Search Documents

The Curtin University Gold Technology Group has been involved in surveying, modelling and optimisation of batch centrifugal concentrator type gravity circuits and CIP/CIL circuits for nearly two decades. The most commonly asked question regarding gravity recovery is, “What is the benefit of a gravity circuit”, which can be hard, if not impossible, to quantify. With the help of the AMIRA P420 Project’s Integrated Liberation Leach Model (ILLM) it is now possible to evaluate the effect of gravity recovery on total gold recovery when changes are made to the grind size, gravity and/or leach/adsorption circuits. This paper demonstrates how the ILLM can be used to determine the net benefit of introducing or modifying a gravity circuit and assess the effect of operating conditions (grind size, coarse gold size distribution, leach residence time, carbon activity, etc.) on plant performance.

Jan 1, 2017

By Gino Merello

Dado que los cargadores frontales LHD son los equipos encargados de extraer gran parte de la producción en la mina subterránea El Teniente, se justifica el estudio de confiabilidad, mantenibilidad y disponibilidad que permita optimizar la actual estrategía de mantenimiento. En ese sentido, el presente texto señala la optimización de la estrategia de mantenimiento a través de la metodología de revisar continuamente los parámetros básicos del motor diesel y la condición físico-química del lubricante de motor. También se monitoreó con una frecuencia de dos días el estado general de los equipos, con el fin de detectar prematuramente algún tipo de daño que se derive de la implementación de la nueva estrategia.

Jun 1, 2014

By S Q. Zhao, J H. Wei

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. The Xitieshan lead-zinc deposit is located in the north margin of the Qaidam Basin, Qinghai Province, China. It is one of the largest massive sulfide deposits in China and is supposed to be of the sedimentation-exhalation (SEDEX) type. Based on the main ore mineral and sulfur isotopic compositions in sulfides found in the wall rock, the S of the deposit is considered to originate from the mantle, but the fluid potentially mixed with sea water during the hydrothermal circulation exchange. The study of lead isotopes shows that the metallogenic material is characterised by the mixture of orogenic and upper crust sources. The lead isotopic signature of the wall rock is similar to that of the ore, which shows synsedimentary characteristics. According to the composition of the rubidium and strontium isotopic signature, the value of 87Sr/86Sr is lower than the average value of that in the crustal rock, which is larger than that of the mantle. Hence, the metallogenic materials of this deposit mainly originate from the crust, which is related to materials of volcanic rocks activation and migration of the deep hot circulating water. The process of the metallogenic fluid circulation shows continuous interaction with crustal material and lead to continuous enrichment of the ore forming fluids. From the study of the fluid inclusion microthermometry of the ore and the associated minerals combined with the C, H-O, Si isotopes, it is believed that the metallogenic fluid is mainly coming from the mantle or the deep magma chambers. The rising deep fluid then mixes with the sea water. The carbon dioxide escaping and mixing with sea water during the hydrothermal exhalation process leads to the rapid precipitation of the hydrothermal fluid to deposit metal. That is proposed as the principal formation mechanism of the Xitieshan deposit. Further studies are proposed, including obtaining geochronology data from this deposit.CITATION:Zhao, Z X, Wei, J H, Liang, S N and Zhao, S Q, 2015. Advances in research on metallogenic mechanisms for the Xitieshan sedimentation-exhalation lead-zinc deposit, Qinghai Province, China, in Proceedings PACRIM 2015 Congress, pp 487–494 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By J. A. Farinelli

In the Appalachian region of the United States, approximately 40% of the underground coal reserve base exists in seams 0.7 - 1.1m thick. These seams are, in general, often of premium quality and are frequently accessible through above-drainage drift-type openings. Unfortunately, there are no apparent advantages to mining thin seams, if quality is disregarded. The thin-seam mine is faced with the same legal and economic pressures as any other underground coal mine. But in addition to these common problems, thin-seam operations must also deal with the unique problems associated with mining at such a restrictive height. Small-scale, short-lived operations appear to be the most feasible means of mining these reserves. The purpose of this paper is to evaluate the production and safety potential of various thin-seam mining systems. Recommendations will be made regarding present and future thin-seam operations.

Jan 1, 1987

By M. Saunders Macdonald

A number of open pit gold mines in Nevada extract ore from areas below natural groundwater elevations, necessitating dewatering and some method of disposal of the extracted water. These open pits extend well below the water table, with associated dewatering volumes greater than 10,000 gpm. Some mines, with large volumes of dewatering water to manage, have constructed re-infiltration basins to re-introduce dewatering water to the groundwater system some distance from the pits. This paper presents an overview of the state of the art of re-infiltration projects, including the permit process for such projects in Nevada, and the necessary engineering considerations.

