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By G K. N Subasinghe

Metallurgists operating Knelson Concentrators (KC) often rely on manufacturerÆs recommendations for selecting operating parameters, such as fluidising water flow rate and cycle time. Recent studies have shown that these parameters are not only dependent on the machine parameters but also on the feed characteristics, such as size distribution of the gold and gangue particles and the composition of its constituent minerals. It is known that a particle entering a KC initially traverses a circular path within the bowl. For a particle to maintain a given orbit, the required centripetal force must be supplied by external means. It has been argued that this centripetal force, which is dependent on the mass of the particle, its radial position and the rotational speed of the bowl, is provided by the fluid drag force created by inwardly moving fluidising water and the BagnoldÆs force created by the particle/particle collisions. Depending on the fluidising water flow rate, one of two situations can occur where the porosity of the bed increases or decreases, which influences the amount of material retained within the bowl. The amount of material of a given size and density retained in the bowl is thus dependent on the extent of the centripetal force provided. Based on the above concept, a criterion that can be used to predict the amount of material recovered in the bowl has been derived and validated by experimental data. It may also be construed that this criterion demarcates the transition of the bed from a packed-bed state to a fluidised state. By identifying the transition values for the different constituent mineral particles in the feed, it is possible to estimate the optimal fluidising water flow rate that would maximise gold recovery while minimising gangue recovery. In addition, the kinetics of gangue displacement by incoming heavy mineral particles were also studied using synthetic mineral mixtures. The experimental data suggests that this process follows first order kinetics and that the build-up of heavy mineral reaches a maximum. A model has been proposed to predict the optimal batch cycle time for a KC in terms of the feed characteristics and machine operating parameters.

Jan 1, 2006

By J. D. Mooney, D. L. Darnell

The accompanying chart has been drawn for the convenicncc of engineers as' a means of quickly determining the correct number of plies of conveyor belts operating under specific conditions. The calculations are based on the average safe strength (factor of safety, 15) of the various standard rubber conveyor belts. The calculations assume maximum loading conditions; that is, the belt is considered as carrying the greatest load that it will handle without spillage at ordinary belt speeds. This not only produces the most economical operating conditions, but also the maximum tension in the belt. The chart is a graphical representation of the formula: Where, p = kg W(L + 10H) p = the correct number of plies k = a constant, depending on the type of drive g = the weight 'in pounds per cubic foot of material handled W = the width of the belt in inches L = the length of the belt in feet (approximately twice the center distance). H = the difference in elevation between the head and tail pulleys, in feet. For a simple drive, with a bare pulley, k = ----1 For a simple drive, with a rubber-lagged pulley, k = --- 1 For a, tandem drivej with bare pulleys, k = 1/375.000 For a tandem drive, with rubber-lagged pulleys, k = ---1 The chart is drawn for a simple drive, with a bare pulley (k — =e)1 ; therefore, the number of plies obtained from the chart should be multi- ' plied by the factor 0.83 or 5/6 for simple, lagged drive; the factor 0.67 or 2/3 for tandem, bare; and the factor 0.55 or 11/20, for tandem, lagged. The formula p = kgW(L + 10H) has been developed mathematically

Jan 1, 1916

By Jhony Mamani

El presente texto describe los casos de recuperación de recursos en rampas y taludes finales de un tajo abierto. El primer caso está referido a la recuperación de mineral en la rampa principal del tajo Chaquicocha, y el segundo, la recuperación de mineral en taludes de los tajos El Tapado y La Quinua.

Jan 1, 2017

By A E. Petts

Record iron ore prices and a renaissance of infrastructure in the Pilbara have Flinders Mines poised to move from explorer/developer to an iron ore producer. The potential of the company’s Pilbara Iron Ore Project was first highlighted by the announcement of Rio Tinto’s Caliwingina North deposit to the north and the Fortescue Metals group’s Serenity deposit in the southeast. The success of Flinders Mines’ exploration has been based on incorporating landscape studies into an existing geological framework, and using this to understand the iron-rich materials that were emplaced during the Tertiary. The development of the Delta and Eagle deposit resource models highlights this process. There are three main mineralisation styles at the project; detrital iron, channel iron and bedded iron deposits. They have textural and mineralogical similarities with comparative deposits in the region. Gaining an insight into the geological processes unique to detrital iron deposits and more distal channel iron deposits has been important to understanding the geometallurgy of the mineralisation. The model sits comfortably with other regional oregenesis models and allows a contextual framework to be developed around the timing of deposition of the Fe-rich detritus and pisolitic nodules that dominate the deposits. The exploration model also allows Flinders to explore more effectively for bedded iron mineralisation developed prior to, and since the development of the Tertiary weathering landscape.

