Search Documents

By Q. Zhang

The necessary capability of the gravity transportation pipeline system for cemented coal gangue backfilling at the Suncun Coal Mine, China, is about 74.4 m3?h-1 according to mining production and working times in the mine. It is estimated that the working velocity and maximum pipe length-backfill depth ratio of the backfill system are 3.82m?s-1 and 5.4, respectively and that the probable backfill capability of the system is 110.18m3?h-1. Results of hydraulic calculations for the backfill transportation system show that the designed backfill system is reliable in flowability and sufficient for backfill capability needs.

May 1, 2007

Grade uncertainty can have a number of important implications for a mining operation. One of the most significant risks in not considering grade uncertainty in planning is the over or under allocation of processing or mining capacity when compared to realised grades. This could lead to wasted capital expenditure or missed opportunities to add value. This paper demonstrates a method that optimises production capacity and mining schedules in the presence of grade uncertainty. Applying this method to the case study of a nickel deposit recommended a reduction in processing capacity, an increase in mining capacity and more extensive utilisation of stockpiles than optimisations completed with traditional methods. As a result, average NPV improvements of between seven per cent and 27 per cent were gained.

Dec 6, 2010

By Norman O. Lotter, Dominic Fragomeni, Lori J. Kormos, Guy Comeau, Antonio Di Feo

"A performance opportunity was identified for the Raglan concentrator operation by changing the selection of xanthate from Potassium Amyl Xanthate (PAX) to Potassium Isobutyl Xanthate (PIBX). This opportunity was identified by a Statistical Benchmark Survey of the operation and QEMSCAN measurement of these survey samples, in which fine liberated pentlandite was found in the final tailings. This was confirmed by some laboratory scale flotation testwork using High- Confidence Flotation Testing. A statistically designed plant trial was implemented in 2007 to measure and confirm the performance gain. This trial design used on-off switching following a three-month reference distribution of normal operations using PAX. This layout provided both external and internal reference distributions on PAX to be established. These were used to evaluate the internal reference distributions on PIBX. This trial format was deliberately designed so as to block out the effects of autocorrelation in the operations data. In this way, small but significant metal recovery gains may be measured and proven in a plant trial. The paper describes the case study to show that this approach successfully blocks out autocorrelation in time, which is an obstacle in analysing concentrator operations data. The results showed that the PIBX had produced clear and statistically significant recovery gains for Ni, Cu, Pt and Pd. Adjusted for feed and concentrate grades, these recovery gains were: Ni: 1.00, Cu: 0.96, Pt: 5.07 and Pd: 1.90%.INTRODUCTIONConcentrator OperationsMilling and flotation, sometimes accompanied by gravity separation, are well-established unit processes. These have traditionally been used to treat ore that has been mined, producing a lowbulk concentrate containing a high percentage of the paymetal(s) in the ore mined. These concentrates are more economically treated in subsequent beneficiation processes than the ore from which they were produced.This choice of a concentration process results in a significant and variable paymetal loss to the concentrator tailing. This tailing is discarded and disposed of in an impoundment area, and has no immediate business use. This paymetal loss forms the largest loss of paymetal in the entire flowsheet by which refined, or saleable, metal(s) are produced [Cramer, 2001]. The question arises as to whether any particular concentrator is performing at its full potential, and how this answer may be determined. In a concentrator operation, there is always an ongoing performance improvement programme for this reason."

