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An intensely sheared and mineralized zone occurs in the quartz dolerite greenstone (or younger greenstone) mass on the western limb of the Kalgoorlie syncline. This zone comprises the western part of the Golden Mile and has produced the greater part of the 33,000,000 oz of gold produced to date from the main mining belts. A study of the general geological and structural features suggests that the lode shear system will continue southward on a pitch similar to that of the main syncline. Although payable ore has been found recently further to the south, the expectation of large quantities extending southward from the present mining areas is problematical.INTRODUCTIONUntil the late 1930's the principal mining activities in the western lode system were centred on three major ore-shoots formed on the No. 4, No. 3 and to a lesser extent on the No. 2 lode shears (Fig. 1). With the gradual reduction of grade in depth on these main ore shoots, increasing attention was paid to the "Minor Lode" system of lode shears known to exist in the same area. A large quantity of payable ore was found on these "Minor Lodes" particularly in the central part of the mining area. In recent years more attention has been given to exploration in a southerly direction.ROCK TYPES AND STRUCTURESThe western system occurs on the western flank of a dragfolded, south pitching syncline. The rock succession consists of Black Flag sediments overlying the younger greenstone horizon which overlies the fine grained older greenstone horizon. The axis of the syncline is regarded as a tight infold of the overlying Black Flag sediments. This infold has been faulted and intruded by albite porphyry resulting in the formation of a composite body of slates...

Jan 1, 1964

By Graham Davey

"Ultrafine grinding of minerals has been in wide spread use in the industrial mineral field for over 30 years. Within the last 10 years the metalliferous industry has shown interest in the ability to produce ultrafine particles, as chemical, physio-chemical and physical separation processes have advanced to be able to treat ultrafine metalliferous particles. Also as the primary mineral deposits are depleted, new more difficult deposits must be mined. Existing operations are also looking to maximize economic return from existing deposits, requiring new thinking and technologies.The recent development of industrially proven and cost efficient technologies for ultrafine grinding has opened up another processing option for the treatment of finegrained metalliferous and refractory gold ores. The current commercial designs are variations of stirred mills used in the industrial minerals sector for the past 30 years. For the purposes of this paper ultrafine grinding is considered to be P80 of less than 15 microns.Attrition milling to fine grind sizes presents some challenging issues relating to scale-up including the dearth of information on the quantitative impact of feed and operating conditions, as well as the precise and accurate measurement of particle size distributions. Two examples from recent installations will be analyzed including Thalanga Copper and Century Zinc Mines. Both have diverse grind size targets for the SMD, yet both have realized significant metallurgical gains."

Jan 1, 2002

By Jey K. Jeyapalan

A characteristic common to most tailings dam failures caused by earthquakes or excessive rain storm is that the tailings tend to liquefy and flow for substantial distances as a viscous fluid, with the potential for extensive damage to property and life. Failures of El Cobre, Chile (1965), Mochikoshi, Japan (1978), Aberfan, Wales (19661, Buffalo Creek, West Virginia (1972) are examples of such catastrophic incidents. In these four incidents more than 400 lives were lost, and the loss of property was approximately $200 million. In order to be able to assess the potential for damage in case of such a failure, it is necessary to predict the possible extent of flow slide movement. This paper discusses simple procedures for performing such analyses. Also, in order to illustrate the use of these analysis procedures in tailings dam design, two case histories are analyzed.

Jan 1, 1982

By G. P. Pilling

The use of magnetic ore in the blast furnace is a subject of increasing importance. The end of the deposits of lake ore is in sight, although not imminent, and unless some new field is discovered, the use of magnetites will be an increasing factor in the iron production of the country. Enormous deposits of magnetic ore in the country that have been practically untouched contain ore of sufficient richness and purity to prolong materially our ore supply without extensive importation of foreign ores. Magnetic ores can be divided into three general classes: Fine un-sintered, or raw ore; raw lumpy ore; fine ore that has been sintered. Fine Unsintered Ore Typical analysis and screen test of this class of ore from the Adirondack region is as follows: Per Cent. SCREEN TeST pER Cent. Fe.................... 58.00 Remaining on 4 mesh........... 7.50 SiOz.................. 7.50 Through 4 on 8 mesh........ 13.75 Al,O,................. 1.60 8 on 10 meah........ 3.75 Baseg................. 2.77 10 on 20 mesh........ 22.50 P.................... 1.00 20 on 40 mesh........ 27.50 Mn................... 0.13 40 on 60 mesh........ 2.50 S..................... Trace 60 on 80 mesh........ 10.00 80 on 100 mesh........ 2.50 100 mesh........ 10.00 100.00

Jan 1, 1923

Economic evaluations of mineral projects are based on discounted cash flow analyses, followed by sensitivity and risk analyses. However, the global macroeconomic and political environment in which the mineral industries operate have a profound effect on the viability of individual projects. Since the oil crises of 1974 and 1980, demand patterns for minerals have become much more variable and prices more volatile. Significant changes in the geographical distribution of world mineral supply and demand are underway, and the mix of minerals used is also changing. Social and political factors are as important as economic and technical factors in determining the viability of mineral ventures. Economic evaluation of mineral projects have to be undertaken in a more uncertain and risky environment. They can no longer be reduced to a number crunching exercise.