Jul 11, 2011

By Zbigniew Lubosik, Stanislaw Prusek

"The main elements of hard coal extraction systems in the Polish mining industry, including the characteristics of gateroads, are described, followed by several dozen underground measurements of gateroad roof sag performed in different geological and mining conditions in Upper Silesia Coal Basin.Based on the analysis of the roof sag measurements, an attempt to describe the gateroad roof sag process using a geometrical model was made. To build the model, it was assumed that the roof sag curve could be described by three straight lines. The first line describes the roof sag ahead of the longwall face; the second line, the sag at the longwall-gateroad junction zone; and the last line describes the zone behind the longwall face. Determining the intersection points and inclination angles is essential for the model. These model parameters depend on the geological and mining conditions in the gateroad.Using the statistical computations and analysis, the dependencies between the characteristic points of the gateroad roof sag model and the selected geological and mining parameters were defined. The STATISTICA computer program by StatSoft was used for computation.This paper presents a simple form of the geometrical description of roadway roof sag progression that is very useful during the gateroad support design process.INTRODUCTIONThe longwall system with caving is the dominant method in European mining in cases of hard coal seam extraction. For instance, in Poland, in 2009, 117 longwalls were driven, with total production of 77.5 million tonnes. In roughly 95% of the longwalls, mining operations were conducted using longwalls with roof caving; the remaining 5% used the hydraulic stowing system. The average mining depth was about 700 m (2,297 ft), and average daily output per face was approximately 2,600 tonnes per day. When using the longwall mining system, gateroads play an important role. These principal roadways transport materials, mine crews, and output. In addition, they impact ventilation of the extraction area, affecting, among other things, the climatic conditions or methane hazard. Unfortunately, difficulties often appear in maintaining an adequate size for the gateroads, due to the face line, which causes origination zones with stress concentration around the gateroad, resulting in rock mass movements in the form ofroofsag, floor heave, or horizontal convergence (Figure 1)."

Jan 1, 2010

By D. Blackwell, W. R. Reed, G. Ross, S. Peters, M. Shahan

Dust collectors for roof bolting machines generally use a dry box to collect the roof bolting material. Recently, an underground mining operation converted a dry box dust collector to a wet box dust collector with a unique exception from MSHA for testing purposes. Water is routed to the roof bolter from the main water line of the continuous miner. The wet box utilizes a water spray to wet the incoming material. Testing was conducted comparing the two different collector types. Respirable dust concentrations surrounding the roof bolter with the different collection boxes were similar. The main difference in respirable dust concentrations occurred when cleaning the dust boxes. The average respirable dust concentration during cleaning of the wet box was 0.475 mg/m3, and during the cleaning of the dry box the average respirable dust concentration was 1.188 mg/m3. The silica content of the roof material was high, ranging from 28.9% to 52.7% during this study. The results from this study indicate that using the wet box as a collector reduced exposure to respirable dust up to 60%when cleaning the collector boxes. INTRODUCTION Currently, the dry vacuum dust collection system is the standard dust collector on roof bolters in underground coal mining. It has been proven to be an effective dust control to prevent roof bolter operators’ overexposure to coal mine respirable silica dust during roof bolting operations [Potts eta l, 2011 and Colinet, 2013]. The dry collection system works as follows: drill cuttings are vacuumed into the precleaner. The precleaner dumps oversized material onto the mine floor while undersized material enters the dust box via vacuum airflow produced by a blower. The cuttings entering the dust box are either deposited on the floor of the dust box or into a dust collector bag. The vacuum airflow leaves the dust box through a final filter which removes any small particles from the airflow. Figure 1 shows the internal view of two dry collection system boxes; one that does not use the dust collector bags and another that uses the dust collector bags. Dust collectors that use dust collector bags to contain material inside the dust collector box have been shown to provide better protection to roof bolter operators than dust collectors that do not use the bags [Listak and Beck 2008]. The dry collectors are very efficient at reducing respirable coal mine dust exposure from roof bolting activities. Recently, Blue Mountain Energy’s Deserado underground coal mining operation, outside Rangely, CO, made a modification to the dry collector system to convert it to a wet collector system with a unique exception from the Mine Safety and Health Administration (MSHA) for testing purposes. The wet collector system still uses a vacuum system to pull material from the vertical roof bolt hole, but incorporates a water spray nozzle located inside the dust box to wet the incoming material. The flow through the nozzle ranges from 1.9–7.6 lpm (0.5–2.0 gpm) at 0.69 MPa (100 psi). The conversion to the wet collector system removes the precleaner and the cyclones inside the dust box. The wet material (sludge) then empties through a specialized valve in the bottom of the box. The final filter is still used to prevent respirable dust from leaving the dust box through the exhaust. During operation, the wet collector dust box is opened and hosed clean after roof bolting every place. After every two entries the final filter is changed out. Figure 2 shows the inside of the wet collector box.

