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Mining at Waihi on the Martha Hill commenced in 1878 and between 1892 and 1953 produced 35 million ounces of bullion from some 13.5 million short tons of ore from 40 named quartz reefs. The general geology of the ore is recorded in detail with differing interpretations by Bell and Fraser (1912) and Morgan (1924). The reefs and stringers have formed by fissure filling and replacement in mainly quartz andesite dacite flows within the Waihi 'Graben'. The host rocks are extensively propylitised with intense alteration forming zones of kaolin adjacent to the main reefs.

Jan 1, 1979

By Narasimhan K. S, Sastri S. R

A typical high silica low grade magnesite from the Salem area of Southern India, was used in studies to develop a suitable flotation system involving commercially inexpensive sodium oleate as the collector together with other reagents which can give a product of the required grade with an acceptable recovery. It was found that the presence of metallic ions such as Cu+, Fe+++ or Ca++ introduced by the addition of their salts, or by their formation with the addition of hydrochloric acid to react with magnesium and calcium carbonate in the me, can act as effective depressants for silica. The addition of 'hydrochloric acid' was found to give best results.

Jan 1, 1980

By Joe Roby

Rolling disc cutters are the business end of hard-rock and mixed-face tunnel boring machines (TBMs). Since their first successful employment on a TBM more than 50 years ago, disc cutter technology has constantly evolved, allowing modern TBMs to excavate very hard and abrasive rock efficiently. Disc cutters have also been employed successfully on earth pressure balance (EPB) and slurry machines, cutting rock under water and ground pressure. The range of materials excavated by machines today is broader, excavation rates are higher and cutter costs are lower than ever before, proving the value of investment in cutter development. Disc cutters are used on a range of tunneling equipment, from pipe jacked slurry micro-TBMs less than 1 m (3.3 ft) in diameter to 15 m (49 ft) in diameter, hard-rock boring TBMs. The geological conditions under which they are employed range from sands and gravels, with several bar of water pressure, to extremely hard, massive rock with UCS up to 420 MPa. Regardless of the type of machine or geology, one thing remains constant: changing worn out cutters is costly. When cutters must be changed in the middle of a tunnel, the contractor incurs the cost of downtime as well as the cost of refurbishing or replacing the cutters. In the case of catastrophic cutter failures, the project can be stopped completely for long periods, and the costs mount up rapidly while tunnel production is at a stand still. Catastrophic cutter failures include the occasion when hard-rock disc cutters are failed in groups (called a ?wipeout? phenomenon) and the operator fails to stop the machine, which results in severe damage to the cutterhead. The cause of this can be either an undetected failed cutter propagating damage to surrounding cutters or operator error in steering. Regardless of the cause, the resulting damage can take days or even weeks to repair. When cutters fail prematurely on EPB or slurry machines in certain geological conditions, it is impossible to evacuate the chamber and, therefore, impossible to get [ ] into the chamber to change the cutters. The solution is frequently an unplanned intervention shaft that must be sunk at great cost. The importance of being able to predict cutter life accurately, and in all geological conditions, cannot be overemphasized. For these reasons, cutters have been developed for specific machine types and sizes, as well as for specific geological operating conditions. Different size cutters are required for different size machines. For example, while 483- and 508-mm (19- and 20-in.) cutters are used on large diameter TBMs, it is impossible to employ cutters so large on a small micro-TBM. Also, the cutter must be designed for the specific geological conditions under which it will be operating. The disc cutter rings required to bore extremely hard rock are the most expensive of cutter rings. However, they provide little advantage in weaker rock formations where less expensive rings will do the job as well. It is important to choose the correct cutter for the machine and the geological conditions in order to get the best balance of cost and risk.

Jan 1, 2009

Up to the end of World War n, flat-back cut and fill stoping with or without square sets was the universal method of ore extraction. Rapid changes in practice occurred during the post-war years; first, ore extraction was fully mechanized; secondly, the stope design for new levels, notably No. 17 Level Zinc Corporation Ltd. and No. 19 Level New Broken Hill Consolidated Ltd., was modified to suit this mechanization; and thirdly, sub-level and shrinkage stopes were developed in orebodies where cut and fill methods would be uneconomical. The following is a brief survey of the changes that have occurred-most of which were inaugurated during the last five years.ROCK DRILLINGDuring 1951 open stoping was investigated in detail. In order to reduce steel handling problems, forged steel onepass detachable bits were introduced, but were soon superseded by the "Swedish method". Investigation showed that when using a bar and arm mounted 3-in. drifter the overall drilling time was approximately 6 min. per ft. compared with 4 min. per ft. using the light jackhammer-airleg combination with 1-in. hex. by 4-in. collared shank tungsten carbide-tipped steel.Although competitive with tipped steels on a cost per foot drilled basis (excluding miner's time), detachable steel bits proved most unsatisfactory for hard drilling conditions.Rapid blunting necessitated frequent bit changes and thus caused lost drilling time. This, together with rapid gauge...