Jan 1, 1987

By G. P. Pilling

The use of magnetic ore in the blast furnace is a subject of increasing importance. The end of the deposits of lake ore is in sight, although not imminent, and unless some new field is discovered, the use of magnetites will be an increasing factor in the iron production of the country. Enormous deposits of magnetic ore in the country that have been practically untouched contain ore of sufficient richness and purity to prolong materially our ore supply without extensive importation of foreign ores. Magnetic ores can be divided into three general classes: Fine un-sintered, or raw ore; raw lumpy ore; fine ore that has been sintered. Fine Unsintered Ore Typical analysis and screen test of this class of ore from the Adirondack region is as follows: Per Cent. SCREEN TeST pER Cent. Fe.................... 58.00 Remaining on 4 mesh........... 7.50 SiOz.................. 7.50 Through 4 on 8 mesh........ 13.75 Al,O,................. 1.60 8 on 10 meah........ 3.75 Baseg................. 2.77 10 on 20 mesh........ 22.50 P.................... 1.00 20 on 40 mesh........ 27.50 Mn................... 0.13 40 on 60 mesh........ 2.50 S..................... Trace 60 on 80 mesh........ 10.00 80 on 100 mesh........ 2.50 100 mesh........ 10.00 100.00

Jan 1, 1923

Drill and blast excavation in underground mining and. civil engineering projects has grad- ually given ground to mechanical boring of tun- nels, shafts and raises during the past twenty years. The use of.boring equipment must today be considered significant and wide spread al- though comprising only a very small percent of total underground excavation. The encroachment of mechanical boring into the domain of blast- ing has been by slow incremental advances. There have been few, if any major breakthroughs in this development, and none can be foreseen in the next decade. After 1990 it is possible that scientific. development will provide some form of breakthrough in rock breaking, but this is so uncertain that it should have little relevance to planners in the 1980's. A more near term view of the future, con- centrating on the next five to ten years, has lead to the conclusion that significant im- provements will be seen in tunnel borers for poor ground conditions. A universal machine will be developed that converts from a dry hard rock machine to a closed slurry type machine for passing through fault zones with unstable crushed rock and water. Two other machines have been described as alternate designs for tunnelling in squeez- ing ground conditions.

Jan 1, 1981

By K. Collett

Elandsrand started shotcreting back in 1991. This paper will share the experiences of the mine by looking into the past, the present situation and the way Elandsrand plans to approach the future. It looks at the application of drycrete and discusses the factors that led to the introduction of wet fibre reinforced shotcrete. The logistical constraints of getting shotcrete material underground will be solved by the development of an underground batch plant, using run of mine waste rock as an aggregate.

Jan 1, 1998

By Paul M. Godlewski, Gerry Millar, Harvey W. Parker

Recently, over 70 railroad tunnels in the western USA have been enlarged and rehabilitated "live track," utilizing modern excavation and lining methods, in most cases to clear the larger double-stack container cars. This paper presents the general conditions of the tunnels and the technical aspects and costs of the rehabilitation of approximately 40 kilometers of tunnels, which range in length from a few hundred meters to 13 kilometers. Concrete-lined tunnels were rehabilitated by grouting and rock bolting, while unlined or timber-supported tunnels were relined with shotcrete and rock bolts. High output lining methods were required because of limited track time. Enlargement has been accomplished primarily by carving notches out of the concrete linings with a roadheader, or occasionally with saws. Unlined tunnels were enlarged by drill-and-blast or roadheader excavation.

Jan 1, 1991

By A. Mainza, I. Govender, Elbasher M. E. Ahmed

A mechanistic description of axial segregation in rotating drum flows remains an open question. Consequently, optimal mixing of grinding balls and rocks for efficient breakage, maximum production of fines, and slurry transport is seldom achieved. Experimental and numerical studies of granular mixtures in rotating drums identify alternating axial bands that eventually coarsen in the long-term limit. Most models of axial segregation are limited to binary mixtures and cannot always predict the logarithmic coarsening effects observed experimentally. A key missing factor is a robust description of the axial free surface profile that is valid across a wide range of flow regimes. We present a practical model of the axial free surface profile by linking it to readily-derived geometric features of the cross-sectional S-shaped free surface profile. A parametric study shows good agreement with experimental measurements reported in the literature and heuristically valid trends.