Jan 1, 2019

By J. G. Eacott

This paper reviews the role of oxygen potential and the advances that have been made in the application of tonnage oxygen in copper smelting. Brief reference is made to reaction kinetics before attention is turned to the thermodynamic considerations in copper melting to illustrate the importance of oxygen and. oxygen potential in the component parts of the overall smelting process. The chemical potential diagram for the Cu-Fe-S-O-Si02 system is used to elucidate the difference b etween the conventional matte smelting process and the modern continuous processes. A progressive oxidation scale' is constructed to show the common elements which exist, and the matte grades produced, during the smelting of concentrates to blister copper in commercially available copper smelting processes and those under development. The common route in producing blister copper from molten mattes, regardless of process, is illustrated on the Cu-Fe-S equilibrium phase diagram. The essential features of oxygen enrichment, in terms of its effect on combustion conditions (i.e. oxidation of fuel and sulphide minerals) and the heat balance are outlined. The benefits of oxygen enrichment are listed. The influence of tonnage oxygen and its effect on productivity, fuel savings, gas volume and strength in various copper melting processes are examined as a state-of-the-art review. Reference is made to the economics of tonnage oxygen utilization.

Jan 1, 1983

By David Fernando de Carvalho

Este estudo de caso foi solicitado por uma grande mineradora brasileira à Chemtech Engenharia, com o objetivo de avaliar um projeto de um Transportador de Correia de Longa Distância na fase conceitual, onde se buscava a otimização do consumo energético, mínimo investimento financeiro inicial e redução dos custos operacionais. O resultado deste estudo de caso foi usado como diretriz no projeto básico do equipamento, além de ser usado como referência para outros projetos similares.

Sep 25, 2017

By R. C. Miranda

Flotation is an operation widely used in mineral processing because of its aptitude to recover minerals of interest very efficiently. Flotation is often responsible for making possible the exploitation of mineral deposits of low concentration. In flotation various processes phenomena occur, some of which have still not been explained scientifically. Due to this fact, there are no models that can be widely applied in flotation control. Thus, in most cases, the control is done by experienced operators who are able to visually classify the types of foam into different categories and each one of them is associated with an operating actuation. In this situation, image analysis is configured as a solution that has already been employed in several ways. In this paper, a control strategy based on the colour of froth on a direct flotation of a nonferrous metal is presented. Moreover, the paper reveals the theoretical basis of the method, the critical points, difficulties and improvements that can be implemented. Data of grade were collected from the mineral of interest and RGB (red, green and blue) data of final concentrate of the froth. The mineral grade was collected and analysed during one month of operation and RGB was obtained using a camera. It was verified that the red colour showed the same trend of the grade curve in the concentrate. Thus, the use of this online data in optimising control was introduced. The laboratory grade is used to calibrate the colour set point. Therefore, it was possible to monitor in real time the trend of enrichment and depletion of a non-ferrous mineral in a flotation. It was possible to establish an online control strategy based on simple data acquisition. The result was an increase of 10% on production.

