Search Documents

By C. S. Griffith

Lithium Australia NL (ASX:LIT) and ANSTO Minerals have been working together since 2015 on the development of halide accelerated leaching for the extraction of lithium from lithium-bearing micas, spodumene and clays. This technology has been termed SiLeach® process. The driving force behind development of the SiLeach® process, initially, was to develop a hydrometallurgical process to extract lithium from micas and spodumene without the need for the energy intensive, high temperature processing conventionally applied to lithium extraction. This driving force remains today and continues to hold promise in realising the value of previously under-utilised lithium resources. A comprehensive understanding of the technology and its applicability to the processing of micas and spodumene currently exists, and the flowsheet has been rigorously piloted. Production of battery grade lithium carbonate has been demonstrate

By B. Das

Most coals are susceptible to spontaneous heating which in turn creates problem to mining, storage and transportation of coal. It is impossible in actual practice o eliminate spontaneous heating but spontaneous combustion can effecively be controlled through a clear understanding of its mechanism and the factors affecting it. There are altogether six stages in the process of spontaneous combustion. This includes the water adsorption stage and six oxidation stages: chemi-sorption (upto 70°C), decomposition of peroxygens (70°C-150°C), oxy-coal formation (150°C-230°C), combustion initiation (230°C) and active combustion (> 230°C). Heat is produced in all these stages. On the other hand heat is also dissipated so that some equilibrium temperature is reached. If this temperature exceeds a certain critical value (generally about 70°C), coal oxidation may advance to spontaneous combustion. The major factors influencing spontaneous combustion of coal are: coal rank, maceral composition,, water, mineral matter, joints and fissures, seam depth and thickness, mine Layout, method of ventilation, etc. Susceptibility is high for low rank coals and generally decreases with increase in rank. Of the macerals, the exinites are generally most susceptible, the inertinites least and the vitrinites somewhere in between. Water plays a major role on the spontaneous heating of coal, assisting in someways and inhibiting in other. Unrecovered coal in the gob (generally in thick seams) is a major source of fire hazards and this is specially important in shallow mine. Proper design of mine ventilation system can substantially reduce the risk of mine fire. Panel layout and load transfer can affect the development of induced cracks which in turn influence spontaneous heating. Finally, the difference between the spontaneous heating of coal in a seam and that in storage or transportation is mainly due to the change in moistured content, air circulation through the coal and coal fragmentation. These aspects have been analyzed in this paper with a view o reducing the risk of spontaneous combustion.

Jan 1, 1986

By M. H. ElMaghraby

This paper describes the development and validation of a strategy for vibration-based online detection of faults in a particular class of machinery commonly found in industry. This machinery is defined by two basic characteristics that preclude it from the application of standard online condition monitoring approaches. The first characteristic is that the machine is in a constant state of transient operation, thus making it difficult to differentiate between changes in transducer measurements that are due to variable duty and those that are due to machine malfunction or fault. The second characteristic is the fact that the machinery involves multiple sub systems that are subject to identical and simultaneous loading, operating environments and duty cycles. An example of such machinery is a system of multiple hydraulic pumps driving a common load. The monitoring strategy presented here employs an anomaly detection scheme together with methods of signal processing and feature extraction that exploit the parallel duty arrangements of this equipment. Preliminary data is collected from a pair or motor-gearbox assemblies used in a material haulage system in the mining industry. Testing and validation was performed on a mechatronic test bench with both healthy and faulted components. Experiments were carried out to investigate how various configurations of the system were able to detect different types of faults. The results indicate that this approach is effective and merits further investigation.

