Search Documents

By V. A. Ignatkina, V. A. Bocharov, T. I. Yushina, I. M. Petrov, A. A. Kayumov

"The purpose of this research was aimed at increasing recovery of metals from rebellious sulfide polymetallic ores of nonferrous and rare metal deposits. The ores under consideration have common processing features, including textural and structural complex characteristics, irregularity of impregnation and wide range of grain size, up to nanoparticle size, variable complex mineral composition, low content of precious metals etc. This all predetermines the need for advanced processing schemes with deep selective liberation and separation of minerals with intercycle release into rough concentrate and fractional products with the use of multi-stage cycles of individual dressing, based on an optimum combination of various integrated beneficiation and hydrometallurgical processes. The application of existing standard processes does not enable the production of high-grade selective concentrates without reducing the recovery rate due to incomplete separation of fine mineral intergrowths and overgrinding of brittle ore and rock minerals.The combined beneficiation processes for such type of resources, aimed at increasing recovery of nonferrous, rare, and precious metals are based on flotation methods in combination with gravity concentration to produce rich rough collective or selective concentrates, comprising readily floatable mineral fractions. At the same time, hardly recoverable and non-separable mineral associations are released into separate concentrated products for following dressing by individual processes. The proposed combined process provides for successive selective liberation of minerals with release of rich readily recoverable mineral fractions at the preparation and ore beneficiation stages. The hardly recoverable mineral associations shall be released in subsequent operations with the use of dressing, based on a combination of beneficiation and pyro- and hydrometallurgical methods."

Jan 1, 2018

By R. H. Jefferson

This Bureau of Mines report describes a series of rapid wet chemical methods for the analysis of blast furnace slags. A "complete" analysis for total iron, manganese, silica, lime (calcium oxide), magnesia (magnesium oxide), sulfur, and mixed oxides (R203) can be routinely performed in less than 3 hours. These methods were employed as the analytical control procedures for the Bureau's experimental blast furnace operations and have been satisfactorily applied to the analysis of other slags and calcareous materials.

Jan 1, 1974

By Fred Beasley

METALLURGISTS have, in the past ten years, overcome many difficulties of high zinc in lead blast-furnace slags. This problem was brought to the front at the close of the late war, by the price obtained for lead and the high cost of labor, fuel, and flux. The Port Pirie plant of the Broken Hill Associated Smelters, Australia, early in 1919 had increased the zinc oxide in its blast-furnace slags from 13.5 to 20 per cent., at the same time reducing the iron oxide in the slag from 33.5 to 25.6 per cent. These results were obtained by the following proceduret the addition of granulated slag to the roaster charge, 10 to 12 per cent., improved conditions of the crushing and mixing and roasting of the constituents of the sinter. By experiments and improve-ments the practice at this plant has developed a normal slag that carries 22 per cent. zinc oxide, and at times runs as high as 33 per cent. zinc oxide, with only slight furnace trouble. The granulated slag is used not, only as a diluent to the sulfur in the roaster charge, but also on account of its value as a slag-forming material and on account of the physical properties it imparts to the finished sinter. The ore is mixed with flux and given a double roast. All the first roasting is by sintering with the Dwight & Lloyd machines. The final roasting is performed partly by Dwight & Lloyd machines and partly by H. & H. pots. The charge to the blast furnaces consists chiefly of the final sinter, slag shells, siliceous and non-bearing sulfur, lead ores. High blast and ore columns are the practice. The greatest care is taken to obtain in the final sinter as low a sulfur content as possible.

Jan 2, 1925

By T. I. Urbancic, C-I. Trifu

"ABSTRACTSeveral case studies are presented on the use of seismic techniques to map active structures, evaluate changes in stress levels, and identify the conditions leading to large magnitude seismic events and the generation of rock-bursts in Canadian mines. The results suggest that microseismicity can be used to identify the orientation of active fractures; define regions of relatively high and low stress, and those most likely to host a rockburst; determine the role of local stress on observed shear failures; and identify the path of stress transfer associated with the remote triggering of rockbursts. Additionally, the conditions leading to rock-bursts can be characterized by a significant increase in the clustering of microseismic events along the fault plane orientation of an impending event, and an increase in the effective stress levels. It is concluded that the analysis of microseismicity provides the means for remotely monitoring rock mass behaviour as a result of mining."

