are performed and how realistic the obtained results are. Current amenability test procedure utilises a handheld XRF analyser (such as an Olympus InnovX, as used in this work) on multiple, generally 4, sides of the rock and uses the average measured grade as a criterion for separation. While this is a widely accepted technique, it fails to consider some important factors such as exposure time and the distance between the sensor and the particle. These factors can significantly affect the sorting outcome.

Jan 1, 2019

By C. Laughton

Construction of a Deep Underground Science and Engineering Laboratory(DUSEL) is proposed under the auspices of the US National Science Foundation(NSF). DUSEL will provide scientists and engineers with a research facility capable of supporting a broad spectrum of fundamental and applied research deep in the earth’s crust. Research partners are physicists, biologists and geoscientists. DUSEL research calls for the construction of a network of shafts, tunnels and caverns that will provide laboratory facilities at depths of up to approximately 2 kilometers. The Project is still in the planning stages but, the initial experimental program is taking shape and conceptual designs have already been developed at two hard rock mine sites. This paper discusses the overall program and key engineering tasks being developed to support the construction of deep, large-span caverns. These caverns will house a new generation of physics experiments. As currently scoped, the experiments call for the excavation of permanent caverns with spans of up to 60 meters, sited at depths in excess of a kilometer.

Jan 1, 2007

By C. Hosten, K. V. S. Sastry, D. J. Kawulok-Englund

Introduction Since the last decade the iron ore processing industry has undergone drastic changes from supplying screened and natural ores to manufacturing tailored concentrates and pellets. Increased need for the beneficiation of lower grade iron ore deposits and the increased demand for higher grade concentrates necessitate finer grinding of iron ores before concentration. The normal filtration stations used in the past are experiencing difficulties in dewatering the finely ground concentrates to moisture levels acceptable for balling. In addition to finer grinding, applications of complex beneficiation techniques has decreased the filterability of the concentrates and create problems in filtration of iron ore concentrates. An overview of the filtration literature indicates there are few research reports on the dewatering of iron ore concentrate slurries. There exists a need to understand the principles and mechanisms involved in the filtration of iron ore concentrate slurries with a goal of developing more efficient filtration techniques. This paper presents the results from the first phase of our research program that included the development of a reproducible benchscale filtration technique and the investigation of the filtration behavior of eight iron ore concentrates.

Jan 10, 1983

By J. M. Wempen

Booster fans, large underground fans, can increase the volumetric efficiency of ventilation systems by helping to balance the pressure and quantity distribution throughout a mine, reducing leakage and reducing the total power requirement. However, in ventilation systems that use booster fans there is a potential for system recirculation, the leakage of return air to intake air, and also for localized recirculation near the fan through the bulkhead and airlock doors. Air that is recirculated locally decreases the system efficiency because the quantity of air flow through the fan increases without increasing the airflow throughout the system. To understand the detailed flow characteristics of a ventilation system with a booster fan, two-dimensional computational fluid dynamics (CFD) models were developed using the software Ansys-FLUENT. Though two-dimensional models do not represent the full complexity of the flow dynamics, they do provide a good representation of the flow characteristics and they allow for a qualitative analysis of how the flow dynamics are affected by the system characteristics. The CFD models were used to evaluate how the number of booster fans, the booster fan placement, the location and geometry of the fan installation and the construction of the airlock system affect the flow characteristics and the localized efficiency of the ventilation system.