Jan 1, 2009

By H. J. Modi, D. W. Fuerstenau

pH effectively regulates the flotation of corundum through its control of the surface charge. Since collector ions function as counter ions in the double layer, the collector must be anionic when corundum is positively charged and cationic when it is negatively charged. Even a long-chained xanthate will float positively charged corundum. Association of the hydrocarbon chains of the adsorbed collector ions gives rise to increased adsorption and increased rate of flotation. Because of this phenomenon, neutral organic molecules aid flotation although the unionized collector cannot promote flotation independently. Na2SO4 was found to depress the flotation of corundum with animic collectors through ionic competition whereas the same salt activates corundum for flotation with cationic collectors. A close connection between ion association, electrokinetic behavior, and floatability is suggested. As part of the increasing interest in the physical chemistry of flotation, strong experimental evidence has been obtained which indicates that organic ions are adsorbed as counter ions by non-metallic oxide minerals mainly because of the electrical forces which exist at interfaces(1-3). Thus flotation of such minerals without activation should then be appreciable only when the mineral and the collector are oppositely charged. Since only limited work has been reported on the effect of surface charge upon flotation behavior(3) this general hypothesis on the flotation of insoluble oxide minerals has not been tested thoroughly. Investigating the flotation of a mineral for which extensive electrokinetic data exist yields a way to test this hypothesis more extensively. The electrokinetic behavior of corundum in solutions containing both organic and inorganic electrolytes has been studied quite thoroughly' Electro-kinetic measurements have shown that in the case of corundum, simply by controlling pH the solid surface can be charged either positively or negatively. For this reason corundum was chosen for study. The object of this paper is to present a study of the flotation of corundum and to explain the results in the light of our knowledge of adsorption mechanisms gained from streaming potential investigations. This paper is concerned mainly with the effect of surface charge on flotation with anionic and cationic collectors, but in addition such flotation phenomena as collector hydrolysis, Van der Waals attraction between hydrocarbon chains, ionic competition, and activation are discussed. While the present paper is confined to a reporting of the data obtained and some of the more immediate conclusions, it will be seen that the results, in combination with those on other systems, do promise a

Jan 1, 1961

By Craig Compton

Falls of small pieces of rock from between roof bolts continue to cause fatalities and to injure hundreds of coal miners each year. Roof screen is the most effective way to prevent these incidents, but some mines are reluctant to use it because they believe installing screen can be awkward, expensive and time-consuming. The most common type of roof bolting machine used in mines today is the dual boom, outside-controlled roof bolter. Mines who install roof screen using these machines have developed some machine modifications and techniques to ease roof screen installation. This paper describes some successful techniques and machine modifications that are being used in productive mines to assist with roof screen installation. Since the material handling involved with roof screen installation can expose miners to an increased risk of musculoskeletal injuries, the National Institute for Occupational Safety and Health (NIOSH) ergonomists, designed machine modifications and implemented a series of tests to evaluate roof screen handling procedures for outside-controlled, dual boom roof bolting machines. Roof screen installation can also have a positive economic impact on a mine by reducing the cost of injuries, workers? compensation, required spot or re-bolting, and clean-up of long term travel and belt entries.

Jan 1, 2007

By Brigitte J. Dejou

The Red Dog sediment-hosted zinc-lead deposit is located in the Brooks Range thrust belt in northwest Alaska, approximately 1000 km northwest of Anchorage. The mine constitutes the primary deposit in a 400 square kilometre district, which hosts several other mineral occurrences. All the known mineralisation is hosted by the Mississippian Ikalukrok Member, deep basinal shale of the Kuna Formation, part of a Devonian to Cretaceous sedimentary sequence. The rocks underwent intense deformation during the Brookian Orogeny in Middle Cretaceous time. Several thrust faults juxtapose the stratigraphy. The Red Dog mine is composed of four deposits which together contain 105 Mt in resources and reserves for a total resource exceeding 18 Mt of Zn metal. The mine is an open pit with 25 foot high benches. The biggest challenge is not the Arctic conditions, but metal extraction, due to the fine grained nature of the mineralisation and the variability of the ore. The mine produces Zn and Pb-Ag concentrates that are shipped to smelters around the world from the Red Dog port facilities during the short summer period. Ore mineralogy is generally simple and consists of sphalerite, pyrite, galena and marcasite. The deposits are generally overlain by decametre thick exhalative barite horizons and exhibit strong silicification, which locally obliterates the original textures. Although described as a world class Sedex-type deposit, a large portion of the mineralisation exhibits sub-surface replacement textures. Moreover, unlike most other Sedex deposits, the reconstruction of the basin is made difficult by the structural complexity of the district. To assist exploration in the district, several assumptions are made regarding the deposit settings relative to metal source, growth faults or crustal extension.

