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By B. McFadzean, J. Taguta

The enthalpy of immersion is the heat change arising from the replacement of the solid-gas interface with the solid-liquid interface when a solid surface is immersed in a liquid. Although immersion calorimetry has been established as a valuable and reliable means of determining solid surface properties such as wettability, it has seldom been applied in mineral processing research. In this study, precision solution calorimetry was employed to measure the enthalpies of immersion of different minerals in water. The enthalpies of immersion were then related to the first-order flotation rate constant as determined by the microflotation technique. The same measurements were also made on sulphide minerals whose surfaces were modified to different degrees of hydrophobicity using different percentage coverages of amyl xanthate collector. The enthalpy of immersion technique was capable of distinguishing and ranking minerals according to their wettability. All mineral types and collector-treated minerals conformed to the same relationship that was found between the enthalpy of immersion and the flotation rate constant. This conformed, empirically, to a power law equation. As the enthalpy of immersion decreased, there were large increases in flotation response for very small changes in hydrophobicity. In addition, a critical enthalpy of immersion (CEI) was found, above which no flotation could occur. The scatter in the data points could be corrected for by adjusting the rate constant using the density of the minerals to produce a robust relationship between the rate constant and enthalpy of immersion. These results have shown that the enthalpy of immersion is able to indicate both the natural mineral hydrophobicity and the extent to which collectors can render a mineral hydrophobic. This technique has considerable potential to be used as a sensitive and accurate measure of mineral surface wettability in order to predict flotation performance.

Jan 1, 2018

By G. F. Loughlin

Nearly 55 years have elapsed since the U. S. Geological Survey was organized. During this period the mineral industries have grown from infancy or early childhood to well developed maturity, and some mining industries appear to be declining. Decline in mining is even more conspicuous in certain districts, or even states, than in any mining industry as a whole, and discoveries or developments of important new districts have been very few in recent years. Our reserves of most metals and nonmetals are adequate for many years of normal production, subject to changes in rate of exploitation that may be caused by foreign competition and by changes in technology and market conditions; but the declining production of many districts and the scarcity of important new discoveries to compensate for them is cause for some apprehension. It is likely that future production will depend to a considerable extent on deep exploration and on the thorough examination of places in and adjoining existing districts where significant outcrops are lacking and only apparently insignificant geologic features offer encouraging clues—more so than on the discovery of entirely new districts. Even the possible discovery of new districts, which have escaped the intensive search by the nontechnical prospector, must be dependent on geologic information. There is therefore no need for argument as to the value of geology to the mining industry; and the need of continuing to advance the science. The U. S. Geological Survey's past contributions to mining geology, as expressed in its official reports and other publications, are recognized by Ransome in his historical review of mining geology in the Lindgren volume.' These contributions have helped to form the basis of modern mining geology, which has grown rapidly in the last 25 years. This growth has witnessed the organization and maintenance of geologic staffs by mining companies in several districts, and their detailed work, together with the fact that nearly all of the larger mining districts have

Jan 1, 1935

By Peng ZANG, Qihang Liu

Experimental work was conducted to determine the relationships of coal char conversion with temperature and heat absorption. The results show that at an earlier stage of the coke forming process, lump coal would absorb large amounts of heat but the increase of high temperature strength of lump coal was not significant. Contrarily, the lump coal’s high temperature strength was greatly improved at later stage of coke forming process. A number of residual coal was found in most tuyere coke samples illustrating that the lump coals added in the melter gasifier were not completely transformed into coke when they arrived at the tuyere region. The results indicate that the improvement of lump coal’s high temperature performance is limited in the melting gasifier by the low coke forming rate which could become the core factor of fines generation of lump coal in the melting gasifier.

