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By Y L. Ma, M Chen, W Bruckard

With the extensive exploitation and gradual depletion of high-grade copper reserves, the mining industry is paying more and more attention to the hydrometallurgical extraction of copper from lowgrade and arsenic bearing copper ores. Hydrometallurgical processing, such as heap leaching, column leaching and bioleaching, provide a viable alternative to the traditional pyrometallurgy due to its harmony with the environment, moderate capital investment, and low operating costs. However, the slow leaching kinetics of enargite (Cu3AsS4) and chalcopyrite (CuFeS2) remain problematic for commercial leaching practice. The formation mechanism and the nature of the passivating layers during leaching is still a matter of debate in hydrometallurgical research. In this study, the dissolution mechanism of enargite and chalcopyrite in sulfuric acid solution was investigated using a range of electrochemical and spectroscopic analysis methods. Electrochemical oxidation of enargite demonstrated an obvious passivation region from 500 to 750 mV (Ag/AgCl). The formed passivation film was found a n-type semiconductor behaviour, which is different from the original enargite with a p-type behaviour. The results of X-ray photoelectron spectroscopy (XPS) suggested that a nonstoichiometric film Cu(3−x)As(1−y)S4 (x>>y) accumulated on the electrode surface, which accounted for the obvious decrease in current density in the passive potential region. For chalcopyrite, three important potentials of 550, 680 and 730 mV which are related to the formation and dissolution of passivation film were observed based on the cyclic voltammetry (CV) and potentiodynamic polarisation. Raman and X-ray absorption near edge structure (XANES) spectra studies of the chalcopyrite electrodes after being treated under these three potentials indicated a metal-deficient sulfide of Cu1−xFe1−yS2 (y>>x) might be responsible for the passivation phenomenon. Hence, it is concluded that the passivation of enargite and chalcopyrite are similar which are caused by metaldeficient sulfide surfaces although the compositions of the metal-deficient sulfide are different.

Aug 24, 2022

By Houlihan RN, Landau J

A reciprocating plate column is described in which two sets of perforated plates are mounted alternately on two shafts and are reciprocated with a phase difference of 1800 between them. It is shown that such a column is mechanically superior to the previously proposed types: under practical operating conditions the pressure fluctuations at the base of the column are only a small fraction of the static head. Furthermore, mass transfer experiments with the system tributyl phosphate in kerosene- acid aqueous solutions of uranyl nitrate show that both high specific throughputs and reason- ably good efficiencies can be attained in this type of column. A comparison with the more conventional extraction equipment (mixer -settlers, pulsed columns) on the basis of residence time per equilibrium stage indicates the potential of reciprocating plate columns in hydrometallurg- ical application, especially in which the requirements of separation efficiency are modest while the scale of operation is large.

Jan 1, 1975

The Bureau of Mines, with a history of mining research since 1910, still seeks improvement in safety and health along with improvement and competitiveness in the mining industry. Much promise of such improvements lies in new technology, and this is particularly the case in the still growing coal mine sector, although much Bureau research is long term, high risk, aimed at new concepts.The miner's environment is a primary concern, involving technologies of contaminant monitoring and control in high production scenarios. Contaminants arising from diesel use, alternatives to high speed rotary cutting and more efficient dust removal are being addressed, and drilling efficiencies, better monitoring through unitising operations and insitu rock dust monitoring are particular features.

Jan 1, 1991

By Xizhen J

Point load testing for irregular rock specimens was studied to determine the relationship between tensile and compressive strengths, drill penetration rate and other rotary drilling parameters. The DH-l type point load tester was developed and more than 2 000 irregular specimens of over 60 kinds of rock from 16 mines and quarries were tested. The effects of size, shape and number of samples on the point load strength index were investigated, using regression analysis. Experiments were carried out to investigate the relationship between point load strength index and uniaxial compressive strength on 29 kinds of rock. The relationship between these values and the drill penetration rate for rotary and percussion drills is discussed.

