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By C. O. Brawner, J. Kalejta II

The classical approach to control rock fall and ravel in open pit mining has been to use catch benches. The width and volume of benches is most dependent on the bench height, size of loading equipment, blast damage to the face and mining regulations. This was compatible with open pit slopes of less than about 45°. As our understanding of rock mechanics and blasting control has improved over recent years, much steeper rock slopes can be developed at many open pit mines. However, narrower benches result with less rock fall capacity. The transportation industry has been very successful in using catch fences to protect highways throughout North America and Europe for years. The authors recommend that cable and ring net fences have a potential major application in open pit mining to allow steeper rock slopes with significant economic benefit. This paper outlines the application, design and operation of catch fences in surface mining for specific conditions. Typical case examples are presented.

Jan 1, 2002

By A Tomsett, J Rutter

Ore control systems at Ridgeway have been designed to deliver gold and copper metal production through focussing on the ore characteristics that impact on mine and mill performance and ultimately metal delivery. This is achieved using data collection and management systems which allow data to be collected digitally with æat captureÆ validation routines. This data forms the basis of forecasting systems which aim to accurately assess local in situ and drawn ore characteristics. Physical attributes of ore such as draw characteristics, brow conditions and visual grade estimation are rountinely recorded. Ore tracking and accounting systems monitor gold and copper grade, copper mineralogy, host lithology and ore sizing. These have material impacts on concentrator throughput and metal recovery. Routine reconcilation and check sampling allow calibration of these systems.

Jan 1, 2002

By Thomas J. DeMull

Development of the Batu Hijau copper project was completed in the fourth quarter of 1999 with the formal handover and start-up of ore processing facilities. The project began in August 1996 when the owner, PT Newmont Nusa Tenggara (PTNNT), awarded an engineering, procurement and construction (EPC)contract to Fluor Daniel (FD) for the development of the project. This included a copper concentrator, port, power plant, town site and infrastructure. PTNNT managed the development of the mine and the procurement of the mine equipment. In 1996, Batu Hijau was the largest mining project ever undertaken. Developing the Batu Hijau Mine was complex. It involved the work of thousands of people in all parts of the world to plan, engineer, procure, fabricate and manufacture equipment, supply and deliver materials and equipment, and build the plant.

Jan 1, 2002

In 1991, Placer Dome Venezuela established a 70% stake in Minera Las Cristinas, to mine the Las Cristinas gold deposits in Bolivar. This case study examines the multi-sectoral partnership arrangement that was developed to improve health services near the proposed Las Cristinas gold mine. The investment climate in Venezuela is uncertain and the socio-economic circumstances are potentially hostile. Despite that, the partnership between the mining company, local communities, government agencies and an international health nongovernmental organization (NGO) collectively leveraged nearly $2.5 million to build and operate a community health center.

Jan 1, 2002

By J. D. Noll

Elemental carbon (EC) is used as a surrogate for regulating the exposure to diesel particulate matter (DPM) of underground metal/non-metal miners. EC was chosen as a surrogate because EC is selective to DPM and is a major component of DPM. Using EC as a surrogate also gives one the advantages of no sampling artifacts and being able to sample at all locations in the mine. Currently, EC represents DPM well in underground mines. Some control technologies have been shown to possibly alter the relationship between DPM and EC and characteristics of DPM. Therefore, future work will investigate the relationship between DPM and EC as new control technologies are implemented.

Jan 1, 2002

By Robert Snow, Yingxue Yu, Patrick Zhang

The FIPR/SAPR process is FIPR's third approach to develop a viable alternative to the Crago "Double Float" process for phosphate flotation. SAPR stands for Single-collector, All-anionic Phosphate Recovery. The FIPR/SAPR process - offers a universal flowsheet for any anionic reagent system and flotation feed of varying sizes. For an unsized or fine flotation feed, the FIPR/SAPR process consists of the following steps: 1) high-solids conditioning with an anionic collector; 2) anionic rougher flotation, with the rougher concentrate sized at 48 (or 65) mesh and the +48 mesh recovered as a final product; and 3) cleaning flotation of the -48 mesh fraction from step 2. In a variation of step 2, the rougher concentrate from the first two cells may be collected as a final product, and the rougher concentrate from the last two cells sized at 48 or 65 mesh. The new process was tested with a blend of anionic collectors, achieving single-digit Insol at 85 + % recoveries.

Jan 1, 2002

By A. I. Kalugin, A. A. Abramov, D. E. Kozlov, D. V. Magazanik

Based on theoretical and experimental researches of phosphate and carbonate minerals flotation in the presence of soluable glass at various pH values and sodium silicate concentrations, it has been established that the presence of soluble glass in solution leads to formation of silicate compounds on the surface of phosphate and carbonate minerals causing change in their floatability for the worse. The harmful influence of soluable salts is done by tying of collector as metallic soaps, forming precipitates on the surface of minerals to be floated and causing their depression of flotation, and breaching of the froth etc. Depressing action of slimes and products of interaction with collector depends on the ratio of values and signs of potentials of the mineral surfaces. The possibility of phosphate and gangue minerals separation can be evaluated by comparing the minimum-necessary concentrations of collector required for their flotation.