May 1, 2013

By M. Walawalkar, C. K. Nichol, G. Azimi

Rare earth elements (REEs) are essential to the production of technologically advanced products, including wind turbines, electric and hybrid cars, automotive catalytic convertors, hand held electronic devices, and military defense systems. Their application in environmentally beneficial technologies puts them at a high priority for ameliorating environmental concerns. Because of their increasingly high demand and limiting resources, it is highly beneficial to find new sources for them. The present study is focused on leaching REEs from a phosphate based fertilizer by-product, known as phosphogypsum (PG). Global estimated world production of PG is about 240 million tonnes that is stored in the form of wet stacks adjacent to fertilizer production facilities, occupying vast amounts of land. PG also contains trace metals, which are detrimental to the environment, and hence it is crucial to monitor these stacks. We obtained our PG sample from Agrium Inc. (a fertilizer manufacturing company in Canada). We performed a comprehensive characterization of the PG sample and found that it predominantly contains Y, La, Ce, Nd, and Sm. For leaching purposes, we used hydrometallurgical acid leaching techniques. We investigated three acids over a range of operating conditions such as acid concentration, temperature, solid-to-liquid ratio, and residence time. We achieved an average leaching of 81% with hydrochloric acid as leachant using operating conditions that can be easily replicated in industrial settings. If our process is implemented, not only will it reduce the size of the existing PG stacks (mitigating their environmental risks), but also enable the development of new innovative routes for extracting REEs, making countries like Canada less vulnerable to supply disruptions.

Jan 1, 2016

By F. E. Heuze

This article deals with the effects of high-explosive and nuclear explosions in rock masses. We first highlight the strong influence of geological discontinuities, such as joints and faults, on ground motion characteristics. Then, we briefly introduce the Discrete Element Method, as a new technique for numerical simulations. II is shown to be far superior to continuum-based approaches, when dealing with the dynamics of discontinuous media such as jointed rocks. Finally, we simulate the ground effects from a generic contained nuclear explosion, which bears some similarity to the SHOAL event in granite. This calculation is intended to emphasize the influence of the near-source geology on the distribution of energy, and on the motion at various azimuths in the medium.

Jan 1, 1991

By Ihsan Berk Tulu

The complex interaction between multiple seam pillar extraction panels and variable topography can generate unexpected ground control problems. This case study describes stress-related damage in multiple seam workings that resulted in difficult operating conditions and compromised the safety of the support crews. The damage appeared to be caused by horizontal stress but the unexpected location of the damage baffled the authors. A 2D Finite element analysis was conducted of the mine layout and surface topography in an attempt to explain the observed failure. It was discovered that the topography resulted in the rotation of the major stress at the location of the current workings. The stress rotation caused asymmetrical interactions between the workings on the different coal beds, which can explain the unexpected response observed in the mine. Consequently the layout of the next panel was changed by locating the vulnerable entry 30 ft away from its originally planned position. The new location was selected to locate the entry in favorable stress conditions. The change in layout resulted in a significant improvement in conditions when the next panel was mined. At the time of writing this paper, a full panel has been developed using the modified layout without undue ground control problems. The case study demonstrates that numerical models can help engineers to interpret and solve complex multi-seam interaction problems.

Jan 1, 2014

By Tseng. B. H.

Samples of unchlorinated and chlorinated carbonaceous concentrate from a carbonaceous gold ore were analyzed by transmission electron microscopy (TEM) for organically bonded sulfur and chlorine. The concentrate assayed 1.53 oz/t gold and 6.01% organic carbon. Much of the organic carbon occurred as sizable coarse particles up to several hundred microns in size, which showed no visible evidence of reaction with chlorine after chlorination treatment. Both the untreated and chlorinated fractions of the carbonaceous concentrate were analyzed by the TEM method, which detected organically bonded sulfur in all of the carbon particles examined in the untreated sample, ranging from about 1 to 5% organic sulfur, and averaging near 3.1%. TEM analysis of 40 carbon particles in the chlorinated sample indicated that organic sulfur was reduced significantly in the carbon and replaced in part by the chlorine, as the result of chlorination.