Jan 1, 1997

By W. K. Dressel

Over 2 million tons of steel furnace dusts are produced each year in the United States. Recycling of these dusts rather than disposal would conserve mineral resources, reduce land requirements for disposal, and decrease pollution. In addition to the iron content, the dusts contain appreciable amounts of zinc and lead. Removal of lead and zinc with simultaneous reduction of Iron oxide has been achieved by inert atmosphere roasting of carbon-containing pellets prepared from steel furnace wastes. High- and low-carbon wastes were blended to obtain mixtures with sufficient carbon to serve as a reductant during subsequent roasting. The mixtures were pelletized with the addition of bentonite and water, and the dried pellets were roasted in a stream of nitrogen at temperatures ranging from 900" to 1,150° C. Zinc and lead contents were reduced to the 0.1 percent level or less by roasting mixtures containing as little as 7 percent carbon for 1 hour at 1,100° C. ton metallization increases with available carbon content; 50 percent metallization is achieved with 7 percent carbon, 85 percent metallization with 12.5 percent carbon, and over 95 percent metallization when the pelletized mixtures contained in excess of 20 percent carbon.

Jan 1, 1973

By G R. Howard, G Back

Management of information systems for data collection is essential to maintain data integrity and continuity, and manage loss control on a large world-class mine such as Telfer Gold Mine. This paper aims to describe the individual systems and protocols of geological data capture at Telfer, then focus on Quality Assurance Quality Control data as an example of loss control in practice. Loss control systems are required to provide capacity, flexibility, structure and management tools to enhance data interrogation. The data that have been collected can then provide geological, financial, environmental, and contractual information to optimise management of business best practice. Telfer Gold Mine is a wholly owned and operated subsidiary of Newcrest Mining Limited. The mine is located in a remote area of NW Western Australia, and has been operating for 20 years. Geological data have been collected at Telfer since 1973. The data include drilling, assay, geological, survey, structural and geophysical data. Data management has evolved through many systems with data stored on many different hardware and software platforms. Commencing in 1995, collation, standardisation and validation of the historic data was completed. This has resulted in the first Access based drill hole database incorporating all available drilling data. This drill hole database, now hosted in SQL Server, is the hub for all geology related data management systems. The Telfer Gold Mine Geology Department has developed a series of inter-related database systems in order to manage the core geology business issues. Databases relating to drill hole planning, drill contract management, geological logging, accounting (standard costing, forecasting, invoice reconciliation), quality control (QAQC), and environment rehabilitation have all been developed to manage loss control. Management effort to provide adequate data systems and protocols has driven the system from concept to utilisation. The improved productivity, data integrity and data analysis capabilities provided by the new database systems at Telfer have allowed for greater confidence in decision making. Systems such as the drill hole and QAQC databases, when utilised in the proper manner provide up-to-date data analysis for resource audits and contract negotiations. The loss control systems are essential to maintain confidence in data integrity and hence directly effect the future of mining at Telfer.

