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By P M. Downes

Porphyry-related skarns are common around thePacific Rim. Examples include Cadia and Goonumbla (Australia) Ok Tedi (PNG) and Ertsberg and Grasberg (Indonesia). Although usually treated as separate to the adjacent porphyry copper-gold (Cu-Au) deposit, skarns near porphyry deposits are commonly inextricably part of the larger Cu-Au system(s). Using Cadia as the primary example, we demonstrate that large, zoned, calc-silicate skarns necessitate very large porphyry systems. The Big Cadia and Little Cadia Fe-Cu-Au skarns are associated with the Late Ordovician to Early Silurian high-K calc-alkaline to shoshonitic Cadia Intrusive Complex (CIC). Together, these skarns total ~40 Mt of Cu-Au ore but are much smaller than the adjacent Cadia EastûFar East, Cadia Hill, and Ridgeway porphyry-related Cu-Au deposits. Historically these skarns were large, economically significant and highly controversial deposits. Porphyry-related skarns typically have well-developed calc-silicate and ore zonation. At Cadia, classic skarn zonation has been mapped between Cadia Quarry (proximal) and Big Cadia (distal). Over this 800 minterval, mineralogy trends from: proximal garnet > pyroxene, grading to; fe-oxide-rich skarn; and distal haematite-epidote-rich skarn. At Little Cadia, analogous but symmetrical alteration zonation is present. Big Cadia formed from fluids that migrated laterally within calcareous units and were sourced from strongly altered quartz monzonite phases of the CIC at Cadia Quarry. Isotope studies and mass-balance calculations suggest that prograde and retrograde skarn alteration was caused by magmatic dominated fluids. They also indicate that the mapped alteration system at Cadia Quarry is insufficient to account for the total volume of Fe present at Big Cadia. Despite the typically oxidised nature of many porphyry systems, not all skarns in the porphyry environment are oxidised. Assimilation of carbonaceous sediment by hydrous, alkaline intrusions could lead to reduced Au skarns rather than porphyry deposits. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By William J. Miles, Raymond E. Blair

The oil and gas drilling industry is the largest user of "functional" industrial minerals for well drilling and completion. (Functional industrial minerals can be defined as those used for performance characteristics rather than composition.) This industry's use of industrial minerals involves complex mining, processing, and distribution of products. The cost of these products at the well site reflects the complexity of distribution to typically remote locations and the cost of service. Table 1 illustrates the use of functional industrial minerals by the drilling industry. The total tonnage shown is almost 2 1/2 times larger than the 3.3 Mt (3.6 million st) of kaolin used by the paper industry for filling and coating, another major use for functional industrial minerals. Drilling fluids are an indispensible part of a drilling operation. These fluids perform several functions simultaneously. They cool and lubricate the drill bit, remove formation cuttings, increase the specific gravity of the fluid to counteract formation fluid pressures, provide a filter cake on the wall of the drill hole to prevent drilling fluid loss to the formation, protect the porosity of producing zones, and prevent reaction of the formation or formation fluids with the drilling mud. When porosity of a formation exceeds the ability of the drilling fluid to form a wall cake, it is referred to as lost circulation. Because these fluids are being constantly formulated for changing formation conditions, they require a skilled technician or drilling mud engineer on the site at all times. Drilling fluids are composed of oil or water as the liquid phase, and industrial mineral products and chemicals to control chemical and physical properties. The basic function of viscosity and suspension result from the use of gelling clays and chemical and mineral dispersants; specific gravity of the mud is adjusted with mineral weighting agents; filtration control is maintained by clays and various natural and synthetic polymers; platey minerals and scrap products are used for controlling lost circulation in porous or fractured zones; salts are added to the mud to inhibit shale and clay swelling; chemicals are added for pH adjustment, prevention of corrosion, and as scavengers for formation fluid components. Because of the clay component, drilling muds have rheological properties different from conventional fluids, behaving as Bingham plastic fluids as opposed to the Newtonian behavior of water and oil. Newtonian fluids will begin to flow with the application of any force, however small. Bingham plastic fluids require a finite force or shear stress (yield value) before flow begins. Thixotropy is another property of clay-based drilling fluids. At rest they form a gel structure that suspends the weighting agents and rock cuttings. These gels break down when a finite force is applied and circulation is restored. At the bit where shear rates are the greatest, the viscosity or resistance to flow decreases, so hydraulic pressures and pumping costs are minimized. A drilling rig provides a means of rotating a hollow pipe attached to a cutting bit. A mud pit or tank is used for mixing the drilling mud and its components. A centrifugal pump delivers this fluid to the drill ripe and down to the bit