Jan 1, 2002

The relationship between comminution testwork results and the milling circuit that is subsequently selected is not a direct one and frequently involves recourse to databases of past test results. This in itself reflects the lack of a systematic engineering approach in the design process. This paper reviews comminution tests for SAG mill design in an attempt to identify where the essential information comes from that will be used in mill selection. The conclusion is that results from traditional test methods, including obscure and little used procedures like the Mokken test, are more valuable from an engineering perspective than parameters for breakage rate based modelling. Suggestions are made on ways in which existing test procedures can be enhanced in order to generate parameters that can be directly related to characteristics of the milling circuit being designed.

Jan 1, 2002

By H. Maleki, G. Tetreault

This study was initiated by the US Bureau of Land Management (BLM) to develop guidelines for determining the maximum economic recovery of resources in coal mines. The work was in response to a requirement in the Mineral Leasing Act of 1920 and Federal regulations. The intent was to address the economic rainability of small, irregular reserves in existing longwall mines. In particular, there was a need to determine if room- and-pillar mining using a continuous miner (CM) was economically sound or whether unconventional (short or odd-shaped) longwalls could be used to recover small coal reserves economically. Small reserves, called "widgets " are left in longwall mines on one side of the mains near outcrops and adverse geological conditions or near any other location where reserve geometry does not lend itself to mining with a rectangular longwall panel. The work included the analysis of the geologic, geotechnical and economic factors that influence the recovery of small coal reserves; the analysis of historic changes in supply, demand and coal prices; the development of typical cost models for room-and-pillar and longwall mines; and the development of a practical methodology for determining maximum economic recovery. The methodology included an evaluation of the ratio of coal mined during longwall mining to that mined for development (LDR), as well as costs of maintaining coal quality depending on market conditions. The LDR is a good indicator of mine efficiency and overall coal recovery in modern longwall mines and, thus, is used to evaluate the increased costs associated with adding new development sections for extraction of small reserves. The study examines the economic feasibility of using unconventional longwalls for the recovery of medium-sized reserves, depending on site-specific geologic and geometric conditions.

Jan 1, 2002

By Kurt Burg, Allen Reicks

Tapered clamping devices have been used successfully over the years to transmit torque and bending loads from conveyor drives to conveyor belts. Proper design and application is important in the successful operation of these key components. This paper includes a historical review of component design and application and an overview of the important dynamics and limiting factors. Actual applications and simulation models are used to demonstrate the correct use of these devices.

Jan 1, 2002

The complete life cycle of a production facility has many phases requiring many different skills and many different personalities. It is not unlike the life cycle of a person and many parallels can be drawn from it. I leave some of these analogous situations to your fertile minds. The author, having worked in operations, plant design, plant commissioning, marketing and many other interesting situations through the industry has drawn from this experience and examples given by many associates in the industry.The phases seen are as follows: Concept Studies û someone has a bright idea of how to make a dollar. Scope Studies û what possible processes/options that could make a dollar. Prefeasibility Study û the æviableÆ scope options are studied to develop feasible options. Feasibility study û defines the concepts that should be designed to make a viable project thus enabling financing and project commitment to be made. Detailed Design û an intermediate step that consolidates the inputs to give a robust plant that can be constructed.Construction û people can see what they thought was going to occur and start to understand the plant. Commissioning û the hand-over of æownershipÆ from the conceiverÆs to the operators. Operations û the ætoyÆ has become reality and money must be made. De-commissioning û the plant has seen out the useful life of the ore deposit, it now goes through a further process required by society.Across these phases of plant design run several countervailing management requirements that can influence the outcome of the plant design. Some of the management rigours that have to be applied to the various phases are as follows: costing basis of the various phases; operational and maintenance reviews; sustainable development; risk assessment; reliability reviews; equipment availability; commissioning time; and environmental review.This paper endeavours to awaken people to the phases that projects require for a successful outcome and the management rigour that has to be applied throughout the phases to ensure the correct intellectual horsepower is applied at the right time to ensure the best outcome.Many of you would be parents and realise this is not unlike the development of children, teenagers, adults, retirees and ongoing.

