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By A K. Ghosh, J Chung, E Topal, M Asad

"Many open pit (OP) mines with considerable vertical extent are approaching the end of their life-of-mine; some of them are seeking the opportunity to make the transition from OP to underground (UG) mining. The decision on the best location for transition from OP to UG mining should be addressed at the strategic mine planning stage. Conservatively, the transition to UG mining is considered near or after the exhaustion of the reserve within the ultimate pit.However, if UG is evident and exclusively viable from the inception, defining the best location for the transition through a conservative approach may not be an optimal option to explore. This clearly establishes the need for a mathematical model that aims to maximise the project value and considers OP and UG mining with crown pillar (CP) requirement simultaneously. Underground mine layout varies from one UG mining method to the other, and consequently the variation in the location of transition is eminent. Thus, focus on the selection of UG mining method must be a part of this analysisThis paper presents an implementation of an integer programming (IP) based mathematical model that evaluates the changes in mining layout and the project value under possible variation in the transition point from OP to UG mining for stoping and block caving methods. An IP problem is a mathematical optimisation or feasibility method in which some or all of the variables are restricted to be integers. The outcome of the implementation reflects that mining strategies with OP transition to stoping and block caving methods generated higher values than OP-only mining strategy. The case study not only demonstrates the difference in mining layout for both stoping method and block caving method, but also reflects that a joint consideration of OP mining, UG mining and CP placement helps to achieve maximum project value and resource utilisation.Citation:Darbritz, J, 2016. Remediation of Wall Failure at Kalgoorlie Consolidated Gold Mines' Golden Pike Cut-back 2016, in Proceedings Ninth AusIMM Open Pit Operators' Conference 2016, pp 96–103 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 15, 2016

By Hiroshi Ono

"By newly developed ICP method, trace amounts of As(III), As(V) .,Sb(III) and Sb(V) were precisely determined within accuracy of sub ng/ml. As(III) and Sb(III) were separated from As(V) and Sb(V) by extracting into ·xylene as diethyldithiocarbamate complexes using diethylammonium diethyldithiocarbamate (DDDC), and then back-extracted into nitric acid for a quantitative determiruition by ICP-AES equipped with hydridegeneration system The recoveries of As(III) and Sb(III) were satisfactory throughout the extraction with 0.04mol/l DDDC in xylene from lmol/l hydrochloric acid solution and the back-extraction with 7 mol/l nitric acid. As(V) and Sb(V) were reduced to As(III) and Sb(III) by ascorbic acid and potassium iodide, and their quantities were determined as mentioned above. The detection limits were found to be 0.58ng/ml for As(III), 0.63ng/ml for Sb(III) using 50ml of a sample. The proposed method was applied to analysis of the real sample.Introduction In drain, arsenic(AS) concentration is prescribed below 0.lmg/l, so As must be removed. As is existed at .the form of As(III) or As(V) in solution. For t1Jeir difference of chemic;µ property, it is not easy to remove As in solution. So it is an urgent necessity to develop for determining concentration of As(III) and As(V). Antimony( Sb) has resemblance .chemical property to As. So Sb was experimented the same as As.The separation and determination of As(III) and As(V) have been carried out using several methods, such as ICP after copreclpitating separation, HPLC, direct hydride generation atomic absorption. However these methods have some problems. One of main problems is that HPLC and direct hydride generation atomic absorption methods are influenced by coexisting elements."

Jan 1, 2000

By B. K. Slone

The depth at which it becomes more economical to use slope access as opposed to box-cut access for near-surface coal reserves, termed "transition depth," can be established for a given coal property by considering cost estimates for those parameters that determine respective access method. Fourteen parameters that influence access cost were identified and ranges determined. A Transition Depth Formula was developed to permit determination of the better method of accessing a reserve, given such information as highwall slope, road width, total bench width, pit dimensions, road grade, belt component costs, pumping costs, and cost of overburden removal and reclamation. In most cases, in Appalachia, studies indicate that the transition depth ranges between 20 and 30 m.

