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By C. T. Thompson

"Rotary percussion" implies two types of energy, rotary and percussion. Into these categories fall rock' drills of varying sizes. The larger ones drill above 6" diameter holes; the medium size, 2 3/4" to 4 1/2" holes; and the smallest, 1 1/4" to 2" holes. Essentially, the larger holes are drilled with doom-the-hole drills using tri-cone bits. Percussion energy evolves from the drill piston and rotation power from the rotary table or overhead drive, using drill collars or pull down mechanism to preload the bit.

Jan 1, 1963

By Joe Sr Strobbe

In 1933 the Cobre Mining Company re-opened the 32-year-old UV Industry Mine, which is located in a scenic canyon near Silver City, New Mexico. The site location is shown in Figure 1. Current mineral extractions are copper and magnetite; both extractions similar to those mined many years ago. Copper is extracted from chalcopyrite imbedded in the host rock of massive limestone deposits and magnetite, an iron ore, is a by-product of the same extraction process.

Jan 1, 1998

By Walter Weeks

THE process of cooling air by allowing it to expand and do work in an engine is well known, but the theory of obtaining cold air by free expansion without the aid of an engine operating with cutoff has been little discussed. CASE I If compressed air is allowed to expand to the atmospheric pressure through an orifice in an air line that is supplied by a running compressor, no cooling results except the negligible one due to the Joule-Thompson effect, which will not be considered in this discussion. The effect of moisture will also be neglected.

Jan 1, 1937

By Richard H. Ross

A broad definition of' "Mill Design" might cover everything from the first tentative choice of general process to the final structural details for construction. The first phases are mainly concerned with metallurgy and economics and the final stages with the mechanics of putting the selected equipment together into an integrated plant. It is the purpose of this article to discuss only data, derived from laboratory testing, that contributes directly to design of the milling plant itself, and only the plant design phases that are influenced by laboratory testing. Most ore beneficiation testing is devoted to determining recoveries, grades of products, elimination of impurities, reagent and supply requirements, etc. having little to do with physical plant design although these factors are of prime importance in the evaluation of a mining project.

Jan 3, 1964

By D. G. Millette, A. J. S. (Sam) Spearing

The design of a cost effective backfill system involves many aspects and various inputs from different engineering disciplines. Backfilling is a very significant mining cost and efforts need to be made in the design stage to maximise efficiency and flexibility whilst minimising costs. The aspects that need to be considered include the following: Required fill performance underground Peak and average fill tonnage requirements Backfill scheduling in the mining cycle Material selection, testing and preliminary costing Plant design and storage needs Infrastructure requirements Implications on surface waste/tailings disposal and costs Total backfill costs In order to produce a cost effective and efficient backfill operation, a multi-disciplinary project team is required that should include the following skills and functions: Mine Planning Rock Engineering Metallurgy Mechanical Engineering Environmental Health and Safety Tailings Disposal/Waste Management This paper discusses the above and indicates important aspects that should be considered.

Jan 1, 2001

By Warren E. Morrison

The expansion of the United States economy in the postwar period has had a tremendous impact on the demand for energy. Not only has total energy consumption increased at an unprecedented rate, but there have been major shifts in the composition or mix of energy resources within the end-use sectors. Because of the numerous interrelationships between substitutable energy resources and their markets, the energy economy can only be analyzed in terms of the trends of its component parts. This problem takes on additional complexity when attempting to chart the nation's future energy requirements. Total energy consumption can be forecast with reasonable accuracy for periods up to 15 years by relating this to projections of economic indicators. However, forecasting the component parts of the energy economy constitutes a dilemma in that the sum of the projected parts frequently exceeds predictions for total energy. Areas of uncertainty in energy forecasting tend to mount rapidly when proceeding from total energy to the consideration of specific energy resources consumed as fuel, power, or raw materials.

