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By John A. Haggman

Philippines is a country that is richly endowed in mineral wealth. In 1988, Climax Arimco Mining Corp. (CAMC) geologists found the Dinkidi porphyry gold-copper deposit in Nueva Vizcaya province. It is the most significant mineral discovery in that country in recent times. To date, the company has defined indicated resources of 124 Mt (136 million st) of 1-g/t (0.029-oz/st) gold and 0.4% copper. This includes a high-grade core of 7.9 Mt (8.7 million st) of 6-g/t (0.175-oz/st) gold equivalent. Total contained metal is 124.4 t (4 million oz) of gold and 499 kt (1.1 billion lb) of copper. Dinkidi's discovery resulted from initial geologic reconnaissance and recognition of the intrusive complex that is exposed at surface and anomalous in its topographic expression. This was followed by systematic exploration. This includes extensive gradient array induced polarization (IP), ground magnetics, geochemical sampling and diamond drilling. This later defined a further 16 satellite porphyry targets in the Didipio region. Climax was been granted a Financial and Technical Assistance Agreement contract with the Philippine government. It allows 100% foreign ownership of mining projects. After four years of negotiations, Climax was the first company to have such an application granted. Some 120 applications from numerous international mining companies are waiting for approval following implementation of new Philippine Mining Act of 1995. Exploration history Didipio is located 200 km (125 miles) north of Manila at an elevation of about 700 m (2,300 ft) in the remote Sierra Madre mountains. This region remains mostly unexplored. The property is accessed by 25 km (15 miles) of logging track from the town of Cabarroguis, Quirino. The area experiences an average rainfall of about 3,000 mm (118 in.) a year. Most of it falls during the July-to-November typhoon season. Didipio was first recognized as a gold province in the 1970s when native Ifugao and Ilongot hunters discovered alluvial gold in the region. The region had been prospected over the years by local companies. They were mostly prospecting for alluvial gold. However, in 1988, Climax Mining geologists identified the potential of an obscure razorback ridge protruding from the alluvial valley floor. This ridge, later named Dinkidi by Climax, was the site of several small- scale tunnels. Locals had mined narrow quartz stockwork veining and sluiced soft argillic alteration zones, using irrigation canals and sluice boxes to catch free gold.

Jan 1, 1997

By D. M. Muir, C. Cao

Many gold ores have copper mineralisation which presents problems in a carbon-in-pulp operation. Various types of copper-gold ores and ways of tackling the problem are discussed. In some cases copper and gold can be upgraded to a concentrate by flotation; otherwise, copper or gold can be selectively leached. When both copper and gold cyanide are present in solution, it is possible to minimise copper loading onto carbon or to selectively strip the copper from the carbon. Alternative leach solutions like thiourea and bromine are discussed and results obtained with the ammonia/cyanide system are presented in the light of our present understanding of the chemistry involved.

Jan 1, 1989

By Ken A. Pfaff, Ray Daigh

This paper will discuss state-of-the-art applications of GPS automation in mobile conveying systems. Robotic mobile conveying systems increase profitability, optimize stacking and reclaiming operations, and control complex interfaces more accurately than other systems. We will also discuss the application process in machine-to-machine coordination, selection of the appropriate GPS system, and Ethernet considerations. As the leading supplier of GPS-controlled mobile conveying systems, we'll draw on our experience at Morenci, Radomiro Tomic, Zaldivar, El Abra (Figure 1), and El Tesoro mines in the US and South America to demonstrate system reliability and the lessons we've learned through analysis of these projects.

