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By S. Asokan, Ch. V. G. K. Murty, R. Upadhyay

Zircon (ZrSiO4) is the most frequently found zirconium ore occurring in heavy mineral sands, from which it is extracted as a co-product in the production of ilmenite and rutile. Estimated world reserves of zircon are 124 million tonnes, highest in Australia (around 56 million tonnes), followed by Mozambique (15 million tonnes), India (12.6 million tonnes) and South Africa (12million tonnes). Zircon finds its application in ceramics (54%) and refractory industries (14%), which account for 68% of zircon?s total world consumption of 1.20 million tonnes. The rest (32%) is consumed in foundry, TV glass, zirconia chemicals and other applications. It is a long recognized feature of the zircon industry that supply is totally dependent upon the concurrent production of titanium minerals. But in recent years, several new developments such as the discovery of zircon-rich mineral sands in Australia, the continuing trend of higher prices of zircon and increase in trade of lower quality zircon have changed the scenario. These factors have prompted more intensive efforts to increase the recovery of zircon, particularly in the process for separating zircon from alumino-silicate minerals. Tata Steel?s proposed heavy mineral sands deposit contains on an average 10% heavy mineral content and 15% slimes of the size below 63 micron. Mineral assemblages of the resource contain65?70% ilmenite, 4?6% rutile, 4% zircon, 16% sillimanite and other minor minerals. Wide size range and tenacious iron oxide coating are the inherent characteristics of this deposit. High concentration of sillimanite among the non-magnetic heavy minerals and heavy surface coatings on the minerals are challenges for high recoveries and production of premium grade zircon. This paper outlines various process steps that were taken at pilot plant stage to produce zircon of premium grade and subsequently develop the appropriate flow-sheet.

Jan 1, 2007

By Marcel Magnusson, Guozhu Ye, Pekka Vaananen, Yang Tian

The most used technology for recycling of spent alkaline batteries consists of crushing, magnetic separation and processing of the nonmagnetic fraction, black mass, using a rotary kiln. In the process only zinc is recovered and all manganese in the black mass is lost. According to the EU regulation for recycling of batteries, more than 50% of batteries should be recovered. To meet the demand, Swerea MEFOS has together with a major battery recycler IsoLogistics in Finland and Sweden developed technologies for efficient recovery of zinc and manganese aiming for >50% recovery. This paper will focus on a treatment process using a DC furnace to produce a ZnO- and a MnO-product. The process has been demonstrated in pilot scale, 1 ton/h. The major outcomes will be highlighted. Another approach by using thermal vacuum technology for distillation of zinc metal has also been demonstrated in laboratory scale which is also reported in this paper.

Mar 1, 2018

A simple production technique has been initiated and implemented at Oaky Creek open cut coal mine to optimise recovery of coal from the relatively thin geological seams. The production technique is based upon minimising coal dilution through careful dragline operation and the selective use of mine mobile equipment to clean the top of coal. In addition, recovery of coal from the pits has been increased by refining blasting and dragline methods.The implementation of the recovery optimisation programme at Oaky Creek has provided significant economic benefits from increased yield through the preparation plant by the reduction in dilution, and from increased raw coal tonnage through improved pit recovery methods.

Jan 1, 1990

By M. J. King, W. K. B. Loftus, H. S. Simpson

SYNOPSIS The history of the early diamond fields and primitive methods of diamond recovery are traced, giving a brief description of the improvements made in final diamond recovery processes and techniques up to the present day. In particular the emphasis is on the effect of improved equipment in reducing final hand sorting time and labour, better security and greater recovery of fine diamonds.

