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By Das S. C

A detailed study was undertaken on the effect of Fe+3 in combination with LIX64N during copper electrowinning from sulphate electrolytes. The results show that the presence of Fe+3 not only affects the current efficiency during copper electrowinning but also affects the cathode quality. The effect is enhanced by electrolysis parameters like temperature, circulation rate, current density, etc. No significant effect was found from the presence of Fe+2. The presence of Fe+3 along with LIX64N causes a synergistic effect and results in a drastic fall in current efficiency. Moreover, cathode quality is also affected. A pyramidal structure is favoured in the presence of Fe+3 but the presence of LIX64N along with Fe+3 promotes a ridge structure. Addition of thiourea not only causes modification of cathode deposits, but also a rise in current Efficiency.

Jan 1, 1992

The problems of the as-built water supply system are discussed. Recent modifications to the collection dams and the water cleaning station using wedge wire screens to resolve these problems are outlined.

Jan 1, 1978

By Moylan T, Stewart D

A case study examining the procedures and financial benefits of introducing dump leaching to augment the Mt Gibson Gold Project CIP operations is discussed. Metallurgical testwork, followed by pilot dump leach operations, confirmed that gold recoveries of greater than 60 per cent could be achieved by dump leaching Mt Gibson laterite ore. Capital and operating costs were determined. Pit optimisation using the Whittle FOUR-D optimisation program calculated an optimum cutover grade between CIP and dump leaching for one orebody. The resultant recalculation of reserves based on CIP and dump leach operating costs showed that reserves for that orebody could be increased from 329 000 tonnes at 1.9 g/t An, to 1 488 000 tonnes at 1.2 gh An. NPV for the CIP only option of $1.4 m, was increased to $4.0 m for the combined CIP/dump leach option. This technique can be applied to existing gold projects and to new Developments.

Jan 1, 1992

By Knasmillner

During blasting body wave interaction with geometrical surfaces induces Rayleigh-waves which propagate along free surfaces, e.g. crack faces or delaminated rock layers. These Rayleigh-waves carry most of their energy within a very shallow surface layer and propagate with very little attenuation in real rock materials. Upon interaction with a crack front a very strong mixed mode stress intensity factor may result and lead to fracture initiation. On the basis of experimental photomechanical results the history of dynamic stress intensity factors Kt and K2 will be studied in Detail.

Jan 1, 1990

By den Drijver J

Worldwide, hard coal mining is being carried out at ever increasing depth, and has, therefore, to cope with correspondingly increasing methane emissions. About seven per cent of global methane emissions are caused by coal mining. Beside carbon dioxide, chloro-fluorocarbons (CFCs) and nitrogen oxides, methane is one of the most significant `greenhouse' gases. It is mainly through the release of such trace gases that the greenhouse effect is brought about. Reducing methane emissions is therefore an important problem to be solved by the coal mining industry. This paper begins by highlighting some of the fundamental principles of methane in hard coal mining. The methane problem in German hard coal mining and the industry's efforts to reduce methane emissions are presented. The future development in German hard coal mining is illustrated by an example which shows how large methane volumes can be managed, while still maintaining high outputs at increasing depth.

Jan 1, 1995

Previous studies on the blast furnace raceway zone have been undertaken at three levels of scale, namely: laboratory models at low temperature, hot models which simulate coke combustion in the zone, and tests performed on operating and dismantled blast furnaces. This paper reviews the results of this published work on raceways in order to illustrate the factors which affect the raceway shape, size and combustion characteristics. As a result of the work it has been established that raceways are influenced by blast parameters such as velocity, temperature and chemistry, as well

Jan 1, 1981

The process of evaluating orebodies at the feasibility study stage is extremely important. In recent times many groups have indicated that they would like ore reserve estimation to be numeric and objective. Whilst sampling, geological, mining and mathematical principles may be used to analyse the data, all ore reserve methods require the use of experience factors and as such are value j ddgment statements.