Jan 10, 1983

By Paul C. Hyndman

No minerals have been produced from the McGraw Creek RARE II area. During the 1982 U.S. Bureau of Mines study, there were no active mines in the area. Limestone occurrences (fig. 1, no. 2), four copper prospects (fig. 1, no. 1, 4, 5, 6), and a prospect with no significant mineral values (fig. 1, no. 3) were examined. A moderate potential for high-calcium limestone resources was estimated between ocurrences within the study area near McGraw and Spring Creeks (fig. 1, no. 2). There is low potential for copper resources at the Argenta Prospect (fig. 1., no. 1) in the study area, and the McDougall Prospect adjacent to the area.

Jan 1, 1983

By Nic Arrieta

The Arimetco White Cliff Diatomite operation near Tucson, Arizona will be discussed and reviewed across the spectrum of geology, mineralogy, mining, processing and product attributes and market applications. Unique for the operation are the type, quality and the extent of the reserves and several product characteristics of the diatomite.

Jan 1, 1996

By Grainne A. Matthews

Jan 1, 2009

By Brad H. A Brown, J Paul Tidman

To design a blast, one must give consideration to safety, economics, geometry, geology, production needs, and a variety of other requirements. To compare designs requires the time to develop alternatives, analyze, and then improve on them. A number of tools are available to assist with the first set of requirements, however they are poorly integrated. SHOTPlus is a program to improve the efficiency of blasting operations, by combining measurement and blast design tools, and offers the user the time and means to modify designs and explore alternatives.

Jan 1, 1997

By M. G. Ayat

Coal degradation is the breakage of coal particles to finer sizes due to the continuous forces of attrition and gravity to which coal is subjected during mining, handling and preparation. The objective of this paper is to determine the extent of degradation that a coal slurry experiences when transported through pumps and pipelines. The examination of degradation results for a number of different coal slurries have indicated that the extent of breakage is dependent upon the physical properties of coal and the time span of circulation. These results have also indicated that certain size fractions of coal are more susceptible to breakage than others.

Jan 1, 1986

By Joseph L. Condon

The U.S. Department of the Interior, Bureau of Mines, is doing research on methods to obtain premining information on problems such as detection of old mine workings, abandoned oil wells, channel sands, faults, and other geologic features that are undesirable from a production or safety aspect. Techniques being developed to acquire the necessary information include seismic and electromagnetic. The seismic methods include high-resolution seismic and acoustic methods applied from the surface and inseam channel waves applied under- ground. The electromagnetic, or radar, methods are applied from the surface, from boreholes, and from the working face underground. All of these methods are useful under certain site-specific conditions, but none of these methods is universally applicable for all mining conditions.

Jan 1, 1980

By Doug Milne

Linking Classification Systems with each other Similar Parameters between systems Different Rock Mass Properties Rock Mass Classification parameters and geology Different sources of data Commonly Used Rock Mass Classification Systems Q? = Q with SRF = 1.0 RMR? = RMR with no joint orientation correction RMR76 = 9lnQ + 44 RMR?76 = 9lnQ? + 44 RMR76 = RMR89-5 RMR?76 = GSI = RMR89-5 MRMR = ??MRMR

May 1, 2013

By Roger Moss

OUTLINE Area selection Mineralization/Alteration Styles Island Copper Mineralization Geophysics Geochemistry Coppercorp Setting Mineralization Geophysics Geochemistry Formation Common Characteristics Conclusions

Apr 1, 2005

The concept of "classification is expanded beyond the performance of the classifying equipment to include all aspects of the fines removal system of the grinding circuit. Design and operating parameters which affect fines removal are identified and discussed, and a quantitative index for circuit fines removal effectiveness is defined. This approach lends new interpretation to certain observed phenomena, and suggests useful guidelines for circuit design and operation.