Jan 1, 2002

By G. B. Misra

Heat transfer in partially wet mine airways has been the subject of study for quite some time. Of the available models some are quite empirical while some involve highly complicated computation. Models developed by Amano, Mizuta and Hiramatsu and Banerjee and Chernyak as well as that modified by Misra were evaluated for prediction of the rise in temperature and humidity (mixing ratio ) of partially wet mine airways at four different levels in the Mosaboni Mine of Hindustan Copper Ltd. Measurements of barometric pressure, virgin-rock temperature and changes in dry- and wet-bulb temperatures along a certain length of airway were made. The rise in dry-bulb temperature and mixing ratio of air over the sections were calculated using the three models. The study reveals that calculated values of temperature and moisture content agree within possible rage of experimental error with all the three models in case of three levels with low wetness factor, but the agreement was poor for the relatively more wet airway on the 30th level. Errors in the estimation of fw to the tune of 0.025 can lead to fair error up to 0.94 K in the estimated temperature while alternative ways of estimating the heat transfer coefficient [] can introduce errors up to 1.45 K.

Jan 1, 1987

All coal preparation unit operations in which fine coal is handled depend to some extent on wettability of coal surface by water. The wetting results from interactions between the coal surface and water molecules that are determined by the composition of coal matrix (interrelated with coal rank) and heterogeneous constituents such as oxygen functional groups, mineral impurities and pores. The contact angle of water on an unoxidized, homogeneous coal hydrocarbon matrix is calculated to be 100o, and much lower values measured on real coal specimens result from contributions from the heterogeneous constituents. While the effect of wettability is critical in flotation and oil agglomeration, suppression of respirable dust, and coal water fuels, it has been shown to play a significant role also in coal flocculation with semi-hydrophobic and totally hydrophobic flocculants.

Jan 1, 1995

By N. Finkelstein, D. A. Hinckfuss

The large and compact but simple Bougainville Copper Limited flotation circuit has been in operation for 3-1/2 years. Discussion of problem areas encountered since start-up and remedies that have been implemented or proposed, form the main basis of this paper. Full cur- rent operational data is also provided.

Jan 1, 1976

By R. L. Jones, D. D. Runnels, D. P. Dupon, D. J. Cline

To establish meaningful remediation goals and monitoring programs in areas disturbed by mining and associated industries, it is desirable to determine the natural concentrations of metals that existed in these areas prior to being disturbed. In mineralized areas, multiple natural populations of metals and associated components may be present. This paper describes a method for characterizing the natural background chemistry by means of probability distribution dia¬grams. The method can be applied to water, soil and other natural materials. In a study of a complicated hydrogeologic system at the Kennecott Utah Copper North and South Operational Areas near Salt Lake City, UT, probability distribution diagrams were used to differentiate between natural background waters and waters impacted by human activities. The probability distribution diagrams allowed a component-by-¬component interpretation of the chemistry of ground¬water and surface water over a large geographic area. Natural chemical background populations and anthro¬pogenic effects were identified Although the method is illustrated for mining-related sites, the same approach can also be used for other natural and anthropogeni¬cally impacted sites.

Jan 1, 1999

By D. A. Swanson, G. Danziger, G. Savci, C. Barnes

Hydrologic assessments of existing and proposed waste rock stockpiles are typically required for application of operating and closure permits at mine sites. A hydrologic assessment should include an evaluation of climatic data and prediction of the net infiltration rate through the waste rock stockpile surface. In addition, hydrologic factors such as the time required to deplete available moisture storage in the stockpiles and the time required for potential seepage to migrate to the underlying aquifer should also be predicted.

Jan 1, 2000

Microwave pretreatment can improve grindability by weakening brittle particulate material prior to size reduction. The differential thermal expansion experienced by multiphase materials during rapid heating can also promote damage in the grain-boundary region, which may ultimately translate into enhanced liberation. The effect of microwave pretreatment on the breakage characteristics of different ores has been studied using the Ultrafast Load Cell. The energy accumulated during impact (fracture energy) and the particle stiffness have been measured for untreated and microwaved ore samples. It has been observed that microwave pretreatment can weaken brittle multiphase particulate material, as observed by reductions in fracture energy and increase in damage.