Jan 1, 1998

By Donald R. Williamson

Statistical studies at Cyprus Pima Mine indicate that samples from 22 blastholes are necessary for determining average copper grades, within a desired range of precision, for mine-model blocks by arithmetic averaging. The average number of holes in such blocks is 14. Many considerations show that more holes will not be drilled for sampling. A way to determine block grades more reliably than by" arithmetic averaging was sought. Thus far arithmetic averaging has proven to be the best procedure for the particular operation characteristics despite the small number of samples. It naturally follows that expenditure of great effort in sampling blasthole cuttings is unwise.

Jan 1, 1977

By F. E. Senftle

Introduction The usual laboratory methods of uranium analysis are either tedious, time-consuming chemical procedures or elaborate physical methods requiring sensitive equipment. There is thus an urgent need for a method of estimating the uranium content of ore samples by approximate analysis in the field. When a new property is being developed, it is desirable to know, with the least possible delay, the uranium content of channel samples in order to guide the diamond drilling and digging operations. Prospectors, too, require approximate analyses of their hand specimens to evaluate their discoveries. To satisfy the demand for these types of analyses, several field procedures have been tried. Two general plans can be followed. One is fast but will yield only a rough estimate. The other is slightly longer but, if done carefully, will give an assay probably within 10 per cent of the true value. For field operation it is necessary to strip the more accurate laboratory methods of analysis of all refinements because of the limited equipment and skilled techniques at hand. Most of the corrections normally applied, with the exception of that for equilibrium, will not alter the gross analysis to any appreciable extent. When uranium atoms in pitchblende disintegrate, they break down into other radioactive elements, and eventually the number of elements being formed is equal to the number breaking down. The ore is then said to be in equilibrium. Certain geological processes, however, such as leaching, may selectively remove some of these elements and hence reduce the radioactivity of the ore sample. The ore is then said to be out of equilibrium. The field analysis may then be in error by as much as 50 per cent since the apparatus is calibrated with standards that are in equilibrium. However, such a large error due to loss of equilibrium is the exception, and in most cases uncorrected field types of analyr.is are justified.

Jan 1, 1949

By B. A. Slaker

The ability to detect and quantify ground movements in underground mine workings is of the utmost importance to the safety of miners and continuity of operations. Rib sloughage is one of the most common forms of underground deformation. Remote sensing techniques, such as laser scanning, can be used to quantify this rib sloughage, by recording precise, timelapse point clouds of mine workings. In order to determine sloughage volumes and locations, two sets of laser scans were performed 42 days apart at a working section of an underground limestone mine. During this period, significant sloughing and scaling occurred, allowing for differentiation between the initial and final point clouds. Volumetric changes of 2.3-2.6 m3 were detected on rib faces during the time-lapse study. In addition, displacement in the mine roof was, as expected, not detected, suggesting well surveyed scans and an appropriate scan resolution.

Nov 1, 2013

By Cynara Christ Klippel

Devido às exigências de teores de fosforo cada vez menores no aço, o processo de desfosforação tem ganhado destaque nas indústrias. Para aproveitamento das melhores condições termodinâmicas a etapa mais eficiente para o processo de desfosforação ocorre no ferro-gusa. Esse trabalho utilizou quatro misturas iniciais de composição definida com base na literatura, juntamente com o ferro-gusa para ser simulado o processo de desfosforação. A simulação foi feita através do software de cálculos termodinâmicos FactSage e através dos resultados obtidos do programa foram feitos cálculos para avalição da eficiência do processo. Além disso, também foram feitos cálculos baseados na literatura para comparação de resultados e estudo mais aprofundado dos resultados. Os resultados obtidos comprovaram a teoria inicial de que menores temperaturas favorecem o processo.

Aug 17, 2017

By Breno Totti Maia

A principal ferramenta de controle do processo BOF reside na regulagem dos parâmetros de sopro de oxigênio. As condições ótimas desse processo envolvem diversas variáveis, como vazão de oxigênio, distancia banho lança (DBL), número de furos para a saída de oxigênio na lança, entre outros fatores. Através de uma análise visual da penetração do jato e do volume movimentado, foram analisados os comportamentos para cada configuração de sopro entre diferentes combinações de bicos multifuros (3 a 6 furos), para uma distância banho lança (DBL) e vazão constantes. A análise dos parâmetros de interação entre o sopro e o banho líquido composta pelas frações de metal e escória, representados respectivamente por água e óleo de parafina é o principal objetivo deste trabalho. Foi necessário desenvolver nova metodologia para a determinação da penetração assim como proposta de nova fórmula e ajuste da constante empírica, fator K. As maiores penetrações foram alcançadas com os bicos de 3 e 4 furos. Para a configuração de 6 furos, foram encontrados os menores valores de penetração e maior volume de zonas de baixa movimentação em relação aos parâmetros estabelecidos.