Jan 1, 2000

"In many gold deposits, a reasonable amount of the gold that remains in the cyanide leach tailing is associated with pyrite. Some gold plants have found it economical to incorporate gravity circuits on the cyanide leach tailing to recover the gold bearing pyrite before subjecting it to fine grinding, then recycling the ground pyrite back to the cyanide leach circuit. For low grade gold deposits the loss of gold bearing pyrite is exacerbated as the broader process economics normally favour a coarse grind (> 150 ?m). An option that has received attention over the last decade is to recover the gold bearing sulphides in the milling circuit by gravity, similar to the widely-practiced gravity recovery of free liberated gold. The modelling and simulation of a gravity gold circuit in a milling flowsheet is relatively simple compared with a gold bearing pyrite circuit, as the recycle advantages and breakage functions for gold and pyrite are quite different. This current work represents an attempt to simulate the gravity recovery of gold bearing sulphides in a milling circuit that also incorporates fine grinding, using relatively simple simulation models. The simulation results are further explored with reference to the economics of this type of circuit.INTRODUCTION It is well known that gold is associated with pyrite in most sulphide gold deposits and that the amount of gold associated with pyrite will vary from deposit to deposit. Most of the gold associated with pyrite is liberated in the grinding circuit during the processing of a gold ore. However, some gold remains occluded in the pyrite and is lost in the final leach tailings. Little information is available in the literature on methods to enhance gold liberation from pyrite by specifically removing pyrite, either in the grinding circuit or from the final tailings stream, and grinding it finer. One of the earliest record of this approach is described by King (King, 1949) where pyrite present in Witwatersrand gold ores was recovered by circular jigs and Johnson barrels followed by fine grinding of the concentrate prior to cyanide leaching. Dominy et al., 1970, provides information on the use of Yuba jigs to recover pyrite from the discharge end of ball mills. Again, the jig concentrate was ground to a fine particle size before cyanide leaching to recover the liberated gold. Unfortunately, no information is provided in these articles on the additional gold recovery from implementing these circuits in a flowsheet. Martins et al., 1993, provides details of a gravity circuit using Reichert cones and spirals to recover gold bearing pyrite from a cyanide leach tailings followed by fine grinding of the pyrite concentrate in a Tower mill. The ground concentrate returned to the front end of the already installed leach circuit. Overall recoveries were increased by some 2% to 4% depending on the amount of gold and pyrite in the plant feed."

Jan 1, 2017

Anodic stripping voltammetry is an analytical technique which has established some popularity for trace analysis of metals because of its sensitivity, selectivity and capability for simultaneous analysis of some elements. The technique can be readily adapted for field use because of its relative simplicity and low power requirements. This paper describes a relatively new instrument, the Portable Digital Voltammeter, developed by CSIRO, which utilises the glassy carbon electrode in a novel cell design and provides parts per billion (ug/L) sensitivity in an instrument which can be field operated. Ten elements, Zn, Cd, Tl, Pb, Cu, Sb, Bi, Hg, As and Au can be routinely analysed. Many of these elements are of interest to the mining industry, and to exploration geochemistry in particular. Case histories where the instrument has been successfully employed for stream and stream sediment analysis of Cu and Pb, for soil surveys of Cu and Au, and for Au in stream sediments and drill chips indicate there are advantages in having on-site data, during Exploration.

Jan 1, 1987

By Z. L. Huang

A new porous apatite product was prepared using phosphorite from Yichang China by a tem-plate-directed method in self-made reaction equipment under constant temperature and pressure. The product was characterized by XRD, FT-IR and SEM. The results showed that the product was a kind of micrometer porous sphere three-dimensionally structured by apatite nanoflakes, that the average thickness of nanoflakes was about 50 nm, that the average pore size was about 1.2 µm and that the particle average size was about 20 µm. Great amounts of Ca2+channel, high special surface area and regular spherical shape show the potential promising applications of this special porous apatite product in the fields of catalyst, medication, chemical engineering and environment engineering

Jan 1, 2014

By J. Hoover Mackin

The iron ore bodies of the Iron Springs district are replacement deposits of magnetite and hematite in Jurassic limestone around the borders of three intrusions of quartz-monzonite porphyry. Production in the period 1923-1965 was about 72,000,000 tons, nearly all of which was direct-shipping ore from open pits. The intrusions are laccolithic in form; all three were emplaced at the same stratigraphic horizon, which had been a zone of decollement gliding during the Laramide orogeny. The intrusions and associated volcanic rocks are post-orogenic. There was no change in the thickness of the limestone during the metallization. Comparison of the composition of the limestone and stratigraphically equivalent replacement ore indicates that, with every million tons of iron, there were additions of 40,000 tons of silicon, 20,000 tons of magnesium, and 10,000 tons of aluminum. The ore-forming fluid was derived from the exposed porphyry. The iron was first incorporated in hydroxyl-bearing mafics, which crystallized in depth and were carried upward in the magma that formed the hypabyssal intrusions. The mafic phenocrysts decayed deuterically in the new environment, releasing iron into the interstitial fluid of a consolidating crystal mush in the interior of the intrusions. Primary tension joints, which opened in areas of late intrusive distention, served as roots through which the ore-forming fluid was drawn from the crystal mush.