Jan 1, 1965

By P Cleary, G K. Robinson, J Hilton, P Wilson

Concern has been expressed that Vezins can be biased when used for sampling fine materials if the cutter speed is as high as the 0.6 m/s which is often used. Using modelling techniques that consider airflow as well as particles, we have endeavoured to investigate sampling bias as a function of the size of fine particles, cutter aperture, cutter speed, shape of cutter blades, and the size of the gap between the inlet pipe and the cutter blades. Using crude estimates of the rate of airflow and a simple model of a single particle moving through air led to an approximate rule that bias will not occur due to mechanisms related to airflow for particles larger than about 200 microns; and bias will always occur for particles smaller than about 40 microns. For particles between these size limits, the extent of bias depends on particle density, cutter speed and cutter geometry as well as particle size.CITATION:Robinson, G K, Wilson, P, Hilton, J and Cleary, P, 2012. Avoiding bias when using vezins for sampling dusty materials, in Proceedings Sampling 2012 , pp 109-114 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 21, 2012

This paper presents the results of studying the influence of catastrophic failures arising in mines, on the behaviour of mine ventilation systems. It is very important to take account of this influence for the stable operation of the system and to ensure mine safety when mining underground coal and ore deposits.

Jan 1, 2003

By John W. Fredland

Conducting mining operations under a body of Water can create hazardous conditions for miners. The potential for a sudden inrush must be considered and abnormal ground control conditions can be encountered. This paper synopsizes the factors which mine operators should take into account when evaluating whether an inrush may occur. It addresses the applicable Federal regulations and discusses some items which coal operators should consider in applying for a permit, Through collecting and analyzing the pertinent information, the likelihood of encountering problems can be judged. Through proper mine planning, the potential for creating hazardous conditions can be mitigated.

Jan 1, 1982

Hoses provide a variety of critical functions in nearly every mining operation. Care must be taken when selecting, installing, and maintaining hoses to insure maximum hose life. This article provides some tips on selecting, installing, and maintaining hoses, and gives some background on hose construction and safety. In the mining industry, hoses are used for everything from hydraulic systems that power drills and hammers, to suction systems that carry away dust and debris. Hoses are used on such a large scale that a detailed discussion of specific applications would require many volumes. Dayco Corp. has, however, provided these basic and brief guidelines on how to select and maintain hoses for mining applications. Hose Construction Industrial hoses are classified as much by construction as they are by application. So, it is a good idea to start any discussion of hoses with a description of their basic construction. There are four basic components to hoses: the tube, reinforcement, cover, and couplings. The tube is the inner core or lining, and is usually made of smooth rubber or plastic. Rubber or plastic composition is scientifically determined to be compatible with the materials passing through it, such as fluids, chemicals, gases, or substances. Other considerations in compounding rubber or plastic for the tube are temperature ranges and stresses. In practice, the required compound can be precisely chosen from various charts listing them according to application. There are, however, applications where the compounding of tube rubber or plastic must be customized. The reinforcement hose layer immediately surrounds the tube. As its name implies, this layer gives the hose strength and provides protection for the tube component. Reinforcement must be able to contain the inner forces-pressure and shock-transmitted through the tube, and such external forces as twisting, bending, and crushing. So it is usually made of high tensile strength cord, fabric, or wire that is wrapped, wound, or braided around the tube. The cover is the outermost layer, so it may encounter oils, acids, water, dust, abrasion, and other potentially damaging influences depending, of course, on the application. An appropriate cover material must be selected, usually a rubber compound. Couplings, even though they are a hose attachment, are as vital as any other component and should be considered part of the hose. Couplings are usually made of carbon steel or malleable iron; however, bronze or stainless steel might be used if corrosive chemicals are involved and brass or aluminum might be used for flammable fluids. A coupling is usually in two parts: an insert that fits into the hose bore and contains the threaded male, female, or other type of connection, and the ferrule or collar that fits over the hose and secures the coupling in place. There are, however, some one-part couplings that fit securely into the hose without a ferrule. These are usually limited to low pressure applications and are secured to the hose by clamps or metal bands. Some fittings can also be permanently "built-in" as the hose is made. Couplings can be classified as reusable or permanent. The reusables can be removed when the old hose expires and used again on a new hose. The permanent types are crimped or swaged on at the factory or in the field (using special equipment) and must be discarded with the hose. Although couplings are most commonly thought of as having threaded fittings, there is another type called "quick connect." These either have a crow-foot or jaw-type design that permits a fast, "snap" connection. This can