Jan 1, 1986

By Filigenzi M. T

Stresses around mine openings at depth can cause the surrounding rock to fail, releasing stored strain energy. When this happens, the rock may literally explode or `burst' into the opening without warning. As mining progresses deeper into the earth, the possibility of seismic events and rock bursts increases. Researchers at the US Bureau of Mines (USBM) are currently studying seismic activity in three underground hard-rock mines in the United States: the Homestake Mine, Lead, SD; the Lucky Friday Mine, Mullan, ID; and the Sunshine Mine, Kellogg, ID. Waveforms from seismic events are recorded by personal-computer-based hardware and software. This information is archived and transferred from the mine sites to the USBM via modem communication links. Then, using USBM-developed software, the events are analysed to determine various parameters, including magnitude, frequency, and location. In addition, researchers are modelling the deep levels of the Homestake Mine using a finite-element code. These models generate stress and displacement values for a given loading condition. By studying material properties, in situ stresses, and seismic activity along with actual scope sequencing, researchers can make correlations between stresses induced by mining and the frequency and magnitude of seismic events. Information on seismic events coupled with results from finite-element analyses have increased understanding of rock mass behavior and the mechanisms that may lead to rock bursts. Optimisation of slope sequencing designs as a result of these studies could reduce rock burst hazards.

Jan 1, 1995

By E V. Man, O N. Savassi, J-P Franzidis

In flotation, the property that is exploited to effect the separation of a mineral from an ore is referred to as its floatability. Assessment and quantification of ore floatability is of fundamental importance in modelling and simulation of flotation circuits. This paper describes the design, construction and operation of a new laboratory flotation rig that has been developed at the Julius Kruttschnitt Mineral Research Centre (JKMRC) to determine the floatability of different ores on a small-sale. The rig is designed for continuous operation. The major features of the rig are highlighted in this paper. An unique characteristic of the rig is a 9.1 L conditioning vessel. This provides a mixing regime close to plug-flow which avoids complications such as different collector coverages for similarly sized particles (which would considerably increase the complexity of ore floatability determination). The main advantages of this rig when compared to conventional batch flotation cells include better control of the chemical environment and the ability to determine froth recovery, entrainment and water recovery with increased accuracy. Preliminary tests undertaken with a high-grade lead/zinc ore from BHP Cannington are presented demonstrating the good level of reproducibility obtainable in operating the equipment.

Jan 1, 2000

By Jagger N. D

Lead residue from the Zinc Leach Plant at Pasminco's Port Pirie Lead Smelter was previously filtered on a vacuum drum filter and further dried in a gas fired rotary kiln prior to stockpiling and transport to the Sinter Plant. This process involved several materials handling stages, recycled significant amounts of zinc and often resulted in poor environmental conditions. These problems have been overcome by pumping the thickened leach residue approximately 450m to the Sinter Plant where it is filtered in a Larox Automatic Pressure Filter. The filter cake is discharged onto a conveyor belt, held in a storage hopper and then fed directly to the main sinter plant feed stream. Filtrate is returned to the process for additional zinc recovery. The laboratory and pilot plant filtration results are briefly discussed and compared with the operating plant data. The filter installation and ancillaries are described in detail along with the commissioning, operating and maintenance experience over the past 4 years. This installation has overcome the environmental and materials handling problems and resulted in annual savings of approximately $1 million.