Aug 17, 2017

By Roberto Carneiro da Silva, José Geraldo da Silva Moreira, Eder Quental de Araújo, Patrick Petronio de Castro Andrade

Os fornos de reaquecimento são equipamentos comumente utilizados na indústria siderúrgica para aquecimento de produtos intermediários produzidos pelo processo de lingotamento. A operação correta desses equipamentos pode ser medida através de sua produtividade, seu consumo específico e seu rendimento metálico. Isso se torna ainda mais desafiante quando se trata de fornos multicombustível, e de uma siderúrgica integrada de grande porte como é o caso da Gerdau Ouro Branco, que possui 5 fornos de reaquecimento para atender a 5 diferentes laminações onde a disponibilidade de gases combustíveis é variável para cada forno. Dessa forma, esse trabalho traz uma metodologia de otimização capaz de determinar qual a melhor mistura de combustíveis e Poder Calorífico Inferior do Gás Misto (PCIGM) para operar os fornos de reaquecimento em diferentes situações e necessidades operacionais e de produção.

Aug 1, 2019

By Verônica Scarpini Candido

O estudo da composição mássica de cerâmicas vermelhas é de extrema importância para a produção de peças com propriedades tecnológicas aceitáveis. Nesse contexto esse trabalho tem por objetivo determinar as propriedades tecnológicas de cerâmica vermelha para fabricação de blocos de vedação. Dois tipos de argila foram usados, argila forte e fraca, para a confecção dos corpos de prova que foram moldados por prensagem uniaxial. Após essa etapa foram determinadas a absorção de água e a resistência em flexão. Os resultados mostraram que a massa composta por 50% de argila forte e 50% de argila fraca apresentaram os melhores resultados de resistência à flexão. Assim, o estudo mostrou que todas as massas estudadas atendem aos requisitos mínimos exigidos por norma e que a massa composta pela mistura das argilas apresentou o melhor desempenho mecânico tecnológico.

Oct 30, 2017

By Josué Mesquita de Souza Junior

A concentração gravítica corresponde a uma das mais antigas e importantes formas de processamento mineral, sendo utilizada para beneficiar uma grande variedade de minérios. Neste contexto, a melhor maneira de investigar e prever resultados de processos gravíticos é a chamada “curva de lavabilidade”. Estas curvas apresentam a distribuição das partículas de um dado um material segundo as suas densidades e são construídas a partir de dados experimentais obtidos nos denominados testes de flutua-afunda. Para a realização destes testes são utilizados líquidos com diferentes densidades, os quais correspondem a substâncias muito tóxicas, voláteis, de difícil manuseio e, na maioria dos casos, muito caras. Além disto, por não existirem líquidos com densidades muito elevadas, os mesmos não podem ser usados no fracionamento de sulfetos ou óxidos metálicos, o que restringe o uso das curvas de lavabilidade a materiais leves. Pensando nisto, procedeu-se ao desenvolvimento do presente trabalho, cujo objetivo é apresentar uma nova metodologia para a construção das curvas de lavabilidade a partir da análise de imagens digitais. Com esta metodologia será possível construir curvas de lavabilidade de uma maneira mais rápida e segura, além de tornar possível a aplicação desta ferramenta para minérios que possuam partículas com densidades mais elevadas.

Aug 17, 2017

By James G. Lyons

All machines vibrate and make noise. An increase signals impending trouble. Vibration and noise analysis allows the condition of the machine to be determined without costly interruption in service for disassembly and physical inspection.