Jan 1, 1990

By M Binks

The Fosterville Gold mine is located approximately 20km to the East of Bendigo in central Victoria. The gold at Fosterville occurs as solid solution within disseminated arsenopyrite and pyrite. The Fosterville ore bodies contain various amounts of native carbon in the form of bituminous coal. This carbon (Non-Carbonate Carbon or NCC) has been the predominant mechanism for gold loss from the processing facility through”preg-robbing”.Processing of the Fosterville ore is achieved initially through crushing, grinding and flotation to extract the sulphides. The sulphide concentrate is oxidized using Bacterial Oxidation, before being leached in a conventional CIL circuit. A high portion of the native carbon (NCC) in the mine ore is naturally hydrophobic in nature, and subsequently reports to the flotation concentrate stream, and ultimately onto the CIL circuit. This NCC has a notable preg-robbing ability. Treatment of Black Shale ores, which have elevated NCC levels, has historically resulted in CIL recoveries as low as 35%, with around 60-80% of the gold loss from the leach circuit attributed to preg-robbing.Standard technologies for dealing with a carbonaceous leach feed have been trialed with limited success. The discovery of the significance of heat on leach recoveries, triggered extensive testwork on a range of leach feed and tails samples. Pilot plant testing demonstrated that “Heated Leaching” of the CIL tails was the best process with an average recovery increase of 7.5% being achieved. Following a successful pilot study, an engineering feasibility study was completed by Minerva Engineering, and the project economics determined. With strong recovery gains evident and a predicted project payback of 1-1.5 years, approval for the installation of the full scale plant was granted. Detailed design commenced in September 2008 with installation commencing in January 2009. The circuit was successfully commissioned in April 2009.Following commissioning, the Heated Leach circuit has achieved recovery gains of 4-14%, and has proven itself to be a significant contributor to the overall plant performance.

Aug 8, 2011

By A V. Ozsever

The selectivity in flotation columns involving the separation of particles of varying degrees of floatability is based on differential flotation rates in the collection zone, reflux action between the froth and collection zones, and differential detachment rates in the froth zone. Using well known theoretical models describing the separation process and experimental data, froth zone and overall flotation recovery values were quantified for particles in an anthracite coal that have a wide range of floatability potential. For highly floatable particles, froth recovery had a very minimal impact on overall recovery while the recovery of weakly floatable material was decreased substantially by reductions in froth recovery values. In addition, under carrying-capacity limiting conditions, selectivity was enhanced by the preferential detachment of the weakly floatable material. Based on this concept, highly floatable material was added directly into the froth zone when treating the anthracite coal. The enriched froth phase reduced the product ash content of the anthracite product by five absolute percentage points while maintaining a constant recovery value.

Jan 1, 2005

By C Morley, B Costello

In 2002 the Argyle Diamond Mine upgraded the process plantÆs recrush circuit to include a High Pressure Grinding Roll (HPGR), or High Pressure Rolls Crushers (HPRC) as they are termed in the diamond industry. HPGR have generated considerable interest over the last decade, though there are still technical/processing unknowns to its effectiveness as a primary diamond ore crusher.The upgrade of the Recrush circuit at Argyle Diamonds has gone a long way to answering some of the key questions, and thus it has reduced the unknowns to a level more acceptable to the industry.This paper focuses on the results from the HPRC at Argyle, in particular the performance of the studded wear surfaces, comparison of energy efficiency against traditional quaternary cone crushers and the resultant increased liberation. Issues that have arisen, including edge wear of the studded surfaces, will be discussed and the steps taken to reduce this issue are presented.

Jan 1, 2004

By Smith S. F, Terezopoulos N. G

This paper discusses experimental results of physical scale models employed to study the stability of a pillar between rectangular roadways. A programme of laboratory investigations utilising a bi-axial test rig has been undertaken to examine the influence of various stressfields on the stability of pillars between mine roadways. The effect of pillar height/width ratio on the overall stability is studied. Observations of failure characteristics in and around pillars are discussed especially in relation to the various stressfields applied to the models.

Jan 1, 1992

By Baczynski NR, Fagan MJ

A 3050m long section of a 1.65m internal diameter tunnel is presently under construction in the Brisbane area by means of the pipe-jacking method. The soils along the alignment had been deposited in a deltaic/estaurine environment and rapid changes in soil type occur. The tunnel passes beneath several extensive bodies of surface water. Groundwater problems have been experienced with tunnelling through alluvial sands and gravels. Details of the ground conditions, the pipe-jacking method used and tunnelling experience are discussed in this Paper.

Jan 1, 1987

This paper examines the impact of the time value of money on the location of mining facilities, as examplified by a central processing plant serving several mines. Three approaches, the Euclidean-Distance Approach, the Gravity Centre Approach, and the Rectilinear-Distance Approach, commonly applied to a single facility location problem were employed in the study. The objective function in all three models was the updated value of the following three costs influenced by the processing plant location and defined within the framework of the continuous model of value representation and the continuous interest rate convention: I. the costs of transporting the useful mineral from the mines to the plant, 2. the costs of constructing the transportation links between the mines and the plant, and 3. the costs of maintaining these links over time. Results of the study show a substantial impact of the time value of money on both the processing plant optimal location and the opportunity cost of neglecting the time value of money in the locational considerations.