Jan 1, 1987

By Erik Westman, Brandon Stables, Benjamin Mirabile

"Standing support is often used in conjunction with underground retreat mining. Knowledge of the load-displacement behavior of standing support and loading induced by the mine opening is critical to proper support selection. The NIOSH STOP database contains load-displacement laboratory test data for most commonly used standing supports. Hydraulic load cells currently used to measure in-situ loading of standing supports have exhibited leakage under load, producing irregularities within the dataset. An improved hydraulic load cell eliminates leakage and produces more consistent data.INTRODUCTIONA hydraulic load cell, more commonly known as a flat jack or JackPack, is a device installed to determine the loading characteristics of the roof-to-floor supports. These standing or roof-to-floor supports include, but are not limited to pumpable cribs, cans, wooden cribs (4-point, 9-point, etc.), metal props, wood timbers, concrete donut cribs, and other variations of these standing supports.Flat jack devices have been used previously to determine the loading of such roof to floor supports. The most commonly used load cell for standing supports is based on a design intended for pre-stressing standing supports, not load measurement. Preloading helps to keep the supports, such as timbers props and cribs, in place during the dynamic loading associated with blasting (Barczak and Tadolini, 2004).Flat Jacks are manufactured in various shapes and sizes depending on the application; common shapes are square and round that are 25.4 mm (1.0 inch) thick when collapsed, as shown in Figure 1. These load cells are produced in South Africa and can be formed into several different shapes depending on the application (Barczak, 2003). The sheet metal that makes up the bladder is comprised of 19-gauge or 1.11 mm (0.04 inch) thickness; the top and bottom pieces of sheet metal are resistance-seam welded around the perimeter. There are two different ports installed on one of the bladder skin corners of the flat jacks; these ports allow fluid to fill the unit, and the other port has a relief valve. The fill port is comprised of a check valve. The pressure relief valve is located in the second port; preset to 1,724 kPa (250 psi), the pressure relief valve keeps the load cell from bursting. Bursting of these load cells typically causes a small tear in the metal skin allowing the fluid to leak out without a large catastrophic failure.The effective inflation range of these load cells is between 25.4 mm (1.0 inch) to 254.0 mm (10.0 inches) thick. Different types of fluids can inflate these load cells but the most common and easily accessible fluid for testing applications is water. Water pressure from the mine supply line can inflate these load cells to the desired load. Depending on the pre-stressing requirements, a pneumatic powered pump, hydraulic pump, or hand pump may be required to inflate the load cells."

Jan 1, 2019

By Jorge Ganoza

Algunos concentrados de plomo contienen contaminantes que afectan la comercialización del concentrado de cobre debido a aspectos ambientales, así como la calidad del producto final. En ese sentido, el presente texto busca la forma de minimizar la presencia del plomo y de bismuto en el concentrado de cobre, a través de la flotaciónpor chalcopirita. De otro lado, dado que el plomo y bismuto son elementos que tienen similar comportamiento durante la flotación, es factible aislar los minerales de plomo y bismuto.

Nov 1, 2012

By L. A. Panek, A. J. Barry, John A. McCormick

"INTRODUCTION During recent years, roof bolting has become widely accepted as a systematic method of supporting both coal- and metal-mine roofs. Today, over 2 million roof bolts are installed monthly. Most of the information on bolt installation procedure reported to date (1,2,3,4,5,6) 3/ has been obtained by trial and error by individual groups or operators. To insure good roof control, experience and field tests have indicated that roof bolts should be installed immediately after the exposure of new roof, and they should be preloaded enough to minimize sag of the roof over the opening. The question of the proper initial preload for roof bolts is under study, although it is a general practice to impose an initial load on a bolt of approximately 10,000 pounds. This created a problem of measuring bolt loads at installations in underground mines, which was partly solved by using a commercial-type torque wrench; a device that permits a direct reading of the torque applied to the nut on a roof-bolt assembly from which the corresponding load can be determined by referring to specifications furnished by the manufacturers. However, considerable apprehension was expressed regarding the accuracy of this measuring procedure because of variations in the manufacture of roof-bolting materials and the degree of care exercised in making bolt installations. In the process of loading a bolt, only a small part of the effort is expended in producing strain in the bolt - the larger part of the effort is used in overcoming frictional effects in the nut-bolt-washer assembly. These frictional effects are subject to many factors, such as condition of threads, type of lubrication, if any, the finish on the nut and bearing plate, and the alinement of the bearing plate on the bolt. The object of this investigation was to determine the accuracy with which the load developed in a slotted-type roof bolt installed in a conventional manner in shale or sandstone roof rock can be determined from the torque applied to the nut.This report is the first of a series relating to basic research in roof bolting in underground mines. A future report will cover results obtained using expansion-type bolts under similar conditions. Other reports will consider the efficiency of bolt anchorages, the long period stability of bolts, and the design of safe and efficient roof-bolting systems."