Jan 1, 1985

By R. Switalski, M. Schafer, R. Pintabona, M. Kritzer, B. Lukajic, S. Janosko

Methane gas caused an eight-month shutdown of mining operations at the Mill Creek, Phase 3, Tunnel. The gas-related shutdown occurred as the tunnel was advanced to an approximate distance of 2,700 feet, which constitutes approximately18% of the total tunnel length. The construction of an emergency ventilation shaft, a comprehensive program of de-gassing wells and an expanded gas monitoring system were used to mitigate the gas condition. When complete, this tunnel will be utilized to convey and store combined storm and sanitary sewage collected from a portion of Cleveland, Ohio and ten suburbs. This paper will provide an overview of gas related remedial measures and explain how these measures were integrated into the project to ensure safe tunneling conditions.

Jan 1, 2007

By G. Deschenes, W. Yen

Ammonium thiosulphate is a non-cyanide lixiviant for gold leaching. The major problem is the high reagent consumption. A combination of 0.3M (NH4)2S2O3, 0.03M CuSO4, 3M NH3 was used to leach a copper-bearing gold ore at pH 10.2 for 24 hours. 30 kg/t of thiosulphate was consumed. Oxygen and copper species were found to be responsible for thiosulphate decomposition. The thiosulphate consumption could be reduced to around 17 kg/t by adding chelating agent, reducing copper sulphate concentration to 0.001 M and replacing CuSO4 by NiSO4. The increase of pulp density might reduce the thiosulphate consumption to around 17 kg/t. By regulating the oxygen supply, the thiosulphate consumption could be reduced to 10 kg/t.

Jan 1, 2002

By Craig Dirk

Agenda Applications of ?GPS ?Drill Navigation ?Cycle time monitoring ?UDS / Boom Stress monitoring ?Payload systems ?Laser Surveying Future Applications

May 1, 2006

By Michael Moran

Typical ACIP Pile Rig [ ] Hollow Stem Auger ? Continuous flight auger ? 3 inch inside diameter pipe ? Auger diameters: 12, 14, 16, 18, 20, 22, 24, 30, and 36 inches ? Auger section lengths: 4, 5, 10, and 20 ft ? Weight ranges from about 70 lbs per ft for 12 inch to 120 lbs per ft for 24 inch and 200 lbs per ft for 36 inch

Jan 1, 2005

By Fred C. Drury

Blasting vibrations have been a concern to those using explosives since as early as 1927. Many criteria have been used to correlate vibration levels with damage to structures. After considering many alternatives, peak particle velocity has become the most commonly used criteria.

Jan 1, 1975

Jan 1, 1927

A saturated, metal-free solution of alum can be used as a fiocculant to speed up the sampling procedure during a geochemical survey of stream silts.

Jan 1, 1969

By Michael J. Sapko, Eric S. Weiss, Richard W. Watson

As part of the Bureau of Mines research into the hazards associated with the mining and processing of oil shale, experimental mine tests have been conducted to evaluate preferred combinations of explosives and inerting materials to prevent ignition of oil shale dust and mixtures of oil shale dust and methane.

Jan 1, 1989

BARBOUR, PERCY E., Deputy Supt., (Captain), New York State Troopers; Captain, 22nd Regiment, N. Y. N. G. BARLING, 1i. B., 1st Lieutenant, Engineer Officers' Reserve Corps. CHAPMAN, R. H., Major, Engineer Officers' Reserve Corps. DUNN, THEODORE S., 1st Lieutenant, Engineer Officers' Reserve Corps. DWIGHT; ARTHUR S., Major, Engineer Officers' Reserve Corps. FORBES, CARROLL R., Captain, Engineer Officers' Reserve Corps. GOODSPEED,. G. E., JR., 1st Lieutenant, Engineer Officers' Reserve Corps.

Jan 7, 1917