Jan 1, 1977

By K. D. Dill, S. D. Rosenthal

"This project analyzed the efficiency of incorporating the use of directional drilling technology into coal overburden blasting. Directional drilling is currently in use in the petroleum industry and it is believed that it will be a valuable asset in the mining industry. This project has shown that directional drilling can be a viable technology for use in the coal overburden removal process resulting in increased drill utilization and potential for cost savings. Future work regarding blasting and geotechnical evaluation should be performed to solidify the concept. INTRODUCTION Determine the Potential Drill Utilization Improvements and Rock Fragmentation Requirements Using Directional Drilling in a Coal Mining Overburden Highwall Application was a project funded by Atlas Copco Drilling Solutions (Atlas Copco) based in Garland, Texas. The project was developed and researched by Montana Tech of the University of Montana. This project was intended to show how the use of directional drilling can increase drill utilization, while decreasing costs, without sacrificing overburden blasting results. This paper discusses a review of the literature, the methods performed, conclusions and future work Background Atlas Copco theorized that an alternative approach to drilling a cast blast pattern would be beneficial to coal mining operations by increasing drill utilization and therefore, decreasing overall costs. Increasing drill utilization results in an increase in the amount of time the drill is being productive, more drill bit time in ground. Atlas Copco’s theory is that by incorporating directional drilling in the design of a cast blast pattern, a drill rig could drill multiple directional holes, which are the length of the cast blast, from a single drill set up. A drill goes through a series of steps to complete a blast pattern, these steps include: tramming to the hole location, leveling the drill, drilling the hole, cleaning the hole, and retracting the drill steel. This process is repeated hundreds of times until the whole pattern is completed. The most time intensive part of this process is drilling out the blast pattern. Integrating directional drilling into this process could decrease the overall time it takes to drill out a blast pattern by minimizing the amount of time spent tramming and setting up for each subsequent hole. Tramming and drill set up are two aspects of the drilling process where the drill tool is not engaged with the ground and, therefore, not being utilized. A cast blast pattern designed to utilize directional drilling will allow the drill tool to be “in the hole” longer and will improve drill utilization. This change in drill utilization was analyzed. Drilling and blasting is an integral part of the mining process, without it mining would be a slower process and less material could be mined. Drilling provides holes for explosives to be loaded and then blasted. Blasting has been found to be the most cost effective method of fracturing rock in mining for material removal. Blasting is also used as a low-cost method to move the rock in open cast mines, commonly referred to as cast blasting. A cast blast is a large blast designed to allow for the maximum amount of overburden to be removed using explosives in a single blast thereby uncovering more coal at a lower cost. Not all the material is blasted to cast-to-final, which requires that material to be moved with large mining machinery. Material that is considered cast-to-final is material that has been thrown far enough to never be moved again in the coal extraction process, therefore it is in its final resting place. A typical cast profile and cast-to-final area is shown in Figure 1."

Jan 1, 2017

Sampling protocols and metallurgical flow sheets should be designed to suit the style of mineralisation in question. In support, the a priori need for evaluation programs is the characterisation of the mineralisation type(s) and domain definition. The proportion and size of gold particles has a direct impact on the effectiveness of sampling protocols and metallurgical processes employed. Within the coarse- to-fi ne gold spectrum, the samplability of a deposit ranges from relatively simple for fine-grained disseminated particles, through to difficult for coarse gold mineralisation. Conversely, metallurgical processing may be relatively simple for coarse gold ore and more difficult for very fi ne gold ores. Most deposits contain a proportion of both particle size types. The nature of mineralisation, mineralogy and associated gold particle sizing can only be determined by preliminary sampling to facilitate testing. Mineralogical studies, focussing on ore mineralogy and gold particle deportment, size and distribution are required as part of wider paragenetic and geometallurgical investigations. This paper discusses key issues and presents a methodology for the determination of gold particle size in coarse gravity-gold ores to support sampling optimisation and which also contributes to metallurgical characterisation.