Feb 27, 2013

By Peter Metcalfe

"Wireless communication in the mineral processing environment is not as simple as it is in the home or office environment. The correct design of a wireless network in the mineral processing environment can offer a more flexible and lower cost installation than the transitional fiber networks. However with the flexibility of a wireless solution, also comes some limitations. By reviewing the plant requirements along with weighting the wireless benefits and limitations it is possible to design a network that combines the robustness of a wired solution with the mobility of a wireless solution. This paper addresses some wireless design considerations and it looks at some real life examples in the following areas: •,Meshed wireless network for high levels of redundancy •,Wireless instruments (such as HART, Modbus and others) •,Portable devices for mobile operators •,Network monitoring for plant personnel (it’s no longer just for IT people) INTRODUCTION Typical networks used in the mineral processing environment consist of a fiber network infrastructure with industrial switches used to connect the network devices. These fiber networks can be redundant or put into a ring topologies to offer a higher level of availability. Fiber networks have the benefits of: •,Immunity to noise from power and grounding issues •,Ability to span long distances (2km for multimode fiber and 20km for single mode fiber) •,Maintainable “off-the-shelf” technology Fiber networks however have some drawbacks, such as: •,Relativity high initial installation cost for cable trays, poles, trenches and pulling and termination of cable. •,Fixed geographic topology, adding future fiber drops may be challenging and expensive. •,Mobile users are not considered. Integrating a wireless network with a fiber network can offer the best of two worlds, a reliable high speed backbone for mission critical activities and a wireless network for remote applications and mobile users."

Jan 1, 2014

By Paul Worsey, Larry Frost, Braden Lusk, Seok Bin Lim

For certification of blast resistant windows, current tests consist of arena tests or large air gun tests. Arena tests involve the detonation of more than 1000 pounds of explosives with windows placed in the range of hundreds of feet. The result of an arena test is a loading on a window consistent with an expected industrial or terrorist blast. Due to the nature of this type of test, only a limited number of facilities are available and operational costs can be extremely high. Air gun tests involve the use of compressed air and a failing diaphragm fired through a large tube. Although this test is more cost effective and easier to administer with lower environmental impacts, it is not an explosive loading and does not create a negative phase on the tail of the pressure pulse. Simply using a small charge in close proximity to the window is not a viable option either. The pressure peak can be reached using this method, but the duration of the pressure pulse is such that the positive phase impulse is on the order of ten times less than that for an arena test.

Jan 1, 2006

By Daniel Brutto

"Environmental considerations are a key driver within marine mining consenting processes across different national and international legislative regimes and are critical in shaping the global public perception of the industry. As a result, it is vital that mining companies seeking to operate within marine environments establish a robust understanding of the sensitivities of the seabed environments in which they are active, the impacts of their activities and the ability of the environment to recover from these impacts. The significant risks of failing to do so include an inability to either obtain or maintain operating permits. At the individual project level, the environmental effects of any given development project are typically defined within the scope of an Environmental Impact Assessment (EIA). For well-established industries operating in well-studied environments this approach typically works well. However, where emerging industries or existing industries that are operating within new environments are concerned, there may be significant knowledge gaps pertaining to our understanding of how specific anthropogenic practices or activities interact with the marine environment. These knowledge gaps can cause significant uncertainties pertaining to the likely significant effects of a project. Such uncertainties may result in barriers to industry and economic progress, increased consenting risks, increased project costs to be borne by individual project developers through the acquisition of additional environmental data during the pre-consent or post-consent project phases, project delays and/or significant increases in environmental monitoring burdens with corresponding increases in project costs."

Sep 1, 2014

By D Craw, J Youngson

Recent exploration for mesothermal gold deposits in the Otago Schist has focussed largely on extensions of, or analogies to, the reverse fault-hosted Hyde-Macraes Shear Zone deposit. Abundant normal fault-hosted mesothermal and epithermal vein deposits in the Otago Schist have attracted less attention, largely because they have limited lateral extent and steeper dips. Northwest-striking normal fault-hosted vein sets near Barewood and Hindon in east Otago crosscut schist foliation on the Barewood-Hindon plateau at a high angle along a combined strike length in excess of 20 kilometres. The trend of the vein sets is not linear, but rather contains several right lateral steps. Almost all veins dip steeply to the northeast. Angular discordance between schist foliation and the plateau surface along the trend increases from near zero at the northwest end of the veins to about 30¦ at the southeast end. Crude formation depth estimates decrease from about 7.5 km at the Barewood end of the zone to