May 1, 1953

By Tyler Acorn

In December of 2009 an estimated one million ton slope failure activated a 10 million ton mass impacting use of the main ramp system in the Newmont Gold Quarry pit. The failure left behind a 400 foot (122 meters), vertical to sub vertical scarp feature and shut down production in the lower benches of the pit.

Jan 1, 2011

By Piotr Malkowski

Studies on the properties of rocks heated to high temperatures are rather rare. Such research is occasionally conducted for example; in areas around nuclear power plants. The national Polish coal gasification (underground coal gasification, or UCG) project has, however, forced the analysis of the geomechanical properties of heated rocks in the vicinity of a designed geo-reactor. Ukrainian experience with UCG show that rocks up to 2 m from the burned coal seam be at a temperature > 600ºC. Such a high temperature will undoubtedly influence their physical properties. This paper presents studies on the strength and deformation properties of carboniferous rocks in the Upper Silesian region, where the UCG process is planned. Three types of rocks were tested: claystones, mudstones and sandstones. Laboratory tests of these rocks evaluated compressive strength, elastic modulus and weight loss. An evaluation of the results of the tests comparing the thermal conductivity of rocks and their specific thermal capacity was then carried out. All of the rocks studied were heated to 300, 600 and 1000ºC, and also evaluated at room temperature. This procedure shed new light upon the behavior of heated rocks in relation to their distance from the designed geo-reactor. The test results presented were developed within Research Task No. 3 ?Developing a technology of coal gasification for efficient production of fuels and electric power?, financed by The National Centre for Research and Development under strategic research and development programme ?Advanced Technologies for Energy Generation.?

Aug 1, 2013

By S. Shankar

The phenomenon of re-entrainment is seen in many environments, such as sand dune formation, soil erosion, fugitive dust emission, spread of radio-nuclides from accidents involving nuclear weapons, etc. A thorough review of existing literature reveals that work on re-entrainment of dust in mine atmospheres is scant. The present study was undertaken as a part of on-going research in the Respirable Dust Center on the prediction of ambient dust concentrations in mine atmospheres (Ramani, 1983) to identify the contribution of dust re-entrainment to the spatial and temporal concentration in mine airways and included wind tunnel and in-mine studies. A set of seven experiments was performed in the Lake Lynn Laboratory Mine of the U.S. Bureau of Mines under controlled conditions. Two types of source coal dust, anthracite and bituminous, were subjected to airflow with a range of air velocities and walking by two different walkers. Six sets of instruments were used along the test section for sampling the airborne particles. The average air velocity just above the coal dust bed varied between 2.1 to 3.2 m/s. Due to re-entrainment as a result of the airflow conditions, the average respirable dust concentration in the center of the mine airway increased to 0.09 mg/m3 (standard deviation = 0.03 mg/m3) from an initial value of 0.02 mg/m3. The concentration of all (i.e., total) airborne dust increased to 0.17 mg/m' (standard deviation = 0.10 mg/m') from an initial value of 0.02 mg/m'. The action of personnel walking, however, caused higher amounts of re-entrainment. Average concentration of respirable and total dust at the center of the mine airway increased to values of 0.28 mg/m' (standard deviation = 0.12 mg/m3) and 1.53 mg/m3 (standard deviation = 1.0 mg/m3), from initial values of 0.03 mg/m3 and 0.05 mg/m3, respectively. It was observed that the dust concentrations were much higher near the floor, immediately at the end of the coal dust bed. Depending on the level of activity and the amount of dust deposited in mine airways, re-entrainment may become an important source of airborne dust away from the point of actual mining.