Jan 1, 2016

By Mohammed Sakr

The empirical relationship between torque measured during installation and pile capacity has gained a wide acceptance in the helical pile industry in the last few decades. This paper presents a theoretical model developed to estimate torsional resistance of cohesive soils to helical pile installation. The proposed torsional resistance model was then used to establish torque factor, Kt, a factor that is widely used in the industry. The results of the study indicated that the Kt factor is a function of the load path (i.e. tension or compression), pile geometry and soil properties. The assessed Kt factors in tension and compression were validated by the results of 74 installation records and full-scale helical pile load tests. A parametric study was also performed to qualitatively assess the relative importance of different parameters that affect the Kt factors.

Aug 1, 2013

By Zhang Hengzhong

Based on thermodynamics of surfaces and a proposed two-dimensional state equation for surfaces, the relationship between the surface tension (Y) of a solution and the activity (a1) of its component (i) was derived: (1/Y)r2-.¬E (ai/Yl) The derived equation was verified with reported experimental data of water-alcohol systems and water-acetone system, the calculated results showed astonishing coincidence with experimental. Applications of the equation to the five matte systems Cu2S-FeS, Ni3S2-FeS, FeS-PbS, Cu2S-PbS and FeS-Cu22S-PbS also demonstrated that at given matte compositions the calculated surface tensions agreed with experimental fairy well.

Jan 1, 1993

By T. M. Williams, P. M. Green

Paper presented at Mineralisation in the Caledonides, the Mike Gallagher memorial meeting held in Edinburgh, 27-28 June 1996. The sediment geochemistry of streams draining Southern Uplands and Lake District turbidites was compared with lithogeochemical data for the source greywackes, using stratigraphically defined catchments. Several systematic trends in element abundance variation between source and stream sediment can probably be applied more widely to interpretation of drainage geochemistry. Pb and Zr increase markedly from source rock to sediment, by adsorption on clay and zircon grain concentration. Variation of feldspar-related elements Rb, Sr, K and Ba appears to be controlled by source grain size and compositional maturity. Ni shows surprisingly little change and Fe and Co are only slightly raised. Cr is particularly useful, with variations superimposed in anomalously high regional levels. Abrupt changes in Cr distribution in stream sediment coincide with stratigraphical boundaries, allowing drainage data to be used as a surrogate for whole-rock values

Jun 19, 1905

An extensive laboratory grinding study was carried out on a magnetite ore in order to assess the grinding behaviour of magnetic concentrate and tail from low intensity magnetic separation (LIMS).The test work involved Bond ball mill testing, rod milling, low intensity magnetic separation (LIMS), and batch ball milling down to product sizes of around P80~25 microns. A total of 18 Bond tests and over 150 batch grinding tests and sieve sizing were carried out. Throughout the grinding tests, power draw was continuously monitored. The relationship between the grinding energy and product size was analysed using the conventional energy-size concepts. It was found that the Rittinger equation fits the experimental data well. However, Bond?s equation does not fit the experimental data well, and therefore a modified Bond equation was developed. Differences in grinding properties between the magnetic and non-magnetic component were analysed and compared to the bulk ore. It was found that grinding properties differ significantly and therefore separate grinding test work may be required for each grinding step in the magnetite ore beneficiation flowsheet. Keywords: grinding, iron ores, particle size, modelling.

Jan 1, 2010

By C. J. Sullivan

"The outlook for supplying the world's metal needs in the next twenty-five years is good, although in several cases basic costs are likely to increase with rising demand. Metal prices calculated at a constant dollar from 1900 to the present show that for nickel, copper, silver, lead, zinc and tin, prices -and presumably production costs -fell from 1900 to the early 1930s. Since then, they have generally risen, apparently reflecting some depletion in relation to demand. This tendency has been accentuated since the post-World War II adoption of managed, full-employment, growth economics, which have resulted in a sharp escalation in world demand for metals. (Abandonment of such policies, apparently now under consideration in North America, would, of course, affect the pre-dictions of this paper.) Nevertheless, metal prices generally are still below those prevailing in 1900. Exploration potential exists for disseminated ores of many metals still thought of as characteristic of lode and vein deposits. These include uranium, silver, gold, tin and nickel and, to a lesser extent, lead and zinc. Considering the discovery potential for some principal metals in relation to expected demand and prices, I would tend to rate them as follows: molybdenum, zinc, lead, uranium, silver, gold, tin, nickel and copper."