Jan 1, 2002

By H. Tomlinson

"PURPOSE OF REPORTThe purpose of this report, which is the third of a. series on the coal mines of the Western States, is to give the findings of a study of the causes and methods of prevention of accidents from falls of root and coal in the mines of Lincoln County, Wyo. The three mines covered in this report, referred to as A. B. and C, account- for 9 per cent of the coal production in the county and nearly 9 per cent of the State's total production. For comparative purposes some statistical data are presented bearing upon the relation of injuries to their causes, to tonnage produced, to men employed, to days worked, and to days lost as the result of injuries.FATALITIES IN WYOMINGTo show the necessity for this study, Table 1 given the fatalities that occurred during 1928 in the bituminous—coal mines of the United States, of the State of Wyoming of Lincoln County, and in Mines A, B, and C, followed by a brief description of the Kemmerer coal dis-trict, its coal beds and immediate roof, thickness of cover, dip of coal beds, methods of mining timbering for roof support, roof testing, and supervision. All of these factors must be considered in any plan outlined to prevent accidents resulting from falls of roof and coal.ACKNOWLEDGMENTAcknowledgment is made to the officials of the operating companies for their cooperation and assistance during the study and collection of data to complete this report.GENERAL INFORMATIONLocation and Ownership The mines included in this report are within 18 miles north and south of Kemmerer, Lincoln County, Wyo. (fig. 1), and are owned and operated by various coal companies to supply the domestic, smelter and railroad markets. They are severed by branch lines of the Oregon Shorty Line Railroad Coal production and men employed underground in the three mines are indicated in essential detail in Table 2."

Sep 1, 1932

By Mohammad Eslami

The Tabriz-Urmiyeh Highway shortens the distance of north-western cities of Iran by about 130 km, resulting in improved access and efficient transit between Iran and Europe through Turkey. The highway crosses the Urmiyeh Lake, an inland lake surrounded by mountains. Due to the circulation of salt-water in the lake and the necessity to continue shipping between adjacent ports, a waterway should be kept open. Consequently, a bridge was built to provide access of marine traffic. A causeway bridge had a length of 1,260 m, comprising of 19 spans. In construction of the bridge, more than 400 piles having a total length of 32 km have been driven. For design of piles different methods have been used such as static analysis, dynamic testing, and correlations to in situ tests, such as cone penetration test (CPT). This paper presents construction of bridge substructure, full-scale piling tests, and methods of analysis used in the evaluation of the deep foundation capacity. The presentation includes an assessment of four current direct CPT and one CPTu methods to calculate the bearing capacity of the piles. It was found that the CPTu and dynamic testing are two suitable tools for rapid and optimum pile design and verification.

Jan 1, 2010

By D. Brand

"The risk management objective of the AMIRA Code of Practice for Metal Accounting has seldom been systematically investigated in the literature up to the authors’ knowledge. Risk is defined in the Australian Standard on Risk Management (AS/NZS 4360:2004), as “the chance of something happening that will have an impact on objectives”. The simplified economic analysis performed in this paper has lead to define “something happening” as measurement non-representativity and “impact on objectives” as NSR loss from the optimal NSR. This has pinpointed a missing link being the establishment of a relation between NSR in flotation plants and measurement representativity. The proposed framework, referred to as the total cost of representativity, answers the previously unanswered question of how much accuracy/reproducibility is fit for purpose in a given flotation plant. Authors readily acknowledge that it is way easier to assess the cost of accuracy/reproducibility than the cost of inaccuracy/irreproducibility. However, this exercise not only answers previously unanswered questions but also establishes an essential link with operational excellence. This paper exposes why such operational excellence could neither be attained nor proved without a state of the art metal accounting system. This should impact not only how metal accounting systems are audited/designed/refactored, but also how flotation plants are designed.IntroductionBecause representative metal accounting is a vital source of information for the financial accounts of a mining/metallurgical company, the need for a code on metal accounting was recognized in 2001 and a team was formed in 2003, under the sponsorship of several major mining houses, to produce such a code. Table 1 exposes the two main objectives of this AMIRA Code of Practice for Metal Accounting."