Jan 1, 1957

By Joseph Kuti

Longwall mining is the term used for the underground extraction of a wide and deep panel of coal. Such a panel may be blocked out by one or more entries on either side ("head" and "tail") of a longwall face. If all the entries are pre-driven, the panel extraction is termed longwall retreat mining. With one exception, all the longwall faces in the United States are of this type. (1) prior to the general decline in the rates of production with Continuous Miners, the development of the multiple entries generally kept ahead of the longwall extraction rate. This is no longer the case: longwall extraction rates far exceed the rate of development. In addition to this problem, in newly established mines, the development of a haulage and bleeder system based on multiple entries results in a lead-time of three years or more before longwall mining can be applied. This is one reason why earlier projections and much of the optimism attached to longwall mining as a principal "savior" in the energy crisis should be viewed with some caution.

Jan 1, 1978

IN presenting a'description of milling and treatment methods at the Waihi mine, it is advisable to first traverse a good deal of the past history of the mine, and show the various steps which have led up to present-day practice. The record of the company is one of steady, solid advancement, both in metallurgical and financial results. This is illustrated by the following figures, dating back from 1897...

Jan 1, 1912

By M. Cornelius

Drilled shaft construction through caving soils has historically been an uncertain, risky and costly operation. Uncertain, because the zone of caving may or may not be known, risky because the loss of a shaft is disastrous, and costly because the Contractor, who faces these risks, must include large sums of money in his bid for shaft wall stabilization techniques. This case study will discuss the stabilization techniques that are typically used within the United States, and then present new technologies, born in Europe, that are being utilized in the States by Malcolm Drilling Company today.

Jan 1, 1999

The Black Hills Mineral Atlas briefly summarizes all important data available on the mines and mineral deposits in the Black Hills that have been explored, developed, mined, or located. The purpose of the atlas is threefold; First, from available data the general potentialities of the Black Hills region can be determined, although it is not possible to calculate actual ore reserves; second, it will provide the necessary basic information regarding a given property or commodity for further detailed study; and third, the compilation is a comprehensive directory of Black Hills deposits.

Jan 1, 1955

By William Gleason

"It is the largest mining exhibition in the world that attracts thousands of attendees from around the world to Las Vegas, NV once every four years. Despite the recent struggles in the mining industry, MINExpo International 2016 promises to be as big as ever. In the following pages, Mining Engineering takes a look what some of the more than 1,800 companies plan to showcase during the three-day exhibition.CaterpillarCaterpillar will support MINExpo 2016 with an exhibit showcasing machines, technology, expertise and practical knowledge that miners can apply to help address their cost, productivity and efficiency challenges in today’s mining environment.Caterpillar will once again occupy the largest space at the event and will showcase both surface and underground machines, but the talk at the booth will focus on how Cat technology and know-how combines to help mining operations address and solve the issues that are most important to them. The main stage in the exhibit will feature presentations describing how mining companies, Cat dealers and Caterpillar work together to improve operations.“The challenge for all in the mining industry now is to optimize operations — to drive costs down while creating sustainable businesses that can weather downturns,” said Caterpillar Resource Industries group president Denise Johnson. “We believe that through our expertise and the knowledge of our dealers —combined with innovative technologies and our growing data analysis capabilities — we can help them not only survive, but thrive in these challenging times.” Johnson was selected by the National Mining Association (NMA) to chair MINExpo 2016. “Chairing this show is a great honor, and it’s a testament to Caterpillar’s partnership with this critical industry,” she said. “We’re proud to be a long-time supporter of the NMA, and we are excited to participate in another MINExpo. It’s an opportunity for us all to learn from each other how to increase productivity, control costs and improve overall operations.”Surface mining displays. The surface mining section of the Caterpillar exhibit will showcase the new MD6420C rotary drill. This is autonomy ready and optionally equipped to leverage the safety and productivity benefits of Cat MineStar Terrain. This high-precision drill management system optimizes utilization and improves drilling and blasting operations by accurately guiding the operator and improving precision of hole placement and drilling depth — and the next step is fully autonomous operation, Command for drilling. The third-generation drill incorporates proven Cat components throughout for superior reliability and durability."

Sep 1, 2016

By William H. Schiffbauer

The Bureau of Mines has developed a passive encoder for range knobs, a device that automates the task of obtaining the range settings from devices or instruments to be input to microcomputers. It is easily constructed and installed and will not disrupt the device to which it is being attached. It consists of a custom knob and a small printed circuit board that has light-emitting diodes and magnetic reed switches attached. A ribbon cable connects it to a microcomputer. This encoder eliminates one source of human error in an automated process.