Jan 1, 1970

By Harry Power

THE relative merits of air and natural gas as propulsive agents in pressure drive operations have been discussed for a number of years. When air or gas is introduced into the sand, various factors lead the operator to the selection of what he believes to be the proper propelling medium; but when the question of relative drive effect is raised, several physical and chemical premises must be taken into consideration in arriving at a conclusion as to the superiority of one medium over the other. Dow and Calkins1 and Beecher and Parkhurst2 have contributed fundamental experimental work on the effect of dissolved gas in lowering the viscosity and surface tension of crude oil. Herold3 and Tickell4 have indicated that whatever type of reservoir control obtains, gas plays other important parts in the movement of oil towards the well, namely: 1. The propulsive and expansive force of the gas. 2. The "Jamin effect," or resistance to the movement of oil in a porous media due to the formation of gas bubbles. When quantitative studies are made, parallel conditions must be selected whereby we may say definitely whether air is superior to gas as a driving medium, or vice versa. Examples of similar conditions are not easy to find in the field. However, in the laboratory we can make determinations which may lead to general conclusions when applied to the field. The- experimental and research work described here was started at the laboratories of the University of California in January, 1927, and completed in private laboratories at Tulsa, Okla., in February, 1928. The apparatus used was designed especially for the work.

Jan 1, 1928

By Sanchita Chakravarty, Sumantra Bhattacharya, Divya Jyoti, A. K. Mukherjee, Soni Jaiswal

"Release analysis is independent of collector and frother dosage and type, but it is primarily influenced by the degree of liberation or “state of release of the sample”. The shape of release curve is an indication of the degree of liberation. This paper briefs about the effect of reagent combination, particle size and surface characteristics on the release analysis of difficult-to-clean LVC coal.Release analysis of three LVC coal fines obtained from two different coalfields of India was carried out at three different size levels such as -0.5mm, (-0.5+0.1) mm, and -0.1mm. The collectors used were n-dodecane and commercial diesel oil. Incomplete liberation of coal fines even at a size of -100µm, corroborated by photomicrographs of ROM and clean coal macerals, in a great measure reduced the flotation-based cleaning potential of the fines. FESEM images of fines reveals that the adherence of ultrafine onto the surface of relatively coarser particles reduced the clean coal recovery. The results obtained also appear to be coal, reagent combination and, particle size and particle surface specific. Only one coal indicated the liberation as is usually expected for -0.1mm particles with a reasonable yield of 65% at 18% ash. INTRODUCTION Froth flotation has a long history of being used to treat coal fines. Coal flotation is considered to be difficult, if the percentage of Near Gravity Material (NGM), i.e. essentially locked particles, in flotation feed is >10% [Aplan, 1993], which is usually the case with all the coking coal fines in India. The fines are rich in vitrinite, so valuable for coking coal. Unfortunately, there appears to be no standard procedures to determine the separation efficiency of froth floatation. Release analysis proposed by C.C. Dell in 1953 [Dell, 1953], aimed to determine the ultimate floatability of coal. Several other techniques had been proposed but release analysis technique has been considered to be a vast improvement over the batch flotation process [Forrest et al. 1994]."