By W. K. Loftus, H. S. Simpson

Discussion I. R. M. Cheston (Visitor): I should like to congratulate the authors on this interesting paper which graphically illustrates the overall effects of the gradual developments in diamond concentrating processes which have taken place over the past few years. These final stages of diamond concentration represent only a minor factor in the cost of diamond production but because of the shortage of highly trained people for this work, any easing of the burden on the sorting staff has an importance far beyond the immediate economic sphere. The search for the solution of problems posed by the economic and social conditions of industry is never-ending. The Diamond Research Laboratory is, even now, carrying out further work to improve still more the operation of general diamond recovery processes as described in the paper. Before looking at some of the latest developments in this field of final recovery, there are a few points arising from the paper on which I would like to comment. On page 321, reference is made to the X-ray sorters originally developed by the DRL. The paper gives a figure of 100 per cent recovery of diamonds from +7 mesh concentrates in two passes through the prototype machine. Not wishing to claim miraculous powers for our group, I would prefer to see this given as virtually 100 per cent recovery of all fluorescing diamonds. Firstly however much care is taken, there is bound to be an occasional operating loss. In the test work, 100 per cent recovery was made on many occasions but this was not always so. Secondly, although most diamonds fluoresce strongly under X-rays, some diamonds only fluoresce weakly. Type IIB diamonds, in fact hardly fluoresce at all, but the incidence of this special type of diamond is very low in most deposits. However, in operating the commercial X-ray machines, there is a certain background level of reflected radiation from other feed particles. Unless the diamond fluorescence is several times greater than this, it is not possible to achieve sufficient sensitivity in ejection. A certain small but variable proportion of diamonds from each deposit is always found to fluoresce too weakly to be recovered by the X-ray machine. Tests have shown, that for the De Beers mines, this proportion is considerably less than I per cent. These diamonds are nearly all dark brown or black in colour and therefore of low value. The degree of fluorescence does not, however, depend entirely on the colour or quality of the diamond and some of the brightest fluorescence comes from the lowest quality of boart diamonds. Investigations into the property of the diamond which causes this low fluorescence are being carried out. On page 322 it is suggested that zircon fluoresces in the same colour spectrum as the diamond. This is not quite accurate. The total light given out by zircon under X-rays is of the same order as that of diamond. However the zircon radiation has a much wider spectrum band than the diamond fluorescence. Reference is also made on page 322 to the effect of selective milling in small laboratory mills on diamonds. Perfect diamonds are very hard and very strong and are extremely difficult to break. Imperfect diamonds, which form the majority of diamonds recovered from most deposits, although hard, can be very brittle. Even under slight impact some of these diamonds may shatter to powder. Milling conditions must therefore be extremely closely controlled to minimize breakage, and even so, some breakage will always occur. As suggested in the paper, the necessary conditions are: the use of small balls, slow speed mills and very limited water addition. Tests elsewhere have suggested that the water content of the pulp in such a mill must be less than 25 per cent by weight of pulp to prevent diamond breakage reaching significant proportions. The skin flotation techniques described on page 323 operate on a very small scale. It is of interest to note that in West Africa a large-scale continuous skin flotation machine is used to recover the fine diamonds. In this operation the feed is dried and, after standing, is mixed with water and fed in a single layer onto a woven phosphor-bronze conveyor belt. This belt runs at a shallow angle into a water bath and as the particles are carried through the air-water-interface, the diamonds float off and over a weir into a collecting box. The bulk of the particles, being wettable, sink to the bottom of the tank and are continuously removed. If treated without prior drying, the diamond recovery is poor. If material is treated immediately after drying, a lot of the gangue particles also float. During standing, in the hot and humid atmosphere of West Africa, it is found that the gangue particles recover their wettability much faster than the diamond particles. Optimum selectivity is obtained after standing for approximately 24 hours. At the DRL we have been experimenting with optical filters to differentiate between the fluorescence of diamonds and zircon. By limiting the light transmission to the fairly narrow range emitted by diamonds, it is

Jan 4, 1970

Recovery Process of Carbon Dioxide with Metal Oxides and Metal Hydroxides

Sep 13, 2010

By P. Blonde

Recent analysis has suggested that a balanced recovery profile can improve flotation bank performance. Test work was conducted to test the balanced profile concept at the Penhorwood talc mine near Timmins, Ontario, Canada. Plant trials were devised to determine how to control the recovery profile and the resultant impact on grade and recovery in a rougher bank of four cells. Accompanying gas dispersion measurements revealed a maintenance issue with one cell that was corrected. By manipulating air and frother addition it was possible to bring the bank closer to a balanced recovery profile and the down-the-bank grade/recovery improved. Plant production showed an increased talc grade at similar yield with the balanced profile. The results provide justification for a long term plant trial.