May 1, 2006

Objective To develop safety training tools for mine safety and health trainers that can be used for both new-miner training and annual refresher training. Background For the past 3 years, NIOSH has been developing training materials for mine safety trainers in response to gaps identified during stakeholder meetings. Most materials have been directed to the hazards of underground mines, but the recent passage of Part 46 of CFR 30 required new-miner and annual refresher training in aggregate operations. One result was the identification of another audience needing basic information about safety in mining. Trainers characterized trainees in this segment of the industry primarily as young males, many of whom had little work experience. Approach Training specialists from the Arizona State Mine Inspector’s Office approached NIOSH researchers early in2002 about the possibility of a collaborative project to develop safety training materials for new trainees in aggregate operations. A preliminary search of MSHA accident statistics identified over a dozen common hazards that could be targeted in a training video. A storyline was developed for review by safety specialists in the aggregate industry, and a script was written to cover the selected hazards. Although the target audience was primarily new hires, the finished video was also to be relevant to more experienced workers.

Jan 1, 2003

By M. Leroux, P. Lacombe, S. R. Rao, J. Y. Kim, J. A. Finch, G. Labonté, N. Macminn, M. Ounpuu

"Laboratory investigations on two complex ores, the A1 zone ore from Les Mines Selbaie and the Lyon Lake ore from Mattabi Mines Ltd. (Division of Noranda Minerals), have been carried out to determine some of the main variables in collectorless flotation. In particular, the effect of pulp potential (controlled by gas composition), conditioning time, pH and grinding media have been studied.Chalcopyrite showed the greatest response to collectorless flotation among the four major sulphide minerals present, followed by galena. Flotation of sphalerite was variable from minimal to important depending on the mineralogy and the pre-treatment performed. Appreciable silver recovery was achieved collectorlessly for the Lyon Lake ore while it could not be achieved for the A1 zone ore of Les Mines Selbaie. It appears that the difference between the two ores is related to silver's predominance as tetrahydrite in the Lyon Lake ore while it is as argentite and native silver in the A1 zone ore.The response of the ores to collectorless flotation is strongly dependent on the pulp potential, Ep, and pH. Using different gas compositions and different conditioning times it was found that collectorless flotation occurs when Ep is +195 to +295 mv (vs SHE). The actual on-set potential for collectorless flotation is dependent on the ore. A too high potential or prolonged oxidation leads to a decrease in selectivity. Some other factors were examined, notably the effect of pH and the type of grinding media on the selectivity achieved in the laboratory.Preliminary results from a plant trial at Mattabi Mines Ltd. confirmed that collectorless flotation occurs and that it is preferential for chalcopyrite and to a lesser extent galena. Collectorless flotation was not attempted at Les Mines Selbaie. However, examination of the distribution of collector between the different addition points in the copper circuit suggests that it may be present."

Jan 1, 1990

By Darcey Baker

Quarry Blasting is usually boring, and that is how we like it. By this, boring means routine, straightforward, meat and potatoes blasting. Quarries typically will not utilize cast blasting, coyote tunnels, or any of the other more spectacular blasting techniques – just plain, old day-in and day-out quarry production and possibly overburden blasting. Differences in material characteristics, mining method, equipment availability, and target markets all play a part in determining the blasting procedures employed at any given location. However, variables exist everywhere and with foresight and planning, effects of tangible variables can be minimized. Variables caused by geology, weather, neighbors, or limitations caused by major plant or mobile equipment are, generally speaking, intangible; and leave the operator with finite options to improve or modify blasting procedures.

Jan 1, 2009

By William G. Szymczak

A set of experiments were conducted at the Aberdeen Proving Grounds [1] in which explosive charges were buried in saturated sand beneath a suspended rigid platform. The goal of these experiments was to measure the dependence of the impulse transmitted to the platform on the standoff distance and the charge burial depth. Simulations of these experiments were performed using the BUB2D axi-symmetric code using a frictional-cohesive visco-plastic model to describe the response of the saturated sand. This code solves a constrained set of conservation laws in which the liquid region (in this case saturated sand) is assumed incompressible. The explosion is initialized as a high pressure gas bubble (void) within the fluid. Comparisons of the simulations to the experiments are presented together with a study of the physical phenomenology associated with the loading process. In particular, it is shown that the force imparted to the platform is a combination of the impact of the sand on top of the explosion gas bubble and the pressure of the bubble as it expands before venting into the atmosphere. Under certain conditions, when the platform standoff is sufficiently small and the platform is sufficiently large, the bubble can over-expand before venting and pull the platform downward. This phenomenon was studied further through carefully measured and photographed small-scale experiments performed at the University of Maryland [2]. The small-scale experiments provide additional important validation benchmarks for our model.