Jan 1, 2018

By J. Wong, M. G. Lipsett, L. K. Daneshmend

"Current trends of increased size, complexity, and automation of surface mining equipment necessitate more comprehensive and objective techniques for equipment comparison and selection. The field of reliability analysis provides tools to generate quantitative bases for maintenance and reliability aspects of such comparisons. Results from statistical analyses of failure and repair time data are used to perform the comparison. A case study is presented which analyzes five machines of two different technologies and three different designs.IntroductionThe surface mining industry is currently faced with a rapid evolution in production equipment. The more obvious trend in this evolution is the steady introduction of even larger machines. Parallel, and complementary, to this increase in size is the introduction or adaptation of new technologies. Together, these two trends result in new surface mining equipment designs; these designs are often more complex and may feature technologies that have yet to be proven for the application or at the scale they are now fielded.The prospect of significant automation of open pit equipment is also bound to add complexity to future equipment designs. Semi-automated features, such as drilling controllers (Aquila, 2000), have already been commercialized. Fully autonomous haul trucks have been demonstrated in open pit mines (Jackson and Zoschke, 2000). Design concepts for comprehensive teleoperation of open pit operations have been formulated (Lipsett, 1998).With this rapid availability and deployment of new technology and equipment, managers and maintainers are faced with a multitude of decisions regarding what equipment to acquire and what maintenance strategies to implement. In light of this evolution in mining equipment, it is necessary to develop better methods for making equipment management decisions (Dessureault et al., 1999; Paraszczak, 1999). The incentive for development of such techniques is that a large portion of an open pit mine’s operating cost is maintenance related, as shown in Table 1."

Jan 1, 2000

By E. Siami-Irdemoosa, S. R. Dindarloo

"Pareto analysis was used to investigate the failures database of a Hitachi EX1900 hydraulic shovel over one year of continuous operation. The hydraulic system and hydraulic links, hoses and piping were identified as the most critical system and subsystem, respectively. A three-parameter gamma distribution function was identified as the best fit for a probabilistic modeling of the time between failures (TBFs). This distribution was used in a Monte Carlo reliability analysis of the hydraulic system. Autoregressive integrated moving average (ARIMA), within the context of a time series analysis of the TBFs, was proposed as a viable alternative to the traditional technique of distribution fitting. The mean absolute percentage error (MAPE) metric was used to compare the two models. The MAPE value that resulted from the ARIMA was 66 percent smaller than that from the traditional technique in predicting the TBFs.Resumen ¦ Se usó análisis Pareto para investigar la base de datos de fallas de una pala hidráulica Hitachi EX1900 durante un periodo de un año de operación continua. Se identificó al sistema hidráulico y a los enlaces hidráulicos, mangueras y tuberías como el sistema y subsistema más importantes, respectivamente. Se identificó una función de distribución de tres parámetros gamma como el más apto para un modelado de probabilidades del tiempo transcurrido entre las fallas (Tabes por sus siglas en inglés). Esta distribución fue usada en un análisis de confiabilidad Monte Carlo para un sistema hidráulico. El promedio de movimiento integrado auto-regresivo (ARIMA por sus siglas en inglés), dentro del contexto de análisis de serie temporal de los TBFs, fue propuesto como una alternativa viable a la tradicional técnica de ajuste de distribución. Se usó el porcentaje de la media absoluta de error (MAPE) para comparar los dos modelos. El valor MAPE que resultó de la ARIMA fue 66 por ciento menor que el resultado obtenido con la técnica tradicional de predicción de TBFs."