Jan 1, 1996

By K. Papke

Nine western states contain significant barite deposits, but most deposits are in Nevada, which has been the principal western producer for more than three decades. Nevada produces about 85% of the total United States production, but about one-half of the barite consumed in the country is imported. Approximately 95% of the barite is used in drilling muds. Sharply decreased oil and gas drilling, starting in early 1982, severely depressed the domestic barite industry. Other problems for western barite include long distances to the areas of major drilling, high railroad-freight rates, and increased barite imports. Bedded deposits, formed by submarine exhalative processes, account for almost all western production, and reserves are large.

Jan 1, 1983

By Wayne Stange

Due to the availability of user-friendly microcomputer based packages, the use of simulation is increasing.. Users have however encountered problems inherent to the structure of sequential-modular simulators. These are the difficulties associated with estimating parameters for arbitrary' models and the solution of design and optimization problems. The implementation of an optimization routine in the simulator MicroSim has facilitated the solution of such problems. The literature indicates that more efficient numerical techniques for solving optimization problems than those presently used in MicroSim are available. These techniques, together with user-interfaces which allow such problems to be specified easily by users, will result in the development of simulators much more powerful than existing ones.

Jan 1, 1989

By R. Hiebert, M. Canty, S. Beckman

An innovative biological process is described for the treatment of cyanide-, metals- and nitrate-contaminated mine process water. The technology was tested for its ability to detoxify cyanide and nitrate and to immobilize metals in wastewater from agitation cyanide leaching. A pilot-scale demonstration is described in which a pilot plant was constructed to demonstrate the technology on a mine process-waste stream at a mine in Nevada. The demonstration was performed jointly under the Mine Waste Technology Program (MWTP), funded by the US Environmental Protection Agency (EPA) and jointly administered by the US De¬partment of Energy's (DOE) Western Environmental Technology Office (WETO) under Interagency Agree¬ment Number DW89938513-01-0. The Superfund Innovative Technology Evaluation (SITE) demonstration program was also involved in the project. MSE Technology Applications Inc. (MSE), Butte, MT, was the contractor responsible for conducting the project, and Pintail Systems Inc., Aurora, CO, was the technology provider. The pilot-scale unit was field-tested at Echo Bay's McCoy/Cove Mine southwest of Battle Mountain, NV. The biotreatment process was considered successful in destroying cyanide in the mine process water. The process was also determined to be effective in removing metals. The pH was consistently neutralized and nitrates were successfully removed from the mine process water. From the results of these pilot-scale tests, it was concluded that the biotreatment process potentially of¬fers an innovative, cost-effective alternative for the treatment of mining wastewaters.

Jan 1, 2000

By M. Shen, T. D. Wheelock

The important characteristics of a gas-promoted oil agglomeration process for cleaning coal particles in an aqueous suspension were determined. Numerous agglomeration tests with scale-model mixing systems of different sizes with controlled amounts of air were conducted. The tests were conducted on high- and mediumvolatile bituminous coals using either i-octane or hexadecane as an oily agglomerant. The performance of the system was characterized by employing the minimum time required to produce spherical agglomerates (tE), the mean agglomerate diameter (dp), coal recovery and product ash content. Among these parameters, tE was found the most useful. It is a key parameter in the scale-up of an agglomeration mixing system. This parameter was found to depend on a number of system and operating variables. By controlling these variables and conducting further agglomeration tests with mixing systems that varied in size, an appropriate size scale-up rule was established.

Jan 1, 2002

By B. K. Gupta

Arch Mineral's Captain Mine has used the Bucket Wheel Excavator System(BWE) for over 3 years in conjunction with a 180 yd3 (138M3) stripping shovel. The bucket wheels prestrip the soft overburden ahead of the shovel. This soft overburden is brought to the spoil side through a series of shiftable conveyors and placed by a spreader over the ungraded or partially graded shovel spoils. The placement of the soft overburden and top soil is accomplished in a manner that meets the reclamation mandates. The prestripping by the BWE has reduced the incidence of the highwall and spoil slides, depth the stripping shovel has to dig and the volume handled by the pullback draglines.