Jan 1, 2017

By C. Vipulanandan, M. Dawood, Dongmei Pan

"With the aging infrastructure, there is a need to maintain and extend the service life of steel structures in general and steel piles in particular. Steel piles support not only vertical loads but also dynamic horizontal loads in onshore and offshore applications. In order to select the appropriate methods to repair corroded steel piles used in onshore and offshore application, corrosion mechanisms were investigated with the rate of corrosion in various environments. The corrosion rate of steel in soil, water and soil-water interface varied from 2 to 500 µm/year. Based on literature review and analyses, the repair methods can be broadly characterized as protective coating, electro-chemical methods, wrapping and encasement and partial replacement of steel. Also, methods to evaluate the repair materials and the repair configuration have been documented.IntroductionOne of the biggest challenges facing the aging infrastructure is the materials loss and deterioration due to corrosion. Many studies indicate that in the US alone, costs due to corrosion loss is more than $276 billion annually (Michiel et al., 2010). Corrosion is the major cause of deterioration of steel structures and components (MNC, 2005). Load bearing steel piles are used as foundations for various types of structures and hence corrosion is very much influenced by the environment such as soil, water and soil-water interface. Corrosion of steel pile foundations may result in reduced capacity in the axial and lateral directions. Hence, understanding the rate of pile corrosion is essential to select the appropriate repair methods to avoid excessive deflection and failure (Decker et al. 2008).To prevent the deterioration mechanisms that attack a pile, it is fundamental both to identify and understand the deterioration mechanism that has been the cause of damage. Understanding the deterioration mechanism allows the engineer to design a repair that will combat this type of damage. It is widely recognized that the corrosion of carbon steel in soil, water and soil-water interface proceeds according to the following simplified anodic reaction and cathodic reactions in the presence of oxygen (Decker et al. 2008)."

Jan 1, 2017

By Göran Bäckblom

The Swedish mining companies LKAB and Boliden, the equipment supplier Atlas Copco, the general contractor NCC and the specialist company Reflex joined forces in 2005 to advance the field of rock technology for the purpose of mining and underground construction. The creation of the company Rock Tech Centre is part of the strategy developed by the Swedish mining industry to strengthen co-operation with industry, academia and society. This paper outlines the current R&D strategies developed for the industry in general, discusses what focus areas are selected and provides some details on the current RTC project portfolio, especially faster and better drifting.

May 1, 2006

By Sterling J. Anderson

Through the use of nondestructive testing techniques, the Bureau of Mines is pursuing a goal of improving the efficiency of the rock excava-tion process. Toward this end, 44 laboratory tests were conducted to identify a practical method of monitoring fracture development in rock, as caused by an excavation tool. An acoustic emission CAE) transducer was used to monitor the test samples as they were loaded. The signal from this instrument was recorded in real time along with the radial and axial loads generated by the fracturing device. Through the review of these signals on a common-time base, it was possible to see the relationship between the developing fracture and the loading conditions. As a part of the posttesting investigations, samples that were pletely fractured were sawn and ground to expose the fractures. examination of these samples allowed approximations to be made incom-Visual of the total surface created. Surface area approximations were also made for the completely fractured samples. Quantitative analyses· of the AE signals were conducted for comparisons with the calculated surface areas.