Jan 1, 1996

"Hematite pellets were electro-deoxidized to iron in molten sodium hydroxide to produce iron containing about 10-wt % oxygen. The anodic reaction was the evolution of oxygen on an inert nickel anode. Before the electrochemical reaction, there is a reaction between sodium hydroxide and ferric oxide to form sodium ferrite and, in order to compensate for the reduction in sodium oxide content, 1 wt % sodium oxide is added to the melt. In a laboratory cell, the cell voltage was 1.7 V with a current density of 5000 A m-2, a current efficiency of 90% and an energy consumption of 2.8 kWh kg-1.Introduction The iron and steel industry contributes about 2.3 bn tonnes/annum of the carbon dioxide to the atmosphere, which is about 10% of the total, and some believe that, in order to prevent a catastrophic rise in the earth’s temperature, carbon dioxide emissions must be reduced by 50% come 2050. However, by 2050, it is likely that the iron and steel industry would have grown significantly so that the production may have risen to 2 or 3 bn tonnes/year so in order to meet the 50 % reduction on today’s figure, the carbon dioxide may have to be reduced to 25% or less, which is a very demanding requirement. There are probably three ways of reducing the carbon dioxide output:1. By capture and sequestration, but this may be technically very demanding.2. Reduction using hydrogen in place of carbon."

Jan 1, 2009

By D Michaelsen, S Miller

The Grasberg Mine is a copper and gold open pit mine operated by PT Freeport Indonesia (PTFI) and located in the high equatorial mountains of the Indonesian province of Papua. The climate is alpine/subalpine with little seasonal variation in temperature or rainfall. The daily average temperature ranges from about 2¦C to 14¦C and the annual rainfall in the vicinity of the mine and overburden stockpiles is about 4000 mm to 5000 mm. Mining of the Grasberg open pit will continue until 2014 at which time approximately 2750 Mt of overburden will have been produced. Current overburden production rates are 200 Mt per annum. The current mill rate is 230 000 t/day from the Grasberg pit (190 000 t/day) and the underground operations (40 000 t/day). The acid rock drainage (ARD) issues associated with overburden from the Grasberg operations were identified early in the mining operation. Almost all overburden placed to date has been Potentially Acid Forming (PAF). Laboratory testing has identified four main overburden types: limestone and non-acid forming (Green waste), PAF low capacity (Blue waste) and PAF high capacity (Red waste), and Heavy Sulfide Zone (HSZ), which contains greater than 20 per cent pyrite. Waste type block modelling indicates that at least 30 per cent of the overburden production from 2003 to the end of Grasberg pit operations will be limestone. Strategies are being developed to maximise the beneficial use of limestone through strategic blending and placement for ARD mitigation and control.

Jan 1, 2003

By Asbjørn Solheim

The service life for aluminium reduction cells is often limited by the cathode carbon, due to preferential wear along the periphery of the cell leading to the so-called "W" wear pattern. The reason for this preferential wear is not well understood. Two mechanisms are suggested in the present paper; 1) non-stationary dissolution of aluminium carbide into a layer of sludge that periodically forms and disappears, and 2) electrochemical formation and dissolution of aluminium carbide within an aluminium carbide layer containing bath-filled pores. The latter mechanism may be related to the high local current density at the periphery of the cathode.

Jan 1, 2011

By S Morgan, D J. Bradshaw, S Schwarz

The characterisation of the flotation kinetic response in future mining deposits is important because the flotation response is affected by changes in ore mineralogy. Current methods for characterising the flotation response of different ore types, such as the JK floatability index test (JKFIT) methodology, require at least 10 kg of feed material. In geometallurgical applications, this material is taken from core samples. Core samples are generally obtained using specialised drills and are limited in nature. Thus, it would be beneficial to develop a laboratory technique that required less sample material but still characterised the flotation response of different ore types. The JK mineral separation index (JKMSi) is a small-scale flotation test that requires significantly less feed material (10 g of sample/data point). This study aims to investigate the JKMSi system kinetics and to validate this technique using the JKFIT proven methodology. The JKMSi flotation kinetics were manipulated by varying selected system parameters. The relationship between these parameters and mineral recovery was used to obtain floatability characteristics of the ore. For an ore sample containing chalcopyrite and pyrite, it was found that the chalcopyrite floatability parameters determined from both the JKMSi and JKFIT tests were of the same order of magnitude and the mass fractions of the fast, slow and non-floating components were similar. For pyrite, the floatability parameters were not of the same order of magnitude, but modifications to the test procedure have been identified, which may correct this.CITATION:Morgan, S, Bradshaw, D J and Schwarz, S, 2012. Julius Kruttschnitt Mineral Separation Index - Small-scale test to characterise the flotation response of an ore type, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 159-162 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By Felicia F. Peng