Aug 1, 2010

By E. Pourjenaei, P. Ghobadi

High Pressure Grinding Roll (HPGR) is efficient equipment in comminution process. HPGR could be a good option for preparing ball mill feed at the first stage of grinding due to its high efficiency and low energy consumption. Closing with a screen, these mills are utilizing as one of the principle parts in mineral processing industries, especially for iron ores. Recently, HPGRs are working as primary mills at 4 developing lines in Gol-e-Gohar Iron Ore Processing Complex, Iran. Different mechanism of particle crushing in compare to the other tumbling mills makes the HPGR as certain equipment with its own particular controlling parameters. Hydraulic pressure, roller speed and level of material inside feeding hopper are the most important variables influencing grinding efficiency of the HPGR. To figure out how they impress the process and operation situation, different industrial tests were carried out and the best result (d80 about 8 mm for HPGR discharge) was achieved at 180-190 bar pressure (P), 300 rpm speed (S) and 50% of hopper level (L). It is worth noting that this finding has been observed through past pilot test too. We also used design expert method (DX7 software) to develop the best design and analysis the test results, as well. According to the mechanical restriction of HPGR and process limitation in the plant (based on the industrial results), we adjusted value of each parameter in a logical range. Therefore, 20 industrial tests were conducted, as DX7 recommended, and the various impacts of the parameters and their interaction were identified based on statistical analysis. As the authors expected, it was revealed that after presser, roller speed is a critical variable because of its significant role in residence time of the particles between the rollers. The function below has been determined to explain the relation between different parameters and the response.

Jan 1, 2018

By R A. Pax

Operational grinding mills emit significant acoustic emissions which are a consequence of the dynamic environment prevailing inside them. From a technical perspective, the noise presents an opportunity to determine some details of the processes occurring inside the mills. The noise generated is not random and can be attributed to a range of events that occur inside these mills, consequently non-contact acoustic determinations of in-mill behaviour provide powerful insights into the operation of primary comminution tumbling mills. To enable a logically coherent picture to be formed of the processes inside a mill, arrays of microphones have been used. This approach allows a clearer picture of the in-mill behaviour of the charge to be accessed. In contrast to single microphone approaches, usually located near the expected charge toe position, an array of microphones allows much more useful information to be obtained from grinding mill noise.This paper will discuss and present data obtained from microphone arrays positioned at the toe and shoulder locations of a mill, and how this information can then be used for the optimisation of grinding mills in real-time.CITATION:Pax, R A, 2012. Determining mill operational efficiencies using non-contact acoustic emissions from microphone arrays, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 119-126 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By M. B. Kime, A. T. Kaniki

"Grinding tests were conducted on an oxidized copper-cobalt ore using a pear-shaped ball mill. Twelve mono-sized ore fractions were prepared and wet ground batchwise. The mill was run for 0.5 to 30 min intervals. The shortest interval provided data more closely related to the breakage function (B) because less secondary breakage was hypothesized. Some selection function (S) and B parameters were determined. Remaining parameters were estimated using a population balance model simulator. To evaluate the kinetics model, an unsized ore sample was also milled. Predicted and measured particle size distributions (PSDs) agreed well, suggesting that S and B parameters can be used for continuous operation mass balances.RÉSUMÉ Des essais de broyage ont été menés sur un minerai oxydé de cuivre-cobalt à l’aide d’un broyeur à boulets piriforme. Douze fractions de minerai de dimension unique ont été préparés et broyés en voie humide en lots. Le broyeur était mis en route à des intervalles de 0,5 à 30 minutes. L’intervalle le plus court fournissait des données plus étroitement liées à la fonction d’abattage (B) car d’après l’hypothèse avancée, le besoin d’abattage secondaire était moindre. Certains paramètres de la fonction de sélection (S) et de B ont été déterminés ; les paramètres restants ont été estimés à l’aide d’un simulateur de modèle d’équilibre de population. Pour évaluer le modèle de cinétique, un échantillon de minerai non calibré a également été broyé. Les compositions granulométriques (PSD, de l’anglais particle size distributions) prévues et mesurées correspondaient bien, ce qui laisse penser que l’on peut se servir des paramètres S et B dans le cadre d’équilibrages massiques en fonctionnement continu. INTRODUCTIONSize reduction of solids is a very energy intensive and highly inefficient process. It consumes approximately 5% of the electricity produced worldwide (Rhodes, 1998), and more than 50% of the total energy used in mineral processing plants (Walkiewicz, Lindroth, & Clark, 1996). An increase in grinding efficiency can therefore result in significant reductions in operating costs. This often amounts to determining the optimal design configurations for milling an ore sample in a laboratory mill under standard conditions. Prior to optimizing the milling stage, the requirements for downstream processing in terms of particle size distribution (PSD) need to be understood because low liberation and overgrinding will lead to future problems. Once this is done, it is also important to clearly understand the breakage properties of the ore. The kinetics of size reduction in tumbling mills are often determined using two probabilistic functions: selection and breakage (Austin & Luckie, 1972). Knowledge of the selection and breakage functions also enables the prediction of the PSD for a given ore sample."