Jan 6, 1982

By N. Gharib, F. Hassani, P. Nekoovaght

"Novel rock breakage techniques are becoming more viable and attractive to industry. Microwave energy, as a thermal energy capable of inducing micro cracks through differential heating (therefore expansion) is a technology gaining considerable attention in mineral processing and ore comminution applications. Recently, the use of microwave radiation has been evaluated as a possible avenue for terrestrial and extra-terrestrial drilling applications as well as full face tunneling or rock breaking machines. As part of an overall research on use of microwave in rock breaking systems, the influence of microwave energy on the mechanical properties of common hard rock types as basalt has been investigated. The results revealed that microwave energy irradiation imposes micro and macro cracks to the surface of the rock being irradiated. In explosive free tunneling applications using TBM, jointed and cracked surface of rock eases the cutting process and increases penetration rate. The experimental setups have been simulated with the help of a multi-physics numerical modeling and the results have been compared with practical experiment. The wave propagation of microwave has been simulated and the distances where the power intensity is higher are identified. Experimental and simulation results underlined the potential impact of the use of microwave energy in underground or surface excavation applications such as mining and tunneling. This will also contribute economically when mine-to-mill operation is fully considered to improve the efficiency of rock crusher stages. INTRODUCTIONDuring hard rock breakage (i.e., separation of a piece of a rock from its parent deposit) in mining and civil applications, the performance of mechanical equipment such as tunnel boring machines (TBMs) is limited by high levels of bit wear and maintenance. Preweakening natural rock prior to breaking it by machine is one approach to lower bit wear and maintenance costs. Some preweakening methods apply heat directly or indirectly. For example, flame torch-assisted TBMs (Lauriello et al., 1974; Resource Technology, 1984) have been deemed economical in terms of equipment, but their feasibility is limited by high fuel consumption. Microwave energy could offer several advantages over the flame torch method: it does not produce emissions or increase fuel consumption (electricity source is available on the machine), and is easy to control (quick power on and off)."

Jan 1, 2015

By O. Mejia

"As study was undertaken to investigate the relationship between mill liner wear and grinding energy efficiency and to assess the opportunity to control mill speed to improve energy performance as mill liner wears. The study involved analysis of plant operating data and liner wear profiles over time. The operating work index was found to be an effective tool to identify the decrease of grinding efficiency along the liner service. The plant data show that the mill grinding efficiency as determined by monitoring the operating work index, and throughput decreases as liner wears. However, efficiency and throughput can be maintained by either changing the liner more frequently or by increasing the mill speed. Two scenarios for increasing mill throughput were analyzed. The first one involves changing the liner before the efficiency drops and the second one requires increasing the mill speed from 75% to 79%. Both scenarios show financial benefits that can be used in mill operations.INTRODUCTION The analysis of the mill power draw is used in this study as a key parameter for comparing mill liner profile and its effect on mill performance. Current technology and simulation software used in the mining industry do not factor in the impact of liner wear profiles in grinding efficiency and mill throughput (Toor, 2013). To address this gap, this study provides an analysis of key factors affecting mill throughput and grinding efficiency: mill speed, ball loading, and liner profiles. Several years of plant mill operating data, published research papers, and MillTraj® simulation results are used to demonstrate that face angles impact grinding efficiency and throughput and that mill speed can be used to overcome this problem. Moreover, the liner profile wear analyses clarify a mismatch between actual and estimated power draw calculations."

Jan 1, 2019

By J. Fournier, D. Fortin, F. Robichaud

Since milling began in 1988, the Laronde mill has been expanded several times, the most recent, increasing the milling rate from 5 000 to 7 000 mtpd. Laronde uses SAG/ball mill grinding followed by copper and zinc flotation circuits. A cyanidation/Merrill-Crowe process recovers the remaining gold and silver in the flotation tails in order to cope with high silver/gold ratio associated with the discovery of the Penna shaft. Since the commissioning of the Merrill-Crowe refinery in 2000, several modification and expansion projects were performed to reduce health and safety hazards. Remarkably, several of these improvements have contributed at increasing productivity and Net Smelter Return of the refinery while reducing worker's injuries. In 2004, the refinery was audited to evaluate and quantify the circuit performance. Metallurgical and mechanical operating conditions of the refinery are now understood and areas for further improvements are well defined. This paper describes some of the factors that have contributed to this improvement and describes how ergonomics and recovery can further be improved.

Jan 1, 2005

By Thomas F. Nederpel

The production of zinc and zinc-aluminum coated strip can be reasonably accomplished on a single operating unit. However, if the hot dip coating line is equip d with only one mo 7 ten metal holding furnace, it is necessary to transfer liquid metal of different chemistries and reintroduce virgin material to obtain the 18" necessary balance of elements in the bath. Dofasco produces Galvanize and Galvalume on a coating line with a sin le liquid metal furnace and has developed not only an efficient liquid metal trans& system but also an effective means of reutilizing the zinc-aluminum mixtures without detrimental quality affects.