Jan 1, 1983

The point of the anode effect on carbon anodes of dcfincd surface area. during electrolytic decomposition of alumina dissolved in molten fluorides. has been determined from current-voltage curves. The reproducibility and accuracy was found to be better for cell voltage than anode current density. Results have been obtained for the effect of alumina concentration temperature and carbon type. The point of the anode effect was strongly dependent on both the alumina concentration and the carbon type. For high alumina concentrations it has been found that the anode effect approaches reversibility. From these results it is concluded that co-evolution of CO, and CF. occurs prior to the onset of the anode effect. The anode effect results when the CF, content becomes sufficiently high for the melt not to wet the electrode surface and is maintained because of the slow desorption of CF, and the high electrode potential that results.

Jan 1, 1967

The Barmac autogenous crushing mill is one of the most successful new comminution technologies to become available to the mining and industrial minerals industries in this decade.   The Barmac autogenous crushing mill is an innovative Vertical Shaft Impactor which operates in essence like a high intensity dry ore centrifugal pump with the reduction occurring primarily as a result of high velocity rock to rock impact in a fully rock lined crushing chamber.   With applications in a wide range of mining and industrial minerals operations the Barmac autogenous crushing mill presents an opportunity to enhance reduction and liberation whilst providing many cost savings and production increases in new and existing plants.   This paper briefly describes the operation of the Barmac autogenous crushing mill and reviews its benefits.

Jan 1, 1990

By P Meehan, R McAree, Z Guan

Equipment maintenance is 30 - 50 per cent of the operating costs for a typical mining company. While this is substantial, its importance is beyond its significance as a cost heading. Modern mining requires large amounts of investment in capital infrastructure and equipment to produce a product sold at a low unit cost. To stay competitive, such a business has to focus on full realisation of its capital investment, ie sustained production at high levels. Maintenance plays an essential role in achieving this goal. Mining companies typically use a mix of breakdown or corrective maintenance, planned maintenance, and some condition-based maintenance. The share of breakdown maintenance has been coming down through more effective planned maintenance and better condition monitoring tools. Planned or preventive maintenance (PM) is playing an increasingly important role in todayÆs mining maintenance. This is the suite of inspection and repair/replacement actions performed at scheduled time intervals as part of a preplanned activity. The activities are scheduled well in advance and, usually, the current wear-state of the machine is irrelevant. For example, the replacement of a major gear may have been planned 18 months in advance; replacement is carried out when the time comes regardless of the actual condition of the gear. The PM costs are significant and include direct cost of parts and labour as well as the opportunity cost of lost production while the machine is under maintenance. It is important to identify the optimum PM effort because over-maintenance should be avoided as much as under-maintenance. A new concept called severity-based maintenance is introduced in this paper. We have seen that measuring equipment ageing in mining merely by counting the engine hours is a very imprecise way of planning and scheduling maintenance because the damage accumulated in one hour varies enormously from operator to operator and with changing pit conditions. We recommend continuous monitoring of duty on all major equipment. This is feasible without having to fit out the machine with an army of sensors because most of the physical sensors required by dutymeters are already installed and maintained as part of the existing performance monitors. While the investment is modest, the potential benefits are huge and can be grouped under three headings:Immediate benefits will come from providing operators with direct feedback on the effect of their behaviour on machine health and training them to use this feedback to correct their operating style. The equipment can operate closer to the limits of capacity, producing more without unduly sacrificing the availability by monitoring and controlling the severity of the operation, ie the duty on the machine. Longer term benefits accrue from establishing correlations between actual time to failure data and measured equipment duty and using these correlations to optimise maintenance effort as well as planning new equipment purchases and warranty conditions.

Jan 1, 2002

By Tim Peterson

Factors Controlling Stability Stability of slopes in soft rock, waste dumps or soils is governed by three factors: ?Slope configuration ?Groundwater ?Shear strength

Jan 1, 2004

By B. C. Vargas

The Toulon tunnel project is a key component of the Highway corridor on the French Riviera between Marseille and Nice and is a fundamental transportation infrastructure for the region. The first design studies started in the 1960?s. The tunnel project is made of 2 separate tunnels: South and North tunnel. The North tunnel was built between 1992 and 2002 after 10 years of difficult construction (for example, on March 15th, 1996, a collapse of the tunnel in the ?Marchand Area? generated a sink hole in the city Center, causing 20 months delay). The South tunnel alignment runs parallel to the North tunnel at the same depth below Toulon historical downtown (20 to 40m depth with some areas with less than 10m of cover). The Risk management program was studied to be a State of the Art program in urban tunneling construction. The Hydro Geological Context The whole project area is covered with backfills and colluviums of 1 to 4m thick. The Schist, marls and sandstones, randomly distributed along the alignment below the first layer have different characteristics. While the Schist are pretty compact, the marls are fractured. The other layers have very different characteristics, and many faults are located along the alignment, especially in the limestones. The Breccia are heavily decompressed and deformable, as well as the other soils located in the Marchand Area. This 80m long area is where the settlements need to be controlled with an extensive monitoring program. The complete Geological profile is presented in Figure 1. [ ]