Using a fuzzy logic controller, a signal applied on the processes may be generated through a linguistic protocol expressing an operator's intuitive control strategies. In this work, fuzzy logic controller and PID controller imposed upon the feedback liquid level control systems for a stirred tank are studied and compared. The construction factors including the shape of membership functions, number of fuzzy variables, number of inputs, number of rules, and different defuzzification methods are considered in design and formulating the fuzzy logic control strategies and algorithms. From the analysis of the strategies and control performances, an optimum controller may be generated by making use of the best combination of these fuzzy construction factors.

Jan 1, 1997

By Carl-Oscar Nilsson, Åke B. Nilsson

"The embankment dam at Storfinnforsen is 23 m high and was completed in 1954. The dam has an impervious zone with timber sheet piles and a support fill of glacial till. The pore water pressure in the downstream shoulder has during recent years increased due to deterioration in the sealing function of the timber sheet piling. There is a concern that the high pore water pressure in the glacial till will cause internal erosion initiating at a thin coarse transition layer between the glacial till and the rock fill along the downstream toe. As a remedial action in order to improvement of the leakage resistance a supporting berm of coarse rockfill against the downstream slope of the dam was constructed in year 2013. In addition a new impervious seal in the centre of the dam e.g. a diaphragm wall was considered. However, after further studies and a trial stretch of 40 drains each 20 m long and diameter 0.3 m an alternative with vertical drilled drains in the downstream support was selected. A contract has now started up to drill in a similar way to treat the full length of the dam with drains. The work is in the planning to be completed in 2016.Dam ConstructionStorfinnforsen Embankment Dam was put into operation in 1954. The dam is 330 m long and maximum height is approximately 23 m. The dam is constructed with a central core zone and supporting zones of earth and rockfill on the upstream and downstream sides giving an almost symmetrical cross-section about the dam axis, see Fig. 1. The upstream slope is 2H:1V down to el. 270 and 2.5H:1V below. On the downstream side the slope is 1.75H:1V down to +269 and 2H:1V below. The core zone consists of a timber sheet pile wall with a Zone 5 of glacial till, approximately 2 m wide, adjacent to the wall on the upstream side."

Jan 1, 2016

By Paul Weaver

DURING 1932 the amount of geophysical surveying carried out as a part of oil-field development in¬creased, particularly in the Gulf Coast of Texas and Louisiana. Here the most intensive geophysical activity was displayed in the discovery of domes and prospects several years ago, after which there was a period of relative inactivity. This year many of the leases required development and geophysical methods were used to obtain pictures of the detailed structures. These were almost exclusively gravity and reflection-seismograph surveys and for the first time this latter method was generally used by oil operators to construct subsurface contours. The total number of geophysical troops in this territory increased from 16 to 40 during the year.

Jan 1, 1933

By J. W. Ristori, V. R. Garfias

ONE of the most serious problems now confronting Gel- many-and one that will affect Italy even more seriously if she goes to war against England and France -is that of supplying her navy, mechanized army, and air force as well as her industrial and other needs with the necessary and related products. This problem, serious even now, will become vital should hostilities on a large scale develop.

Jan 1, 1939

By R. L. Zick

The High Density Sludge Process was originally developed by Bethlehem Steel Corporation for use on acid mine drainage and diluted waste pickle liquor discharges requiring continuous chemical treatment systems. This work began in the early 1970s and was first put into practical use around 1973. To date there are approximately 15 operating systems which have been installed on mine drainage in the United States, and another 10 systems worldwide. Dense Sludge is an innovative and improved method for treating acidic metal bearing streams in a manner which minimizes the volumetric generation of sludge for disposal. The technology utilizes a sludge recycle process which forms particles that have a low affinity for water, unlike conventional metal hydroxide solids which contain tightly bound interstitial waters. Typical acid mine drainage streams contain high sulfate concentrations which combine with calcium ions in lime based treatment systems to form gypsum crystals. The physical form of this gypsum is radically altered when the Dense Sludge process is utilized compared to the form generated in conventional lime treatment systems. The characteristics of the metals particles are also changed in this process, as the metal hydroxides are converted to metal oxides. Slides No. 1 and No.2 show scanning electron micrographs of conventional and densified sludges illustrating these differences. The magnification used was 300X. The dense sludge particles settle faster, dewater more readily, are more easily pumped, and hold much less water than conventional precipitates. In some cases, because the metal content of the sludge is more concentrated, it can be economically recovered.