Jan 1, 1992

By Jim Finley, Adam Bedell, Eric Schrader

The CSO 52 Storage Tunnel and Pump Station project consists of 4,700 ft of hard rock tunnel, 2 intakes, and a 4 MGD wet pit pump station. During the geotechnical investigation, it was determined that the host geology contained abundant suldes. The purpose of this paper is to detail the investigation and subsequent determination that acid producing materials would affect the project during construction as well as long-term exposure of tunnel lining and permanent components during the operational life cycle of the tunnel and pump station. Details regarding the interaction between tunnel components and the acid producing material are also provided.

Jun 23, 2024

By U Dzharlkaganov, B Bekmurzayevand M

The principle conception is presented of timely planning of winning operations in complex-structural blocks and faces in week-24-hourly regime. For adequate description of complex interconnections of open cast operation in space and in time and solving of optimisation problems in timely regime it is necessary using of complex logical and calculation procedures.

Jan 1, 2003

By Phillips H. R

The action of free rolling disc cutters is well understood, relationships between disc geometry and performance having been established both in the laboratory and under field conditions. However, under severe operational conditions a malfunction of the disc bearing assembly is likely to produce a definite change of cutting action. Collapsed or siezed bearings can even prevent the disc from rolling and thereby create what is equivalent to a drag pick. This paper describes a programme of laboratory experiments using deliberately stalled discs. Their performance under such conditions is contrasted with that for a free rolling disc and also with a drag pick having a ridged front developing into a negative radiused back clearance angle. In conclusion an assessment is made of the influence stalled discs can have on the torque and thrust requirements for a tunnel boring machine.

Jan 1, 1981

By R. A. Jankowski, J. D. Potts

Four underground respirable dust surveys were conducted to determine factors affecting belt entry dust levels and how using belt air to ventilate work areas affected dust exposures. Belt entry dust levels on the surveyed longwall and continuous miner section averaged 0.59 and 0.26 mg/m3, respectively. The stageloader/crusher contributed an additional 0.5 to 0.9 mg/m3 of dust to belt air, while the feederbreaker contributed 0 to 0.2 mg/m3 of dust. A 1000 ft (305 m) increase in belt entry length or a 200 to 500 tons/shift (181,000 to 454,000 kg/shift) increase in production resulted in roughly a 0.1 mg/m3 increase in dust. Using the belt entry as an intake entry on the continuous miner section appeared to reduce dust levels by 0.1 to 0.3 mg/m3 during cutting. Belt air was not used to ventilate the face on the longwall section.

Jan 1, 1992

By D. Allan Coutts

Demonstration projects using hydrogen as a fuel are becoming very common. Often these projects rely on project-specific risk evaluations to support project safety decisions. This is necessary because regulations, codes, and standards (hereafter referred to as standards) are just being developed. This paper will review some of the approaches being used in these evolving standards, and techniques which demonstration projects can implement to bridge the gap between current requirements and stakeholder desires. Many of the evolving standards for hydrogen-fuel use performance-based language, which establishes minimum performance and safety objectives, as compared with prescriptive-based language that prescribes specific design solutions. This is being done for several reasons including: (1) concern that establishing specific design solutions too early will stifle invention, (2) sparse performance data necessary to support selection of design approaches, and (3) a risk-adverse public which is unwilling to accept losses that were incurred in developing previous prescriptive design standards. The evolving standards often contain words such as: ?The manufacturer shall implement the measures and provide the information necessary to minimize the risk of endangering a person?s safety or health.? This typically implies that the manufacturer or project manager must produce and document an acceptable level of risk. If accomplished using comprehensive and systematic process the demonstration project risk assessment can ease the transition to widespread commercialization. An approach to adequately evaluate and document the safety risk will be presented.

May 1, 2007

Construction workers may be exposed to hazardous dust containing crystalline silica during site preparation when drilling systems are used. The National Institute for Occupational Safety and Health (NIOSH) found that drill dust could be decreased by using wet or dry dust reduction engineering controls, enclosed cabs, and implementing a dust control program.

Jan 1, 2009