Jan 1, 1994

By Andrew Moran, William H. Walton, Matthew D. Emrick, Mary C. Nodine

"A rapidly growing company in the northern US needed a large auditorium built into a dolomite bedrock hillside. The structure required an 80-foot-deep earth retention system independent of the auditorium foundation and superstructure. Allowable wall movements were limited to less than two inches. A 60-foot-tall permanent shotcreted soil and rock nail wall was designed for excavation support. The soil and rock nail wall utilized both active (post-tensioned) and passive nails, with capacities and installation angles optimized to address varying soil and rock conditions and to support heavy surcharges. The wall was configured with three two-foot-wide benches to facilitate controlled blasting and removal of more than two million cubic yards of soil, limestone and dolomite bedrock, and featured a permanent cast-in-place concrete face and a robust waterproofing and drainage system. A 20-foot-high reinforced concrete retaining wall was required at the top of the soil and rock nail wall to raise grades, resulting in a large surcharge.Design of the soil and rock nail wall was initiated less than three months before the start of construction, requiring expedited geotechnical explorations, analyses, design, and construction that would occur simultaneously. Design changes were made to address the discovery of a weak clay residuum seam at depth running along the base of the excavation, as well as significant changes to the building footprint made after the start of construction. Extensive performance monitoring was conducted during construction to measure vibrations and movements.Introduction and Project BackgroundA fast-growing company in the northern United States had a need for 600,000 square foot, 11,000 seat auditorium as part of its campus expansion. The auditorium was built underground, into a hillside to preserve the views of rolling terrain and farmland beyond. It featured a green roof and rockwork facing that mimicked regional geologic formations. The sixstory building required up to 80 feet of earth retention, including 60 feet of excavation beneath existing grades.As concepts for the project evolved, it became apparent that due to the geologic conditions, space limitations on site and the depth of cut required, a standard counterfort wall system would not be feasible. With groundbreaking for the building three months away, Thornton Tomasetti (structural engineer) engaged GEI Consultants, Inc. (wall design engineer) to design a 1,600-foot-long permanent soil and rock nail wall to support the excavation. The wall design engineer implemented a geotechnical exploration program immediately and began the design process, coordinating closely with Nicholson Construction (specialty"

Jan 1, 2017

Palabora Mining Company (PMC) processes a multi-component ore body using a circuit consisting of two AG mills in parallel, closed with vibrating double deck screens and hydrocyclones. The bottom screen undersize feeds the hydrocyclones, but the screen oversize products can be treated in a variety of ways. The top deck screen pebbles can be crushed and then combined with the bottom deck oversize and recycled to the AG mill. Alternatively both the top and bottom deck screen oversize can by-pass the recycle crusher and be recycled directly to the mill. A full tap-off is a configuration when both the top and bottom deck screen oversize streams are stockpiled. The other configuration is when the bottom deck screen oversize is recycled to the mill while the top deck screen oversize is stockpiled - termed partial tap-off. This article reports the findings from the surveys performed to evaluate the performance of the PMC auto mill circuit when operated under the four different configurations discussed. Ore characterisation tests were performed to assess the deportment of the key ore components for the different configuration.

Jan 1, 2012

By Donna L. Bodine

The ability of oxidized Upper Freeport bituminous coal to adsorb Cu2+, Cd2+ and Mn(VII) from very dilute aqueous solutions has been studied. Low-rank coal is known to adsorb heavy metal ions from dilute, aqueous solutions, probably by ion exchange and/or chelation by acidic functional groups on the coal surface. However, it would be advantageous to use higher rank coals for water treatment. Coal samples were oxidized thermally or by 30% H202 to increase the surface concentration of phenolic and carboxylic groups, then portions were shaken with Cu2+ and Cd2+ solutions. Acidic KMnO4 was also used to oxidize coal, with concurrent sorption of the resulting Mn(IV) and Mn(ll). The effect of oxidation treatment, metal ion concentration, and solution pH on metal uptake kinetics was investigated. Potential applications for treating effluents, especially those containing oxidizing ions, are discussed, along with possible flowsheet options.