Jan 1, 1987

By Donald Thompson, Jessie Bonner, Ileana Tibuleac

Predicting ground motion from complicated mining explosions is important for mines developing blasting programs in regions where vibrations must be kept below certain levels. Additionally, predicting ground motion from explosions in complex 3D media is important for source size estimation for nuclear treaty monitoring. Both problems have been addressed under the development of a new series of programs including: 1) Generalized Fourier Methods to generate synthetic seismograms (Green’s functions) in 3D media for a moment tensor source implementation and 2) MineSeis3D, a program that simulates seismograms for delay-fired mining explosions with a linear relationship between signals from small size individual shots. To test the programs, three-component seismic recordings of three production shots at an iron mine in northern Minnesota were compared to synthetic waveforms in 3D media. Comparison of the observed and synthetic waveforms shows promising results. The shape and arrival times of the normalized synthetic and observed waveforms are similar for most of the stations. The synthetic and observed waveform amplitude fit is best for the vertical components in the mean 3D model but not as promising for the transversal components. The observed effect of spall on the waveform spectra was weak in the case of fragmentation delay-fired mining explosions. Commercial applications of the code could provide data needed for designing explosions that do not exceed ground vibration requirements posed by the United States Department of Interior, Office of Surface Mining.

Jan 1, 2005

By H. Ipek

Industrial grinding machines used in the mineral processing industries are mostly of the tumbling mill type. These mills exist in various types: ball, rod, pebble, autogenous, and semi-autogenous. Balls and rods are traditionally media shapes used in the tumbling mills. In resent years, as an alternative to balls, grinding charges with various shapes are being used. Cylpebs are slightly tapered cylindrical grinding charges with length equaling diameter, and all the edges being radiused. Cylpebs of equal diameter and length have 50% greater surface area and 45% greater weight than balls of the same material. In addition, they have 9% higher bulk density than steel balls, or 12% higher bulk density than cast balls. An important advantage of cylpebs over balls is that cylpebs produce narrower granulometric distribution due to their shapes. However, some discrepancies were found in the literature regarding the milling performance of cylpebs in comparison with balls (Chi, 2004). In recent studies, Chi (2004) has provided detailed information on cylpebs and has compared these to balls in relation to media mass, size distribution, surface area, and input specific energy. Ipek (2006) has investigated the effects of cylpebs and balls with equal mass and surface area on the breakage rate of quartz, using cylpebs and balls separately. Similarly, Lameck and Moys (2006) have investigated the effects of balls and worn balls on breakage rate of material using worn balls as grinding environment. However, no study has attempted to investigate the effects of grinding environment other than balls on the brekage distribution. As indicated by Prasher (1987), the breakage distribution function is independent of the following variables in ball mills: hold-up (Mika et al., 1967; Kelsall et al. 1969), mill speed and ball load (Herbst and Fuerstenau, 1972), media load and ball density (Kelsall et al., 1973), mill diameter (Malghan and Fuerstenau, 1976), and powder charge (Shoji et al. 1980). The aim of the present paper is to compare the effects of cylpebs and balls on the breakage distribution function of quartz with respect to same mass and same surface area. BACKGROUND Comminution as a rate process is called kinetic approach. Studies on the kinetic approach are reviewed by Oner (2001). Oner states that grinding kinetics are based on studies by Kolmogorov in 1941 and that Robert (1950) is the first to suggest this approach. Later, Melzak, Loeveday, and Reid have improved the grinding kinetics equation; and, Austin and Lynch have conducted two basic studies on the analytical solutions of these equations. Considering the results of studies comparing the size reduction mechanisms, it has been accepted that breakage constitutes of two operations. These two basic operations, first defined by Epstein (1948), are those of selection of material for breakage and the distribution of breakage material to particle sizes smaller than the initial size (Lynch, 1977). Epstein defined the two operations as: ? Pn(y), the probability of breakage of a particle size in the nth step of the breakage process. ? F(x,y), the cumulative distributions by weight of particles of size x<y arising from the breakage of a unit mass of a size y. Probability of breakage is called a selection or a breakage-rate function (Si). Characteristics size distribution after breakage is called a breakage distribution or appearance function (Bi,j). Due to the difficulties in representing particle size distributions mathematically and constantly, the batch equation based on particle size fraction is suggested. Thus, as is the case in breakage distribution and specific rate of breakage, the breakage parameters were defined by batch grinding experiments conducted in laboratories (Oner, 2001). When effective breakage occurs in the mill, the breakage of material with single feed size fraction usually fits first order grinding kinetics and the specific rate of breakage values can be calculated through the slope of semi-log plot. The values of the breakage distributions are deduced from the size distributions at short grinding times where there is mainly size 1 material breaking and only small amount of smaller sizes to rebreak (Austin et. al., 1984). B values can be calculated by using BII. [ ] where j is the top size of the charge, Pi(t) is the cumulative percent undersize of i th size interval at the short grinding time which gives no more than about 30% broken out of the top size interval. Cumulative primary breakage distribution, Bi,j, is also defined in an empirical form by [ ] where xi is the top size and Bi,j is the weight fraction of primary breakage products. The parameters F, ? and ß define the size distribution of the material being ground. On plotting size versus Bi,j on log scale, the slope of the lower portion of the curve gives the value of ?, the slope of the upper portion of the curve gives the value of ß, and F is the intercept as in Fig.1. [ ]