Jan 1, 1984

By A. P. Schissler, S. Badr, U. Ozbay, M. D. G. Salamon

Yield pillars are used in deep coal longwall mines, where the depth of cover is so great that a conventional chain pillar design tends to be unsuccessful. The design of yield pillars in deep U.S. mines has been based mainly on experience, pressure arch theories, numerical modeling, and empirical methods that originated in the eastern U.S. coal mines. This paper offers field experience based guidelines for the design of yield pillars through analysis and evaluation of numerous case histories. Case histories of yield pillar applications were collated and critically reviewed to identify trends in data that can be used to formulate the design guidelines. Convincing trends observed in the case of successful case histories indicate that yield pillars should have a width to height ratio in the range from 2.8 to 6.0, a stability factor during development between 0.4 and 0.6, and shed between 94% to 98% of the cover and abutment load, as provided by the Carr-Wilson (1982) method. Also, yield pillars should be utilized in coalmines only where the roof and floor rock have a CMRR rating of 50 or better.

Jan 1, 2003

By D. M. Bodily, M. D. Deo, E. M. Whitney

Field data from coalbed methane wells indicate a significant variation in composition as a function of flow rate and time. In particular, San Juan Basin wells have displayed an increase in C02 concentration over time. Prediction of gas quality is critical to the economic evaluation of any coalbed project. Previous models have forecast only pressure and production profiles, ignoring compositional variations. In this study a multicomponent model that incorporates binary isotherms for methane and carbon dioxide has been developed. An extended Langmuir isotherm is used for the adsorption representation and a constant separation factor (similar to relative volatilities in distillation) describes the phase distribution of the species. This separation factor depends both on the surface characteristics of the coal and on the adsorbing species. The chromatographic separation equations have been superimposed on Darcy's law flow. The formulation allows decoupling of the pressure and compositional partial differential equations. The equations have been cast in dimensionless form and solved for pressures and compositions. It is observed that the composition of the preferentially adsorbed C02 increases at the wellbore as a function of dimensionless time. The dimensionless time is directly proportional to the real time and coalbed permeability and is inversely proportional to the gas viscosity, coal porosity and the square of the length of the reservoir. As the separation factor increases, the compositional variation increases. This variation in produced C02 concentration is also greater when the initial C02 concentration in the reservoir is higher. A sensitivity study has been performed to identify the effects of important parameters such as isotherm variables and reservoir characteristics on pressure and composition profiles.

Jan 1, 1993

By Angus M. Henderson, Charles R. Lilley

Underground mining at Kanowna Belle commenced in July 1998, using a sublevel open stoping method. The use of this stoping method necessitated the use of a cemented fill material for filling primary and secondary stope voids. A detailed engineering study recommended the construction of a cemented aggregate fill (CAF) system for Block A, in favour of paste fill. The CAF system consisted of a crushing and screening plant, a surface binder preparation plant and an underground fill station. Conventional underground dump trucks were used for CAF delivery. Since CAF plant commissioning in March 1999, 1.2 million tonnes of CAF have been placed underground. CAF segregation was the most significant quality control issue during CAF system operation. At the hangingwalls of filled stopes, CAF segregation sometimes occurred to such the extent that the resulting fill material was essentially uncemented coarse aggregate. This caused some CAF dilution during the extraction of adjacent secondary stopes. Numerous CAF were prepared on site for strength testing. A relationship has been formulated that allows estimation of the CAF uniaxial compressive strength in MPa, based on the cement content (c) and porosity (n), as follows. [ ] Practice at Kanowna Belle has confirmed that laboratory testing results cannot be applied for optimising the mix design of cemented rock fills that do not exhibit debris flow behaviour during placement. The grain flow characteristics and consequent marked segregation dominate the in situ fill strength. A detailed review of backfill requirements for the lower mine indicated that the total net present cost of CAF and paste systems was similar. Several significant operational advantages offered by a paste system have resulted in its selection for the remaining mine life. The construction of a paste fill system at Kanowna Belle is currently in progress.