Jan 1, 2015

By Bjørn Nilsen

"INTRODUCTION/BACKGROUND Weakness zones or faults containing clay-rich gouge represent one of the most challenging rock mass conditions to be encountered during tunneling. In Norway, such conditions count for a large part of the rock support costs, and in cases where the rock support has been insufficient, serious instability and cave-in have in many cases been the result. Most commonly, such cave-in has occurred after water filling of hydropower tunnels, but in some cases it has also occurred in tunnels under excavation and in completed “dry” tunnels. To avoid instability, two important requirements have to be fulfilled: 1) The location of the weakness zone and its character have to be identified in time. 2) The rock support has to be sufficient to withstand the loading caused by the zone. An incident which really brought the problems related to swelling clay into focus was the cave-in at the Hanekleiv road tunnel in 2006. Here, rock fall from the roof as shown in Figure 1 occurred unexpectedly about 10 years after the tunnel was completed. Fortunately this happened at a time with very little traffic, and nobody was injured. This incident emphasized the significance of the issue of swelling clay, although it was found to be caused also by gravitational collapse of the clay-rich gouge material of the weakness zone, and not related to swelling only (Nilsen et al. 2007).In this paper, main focus will be on discussing the characteristic features of swelling clay, test procedures which are being used for characterizing swelling clay, and the reliability of the results from testing for use in support evaluation and design in conditions with swelling clay. It is generally well known that swelling clay may cause considerable pressure on support elements, but quantifying this pressure for reliable analysis and design of rock support is still a great challenge."

Jan 1, 2016

By Snehamoy Chatterjee, Sanjay Kumar Palei, Smarak Das

Machine manufacturers’ recommendations on maintenance strategies of capital-intensive draglines are not always based on real data and therefore lead to losses from downtime. This paper proposes a preventive maintenance strategy for a dragline deployed in an opencast coal mine based on reliability-centered maintenance and failure-mode-effects analysis using real operational data. Reliability-centered maintenance replaced a cluster of critical failure components of the dragline while satisfying two specific conditions: (i) the components should be replaced at the earliest mean time to failure (MTTF) within the group and (ii) the time taken to replace all the parts should be equivalent to the maximum downtime within the group. Estimated threshold weightage factor identified twenty-six critical failure components for the preventive maintenance strategy, and clustering of components divided them into nine groups. In a group, the loss that is expected to occur by replacing some of the components before their failure, and the gain by reducing the overall maintenance downtime, has been explained through a cost-benefit analysis. The total net profit generated is calculated as US$200,178. This clustering activity also led to a reduction of annual downtime by 231 h, whose approximate market price as equivalent coal production costs $295,365.

May 28, 2020

By G. W. Brooks

This short article is quite different to the general run of papers that are presented to the Institute, but no apology is offered because I consider that first-aid and mine-rescue work are of equal importance to many other subjects that are dealt with in our Transactions. Members of the Institute should be as much interested in the safety of persons engaged in the mining industry as they are in the practical methods of modern mining. We must not only do our best to conserve life and property by adopting every known device to that end, but we must also prepare ourselves so that we may take prompt and effective action when life is in danger, or when property is subject to loss. The need for such preparation in Alberta is perhaps greater than in most places where mining is carried on, and we must spare no effort to assemble at every mine men who are well trained in first-aid and mine-rescue work. The large area over which the mines are distributed renders central training stations out of the question, hence the need for local rescue-teams. Hospitals with skilled staffs, close enough to the mines to be convenient, also seem to be out of the question; therefore the greater need of a high standard of first-aid training for the people in our mining camps. The Government mine-rescue cars are supplied with the equipment necessary for training persons in this essential work and also for dealing with disasters should they occur. The question then arises: are there a sufficient number of men who are trained ? If so we can rest assured that what is possible to be done will be done. But if a sufficient number of trained men are not available much loss of life and damage to property is likely to result.

Jan 1, 1925

By JoAnn Silverstein, Eric A. Marchand

Competition between Thiobacillus ferrooxidans and non-iron-oxidizing heterotrophic bacteria was induced by the addition of glucose to a co-culture of T. ferrooxidans and A. acidophilum in an oxygen-limited environment. Iron oxidation was inhibited as dissolved oxygen was used preferentially for glucose metabolism. Furthermore, as the water became anoxic, glucose was consumed along with the oxidized iron species (Fe3+) during iron respiration resulting in a pH increase from 2.0 to 4.0. Results suggest that biologically mediated acidification of drainage water can be reversed by dispersion of an easy to degrade, soluble, and inexpensive carbon source such as glucose into the subsurface.