Jan 1, 1989

By D Clarke, R Simpson

The Main lode in the Anwia Gold deposit is difficult to interpret due partly to the fact that three separate grid and drill hole orientations exist over the area and partly due to a lack of understanding of the controls on the high-grade mineralisation. Scattered high gold grades and multiple veining orientations add to the confusion. Sectional interpretations of the lode are often misleading due to the multiple orientations of drilling. Initial attempts to define a high-grade constrained geological model were not successful due to the inability to establish any geological continuity that would hold together in three dimensions. As a consequence the initial geostatistical domaining for the Main lode at Anwia comprised a simple broad mineralised envelope split by the weathering profiles. Subsequently an analysis correlating subjective qualitative logging information with grade plus utilisation of LeapfrogTM software, together with extensive geological re-interpretation resulted in the definition of a coherent high-grade shoot within the Main lode. The resource was re-estimated including this new domain as a high-grade hard boundary. Estimations on both models were carried out using uniform conditioning, which is a recoverable resource estimation methodology that estimates tonnages and metal above a series of cut-offs for SMU (selective mining unit) sized blocks. This paper compares the tonnages and metal contents that are calculated from the two estimation runs, both at a zero cut-off and a series of higher cut-offs. The results confirm that the estimation methodology has been implemented correctly as the tonnage and metal content at zero cut-off is the same for both models. The resource tabulations and grade tonnage curves predicted by the two models highlight the differences that can occur at higher cut-offs when realistic high-grade domaining is implemented. The results also reinforce the point that recoverable resource models are intended to address selectivity issues and are not substitutes for good geological modelling. Recoverable resource techniques, such as uniform conditioning, will not correctly estimate high-grade zones that have not been explicitly modelled.

Jan 1, 2006

Preliminary petrographic investigations of eight Upper Permian coal seams of the Muja sub-basin, Collie Coalfield, reveal that the coal is high in inertinite and relatively low in vitrinite and exinite contents. The exinite content of Collie coal is relatively high when compared to other Australian coal of similar age. In addition the mineral matter content of the coal is very much lower than comparable Permian coal of Eastern Australia. The higher exinite content could be attributed to the type of Glossopteris flora, and the lower mineral matter content to the environment of deposition postulated for the Collie Coal Measures.

Jan 1, 1982

Underground measurements, observations and computed simulations, started a long time ago were concerning the study of : - occurence of typical rockburst, - inducing, stretching of main fractures in the roof of caved longwalls. They made obvious a foundamental phenomenon of inducing of strata fractures involving contact be- tween two layers quite different in their elastic characteristics : coalseam and rocklayer.. The start of primary cracks in maximum abutment zone takes place in the rock near the contact surface. It is opening of crevasses induced by traction stress component resulting of difference of rigidity of both materials and no sliding on in- terface. Occurence and stretching of these crevas- ses are a rheological phenomenon so that the rate of advance and stops of the face influence the distance between the crevasses and the stretching of these ones. The characteristics of these cracks in space and time affect mining conditions. So it is for fractures proximity and expan- sion inducing eventual blocks formation in longwall roofs in front of faces, for depth and delay of road- ways ribsides fracturing, inducing some rockbursts. In longwalls roofs, cracks initiated in front of a face can be either quite close or quite distant each from the other one, according to the depth of crushed coal in front of the face, which af- fects also extension of the cracks.

Jan 1, 1988

The Olympic Dam copper-uranium-gold-silver deposit, located approximately 520 km north-northwest of Adelaide, South Australia (Figure 1) was discovered in 1975 by Western Mining Corporation. A joint venture to facilitate development of the deposit was formed in mid-1979 between WMC (51 per cent) and the British Petroleum Group (BP, 49 per cent). Production commenced in 1988, and current annual output from the mining and treatment of 2.2 Mt of ore is approximately 65 000 t of refined copper and 1400 t of uranium oxide. Significant amounts of refined gold and silver are also produced.