Jan 1, 1995

By R. Kramer, A. Habibi

"Diesel Particulate Matter (DPM) measurements were taken at Tronox’s Westvaco Trona mine in Wyoming. Both shift-average and real-time monitoring using Elf pumps and Airtec analyzers, were used. The mine’s underground transportation fleet consists of more than 250 diesel-powered vehicles. A vehicle monitoring log tracked fleet usage during the test; logged data consisted of vehicle type, direction of travel, and time. The log was used in analysis to determine the DPM spread rate, of normally operating equipment, in the different entries with respect to vehicle location. Airflow velocity measurements at the stations were taken during the survey. The survey results also identified vehicles with higher emission rates. An ECOM gas and a MAHA DPM analyzer, both located in the mine’s underground emission shop, were used to obtain various vehicle emission rates. The correlation of the workshop and field measurements was investigated with regard to the machine activity, fuel usage and atmospheric conditions. The results were used to identify and execute a ventilation project to reroute 45% of diesel shop air back to intake entries, by interlocking an automated door and a regulator. The result is reduced DPM downstream. INTRODUCTION DPM has been classified as a potential occupational carcinogen by the National Institute for Occupational Safety and Health (NIOSH).The Mine Safety and Health Administration (MSHA) rule governing DPM exposures in metal and nonmetal mines cites total carbon (TC), a summation of elemental carbon (EC) and organic carbon (OC) obtained by NIOSH Method 5040, as a surrogate for determining DPM exposures (Noll, 2006). MSHA personnel use the 1973 sampling criteria outlined by the American Conference of Government Industrial Hygienists (ACGIH) for collecting compliance-based respirable and inhalation samples in metal/nonmetal mines. Instrumentation developments are allowing improved real time monitoring of ventilation parameters. DPM is within the aerodynamic particle size range of the samplers used for respirable and inhalable dust measurements. If a sampler used by MSHA to collect inhalable or respirable dust samples in underground metal/nonmetal mines was used to collect DPM, both the DPM and mine ore dust would accumulate on the sample filter (Noll, 2006). To comply with the requirement and lower the DPM exposure, mines are implementing a variety of control technologies such as emission based maintenance programs where adjustments or repairs are performed on the vehicles (McGinn, 2000)."

Jan 1, 2016

By R. R. Dorfler

The existing regrind circuit at the Climax Operations uses sodium cyanide and Nokes reagent to reject pyrite, copper, and lead minerals. Laboratory flotation studies were performed using feed to flotation following first-stage regrinding. The effects of conditioning time, pH, and the concentration of depressants such as Nokes reagent and sodium cyanide on the rejection of pyrite, lead, and copper minerals were investigated. The metallurgical results indicate that, in the presence of depressants, the rejection of copper is strongly dependent on the pH. Preliminary mill testing confirmed the finding. The rejection of impurities is also dependent on conditioning time. The recovery of molybdenite is independent of the variables investigated.

Jan 1, 1981

By A. Taylor, E. Thorn Corthay, J. Farrell, L. A. Westfall, S. Borchardt

Mining and metallurgical industries need to minimize their greenhouse gas (GHG) emissions; Hatch specializes in conducting mining and metallurgical energy management assessments and optimizing productivity. Projects executed have demonstrated that there is a wealth of energy management, waste reduction, and process efficiency improvements that require no or low capital investment. Typical energy cost savings are on the order of 5% to 12%, with similar reductions in GHG emissions. Hatch generates Marginal Abatement Cost Curves to optimize the implementation pathway, maximizing carbon abatement and minimizing cost. The findings of a practical case study from Cameco are presented.

Jan 1, 2010

By Rajashekhar Marthi

Lithium is a key component for future electric vehicle batteries and energy storage. The future availability of lithium to meet the growing demands remains in question. Around 60% of lithium resources exist in the form of continental brines. Traditional methods to recover lithium from brines use solar concentration with precipitation and have found limitations in lithium extraction due to interference of Mg in high Mg/Li brines. Thus, there is a need for highly selective adsorbents. Recently, spinel structured delithiated lithium manganese oxides have demonstrated promising results. However, due to the small particle sizes, it is economically difficult to recover the adsorbents and thereby limits industrial applications. In our work, LiMn2O4 ion sieve was synthesized and immobilized on diatomaceous earth. Fundamental adsorption studies were carried out in lithium buffer solutions to understand the nature of adsorption and kinetics. The adsorbents were also tested for recycle stability, as well as recovery of lithium from Great Salt Lake water samples.