Jan 1, 2000

By Courtney A. Young

Cyanide is a critically important chemical to the mining and metallurgical industry. It has a strong affinity for metals making it favorable as an agent for metal finishing and treatment as well as a lixiviant for metal leaching, particularly gold. These technologies are environmentally sound but, because cyanide is very toxic, safeguards are required to prevent accidental spills and treat effluents before being discharged. Various methods of cyanide remediation by separation and destruction for cyanide management purposes are therefore reviewed. The methods have been broadly categorized as physical, -adsorption. complexation and oxidation methods including photolysis and other advanced-oxidation processes. Reaction mechanisms for these methods are presented throughout this paper, Finally, the methods are compared in regards to their effectiveness in treating various cyanide species: free cyanide, thiocyanate, weak-acid dissociables, and strong-acid dissociables.

Jan 1, 1998

By C. A. Young

Cyanide is a toxic species that is found predominantly in industrial effluents generated by metallurgical operations. Cyanide's strong affinity for metals makes it favorable as an agent for metal finishing and treatment and as a lixivant for metal leaching, particularly gold. These technologies are environmentally sound but require safeguards to prevent accidental spills. Various methods of cyanide remediation by separation and oxidation, including photolytic advanced-oxidation processes, are therefore reviewed. Reaction mechanisms are presented throughout the paper. The methods are compared in regards to their effectiveness in treating various cyanide species: free cyanide, thiocyanate, weak-acid dissociables, and strong-acid dissociables.

Jan 1, 1996

By C. W. Goodale

TOMBSTONE, a name not exactly full of cheerful suggestion, has a great record as a mineral producer and a colorful history as a frontier mining camp. The only practical route to Tombstone in the early 80's was by way of San Francisco and Los Angeles. The Southern Pacific was building across Arizona, and a sleeper was attached to a construction and freight train at Los Angeles, and was trailed slowly across the Colorado Desert to Benson in the San Pedro Valley. Thence one staged 26 miles to Tombstone, which is located near the foot of a range of hills at an altitude of about 4500 ft.

Jan 1, 1925

By A N. Kusnanto, D Sims, L Henim, S Crispin, J Hertrijana

The high sulfidation Purnama Au-Ag deposit located on the Indonesian island of Sumatra entered production in mid-2012 following a two-year program of construction and development. Discovered in 1997 following a regional stream sediment geochemical sampling program by the Normandy Anglo Asia joint venture, it is the first and largest deposit in G-Resource’s Martabe Project to enter production and is the centrepiece of a series of six deposits totalling 8.1 Moz Au and 73.8 Moz Ag in Mineral Resources (G-Resources, 2013a).In 2011 investigation into the controls of high-grade mineralisation in isolated parts of the deposit identified a potentially significant mineralisation style which had not been previously recognised or accommodated in the resource model. An extensive investigation of core and logging data followed to confirm the distribution of the somewhat unusual mineralisation style – a sedimentary-like cavity infill of very high-grade auriferous pyrite within the steep hydrothermal breccia feeders to the system. With the bulk of mineralisation located within the adjacent volcanic sequence and sandy-matrix phreatomagmatic breccia surrounding the feeders, the lack of constraint for high-grade intersections in the hydrothermal breccia zones had potential to significantly impact the mine plan in the lower sections of the planned pit through overestimation of local gold grade. Combined with new data emerging from grade control drilling and infill resource drilling in the pit, a program of reinterpretation of the deposit was initiated to update the geological and alteration framework underpinning the resource model. The result has improved the economics of the project and added metal to the Ore Reserve for Purnama.CITATION:Sims, D, Henim, L, Hertrijana, J, Kusnanto, A N and Crispin, S, 2014. Remodelling the Purnama deposit – an interpretation case study from G-Resources Martabe Project, Indonesia, in Proceedings Ninth International Mining Geology Conference 2014 , pp 229–236 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 18, 2014