Aug 1, 2013

By J. R. Parga

Bacís mining is a young enterprise in Mexico that produces a pyrite concentrate rich in gold and silver. When gold and silver are associated to sulfide minerals, pre-treament such as: roasting, pressure oxidation and bioleching, is required to decompose the sulphides and thereby expose the gold and silver particles to the cyanide solution. A novel method demonstrates that the oxidation and dissolution of gold and silver in alka-line cyanide solution can be conducted simultaneously in the same autoclave in less than 90 minutes with a recovery that exceeds 96%. Factors affecting recovery efficiency such as pH, leaching time in the reactor, temperature, particle diameter, pressure, % of NaCN and pulp density were investigated.

Jan 1, 2007

By C J. Greet, S Jacques

In most instances, the application of high-chrome grinding media results in an increase in the recovery of the valuable mineral(s). The authors have published data from a number of plant-based case studies, which indicate that it is not unreasonable to expect a recovery increase in the vicinity of 1.5 to 2.0 per cent for a copper ore. It is of interest to understand where the increase in recovery is coming from. That is, is the additional copper recovery the result of improved fine particle flotation or is it due to an improvement across all size fractions?This paper aims to answer this question. Laboratory flotation tests were completed using forged steel and a high-chrome alloy on a volcanogenic massive sulfide copper ore. The unsized data indicated that the application of high-chrome grinding media to this ore resulted in an improvement in both copper recovery and copper concentrate grade. A detailed kinetic analysis of both the copper sulfide and gangue minerals was completed that clearly shows that the change to a more inert grinding media produced significant increases in the flotation rate constants (both fast and slow) across all size fractions. It is also possible to observe that the change in pulp chemistry has resulted in a decrease in the flotation kinetics of the -20 micron pyrite, while the coarse pyrite recoveries have increased, presumably because of an increase in the flotation of the chalcopyrite/pyrite composite particles.CITATION:Greet, C J, Jacques, S and Kinal, J, 2014. Recovery-by-size kinetic analysis to determine where metallurgical improvements occur when converting to high-chrome grinding media, in Proceedings 12th AusIMM Mill Operators’ Conference 2014 , pp 217–224 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 1, 2014

By Eleanora I. Robbins, Motoaki Sato

Many problems associated with acid mine drainage (AMD) are caused by the complex way molecular oxygen (O2) oxidizes reduced matter at surface temperatures. In aqueous solution, O2 kinetically "prefers" to go through the formation of hydrogen peroxide (H2O2) as an intermediate. Being innately unstable, H2O2 is quickly decomposed back to water and oxygen in the presence of dissolved Fe and Mn, both catalysts for the decomposition. Direct addition of H2O2 to AMD produced similar results. Ozone (O3) is a much faster and stronger oxidizer than either O2 or H2O2. In the laboratory, O3 rapidly precipitated Mn, Fe, Ni, Co, Pb, and Ag even in acidic solutions. The experiments indicate that AMD can probably be processed with ozone and metal oxides/hydroxide recovered in flow systems using only septic-tank-size reactors and small sedimentation ponds.

Jan 1, 2000

By Saul Hissaci de Souza

A liga de alumínio AA 7075 recebida no estado T6 (conformada e envelhecida artificialmente) sofreu tratamento térmico a 300°C com o objetivo de causar o engrossamento das partículas de MgZn2, intermetálico responsável pelo endurecimento do material. As amostras foram então deformadas 45% em redução de espessura por laminação e recozidas isotermicamente a 200°C e a 250°C por tempos variados para estudar a cinética de amolecimento por meio de medidas de dureza Vickers. Os resultados indicam que a cinética de amolecimento em ambas as temperaturas de recozimento aproxima-se do comportamento previsto pelo modelo Johnson-Mehl-Avrami-Kolmogorov (JMAK) com boa concordância (coeficientes de correlação de 0,9725 e 0,9140 a 200°C e a 250°C, respectivamente), ainda que as micrografias ópticas da amostra recozida a 300°C por 4 horas não evidenciem a ocorrência de recristalização.