Jan 1, 1998

By Franciéli Mantovani

Apesar da primeira preocupação com relação à gestão de resíduos ser a busca pela minimização da geração dos mesmos, há muitos casos de processos produtivos que geram resíduos inevitáveis. A investigação e o desenvolvimento de processos tecnológicos capazes de transformar os resíduos no sentido de reutilizá-los são plenamente justificados e passaram a ser uma realidade. Dentro deste panorama, a reciclagem de resíduos potencialmente perigosos, como o pó de aciaria elétrica - PAE, é uma importante questão ambiental. A indústria de pigmentação, na busca de matérias primas alternativas e de menor custo, vem apresentando potencial para absorver resíduos que contenham elevados teores de ferro sob a forma de óxidos. Neste sentido, esta pesquisa objetivou avaliar a viabilidade do uso de PAE para pigmentação da fração argamassa do concreto. Para tanto, foram moldados três traços diferentes, com teores de adição de PAE e de pigmento comercial de 0% e 5%, mantendo-se uma relação água/aglomerante de 0,4. Para cada traço moldaram-se corpos de prova destinados aos ensaios de resistência à compressão e de medições colorimétricas. A partir dos resultados obtidos, verificou-se que o PAE apresenta potencial para pigmentação de argamassas. Entretanto, verificou-se retardo na pega do material, o que pode vir a prejudicar a desforma.

Jul 30, 2018

By Irajá Bernardino Ribeiro Juniorr

O presente trabalho tem por objetivo apresentar alguns exemplos de aplicações na Indústria Siderúrgica e de Mineração (Prensa de Rolos e Torre de Resfriamento) mostrando que com o emprego de uma confiável metodologia para determinação dos benefícios energéticos é possível a implantação das medidas de conservação de energia em sistemas de força motriz instalados nestas indústrias com o simples uso de Lubrificantes Sintéticos Especiais em substituição ao largo emprego de óleos minerais. Esta solução também proporciona ganhos energéticos e financeiros expressivos e mais atrativos do que as já consagradas soluções de eficiência energética como troca de lâmpadas e /ou motores de alto rendimento. Além do mais, a troca de lubrificante já é rotina implementada nas indústrias e seus profissionais da área de manutenção, não sendo preciso treinamento adicional para implementação, tornando esta ação com o propósito de economizar energia simples e fácil de ser implementada. Este trabalho é uma parte dos resultados do projeto inovador desenvolvido pela Klüber Lubrication desde 2010, onde o principal objetivo é disponibilizar aos usuários de sua linha de produtos este recurso, internacionalmente reconhecido, de Medição & Verificação para a comprovação de ganhos de energia em prensas de rolos com alcance de redução de cerca de 10% de consumo de energia.

Aug 17, 2017

By Guiqing Zhang, Liansheng Xiao, Zuoying Cao, Li Zeng

A new process of direct solvent extraction of nickel from sulfuric acid leach solutions of low grade and complicated nickel resources using a novel extractant HBL110 was proposed. The basic performance of new organic system was investigated and the continuous pilot plant and the industrial test were conducted. The results indicated that the extractant of HBL110 can be used to directly extract nickel selectively over iron, aluminum, manganese, magnesium, calcium and chromium from sulfuric acid leach solutions. The loaded organic solution can be easily stripped using dilute H2SO4 solutions. Both kinetics of extraction and stripping of nickel were fast. The continuous pilot plant test with the sulfuric acid leach solution of laterite containing 6.22g/L Ni2+, 14.1g/L Fe3+, 0.73g/L Fe2+, 33.9g/L Mg2+, 1.58g/L Al3+, 0.495g/L Ca2+, 0.97g/L Mn2+ and 0.5g/L Cr3+ as feed in mixer-settlers showed that the process had run stably with 98% recovery of nickel. The concentration of nickel in strip liquors reached as high as 50 g/L while the removals of Fe3+, Fe2+, Mg2+, Al3+, Ca2+, Mn2+ and Cr3+ were 98.5%, 91.5%, 99.95%, 99.8%, 99.1%, 98.6% and 99.5%, respectively. The industrial test with the sulfuric acid leach solution of electroplating sludge containing 11.5g/L Ni2+, 2.68g/L Fe3+, 7.54g/L Cr3+, 0.61g/L Mg2+, 2.09g/L Al3+, 0.68g/L Ca2+, 0.022g/L Mn2+ and 0.154g/L SiO2 as feed in mixer-settlers also showed that the process had operated successfully with 99.5% recovery of nickel. The concentration of nickel in strip liquors reached 42.7 g/L while the removals of Fe3+, Cr3+, Mg2+, Al3+, Ca2+, Mn2+ and SiO2 were 99.2%, 99.77%, 99.73%, 99.56%, 99.57%, 98.51% and 98.75%, respectively. The new process exhibited big advantages of short flow sheet, high recovery of nickel, high removal of impurities, low chemical reagent consumption and low cost. Application of this process in industry is expected to make important impact on the extraction of nickel from sulfuric acid leach solutions and to deliver good environmental and economical benefits.