Jan 1, 2002

Novel flotation reagents were developed to improve the flotation of coarse particles. Laboratory tests conducted on an anthracite coal sample from Kyung-Dong Coal Company, Korea, showed that the reagents can successfully clean 2?3 mm top-size materials. Pilot-scale tests conducted on a 1.41 mm x0 coal gave substantially better results than those obtained using kerosene as collector. The pilot-scale test results were used to develop a flowsheet, in which the 1.41 mm x0 fraction is cleaned by flotation and the 4 x1.41 mm coal is cleaned by single-stage spirals. The performance of this circuit was compared with another flowsheet, in which the 0.5 mm x0coal is floated using the conventional flotation reagent, with the 4 x0.5 mm material being cleaned using two separate spiral circuits. The performance of the two flowsheets was compared by computer simulation. The results showed that the flowsheet consisting of the coarse particle flotation circuit can give substantially higher yield sat a given product grade. Keywords: coal flotation, coarse particle flotation, collector, spirals, computer simulation.

Jan 1, 2002

Over years of exploration the massive and tabular orebodies in the area to the South West of Western Areas Gold Mine had been assessed as containing about 50 million ounces of gold û a world class orebody. Planning initially was for a surface and subvertical shaft system to exploit this area but because of cost, a single lift shaft to an area which could be accessed ex Western Areas was planned to intersect the reef at 2760 metres. It was also planned to mine out the shaft pillar area long before the deep shafts would reach that position. This is not the normal practice in South African Gold Mines. The stoped out shaft pillar was backfilled to minimise movement in the shaft sites. The result of a competitive tender/adjudication process was that Cementation Mining û Skanska won and was awarded the R192 million contract to sink the Main and Ventilation Shafts on 15 June 1995. On 1 April 1999 Western Areas and Placer Dome SA formed a Joint Venture, which now owns and operates the mine on which the South Deep Shafts are situated. This situation prevails today.

Jan 1, 2002

By V Lickfold, A J. Crawford, A J. Wilson

A total of 12 alkalic porphyry centres of Late Ordovician age have been discovered in two mineral districts within NSW. The alkalic porphyry deposits are hosted within shoshonitic volcanic centres that formed where a major cross-arc basement structure (the Lachlan Transverse Zone) cut the Ordovician Macquarie Arc. The Macquarie Arc was amalgamated with the back-arc basin sediments of the Wagga Marginal Basin and with the proto-Pacific margin of Gondwanaland to form the Lachlan Fold Belt after the cessation of arc magmatism in the Late Ordovician. Within the Ordovician volcanic belts of NSW, the alkalic porphyries are the most significant mineral deposits economically. The combined resource of the Cadia district porphyries (729 Mt @ 0.79 g/t Au and 0.30 per cent Cu) makes Cadia the worldÆs seventh largest known porphyry gold system and the largest known gold resource in an alkalic porphyry system (574 t Au). Hydrothermal alteration in the alkalic porphyries comprises a complex sequence of potassic, calc-potassic, sodic, calc-sodic, propylitic and late-stage, typically fault-controlled phyllic assemblages. Hematite dusting is common in many of these alteration assemblages, giving the intrusions and the altered volcano-sedimentary host sequences a distinctive pink-orange colouration. Intensely developed hydrothermal alteration assemblages are localised to within a few hundred metres of the composite intrusions that sourced the mineralising fluids, making these deposits difficult exploration targets. Sulfides are typically zoned, with several of the deposits having bornite-rich cores, chalcopyrite-dominant annuluses and pyritic outer haloes. Gold is well correlated with bornite in most of the deposits, and with chalcopyrite at Cadia Hill.

Jan 1, 2002

By Kokichi Iizasa

Kuroko-type deposits exist in Japanese EEZ. Some of them are present in the Izu-Ogasawara oceanic island arc south of Tokyo. Major two Kuroko-type deposits occur in the area. One is the Sunrise hydrothermal field occurring on the caldera floor of Myojin knoll, which is likely to be the developed stage in sulfide mineralization. Another is present in the crater of Suiyo seamount that is the early stage of sulfide mineralization. The two deposits are here presented on the growth history based on samples recovered by Benthic Multicoring System (BMS).

Jan 1, 2002

By Dominique Vié

Standards methods covers the procedures for testing deep foundation to determine the force and velocity response to an impact of a pile driving hammer or similar device. The results of analysis generally include an assessment of pile integrity and the value of maximum dynamic stresses. But evaluation of static bearing capacity remains a matter of individual engineering judgment. A new 1D finite elements model has been developed for dynamic stresses and velocity analysis. Following an international benchmark of bearing capacity prediction organised by the Belgium Building Research Institute (BBRI), 12 piles in a site of fissured stiff tertiary clay tested in 1999, and 12 piles in a site of dense sand tested in 2001, comparison are proposed between analysis of dynamic tests and static tests results. A procedure is proposed to take in account the results of dynamic test for evaluation of bearing capacity.