Jan 1, 2005

By J. D. Miller, C. L. Lin

In the processing industries, it is well known that particle shape is an important factor which determines the behavior of particulate systems. For example, system properties of technological significance including rheology, suspension stability, agglomeration, packing, permeability…etc, are affected by particle shape. In this regard, characterization and analysis of particle shape is essential for more detailed understanding and improved development of particulate processes. In general, it is clear that the behavior of these systems depends on the statistical characteristics of particle shape. Remarkably few techniques exist to predict the mechanical and hydrodynamic behavior of an irregularly shaped particle or a population of irregularly shaped particles for that matter. The lack of models and correlations can be attributed to the wide variety and complexity of particle shapes, the difficulty of defining shape descriptors suitable for modeling, the limitations of measuring shape, and the lack of classifying techniques to characterize particle shape. In this paper, we present information on how 3D particle shape can be measured, characterized, and analyzed using cone-beam X-ray microtomography (XMT).

Jan 1, 2005

By Amanda Elioff

Success of the Gold Line Eastside Extension rail tunnels in Los Angeles has prompted Metro?s planning for two new rail lines to include underground alternatives. The Westside Extension Transit Corridor alternatives include up to 17 miles of subway to be constructed in soft ground. The routes will require construction in Los Angeles? ?Potential Methane Zone,? not considered for subway construction until recently. Slurry face TBMs will likely be specified. The Regional Connector, through the downtown area, includes one underground alternative with 1.7 miles of tunnel as well as three underground stations in soft ground and rock. Challenges will include tunnel and station construction under narrow streets. This paper will describe the alternatives, planning, geologic conditions and tunneling concepts for both planning studies.

Coal bursts are one of the least understood yet the most critical hazards in underground coal mines. The ground motions induced by seismic events can trigger unstable failure of coal and rock mass and degrade the surroundings of an excavation. Therefore, the characteristics of ground motions should be fully investigated for an improved burst risk management. This paper analyzes ground motion features of a longwall panel from a typical underground burst-prone coal mine in China. The results showed that most of the ground motions on roadways were hardly initiate coal bursts due to insignificant energy input to the damage. The intensity of ground motions in near-field zone were nearly 20 times higher than those in far-field zone. The strongest vibration on roadway was induced by a coal burst with energy of 28,600 kJ, which can cause ground motion of 0.77 m/s and equivalent dynamic stress of 14.69 MPa. The findings of this paper can improve the assessment of seismic risks and its management.

Jan 7, 2020

By Andy Fortin, André Vien, Christophe Bouché, Jeff McKay

"The technology and equipment design of the Twenty-first Century permit us to exploit low-grade ore bodies with milled tonnages reaching 300,000 tpd. Because of their substantial operational costs (energy, wear parts, etc) and precarious economic situations, the operations of today must maximize their metallurgical performance.The implementation of an Expert System becomes a logical avenue to pursue in view of increasing plant performance.Many operations, following the implementation of an Expert System, meet the objectives they determined before its integration; such as increased tonnage, stability, decreased costs, etc. However, they often cannot develop the full potential of the system due to certain factors that have been neglected or omitted during the implementation of the system.Three main elements have been identified during the implementation phase at INMET Mining Troilus Concentrator: 1- Instrumentation & Control 2- Software 3- Integration. Even though they have been clearly identified, these elements are often neglected due to lack of resources or lack of comprehension on the part of the operations personnel. This document will demonstrate, based upon our experience at Troilus and that of Metso Minerals, that we can identify and handle many factors which influence the profitability of the Expert System, for both short and long-term process control improvements.INTRODUCTIONThe Inmet Troilus Mine is an open pit mine, situated 175 km north of Chibougamau in the province of Québec, Canada. The mill, which started production in November of 1996, was originally designed to treat a gold – copper ore at a rate of 10,000 tpd.In early 1998, the mine plan called for a pit pushback and decreasing head grades for the following two years. With the price of gold nearing decade lows, the Troilus project was facing a major economical setback. There was a sense of urgency to reduce operating costs below the market price of gold. The mill team presented a project to management calling for an increase in mill throughput while minimizing capital expenditures and operating costs. This idea was supported by the existing mine plan, which called for a mine cut-off of 0.7 g/t Au and stockpiling low grade 0.5 g/t material for future milling."