Jan 1, 2016

By Eduardo Luiz Sales Marinho

A Fábrica de oxigênio da AMT produz gases O2 e N2, utilizados no processo de produção de aço. Neste processo de fracionamento de ar, existe um compressor de ar que é responsável pela captação do ar atmosférico. Este compressor é do tipo centrifugo de 4º estágios de compressão, fabricação Hitachi, e tem capacidades de vazão de 114.000 Nm³/h e pressão de descarga 5.4 Kg/cm². Em Novembro de 2012, foi realizada inspeção no compressor e identificado trincas nas pás do impelidor do 4º st e perda de espessura de parede das pás do impelidor do 3º st de compressão. Houve perda da confiabilidade de operação do equipamento, sendo necessária uma ação para correção do problema. Depois de identificado a causa raiz das trincas,foi decidida a compra de dois novos impelidores com modificações no material para aumentar a resistência à corrosão. Na aquisição dos novos impelidores havia duas possibilidades: 1) Adquirir novos impelidores junto ao fabricante original do equipamento; 2) Adquirir novos impelidores por processo de engenharia reversa (levantamento de desenhos da peça desgastada para fabricação de uma nova) em conjunto junto com empresa especializada. Este trabalho irá mostrar os critérios e considerações que levaram a AMT decidir pela compra de novos impelidores por “Engenharia Reversa”, bem como, suas vantagens e riscos assumidos.

Sep 25, 2017

By Victor Avdokhin, Ivan Kovlekov

"Studies of the process of concentration of gold-containing sands and technogenic resources show that the main reason of gold losses is misbalance between size of gold particles and degree of roughness of mineral bed. This results in free circulation of small gold particles in pores with following washing off the particles from the bed by turbulent flows.We elaborated design of magnetic sluice, intended for improving efficiency of recovering fine gold by optimizing magnetic field of a magnetic system on the base of forming catching coat from magnetic mineralsThe magnetic sluice includes trough-shaped body from magnetic-conducting material. On the bottom of the trough, magnets are placed, and opposite poles of the magnets are oriented outwards. Thickness of the bottom is determined to be sufficient for locking magnetic lines of force of the magnets on each other. The magnets of rectangular plate shape are placed on the rough bottom, covering the whole surface or with spare areas; the magnets are placed across the trough with alteration of rows with the same pole orientation.Catching coat is formed of natural magnetic and weak-magnetic placer minerals in field of magnetic system of the sluice. Magnetic minerals, placing along magnetic lines of force, form rough coat of fluffy structure. Size of the magnetic particles is chosen taking into account expected size of gold particles, which are to be fixed on the rough coat or between the magnetic particles. Changing coarseness of particles of mineral bed allows to regulate selectivity of recovering heavy minerals.Forming artificial fleece from magnetic minerals of initial sand, increasing capacity of the bed and relative hydraulic proportionality of mineral particles of the bed provide for the most effective recovery of fine gold."

Jan 1, 2003

By R Urie

Dilution and loss of ore during the mining process invariably occur in all underground mining operations. This dilution and ore loss can have a significant effect on the performance and value generated from a mining operation. Further, excessive dilution or greater than anticipated ore loss during mining is often one of the key reasons for the underperformance of a mining project when compared to a feasibility study or annual budget. Mining professionals often go to great lengths preparing detailed mine plans, schedules and economic models only to then apply high-level estimates or rule of thumb values for dilution and mining recovery that can ultimately lead to inaccurate forecasts for the performance of a mine with the resultant loss of value due to the mining of uneconomic material or the loss of potentially valuable ore. This paper discusses processes and practices that can be practically used to manage dilution and mining recovery in an underground mining operation with a focus on understanding and then maximising value. The processes cover items such as the definition and measurement of dilution and mining recovery, techniques for the estimation of dilution and mining recovery, consideration of the economic implications, management of dilution and mining recovery through the stages of the planning cycle, and practices to reduce dilution and improve mining recovery. Common misconceptions and omissions are also discussed.

Mar 29, 2023