Oct 30, 2017

By C. T. Agouridis

Head-of-hollow fills or valley fills have gained national attention due to increasing environmental concerns, particularly with regards to headwater stream loss. Researchers at the University of Kentucky in conjunction with outside scientists and consultants in the fields of stream restoration, wetland restoration, and mined land reclamation have developed new design methodologies for creating a headwater stream system for a head-of-hollow fill in eastern Kentucky. The design was largely built on the Forestry Reclamation Approach (FRA), which encourages a non-compacted spoil medium to promote tree growth, in an effort to address concerns related to water quantity and quality as well as habitat development. The major components of the design included 1) modifications to the crown geometry, 2) compaction of the crown to control infiltration, 3) utilization of natural channel design techniques, 4) use of the FRA to promote tree growth, 5) creation of ephemeral channels and vernal ponds, and 6) implementation of a novel bioreactor-wetland treatment system to improve water quality.

Jan 1, 2008

By Flávia Vieira Braga

Este trabalho teve como objetivo verificar a melhor condição para promoção de recristalização de um aço inoxidável ferrítico 430, estabilizado ao Nb, no processo de laminação à quente de acabamento. Ensaios de torção foram realizados para simular o processo de laminação em laminador Steckel, utilizando diferentes temperaturas de laminação. Ensaios interrompidos foram realizados para avaliar a recristalização entre os passes. As amostras ensaiadas foram analisadas por microscopia ótica e EBSD. Como resultado do trabalho, foram levantados os esquemas de laminação mais favoráveis para promover a recristalização. Estes esquemas poderão fornecer subsídios para estabelecimento de prática padrão industrial de laminação deste aço adequada para promover a recristalização.

Aug 8, 2018

By Fabiana da Silva Santos

Neste trabalho foram estudados os efeitos da laminação a frio com baixo percentual de redução e a cinética de recristalização em um aço médio carbono e alto manganês. O aço em estudo foi laminado a frio com percentual de redução de 10%, seguido de um tratamento térmico de recozimento nas temperaturas de 650 e 700°C, em tempos de 10, 15, 20, 25 e 30 minutos. A caracterização microestrutural e avaliação da fração recristalizada foram avaliadas por microscopia óptica e a dureza Vickers (avaliada em um macrodurômetro e um microdurômetro). De acordo com os resultados pode-se observar um efeito combinado de recristalização e crescimento de grão em função da microestrutura parcialmente encruada pelo baixo percentual de redução imposto, que se acentua com aumento do tempo e da temperatura de encharque.

Aug 16, 2017

By Flávia Vieira Braga

Este trabalho teve por objetivo avaliar as melhores condições para promover a recristalização entre passes, durante a laminação a quente em laminador Steckel, de um aço inoxidável ferrítico AISI 430 estabilizado ao Nióbio. A laminação a quente de acabamento foi simulada através de ensaios de torção utilizando um esquema em diferentes temperaturas. A ocorrência de recristalização entre os passes de laminação foi estudada através de interrupções antes de alguns passes. As amostras ensaiadas foram analisadas por microscopia ótica e MEV-EBSD (difração de elétrons retro-espalhados). Os resultados deste trabalho mostraram ser possível promover a recristalização entre passes durante a laminação de acabamento do aço AISI 430 estabilizado ao Nb. Foi, ainda, estabelecida a melhor faixa de temperatura para a promoção de recristalização.

Jul 30, 2018

By A. Fleming

The exploration process, like any other commercial activity, can only succeed if the objective of the exercise is clearly defined and persistently pursued. Successful exploration requires properties, funding, personnel and persistence. Many of us have years of experience in conducting exploration in our countries of residence. Conducting exploration in a foreign country, however, requires a number of significant other criteria.