Sep 1, 2012

By J Player, G Sweby, S Webber, E Jones

Seismic systems are a tool for the monitoring and forecasting the rock mass response to excavation. Common issues encountered at mine site audits and reviews are: how to design an effective seismic system, implementation of the design, interpretation of seismic source results and understanding the reliability of the seismic source. These issues are often a function of several items including: • Experience of site personnel in undertaking seismic system design. • Personnel not envisioning multiple phases of system expansion to understand system robustness issues. • System design/expansion occurring in response to damaging seismic activity rather than planned expansion of a system • The mine access development is often localised in comparison to the total orebody being mined hence, planning sensors in longholes in advance of development rather than in short holes close to development will improve the three-dimensional aspect of the network. • Limited site processing of the seismic event data, hence engineers do not see the uncertainty associated with event location, size, source and system layout. Mine site users require a framework to appreciate the challenges and limitations in locating large events. For example, event locations are given as precise measurements (to the nearest centimetre) whereas the volume of deformation resulting in the event often has dimensions of tens of metres or more (as defined by the source radius). A stronger awareness of the uncertainty of rock mass yield within large seismic sources will assist site users in the interpretation of rock mass damage. The encountered design and implementation errors are reviewed and discussed with a practical set of rules presented to provide a robust seismic system that provides consistent results and increases the user’s understanding of uncertainty in source location and size. The authors’ experience across multiple mine sites, seismic systems and damaging seismic events over a 30 year period has been summarised into practical rules for site personnel of all experience levels.

Nov 29, 2022

By Jan M. Mutmansky

Simulation is a general term which commonly appears in the technical literature and which can have different meanings to different people. One interesting definition (9)* applicable in an engineering context is the following: "Simulation is the use of a model to study a problem." In most cases, the model referred to in the above definition is a simulation model constructed in a computer language and implemented on a computer in order to solve the problem under consideration. The application of computer simulation models to the study of problems in materials handling and earthmoving has been successful in the past. Generally speaking, this method has been used where the system to be studied has many variables and where the ability to predict the outcome of the system under different sets of conditions is difficult. The prime reason for using such a model is to evaluate the numerous likely ways of operating any particular system without the necessity of actually conducting full-scale field tests. The simulation model presented here is such an application made to the process of tunneling and, in particular, to the process of tunneling with a boring-type tunneling device. At first glance, the process of tunneling may not appear to be particularly complex and susceptible to study by a computer model. However, a close analysis of the tunneling process will reveal that it is rather complicated as a result of limitations placed upon the system by restricted space in the tunnel, geologic variations along the tunnel

Jan 1, 1972

By M Jones, G Corder, A C. Keith

"Sustainable development has become an issue of ever increasing importance to the mining industry. The Ernst & Young (EY) mining industry risk radar regularly shows several sustainability elements in the top ten risks, with social license the number three risk in the 2014/15 survey. This is supported by the Fraser Institute survey results of 2013 showing that 36 per cent of responding companies indicated public opposition had affected their permitting and approvals process.Addressing these issues in a strategic way across a mining business that is then translatable to actions at operational level has remained an elusive goal in the industry. In addition the environment and community issues are commonly viewed as somewhat separate from financial and production issues and as a compliance cost rather than a value add. In their Harvard Business Review paper of 2011, ‘Creating Shared Value’, Porter and Kramer outline changes in thinking required for companies to improve their business sustainably through considering the societal issues impacted by their operations and products. Along the lines of ‘doing more with less’ companies’ value chains can be redefined to reduce energy, transport, water or other resource usage leaving additional resource for societal usage and/or reducing environmental impacts. This paper explores the linking of the holistic Five Capitals-based approach with the creating shared value (CSV) concept to help businesses unleash the benefits of innovation. Previous papers have demonstrated the potential for Five Capitals approach to create strategic value through sustainable development. Building on previous work, this paper provides an overview of the current status of holistic approaches to mine management and presents the application of the CSV concept on an African mine currently undertaking capitals-based strategic planning. The paper also demonstrates the value that has been created through utilising this approach and proposes improvements for changing the way the industry tackles and delivers benefits related to sustainability issues.CITATION:Keith, A C, Corder, G and Jones, M, 2016. Strategic sustainable development – creating shared value in the mining industry, in Proceedings International Mine Management Conference, pp 249-264 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 22, 2016

By Donald C. Strimbeck

The Bureau of Mines, U.S. Department of the Interior, is conducting research and development on a coal-burning gas turbine. This work includes the development of (1) turbine blades resistant to coal ash erosion, (2) equipment to feed coal under pressure to a turbine, (3) an efficient combustion system, and (4) equipment to remove coal ash from the gases that drive the turbine. Initial emphasis is being placed on testing the first turbine ever equipped with blades designed specifically for use with coal as the fuel. Operating tests with this turbine are now in progress. This paper describes the Bureau's coal-burning gas turbine development program and progress on this operating test.