Jan 1, 1968

By S. F. Willey

The difficulties encountered in justifying replacements for over-age mobile mine equipment at the Gay Mine are common to most mining operations. More critical management reviews, resulting from ever rising capital expenses, increased such difficulties. These increased difficulties are especially apparent to those who are primarily operators and are not statisticians, mathematicians, or computer oriented. The Gay Mine is located 17 miles east of the town of Fort Hall in southern Idaho. This open pit operation annually supplies the J. R. Simplot Company and the FMC Corporation with 1.5 MM - 2.0 MM tons of phosphate ore. Stripping ratios average approximately three bank cubic yards of waste per ton of ore mined. The mobile mine equipment fleet consists of ten 24 yard scrapers; twenty-one 30-50 ton end dump trucks; four 32 42 yard shovels; fifteen dozers in the D-8 and D-9 classes; and three road patrols. Equipment replacement is based on the results of evaluations made on individual units. Authorization of capital expenditures for equipment replacement is dependent upon a favorable profitability index (true rate of return on investment) plus a favorable payout time. The system is based on cash flows and requires the determination of (1) the net cash outflows in the form of capital expenses plus (2) the expected cash inflows resulting from reduced expenses and depreciation tax credits. After adjustments for taxes and the time value of money, the net amounts are used to calculate the required indices. The basic elements for the system related to the replacement of mobile mine equipment include: (1) the determination of dollar penalties to be expected from the continued use of aging equipment; (2) the selection of equipment that will provide the greatest return on the investment dollars; (3) the quantification of the expected savings; and (4) the calculations of the prescribed indices. Inadequacies inherent in previous evaluating methods led to the search for more

Jan 1, 1972

By E. Peters

Roasting processes are divided into several elementary mechanisms, any of which could be significant or pre-dominant in a particular roast. The elementary processes considered in-elude beat transfer, gas-solid inter-actions with accompanying mass transfer between the bed and furnace atmosphere, vapor phase transport processes in solid-solid interactions, and solid phase diffusion processes. Examples are chosen of processes in which one of these mechanisms pre-dominates and some recently obtained data is presented to support the existence and significance of these mechanisms. Proposals are also made for future research in these areas, and for utilizing the information in the improvement of roaster capacities’ OASTING of ores as a preparative treatment for smelting or leaching has been practiced for so long that its origin has been lost in antiquity, but little has been under-stood of its basic nature until fair-ly recent times. The nominal chemistry of roasting processes is now understood; that is, the initial chemical com-pounds present in the ores or con-

Jan 1, 1961

By Chris Yellowega

The construction and startup of a new mine is a daunting task. To successfully locate, design, build and startup an immense human endeavour like a new mine, takes perseverance, planning, dedication and significant capital. The application of capital requires a thorough evaluation of risk and where that risk is most properly limited to create the risk/return profile. One area of significant capital and thus, significant risk is the selection and maintenance of the very machinery needed to deliver the creation of investor wealth. Albian Sands Energy is the operator of the new Muskeg River Mine located north of Fort McMurray in Alberta?s oilsands. The Muskeg River Mine is owned by a joint venture of three companies: Shell Canada, Chevron Canada Ltd.and Western Oil Sands. The mine is designed to run 400,000 tons per day, 365 days per year. The mine conditions vary from material as hard and of similar consistency to pavement to underfoot conditions as soft as saturated sands. Water cannot be drained below surface conditions, shovel teeth can disappear in less than 24 hours and the primary business is often constructing large civil structures that have little to do with the delivery of ore. The mine starts with the deposit (if it doesn?t exist, nothing else matters), moves into the design, the feasibility study and the approval. The evaluation of risk and the strategies surrounding the control of that risk truly lie after these stages are complete. The strategy and execution stage is where risk is eliminated or accommodated. The point at which the investors money is being spent is the point at which the decisions made cannot be reversed. It is of absolute importance that the execution of the decisions are consistent with the strategy agreed to, lest the investors need to be asked for more money. The key sources of risk identified for the Muskeg River Mine were recruitment of trained and experienced personnel and the delivery of ore to maximize early (<2yr) cash flow. The Muskeg River Mine personnel determined that to minimize risk, personnel would be recruited to operate the mine equipment yet, the requirements for maintaining the equipment would best be held by the manufacturer. The strategy was to obtain the correct equipment for the operation of the mine and leverage the supplier?s expertise to ensure the mine wasn?t training a maintenance organization at the same time as a mining organization. In essence the key strategy for the mine start up and early operation was to leverage the equipment suppliers to maintain and repair the equipment. Albian Sands would maximize the utilization of Maintain And Repair Contract?s.