Jan 1, 2001

By J de Cuyper, S. R. Rao, J. Leja, K. S. Moon, W. Freyberger

A prolonged grinding of sulphide ores in steel mills appears harmful to flotation recovery and selectivity whenever xanthates are used as collectors. Particles finer than about 10um show a pronounced decrease in floatability. A supposition was made that the cause of the reduction in floatability of ground sulphides is the presence of metallic iron abraded during grinding and deposited on the ground particles. Electro- chemical measurements were made of mixed potentials developed by different sulphide-mineral electrodes (galena, chalcopyrite, pyrite, marmatite, pyrrhotite) in xanthate solutions, without a direct con- tact or in contact with a metallic iron electrode. These measurements showed that without a galvanic contact between the sulphide and the iron, the values of mixed potentials were in the vicinity of the xanthate/dixanthogen redax potential. When contact with iron was established, the mixed potentials shifted towards the more negative reducing or cathodic values, The shift was greater the higher was the ratio of the surface areas: iron electrode to sulphide electrode. Further, the shift in mixed potentials was greater the more reducing were the conditions on the sulphide electrode. Chemical analysis of reaction products produced on the surfaces of sulphides and in the bulk solution showed that less thiosulphate was formed in all of the sulphide-xanthate systems and that more elemental sulphur was detect-

Jan 1, 1976

By Steve Van Kouteren

Filters and absorbents purify, clarify, and clean many types of liquids by removing solid particles. In addition, absorbents provide a convenient way to handle liquids and to clean up liquid wastes or spills. Filtration or absorptive processes are accomplished either in a mechanical way, as in absorption and filtration, or in a chemical way, as in adsorption. In filtration, minerals and rocks used as filter mediums are extensively utilized in applications requiring the filtration of high volumes of liquids. End use applications include liquid food products, waste waters, petroleum and chemicals, and drugs and pharmaceuticals. Upon closer examination of all of the materials used as filters and absorbents, industrial minerals and rocks represent only a small proportion of the total amount, as shown in [Fig. 1] (Rees, 1991). Given all the industries that use these minerals, most of the volume is concentrated in a few major end-use markets. Within these major end-use markets, a handful of minerals account for most of the total volume and value. The focus for this chapter will be to discuss the industrial minerals and rocks used as filters and absorbents in the most important markets. The selection of the minerals and markets to review is solely based on the total volume of material used and in special cases, those where the value of the market and material is high. The major materials include diatomite, perlite, sand, gravel, and such specialty clays as montmorillonite and attapulgite. These materials are mainly used for the filtration of food, chemical, and petroleum products. In addition, they are used as absorbents for pet litter and oil and grease spills, and as carriers for pesticides and fertilizers.

Jan 1, 1994

By Carl E. Nelson

Shallow epithermal stockworks hosted by maar eruption craters contain over ninety percent of the bulk mineable gold identified to date in the Circum-Caribbean region. Pueblo Viejo (Dominican Republic) and Santa Rosa (Panama) contain combined gold reserves of over 600 tonnes. Bulk mineable gold deposits are also being discovered in and around veins that were formerly mined underground. Bellavista, El Recio and San Martin (Costa Rica) contain combined announced gold reserves of over 50 tonnes. Representative rock suites collected at 8 bulk mineable gold deposits include 291 samples of veins and vein stockworks, hydrothermal eruption breccias, sinter, variably altered host, unaltered host, nearby intrusive rocks and basement. Analyses completed to date show that Circum-Caribbean epithermal ores are enriched in arsenic, mercury and antimony as well as gold and silver. Exploration efforts in the region naturally focus on districts with past production. However, an order of magnitude more bulk mineable gold has been discovered in shallow epithermal stockworks outside of the old bonanza vein camps. Exploration guides include basal island arc volcanic sequences, hydrothermal and hydrovolcanic (maar) eruption breccias, thinly-bedded carbonaceous maar sediments, and hot spring-related silicification and argillic alteration.

Jan 1, 1990