Jan 1, 1964

By E. W. Williams

THE Ontario Research Foundation has developed a process for producing low-density steel shapes by direct reduction of iron oxide powders. The process is a combination of reduction, sintering (without compaction), and carburizing, and has been described by Cavanagh (1). Iron oxide powder, in the form of mill scale or highly concentrated iron ore, carefully sized, is poured into a porous mould. A reducing agent, generally coke breeze, is placed around this mould in a heat resistant sagger which is sealed off and heated to 2,000°F. for a number of hours. The coke/ ore ratio, the particle size distribution, the temperature and time of soaking, and the size and shape of the reduced product, determine the densities and carbon contents attained. The Defence Research Board sponsored a programme of research into some of the mechanical properties of the material (which was named Controlled Density Steel) and this paper is an account of various factors which govern the tensile strength of the steel. The ?practically attainable range of density is from 1.5 to 5.5 gm./ cc. but higher densities are obtained on hot working. This paper, however, is restricted to discussion of results for moulded products.

Jan 1, 1957

By Guilherme Silva Costa

A utilização de uma matéria prima renovável que possa substituir os asfaltos utilizados para pavimentação, provenientes do petróleo torna-se algo que pode ser viável ambientalmente. A produção renovável de bioprodutos através do craqueamento térmico de óleos vegetais gera um rejeito conhecido como produto líquido orgânico (PLO). O objetivo deste trabalho é obter uma metodologia de produção de ligantes asfálticos a partir do produto de fundo proveniente da etapa de destilação do PLO oriundo da reação de craqueamento do óleo de palma em uma unidade piloto de produção. Foram caracterizadas quatro amostras (produto de fundo sem tratamento térmico, produto de fundo com tratamento térmico a 375°C durante 15, 30 e 45 minutos) para obtenção da metodologia na qual os resultados seriam os mais aproximados dos valores específicos dos ligantes asfálticos derivados de petróleo. As análises dos dados possibilitaram observar a amostra com tratamento térmico a 375°C durante 45 minutos consumiu muito material, porém obtive resultados aproximados aos especificados pelo CAP 150-200.

Aug 16, 2017

By Zhu Yangge, Zheng Guibing, Hu Xiaoxing

"Because of the similar crystal structure and surface properties, it is very difficult to realize the efficient separation of magnesite and dolomite by flotation, which is the main reason restricting the utilization of magnesite resources with dolomite symbiotic. To deal with a magnesite resources with high content of calcium impurity in northwest China, a novel decalcification technology by combining flotation with leaching is proposed in this paper. In flotation process, a novel flotation collector with good efficiency and low temperature resistance was developed, and the depression effect of sodium hexametaphosphate was investigated. In leaching process, the leaching rate difference of calcium and magnesium was observed. By industrial test, from the magnesite ore with MgO content of 43.96%,the grade and recovery of obtained concentrate ( calculated by MgO) are 47.28% and 67.68% respectively, at the same time, CaO content decreases from 3.91% to 0.30%, which means that more than 95% of CaO impurity is removed.INTRODUCTIONMagnesite is one of the main raw materials for the production of refractory materials, and it is widely used in metallurgy, chemicals, ceramic, construction and other industries. China is the most important supplier of highquality magnesite resources, accounting for about 60-70% of the world's identified supply of magnesite products is provide by China (Jewell, 2014). In recent years, high-quality magnesite ores can be directly used are going to run out in China, and the utilization of magnesite resources with high impurity content have drawn more attention.The main purpose of purification for magnesite is to remove SiO2 and CaO impurities which affects the strength of the refractory material. Flotation is the commonly used method to remove impurities in magnesite ore. Reverse flotation with cationic collector is usually adopted to remove silicon containing impurities, and a great deal of literature has been reported (Santana A. N. and Peres A. E. C., 2001; Wang and Sun, 2008; Zhu et al, 2014; Wu et al, 2015; Ivan B. et al, 2017). But when the major gangue component is dolomite, it is very difficult to realize the efficient separation due to the similar crystal structure and surface properties between magnesite and dolomite. To solve this problem, researches have studied the surface properties of magnesite and dolomite, such as wettability, electrical property, solubility and solution chemistry (Nermin and Nurgul, 2006; Nermin 2006; Ozbek and Abali, 1999; Lacin et al, 2005; Bayrak et al, 2006; Bakan et al, 2006; Chen G. and Tao D., 2004), but the commonly studied direct flotation using oleic acid as collector is still hard to receive an ideal effect."