May 1, 2003

By Rodney Ishak, Merete Tangstad

In the HC FeMn production, better utilisation of coke and electric power is vital for reducing the production costs. The higher manganese oxides in the charge are reduced to MnO in the prereduction zone, where also the Boudouard reaction is active. These gas-solid reactions are to a large extent decisive for the total consumption of both coke and electrical power in ferromanganese production. In the present work formulas for calculating the Degree of prereduction have been developed for industrial practice. It shows that the typical Degree of prereduction is between 10-40%, but it may in good periods be as high as 60%. Statistical analysis has been done in order to find how various operational parameters influence the Degree of prereduction. A few parameters were observed to have an effect on the prereduction. Comilog ore definitely had a positiveinfluence on the prereduction, Comilog sinter and Mamatwan ore probably had a positive influence on the prereduction, all in relation to the average prereduction in the selected periods. Meanwhile, As man ore definitely, % H2O in raw materials and increasing Hd probably, had a negative influence on the prereduction. The findings for these raw materials were very much in coherence with the results of laboratory scale experiments performed, where the CO-reactivity of different ore materials was studied.

Jan 1, 2007

By Andrelio Marcos Ribeiro, Lucio Ribeiro Camisao, Antonio Carlos Ataíde, Alan de Sousa Pereira, Renato Siqueira Campos

The annealing and pickling line n. 1, responsible for the production of stainless steel 3xx, 4xx and 430a in thicknesses from 4 to 0.4 mm, has two vertical strip accumulators. These are intended not to let the material exceed the determined time in the furnace and in the pickling, and consequently do not cause defects like burning and excessive pickling. Strip accumulator n. 1 avoids the line from stopping during welding execution of the coils in the welding machine. In sequence, the strip accumulator n. 2 avoids the line from stopping at the end cutting of the tips, and in the coils removal from the pickling. The strip accumulators have a roller table that during the strip accumulation moves vertically downwards while its counterweight moves vertically upwards, and do the inverse movement when the material is released. On December 12th 2018, the failure occurred in the strip accumulator n. 1, where it was verified that the shaft of one of the pulleys had been fractured by high-cycle mechanical fatigue, which was characterized by alternating bending. With the fracture of the shaft, occurred the unevenness of the counterweight that damaged the guides. Failure analysis of this occurrence was based on the PDCA methodology, when was verified a weld between the shaft and the pulley. The analysis of the microstructure transformation in the molten zone, in the heat affected zone and in the base metal was carried out in an optical microscope, and no abnormality was observed. It was also carried out the end test by penetrating liquid, finding an inadequate weld in its geometry, as well as longitudinal trunks along the center of the weld bead. However, after a huge investigation of the causes, it was found that the failure was triggered by an inadequate design of the pulley shaft. It was also verified that the shaft had an open measure, inadequate for the operational context. After the analysis, action plans were drawn up based on the FMEA methodology to inhibit the failure recurrence.