Jan 1, 2003

By H. H. Dreissen, F. J. Fontein

The operating principle of the classifying cyclone has been described often but some special aspects of the cyclone receive further clarification here. In addition, several uses of the classifiers are summarized and made clear by means of practical examples. In coal and ore washeries, the washing cyclone is widely used for the separation by specific gravity of sizes up to about 12 mm. This application has lately been extended to the separation by specific gravity of particles up to about 50 mm. This use makes special demands on the construction and wear resistance of the cyclone. The sieve bend, a development of the Dutch State Mines which is less well known than the hydrocy-clone, is dealt with at some length. The sieve bend is an apparatus designed for wet screening. Attention is given to the variables influencing the performance of the sieve bend. Hydrocyclones are now so widely applied that it would be difficult to find an industry not, directly or indirectly, using them or knowing how to use them since publications on this subject abound.1-3,5,9-11,13-15 However, because of the large number of variables influencing the operation of classifying cyclones, it is not entirely possible to calculate the results of this type of cyclone. Therefore, a number of lesser known variables will be discussed here along with some special applications of the classifying cyclone. FACTORS INFLUENCING CYCLONE CLASSIFICATION Shape of Particles: The shape of particles may cause a much coarser classification than the one expected, considering the sieve analysis and the cyclone dimensions chosen. This was clearly shown by feeding a mixture of spheres and disks in water into a cyclone. The spheres were 0.36 mm diam and the disks, 3 mm diam and 0.03 mm thick. These dimensions were chosen in order that the disks and spheres might have the same rates of fall under gravity. Both spheres and disks had a specific gravity of 1.05. The results obtained with these particles in a cyclone are summarized in Table I. Test No. 2 shows that the catch of spheres was

Jan 1, 1963

By Peter Fischer

Between 45,000 and 50,000 claims for subsidence are submitted each year to the German hard coal industry. In order to improve the service to claimants a quality management was established in 2005. This paper describes the process now used for handling these claims. A quality check has also been carried out by way of a customer survey, which was performed by an independent research agency. The results of the survey are presented in this paper. In Germany, research into mining subsidence mainly involves the prediction of ground movements caused by deep mining operations. Special areas of research are subsidence reducing aspects of the extraction panel planning, especially from the point of view of mining dynamics, as well as securing and restoration measures. This work seeks to prevent or minimize mining-induced damages close to the surface, for instance, buildings or infrastructure installations (such as pipelines), or underground mine openings (e.g. shafts). Roof collapses and surface fractures caused by shallow mine workings of an earlier era currently constitute a special area of investigation.