Jan 1, 1995

By Palmer DJ

Mercury is introduced into EZ's electroly tic zinc/sulphuric acid plant complex at Risdon, Tasmania, in zinc sulphide concentrate. Mercury is volatilised during the roasting operation and then distributed in the sulphuric acid plant effluents and product acid. Following an investigation of the factors determining the mercury distribution, a plan was formulated to-provide an environmentally accep- table degree of mercury containment at Risdon. This paper discusses details of the various control measures investigated and out- lines the reasons for selecting the particular procedures finally adopted for the Risdon plant.

Jan 1, 1980

By Chamberlain A. C, Fisher N, Avraamides J

The thermal decomposition of sodium ethyl xanthate (SEX) adsorbed onto activated carbon was studied by coupled thermogravimetric analysis-Fourier transform infrared spectroscopy (TG-FTIR). Two discrete mass losses were observed, in the temperature ranges 100 - 230¦C and 200 - 340¦C. The same two gases, carbonyl sulphide (COS) and carbon disulphide (CS2), were the main gases evolved in each of the mass losses. Samples of activated carbon from two industrial plants were obtained and analysed by TG-FTIR. COS and CS2 were not detected in one of the samples. The other sample did show evidence of COS and CS2, which indicated that fouling of the carbon by SEX was still present. Other organic compounds were detected in the evolved gas stream of both samples, indicating the presence of organic reagents other than SEX.

Jan 1, 1996

By Corbett GJ

Magmatic-related low sulphidation hydrothermal ore systems at plate margins exhibit distinct spatial and temporal zonations which can be used to aid mineral exploration and development. Low sulphidation systems at all crustal levels exhibit the same paragenetic sequence of events: early breccia formation, followed by quartz - secondary feldspar - sericite/illite veining, then mineralisation, and final argillic overprint. This sequence of events is interpreted to reflect the initial emplacement of melts at high crustal levels, and the progressive cooling of that melt and release of magmatic constituents into a circulating hydrothermal system.

Jan 1, 1995

By J MacDiarmid

Atlas Copco is a leading provider of industrial productivity solutions (Atlas Copco, 2007) and one of the worldÆs largest suppliers of rock drilling equipment. The business division of Atlas Copco Construction and Mining Technique is based in +rebro, Sweden with the majority of their equipment produced in a number of facilities within the area. As part of the 2006 AusIMM/Atlas Copco Scholarship I was fortunate enough to visit these facilities to experience first hand this truly unique global company. Through numerous presentations on the various divisions and products manufactured by the company, I saw the broad range of products and services offered by the company and came to realise it is much more than just selling drills. Other highlights included a brief love affair, a tour of EuropeÆs largest underground mine (or factory depending who you ask), a drink at the ice bar at the ice hotel in JukkasjSrvi, and a number of dinners of reindeer. Overall this it was a truly amazing experience with all involved with the program going out of their way to ensure I got the most out of the trip. More importantly, through no effort at all, everyone naturally conveyed their passion for the industry and the company which is a great credit to the æAtlas Copco WayÆ thereby creating a company æcommitted to your superior productivity through interaction and innovationÆ.

Jan 1, 2007

Broken Hill is situated at an elevation of approximately 1000 ft. above sea-level, on the Barrier Ranges, in the State of New South Wales, Australia. It is approximately 700, 280 and 330 miles from the ports of Sydney, Pirie, and Adelaide, respectively.The summers are usually hot and dusty, with a recorded maximum shade temperature of 114° F. The rainfall averages approximately 9 in. per annum.

Jan 1, 1932

The orebodies at Kambalda are complexly faulted, folded and intruded. It is realized that the ore reserve calculations will be wrong and steps are taken to minimise the errors. The calculations are a combination of computer data handling and manual input. Initially Geological Ore Reserves are calculated and then production data and experience are used to produce a Planned Mining Reserve. At all stages maximum professional judgement is incorporated. The basis of the calculation is the polygonal method of area estimation, and production reconciliations together with the style of data available indicate that it is a most suitable technique. It is also a tech- nique that is easily communicated to all levels from operators to management.

Jan 1, 1979

This paper describes the application of a three-dimensional finite element modelling tool to help assess the stability of a highwall at a Central Queensland mine following the weakening of its base due to highwall mining. With traditional stability assessment techniques, likely failure modes are identified on the basis of previous experience and structural, sedimentological and geomechanical data and a mechanistic analysis of these individual modes is performed. The value of the full three-dimensional model over these traditional techniques is that it provides a coherent approach to assessing highwall stability without the necessity of initially deciding upon the dominant failure mechanism and gives a useful adjunct to the traditional tools. The three-dimensional model assumes the rock mass is made of elasto-plastic blocks, incorporating possible planes of weakness, separated by near horizontal joints. The model includes the relaxation of stresses due to the excavation of the highwall and incorporates estimates of blast damage near the highwall surface

Jan 1, 1995