Oct 7, 2019

By S. N. Singh, M. C. Flemings

Results are presented of a detailed study on the combined influences of ingot dendrite am spacing and thermomechanical treatments on the structure and solution kinetics of high --purity cast and worked 7075 alloy. Solution kinetics were found to depend sensitively on ingot dendrite am spacing and on details of therrnomechanical processing, including amount of reduction and extent of&apos; solution treatment before reduction. An approximate analysis is given for rate of solution of nonequilibrium second phase in the cast and worked structres; results of the analysis are compared with experiment. MICROSEGREGATION in high strength aluminum alloys manifests itself as "coring" (composition differences within the primary aluminum-rich phase), and as interdendritic second phase. The mechanism of formation of the microsegregation is understood, and approximate prediction of the amount of second phase is possible for simple binary systems.1,2 When alloy elements or impurities are present in amounts less than their solid solubility at solution temperature, any phases forming from these elements are termed "nonequilibrium" and can be dissolved by appropriate solution treatment. The rate at which the nonequilibrium phases are removed depends sensitively on their spacing (dendrite arm spacing in the cast material, or band spacing in wrought material). When alloy elements or impurities are present in amounts in excess of their solubility at the solution temperature, second phase particles form an "equilibrium" second phase that does not dissolve in heat treatment and may, in fact, coarsen in such treatment. Usual commercial, high strength, wrought aluminum alloys contain nonequilibrium second phases that were not fully dissolved during ingot processing. They also contain equilibrium second phases resulting from impurities present in amounts greater than their solubility. As has been shown by Antes, Lipson, and Rosenthal,3 and will be demonstrated further in a subsequent paper by the authors,4 significant improvements in mechanical properties of high strength alloys can be achieved by reduction or elimination of these second phases. Methods of elimination are 1) to employ high purity materials to minimize amounts of equilibrium second phase, and 2) to employ suitable thermomechanical processing techniques to fully eliminate nonequilibrium second phases. Work reported herein comprises a study of selected thermomechani- cal processing treatments, and of their influence on solution kinetics of wrought high purity 7075 alloy. EXPERIMENTAL PROCEDURE Melting and Casting. The bulk of the work reported was performed on a single ingot of high purity 7075 alloy. The ingot was 4 in. by 4 in. by 8 in. high, uni-directionally solidified following a procedure previously described.5 The mold was heated to 1350°F before pouring the melt. The bottom chill was carbon coated stainless steel. Water was circulated through the chill after the melt was poured. The 7075 alloy was prepared from high purity virgin material (aluminum, zinc, magnesium) and from master alloys (Al-50 pct Cu, A1-15 pct Cr, A1-5 pct Ti). Final measured melt composition (wt pct) was: Zn Mg Cu Cr Ti Fe Si Al 5.70 2.28 1.35 0.18 0.15 <0.002 <0.012 bal Melting was done in a silicon carbide crucible; all tools were coated with zircon wash to minimize iron contamination; degassing was by bubbling chlorine through the melt. che-rmomechanical Treatments. Detailed studies were made on material taken from a location approximately 13 in. from the chill and 51/2 in. from the chill (i.e., from 1 in. thick slices taken between 1 and 2 in. from the chill and between 5 and 6 in. from the chill). Solution treatment was done at 860°F in an air-circulating furnace with a "bottom drop" arrangement to achieve minimum delay time between solution treatment and quench. Samples solution treated in this way were 2 in. by 2 in. by 1 in. Temperature of the quench water was approximately 10°C. Mechanical reduction was by cold rolling. Samples 11/2 and 51/2 in. from the chill were treated for 12 and 24 hr, respectively, before cold rolling. Reduction by cold rolling was then 4/1, 16/1, and 35/1. In each case, several intermediate anneals (1/2 hr at 860°F) were used to permit reaching the final thickness without cracking; two such anneals were used for the 4/1 reduction, five for 16/1, and six for 35/1. After working, materials were again solution treated for various lengths of time from 0 to 48 hr and quenched in water. Structural Measurements. Secondary dendrite arm spacings were measured using procedures previously described.&apos; For each measurement reported, five photomicrographs were first made at X75. Measurements were made of dendrite arm spacings in at least 20 different grains (grain structure was equiaxed). Grain size measurements were made by running a number of random traverses across photomicrographs of the samples and obtaining the mean lineal intercept. Measurement of the volume percent of second phase and porosity was done by quantitative metallography. A two-dimensional systematic point count was used

Jan 1, 1970

Economies in cemented fill demand the utilisation of the full potential of the portland cement component of the mix. If declined tailings are used, it is desirable to establish the optimum particle size distribution. Pozzolic materials and slags are. very useful additions to increase the amount of cementitious material through reaction with calcium hydroxide produced by hydration of the cement. It is also essential to check out the presence of substances which may seriously affect the setting and hardening of the cement or the durability of the cement bond. The importance of quality control in the preparation of cemented fill cannot be over Emphasised.