Jan 1, 2006

By D. M. Wyslouzil

"Micron or sub-micron size gold inclusions in sulphide minerals cannot be extracted by conventional cyanidation. The gold surfaces must first be exposed by decomposition of the sulphides. As an alternative to roasting, pressure oxidation was found to be a most satisfactory method to decompose the sulphides and expose the gold particles. For cyanidation the pressure oxidation pulp has to be neutralized and stabilized with lime. It was found that thiourea can extract the gold directly from the pressure oxidation pulp without pH adjustment and oxidant addition. The main obstacles against the common use of thiourea are circumvented by a recently described control method of the emf during leaching.INTRODUCTION Amalgamation and cyanidation are the most conventional processes for gold extraction. The prerequisite for gold extraction is the possibility of gold surface to be contacted by mercury or by the cyanide solution. Encapsulated gold has little chance of contact and this leads to poor extractions.The reasons why a gold ore may be refractory are: micron or sub-micron size gold particles included in the sulphide minerals, such as pyrite and arsenopyrite; presence of and association with antimony, arsenic, tellurium and carbonaceous minerals. Some alternative processes, such as double oxidation(1,2), pretreatment with lime , H202, chlorine and Caro's acid, roasting and thiourea leach, have solved some of the problems of ""refractory"", but the sub-micron gold in sulphide minerals still shows little response. Roasting and the cyanidation of the calcine was one of the most successful approaches for this type of gold ore.There are two disadvantages to the roasting process: (1) the generation of sulphur, arsenic, antimony and mercury containing gases is undesirable and the control is extremely expensive; (2) gold particles might be fused in the roasted product and the oxidized base metals in the calcine might reduce the cyanidation efficiency. In recent years the pressure oxidation process has been considered as one of the more effective and satisfactory methods to decompose the sulphide minerals and expose the gold surface to the cyanide leach solution. The pollution problem could be better controlled and the gold extraction is more amenable."

Jan 1, 1985

By M. P. Hay

"For a model to be successful it must address the concerns and needs of a target audience. Further, the model must demonstrate the same patterns of behaviour as the real system, and need only be complex enough to meet this objective. If the model is too complex it can become unusable to those who need it most.With this in mind, SUPASIM has been developed for the practical metallurgist requiring only laboratory flotation rate data as input. Some 35+ successful plant simulations have been completed since 1985. The approach of SUPASIM is to characterise an ore, organise information in an understandable way and add structure to the complex flotation situation and hence support the metallurgist to interpret the relationship between variables and optimise the flotation process.The paper describes the basis on which the model was developed and sets out to provide an insight into interpreting laboratory flotation kinetics and their physical meaning in a production plant and the influence floatable gangue has on float performance and plant design. A case study illustrates how the ratio of slow floating mineral to gangue can influence circuit design and improve recovery on a plant scale.INTRODUCTIONThere is an enormous amount of useful data in the results of a laboratory scale rate test. Each variable of fraction and rate, for mineral, metal and gangue has a physical meaning in the plant. The link between float kinetics and the plant in respect of recovery, grade, pulp density, pulp flowrate, residence time, number of stages of cleaning and circuit configuration has been established by the author in the process of developing SUPASIM."

Jan 1, 2005

By S R. La Brooy, T Giraudo, I C. Ritchie

The treatment plant at the Macraes Gold Project in New Zealand processes a carbonaceous, refractory sulphide gold ore. Since its commissioning in 1990, there has been a programme of continuous improvement of the plant, leading to higher recovery, increased throughput and low operating costs. During this time, a number of processes for treating both, or either, the preg-robbing carbonaceous fraction of the ore and the refractory sulfide fraction have been evaluated, trialed and utilised. The latest phase involves the installation by Minproc of plant utilising Newmont Gold's Pressure Oxidation Technology, a process which is anticipated to mitigate both problem factors when commissioned in 1999.

Jan 1, 1998

By T. A. Ngcobo

Paper written on project work carried out in partial fulfilment of BSc Eng (Mining)degree The purpose of this report is to assess the risks faced by mines in dolomitic compartments in particular Kloof 8 shaft. The dolomites of the West Rand comprise one of South Africa?s most natural water resources, and overlie the reefs of the richest gold mines in the world. The pumping of water from the dolomitic aquifers to prevent flooding has caused the natural water table to subside, and the resulting cavities within the dolomite rock formations that overlie many gold deposits sometimes collapse, causing sinkholes. These impacts of the mining industry could worsen over time if preventative measures are not taken. This report discusses these impacts in detail, more specifically the risks to which operations in dolomitic compartments are exposed. A risk analysis was carried out to access the risks that the organization could face and it was this analysis that allowed one to examine the best methods to combat the problems. Other factors such as geological features and seismic events were also considered for the evaluation. To aid with the completion of this work various resources were utilized. A literature study was undertaken, information was gathered from various experts who specialize in dolomitic studies, evaluations were conducted and conclusions reached. The results from the project indicated that preventative measures should be implemented and correct procedures put in place to prevent any disasters.

Jan 1, 2006