Jan 1, 2009

By M. Abdellatif

Keywords: Pyrometallurgy, furnace, DC arc furnace, smelting, silicon The technical feasibility of silicon smelting in a DC arc furnace was investigated. A graphite-lined furnace was operated at power levels of 150 to 160 kW, and 40 to 60 V. The average feed rate during the silicon production period was about 30 kg/h. The recipe consisted of pre-mixed batches of 28% petroleum coke and 72% lumpy silica. The target furnace operating temperature was set at 1600°C and then raised to 1700°C. In total, about 1.6 tons of premixed feed materials was processed over 16 feeding?tapping operations. The feed was manually charged into the furnace in sub-batches of 10 to 40 kg at a time. The total batch mass was set at 90 kg during the initial part of the testwork, and increased to about 120 kg for the rest of the campaign.

Jan 1, 2011

By George S. Rice

In response to numerous requests for information as to the status of internal-combustion mine locomotives of the Diesel type that use heavy or non- volatile oil for fuel, with special reference to their safe use in coal mines, the United States Bureau of Mines is issuing this report. Data mere obtained, on application of such locomotives to cod mining only in Belgium, France, Germany, and Great Britain. The locomotives are used in coal mining in other countries, as well as in potash, iron, and other kinds of mining, but their chief development has been in coal mining in Germany, France, and Belgium. Recently popular interest in the Diesel type of engine for motive purposes was aroused in this country by the successful application of Diesel engines to railroad locomotives hauling fast transcontinental trains, and, according to published statements, at a low cost of fuel per mile of run.

Jan 1, 1936

By Larissa Koroznikova, Steve Durkin, Bradley Drake, Michael Tuck

This paper presents the results from the investigation of the application of thermal fragmentation in Australian hard rock underground narrow-vein mining. Two geologically similar samples from an underground narrow-vein hard rock gold mine were collected to obtain a measure of the technology’s ability to recover ore by the creation of large thermal openings to assess the applicability of the thermal method. Particle size distribution showed a higher generation of fine product, − 2 mm, by thermal fragmentation compared with selective blasting by 31%. The Bond work index for thermal ore (12.62 kWh/t) is half to that of the blasted ore value (25.32 kWh/t). The average grindability obtained for the thermal ore sample was greater than the blasted sample by a factor of 2.44, a higher value indicating a decrease in the energy required to grind. The thermal fragmentation method generates product with higher dissolution of gold in cyanide, by 14% for the − 9.5 + 2 mm size fraction samples. Additionally, the thermal fragmentation results in higher production of − 9.5 + 2 mm material by 15 % compared with selective blasting.