Jan 1, 2002

By Frank S. Hicks, Y. Charles Guan, Glenn A. Gruber

This paper describes a two-part program funded by the Florida Institute of Phosphate Research and performed by Jacobs. The first part of the program was to examine the application of ultrasonic treatment to clean phosphate particle surfaces. Florida phosphate pebble and rougher flotation feeds were treated in an ultrasonic trough to remove clays. Also, the de-oiling of rougher concentrates by ultrasonic treatment was tested. In order to improve the clay removal efficiency, viscosities of primary cyclone overflow from six beneficiation plants were studied in the second part of the program. Viscosities for different samples at the same clay % solids vary significantly, and increase exponentially with clay % solids content for the same sample. A method of controlling cyclone operation using on-line viscosity measurements and pump box level sensors is proposed to logically improve primary cyclone performance.

Jan 1, 2002

By H. Arima, T. Fujita, W. Yen

The copper catalyzed gold oxidation and reduction mechanisms in ammonium thiosulfate solution were investigated by Eh-pH diagram based on the optimum reagent combination for 60 mass% -75 µm silicate ore at 16g/t Au with the maximum gold extraction of 92% and the minimum ammonium thiosulfate consumption of 23 kg/t-ore for 24 hour’s leaching at ambient temperature. The gold recovery by cementation was nearly 100% by Zn and Al powders at Metal/Au mass ratio of 30, and around 95% by Cu powder at Cu/Au+ mass ratio of 50. In order to oxidize the gold efficiently with the less thiosulfate consumption, the stable region of [Cu(NH3)4]2+ should be as wide as possible in the region, where [Cu(S2O3)2]3- was more stable than [Cu(NH3)2]+. In order to reduce gold from the pregnant solution with the less metal powder’s (Zn, Cu, Al) consumption, the stable region of [Cu(S2O3)2]3- should be wider than [Cu(NH3)2]+ on copper precipitation. Zinc powder may recover gold more efficiently than copper powder with the similar trend on the effect of ammonia, copper and thiosulfate. However, the large amount of copper will be co-precipitated along with gold since the stability of zinc ammine and thiosulfate complexes are higher than that of copper’s. Aluminium may reduce gold efficiently at higher thiosulfate concentration and pH. These results were confirmed and compared with the optimum reagent combination for finer grind sample at 100 mass% -75 µm, which is the optimum ore size for the standard cyanidation at 1.0 g/ l NaCN to obtain about 95% gold extraction. The optimum reagent combination was concluded as 0.5 mol/l NH4OH, 0.0001 mol/l CuSO4*5H2O and 0.05 mol/l (NH4)2S2O3 with the result of 94% gold extraction and 3kg/t-ore of ammonium thiosulfate consumption. Gold and copper stabilities were well agreed with the result of coarser grind ore thermodynamically. The lower reagent combination will reduce gold oxidation power, but significantly minimize the reagent consumption. From this pregnant solution, nearly 100% of gold was successfully recovered by zinc precipitation at Zn/Au+ mass ratio of 30. Aluminium and copper precipitations resulted in less than 40% of gold recovery at Metal/Gold mass ratio of 30. The reagent consumption cost on this lower reagent combination followed by zinc precipitation was $1.6/t-ore, while the cyanidation was $3.1/t-ore. Thiosulfate oxidation mechanism indicated the similarity to Belousov-Zhabotinsky reaction.

Jan 1, 2002

By R. Codell, D. L. Hughson

The authors benchmarked the integrated finite-volume code MULTIFLO against the analytical solution of Philip et al. (1989) for cylindrical underground openings. They found that the numerical simulation of dripping threshold flux was consistently higher than the analytical solution for rectangular and unstructured grids. The magnitude of this error was proportional to the alpha parameter characterizing capillarity. This error may bias estimates of seepage into drifts for repository performance towards nonconservatism.

Jan 1, 2002

By R. W. Schutz

"Titanium possesses an exceptional and wide-range resistance to chlorides and their compounds when compared to most corrosion-resistant engineering alloys (CRAs) used in the chemical process industry. This natural resistance to chlorides stems from titanium’s protective, tenacious, and readily rehealable titanium oxide surface film, which is chemically stable over a wide range of pH and redox potentials in aqueous environments. This passive film explains titanium’s elevated resistance to anodic pitting, crevice and stress corrosion, and erosion-corrosion in aqueous chloride environments.Guidelines for successful selection and application of industrial titanium alloys are derived from an extensive laboratory test database and more than forty years of industrial/chemical service experience. These guidelines are simplified, and alloy corrosion performance is assessed with respect to four basic aqueous chloride service categories where selection or consideration of titanium is highly merited. An overview of historical titanium alloy applications in chloride-rich environments in a wide variety of process industries substantiates their exceptional chloride tolerance. These industrial titanium alloys are cost-competitive with stainless steels and nickel alloys, readily commercially available, and routinely fabricated and welded in the shop and field via well-established methods."

Jan 1, 2002