May 1, 2021

By Wolfgang Roth

In 1990, a residential area above the North Outfall Sewer (NOS) tunnel constructed in 1924, experienced subsidence. After sewage was diverted into the North Outfall Replacement Sewer (NORS), soil probing from within the tunnel was conducted, soil-improvement options were developed, and a preferred grouting scheme was analyzed by numerical modeling to evaluate the stability of the 80-year+ old tunnel liner under grouting-induced loading conditions. This paper discusses the initial field investigation and the development and analysis of a grouting scheme originally intended to be implemented before relining of the tunnel. The scheme was later modified, and the new liner was installed before the final probing and grouting work was done.

Jan 1, 2008

By B. E. Davis

A technique was devised by the Bureau of Nines to recover coarse (plus 1.7 m) North Carolina phosphate now discarded as waste. Concentration utilizes the difference in particle sphericity between the relatively flat calcite and the rounded phosphate pebbles. Sizing, treatment in a continuous hydraulic classification system, and grinding upgraded a 17.0-pct-P205 reject to 24.5 pct P205 with a phosphate recovery of 63 pct.

Jan 1, 1985

By Pengfu Tan

A thermodynamic model has been developed to predict the distribution behaviors of Cu, Fe, S, O, Pb, Zn, As, and heat balance in a lead blast furnace. The modeling results have been validated by the plant data of a lead smelter in Asia. The model can be used to predict for any set of controllable process parameters such as feed composition, smelting temperature, degree of oxygen enrichment and volume of oxygen-enriched air. The effects of the blast air, industrial oxygen, and coke charge on the distributions of Cu, Fe, S, O, Pb, Zn, As, and heat balance, and on the lead loss in slag have been presented and discussed.

Jan 1, 2005

By Peter A. Witt

Highland Valley Copper is a conventional truck-shovel mining and flotation concentrator operation located some 75 kilometres southwest of Kamloops, B.C. (Figure 1). The ore is located within a porphyry copper deposit and is mined at a rate of 135,000 metric tonnes per day from two separate open pits. The nearby mill produces concentrates containing 375 million pounds of copper and 5 million pounds of molybdenum metal yearly. In the Valley pit, head grades are roughly 0.40% Cu at a 0.23% Cu equivalent cut-off. The Valley pit strip ratio currently sits at 0.55:1 with waste quantities made up of separate rock and unconsolidated overburden units. From the mill, concentrates are trucked to nearby Ashcroft and then hauled by rail to ocean port facilities in Vancouver. The mine employs 950 persons and is planned to operate until 2009. The operation is a partnership between TeckCominco with a 63.9% interest, BHP Billiton holding 33.6%, and others 2.5%. Management is shared by the two principal owners and directed by a management committee.

May 1, 2003

ROESLER MAX-Geology of the Iron-Ore Deposits of the Firmeza District, Oriente Province, Cuba. Discussed by William Kelly, J. T. Singewald, Jr., B. L. Miller, J. D. Irving, L. C. Graton, C. P. Berkey 439 SINGEWALD, J. T., JR., AND MILLER, B. L.-The Manganese Ores of the Lafayette District, Minas Geraes, Brazil. Discussed by L. C. Graton, J. T. Singewald, Jr., F. Lynwood Garrison HARDER, E. C.-Manganese Ores of Russia, India, Brazil, and Chile. Discussed by J. T. Singewald, Jr., E. C. Harder 454 SCHRADER, FRANK C.-Geology and Ore Deposits of Mohave County, Arizona. Discussed by J. C. Anderson McDOWELL, J. SPOTTS-A Study of the Silica Refractories. Discussed by J. W. Richards, H. D. Hibbard, W. F. Rochow, J. B. Umpleby-: 460 PHALEN, W. C.-The Conservation of Phosphate Rock in the United States. Discussed by E. G. Spilsbury 462 NORTON, S., AND LEFEVRE, S.-The Magnetic Concentration of Low-Grade Iron Ores. Discussed by G. C. Foote, J. L. W. Birkinbine, F. L. Nason 462

Jan 4, 1917

A South African gold mining rock-related fatal accident database has been analysed in order to determine rock-related fatality trends in the gold mining industry over the period 1990 to 1998. This analysis was extended further to include some of the individual reefs mined and focused particularly on the Carbon Leader Reef, the Ventersdorp Contact Reef, the Vaal Reef and the Basal Reef. Rock-related accident locations are also presented. A stope rock-related risk is proposed, where the fatality rate in terms of rock-related fatalities per million square metres mined for the gold mining industry as a whole is compared to individual reefs, allowing a stope rock-related risk to be attributed to the individual reef. This comparison is extended further by removing the contribution by the reef being evaluated from the industry data, thereby allowing this reef to be directly compared to the rest of the industry with respect to a stope rock-related risk.