Jan 1, 1993

By Miller JD, Ye Y

The Air-Sparged Hydrocyclone (ASH) has been developed for the fast and efficient flotation of fine mineral particles in a centrifugal field during the past decade at the University of Utah. Over the years, the air-sparged hydrocyclone unit has shown promising potential for the flotation of copper porphyry ore, low-grade placer gold and auriferous pyrite ores, various industrial minerals, and fine coal cleaning. Many fundamental studies including the X-ray computed tomography (CT) analysis have been carried out in order to understand the multiphase fluid flow phenomena associated with ASH flotation. With data available from these studies, it is now possible to construct more accurate ASH flotation models for different applications in order to analyse the behaviour of the system and to optimise design and operating variables. The ASH flotation model developed in this paper is based on the data given in `Air-Sparged Hydrocyclone/Advanced Froth Flotation Fine Coal Cleaning', Final Report, DOE Contract No DE-AC-88PC88853, submitted by Pennsylvania Electric Company (PENELEC), December 1989. Data from several hundred experiments with the two-inch ASH-2C air-sparged hydrocyclone (capacity 0.1 - 0.3 tph dry coal) are available from the report and have been used for this analysis. In the past, a preliminary model based on limited data had been developed. The current study, however, emphasises the global behaviour of the ASH system by utilising almost all the data from the report for the purpose of scale-up and industrial application. There are two parts in the current modeling and analysis effort for ASH flotation of fine coal. The first part is the modeling/analysis of dimensionless ratio of overflow opening area to underflow opening area, A*, and the dimensionless ratio of air flowrate to slurry flowrate, Q . The second part involves the modelling/analysis of all other variables in the system and an expert system for operation and control is introduced.

Jan 1, 1993

By Monette J. C, Nulty J. H

High temperatures and pressures are required to obtain acceptable stripping rates. Higher chemically induced stripping rates could reduce the need for higher temperatures which lead to cyanide losses. The higher rates could lead to lower carbon inventories and higher gold production. This paper reports laboratory and continuous test unit data which strongly suggest that the preceding can be achieved. New stripping agents demonstrate efficient stripping under conditions of cyanide depletion such as after carbon acid washing. Stripping times for gold and silver can be reduced by at least half compared to caustic cyanide through the use of these novel substances.

Jan 1, 1991

By Still RF

Sintering of lead and zinc concentrates is practised by Sulphide Corporation Pty. Limited to provide both desuiphurised lump sinter feed, for simultaneous reduction to zinc and lead in the Imperial Smelting Process blast furnace, and sulphur dioxide gas for sulphuric acid manufacture. From November, 1969 a 20 percent increase in production rate has been obtained through improvements in operating technique. A gradual increase in bed permeability was achieved by modifications to the feed mix conditioning equipment and by improving moisture control. However advantage could not be taken of the higher permeability to increase sulphur elimination because the hardness of the lump sinter decreased. Higher throughput, better quality sinter and more stable sintering conditions were however made possible by simultaneously: 1. reducing segregation and compaction in the sinter bed, by narrowing the discharge opening of the main layer feed hopper, 2. reducing the sizing of sinter returns to give a closer size spectrum of particles in the feed mix, and 3. increasing the sulphide sulphur content of the feed mix to give higher bed Temperatures.

Jan 1, 1972

By E Nettleton, A Melkumyan

Identification of geology and mineralogy in situ on the mine face is essential if mining processes are to be automated for tasks such as exploration, grading and reconciliation. Hyperspectral data acquired from field based platforms are ideally suited to these tasks, and are set to revolutionise the automated mining industry. Changing conditions of solar illumination introduces variation into the hyperspectral signal, which is unrelated to geology, complicating analysis of data. Thus, algorithms must be able to deal with changing illumination conditions and operate in a consistent and probabilistic framework, which is a prerequisite for data fusion with other sensors. To produce accurate classification maps of geology, algorithms must be developed that are effective under different conditions of illumination.The efficacy of three algorithms to classify hyperspectral data for geology mapping on vertical mine faces was assessed. These algorithms are the spectral angle mapper (SAM), and two machine learning methods operating within a fully probabilistic Gaussian process (GP) framework û the squared exponential (SE) and the observation angle dependent (OAD) covariance functions (kernel). Two experiments were done to assess the classification performances. The first determined the performance of the algorithms by classifying hyperspectral data of known rock samples acquired using a field spectrometer. The GP-based methods had a similar performance, with average accuracies and F-scores of 97 and 88 per cent (GP-OAD) and 95 and 81 per cent (GP-SE), respectively. Average accuracies and F-scores for SAM were significantly smaller (80 and 40 per cent respectively). The algorithms were then applied to hyperspectral imagery acquired from a vertical mine face at different times of the day, under very different conditions of illumination. In contrast with experiment 1, SAM and GP-OAD gave results which were superior to GP-SE and were entirely consistent with geology mapped in the field. Compared with SAM, GP-OAD was less sensitive to the effects of shadow and produced classified images that were less noisy. The GP-SE method failed to delineate even gross changes in geology on the mine face. These results show conclusively that in order to use independent training data (spectral library) to classify imagery acquired under a different set of conditions, algorithms must take into account variability in incident illumination. Measures based on spectral distance are inferior to those based on spectral angle.The OAD kernel within the GP framework (GP-OAD) is superior to the other two methods because:it provides a probabilistic framework;it is insensitive to variability in illumination within and between imagery acquired under different conditions; andit can identify and map geological zones on a vertical mine face using an independent spectral library, without a priori knowledge.