Jan 1, 2017

By Jerry Tien

Mine regulators are normally used for proper air distribution in underground mines. They are deliberately introduced resistance in the regulated airway, and by altering sizes, they can distribute specific air quantities to regulated splits and free splits (4, 5). The enactment of the Federal Coal Mine Health and Safety Act of 1969, the Federal Mine Safety and Health Amendments Act of 1977, and the regulations adopted by the Mining Enforcement and Safety Administration (now called the Mining Safety and Health ministration) prompted greater discussions of optimal mine regulator locations because of the Act's stringent ventilation requirements (2, 3). For example, by requiring the separation of the air used in the belt haulage entries from the intake and return airways, the regulations required the creation of a third type of airway---the neutral airway, as opposed to the intake and return airways, adding to the complexity of a mine's ventilation network. It is the intent of this report to show that panel regulators should be located in intake airways at the neck of a panel for a blowing fan system and in return airways at the neck of a panel for an exhausting fan system in order to achieve optimal air control. A computer simulation model is used to determine optimal mine regulator location.

Jan 1, 1983

By Tapiwa Chenje, Victor Olivas, Peter Radziszewski

"Ore breakage and grinding media wear have always been considered and determined separately in laboratory tests. However the two processes are linked with the ore broken down in any comminution device being responsible for the majority of the steel wear experienced. The Comminution Dynamics Laboratory (CDLab) successfully developed a test methodology that can more accurately predict grinding media wear in tumbling mills than the Bond Abrasion test. This paper looks at the possible application of the abrasive wear methodology to determine breakage parameters of the same ore used in the abrasion test. Results indicate that breakage parameters comparable to t10 can be determined using the Steel Wheel Abrasion Test (SWAT), while using significantly less ore than standard breakage tests.BACKGROUNDThe Rubber Wheel Abrasion Test (RWAT) is an internationally accepted and widely used method for determining the abrasion wear behavior of materials. The abrasion wheel test was developed to primarily utilize a steel wheel (Brinell, 1921). Haworth (1949) criticized using of the steel wheel by arguing that increasing the contact area size in the steel wheel test causes a change in the wear rate with time. He suggested that the use of a rubber wheel instead eliminates this problem, leading to the adoption of the RWAT which was standardized in ASTM G65 (2004).Radziszewski (2002), however, found that the use of the Steel Wheel Abrasion Test (SWAT) was more applicable for wear testing in the mining industry for two critical reasons. Firstly, the major cause of wear in a ball mill, the most frequently used comminution device, is ball-ore-ball contact and also ball-ore-liner which both are metal-ore-metal contact. Therefore, using the steel wheel has the advantage of providing a similar abrasive environment to the one that takes place in a real ball mill. Secondly, the SWAT creates the potential of running experiments at much higher force regimes that are closer to what happens in actual mills, unlike the RWAT which is a low stress test."

Jan 1, 2011

By Michael David Harmse, Wiehan Adriaan Pelser, Jean Herman van Laar, Cornelius Stephanus Lodewyk Schutte

The South African deep-level mining industry is characterised by high operating costs and narrowing profit margins. Compressed air is commonly the largest consumer of energy in these mines, and any inefficiencies reduce profitability. Various methods aiming to optimise the compressed air networks have been implemented without an ideal economic dispatch strategy due to the lack of compressed air storage. In this study, a genetic algorithm was developed to evaluate the financial benefit of converting underground haulage to act as an air receiver (compressed air storage). By converting inactive haulage of 1.17 km in length into a volumetric air receiver, an annual monetary benefit of R2.5 million ($163 200) can be achieved, with a payback period of fewer than eight months. However, implementing the ideal size air receiver would result in an annual monetary benefit of R7.67 million ($500 700).

Jul 11, 2022