Jan 1, 2001

From the viewpoint of mechanical efficiency, charges should be fully coupled and, upon detonation, should just fail to break the rock in compression. But because mining thrives on its cost-effectiveness rather than its mechan- ical efficiency, the explosive which generates maximum energy per $ should generally be used, even though the mechanical efficiency of this explosive's detonation products may be sub- optimum. Wherever possible, each charge should have a length:diameter ratio of about 20 or more and should shoot to a concavely biplanar free face that is both parallel and reasonably close to the blasthole. Success in obtaining parallel effective faces often demands the drilling of angled blastholes and, hence, will require intensified research and development efforts by drilling manufacturers, especially where hard strong rocks are encountered. Blastholes should be drilled on equilateral triangular grids and fired in a Vl or shallower V-type sequence using inter-row delays which ensure that good pro- gressive relief of burden is achieved. The conventional method of calculating Se/Be values (on the basis of planar effective faces) is often invalid.

Jan 1, 1986

Tapira Mine (Tapira, MG, Brazil) is the largest phosphate ore and concentrate producer in Brazil. The mine is an open pit, which until recently operated with a large equipment fleet and now uses a smaller fleet operated by contractors. The annual production reaches 17 Mt of ore plus 14 Mt of waste at a stripping ratio of 0.82. Defining the geological boundaries and forecasting the annual production can be a difficult task if not performed on a reliable model. The geological model has been totally reviewed as well as the estimation process. Ordinary Kriging has been used to build the new block model with P2O5 and contaminant grades. After estimation, block model validation and classification criteria definition to assess resources and reserves, the result is given by the life-of-mine plan is defined after pit optimisation and design. The Lerchs-Grossmann algorithm implemented in the NPV Scheduler was used to define the long-term production targets based on the main parameters P2O5 and the contaminants that are just important to the beneficiation process.

May 1, 2010

In the course of work being carried out in the Lubricants and Bearings Section of the Council lor Scientific and Industrial Research on the production of copper4ead 'bearings for 'use in aircraft, it has been found necessary to develop special metallographic methods. For proper control of the production of steel-backed copper-lead bearings it is necessary to adhere to rigidly controlled conditions, and it is essential that a method of examination be adopted which will readily detect actual defects or any variations in quality. Some defects can be observed with the naked eye, whilst others are detected by radiographic examination. This latter method is invaluable as a rapid, reliable test in the production of aircraft bearings, but it is necessary to observe the structure of the alloys under the microscope, both to be able to interpret the radiograph correctly and to determine what has occurred to the metal during and after solidification. The use of a sound metallographic technique is'particularly important in developmental work and research connected with these bearings.Polishing TechniqueCopper and lead are practically immiscible in the solid state, but whilst they are miscible only in certain limited proportions in the liquid state; consequently "alloys" of copper and lead consist of a mixture of the constituent metals. The metallographic difficulties are obvious. Copper is a relatively tough metal, although it readily scratches, whilst lead is extremely soft and easily deformed. It wouId be expected if any normal polishing technique were applied that the lead would be readily torn out of the surface being prepared, and, in addition, that the lead would tarnish very easily.Grange(2) has described a method by which these difficulties can be overcome. The method involves an etch-polish procedure using "chrome regia" as an etchant for the copper. The chrome regia was a solution of chromium trioxide and hydrochloric acid in water. This type of etchant has been adopted, but it was found necessary to make certain changes.The method now adopted in this laboratory is as follows: The specimen (which is usually mounted in bakelite) is wet ground in a series of successively finer Hydro-Durexsil emery papers down to 60.0· grit paper.The specimen is then etched in the chrome regis, etchant (the composition of this etchant will pe discussed later) for approximately five seconds.Most efficient etching is obtained by swabbing the surface of the specimen...

Jan 1, 1944

By D. W. Fuerstenau

In 1940 Schuhmann1 showed that the size distribution of a comminuted material can be expressed by the following empirical relationship: y = 100 (|f [i] where y is the cumulative percentage of material finer than size x, k is a size modulus, and a is a distribution modulus which is constant for a given material and machine. During the past few years, considerable emphasis has been given to the investigation of the extent of size reduction resulting from the expenditure of mechanical energy in crushing and grinding. Recently Schuhmann' presented a derivation of the energy-size reduction relationship by postulating that comminution in a device such as a ball mill can be considered to be the summation of many single comminution events, each of which yields a size distribution of particles following the Schuhmann size distribution equation. By grinding

Jan 1, 1961