Jan 1, 1973

By Jeffrey W. Lin, Jonathan D. Abbott, Patrick R. Bowden, Tyson J. Plitt

Pentolite is a class of high explosives containing trinitrotoluene (TNT) and pentaerythritol tetranitrate (PETN) with PETN content typically ranging from 40 to 60 wt%. Manufacture involves melting TNT, 80 °C, followed by addition of PETN and trace ingredients to form a homogeneous mixture. Once a mix is ready to be poured, several factors can influence the behavior of the finished product including how long the mix has been at temperature and cooling rate. After the manufacturing process has been completed, storage conditions combined with manufacturing conditions may cause physical changes. Two such changes explored were exudation, liquid exuding from solid boosters, and ratchet growth, irreversible volumetric expansion. Exudation is principally caused by excess water in the process. Ratchet growth is a common phenomenon of nitroaromatic compounds such as TNT where time and temperature fluctuations can cause materials to increase volume, simultaneously decreasing density. Although neither phenomenon affects common attributes such as sensitivity, performance, and shelf-life, both can cause issues in storage and handling. In this study pentolite was cast into various forms under different manufacturing conditions and evaluated over several months of controlled storage conditions including ambient, temperature cycling and elevated isothermal. Subjective and objective measurements were made throughout the evaluation period with the aim to determine the preferred storage methodology.

Jan 21, 2025

By A. R. Miller, G. Desrivières, M. C. Bétournay, D. L. Barnes, P. Laliberté

"Over the last four years, an international initiative, championed by Vehicle Projects LLC, the Fuelcell Propulsion Institute and Natural Resources Canada, has been active in carrying out research projects to prove out the concept of applying fuel cell technology to underground mining vehicles. These have been carried out by a consortium consisting of mining companies, equipment manufacturers, technology developers, national laboratories and consultants, with the participation of Canadian and U.S. mine regulatory agencies.This clean technology, which produces only water and electricity, would allow several advantages to be obtained, in the health area (by eliminating diesel emissions and reducing noise generation), in lowering production costs (such as reducing ventilation required) and lowering greenhouse gas emissions.This paper outlines the results obtained in several key areas, such as, the operation of fuel cells in underground conditions, risk issues related to underground and surface operation of hydrogen vehicles and hydrogen production and delivery systems, and the design and mining performance of the world’s first hydrogen mining vehicle, a mine production locomotive. The work to date on the fuel cell loader, designing the power plant and power transmission systems, operational requirements, and operating cost reductions is also presented."

Jan 1, 2003

By C. Perez

In mineral processing plants it is important to estimate rock composition, size and grindability to improve control of the grinding process. It is well known that variation in ore grindability and size distribution directly affects mills power consumption and throughput. This paper extends a general machine vision approach for on-line estimation of rock mixture composition using color information. Our proposed rock lithological recognition method requires the following steps: division of each image into sub-images, color feature extraction using the Binary Quaternion-Moment-Preserving thresholding technique (BQMP) and support vector machines (SVM) for classification. The BQMP thresholding technique splits the image in two and chooses representatives of each half using the histogram as features. The statistical parameters of the color data can be expressed using the quaternion moments into the representatives. This method can be recursively applied to the sub-images, obtaining 5x2n features in n iterations. Once the feature vector has been computed, each vector is assigned to one of three classes using a classifier. The method was tested on a database containing 20480 sub-images (64x43 pixels) of five ore types as follows: massive sulphide (MS), disseminated sulphide (DS), net textured (NT), gabbro (G), and peridotite (P). These ore types were assigned to three grindability classes: soft (MS), medium (DS and NT) and hard (G and P). The database was divided in 2 subsets: 15360 sub-images used for training and cross validation and 5120 sub-images used for test. The classification accuracy was compared with a method previously published based on a mixture of principal components analysis (PCA) for color, and wavelet texture analysis (WTA) for texture feature extraction. WTA-PCA approach reached a 76% accuracy in test while our BQMP method reached 90% of classification accuracy using only color features. Experimental results show that our proposed method yields excellent results compared to previously published results. Keywords: rock classification, lithological classification, grindability estimation

Sep 1, 2012