Jan 1, 1997

By A G. L Pratt, M S. Kemp

BHP has used many innovative techniques when recruiting its workforce for the Cannington Project. Looking for a balance of experience and enthusiasm it was necessary to develop pre-selection tests to reduce the initial number of applicants to a manageable number for first interviews in Townsville. Success at this stage led to an applicant, and their spouse, to go through a second interview at the mine site. The full process from application to job offer took up to six months, but the results were felt to be worth the effort. The approach taken has resulted in a highly motivated and flexible workforce. This paper outlines the philosophies behind CanningtonÆs recruitment process, highlights some of the issues associated with the approach, and offers some measures of the outcomes.

Jan 1, 1998

By P. Conrad, S. Rosenthal

"Engineers remain in demand. Job opportunities in the United States still exceed the number of students graduating from college with degrees in Mining Engineering. Although enrollment is up for freshman studying Mining Engineering, many of those students will either change majors or not complete their degree, maintaining that deficit of available Mining Engineers. What can be done to ensure that enough Mining Engineers will graduate to fill the needs of the mining industry over the next ten to 20 years? The authors believe that this need can be met by recruiting students to Mining Engineering programs who are genuinely interested in working in the mining industry. With this in mind, Montana Tech conducted its first Mining Engineering camp in July 2014 to get junior and senior high school students interested in careers in the mining industry by showing them that Mining Engineering is both an exciting and rewarding career. This paper discusses What a Blast! The 2014 Montana Tech Mining Camp. INTRODUCTION The concept of summer camps for high school students is not new. For example, Missouri University of Science and Technology has offered their “Explosives Camp” for several years. A large percentage of attendees to these camps discover or confirm an interest in Mining Engineering and enroll in the school’s program. The Dean of the Montana Tech School of Mines and Engineering challenged department heads to develop and offer summer camps for prospective high school students to get a taste of engineering with the goal being to improve recruitment for each discipline. Mining Engineering embarked on the concept of a summer camp in 2013 with a concept to provide a week’s experience in Mining Engineering during the summer of 2014. What it takes to progress from concept to reality, with some of the learnings to be shared, follows."

Jan 1, 2015

By Joshua Hoffman

The recruitment and retention of future talent into the explosives industry is becoming increasingly important. Student chapters help with this effort but what are they doing and are there things they could learn from each other? This paper discusses the University of Kentucky Student Chapter's efforts to grow membership, retain its recruits, and integrate them into the explosives industry. Several social and professional events during which the students are able to meet and network with members of their future industry are introduced. The special relationship that has been fostered between the University of Kentucky and Missouri University of Science and Technology is discussed. Professional development initiatives which are critical for a student to become vested in the industry are shared in this paper. These opportunities which range from internships to research positions allow a person to get a better understanding of the explosives industry and find the niche that best suits them. Many of the student chapters are closely connected with engineering programs. While this makes sense and both entities benefit from these arrangements there is a trend of job placement primarily in the engineering industry. By providing these students with the chance to learn more about the explosives industry and get hands on experience more of these future engineers and professionals can be retained after their graduation.

Jan 1, 2013

By Maurice Cook

A procedure of obtaining specimens of lead, tin, and cadmium with a moderately equiaxed structure and a smooth surface suitable for etching without grinding and polishing is described; the advantages of general oblique illumination (as opposed to vertical illumination) in the photomicrography of pure metals .are stated. Using these methods, a statistical study of the changes brought about in deformed lead, on annealing, has been made. The common mode of structural change was found to be recrystallization. Cases of growth of one original grain into another were rare; but if a totally recrystallized specimen was annealed above 200° C., a few large grains appeared and spread over the whole area, except for a certain number of small grains which remain unabsorbed. The temperature needed to produce structural change in lead was found to be lower, the greater the degree of deformation. With tin, an extension of 28 per cent. caused practically no recrystallization at ordinary temperatures, but recrystallization occurred if the specimen was heated to 100° C. In cadmium at low temperatures, the grain size decreased in marked manner as the deformation increased; but at high annealing temperatures, the grain size was comparatively independent of the degree of deformation. THE structural changes in metals brought about by annealing following a deformation at a low temperature has been the subject of many investigations. No less than eleven metals and alloys have been studied in some detail; namely, aluminum,1 tungsten,2 iron,3 copper,4 gold,5

Jan 11, 1924