Jan 1, 2012

By James H. Owen

Because of price structure, ANFO is normally considered to be the most cost effective explosive used in quarry blasting. Results indicate that bulk smulsion can be more cost effective in applications where hole sizes range up to 6.5 inches in diameter while providing the simplicity of single product loading and storage. This can be accomplished without any fragmentation and/or movement loss usually in patterns which are about twice the size of ANFO patterns, allowing the combined drilling and blasting cost to be less when using bulk emulsions. Examples are presented supporting this concept using actual field results along with some simple calculations which take into account differences in the products such as density, matrix and detonation velocity.

Jan 1, 1998

By Michael Quadagno

Hudson River Pier 86, home of the historic USS Intrepid Aircraft Carrier and the Intrepid Sea-Air-Space Museum, is currently undergoing a $30M reconstruction. This project involves the demolition of the old timber pile supported pier and construction of a new 150 ft wide by 782 ft long concrete pier, built over the footprint of the old piles. The new pier consists of steel pipe piles, precast concrete pile caps, and a composite deck, made up of precast, prestressed concrete planks and cast-in-place concrete topping. This paper focuses on both the structural design and construction of the new pier, with emphasis on the pile foundation. Pier 86 is unique in that it is required to resist the extremely high lateral loads imposed on it by the permanently moored 898 ft long aircraft carrier during severe storms. A total of 360 steel pipe piles support the new pier. These piles, which are 24 in. in diameter and range in length from 58 ft to 175 ft, were driven down to bedrock. The piles, each having 200 ton allowable capacities, work together to resist the significantly large lateral loads exerted on the pier by the ship. The installation of the piles was unique in that all the piles, including the ?super-longs?, were fabricated to-length offsite, delivered to the site via truck and barge, and installed in one piece, eliminating the need for field splicing. The Pier 86 reconstruction will be completed within an extremely aggressive 18 month schedule, from January 2007 through June 2008. The refurbished aircraft carrier Intrepid will return home in September 2008, and the grand re-opening of the pier will be on Veteran?s Day 2008. This paper provides a case history for owners, government agencies, engineers, and construction professionals that will be faced with the challenges of designing and building new piers.

Jan 1, 2008

The ready solubility of gold in dilute aqueous solutions of the cyanides of the alkalies or alkaline earths provides a convenient method for the separation of the precious metal -from the large surplus of associated materia1. The finely ground ore is pulped with a weak solution of cyanide, agitated to dissolve the gold, filtered and washed. The lowgrade filtrate is then clarified and the gold precipitated by some electronegative agent, the most usual being finely divided zinc or zinc dust. The slight precipitate is collectedon some form of filter coated with a filter aid, the filter cake being then known as "gold slime".A typical analysis of this slime is given in Table 1.

Jan 1, 1956

By Daniel Lozada

La unidad de producción polimetálica de Yauliyacu, ubicada en la localidad de Casapalca, Lima, tiene una presa de relaves en el paraje de Chinchan del mismo departamento. Sin embargo, dado que la presa nueva Yauliyacu culminaría su función y que la presa auxiliar Tablachaca no contaba con la suficiente capacidad de almacenaje, Centromin Perú evalúo otras alternativas para la ubicación y construcción de una nueva. De acuerdo al estudio realizado, se encontró que la quebrada de Chinchan era la más adecuada puesto que ofrecía mayor capacidad de producción y se descartó las de Corina y Tablachaca. En este sentido, el presente texto describe las características de la quebrada, el diseño del depósito de Chinchan, su proceso de construcción, la limpieza de fundación, el análisis de la estabilidad física y química, la implementación para mejorar la estabilidad de la presa, la mejora de calidad del aire en la zona del depósito, el programa de inversiones y el plan de cierre del relave.

Sep 13, 2001

By B. Y. Park

This paper develops a series of three-dimensional simulations for the Bayou Choctaw Strategic Petroleum Reserve. The U.S. Department of Energy plans to leach two new caverns and convert of one of the existing caverns within the Bayou Choctaw salt dome to expand its petroleum reserve storage capacity. An existing finite element mesh from previous analyses is modified by adding two caverns and increasing the size of existing Cavern 102. The structural integrity of the three expansion caverns and the interaction between all the caverns in the dome are investigated. The impacts of the expansion on underground creep closure, surface subsidence, infrastructure stability, and well integrity are quantified. The results show that from a structural viewpoint, the locations of the two newly proposed expansion caverns are acceptable, and all three expansion caverns can be safely constructed and operated.

May 1, 2009