Jan 1, 2018

By B. McNulty

The Niblack polymetallic volcanogenic massive sulfide deposits are located on Prince of Wales Island in southeast Alaska, approximately 50 km southwest of Ketchikan. The property hosts a number of polymetallic volcanogenic sulfide occurrences within the folded Lookout rhyolite volcanic succession. The Lookout deposit is the primary focus of current resource delineation and contains an indicated resource of 4,136,000 tonnes at 1.13% Cu, 2.32 g/t Au, 2.27% Zn, 38.70 g/t Ag and an inferred resource of 1,736,000 tonnes at 1.09% Cu, 1.77 g/t Au, 2.02% Zn, and 25.52 g/t Ag as of March 2011. Sulfide mineralization is interpreted to have formed sub-seafloor, within permeable felsic fragmental volcanic rocks. Sulfide minerals of economic interest include chalcopyrite and Fe-poor, Zn-rich sphalerite. Of considerable importance, the Lookout deposit contains elevated gold that occurs as inclusions within the base metal sulfides.

Jan 1, 2012

By H. C. Seeber

When considering all the aspects of a viable mine plan, it is important to estimate the accurate cost of mine ventilation, which varies as a function of airway dimensions, fan selection and ventilation network. Optimization of the overall elements of ventilation design can lead to very significant cost savings when capital and operating cost savings are considered in combination. This paper will describe a methodology, whereby ventilation costs can be minimized by optimizing the ventilation aspects of mine design and fan selection, by providing a brief description on ventilation theory and the factors which affect ventilation operating and capital costs.

Jan 1, 2002

By Michael E. Henderson

Presented in this report are the experimental results of coarse coal slurry degradation data obtained from the Hydraulic Transport Research Facility (HTRF) at the Pittsburgh Research Center (PRC), Bruceton, PA. The facility is operated by Boeing Services International, under Bureau of Mines Contract No. J0333956. Presented in this report are the experimental results of coarse coal slurry degradation data obtained from the Hydraulic Transport Research Facility (HTRF) at the Pittsburgh Research Center (PRC), Bruceton, PA. The facility is operated by Boeing Services International, under Bureau of Mines Contract No. J0333956. This particle degradation report is a summary of the particle distribution data obtained at the HTRF for the period 26 November 1982 to 1 October 1983. The testing covered herein is for coarse Pittsburgh Seam coal in the 6-in (150 mm) and 12-in (300 mm) pipelines, at velocities ranging from 5 to 18 ft/s (1.5 to 5.5 m/s), and at concentrations by weight ranging from 15 to 55 pet. Particle size distribution samples were taken systematically throughout the testing.

Jan 1, 1985

By H. P. Hermance

Preliminary examinations of the Parker and Webb deposits were made by E. E. Maillott, Bureau of Mines engineer in July 1942. The chemical and spectrographic analyses included in this report wore made at the Eastern Experiment Station of the Bureau of Mines at College Park, Md., under the general supervision successively of S. M. Shelton and of Paul M. Tyler, formerly regional engineer, Eastern Region. Beneficiation tests were conducted under the supervision of Frank D. Lamb. The mineral exploration was under the general supervision of J. D. Bardill, formerly district engineer. Acknowledgment is gratefully made to the St. Joseph Lead Co., in particular to John S. Brown and P. J. Mechin for their assistance. Special acknowledgment is made to the American Metal Co., Ltd., ,Ind to T. C. Moore for furnishing core-drill and assay data; to the Universal Exploration Co. and P. B. Jennings; and to the Northern New York Mining Corp. and C. H. Sprague for their permission to publish the core-drill dta. Excellent cooperation was given by Dr. W; M. Agar and C, L. Rogers of the Geological Survey.

Jan 1, 1949