Sep 26, 2011

Leichhardt Colliery is developed for underground mining of coal seams at depths exceeding 280 m. Investigations of the area were conducted in phases, each designed to delineate seam characteristics more accurately and to indicate with increasing precision the nature of local geological features and the ranges of those coal properties susceptible to variation. The investigational campaign is described phase by phase summarizing evaluation of the area at the conclusion of each phase. Predictions of geological conditions likely to influence engineering planning are contrasted with actual conditions observed during trial mining.

Jan 1, 1974

By Gao K, Wu C, Xia J, Burdett M

X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques have been adopted in this study, to investigate the structure of carbonaceous materials such as graphite, brown coal char as well as coke, in order to explain their dissolution performance during ironmaking. These materials have been selected for study since they are commonly used recarburizers in the metallurgical industry. It was concluded that the crystal structure in a carbonaceous material can have a significant influence on its dissolution into iron melts. The material with the highest degree of ordering, which is graphite, showed the best dissolution performance. In contrast, the material with the lowest degree of ordering, which is brown coal char, showed the worst dissolution performance.

Jan 1, 1996

By Zamel G. I, Zenari L. P

Technological developments in modem Tunnel Boring Machines (TBMs) and associated back-up equipment are offering significant alternatives for mining operators to consider, in the selection of equipment for coal mine development drifts, roadways, longwall gate roads as well as metalliferous mining declines and development drives.Greater flexibility in handling variable ground conditions, muck disposal and radius of turn as well as advance rates, are just some of the areas where modem TBMs can accomplish the flexibility that mine operators require to achieve cost-effective developments.Compact TBMs are achieving this acceptance because of the fundamental design of a shielded machine containing electrics and hydraulics within the forward shell, ability to achieve tight radius of curvature and grades, and ability to provide highly flexible support systems to meet all possible ground conditions.However, a single TBM design will not suit all mine developments, as each development method - while having common goals with all mine developments - will also require certain unique criteria to be fulfilled.

Jan 1, 1993

By Tucker G, Clark A, Young M. F, Johnston M

Mount Isa Mines has made a huge commitment to process control in milling. Yet in lead zinc we still failed to achieve a steady operation. Comparisons with manufacturing plants showed the key difference was failure to control plant inputs. Lead

Jan 1, 1998

Many metallurgical beneficiation and primary concentrating processes rely upon discrimination of products from gangue based on particulate density of the different minerals and combinations of minerals in an ore. The basic definition of density is simple, but the apparent density that minerals exhibit when in the environment of commercial densimetric separation processes is more complex and is ill-defined. Measurement of the apparent density displayed by minerals in their separation situation is essential if modelling of plant performance is to be meaningful or when comparison of an existing operation with a æperfectÆ separation constitutes a part of an audit or of a plant control function. Seven methods of dividing ore samples into discreet density fractions are examined and criticised in this paper. The shortcomings, difficulties and potential errors arising from the use of each method are evaluated. Most of the techniques described have been used by the author and generally their faults are understood and the resultant first-hand experience has been used to overcome these faults. A simple new computer-assisted technique for developing meaningful densimetric data is described.

Jan 1, 2004